MXene‐Based Dendrite‐Free Potassium Metal Batteries

Abstract Potassium metal batteries are considered as attractive alternatives beyond lithium‐ion batteries. However, uncontrollable dendrite growth on the potassium metal anode has restrained their practical applications. A high‐performance potassium anode achieved by confining potassium metal into a titanium‐deficient nitrogen‐containing MXene/carbon nanotube freestanding scaffold is reported. The high electronic transport and fast potassium diffusion in this scaffold enable reduced local current density and homogeneous ionic flux during plating/stripping processes. Furthermore, as verified by theoretical calculations and experimental investigations, such “potassium‐philic” MXene sheets can induce the nucleation of potassium, and guide potassium to uniformly distribute in the scaffold upon cycling. Consequently, the as‐developed potassium metal anodes exhibit a dendrite‐free morphology with high Coulombic efficiency and long cycle life during plating/stripping processes. Such anodes also deliver significantly improved electrochemical performances in potassium–sulfur batteries compared with bare potassium metal anodes. This work can provide a new avenue for developing potassium metal‐based batteries.