Synergistic combination of a Co-doped σ-MnO2 cathode with an electrolyte additive for a high-performance aqueous zinc-ion battery

Abstract

The key challenges in aqueous zinc-manganese dioxide batteries (MnO₂//Zn) are their poor electrochemical kinetics and stability, which are mainly due to low conductivity and the inevitable dissolution of MnO₂. A synergistic combination of a Co-doped σ-MnO₂ electrode (Co-MnO₂) and a Co(CH₃COO)₂•4H₂O (CoAc) electrolyte additive is here developed to design a high-performance aqueous MnO₂//Zn battery (denoted as a Co-MnO₂//Zn battery with CoAc). The introduction of Co ions (Co³⁺/Co²⁺) into the σ-MnO₂ electrode is achieved via a facile one-step electrodeposition method. Benefitting from the synergistic coupling effect of the Co-MnO₂ electrode and the CoAc electrolyte additive, the fabricated Co-MnO₂//Zn battery with CoAc shows a commendable discharge capacity of 313.8 mAh g⁻¹ at 0.5 A g⁻¹, excellent rate performance, excellent durability over 1000 cycles (∼ 92% capacity retention at 1.0 A g⁻¹) and admirable energy density (439.3 Wh kg⁻¹), which is a significant improvement compared with an un-doped σ-MnO₂//Zn battery.