Nonaqueous electrolyte secondary battery insulating porous layer
An insulating porous layer for a nonaqueous electrolyte secondary battery having excellent separator resistance is provided. The porous layer contains an inorganic filler and a resin, a central particle diameter of the inorganic filler is in a range of 0.1 μm to 11 μm, a BET specific surface area per unit area of the inorganic filler is not greater than 100 m 2 /g, and the value of formula (1) is in a range of 0.10 to 0.40: [1−T/M] (1) In formula (1), T and M respectively represent a distance by which the insulating porous layer moves in a traverse direction or a machine direction from a starting point of measurement to a point where a critical load is obtained in a scratch test under a constant load of 0.1 N.
1. A nonaqueous electrolyte secondary battery insulating porous layer comprising an inorganic filler and a resin, wherein:
a central particle diameter of the inorganic filler is in a range of 0.1 μm to 11 μm;
a BET specific surface area of the inorganic filler is not greater than 100 m 2 /g;
a weight per unit area of the inorganic filler and the resin is 0.5 g/m 2 to 20 g/m 2 ; and
a value expressed by the following formula (1) is in a range of 0.10 to 0.40, the value being an index indicative of the orientation of the inorganic filler:
|1−T/M| (1),
wherein T and M are obtained in a scratch test comprising moving a test sample of the nonaqueous electrolyte secondary battery insulating porous layer a distance of 10 mm in a transverse direction of the porous layer at a speed of 5 mm/min while applying a vertical load of 0.1 N to the test sample, and then moving the test sample of the nonaqueous electrolyte secondary battery insulating porous layer a distance of 10 mm in a machine direction of the porous layer at a speed of 5 mm/min while applying a vertical load of 0.1 N, where where T represents a distance by which the porous layer moves in the transverse direction from a starting point of measurement to a point where a critical load is obtained in the scratch test until a constant load of 0.1 N and M represents a distance by which the porous layer moves in the machine direction from a starting point of measurement to a point where a critical load is obtained in the scratch test under the constant load of 0.1 N,
wherein the nonaqueous electrolyte secondary battery insulating porous layer is formed by applying a coating solution containing the inorganic filler and the resin along a single direction to form the porous layer,
wherein the transverse direction is the single direction and the machine direction is a direction perpendicular to the transverse direction.
2. The nonaqueous electrolyte secondary battery insulating porous
layer according to claim 1 , wherein:
a value expressed by the following formula (2) is in a range of 0.10 to 0.40, the value being an index indicative of the orientation of the inorganic filler:
1−T/M (2).
3. The nonaqueous electrolyte secondary battery insulating porous layer according to claim 1 , wherein:
the inorganic filler contains alumina and a plate-shaped filler.
4. A nonaqueous electrolyte secondary battery laminated separator comprising:
a porous base material containing a polyolefin as a main component; and
a nonaqueous electrolyte secondary battery insulating porous layer recited in claim 1 , the nonaqueous electrolyte secondary battery insulating porous layer being provided on one surface or both surfaces of the porous base material.
5. A nonaqueous electrolyte secondary battery member comprising:
a positive electrode;
a nonaqueous electrolyte secondary battery laminated separator recited in claim 4 ; and
a negative electrode,
the positive electrode, the nonaqueous electrolyte secondary battery laminated separator, and the negative electrode being provided in this order.
6. A nonaqueous electrolyte secondary battery comprising:
a positive electrode,
an electrolyte,
the nonaqueous electrolyte secondary battery laminated separator recited in claim 4 , and
a negative electrode.
7. A nonaqueous electrolyte secondary battery member comprising:
a positive electrode;
a nonaqueous electrolyte secondary battery insulating porous layer recited in claim 1 ; and
a negative electrode,
the positive electrode, the nonaqueous electrolyte secondary battery insulating porous layer, and the negative electrode being provided in this order.
8. A nonaqueous electrolyte secondary battery comprising:
a positive electrode,
an electrolyte,
the nonaqueous electrolyte secondary battery insulating porous layer recited in claim 1 , and
a negative electrode.
9. The nonaqueous electrolyte secondary battery insulating porous layer according to claim 1 , wherein:
the resin is at least one resin selected from the group consisting of aromatic polyamides and wholly aromatic polyamides.