Sandwich-Like MXene@Mn₃O₄@PPy Hollow Microspheres Synergistically Enabled Ultra-long Cycling Life in Aqueous Zinc Ion Batteries

Manganese-based oxides are be regarded as one of the most promising cathode materials for aqueous zinc ion batteries (AZIBs). A major restriction of manganese-based oxides in practical applications is their unsatisfied structural stability due to the irreversible manganese dissolution. Additionally, the poor electrical conductivity also limits the rate capability. Herein, the sandwich-like MXene@Mn₃O₄@PPy hollow microspheres are constructed via self-sacrificial template and surface coating method to improve the cycling life of AZIBs. Benefiting from the unique sandwich-like hollow structure and the surface coating of PPy, the MXene@Mn₃O₄@PPy cathode possesses high electronic/ionic conductivity and satisfied structural stability. The sandwich-like MXene@Mn₃O₄@PPy hollow microspheres deliver excellent electrochemical performance, including an impressive rate capability and ultra-long cycling life with a capacity of 120 mAh g⁻¹ at 5 A g⁻¹ after 9000 cycles. In addition, the systematic ex situ XRD and HRTEM characterizations verify the highly reversible Zn²⁺ and H⁺ insertion/desertion in the sandwich-like MXene@Mn₃O₄@PPy hollow microspheres. This work combines hollow structure design and surface coating method to provide an effective strategy for improving the structural stability of manganese-based oxides in AZIBs.