Synthesis of MnO 2 @TiO 2 composite electrodes via hydrolysis and calcination for high stability zinc ions batteries

Aqueous Zn/MnO ₂ batteries have been extensively attracted attentions for their superior comprehensive performance. However, the poor structural stability and dissolution of MnO ₂ have seriously prevented its further development. Therefore, TiO ₂ is introduced for coating MnO ₂ to improve its electrochemical stability. Firstly, TiO ₂ used as a protective layer could hamper the direct contact between the electrode and the electrolyte, and effectively inhibiting the dissolution of manganese. Secondly, TiO ₂ has good mechanical strength to adapt to the volume change of MnO ₂ during the charge/discharge processes, which consolidates the stability of the electrode material. Finally, TiO ₂ could improve the electrical conductivity of the composite material, achieving lower polarization and good electron/ion transport. As a result, Zn/MnO ₂ @TiO ₂ -2 exhibits extraordinary electrochemical performance with a rate capacity of 245.16 mAh g ^− 1 at 0.2 A g ^− 1 and maintains a capacity of 137.09 mAh g ^− 1 after 1000 cycles at 1 Ag ^− 1 . Even at a high current density of 3 A g ^− 1 , it has a capacity of 93.35 mAh g ^− 1 after 1500 cycles, and the capacity retention rate is 97.47%. This work provides the inspiration and foundation method for designing high-performance Zn/MnO ₂ batteries.