Nonaqueous electrolyte secondary battery
A nonaqueous electrolyte secondary battery ( 10 ) according to one embodiment of the present disclosure is provided with: an electrode body ( 14 ) which is obtained by winding a positive electrode ( 30 ) and a negative electrode ( 40 ), with a separator ( 50 ) being interposed therebetween; a nonaqueous electrolyte; and a battery case ( 15 ) which is formed of a metal and contains the electrode body ( 14 ) and the nonaqueous electrolyte. The negative electrode ( 40 ) comprises a negative electrode collector ( 41 ) and a negative electrode active material layer ( 42 ) that contains graphite particles as a negative electrode active material; the outer circumferential surface of the electrode body ( 14 ) is provided with an exposure part ( 43 ) from which the negative electrode collector ( 41 ) is exposed so as to be in contact with the inner circumferential surface of the battery case ( 15 ); and the graphite particles have a compressive strength of 15 MPa or more.
1 . A non-aqueous electrolyte secondary battery, comprising:
an electrode assembly formed by winding a positive electrode and a negative electrode with a separator being interposed between the positive electrode and the negative electrode;
a non-aqueous electrolyte; and
a metal exterior body that houses the electrode assembly and the non-aqueous electrolyte; wherein
the negative electrode includes a negative electrode current collector being a metal foil, and a negative electrode active material layer including graphite particles as a negative electrode active material,
the negative electrode comprises a peripheral part thereof located at an outer peripheral surface of the electrode assembly,
one surface of the peripheral part of the negative electrode forms an exposed portion in which the negative electrode current collector is exposed and is in direct physical contact with an inner peripheral surface of the exterior body,
another surface opposite the one surface of the peripheral part of the negative electrode forms a non-exposed portion that has the negative electrode active material layer disposed on the negative electrode current collector, wherein the non-exposed portion is directly opposite the exposed portion in a thickness direction of the negative electrode, and
the graphite particles have a compressive strength of 15 MPa or more and 30 MPa or less, wherein the compressive strength of the graphite particles is measured as a compressive force in deformation testing at which a variation of a particle size of a specimen of the graphite particles having an original volume average particle size of 40 μm or more and 60 μm or less, due to load application at a rate of 4.46 mN/sec in a center direction of the graphite particles at room temperature, reaches 10% from the original volume average particle size.
2 . The non-aqueous electrolyte secondary battery according to claim 1 , wherein a ratio S2/S1 of a measured surface area S2 to an apparent surface area S1 of the graphite particles is 10 or less.
3 . The non-aqueous electrolyte secondary battery according to claim 1 , wherein the non-aqueous electrolyte includes a fluorinated cyclic carbonate.
4 . The non-aqueous electrolyte secondary battery according to claim 3 , wherein the fluorinated cyclic carbonate is monofluoroethylene carbonate.
5 . The non-aqueous electrolyte secondary battery according to claim 3 , wherein a content of the fluorinated cyclic carbonate is 1 volume % or more and 30 volume % or less based on a total amount of the non-aqueous electrolyte.
6 . The non-aqueous electrolyte secondary battery according to claim 1 , wherein the compressive strength of the graphite particles is 15 MPa or more and 18 MPa or less.
7 . The non-aqueous electrolyte secondary battery according to claim 1 , wherein a thickness of the negative electrode current collector is 5 μm or more and 40 μm or less.
8 . The non-aqueous electrolyte secondary battery according to claim 1 , wherein a thickness of the negative electrode current collector is 10 μm or more and 20 μm or less.
9 . The non-aqueous electrolyte secondary battery according to claim 1 , wherein the negative electrode current collector is formed of a copper foil.