CN-116713211-B - Method, device, equipment and storage medium for screening battery cells

CN116713211BCN 116713211 BCN116713211 BCN 116713211BCN-116713211-B

Abstract

The application provides a method, a device, equipment and a storage medium for screening electric cores, which comprise the steps of S10, carrying out primary screening on the electric cores in the same batch according to the formation capacity of the electric cores in the same batch to obtain primary selected electric cores, carrying out secondary screening on the primary selected electric cores according to the performance parameters of the primary selected electric cores to obtain candidate electric cores with consistent static performance, S20, carrying out charge and discharge testing on the candidate electric cores and obtaining the coulomb efficiency value of the candidate electric cores after the charge and discharge testing, and S30, carrying out consistency grouping on the candidate electric cores according to the coulomb efficiency value of the candidate electric cores to obtain shipment electric cores with consistent dynamic performance. The method can avoid the influence of the difference between the battery packs and the single battery cells on the service life and the safety of the battery, so that a user can have better experience in the use process.

Inventors

Nan Caihong
FENG LINLIN
DAI LU

Assignees

宁德新能源科技有限公司

Dates

Publication Date: 20260505
Application Date: 20230629

Claims (9)

1. A method of cell screening, the method comprising the steps of: S10, carrying out primary screening on the cells in the same batch according to the formation capacity of the cells in the same batch to obtain primary selected cells, and carrying out secondary screening on the primary selected cells according to the performance parameters of the primary selected cells to obtain candidate cells with consistent static performance; S20, performing charge and discharge tests on the candidate battery cells, and acquiring coulomb efficiency values of the candidate battery cells after the charge and discharge tests; s30, carrying out consistency grouping on the candidate battery cells according to the coulomb efficiency values of the candidate battery cells to obtain shipment battery cells with consistent dynamic performance; wherein, the step S20 includes: s202, performing a first charge-discharge test on the candidate battery cell by adopting a preset first charge-discharge strategy to adjust the SOC of the candidate battery cell to a target SOC interval corresponding to the candidate battery cell, wherein the upper limit value of the target SOC interval is smaller than a preset SOC, and the target SOC interval is a verified SOC interval without capacity loss before and after the candidate battery cell is subjected to high-rate charge-discharge, and the high-rate is larger than the charge-discharge rate which can be born by the candidate battery cell; s203, adopting a preset cyclic charge-discharge strategy in the target SOC interval, and carrying out repeated cyclic charge-discharge tests on the candidate battery cells; s204, after the cyclic charge and discharge, performing a second charge and discharge test on the candidate battery cells by adopting a preset second charge and discharge strategy, and acquiring the coulomb efficiency value of the candidate battery cells after the second charge and discharge test; And the charge-discharge multiplying power adopted in the cyclic charge-discharge test is larger than the charge-discharge multiplying power in the first charge-discharge test and the second charge-discharge test.
2. The method of claim 1, wherein the second charge and discharge test comprises a second charge test and a second discharge test, the obtaining the coulombic efficiency values of the plurality of candidate cells after the second charge and discharge test comprising: measuring the capacity of the battery cell when the SOC of the candidate battery cell is regulated to the target SOC interval to obtain a first capacity; in the second charge and discharge test, measuring the capacity of the battery cell of the candidate battery cell after the second charge test to obtain a second capacity, and measuring the capacity of the battery cell of the candidate battery cell after the second discharge test to obtain a third capacity; and acquiring the coulomb efficiency value of the candidate battery cell according to the first capacity, the second capacity and the third capacity.
3. The method according to claim 1, characterized in that before said step S202, said method further comprises the step of: s200, performing full charge test on the candidate battery cells to obtain actual SOC (state of charge) when the candidate battery cells are fully charged; s201, determining a target SOC section corresponding to the candidate battery cell according to the actual SOC of the candidate battery cell; wherein the lower limit value of the target SOC section is greater than or equal to 10% of the actual SOC, and the upper limit value of the target SOC section is less than or equal to 30% of the actual SOC.
4. The method of claim 1, wherein the obtaining the coulombic efficiency value of the candidate cell after the second charge-discharge test comprises: Screening out candidate cells with lossless capacity from the candidate cells after the second charge and discharge test; obtaining the coulomb efficiency value of the candidate battery cell with lossless capacity in the candidate battery cell; the step S30 includes: and carrying out consistency grouping on the candidate battery cells with lossless capacity according to the coulomb efficiency values of the candidate battery cells with lossless capacity in the candidate battery cells to obtain shipment battery cells with consistent dynamic performance.
5. The method of claim 4, wherein screening out candidate cells with lossless capacity among the candidate cells after the second charge-discharge test comprises: Performing charge and discharge testing on the candidate battery cells at a first testing time by adopting a preset third charge and discharge strategy to obtain first testing data, and acquiring a first dv/dq curve of the candidate battery cells according to the first testing data, and/or testing at the first testing time to obtain a first electrochemical impedance spectrum of the candidate battery cells, wherein the first testing time is before the cyclic charge and discharge testing; at a second test time, carrying out charge and discharge testing on the candidate battery cells by adopting the third charge and discharge strategy to obtain second test data, and obtaining a second dv/dq curve of the candidate battery cells according to the second test data, and/or testing at the second test time to obtain a second electrochemical impedance spectrum of the candidate battery cells, wherein the second test time is after the cyclic charge and discharge testing; and screening candidate cells with lossless capacity in the candidate cells according to the first dv/dq curve and the second dv/dq curve, and/or screening candidate cells with lossless capacity in the candidate cells according to the first electrochemical impedance spectrum and the second electrochemical impedance spectrum.
6. The method according to any one of claims 1 to 5, wherein the step S30 comprises: calculating the average value of the coulomb efficiency values of the candidate battery cells, and calculating the deviation value of the coulomb efficiency values of the candidate battery cells and the average value; And carrying out consistency grouping on the candidate battery cells according to the deviation values to obtain shipment battery cells with consistent dynamic performance, wherein the deviation value of the coulomb efficiency value of the shipment battery cells with consistent dynamic performance and the average value is smaller than a preset deviation value.
7. A device for cell screening, the device comprising: The screening module is used for carrying out primary screening on the cells in the same batch according to the formation capacity of the cells in the same batch to obtain primary selected cells, and carrying out secondary screening on the primary selected cells according to the performance parameters of the primary selected cells to obtain candidate cells with consistent static performance; The acquisition module is used for carrying out charge and discharge tests on the candidate battery cells and acquiring coulomb efficiency values of the candidate battery cells after the charge and discharge tests; The grouping module is used for carrying out consistency grouping on the candidate battery cells according to the coulomb efficiency values of the candidate battery cells to obtain shipment battery cells with consistent dynamic performance; The acquisition module is specifically configured to perform a first charge-discharge test on the candidate battery cell by using a preset first charge-discharge strategy, so as to adjust the SOC of the candidate battery cell to a target SOC interval corresponding to the candidate battery cell, wherein an upper limit value of the target SOC interval is smaller than a preset SOC, the target SOC interval is an authenticated SOC interval with no capacity loss before and after performing high-rate charge-discharge on the candidate battery cell, the high-rate is larger than a charge-discharge rate that the candidate battery cell can withstand, perform a multiple-cycle charge-discharge test on the candidate battery cell by using a preset cycle charge-discharge strategy in the target SOC interval, perform a second charge-discharge test on the candidate battery cell by using a preset second charge-discharge strategy after the cycle charge-discharge, and acquire a coulombic efficiency value of the candidate battery cell after the second charge-discharge test.
8. An electronic device, the electronic device comprising: A memory for storing executable program code; A processor for calling and running the executable program code from the memory, causing the electronic device to perform the method of any one of claims 1 to 6.
9. A computer readable storage medium, characterized in that the computer readable storage medium stores a computer program which, when executed, implements the method according to any of claims 1 to 6.

Description

Method, device, equipment and storage medium for screening battery cells Technical Field The present application relates to the field of battery technologies, and in particular, to a method, an apparatus, a device, and a storage medium for cell screening in the field of battery technologies. Background The lithium ion battery has the advantages of higher energy density, longer life cycle, lower self-discharge, small environmental pollution and the like, and becomes a main power source of digital products. Because of process fluctuation, even if the same batch of battery cells are different, if the battery cells are randomly matched without screening, the difference can seriously reduce the service life of the whole battery pack, so that the batteries are required to be screened for consistency. At present, battery sorting technology mostly uses characteristic parameters such as capacity, voltage, internal resistance, self-discharge rate and the like as indexes to screen, but the parameters can only ensure the consistency of the battery cells in a static state, can not reflect the consistency of the battery in the use process, have deviation in the performance judgment of the battery, influence the service life and the safety of the battery due to the difference between single battery cells in the use process of the battery pack, and further cause poor experience in the use process of a user. Therefore, how to avoid the battery pack from influencing the service life and the safety of the battery due to the difference between the single cells is a technical problem to be solved. Disclosure of Invention The application provides a method, a device, equipment and a storage medium for screening battery cells, which can prevent the service life and the safety of a battery from being influenced by the difference between single battery cells of a battery pack, so that a user can have better experience in the use process. The method comprises the steps of S10, carrying out primary screening on the cells in the same batch according to formation capacity of the cells in the same batch to obtain primary selected cells, carrying out secondary screening on the primary selected cells according to performance parameters of the primary selected cells to obtain candidate cells with consistent static performance, S20, carrying out charge and discharge testing on the candidate cells to obtain coulomb efficiency values of the candidate cells after the charge and discharge testing, and S30, carrying out consistency grouping on the candidate cells according to the coulomb efficiency values of the candidate cells to obtain shipment cells with consistent dynamic performance. In the technical scheme, after candidate cells with consistent static performance are screened out from the cells in the same batch, the candidate cells are subjected to charge and discharge test to obtain the coulomb efficiency value of the candidate cells, and finally, further dynamic consistency grouping is carried out based on the coulomb efficiency value. The consistency of the battery in the use process can be reflected by the coulomb efficiency value, so that the candidate battery cells are subjected to consistency grouping based on the coulomb efficiency value, the consistency of the dynamic performance of the shipment battery cells is improved, the service life and the safety of the battery are prevented from being influenced by the difference between the single battery cells due to the battery pack, and a user can have better experience in the use process. In the technical scheme, the formation capacity and the performance parameters can reflect the static characteristics of the battery cells, so that the candidate battery cells with consistent static performance can be reasonably and accurately obtained through primary screening based on the formation capacity and secondary screening based on the performance parameters. In combination with the first aspect, in some possible implementation manners, the step S20 includes performing a first charge-discharge test on the candidate battery cell by using a preset first charge-discharge strategy to adjust the SOC of the candidate battery cell to a target SOC interval corresponding to the candidate battery cell, where an upper limit value of the target SOC interval is smaller than a preset SOC, performing a multiple-cycle charge-discharge test on the candidate battery cell by using a preset cycle charge-discharge strategy in the target SOC interval, and performing a second charge-discharge test on the candidate battery cell by using a preset second charge-discharge strategy after the cycle charge-discharge, and obtaining a coulomb efficiency value of the candidate battery cell after the second charge-discharge test, where a charge-discharge rate used in the cycle charge-discharge test is greater than a charge-discharge rate used in the first charge-discharge test and the second charge-discharge test. In the te