Regulating the crystal structure of ZnMn2O4 material by Zr doping for rechargeable aqueous zinc-ion batteries

Manganese-based materials are promising for cathodes due to their low cost and high specific capacity in aqueous zinc-ion batteries. However, structural collapse and capacity degradation during cycling limit their practical applications. This study presents a zirconium (Zr) doping modification strategy to stabilize the crystal structure of spinel ZnMn2O4 (ZMO), creating lattice defects and modulating manganese valence states. Zr-doped ZnMn2O4 (Zr-x ZnMn2O4, x=0.005, 0.01, 0.015, 0.025) materials were synthesized using a one-step hydrothermal method. The optimized Zr-0.01 ZMO material exhibits a high capacity of 300.7 mAh g- 1 at a low current density of 0.1 A g- 1. It retains 134.0 mAh g- 1 after 1000 cycles at a high current density of 1.0 A g- 1, with faster activation than the undoped sample. This enhanced performance of Zr-0.01 ZMO is attributed to its improved structural reversibility and increased conductivity during Zn2+ insertion/extraction. We believe that this strategy offers a novel approach to advancing manganese-based materials for aqueous zinc-ion battery applications.