Ni/Fe Bimetallic Ions Co-Doped Manganese Dioxide Cathode Materials for Aqueous Zinc-Ion Batteries

Abstract

The slow diffusion dynamics hinder aqueous MnO2/Zn batteries’ further development. Here, a Ni/Fe bimetallic co-doped MnO2 (NFMO) cathode material was studied by density functional theory (DFT) calculation and experimental characterization techniques, such as cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectra (EIS). The results indicated that the energy band structure and electronic state of MnO2 were effectively optimized due to the simultaneous incorporation of strongly electronegative Ni and Fe ions. Consequently, the NFMO cathode material exhibited a faster charge transfer and ion diffusion dynamics than MnO2 (MO), thus, the assembled NFMO/Zn batteries delivered excellent rate performance (181 mA h g−1 at 3 A g−1). The bimetallic ions co-doping strategy provides new directions for the development of oxide cathode materials towards high-performance aqueous zinc-ion batteries.

Keywords

• aqueous zinc ion batteries
• bimetallic ion-doping
• Ni/Fe co-doped MnO₂
• vacancy defects