Highly stable Co-doped MnO2 nanoarrays as enhanced cathode materials for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) are a promising battery technology because of low costs and high safety. However, dissolution, self-aggregation and irreversible phase changes during charge and discharge of cathode materials may severely restrict the cycle stability of ZIBs. The main objective of this work was to prepare a more stable cathode material. For this purpose, we successfully prepared transition metal Co-doped MnO2 (Co-MnO2) using a simple one-step potentiostatic electrodeposition method. Co-MnO2 showed a high specific capacity of 237 mAh g−1 at 0.1 A g−1. Even at a high current density of 4 A g−1, the capacity retention was 87 mAh g−1. When returning back to 0.1 A g−1, the capacity retention rate exceeded 100%. Compared with long-cycle performance of the undoped MnO2, the electrochemical performance of the ion-doped electrodes with transition metal was significantly improved. The results indicate that transition metal doped electrode material (here Co-MnO2) can significantly improve the electrochemical performance and structural stability of the electrode material and improve the cycling performance. The results are relevant for the developing advanced cathodes for ZIBs.