Novel synthesis of Zn2(V3O8)2 and its application to aqueous zinc-ion batteries

Aqueous zinc-ion batteries, with their high capacity and stable zinc anode, are a promising choice for large-scale energy storage systems. To fabricate promising cathode materials for aqueous zinc-ion batteries, the VO2(M)-C composite was designed and synthesized in this work by a simple hydrothermal reaction and high-temperature calcination. The VO2(M)-C composite undergoes an in situ electrochemical conversion during the initial cycle of activation when it is charged to 1.4-1.55 V, generating Zn-2(V3O8)(2) with large layer spacing and a stable structure. The activated cathode material exhibited high specific capacity (520.64 mA h g(-1) at 0.5 A g(-1)) and excellent cycling stability (215.17 mA h g(-1) after 1000 cycles at 20 A g(-1)). These excellent performances are mainly attributed to the high pseudo-capacitance contribution ratio as well as the good electronic conductivity and fast ionic diffusion. This study brings new prospects of designing high-performance cathode materials for aqueous zinc-ion battery.