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CN-122025885-A - Method for judging alternating-current internal resistance of battery cell, application of method and battery cell matching method

CN122025885ACN 122025885 ACN122025885 ACN 122025885ACN-122025885-A

Abstract

The invention provides a judging method of alternating current internal resistance of a battery cell, application of the judging method and a battery cell matching method, and relates to the technical field of batteries. The method for judging the alternating-current internal resistance of the battery cell comprises the steps of pre-charging the battery cell after liquid injection, then aging the pre-charged battery cell, wherein the larger the voltage reduction amplitude is during aging, the larger the alternating-current internal resistance of the battery cell is, the pre-charging comprises the following steps of carrying out constant-current discharge on 5~10 min;S2.0.02C~0.1C to 0 SOC by means of constant-current charging at S1.0.02C-0.1C, carrying out constant-current charging at 2-5 min, carrying out constant-current charging at 3.0.02-0.1C for 5-10 min, and repeating S2 and S3 for 0-3 times. The judging method is simple and efficient, can accurately judge the alternating current internal resistance of the battery cells and is further applied to the matching of the battery cells by adding a pre-charging process and monitoring the voltage change condition after aging to judge the internal resistance condition of the battery cells.

Inventors

  • SUN CHAO
  • ZHANG YANG
  • SONG ZHANGXUN
  • Yang Yishuang
  • YANG QINGHENG

Assignees

  • 江苏中兴派能电池有限公司

Dates

Publication Date
20260512
Application Date
20260327

Claims (8)

  1. 1. A method for judging the AC internal resistance of a battery cell is characterized by comprising the steps of pre-charging the battery cell after liquid injection, and then aging the pre-charged battery cell, wherein the larger the voltage reduction amplitude is during aging, the larger the AC internal resistance of the battery cell is; The pre-charging comprises the following steps: S1.0.02C-0.1C constant current charging for 5-10 min; S2.0.02C-0.1C constant current is discharged to 0 SOC, and the mixture is placed for 2-5 min; S3.0.02C-0.1C constant current charging for 5-10 min; repeating the steps S2 and S3 for 0-3 times; The battery cell is prepared by adopting the same process.
  2. 2. The method of claim 1, wherein the cells are pre-charged in a temperature environment of 25-45 ℃.
  3. 3. The method according to claim 1, wherein the aging treatment temperature is 25-45 ℃; the aging treatment time is 5-48 h.
  4. 4. The method of claim 1, wherein the smaller the voltage drop during the aging process, the smaller the internal ac resistance of the cell.
  5. 5. The method of claim 1, wherein the voltage drop during the aging process is substantially similar and the ac internal resistance of the cells is substantially uniform.
  6. 6. The method of claim 1, wherein the battery cell comprises a lithium ion battery cell or a sodium ion battery cell.
  7. 7. The use of the judgment method of any one of claims 1 to 6 in battery packs.
  8. 8. The method for matching the battery cells is characterized in that the method for judging the AC internal resistance of the battery cells is adopted, and the battery cells with high consistency of the AC internal resistance are selected for matching.

Description

Method for judging alternating-current internal resistance of battery cell, application of method and battery cell matching method Technical Field The invention relates to the technical field of batteries, in particular to a method for judging alternating current internal resistance of a battery cell, application of the method and a battery cell matching method. Background The internal resistance of each battery cell in the module is inconsistent and is easy to cause the increase of charge-discharge pressure difference, the module can be disabled in the past for a long time, and in order to keep the consistency of the battery resistance in the module, the control is generally carried out through ACR or ACR+DCR grading, but on the one hand, the ACR test accuracy is poor, the DCR test needs high-current discharge, the discharge time is lower, the test accuracy can be reduced if the discharge time is too long, and the production beat can be reduced. In view of this, the present invention has been made. Disclosure of Invention The first objective of the present invention is to provide a method for determining ac internal resistance of a battery cell, so as to solve the above technical problems. A second object of the present invention is to provide an application of the above-mentioned determination method in a battery pack. The third objective of the present invention is to provide a method for assembling battery cells. In order to achieve the above object, the following technical scheme is adopted: The invention provides a method for judging the alternating-current internal resistance of a battery cell, which comprises the steps of pre-charging the battery cell after liquid injection, and then aging the pre-charged battery cell, wherein the larger the voltage reduction amplitude is during aging, the larger the alternating-current internal resistance of the battery cell is; The pre-charging comprises the following steps: S1.0.02C-0.1C constant current charging for 5-10 min; S2.0.02C-0.1C constant current is discharged to 0 SOC, and the mixture is placed for 2-5 min; S3.0.02C-0.1C constant current charging for 5-10 min; repeating the steps S2 and S3 for 0-3 times; The battery cell is prepared by adopting the same process. As a further technical scheme, the battery cells are pre-charged in a temperature environment of 25-45 ℃. As a further technical scheme, the temperature of the aging treatment is 25-45 ℃; the aging treatment time is 5-48 h. As a further technical scheme, the smaller the voltage reduction amplitude is during aging treatment, the smaller the alternating current internal resistance of the battery cell is; as a further technical scheme, the voltage reduction amplitude is similar in the aging treatment period, and the consistency of the alternating current internal resistance of the battery cell is high. As a further technical scheme, the battery cell comprises a lithium ion battery cell and a sodium ion battery cell. In a second aspect, the present invention provides an application of the above-mentioned determination method in battery packs. In a third aspect, the invention provides a method for matching battery cells, which adopts the above method for judging the ac internal resistance of the battery cells, and selects the battery cells with high ac internal resistance consistency for matching. Compared with the prior art, the invention has the following beneficial effects: According to the method for judging the alternating current internal resistance of the battery cell, provided by the invention, the internal resistance of the battery cell is judged by adding the pre-charging process and monitoring the voltage change condition after aging, the method is simple and efficient, and the judgment of the alternating current internal resistance of the battery cell can be accurately realized, so that the method is applied to the matching of the battery cells. Drawings In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art. FIG. 1 is an aging curve of example 1; FIG. 2 is an aging curve of example 2. Detailed Description Embodiments of the present invention will be described in detail below with reference to embodiments and examples, but it will be understood by those skilled in the art that the following embodiments and examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are inte