High‐Capacity and Long‐Life Manganese Vanadium Oxide Composite as a Cathode for Aqueous Zinc‐Ion Batteries

Abstract Aqueous zinc‐ion batteries (AZIBs) are widely attractive by virtue of its high safety and low cost. However, their development for widespread applications is limited due to unstable cathode materials. Herein, a manganese vanadium oxide (Mn 2 V 2 O 7 /V 2 O 3 ) (MnVO) composite is fabricated and can be utilized as a superior intercalated cathode for AZIBs. The extraction of Zn 2+ from the MnVO composite causes the phase transition during the initial charge cycle to form electrochemically reversible MnV 10 O 26 ·10H 2 O. The phase transformation modifies morphology and the as‐formed MnV 10 O 26 ·10H 2 O phase acts as a Zn 2+ host for the subsequent cycles, leading to excellent electrochemical performances. As a result, the electrode delivers a superior reversible capacity of 204 mA h g −1 at 1 A g −1 over 1000 cycles and is also sustainable over a long‐life span of 3000 cycles even at 10 A g −1 . Additionally, the Zn/MnVO battery exhibits a high energy density of 256.31 Wh kg −1 at a power density of 410 W kg −1 . The exceptional reversible capacity even at different current densities over a long‐life span makes them a promising candidate for fabricating the safe and reliable AZIBs. Also, the Zn 2+ storage mechanism in MnVO composite cathode for rechargeable AZIBs is demonstrated.