Construction of diphenic acid molecular welded Ti3C2 with enlarged and stable interlayer spacing towards high rate alkali metal ions storage

Ti3C2-MXene has been generally studied in energy storage area because of adjustable surface chemistry, excellent electronic conductivity, and unique layered structure. However, the diffusion kinetic performance of alkali metal ions in Ti3C2 is restricted by the limited interlayer spacing. Enlarging interlayer spacing of Ti3C2 is beneficial to improve the ion diffusion rate. Here, a simple and effective diphenic acid (DHA) molecular welding strategy is reported to prepare DHA welded Ti3C2 (DHA-Ti3C2) by dehydration condensation reaction. The welded DHA molecule contributes the dual effects of pillar and strain on the layered structure of Ti3C2, which can improve ion diffusion kinetic performance and alleviate volume expansion during the alkali metal ions insertion/extraction process. The DHA-Ti3C2 exhibits high rate capability and long-term cycle stability because of the enlarged interlayer spacing and enhanced structure stability. The specific capacity of 444 mAh g−1 and 156 mAh g−1 at current density of 0.1 A g−1 can be reached after 200 cycles and 1700 cycles in Li+/Na+ batteries, respectively. This study offers a strategy to efficiently tuning the layered structure of two-dimensional (2D) materials for achieving the optimal alkali metal ions storage performance.