Enhancing aqueous zinc-ion batteries: The role of copper-ion-doped Mn3O4 as cathode material

It is widely recognized that manganese-based cathode materials are the most prospective cathode energy storage materials among zinc ion batteries. While rapid capacity decay and structural instability are the main hindrance in the rapid advancement of Manganese based materials. It has been established that ion doping is an accurate lever to enhance the stability of the structure and cycling performance of manganese-based materials. In this work, copper ions were selected as doping of Mn3O4 to mitigate obstacle of H+/Zn2+ extraction/insertion by expanding the lattice spacing of Mn3O4. The results show that Cu2+ doping results in a significant improvement in the properties of Mn3O4 (CMO). After 600 cycles at a current density of 1 A g-1, the initial capacity retention rate of Mn3O4 without doping is only 35.4%, while the CMO achieves a capacity retention rate of 98.9% (capacity retention of 166 mAh g-1). In addition, the CMO obtains a high specific capacity of 360 mAh g-1 at 0.1 A g-1. The significant difference in electrochemical properties between CMO and Mn3O4 indicates that Cu2+ doping improves the energy storage capacity of the cathode material.