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.
Highlights
Our results suggest that 3D-networked NiCo2S4 nanosheet arrays (NSAs)/carbon cloth composites are a promising material for electrodes in high-performance lithium-ion batteries
Our work demonstrates that the direct growth of NiCo2S4 NSAs on carbon cloth enables their use as anodes in lithium-ion batteries (LIBs) without requiring the addition of carbon additives and binders
The NiCo precursor NSAs were converted to 3D-networked and mesoporous NiCo2S4 NSAs with well-retained morphology via a simple sulfurization treatment, and densely packed, highly ordered NiCo2S4 NSAs were formed on the cloth, as shown in Figures 1b and c
Summary
Rechargeable lithium-ion batteries (LIBs) are the most widely used electrochemical energy storage devices because of their inherent advantages including high energy density, long life span, lack of memory effect and environmental nontoxicity.[1,2,3] The increasing applications of LIBs in daily electronic devices—along with industry demands for further improvement in energy density, durability, rate capability and safety—have driven the development of new electrode materials and new electrode structures.[4,5,6,7] Among the great variety of anode materials studied, metal oxides (MOs) and metal sulfides (MSs) such as Co3O4,8 SnO2,9 Fe3O4,10 V2O5,11 FeS2,12 NiS2,13 MoS214 and WS2 15 comprise an important class of materials that can be charged and discharged through redox reactions. The necessary addition of conductive additives and binders inevitably lessens overall energy storage capacity, and binders in particular hinder electron transport from MS nanostructures to the electron collector, limiting their practical applications.[16,17]
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