Gel polymer electrolyte based on PVdF-HFP/PEGDME/LiNO3 for stable solid-state lithium metal batteries at room temperature

All-solid-state lithium metal batteries (ASSLMB) are emerging technologies that have gained significant attention due to their potential to revolutionize energy storage systems. Replacing traditional organic liquid electrolytes by solid-state electrolytes can resolve serious safety concerns, chemical/electrochemical instability leading to dendrite formation and short cycle life of lithium-metal batteries. In this work, gel polymer electrolytes (GPEs) were successfully fabricated by using poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF−HFP) mixing with lithium nitrate (LiNO3) and poly(ethylene glycol) dimethyl ether (PEGDME). Specifically, the obtained GPEs were thermal stable up to 200 °C and electrochemical stable up to 4.5 V. The GPE with ethylene oxide (EO): Li = 40:1 demonstrated an ionic conductivity ~ 1.50 × 10⁻⁵ S cm⁻¹ at 30 °C, which is considered suitable for the cell’s performance at this temperature. Indeed, all solid-state Li||LiFePO4 using this GPE displayed good cycling performance at various rates, typically its retention capacity after 50 cycles at the current density of C/10 was 85% at 30 °C.