Nonaqueous electrolyte secondary battery separator
As a nonaqueous electrolyte secondary battery separator used to produce a nonaqueous electrolyte secondary battery which is low in resistance increasing rate in a case where the nonaqueous electrolyte secondary battery is repeatedly subjected to a charge-discharge cycle, the present invention provides a nonaqueous electrolyte secondary battery separator which includes a polyolefin porous film, the nonaqueous electrolyte secondary battery separator having ion permeability barrier energy of not less than 300 J/mol/μm and not more than 900 J/mol/μm.
1. A nonaqueous electrolyte secondary battery separator comprising a polyolefin porous film,
the nonaqueous electrolyte secondary battery separator having ion permeability barrier energy of not less than 300 J/mol/μm and not more than 900 J/mol/μm per unit film thickness,
wherein the nonaqueous electrolyte secondary battery separator causes an electrode resistance increasing rate after 100 charge-discharge cycles of a nonaqueous electrolyte secondary battery containing the nonaqueous electrolyte secondary battery separator to be lower than an electrode resistance increasing rate after 100 charge-discharge cycles of a nonaqueous electrolyte secondary battery containing a reference nonaqueous electrolyte secondary battery separator comprising a polyolefin porous film and having an ion permeability battery energy of less than 300 J/mol/μm or more than 900 J/mol/μm per unit film thickness,
wherein the electrode resistance increasing rate after 100 charge-discharge cycles is measured by subjecting the nonaqueous electrolyte secondary battery to 100 charge-discharge cycles each performed at 55° C. at a voltage ranging from 2.7 V to 4.2 V with CC-CV charge at a charge current value of 1 C, terminal current condition 0.02 C and with CC discharge at a discharge current value of 10 C,
wherein CC-CV is a charging method comprising charging the battery at a constant electric current to a certain voltage and maintaining the certain voltage while the electric current is reduced; and
wherein CC discharge is a discharging method comprising discharging the battery at a constant electric current until the certain voltage is reached.
2. The nonaqueous electrolyte secondary battery separator recited in claim 1 , further comprising an insulating porous layer which is provided on one or both surfaces of the polyolefin porous film.
3. A nonaqueous electrolyte secondary battery member comprising:
a positive electrode;
a nonaqueous electrolyte secondary battery separator recited in claim 1 ; and
a negative electrode,
the positive electrode, the nonaqueous electrolyte secondary battery separator, and the negative electrode being disposed in this order.
4. A nonaqueous electrolyte secondary battery comprising a nonaqueous electrolyte secondary battery separator recited in claim 1 .
5. A nonaqueous electrolyte secondary battery member comprising:
a positive electrode;
a nonaqueous electrolyte secondary battery separator recited in claim 2 ; and
a negative electrode,
the positive electrode, the nonaqueous electrolyte secondary battery separator, and the negative electrode being disposed in this order.
6. A nonaqueous electrolyte secondary battery comprising a nonaqueous electrolyte secondary battery separator recited in claim 2 .
7. The nonaqueous electrolyte secondary battery separator recited in claim 2 , wherein the insulating porous layer contains a polyamide-based resin.
8. The nonaqueous electrolyte secondary battery separator recited in claim 7 , wherein the polyamide-based resin is a wholly aromatic polyamide.