Single‐Atom Metallophilic Sites for Liquid NaK Alloy Confinement toward Stable Alkali‐Metal Anodes

Room temperature liquid NaK alloy is a promising candidate for high performance metal batteries, due to its dendrite‐free property and high energy density. However, its practical application is hindered by the high surface tension of liquid NaK, which causes difficulties in maintaining a stable contact with a current collector. Here, the authors demonstrate the extraordinary stable confinement of NaK alloy at room temperature by constructing a super‐wetting substrate, which is based on highly dispersed cobalt‐single‐atom carbon nanoarrays. The developed liquid anode electrode prevented successfully the leakage of NaK alloy even in harsh stress (>5 MPa) or sharp shock conditions. The symmetric cells achieved ultra‐long reversible plating/stripping cycling life in both Na‐ion (>1010 hrs) and K‐ion electrolytes (>4000 hrs) at 10 mA cm(−2)/10 mAh cm(−2). Upon fitting with Na(3)V(2)(PO(4))(3), the NaK assembled full battery provided high energy density (332.6 kWh kg(−1)) and power density (11.05 kW kg(−1)) with excellent stability after >21600 cycles, which is the best value reported so far. The prepared pouch cell was able to drive a four‐axis aircraft, demonstrating a great prospect in practical application. This work offers a new approach in the preparation of advanced dendrite‐free liquid metal anodes with promising applications in electrochemical energy storage.