Interfacial and structural optimization of graphene wrapped β-MnO2 nanorod cathodes for long-life aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) as promising candidates for grid-scale storage are constrained by the poor conductivity and structural instability of manganese dioxide (MnO 2 ) cathodes during cycling. Herein, we report a rationally designed cathode comprising β-MnO 2 nanorods intimately decorated with reduced graphene oxide (β-MnO 2 @rGO) through an in-situ hydrothermal and thermal activation process. The one-dimensional β-MnO 2 nanorods provide shortened diffusion pathways for H + /Zn 2+ ions, while the conformal rGO network establishes a three-dimensional conductive skeleton that enhances electronic transport and buffers volumetric expansion during cycling. X-ray photoelectron spectroscopy (XPS) confirms the formation of robust Mn-O-C interfacial bonds, which facilitate charge transfer and mitigate manganese dissolution. The optimized β-MnO 2 @rGO-30 exhibits a high reversible specific capacity of 387 ± 3.0 mAh g −1 at 0.1 A g −1 and maintains 89 ± 1% capacity retention after 6000 cycles at 1.0 A g −1 . A sequential insertion mechanism, beginning with H + intercalation followed by Zn 2+ storage, with excellent structural reversibility, is elucidated by ex-situ spectroelectrochemical analysis. This work provides a viable strategy for designing high-performance MnO 2 -based cathodes through synergistic nanoengineering and conductive hybridization for advanced AZIBs. This work constructs β-MnO₂@rGO heterostructures with covalent Mn-O-C bonds to overcome poor conductivity and structural instability in AZIB cathodes. The rGO scaffold enhances reaction kinetics, buffers volume change, and suppresses Mn dissolution. The optimized electrode delivers a high reversible specific capacity, excellent capacitance retention and cyclic stability. Download: Download high-res image (146KB) Download: Download full-size image