A facile in-situ polymerization of cross-linked Poly(ethyl acrylate)-Based gel polymer electrolytes for rechargeable aluminum batteries

Rechargeable aluminum batteries are of interest owing to the nonflammability of Al metal anode and the ionic liquid electrolytes together with the low cost and high capacity of Al metal anode. However, the ionic liquid electrolytes are also moisture sensitive and highly corrosive, bringing about irreversible activity loss, undesired gas production and destructive leakage corrosion, which thus hinder the practical application of rechargeable aluminum batteries. Herein, a gel polymer electrolyte is designed via in-situ cross-linking polymerization of ethyl acrylate (EA) monomer and pentaerythritol acrylate (PETEA) crosslinker in high molar ratio of AlCl3/1-ethyl-3-methylimidazolium chloride (EMIC) ionic liquid. This gel polymer electrolyte exhibits an ionic conductivity of 1.46 × 10−3 S cm−1, a wide electrochemical window up to 3.0 V (vs. Al), alleviated moisture sensitivity and appreciable interfacial stability at room temperature. The assembled solid-state Al//graphite batteries with the gel polymer electrolyte deliver stable capacities of ∼90 mAh g−1 for 1000 cycles at the current density of 100 mA g−1 at both ambient temperature and −10 °C. Even with high-loading graphite cathode of 11 mg cm−2, capacities of ∼60 mAh g−1 can still be obtained for 300 cycles. This work provides a promising strategy for developing reliable and flexible rechargeable aluminum batteries.