Microwave-Hydrothermal Graphene Synergy Boosts α-MnO₂ Cathode for High-Performance Zn-Ion Batteries

Aqueous zinc-ion batteries (AZIBs) promise safe, green and cheap grid storage.Among the cathode candidates, α-MnO₂ is regarded as one of the most promising materials yet they are throttled by poor conductivity.In this work, a microwave-hydrothermal route is adopted to rapidly tailor the crystal orientation and micro-morphology of α-MnO₂, and the correlation between microstructure and ion-diffusion kinetics is systematically investigated. Graphene (Gr) is subsequently introduced to construct a three-dimensional conductive network, which markedly lowers charge-transfer resistance. Quantitative pseudocapacitive analysis further elucidates the underlying energy-storage mechanism. It is revealed that a properly prolonged hydrothermal duration alleviates nanorod aggregation, enlarges the specific surface area, and thus accelerates ion diffusion. Concurrently, the Gr-incorporated architecture enables rapid Zn²⁺/H⁺ transport and endows the composite with superior reaction kinetics. Consequently, a synergistic enhancement in both specific capacity and cycling stability is achieved. This work offers a feasible strategy for the rational design of high-performance Mn-based cathodes.