Experimental and computational techniques have been applied to investigate the influence of Li0.5La0.5TiO3 nanoparticles on the ionic conductivity of the poly(vinylidene fluoride) (PVDF)/LiClO4 nanocomposite solid polymer electrolyte. The theoretical evidence facilitated to suggest a plausible mechanism for Li-ion conduction across the PVDF/LiClO4/Li0.5La0.5TiO3 based solid polymer electrolytes. The solid composite polymer electrolyte with 30wt% of Li0.5La0.5TiO3 (LLTO) nanofiller exhibited an unprecedented ionic conductivity of 2.3687 × 10-3 S cm-1 at room temperature. The addition of LLTO nanoparticles to the polymer matrix enhanced its ionic conductivity by two orders of magnitude. The activation energy (Ea) and total transference number (t) were estimated to be 0.29 eV and 0.853, respectively. The interaction between the filler and polymer matrix has been inferred by the density functional theory (DFT)-IR analysis. The DFT calculations have been performed on the above system using the basis set of B3LYP-LANL2DZ. The calculated IR spectra were compared with the experimental FTIR data, which allowed us to propose accurate vibrational assignments and to clarify the complex IR vibration of the samples. All-solid-state Li2FeSiO4/CPVDF/LiClO4/LLTO graphite lithium cell has been fabricated using the highest Li-ion conducting PVDF/LiClO4/LLTO composite polymer electrolyte. The all-solid-state cell exhibits an excellent initial specific capacity of 87.13 and 73.24 mAh g-1 after 30 cycles, demonstrating higher capacity retention. The findings provide an avenue for exploring the simple all-solid-state lithium batteries, which are potential candidates for next-generation energy storage technology.