Gel polymer composites electrolytes containing nano LiAlO2 as filler were prepared using a solution cast technique and characterized using different techniques such as X-ray diffraction (XRD), thermal analysis (TG, DSC), Fourier transform infra e red spectroscopy (FT-IR) and scanning electron microscope (SEM). Xray diffraction analysis showed the effect of lithium tri fluoro methane sulphonate (LiCF3SO3), poly vinyl acetate (PVAc) and nano lithium aluminate (LiAlO2) on the crystalline structure of the poly vinylidene fluoride ecoe hexa fluoro propylene (PVDF-co-HFP) matrix containing ethylene carbonate (EC) and diethyl carbonate (DEC) as plasticizers. FT-IR analysis confirmed both the good dissolution of the LiCF3SO3 salt and the good interaction of the nano LiAlO2 filler with the polymer matrix. TG analysis showed the good thermal stability of the LiAlO2 samples compared to the free one. Also, addition of nano LiAlO2 filler enhanced the conductivity value of the polymer composites electrolytes. The sample containing 2 wt% of LiAlO2 showed the highest conductivity value, 4.98
103 U 1 cm1 at room temperature, with good thermal stability behavior (Td ¼ 362 C). This good conductive and thermally stable polymer nano composite electrolyte was evaluated as a promising membrane for lithium ion batteries application.