Review on Low-Temperature Electrolytes for Lithium-Ion and Lithium Metal Batteries

Using the same salt LiPF6, an acetonitrile-based electrolyte has an ionic conductivity more than twice the value of an EC-DMC-based electrolyte at room temperature.

“Using the same salt LiPF 6 , the AN-based electrolyte has an ionic conductivity more than twice the value of the EC-DMC-based electrolyte at RT [52].”

• cites [52] Cho, Y.G., Kim, Y.S., Sung, D.G., et al.: Nitrile-assistant eutectic electrolytes for cryogenic operation of lithium ion batteries at fast charges and discharges. Energy Environ. Sci. 7, 1737–1743 (2014). https://doi.org/10.1039/C3EE43029D sourceDisputed

  Section 3.1 (page not indicated in our copy) reports room-temperature ionic conductivities of 20.5 mS cm⁻¹ for the acetonitrile-containing electrolyte and 11.33 mS cm⁻¹ for the EC–DMC control. Both used 1 M LiPF6, but 20.5 is about 1.81 times 11.33, not more than twice. (LLM, conf=0.90)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured

Elemental sulfur and allyl disulfide were reported to have the capability to reduce SEI impedance, which can effectively improve low-temperature battery performance.

“Furthermore, in addition to the sulfur-containing additives mentioned above, elemental sulfur and allyl disulfide were also reported to have the capability to reduce SEI impedance as well, which can effectively improve LT battery performance [116,117].”

• cites [116] Jurng, S., Kim, H.S., Lee, J.G., et al.: Low-temperature characteristics and film-forming mechanism of elemental sulfur additive on graphite negative electrode. J. Electrochem. Soc. 163, A223–A228 (2015). https://doi.org/10.1149/2.0421602jes sourceDisputed

  The Results and Discussion report better low-temperature performance with elemental sulfur, but attribute it to lower charge-transfer resistance, not lower SEI resistance. They state that SEI resistance was higher for the sulfur-added electrode. The cited paper studies elemental sulfur, not allyl disulfide. (LLM, conf=0.88)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured
• cites [117] Jurng, S., Park, S., Yoon, T., et al.: Low-temperature performance improvement of graphite electrode by allyl sulfide additive and its film-forming mechanism. J. Electrochem. Soc. 163, A1798–A1804 (2016). https://doi.org/10.1149/2.0051609jes sourcePartly supported

  The Abstract reports improved low-temperature graphite performance with elemental sulfur, and Results and Discussion reports a comparable improvement with allyl disulfide. Neither passage establishes that these two additives reduce SEI impedance. The paper attributes its measured impedance benefit for allyl sulfide to lower charge-transfer resistance, a different quantity (Results and Discussion, Table I; page numbers unavailable). (LLM, conf=0.88)

  Experimental — accuracy not yet measured

High oxidation stability of the methyl propionate-based electrolyte enabled stable graphite||graphite cycling with an upper voltage cutoff at 5.2 V for storage of PF6- anion in graphite at the cathode side.

“Meanwhile, high oxidation stability of this electrolyte enabled stable graphite||graphite cycling with the upper voltage cutoff at 5.2 V for the storage of PF 6 -anion in graphite at the cathode side.”

• cites [43] Holoubek, J., Yin, Y.J., Li, M.Q., et al.: Exploiting mechanistic solvation kinetics for dual-graphite batteries with high power output at extremely low temperature. Angewandte Chemie Int. Ed. 58, 18892–18897 (2019). https://doi.org/10.1002/anie.201912167 sourcePartly supported

  The Accepted Manuscript reports high oxidative stability for the MP-based electrolyte containing 10% FEC. The Angewandte Chemie International Edition section reports stable graphite||graphite full-cell cycling and PF6− storage in graphite at approximately 4.6–5.2 V versus Li/Li+. It does not identify 5.2 V as the full cell’s upper voltage cutoff; that number describes the positive electrode’s potential versus Li/Li+. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

Propylene carbonate cannot be used in graphite-anode-containing battery systems as the major or single solvent due to solvent co-intercalation and exfoliation of graphite anodes.

“However, it could not be used in graphite anode contained battery systems as the major/single solvent due to the solvent co-intercalation and exfoliation of the graphite anodes [30,31].”

• cites [30] Wang, L.N., Menakath, A., Han, F.D., et al.: Identifying the components of the solid-electrolyte interphase in Li-ion batteries. Nat. Chem. 11, 789–796 (2019). https://doi.org/10.1038/s41557-019-0304-z sourceCould not verify

  Section 1.4 describes graphite-electrode tests using DMC and EC electrolytes, but does not address propylene carbonate. Searches for propylene carbonate, co-intercalation, and exfoliation found no passage supporting the claimed restriction or its cause. Page numbers were not available in the indexed passages. (LLM, conf=0.74)

  Experimental — accuracy not yet measured
• cites [31] Xing, L.D., Zheng, X.W., Schroeder, M., et al.: Deciphering the ethylene carbonate-propylene carbonate mystery in Li-ion batteries. Acc. Chem. Res. 51, 282–289 (2018). https://doi.org/10.1021/acs.accounts.7b00474 sourceNot checked — no full text of the source

A graphite||graphite dual-ion battery retained 93.1% and 84.4% of its room-temperature capacity at -40 and -60 °C, respectively.

“As a result, this graphite||graphite dual-ion battery (DIB) retained 93.1% and 84.4% of its RT capacity at -40 and -60 °C, respectively (Fig. 6b).”

• cites [43] Holoubek, J., Yin, Y.J., Li, M.Q., et al.: Exploiting mechanistic solvation kinetics for dual-graphite batteries with high power output at extremely low temperature. Angewandte Chemie Int. Ed. 58, 18892–18897 (2019). https://doi.org/10.1002/anie.201912167 sourceSupported

At high charge rates, low lithium-ion transference number means Li+ transport in the electrolyte cannot catch up with Li+ entering the electrode, causing a steep Li+ concentration profile at the interphase that limits lithium-ion battery performance.

“This means at high charge rates the speed of Li + transport in the electrolyte cannot catch up with the Li + entering the electrode, resulting in a steep Li + concentration profile at the interphase limiting the LIB performance [7,8].”

• cites [7] Fong, K.D., Self, J., Diederichsen, K.M., et al.: Ion transport and the true transference number in nonaqueous polyelectrolyte solutions for lithium ion batteries. ACS Cent. Sci. 5, 1250–1260 (2019). https://doi.org/10.1021/acscentsci.9b00406 sourcePartly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites [8] Piao, N., Gao, X.N., Yang, H.C., et al.: Challenges and development of lithium-ion batteries for low temperature environments. eTransportation 11, 100145 (2022). https://doi.org/10.1016/j.etran.2021.100145 sourceNot checked — no full text of the source

A stable interphase formed by fluoroethylene carbonate combined with high bulk electrolyte conductivity contributed by methyl propionate enabled greatly improved performance, delivering over 60% room-temperature capacity at -60 °C and 1 C rate.

“The stable interphase formed by FEC combined with high bulk electrolyte conductivity contributed by MP enabled greatly improved performance, delivering over 60% RT capacity at -60 °C and 1 C rate (Fig. 6a).”

• cites [43] Holoubek, J., Yin, Y.J., Li, M.Q., et al.: Exploiting mechanistic solvation kinetics for dual-graphite batteries with high power output at extremely low temperature. Angewandte Chemie Int. Ed. 58, 18892–18897 (2019). https://doi.org/10.1002/anie.201912167 sourceSupported

The energy density and power density of lithium-ion batteries at -40 °C retain only a very small percentage of their room-temperature values.

“Moreover, the energy density and power density of LIBs at -40 °C can only retain a very small percentage of their values at RT, respectively [4].”

• cites [4] Nagasubramanian, G.: Electrical characteristics of 18 650 Li-ion cells at low temperatures. J. Appl. Electrochem. 31, 99–104 (2001). https://doi.org/10.1023/A:1004113825283 sourceSupported

The melting point of a mixed carbonate solvent is related to its composition, the melting point of each component, and their relative content.

“They suggested that the melting point of the mixed solvent is related to the composition, the melting point of each component, and the relative content.”

• cites [18] Ding, M.S.: Liquid-solid phase diagrams of ternary and quaternary organic carbonates. J. Electrochem. Soc. 151, A731 (2004). https://doi.org/10.1149/1.1690782 sourceSupported

An NMC111-graphite pouch cell in a methyl propionate-based electrolyte demonstrated stable charge and discharge performance at -20 and -40 °C.

“Chen's group [44] further demonstrated stable charge and discharge performance of NMC111-graphite pouch cell in MP-based electrolyte at the subzero temperatures of -20 and -40 °C.”

• cites [44] Cho, Y.G., Li, M.Q., Holoubek, J., et al.: Enabling the low-temperature cycling of NMC||graphite pouch cells with an ester-based electrolyte. ACS Energy Lett. 6, 2016–2023 (2021). https://doi.org/10.1021/acsenergylett.1c00484 sourceSupported

Electrolytes using ethyl methyl carbonate as the single solvent can work on graphite anodes without ethylene carbonate when LiAsF6 salt is used.

“The electrolytes using EMC as the single solvent can even work on graphite anodes without EC when LiAsF 6 salt was used [24].”

• cites [24] Ein-Eli, Y., Thomas, S.R., Koch, V., et al.: Ethylmethylcarbonate, a promising solvent for Li-ion rechargeable batteries. J. Electrochem. Soc. 143, L273–L277 (1996). https://doi.org/10.1149/1.1837293 sourceSupported

A methyl propyl carbonate electrolyte can enable reversible lithium intercalation into the graphite anode.

“MPC electrolyte could enable reversible lithium intercalation into the graphite anode.”

• cites [28] Ein-Eli, Y., McDevitt, S.F., Aurbach, D., et al.: Methyl propyl carbonate: a promising single solvent for Li-ion battery electrolytes. J. Electrochem. Soc. 144, L180–L184 (1997). https://doi.org/10.1149/1.1837792 sourceSupported

Ethyl methyl carbonate can form a much stabler solid electrolyte interphase on graphite than dimethyl carbonate.

“They showed that EMC can form much stabler SEI on graphite than DMC.”

• cites [23] Ein-Eli, Y., McDevitt, S.F., Laura, R.: The superiority of asymmetric alkyl methyl carbonates. J. Electrochem. Soc. 145, L1–L3 (1998). https://doi.org/10.1149/1.1838196 sourceSupported

Li+(DEE)1.8 complexes possessed a much lower binding energy of -280 kJ mol-1 than Li+(DME)2.3 (-414 kJ mol-1) formed in 1 M LiFSI in DOL-DME electrolytes.

“Meanwhile, the Li + (DEE) 1.8 complexes possessed a much lower binding energy of -280 kJ mol -1 than that of Li + (DME) 2.3 (-414 kJ mol -1 ) formed in 1 M LiFSI in DOL-DME electrolytes shown in Fig. 8a.”

• cites [57] Holoubek, J., Liu, H.D., Wu, Z.H., et al.: Tailoring electrolyte solvation for Li metal batteries cycled at ultra-low temperature. Nat. Energy (2021). https://doi.org/10.1038/s41560-021-00783-z sourceSupported

DEE electrolytes presented characteristic contact-ion pairs with 1.8 DEE oxygens and 2.0 FSI- oxygens per Li+.

“Different from typical solvent-separated ion pair (SSIP) solvation structure, DEE electrolytes presented characteristic CIPs with 1.8 DEE oxygens and 2.0 FSI -oxygens per Li + .”

• cites [57] Holoubek, J., Liu, H.D., Wu, Z.H., et al.: Tailoring electrolyte solvation for Li metal batteries cycled at ultra-low temperature. Nat. Energy (2021). https://doi.org/10.1038/s41560-021-00783-z sourceSupported

When electrolytes containing high concentrations of LiTFSI or LiFSI are used in Li metal anode cells, they can form salt anion-derived SEI with a LiF-rich component that is beneficial for anode protection and electrochemical performance.

“When the electrolytes containing high concentration of these salts are used in Li metal anode cells, they can form salt anion-derived SEI with a LiF-rich component which is beneficial for anode protection and electrochemical performance [104].”

• cites [104] Qian, J.F., Henderson, W.A., Xu, W., et al.: High rate and stable cycling of lithium metal anode. Nat. Commun. 6, 6362 (2015). https://doi.org/10.1038/ncomms7362 sourcePartly supported

  The Results section (“Formation of a stable SEI layer”; page not available) reports that a protective SEI forms with 4 M LiFSI-DME and that increasing fluoride content during cycling may result from anion degradation. It does not identify the SEI as LiF-rich or establish the same SEI mechanism for highly concentrated LiTFSI in Li-metal cells; its discussion of concentrated LiTFSI concerns Li|graphite cells. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

Introducing nitriles with varying alkyl chain lengths and low melting points into EC or EC-DMC-based electrolyte lowers the freezing point of solvent mixtures.

“Recently, Cho et al. [52] introduced nitriles with varying length of alkyl chains and low melting points into EC or EC-DMC-based electrolyte to lower the freezing point of solvent mixtures.”

• cites [52] Cho, Y.G., Kim, Y.S., Sung, D.G., et al.: Nitrile-assistant eutectic electrolytes for cryogenic operation of lithium ion batteries at fast charges and discharges. Energy Environ. Sci. 7, 1737–1743 (2014). https://doi.org/10.1039/C3EE43029D sourceSupported

In all electrolyte systems studied by Cho, 2% fluoroethylene carbonate was used as a solid electrolyte interphase additive to relieve the graphite incompatibility issue of nitriles.

“Moreover, in all electrolyte systems studied by Cho, 2% FEC was used as SEI additive to relieve the graphite incompatibility issue of nitriles.”

• cites [52] Cho, Y.G., Kim, Y.S., Sung, D.G., et al.: Nitrile-assistant eutectic electrolytes for cryogenic operation of lithium ion batteries at fast charges and discharges. Energy Environ. Sci. 7, 1737–1743 (2014). https://doi.org/10.1039/C3EE43029D sourcePartly supported

  Section 2.1 (page unavailable) states that 2 wt% FEC was used as an SEI-forming agent for the cell tests, supporting the amount and additive role. It does not say FEC was used in every electrolyte measurement or that its purpose was specifically to relieve nitrile–graphite incompatibility. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Highly improved bulk ion transport properties effectively increased the discharge/charge capacity of graphite||NCA full cells at -20 °C.

“The highly improved bulk ion transport properties effectively increased the discharge/charge capacity of graphite||NCA full cells at LT (-20 °C) (Fig. 7b).”

• cites [52] Cho, Y.G., Kim, Y.S., Sung, D.G., et al.: Nitrile-assistant eutectic electrolytes for cryogenic operation of lithium ion batteries at fast charges and discharges. Energy Environ. Sci. 7, 1737–1743 (2014). https://doi.org/10.1039/C3EE43029D sourceSupported

The Li/SPAN cell using 1 M LiFSI in DOL/DME failed immediately at -60 °C.

“In contrast, the Li/SPAN cell using 1 M LiFSI in DOL/DME failed immediately at -60 °C.”

• cites [57] Holoubek, J., Liu, H.D., Wu, Z.H., et al.: Tailoring electrolyte solvation for Li metal batteries cycled at ultra-low temperature. Nat. Energy (2021). https://doi.org/10.1038/s41560-021-00783-z sourcePartly supported

  The Full Cell Behavior section (Fig. 6g; page not provided) reports that the Li||SPAN cell using 1 M LiFSI in DOL/DME had no viable capacity output after two cycles at −60 °C. This supports failure at that temperature, but not the claim that it failed immediately. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Introducing diluents such as hydrofluoroethers to form LHCE has the advantages of both good SEI formation capability and low viscosity.

“An effective measure to address this issue is to introduce diluents (i.e., hydrofluoroethers) to form the LHCE which has the advantages of both good SEI formation capability and low viscosity [62,[105][106][107].”

• cites [62] Fan, X.L., Ji, X., Chen, L., et al.: All-temperature batteries enabled by fluorinated electrolytes with non-polar solvents. Nat. Energy 4, 882–890 (2019). https://doi.org/10.1038/s41560-019-0474-3 sourceNot checked — no full text of the source
• cites [105] Chen, S.R., Zheng, J.M., Yu, L., et al.: High-efficiency lithium metal batteries with fire-retardant electrolytes. Joule 2, 1548–1558 (2018). https://doi.org/10.1016/j.joule.2018.05.002 sourceSupported
• cites [106] Zheng, Y., Soto, F.A., Ponce, V., et al.: Localized high concentration electrolyte behavior near a lithium-metal anode surface. J. Mater. Chem. A 7, 25047–25055 (2019). https://doi.org/10.1039/C9TA08935G sourceNot checked — no full text of the source

Pouch cells using electrolytes with shorter alkyl chain nitrile (acetonitrile) with higher ionic conductivity delivered less discharge capacity at the same condition compared with propionitrile, which has the best retention at -20 °C for room-temperature capacity.

“However, pouch cells using electrolytes with shorter alkyl chain nitrile (i.e., AN) with a higher ionic conductivity delivered less discharge capacity at the same condition compared with propionitrile (PN), which has the best retention at -20 °C for RT capacity.”

• cites [52] Cho, Y.G., Kim, Y.S., Sung, D.G., et al.: Nitrile-assistant eutectic electrolytes for cryogenic operation of lithium ion batteries at fast charges and discharges. Energy Environ. Sci. 7, 1737–1743 (2014). https://doi.org/10.1039/C3EE43029D sourcePartly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

Electrolyte ionic conductivity was greatly improved after introducing nitriles.

“The electrolyte ionic conductivity was greatly improved after introducing nitriles (Fig. 7a).”

• cites [52] Cho, Y.G., Kim, Y.S., Sung, D.G., et al.: Nitrile-assistant eutectic electrolytes for cryogenic operation of lithium ion batteries at fast charges and discharges. Energy Environ. Sci. 7, 1737–1743 (2014). https://doi.org/10.1039/C3EE43029D sourceSupported

Addition of the ionic additive LiFSI can suppress Li plating compared to a baseline cell.

“It was reported that the addition of ionic additive LiFSI can suppress the Li plating compared to the baseline cell.”

• cites [139] Pham, H.Q., Chung, G.J., Han, J., et al.: Interface stabilization via lithium bis(fluorosulfonyl)imide additive as a key for promoted performance of graphite‖LiCoO2 pouch cell under − 20 °C. J. Chem. Phys. 152, 094709 (2020). https://doi.org/10.1063/1.5144280 sourceSupported

LiF lattice signature was not detected in the FEC-derived SEI.

“Strangely, the signature of Li fluoride (LiF) lattice was not detected, even though LiF is considered to be a primary reason for performance enhancement [162].”

• cites [165] Li, Y.Z., Li, Y.B., Pei, A., et al.: Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy. Science 358, 506–510 (2017). https://doi.org/10.1126/science.aam6014 sourceSupported

Cryo-EM outperforms other techniques for characterizing the sensitive chemical composition, spatial distribution, and nanoscale morphology of the SEI.

“In the former [164], cryo-EM was reported to outperform other techniques used for characterizing the sensitive chemical composition and spatial distribution of the SEI, as well as the morphology at nanoscale.”

• cites [164] Wang, X.F., Zhang, M.H., Alvarado, J., et al.: New insights on the structure of electrochemically deposited lithium metal and its solid electrolyte interphases via cryogenic TEM. Nano Lett. 17, 7606–7612 (2017). https://doi.org/10.1021/acs.nanolett.7b03606 sourceSupported

In contrast, only about 175 mAh g-1 was obtained at the same condition for a cell using the electrolyte without FEC.

“In contrast, only ~ 175 mAh g -1 was obtained at the same condition for a cell using the electrolyte without FEC (Fig. 14a) [125].”

• cites [125] Liu, B.X., Li, B., Guan, S.Y.: Effect of fluoroethylene carbonate additive on low temperature performance of Li-ion batteries. Electrochem. Solid-State Lett. 15, A77 (2012). https://doi.org/10.1149/2.027206esl sourcePartly supported

  The Results and Discussion section reports that a cell without FEC had a lower first-cycle discharge capacity at −20 °C than a cell with 2% FEC. It does not give an absolute capacity of approximately 175 mAh g⁻¹, so the cited text supports the comparison but not the claimed number. (LLM, conf=0.83)

  Experimental — accuracy not yet measured

The difference in capacity with and without FEC was attributed to decreased charge transfer and SEI impedance after forming LiF-rich SEIs with FEC.

“This difference was attributed to the decreased charge transfer and the SEI impedance after forming LiF-rich SEIs with FEC.”

• cites [125] Liu, B.X., Li, B., Guan, S.Y.: Effect of fluoroethylene carbonate additive on low temperature performance of Li-ion batteries. Electrochem. Solid-State Lett. 15, A77 (2012). https://doi.org/10.1149/2.027206esl sourceSupported

By using conventional carbonate electrolyte with FEC as additive, a capacity of about 320 mAh g-1 was delivered when a Li/graphite cell was discharged at -20 °C at a 1/15C rate.

“By using conventional carbonate electrolyte with FEC as the additive, it was reported that a capacity of ~ 320 mAh g -1 was delivered when a Li/graphite cell was discharged at -20 °C (a 1/15C rate).”

• cites [125] Liu, B.X., Li, B., Guan, S.Y.: Effect of fluoroethylene carbonate additive on low temperature performance of Li-ion batteries. Electrochem. Solid-State Lett. 15, A77 (2012). https://doi.org/10.1149/2.027206esl sourcePartly supported

  The Experimental section (page unavailable) describes Li/graphite cells using a carbonate electrolyte with FEC and discharge at −20 °C at 1/15C. Results and Discussion (page unavailable) reports increased discharge capacity with FEC, but our copy gives no value of approximately 320 mAh g⁻¹; a search for 320 did not find it. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

LEMC, instead of LEDC, becomes the major organic component in the SEI on graphite anodes in LiPF6-EC/DMC electrolytes after prolonged cycling.

“Their results show that lithium ethylene mono-carbonate (LEMC), instead of lithium ethylene di-carbonate (LEDC), becomes the major organic components in the SEI on graphite anodes in LiPF 6 -EC/DMC electrolytes, after prolonged cycling.”

• cites [30] Wang, L.N., Menakath, A., Han, F.D., et al.: Identifying the components of the solid-electrolyte interphase in Li-ion batteries. Nat. Chem. 11, 789–796 (2019). https://doi.org/10.1038/s41557-019-0304-z sourcePartly supported

  Section 1.5 describes analyzing the SEI on graphite after three cycles in LiPF6/EC/DMC, using LEMC and LEDC as reference materials. Supplementary Figure 26 reports that LEMC was more persistent than LEDC in separate reaction tests, but those tests do not establish which compound dominates the graphite SEI. The available passages do not support the claim that LEMC becomes its major organic component after prolonged cycling. (LLM, conf=0.78)

  Experimental — accuracy not yet measured

The amorphous matrix in the SEI is likely the organic polymer formed by carbonate electrolyte decomposition.

“The amorphous matrix is likely the organic polymer formed by carbonate electrolyte decomposition.”

• cites [165] Li, Y.Z., Li, Y.B., Pei, A., et al.: Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy. Science 358, 506–510 (2017). https://doi.org/10.1126/science.aam6014 sourceSupported

Boron-based salts such as LiBOB, LiDFOB and similar derivatives were used as electrolyte additives due to their good SEI film-forming properties.

“Some boron-based salts described in Sect.3, such as LiBOB, LiDFOB and similar derivatives, were also used as electrolyte additives due to their good SEI film-forming properties [136, 137].”

• cites [136] Smart, M.C., Hwang, C., Krause, F.C., et al.: Wide operating temperature range electrolytes for high voltage and high specific energy Li-ion cells. ECS Trans. 50, 355–364 (2013). https://doi.org/10.1149/05026.0355ecst sourcePartly supported

  The Introduction describes LiBOB as an electrolyte additive among formulations containing SEI-promoting additives. It does not identify LiDFOB or similar boron-based derivatives as additives. The Results and Discussion attribute the LiBOB formulation’s improved performance to a possible cathode electrolyte interface (CEI) effect, rather than demonstrating SEI film formation. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [137] Cappetto, A., Cao, W.J., Luo, J.F., et al.: Performance of wide temperature range electrolytes for Li-Ion capacitor pouch cells. J. Power Sources 359, 205–214 (2017). https://doi.org/10.1016/j.jpowsour.2017.05.071 sourceNot checked — no full text of the source

The crystalline grains in the SEI are inorganic components identified as Li oxide and Li carbonate by matching their lattice spacings.

“These crystalline grains are the inorganic components of the SEI, identified to be Li oxide and Li carbonate by matching their lattice spacings.”

• cites [165] Li, Y.Z., Li, Y.B., Pei, A., et al.: Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy. Science 358, 506–510 (2017). https://doi.org/10.1126/science.aam6014 sourceSupported

Cryo-TEM for the first time elucidated the nanostructure of electrochemically deposited Li (EDLi) and its surface SEI film.

“For the first time, cryo-TEM elucidates the nanostructure of the electrochemically deposited Li (EDLi) and its surface SEI film.”

• cites [164] Wang, X.F., Zhang, M.H., Alvarado, J., et al.: New insights on the structure of electrochemically deposited lithium metal and its solid electrolyte interphases via cryogenic TEM. Nano Lett. 17, 7606–7612 (2017). https://doi.org/10.1021/acs.nanolett.7b03606 sourceSupported

At -40 °C, the Li-LFP cell showed 90% capacity retention after 100 cycles at a cathode-limited areal capacity of 5 mAh cm-2.

“At -40 °C, the Li-LFP cell showed 90% capacity retention after 100 cycles at the cathode-limited areal capacity (5 mAh cm -2 ).”

• cites [139] Pham, H.Q., Chung, G.J., Han, J., et al.: Interface stabilization via lithium bis(fluorosulfonyl)imide additive as a key for promoted performance of graphite‖LiCoO2 pouch cell under − 20 °C. J. Chem. Phys. 152, 094709 (2020). https://doi.org/10.1063/1.5144280 sourceCould not verify

  The Experimental Section (page unavailable) describes graphite‖LiCoO₂ pouch cells cycled at −20 °C for 50 cycles, not Li–LFP cells. A search for Li–LFP, −40 °C, 100 cycles, and 5 mAh cm⁻² found no passage reporting the claimed result; the different experiment does not establish that the claimed result is false. (LLM, conf=0.76)

  Experimental — accuracy not yet measured

The SEI contains small crystalline domains (diameter ~3 nm) dispersed randomly throughout an amorphous matrix that coats the Li metal.

“In the latter [165], the SEI was revealed to contain small crystalline domains (diameter ~ 3 nm) dispersed randomly throughout an amorphous matrix that coats the Li metal.”

• cites [165] Li, Y.Z., Li, Y.B., Pei, A., et al.: Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy. Science 358, 506–510 (2017). https://doi.org/10.1126/science.aam6014 sourceSupported

The benefit of using FEC decreased rapidly during cycling and became insignificant after 25 cycles at -20 °C.

“Unfortunately, the benefit of using FEC decreased rapidly during cycling and became insignificant after 25 cycles at -20”

• cites [125] Liu, B.X., Li, B., Guan, S.Y.: Effect of fluoroethylene carbonate additive on low temperature performance of Li-ion batteries. Electrochem. Solid-State Lett. 15, A77 (2012). https://doi.org/10.1149/2.027206esl sourceSupported

The SEI formed in standard electrolyte resembles the mosaic structure predicted by Peled et al., which describes the SEI as a heterogeneous distribution of inorganic and organic components.

“The SEI formed in this standard electrolyte resembles the mosaic structure predicted by Peled et al. [166], who described the SEI as a heterogeneous distribution of inorganic and organic components.”

• cites [165] Li, Y.Z., Li, Y.B., Pei, A., et al.: Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy. Science 358, 506–510 (2017). https://doi.org/10.1126/science.aam6014 sourceSupported
• cites [166] Peled, E., Golodnitsky, D., Ardel, G.: Advanced model for solid electrolyte interphase electrodes in liquid and polymer electrolytes. J. Electrochem. Soc. 144, L208–L210 (1997). https://doi.org/10.1149/1.1837858 sourceSupported

A completely different SEI structure is formed in carbonate-based electrolyte with 10% FEC.

“They also observed a completely different SEI structure when it was formed in a carbonate-based electrolyte with 10% FEC.”

• cites [165] Li, Y.Z., Li, Y.B., Pei, A., et al.: Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy. Science 358, 506–510 (2017). https://doi.org/10.1126/science.aam6014 sourceSupported

The SEI formed in the presence of FEC is more ordered and appears to have a multilayer structure, consistent with the multilayer system proposed by Aurbach et al.

“Instead of a random distribution of organic and inorganic components, the SEI formed in the presence of FEC is more ordered and appears to have a multilayer structure, consistent with the multilayer system proposed by Aurbach et al. [167].”

• cites [165] Li, Y.Z., Li, Y.B., Pei, A., et al.: Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy. Science 358, 506–510 (2017). https://doi.org/10.1126/science.aam6014 sourceSupported
• cites [167] Aurbach, D., Ein-Ely, Y., Zaban, A.: The surface chemistry of lithium electrodes in alkyl carbonate solutions. J. Electrochem. Soc. 141, L1–L3 (1994). https://doi.org/10.1149/1.2054718 sourceNot checked — no full text of the source

When cycled between 3.0 and 4.3 V at -20 °C, the cell using LiFSI additive delivered ~30% higher capacity than baseline at all rates of 0.1 C, 0.2 C, 0.5 C, 1 C, and 2 C.

“when cycled between 3.0 and 4.3 V at -20 °C, the cell using LiFSI additive delivered ~ 30% higher capacity than the baseline electrolyte at all rates of 0.1 C, 0.2 C, 0.5 C, 1 C, and 2 C.”

• cites [139] Pham, H.Q., Chung, G.J., Han, J., et al.: Interface stabilization via lithium bis(fluorosulfonyl)imide additive as a key for promoted performance of graphite‖LiCoO2 pouch cell under − 20 °C. J. Chem. Phys. 152, 094709 (2020). https://doi.org/10.1063/1.5144280 sourcePartly supported

  The Fig. 4 rate-capability discussion reports higher discharge capacities with LiFSI at every listed rate between 0.1 C and 2 C, under −20 °C and between 3.0 and 4.3 V. Its reported values imply increases of about 34% at 0.1 C and 39–46% at the other listed rates, so the claim’s “~30% higher” magnitude does not fit all rates. The supplied passage does not specify a page. (LLM, conf=0.89)

  Experimental — accuracy not yet measured

The ternary electrolyte 1 M LiPF6 in EC:DMC:DEC (1:1:1) resulted in the largest discharge capacity in a graphite||LiCoO2 cell.

“This resulted in the largest discharge capacity in a graphite||LiCoO 2 cell using the ternary electrolyte (Fig. 4b).”

• cites [20] Smart, M.C., Ratnakumar, B.V., Surampudi, S.: Electrolytes for low-temperature lithium batteries based on ternary mixtures of aliphatic carbonates. J. Electrochem. Soc. 146, 486–492 (1999). https://doi.org/10.1149/1.1391633 sourceNot checked — no full text of the source

To effectively improve the low-temperature performance of a lithium-ion battery, one must simultaneously improve both charge transfer kinetics and bulk electrolyte ionic conductivity.

“Therefore, in order to effectively improve the LT performance of a LIB, one must simultaneously improve both charge transfer kinetics and bulk electrolyte ionic conductivity.”

A ternary low-temperature electrolyte consisting of 1.0 M LiPF6 in EC:EMC:MP (20:60:20 by volume) enabled several NASA missions when incorporated into mesocarbon microbead-graphite-LiNiCoAlO2 cells requiring good charging and discharging from -30 to 35 °C.

“Smart et al. [22] at Jet Propulsion Laboratory developed a ternary LT electrolyte consisting of 1.0 M LiPF 6 in EC:ethyl methyl carbonate (EMC):methyl propionate (MP) (20:60:20 in volume ratio), which has enabled several NASA missions when incorporated into mesocarbon microbead (MCMB)-graphite-LiNiCoAlO 2 (NCA) cells where good performance was required for charging and discharging from -30 to 35 °”

• cites [22] Smart, M.C., Ratnakumar, B.V., Ewell, R.C., et al.: The use of lithium-ion batteries for JPL’s Mars missions. Electrochim. Acta 268, 27–40 (2018). https://doi.org/10.1016/j.electacta.2018.02.020 sourceNot checked — no full text of the source

The freezing point of different carbonate electrolytes can be tuned by adjusting the composition and content of the solvent.

“Therefore, the freezing point of different electrolytes can be tuned by adjusting the composition and the content of the solvent.”

Ethylene carbonate is widely used because of its high dielectric constant and excellent solid electrolyte interphase formation capability.

“The widely used EC is based on its high dielectric constant and excellent SEI formation capability.”

An ethyl trifluoroacetate/fluoroethylene carbonate electrolyte demonstrated excellent compatibility with both lithium metal anode and graphite anode over a wide temperature range with fast charging rates.

“This electrolyte demonstrated excellent compatibility with both LMA and graphite anode at wide-temperature range with fast charging rates.”

• cites [46] Yang, Y., Fang, Z., Yin, Y., et al.: Synergy of weakly-solvated electrolyte and optimized interphase enables graphite anode charge at low temperature. Angewandte Chemie Int. Ed. 61, e202208345 (2022). https://doi.org/10.1002/anie.202208345 sourceNot checked — no full text of the source

The interphasial process, rather than the bulk process, has the dominant influence on the overall low-temperature electrochemical performance of lithium-ion batteries.

“Therefore, it is the interphasial process, rather than the bulk process, that has the dominant influence on the overall LT electrochemical performance.”

Linear carbonates and carboxylic esters are desirable for low-temperature electrolytes owing to their low viscosity and low melting points.

“Linear carbonates and carboxylic esters are always desirable for LT electrolytes, owing to their low viscosity and low melting points (Fig. 3).”

A multi-solvent system has higher conductivity than a single-solvent system at low temperatures due to the disordered effect of Li+ coordination in various mixed solvents.

“In addition to the tunable freezing point, the multi-solvent system owns a higher conductivity than the single-solvent system at LTs due to the disordered effect of Li + coordination in various mixed solvents [19].”

• cites [19] Dong, X.L., Wang, Y.G., Xia, Y.Y.: Promoting rechargeable batteries operated at low temperature. Acc. Chem. Res. 54, 3883–3894 (2021). https://doi.org/10.1021/acs.accounts.1c00420 sourceNot checked — no full text of the source

The high viscosity and high freezing point of ethylene carbonate (36.4 °C) negatively affect ionic conductivity, especially at room or low temperatures.

“However, the high viscosity and high freezing point (36.4 °C) of EC negatively affect the ionic conductivity, especially at room or low temperatures.”

Electrolyte engineering is one of the most effective approaches to mitigate lithium-ion battery performance degradation at low temperatures.

“The electrolyte engineering has proved to be one of the most effective approaches to mitigate LIB performance degradation at LTs.”

Desolvation is identified as the most sluggish step with the highest energy barrier in many Li+ charge transfer systems.

“During the whole charge transfer process, desolvation is identified to be the most sluggish step with the highest energy barrier to be overcome in many systems.”

• cites [10] Xu, K., von Cresce, A., Lee, U.: Differentiating contributions to “ion transfer” barrier from interphasial resistance and Li+ desolvation at electrolyte/graphite interface. Langmuir 26, 11538–11543 (2010). https://doi.org/10.1021/la1009994 sourceNot checked — no full text of the source

The low-temperature limit of an electrolyte may not be provided by the lowest-melting linear carbonate.

“Under such context, the LT limit of electrolyte may not be provided by the lowest melting linear carbonate.”

The effect of low lithium-ion transference number becomes especially pronounced at high charge/discharge rates.

“The effect of low t Li + would become especially pronounced at high charge/discharge rates [9].”

• cites [9] Qian, Y.X., Chu, Y.L., Zheng, Z.T., et al.: A new cyclic carbonate enables high power/low temperature lithium-ion batteries. Energy Storage Mater. 45, 14–23 (2022). https://doi.org/10.1016/j.ensm.2021.11.029 sourceNot checked — no full text of the source

Lithium metal plating and dendrite formation on the graphite anode surface, caused by increased anode polarization at low temperatures, can cause severe capacity loss and internal short circuit.

“The lithium metal (Li 0 ) plating and dendrite formation on the graphite anode surface, both caused by the increased anode polarization at low temperatures (LTs), can cause severe capacity loss and internal short circuit.”

Linear carbonates with low melting points and low viscosity are introduced as cosolvents to address the high viscosity and high freezing point of ethylene carbonate.

“Thus, linear carbonates with low melting points and low viscosity are always introduced as cosolvents to address these issues.”

The high melting point of ethylene carbonate (36.4 °C) is responsible for the significantly increased electrolyte viscosity at low temperatures.

“Unfortunately, the most widely used electrolyte solvent, EC, has a high melting point (36.4 °C), which is responsible for the significantly increased electrolyte viscosity at LTs.”

More delocalized charges on anions make them less likely to reassociate with cations after salt dissolution.

“and similarly, the more delocalized the charges on the anions are, the less likely they would reassociate with the cations after the salt dissolution.”

An optimized EC:DMC:EMC solvent ratio of 8.3:25:66.7 by weight achieved 90% capacity at -40 °C.

“Xiao et al. [26] systematically compared the different content ratios of EC:DMC:EMC systems and achieved 90% capacity at -40 °C with the optimized solvent ratio (EC:DMC:EMC, 8.3:25:66.7 in weight ratio).”

• cites [26] Xiao, L.F., Cao, Y.L., Ai, X.P., et al.: Optimization of EC-based multi-solvent electrolytes for low temperature applications of lithium-ion batteries. Electrochim. Acta 49, 4857–4863 (2004). https://doi.org/10.1016/j.electacta.2004.05.038 sourceNot checked — no full text of the source

Solid electrolyte interphase properties vary with the type of linear carbonate introduced.

“In addition to ion transport properties, SEI properties vary with the type of linear carbonates introduced.”

Li+ transport through the solid electrolyte interphase is often a limiting factor at low temperatures.

“In addition to bulk transport properties, Li + transport through solid electrolyte interphase (SEI) is often a limiting factor at LTs.”

When the salt concentration is 4 M, a Li/LiNi0.5Mn1.5O4 cell maintained 80.85% of its room-temperature specific discharge capacity at -50 °C.

“When the salt concentration is 4 M, the Li/LiNi 0.5 Mn 1.5 O 4 (LNMO) cell maintained 80.85% of its RT specific discharge capacity even at the LT of -50 °C.”

• cites [45] Feng, T.T., Yang, G.Z., Zhang, S., et al.: Low-temperature and high-voltage lithium-ion battery enabled by localized high-concentration carboxylate electrolytes. Chem. Eng. J. 433, 134138 (2022). https://doi.org/10.1016/j.cej.2021.134138 sourceNot checked — no full text of the source

Ion transport across electrode/electrolyte interphases plays a comparable or even more important role than sluggish bulk electrolyte ion transport in the deteriorated low-temperature performance of lithium-ion batteries.

“However, the ion transport across electrode/ electrolyte interphases plays comparable or even more important roles [5].”

• cites [5] Zhu, G.L., Wen, K.C., Lv, W.Q., et al.: Materials insights into low-temperature performances of lithium-ion batteries. J. Power Sources 300, 29–40 (2015). https://doi.org/10.1016/j.jpowsour.2015.09.056 sourceNot checked — no full text of the source

A lithium-ion battery reported in 2015 had a significant capacity drop to about one fifth of its room-temperature capacity at -30 °C.

“In a paper published in 2015, a LIB was reported to have a significant capacity drop down to about one fifth of its RT capacity at -30 °C [5].”

• cites [5] Zhu, G.L., Wen, K.C., Lv, W.Q., et al.: Materials insights into low-temperature performances of lithium-ion batteries. J. Power Sources 300, 29–40 (2015). https://doi.org/10.1016/j.jpowsour.2015.09.056 sourceNot checked — no full text of the source

The liquidus lines of binary cyclic/linear carbonate systems depend not only on the low melting temperature of the individual components but also on how much these melting temperatures match each other.

“According to the phase diagrams constructed for the binary systems of these cyclic and linear carbonates, the liquidus lines, which serve as a demarcation between stable liquid electrolyte and onset for solid precipitation, depend not only on the low melting temperature of the individual components, but also on how much these melting temperatures”

Electrolyte ionic conductivity drops at low temperatures because of increased viscosity, rendering sluggish Li+ migration in the bulk electrolyte.

“As expected, the electrolyte ionic conductivity drops at LTs because of the increased viscosity, rendering sluggish Li + migration in the bulk electrolyte.”

Most graphite anode materials can only deliver 12% of room-temperature capacity when both lithiation and delithiation are carried out at -20 °C.

“As reported in early 2000, most graphite anode materials can only deliver 12% of room-temperature (RT) capacity when both lithiation and delithiation were carried out at -20 °C [3].”

• cites [3] Zhang, S.S., Xu, K., Jow, T.R.: Low temperature performance of graphite electrode in Li-ion cells. Electrochim. Acta 48, 241–246 (2002). https://doi.org/10.1016/S0013-4686(02)00620-5 sourceNot checked — no full text of the source

This is the first attempt to use a localized high-concentration electrolyte for a high-voltage Li/LiNi0.5Mn1.5O4 system at low temperatures.

“It should be noticed that this is the first attempt to use LHCE for high-voltage Li/LNMO system at LTs.”

• cites [45] Feng, T.T., Yang, G.Z., Zhang, S., et al.: Low-temperature and high-voltage lithium-ion battery enabled by localized high-concentration carboxylate electrolytes. Chem. Eng. J. 433, 134138 (2022). https://doi.org/10.1016/j.cej.2021.134138 sourceNot checked — no full text of the source

When the solid electrolyte interphase is not less pronounced or highly conductive, Li+ transport inside the solid electrolyte interphase still plays a significant role in Li+ charge transfer kinetics.

“Otherwise, Li + transport inside the SEI still plays a significant role in Li + charge transfer kinetics.”

The challenges of lithium-ion batteries at subzero temperatures primarily come from the anode side.

“These challenges primarily come from the anode side.”

Low-melting-point and low-viscosity linear carbonates with stable solid electrolyte interphase formation abilities are good candidates as cosolvents and even main solvents for low-temperature applications.

“These low melting point and low viscosity linear carbonates with stable SEI formation abilities are good candidates as cosolvents and even main solvents for LT applications.”

Compared with the binary electrolytes 1 M LiPF6 in EC:DMC (30:70) and 1 M LiPF6 in EC:DEC (30:70), the ternary electrolyte 1 M LiPF6 in EC:DMC:DEC (1:1:1) showed the highest ionic conductivity at -20 °C due to a synergistic effect.

“Compared to the two binary electrolytes of 1 M LiPF 6 in EC:DMC (30:70) and 1 M LiPF 6 in EC:DEC (30:70), the ternary electrolyte of 1 M LiPF 6 in EC:DMC:DEC (1:1:1) showed the highest ionic conductivity at -20 °C due to synergistic effect as shown in Fig. 4a.”

• cites [20] Smart, M.C., Ratnakumar, B.V., Surampudi, S.: Electrolytes for low-temperature lithium batteries based on ternary mixtures of aliphatic carbonates. J. Electrochem. Soc. 146, 486–492 (1999). https://doi.org/10.1149/1.1391633 sourceNot checked — no full text of the source

The combination of salts and solvents can influence the transport kinetics of the electrolyte.

“The combination of salts and solvents can influence the transport kinetics of the electrolyte [6].”

• cites [6] Xu, K.: Nonaqueous liquid electrolytes for lithium-based rechargeable batteries. ChemInform 35, 5 (2004). https://doi.org/10.1002/chin.200450271 sourceNot checked — no full text of the source

A methyl acetate-based, ethylene-carbonate-free electrolyte developed by Zhang's group shows exceptional low-temperature performance.

“Moreover, the MA-based EC-free electrolyte developed by Zhang's group shows exceptional LT performance [47].”

• cites [47] Yao, Y.X., Yao, N., Zhou, X.R., et al.: Ethylene-carbonate-free electrolytes for rechargeable Li-ion pouch cells at sub-freezing temperatures. Adv. Mater. 34, 2206448 (2022). https://doi.org/10.1002/adma.202206448 sourceNot checked — no full text of the source

DME-based LHCE systems with bis(2,2,2-trifluoroethyl) ether as diluent allow modulation of the degree of ion-pairing while maintaining relatively low bulk viscosity.

“bis(2,2,2-trifluoroethyl) ether (BTFE) as the diluent, which allows for the modulation of the degree of ion-pairing while maintaining a relatively low bulk viscosity [58].”

• cites [58] Holoubek, J., Kim, K., Yin, Y.J., et al.: Electrolyte design implications of ion-pairing in low-temperature Li metal batteries. Energy Environ. Sci. 15, 1647–1658 (2022). https://doi.org/10.1039/D1EE03422G sourceNot checked — no full text of the source

SEIs formed by fluorinated linear carbonates have lower impedance than conventional EC-DEC-based electrolytes.

“As shown in Fig. 9b, SEIs formed by the fluorinated linear carbonates have lower impedance than conventional EC-DEC-based electrolytes.”

By adding EG as additive, the low-temperature rate performance of LiFePO4 cathode at -20 °C was optimized due to improved ionic mobility.

“By adding EG as additive, the LT rate performance of LiFePO 4 cathode at -20 °C has been successfully optimized due to the improved ionic mobility [82].”

• cites [82] Tron, A., Jeong, S., Park, Y.D., et al.: Aqueous lithium-ion battery of nano-LiFePO4 with antifreezing agent of ethyleneglycol for low-temperature operation. ACS Sustain. Chem. Eng. 7, 14531–14538 (2019). https://doi.org/10.1021/acssuschemeng.9b02042 sourceNot checked — no full text of the source

The ionic conductivity of polymer electrolytes is largely affected by the liquid electrolyte components.

“This work suggested that the ionic conductivity of polymer electrolytes is largely affected by the liquid electrolyte components.”

• cites [72] Smart, M.C., Ratnakumar, B.V., Behar, A., et al.: Gel polymer electrolyte lithium-ion cells with improved low temperature performance. J. Power Sources 165, 535–543 (2007). https://doi.org/10.1016/j.jpowsour.2006.10.038 sourceNot checked — no full text of the source

The Li||LiNi0.8Co0.15Al0.05O2 cell can be cycled well using a cutoff voltage of 4.3 V for charging.

“The Li||LiNi 0.8 Co 0.15 Al 0.05 O 2 cell can be cycled well using a cutoff voltage of 4.3 V for charging.”

• cites [62] Fan, X.L., Ji, X., Chen, L., et al.: All-temperature batteries enabled by fluorinated electrolytes with non-polar solvents. Nat. Energy 4, 882–890 (2019). https://doi.org/10.1038/s41560-019-0474-3 sourceNot checked — no full text of the source

LiPF6 represents an excellent balanced property compared to other salts such as LiBF4, LiClO4, and LiAsF6.

“Considering all these parameters, LiPF 6 represents an excellent balanced property compared to other salts, such as LiBF 4 , LiClO 4 , and LiAsF 6 .”

Liu's group selected sulfolane as cosolvent of antifreeze and water activity inhibitor because of its low toxicity, high miscibility with water, high oxidation stability, and strong interaction with water molecules.

“In another work reported by Liu's group [86], sulfolane (SL) was selected as the cosolvent of antifreeze and the activity inhibitor of water, because of its low toxicity, high miscibility with water, high oxidation stability and strong interaction with water molecules.”

• cites [86] Liu, J.H., Yang, C., Chi, X.W., et al.: Water/sulfolane hybrid electrolyte achieves ultralow-temperature operation for high-voltage aqueous lithium-ion batteries. Adv. Funct. Mater. 32, 2106811 (2022). https://doi.org/10.1002/adfm.202106811 sourceNot checked — no full text of the source

Excessively large anions can lead to low mobility that is adverse for ion transport, as seen in BETI or other poly-TFSI anions.

“However, excessively large anions can lead to low mobility which is adverse for ion transport, which can be seen in the examples of bis[(pentafluoroethyl)sulfonyl]imide (BETI) or other poly-TFSI anions.”

Smart et al. found that fluorinated linear carbonates delivered much higher capacity than non-fluorinated analogues at -20 °C.

“For example, Smart et al. [64] studied a series of fluorinated linear carbonates and found that these electrolytes were able to deliver much higher capacity than the non-fluorinated analogues at -20 °C (Fig. 9a).”

• cites [64] Smart, M.C., Ratnakumar, B.V., Ryan-Mowrey, V.S., et al.: Improved performance of lithium-ion cells with the use of fluorinated carbonate-based electrolytes. J. Power Sources 119(120/121), 359–367 (2003). https://doi.org/10.1016/S0378-7753(03)00266-0 sourceNot checked — no full text of the source

Armand et al. proposed hindered glymes with bulky groups that prevent solvent co-intercalation due to their larger size and lower binding energy to Li+, making Li+ desolvation more favorable than co-intercalation.

“Armand et al. [54] proposed a family of “hindered glymes” with bulky groups that prevent solvent co-intercalation due to their larger size and lower binding energy to Li + making the Li + cation desolvation more favorable than co-intercalation.”

• cites [54] Shanmukaraj, D., Grugeon, S., Laruelle, S., et al.: Hindered glymes for graphite-compatible electrolytes. Chemsuschem 8, 2691–2695 (2015). https://doi.org/10.1002/cssc.201500502 sourceNot checked — no full text of the source

The gel polymer cell containing 1 M LiPF6 in EC:DEC:DMC:EMC (1:1:1:3, volume ratio) delivered nearly full (>99%) room-temperature capacity when discharged at -40 °C using a C/10 rate.

“The gel polymer cell containing electrolyte of 1 M LiPF 6 in EC:DEC:DMC:EMC (1:1:1:3, volume ratio) delivered nearly full (> 99%) RT capacity when discharged at -40 °C using a C/10 rate (Fig. 10a).”

• cites [72] Smart, M.C., Ratnakumar, B.V., Behar, A., et al.: Gel polymer electrolyte lithium-ion cells with improved low temperature performance. J. Power Sources 165, 535–543 (2007). https://doi.org/10.1016/j.jpowsour.2006.10.038 sourceNot checked — no full text of the source

LiTFSI and LiFSI salts have high solubility in aprotic solvents enabled by stabilization of the negative charge provided by the strong electron-withdrawing group (-CF3 or -F).

“LiTFSI and LiFSI salts have attracted a lot of attention recently, due to their high solubility in aprotic solvents enabled by the stabilization of the negative charge provided by the strong electron-withdrawing group (-CF 3 or -F) [6].”

• cites [6] Xu, K.: Nonaqueous liquid electrolytes for lithium-based rechargeable batteries. ChemInform 35, 5 (2004). https://doi.org/10.1002/chin.200450271 sourceNot checked — no full text of the source

Within the wide temperature range, LMBs retained Coulombic efficiencies of 97.3%, 97.2%, 95.2%, and 91.0% at 0, -20, -40, and -60 °C, respectively.

“Moreover, within the widetemperature range, LMBs retained Coulombic efficiencies of 97.3%, 97.2%, 95.2% and 91.0% at 0, -20, -40 and -60 °C, respectively.”

• cites [78] Yin, Y.J., Yang, Y., Cheng, D.Y., et al.: Fire-extinguishing, recyclable liquefied gas electrolytes for temperature-resilient lithium-metal batteries. Nat. Energy 7, 548–559 (2022). https://doi.org/10.1038/s41560-022-01051-4 sourceNot checked — no full text of the source

Meng's group developed a novel LGE by adding the simplest liquefied ether to a non-flammable low-solvating hydrofluorocarbon mixture.

“Meng's group [78] recently developed a novel LGE by adding the simplest (liquefied) ether to a non-flammable lowsolvating hydrofluorocarbon mixture.”

• cites [78] Yin, Y.J., Yang, Y., Cheng, D.Y., et al.: Fire-extinguishing, recyclable liquefied gas electrolytes for temperature-resilient lithium-metal batteries. Nat. Energy 7, 548–559 (2022). https://doi.org/10.1038/s41560-022-01051-4 sourceNot checked — no full text of the source

Sulfur-containing compounds such as DTD and 1,3-PS have been extensively studied as electrolyte additives to form stable SEI layers on graphite and suppress graphite exfoliation in PC-based electrolytes.

“Sulfur-containing compounds, such as 1,3,2-dioxathiolane-2,2-dioxide (DTD) and 1,3-propanesultone (1,3-PS), have been extensively studied as electrolyte additives to form stable SEI layers on graphite and suppress graphite exfoliation in PC-based electrolytes.”

The enhanced performance with TFENH is attributed to the formation of a thin and stable SEI on the graphite surface that reduces charge transfer resistance.

“Such enhanced performance is attributed to the formation of a thin and stable SEI on the surface of graphite to reduce charge transfer resistance [70].”

• cites [70] Lu, W., Xiong, S.Z., Xie, K., et al.: Identification of solid electrolyte interphase formed on graphite electrode cycled in trifluoroethyl aliphatic carboxylate-based electrolytes for low-temperature lithium-ion batteries. Ionics 22, 2095–2102 (2016). https://doi.org/10.1007/s11581-016-1743-9 sourceNot checked — no full text of the source

1 M LiAsF6 in EC:EMC:MA:toluene (1:1:1:1, volume ratio) quaternary solvents displayed high ionic conductivity values of 1.830 and 1.100 mS cm-1 at -40 and -50 °C, respectively.

“For example, 1 M LiAsF 6 in EC:EMC:MA:toluene (1:1:1:1, volume ratio) quaternary solvents displayed high ionic conductivity values as 1.830 and 1.100 mS cm -1 at -40 and -50 °C, respectively [94].”

• cites [94] Shiao, H.C., Chua, D., Lin, H.P., et al.: Low temperature electrolytes for Li-ion PVDF cells. J. Power Sources 87, 167–173 (2000). https://doi.org/10.1016/S0378-7753(99)00470-X sourceNot checked — no full text of the source

After increasing the discharge rate to C/5, the gel polymer cell still delivered over 94% of room-temperature capacity.

“After increasing the discharge rate to C/5, this cell still delivered over 94% of RT capacity.”

• cites [72] Smart, M.C., Ratnakumar, B.V., Behar, A., et al.: Gel polymer electrolyte lithium-ion cells with improved low temperature performance. J. Power Sources 165, 535–543 (2007). https://doi.org/10.1016/j.jpowsour.2006.10.038 sourceNot checked — no full text of the source

Lithium cycling at >99% Coulombic efficiency for over 200 cycles at 3 mA cm-2 and 3 mAh cm-2 was demonstrated.

“As a result of the beneficial solvation chemistry and a fluorine-rich environment, a lithium cycling at > 99% Coulombic efficiency for over 200 cycles at 3 mA cm -2 and 3 mAh cm -2 was demonstrated.”

• cites [78] Yin, Y.J., Yang, Y., Cheng, D.Y., et al.: Fire-extinguishing, recyclable liquefied gas electrolytes for temperature-resilient lithium-metal batteries. Nat. Energy 7, 548–559 (2022). https://doi.org/10.1038/s41560-022-01051-4 sourceNot checked — no full text of the source

A LiBF4:LiBOB (9:1, molar ratio) dual-salt system in PC/EC/EMC ternary solvent enabled a Li-LiFePO4 cell to show enhanced cyclic performance in a wide temperature range from -50 to 90 °C.

“To combine the good ionic conductivity of LiBF 4 and decent SEI formation capability from LiBOB, a LiBF 4 :LiBOB (9:1, molar ratio) dual-salt system was developed by Xu et al. [99,102], in PC/EC/EMC ternary solvent the Li-LiFePO 4 (LFP) cell showed enhanced cyclic performance in a wide-temperature range from -50 to 90 °C.”

• cites [99] Zhang, S.S., Xu, K., Jow, T.R.: Enhanced performance of Li-ion cell with LiBF4-PC based electrolyte by addition of small amount of LiBOB. J. Power Sources 156, 629–633 (2006). https://doi.org/10.1016/j.jpowsour.2005.04.023 sourceNot checked — no full text of the source
• cites [102] Xu, K., Zhang, S.S., Lee, U., et al.: LiBOB: is it an alternative salt for lithium ion chemistry? J. Power Sources 146, 79–85 (2005). https://doi.org/10.1016/j.jpowsour.2005.03.153 sourceNot checked — no full text of the source

The counter-intuitive difference in discharge capacity between acetonitrile and propionitrile electrolytes must be attributed to the different interphases formed from the decomposition of these nitriles.

“This counter-intuitive difference must be attributed to the different interphases formed from the decomposition of these nitriles.”

The dual-salt electrolyte with a LiBF4:LiDFOB ratio of 8:2 enabled LiCoO2 cathodes with a high capacity retention of 98.67% at -20 °C after 300 cycles.

“The dual-salt electrolyte with a LiBF 4 :LiDFOB ratio of 8:2 enabled LiCoO 2 cathodes with a high capacity retention of 98.67% at -20 °C after 300 cycles.”

Lu et al. demonstrated that at a charge rate of 0.2 C, a graphite anode in an electrolyte with 25% TFENH maintained 92% of room-temperature capacity at -50 °C.

“Lu et al. also explored electrochemical performance of a graphite anode at different subzero temperatures in an electrolyte with 25% TFENH as cosolvent, and demonstrated that at a relatively higher charge rate of 0.2 C, the graphite anode maintained 92% of RT capacity at -50 °C.”

• cites [70] Lu, W., Xiong, S.Z., Xie, K., et al.: Identification of solid electrolyte interphase formed on graphite electrode cycled in trifluoroethyl aliphatic carboxylate-based electrolytes for low-temperature lithium-ion batteries. Ionics 22, 2095–2102 (2016). https://doi.org/10.1007/s11581-016-1743-9 sourceNot checked — no full text of the source

The cell using MB-based electrolytes delivered 80% of its room-temperature capacity when discharged at -60 °C.

“The cell using MB-based electrolytes delivered 80% of its RT capacity when discharged at -60 °C (Fig. 10b).”

• cites [72] Smart, M.C., Ratnakumar, B.V., Behar, A., et al.: Gel polymer electrolyte lithium-ion cells with improved low temperature performance. J. Power Sources 165, 535–543 (2007). https://doi.org/10.1016/j.jpowsour.2006.10.038 sourceNot checked — no full text of the source

Ethylene glycol can reduce the freezing point of aqueous electrolyte to lower than -24 °C.

“Ethylene glycol (EG) is a wellknown antifreeze additive with a high dielectric constant (ε = 37 at 25 °C), which can reduce the freezing point of aqueous electrolyte to be lower than -24 °C.”

Ethers are usually disfavored as a low-temperature electrolyte solvent for Li+.

“For these reasons, ethers are usually disfavored as an LT electrolyte solvent for Li + .”

The LGE with oxidation stability up to 4.4 V enabled Li/NMC622 cells to exhibit stable cycling properties from -60 to 55 °C.

“The LGE with oxidation stability up to 4.4 V enabled Li/NMC622 cells exhibiting stable cycling properties from -60 to 55 °C.”

• cites [78] Yin, Y.J., Yang, Y., Cheng, D.Y., et al.: Fire-extinguishing, recyclable liquefied gas electrolytes for temperature-resilient lithium-metal batteries. Nat. Energy 7, 548–559 (2022). https://doi.org/10.1038/s41560-022-01051-4 sourceNot checked — no full text of the source

Ionic conductivity is not always compromised by fluorination since some fluorination may lead to higher dielectric constant.

“the ionic conductivity is not always compromised since some fluorination may lead to higher dielectric constant.”

Among the fluorinated linear carbonates, the electrolyte with ethyl-2,2,2-trifluoroethyl carbonate exhibited the highest delivered capacity.

“Among them, the electrolyte with ethyl-2,2,2-trifluoroethyl carbonate (ETFEC) exhibited the highest delivered capacity [64].”

• cites [64] Smart, M.C., Ratnakumar, B.V., Ryan-Mowrey, V.S., et al.: Improved performance of lithium-ion cells with the use of fluorinated carbonate-based electrolytes. J. Power Sources 119(120/121), 359–367 (2003). https://doi.org/10.1016/S0378-7753(03)00266-0 sourceNot checked — no full text of the source

An expanded electrochemical stability window of 3.8 V was achieved due to the formation of a sulfolane-containing solvation sheath and strengthened O-H bond of water, inhibiting water decomposition.

“An expanded electrochemical stability window of 3.8 V has been achieved due to the formation of SL contained solvation sheath and strengthen O-H bond of water, inhibiting the decomposition of water.”

• cites [86] Liu, J.H., Yang, C., Chi, X.W., et al.: Water/sulfolane hybrid electrolyte achieves ultralow-temperature operation for high-voltage aqueous lithium-ion batteries. Adv. Funct. Mater. 32, 2106811 (2022). https://doi.org/10.1002/adfm.202106811 sourceNot checked — no full text of the source

Some sulfur-containing additives result in SEI layers that are less resistive.

“Moreover, it has been reported that some sulfur-containing additives result in SEI layers that are less resistive [33].”

• cites [33] Wotango, A., Su, W.N., Haregewoin, A.M., et al.: Designed synergetic effect of electrolyte additives to improve interfacial chemistry of MCMB electrode in propylene carbonate-based electrolyte for enhanced low and room temperature performance. ACS Appl. Mater. Interfaces 10, 25252–25262 (2018). https://doi.org/10.1021/acsami.8b02185 sourceNot checked — no full text of the source

Fluorinated solvents can significantly improve interphase chemistry and oxidation stability for low-temperature electrolytes.

“In addition to the usage of low melting point and low viscosity solvents mentioned above, the application of fluorinated solvents which could significantly improve the interphase chemistry and oxidation stability has also been extensively investigated for LT electrolytes.”

Even at -85 °C, the cell can still deliver about 50% of its room-temperature capacity.

“The ionic conductivity is also superior as demonstrated by the fact that even at -85 °C, the cell can still deliver ~ 50 % of its room-temperature capacity.”

• cites [62] Fan, X.L., Ji, X., Chen, L., et al.: All-temperature batteries enabled by fluorinated electrolytes with non-polar solvents. Nat. Energy 4, 882–890 (2019). https://doi.org/10.1038/s41560-019-0474-3 sourceNot checked — no full text of the source

Acetonitrile has an incompatibility issue with graphite anodes because its reduction product fails to form a solid interphase.

“Unfortunately, AN has the incompatibility issue with graphite anodes because its reduction product fails to form a solid interphase.”

Better SEIs can be obtained by using fluorinated electrolytes.

“More importantly, better SEIs could be obtained by using fluorinated electrolytes.”

From the cation-anion dissociation perspective, larger anions are more desirable than smaller ones because the negative charge is more delocalized, reducing Coulombic attraction between counterions.

“From the cation-anion dissociation perspective for salt selections, larger anions are more desirable than the smaller ones, because the negative charge is more delocalized, which in turn reduces the Coulombic attraction between counterions.”

Poor oxidative stability largely limits the application of ethers in high-voltage rechargeable batteries.

“In addition, the poor oxidative stability largely limits the application of ethers in high-voltage rechargeable batteries.”

For low-temperature electrolyte application, decreasing interphase impedance is particularly important since it can improve overall cell kinetics and offset negative effects on transport property caused by low temperature.

“For LT electrolyte application, decreasing the interphase impedance is particularly important since it can improve the overall kinetics of the cell and offset the negative effects on transport property caused by the LT.”

For low-temperature application, the high viscosity of high-concentration electrolyte is a problem.

“However, when it comes to LT application, the high viscosity of high concentration electrolyte (HCE) is a problem.”

The high impedance of oxalate-derived SEI causes a problem for low-temperature electrolytes.

“However, in those cases, the high impedance of oxalate-derived SEI causes another problem for LT electrolytes.”

Fluorinated solvents can form less resistive SEI compared with their non-fluorinated counterparts.

“This is because fluorinated solvents can form less resistive SEI compared with their non-fluorinated counterparts.”

In contrast to polymer-like SEIs formed in conventional carbonate electrolytes with high impedance, a ceramic-like SEI with high Li mobility through grain boundaries was generated on Li foil using the FM electrolyte, enabling facile Li transportation through the interphase.

“In contrast to the polymer-like SEIs formed in conventional carbonate electrolytes with high impedance, a ceramic-like SEI with high Li mobility through the grain boundaries was generated on Li foil using the FM electrolyte, enabling facile Li transportation through the interphase.”

Most ethers solvate Li+ so tightly that the formed solvation cage would not release coordinated Li+ easily.

“the reality is that most of the ethers solvate Li + so tightly that the formed solvation cage would not release the coordinated Li + easily.”

Salts with large anions and a high degree of fluorination, such as PF6-, BF4-, TFSI-, and FSI-, are easier to dissociate than those with small anions.

“For these two reasons, salts with large anions and high degree of fluorination, such as PF 6 -, BF 4 -, TFSI -and FSI -, are easier to dissociate than those with small anions.”

McDowell reported that Coulombic efficiency of Li metal anodes can be significantly improved at low temperatures (-60 °C) by adding EC or FEC in an electrolyte of 0.8 M LiTFSI and 0.2 M LiNO3 in DOL-DME solvents to tailor solvation structure and SEI properties.

“McDowell [56] reported that the Coulombic efficiency of Li metal anodes can be significantly improved at LTs (-60 °C) by adding EC or FEC in the electrolyte of 0.8 M LiTFSI and 0.2 M LiNO 3 in DOL-DME solvents to tailor the solvation structure and SEI properties.”

• cites [56] Thenuwara, A.C., Shetty, P.P., Kondekar, N., et al.: Efficient low-temperature cycling of lithium metal anodes by tailoring the solid-electrolyte interphase. ACS Energy Lett. 5, 2411–2420 (2020). https://doi.org/10.1021/acsenergylett.0c01209 sourceNot checked — no full text of the source

Acetonitrile must be used together with another solvent or additive that can form protective solid electrolyte interphases to obtain reversible cycling in lithium-ion full cells.

“Therefore, AN must be used together with other solvent/ additive that can form protective SEIs to obtain the reversible cycling in lithium-ion full cells.”

The role of LiF in SEIs and its impact on ionic transportation remains a controversial topic.

“Therefore, the role of LiF in SEIs and its impact on the ionic transportation remains a controversial topic, with more thorough studies needed”

Reducing the intrinsic solvating power of solvents by fluorination improves the low-temperature performance of electrolytes.

“which is another essential strategy to improve the LT performance of electrolytes by reducing the intrinsic solvating power of solvents.”

• cites [127] Wang, Z.X., Sun, Z.H., Shi, Y., et al.: Ion-dipole chemistry drives rapid evolution of Li ions solvation sheath in low-temperature Li batteries. Adv. Energy Mater. 11, 2100935 (2021). https://doi.org/10.1002/aenm.202100935 sourceNot checked — no full text of the source

The improved low-temperature electrochemical performance by using PhMs additive was ascribed to decreased interphase impedance.

“Recently, the improved LT electrochemical performance by using phenyl methanesulfonate (PhMs) additive [131] was ascribed to the decreased interphase impedance as well.”

• cites [131] Lin, Y.C., Yue, X.P., Zhang, H., et al.: Using phenyl methanesulfonate as an electrolyte additive to improve performance of LiNi0.5Co0.2Mn0.3O2/graphite cells at low temperature. Electrochimica Acta 300, 202–207 (2019). https://doi.org/10.1016/j.electacta.2019.01.120 sourceNot checked — no full text of the source

The high ionic conductivity of DTD-derived SEIs observed in this work agrees with previous literature, where it was attributed to reduction products such as Li2SO3 and ROSO2Li.

“The high ionic conductivity of DTDderived SEIs observed in this work is in good agreement with the results previously reported in the literature by other groups, in which it was attributed to the reduction products such as Li 2 SO 3 and ROSO 2 Li [111].”

• cites [111] Li, X.C., Yin, Z.L., Li, X.H., et al.: Ethylene sulfate as film formation additive to improve the compatibility of graphite electrode for lithium-ion battery. Ionics 20, 795–801 (2014). https://doi.org/10.1007/s11581-013-1036-5 sourceNot checked — no full text of the source

Metallic Li plating is a critical problem for Li-ion cells operating at low temperatures, occurring when cells are charged at low temperatures, at excessive rates, and/or at high voltage.

“One critical problem of Li-ion cells operating at LTs is the metallic Li plating, which occurs when cells are charged at LTs, at excessive rates, and/or at high voltage.”

The Li+-dipole interaction strength decreases from 1.90 to 1.66 eV and then to 1.44 eV as the fluorination degree increases from EC to FEC to DFEC.

“Experimental and calculation results demonstrated that the Li + -dipole interaction strength gradually decreases from 1.90 to 1.66 eV and then to 1.44 eV with an increase of the fluorination degree from EC to FEC and DFEC, respectively.”

• cites [127] Wang, Z.X., Sun, Z.H., Shi, Y., et al.: Ion-dipole chemistry drives rapid evolution of Li ions solvation sheath in low-temperature Li batteries. Adv. Energy Mater. 11, 2100935 (2021). https://doi.org/10.1002/aenm.202100935 sourceNot checked — no full text of the source

The DFEC-based electrolyte displays six times faster ion desolvation rates than the EC-based electrolyte at -20 °C.

“the DFEC-based electrolyte displays six times faster ion desolvation rates than that of the EC-based electrolyte at -20 °C.”

• cites [127] Wang, Z.X., Sun, Z.H., Shi, Y., et al.: Ion-dipole chemistry drives rapid evolution of Li ions solvation sheath in low-temperature Li batteries. Adv. Energy Mater. 11, 2100935 (2021). https://doi.org/10.1002/aenm.202100935 sourceNot checked — no full text of the source

The cell using 1.0 M (0.98 M LiBF4 + 0.02 M LiBOB) in 1:1:3 PC:EC:EMC delivered 83% and 63% of RT discharge capacity at -30 and -40 °C, respectively.

“The cell using the electrolyte of 1.0 M (0.98 M LiBF 4 + 0.02 M LiBOB) in 1:1:3 PC:EC:EMC was able to deliver 83% and 63% of RT discharge capacity at -30 and -40 °C, respectively (Fig. 16b).”

• cites [99] Zhang, S.S., Xu, K., Jow, T.R.: Enhanced performance of Li-ion cell with LiBF4-PC based electrolyte by addition of small amount of LiBOB. J. Power Sources 156, 629–633 (2006). https://doi.org/10.1016/j.jpowsour.2005.04.023 sourceNot checked — no full text of the source

The discovery of SEI LiF clarified how an ionic insulator like bulk LiF can be a critical component for good SEI.

“This discovery clarified the puzzle on how an ionic insulator like (bulk) LiF can be a critical component for good SEI.”

LiBOB introduced into the LiBF4-PC:EC:EMC electrolyte forms an SEI with semicarbonate-like products.

“Hence, LiBOB was introduced into this electrolyte system, which forms an SEI with semicarbonate-like products (Fig. 16a) [99].”

• cites [99] Zhang, S.S., Xu, K., Jow, T.R.: Enhanced performance of Li-ion cell with LiBF4-PC based electrolyte by addition of small amount of LiBOB. J. Power Sources 156, 629–633 (2006). https://doi.org/10.1016/j.jpowsour.2005.04.023 sourceNot checked — no full text of the source

New tools will help gain more fundamental understanding of SEIs and provide insights on SEI chemistry that have been impossible to study using traditional characterization techniques.

“The results of the above examples demonstrated that new tools will be able to help us to gain more fundamental understanding of SEIs and provide us valuable insights on the SEI chemistry that have been impossible to study using the traditional characterization techniques.”

The electrolyte using 1,3-PS delivered even lower capacity at low temperature compared to the electrolyte without additive.

“The electrolyte using 1,3-PS delivered even lower capacity at LT compared to the electrolyte without additive.”

• cites [110] Wu, Z.L., Li, S.G., Zheng, Y.Z., et al.: The roles of sulfur-containing additives and their working mechanism on the temperature-dependent performances of Li-ion batteries. J. Electrochem. Soc. 165, A2792–A2800 (2018). https://doi.org/10.1149/2.0331811jes sourceNot checked — no full text of the source

NMC811-Li cells with DFEC-based electrolyte displayed better fast-charge capability and long-term cyclability from -30 to 25 °C compared to cells with EC-based electrolyte.

“NMC811-Li cells with the DFECbased electrolyte displayed better fast-charge capability and long-term cyclability in the temperature range from -30 to 25 °C compared to that with the EC-based electrolyte.”

• cites [127] Wang, Z.X., Sun, Z.H., Shi, Y., et al.: Ion-dipole chemistry drives rapid evolution of Li ions solvation sheath in low-temperature Li batteries. Adv. Energy Mater. 11, 2100935 (2021). https://doi.org/10.1002/aenm.202100935 sourceNot checked — no full text of the source

LiDFBOP additive decreased interface resistance of graphite anodes at 0 °C from 1935 to 820 Ω.

“resulting in the decreased interface resistance (the sum of R sei and R ct ) of graphite anodes at 0 °C [from 1 935 to 820 Ω after adding 0.5% LiDFBOP in the baseline electrolyte (1 M LiPF 6 in PC:EMC, 1:1 in weight ratio)] (Fig. 19b).”

• cites [143] Liao, B., Li, H.Y., Xu, M.Q., et al.: Designing low impedance interface films simultaneously on anode and cathode for high energy batteries. Adv. Energy Mater. 8, 1800802 (2018). https://doi.org/10.1002/aenm.201800802 sourceNot checked — no full text of the source

EMI-BF4 additive-derived surface films prevented continuous reaction between electrolyte and electrodes, keeping structural integrity of NCM cathode and graphite anode.

“The additive-derived surface films prevented the continuous reaction between the electrolyte and electrodes, keeping the structural integrity of NCM cathode and graphite anode.”

• cites [144] Wang, W.L., Yang, T.X., Li, S., et al.: 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4) as an ionic liquid-type electrolyte additive to enhance the low-temperature performance of LiNi0.5Co0.2Mn0.3O2/graphite batteries. Electrochimica Acta 317, 146–154 (2019). https://doi.org/10.1016/j.electacta.2019.05.027 sourceNot checked — no full text of the source

An SEI with a thinner organic layer is beneficial for reducing diffusion limitation.

“The SEI with a thinner organic layer is beneficial for reducing diffusion limitation.”

Adding VC or LiBOB to the baseline electrolyte resulted in worsened Li plating.

“In contrast, adding VC or LiBOB to the baseline electrolyte resulted in worsened Li plating.”

SEI and CEI surface films containing more LiF and less Li2CO3 resulted in higher ionic conductivity at both room and low temperatures.

“Besides the protection nature, the SEI and CEI surface films containing more LiF and less Li 2 CO 3 resulted in higher ionic conductivity at both room and LTs based on EIS results.”

• cites [144] Wang, W.L., Yang, T.X., Li, S., et al.: 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4) as an ionic liquid-type electrolyte additive to enhance the low-temperature performance of LiNi0.5Co0.2Mn0.3O2/graphite batteries. Electrochimica Acta 317, 146–154 (2019). https://doi.org/10.1016/j.electacta.2019.05.027 sourceNot checked — no full text of the source

There are competing arguments in the literature that improved battery performance at low temperatures was obtained by decreasing inorganic species including LiF in SEIs.

“there are competing arguments regarding the effects of inorganic components of SEIs in the literature claiming that improved battery performance was obtained at LTs by decreasing inorganic species including LiF in SEIs.”

• cites [129] Yang, T.X., Fan, W.Z., Wang, C.Y., et al.: 2,3,4,5,6-Pentafluorophenyl methanesulfonate as a versatile electrolyte additive matches LiNi0.5Co0.2Mn0.3O2/graphite batteries working in a wide-temperature range. ACS Appl. Mater. Interfaces 10, 31735–31744 (2018). https://doi.org/10.1021/acsami.8b04743 sourceNot checked — no full text of the source
• cites [130] Guo, R.D., Che, Y.X., Lan, G.Y., et al.: Tailoring low-temperature performance of a lithium-ion battery via rational designing interphase on an anode. ACS Appl. Mater. Interfaces 11, 38285–38293 (2019). https://doi.org/10.1021/acsami.9b12020 sourceNot checked — no full text of the source
• cites [131] Lin, Y.C., Yue, X.P., Zhang, H., et al.: Using phenyl methanesulfonate as an electrolyte additive to improve performance of LiNi0.5Co0.2Mn0.3O2/graphite cells at low temperature. Electrochimica Acta 300, 202–207 (2019). https://doi.org/10.1016/j.electacta.2019.01.120 sourceNot checked — no full text of the source

The LiPO2F2-derived SEI has much lower ionic resistance than baseline electrolyte at 0 °C.

“This SEI with rich inorganic species has much lower ionic resistance compared to that of baseline electrolyte at 0 °C (Fig. 18a).”

• cites [142] Yang, B.W., Zhang, H., Yu, L., et al.: Lithium difluorophosphate as an additive to improve the low temperature performance of LiNi0.5Co0.2Mn0.3O2/graphite cells. Electrochimica Acta 221, 107–114 (2016). https://doi.org/10.1016/j.electacta.2016.10.037 sourceNot checked — no full text of the source

Capacity retention after 200 cycles at 0 °C and C/5 increased from 57% to 94% after adding LiDFBOP.

“The capacity retention after 200 cycles was increased from 57% to 94% at 0 °C and C/5 rate after adding LiDFBOP (Fig. 19c).”

• cites [143] Liao, B., Li, H.Y., Xu, M.Q., et al.: Designing low impedance interface films simultaneously on anode and cathode for high energy batteries. Adv. Energy Mater. 8, 1800802 (2018). https://doi.org/10.1002/aenm.201800802 sourceNot checked — no full text of the source

High abundance of LiH in the SEI was confirmed by XRD.

“High abundance of LiH was confirmed by XRD.”

• cites [163] Shadike, Z., Lee, H., Borodin, O., et al.: Identification of LiH and nanocrystalline LiF in the solid-electrolyte interphase of lithium metal anodes. Nat. Nanotechnol. 16, 549–554 (2021). https://doi.org/10.1038/s41565-020-00845-5 sourceNot checked — no full text of the source

LiDFBOP additive improved charge/discharge performance at low temperatures by increasing ionic conductivity on both sides.

“Therefore, with the increased ionic conductivity on both sides, the charge/discharge performance at LTs was significantly improved by introducing LiDFBOP additive.”

• cites [143] Liao, B., Li, H.Y., Xu, M.Q., et al.: Designing low impedance interface films simultaneously on anode and cathode for high energy batteries. Adv. Energy Mater. 8, 1800802 (2018). https://doi.org/10.1002/aenm.201800802 sourceNot checked — no full text of the source

1%-5% LiBOB was sufficient to enable graphite anode cycling reversibly in 1.0 M LiBF4 in 1:1:3 PC:EC:EMC and 1.0 M LiBF4 in 1:1 PC:EC while maintaining excellent cycling performance at low temperatures.

“It was demonstrated that 1%-5% (molar percentage) LiBOB was sufficient to enable graphite anode cycling reversibly in 1.0 M LiBF 4 in 1:1:3 PC:EC:EMC and 1.0 M LiBF 4 in 1:1 PC:EC, respectively, while maintaining the excellent cycling performance of LiBF 4 -PC-based electrolytes at LTs.”

• cites [99] Zhang, S.S., Xu, K., Jow, T.R.: Enhanced performance of Li-ion cell with LiBF4-PC based electrolyte by addition of small amount of LiBOB. J. Power Sources 156, 629–633 (2006). https://doi.org/10.1016/j.jpowsour.2005.04.023 sourceNot checked — no full text of the source

LiDFBOP is electrochemically reduced prior to carbonate solvents.

“According to the electron affinity calculation and experimental results, LiDFBOP is electrochemically reduced prior to carbonate solvents 19a.”

• cites [143] Liao, B., Li, H.Y., Xu, M.Q., et al.: Designing low impedance interface films simultaneously on anode and cathode for high energy batteries. Adv. Energy Mater. 8, 1800802 (2018). https://doi.org/10.1002/aenm.201800802 sourceNot checked — no full text of the source

The improved performance with PFPMS was attributed to a lower-resistance interphase, resulting in better ionic conductivity at low temperatures in full cells.

“This improved performance was attributed to the as-formed lower resistance interphase in PFPMS electrolytes compared to VC-additive and no-additive systems, resulting in better ionic conductivity at LTs in full cells.”

• cites [129] Yang, T.X., Fan, W.Z., Wang, C.Y., et al.: 2,3,4,5,6-Pentafluorophenyl methanesulfonate as a versatile electrolyte additive matches LiNi0.5Co0.2Mn0.3O2/graphite batteries working in a wide-temperature range. ACS Appl. Mater. Interfaces 10, 31735–31744 (2018). https://doi.org/10.1021/acsami.8b04743 sourceNot checked — no full text of the source

One problem of using FI as additive is low initial Coulombic efficiency, caused by Li consumption through SEI formation during the first cycle.

“One problem of using FI as additive is the low initial Coulombic efficiency, caused by the consumption of Li through SEI formation during the first cycle.”

• cites [128] Shi, J.L., Ehteshami, N., Ma, J.L., et al.: Improving the graphite/electrolyte interface in lithium-ion battery for fast charging and low temperature operation: fluorosulfonyl isocyanate as electrolyte additive. J. Power Sources 429, 67–74 (2019). https://doi.org/10.1016/j.jpowsour.2019.04.113 sourceNot checked — no full text of the source

It is possible to avoid Li plating by selecting anodes with higher potential than graphite such as metal oxides or alloy anodes.

“It is possible to avoid Li plating by selecting anodes with higher potential than graphite such as metal oxides or alloy anodes [170].”

• cites [170] Lin, X.K., Khosravinia, K., Hu, X.S., et al.: Lithium plating mechanism, detection, and mitigation in lithium-ion batteries. Prog. Energy Combust. Sci. 87, 100953 (2021). https://doi.org/10.1016/j.pecs.2021.100953 sourceNot checked — no full text of the source