Solid/Solid Interfacial Architecturing of Solid Polymer Electrolyte–Based All‐Solid‐State Lithium–Sulfur Batteries by Atomic Layer Deposition

Solid polymer electrolytes (SPEs)‐based all‐solid‐state lithium–sulfur batteries (ASSLSBs) have attracted extensive research attention due to their high energy density and safe operation, which provide potential solutions to the increasing need for harnessing higher energy densities. There is little progress made, however, in the development of ASSLSBs to improve simultaneously energy density and long‐term cycling life, mostly due to the “shuttle effect” of lithium polysulfide intermediates in the SPEs and the low interfacial compatibility between the metal lithium anode and the SPE. In this work, the issues of solid/solid interfacial architecturing through atomic layer deposition of Al₂O₃ on poly(ethylene oxide)‐lithium bis(trifluoromethanesulfonyl)imide SPE surface are effectively addressed. The Al₂O₃ coating promotes the suppression of lithium dendrite formation for over 500 h. ASSLSBs fabricated with two layers of Al₂O₃‐coated SPE deliver high gravimetric/areal capacity and Coulombic efficiency, as well as excellent cycling stability and extremely low self‐discharge rate. This work provides not only a simple and effective approach to boost the electrochemical performances of SPE‐based ASSLSBs, but also enriches the fundamental understanding regarding the underlying mechanism responsible for their performance.