MXenes for sustainable energy: A comprehensive review on conservation and storage applications

This review explores the potential of MXenes, a novel class of two-dimensional (2D) materials, in advancing energy storage and conservation technologies. MXenes exhibit exceptional physicochemical properties, including a high specific surface area (∼390 m² g⁻¹ for MXene@PPy-800), outstanding electrical conductivity, and robust chemical stability, making them ideal for energy-related applications. In supercapacitors, MXene-based electrodes have demonstrated capacitances exceeding 700 F g⁻¹ at 1 mV s⁻¹, with retention of over 90 % of their initial performance after 10,000 charge/discharge cycles. For lithium-ion batteries, MXenes achieve theoretical capacities ranging from 390 to 600 mAh g⁻¹, depending on the type of MXene material, with experimental reversible capacities often exceeding 400 mAh g⁻¹ at 1C rates and high cycling stability.

This review synthesizes recent research efforts on the synthesis, structural characterization, and integration of MXenes into energy storage systems. Findings highlight their versatility as electrode materials for supercapacitors, lithium-ion batteries, and fuel cells, as well as their catalytic potential in solar energy conversion. Despite these advancements, challenges remain unresolved. Scalability of MXene synthesis through selective etching methods continues to be a significant technical and economic barrier. Moreover, while MXene-based devices show high initial performance, further work is needed to improve long-term stability in operational and harsh chemical environments.

By providing a comprehensive overview of MXene-based energy systems, this review identifies critical gaps in understanding their electrochemical mechanisms, particularly ion transport and surface interaction dynamics. Addressing these challenges will be key to optimizing MXene properties and enabling their widespread application in efficient and sustainable energy technologies.