NOVELTY - The non-aqueous electrolyte composition comprises electrolyte salt, non-aqueous solvent, and compound containing phosphorus-hydrogen bond or phosphorus-carbon bond.    USE - The non-aqueous electrolyte composition for secondary battery (claimed). Uses include but are not limited to primary battery and lithium ion secondary battery used as power supply for electronic devices such as camcorder, mobile telephone, digital still camera, video camera, portable information terminal and notebook-type computer.    ADVANTAGE - The non-aqueous electrolyte composition including compound containing phosphorus-hydrogen bond and phosphorus-carbon bond, improves the discharge capacitance maintenance factor of battery during repeated charging and discharging.    DETAILED DESCRIPTION - The non-aqueous electrolyte composition comprises electrolyte salt, non-aqueous solvent, and compound containing phosphorus-hydrogen bond or phosphorus-carbon bond. The compound containing phosphorus-hydrogen bond or phosphorus-carbon bond has hydrogen that can be dissociated as proton. The compound containing phosphorus-hydrogen bond is phosphonic acid and/or phosphinic acid. The compound containing phosphorus-carbon bond is organic phosphonic acid and/or organic phosphinic acid with carbon-carbon multiple bond. The organic phosphonic acid and/or organic phosphinic acid are vinyl phosphonic acid, phenyl phosphonic acid, phenylphosphine acid and/or diphenyl phosphonic acid. The non-aqueous electrolyte composition further contains cyclic anhydride, unsaturated sulfone, cyclic sulfonate ester, cyclic carboxylate ester and/or cyclic-phosphoric-acid ester, carbonate ester with carbon-carbon multiple bond and high molecular compound. The cyclic anhydride is succinic anhydride and/or glutaric acid anhydride. The unsaturated sulfone is divinyl sulfone. The cyclic sulfonate ester is 1,3-propane sultone and/or 1,3-propene sultone. The carbonate ester with carbon-carbon multiple bond is vinylene carbonate. The high molecular compound is polyvinyl formal, polyacrylic acid, polyvinylidene fluoride. The packing component (30) in non-aqueous electrolyte secondary battery has aluminum laminate film (33).    DESCRIPTION OF DRAWING(S) - The drawing shows perspective view of non-aqueous electrolyte secondary battery. (Drawing includes non-English language text).    Anode terminal (18)    Cathode terminal (19)    Battery element (20)    Packing component (30)    Laminate film (33)