Synergistic improvement the Zn storage performance of ZnMn2O4 quantum dots by Ni doping and in-situ electrochemical induction

Manganese-based materials have been widely recognized as the most promising cathode materials for aqueous zinc-ion batteries (ZIBs). However, due to the problems of disproportionation reaction and slow electron transport, the development of manganese-based materials is greatly limited. In this work, a carbon-coated Ni-doped ZnMn2O4 quantum dot (NZMO QD@C) were obtained by a combined strategy of gradient calcination and electrochemical induction process with Mn-MIL-100 as the precursor. The presence of 0D quantum dot structure allows ZnMn2O4 to have shorter Zn2+ diffusion pathways and more active sites. Meanwhile, the doping of Ni can promote electron rearrangement, improve conductivity, and ultimately improve the reaction kinetics and electrochemical performance of cathode materials. Furthermore, Ni doping can effectively enhance the stability of the Mn-O bond in NZMO QD@C by optimizing the Mn ion state and electronic bandgap. Therefore, the synthesized NZMO QD@C provide a higher specific capacity of 392 mAh/g (0.1 A/g) and better (≈80.28 % capacity retention for more than 820 cycles at 1 A/g) than original MO QD@C cathode. This work brings new ideas to promote the development and design of manganese-based oxide cathode materials for ZIBs.