SEPARATOR FOR SECONDARY BATTERY AND PREPARATION METHOD THEREFOR, SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK, AND POWER CONSUMING DEVICE
Provided are a separator for a secondary battery and a preparation method therefor, and a secondary battery including the separator, a battery module, a battery pack, and a power consuming device. The separator for a secondary battery of the present application includes a substrate layer and a nanofiber layer provided on one surface of the substrate layer. The nanofiber layer includes a lithium supplementing agent, a polymer, and an optional conductive material; and in the total weight of the nanofiber layer, the content of the lithium supplementing agent accounts for 30.0-50.0% by weight, the content of the polymer accounts for 50.0-70.0% by weight, and the content of the conductive material accounts for 0-5.0% by weight.
1 . A separator for a secondary battery, comprising:
a substrate layer; and
a nanofiber layer provided on one surface of the substrate layer,
wherein the nanofiber layer comprises a lithium supplementing agent, a polymer, and a conductive material, in the total weight of the nanofiber layer, the content of the lithium supplementing agent accounts for 30.0-50.0% by weight, the content of the polymer accounts for 50.0-70.0% by weight, and the content of the conductive material accounts for 0-5.0% by weight.
2 . The separator according to claim 1 , wherein the conductive material comprises a zero-dimensional conductive material and an one-dimensional conductive material, and in the total weight of the nanofiber layer, the content of the zero-dimensional conductive material accounts for 1.0-5.0% by weight, and the content of the one-dimensional conductive material accounts for 0-0.3% by weight.
3 . The separator according to claim 2 , wherein the zero-dimensional conductive material has a particle size of 30-50 nm; and the zero-dimensional conductive material is selected from one or more of carbon black, acetylene black and Ketjen black.
4 . The separator according to claim 2 , wherein
the one-dimensional conductive material has a length-diameter ratio of 500-1,000; and
the one-dimensional conductive material is a carbon nanotube, a single-wall nanotube, a multi-wall nanotube, or a combination thereof.
5 . The separator according to claim 1 , wherein the lithium supplementing agent is selected from one or more of Li 2 C 2 O 4 , C 4 BLiO 8 , Li 15 Si 4 , Li 4 Sn, Li 2 NiO 2 , LiF, Li 2 TiO 3 , Li 2 CrO 4 , Li 2 Cr 2 O 7 , Li 4 SiO 4 , Li 2 SiO 3 , Li 3 AsO 4 , Li 2 SeO 4 , Li 2 SeO 3 , LiVO 3 , LiAlO 2 , Li 3 PO 4 , Li 2 B 8 O 13 , Li 2 B 4 O 7 , LiBO 2 , Li 3 AlF 6 , Li 2 SnF 6 and LiAsF 6 , and one or more of Li 2 NiO 2 , Li 4 Sn and LiAsF 6 .
6 . The separator according to claim 1 , wherein the lithium supplementing agent has a particle size of 50-200 nm.
7 . The separator according to claim 1 , wherein in 100 parts by weight of the polymer, the content of the lithium supplementing agent accounts for 40-100 parts by weight.
8 . The separator according to claim 2 , wherein in 100 parts by weight of the lithium supplementing agent, the content of the zero-dimensional conductive material accounts for 1-12.5 parts by weight; and the content of the one-dimensional conductive material accounts for 0.15-0.75 parts by weight.
9 . The separator according to claim 1 , wherein the polymer is selected from one or more of polyvinylidene chloride, polyimide, polyacrylonitrile, and polystyrene.
10 . The separator according to claim 1 , wherein the nanofibers in the nanofiber layer have a diameter of 100-500 nm.
11 . The separator according to claim 1 , wherein the nanofiber layer has a thickness of 1.0-5.0 μm.
12 . The separator according to claim 1 , wherein the nanofiber layer has a porosity of 80% or above.
13 . A method for preparing a separator for a secondary battery, comprising:
dissolving a polymer in a solvent to obtain a polymer solution;
adding the polymer solution to a lithium supplementing agent or a blend of a lithium supplementing agent and a conductive material, and performing high-speed dispersion to obtain a dispersion liquid; and
attaching the dispersion liquid to one surface of a substrate layer by means of electrostatic spinning to form a nanofiber layer;
wherein in the total weight of the nanofiber layer, the content of the lithium supplementing agent accounts for 30.0-50.0% by weight, the content of the polymer accounts for 50.0-70.0% by weight, and the content of the conductive material accounts for 0-5% by weight.
14 . The method according to claim 13 , wherein a solid content of the polymer solution accounts for 20-40% by weight.
15 . The method according to claim 13 , wherein the nanofiber layer has a thickness of 1.0-5.0 μm.
16 . A secondary battery, comprising:
a positive electrode;
a negative electrode;
an electrolyte; and
the separator according to claim 1 ,
wherein the nanofiber layer is provided on the surface of the substrate layer facing the positive electrode.
17 . A battery module, comprising the secondary battery according to claim 16 .
18 . A battery pack, comprising the battery module according to claim 17 .
19 . A power consuming device, comprising the battery pack according to claim 18 .