Vertically Aligned MXene Nanosheet Arrays for High-Rate Lithium Metal Anodes

Lithium (Li) metal is considered as one of the best anode materials due to its high theoretical capacity and low reduction potential. However, its practical application is restricted by uneven Li metal dendrite growth. Herein, vertically aligned Ti₃C₂T_x MXene nanosheet arrays synthesized by a facile ice template assisted blade coating method are adopted to regulate Li metal nucleation and guide Li metal deposition. This kind of vertical structure exhibits low tortuosity that can achieve homogeneous and fast Li transport. In addition, the rich -F and -O groups on the Ti₃C₂T_x surface are conducive to the formation of a uniform solid–electrolyte interphase layer, which plays an important role in regulating the nucleation and growth of Li metal. Consequently, the vertically aligned Ti₃C₂T_x electrodes achieve high Coulombic efficiencies (98.8%) for more than 450 cycles at a fixed areal capacity of 1.0 mAh cm⁻² with a current density of 1.0 mA cm⁻². Moreover, it can maintain stable lithium plating/striping behaviors even at an ultrahigh current density of 5.0 mA cm⁻² and high areal capacity of 5.0 mAh cm⁻². Furthermore, full batteries (LiFePO₄ as cathode) paired with these vertically aligned Ti₃C₂T_x electrodes show superior stability and rate performance than the horizontally aligned Ti₃C₂T_x electrodes.