Dendrite-free and gasless potassium metal anodes assisted by the mechanical-electrochemical enhancing solid K-electrode and electrolyte interface

With their high-energy density and low-price advantage, potassium (K) metal batteries have been considered the next generation of energy storage system. However, applications of K metal anode are always obstructed by severe side reactions and rapid growth of K dendrites upon cycles due to the fragile solid electrolyte interface (SEI). Herein, a novel mechanical-electrochemical stability enhancement interface is constructed through potassium salt anion structure design and in-situ ion exchange reaction, which enables SEI with reducing side reactions and relieving interface stress during cycling process. The batteries with the designed SEI could deliver excellent performances with a high average Coulombic Efficiency of 95.91 %, a critical current density of 7.5 mA cm-2 and a durable stability of more than 1350 h (0.1 mA cm-2). This work provides an effective strategy to construct a high-energy and stable K metal anode interface and will inspire the electrolyte design for other alkali metal batteries.