Synergistic Stabilization of Potassium Metal Anodes Through Orange‐Peel Elimination and Robust Solid–Electrolyte Interphase Formation

Potassium (K) metal anodes are attractive for next‐generation rechargeable batteries due to their low redox potential and elemental abundance, yet their practical application is hindered by dendrite growth and unstable solid‐electrolyte interphases (SEIs). Here, we replace conventional roll pressing with a cutting‐based fabrication strategy to produce crystallographically more uniform and minimally deformed K surfaces, while independently tuning SEI chemistry through electrolyte concentration. This approach establishes a unified framework that elucidates the synergistic coupling between surface uniformity and SEI robustness in governing K plating/stripping stability. Only their synergy delivers fast kinetics, high areal capacity, and long‐term reversibility. Consequently, optimized K||K symmetric cells operate stably for over 4 000 h at 0.5 mA cm −2 and 4 mA h cm −2 . Full cells paired with K 1.97 Mn[Fe(CN) 6 ] cathodes retain 90% capacity after 1200 cycles. These findings highlight the importance of concurrent morphological and interfacial regulation for practical K metal anodes.