Synergetic V2O5•3H2O/Metallic VS2 Nanocomposites Endow a Long Life and High Rate Capability to Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries have attracted significant attention due to their cost effectiveness, high safety, and high ionic conductivity. However, the cathodes usually suffer from a short cycle life or low capacity. Combing the high conductivity of vanadium sulfide and high chemical stability of vanadium oxides, a biphasic V2O5 center dot 3H(2)O@VS2 (SVO) nanocomposite cathode is proposed for effective zinc-ion batteries. The structural water in V2O5 center dot 3H(2)O as a shielding layer can weaken the electrostatic interactions; density functional theory calculation verifies the metallic character of VS2, which could improve conductivity of the composite. Besides, the morphology transformation during the cycling process offers extra transport routes and increased active sites. Under the electrochemical synergism between V2O5 center dot 3H(2)O and VS2 and the shielding effect of ethylene glycol in hybrid electrolyte on the Zn surface, the novel SVO//Zn system realizes a durable structure stability, ultralong cycle life, impressive rate capability, and favorable low-temperature adaptability. The cathode delivers a specific capacity of 290 mA h g(-1) at 0.5 A g(-1), realizes a long-term lifespan of 6700 cycles at 5 A g(-1), and possesses a meritorious rate capability of 202 mA h g(-1) at 10 A g(-1) and low-temperature adaptability at -20 and 0 degrees C. The assembled Zn//Zn symmetrical cell demonstrates preferable Zn plating/stripping reversibility. This work could provide a new robust cathode with a biphasic structure for aqueous zinc-ion batteries.