| 摘要 |
PURPOSE:To maintain the electric potential of the positive electrode exceptionally high even when the concentration of halogen decreases and remarkably improve the charge-and-discharge energy efficiency of a metal-halogen secondary battery by applying a specific paper-like porous carbon fiber member to the positive electrode. CONSTITUTION:A positive electrode is prepared by affixing over the surface of an electrode base material a paper-like member having a fiber density of over 0.1g/cc and consisting of porous or active carbon fiber having over 0.1cc/g volume of fine holes with 30-10,000Angstrom diameter. If the micropores of the paper-like member principally comprise those with smaller than 30Angstrom diameters, the diffusion coefficient of a halogen into the fine holes decreases inhibing the effective action of the halogen on electrode reaction. If the micropores of the paper-like member principally comprise those with larger than 1,000Angstrom diameters, it is not preferable since the surface area of the entier porous carbon fiber becomes too small. If the volume of the fine holes is smaller than 0.1cc/g, the surface area per unit volume of the porous carbon fiber further decreases inhibing good effect to be obtained. In addition, if the fiber density of the paper-like member is smaller than 0.1g/cc, it is not preferable since contact between fibers decreases and the electric resistance increases resulting in increase in the internal resistance of a battery and reduction in its voltage efficiency. |
