Screening for Stable Ternary-Metal MXenes as Promising Anode Materials for Sodium/Potassium-Ion Batteries

We screened out five stable ternary-metal (TM) MXenes (TiTaZrC2, VTiMoC2, VHfMoC2, VHfWC2, and VTaHfC2) and studied their performance as the electrodes of sodium/potassium-ion batteries by using the density functional theory. The TM MXenes have stronger adsorption energies for Na (-1.08 similar to -1.28 eV) and K (-1.44 similar to -1.63 eV) ions and significantly lower diffusion barriers (0.01 similar to 0.03 eV) than pristine Ti3C2 and V3C2. Especially at the high concentration of Na adsorption, the TM MXenes exhibit superior performance. Among them, VHfMoC2 and VHfWC2 could reach full Na adsorption on the favorable sites with reversible and suitable average voltage (0.59/0.58 V) for sodium-ion batteries. Our results suggest that TM MXenes have great potential as electrode materials and provide new ideas for multimetal MXene applications in batteries.