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Cited by 132Supercapacitor Materials and FabricationAqueous and Flow BatteriesMXene and MAX Phase Materials

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Flexible and Self-Healing Aqueous Supercapacitors for Low Temperature Applications: Polyampholyte Gel Electrolytes with Biochar Electrodes

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Li, Xinda, Liu, Li, Wang, Xianzong, Ok, Yong Sik, Elliott, Janet A. W., Chang, Scott X., Chung, Hyun-Joong·2017·Scientific Reports
DOI 10.1038/s41598-017-01873-3PMC PMC5431763
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Abstract

A flexible and self-healing supercapacitor with high energy density in low temperature operation was fabricated using a combination of biochar-based composite electrodes and a polyampholyte hydrogel electrolyte. Polyampholytes, a novel class of tough hydrogel, provide self-healing ability and mechanical flexibility, as well as low temperature operation for the aqueous electrolyte. Biochar is a carbon material produced from the low-temperature pyrolysis of biological wastes; the incorporation of reduced graphene oxide conferred mechanical integrity and electrical conductivity and hence the electrodes are called biochar-reduced-graphene-oxide (BC-RGO) electrodes. The fabricated supercapacitor showed high energy density of 30 Wh/kg with ~90% capacitance retention after 5000 charge–discharge cycles at room temperature at a power density of 50 W/kg. At −30 °C, the supercapacitor exhibited an energy density of 10.5 Wh/kg at a power density of 500 W/kg. The mechanism of the low-temperature performance excellence is likely to be associated with the concept of non-freezable water near the hydrophilic polymer chains, which can motivate future researches on the phase behaviour of water near polyampholyte chains. We conclude that the combination of the BC-RGO electrode and the polyampholyte hydrogel electrolyte is promising for supercapacitors for flexible electronics and for low temperature environments.

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Crossref · 10.1038/s41598-017-01873-3

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Figures

Figure 1 Schematic of supercapacitor (SC-PA) fabrication. (a) As-received biochar (BC-pristine) was oxidized (BC-treated) and dispersed in a graphene oxide solution. Subsequent solvent evaporation and graphene oxide reduction result in a consolidated electrode (BC-RGO) with high electrical conductivity. (b) The BC-RGO electrodes are supported on a Kapton substrate. (c) A polyampholyte hydrogel is synthesized on the BC-RGO electrodes by photo-initiated random copolymerization of NaSS and MPTC. (d) The electrolyte is dialyzed in 3 M KOH solution. (e) Compressing the dialyzed electrolyte/electrode pair with the top BC-RGO electrode will make a symmetric supercapacitor. (f) Three symmetric supercapacitors are encapsulated in silicone to light a green LED in (g).
Figure 1 Schematic of supercapacitor (SC-PA) fabrication. (a) As-received biochar (BC-pristine) was oxidized (BC-treated) and dispersed in a graphene oxide solution. Subsequent solvent evaporation and graphene oxide reduction result in a consolidated electrode (BC-RGO) with high electrical conductivity. (b) The BC-RGO electrodes are supported on a Kapton substrate. (c) A polyampholyte hydrogel is synthesized on the BC-RGO electrodes by photo-initiated random copolymerization of NaSS and MPTC. (d) The electrolyte is dialyzed in 3 M KOH solution. (e) Compressing the dialyzed electrolyte/electrode pair with the top BC-RGO electrode will make a symmetric supercapacitor. (f) Three symmetric supercapacitors are encapsulated in silicone to light a green LED in (g).CC BY · PubMed Central
Figure 2 (a) The SEM image of as-received biochar (BC-pristine) and (b) a magnified image of the small region identified by the white rectangular box in (a). (c) The SEM image of oxidized biochar (BC-treated) and (d) a magnified image of the small region identified in (c). (e) The SEM image of the top of a BC-RGO electrode and (f) a magnified image of the small region identified in (e). (g) The SEM image of the BC-RGO cross section and (h) a magnified image of the small region identified in (g).
Figure 2 (a) The SEM image of as-received biochar (BC-pristine) and (b) a magnified image of the small region identified by the white rectangular box in (a). (c) The SEM image of oxidized biochar (BC-treated) and (d) a magnified image of the small region identified in (c). (e) The SEM image of the top of a BC-RGO electrode and (f) a magnified image of the small region identified in (e). (g) The SEM image of the BC-RGO cross section and (h) a magnified image of the small region identified in (g).CC BY · PubMed Central
Figure 3 (a) Nitrogen adsorption isotherm according to the BET model and (b) Pore size distribution (represented as differential pore volume plotted against pore width) derived from (a), calculated with the NLDFT model.
Figure 3 (a) Nitrogen adsorption isotherm according to the BET model and (b) Pore size distribution (represented as differential pore volume plotted against pore width) derived from (a), calculated with the NLDFT model.CC BY · PubMed Central
Figure 4 (a) Cyclic voltammetry (CV) and (b) galvanostatic charging–discharging (GCD) profiles of symmetric SC-PA KOH (inset: specific capacitance verses current density). The arrow in (a) indicates the direction of increasing scanning rate. (c) Cycle test of the fabricated supercapacitor (SC-PA). The inset presents first and last three galvanostatic charging–discharging (GCD) profiles.
Figure 4 (a) Cyclic voltammetry (CV) and (b) galvanostatic charging–discharging (GCD) profiles of symmetric SC-PA KOH (inset: specific capacitance verses current density). The arrow in (a) indicates the direction of increasing scanning rate. (c) Cycle test of the fabricated supercapacitor (SC-PA). The inset presents first and last three galvanostatic charging–discharging (GCD) profiles.CC BY · PubMed Central
Figure 5 (a) Fabricated supercapacitor (SC-PA) temperature dependence of cyclic voltammetry (CV) profiles at a scan rate of 20 mV s−1. The arrow indicates the direction of increasing temperatures. (b) Galvanostatic charging–discharging (GCD) profiles at a current density of 1 A g−1. The inset indicates calculated specific capacitance with respect to temperature change. (c) A differential scanning calorimetry (DSC) result of 3 M KOH-containing polyampholyte hydrogel with increasing temperature compared with the change in conductivity as a function of temperature.
Figure 5 (a) Fabricated supercapacitor (SC-PA) temperature dependence of cyclic voltammetry (CV) profiles at a scan rate of 20 mV s−1. The arrow indicates the direction of increasing temperatures. (b) Galvanostatic charging–discharging (GCD) profiles at a current density of 1 A g−1. The inset indicates calculated specific capacitance with respect to temperature change. (c) A differential scanning calorimetry (DSC) result of 3 M KOH-containing polyampholyte hydrogel with increasing temperature compared with the change in conductivity as a function of temperature.CC BY · PubMed Central
Figure 6 Photographs of (a) pristine, (b) bent, (c) broken, and (d) self-healed supercapacitor (SC-PA). (c,d) show the procedure for the perpendicular cut. The procedure for the planar cut is described in supporting information. (e) Cyclic voltammetry (CV) profile of pristine, bent and self-healed (perpendicular and planar cuts) SC-PAs at a scan rate of 20 mV s−1. (f) Schematic illustration of polyampholyte hydrogel self-healing for the perpendicular cut.
Figure 6 Photographs of (a) pristine, (b) bent, (c) broken, and (d) self-healed supercapacitor (SC-PA). (c,d) show the procedure for the perpendicular cut. The procedure for the planar cut is described in supporting information. (e) Cyclic voltammetry (CV) profile of pristine, bent and self-healed (perpendicular and planar cuts) SC-PAs at a scan rate of 20 mV s−1. (f) Schematic illustration of polyampholyte hydrogel self-healing for the perpendicular cut.CC BY · PubMed Central

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  1. Khodakovsky, I. L., Mironenko, M. V., Chernysheva, I. V. and Pokrovsky, O. S. Liquid radioactive waste solutions. In Contaminant hydrology: cold regions modelling (eds Grant, S. A. & Iskandar, I. K.) (CRC Press, 2000).

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Metadata

Authors
Li, X., Liu, L., Wang, X., Ok, Y. S., Elliott, J. A. W., Chang, S. X., & Chung, H.-J.
Affiliations
  • University of Alberta (CA)
  • Kangwon National University (KR)
Corresponding author
Chung, Hyun-Joong
ORCID
Venue
Scientific Reports
Publisher
Springer Science and Business Media LLC
Published
2017-05-10
Volume
7
Issue
1
Pages
1685-1685
ISSN
2045-2322 (ISSN-L)
DOI
10.1038/s41598-017-01873-3
PMC
PMC5431763
OpenAlex
W2610557054
Cited by
132
References
52
Citations by year
2026: 7 · 2025: 8 · 2024: 3 · 2023: 18 · 2022: 17 · 2021: 15 · 2020: 27 · 2019: 18 · 2018: 15 · 2017: 4
FWCI
5.95
Type
journal article
Language
en
Open access
Licence
Locations
  • Scientific Reports (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • University of Alberta
  • Canada Research Chairs
  • Canadian Institutes of Health Research (140186_1)
  • Natural Sciences and Engineering Research Council of Canada (435914, CHRPJ 478519, RGPIN 435914)
Topics
  • Physical Sciences › Materials Science › Electronic, Optical and Magnetic Materials › Supercapacitor Materials and Fabrication
  • Physical Sciences › Engineering › Electrical and Electronic Engineering › Aqueous and Flow Batteries
  • Physical Sciences › Materials Science › Materials Chemistry › MXene and MAX Phase Materials
Keywords
aqueous supercapacitors, self-healing hydrogels, biochar electrodes, reduced graphene oxide, low-temperature performance, flexible energy storage, non-freezable water, energy density, cycling stability, flexible electronics

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