V₂O₅ Nanospheres with Mixed Vanadium Valences as High Electrochemically Active Aqueous Zinc-Ion Battery Cathode

A V⁴⁺-V₂O₅ cathode with mixed vanadium valences was prepared via a novel synthetic method using VOOH as the precursor, and its zinc-ion storage performance was evaluated. The products are hollow spheres consisting of nanoflakes. The V⁴⁺-V₂O₅ cathode exhibits a prominent cycling performance, with a specific capacity of 140 mAh g^-1 after 1000 cycles at 10 A g^-1, and an excellent rate capability. The good electrochemical performance is attributed to the presence of V⁴⁺, which leads to higher electrochemical activity, lower polarization, faster ion diffusion, and higher electrical conductivity than V₂O₅ without V⁴⁺. This engineering strategy of valence state manipulation may pave the way for designing high-performance cathodes for elucidating advanced battery chemistry.