Manufacturing method of a separator for a lithium secondary battery and an organic electrolyte lithium secondary battery using the same separator

This invention relates to an organic electrolyte lithium secondary battery wherein lithium works as an active material, and comprises a negative electrode made of metallic lithium or lithium alloy, and relates more particular to a separator of the same battery. A conventional battery uses a separator made of poly ethylene and/or poly propylene, however, this invention uses microporous polyolefin membrane as a separator matrix whose pores are filled and closed with ionic conductive gel electrolyte. The separator uses a sheet whose at least one face contacting the negative electrode has a gel electrolyte layer on it. The gel electrolyte is formed by irradiating ultraviolet ray to a mixed solution wherein a mixture of which major components are oligomer and monomer polymertized by ultra violet ray is added to organic electrolyte. By using the separator according to this invention in an organic electrolyte lithium secondary battery, internal shortcircuits due to dendrited lithium growing on a negative electrode during a charge can be prevented, and a longer cycle life is expected. Further, burning accidents can be reduced. A highly reliable lithium secondary battery can be thus achieved. Note: The expression "dendrited lithium" means that metal lithium deposited on a negative electrode grows in a form of (or in a shape of ) dendrite.