From surface chemistry to ion dynamics: mechanistic roles of MXenes in aqueous zinc-ion batteries

Abstract

As the global demand for sustainable and safe energy storage solutions intensifies, aqueous zinc-ion batteries (AZIBs) have emerged as a promising next-generation energy storage system owing to their inherent safety, cost-effectiveness, and environmental benignity. Metallic zinc, with a high theoretical capacity (820 mAh g⁻¹), a low redox potential, and natural abundance, is well-suited for use as an anode. However, persistent challenges, including dendrite growth, parasitic hydrogen evolution, and corrosion, undermine its long-term electrochemical stability. Meanwhile, cathode performance is often limited by structural degradation and sluggish Zn²⁺ diffusion kinetics. In this context, MXenes, a rapidly expanding family of two-dimensional (2D) transition metal carbides and nitrides, offer new opportunities for advancing AZIB technologies. Their unique structural characteristics, including high electrical conductivity, tunable interlayer spacing, and surface-rich functionalities, position them as promising candidates for both anode and cathode design. This review systematically elucidates the charge storage mechanisms in AZIBs, summarizes the development of advanced cathode and anode materials, and provides a critical overview of MXene synthesis, surface modification, and integration strategies. Particular emphasis is placed on their multifunctional roles in electrode frameworks and as electrolyte additives to modulate ionic conductivity and interfacial stability. By integrating recent insights and highlighting future research directions, this review aims to provide a roadmap for the rational design of MXene-enabled AZIBs with enhanced electrochemical reversibility, structural durability, and system-level performance.