Alloy‐Boosted Potassiophilic Membrane Interphase for Ultrastable K Metal Anodes

Abstract The advancement of K metal anodes has long been hindered by challenges including dendrite proliferation and volume expansion amid electrochemical cycles. Generic interlayer design for extended anodes and its K uptake/release mechanism remain unexplored to date. Herein, a generic alloy‐boosted strategy is reported to devise a ZnX‐loaded (X = S, Se or Te) porous carbon nanofiber (PCNF) membrane as an efficient 3D interphase layer for K metal anodes. Theoretical computations and experimental investigations suggest that representative ZnTe acts as an alloying site, thereby reducing the nucleation energy barrier and optimizing the deposition pattern of K. Such a maneuver enables dendrite‐free plating of K metal within the interface layer, which facilitates the construction of an extended K anode. As a result, the symmetric cell modified with ZnTe@PCNF demonstrates a lifespan of over 3100 h. When coupled with a cathode, the full cell delivers a capacity retention of 94% after 500 cycles at 1.0 A g⁻¹, showing its potential for the development of practically viable K metal batteries.