Biomass-derived carbon coating enables stable MnO2 cathodes for aqueous zinc batteries

Aqueous Zn-MnO 2 batteries (AZMBs) are considered as highly promising sustainable energy-storage systems owing to their intrinsic safety, low cost, and environmental friendliness. However, manganese dioxide (MnO 2 ) cathodes suffer from slow kinetics and poor stability due to severe manganese dissolution during cycling, which severely hinders their practical application. Herein, we propose a carbon-coating strategy based on a low-cost biomass-derived carbon source (glucose), whereby a uniform and continuous carbon layer is constructed on MnO 2 nanowires via thermal carbonization to form MnO 2 @C cathodes. The carbon coating acts as a robust protective barrier, preventing Mn dissolution and buffering volume changes during cycling. Meanwhile, the carbon layer forms a highly conductive and electrochemically active interface, which markedly enhances charge transfer kinetics and ion diffusion dynamics. Owing to these synergistic effects, the MnO 2 @C cathode delivers a high reversible capacity of 239.6 mAh g −1 after 100 cycles at 0.2 A g −1 and maintains approximately 105 mAh g −1 (60% capacity retention) after 1000 cycles at 2 A g −1 , outperforming most previously reported Mn-based cathodes. This study demonstrates a scalable interfacial stabilization strategy utilizing biomass derivatives to realize durable MnO 2 cathodes in aqueous zinc batteries.