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CN-122000429-A - Battery, preparation method thereof, method for evaluating flatness of battery, battery device and power utilization device

CN122000429ACN 122000429 ACN122000429 ACN 122000429ACN-122000429-A

Abstract

The application belongs to the technical field of batteries, and particularly relates to a battery, a preparation method thereof, a method for evaluating the flatness of the battery, a battery device and an electric device, wherein the surface thickness distribution coefficient SPAN (a-b) = (T a -T b ）/T 50 ) of the battery meets at least one of the following conditions that SPAN (100) is less than or equal to 4.11%, SPAN (90) is less than or equal to 1.73%, SPAN (80) is less than or equal to 1.24%, SPAN (70) is less than or equal to 0.99%, SPAN (60) is less than or equal to 0.80%, and SPAN (50) is less than or equal to 0.64%.

Inventors

  • CUI MANYING
  • MA YONGJUN
  • WAN YUE
  • WU MINGDA
  • GUO ZIZHU

Assignees

  • 比亚迪股份有限公司

Dates

Publication Date
20260508
Application Date
20251231

Claims (13)

  1. 1. A battery characterized in that a surface thickness distribution coefficient SPAN (a-b) = (T a -T b ）/T 50 ) of the battery satisfies at least one of the following conditions: SPAN(100)≤4.11%; SPAN(90)≤1.73%; SPAN(80)≤1.24%; SPAN(70)≤0.99%; SPAN(60)≤0.80%; SPAN(50)≤0.64%; wherein T a represents the a-th percentile of the thickness data of the battery, T b represents the b-th percentile of the thickness data of the cell, T 50 represents the 50 th percentile of the thickness data of the cell, a+b=100; The thickness data comprises a plurality of thickness values corresponding to a surface lattice of at least one surface of the battery, and the dot density of the surface lattice is more than or equal to 0.1/cm 2 .
  2. 2. The battery of claim 1, wherein 50-b-100 or 70-a-b-90.
  3. 3. The battery according to claim 1 or 2, characterized in that at least one of the following conditions is satisfied: 75≤a≤100; 0≤b≤25。
  4. 4. a battery according to any one of claims 1 to 3, wherein the dot density of the surface lattice is 1 to 200 per cm 2 per cm 2 .
  5. 5. The battery of any one of claims 1-4, comprising two large faces disposed opposite each other and two narrow faces disposed opposite each other, the large faces having an area greater than an area of the narrow faces, the surface lattice being located on at least one large face of the battery.
  6. 6. The battery of any one of claims 1-5, wherein a distance between two adjacent points of the surface lattice is no more than 1cm.
  7. 7. A method of producing the battery of any one of claims 1 to 6, comprising: coating the positive electrode slurry on at least one side of a positive electrode current collector to obtain a positive electrode plate; Coating the negative electrode slurry on at least one side of a negative electrode current collector to obtain a negative electrode plate; assembling the positive plate, the separation layer and the negative plate to obtain the battery; Wherein at least one of the positive electrode slurry and the negative electrode slurry is coated using a wet-wet double-layer coating method.
  8. 8. The method of claim 7, wherein at least one of the following conditions is satisfied: The solid content of the positive electrode slurry is 70% -80%; The fineness of the positive electrode slurry is 10-15 mu m; the viscosity of the positive electrode slurry is 300-800 mpa.s at 50s -1 ; The double-sided density of the positive plate is 420-450 g.m -2 ; The separator layer is an electrolyte layer.
  9. 9. The method according to claim 7 or 8, characterized in that at least one of the following conditions is fulfilled: the solid content of the negative electrode slurry is 40% -50%; The fineness of the negative electrode slurry is 5-10 mu m; The viscosity of the negative electrode slurry is 100-500 mpa.s at 50s -1 ; the double-sided density of the negative plate is 170-190 g.m -2 .
  10. 10. A method of evaluating flatness of a battery, comprising: Performing thickness measurement on a surface lattice on at least one surface of the battery to obtain thickness data containing a plurality of thickness values, wherein the dot density of the surface lattice is more than or equal to 0.1/cm 2 ; Determining an a-th percentile T a , a b-th percentile T b , a 50-th percentile T 50 of the thickness data, and calculating a surface thickness distribution coefficient SPAN (a-b) = (T a -T b ）/T 50 , a+b=100) of the obtained battery; If the surface thickness distribution coefficient SPAN (a-b) of the battery meets at least one of the following conditions, the flatness of the battery is qualified, otherwise, the flatness of the battery is unqualified; SPAN(100)≤4.11%; SPAN(90)≤1.73%; SPAN(80)≤1.24%; SPAN(70)≤0.99%; SPAN(60)≤0.80%; SPAN(50)≤0.64%。
  11. 11. The method of claim 10, wherein the thickness data is obtained using a three-coordinate gauge test and at least one of the following conditions is satisfied: The measurement mode of the three-coordinate measuring instrument is lattice scanning; the probe sampling point interval of the three-coordinate measuring instrument is 0.01 cm-1 cm; The probe moving speed of the three-coordinate measuring instrument is 40-80 mm/s; The precision of the three-coordinate measuring instrument is +/-2 mu m; the test temperature of the three-coordinate measuring machine is 25 ℃.
  12. 12. A battery device comprising the battery according to any one of claims 1 to 6.
  13. 13. An electric device comprising the battery according to any one of claims 1 to 6 or the battery device according to claim 12.

Description

Battery, preparation method thereof, method for evaluating flatness of battery, battery device and power utilization device Technical Field The application relates to the field of batteries, in particular to a battery, a preparation method thereof, a method for evaluating flatness of the battery, a battery device and an electric device. Background Because of the solid-solid contact problem between particles, external Gao Jushu force (generally more than 3 MPa) is needed to maintain stable interface contact, and in a high-restraint state, serious uneven stress distribution is caused by small deviation of the surface flatness of the battery, so that the capacity of a low-stress area cannot be exerted to influence the whole capacity of the battery, and meanwhile, the porosity and interface contact of the high-stress area and the low-stress area of the battery are different, so that the interface impedance and the lithium ion flux are different to influence the capacity exertion and the multiplying power performance of the battery. Therefore, problems related to the flatness of the battery surface remain to be improved. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, the invention provides a battery capable of effectively exerting capacity and multiplying power performance, a preparation method thereof, a method for evaluating the flatness of the battery, a battery device and an electric device. A first aspect of the application provides a battery. According to an embodiment of the present application, the surface thickness distribution coefficient SPAN (a-b) = (T a-Tb）/T50 satisfies at least one of the following conditions: SPAN(100)≤4.11%; SPAN(90)≤1.73%; SPAN(80)≤1.24%; SPAN(70)≤0.99%; SPAN(60)≤0.80%; SPAN(50)≤0.64%; wherein T a represents the a-th percentile of the thickness data of the battery, T b represents the b-th percentile of the thickness data of the cell, T 50 represents the 50 th percentile of the thickness data of the cell, a+b=100; The thickness data comprises a plurality of thickness values corresponding to a surface lattice of at least one surface of the battery, and the dot density of the surface lattice is more than or equal to 0.1/cm 2. Meanwhile, the surface thickness distribution coefficient SPAN value focuses intermediate data, is closer to an actual stress area in a battery restraint state, the surface thickness distribution coefficient of the battery is directly related to stress distribution in the battery restraint state, the surface thickness distribution coefficient SPAN value is directly related to battery performance, and the surface thickness distribution coefficient SPAN value can more accurately reflect capacity performance and rate performance differences of the battery. In the battery, the surface thickness distribution coefficient SPAN value is controlled to meet the requirements, so that the battery has higher flatness, the stress uniformity of the battery is improved, the ion transmission and ion flux in the circulation process are more uniform, the local current density is prevented from being too high, the utilization rate of the whole active material is improved, and the capacity of the battery is higher, and the rate capability is better. According to embodiments of the present application, 50≤a-b≤100, or 70≤a-b≤90. According to an embodiment of the present application, the battery satisfies at least one of the following conditions: 75≤a≤100; 0≤b≤25。 According to the embodiment of the application, the dot density of the surface dot matrix is 1/cm 2 -200/cm 2. According to an embodiment of the application, the battery comprises two large faces arranged oppositely and two narrow faces arranged oppositely, the area of the large faces is larger than that of the narrow faces, and the surface lattice is located on at least one large face of the battery. According to an embodiment of the application, the distance between two adjacent points of the surface lattice is not more than 1cm. In a second aspect of the application, there is provided a method of making a battery as hereinbefore described. According to the embodiment of the application, the method comprises the steps of coating positive electrode slurry on at least one side of a positive electrode current collector to obtain a positive electrode plate, coating negative electrode slurry on at least one side of a negative electrode current collector to obtain a negative electrode plate, and assembling the positive electrode plate, a separation layer and the negative electrode plate to obtain the battery, wherein at least one of the positive electrode slurry and the negative electrode slurry is coated by a wet and wet double-layer coating method. In the wet-wet double-layer coating method, an upper die head, a lower die head and a double discharge hole are adopted, the upper layer and the lower layer can be coated simultaneous