The CK bond plays a significant role in stabilizing the Na‐K (NaK) alloy electrodes due to the enhancive interfacial affinity. In this study, a method for constructing semi‐solid K metal electrodes with rich CK bonds by in situ replacement of N‐doped carbon nanotubes (CNT) and liquid NaK alloy is proposed. Based on the in situ infrared thermal imaging technique combined with heat calculation, X‐ray photoelectron spectroscopy elemental analysis, and reaction thermodynamic calculation, graphite‐N, which is widely distributed on the wall of CNT, offers plenty of replacement sites for forming CK bonds. Due to the rich bonds, the amount of CNT sharply reduces in dendrite‐free semi‐solid CNT@NaK electrodes and the activity of NaK alloy raises to ≈90%. This discovery provides a new idea for establishing dendrite‐free anodes for K metal batteries.

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Separators with low-cost, superior mechanical properties, such as nanofiber materials, are considered a viable option for solving the dendritic problem in alkali metal batteries. Consuming the dendrites rather than blocking them underpins the long-life stable cycle performance of the cell. Herein, a five-layer structural separator (LiNO 3 @PVDF@mask) is presented, in which a mask is used as a framework and the polyvinylidene fluoride (PVDF) layer loaded with LiNO 3 can generate a passivation layer by reacting with K dendrites. In the case of potassium metal batteries, for example, the LiNO 3 @PVDF@mask separator has excellent mechanical properties that can effectively cope with the hazards caused by the K dendrite. In addition, sustained-release LiNO 3 can react with penetrated K dendrites to form inactive substances like KNO 3 and K 2 O, blocking further dendrite growth. Importantly, the LiNO 3 @PVDF@mask separator uses a low-cost abundant mask and possesses excellent wettability of electrolyte with a reduced amount of liquid electrolyte, enabling one to further iron out cost problems. This study opens up a new direction for research and contributes to practical applications of flexible devices for rechargeable alkaline metal batteries.

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