Three-dimensional-networked NiCo2S4 nanosheet array/carbon cloth anodes for high-performance lithium-ion batteries

Abstract

We present the design and synthesis of three-dimensional (3D)-networked NiCo2S4 nanosheet arrays (NSAs) grown on carbon cloth along with their novel application as anodes in lithium-ion batteries. The relatively small (~60%) volumetric expansion of NiCo2S4 nanosheets during the lithiation process was confirmed by in situ transmission electron microscopy and is attributed to their mesoporous nature. The 3D network structure of NiCo2S4 nanosheets offers the additional advantages of large surface area, efficient electron and ion transport capability, easy access of electrolyte to the electrode surface, sufficient void space and mechanical robustness. The fabricated electrodes exhibited outstanding lithium-storage performance including high specific capacity, excellent cycling stability and high rate of performance. A reversible capacity of ~1275 mAh g−1 was obtained at a current density of 1000 mA g−1, and the devices retained ~1137 mAh g−1 after 100 cycles, which is the highest value reported to date for electrodes made of metal sulfide nanostructures or their composites. Our results suggest that 3D-networked NiCo2S4 NSA/carbon cloth composites are a promising material for electrodes in high-performance lithium-ion batteries. Three-dimensional networks of NiCo2S4 nanosheets on carbon cloth substrates are highly promising as anodes for lithium-ion batteries. Nanostructures made from metal sulphides make attractive anode materials for lithium-ion batteries except they tend to undergo large volume changes during electrochemical reactions, which lead to reduced capacity and poor cycling stability. Now, Wenjun Zhang and colleagues at City University of Hong Kong and Donghua University in Shanghai have demonstrated that NiCo2S4 nanosheet arrays on carbon cloths expand by only about 60% during lithiation as a result of their mesoporous structure. Furthermore, the arrays exhibited the highest specific capacity of any metal sulphide electrode reported to date as well as an excellent cycling stability and a high rate capability. They are thus excellent candidates for anode materials in high-performance lithium-ion batteries. 3D Networked NiCo2S4 nanosheet array/carbon cloth composites are synthesized by a facile hydrothermal reaction and subsequent sulfurization process, and the rational material composition and structure design lead to their outstanding overall performance as an anode material in lithium-ion batteries.