V(2)O(5) Nanospheres with Mixed Vanadium Valences as High Electrochemically Active Aqueous Zinc-Ion Battery Cathode

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. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s40820-019-0256-2) contains supplementary material, which is available to authorized users.