DMSO/PEO‐Based Gel Polymer Electrolyte for Li–O ₂ Batteries

We investigate gel polymer electrolytes (GPEs) based on poly(ethylene oxide) (PEO) dissolved in dimethyl sulfoxide (DMSO) with LiTFSI for application in Li–O ₂ batteries. A simple preparation route yields GPEs with tunable ionic conductivity controlled by the wt% of PEO. The resulting gels exhibit greater resistance to solvent oxidation compared to the analogous liquid electrolyte, while retaining the ability to promote oxygen‐reduction pathways characteristic of conventional Li–O ₂ systems. Li–O ₂ cells incorporating these GPEs display outstanding cycling performance, achieving up to 4 times longer cycle life than cells employing liquid electrolytes and reaching 500 h of operation at 0.1 mA cm ⁻² (26 mAh cm ⁻² ). Postmortem analysis revealed that the primary cause of capacity fade is the degradation of the GPE, particularly in regions adjacent to the lithium metal. These results highlight PEO‐based GPEs as promising and easily processable electrolytes for improving the durability and safety of Li–O ₂ batteries.