INDUSTRY TRACK: How MXenes Assist in Storing Electrical Energy

INDUSTRY TRACK: Carbides and nitrides of transition metals known as MXenes are the fastest-growing family of 2D materials. About 50 stoichiometric carbide and nitride MX compositions have been reported (not counting surface terminations), and the structure and properties of numerous other MXenes have been predicted. The versatile chemistry of the MXene family renders their properties tunable for a large variety of applications. IUPAC listed MXenes among its Top 10 emerging technologies in chemistry with a true potential to transform our world in 2024. O/OH-terminated MXenes combine high electronic conductivity with hydrophilicity and fast ionic transport, while Cl-terminated MXenes are hydrophobic. Ti₃C₂T_x(T= O, OH, F, etc.) MXene offers a much higher conductivity (over 20,000 S/cm) than reduced graphene oxide (rGO) or other carbon nanomaterials, thus decreasing resistive losses in electrochemical applications. Oxygen-terminated MXenes are capable of fast surface redox reactions of transition metals in their surface layers. Transition metals with multiple valency, such as V, Nb, Mo, or Ti, are used in oxide-based energy storage materials. The electronic conductivity of carbides and nitrides combined with the intrinsically large electrochemically active surface of 2D materials make MXenes attractive for redox energy storage, especially when high rate and power are needed. This, along with other advantageous properties, makes the MXene family promising for energy storage. Energy storage was the first application of MXenes, explored immediately after their discovery, and numerous articles are dedicated to the use of MXenes in Li, K, Na, Zn-ion, Na-S and Li-S and other batteries, as well as supercapacitors. However, using Ti₃C₂ in passive elements (micrometer-thin current collectors and conductive additives) looks like a low-hanging fruit.