Composite gel electrolyte for rechargeable lithium batteries

Composite polymer electrolyte films consisting of zeolite powders dispersed in poly(acrylonitrile) (PAN)-based gels with LiAsF6 have been prepared and their electrochemical properties studied. Gel electrolytes prepared by adding LiAsF6 in propylene carbonate (PC) and ethylene carbonate (EC) mixtures with PAN have demonstrated ionic conductivities greater than 10−3 S/cm at room temperature and above. The addition of zeolite powders increased ionic conductivity at low temperatures due to the highly amorphous nature of the composite film. Impedance spectroscopy was performed to study the Li electrode/electrolyte interface and a reduction of the passivation kinetics was observed. Cyclic voltammetry showed that addition of PAN and zeolite powder to LiAsF6, PC and EC mixtures did not change the stable electrochemical potential window. In Li/LiCoO2 cells, at 25 °C, these composite electrolytes demonstrated current densities as high as 0.5 mA/cm2, with little voltage or capacity loss compared with cells with liquid electrolytes.