Two-Dimensional Titanium Carbonitride Mxene for High-Performance Sodium Ion Batteries

Two-dimensional layered MXenes are attractive materials for energy storage devices due to their superior electrochemical performance and encouraging capacitances as anode materials in sodium ion batteries (SIBs). Herein, we report the use of Ti3CN as a new promising anode material in SIBs and the interfacial kinetic properties of Ti3CN electrodes. The Ti3CN electrode delivered a high specific capacity of 507 and 211.5 mAh g–1 for the first discharge/charge process, respectively, at a current density of 20 mA g–1. When tested at 500 mA g–1, the discharge specific capacity of the Ti3CN electrode was 98.9 mAh g–1, which is 1.65 times as much as that of pristine Ti3C2. The density functional theory (DFT) calculations demonstrate that the introduction of more electronegative nitrogen into the lattice grid of Ti3C increases the electron count of MXenes. The significantly improved capacities and long-term cycling performance of Ti3CN compared to those of its counterpart Ti3C2 SIBs indicate that Ti3CN can be considered promising anode materials for sodium-based energy storage devices.