System and method for testing wettability of battery powder material

Abstract

The invention provides a battery powder material wettability test system and method, and relates to the technical field of battery material test.The battery powder material wettability test system comprises a sample storage device, a liquid injection assembly, an electric conductor and a resistance test.The sample storage device is provided with a sample storage cavity and a liquid injection channel communicated with the sample storage cavity, and the two ends, in the first direction, of the sample storage cavity are open and suitable for containing test powder; the liquid injection channel extends in the second direction and communicates with the liquid injection assembly. The two electric conductors are connected with the sample storage cavity in a sliding mode in the first direction, the two electric conductors correspond to the openings in the two ends of the sample storage cavity in a one-to-one mode so as to block the openings, and the electric conductors are suitable for being connected with an external pressure device so that the test powder can be pressed into samples; the electric conductor abuts against the sample and is electrically connected with the resistance tester. The wettability of the compacted mixed powder is tested, so that the testing process is closer to the actual use state of the powder, whether the powder is completely wetted or not can be accurately judged, the overall structure is simple, the testing error is small, and the testing cost is low.

Description

Technical Field

[0001] This application relates to the field of battery material testing technology, and in particular to a battery powder material wettability testing system and method. Background Technology

[0002] A battery is a device that converts chemical energy into electrical energy. Many factors affect battery performance. Among them, the wetting effect of the battery electrode material on the electrolyte is one of the important indicators for evaluating battery performance. Poor wetting will lead to an increase in the battery interface resistance, affecting the battery's rate performance, discharge capacity and cycle life. Therefore, it is necessary to study the wetting of the electrode material before battery manufacturing.

[0003] In related technologies, the testing of electrode wetting performance often only tests the electrode wetting rate, or judges whether the electrode is completely wetted by wetting it for a long time. However, it cannot determine whether the electrode is completely wetted, resulting in large test errors and strong limitations. In addition, the testing method is complicated, time-consuming, labor-intensive and costly when the powder material is made into an electrode. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in the related art.

[0005] Therefore, one embodiment of this application proposes a battery powder material wettability testing system. This battery powder material wettability testing system tests the wettability of compacted mixed powder, making the testing process closer to the actual use state of the powder. It can accurately determine whether the powder has been completely wetted. The overall structure is simple, the testing error is small, and the testing cost is low.

[0006] Another embodiment of this application proposes a method for testing the wettability of battery powder materials.

[0007] A battery powder material wettability testing system according to an embodiment of this application includes a sample storage device, a liquid injection assembly, conductors, and a resistance tester. The sample storage device has a sample storage cavity and a liquid injection channel communicating with the sample storage cavity. The sample storage cavity is open at both ends along a first direction and is adapted to hold test powder. The liquid injection channel extends along a second direction and communicates with the liquid injection assembly to inject electrolyte to wet the test powder. The second direction forms an angle with the first direction. There are two conductors, each slidably connected to the sample storage cavity along the first direction. The two conductors correspond one-to-one with the two openings at both ends of the sample storage cavity to seal the openings. The conductors are adapted to be connected to an external pressure device to compress the test powder into a sample. The conductors abut against the sample and are electrically connected to the resistance tester to measure the internal resistance of the sample.

[0008] According to the battery powder material wettability testing system of this application embodiment, the test powder can be filled into the sample storage cavity through the opening of the sample storage cavity in the sample storage device. The conductor can block the opening and cooperate with the external pressure device to complete the compaction of the test powder in the sample storage cavity to obtain a sample. Then, the connection between the conductor and the external pressure device is disconnected, so that the conductor is connected to the resistance tester. Electrolyte is injected into the sample through the injection channel through the liquid injection component to perform wettability testing on the sample. During the test, the conductor and the sample are in contact, which can form a closed loop between the sample, the two conductors and the resistance tester. The resistance tester measures the change of the internal resistance of the sample with the injection volume and the wetting time in real time. When the internal resistance of the sample no longer changes, it can be determined that the sample is completely wetted. Therefore, compared with related technologies, this application makes the test process closer to the actual use state of the powder by performing wettability testing on compacted mixed powder. It can accurately determine whether the powder is completely wetted. The overall structure is simple, the test error is small and the test cost is low.

[0009] In some embodiments, there are multiple injection channels and multiple injection assemblies, each corresponding to one of the injection channels;

[0010] Alternatively, the injection assembly may be a single unit, and the testing system may further include a dispensing tube having an inlet end and multiple outlet ends. The outlet of the injection assembly is connected to the inlet end of the dispensing tube, and the multiple injection channels are connected one-to-one with the multiple outlet ends of the dispensing tube.

[0011] It is understandable that a structural design that injects electrolyte into the sample through multiple injection components or one injection component via multiple injection channels can improve the efficiency of wettability testing of battery powder materials, while achieving uniform injection of electrolyte into the sample, thereby further ensuring the reliability of the test results.

[0012] In some embodiments, a plurality of the injection channel arrays are arranged in the sample storage device to ensure injection uniformity.

[0013] In some embodiments, the testing system further includes a negative pressure chamber, the negative pressure chamber having a negative pressure cavity, and the sample storage device located within the negative pressure cavity to test the wettability of the sample under negative pressure.

[0014] Understandably, since the liquid injection stage in battery production is carried out under negative pressure, placing the sample storage device in a negative pressure chamber for wettability testing can simulate the state of formal battery production. This not only makes the testing process closer to the actual state and improves the accuracy of the test results, but also verifies the differences in wettability of battery powder materials under different negative pressure states. This provides better guidance for controlling the relationship between battery powder materials and negative pressure during battery production, ensuring battery performance and achieving the goal of reducing costs and energy consumption in mass production.

[0015] In some embodiments, the testing system further includes a barometer connected to the negative pressure chamber and adapted to detect the air pressure in the negative pressure chamber, so as to obtain the pressure in the negative pressure chamber in real time and intuitively, which is conducive to timely adjustment of the negative pressure in the negative pressure chamber and ensures the smooth progress of the testing process.

[0016] In some embodiments, the injection assembly includes an injector and an injection funnel. The injector is detachably connected to the negative pressure chamber. The outlet of the injector is located in the negative pressure chamber and communicates with the inlet of the injection funnel. The injection funnel is located in the negative pressure chamber, and the outlet of the injection funnel is communicated with the injection channel.

[0017] Understandably, detachably connecting the injector to the negative pressure chamber facilitates the use of the injector to draw electrolyte for supplying electrolyte to the sample. Furthermore, the pressure difference between the negative pressure chamber and the external environment allows the electrolyte in the injector to automatically flow into the injection funnel, which then injects the electrolyte into the injection channel, ensuring a consistent injection rate and saving time and effort.

[0018] In some embodiments, on a projection plane perpendicular to the first direction, the outer contour of the projection of the sample storage cavity can be one of a circle, a polygon, and an arbitrary closed curve. Preferably, the outer contour of the projection of the sample storage cavity is a circle, and the conductor is a cylindrical conductive column, which facilitates the subsequent calculation of the sample volume and ensures the smooth sliding of the conductor at the opening of the sample storage cavity, so that the sample is subjected to uniform force during the pressing process, and further improves the accuracy of the test results.

[0019] In some embodiments, the inner peripheral wall of the sample storage cavity is coated with a corrosion-resistant material, or the sample storage device is made of a corrosion-resistant material to effectively avoid corrosion problems caused to the sample storage cavity during the wettability test and ensure the service life of the sample storage device.

[0020] In some embodiments, the testing system further includes a terminal device electrically connected to the resistance tester. The terminal device is used to record and process the test data of the resistance tester to further improve the automation performance of the testing system, which is beneficial for quickly analyzing and obtaining the wetting performance of battery powder materials and providing guidance for battery research.

[0021] A method for testing the wettability of battery powder materials according to an embodiment of this application, based on the battery powder material wettability testing system described in any of the above embodiments, includes the following steps:

[0022] A predetermined weight of test powder is loaded into the sample storage chamber, and the opening of the sample storage chamber is sealed by a conductor.

[0023] Pressure is applied to the conductor by an external pressure device, and the conductor slides along a first direction to squeeze the test powder to compress the sample.

[0024] The conductor is electrically connected to a resistance tester, and the electrolyte is injected into the sample through the injection channel by the injection assembly to obtain the change of the internal resistance of the sample with the injection volume and immersion time.

[0025] Calculate the total liquid absorption, wetting rate, compaction density, and liquid injection coefficient of the test powder.

[0026] The technical advantages of the battery powder material wettability testing method according to the embodiments of this application are the same as the technical advantages of the battery powder material wettability testing system described above, and will not be repeated here.

[0027] In some embodiments, prior to the steps of electrically connecting the conductor to a resistance tester, injecting electrolyte into the sample through an injection channel by an injection assembly, and obtaining the change in the internal resistance of the sample with the injection volume and immersion time, the method further includes:

[0028] Place the sample storage device in the negative pressure chamber and maintain the air pressure in the negative pressure chamber at the set negative pressure.

[0029] In some embodiments, prior to the step of loading a predetermined weight of test powder into a sample storage cavity and sealing the opening of the sample storage cavity with a conductor, the method further includes preparing the test powder.

[0030] In some embodiments, the step of preparing the test powder includes:

[0031] The main material, conductive agent and binder are mixed in the designed ratio and homogenized to obtain a mixed slurry solvent;

[0032] The solvent in the mixed slurry is dried to obtain a solid slurry.

[0033] The solid slurry is crushed to prepare test powder.

[0034] In some embodiments, the total liquid absorption of the test powder is calculated using the following formula:

[0035] G = G′ - G0

[0036] Wherein, G is the total liquid absorption of the test powder, G′ is the total weight of the sample storage device, the sample and the two conductors when the sample is fully wetted, and G0 is the total weight of the sample storage device, the sample and the two conductors before the sample is wetted.

[0037] In some embodiments, calculating the wetting rate of the test powder includes:

[0038] The wetting time of the test powder is calculated using the following formula:

[0039] Δt=t1-t0

[0040] Wherein, Δt is the wetting time of the test powder, t1 is the complete wetting time when the internal resistance of the sample no longer changes with time, and t0 is the initial time of injecting electrolyte into the sample.

[0041] Based on the wetting time and the total liquid absorption of the test powder, the wetting rate of the test powder is calculated using the following formula:

[0042]

[0043] Where v is the wetting rate of the test powder, and G is the total liquid absorption of the test powder.

[0044] In some embodiments, calculating the compacted density of the test powder includes:

[0045] The volume of the sample is calculated using the following formula:

[0046] V = S·(L-2l)

[0047] Wherein, V is the volume of the sample, S is the cross-sectional area of ​​the outer contour of the sample storage cavity projected on the projection plane perpendicular to the first direction, L is the distance between the ends of the two conductors extending out of the sample storage cavity along the first direction, and l is the length of the conductor along the first direction.

[0048] Based on the volume of the sample and the predetermined weight of the test powder, the compacted density of the test powder is calculated using the following formula:

[0049]

[0050] Wherein, ρ is the compacted density of the test powder, and A is the predetermined weight of the test powder.

[0051] In some embodiments, calculating the injection volume coefficient of the test powder includes:

[0052] Based on the volume of the sample, the porosity of the sample is calculated using the following formula:

[0053] δ=VV 导电剂 -V 粘结剂 -V 主料

[0054] Where δ is the porosity of the sample, V 导电剂 V is the true volume of the conductive agent in the test powder. 粘结剂 V is the true volume of the binder in the test powder.主料 It is the true volume of the main component in the tested powder;

[0055] Based on the porosity of the sample and the total liquid absorption of the test powder, the liquid injection coefficient of the test powder is calculated using the following formula:

[0056]

[0057] Wherein, ε is the liquid injection coefficient of the test powder, and G is the total liquid absorption of the test powder.

[0058] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the structure of a battery powder material wettability testing system according to an embodiment of this application.

[0060] Figure 2 This is a schematic flowchart of a battery powder material wettability testing method according to an embodiment of this application.

[0061] Figure 3 This is a schematic flowchart of a battery powder material wettability test method according to another embodiment of this application.

[0062] Figure 4 This is a schematic flowchart of a battery powder material wettability test method according to another embodiment of this application.

[0063] Figure 5 This is a diagram illustrating the wetting process of the test powder in the battery powder material wettability test method according to an embodiment of this application.

[0064] Figure 6 This is a graph showing the difference in wetting of the same (or different) test powders under different compaction densities in the battery powder material wettability test method according to the embodiments of this application.

[0065] Figure 7 This is a comparison chart of the maximum liquid absorption of different test powders when fully wetted in the battery powder material wettability test method according to the embodiments of this application.

[0066] Reference numerals: 1. Sample storage device; 11. Sample storage chamber; 12. Liquid injection channel; 2. Liquid injection assembly; 21. Liquid injector; 22. Liquid injection funnel; 3. Conductor; 4. Resistance tester; 5. Negative pressure chamber; 51. Negative pressure cavity; 6. Pressure gauge; 7. Terminal equipment. Detailed Implementation

[0067] The embodiments of this application are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0068] like Figure 1 As shown in the figure, a battery powder material wettability testing system according to an embodiment of this application includes a sample storage device 1, a liquid injection assembly 2, a conductor 3, and a resistance tester 4. The sample storage device 1 has a sample storage cavity 11 and a liquid injection channel 12 communicating with the sample storage cavity 11. The sample storage cavity 11 is open at both ends along a first direction and is suitable for loading test powder. The liquid injection channel 12 extends along a second direction and communicates with the liquid injection assembly 2 to inject electrolyte to wet the test powder. The second direction forms an angle with the first direction. There are two conductors 3, both of which are slidably connected to the sample storage cavity 11 along the first direction. The two conductors 3 correspond one-to-one with the two openings at both ends of the sample storage cavity 11 to seal the openings. The conductors 3 are suitable for connection to an external pressure device to compress the test powder into a sample. The conductors 3 abut against the sample and are electrically connected to the resistance tester 4 to measure the internal resistance of the sample.

[0069] It is understood that, according to the battery powder material wettability testing system of this application embodiment, the test powder can be filled into the sample storage cavity 11 through the opening of the sample storage device 1, and the conductor 3 can seal the opening and cooperate with the external pressure device to complete the compaction treatment of the test powder in the sample storage cavity 11 to obtain a sample. Afterwards, the connection between the conductor 3 and the external pressure device is disconnected, so that the conductor 3 is connected to the resistance tester 4, and the electrolyte is injected into the sample through the injection channel 12 through the liquid injection assembly 2 to perform wettability testing on the sample. During the process, the conductor 3 comes into contact with the sample, forming a closed loop between the sample, the two conductors 3, and the resistance tester 4. The resistance tester 4 measures the change in the internal resistance of the sample with the amount of liquid injected and the wetting time in real time. When the internal resistance of the sample no longer changes, it can be determined that the sample is completely wetted. Therefore, compared with related technologies, this application makes the testing process closer to the actual use state of the powder by testing the wetting performance of the compacted mixed powder. It can accurately determine whether the powder is completely wetted. The overall structure is simple, the test error is small, and the test cost is low.

[0070] Specifically, the sample storage chamber 11 can extend along a first direction. The first direction can be the left-right direction shown in the figure. The sample storage chamber 11 has openings at both ends along the first direction, that is, the sample storage chamber 11 extends through the sample storage device 1 along the first direction. The second direction can be the up-down direction shown in the figure. The liquid injection assembly 2 can be connected to an external electrolyte source, or the liquid injection assembly 2 can be a liquid injector 21, and the liquid outlet of the liquid injection assembly 2 is connected to the liquid injection channel 12. The conductor 3 slides with the opening of the sample storage chamber 11, that is, the cross-sectional area of ​​the conductor 3 is the same as the cross-sectional area of ​​the sample storage chamber 11. The conductor 3 is not limited to a conductive column (such as a copper column) or a conductive sheet. The conductor 3 has good conductivity and directly contacts the sample to transmit the sample resistance during sample wetting. The external pressure device is not limited to a hydraulic press. The external pressure device drives at least one of the two conductors 3 to slide along the first direction to squeeze the test powder in the sample storage chamber 11 and compress it into a sample with the required compaction density. Conductor 3 can be connected to resistance tester 4 via wires to transmit resistance data during sample immersion during testing.

[0071] It should be noted that in this application, the test powder is compacted to the required density to obtain a sample. By conducting a wettability test on the sample, the time requirement of the wettability process in the battery production process is evaluated, which is closer to the actual use state of the powder. Compared with related technologies, it does not require the powder to be coated into an electrode sheet, making the test method simple and the same as the actual application. At the same time, the sample in this application has a larger overall thickness than the electrode sheet in related technologies, so the test error is smaller and the test results are more accurate.

[0072] like Figure 1 As shown, in some embodiments, there are multiple injection channels 12 and multiple injection components 2, each corresponding to one of the injection channels 12.

[0073] Alternatively, the injection assembly 2 may have one component, and the test system may also include a distribution tube (not shown in the figure), which has an inlet end and multiple outlet ends. The outlet of the injection assembly 2 is connected to the inlet end of the distribution tube, and the multiple injection channels 12 are connected to the multiple outlet ends of the distribution tube in a one-to-one correspondence.

[0074] It is understandable that the structural design of injecting electrolyte into the sample by multiple injection components 2 or one injection component 2 through multiple injection channels 12 can improve the wettability test efficiency of battery powder materials, while achieving uniform injection of the sample and further ensuring the reliability of the test results.

[0075] It should be noted that the specific number of injection channels 12 and injection components 2 can be designed according to the specifications of the sample, etc., to ensure wettability and testing efficiency, which will not be elaborated here. In addition, while ensuring wettability of the sample, there can be only one injection channel 12 and one injection component 2. In this case, the injection channel 12 can be opened at the center of the sample storage device 1.

[0076] In some embodiments, a plurality of injection channels 12 are arranged in an array in the sample storage device 1 (not shown in the figure) to ensure injection uniformity.

[0077] like Figure 1 As shown, in some embodiments, the testing system further includes a negative pressure chamber 5, which has a negative pressure cavity 51, and the sample storage device 1 is located inside the negative pressure cavity 51 to test the wettability of the sample under negative pressure.

[0078] Understandably, since the liquid injection stage in the battery production process is carried out under negative pressure, placing the sample storage device 1 in the negative pressure chamber 51 for wettability testing can simulate the state of formal battery production. This not only makes the testing process closer to the actual state and improves the accuracy of the test results, but also verifies the differences in wettability of battery powder materials under different negative pressure states. This provides better guidance for controlling the relationship between battery powder materials and negative pressure during battery production, ensuring battery performance and achieving the goal of mass production, cost reduction, and energy consumption reduction.

[0079] It should be noted that this application can test the change in the wetting resistance of the same powder material under different negative pressures, calculate the wetting rate of the electrolyte under different pressures, and determine the liquid absorption amount when fully wetting is achieved based on the change in sample weight, thus analyzing the wetting effect of the powder material. It can also test the change in the wetting resistance of different powder materials under the same negative pressure to better guide the selection of battery powder materials.

[0080] like Figure 1 As shown, in some embodiments, the testing system also includes a barometer 6, which is connected to the negative pressure chamber 5 and is suitable for detecting the air pressure in the negative pressure chamber 51, so as to obtain the pressure in the negative pressure chamber 51 in real time and intuitively, which is conducive to timely adjustment of the negative pressure in the negative pressure chamber 51 and ensures the smooth progress of the testing process.

[0081] like Figure 1 As shown, in some embodiments, the injection assembly 2 includes an injector 21 and an injection funnel 22. The injector 21 is detachably connected to the negative pressure chamber 5. The outlet of the injector 21 is located in the negative pressure chamber 51 and communicates with the inlet of the injection funnel 22. The injection funnel 22 is located in the negative pressure chamber 51, and the outlet of the injection funnel 22 is connected to the injection channel 12.

[0082] It is understandable that the injector 21 is detachably connected to the negative pressure chamber 5, which facilitates the use of the injector 21 to draw electrolyte to supply electrolyte to the sample. Under the pressure difference between the negative pressure chamber 51 and the outside, the electrolyte in the injector 21 can automatically flow into the injection funnel 22, and then be injected into the injection channel 12 through the injection funnel 22, ensuring the consistency of the injection rate and saving time and effort.

[0083] Specifically, the injector 21 is not limited to a syringe. The cross-sectional area of ​​the inlet of the injection funnel 22 is larger than the cross-sectional area of ​​the outlet to avoid leakage during the injection process. The outlet of the injection funnel 22 is also inserted into the injection channel 12.

[0084] like Figure 1 As shown, in some embodiments, on the projection plane perpendicular to the first direction, the outer contour of the projection of the sample storage cavity 11 can be one of a circle, a polygon, and an arbitrary closed curve. Preferably, the outer contour of the projection of the sample storage cavity 11 is a circle, and the conductor 3 is a cylindrical conductive column, which facilitates the calculation of the sample volume in the later stage and also ensures the smooth sliding of the conductor 3 at the opening of the sample storage cavity 11, so that the sample is subjected to uniform force during the pressing process, and further improves the accuracy of the test results.

[0085] For example, taking the sample storage cavity 11 as cylindrical (i.e., a tube open at both ends) as an example, its inner diameter can be from 1 cm to 3 cm. In the sample storage device 1, multiple injection channels 12 can be arranged at equal intervals along the extension direction of the sample storage cavity 11.

[0086] like Figure 1 As shown, in some embodiments, the inner peripheral wall of the sample storage cavity 11 is coated with a corrosion-resistant material, or the sample storage device 1 is made of a corrosion-resistant material, so as to effectively avoid corrosion problems caused to the sample storage cavity 11 during the wettability test and ensure the service life of the sample storage device 1.

[0087] Specifically, corrosion-resistant materials are not limited to polytetrafluoroethylene.

[0088] like Figure 1 As shown, in some embodiments, the testing system further includes a terminal device 7, which is electrically connected to the resistance tester 4. The terminal device 7 is used to record and process the test data from the resistance tester 4 to further improve the automation performance of the testing system. This facilitates the rapid analysis and acquisition of the wetting properties of battery powder materials, providing guidance for battery research. The terminal device 7 can be a computer.

[0089] like Figure 2 As shown, an embodiment of this application provides a method for testing the wettability of battery powder materials, based on the battery powder material wettability testing system of any of the above embodiments. The testing method includes the following steps:

[0090] Step S01: A predetermined weight of test powder is loaded into the sample storage chamber 11, and the opening of the sample storage chamber 11 is sealed by the conductor 3. The predetermined weight of powder can be obtained by weighing (the predetermined weight can be determined according to the amount of sample loaded into the sample storage chamber 11).

[0091] In step S02, pressure is applied to the conductor 3 by an external pressure device, and the conductor 3 slides along the first direction and squeezes the test powder to press out the sample.

[0092] Step S03: Connect the conductor 3 to the resistance tester 4 electrically, and inject electrolyte into the sample through the injection channel 12 by the injection component 2 to obtain the change of the sample's internal resistance with the injection volume and immersion time.

[0093] Step S04: Calculate the total liquid absorption, wetting rate, compaction density, and liquid injection coefficient (or liquid injection parameter) of the test powder.

[0094] The technical advantages of the battery powder material wettability testing method according to the embodiments of this application are the same as the technical advantages of the battery powder material wettability testing system described above, and will not be repeated here.

[0095] It should be noted that, compared with related technologies, this application has the following advantages:

[0096] 1) By simply mixing and compacting the extreme powder, wetting performance testing is conducted, which is closer to the actual use state of the powder. At the same time, it is not necessary to coat the extreme powder into an electrode sheet. The testing method is simple and the same as the actual application, thus reducing testing costs.

[0097] 2) This application can not only test the wetting rate, but also accurately determine whether the test powder is completely wetted by real-time monitoring of the internal resistance of the sample made of the test powder, thus solving the error problem;

[0098] 3) This application can calculate the total liquid absorption, wetting rate, compaction density and liquid injection coefficient when the test powder is fully wetted.

[0099] Therefore, the method for testing the wettability of battery powder materials in this application is highly advanced and can meet the current requirements for wettability research of electrode sheets in battery manufacturing, assess the time requirements of the wettability process in battery production, and evaluate the wettability differences of materials at the battery material end, as well as the relationship between battery materials and compaction, so as to better guide material and battery research.

[0100] like Figure 3 As shown, in some embodiments, before step S03, the method further includes:

[0101] In step S02', the sample storage device 1 is placed in the negative pressure chamber 51, and the air pressure in the negative pressure chamber 51 is kept at the set negative pressure so that the entire test process can be carried out under the same pressure conditions, ensuring the reliability of the test results.

[0102] like Figure 4 As shown, in some embodiments, before step S01, the method further includes step S00, preparing test powder.

[0103] Therefore, in some embodiments of this application, the battery powder material wettability testing method includes steps S01, S02, S03, and S04; in other embodiments, the battery powder material wettability testing method includes steps S01, S02, S02', S03, and S04; and in still other embodiments, the battery powder material wettability testing method includes steps S00, S01, S02, S02', S03, and S04. Therefore, the battery powder material wettability testing method of this application can be any of the three methods described above.

[0104] In some embodiments, step S00 includes:

[0105] Step S001: Mix the main material, conductive agent and binder according to the design ratio and homogenize them to obtain a mixed slurry solvent;

[0106] Step S002: Dry the solvent in the mixed slurry to obtain a solid slurry;

[0107] Step S003: The solid slurry is crushed to produce test powder.

[0108] In some embodiments, the total liquid absorption of the test powder is calculated using formula (1):

[0109] G=G′-G0 (1)

[0110] Where G is the total amount of liquid absorbed by the test powder, G′ is the total weight of the sample storage device 1, the sample and the two conductors 3 when the sample is fully wetted, and G0 is the total weight of the sample storage device 1, the sample and the two conductors 3 before the sample is wetted.

[0111] It should be noted that the total weight G′ of the sample storage device 1, the sample, and the two conductors 3 when the sample is fully immersed, and the total weight G0 of the sample storage device 1, the sample, and the two conductors 3 before the sample is immersed, can be obtained by weighing (e.g., using an electronic scale).

[0112] In some embodiments, calculating the wetting rate of the test powder includes:

[0113] Step S041, calculate the wetting time of the test powder using formula (2):

[0114] Δt=t1-t0 (2)

[0115] Where Δt is the wetting time of the test powder, t1 is the complete wetting time when the internal resistance of the sample no longer changes with time, and t0 is the initial time of injecting the sample with electrolyte.

[0116] Step S042, based on the wetting time of the test powder and the total liquid absorption of the test powder, the wetting rate of the test powder is calculated using formula (3):

[0117]

[0118] Where v is the wetting rate of the test powder, and G is the total liquid absorption of the test powder.

[0119] In some embodiments, calculating the compacted density of the test powder includes:

[0120] Step S041', calculate the sample volume using formula (4):

[0121] V=S·(L-2l) (4)

[0122] Where V is the volume of the sample, S is the cross-sectional area of ​​the outer contour of the sample storage cavity 11 projected on the projection plane perpendicular to the first direction (the cross-sectional area S can be set accordingly during the initial design and manufacturing of the sample storage device 1 for easy calculation in later use), L is the distance between the ends of the two conductors 3 extending out of the sample storage cavity 11 along the first direction, and l is the length of the conductors 3 along the first direction. In addition, the distance L and the length l of the conductors 3 can be measured by means of measuring ruler, laser rangefinder, etc.

[0123] Step S042': Based on the sample volume and the predetermined weight of the test powder, calculate the compaction density of the test powder using formula (5):

[0124]

[0125] Where ρ is the compaction density of the test powder, and A is the predetermined weight of the test powder (the predetermined weight A can be determined based on the amount of sample loaded in the sample storage chamber 11, and the predetermined weight of powder can be obtained by weighing methods such as electronic scales).

[0126] In some embodiments, calculating the injection volume coefficient of the test powder includes:

[0127] Step S041": Based on the sample volume, calculate the sample porosity using formula (6):

[0128] δ=VV 导电剂 -V 粘结剂 -V 主料 (6)

[0129] Where δ is the porosity of the sample, V 导电剂 It is used to test the true volume of the conductive agent in the powder, V 粘结剂 It is used to test the true volume of the binder in the powder, V 主料 It tests the true volume of the main component in the powder.

[0130] Step S042”, based on the porosity of the sample and the total liquid absorption of the test powder, calculate the liquid injection coefficient of the test powder using formula (7):

[0131]

[0132] Where ε is the injection volume coefficient of the test powder, and G is the total liquid absorption of the test powder.

[0133] It should be noted that the true volume of the conductive agent, the true volume of the binder, and the true volume of the main material can all be measured by existing true volume testing instruments, which are existing technologies in this field, and therefore will not be described in detail.

[0134] In addition, by using the above-mentioned battery powder material wettability test method, the following can be obtained:

[0135] like Figure 5 The diagram shown illustrates the wetting process of the test powder. As the wetting process progresses, the resistance of the sample changes over time. When the resistance of the sample no longer changes over time, it can be determined that the sample has been completely wetted under the given conditions (i.e., the wetting time and the amount of liquid injected).

[0136] like Figure 6 The graph shows the difference in wetting of the same (or different) test powders under different compaction densities. As can be seen from the graph, the higher the compaction density, the longer the wetting time.

[0137] like Figure 7 The diagram shows a comparison of the maximum liquid absorption of different test powders when fully wetted. Test powder A is NCM-1, test powder B is NCM-2, and test powder C is NCM-3, for example. In other words, taking a ternary lithium battery as an example, the test powder can be a nickel-cobalt-manganese ternary cathode active material. The electrolyte used when wetting different test powders is as follows: LiPF6 is dissolved in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DMC) (volume ratio EC:DMC = 1:1) to obtain a LiPF6 solution with a concentration of 1 mol / L.

[0138] The working process of this battery powder material wettability testing system will now be explained, based on its specific structure:

[0139] 1) Ingredient preparation: Mix the test samples according to the battery design formula by weight:

[0140] Ternary system formulation: 97.5% LiNi 0.8 Mn 0.1 Co 0.1 O2: 0.5% Super P: 2% PVDF;

[0141] Lithium iron phosphate system formulation: 97.2% LiFePO4: 0.7% Super P: 2% PVDF: 0.1% PVP;

[0142] And the negative electrode system formulation: 96% graphite: 1.5% Super P: 1% CMC: 1.5% SBR;

[0143] 2) Homogenize the mixture according to the above mixing ratio until it is evenly mixed;

[0144] 3) Baking: Dry the mixed slurry. After drying, use a mortar and pestle (or knead into) small pieces or powder.

[0145] 4) Weigh a certain amount of test powder (which can be determined according to the sample loading amount), and use a reagent spoon to load the test powder into the sample storage chamber 11 of the sample storage device 1.

[0146] 5) Assembly: Insert the copper columns into the openings at both ends of the cylindrical sample storage cavity 11, and prepare for tableting;

[0147] 6) Compacting: Compact the test powder to the required density (g / cm³). 3 The sample is pressed out by pressing two copper columns with a hydraulic press, and then the copper columns are fixed. Since the inner diameter of the sample storage chamber 11 is fixed, the compaction density can be determined according to the distance between the two copper columns.

[0148] 7) Transfer: Place the prepared sample, along with the copper column and sample storage device 1, into the negative pressure chamber 5, and connect it to the copper column using a wire.

[0149] 8) Assemble the sample by taking the injection device 21 and fixing it onto the sample storage device 1;

[0150] 9) Seal and close the negative pressure chamber 5, and then use the injector 21 to take the electrolyte (dissolve LiPF6 in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DMC) (volume ratio EC:DMC=1:1) to obtain a LiPF6 solution with a concentration of 1mol / L) and place it in the fixed position of the negative pressure chamber 5.

[0151] 10) Test: Open the negative pressure to the required test pressure and detect the change in resistance. When the negative pressure is activated, the electrolyte in the injector 21 will automatically flow into the injection funnel 22. Alternatively, the electrolyte in the injector 21 can be manually injected into the injection funnel 22.

[0152] 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", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship 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.

[0153] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0154] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0155] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0156] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0157] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A battery powder material wettability testing system, characterized in that, include: The sample storage device (1) and the liquid injection assembly (2) are provided. The sample storage device (1) has a sample storage cavity (11) and a liquid injection channel (12) communicating with the sample storage cavity (11). The sample storage cavity (11) is open at both ends along a first direction and is suitable for loading test powder. The liquid injection channel (12) extends along a second direction and communicates with the liquid injection assembly (2) so as to inject electrolyte to wet the test powder. The second direction forms an angle with the first direction. Conductors (3), two of which are slidably connected to the sample storage cavity (11) along the first direction, the two conductors (3) corresponding one-to-one with the openings at both ends of the sample storage cavity (11) to seal the openings, the conductors (3) being adapted to be connected to an external pressure device to compress the test powder into a sample; and A resistance tester (4) is used to measure the internal resistance of the sample, wherein the conductor (3) is in contact with the sample and electrically connected to the resistance tester (4).

2. The battery powder material wettability testing system according to claim 1, characterized in that, There are multiple injection channels (12), and there are multiple injection components (2) that correspond one-to-one with each injection channel (12); Alternatively, the injection component (2) may be one, and the test system may also include a liquid distribution tube, which has an inlet end and multiple outlet ends. The outlet of the injection component (2) is connected to the inlet end of the liquid distribution tube, and the multiple injection channels (12) are connected to the multiple outlet ends of the liquid distribution tube in a one-to-one correspondence.

3. The battery powder material wettability testing system according to claim 1 or 2, characterized in that, It also includes a negative pressure chamber (5), which is provided with a negative pressure cavity (51), and the sample storage device (1) is located in the negative pressure cavity (51) so as to test the wettability of the sample under negative pressure.

4. The battery powder material wettability testing system according to claim 3, characterized in that, The injection assembly (2) includes an injector (21) and an injection funnel (22). The injector (21) is detachably connected to the negative pressure chamber (5). The outlet of the injector (21) is located in the negative pressure chamber (51) and communicates with the inlet of the injection funnel (22). The injection funnel (22) is located in the negative pressure chamber (51), and the outlet of the injection funnel (22) is connected to the injection channel (12).

5. A method for testing the wettability of battery powder materials, based on the battery powder material wettability testing system as described in any one of claims 1-4, characterized in that, Includes the following steps: A predetermined weight of test powder is loaded into the sample storage chamber (11), and the opening of the sample storage chamber (11) is sealed by a conductor (3); Pressure is applied to the conductor (3) by an external pressure device, and the conductor (3) slides along the first direction and squeezes the test powder to press out the sample; The conductor (3) is electrically connected to the resistance tester (4), and the electrolyte is injected into the sample through the injection channel (12) by the injection assembly (2) to obtain the change of the internal resistance of the sample with the injection volume and immersion time. Calculate the total liquid absorption, wetting rate, compaction density, and liquid injection coefficient of the test powder.

6. The method for testing the wettability of battery powder materials according to claim 5, characterized in that, Before the step of electrically connecting the conductor (3) to the resistance tester (4), injecting electrolyte into the sample through the injection channel (12) by the injection assembly (2), and obtaining the change of the internal resistance of the sample with the injection volume and immersion time, the method further includes: Place the sample storage device (1) in the negative pressure chamber (51) and maintain the air pressure of the negative pressure chamber (51) at the set negative pressure.

7. The method for testing the wettability of battery powder materials according to claim 5, characterized in that, The total liquid absorption of the test powder is calculated using the following formula: G = G′ - G0 Wherein, G is the total amount of liquid absorbed by the test powder, G′ is the total weight of the sample storage device (1), the sample and the two conductors (3) when the sample is fully wetted, and G0 is the total weight of the sample storage device (1), the sample and the two conductors (3) before the sample is wetted.

8. The method for testing the wettability of battery powder materials according to claim 7, characterized in that, The calculation of the wetting rate of the test powder includes: The wetting time of the test powder is calculated using the following formula: Δt=t1-t0 Wherein, Δt is the wetting time of the test powder, t1 is the complete wetting time when the internal resistance of the sample no longer changes with time, and t0 is the initial time of injecting electrolyte into the sample. Based on the wetting time and the total liquid absorption of the test powder, the wetting rate of the test powder is calculated using the following formula: Where v is the wetting rate of the test powder, and G is the total liquid absorption of the test powder.

9. The method for testing the wettability of battery powder materials according to claim 7 or 8, characterized in that, The calculation of the compacted density of the test powder includes: The volume of the sample is calculated using the following formula: V = S·(L-2l) Wherein, V is the volume of the sample, S is the cross-sectional area of ​​the outer contour of the sample storage cavity (11) projected on the projection plane perpendicular to the first direction, L is the distance between the ends of the two conductors (3) extending out of the sample storage cavity (11) along the first direction, and l is the length of the conductor (3) along the first direction. Based on the volume of the sample and the predetermined weight of the test powder, the compacted density of the test powder is calculated using the following formula: Wherein, ρ is the compacted density of the test powder, and A is the predetermined weight of the test powder.

10. The method for testing the wettability of battery powder materials according to claim 9, characterized in that, The calculation of the injection volume coefficient of the test powder includes: Based on the volume of the sample, the porosity of the sample is calculated using the following formula: δ=VV 导电剂 -V 粘结剂 -V 主料 Where δ is the porosity of the sample, V 导电剂 V is the true volume of the conductive agent in the test powder. 粘结剂 V is the true volume of the binder in the test powder. 主料 It is the true volume of the main component in the tested powder; Based on the porosity of the sample and the total liquid absorption of the test powder, the liquid injection coefficient of the test powder is calculated using the following formula: Wherein, ε is the liquid injection coefficient of the test powder, and G is the total liquid absorption of the test powder.

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