Recent advances and perspectives in stable and dendrite-free potassium metal anodes

Potassium (K) metal is the "super star" among all the anode materials for potassium-ion batteries because of its merits such as large abundance (similar to 0.0017 wt %), high theoretical specific capacity (687 mAh g(-1)) and low electrochemical potential (-2.93 V vs. the standard hydrogen electrode, SHE). Nevertheless, challenges such as extremely high reactivity, large volume change, unstable interface and uncontrollable growth of K dendrites hinder its further development and practical application. Various effective tactics have been put forward to solve the issues of K metal anodes in recent years. Herein, we detailedly summarize the recent strategies for stable and dendrite-free K metal anodes such as designing a host, interfacial engineering, replacing pure K metal with K-based alloys, modifying liquid electrolyte and replacing liquid electrolyte with solid-state electrolyte. We also proposed some perspectives and outlooks. We believe this review can attract related researchers and provide some help for the future development of K metal anodes.