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US-12626999-B2 - Separator, battery cell, battery and electrical apparatus

US12626999B2US 12626999 B2US12626999 B2US 12626999B2US-12626999-B2

Abstract

The present application relates to a separator, a battery cell, a battery and an electrical apparatus, wherein the separator comprises two surfaces opposite to each other along its own thickness direction, at least one of the surface of the separator and the interior of the separator comprises a pore structure, and the separator further comprises a swellable polymer; the separator satisfies: when a pressure of 1.25 MPa is applied along the thickness direction of the separator, the compression rate ΔV of the separator is ≤25%.

Inventors

  • Baiqing Li
  • Shuangjuan PENG
  • Lin Peng
  • Cheng Ji
  • Yao Li
  • Ou Qian
  • Haizu Jin
  • Fenggang Zhao

Assignees

  • CONTEMPORARY AMPEREX TECHNOLOGY CO., LIMITED

Dates

Publication Date
20260512
Application Date
20250819

Claims (20)

  1. 1 . A separator comprising two surfaces opposite to each other along its own thickness direction, wherein at least one surface of the two surfaces of the separator and/or an interior of the separator comprises a pore structure, the pore structure comprises a first recessed area, and the separator further comprises a swellable polymer capable of absorbing an electrolyte solution and locking the electrolyte solution into the separator, the swellable polymer comprises at least one of a first fluoropolymer, a first ester polymer, and a first ether polymer; and the separator satisfies: when a pressure of 1.25 MPa is applied along the thickness direction of the separator, a compression rate ΔV of the separator is ≤25%.
  2. 2 . The separator according to claim 1 , wherein the separator further satisfies: a separator with an area of 5 cm×10 cm is taken and its mass ms1 is recorded in g; the separator is immersed in excessive electrolyte solution at 25° C. for 7 days, then taken out and placed vertically until there is no droplet for 5 min, and its mass ms2 is recorded in g, then, ((ms2−ms1)/ms1)×100%≥10%.
  3. 3 . The separator according to claim 1 , wherein a swelling rate of the swellable polymer is ≥100%.
  4. 4 . The separator according to claim 1 , wherein a compression modulus of the separator is ≥45 MPa.
  5. 5 . The separator according to claim 1 , wherein the separator comprises a first porous substrate film containing the swellable polymer capable of absorbing the electrolyte solution and locking the electrolyte solution into the first porous substrate film.
  6. 6 . The separator according to claim 1 , wherein the separator comprises a second porous substrate film and a coating provided on at least one side of the second porous substrate film, and the coating comprises the swellable polymer capable of absorbing the electrolyte solution and locking the electrolyte solution into the coating, the surface of the coating facing away from the second porous substrate film comprises the first recessed area; or the first recessed area is enclosed between the coating and the second porous substrate film.
  7. 7 . A battery cell comprising an electrode assembly and an electrolyte solution, wherein the electrode assembly comprises the separator according to claim 1 .
  8. 8 . The battery cell according to claim 7 , further satisfying: V 0 /(m/ρ)≥1; in a formula, V 0 represents a pore volume and interlayer gap volume in the electrode assembly in mL; m represents a difference between a mass of the battery cell before oven drying and a mass after oven drying in g; ρ represents a density of the electrolyte solution in g/mL.
  9. 9 . The battery cell according to claim 7 , wherein the electrode assembly comprises a first electrode plate and a second electrode plate, the first electrode plate and the second electrode plate are opposite in polarity, the separator is provided between the first electrode plate and the second electrode plate, and the surface of the first electrode plate facing toward the separator has at least one second recessed area.
  10. 10 . The battery cell according to claim 9 , wherein the first electrode plate comprise a current collector and a film layer provided on at least one surface of the current collector, the film layer comprises a liquid-retaining polymer and active material particles, the liquid-retaining polymer is distributed on a surface of the active material particles facing away from the current collector, the liquid-retaining polymer is capable of absorbing and locking an electrolyte solution to form an elastic porous sustained-release electrolyte adhered to the surface of the active material particles.
  11. 11 . The battery cell according to claim 7 , wherein the battery cell further comprises an electrolyte solution, and the electrolyte solution is located inside the electrode assembly.
  12. 12 . The battery cell according to claim 7 , wherein the battery cell satisfies: ( m / ρ ) / V total ⁢ pore ⁢ space ≥ 80 ⁢ % ; V total pore space represents a numerical value of pore volume of the electrode assembly in mL; m represents a numerical value of difference between a mass of the battery cell before oven drying and a mass after oven drying in g; ρ represents a numerical value of density of the electrolyte solution in g/mL.
  13. 13 . The battery cell according to claim 7 , wherein the battery cell satisfies: 0 ≤ y / Ah ≤ 15 ⁢ % ; y represents a numerical value of volume of free electrolyte solution in the battery cell in mL; Ah represents a numerical value of nominal capacity of the battery cell in Ah.
  14. 14 . The battery cell according to claim 7 , wherein the battery cell satisfies: 0 ≤ y / V total ⁢ pore ⁢ space ≤ 15 ⁢ % ; y represents a numerical value of volume of free electrolyte solution in the battery cell in mL; V total pore space represents a numerical value of pore volume of the electrode assembly in mL.
  15. 15 . The battery cell according to claim 7 , wherein after a linear frequency sweep vibration test, the battery cell is charged to 100% state of charge (SOC), a hole is opened on the battery cell, the hole is provided at the lowest site in a vertical direction, and the volume of the electrolyte solution flowing out of the battery cell is recorded as M1, 0 mL≤M1≤0.5 mL; wherein a vibration direction of a linear frequency sweep vibration test is: up-and-down single vibration; a vibration frequency of a linear frequency sweep vibration test is: 10 Hz to 55 Hz; the maximum acceleration of a linear frequency sweep vibration test is: 30 m/s 2 ; a number of frequency sweep cycles of a linear frequency sweep vibration test is: 10 times; and a vibration time of a linear frequency sweep vibration test is: 3 h.
  16. 16 . The battery cell according to claim 7 , wherein after a linear frequency sweep vibration test, the battery cell is charged to 100% state of charge (SOC), a hole is opened on the battery cell, the hole is provided at the lowest site in a vertical direction, and the volume of the electrolyte solution flowing out of the battery cell is recorded as M1, and M1 is 0 mL, wherein after the battery cell is subjected to a linear frequency sweep vibration test, the electrode assembly is taken out, and after the electrode assembly is subjected to an extrusion test, the volume of the electrolyte solution flowing out of the electrode assembly is recorded as M2, 0 mL≤M2≤0.5 mL; and, wherein an extrusion direction of the extrusion test is: perpendicular to the thickness direction of the electrode assembly; an extrusion degree of the extrusion test is: an extrusion pressure is 0.35 MPa, wherein after the battery cell is subjected to the linear frequency sweep vibration test, the electrode assembly is taken out, and after the electrode assembly is subjected to the extrusion test, the volume of the electrolyte solution flowing out of the electrode assembly is recorded as M2, and M2 is 0 mL.
  17. 17 . The battery cell according to claim 7 , wherein the first fluoropolymer comprises at least one of the structural units represented by formula (AI), formular (AII), or formula (AIII), in formula (AI) and formula (AII), R 11 , R 12 , R 13 and R 14 each independently comprise a hydrogen atom, a fluorine atom, a chlorine atom, substituted or unsubstituted alkyl or substituted or unsubstituted alkoxy, and at least one of R 11 , R 12 , R 13 and R 14 comprises a fluorine atom, in formula (AIII), R 15 includes a single bond, substituted or unsubstituted alkyl; when substituted, the substituent includes a fluorine atom, p is a positive integer selected from 1 to 3, R 11 , R 12 , R 13 and R 14 each independently comprise a hydrogen atom, a fluorine atom, a chlorine atom, substituted or unsubstituted alkyl or substituted or unsubstituted alkoxy, the first ether polymer comprises a structural unit represented by formula (BI), in formula (BI), R 21 and R 22 each independently comprise a hydrogen atom, substituted or unsubstituted alkyl, or substituted or unsubstituted alkoxy; and R 23 comprises a single bond or substituted or unsubstituted methylene, in formula (BII), R 24 to R 27 each independently comprise a hydrogen atom, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, or an ether group, and at least one of R 24 to R 27 comprises substituted or unsubstituted alkoxy or an ether group, the first ester polymer comprises a structural unit represented by formula (CI), formula (CII), or formula (CIII), in formula (CI), R 31 , R 32 and R 33 each independently comprise a hydrogen atom or substituted or unsubstituted alkyl; R 34 comprises substituted or unsubstituted alkyl or substituted or unsubstituted hydroxyalkyl, in the formula (CII), R 35 comprises substituted or unsubstituted methylene, in formula (CIII), R 36 , R 37 and R 38 each independently comprise a hydrogen atom, or substituted or unsubstituted C1-C8 alkyl; R 39 comprises substituted or unsubstituted C1-C8 alkyl.
  18. 18 . The battery cell according to claim 7 , wherein the swellable polymer comprises the first fluoropolymer, the first fluoropolymer is at least one selected from polyperfluoroethylene PTFE, polyvinylidene fluoride PVDF, perfluoroethylene propylene copolymer FEP, perfluoroalkoxy polymer PFA, perfluoropolyether PFPE, polyvinylidene fluoride-hexafluoropropylene copolymer PVDF-HFP, polyvinylidene fluoride-trifluoroethylene copolymer PVDF-TrFE, and perfluoro (1-butenyl vinylether) polymer.
  19. 19 . A battery, comprising a battery cell, the battery cell comprising the separator according to claim 1 .
  20. 20 . An electrical apparatus, comprising the battery according to claim 19 .

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation of International Application No. PCT/CN2024/072431, filed on Jan. 16, 2024, which claims priority to the Chinese Patent Application No. 202310409606.X filed on Apr. 17, 2023 and entitled “SEPARATOR, BATTERY CELL, BATTERY AND ELECTRICAL APPARATUS,” which is incorporated herein by reference in its entirety. TECHNICAL FIELD The present application relates to the technical field of batteries, and more particularly, to a separator, a battery cell, a battery, and an electrical apparatus. BACKGROUND Battery cells feature high capacity, long service life and the like, so that they are widely used in electronic devices, such as mobile phones, laptops, electromobiles, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and electric tools. However, as the application range of batteries becomes more and more extensive, the requirements on the performance of battery cells are becoming increasingly stringent. In order to improve the performance of battery cells, the battery cells are usually optimized and improved; however, the operational reliability and cycling performance of the battery cells are still poor. SUMMARY OF THE INVENTION The present application is conducted in view of the above issues, and aims to provide a separator, a battery cell, a battery, and an electrical apparatus. In a first aspect, the present application proposes a separator, the separator comprises two surfaces opposite to each other along its own thickness direction, at least one of the surface of the separator and the interior of the separator comprises a pore structure, and the separator further comprises a swellable polymer; the separator satisfies: when a pressure of 1.25 MPa is applied along the thickness direction of the separator, the compression rate ΔV of the separator is ≤25%. Therefore, when the separator in the embodiments of the present application meets the above conditions, the separator can have both good liquid absorption capacity and excellent compression resistance, and the pore structure will basically not undergo compression deformation, so that the electrolyte solution can be stored in the pore structure, thereby reducing the risk of the electrolyte solution being squeezed out of the electrode assembly, and improving the operational reliability and cycling performance of the battery cell. In some embodiments, at least one surface of the separator comprises a pore structure, and the pore structure comprises a first recessed area. In some embodiments, the separator further satisfies: a separator with an area of 5 cm×10 cm is taken and its mass ms1 is recorded in g;the separator is immersed in excessive electrolyte solution at 25° C. for 7 days, then taken out and placed vertically until there is no droplet for 5 min, and its mass ms2 is recorded in g,then, ((ms2−ms1)/ms1)×100%≥10%. Therefore, when the embodiments of the present application satisfy the above range, the liquid absorption capacity of the separator is relatively strong, which is conducive to adsorbing the electrolyte solution into the swellable polymer molecular chain, thereby improving the cycling performance of the battery cell. In some embodiments, the swelling rate of the swellable polymer is ≥100%. When the swelling rate of the swellable polymer is within the above range, the electrolyte solution more easily diffuses between the polymer molecular chains of the separator, so that the separator has a better liquid absorption capacity. In some embodiments, the compression modulus of the separator is ≥45 MPa. When the separator in the embodiments of the present application meets the above conditions, the separator has excellent compression resistance and the pore structure basically does not undergo compression deformation, thereby reducing the risk of the electrolyte solution being squeezed out of the electrode assembly, and improving the operational reliability and cycling performance of the battery cell. In some embodiments, the separator comprises a first porous substrate film comprising the swellable polymer. In some embodiments, the first porous substrate film is provided with the pore structure inside. In some embodiments, the surface of the first porous substrate film comprises at least one first recessed area. In some embodiments, the separator comprises a second porous substrate film and a coating provided on at least one side of the second porous substrate film, wherein the coating comprises the swellable polymer. In some embodiments, the surface of the coating facing away from the second porous substrate film comprises at least one first recessed area. In some embodiments, the first recessed area is enclosed between the coating and the second porous substrate film. In some embodiments, the swellable polymer includes at least one of a first fluoropolymer, a first ester polymer and a first ether polymer.