Enhanced performance of a novel gel polymer electrolyte by dual plasticizers

In this contribution, polyethylene glycol dilaurate (PEGDL) is synthesized and adopted as the physical cross-linking agent to enhance the performance, especially the mechanical property of the gel polymer electrolytes (GPEs). With polyethylene glycol dimethyl ether (PEGDME) as the main plasticizer and PEGDL as the secondary plasticizer, several gel polymer electrolytes based on a copolymer of methoxy-poly(ethylene glycol) methacrylate (MPEGM) and hexadecal-poly(ethylene glycol) methacrylate (HPEGM) are prepared by UV radiation curing. The relationship between the composition of the GPE and the physical properties, e.g., thermal property, mechanical property and ionic conductivity, is investigated. The lithium ion transference number, lithium/GPE interfacial property and charge-discharge performance of the lithium polymer cell based on the physically cross-linked GPE are studied. The gel polymer electrolyte prepared with the optimum composition exhibits excellent mechanical properties and a relatively high ionic conductivity (8.2 × 10^-4 S cm^-1 at 30 C). A coin cell Li/GPE/LiFePO₄, shows a discharge capacity 152 mAh g^-1 and 163 mAh g^-1 when cycled at 30 C and 50 C, respectively, under a current density of 0.1 C.