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Mn-based cathodes are admittedly the most promising candidate to achieve the practical applications of aqueous zinc-ion batteries because of the high operating voltage and economic benefit. However, the design of Mn-based cathodes still remains challenging because of the vulnerable chemical architecture and strong electrostatic interaction that lead to the inferior reaction kinetics and rapid capacity decay. These intrinsic drawbacks need to be fundamentally addressed by rationally decorating the crystal structure. Herein, an oxygen-defective Mn-based cathode (Oc u -Mn 2 O 3 ) is designed via a doping low-valence Cu-ion strategy. The oxygen defect can modify the internal electric field of the material and enhance the substantial electrostatic stability by compensating for the nonzero dipole moment. With the merits of oxygen deficiency, the Oc u -Mn 2 O 3 electrode exhibits the significant diffusion coefficient in the range from 1 × 10 –6 to 1 × 10 –8, and good rate performance. In addition, the Oc u -Mn 2 O 3 maintains the highly reversible cyclic stability with the capacity retention of 88% over 600 cycles. The charge storage mechanism is explored as well, illustrating that the oxygen defects can improve the electrochemical active sites of H + insertion, achieving a better charge-storage capacity than Mn 2 O 3 .
Liu et al. (Mon,) studied this question.