Promoting Proton Migration Kinetics by Ni2+ Regulating Enables Improved Aqueous Zn-MnO2 Batteries

Abstract

The energy storage behaviors of MnO2 for aqueous Zn-MnO2 batteries mainly depend on the Zn2+/H+ intercalation but are limited by poor ion/electron migration dynamics and stability. Herein, a strategy is proposed that promoting proton migration kinetics ameliorates H+ storage activity by introducing Ni2+ into γ-MnO2 (Ni-MnO2). Ni2+ can lower the diffusion barrier of H+ and selectively induce the ion intercalation, thereby alleviating the electrostatic interaction with the lattice. Moreover, Ni2+ enables the adjacent [MnO6] octahedrons to have better electron conductivity. The Ni-MnO2 exhibits superior rate performance (nearly four times specific capacity compared with MnO2) and ultra-long-cycle stability (100% of capacity retention after 11 000 cycles at 3.0 A g−1). The calculation indicates that the Ni-MnO2 allows H+ migrate rapidly along the one-dimensional tunnel due to reduction of the activation energy caused by Ni2+ regulating, thus achieving excellent reaction kinetics. This work brings great potential for the development of high-performance aqueous Zn-MnO2 batteries.