Polymeric gel electrolytes, based on a blend of poly(methylmethacrylate)/poly(vinylidene fluoride) (PMMA/PVdF), ethylene carbonate/propylene carbonate (EC/PC) as plasticizer and lithium perchlorate as electrolyte, have been studied as a function of the different polymeric ratios to obtain the best compromise between ionic conduction and mechanical properties of the systems involved. Ionic conductivity and the lithium self-diffusion coefficient were measured by the PFG–NMR method, which revealed a maximum of lithium mobility for the composition PMMA 60%–PVdF 40%. The Raman spectroscopic study revealed a change of the interaction between that of the lithium cations and the plasticizer molecules for different PMMA / PVdF ratios. Oscillatory rheological tests have shown better mechanical properties for the intermediate compositions of the blend.