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CN-122000430-A - Battery, preparation method thereof, method for evaluating flatness of battery, battery device and power utilization device

CN122000430ACN 122000430 ACN122000430 ACN 122000430ACN-122000430-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 flatness of the battery, a battery device and an electric device, wherein PDI of the battery is less than or equal to 0.094%, PDI= (sigma/mu) 2 /[1+(σ/μ) 2 , and sigma and mu are standard deviation and average value of thickness data of the battery respectively. The battery has higher capacity and better multiplying power performance.

Inventors

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

Assignees

  • 比亚迪股份有限公司

Dates

Publication Date
20260508
Application Date
20251231

Claims (11)

  1. 1. A battery is characterized in that PDI of the battery is less than or equal to 0.094%, wherein PDI= (sigma/mu) 2 /[1+(σ/μ) 2 , sigma and mu are standard deviation and average value of thickness data of the battery respectively, the thickness data comprise a plurality of thickness values corresponding to a surface lattice of at least one surface of the battery, and the point density of the surface lattice is more than or equal to 0.1/cm 2 .
  2. 2. The battery of claim 1, wherein the battery has a PDI of 0.088% or less.
  3. 3. The battery according to claim 1 or 2, wherein the dot density of the surface lattice is 1 to 200 dots per cm 2 .
  4. 4. A battery according to any one of claims 1 to 3, comprising two large faces arranged opposite each other and two narrow faces arranged opposite each other, the large faces having an area larger than the area of the narrow faces, the surface lattice being located on at least one large face of the battery.
  5. 5. The battery of any one of claims 1-4, wherein a distance between two adjacent points of the surface lattice is no more than 1cm.
  6. 6. A method of producing the battery of any one of claims 1 to 5, 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; the method meets at least one of the following conditions: the dyne value of the positive current collector is 55 mN/m-80 mN/m; The dyne value of the negative electrode current collector is 40 mN/m-65 mN/m.
  7. 7. The method of claim 6, wherein at least one of the following conditions is satisfied: The dyne value of the positive current collector is 72 mN/m-80 mN/m; the dyne value of the negative electrode current collector is 50 mN/m-65 mN/m.
  8. 8. 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 average μ and a standard deviation σ of the thickness data; if the battery meets PDI= (sigma/mu) 2 /[1+(σ/μ) 2 ] < 0.094%, the flatness of the battery is qualified, otherwise, the flatness of the battery is not qualified.
  9. 9. The method of claim 8, 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 ℃.
  10. 10. A battery device comprising the battery according to any one of claims 1 to 5.
  11. 11. An electric device comprising the battery according to any one of claims 1 to 5 or the battery device according to claim 10.

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 In solid state battery systems, ion transport at the solid-solid interface is strongly dependent on the stability of the interparticle contact. When the flatness of the surface of the battery is different, a high pressure area (such as a convex part) and a low pressure area (such as a concave part) are generated under the restraint force condition, for example, when 5MPa restraint force is applied, the pressure difference between the two areas can reach 15MPa, uneven distribution of ion flux and current density is further caused, and the capacity exertion and the multiplying power performance of the battery are affected. Meanwhile, the contact between particles in the low-pressure region is insufficient, and part of active particles cannot participate in electrochemical reaction, so that the capacity of the battery is reduced. Therefore, how to control the flatness of the battery within a certain range to avoid the above problems is one of the challenges facing today. 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 with high surface flatness and capability of effectively playing capacity and multiplying power, 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 the embodiment of the application, PDI of the battery is less than or equal to 0.094%, wherein PDI= (sigma/mu) 2/[1+(σ/μ)2, sigma and mu are respectively standard deviation and average value of thickness data of the battery, the thickness data comprise a plurality of thickness values corresponding to a surface lattice of at least one surface of the battery, and the point density of the surface lattice is more than or equal to 0.1/cm 2. Specifically, the PDI value of the battery is normalized, and is calculated based on the standard deviation (sigma) and the average value (mu) of the thickness data, so that the sensitivity to abnormal values is low, and the general fluctuation and the serious unevenness can be better distinguished. Meanwhile, (sigma/mu) 2 in the PDI can amplify the contribution of high deviation, the PDI is more in line with the actual requirement of battery performance, the PDI balances the defects of 'extremely poor' and 'variation coefficient (sigma/mu) 2', excessive dependence on extreme values or high deviation neglected is avoided, and the thickness distribution uniformity of the battery can be reflected more accurately to quantify the flatness of the battery. The PDI is controlled to be less than or equal to 0.094%, so that the uniform distribution of the surface thickness of the battery can be ensured, the high flatness is realized, the local high-impedance area is reduced, the utilization rate of active substances is improved, the capacity of the battery is improved, meanwhile, the battery with high flatness is uniformly stressed in a constrained state, the rapid transmission of active ions and the homogenization of ion flux can be promoted, and the rate capability of the battery is improved. According to an embodiment of the application, the PDI of the battery is less than or equal to 0.088%. 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, assembling the positive electrode plate, a separation layer and the negative electrode plate to obtain the battery, wherein at least one of the following conditions is met by the method, the current collector has a dyne value of 55-80 mN/m, specifically 72-80 mN/m, and the current collector has a dyne value of 40-65 mN/m, specifically 50-65 mN/m.