Sandwich-like Na2Ti3O7 Nanosheet/Ti3C2 MXene Composite for High-Performance Lithium/Sodium-Ion Batteries

MXenes have shown great promise in high-efficiency energy storage on account of superior electrical conductivity and outstanding mechanical properties. However, the practical applications of MXenes in electrochemical energy storage are limited by layer restacking and surface oxidation issues. Herein, a unique sandwich-like Na2Ti3O7 nanosheet/Ti3C2 MXene composite (NTO@MXene) with an expanded interlayer spacing of MXene has been fabricated by one-step simultaneous alkalization and oxidation. The NTO@MXene with a unique structure shortens the ion diffusion distance and promotes electrolyte infiltration, which is favorable for high-performance rechargeable batteries. As a result, the NTO@MXene composite as an anode electrode for lithium-ion batteries delivered exceptional rate performance (159 mAh g–1 at 4 A g–1) and long-life cycling performance (capacity retention of nearly 100% at 4 A g–1 after 1200 cycles). When used as a sodium-ion battery anode, the electrode also achieved an extraordinary capacity of 103 mAh g–1 at 0.1 A g–1 and an exceptional capacity retention of 70% at a high current density of 2 A g–1 after 3000 cycles.