M2X Monolayers as Anode Materials for Li Ion Batteries

Electrochemically efficient electrode materials are required for clean energy storage in Li ion batteries. We predict two-dimensional hexagonal metal nitrides, borides, and phosphides (Sc2B, Sc2N, Y2B, Y2N, and Y2P) and evaluate the feasibility of experimental realization. The materials combine excellent metallicity, as required for electrodes, with Li binding energies providing high storage capacity and a low average open-circuit voltage. In contrast to two-dimensional silicene, borophene, and SnS2, we observe negligible structural distortions during Li adsorption and extraction, which results in high reversibility and a long cycle life. Superionic Li diffusion enables fast charge or discharge of next-generation Li ion batteries.