Test methods and testing apparatus for corrosion resistance of battery cells

Abstract

This application relates to a method and apparatus for testing the corrosion resistance of a battery cell. The method includes: installing a simulated battery cell casing inside a test container, wherein the test container contains a corrosive liquid for submerging at least a portion of the positive and negative simulated electrode plates of the simulated battery cell casing; electrically connecting the positive test electrode plate of the test battery cell to the positive simulated electrode plate, and electrically connecting the negative test electrode plate of the test battery cell to the negative simulated electrode plate; and electrically connecting the positive and negative simulated electrode plates to a voltage measuring device to obtain the corrosion resistance of the battery cell. By installing the simulated battery cell casing inside the test container and electrically connecting the positive and negative simulated electrode plates to the voltage measuring device, this application can utilize the uncharged simulated battery cell casing as a reaction electrode, while avoiding the influence of the corrosive liquid on the battery cell test, making the corrosion resistance test of the battery cell more accurate and improving the safety of the corrosion resistance test.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method and apparatus for testing the corrosion resistance of battery cells. Background Technology

[0002] In battery cell applications, over time, electrolyte leaks may occur, which can corrode the positive and negative terminals of the battery cell.

[0003] Currently, the immersion method, recommended by national standards, is commonly used to test the corrosion resistance of batteries before production. This method involves completely immersing the battery in a corrosive solution, testing its corrosion resistance at predetermined temperatures and for a set time. However, by completely submerging the battery cell in the corrosive solution, the intensity of the corrosion interface reaction cannot be observed. Furthermore, the voltage readings of the positive and negative electrodes on the battery cell are easily affected by the corrosive solution, leading to abnormal voltage readings. Summary of the Invention

[0004] In view of this, this application proposes a test method and device for the corrosion resistance performance of battery cells. It can use a non-charged simulated battery cell shell as a reaction electrode, while avoiding the influence of corrosive liquid on the battery cell test. This makes the corrosion resistance performance test of battery cells more accurate and improves the safety of the corrosion resistance performance test. At the same time, it is convenient to monitor the changes in battery cell voltage and the intensity of the reaction at the corrosion interface during the corrosion process. It is applicable to various types of battery cells.

[0005] In a first aspect, embodiments of this application provide a method for testing the corrosion resistance of a battery cell. The simulated battery cell casing includes a positive simulated electrode plate and a negative simulated electrode plate, and the test battery cell includes a positive test electrode plate and a negative test electrode plate. The method includes: installing the simulated battery cell casing inside a test container, wherein the test container contains a corrosive liquid for submerging at least a portion of the positive simulated electrode plate and at least a portion of the negative simulated electrode plate of the simulated battery cell casing; electrically connecting the positive test electrode plate to the positive simulated electrode plate; electrically connecting the negative test electrode plate to the negative simulated electrode plate; and electrically connecting the positive simulated electrode plate and the negative simulated electrode plate to a voltage measuring device to obtain the corrosion resistance of the test battery cell.

[0006] In one embodiment, the model number of the simulated battery cell casing is the same as that of the test battery cell casing.

[0007] In one embodiment, the corrosive liquid in the test container submerges a portion of the positive simulated electrode and a portion of the negative simulated electrode.

[0008] In one embodiment, the method for testing the corrosion resistance of the battery cell further includes: obtaining the corrosion resistance of the test battery cell through the voltage measuring device.

[0009] In one embodiment, the step of obtaining the corrosion resistance performance of the test cell through the voltage measuring device includes: obtaining multiple test voltage values ​​between the positive simulated electrode and the negative simulated electrode within a preset time range through the voltage measuring device; calculating the rate of change of the test voltage values ​​according to the relationship curve between the multiple test voltage values ​​and the test time; and determining the corrosion resistance performance of the test cell based on the rate of change of the test voltage values.

[0010] In one embodiment, after the step of obtaining the corrosion resistance performance of the test cell through the voltage measuring device, the method further includes: comparing the rate of change of the test voltage with a preset rate of change to obtain a rate of change difference; and adjusting the spacing between the positive and negative plates of other cells of the same model as the test cell according to the rate of change difference.

[0011] In one embodiment, the step of adjusting the spacing between the positive and negative plates of other cells of the same model as the test cell based on the difference in the rate of change includes: if the difference in the rate of change is greater than or equal to a rate of change threshold, increasing the spacing between the positive and negative plates of other cells of the same model as the test cell.

[0012] In one embodiment, after the step of obtaining the corrosion resistance performance of the test cell through the voltage measuring device, the method further includes: adjusting the materials of the positive and / or negative plates of other cells of the same model as the test cell according to the rate of change difference.

[0013] In one embodiment, after the step of electrically connecting the positive and negative simulated electrode plates to the voltage measuring device, the method further includes: obtaining the degree of corrosion of the simulated battery cell shell by measuring the amount of bubbles or color changes within a preset time range; and determining the corrosion resistance of the test battery cell based on the degree of corrosion.

[0014] In one embodiment, the simulated battery cell housing is a cylindrical battery cell housing, which is fixedly installed at the bottom of the test container, and the axial direction of the cylindrical battery cell housing is parallel to the bottom of the test container.

[0015] In one embodiment, the simulated battery cell casing is a square battery cell casing, which is fixed to the bottom of the test container, and the height direction of the square battery cell casing is parallel to the bottom of the test container.

[0016] Secondly, embodiments of this application provide a testing device for the corrosion resistance performance of a battery cell. The testing device includes: a simulated battery cell casing, comprising a positive simulated electrode plate and a negative simulated electrode plate, wherein the positive simulated electrode plate is electrically connected to the positive test electrode plate of the test battery cell, and the negative simulated electrode plate is electrically connected to the negative test electrode plate of the test battery cell; a testing container for containing a corrosive liquid to submerge at least a portion of the simulated battery cell casing; and a voltage measuring device for being electrically connected to the positive simulated electrode plate and the negative simulated electrode plate.

[0017] By installing a simulated battery cell casing inside a test container, allowing the corrosive liquid inside the test container to submerge at least a portion of the simulated battery cell casing, and electrically connecting the positive test electrode to the positive simulated electrode, and the negative test electrode to the negative simulated electrode, and electrically connecting the positive and negative simulated electrodes to a voltage measuring device, this invention allows the use of a non-charged simulated battery cell casing as a reaction electrode, while avoiding the influence of the corrosive liquid on the battery cell test. This makes the corrosion resistance test of the battery cell more accurate, improves the safety of the corrosion resistance test, and facilitates monitoring of changes in battery cell voltage and the intensity of the corrosion interface reaction during the corrosion process. It is applicable to various types of battery cells. Attached Figure Description

[0018] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0019] Figure 1 A flowchart illustrating a method for testing the corrosion resistance of battery cells according to an embodiment of this application is provided.

[0020] Figure 2 A schematic diagram of a square battery cell according to an embodiment of this application is shown.

[0021] Figure 3 This diagram illustrates the application of the corrosion resistance method for square battery cells according to an embodiment of this application.

[0022] Figure 4 A schematic diagram illustrating the application of the corrosion resistance method for cylindrical battery cells according to embodiments of this application.

[0023] Figure 5 A block diagram showing a test apparatus for the corrosion resistance performance of battery cells according to an embodiment of this application. Detailed Implementation

[0024] 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 a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0025] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0027] The following disclosure provides many different implementations or examples for carrying out different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials. In some instances, methods, means, elements, and circuits well known to those skilled in the art are not described in detail in order to highlight the main points of this application.

[0028] Figure 1 A flowchart illustrating a method for testing the corrosion resistance of battery cells according to an embodiment of this application is provided. Figure 1 As shown, the test method for the corrosion resistance of the battery cell may include:

[0029] Step S1: Install the simulated battery cell casing inside a test container, wherein the test container contains a corrosive liquid for submerging at least a portion of the simulated battery cell casing;

[0030] In one embodiment, the simulated cell casing can be part of a complete cell used in actual applications. The simulated cell casing includes a positive simulated electrode plate and a negative simulated electrode plate. The positive simulated electrode plate is the same as the positive electrode plate of a cell used in actual applications, and the negative simulated electrode plate is the same as the negative electrode plate of a cell used in actual applications. In this application, apart from the positive and negative simulated electrode plates, the electrolyte, separator, and other components of a complete cell can be omitted from the simulated cell casing. By using the positive and negative plates of the battery cell used in actual application environments as positive and negative simulated plates, respectively, and submerging at least a portion of the positive and negative simulated plates, on the one hand, the embodiments of this application can avoid redesigning the electrodes used for battery cell corrosion resistance testing, thereby improving the testing efficiency of battery cell corrosion resistance. On the other hand, since the simulated battery cell shell utilizes the outer shell of the battery cell, and the simulated battery cell shell itself does not contain electrolyte and cannot provide electromotive force, the simulated battery cell shell will not be affected by electrical connections, reducing the risk of short circuit between the positive and negative electrodes of the battery cell and improving the testing safety of battery cell corrosion resistance.

[0031] It is worth noting that the type of simulated battery cell corresponding to the simulated battery cell casing in this application embodiment can be determined as needed, such as a pouch cell. Preferably, the simulated battery cell is a square cell or a cylindrical cell. Because the simulated battery cell casing has a low short-circuit risk and high safety, it can be applied to different types of battery cells, thus broadening the application scenarios for battery cell corrosion resistance testing.

[0032] In one embodiment, the model number of the simulated battery cell casing is the same as that of the test battery cell casing. The test battery cell includes a positive test electrode and a negative test electrode. The positive test electrode and the positive simulated electrode are of the same model number, and the negative test electrode and the negative simulated electrode are of the same model number. Because the model number of the simulated battery cell casing is the same as that of the test battery cell casing, the corrosion condition of the simulated battery cell casing in the etching solution can accurately reflect the corrosion condition of the test battery cell casing in the etching solution.

[0033] The test cell can be a complete cell used in actual applications. This test cell can provide an electromotive force (EMF) for the test circuit of the cell's corrosion resistance performance. The current EMF of the test cell can be used to calculate the current remaining charge of the test cell. Since the remaining charge of the test cell is required to test its corrosion resistance performance, it is necessary to ensure that the remaining charge of the test cell reaches the expected level to avoid interruption of the corrosion resistance test due to insufficient remaining charge.

[0034] Specifically, if the current electromotive force (EMF) of the test cell is greater than or equal to a preset EMF threshold, it indicates that the remaining charge of the test cell is sufficient to support the completion of the corrosion resistance test, and therefore the test cell can be directly installed in the test container. If the current EMF of the test cell does not exceed the EMF threshold, it indicates that the remaining charge of the test cell is insufficient to support the completion of the corrosion resistance test, posing a risk of interruption to the corrosion resistance test. Therefore, the test cell can be charged before being used for testing. Alternatively, multiple test cells with insufficient remaining charge can be installed together to form a test cell group to avoid the risk of interruption to the corrosion resistance test.

[0035] Figure 2 A schematic diagram of a square battery cell according to an embodiment of this application is shown. The square battery cell casing includes a positive electrode plate 11 and a negative electrode plate 12. Since the square battery cell casing is typically flat, when it is laid flat, the positive test points corresponding to the positive electrode plate and the negative test points corresponding to the negative electrode plate are welded based on the square battery cell casing, without needing to consider the risk of a short circuit between the positive electrode plate 11 and the negative electrode plate 12.

[0036] In one embodiment, the square battery cell casing is fixedly installed at the bottom of the test container, and the height direction of the square battery cell casing is parallel to the bottom of the test container. For example, the test container can be a trough-shaped container, and the square battery cell is fixedly installed at the bottom of the test container through the opening of the trough-shaped container. During installation, a clamp can be used to hold the square battery cell casing, keeping the height direction of the square battery cell casing parallel to the bottom of the test container, and gradually sinking it into the bottom of the test container from top to bottom. Compared to the prior art where the length direction of the square battery cell is placed perpendicular to the bottom of the test container, i.e., the square battery cell is vertically submerged in the corrosive liquid, this embodiment can provide uncorroded test points even when the square battery cell casing is subjected to corrosion, thereby avoiding the influence of the corrosive liquid on the test of the square battery cell casing, making the corrosion resistance test of the battery cell more accurate, and improving the safety of the corrosion resistance test of the battery cell.

[0037] Step S2: Connect the positive test plate to the positive simulation plate, and connect the negative test plate to the negative simulation plate.

[0038] In one embodiment, to facilitate the connection between the square cell casing and the test cell, the positive electrode plate 11 can lead out a positive test point A, and the negative electrode plate 12 can lead out a negative test point B. The positive test point is electrically connected to the positive test electrode plate through a wire, and the negative test point is electrically connected to the negative test electrode plate through another wire.

[0039] Step S3: Connect the positive and negative simulated electrode plates to the voltage measuring device.

[0040] The voltage measuring device can be a voltmeter 30, which can be analog or digital. The voltmeter 30 has a positive test terminal and a negative test terminal. The positive plate is electrically connected to the positive test terminal via a wire, and the negative plate is electrically connected to the negative test terminal via another wire. In other words, the voltmeter 30 can be connected in parallel on the square battery cell casing to monitor the voltage between the positive and negative plates of the square battery cell casing in the corrosive solution. The voltage measuring device can also be implemented in other ways, and this application does not limit the specific implementation of the voltage measuring device.

[0041] Furthermore, the corrosive liquid in the test container submerges a portion of the positive simulated electrode plate and a portion of the negative simulated electrode plate. Figure 3 This diagram illustrates the application of the method for improving the corrosion resistance of a square battery cell casing according to an embodiment of this application. See also... Figure 3 The square battery cell casing can be placed horizontally at the bottom of the test container 20, and the corrosive liquid inside the test container 20 submerges a portion of the positive electrode plate 11 and a portion of the negative electrode plate 12. Two wooden strips, namely wooden strip 201 and wooden strip 202, can be provided on the bottom surface of the test container 20. Wooden strips 201 and 202 can be cuboid in shape. The side of wooden strip 201 can abut against the left half of the square battery cell casing, and the side of wooden strip 202 can abut against the right half of the square battery cell casing, thereby fixing the square battery cell casing under the action of wooden strips 201 and 202 and preventing the square battery cell from moving.

[0042] In one embodiment, the positions of the wooden strips 201 and 202 are movable. By moving the positions of the wooden strips 201 and 202, the position of the square battery cell casing can be changed, thereby adjusting the relative distance between the square battery cell casing and the surface of the corrosive liquid. For example, the wooden strips 201 and 202 can be mounted on a guide rail. By moving the corresponding adjustment lever outside the test container, the wooden strips 201 and 202 can be moved along the guide rail, thereby adjusting their positions. Of course, in practical applications, there are other ways to adjust the position of the square battery cell casing. For example, the square battery cell casing can be suspended at a fixed height first, and then the positions of the wooden strips 201 and 202 can be adjusted. It is understood that this application does not limit how the square battery cell casing is fixedly installed.

[0043] Further, the step of electrically connecting the positive and negative simulated electrode plates to the voltage measuring device includes:

[0044] Step S31: Connect the positive simulated electrode plate, which exposes a portion of the corrosive liquid, and the negative simulated electrode plate, which exposes a portion of the corrosive liquid, to the voltage measuring device.

[0045] In one embodiment, please refer to Figure 3 The positive simulation electrode 11 includes a portion exposed to the corrosive liquid and a portion submerged in the corrosive liquid. The area of ​​the portion exposed to the corrosive liquid and the area of ​​the portion submerged in the corrosive liquid are equal. That is, the surface of the corrosive liquid can coincide with the centerline of the positive simulation electrode 11, equally dividing the positive simulation electrode 11. Similarly, the negative simulation electrode 12 may also include a portion exposed to the corrosive liquid and a portion submerged in the corrosive liquid. The area of ​​the portion exposed to the corrosive liquid and the area of ​​the portion submerged in the corrosive liquid are equal. That is, the surface of the corrosive liquid can coincide with the centerline of the negative simulation electrode 12, equally dividing the negative simulation electrode 12. For example, both the positive simulation electrode 11 and the negative simulation electrode 12 are rectangular.

[0046] By connecting the positive and negative simulated electrode plates, each exposed in the corrosive liquid, to the voltage measuring device, this embodiment of the application can utilize the existing positive and negative simulated electrode plates in the simulated battery cell casing as two electrode plates in the method for testing the corrosion resistance of the battery cell. The existing charge of the test battery cell E1 is used to power the test circuit. Furthermore, since the voltage measuring device is connected to the positive and negative simulated electrode plates exposed in the corrosive liquid, the measurement points are not affected by the corrosive liquid, making the corrosion resistance test of the battery cell more accurate and improving the safety of the corrosion resistance test.

[0047] It should be noted that, Figure 3 The distance between horizontal line 101 and horizontal line 102 is the electrical distance h between the positive electrode plate 11 and the negative electrode plate 12. For square cells, the electrical distance h can be between 1mm and 2mm. Since this electrical distance h is relatively small, the positive test point A is positioned on the positive electrode plate, exposing a portion of the corrosive liquid, and the negative test point B is positioned on the negative electrode plate, exposing a portion of the corrosive liquid. To provide sufficient space for welding the positive test point A and the negative test point B, ensuring that neither point A nor point B touches the corrosive liquid, the positive test point A is positioned above the bisector (or center line) of the positive electrode plate 11, and the negative test point B is positioned above the bisector of the negative electrode plate 12. The bisectors of the positive and negative electrode plates 11 and the surface of the corrosive liquid coincide, providing sufficient margin for welding the positive and negative test points and further improving the safety of the cell's corrosion resistance test.

[0048] Furthermore, the test method for the corrosion resistance of the battery cell also includes:

[0049] Step S4: Obtain the corrosion resistance performance of the test cell using the voltage measuring device.

[0050] For example, the corrosion resistance of the test cell can be classified into grades, with the first grade indicating that the corrosion resistance of the test cell is excellent, the second grade indicating that the corrosion resistance of the test cell is medium, and the third grade indicating that the corrosion resistance of the test cell is poor.

[0051] In practical applications of the test cell, the voltage across its positive and negative terminals is affected by multiple factors. For example, the voltage between the positive and negative plates of the test cell may decrease rapidly within a short period, making it difficult to pinpoint the cause of this abnormal voltage drop. To address this, this embodiment of the application uses a voltage measurement device to obtain the corrosion resistance performance of the test cell. Based on the test results regarding the corrosion resistance performance, the cause of the abnormal voltage drop can be identified, and the test cell can be improved accordingly.

[0052] Further, the step of obtaining the corrosion resistance performance of the test cell through the voltage measuring device includes:

[0053] Step S41: Obtain multiple test voltage values ​​between the positive and negative simulated plates within a preset time range using the voltage measuring device;

[0054] The voltage measuring device can acquire a series of test voltage values ​​within a preset time range. Each test voltage value corresponds to a test time, and multiple test voltage values ​​and test times together form multiple discrete value pairs.

[0055] Step S42: Calculate the rate of change of the test voltage value based on the relationship curves between the multiple test voltage values ​​and the test time;

[0056] For example, multiple test times can be plotted on the x-axis of a two-dimensional coordinate system, and multiple test voltage values ​​can be plotted on the y-axis of the same system, with each test voltage value corresponding to a test time. In this case, the slope of the relationship curve can represent the rate of change of the test voltage.

[0057] Step S43: Determine the corrosion resistance of the test cell based on the rate of change of the test voltage value.

[0058] In one example, if the rate of change of the test voltage is greater than a first rate threshold, it indicates that the corrosion resistance of the test cell is low. By comparing the test voltage's rate of change with the abnormal voltage rate of an actual cell under abnormal voltage rate drops, if the test voltage's rate of change is equal to this abnormal voltage rate, it can be determined that the abnormal voltage rate drops in the actual cell are due to the influence of the corrosive liquid. If the rate of change of the test voltage is between a second rate threshold and a first rate threshold, it indicates that the corrosion resistance of the test cell is medium; if the rate of change of the test voltage is less than the second rate threshold, it indicates that the corrosion resistance of the test cell is high. The second rate threshold is less than the first rate threshold.

[0059] In one embodiment, after the step of electrically connecting the positive and negative simulated electrode plates to the voltage measuring device, the method further includes:

[0060] Step S44: The degree of corrosion of the simulated battery cell casing is obtained by measuring the amount of bubbles or color changes within a preset time range.

[0061] The bubble quantity can be the number of bubbles emerging from the portion of the simulated battery cell immersed in the corrosive solution, and the color change quantity can be the degree of color change on the outer surface of the simulated battery cell's casing. The bubble quantity or color change quantity can be measured in various ways, and this application is not limited to any particular method.

[0062] Step S45: Determine the corrosion resistance of the test cell based on the degree of corrosion severity.

[0063] The degree of corrosion severity can be divided into several levels, each of which can be used to determine the corrosion resistance of the test cell. It is worth noting that the amount of bubbles or color change can be recorded manually or measured using specific instruments; this application does not limit this.

[0064] In one embodiment, after the step of obtaining the corrosion resistance performance of the test cell through the voltage measuring device, the method further includes:

[0065] Step S51: Compare the rate of change of the test voltage with the preset rate of change to obtain the difference in the rate of change;

[0066] For example, the preset rate of change of the voltage to be compared can be the rate of change of the positive and negative voltages of a normal battery cell.

[0067] Step S52: Adjust the spacing between the positive and negative plates of other cells of the same model as the test cell according to the difference in the rate of change.

[0068] In step S52, the difference in the rate of change between the tested cell and the normal cell can be determined by the difference in the rate of change. Then, based on this difference, the spacing between the positive and negative plates of other cells of the same model as the tested cell can be adjusted to further optimize the corrosion resistance of other cells of the same model.

[0069] In one embodiment, the step of adjusting the spacing between the positive and negative plates of other cells of the same model as the test cell based on the difference in the rate of change includes:

[0070] Step S521: If the difference in the rate of change is greater than or equal to the rate of change threshold, increase the spacing between the positive and negative plates of other cells of the same model as the tested cell.

[0071] In this application, the applicant discovered a correlation between the spacing between the positive and negative plates of the test cell and the cell's corrosion resistance. Therefore, the spacing between the positive and negative plates of the cell can be increased or decreased based on the difference in the rate of change, thereby optimizing the cell's corrosion resistance.

[0072] In one embodiment, after the step of obtaining the corrosion resistance performance of the test cell through the voltage measuring device, the method further includes:

[0073] Step S53: Adjust the materials of the positive and / or negative plates of other cells of the same model as the test cell according to the difference in the rate of change.

[0074] In this application, the materials of the positive and / or negative plates of the battery cell are also related to the corrosion resistance of the battery cell. Therefore, the corrosion resistance of the battery cell can be further optimized by changing the materials of the positive and / or negative plates, or by optimizing the material parameters of the positive and / or negative plates.

[0075] Figure 4 A schematic diagram illustrating the application of the corrosion resistance method for cylindrical battery cells according to embodiments of this application. For example... Figure 4 As shown, in one embodiment, the simulated battery cell casing is a cylindrical battery cell casing, which is fixedly installed at the bottom of the test container, and the axial direction of the cylindrical battery cell casing is parallel to the bottom of the test container. That is, the cylindrical battery cell casing can be placed horizontally at the bottom of the test container 20', and the corrosive liquid inside the test container 20' submerges a portion of the positive electrode plate 11' and a portion of the negative electrode plate 12'. Two wooden strips, namely wooden strip 201' and wooden strip 202', can be provided on the bottom surface of the test container 20'. Wooden strip 201' and wooden strip 202' can be cuboid in shape. The side of wooden strip 201' can abut against the left side of the cylindrical battery cell casing, and the side of wooden strip 202' can abut against the right side of the cylindrical battery cell casing, thereby fixing the cylindrical battery cell casing under the action of wooden strip 201' and wooden strip 202' and preventing the cylindrical battery cell casing from moving. The voltmeter 30' can be connected in parallel across the two ends of the test cell E2, and the test cell E2 can provide power to the entire test circuit.

[0076] It should be noted that, Figure 4The distance between horizontal line 101' and horizontal line 102' is the electrical distance h between the positive electrode plate 11' and the negative electrode plate 12'. For cylindrical cell casings, the electrical distance h can be between 1mm and 3mm. Because this electrical distance h is small, the positive test point A' is set on the positive electrode plate exposing a portion of the corrosive liquid, and the negative test point B' is set on the negative electrode plate exposing a portion of the corrosive liquid. To allow sufficient space for welding the positive test point A' and the negative test point B', ensuring that neither point A' nor point B' comes into contact with the corrosive liquid, the positive test point A' is positioned above the bisector (or center line) of the positive electrode plate 11', and the negative test point B' is positioned above the bisector of the negative electrode plate 12'. The bisectors of the positive electrode plate 11' and the negative electrode plate 12', along with the surface of the corrosive liquid, coincide. This provides ample margin for welding the positive and negative test points, further enhancing the safety of the cell's corrosion resistance test.

[0077] It should be noted that, regardless of Figure 3 The square battery cell casing is still Figure 4 The cylindrical cell casings in the test circuit can all have switches installed, for example in... Figure 3 The test circuit is equipped with switch K1. Figure 4 The test circuit is equipped with a switch K2 to control the start and stop of the corrosion resistance test of the battery cell.

[0078] In summary, this embodiment of the application, by installing the simulated battery cell casing inside a test container, submerging at least a portion of the simulated battery cell casing in the corrosive liquid within the test container, electrically connecting the positive test electrode to the positive simulated electrode, electrically connecting the negative test electrode to the negative simulated electrode, and electrically connecting the positive and negative simulated electrodes to a voltage measuring device, utilizes the uncharged simulated battery cell casing as a reaction electrode. This avoids the battery cell test being affected by the corrosive liquid, making the corrosion resistance test of the battery cell more accurate and improving its safety. It also facilitates monitoring changes in battery cell voltage and the intensity of the corrosion interface reaction during the corrosion process, and is applicable to various types of battery cells.

[0079] also, Figure 5 A block diagram illustrating a testing apparatus for the corrosion resistance of battery cells according to an embodiment of this application is shown. Figure 4As shown, the testing device for the corrosion resistance of the battery cell includes: a simulated battery cell casing 51, comprising a positive simulated electrode plate and a negative simulated electrode plate, wherein the positive simulated electrode plate is electrically connected to the positive test electrode plate of the test battery cell, and the negative simulated electrode plate is electrically connected to the negative test electrode plate of the test battery cell; a testing container 52, for containing a corrosive liquid to submerge at least a portion of the simulated battery cell casing; a test battery cell 53, for being electrically connected to the positive simulated electrode plate and the negative simulated electrode plate; and a voltage measuring device 54, for being electrically connected to the positive simulated electrode plate and the negative simulated electrode plate. It is understood that this application does not limit the specific implementation of the testing device for the corrosion resistance of the battery cell.

[0080] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0081] The above provides a detailed description of the testing method and apparatus for the corrosion resistance of battery cells provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. 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 of the technical features. 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.

Claims

1. A method for testing the corrosion resistance of a battery cell, characterized in that, The simulated battery cell casing includes a positive simulated electrode plate and a negative simulated electrode plate; the test battery cell includes a positive test electrode plate and a negative test electrode plate; the method includes: The simulated battery cell casing is installed inside a test container, wherein the test container contains an etching solution for submerging at least a portion of the positive simulated electrode plate and at least a portion of the negative simulated electrode plate of the simulated battery cell casing. The positive test electrode is electrically connected to the positive simulation electrode, and the negative test electrode is electrically connected to the negative simulation electrode. The positive and negative simulated electrode plates are electrically connected to a voltage measuring device to obtain the corrosion resistance performance of the test cell. The positive simulated electrode plate, with a portion exposed in the corrosive liquid, and the negative simulated electrode plate, with a portion exposed in the corrosive liquid, are connected to the voltage measuring device.

2. The method for testing the corrosion resistance of a battery cell according to claim 1, characterized in that, The model number of the simulated battery cell casing is the same as that of the test battery cell casing.

3. The test method for the corrosion resistance of a battery cell according to any one of claims 1-2, characterized in that, The test method for the corrosion resistance of the battery cell also includes: The corrosion resistance of the test cell is obtained using the voltage measuring device.

4. The test method for the corrosion resistance of the battery cell according to claim 3, characterized in that, The step of obtaining the corrosion resistance performance of the test cell using the voltage measuring device includes: The voltage measuring device acquires multiple test voltage values ​​between the positive and negative simulated plates within a preset time range. Calculate the rate of change of the test voltage value based on the relationship curves between the multiple test voltage values ​​and the test time; The corrosion resistance of the test cell is determined based on the rate of change of the test voltage value.

5. The method for testing the corrosion resistance of a battery cell according to claim 4, characterized in that, After the step of obtaining the corrosion resistance performance of the test cell through the voltage measuring device, the method further includes: The rate of change of the test voltage is compared with the preset rate of change to obtain the rate of change difference; Adjust the spacing between the positive and negative plates of other cells of the same model as the tested cell based on the difference in the rate of change.

6. The method for testing the corrosion resistance of a battery cell according to claim 5, characterized in that, The step of adjusting the spacing between the positive and negative plates of other battery cells of the same model as the tested battery cell based on the difference in the rate of change includes: If the difference in the rate of change is greater than or equal to the rate of change threshold, increase the spacing between the positive and negative plates of other cells of the same model as the tested cell.

7. The method for testing the corrosion resistance of a battery cell according to claim 5, characterized in that, After the step of obtaining the corrosion resistance performance of the test cell through the voltage measuring device, the method further includes: Adjust the materials of the positive and / or negative plates of other cells of the same model as the tested cell based on the difference in the rate of change.

8. The method for testing the corrosion resistance of a battery cell according to any one of claims 1-2, characterized in that, After the step of electrically connecting the positive and negative simulated electrode plates to the voltage measuring device, the method further includes: The degree of corrosion of the simulated battery cell casing can be determined by the amount of bubbles or color changes within a preset time range. The corrosion resistance of the test cell is determined based on the degree of corrosion severity.

9. The method for testing the corrosion resistance of a battery cell according to any one of claims 1-2, characterized in that, The simulated battery cell casing is a cylindrical battery cell casing, which is fixedly installed at the bottom of the test container, and the axial direction of the cylindrical battery cell casing is parallel to the bottom of the test container.

10. The method for testing the corrosion resistance of a battery cell according to any one of claims 1-2, characterized in that, The simulated battery cell casing is a square battery cell casing, which is fixed to the bottom of the test container, and the height direction of the square battery cell casing is parallel to the bottom of the test container.

11. A testing device for the corrosion resistance of battery cells, characterized in that, include: The simulated battery cell casing includes a positive simulated electrode plate and a negative simulated electrode plate. The positive simulated electrode plate is electrically connected to the positive test electrode plate of the test battery cell, and the negative simulated electrode plate is electrically connected to the negative test electrode plate of the test battery cell. The test battery cell includes the positive test electrode plate and the negative test electrode plate. A test container for containing a corrosive solution to submerge at least a portion of the simulated battery cell casing; A voltage measuring device is used to electrically connect the positive simulated electrode plate and the negative simulated electrode plate; The positive simulated electrode plate, with a portion exposed in the corrosive liquid, and the negative simulated electrode plate, with a portion exposed in the corrosive liquid, are connected to the voltage measuring device.

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