An Electrochemically Stable Polyester Fabric-reinforced Poly(methyl methacrylate) Gel Polymer Electrolyte for Solid-State Lithium–Oxygen Batteries

Poly(methyl methacrylate) (PMMA) is an ideal polymer matrix for long-term cycling of solid-state lithium–oxygen (Li–O2) batteries using gel polymer electrolytes (GPEs) due to its resistance to nucleophilic attack by the oxygen reduction reaction (ORR) intermediates. However, it is challenging to achieve dimensionally stable gel states with linear PMMA molecules when they are exposed to solvent swelling. To this end, the present work proposes a novel poly(ethylene terephthalate) (PET) fabric reinforcement approach to prepare a dimensionally stable PMMA-based GPE (PMMA@PET GPE) that exhibits a high lithium-ion conductivity of 0.71 mS cm–1 at 25 °C. Benefiting from the chemical and electrochemical stability of PMMA and PET toward lithium metal and ORR intermediates, as well as the mechanical strength and elasticity reinforced by PET fabric that effectively suppress the growth of lithium dendrite, solid-state Li–O2 batteries with PMMA@PET GPE achieve a high reversible capacity of 4.51 mAh cm–2 and 117 stable cycles. PMMA@PET GPE enables a prolonged cycle life 4 times higher than its counterparts including poly(vinylidene fluoride-co hexafluoropropylene) (PVDF-HFP)-based GPE and organic liquid electrolytes. This fabric reinforcement approach would facilitate the application of PMMA-based GPEs in solid-state lithium metal batteries.