Crystalline MnCO@Amorphous MnO Composite as Cathode Material for High-Performance Aqueous Zinc-Ion Batteries.

Rechargeable aqueous zinc-ion batteries (RAZIBs) have received extensive attention because of their advantages of low cost, high safety, and nontoxicity. However, problems such as dissolution of the active cathode material, dendrites/passivation of the zinc anode, and slow reaction kinetics hindered their further applications. In this work, a crystalline/amorphous composite-type material composed of crystalline MnCO and amorphous MnO was prepared and used as the cathode material for RAZIBs. The MnCO@amorphous MnO (MnCO@A-MnO) composite possesses the merits of both the pure crystalline phase of MnCO and the amorphous phase of MnO, which can deliver better electrochemical performance than the corresponding single component in repeated cycles. In addition, crystalline MnCO undergoes a complex phase transition to the active MnO during the first charge process, providing the composite with a stable structure and additional electrochemical capacity. The electrochemical measurement results indicate that the MnCO@A-MnO electrode can display high reversible discharge capacity at 0.1 A g, excellent rate performance at 5.0 A g, and long cycling stability over 2000 cycles, showing great potential as a cathode material for high-performance RAZIBs.