Analysis of the discharge/charge mechanism in VS4 positive electrode material

Among transition metal sulfides, VS4 is a promising candidate material for the positive electrode in rechargeable Li/metal-sulfide batteries, due to its long, flat plateau at about 2.0 V and its high theoretical capacity (1195 mAh g−1). In this study, we prepared VS4 positive electrode material by heating in a sealed tube, and studied local structural changes during charge/discharge cycles via X-ray absorption and scattering spectroscopies, focusing on the reversibility of VS4. The findings reveal that a VS4-like local structure was formed in the first cycle, and that subsequent cycles showed reversible changes.