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

Abstract

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 to 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-doped 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.