Regulating the kinetics of zinc-ion migration in spinel ZnMn2O4 through iron doping boosted aqueous zinc-ion storage performance.

Spinel ZnMn2O4 with a three-dimensional channel structure is one of the important cathode materials for aqueous zinc ions batteries (AZIBs). However, like other manganese-based materials, spinel ZnMn2O4 also has problems such as poor conductivity, slow reaction kinetics and structural instability under long cycles. Herein, ZnMn2O4 mesoporous hollow microspheres with metal ion doping were prepared by a simple spray pyrolysis method and applied to the cathode of aqueous zinc ion battery. Cation doping not only introduces defects, changes the electronic structure of the material, improves its conductivity, structural stability, and reaction kinetics, but also weakens the dissolution of Mn2+. The optimized 0.1 % Fe-doped ZnMn2O4 (0.1% Fe-ZnMn2O4) has a capacity of 186.8 mAh g-1 after 250 charge-discharge cycles at 0.5 A g-1 and the discharge specific capacity reaches 121.5 mAh g-1 after 1200 long cycles at 1.0 A g-1. The theoretical calculation results show that doping causes the change of electronic state structure, accelerates the electron transfer rate, and improves the electrochemical performance and stability of the material.