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

Abstract A V 4+ -V 2 O 5 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 V 4+ -V 2 O 5 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 V 4+ , which leads to higher electrochemical activity, lower polarization, faster ion diffusion, and higher electrical conductivity than V 2 O 5 without V 4+ . This engineering strategy of valence state manipulation may pave the way for designing high-performance cathodes for elucidating advanced battery chemistry.