Device for measuring electrolyte absorption rate of sheet material

Abstract

A device for measuring the electrolyte absorption rate of a sheet material. The device for measuring the electrolyte absorption rate of a sheet material comprises: a base (1); a support (2), arranged on the base (1); two electrode posts (6) and a resistance measurement apparatus (7) which are arranged on the base (1), the electrode posts being electrically connected to the resistance measurement apparatus (7); an electrolyte supply apparatus (5) and a liquid conveying head (4) which are arranged on the support (2), the electrolyte supply apparatus (5) being communicated with the liquid conveying head (4); and a fixing apparatus (8) used for closely attaching a sheet material (2) to the two electrode posts (6). By adding an electrolyte to the sheet material (2) and measuring the resistance of the sheet material (2), the electrolyte infiltration rate of the sheet material (2) is acquired. Compared with the prior art, the present application can accurately represent electrolyte infiltration rates of sheet materials (2), and has relatively good reproducibility and consistency of measurement results.

Description

A sheet electrolyte absorption rate testing device Technical Field

[0001] The present application relates to the field of battery testing technology, and in particular to a sheet electrolyte absorption rate testing device. Background Art

[0002] The electrolyte infiltration rate refers to the amount of material that infiltrates the surface of the battery electrode per unit time and unit area. This electrolyte infiltration rate significantly impacts subsequent battery performance. A low electrolyte infiltration rate indicates a long lithium ion transmission path, making it difficult for lithium ions to travel between the positive and negative electrodes. Battery electrodes not exposed to the electrolyte cannot participate in the battery's electrochemical reactions, increasing the battery's interfacial resistance and impacting the battery's rate performance, discharge capacity, and service life.

[0003] It can be seen that in the process of producing lithium batteries, it is particularly important to test the electrolyte infiltration rate of battery electrodes. In the prior art, there are various methods for testing the electrolyte infiltration rate of battery electrodes. For example, the imbibition method and the weighing method, among which the imbibition method refers to measuring the diffusion area of ​​the electrolyte on the battery electrode within a certain period of time. If the diffusion area is large, it means that the electrolyte infiltration rate is high, otherwise it is low. The weighing method refers to measuring the mass of electrolyte that can be absorbed by the battery electrode per unit volume. If the mass of electrolyte absorbed is large, it means that the electrolyte infiltration rate is high, otherwise it is low. It should be clear that both the imbibition method and the weighing method are easily affected by environmental factors, and the operation is difficult to accurately control. In other words, the reproducibility and consistency of the measurement results of the imbibition method and the weighing method are poor. In other words, the measurement results of the imbibition method and the weighing method are also difficult to accurately characterize the electrolyte infiltration rate of the battery electrode. Utility Model

[0004] The purpose of this application is to provide a sheet electrolyte absorption rate testing device to solve the technical problem in the prior art that it is difficult to accurately measure the electrolyte infiltration rate of battery pole pieces.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions: a sheet electrolyte absorption rate testing device, comprising: a base; a bracket, arranged on the base; a resistance measuring device and two electrode columns arranged on the base, the electrode columns being electrically connected to the resistance measuring device; a liquid supply device and a liquid delivery head arranged on the bracket, the liquid supply device being connected to the liquid delivery head; a fixing device, used to make the sheet material fit tightly with the two electrode columns.

[0006] As a specific solution in the technical solution of the present application, the resistance measuring device includes a voltmeter and an ammeter, or the resistance measuring device includes a multimeter.

[0007] As a specific solution in the technical solution of the present application, the liquid supply device includes a sprayer, or a syringe, or a peristaltic pump.

[0008] As a specific solution in the technical solution of the present application, it also includes a pressing device, which drives the liquid delivery head to reciprocate in the vertical direction so that the liquid delivery head can fit the sheet material.

[0009] As a specific solution in the technical solution of the present application, the pressing device includes an electric push rod or a hydraulic push rod.

[0010] As a specific solution in the technical solution of the present application, a pressure sensor is further provided between the pressing device and the liquid delivery head.

[0011] As a specific solution in the technical solution of this application, the fixing device includes a magnetic block corresponding to the two electrode columns one by one, or the fixing device includes a pressing block corresponding to the two electrode columns one by one, and the pressing block is arranged on the pressing device.

[0012] As a specific solution in the technical solution of the present application, it also includes a lower support probe corresponding to the liquid delivery head, the lower support probe is arranged on the base, and the lower support probe coincides with the axial center line of the liquid delivery head.

[0013] As a specific solution in the technical solution of the present application, it also includes a processor, which is electrically connected to the resistance measuring device and the liquid supply device.

[0014] As a specific solution in the technical solution of the present application, it also includes a protective cover arranged on the base, and the bracket, the resistance measuring device, the two electrode columns, the liquid supply device, the liquid delivery head and the fixing device are all located in the protective cover.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The present invention can obtain the electrolyte infiltration rate of a sheet material by adding an electrolyte to the sheet material and measuring the sheet material's resistance. Compared with existing technologies, the present invention can accurately characterize the electrolyte infiltration rate of a sheet material and has good reproducibility and consistency of measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG1 is a perspective view of a sheet electrolyte absorption rate testing device proposed in an embodiment of the present application;

[0018] FIG2 is a perspective view of the sheet electrolyte absorption rate test equipment in FIG1 with the protective cover removed;

[0019] Figure 3 is a front view of Figure 2;

[0020] FIG4 is a graph showing the resistance change of the same battery electrode sheet tested by the sheet electrolyte absorption rate testing device proposed in an embodiment of the present application;

[0021] FIG5 is a graph showing the resistance variation of different battery electrodes tested by the sheet electrolyte absorption rate test device proposed in an embodiment of the present application;

[0022] FIG6 is a resistance change curve diagram of the same battery electrode with different pore curvatures tested by the sheet electrolyte absorption rate testing equipment proposed in an embodiment of the present application.

[0023] In the figure: 1. Base; 2. Bracket; 3. Lower support probe; 4. Liquid delivery head; 5. Liquid supply device; 6. Electrode column; 7. Resistance measuring device; 8. Fixing device; 9. Pressure sensor; 10. Pressing device; 11. Processor; 12. Sheet material; 13. Protective cover. Implementation Method

[0024] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0025] It should be noted that, in the description of this application, the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as a limitation on this application.

[0026] Furthermore, it should be understood that for the sake of ease of description, the sizes of the various components shown in the drawings are not drawn according to actual proportions. For example, the thickness or width of certain layers may be exaggerated relative to other layers.

[0027] It should be noted that like numbers and letters represent similar items in the following figures, so once an item is defined or described in one figure, it will not need to be further discussed and described in detail in the description of the subsequent figures.

[0028] It should be clear that in the drawings of the embodiments of the present application, in order to clearly show the various structures of the embodiments of the present application, the drawing of electrical connection lines and liquid connection tubes is omitted in each drawing.

[0029] Before understanding the technical solution of this application, it is important to understand that the electrolyte is an ionic conductor that conducts lithium ions between the positive and negative electrodes of a battery. During the charge and discharge process, it transports lithium ions back and forth between the positive and negative electrodes. The electrolyte has a significant impact on the battery's charge and discharge performance (rate and temperature), lifespan (cycle storage), and temperature range. After extensive battery disassembly and analysis, it was found that batteries with poor cycle performance often have poor electrolyte wetting of the battery electrodes. When the electrolyte wetting effect is poor, the ion transmission path becomes longer, hindering the shuttle of lithium ions between the positive and negative electrodes. Electrodes not in contact with the electrolyte cannot participate in the battery's electrochemical reactions, and the battery interface resistance increases, affecting the lithium battery's rate performance, discharge capacity, and service life. In other words, if the electrolyte wetting rate of the battery electrode is poor, the electrolyte's fluidity on the battery electrode is poor. If the electrolyte is added to the surface of the battery electrode, as the electrolyte penetrates from one side of the battery electrode to the other, the resistance of the battery electrode gradually decreases as the electrolyte penetration progresses. In other words, if the electrolyte wetting rate of the battery electrode is good, the resistance of the battery electrode decreases quickly, and if the electrolyte wetting rate of the battery electrode is poor, the resistance of the battery electrode decreases slowly. In other words, the electrolyte wetting rate of the battery electrode can be characterized by the rate of change in the resistance of the battery electrode after adding electrolyte.

[0030] In order to solve the technical problems in the background technology, the embodiment of the present application is a sheet electrolyte absorption rate testing device. Specifically, as shown in Figures 1 to 3, the device includes a base 1, a bracket 2, a resistance measuring device 7 and two electrode columns 6 arranged on the base 1, a liquid supply device 5 and a liquid delivery head 4 and a fixing device 8 arranged on the bracket 2. Among them, the bracket 2 is arranged on the base 1. Of course, in other embodiments of the present application, the bracket 2 can also be designed to be split from the base 1, and the bracket 2 and the base 1 are spliced ​​together when in use. The electrode column 6 is electrically connected to the resistance measuring device 7, and the liquid supply device 5 is connected to the liquid delivery head 4. The fixing device 8 is used to make the sheet material 12 fit tightly with the two electrode columns 6.

[0031] It should be understood that the sheet material 12 in the embodiments of this application is not limited to the battery electrode described in the background art; it can be any material for which electrolyte wetting rate measurement is required. In other words, in some applications, the sheet material 12 can be a single-layer material, such as a separator, anode coating, or cathode coating. In other applications, the sheet material 12 can be a multilayer material, such as a battery electrode or a composite current collector.

[0032] Specifically, in the embodiment of the present application, the liquid supply device 5 and the liquid delivery head 4 are primarily used to add electrolyte to the outer surface of the sheet material 12. It will be readily understood that the liquid supply device 5 and the liquid delivery head 4 can be any device capable of delivering liquid, for example, the liquid supply device 5 can be a sprayer, syringe, or peristaltic pump. The liquid delivery head 4 can be a spray head or liquid delivery head compatible with a sprayer, syringe, or peristaltic pump, and there are no limitations on its shape or structure.

[0033] In the embodiment of the present application, the resistance measuring device 7 is mainly used to test the resistance change of the sheet material 12 after the electrolyte is added. That is, the resistance measuring device 7 can be any device that can measure the resistance of an object. For example, in one embodiment of the present application, the resistance measuring device 7 can be a combination of a voltmeter and an ammeter, while in another embodiment of the present application, the resistance measuring device 7 can be a multimeter. The two electrode columns 6 are mainly used to contact the sheet material 12 and measure the resistance change of the sheet material 12. It is easy to understand that one of the electrode columns 6 is used to electrically connect to the positive pole of the resistance measuring device 7, and the other electrode column 6 is used to electrically connect to the negative pole of the resistance measuring device 7.

[0034] It should be understood that in the embodiments of the present application, the liquid delivery head 4 and the sheet material 12 can be kept out of contact, and the electrolyte can be added to the sheet material 12 by the liquid delivery head 4 in mid-air. In a specific embodiment of the present application, to ensure the stability of the added electrolyte, as shown in Figures 2 and 3, the sheet electrolyte absorption rate test device further includes a pressing device 10, which drives the liquid delivery head 4 to reciprocate in the vertical direction to enable the liquid delivery head 4 to adhere to the sheet material 12.

[0035] Specifically, compared with adding electrolyte in mid-air, if the addition method is spraying or dripping, the electrolyte may splash or drift. However, after the liquid delivery head 4 is attached to the sheet material 12, the amount of electrolyte added to the outer surface of the sheet material 12 can be accurately controlled to ensure detection stability.

[0036] In the embodiment of the present application, the pressing device 10 can be any structure capable of driving the liquid delivery head 4 to perform reciprocating motion. It is easy to understand that in the prior art, there are many devices or structures that can drive an object to perform reciprocating motion, such as: electric push rods, hydraulic push rods, gear rack structures, threaded rod and threaded sleeve structures, etc. These structures can all be applied to the pressing device 10 in the embodiment of the present application, and will not be described in detail here.

[0037] It should be understood that the electrolyte infiltration rate of the sheet material 12 is also highly correlated with its own gap. The larger the gap of the sheet material 12, the better its electrolyte infiltration rate; the smaller the gap of the sheet material 12, the worse its electrolyte infiltration rate. As can be seen from the foregoing, the pressing device 10 mainly drives the liquid delivery head 4 to fit the outer surface of the sheet material 12. In other words, if the bonding force generated between the liquid delivery head 4 and the sheet material 12 is greater, the sheet material 12 will change the gap in the force-bearing area of ​​the sheet material 12 due to the influence of the bonding force. In other words, it may affect the test results. In one embodiment of the present application, in order to make the bonding force generated between the liquid delivery head 4 and the sheet material 12 small enough (that is, it will not cause the gap of the sheet material 12 to change), or to make the bonding force generated between the liquid delivery head 4 and the sheet material 12 the same for each test during multiple tests. A pressure sensor 9 is also provided between the pressing device 10 and the liquid delivery head 4.

[0038] Specifically, in the embodiments of the present application, there is no limitation on the pressure sensor 9. It can be any type or model of pressure sensor. Those skilled in the art can choose according to their needs when implementing the technical solutions in the present application.

[0039] As previously mentioned, the embodiments of the present application test the electrolyte infiltration rate of the sheet material 12 by measuring the change in the resistance of the sheet material 12 after the addition of the electrolyte. In other words, accurately measuring the resistance performance of the sheet material 12 is particularly important in the embodiments of the present application. In the embodiments of the present application, the primary function of the fixture 8 is to ensure a tight fit between the sheet material 12 and the electrode column 6, thereby preventing inaccurate resistance measurements due to poor contact between the sheet material 12 and the electrode column 6. It also prevents inaccurate resistance measurements caused by movement of the sheet material 12 during the test.

[0040] In one embodiment of the present application, as shown in Figures 2 and 3, the fixing device 8 can be a magnetic block that corresponds one-to-one with the two electrode columns 6. In other words, the magnetic block fixes the sheet material 12 and the electrode columns 6 relative to each other. It is easy to imagine that in another embodiment of the present application, the fixing device 8 includes a pressing block that corresponds one-to-one with the two electrode columns 6, and the pressing block is disposed on the pressing device 10 (not shown in the figure). In other words, during each detection process, the pressing block can be driven by the pressing device 10 to tightly fit the sheet material 12 and the electrode columns 6.

[0041] Of course, it is easy to imagine that in other embodiments of the present application, the fixing device 8 may also be in other shapes or structures, such as an elastic clip or an elastic pressing sheet.

[0042] In order to prevent the sheet material 12 from being broken by the liquid delivery head 4 due to the strong adhesion force generated between the liquid delivery head 4 and the sheet material 12, as shown in Figures 2 and 3, in one embodiment of the present application, the sheet electrolyte absorption rate testing device further includes a lower support probe 3 corresponding to the liquid delivery head 4. The lower support probe 3 is disposed on the base 1, and the axis of the lower support probe 3 coincides with the axis of the liquid delivery head 4. In other words, the lower support probe 3 can support the sheet material 12 to prevent the sheet material 12 from being broken by the liquid delivery head 4.

[0043] It should be understood that, in an embodiment of the present application, manual recording and processing of the detection data during the detection process can be employed. In another embodiment of the present application, the sheet electrolyte absorption rate test device is configured to automatically record and process the detection data during the detection process. As shown in Figures 1 to 3, the sheet electrolyte absorption rate test device further comprises a processor 11, which is electrically connected to the resistance measuring device 7 and the liquid supply device 5. Specifically, the resistance change curves obtained by automatic processing are shown in Figures 4, 5, and 6.

[0044] Figure 4 shows resistance curves obtained for the same sheet material 12, with different amounts of electrolyte and different types of electrolyte added. Figure 6 shows that the resistance change is essentially the same for the same sheet material 12 (i.e., the electrolyte infiltration rate is essentially the same). Figure 5 shows resistance curves for sheet materials 12 with different compaction densities. Figure 5 shows that different sheet materials 12 (i.e., different electrolyte infiltration rates) also show inconsistent resistance changes. Sheet materials 12 with lower compaction densities (i.e., larger gaps and better electrolyte infiltration rates) have faster resistance change rates. Figure 6 shows resistance curves for sheet materials 12 with the same compaction density but different pore curvatures. Figure 6 shows that for sheet materials 12 with essentially the same compaction density, the greater the pore curvature, the faster the resistance change rate (i.e., the resistance change slope). That is, in the embodiment of the present application, the quality of the electrolyte infiltration rate of the sheet material 12 can be determined based on the resistance change slope.

[0045] In one embodiment of the present application, in order to protect the various components in the sheet electrolyte absorption rate testing device, as shown in Figure 1, the sheet electrolyte absorption rate testing device also includes a protective cover 13 arranged on the base 1, and the bracket 2, the resistance measuring device 7, the two electrode columns 6, the liquid supply device 5, the liquid delivery head 4 and the fixing device 8 are all located in the protective cover 13.

[0046] The sheet material electrolyte absorption rate test device proposed in this application can obtain the electrolyte absorption rate of the sheet material by adding electrolyte to the sheet material and measuring the sheet material's resistance. Compared with existing technologies, this device can accurately characterize the electrolyte absorption rate of the sheet material and has good reproducibility and consistency of measurement results.

[0047] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A sheet electrolyte absorption rate testing device, characterized in that: include: Base (1); A bracket (2) is arranged on the base (1); A resistance measuring device (7) and two electrode columns (6) arranged on the base (1), the electrode columns (6) being electrically connected to the resistance measuring device (7); A liquid supply device (5) and a liquid delivery head (4) are arranged on the bracket (2), and the liquid supply device (5) is connected to the liquid delivery head (4); The fixing device (8) is used to make the sheet material (12) fit tightly with the two electrode columns (6).

2. The sheet electrolyte absorption rate testing device according to claim 1, characterized in that: The resistance measuring device (7) comprises a voltmeter and an ammeter, or the resistance measuring device (7) comprises a multimeter.

3. The sheet electrolyte absorption rate testing device according to claim 1, characterized in that: The liquid supply device (5) comprises a sprayer, or a syringe, or a peristaltic pump.

4. The sheet electrolyte absorption rate testing device according to claim 1, characterized in that: It also comprises a pressing device (10), wherein the pressing device (10) drives the liquid delivery head (4) to perform reciprocating motion in a vertical direction, so that the liquid delivery head (4) can fit the sheet material (12).

5. The sheet electrolyte absorption rate testing device according to claim 4, characterized in that: The pressing device (10) comprises an electric push rod or a hydraulic push rod.

6. The sheet electrolyte absorption rate testing device according to claim 4, characterized in that: A pressure sensor (9) is also provided between the pressing device (10) and the liquid delivery head (4).

7. The sheet electrolyte absorption rate testing device according to claim 4, characterized in that: The fixing device (8) comprises magnetic blocks corresponding one-to-one to the two electrode columns (6), or the fixing device (8) comprises pressing blocks corresponding one-to-one to the two electrode columns (6), and the pressing blocks are arranged on the pressing device (10).

8. The sheet electrolyte absorption rate testing device according to claim 4, characterized in that: It also comprises a lower support probe (3) corresponding to the liquid delivery head (4), wherein the lower support probe (3) is arranged on the base (1), and the axis of the lower support probe (3) coincides with the axis of the liquid delivery head (4).

9. The sheet electrolyte absorption rate testing device according to any one of claims 1 to 8, characterized in that: It also includes a processor (11), wherein the processor (11) is electrically connected to the resistance measuring device (7) and the liquid supply device (5).

10. The sheet electrolyte absorption rate testing device according to any one of claims 1 to 8, characterized in that: It also includes a protective cover (13) arranged on the base (1), and the bracket (2), the resistance measuring device (7), two electrode columns (6), the liquid supply device (5), the liquid delivery head (4) and the fixing device (8) are all located in the protective cover (13).

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