A Highly Efficient All‐Solid‐State Lithium/Electrolyte Interface Induced by an Energetic Reaction

The energetic chemical reaction between Zn(NO3)2 and Li is used to create a solid‐state interface between Li metal and Li6.4La3Zr1.4Ta0.6O12 (LLZTO) electrolyte. This interlayer, composed of Zn, ZnLix alloy, Li3N, Li2O, and other species, possesses strong affinities with both Li metal and LLZTO and affords highly efficient conductive pathways for Li+ transport through the interface. The unique structure and properties of the interlayer lead to Li metal anodes with longer cycle life, higher efficiency, and better safety compared to the current best Li metal electrodes operating in liquid electrolytes while retaining comparable capacity, rate, and overpotential. All‐solid‐state Li||Li cells can operate at very demanding current–capacity conditions of 4 mA cm−2–8 mAh cm−2. Thousands of hours of continuous cycling are achieved at Coulombic efficiency >99.5 % without dendrite formation or side reactions with the electrolyte. The energetic reaction between Li and Zn(NO3)2 is employed to create a solid‐state interface between Li metal and Li6.4La3Zr1.4Ta0.6O12 electrolyte, enabling high capacity, fast charging–discharging rates, and small overpotentials matching the performance of liquid‐electrolyte Li metal electrodes, but with longer cycle life, higher efficiency, and better safety.