Regulating ion transport behaviors toward dendrite-free potassium metal batteries: recent advances and perspectives

With abundant potassium resources and high capacity, potassium metal batteries (PMBs) present a compelling option for the next generation of energy storage technology. However, PMBs suffer from an unstable anode interface caused by uncontrolled dendrite growth, which results in unsatisfactory cyclability and safety concerns. Extensive investigations suggest that significant progress has been made in enhancing the interfacial stability of PMBs. The various effective strategies for stabilizing interfaces can ultimately be attributed to the regulation of the sluggish ion transfer kinetics and irregular deposition, i.e., the arrangement of ion transport behaviors at the interface. Rational modulation of ions transport rate and ions deposition directions makes it possible to obtain a dendrite-free and smooth deposition plane. Herein, the influencing factors and action mechanism of K⁺ interface transport behaviors are discussed to understand the nature of material design for constructing stable anode interfaces, including regulating the solvation and desolvation structures, accelerating K⁺ transport kinetics and controlling K⁺ deposition direction. In addition, the deficiencies and prospects of the research on electrolyte, separators and designed electrode involved in the manufacturing and testing and ion transport process of PMBs are discussed. This review is expected to provide some possible directions for constructing dendrite-free interfaces in advanced PMBs-related research and offer significant insights for prospective experimental research and commercial applications.