TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The polymeric electrolyte composition further comprises 20 wt.% of lithium salt. The ethylene oxide-containing polymer includes polyethylene oxide homopolymer, and/or ethylene oxide copolymer including one or more additional alkoxide monomers, and has mole fraction of more than 0.8, and crystallinity of more than 60 wt.%, or less than 58 wt.%. Organic microparticles are in latex state and includes hollow organic microparticles (20 wt.%) having void fraction of 0.3 or more, water (20 wt.%), and styrene-containing polymer having glass transition temperature (Tg) measured by dynamic mechanical analysis based on ASTM E1640-99. The styrene-containing polymer is selected from styrene-butadiene block copolymer, styrene-isoprene block copolymer, polystyrene homopolymer, polystyrene random copolymer, high impact polystyrene, styrene-acrylonitrile block copolymer, acrylonitrile-butadiene-styrene block copolymer and/or hydrogenated and partially hydrogenated analogs of isoprene- and butadiene-containing copolymers. The content of phase (I) and phase (II) is more than 5 volume% and more than 20 volume%, respectively with respect to total volume of the electrolyte composition. The phase (II) includes aprotic solvent, lithium salt, and polyethylene oxide. Preferred Properties: The polymeric electrolyte composition has shear modulus (G') which is more than 50% of the shear modulus of ethylene oxide-containing polymer measured by dynamic mechanical analysis based on ASTM 5270-08, and 104-1010 dynes/cm2 measured by dynamic mechanical analysis based on ASTM D5279-08 at 1 radian/second and 30 degrees C. The polymeric electrolyte composition has ionic conductivity ( sigma ) of more than 200% of ionic conductivity of electrolyte composition which is free from porous organic particles. The ionic conductivity is measured by alternating current (AC) impedance spectroscopy in a solartron using an AC amplitude of 10 mV at 30 degrees C, such that the product of shear modulus and ionic conductivity is more than 200 (S/cm)(dynes/cm2).