A Multi‐Colored, Structure‐Tolerant Vanadate Cathode for High‐Performance Aqueous Zinc‐Ion Batteries

Abstract Vanadium‐based cathode materials for aqueous zinc‐ion batteries (AZIBs) have attracted much attention in large‐scale energy storage devices yet their unsatisfactory cyclic stability and slow diffusion rate of Zn 2+ ions during insertion and extraction hinder further commercial applications. Therefore, the development of vanadium‐based cathode materials with stable crystal structures and fast Zn 2+ storage remains challenging. Herein, Na 2 CaV 4 O 12 (NCVO) nanowires are reported as a promising cathode of excellent electrochemical performance in AZIBs, simultaneously rendering high specific capacity (443.2 mAh g −1 at 0.1 A g −1 ) and high average voltage plateau (0.91 V) with impressive energy density (403.3 Wh kg −1 ) and power density (1533 W kg −1 ). As NCVO features a unique open crystal structure with alternately arranged inactive layers ([NaO 6 ] and [CaO 8 ] polyhedra) and active layers ([VO 4 ] tetrahedra), the expansion of the [VO 4 ] tetrahedra during Zn 2+ insertion is well balanced by the contraction of the inactive layer, thus enabling remarkable long‐term cycling stability (91.9% and 80% capacity retention after 5000 and 10 000 cycles at 10 A g −1 , respectively). With the electrochromic property of the NCVO cathode, the AZIB can further be used for adaptive camouflage under a range of scenarios, shedding light on the future development of high‐performance cathodes for AZIBs.