The effect of both nanoparticles and low molecular weight borate esters on the ionic conductivity of cross-linked polysiloxanes was systematically investigated by means of measuring conductivity spectra in the impedance regime at temperatures between− 30 and 90° C. Salt-in-polymer electrolytes were prepared by dissolving lithium triflate (LiSO3CF3) in comblike polysiloxanes bearing one methyl and one oligoether side group per silicon. An ...