Boosting the Zn ion storage ability of amorphous MnO2 via surface engineering and valence modulation

Abstract

Abstract Manganese‐based oxides are promising cathode materials for aqueous zinc ion batteries (AZIBs) while suffering from poor reaction kinetics and structure collapse, resulting in inferior rate capability and cycling stability. Herein, an efficient crystal and surface engineering strategy is proposed to enhance the electron transfer ability of amorphous MnO2 and prevent its structure deformation during the Zn ion storage process. With the synergetic effect of poly(3,4‐ethylenedioxythiophene) (PEDOT) coating and Co‐doping, the Zn//PEDOT@Co‐MnO2 (PCMO) batteries show a high capacity of 298.9 mAh g−1 at the current density of 1 A g−1, a superior rate capability of 50.2% capacity retention at 10 A g−1, and outstanding cycling stability of 92.3% capacity retention after 1000 continuous cycles, significantly surpassing Zn//MnO2 (MO) and Zn//Co‐MnO2 (CMO) batteries in all aspects. Moreover, the peak energy density based on the mass of PCMO can reach 375 Wh kg−1 at a power density of 1.25 kW kg−1, which is better than most recently reported aqueous energy storage devices, including AZIBs, supercapacitors, lead‐acid batteries, and nickel‐based alkaline batteries. This work provides valuable information for designing advanced high‐performance Mn‐based cathodes for AZIBs.

Keywords

• amorphous MnO2
• aqueous Zn ion batteries
• heteroatom doping
• surface engineering