Epitaxial Growth of Nanostructured Li2Se on Lithium Metal for All Solid‐State Batteries

Abstract Lithium is considered to be the ultimate anode material for high energy‐density rechargeable batteries. Recent emerging technologies of all solid‐state batteries based on sulfide‐based electrolytes raise hope for the practical use of lithium, as it is likely to suppress lithium dendrite growth. However, such devices suffer from undesirable side reactions and a degradation of electrochemical performance. In this work, nanostructured Li 2 Se epitaxially grown on Li metal by chemical vapor deposition are investigated as a protective layer. By adjusting reaction time and cooling rate, a morphology of as‐prepared Li 2 Se is controlled, resulting in nanoparticles, nanorods, or nanowalls with a dominant (220) plane parallel to the (110) plane of the Li metal substrate. Uniaxial pressing the layers under a pressure of 50 MPa for a cell preparation transforms more compact and denser. Dual compatibility of the Li 2 Se layers with strong chemical bonds to Li metal and uniform physical contact to a Li 6 PS 5 Csulfide electrolyte prevents undesirable side reactions and enables a homogeneous charge transfer at the interface upon cycling. As a result, a full cell coupled with a LiCoO 2 ‐based cathode shows significantly enhanced electrochemical performance and demonstrates the practical use of Li anodes with Li 2 Se layers for all solid‐state battery applications.