Lithium Salt-Induced In Situ Living Radical Polymerizations Enable Polymer Electrolytes for Lithium-Ion Batteries

Herein, polymer electrolytes (PEs) were designed and fabricated through lithium salt-induced in situ living radical copolymerization of poly(ethylene glycol) methacrylate (PEGMA) and various (meth)acrylates monomers (methyl methacrylate (MMA), n-butyl acrylate (BA), n-butyl methacrylate (BMA), or styrene) with 18-crown-6-ether (18CE6) as both the solvent of copolymerization and the plasticizer of PEs. The lithium salt plays a dual role of activator for alkyl halides (R–X, X = Br or I) initiators, and lithium-ion source. The polymer electrolyte in situ formed in the Li/LiFePO4 cell with a cellulose membrane showed excellent compatibility with electrode materials. The Li/P(PEGMA-co-MMA)-based PE/LiFePO4 cell possessed an initial discharge capacity of 166.5 mAh g–1 at 0.2C and maintained a capacity of 155.3 mAh g–1 at 0.2C after 290 cycles. The lithium salt-induced in situ polymerization offers a new strategy toward polymer electrolytes for high-performance lithium-ion batteries.