Prediction of Mobility, Enhanced Storage Capacity, and Volume Change during Sodiation on Interlayer-Expanded Functionalized Ti₃C₂ MXene Anode Materials for Sodium-Ion Batteries

Sodium storage capacity, mobility, and volume change during sodiation on the surfaces of interlayer-expanded Ti₃C₂ MXenes are investigated using ab initio density functional theory. The theoretical results reveal that the interlayer-expanded bare, F-, O-, and OH-functionalized Ti₃C₂ MXenes exhibit low barriers for sodium diffusion and small changes of lattice constant during sodiation. In addition, enlarged interlayer distance enables the stable multilayer adsorption on the bare and O-functionalized Ti₃C₂ MXenes and therefore significantly enhances their theoretical capacities. Both bare and O-functionalized Ti₃C₂ MXenes are predicted to be prospective anode materials for sodium-ion batteries with high theoretical capacities, fast discharge/charge rates, and good cycling performances. The present results provide a new route to improve the battery performances of anode materials based on MXene intercalation hosts.