Nonaqueous electrolyte secondary battery separator, nonaqueous electrolyte secondary battery laminated separator, nonaqueous electrolyte secondary battery member, and nonaqueous electrolyte secondary battery

1. A nonaqueous electrolyte secondary battery separator which is a porous film containing a polyolefin as a main component,

said nonaqueous electrolyte secondary battery separator (i) having a phase difference of 80 nm or less with respect to light having a wavelength of 590 nm in a state where said nonaqueous electrolyte secondary battery separator is impregnated with ethanol and (ii) having a porosity of 30% to 60%.

2. A nonaqueous electrolyte secondary battery laminated separator comprising:

a nonaqueous electrolyte secondary battery separator recited in claim 1 ; and

a porous layer.

3. A nonaqueous electrolyte secondary battery member comprising:

a cathode;

a nonaqueous electrolyte secondary battery separator recited in claim 1 ; and

an anode,

the cathode, the nonaqueous electrolyte secondary battery separator, and the anode being arranged in this order.

4. A nonaqueous electrolyte secondary battery member comprising:

a cathode;

a nonaqueous electrolyte secondary battery laminated separator recited in claim 2 ; and

an anode,

the cathode, the nonaqueous electrolyte secondary battery laminated separator, and the anode being arranged in this order.

5. A nonaqueous electrolyte secondary battery comprising a nonaqueous electrolyte secondary battery separator recited in claim 1 .

6. A nonaqueous electrolyte secondary battery comprising a nonaqueous electrolyte secondary battery laminated separator recited in claim 2 .