Poly(AN-co-GMA-IDA) has been prepared by copolymerizing acrylonitrile (AN) and 2-methylacrylic acid 3-(bis-carboxymethylamino-2-hydroxy-propyl ester) (GMA-IDA). The polymers were mixed with the plasticizer ethylene carbonate (EC) and lithium perchlorate (LiClO4) to form gel polymer electrolytes (GPE). Fourier-transform infrared spectroscopy (FT-IR) has revealed that the GMA-IDA unit can improve the dissociation of the lithium salt. Furthermore, the GMA-IDA can hinder the crystallization of EC, thereby improving the conductivity of the GPE. This has been established by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. The interaction between GMA-IDA and EC has been confirmed by FT-IR and 7Li solid-state NMR. The maximum conductivity measured in this investigation was 9.75×10−4 Scm−1.