Separator, battery cell, battery, and electric device

Patent metadata

Field	Value
Publication number	US-2025372817-A1
Application number	US-202519297579-A
Country	US
Kind code	A1
Filing date	Aug 12, 2025
Priority date	Sep 28, 2023
Publication date	Dec 4, 2025
Grant date	—

Abstract

A separator, a battery cell, a battery, and an electric device are described. The separator comprises a porous base material and a ferroelectric coating located on at least one surface of the porous base material. The ferroelectric coating comprises a ferroelectric material. The ferroelectric material comprises an inorganic ferroelectric and a ferroelectric polymer. The ferroelectric polymer comprises polyvinylidene fluoride and a copolymer thereof, the ferroelectric polymer comprises β-phase polyvinylidene fluoride, and the content of the β-phase polyvinylidene fluoride in the ferroelectric polymer is greater than or equal to 60%. The separator can slow the continuous growth of dendrites in a direction perpendicular to an electrode sheet, reduce internal short circuits of the battery and improve the reliability of the battery, and can further improve the coulombic efficiency and rate performance of the battery.

First claim

What is claimed is:

1 . A separator, comprising a porous substrate and a ferroelectric coating located on at least one surface of the porous substrate, wherein
the ferroelectric coating comprises a ferroelectric material, and the ferroelectric material comprises an inorganic ferroelectric and a ferroelectric polymer, wherein the ferroelectric polymer comprises polyvinylidene fluoride and a copolymer thereof, the ferroelectric polymer comprises β-phase polyvinylidene fluoride, and a content of the β-phase polyvinylidene fluoride in the ferroelectric polymer is greater than or equal to 60%.

2 . The separator according to claim 1 , wherein the content of the β-phase polyvinylidene fluoride in the ferroelectric polymer is greater than or equal to 80%, optionally greater than or equal to 90%.

3 . The separator according to claim 1 , wherein
a dielectric constant ε r of the ferroelectric coating is greater than a dielectric constant ε r of the inorganic ferroelectric, and optionally, a ratio of the dielectric constant ε r of the ferroelectric coating to the dielectric constant ε r of the inorganic ferroelectric is greater than or equal to 1.6, more optionally greater than or equal to 2.0; the dielectric constant ε r of the inorganic ferroelectric is greater than a dielectric constant ε r of the ferroelectric polymer.

4 . The separator according to claim 1 , wherein
the dielectric constant ε r of the inorganic ferroelectric is 200-8000, optionally 2000-6000; and/or the dielectric constant ε r of the ferroelectric polymer is 5-100, optionally 8-70.

5 . The separator according to claim 1 , wherein at least a part of the ferroelectric polymer is located on at least a part of a surface of the inorganic ferroelectric.

6 . The separator according to claim 1 , wherein
a weight content of the inorganic ferroelectric in the ferroelectric material is 80%-99%, optionally 85%-95%; and/or a weight content of the ferroelectric polymer in the ferroelectric material is 1%-20%, optionally 5%-15%.

7 . The separator according to claim 1 , wherein the ferroelectric polymer satisfies at least one of the following conditions (1) to (5):
(1) a Curie temperature of the ferroelectric polymer is 150° C. to 250° C., optionally 160° C. to 200° C.; (2) a remanent polarization of the ferroelectric polymer is 10 mC/m 2 to 1000 mC/m 2 , optionally 20 mC/m 2 to 800 mC/m 2 ; (3) a weight-average molecular weight of the ferroelectric polymer is 200,000 to 800,000, optionally 400,000 to 650,000; (4) a melting temperature of the ferroelectric polymer is 140° C. to 220° C., optionally 143° C. to 200° C.; and (5) a crystallinity of the ferroelectric polymer is greater than or equal to 45%, optionally 45%-68%.

8 . The separator according to claim 1 , wherein a Curie temperature of the inorganic ferroelectric is 110° C. to 150° C., optionally 120° C. to 140° C.

9 . The separator according to claim 1 , wherein the ferroelectric polymer comprises one or more of polyvinylidene fluoride and copolymers of a vinylidene fluoride monomer with other monomers;
optionally, the other monomers comprise one or more of trifluoroethylene, chlorotrifluoroethylene, fluorinated acetylene, and hexafluoropropylene; optionally, the copolymers of the vinylidene fluoride monomer with other monomers comprise one or more of a vinylidene fluoride-trifluoroethylene copolymer, a vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene copolymer, a vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene-fluorinated acetylene copolymer, and a vinylidene fluoride-hexafluoropropylene copolymer.

10 . The separator according to claim 1 , wherein the inorganic ferroelectric comprises one or more of a perovskite type, a tungsten bronze type, a bismuth layer type, a pyrochlore type, a niobate type, and lead barium lithium niobate.

11 . The separator according to claim 1 , wherein
a volume distribution particle size Dv50 of the inorganic ferroelectric is 0.05 μm to 5 μm, optionally 0.1 μm to 1 μm; and/or a volume distribution particle size Dv50 of the ferroelectric polymer is 10 nm to 150 nm, optionally 15 nm to 50 nm.

12 . The separator according to claim 1 , wherein
a thickness of the ferroelectric coating is 1 μm to 3.5 μm, optionally 1.5 μm to 3 μm; and/or an areal density of the ferroelectric coating is 2.5 g/m 2 to 15 g/m 2 , optionally 3 g/m 2 to 12 g/m 2 .

13 . The separator according to claim 1 , wherein the ferroelectric coating further comprises a dispersant and/or a thickener;
optionally, the dispersant comprises one or more of hydrolyzed polymaleic anhydride, polyacrylic acid, an acrylic block copolymer, a polyester block copolymer, a polyethylene glycol polyol, polyethyleneimine, and respective derivatives thereof; optionally, a ratio of a total weight of the ferroelectric material to a weight of the dispersant is 1:(0.01-0.02), optionally 1:(0.010-0.015); optionally, the thickener comprises one or more of sodium hydroxymethylcellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, polyacrylate, polyurethane, and polyether; optionally, a ratio of the total weight of the ferroelectric material to a weight of the thickener is 1:(0.01-0.02), optionally 1:(0.010-0.015).

14 . The separator according to claim 1 , wherein the ferroelectric coating is located on one of surfaces of the porous substrate, and a ceramic coating is disposed on the other surface of the porous substrate; when applied to a battery, the ferroelectric coating faces a negative electrode and the ceramic coating faces a positive electrode.

15 . The separator according to claim 1 , wherein
a thickness of the porous substrate is 4 μm to 15 μm, optionally 5 μm to 10 μm; and/or the porous substrate comprises one or more of polyolefin, halogenated polyolefin, polyamide, polyester, and respective derivatives thereof.

16 . A battery cell, comprising the separator according to claim 1 .

17 . A battery, comprising the battery cell according to claim 16 .

18 . An electric device, comprising the battery according to claim 17 .

Assignees

• Contemporary Amperex Technology Co Ltd

Inventors

• Liu Feng
• Fan Yulei
• Guan Wenhao
• Zhong Wei
• Ge Xiaoming
• Ouyang Chuying

Classifications

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M50/423

  Polyamide resins · CPC title

• H01M50/491

  Porosity · CPC title

• H01M50/417

  Polyolefins · CPC title

• H01M50/446 Primary

  Composite material consisting of a mixture of organic and inorganic materials · CPC title