Organic-inorganic hybrid electrolytes based on PEO-NaTFSI-ionic liquid (HMIMTFSI)-silica (in situ production via sol gel process) are being reported in this article. The variation in conductivity with ionic liquid (IL) addition has been explained on the basis of number of free TFSI anions evaluated using ATR-IR data. The deconvolution of the IR spectra of these hybrid electrolytes has given evidence of ion-pair formation which has been compared vis-a-vis the conductivity variation. The hybrid electrolyte with maximum conductivity comprises the highest number of free imide ions and has lowest glass transition temperature. FESEM has displayed a porous and layered surface morphology with dispersed silica nanoparticles. In addition, the optimized hybrid electrolyte has been compared with 5 wt% (limit of mechanical stability) ex situ silica added composite where the temperature cycling of conductivity has shown that the ex situ dispersed hybrid electrolytes do not retrace their conductivity path contrary to the in situ prepared hybrid electrolytes. This behavior has been explained to be due to the hindrance offered by the ex situ added silica in the recrystallization kinetics of PEO. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 207-218