Battery cell stress-strain relationship determination method, device, and medium

Abstract

The application discloses a kind of electric core stress strain relationship determination method, device and medium, method includes: obtaining the first corresponding relationship between the absolute thickness of electric core under zero pressure and the residual capacity of electric core, and obtaining the multiple second corresponding relationship between the absolute thickness of electric core under multiple pressures and the residual capacity of electric core, pressure and second corresponding relationship one to one correspondence;From the first corresponding relationship, the first absolute thickness corresponding to target residual capacity is obtained, and the second absolute thickness corresponding to target residual capacity is obtained from each second corresponding relationship;According to first absolute thickness and multiple second absolute thickness, the strain of electric core under each pressure is obtained;According to multiple pressures, and the stress strain relationship of electric core under target residual capacity is obtained under each pressure strain.The stress strain relationship of electric core under target residual capacity can be obtained in the embodiment of the application, and the stress deformation ability of electric core is analyzed.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method, apparatus and medium for determining the stress-strain relationship of a battery cell. Background Technology

[0002] During the use of a battery cell, expansion forces are generated. Under the action of these expansion forces, the positive and negative electrode plates will deform, leading to problems such as reduced porosity and deterioration of liquid phase transport dynamics. Stress-strain curves are usually used to characterize the deformation capacity of a battery cell under stress. Currently, there is an urgent need for a method to determine the stress-strain relationship of the battery cell. Summary of the Invention

[0003] This application provides a method, apparatus, and medium for determining the stress-strain relationship of a battery cell, which is used to determine the strain of the battery cell under different stresses, facilitating the analysis of the battery cell's ability to deform under stress.

[0004] In a first aspect, this application provides a method for determining the stress-strain relationship of a battery cell, including:

[0005] A first correspondence is obtained between the absolute thickness of the battery cell under zero pressure and the remaining charge of the battery cell, and multiple second correspondences are obtained between the absolute thickness of the battery cell under multiple pressures and the remaining charge of the battery cell, wherein the pressures correspond one-to-one with the second correspondences.

[0006] Obtain the first absolute thickness corresponding to the target remaining power from the first correspondence, and obtain the second absolute thickness corresponding to the target remaining power from each of the second correspondences;

[0007] The strain of the battery cell under each pressure is obtained based on the first absolute thickness and a plurality of second absolute thicknesses;

[0008] Based on the multiple pressures and the strain under each pressure, the stress-strain relationship of the battery cell under the target remaining charge is obtained.

[0009] In this embodiment, the stress-strain relationship of the battery cell under the target remaining charge can be obtained. Through this relationship, the strain of the battery cell under different stresses can be obtained. The deformation of the battery cell can be obtained based on the strain. The stress on the battery cell can also be inferred from the deformation of the battery cell, thereby realizing the analysis of the deformation and stress of the battery cell.

[0010] In one embodiment of this application, obtaining multiple second correspondences between the absolute thickness of the battery cell under multiple pressures and the remaining charge of the battery cell includes:

[0011] When the battery cell is subjected to a first pressure, multiple data pairs obtained during the charging and discharging process of the battery cell are acquired. Each data pair includes the remaining charge of the battery cell and the absolute thickness of the battery cell under the first pressure. The remaining charge in each data pair is different, and the first pressure is any one of the multiple pressures.

[0012] By performing data fitting on multiple data pairs, a second correspondence relationship corresponding to the first pressure is obtained.

[0013] In this embodiment of the application, a limited number of data pairs can be fitted to obtain a second correspondence relationship corresponding to the first pressure, thereby improving the efficiency of obtaining the second correspondence relationship and facilitating the subsequent acquisition of the stress-strain relationship of the battery cell under the target remaining charge based on the second correspondence relationship.

[0014] In one embodiment of this application, when the battery cell is subjected to a first pressure, multiple data pairs obtained during the charging and discharging process of the battery cell are acquired, including:

[0015] A first pressure is applied to the battery cell and it is left to stand for a preset time;

[0016] The battery cell is charged and discharged to obtain multiple data pairs.

[0017] In this embodiment, after applying a first pressure to the battery cell, it is left to stand for a preset time so that the effect of creep on the thickness of the battery cell under the first pressure tends to stabilize, thereby making the absolute thickness of the battery cell under the first pressure more accurate.

[0018] In one embodiment of this application, the battery cell is charged and discharged to obtain multiple data pairs, including:

[0019] The battery cell undergoes its first charge-discharge process.

[0020] During the second charge and discharge process of the battery cell, multiple absolute thicknesses corresponding to multiple different remaining charges of the battery cell are obtained, and the multiple remaining charges correspond one-to-one with the multiple absolute thicknesses;

[0021] Based on the multiple remaining battery power and the multiple absolute thicknesses, multiple data pairs are obtained.

[0022] In this embodiment, performing a first charge-discharge process on the battery cell can stabilize the thickness expansion of the battery cell during the second charge-discharge process, thereby making the absolute thickness of the battery cell obtained under the first pressure more accurate.

[0023] In one embodiment of this application, the absolute thickness of the battery cell under the first pressure is the sum of the absolute thickness of the battery cell under zero pressure, the creep thickness, and the expansion thickness, wherein the creep thickness is the amount of thickness change of the battery cell when the first pressure is applied, and the expansion thickness is the amount of thickness expansion of the battery cell when the battery cell is charged and discharged.

[0024] In this embodiment of the application, when determining the absolute thickness of the battery cell under the first pressure, creep thickness and expansion thickness are added. The influence of battery cell creep on the change of absolute thickness of the battery cell, as well as the influence of battery cell charging and discharging on the change of absolute thickness of the battery cell, are taken into account, which can improve the accuracy of the calculation of the absolute thickness of the battery cell under the first pressure.

[0025] In one embodiment of this application, the strain of the battery cell under each pressure is obtained based on the first absolute thickness and a plurality of second absolute thicknesses, including:

[0026] Obtain the difference between the second absolute thickness corresponding to the second pressure and the first absolute thickness, wherein the second pressure is any one of the plurality of pressures;

[0027] Based on the difference and the first absolute thickness, the strain of the battery cell under the second pressure is calculated.

[0028] In this embodiment of the application, the strain of the battery cell under each pressure is obtained by using the first absolute thickness and multiple second absolute thicknesses, which facilitates the subsequent determination of the stress-strain relationship.

[0029] In one embodiment of this application, the stress-strain relationship of the battery cell under the target remaining charge is obtained based on the plurality of pressures and the strain under each pressure, including:

[0030] The stress corresponding to the third pressure is obtained based on the third pressure and the force area of ​​the cell when the third pressure is applied. The third pressure is any one of the multiple pressures.

[0031] Using the stress corresponding to each of the third pressures as the first coordinate axis and the strain corresponding to the third pressures as the second coordinate axis, a curve is obtained to characterize the stress-strain relationship of the battery cell under the target remaining charge.

[0032] In this embodiment, a curve characterizing the stress-strain relationship of the battery cell under the target remaining charge can be obtained. Through this curve, the strain of the battery cell under different stresses can be obtained. The deformation of the battery cell can be obtained based on the strain. The stress on the battery cell can also be inferred from the deformation of the battery cell, thereby realizing the analysis of the deformation and stress of the battery cell.

[0033] Secondly, embodiments of this application provide a device for determining the stress-strain relationship of a battery cell, comprising:

[0034] The first acquisition module is used to acquire a first correspondence between the absolute thickness of the battery cell under zero pressure and the remaining charge of the battery cell;

[0035] The second acquisition module is used to establish multiple second correspondences between the absolute thickness of the battery cell under multiple pressures and the remaining charge of the battery cell, wherein the pressures correspond one-to-one with the second correspondences.

[0036] The third acquisition module is used to acquire the first absolute thickness corresponding to the target remaining power from the first correspondence relationship, and to acquire the second absolute thickness corresponding to the target remaining power from each of the second correspondence relationships;

[0037] The fourth acquisition module is used to obtain the strain of the battery cell under each pressure based on the first absolute thickness and a plurality of second absolute thicknesses;

[0038] The fifth acquisition module is used to obtain the stress-strain relationship of the battery cell under the target remaining charge based on the multiple pressures and the strain under each pressure.

[0039] In this embodiment, the stress-strain relationship of the battery cell under the target remaining charge can be obtained. Through this relationship, the strain of the battery cell under different stresses can be obtained. The deformation of the battery cell can be obtained based on the strain. The stress on the battery cell can also be inferred from the deformation of the battery cell, thereby realizing the analysis of the deformation and stress of the battery cell.

[0040] In one embodiment of this application, the second acquisition module includes:

[0041] The first acquisition submodule is used to acquire multiple data pairs obtained during the charging and discharging process of the battery cell when the battery cell is subjected to a first pressure. Each data pair includes the remaining charge of the battery cell and the absolute thickness of the battery cell under the first pressure. The remaining charge in each data pair is different. The first pressure is any one of the multiple pressures.

[0042] The fitting submodule is used to perform data fitting on multiple data pairs to obtain a second correspondence relationship corresponding to the first pressure.

[0043] In this embodiment of the application, a limited number of data pairs can be fitted to obtain a second correspondence relationship corresponding to the first pressure, thereby improving the efficiency of obtaining the second correspondence relationship and facilitating the subsequent acquisition of the stress-strain relationship of the battery cell under the target remaining charge based on the second correspondence relationship.

[0044] In one embodiment of this application, the first acquisition submodule includes:

[0045] The first unit is used to apply a first pressure to the battery cell and leave it stationary for a preset time.

[0046] The second unit is used to charge and discharge the battery cell to obtain multiple data pairs.

[0047] In this embodiment, after applying a first pressure to the battery cell, it is left to stand for a preset time so that the effect of creep on the thickness of the battery cell under the first pressure tends to stabilize, thereby making the absolute thickness of the battery cell under the first pressure more accurate.

[0048] In one embodiment of this application, the second unit includes:

[0049] The first sub-unit is used to perform the first charge and discharge process on the battery cell;

[0050] The second subunit is used to obtain multiple absolute thicknesses corresponding to multiple different remaining charges of the battery cell during the second charge and discharge process of the battery cell, with each of the multiple remaining charges corresponding to a single absolute thickness.

[0051] The acquisition sub-unit is used to obtain multiple data pairs based on the multiple remaining power and the multiple absolute thicknesses.

[0052] In this embodiment, performing a first charge-discharge process on the battery cell can stabilize the thickness expansion of the battery cell during the second charge-discharge process, thereby making the absolute thickness of the battery cell obtained under the first pressure more accurate.

[0053] In one embodiment of this application, the absolute thickness of the battery cell under the first pressure is the sum of the absolute thickness of the battery cell under zero pressure, the creep thickness, and the expansion thickness, wherein the creep thickness is the amount of thickness change of the battery cell when the first pressure is applied, and the expansion thickness is the amount of thickness expansion of the battery cell when the battery cell is charged and discharged.

[0054] In this embodiment of the application, when determining the absolute thickness of the battery cell under the first pressure, creep thickness and expansion thickness are added. The influence of battery cell creep on the change of absolute thickness of the battery cell, as well as the influence of battery cell charging and discharging on the change of absolute thickness of the battery cell, are taken into account, which can improve the accuracy of the calculation of the absolute thickness of the battery cell under the first pressure.

[0055] In one embodiment of this application, the fourth acquisition module includes:

[0056] The second acquisition submodule is used to acquire the difference between the second absolute thickness corresponding to the second pressure and the first absolute thickness, wherein the second pressure is any one of the plurality of pressures;

[0057] The third acquisition submodule is used to calculate the strain of the battery cell under the second pressure based on the difference and the first absolute thickness.

[0058] In this embodiment of the application, the strain of the battery cell under each pressure is obtained by using the first absolute thickness and multiple second absolute thicknesses, which facilitates the subsequent determination of the stress-strain relationship.

[0059] In one embodiment of this application, the fifth acquisition module includes:

[0060] The fourth acquisition submodule is used to obtain the stress corresponding to the third pressure based on the third pressure and the force area of ​​the battery cell when the third pressure is applied, wherein the third pressure is any one of the multiple pressures;

[0061] The fifth acquisition submodule is used to obtain a curve characterizing the stress-strain relationship of the battery cell under the target remaining charge, with the stress corresponding to each of the third pressures as the first coordinate axis and the strain corresponding to the third pressures as the second coordinate axis.

[0062] In this embodiment, a curve characterizing the stress-strain relationship of the battery cell under the target remaining charge can be obtained. Through this curve, the strain of the battery cell under different stresses can be obtained. The deformation of the battery cell can be obtained based on the strain. The stress on the battery cell can also be inferred from the deformation of the battery cell, thereby realizing the analysis of the deformation and stress of the battery cell.

[0063] Thirdly, embodiments of this application provide a readable storage medium storing a program or instructions that, when executed by a processor, implement the steps of the cell stress-strain relationship determination method as described in the first aspect.

[0064] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0065] The features, advantages, and technical effects of exemplary embodiments of this application will now be described with reference to the accompanying drawings.

[0066] Figure 1 A schematic flowchart illustrating the method for determining the stress-strain relationship of a battery cell provided in an embodiment of this application;

[0067] Figure 2 A schematic diagram of the absolute thickness curves of the battery cell under multiple pressures, provided in an embodiment of this application.

[0068] Figure 3 A schematic diagram of the thickness expansion curve of the battery cell during charging and discharging, provided for an embodiment of this application;

[0069] Figure 4 A schematic diagram of the stress-strain curve of a battery cell at 50% SOC, provided for an embodiment of this application;

[0070] Figure 5 A schematic diagram of the structure of the battery cell stress-strain relationship determination device provided in the embodiments of this application. Detailed Implementation

[0071] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0072] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0073] The following will provide a detailed description of the method, apparatus, and medium for determining the stress-strain relationship of the battery cell provided in the embodiments of this application, with reference to the accompanying drawings.

[0074] Figure 1 A flowchart illustrating a method for determining the stress-strain relationship of a battery cell, as provided in an embodiment of this application, is shown below. Figure 1 As shown, the method includes steps 101-104, wherein:

[0075] Step 101: Obtain a first correspondence between the absolute thickness of the battery cell under zero pressure and the remaining charge of the battery cell, and a plurality of second correspondences between the absolute thickness of the battery cell under multiple pressures and the remaining charge of the battery cell, wherein the pressures correspond one-to-one with the second correspondences.

[0076] The primary correspondence can be determined based on the multiple remaining capacities of the battery cell and the absolute thickness of the cell corresponding to each remaining capacity under zero pressure. This primary correspondence can be represented by a curve. The multiple remaining capacities can be 10%, 20%, 50%, 80%, etc., and are not limited here. It should be noted that the absolute thickness of the cell corresponding to each remaining capacity under zero pressure can be obtained through measurement or calculation. Figure 2 As shown in the figure, the curve corresponding to 0MPa is the first correspondence, which includes the total SOC of the cell and the absolute thickness of the cell at zero pressure for each SOC.

[0077] There are multiple second correspondences. Applying a certain pressure to the battery cell and obtaining the correspondence between the absolute thickness of the cell under that pressure and the remaining charge of the cell is the second correspondence for that pressure. For example, for any one of the multiple pressures (first pressure), the second correspondence can also be determined based on the multiple remaining charges of the battery cell and the absolute thickness of the cell under the first pressure corresponding to each remaining charge. The second correspondence can also be represented by a curve.

[0078] like Figure 2 As shown in the figure, multiple curves are included. The curve representing 0 MPa represents the first correspondence, while the curves representing 1 MPa, 2 MPa, and 4 MPa represent the second correspondences of the battery cell under different pressures. Each second correspondence can include the total state of charge (SOC) of the battery cell, as well as the absolute thickness of the battery cell at a certain pressure corresponding to each SOC.

[0079] Step 102: Obtain the first absolute thickness corresponding to the target remaining power from the first correspondence, and obtain the second absolute thickness corresponding to the target remaining power from each of the second correspondences.

[0080] The target remaining battery capacity can be selected based on actual conditions and is not limited here. The first absolute thickness of the battery cell under zero pressure corresponding to the target remaining battery capacity can be obtained from the first correspondence.

[0081] Similarly, the second absolute thickness of the battery cell corresponding to the target remaining power under the first pressure can be obtained from the second correspondence.

[0082] Step 103: Based on the first absolute thickness and a plurality of second absolute thicknesses, obtain the strain of the battery cell under each pressure.

[0083] For each pressure, the strain of the cell under that pressure can be calculated based on the first absolute thickness and the second absolute thickness corresponding to that pressure.

[0084] Step 104: Based on the multiple pressures and the strain under each pressure, obtain the stress-strain relationship of the battery cell under the target remaining charge.

[0085] For each pressure, the stress under that pressure can be calculated. For example, dividing the pressure by the area of ​​the cell subjected to the force yields the stress. Based on multiple stresses and the corresponding strain for each stress, the stress-strain relationship is obtained. For instance, by performing curve fitting on multiple stresses and the corresponding strain for each stress, the stress-strain relationship of the cell under the target remaining charge can be obtained.

[0086] Through the above steps, the stress-strain relationship of the battery cell under the target remaining charge can be obtained. Through this relationship, the strain of the battery cell under different stresses can be obtained. Based on the strain, the deformation of the battery cell can be obtained. Alternatively, the stress on the battery cell can be inferred from the deformation of the battery cell, thereby enabling the analysis of the deformation and stress of the battery cell.

[0087] In one embodiment of this application, obtaining multiple second correspondences between the absolute thickness of the battery cell under multiple pressures and the remaining charge of the battery cell includes:

[0088] When the battery cell is subjected to a first pressure, multiple data pairs obtained during the charging and discharging process of the battery cell are acquired. Each data pair includes the remaining charge of the battery cell and the absolute thickness of the battery cell under the first pressure. The remaining charge in each data pair is different, and the first pressure is any one of the multiple pressures.

[0089] By performing data fitting on multiple data pairs, a second correspondence relationship corresponding to the first pressure is obtained.

[0090] In the above, charge and discharge tests were conducted on the battery cells under different pressures with different remaining charge levels, and the data pairs between the absolute thickness of the battery cell and the remaining charge level were recorded at each pressure.

[0091] For ease of description, any one of the multiple pressures is referred to as the first pressure. When the cell is subjected to the first pressure, multiple data pairs obtained during the cell's charging and discharging process are acquired. Each data pair includes a remaining charge of the cell and the absolute thickness of the cell under the first pressure at that remaining charge. The remaining charge of the cell included in each data pair is different.

[0092] Data fitting is performed on multiple data pairs. For example, the remaining charge of the battery cell is used as the abscissa of a rectangular coordinate system, and the absolute thickness under the first pressure is used as the ordinate of a rectangular coordinate system. The points formed by the multiple data pairs on the rectangular coordinate system are fitted to obtain a fitting curve. This fitting curve is the second correspondence corresponding to the first pressure.

[0093] For each pressure, the above processing is performed to obtain the second correspondence for each pressure.

[0094] In this embodiment of the application, a limited number of data pairs can be fitted to obtain a second correspondence relationship corresponding to the first pressure, thereby improving the efficiency of obtaining the second correspondence relationship and facilitating the subsequent acquisition of the stress-strain relationship of the battery cell under the target remaining charge based on the second correspondence relationship.

[0095] It should be noted that when obtaining the first correspondence, the method of obtaining the second correspondence can also be used. For example, when the battery cell is under zero pressure, multiple data pairs obtained during the charging and discharging process of the battery cell can be obtained. Each data pair includes a remaining charge of the battery cell and the absolute thickness of the battery cell under zero pressure with that remaining charge. The remaining charge of the battery cell included in each data pair is different.

[0096] In another embodiment of this application, when the battery cell is subjected to a first pressure, multiple data pairs obtained during the charging and discharging process of the battery cell are acquired, including:

[0097] A first pressure is applied to the battery cell and it is left to stand for a preset time;

[0098] The battery cell is charged and discharged to obtain multiple data pairs.

[0099] The preset duration can be set according to the actual situation, such as 1 hour or 2 hours, etc., without limitation.

[0100] During the charging and discharging process of the battery cell, multiple absolute thicknesses corresponding to different remaining capacities can be obtained, with each remaining capacities corresponding one-to-one with a specific absolute thickness. Based on the multiple remaining capacities and the multiple absolute thicknesses, multiple data pairs are obtained. A single remaining capacity and its corresponding absolute thickness constitute a data pair.

[0101] In the above, after applying the first pressure to the battery cell, it is left to stand for a preset time so that the effect of the creep of the battery cell under the first pressure on the thickness tends to be stable, thereby making the absolute thickness of the battery cell under the first pressure more accurate.

[0102] In one embodiment of this application, the battery cell is charged and discharged to obtain multiple data pairs, including:

[0103] The battery cell undergoes its first charge-discharge process.

[0104] During the second charge and discharge process of the battery cell, multiple absolute thicknesses corresponding to multiple different remaining charges of the battery cell are obtained, and the multiple remaining charges correspond one-to-one with the multiple absolute thicknesses;

[0105] Based on the multiple remaining battery capacity and the multiple absolute thicknesses, multiple data pairs are obtained. A remaining battery capacity and its corresponding absolute thickness constitute a data pair.

[0106] In this embodiment, an additional charge-discharge process is added to the battery cell, for example, the battery cell is subjected to two charge-discharge processes. By adding an additional charge-discharge process, the thickness expansion of the battery cell during the charge-discharge process can be stabilized, thereby making the absolute thickness of the battery cell under the first pressure more accurate. Figure 3 The figure shows the thickness expansion curve of the battery cell during the charging and discharging process. The battery cell was subjected to two charging and discharging processes in the figure.

[0107] For example, at the start of the test, an initial pressure is applied to the surface of the battery cell, which is then left to rest under this pressure for 2 hours. During this time, the cell undergoes no charging or discharging, remaining at 0% SOC (fully discharged). After the resting period, the cell is subjected to its first charge-discharge process. This process can be as follows: charge at a constant current rate of 0.33C to the upper limit voltage of the cell, then perform constant voltage charging at that voltage, with the cutoff condition being that the charging current is less than 0.05C (the upper limit voltage depends on the cell design). After resting for 5 minutes, discharge the cell at a rate of 0.33C to the lower limit voltage (the lower limit voltage depends on the cell design).

[0108] In this embodiment, performing a first charge-discharge process on the battery cell can stabilize the thickness expansion of the battery cell during the second charge-discharge process, thereby making the absolute thickness of the battery cell obtained under the first pressure more accurate.

[0109] In another embodiment of this application, the absolute thickness of the battery cell under the first pressure is the sum of the absolute thickness of the battery cell under zero pressure, the creep thickness, and the expansion thickness, wherein the creep thickness is the amount of thickness change of the battery cell when the first pressure is applied, and the expansion thickness is the amount of thickness expansion of the battery cell when the battery cell is charged and discharged.

[0110] In the above, when determining the absolute thickness of the battery cell under the first pressure, creep thickness and expansion thickness were added. The influence of cell creep on the change of absolute thickness of the battery cell, as well as the influence of cell charging and discharging on the change of absolute thickness of the battery cell, were taken into account, which can improve the accuracy of the calculation of the absolute thickness of the battery cell under the first pressure.

[0111] In one embodiment of this application, the strain of the battery cell under each pressure is obtained based on the first absolute thickness and a plurality of second absolute thicknesses, including:

[0112] Obtain the difference between the second absolute thickness corresponding to the second pressure and the first absolute thickness, wherein the second pressure is any one of the plurality of pressures;

[0113] Based on the difference and the first absolute thickness, the strain of the battery cell under the second pressure is calculated.

[0114] In the above description, the difference is the first absolute thickness minus the second absolute thickness corresponding to the second pressure, and the difference is a positive number. Dividing the difference by the first absolute thickness yields the strain of the battery cell under the second pressure.

[0115] By performing the above calculations, the strain of the battery cell with the target remaining charge under multiple pressures can be obtained.

[0116] In this embodiment, the strain of the battery cell under each pressure is obtained by using the first absolute thickness and multiple second absolute thicknesses, which facilitates the subsequent determination of the stress-strain relationship.

[0117] In another embodiment of this application, the stress-strain relationship of the battery cell under the target remaining charge is obtained based on the plurality of pressures and the strain under each pressure, including:

[0118] The stress corresponding to the third pressure is obtained based on the third pressure and the force area of ​​the cell when the third pressure is applied. The third pressure is any one of the multiple pressures.

[0119] Using the stress corresponding to each of the third pressures as the first coordinate axis and the strain corresponding to the third pressures as the second coordinate axis, a curve is obtained to characterize the stress-strain relationship of the battery cell under the target remaining charge.

[0120] In the above, the stress corresponding to the third pressure is obtained by dividing the area of ​​force application. Through this calculation method, the stress corresponding to each pressure can be obtained.

[0121] The stress corresponding to each third pressure is used as the first axis of a Cartesian coordinate system, and the strain corresponding to the third pressure is used as the second axis. The stress and strain corresponding to each pressure are converted into coordinate points on the Cartesian coordinate system. A fitting curve is obtained by fitting these coordinate points; this fitting curve is the stress-strain relationship curve of the battery cell under the target remaining charge. Figure 4 As shown in the figure, the curve in the figure is the stress-strain relationship curve of the battery cell at 50% SOC.

[0122] Through the above steps, a curve characterizing the stress-strain relationship of the battery cell under the target remaining charge can be obtained. Through this curve, the strain of the battery cell under different stresses can be obtained. Based on the strain, the deformation of the battery cell can be obtained. Alternatively, the stress on the battery cell can be inferred from the deformation of the battery cell, thereby enabling the analysis of the deformation and stress of the battery cell.

[0123] Please see Figure 5 This is a schematic diagram of the structure of the battery cell stress-strain relationship determination device provided in the embodiments of this application, as shown below. Figure 5 As shown, the battery cell stress-strain relationship determination device 500 includes:

[0124] The first acquisition module 501 is used to acquire a first correspondence between the absolute thickness of the battery cell under zero pressure and the remaining charge of the battery cell;

[0125] The second acquisition module 502 is used to establish multiple second correspondences between the absolute thickness of the battery cell under multiple pressures and the remaining charge of the battery cell, wherein the pressures correspond one-to-one with the second correspondences.

[0126] The third acquisition module 503 is used to acquire the first absolute thickness corresponding to the target remaining power from the first correspondence relationship, and to acquire the second absolute thickness corresponding to the target remaining power from each of the second correspondence relationships;

[0127] The fourth acquisition module 504 is used to obtain the strain of the battery cell under each pressure based on the first absolute thickness and a plurality of second absolute thicknesses;

[0128] The fifth acquisition module 505 is used to obtain the stress-strain relationship of the battery cell under the target remaining charge based on the multiple pressures and the strain under each pressure.

[0129] In this embodiment, the stress-strain relationship of the battery cell under the target remaining charge can be obtained. Through this relationship, the strain of the battery cell under different stresses can be obtained. The deformation of the battery cell can be obtained based on the strain. The stress on the battery cell can also be inferred from the deformation of the battery cell, thereby realizing the analysis of the deformation and stress of the battery cell.

[0130] In one embodiment of this application, the second acquisition module 502 includes:

[0131] The first acquisition submodule is used to acquire multiple data pairs obtained during the charging and discharging process of the battery cell when the battery cell is subjected to a first pressure. Each data pair includes the remaining charge of the battery cell and the absolute thickness of the battery cell under the first pressure. The remaining charge in each data pair is different. The first pressure is any one of the multiple pressures.

[0132] The fitting submodule is used to perform data fitting on multiple data pairs to obtain a second correspondence relationship corresponding to the first pressure.

[0133] In this embodiment of the application, a limited number of data pairs can be fitted to obtain a second correspondence relationship corresponding to the first pressure, thereby improving the efficiency of obtaining the second correspondence relationship and facilitating the subsequent acquisition of the stress-strain relationship of the battery cell under the target remaining charge based on the second correspondence relationship.

[0134] In one embodiment of this application, the first acquisition submodule includes:

[0135] The first unit is used to apply a first pressure to the battery cell and leave it stationary for a preset time.

[0136] The second unit is used to charge and discharge the battery cell to obtain multiple data pairs.

[0137] In this embodiment, after applying a first pressure to the battery cell, it is left to stand for a preset time so that the effect of creep on the thickness of the battery cell under the first pressure tends to stabilize, thereby making the absolute thickness of the battery cell under the first pressure more accurate.

[0138] In one embodiment of this application, the second unit includes:

[0139] The first sub-unit is used to perform the first charge and discharge process on the battery cell;

[0140] The second subunit is used to obtain multiple absolute thicknesses corresponding to multiple different remaining charges of the battery cell during the second charge and discharge process of the battery cell, with each of the multiple remaining charges corresponding to a single absolute thickness.

[0141] The acquisition sub-unit is used to obtain multiple data pairs based on the multiple remaining power and the multiple absolute thicknesses.

[0142] In this embodiment, performing a first charge-discharge process on the battery cell can stabilize the thickness expansion of the battery cell during the second charge-discharge process, thereby making the absolute thickness of the battery cell obtained under the first pressure more accurate.

[0143] In one embodiment of this application, the absolute thickness of the battery cell under the first pressure is the sum of the absolute thickness of the battery cell under zero pressure, the creep thickness, and the expansion thickness, wherein the creep thickness is the amount of thickness change of the battery cell when the first pressure is applied, and the expansion thickness is the amount of thickness expansion of the battery cell when the battery cell is charged and discharged.

[0144] In this embodiment of the application, when determining the absolute thickness of the battery cell under the first pressure, creep thickness and expansion thickness are added. The influence of battery cell creep on the change of absolute thickness of the battery cell, as well as the influence of battery cell charging and discharging on the change of absolute thickness of the battery cell, are taken into account, which can improve the accuracy of the calculation of the absolute thickness of the battery cell under the first pressure.

[0145] In one embodiment of this application, the fourth acquisition module 504 includes:

[0146] The second acquisition submodule is used to acquire the difference between the second absolute thickness corresponding to the second pressure and the first absolute thickness, wherein the second pressure is any one of the plurality of pressures;

[0147] The third acquisition submodule is used to calculate the strain of the battery cell under the second pressure based on the difference and the first absolute thickness.

[0148] In this embodiment of the application, the strain of the battery cell under each pressure is obtained by using the first absolute thickness and multiple second absolute thicknesses, which facilitates the subsequent determination of the stress-strain relationship.

[0149] In one embodiment of this application, the fifth acquisition module 505 includes:

[0150] The fourth acquisition submodule is used to obtain the stress corresponding to the third pressure based on the third pressure and the force area of ​​the battery cell when the third pressure is applied, wherein the third pressure is any one of the multiple pressures;

[0151] The fifth acquisition submodule is used to obtain a curve characterizing the stress-strain relationship of the battery cell under the target remaining charge, with the stress corresponding to each of the third pressures as the first coordinate axis and the strain corresponding to the third pressures as the second coordinate axis.

[0152] In this embodiment, a curve characterizing the stress-strain relationship of the battery cell under the target remaining charge can be obtained. Through this curve, the strain of the battery cell under different stresses can be obtained. The deformation of the battery cell can be obtained based on the strain. The stress on the battery cell can also be inferred from the deformation of the battery cell, thereby realizing the analysis of the deformation and stress of the battery cell.

[0153] Alternatively, embodiments of this application can be implemented using a computer storage medium. This computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any of the cell stress-strain relationship determination methods described in the above embodiments.

[0154] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0155] The functional blocks shown in the above block diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0156] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0157] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatuses, devices, and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowchart illustrations, and combinations of blocks in the block diagrams and / or flowchart illustrations, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for determining the stress-strain relationship of a battery cell, characterized in that, include: A first correspondence is obtained between the absolute thickness of the battery cell under zero pressure and the remaining charge of the battery cell, and multiple second correspondences are obtained between the absolute thickness of the battery cell under multiple pressures and the remaining charge of the battery cell, wherein the pressures correspond one-to-one with the second correspondences. Obtain the first absolute thickness corresponding to the target remaining power from the first correspondence, and obtain the second absolute thickness corresponding to the target remaining power from each of the second correspondences; The strain of the battery cell under each pressure is obtained based on the first absolute thickness and a plurality of second absolute thicknesses; Based on the multiple pressures and the strain under each pressure, the stress-strain relationship of the battery cell under the target remaining charge is obtained; Wherein, the absolute thickness of the battery cell under the first pressure is the sum of the absolute thickness of the battery cell under zero pressure, the creep thickness, and the expansion thickness. The creep thickness is the change in thickness of the battery cell when the first pressure is applied, and the expansion thickness is the expansion of the thickness of the battery cell when it is charged and discharged. The first pressure is any one of the plurality of pressures, and the absolute thickness of the battery cell under the first pressure is obtained when the creep thickness and the expansion thickness tend to stabilize.

2. The method for determining the stress-strain relationship of a battery cell according to claim 1, characterized in that, Obtaining multiple second correspondences between the absolute thickness of the battery cell under multiple pressures and the remaining charge of the battery cell, including: When the battery cell is subjected to a first pressure, multiple data pairs obtained during the charging and discharging process of the battery cell are acquired. Each data pair includes the remaining charge of the battery cell and the absolute thickness of the battery cell under the first pressure. The remaining charge in each data pair is different. By performing data fitting on multiple data pairs, a second correspondence relationship corresponding to the first pressure is obtained.

3. The method for determining the stress-strain relationship of a battery cell according to claim 2, characterized in that, When a first pressure is applied to the battery cell, multiple data pairs obtained during the battery cell's charging and discharging process are acquired, including: A first pressure is applied to the battery cell and it is left to stand for a preset time; The battery cell is charged and discharged to obtain multiple data pairs.

4. The method for determining the stress-strain relationship of a battery cell according to claim 3, characterized in that, The battery cell is charged and discharged to obtain multiple data pairs, including: The battery cell undergoes its first charge-discharge process. During the second charge and discharge process of the battery cell, multiple absolute thicknesses corresponding to multiple different remaining charges of the battery cell are obtained, and the multiple remaining charges correspond one-to-one with the multiple absolute thicknesses; Based on the multiple remaining battery power and the multiple absolute thicknesses, multiple data pairs are obtained.

5. The method for determining the stress-strain relationship of a battery cell according to any one of claims 1-4, characterized in that, Based on the first absolute thickness and a plurality of second absolute thicknesses, the strain of the battery cell under each pressure is obtained, including: Obtain the difference between the second absolute thickness corresponding to the second pressure and the first absolute thickness, wherein the second pressure is any one of the plurality of pressures; Based on the difference and the first absolute thickness, the strain of the battery cell under the second pressure is calculated.

6. The method for determining the stress-strain relationship of a battery cell according to any one of claims 1-4, characterized in that, Based on the multiple pressures and the strain under each pressure, the stress-strain relationship of the battery cell under the target remaining charge is obtained, including: The stress corresponding to the third pressure is obtained based on the third pressure and the force area of ​​the cell when the third pressure is applied. The third pressure is any one of the multiple pressures. Using the stress corresponding to each of the third pressures as the first coordinate axis and the strain corresponding to the third pressures as the second coordinate axis, a curve is obtained to characterize the stress-strain relationship of the battery cell under the target remaining charge.

7. A device for determining the stress-strain relationship of a battery cell, characterized in that, include: The first acquisition module is used to acquire a first correspondence between the absolute thickness of the battery cell under zero pressure and the remaining charge of the battery cell; The second acquisition module is used to establish multiple second correspondences between the absolute thickness of the battery cell under multiple pressures and the remaining charge of the battery cell, wherein the pressures correspond one-to-one with the second correspondences. The third acquisition module is used to acquire the first absolute thickness corresponding to the target remaining power from the first correspondence relationship, and to acquire the second absolute thickness corresponding to the target remaining power from each of the second correspondence relationships; The fourth acquisition module is used to obtain the strain of the battery cell under each pressure based on the first absolute thickness and a plurality of second absolute thicknesses; The fifth acquisition module is used to obtain the stress-strain relationship of the battery cell under the target remaining charge based on the multiple pressures and the strain under each pressure. Wherein, the absolute thickness of the battery cell under the first pressure is the sum of the absolute thickness of the battery cell under zero pressure, the creep thickness, and the expansion thickness. The creep thickness is the change in thickness of the battery cell when the first pressure is applied, and the expansion thickness is the expansion of the thickness of the battery cell when it is charged and discharged. The first pressure is any one of the plurality of pressures, and the absolute thickness of the battery cell under the first pressure is obtained when the creep thickness and the expansion thickness tend to stabilize.

8. The device for determining the stress-strain relationship of a battery cell according to claim 7, characterized in that, The second acquisition module includes: The first acquisition submodule is used to acquire multiple data pairs obtained during the charging and discharging process of the battery cell when the battery cell is subjected to a first pressure. Each data pair includes the remaining charge of the battery cell and the absolute thickness of the battery cell under the first pressure. The remaining charge in each data pair is different. The fitting submodule is used to perform data fitting on multiple data pairs to obtain a second correspondence relationship corresponding to the first pressure.

9. A readable storage medium, characterized in that, The readable storage medium stores a program or instructions that, when executed by a processor, implement the steps of the method for determining the stress-strain relationship of a battery cell as described in any one of claims 1 to 6.

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