Molecular Crowding Solid Polymer Electrolytes for Lithium Metal Battery by In Situ Polymerization

Solid-state polymer electrolytes (SPEs) require high ionic conductivity and dense contact with the electrodes for high-performance lithium-metal solid-state batteries. However, massive challenges such as poor ionic migration ability, low antioxidant ability, and lithium dendrite formation still remain unresolved. These issues severely restrict its practical applications. Herein, a new type of solid-state polymer electrolyte with a molecular crowding feature is rationally designed by in situ polymerization of a precursor containing poly (ethylene glycol) diacrylate (PEGDA) and 1,2-dimethoxyethane (DME). Noticeably, the prepared SPE expands the electrochemical window to 4.7 V with a high lithium-ion transfer number of 0.55 and a superior ionic conductivity of 3.6 mS cm⁻¹ at room temperature. As a result, the lithium symmetrical batteries achieve stable cycles with more than 3000 h with no lithium dendrites at a current density of 0.5 mA cm⁻². Importantly, this design provides dense contact of solid-state polymer electrolytes with the porous cathode and lithium anode, allowing the assembled winding-type solid-state pouch cells with outstanding cycling stability of 81.7% retention for more than 340 cycles at room temperature. It shows excellent adaption to widely practical technology with large-scale battery production, offering a new solution for the future development of solid-state polymer lithium-metal batteries.