Gelled microporous polymer electrolyte with low liquid leakage for lithium-ion batteries

Gelled microporous polymer electrolyte (GMPE) was prepared by gelating the liquid phase in pores of poly(vinylidene fluoride) membrane with low molecular weight organogelator, 1,3:2,4-di-O-methyl-benzylidene-d-sorbitol (MDBS). Effects of MDBS concentrations on liquid uptake, leakage and ionic conductivity of GMPEs were investigated. The results demonstrated that GMPE containing a certain amount of MDBS showed dramatic decrease in liquid leakage. In consideration of ionic conductivity combining with liquid leakage, the GMPE with 2.0 wt% of MDBS (GMPE-2.0) was used to do further evaluations including electrochemical stability, electrolyte/lithium metal electrode stability and charge/discharge in details. The prepared GMPE-2.0 showed an electrochemical stability window of 4.7 V (vs. Li/Li+). Moreover, tests run on Li/GMPE-2.0/LiFePO4 cell showed better result in terms of discharge retention than that of cell using polymer electrolyte without MDBS (7.0% and 15.1% improvement of capacity retention after 100 cycles at discharge rate of 0.1C and 5C, respectively). These results showed that it was a promising method to prepare safe lithium-ion batteries with high durability and high performance for practical use.