Stable Solid Electrolyte Interphase for Long-Life Potassium Metal Batteries
Jimin Park, Min‐Gi Jeong, Muhammad Hilmy Alfaruqi, Yangyang Liu, Xieyu Xu, Shizhao Xiong, Min‐Gi Jung, Hun‐Gi Jung, Jaekook Kim, Jang‐Yeon Hwang, Yang‐Kook Sun
Abstract
Potassium (K) is considered to be the most suitable anode material for rechargeable K batteries because of its high theoretical capacity (686 mAh g–1) and low redox potential (−2.93 V vs SHE). However, uneven electrodeposition of K during cycling usually leads to the growth of dendrites, resulting in low Coulombic efficiency and compromising battery safety. Herein, we develop a strategy for stabilizing K metal through simple interface control. The conductive passivation layer can be controllably designed by a spontaneous chemical reaction when a K metal foil is kept in contact with a liquid-phase potassium-polysulfide (PPS); this guides the formation of an electronically and ionically conductive solid electrolyte interphase layer including K2S compound, enabling dense K plating with a dendrite-free morphology. Compared to the bare K metal anode, the PPS-treated K metal anode demonstrates superior cycling stability in symmetric half cells and full cells using a TiS2 cathode under practical constraints.