Separator, secondary battery containing such separator, and related battery module, battery pack, and apparatus

1. A separator, comprising:

a substrate; and

a coating layer provided on at least one surface of the substrate; wherein

the coating layer comprises organic particles and inorganic particles, the organic particles comprise first-type organic particles and second-type organic particles, the inorganic particles form an inorganic particle layer on the at least one surface of the substrate, and the first-type organic particles are partially embedded into the inorganic particle layer and form bulges on a surface of the inorganic particle layer;

a mass ratio of the first-type organic particles to the second-type organic particles is greater than 1:1;

a number-based median particle size of the first-type organic particles is 12 μm-25 μm;

an average height of the bulges above the surface of the inorganic particle layer is 10 μm-29 μm;

a thickness of the inorganic particle layer is 0.5 μm-4 μm; and

a ratio of an average height of the bulges to a thickness of the inorganic particle layer is 4-20.

2. The separator according to claim 1 , wherein the first-type organic particles are secondary particles, the secondary particles have an average particle size of 150 nm to 300 nm.

3. The separator according to claim 1 , wherein the first-type organic particles comprise one or more of a homopolymer or copolymer of a fluorinated alkenyl monomer unit, a homopolymer or copolymer of an alkylene monomer unit, a homopolymer or copolymer of an unsaturated nitrile monomer unit, a homopolymer or copolymer of an alkylene oxide monomer unit, and modified compounds of the foregoing homopolymers or copolymers; and

the first-type organic particles comprise one or more of polytetrafluoroethylene, polytrifluorochloroethylene, polyfluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide, a copolymer of different fluorinated alkenyl monomer units, a copolymer of the fluorinated alkenyl monomer unit and the alkylene monomer unit, a copolymer of the fluorinated alkenyl monomer unit and an acrylic acid monomer unit, a copolymer of the fluorinated alkenyl monomer unit and an acrylic monomer unit, and modified compounds of the foregoing homopolymers or copolymers.

4. The separator according to claim 1 , wherein the first-type organic particles comprise one or more of a vinylidene fluoride-trifluoroethylene copolymer, a vinylidene fluoride-hexafluoropropylene copolymer, a vinylidene fluoride-trifluoroethylene-hexafluoropropylene copolymer, a vinylidene fluoride-hexafluoropropylene-acrylic acid copolymer, a vinylidene fluoride-hexafluoropropylene-acrylate copolymer, and modified compounds of the foregoing copolymers.

5. The separator according to claim 1 , wherein the separator satisfies at least one of the following (1) and (2):

(1) a mass ratio of the first-type organic particles to the coating layer is ≥12%; and

(2) a mass ratio of the inorganic particles to the coating layer is ≤85%.

6. The separator according to claim 1 , wherein a median volume-based particle size D v 50 of the inorganic particles is 0.5 μm-2.5 μm.

7. The separator according to claim 1 , wherein the inorganic particles comprise one or more of boehmite (γ-AlOOH), aluminum oxide (Al 2 O 3 ), barium sulfate (BaSO 4 ), magnesium oxide (MgO), magnesium hydroxide (Mg(OH) 2 ), silicon dioxide (SiO 2 ), tin oxide (SnO 2 ), titanium oxide (TiO 2 ), calcium oxide (CaO), zinc oxide (ZnO), zirconium oxide (ZrO 2 ), yttrium oxide (Y 2 O 3 ), nickel oxide (NiO), cerium dioxide (CeO 2 ), zirconium titanate (SrTiO 3 ), barium titanate (BaTiO 3 ), and magnesium fluoride (MgF 2 ).

8. The separator according to claim 1 , wherein the separator satisfies one or more of the following (1) to (5):

(1) an air permeability of the separator is 100s/100 mL-300s/100 mL;

(2) a tensile strength in transverse direction (MD) of the separator is 1500 kgf/cm 2 -3000 kgf/cm 2− ;

(3) a tensile strength in machine direction (TD) of the separator is 1000 kgf/cm 2 -2500 kgf/cm 2− ;

(4) a transverse elongation at break of the separator is 50%-200%; and

(5) a longitudinal elongation at break of the separator is 50%-200%.

9. The separator according to claim 1 , wherein the inorganic particles and the organic particles form an uneven pore structure on the coating layer.

10. The separator according to claim 1 , wherein: a distance between any two adjacent inorganic particles is recorded as L1, a distance between any one inorganic particle and any one organic particle that are adjacent is recorded as L2, and then L1<L2.

11. The separator according to claim 1 , wherein a mass ratio of the first-type organic particles to the coating layer is 15%-25%.

12. A secondary battery, comprising a separator according to claim 1 .

13. A separator, comprising:

a substrate; and

a coating layer provided on at least one surface of the substrate; wherein

the coating layer comprises organic particles and inorganic particles, the organic particles comprise first-type organic particles and second-type organic particles, the inorganic particles form an inorganic particle layer on the at least one surface of the substrate, and the first-type organic particles are partially embedded into the inorganic particle layer and form bulges on a surface of the inorganic particle layer, and the first-type organic particles are secondary particles;

a number-based median particle size of the first-type organic particles is ≥12 μm;

a ratio of an average height of the bulges formed by the first-type organic particles to a thickness of the inorganic particle layer is ≥4;

the second-type organic particles are partially embedded into the inorganic particle layer and form bulges on a surface of the inorganic particle layer, a number-based median particle size of the second-type organic particles is larger than a median volume-based particle size Dv50 of the inorganic particles, and the second-type organic particles are primary particles different from the secondary particles of the first-type organic particles;

a number-based median particle size of the second-type organic particles is 2 μm-10 μm;

a mass ratio of the second-type organic particles to the coating layer is less than 10%, and a mass ratio of the first-type organic particles to the second-type organic particles is greater than 1:1.

14. The separator according to claim 13 , wherein: the second-type organic particles comprise one or more of a homopolymer or copolymer of the acrylic monomer unit, a homopolymer or copolymer of the acrylic acid monomer unit, a homopolymer or copolymer of a styrene monomer unit, a polyurethane compound, a rubber compound, and modified compounds of the foregoing homopolymers or copolymers; and

the second-type organic particles comprise one or more of a copolymer of an acrylic monomer unit and a styrene monomer unit, a copolymer of an acrylic acid monomer unit and the styrene monomer unit, a copolymer of the acrylic acid monomer unit, the acrylic monomer unit, and the styrene monomer unit, a copolymer of the styrene monomer unit and an unsaturated nitrile monomer unit, a copolymer of the styrene monomer unit, an alkylene monomer unit, and the unsaturated nitrile monomer unit, and modified compounds of the foregoing copolymers.

15. The separator according to claim 13 , wherein the second-type organic particles comprise one or more of a butyl acrylate-styrene copolymer, a butyl methacrylate-isooctyl methacrylate copolymer, an isooctyl methacrylate-styrene copolymer, a methacrylate-methacrylic acid-styrene copolymer, a methyl acrylate-isooctyl methacrylate-styrene copolymer, a butyl acrylate-isooctyl acrylate-styrene copolymer, a butyl acrylate-isooctyl methacrylate-styrene copolymer, a butyl methacrylate-isooctyl methacrylate-styrene copolymer, a butyl methacrylate-isooctyl acrylate-styrene copolymer, a styrene-acrylonitrile copolymer, a styrene-butadiene-acrylonitrile copolymer, a methyl acrylate-styrene-acrylonitrile copolymer, an isooctyl methacrylate-styrene-acrylonitrile copolymer, a styrene-vinyl acetate copolymer, a styrene-vinyl acetate-pyrrolidone copolymer, and modified compounds of the foregoing copolymers.

16. The separator according to claim 13 , wherein the number-based median particle size of the second-type organic particles is 2.5 μm-6 μm.

17. The separator according to claim 13 , wherein a mass ratio of the first-type organic particles to the coating layer is 15%-25%.