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CN-121977974-A - Method for measuring electrolyte infiltration degree of battery cell

CN121977974ACN 121977974 ACN121977974 ACN 121977974ACN-121977974-A

Abstract

The application provides a method for measuring the electrolyte infiltration degree of a battery cell, which solves the problems of low precision and long time consumption in the measurement of the electrolyte infiltration degree of the battery cell by adopting a battery cell cycle life test method in the prior art. The risk measurement method comprises the steps of disassembling a battery cell subjected to infiltration treatment to obtain a negative electrode plate to be measured, dividing the negative electrode plate to be measured into a target area and a reference area, wherein the target area and the reference area are arranged along a first direction, part of the outer edge of the reference area forms part of the outer edge of the negative electrode plate to be measured, the target area is spaced from the outer edge of the negative electrode plate to be measured, the content of metal elements in unit area of the target area is measured to be a first content, the content of metal elements in unit area of the reference area is measured to be a second content, and the electrolyte infiltration degree of the battery cell is judged according to the ratio of the first content to the second content.

Inventors

  • LI JINCHENG
  • CHEN Jin
  • ZHOU JIE

Assignees

  • 蜂巢能源科技股份有限公司

Dates

Publication Date
20260505
Application Date
20260408

Claims (10)

  1. 1. The method for determining the electrolyte infiltration degree of the battery cell is characterized by comprising the following steps of: Disassembling the battery cell subjected to electrolyte infiltration treatment to obtain a negative plate to be measured; dividing the negative electrode plate to be measured into a target area and a reference area, wherein the target area and the reference area are in one-to-one correspondence, the target area and the corresponding reference area are arranged along a first direction, and the target area is spaced from the outer edge of the negative electrode plate to be measured along the first direction; Measuring the content of metal elements in a unit area of the target area as a first content, and measuring the content of metal elements in a unit area of the reference area as a second content, wherein the electrolyte in the battery cell comprises the metal elements; and determining the electrolyte infiltration degree of the battery cell according to the ratio of the first content to the second content.
  2. 2. The method of claim 1, wherein dividing the negative electrode sheet to be measured into a target area and a reference area comprises: dividing the negative plate to be detected into m first areas at equal intervals along the second direction of the negative plate to be detected; Equally dividing each first area into n second areas along the first direction; the target area comprises p second areas in one first area, the corresponding reference area at least comprises a 1 st second area and an n-th second area in the corresponding first area, m is more than or equal to 2, n is more than or equal to 3, p is more than or equal to 1, m, n and p are integers, and the first direction is intersected with the second direction.
  3. 3. The method of claim 2, wherein one of said reference regions comprises q second regions, q/2 of said second regions being located on one side of the corresponding target region and q/2 of said second regions being located on the other side of the corresponding target region along said first direction, wherein q is an even number.
  4. 4. A method according to claim 3, wherein the target region meets the corresponding reference region at both ends aligned in the first direction.
  5. 5. The method according to any one of claims 2 to 4, wherein, If the number of the second areas included in one of the first areas is an odd number, the ith second area forms a target area, wherein i= (n+1)/2, and/or, If the number of the second areas included in one first area is even, the ith and (i+1) th second areas form a target area, wherein i=n/2.
  6. 6. The method of any one of claims 2-4, wherein the ratio of the first content to the second content The method meets the following conditions: Wherein, the method comprises the steps of, ; ; Wherein, the Representing the content of the metal element in the ith one of the second regions in one of the target regions, Representing the content of the metal element in the ith one of the second regions in one of the reference regions, Representing the number of said second areas comprised by one of said reference areas, Representing the number of said second areas comprised by one of said target areas.
  7. 7. The method of any one of claims 1-4, wherein determining the electrolyte wetting degree of the cell based on the ratio of the first content and the second content comprises: If the ratio of at least one first content to the corresponding second content is smaller than 0.92, determining that the electrolyte of the battery cell is insufficiently infiltrated; and if the ratio of each first content to the corresponding second content is greater than or equal to 0.92, judging that the electrolyte of the battery cell is fully soaked.
  8. 8. The method of claim 7, wherein determining that the electrolyte of the cell is under-impregnated if the ratio of at least one of the first contents to the corresponding second contents is less than 0.92 comprises: If the ratio of at least one first content to the corresponding second content is smaller than or equal to 0.8, determining that the electrolyte infiltration degree of the battery cell is a first insufficient degree; if the ratio of at least one first content to the corresponding second content is greater than 0.8 and less than or equal to 0.86, determining that the electrolyte infiltration degree of the battery cell is a second insufficient degree; if the ratio of at least one first content to the corresponding second content is more than 0.86 and less than 0.9, determining that the electrolyte infiltration degree of the battery cell is a third insufficient degree; And if the ratio of at least one first content to the corresponding second content is more than or equal to 0.9 and less than 0.92, judging that the electrolyte infiltration degree of the battery cell is a fourth insufficient degree.
  9. 9. The method according to any one of claims 1 to 4, wherein the step of disassembling the cell subjected to the electrolyte infiltration treatment to obtain the negative electrode sheet to be measured includes: Disassembling the impregnated battery cell to obtain an original negative plate, wherein one end of the original negative plate in the first direction is used for being connected with a tab of the battery cell; removing the edge section of the original negative plate to obtain the negative plate to be detected; Wherein the width d of the edge section in the first direction is such that d is less than or equal to 10mm.
  10. 10. The method of claim 9, wherein disassembling the impregnated battery cell to obtain the original negative plate comprises: Disassembling the electrical core subjected to the infiltration treatment, and taking out the pole group; And disassembling at least one original negative plate positioned at the center of the pole group along the thickness direction of the pole group.

Description

Method for measuring electrolyte infiltration degree of battery cell Technical Field The application relates to the technical field of batteries, in particular to a method for measuring electrolyte infiltration degree of a battery cell. Background In the manufacturing process of the battery, the electrolyte fully and uniformly infiltrates the pole piece, which is a key precondition for guaranteeing the performance and safety of the battery core. The term "impregnation" refers to a process in which an electrolyte permeates and fills pores of the positive and negative electrode active materials and micropores of the separator. If the infiltration is insufficient or uneven, the ion conductivity of a local area is obviously reduced, and the phenomena of ion migration blockage and current density distribution unbalance are caused in the charging process, so that ions are forced to be directly reduced into metal on the surface of the negative electrode, namely, metal ion precipitation occurs. The metal ions are separated out to cause irreversible capacity loss and form metal dendrites on the surface of the negative electrode plate. These dendrites may puncture the separator, cause internal short circuits, and in severe cases lead to thermal runaway and even fire explosion, greatly threatening the battery safety. Particularly in fast charge, low temperature charge or high energy density batteries, the risk of metal ion precipitation is even more pronounced. In view of this, the current industry usually indirectly evaluates the infiltration state of the battery cell through the cycle life test result of the battery cell, namely, the battery cell is circulated for a long time under a standard charge-discharge system, and if the capacity decays too fast or the voltage is abnormal, the infiltration problem is deduced in a reverse direction. The method relies on macroscopic performance of the battery in the actual use process, belongs to a post verification means, and cannot measure the infiltration degree of electrolyte in the early stage of manufacturing the battery cell. Because the cycle life test cycle is long (hundreds of cycles are usually needed), the cost is high, the result is comprehensively influenced by various factors (such as material aging, side reaction and the like), and capacity attenuation is difficult to be directly attributed to initial infiltration unevenness, the infiltration state of the battery cell is indirectly estimated through the cycle life test method of the battery cell, and the problems of lower precision and overlong estimation time exist. Disclosure of Invention In view of the above, the embodiment of the application aims to provide a method for determining the electrolyte infiltration degree of a battery cell, so as to solve the problems of low accuracy and long time consumption in determining the electrolyte infiltration degree of the battery cell by adopting a battery cell cycle life test method in the prior art. In a first aspect, an embodiment of the present application provides a method for determining an electrolyte infiltration degree of a cell, including: Disassembling the battery cell subjected to electrolyte infiltration treatment to obtain a negative plate to be measured; dividing the negative electrode plate to be measured into a target area and a reference area, wherein the target area and the reference area are in one-to-one correspondence, the target area and the corresponding reference area are arranged along a first direction, and the target area is spaced from the outer edge of the negative electrode plate to be measured along the first direction; Measuring the content of metal elements in a unit area of the target area as a first content, and measuring the content of metal elements in a unit area of the reference area as a second content, wherein the electrolyte in the battery cell comprises the metal elements; and determining the electrolyte infiltration degree of the battery cell according to the ratio of the first content to the second content. Optionally, dividing the negative electrode sheet to be measured into a target area and a reference area includes: dividing the negative plate to be detected into m first areas at equal intervals along the second direction of the negative plate to be detected; Equally dividing each first area into n second areas along the first direction; the target area comprises p second areas in one first area, the corresponding reference area at least comprises a 1 st second area and an n-th second area in the corresponding first area, m is more than or equal to 2, n is more than or equal to 3, p is more than or equal to 1, m, n and p are integers, and the first direction is intersected with the second direction. Optionally, one of the reference regions includes q second regions, q/2 of the second regions are located on one side of the corresponding target region along the first direction, and q/2 of the second regions are located on