NH4PF6-induced P-doping and surface restructuring: Route to superior lithium storage performance of MXene

2D layered MXene, which holds multiple outstanding properties, like large specific surface area, abundant functional groups, and ultra-high electronic conductivity, have been an attractive anode material for lithium-ion energy storage. However, its practical application is greatly hindered by its limited capacity. Aiming at addressing this problem, this article innovatively proposes to mix NH 4 PF 6 with MXene for sintering, achieving P-doping between MXene layers and the transformation of Ti O and Ti-O-P functional groups. After 1700 cycles of 150 mA g −1 , the modified material still has a high specific capacity of over 250 mAh g −1 , and after 800 cycles of 1500 mA g −1 high current, it still has a capacity retention rate of over 100%. The in-situ XRD, XPS, DFT calculations and other methods have been used to demonstrate that the uniformly distributed phosphorus rich functional groups between MXene layers significantly expand the interlayer spacing, provide more active sites for lithium-ion storage, effectively promote Li + adsorption, and improve capacity and rate performance.