To inexpensively manufacture a separator having the high conductivity of electrolyte ions, high heat resistance against high temperature, and effectively actuating a shutdown function at high temperature.
This separator is manufactured through a process for forming a film type mix body using a mix made of a thermoplastic high polymer material dissolved in a good solvent, a precipitation process for precipitating the high polymer material contained in the mix body via the exposure of the mix body to the poor solvent of the high polymer material, and a drying process for drying the mix body and making the mix body as porous. In the precipitation process, the good solvent and the poor solvent are quickly substituted for each other on the surface of the mix body and the high polymer material performs polymer coagulation to precipitate minutely. In the subsequent drying process, the solvent in the mix body evaporates and a sponge type center part and a surface part densely having holes of smaller diameter than the center part are formed.
UEJIMA HIROSHI
AMANO TADAYOSHI
