Crosslinked Gel Polymer Electrolytes for Si Anodes in Li-Ion Batteries

Gel polymer electrolyte (GPE) membrane was prepared by the facile amine-epoxy crosslinking reaction of poly(ethylene glycol)diglycidylether (PEGDE) with diamino-poly(propylene oxide) (DPPO) and subsequent immersion in 1 M LiPF6 solution. To apply GPE for Si anode in a Li-ion battery, the physical properties were optimized by the degree of crosslinking which was controlled by molecular weight of each part. The crosslinked GPE membrane composed of PEGDE(1,000 g mol−1) and DPPO (4,000 g mol−1) exhibited desirable dimensional stability, low electrical resistance, adequate ionic conductivity of 1.0 mS cm−1 at 25°C. The Si anode cell employing this GPE exhibited enhanced battery performance of 2,434 mAhg−1 and 80% cyclic retention after 100 cycles. The well-optimized cGPE with desirable physical properties could resolve the issues of safety and stability resulted from volume expansion of Si as well as Li dendrite formation.