Metal-Ion Batteries with MXene Electrodes: State of the Art and Perspectives

MXenes are an emerging family of two-dimensional layered materials composed of transition-metal carbides, nitrides, and carbonitrides that have attracted broad attention because of their unusual combination of properties. Since their discovery, their metallic-level electrical conductivity, high accessible surface area, adjustable surface terminations, and lamellar architecture have made them strong candidates for electrochemical energy storage. Across a wide range of battery chemistries, including lithium-ion, sodium-ion, lithium sulfur, and zinc-ion systems, MXenes have been explored as fast-charging electrodes, conductive frameworks that improve electron transport, building blocks in performance-boosting composites, and even as current-collector modifications. Among these functions, one of the most central is their direct participation as charge-storing host materials. In this review, I summarize recent advances in the synthesis and characterization of MXenes and critically assess their use as active materials in divalent metal-ion batteries, with a focus on strategies that improve electrochemical performance. I also examine the dominant charge-storage pathways and how they evolve in pure MXenes versus MXene-based composites within these multivalent systems. Finally, I highlight key limitations and open challenges and outline future directions, emphasizing microstructure engineering as a practical route to designing MXenes that deliver stronger divalent-ion storage performance.