NOVELTY - An ion-conductive composition comprises an electrolyte solution containing an ion conductive salt and a solvent, in combination with a thermoplastic resin having a swelling ratio of 150-800%. The ion-conductive salt is soluble in the solvent.    USE - The composition is used for high-performance non-aqueous electrolyte batteries and electrical double-layer capacitors. The capacitors can be used in memory backup power supplies for electronic equipment (e.g., personal computers and wireless terminals), in uninterruptible power supplies for computers, and in transport devices (e.g., electric cars and hybrid cars).    ADVANTAGE - The inventive ion-conductive composition exhibits good strength and strong adhesion to metal foil current collectors. It is able to bond with active materials, and provides lithium ion secondary cells having improved discharge characteristics and reduced loss at a large current. It eliminates cracking during assembly operations and during repeated charging and discharging of batteries.    DETAILED DESCRIPTION - An ion-conductive composition comprises an electrolyte solution containing an ion conductive salt and a solvent, in combination with a thermoplastic resin having a swelling ratio of 150-800%. The ion-conductive salt is soluble in the solvent. The swelling ratio (%) = (weight of swollen thermoplastic resin after 24 hours immersion in electrolyte solution at 20 degreesC (g) / weight of thermoplastic resin before immersion in electrolyte solution at 20 degrees C (g)) % 100.    INDEPENDENT CLAIMS are also included for:    (A) a gel electrolyte;    (B) a non-aqueous electrolyte batter; and    (C) an electrical double-layer capacitor.    The gel electrolyte is prepared by shaping the thermoplastic resin, and immersing the shaped resin in electrolyte solution to effect swelling. The non-aqueous electrolyte battery comprises a positive electrode, a negative electrode, a separator disposed between the positive and negative electrodes, and electrolyte solution. The positive electrode comprises a positive electrode current collector coated with a positive electrode binder composition comprising the thermoplastic resin, and a positive electrode active material. The negative electrode comprises a negative electrode current collector coated with a negative electrode binder composition comprising the thermoplastic resin, and a negative electrode active material. The electrical double-layer capacitor comprises a pair of polarizable electrodes, a separator disposed between the polarizable electrodes, and electrolyte solution. The polarizable electrode(s) comprises a current collector coated with a polarizable electrode binder composition comprising thermoplastic resin, and activated carbon.    DESCRIPTION OF DRAWING(S) - The figure shows a perspective view of a stacked non-aqueous electrolyte battery or electrical double-layer capacitor.