TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The carbon nanofiber is present in an amount 10 - 50 pbw. The fluorine-containing compound is phenyl (hexa substituted at positions 1 - 6 by R1, R2, R3 R4, R5 and R6 respectively) (preferably monofluorobenzene) (5 - 30 pbw) or (1,3)dioxolan-2-one (di-substituted at position 4 by R7 and H) (5 - 30 %). The negative electrode active material includes a compound of formula SiOx (at least 50 wt.%).R1 - R6=fluorine atom or hydrogen atom;R7=fluorine atom or methyl group (where at least one hydrogen atom is replaced with a fluorine atom);x=0.05 - 1.95.At least one of R1 - R6 is a fluorine atom. EXAMPLE - Non-Aqueous Electrolyte was prepared as follows: To a solvent mixture (second solvent) including ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 30:70, LiPF6 was dissolved in a concentration of 1 mol/l. To the solution, monofluorobenzene (FB) (15 pbw) was added to prepare a non-aqueous electrolyte. Positive electrode preparation was prepared as follows: the positive electrode active material (LiNi0.8Co0.2O2) powder (average particle size of 5 microns) (85 pbw), acetylene black as a conductive agent (10 pbw), and polyvinylidene fluoride as a binder (5 pbw) were mixed. The obtained mixture was dispersed in dehydrated N-methyl-2-pyrrolidone, to prepare a slurry of a positive electrode material mixture. The obtained positive electrode material mixture was applied on both sides of an aluminum foil with a thickness of 20 microns, dried, and rolled, to obtain a positive electrode plate. Negative electrode preparation was prepared as follows: silicon monoxide powder (100 pbw) which was crushed in advance and classified to give a particle size of less than or equal to10 microns; nickel(II) nitrate hexahydrate (1 pbw); and a predetermined amount of ion-exchange water. The obtained mixture was stirred for an hour. The ion-exchange water was removed from the mixture by using an evaporating device for drying. SiO particles with nickel(II) nitrate carried on its surface were thus obtained. As a result of analysis on the obtained SiO particles with a scanning electron microscope (SEM), it was confirmed that the nickel(II) nitrate was particles with a particle size of about 100 nm. The obtained active material particles were placed in a ceramic reaction vessel, and the temperature of the particles was raised to 550degreesC in a helium gas atmosphere. The atmosphere in the reaction vessel was replaced with a mixed gas of hydrogen gas (50 vol.%) and ethylene gas (50 vol.%), and the temperature of the active material particles was kept to 550degreesC for an hour. Carbon nanofibers (CNF) were thus grown on the surface of the SiO particles while the nickel(II) nitrate was being reduced. Then, the mixed gas in the reaction vessel was replaced with a helium gas, and temperature of the SiO particles carrying CNF was cooled to ambient temperature. The obtained composite particles were allowed to stand in an argon gas atmosphere at 700degreesC for an hour to heat-treat CNF. As a result of the SEM analysis on the obtained particles, it was confirmed that carbon nanofibers were attached to the SiO particle surface, and that the carbon nanofibers had a fiber diameter of about 80 nm and a length of 100 microns. The amount of CNF was 25 pbw per 100 parts by weight of silicon monoxide. The following were sufficiently mixed to obtain a slurry of a negative electrode material mixture: SiO particles (100 pbw) to which carbon nanofibers were attached to its surface; an emulsion solution of styrene-butadiene rubber as a binder; carboxymethyl cellulose (3 pbw) as a thickener; and an appropriate amount of ion-exchange water. The emulsion solution of styrene-butadiene rubber was added so that the amount of the styrene-butadiene rubber in the obtained negative electrode material mixture becomes 10 pbw. The obtained negative electrode material mixture was applied to both sides of a copper foil with a thickness of 15 microns, dried, and rolled, to obtain a negative electrode plate. The positive electrode plate and the negative electrode plate obtained as in the above were cut to give a length required. Then to an exposed portion of a positive electrode current collector provided at an end portion of the positive electrode plate, an aluminum-made positive electrode lead was welded. Similarly, to an exposed portion of a negative electrode current collector provided at an end portion of the negative electrode plate, a nickel-made negative electrode lead was welded. A separator was disposed between the positive electrode plate and the negative electrode plate, and the obtained stack was spirally wound around to obtain an electrode assembly. For the separator, Hipore (RTM: a porous polyethylene film) with a thickness of 20 microns was used. Then, a polypropylene-made insulating plate was disposed on top and bottom of the thus made electrode assembly, and the electrode assembly was inserted into a nickel-plated, cylindrical iron battery case. The battery case had a diameter of 18 mm and a height of 56 mm. The positive electrode lead was connected to an aluminum sealing plate having a polypropylene-made gasket, and the negative electrode lead was connected to the inner bottom face of the battery case. To the battery case storing the electrode assembly, 5 cm3 of the above non-aqueous electrolyte was injected. The battery case was decompressed, to immerse the electrode assembly with the non-aqueous electrolyte. At this time, the time it took for the electrode assembly to be permeated by the non-aqueous electrolyte was determined. The results were as follows: the battery had a capacity retention rate of 85%; injection time of 6 minutes and rate performance of 78%. Then, using the aluminum sealing plate having the polypropylene gasket, the opening end of the battery case was crimped to the end of the sealing plate with the gasket interposed between them, to seal the battery case. A cylindrical battery 1 with a designed capacity of 2400 mAh was thus made.