Design strategies for MXene surface chemistry toward advanced energy-storage systems: A review

MXenes, an emerging class of two-dimensional transition-metal carbides, nitrides, and carbonitrides, have received increasing attention for electrochemical energy-storage owing to their abundant surface terminations and tunable surface chemistry. This article provides a comprehensive overview of recent advances in MXene surface chemistry engineering for energy-storage applications, with particular emphasis on understanding how surface chemistry regulates electrochemical processes. We first summarize major strategies for tailoring MXene surface chemistry, including in situ termination control during synthesis, post-synthetic inorganic modification, and organic surface functionalization. Subsequently, we discuss how engineered surface chemistry influences key materials properties, including interlayer spacing, ion adsorption and diffusion, charge transport, pseudocapacitive charge storage, electrical and ionic conductivity, wettability, and electrode–electrolyte interfacial reactions. The roles of surface-functionalized MXenes in regulating electrochemical performance in supercapacitors and various battery systems, including lithium-, sodium-, potassium-, and zinc-based batteries, are critically discussed. Finally, future perspectives are presented on rational surface chemistry design strategies to guide the development of MXene-based next-generation electrochemical energy-storage devices. Surface chemistry-driven modulation of MXene properties for advanced energy-storage systems. SEI, solid-electrolyte interphase.