A zero fading sodium ion battery: High compatibility microspherical patronite in ether-based electrolyte

Abstract

The state-of-the-art vanadium sulfide VS4, a linear-chain compound of disulfide anions [S2]2– with vanadium atoms, has proved to have high potential in the field of secondary batteries due to its unique properties. Possessing qualities of a remarkable theoretical capacity, high electrical conductivity, natural abundance, and environmental friendliness, VS4 is determined to be a significant candidate for new high-energy storage systems. However, the fundamental drawbacks of capacity-fading issues, such as structure collapse or active-material loss during repeated cycling, critically limit the practical applications of VS4. Overcoming those obstacles, the present work used a design strategy to develop a VS4 electrode with a unique secondary morphology and utilize it in combination with a specific choice of an ether-based electrolyte for sodium ion batteries. This pristine VS4 displayed exceptional rate performance with excellent and stable cycling ability. An important finding in this study is the presence of a highly protective solid electrolyte interphase layer along the surface of the primary particle, which limits the polysulfide dissolution and hence preserves the active material during the reaction with sodium, as observed using ex-situ potentio-electrochemical impedance spectroscopy examinations. The detailed complex redox process of VS4/Na was also elucidated by ex situ X-ray photoelectron spectroscopy.