ε-MnO2@C cathode with high stability for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) are potential candidates for achieving considerable energy savings owing to their environmental benignity and low cost. At present, however, Mn2+ dissolution causes structural failure in manganese-based cathodes. Therefore, addressing this issue is vital for improving their cycling stability and specific capacity. Herein, ε-MnO2 was obtained by annealing MnCO3 at 350 °C. Subsequently, ε-MnO2 was coated with a carbon layer (carbonizing D-glucose) to obtain ε-MnO2@C, which effectively mitigated the Mn2+ dissolution as well as the side reactions between the electrode and electrolyte. Electrochemical results revealed a significant improvement in the specific capacity (280 mAh g−1 at 0.2 A g−1) and capacity retention (∼91% over 1700 cycles at 1 A g−1) of the ε-MnO2@C cathode.