Electrochemical performance and degradation mechanism of rechargeable aqueous Al ₂ O ₃ @Zn//MnO ₂ battery

Abstract Rechargeable aqueous Zn ion batteries (AZIBs) have attracted significant attention as a promising alternative to Li‐ion batteries due to the use of water‐based electrolytes, high energy density per volume, and cost‐effectiveness. However, various parasitic reactions relating to hydrogen evolution reaction, corrosion, and dendrite growth in the Zn anode can result in the degradation of the electrochemical performance of AZIBs. Therefore, understanding the mechanisms underlying these various phenomena and their role in the electrochemical performance of AZIBs provides valuable insights for the development of anode and cathode materials. In this study, we investigate the effect of the MnO ₂ cathode and Al ₂ O ₃ ‐coated Zn anode on the electrochemical performance of the AZIBs. The experimental results show that Al ₂ O ₃ ‐coated Zn anodes efficiently suppress the dendrite growth on the Zn. However, significant cycling fade of the full cell comprising of an Al ₂ O ₃ ‐coated Zn anode and MnO ₂ cathode was observed during continuous charge/discharge cycles. The poor cycle performance can be mainly attributed to the phase transformation of MnO ₂ –Mn ₂ O ₃ and the formation of various byproducts, which highlights the importance of the electrochemical stability of cathode materials in AZIBs to improve the cycle performance.