Polypropylene-supported and nano-Al_2O_3 doped poly(ethylene oxide)-poly(vinylidene fluoride-hexafluoropropylene)-based gel electrolyte for lithium ion batteries

摘要

A new gel polymer electrolyte (GPE) is reported in this paper. In this GPE, blending polymer of poly(ethylene oxide) (PEO) with poly(vinylidene fluoride-hexafluoropropylene) (P(VdF-HFP)), doped with nano-Al_2O_3 and supported by polypropylene (PP), is used as polymer matrix, namely PEO-P(VdF-HFP)-Al_2O_3/PP. The performances of the PEO-P(VdF-HFP)-Al_2O_3/PP membrane and the corresponding GPE are characterized with mechanical test, CA, EIS, TGA and charge-discharge test. It is found that the performances of the membrane and the GPE depend to a great extent on the content of doped nano-Al_2O_3. With doping 10 wt.% nano-Al_2O_3 in PEO-P(VdF-HFP), the mechanical strength from 9.3 MPa to 14.3 MPa, the porosity of the membrane increases from 42% to 49%, the electrolyte uptake from 176% to 273%, the thermal decomposition temperature from 225 ℃ to 355 ℃, and the ionic conductivity of corresponding GPE is improved from 2.7 × 10~(-3) Scm~(-1) to 3.8 × 10~(-3) S cm~(-1). The lithium ion battery using this GPE exhibits good rate and cycle performances.