VS₄ with High Crystallinity and Controlled Morphology Enabling Superior Lithium Storage Performance

Due to the rapid increase of electromobiles and the wide application of energy storage devices, there is a sharp increase in the requirement for lithium-ion batteries (LIBs) that offer both high energy and power density. But the commercial graphite with low theoretical capacity as anode materials in LIBs cannot satisfy the developing demands. As a transition metal sulfide, VS₄ has a unique one-dimensional crystal structure and high sulfur content, providing distinctive energy storage properties. However, the large volume change and slow reaction kinetics of VS₄ result in inferior rate capability and cycling performance during the charge and discharge process. In this work, VS₄ with chestnut involucre and water grass-like morphology are synthesized successfully via a solvothermal reaction without using templates. Chestnut involucre-VS₄ appears as a spherical surface covered by one-dimensional nanorods with high crystallinity. The one-dimensional nanorods release the maximum active sites and shorten the Li⁺ transportation distance. The space between the nanorods provides adequate space to alleviate volume expansion, which results in the stable structure. The high crystallinity leads to the fast Li⁺ transportation characteristic which enhances the fast electrochemical reaction kinetics. Thus, the chestnut involucre-VS₄ exhibits superior rate capability and specific capacity compared to water grasss-VS₄. Chestnut involucre-VS₄ presents the first loop Coulombic efficiency of 71.5% and a specific capacity of ∼703 mA h g^-1 after 100 cycles at 100 mA g^-1. Even when subjected to a discharge rate of 15.8 min at 2000 mA g^-1, chestnut involucre-VS₄ demonstrates an energy density of 503.8 W h kg^-1 and a corresponding high power density of 1937.8 W kg^-1. This work affords an effective perspective for the structural design of other transition metal sulfides used as energy storage materials.