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

Abstract The energetic chemical reaction between Zn(NO 3 ) 2 and Li is used to create a solid‐state interface between Li metal and Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) electrolyte. This interlayer, composed of Zn, ZnLi x alloy, Li 3 N, Li 2 O, 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.