Solid polymer electrolytes (SPEs) have wide-scale applications in the fields of energy storage (capacitors and batteries), power conversion (fuel cells), electrochemical sensing etc. In the present work, poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) based SPEs with varying concentration of lithium triflate and composite solid polymer electrolytes (CSPEs) composed of BaTiO3 in addition to the optimised loading of lithium triflate in PVDF-HFP matrix are synthesized by solution casting technique. SPE with 10wt.% lithium triflate shows highest DC conductivity of 2.19×10−6 Scm−1 at 300K, which enhances to 8.89×10−6 Scm−1 by adding 4wt.% of BaTiO3. X-Ray diffraction (XRD) and scanning electron microscopy (SEM) analysis shows that the reduction in crystallite size of the polymeric matrix assists in enhancing the conductivity. Hence, the crystallite size, by altering the arrangement of the non-conducting polymeric chains, affects the ionic conductivity of the composites significantly.