CN-121994651-A - Method and device for testing liquid phase diffusion coefficient of electrolyte and storage medium

CN121994651ACN 121994651 ACN121994651 ACN 121994651ACN-121994651-A

Abstract

The application discloses a liquid phase diffusion coefficient test method, a test device and a storage medium of electrolyte, wherein the liquid phase diffusion coefficient test method of the electrolyte comprises the steps of respectively charging batteries containing the electrolyte according to different charging currents, wherein two reference electrodes are arranged between a positive electrode and a negative electrode of the batteries at intervals; and determining the liquid phase diffusion coefficient of the electrolyte based on the relationship between each charging current and each potential difference. According to the scheme, the electrolyte liquid phase diffusion coefficient obtained by determination can be more accurate.

Inventors

XU LEI
Liang jinding
CHEN TINGFENG
FAN QINGWEI
WEI YIMIN

Assignees

宁德时代新能源科技股份有限公司

Dates

Publication Date: 20260508
Application Date: 20241105

Claims (12)

1. A method for testing the liquid phase diffusion coefficient of an electrolyte, the method comprising: charging batteries containing electrolyte according to different charging currents respectively, wherein two reference electrodes are arranged between the anode and the cathode of the batteries at intervals; acquiring potential differences between two reference electrodes in the battery under each charging current; a liquid phase diffusion coefficient of the electrolyte is determined based on a relationship between each of the charging currents and each of the potential differences.
2. The method of claim 1, wherein the determining a liquid phase diffusion coefficient of the electrolyte based on the relationship between each of the charging currents and each of the potential differences comprises: Fitting each charging current and each potential difference to determine an association relationship, wherein the association relationship is used for representing the correspondence relationship between different charging currents and potential differences; And determining the liquid phase diffusion coefficient of the electrolyte based on the change rate of the association relation.
3. The method according to claim 2, wherein the determining the liquid phase diffusion coefficient of the electrolyte based on the rate of change of the association relation includes: determining a positional relationship between two of the reference electrodes in the battery and state information of the battery; And determining a liquid phase diffusion coefficient of the electrolyte based on the positional relationship, the state information, and the rate of change.
4. The method according to claim 3, wherein the positional relationship includes a relative area for representing an area of projection of the other reference electrode on the plane with a side of the reference electrode facing the other reference electrode being a plane as the relative area, and a relative distance, wherein the state information of the battery includes a bulk concentration of an electrolyte and a temperature of the battery, and wherein the determining of the liquid phase diffusion coefficient of the electrolyte based on the positional relationship, the state information, and the change rate includes: Obtaining a first product between the rate of change, the bulk concentration, the relative area, and a square of a faraday constant; obtaining a second product between an ideal gas constant, the temperature, and the relative distance; and obtaining the liquid phase diffusion coefficient based on the first product and the second product.
5. The method of claim 4, wherein a diaphragm is disposed between two of the reference electrodes in the cell, the deriving the liquid phase diffusion coefficient based on the first product and the second product comprising: determining an initial liquid phase diffusion coefficient based on a ratio between the first product and the second product; And adjusting the initial liquid phase diffusion coefficient based on the porosity of the diaphragm to obtain the liquid phase diffusion coefficient.
6. The method according to any one of claims 1 to 5, wherein the correlation is a linear relationship, the fitting each of the charging currents and each of the potential differences, determining the correlation, includes: performing linear fitting on each charging current and each potential difference to obtain the linear relation; and taking the slope of the linear relation as the change rate.
7. The method according to any one of claims 1 to 6, wherein charging the battery containing the electrolyte at different charging currents, respectively, comprises: Performing a plurality of charging tests on the battery, wherein each charging test comprises a plurality of charging processes, and each charging process is performed according to the sequence of charging current from small to large or from large to small; The obtaining the potential difference between the two reference electrodes in the battery under each charging current comprises: the potential difference between the two reference electrodes is recorded in response to the potential difference between the two reference electrodes stabilizing during each charge of the battery.
8. The method of claim 7, wherein the plurality of charging tests includes a first charging test in which each charging process is performed in order of charging current from small to large, and a second charging test in which each charging process is performed in order of charging current from large to small.
9. The method of claim 8, wherein the manner in which the battery is subjected to the second charge test comprises: For each non-first charging process in the second charging test, responding to the previous charging process of the non-first charging process to record the potential difference between the two reference electrodes, and executing the non-first charging process on the battery after the battery is subjected to power-off treatment and is kept stand for a preset period of time; Wherein the charging current of the charging process preceding the non-first charging process is greater than the charging current of the non-first charging process.
10. The method according to any one of claims 1 to 9, characterized in that the method further comprises: performing charge and discharge tests on the battery; and in response to the battery reaching the test condition of the liquid phase diffusion coefficient of the electrolyte, executing the step of charging the battery containing the electrolyte according to different charging currents respectively.
11. A liquid phase diffusion coefficient testing apparatus of an electrolyte, characterized in that the testing apparatus is capable of performing the liquid phase diffusion coefficient testing method of an electrolyte according to any one of claims 1 to 10 after mating with a battery, the testing apparatus comprising: A charging assembly; the processor is in communication connection with the charging assembly, and is used for controlling the charging assembly to charge batteries containing electrolyte according to different charging currents respectively, and two reference electrodes are arranged between the anode and the cathode of the batteries at intervals; A potential difference sampling assembly in communication with the processor, the potential difference sampling assembly operable to acquire a potential difference between two of the reference electrodes in the battery at each of the charging currents and to transmit the acquired potential difference to the processor; wherein the processor is further configured to determine a liquid phase diffusion coefficient of the electrolyte based on a relationship between each of the charging currents and each of the potential differences.
12. A computer readable storage medium having stored thereon program instructions, which when executed by a processor, implement the method of testing the liquid phase diffusion coefficient of an electrolyte according to any one of claims 1 to 10.

Description

Method and device for testing liquid phase diffusion coefficient of electrolyte and storage medium Technical Field The application relates to the field of batteries, in particular to a liquid phase diffusion coefficient testing method, a testing device and a storage medium of electrolyte. Background The electrolyte is one of the important components of the battery, and the performance of the electrolyte determines the performance of the battery to a great extent. The liquid phase diffusion coefficient of the electrolyte is one of important parameters for representing the transmission performance of the lithium ion electrolyte, and the influence of the liquid phase diffusion coefficient of the electrolyte on the battery performance is quite remarkable. In the diffusion coefficient measurement process, the electrode is usually a porous electrode system, and a solid-phase diffusion process exists, which is usually coupled with a liquid-phase diffusion process in the electrolyte, so that the electrode is difficult to distinguish. At present, a constant current intermittent titration method is adopted to obtain the liquid phase diffusion coefficient of the electrolyte, but the interference of the solid phase diffusion coefficient exists in the process of obtaining the liquid phase diffusion coefficient, so that the obtained liquid phase diffusion coefficient is inaccurate. Disclosure of Invention The application provides at least a liquid phase diffusion coefficient test method, a test device and a storage medium of electrolyte. The application provides a liquid phase diffusion coefficient testing method of electrolyte, which comprises the steps of respectively charging a battery containing the electrolyte according to different charging currents, obtaining potential differences between two reference electrodes in the battery under each charging current, and determining the liquid phase diffusion coefficient of the electrolyte based on the charging currents and the relation between the potential differences. In the scheme, the concentration difference between the two reference electrodes is related to the magnitude of current and the liquid phase diffusion coefficient of electrolyte, and the potential gradient between the two reference electrodes is related to the concentration gradient between the two reference electrodes, so that the change of the potential difference between the two reference electrodes under different charging currents is observed, the liquid phase diffusion coefficient of the electrolyte can be determined, in addition, because the reference electrodes are difficult to embed ions in the charging and discharging processes of the battery, the obtained liquid phase diffusion coefficient is determined by charging the battery with the double reference electrodes according to the different charging currents and collecting the potential difference, and the obtained liquid phase diffusion coefficient is not involved in solid phase diffusion, and is more accurate compared with the current constant current intermittent titration method for measuring the liquid phase diffusion coefficient. In some embodiments, determining the liquid phase diffusion coefficient of the electrolyte based on the relationship between each charging current and each potential difference includes fitting each charging current and each potential difference, determining a relationship, the relationship being used to represent the correspondence between different charging currents and potential differences, and determining the liquid phase diffusion coefficient of the electrolyte based on the rate of change of the relationship. In the scheme, by fitting each charging current and each potential difference, the corresponding relation between different charging currents and potential differences can be obtained, In some embodiments, determining the liquid phase diffusion coefficient of the electrolyte based on the rate of change of the association includes determining a positional relationship between two reference electrodes in the cell and state information of the cell, and determining the liquid phase diffusion coefficient of the electrolyte based on the positional relationship, the state information, and the rate of change. In the above scheme, the difference of potential differences between the two reference electrodes may be caused by the different states of the battery and the different positional relationships between the two reference electrodes, and the liquid phase diffusion coefficient of the electrolyte obtained by determining the specific battery in the specific state and the combination of the change rate can be more accurate. In some embodiments, the positional relationship includes a relative area and a relative distance, the relative area being used to represent an area of a projection of the other reference electrode onto the plane with the side of the reference electrode facing the other reference electrode being