A gel polymer electrolyte based on composite of nonwoven fabric and methyl cellulose with good performance for lithium ion batteries

A new composite gel polymer electrolyte of nonwoven fabric (NWF) and methyl cellulose (MC) with good mechanical properties and outstanding thermal and electrochemical stability is prepared by a simple and green casting process followed by absorbing liquid electrolyte. Its characteristics are investigated by scanning electron microscopy, FT-IR, thermogravimetric analysis (TGA). Due to the synergistic action between MC matrix and the NWF framework, the composite gel polymer electrolyte achieves higher ionic conductivity (0.29 mS cm^-1) at ambient temperature and larger lithium ion transference number (0.34) than those for the conventional Celgard 2730 separator (0.21 mS cm^-1 and 0.27, respectively) in 1 mol L^-1 LiPF₆ electrolyte, and their activation energies are similar. In addition, the composite membrane shows better mechanical strength than the pure MC membrane. The evaporation rate of the liquid electrolyte at elevated temperature is much decreased. The assembled Li//LiFePO₄ cell using this composite gel membrane exhibits better cycling retention and higher discharge capacity than those based on Celgard 2730 separator and pure MC gel membrane. These fascinating characteristics suggest that this unique composite gel polymer electrolyte can be used for lithium ion batteries with good performance and low cost.