A Biomimetic Polydimethylsiloxane Barrier in the Interface for Stable Potassium Metal Battery Anodes

Potassium (K) metal battery (KMB) anodes have attracted significant attention in the energy storage field due to their high theoretical energy density. Unfortunately, developing high-performance KMB anodes remains a considerable challenge due to dendrite growth. Inspired by the protective and regulating functions of the skin's sebum barrier, we designed a biomimetic polydimethylsiloxane (PDMS)-based protective interface as a barrier for the K metal interface. Based on theory calculations and experimental validation, the PDMS interface consistently and effectively shields K metal from interfacial side reactions. Simultaneously, it facilitates the formation of a more robust solid electrolyte interphase layer, thereby enhancing ion transport dynamics at the interface and improving the uniformity of K metal deposition. The symmetric cell of K@PDMS maintains stable cycling exceeding 2700 h at 0.5 mA cm⁻²/0.5 mAh cm⁻². The excellent cycling stability of the K@PDMS//PTCDA full-cell results in superior electrochemical performance with 71% capacity retention after 500 cycles. This unique interfacial design offers a promising strategy for future KMB anode applications.