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Abstract Potassium‐ion hybrid capacitors have attracted increasing attention due to good energy density, high power density, and low cost. Ti 3 C 2 T x ‐MXene is considered as a promising anode material for K ion storage. However, undesirable stacking issues decrease its exposed area and breeds sluggish K ion transport. Herein, a facile spray‐lyophilization strategy is proposed to construct stacking‐resistant Ti 3 C 2 T x with 3D structures. As‐prepared Ti 3 C 2 T x hollow spheres/tubes present stack resistance, a large specific surface area, and a short ion diffusion pathway. When serving as an anode material, it shows enhanced capacity and thickness‐independent rate performance compared to 2D Ti 3 C 2 T x . After 10 000 cycles, a specific capacity of 122 mAh g −1 is obtained at 1 A g −1 . Systematic kinetics analyses demonstrate the significance of concentration polarization on the electrode's rate ability. Furthermore, a 3D Ti 3 C 2 T x ‖hierarchical porous activated carbon (HPAC) K‐ion hybrid capacitor is assembled and displays remarkable energy and power densities with energy retention of 100% after 10 000 cycles at 1 A g −1 . Following this strategy, other 3D structures from nanosheets can also be obtained, such as 3D Ti 3 C 2 T x microtubes and graphene oxide nanoscrolls. This study provides a viable approach to solve the stacking issues of 2D nanosheets to promote the application of 2D materials.
Fang et al. (Sun,) studied this question.