Phosphorus-induced interfacial chemistry via electrolyte design for dense and highly stable potassium metal anodes

Potassium (K) metal anodes have attracted widespread attention in the realm of energy storage due to their cost-effectiveness, abundance, and high theoretical capacity. However, the undesirable K-dendrite growth accompanied by void formation upon prolonged cycling presents formidable obstacles to their real-world applications. Herein, phosphorus-based electrolytes are developed based on the electrolyte additive design criteria of steric hindrance, polar ability, and decomposition preference to enhance the anode/electrolyte interface stability. The additive triphenyl phosphate in the electrolyte could regulate the K⁺ solvation structure and promote the formation of an inorganic P-rich solid-electrolyte interphase layer, thus ultimately mitigating interfacial polarization, augmenting transport properties, and stabilizing the interphase. Therefore, we have successfully achieved a dense and dendrite-free K metal anode, exhibiting improved coulombic efficiency and prolonged lifespan. Our design tactic demonstrates the promising application of K metal batteries in achieving elevated safety, high energy densities, and extended operational longevity.