Interfacial engineering of ZnMn₂O₄ via N-doped rGO wrapping for improved electrochemical kinetics and stable lithium storage

Abstract

Spinel ZnMn₂O₄ is a promising anode material for lithium-ion batteries owing to its high theoretical capacity, low cost, and environmental compatibility. However, its practical utilization is limited by poor electrical conductivity, sluggish reaction kinetics, and structural instability during repeated lithiation and delithiation. These limitations motivate the development of an interfacial strategy that can simultaneously improve charge transport and mitigate the structural degradation associated with conversion-type lithium storage. In this work, N-doped reduced graphene oxide (N-rGO) is intimately wrapped around porous ZnMn₂O₄ nanoparticles to construct an interconnected oxide–graphene interface. The N-rGO framework provides continuous electronic pathways and stable interfacial transport channels, while its flexible network helps accommodate volume variations and maintain electrical connectivity during cycling. The resulting ZMO-M/N-rGO nanocomposite exhibits improved electrochemical kinetics and high-rate capability compared with pristine ZMO-M, delivering a reversible discharge capacity of 541.09 mA h g⁻¹ at a current density of 2 A g⁻¹. Following an initial 10-cycle activation period, the nanocomposite maintains a stable electrochemical response for 300 cycles at 1 A g⁻¹, retaining a discharge capacity of 619.10 mA h g⁻¹, whereas pristine ZMO-M exhibits pronounced capacity fluctuations. Electrochemical impedance analysis further reveals lower interfacial resistance and a more gradual, controlled evolution of Li⁺ transport behavior in the nanocomposite. These results demonstrate that N-rGO interfacial wrapping is an effective approach for improving charge-transfer kinetics, maintaining stable transport pathways, and enhancing the long-term electrochemical stability of ZnMn₂O₄-based anodes.