Exploring Sc2C and fluorinated Sc2C MXenes for high-performance Mg-ion battery anodes

High-capacity and highly stable electrodes are crucial for advancing metal-ion battery (MIB) technologies. Bivalent-ion batteries have garnered attention as safer, higher-energy-density alternatives to monovalent MIBs due to the abundance and bivalence of the metal atoms. The suitability of Sc 2 C and Sc 2 CF 2 MXene monolayers as anodes for bivalent metal atoms (Mg, Ca, and Zn) have been evaluated. The adsorption properties, diffusion barriers, charge transfer behavior, theoretical storage capacities, and voltage profiles of the bivalent metal atoms on these MXenes are analyzed to determine their feasibility for efficient intercalation. The results show that both Sc 2 C and Sc 2 CF 2 monolayers exhibit strong binding energies with the bivalent metals and low diffusion barriers, enabling rapid metal-ion transport within the MXene structures. Specifically, magnesium (Mg)-ion diffusion displays the barrier of 0.13 eV on the Sc 2 C monolayer and appears nearly barrierless (0.09 eV) on the Sc 2 CF 2 monolayer. The Mg-adsorbed MXene composites exhibit ultra-high theoretical storage capacities of 3154.12 and 2298.00 mA h/g for the Sc 2 C and Sc 2 CF 2 systems, respectively. Voltage profile analysis indicates that Sc 2 C and Sc 2 CF 2 provide suitable operating voltages for MIB anodes. These findings suggest that Sc 2 C and Sc 2 CF 2 MXenes are superior anode materials, potentially enabling durable, high-capacity, and sustainable Mg-based energy storage systems.