Realizing a dendrite-free metallic-potassium anode using reactive prewetting chemistry

Potassium metal batteries (PMBs) have become a paramount alternative energy storage technology to lithium-ion batteries, due to their low cost and potential energy density. However, uncontrolled dendrite growth interferes with the stability of the interfacial anode, leading to significant capacity degradation and safety hazards. Herein, a facile reactive prewetting strategy is proposed to discourage dendrite growth by constructing a functional KF/Zn-rich hybrid interface layer on K metal. The KF/Zn@K anode design functions like an interconnected paddy field, stabilizing the anode interface through the preferential redistribution of K⁺ flux/electrons, continuous transport paths, and enhanced transport dynamics. As anticipated, symmetrical batteries exhibit an extended cycling lifetime of over 2000 ​h, with reduced voltage hysteresis at 0.5 ​mA ​cm⁻² and 0.5 mAh cm⁻². Furthermore, when the KF/Zn@K anode is applied to full batteries coupled with PTCDA, a boosted reversible capacity of 61.6 mAh g⁻¹ at 5 ​C is present over 3000 cycles. This interfacial control creates rational possibilities for constructing high-efficiency, stable K metal anodes.