Electrochemical one-step synthesis of Mn3O4 with tunable oxygen defects for high-performance aqueous zinc-ion batteries

Manganese-based oxides have been widely studied as promising aqueous zinc-ion battery cathodes. However, the development of manganese oxides still faces great challenges due to rapid capacity decline and sluggish reaction kinetics. Oxygen-defect manganese oxides cathodes can improve electrochemical activity and inherent stability by changing the bulk electronic structure and the surface properties. In this work, oxygen-defect Mn 3 O 4 nanosheets were synthesized by a facile electrochemical corrosion method, and the concentrations of oxygen vacancies were controlled by adjusting alternating current (AC) and direct current (DC) superimposed power supply. The oxygen vacancy concentration impacted the electrochemical performance of the Mn 3 O 4 cathodes. The aqueous zinc-ion battery with Mn 3 O 4 cathode with the optimal oxygen vacancy concentration exhibited a high specific capacity (456 mAh g -1 at 0.1 A g -1 ) and long-cycle stability with high reversible capacity (94% retained after 2000 cycles at 1.0 A g -1 ). Furthermore, the conversion mechanism with complex phase transformations was explored by ex-situ characterization after the charge/discharge cycling, indicating the co-insertion of H + and Zn 2+ in the Mn 3 O 4 electrode. • VO-rich Mn3O4 were synthesized in a facile method. • The concentration of oxygen vacancy can be adjusted. • Mn3O4 with optimal VOs achieved high- performance AZIBs. • The conversion mechanism of Mn3O4 electrode was explored by ex-situ characterization.