Separator for non-aqueous secondary battery and non-aqueous secondary battery
A separator for a non-aqueous secondary battery contains: a porous layer that is provided on only one side of the porous substrate, and that contains a resin having at least one bonding group selected from an amide bond, an imide bond, and a sulfonyl bond, in which, in the porous substrate, an absolute value of a difference between a temperature of an endothermic peak observed at 120° C. to 145° C., in a temperature raising process 1, and a temperature of an endothermic peak observed at 120° C. to 145° C., in a temperature raising process 2, is 1.50° C. or higher in DSC measurement when the temperature raising process 1 of continuously raising the temperature from 30° C. to 200° C. at a temperature change rate of 5° C./min in a nitrogen atmosphere, and the temperature raising process 2 of lowering the temperature from 200° C. to 30° C. and raising the temperature from 30° C. to 200° C., are performed.
1 . A separator for a non-aqueous secondary battery, the separator comprising:
a porous substrate including a polyethylene microporous film; and
a porous layer that is provided on only one side of the porous substrate, and that contains a resin having at least one bonding group selected from the group consisting of an amide bond, an imide bond, and a sulfonyl bond,
wherein, the porous substrate has a crystalline structure, and in the porous substrate, an absolute value of a difference between a temperature of an endothermic peak observed at from 120° C. to 145° C., in a temperature raising process 1, and a temperature of an endothermic peak observed at from 120° C. to 145° C., in a temperature raising process 2, is from 1.50° C. to 5° C., in differential scanning calorimetry (DSC) measurement,
wherein the DSC measurements are performed continuously by raising the temperature from 30° C. to 200° C. at a temperature change rate of 5° C./min in a nitrogen atmosphere as the temperature raising process 1, lowering the temperature from 200° C. to 30° C. and raising the temperature from 30° C. to 200° C., as the temperature raising process 2, without providing a pause time between the temperature raising process 1 and the lowering, and between the lowering and the temperature raising process 2, and
wherein a Macmillan number Mn determined by the following formula is 10 or less:
Mn=(σe)/(σs)
σs=t/Rm
wherein σe represents a conductivity (S/m) of an electrolytic solution at 20° C. obtained by dissolving 1 mol/l of LiPF 6 in a mixed solvent composed of ethylene carbonate and propylene carbonate in a mass ratio of 1:1, σS represents a conductivity (S/m) of the separator impregnated with the electrolytic solution at 20° C., t represents a film thickness (m), and Rm represents a film resistance (ohm-cm 2 ) of the separator.
2 . The separator for a non-aqueous secondary battery according to claim 1 , wherein the porous layer contains inorganic particles.
3 . The separator for a non-aqueous secondary battery according to claim 1 , wherein the resin contains a wholly aromatic polyamide.
4 . The separator for a non-aqueous secondary battery according to claim 1 , wherein the porous layer has a thickness of from 0.3 μm to 5.0 μm.
5 . The separator for a non-aqueous secondary battery according to claim 1 , wherein the resin is provided inside a pore of the porous substrate.
6 . The separator for a non-aqueous secondary battery according to claim 1 , wherein the porous substrate has an average pore size of 20 nm to 100 nm.
7 . The separator for a non-aqueous secondary battery according to claim 1 , wherein the porous substrate has an average pore size of 20 nm to 90 nm.
8 . The separator for a non-aqueous secondary battery according to claim 1 , wherein the porous substrate has an average pore size of 20 nm to 80 nm.
9 . The separator for a non-aqueous secondary battery according to claim 1 , wherein the porous layer has an average pore size of 10 nm to 300 nm.
10 . A non-aqueous secondary battery that obtains electromotive force by lithium doping and dedoping, the non-aqueous secondary battery comprising:
a positive electrode;
a negative electrode;
the separator for a non-aqueous secondary battery according to claim 1 disposed between the positive electrode and the negative electrode; and
an electrolytic solution in which a lithium salt is dissolved in a solvent containing a cyclic carbonate in an amount of 90% by mass or more based on a total mass of the solvent.