TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The coating comprises vanadium compound chosen from vanadium(II) chloride, vanadium(III) chloride, vanadium tetrachloride, vanadium(II) bromide, vanadium(III) bromide, vanadium tetrabromide, vanadium(II) iodide, and vanadium (III) iodide. The compound particles are included in electrolyte, electrode, and/or separation film of the battery. The compound particles are mixed with the electrode active material. The compound particles are included in the coating layer formed on the surface of the electrode.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The polymerization initiator is photoinitiator, thermal initiator, redox-reaction initiator and/or radiation initiator. The photoinitiator is chosen from ( alpha )-hydroxyketone compound, phenylglyoxylate-type compound, benzyldimethylketal compound, ( alpha )-aminoketone compound, monoacylphosphine compound, phosphine oxide compound, metallocene-group-containing compound, and iodonium salt. The thermal initiator is chosen from azo-based compound, peroxy-type compound, tert-butyl peracetate, peracetic acid, and potassium persulfate. The redox-reaction initiator is persulfate compound or hydroperoxide. The core further comprises foaming agent chosen from azodicarbonamide, azobisisobutyronitrile, N,N'-dimethyl-N,N'-dinitroso-terephthalate, 4,4'-oxybis(benzenesulfonylhydrazide), 3,3'-sulfo bis(benzene-sulfonylhydrazide), 1,1-azobisformamide-azodicarbonamide, p-toluenesulfonyl semicarbazide, and barium azodicarboxylate.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The compound particles comprise monomer chosen from ethylene oxide, acrylic acid, acrylonitrile, methacrylic acid, fluorovinylidene, methyl methacrylate, fluoride, siloxane, phosphazene, imide, sulfide, acetate and succinate, and its copolymer. The coating comprises thermoplastic resin. The thermoplastic resin is chosen from polyethylene, polyvinyl chloride, polypropylene, polystyrene, polyacrylonitrile, styrene-acrylonitrile, acrylonitrile-butadiene-styrene, polymethyl-methacrylate, polytetrafluoroethylene and polychlorotrifluoroethylene. Preferred Properties: The coating has thickness of 2-5 mu m.