SEPARATOR FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY, NONAQUEOUS ELECTROLYTE SECONDARY BATTERY USING SAME, AND PROCESSES FOR PRODUCING SAME

摘要

Hot pressing is essential to the production of a conventional laminate-type separator. However, nanofibers in the laminate-type separator melt during the hot pressing to close up pores among the nanofibers. Therefore, the laminate-type separator has a problem that a lithium ion battery using the separator exhibits a high impedance in a stage where the shutdown function of the separator does not operate yet. A separator (10) for a nonaqueous electrolyte secondary battery is characterized by bearing composite nanofibers (12C), namely, nano-sized fibers which each comprise two or more aqueous resins having different melting points respectively.