Vanadium disulfide flakes with nanolayered titanium disulfide coating as cathode materials in lithium-ion batteries

Lu Li,Jian Shi,Aaron Littlejohn,Congli Sun,Su-Fei Shi,Yanwen Chen,Tianmeng Wang,Yu Xiang,Stephen F Bartolucci,Zhaodong Li,Vincent Meunier,Gwo-Ching Wang,Anthony Yoshimura,Nikhil Koratkar,Prateek Hundekar,Zhizhong Chen

doi:10.1038/s41467-019-09400-w

Abstract

Unlike the vast majority of transition metal dichalcogenides which are semiconductors, vanadium disulfide is metallic and conductive. This makes it particularly promising as an electrode material in lithium-ion batteries. However, vanadium disulfide exhibits poor stability due to large Peierls distortion during cycling. Here we report that vanadium disulfide flakes can be rendered stable in the electrochemical environment of a lithium-ion battery by conformally coating them with a ~2.5 nm thick titanium disulfide layer. Density functional theory calculations indicate that the titanium disulfide coating is far less susceptible to Peierls distortion during the lithiation-delithiation process, enabling it to stabilize the underlying vanadium disulfide material. The titanium disulfide coated vanadium disulfide cathode exhibits an operating voltage of ~2 V, high specific capacity (~180 mAh g−1 @200 mA g−1 current density) and rate capability (~70 mAh g−1 @1000 mA g−1), while achieving capacity retention close to 100% after 400 charge−discharge steps.

Highlights

Unlike the vast majority of transition metal dichalcogenides which are semiconductors, vanadium disulfide is metallic and conductive
A carbon nanotube (CNT) film was selected as the current collector substrate because of its light weight, high conductivity and flexibility
An examination of the junction (Supplementary Fig. 3) between the VS2 and CNT substrate indicates that the VS2 platelets are embedded into the CNT current collector

Summary

Introduction

Unlike the vast majority of transition metal dichalcogenides which are semiconductors, vanadium disulfide is metallic and conductive This makes it promising as an electrode material in lithium-ion batteries. VS2-based electrodes could in principle be deployed in lithium (Li)-ion batteries without requiring a high content of conductive carbon additives or conductive binders, which are inactive materials. In spite of this promise, the realization of VS2based electrodes[7,8,9,10,11] in Li-ion batteries has been limited by its poor stability, which leads to low cycle life. First-principles density functional theory (DFT) calculations indicate that unlike

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Results

Conclusion