Rice husk-derived carbon@α-MnO 2 cathode for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have attracted increasing attention for large-scale energy storage due to their high safety, low cost, and environmental compatibility. However, the practical application of α-MnO 2 cathode is limited by poor electronic conductivity, sluggish ion transport kinetics, and structural degradation during long-term cycling. Herein, a rice-husk-derived carbon@α-MnO 2 composite (RHC@α-MnO 2 ) was constructed to enhance the energy storage performance of α- MnO 2 cathode. The introduced carbon provides an interconnected conductive framework for α-MnO 2 coating nanorods with good dispersivity. This architecture improves electron transport and promotes electrochemical reactions. The Zn||RHC@α- MnO 2 battery delivers a high discharge capacity of 323 mA·h g -1 at 0.1 A g -1 , much higher than that of pristine α-MnO 2 (132 mA·h g -1 ). Moreover, the RHC@α-MnO 2 electrode maintains a discharge capacity of 107.6 mA·h g -1 at 0.5 A g -1 and recovers to 172.3 mA·h g -1 when the current density returns to 0.1 A g -1 . GITT analysis demonstrates RHC@α-MnO 2 electrode exhibiting higher ion transport kinetics with its diffusion coefficient of 7×10 -12 –6×10 -10 cm 2 s -1 compared to α-MnO 2 . The improved electrochemical performance originates from the conductive carbon framework, optimized electrode/electrolyte interface, and accelerated ion migration. This work provides a sustainable strategy for designing MnO2-based cathodes for AZIBs.