TECHNOLOGY FOCUS - METALLURGY - Preferred Method: The metal microparticles are supported on carbon fiber by reduction method of metal ion, preferably electroplating. Preferred Microparticles: The metal microparticles comprise, for occlusion-discharge of lithium, tin, silicon, lead, aluminum, gold, platinum, indium, zinc, cadmium, silver and/or magnesium. Preferred Property: The space of three-dimensional continuous-form carbon fiber filled with metal microparticles is 50 vol.% or less.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compounds: The compound having aromatic ring is chosen from aniline, pyrrole, thiophene, and their derivatives.    TECHNOLOGY FOCUS - POLYMERS - Preferred Method: The three-dimensional continuous-form carbon fiber contains fibril-like polymer obtained by oxidize-polymerizing a compound having an aromatic ring, and baking in a non-oxidizing atmosphere. The oxidation polymerization is electrolytic oxidizing polymerization. Preferred Composition: The polymer electrolyte contains polymer and a supporting electrolyte, and further contains an aprotic organic solvent. EXAMPLE - Copper working electrodes were installed in aqueous acid containing aniline monomer and hydrogen tetrafluoroborate. A platinum board was used as counter electrode and electrolytic polymerization was carried out for 10 minutes at room temperature, to obtain polyaniline. The polyaniline was washed with ion-exchange water and vacuum-dried for 24 hours, to obtain fibril-like polyaniline. The polyaniline was heated to 950degreesC for 1 hour and baked, to obtain three-dimensional continuous-form carbon fiber having fibril diameter of 40-100 nm and surface resistance of 1 Omega. The three-dimensional continuous-form carbon fiber was immersed in acidic solution containing tin ions dissolved in sulfuric acid and was electroplated to obtain tin-supporting carbon fiber. The tin-supporting carbon fiber was water-washed and dried. About 20 vol.% of space of carbon fiber was filled with tin fine particles. An organic solvent mixture of ethyl acetate and ethanol (50/50 mass%) was added and mixed with tin-supporting carbon fiber. The kneaded mixture was coated on a 25 microns thick copper foil (collector), and dried at 100-120degreesC to obtain a cathode of thickness 60 microns. Acetylene black (in mass parts) (3) and polyvinylidene fluoride (3) were added to lithium cobaltate (94), and kneaded with organic solvent mixture of ethyl acetate and ethanol (50/50 mass%). The kneaded material was coated to 25 microns thick aluminum foil (collector), and dried at 100-120degreesc to obtain an anode sheet having a thickness of 80 microns. Polyethylene oxide (in g) (50) having weight average molecular weight of 5-6 million, lithium hexafluoro phosphate (3.7), and acetonitrile (10 mL) were mixed uniformly at 80degreesC, to obtain polyethylene-oxide sol. The obtained sol was applied on both surfaces of a polyethylene separator. Then, acetonitrile was evaporated to obtain a dry gel. The dry gel was impregnated in a mixed solvent of ethylene carbonate and ethyl methyl carbonate. The anode and cathode were opposed through the dry gel, to obtain a polymer battery. The obtained polymer battery had excellent cycle characteristics.