Facile Design of Sulfide‐Based all Solid‐State Lithium Metal Battery: In Situ Polymerization within Self‐Supported Porous Argyrodite Skeleton

All solid-state batteries holds great promise for superiorly safe and high energy electrochemical energy storage. The ionic conductivity of electrolytes and its interfacial compatibility with the electrode are two critical factors in determining the electrochemical performance of all solid-state batteries. It is a great challenge to simultaneously demonstrate fantastic ionic conductivity and compatible electrolyte/electrode interface to acquire a well-performed all solid-state battery. By in situ polymerizing poly(ethylene glycol) methyl ether acrylate within a self-supported 3D porous Li-argyrodite (Li6PS5Cl) skeleton, the two bottlenecks are tackled successfully at once. As a result, all solid-state lithium metal batteries with a 4.5 V LiNi0.8Mn0.1Co0.1O2 cathode designed by this integrated strategy demonstrates a high Coulombic efficiency exceeding 99% at room temperature. Solid-state nuclear magnetic resonance data suggest that Li+ mainly migrates along the continuous Li6PS5Cl phase to result in a room temperature conductivity of 4.6 × 10−4 S cm−1, which is 128 times higher than that of the corresponding polymer. Meanwhile, the inferior solid–solid electrolyte/electrode interface is integrated via in situ polymerization to lessen the interfacial resistance significantly. This study thereby provides a very promising strategy of solid electrolyte design to simultaneously meet both high ionic conductivity and good interfacial compatibility towards practical high-energy-density all solid-state lithium batteries.