Efficient Self-Assembly Preparation of 3D Carbon-Supported Ti 3 C 2 T x Hollow Spheres for High-Performance Potassium Ion Batteries.

MXenes are considered a promising negative electrode material for potassium ion batteries (PIBs) in view of their low potassium ion diffusion barrier and excellent electrical conductivity. However, the stacking phenomenon in practical applications severely reduces their active surface and leads to slow K + diffusion. Herein, a facile composite template method is proposed to construct stacking-resistance 3D carbon-supported Ti 3 C 2 T x (3D-C@Ti 3 C 2 T x ) hollow spheres. Due to the unique structure, when used as a negative electrode material, as-prepared 3D-C@Ti 3 C 2 T x hollow spheres show not only improved rate capability with 160.4 mAh g -1 at 100 mA g -1 and 133.7 mAh g -1 at 500 mA g -1 , but also stable cycling performance with 142.5 mAh g -1 specific capacity remained at 2 A g -1 after 4200 cycles. Furthermore, the full cells with 3D-C@Ti 3 C 2 T x anode can operate stably for 1000 cycles at 100 mA g -1 . Moreover, the linear fit analysis demonstrates that 3D-C@Ti 3 C 2 T x hollow spheres have a fast and stable capacitive potassium storage mechanism. This method is simple and easy to implement, which provide a feasible path to solve the stacking problem of 2D materials.