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JP-7856759-B2 - Electrode assemblies, secondary batteries, battery modules, battery packs, and power consumption devices

JP7856759B2JP 7856759 B2JP7856759 B2JP 7856759B2JP-7856759-B2

Inventors

  • 游興艷
  • 呉益揚
  • 白文龍
  • 武宝珍

Assignees

  • 香港時代新能源科技有限公司

Dates

Publication Date
20260511
Application Date
20220705

Claims (17)

  1. An electrode assembly comprising a negative electrode sheet, a positive electrode sheet, and a separator positioned between the negative electrode sheet and the positive electrode sheet, The negative electrode sheet comprises a negative electrode current collector and a first negative electrode film layer and a second negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the first negative electrode film layer is located between the negative electrode current collector and the second negative electrode film layer and comprises a first negative electrode active material containing graphite, and the second negative electrode film layer comprises a second negative electrode active material containing hard carbon. The separator comprises a base film and a functional coating layer located at least on the side of the base film facing the second negative electrode film layer, wherein the functional coating layer comprises an inorganic ferroelectric material. Electrode assembly.
  2. The thickness of the functional coating layer is H 1 μm, the thickness of the second negative electrode film layer is H 2 μm, the thickness of the first negative electrode film layer is H 3 μm, and the electrode assembly satisfies the condition that H 1 / (H 2 + H 3 ) is 0.01 to 0.15. The electrode assembly according to claim 1.
  3. The thickness of the functional coating layer is H1 μm, where H1 is 2 to 10. The electrode assembly according to claim 1.
  4. The thickness of the second negative electrode film layer is H 2 μm, the thickness of the first negative electrode film layer is H 3 μm, and the negative electrode sheet satisfies the condition that H 2 / H 3 is 0.10 to 5. The electrode assembly according to claim 1.
  5. The volume-average particle size Dv50 of the ferroelectric material is d 1 μm, and d 1 is 1 or less. The electrode assembly according to claim 1.
  6. The volume-average particle size Dv50 of the second negative electrode active material is d 2 μm, and the volume-average particle size Dv50 of the first negative electrode active material is d 3 μm, and d 2 / d 3 is between 0.1 and 1. The electrode assembly according to claim 1.
  7. The mass percentage of the ferroelectric material in the functional coating layer is W1, which is calculated based on the total mass of the functional coating layer, and W1 is between 70% and 95%. The electrode assembly according to claim 1.
  8. The functional coating layer further comprises an adhesive. The electrode assembly according to claim 1.
  9. The separator further includes an adhesive layer provided on the surface of the functional coating layer. The electrode assembly according to claim 1.
  10. The dielectric constant of the ferroelectric material is 50 or more. The electrode assembly according to claim 1.
  11. The mass percentage of hard carbon in the second negative electrode film layer is W2, and calculated based on the total mass of the second negative electrode film layer, W2 is 68% or more, and/or The mass percentage of graphite in the first negative electrode film layer is W3, and calculated based on the total mass of the first negative electrode film layer, W3 is 78% or more. The electrode assembly according to claim 1.
  12. The second negative electrode active material is (1) The volume average particle size Dv50 of the second negative electrode active material is d² μm, and d² is 3 to 11, satisfying the following conditions: The electrode assembly according to claim 1.
  13. The first negative electrode active material is (1) The volume average particle size Dv50 of the first negative electrode active material is d 3 μm, and d 3 is 9 to 18, satisfying the following conditions: The electrode assembly according to claim 1.
  14. The electrode assembly comprises the one described in claim 1. Secondary battery.
  15. A secondary battery as described in claim 14, Battery module.
  16. A secondary battery as described in claim 14, Battery pack.
  17. The invention comprises at least one of the secondary battery described in claim 14, the battery module described in claim 15, and the battery pack described in claim 16. Power consumption equipment.

Description

This application relates to the technical field of batteries, and specifically to electrode assemblies, secondary batteries, battery modules, battery packs, and power consumption devices. In recent years, secondary batteries have been widely used in many fields, including energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. With the application and widespread use of secondary batteries, the demands for energy density, cycle performance, and high-rate charging performance are increasing. The negative electrode active material is a crucial component of secondary batteries, and its performance influences the overall performance to some extent. Graphite is one of the most commonly used negative electrode active materials in secondary batteries, possessing the advantages of low polarization and high cycle stability, but its theoretical gram capacity (capacity per gram) is only 372 mAh/g. Currently, the performance of commercially available graphite has been developed to its maximum potential, and there is very little room for reversible improvement in both its gram capacity and energy density. At the same time, the interlayer spacing of graphite is small, and its high-rate charging performance has also been developed to its maximum potential. Hard carbon, as a novel negative electrode active material, has great potential for development because it can enable rapid intercalation and release of active ions during the charge-discharge process of secondary batteries. However, the compressive density and initial Coulomb efficiency of commercially available hard carbon are low, limiting the improvement in energy density of secondary batteries. This application provides an electrode assembly, a secondary battery, a battery module, a battery pack, and a power consumption device, thereby aiming to simultaneously achieve a high charge rate and a long cycle life, assuming that the secondary battery has a high energy density. A first aspect of this application provides an electrode assembly comprising a negative electrode sheet, a positive electrode sheet, and a separator located between the negative electrode sheet and the positive electrode sheet, wherein the negative electrode sheet comprises a negative electrode current collector and a first negative electrode film layer and a second negative electrode film layer provided on at least one surface of the negative electrode current collector, the first negative electrode film layer located between the negative electrode current collector and the second negative electrode film layer and comprising a first negative electrode active material containing graphite, the second negative electrode film layer comprising a second negative electrode active material containing hard carbon, and the separator comprises a base film and a functional coating layer located at least on the side of the base film facing the negative electrode sheet, the functional coating layer comprising a ferroelectric material. In the electrode assembly of this application, a two-layer combination design is achieved by sequentially providing a first negative electrode film layer containing graphite and a second negative electrode film layer containing hard carbon on the surface of the negative electrode current collector. This design compensates for the respective defects of graphite and hard carbon and brings out their respective advantages. The large interlayer spacing of the hard carbon allows for a higher charging rate, and the interposition of graphite between the hard carbon and the negative electrode current collector compensates for the initial Coulomb efficiency of the hard carbon. Furthermore, the potential at which active ions are absorbed into the microporous structure of the hard carbon is approximately 0V, which is close to the potential at which active ions are deposited from the graphite surface. Therefore, the function of the microporous structure of the hard carbon as a storage site for active ions cannot be fully utilized. However, the inventors of this application have surprisingly found that the above problem can be solved by providing a functional coating layer containing a ferroelectric material on at least the side of the separator closest to the second negative electrode film layer. Ferroelectric materials allow for control over the deposition method of active ions, thereby realizing the large-capacity advantages of the microporous structure of hard carbon. Furthermore, by suppressing the continuous reduction deposition of active ions on the graphite surface, the cycle life of the secondary battery can be improved. Therefore, a secondary battery using the electrode assembly of this application can have a long cycle life, be charged at high rates, have a high output voltage, and possess a high energy density. In any embodiment