Separator for non-aqueous batteries, non-aqueous battery using same, and production method for separator for non-aqueous batteries

A method for producing a separator for non-aqueous batteries, comprising either:

• (i) forming a heat-resistant polymer fiber layer comprising a fiber aggregate of nanofibers and non-nanofibers by preparing both the nanofibers having a diameter of 1,000 nm or smaller and the non-nanofibers having a diameter of exceeding 1,000 nm from a heat-resistant polymer comprising a high melting-point polymer having a melting point exceeding 200° C., a heat-infusible polymer or both,
• forming a low melting-point polymer fiber layer by preparing nanofibers having a fiber diameter of 1,000 nm or smaller from a low melting-point polymer having a melting point of 100 to 200° C., and
• laminating the low melting-point polymer fiber layer and the heat-resistant polymer fiber layer to give a laminate;
• or
• (ii) forming a heat-resistant polymer fiber layer comprising fiber aggregate of nanofibers and non-nanofibers by preparing both the nanofibers having a diameter of 1,000 nm or smaller and the non-nanofibers having a diameter of exceeding 1,000 nm from a heat-resistant polymer comprising a high melting-point polymer having a melting point exceeding 200° C., a heat-infusible polymer, or both,
• preparing a spinning liquid either by solving a low melting-point polymer having a melting point of 100 to 200° C. in a solvent dissolvable of the low melting-point polymer, or by melting a low melting-point polymer, and
• electro-spinning the spinning liquid to form nanofibers on the heat-resistant polymer fiber layer to be laminated,
• wherein
• the separator comprises:
• a low melting-point polymer fiber layer (A) comprising a low melting-point polymer having a melting point of 100 to 200° C., the low melting-point polymer fiber layer (A) comprising nanofibers having a fiber diameter of 1000 nm or smaller and formed from the low melting-point polymer;
• and
• a heat-resistant polymer fiber layer (B) positioned on the low melting-point polymer fiber layer (A) and comprising a heat-resistant polymer selected from the group consisting of a high melting-point polymer having a melting point over 200° C. and a heat infusible polymer, the heat-resistant polymer fiber layer (B) comprising a mixture of nanofibers having a fiber diameter of 1000 nm or smaller and non-nanofibers having a fiber diameter over 1000 nm and both formed from the heat-resistant polymer.