Exploring Self-Healing Liquid Na-K Alloy for Dendrite-Free Electrochemical Energy Storage

The development of high-performance dendrite-free liquid-metal anodes at room temperature is of great importance for the advancement of alkali metal batteries. Herein an intriguing self-healing liquid dendrite-free Na-K alloy, fabricated by a facile room-temperature alloying process, aiming for application in potassium-ion batteries is reported. Through extensive investigation, its self-healing characteristics are rooted upon a thin solid K₂ O layer (KOL) coated on the liquid Na-K alloy. The KOL not only acts as a protective layer to prevent the Na-K alloy from making contact with the electrolyte, but also greatly improves the wetting capability and adhesion between the liquid alloy and the carbon matrix (e.g., carbon fiber cloth (CFC)) to form a stable interface. Consequently, the as-prepared CFC/KOL@Na-K alloy anode exhibits prominent electrochemical performance with smaller hysteresis (less than 0.3 V beyond 140 cycles at 0.4 mA cm^-2 ), better capacity retention, and higher Coulombic efficiency than the CFC/bare Na-K alloy counterpart. When coupled with a potassium Prussian blue (PPB) cathode, the full cell manifests higher capability retention and improved cycling stability. This research deepens the understanding of self-healing Na-K alloys and opens a new way to achieve high-performance dendrite-free alkali metal anodes for application in rechargeable batteries.