All‐Solid‐State Printed Bipolar Li–S Batteries

Abstract Despite their potential advantages over currently widespread lithium‐ion batteries, lithium–sulfur (Li–S) batteries are not yet in practical use. Here, for the first time bipolar all‐solid‐state Li–S batteries (ASSLSBs) are demonstrated that exhibit exceptional safety, flexibility, and aesthetics. The bipolar ASSLSBs are fabricated through a solvent‐drying‐free, ultraviolet curing‐assisted stepwise printing process at ambient conditions, without (high‐temperature/high‐pressure) sintering steps that are required for inorganic electrolyte‐based all‐solid‐state batteries. Two thermodynamically immiscible and nonflammable gel electrolytes based on ethyl methyl sulfone (EMS) and tetraethylene glycol dimethyl ether (TEGDME) are used to address longstanding concerns regarding the grain boundary resistance of conventional inorganic solid electrolytes, as well as the polysulfide shuttle effect in Li–S batteries. The EMS gel electrolytes embedded in the sulfur cathodes facilitate sulfur utilization, while the TEGDME gel composite electrolytes serve as polysulfide‐repelling separator membranes. Benefiting from the well‐designed cell components and printing‐driven facile processability, the resulting bipolar ASSLSBs exhibit unforeseen advancements in bipolar cell configuration, safety, foldability, and form factors, which lie far beyond those achievable with conventional Li–S battery technologies.