Polyimide-Based Solid-State Gel Polymer Electrolyte for Lithium–Oxygen Batteries with a Long-Cycling Life

Metal–air batteries have attracted wide interest owing to their ultrahigh theoretical energy densities, particularly for lithium–oxygen batteries. One of the challenges inhibiting the practical application of lithium–oxygen batteries is the unavoidable liquid electrolyte evaporation accompanying oxygen fluxion in the semi-open system, which leads to safety issues and poor cyclic performance. To address these issues, we propose a solid-state polyimide based gel polymer electrolyte (PI@GPE), immobilizing and reserving a liquid electrolyte in the gelled polymer substrate. The liquid electrolyte uptake of PI@GPE is measured to be 842%, 6 times higher than that of the commercial glass fiber separator, contributing to a high ionic conductivity of 0.44 mS cm –1 . Additionally, PI@GPE possesses an enhanced lithium transference number of 0.596 as well as superior interfacial compatibility with lithium metals. Under 0.1 mA cm –2 and 0.25 mA h cm –2, PI@GPE-based lithium–oxygen batteries demonstrate distinguished long-cycling stability of 366 cycles, 4 times more than that with a glass fiber separator and liquid electrolyte. Our work provides a unique solid-state gel polymer electrolyte to mitigate liquid electrolyte leakage, exhibiting promising potential application in highly safe lithium–oxygen batteries with a long-cycling life.