Electrochemical impedance testing device for soft package battery

Abstract

The utility model discloses a kind of electrochemical impedance testing devices for soft package battery, it is related to lithium ion battery testing technical field, including base, clamping plate, pressure display, test fixture, fixture outer lead and initiative pole, the four corners of the base are slidably connected with guide pillar respectively, the top of multiple guide pillars is equipped with the clamping plate parallel to base, the clamping plate is equipped with pressure display, the base is provided with multiple test fixtures, multiple test fixture tail end is equipped with fixture outer lead, the initiative pole lower end is in the center of the base, the initiative pole upper end is rotatably connected on clamping plate, the utility model can reduce the contact resistance between fixture and battery when testing impedance and the internal resistance of fixture itself;By moving the clamping groove, the pole lug of different spacing can be connected, to avoid the battery pole lug excessive distortion;Reduce test error, improve the repeatability and consistency of test result.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion battery testing technology, and in particular to a device for improving the electrochemical impedance testing of pouch batteries. Background Technology

[0002] With the rapid development of new energy storage technologies such as lithium-ion batteries and solid-state batteries, battery performance evaluation and failure analysis have become increasingly complex. Traditional DC testing methods (such as charge-discharge cycling and polarization testing) can reflect the overall performance of the battery, but they struggle to distinguish the contributions of different internal processes (such as charge transfer, diffusion, and interface reactions). In contrast, EIS (Electronic Information System) can obtain rich kinetic information without damaging the battery structure by applying small AC signals (typically on the order of mV), thus becoming an indispensable tool in battery research. The main advantages are as follows:

[0003] 1. Assess the health of the battery.

[0004] During long-term use, the internal materials of a battery gradually age, such as electrolyte decomposition, electrode active material decay, and SEI film (solid electrolyte interface film) thickening. These changes alter the battery's impedance characteristics. EIS testing allows monitoring of impedance changes at different frequencies, thereby assessing the battery's health, predicting its remaining lifespan, and mitigating the risks associated with sudden performance degradation.

[0005] 2. Analyze the internal dynamics of the battery.

[0006] EIS testing can distinguish different kinetic processes within a battery, such as charge transfer resistance, diffusion impedance, and ohmic impedance. High-frequency impedance typically reflects the ohmic resistance at the electrolyte-electrode interface, mid-frequency impedance corresponds to charge transfer processes, and low-frequency impedance is related to ion diffusion. By analyzing these parameters, the battery's polarization characteristics, reaction rate, and the presence of potential safety hazards such as lithium dendrite growth can be determined.

[0007] 3. Optimize design and diagnose faults.

[0008] During the battery development phase, EIS can help researchers assess the impact of different electrode materials, electrolyte formulations, and separator performance. Meanwhile, during battery use, problems such as internal short circuits, electrolyte drying, and electrode material detachment may occur, all of which will lead to impedance changes. EIS can quickly identify abnormal battery conditions.

[0009] 4. Improve the accuracy of the battery management system (BMS).

[0010] Modern battery management systems require real-time monitoring of battery status, and EIS data can provide more accurate battery parameters (such as internal resistance and capacity degradation). By combining EIS testing, the BMS can more accurately estimate the battery's state of charge (SOC) and state of health (SOH), thereby improving the efficiency and safety of battery pack balancing management.

[0011] However, current electrochemical workstation interfaces generally use screws for tightening or external alligator clips for fixation. Pouch cells, on the other hand, have softer tabs, and the tab spacing varies between different battery models. Traditional fixtures cannot adapt to the varying tab spacing of different pouch cell specifications, leading to frequent fixture changes during testing and impacting testing efficiency. Furthermore, existing fixtures are typically designed for hard-shell batteries and cannot accommodate the inconsistent shapes of pouch cells, easily causing batteries to slip or become unstable. In addition, inconsistent spacing can cause excessive twisting of the tabs, affecting the structural stability of the tab welding area, resulting in unstable contact resistance and impacting the reliability of precision tests such as electrochemical impedance spectroscopy. Utility Model Content

[0012] The purpose of this invention is to address the shortcomings of existing technologies by proposing an electrochemical impedance spectroscopy device for soft-pack batteries.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] Based on the above problems, this utility model designs an electrochemical impedance testing device for soft-pack batteries, including a base, a clamping plate, a pressure display, a test fixture, external leads of the fixture, and an active rod. The base is provided with guide posts at the four corners, and the top of the multiple guide posts is provided with a clamping plate parallel to the base. A pressure display is placed in the middle of the clamping plate. The base is provided with multiple test fixtures. The lower end of the active rod is rotatably connected to the base, and the upper end of the active rod is threadedly connected to the clamping plate.

[0015] Preferably, the base is provided with a slide rail, and the test fixture is slidably connected to the slide rail.

[0016] Preferably, the test fixture includes a positive electrode fixture, a reference fixture, and a negative electrode fixture, and multiple test fixtures are detachable.

[0017] Preferably, multiple of the test fixtures are made of gold-plated copper.

[0018] Preferably, the slide rail includes a track, mounting holes, studs, and nuts. The mounting holes are evenly distributed on the track, the studs are installed between the test fixture and the track, and the nuts are installed on the studs to lock the test fixture 5.

[0019] Preferably, the plurality of test fixtures include a spring, an upper clamping plate, a lower clamping plate, and a pressure sensor. The spring is connected between the upper clamping plate and the lower clamping plate. The pressure sensor is located at the bottom of the upper clamping plate. The lower clamping plate has positioning holes and is fixed to the track by mounting holes and studs.

[0020] Compared with the prior art, the advantages of this utility model are:

[0021] 1. The device of this patent avoids the phenomenon of electrode twisting and bending during the testing of soft-pack batteries, which is conducive to the stable and reliable operation of the test; at the same time, it ensures that the electrode will not fall off during the test, reduces the influence of the fixture on the contact resistance, and improves the repeatability and consistency of the test.

[0022] 2. Positioning the battery tabs using a slide rail prevents excessive twisting or bending of the battery tabs during testing, thus ensuring stable and reliable testing operation;

[0023] 3. The clamp has a micro-convex structure, which provides a large clamping force, reduces the size of the electrode tabs, and lowers the contact resistance, thus reducing factors that may affect the test.

[0024] 4. The device is simple and easy to operate. When alternating test items, the battery does not need to be frequently removed, reducing test errors. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of this utility model.

[0026] Figure 2 This is a schematic diagram of the structure of this utility model from another angle.

[0027] Figure 3 This is a partially enlarged view of the present invention.

[0028] Figure 4 This is an enlarged view of the test fixture of this utility model.

[0029] Figure 5 This is a top view of the present invention.

[0030] Figure 6 This is a result diagram of Comparative Example 1 proposed in this utility model.

[0031] Figure 7 This is a result diagram of Embodiment 1 proposed in this utility model.

[0032] Figure 8 This is a result diagram of Embodiment 2 proposed in this utility model.

[0033] In the diagram: 1. Base, 2. Guide post, 3. Clamping plate, 4. Pressure display, 5. Test fixture, 51. Positive clamp, 52. Reference clamp, 53. Negative clamp, 510. Spring, 520. Lower clamping plate, 530. Upper clamping plate, 540. Sensor, 6. Clamping lead wire, 7. Slide rail, 710. Mounting hole, 720. Stud, 730. Nut, 740. Rail, 8. Drive rod. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0035] like Figure 1-3 As shown, an electrochemical impedance spectroscopy (EIS) testing device for soft-pack batteries includes a base 1, a clamping plate 3, a pressure display 4, test fixtures 5, external leads 6, and an active rod 8. The base 1 has guide posts 2 at its four corners, and the tops of the guide posts 2 are provided with clamping plates 3 parallel to the base 1. The pressure display 4 is placed on the clamping plates 3. The base 1 is equipped with multiple test fixtures 5, and the tail ends of the multiple test fixtures 5 are provided with external leads 6. The lower end of the active rod 8 is rotatably connected to the base 1, and the upper end of the active rod 8 is threadedly connected to the clamping plate 3. When the active rod 8 is rotated, the four guide posts 2 will synchronously displace, and the height of the clamping plate 3 can be adjusted to a suitable position through this transmission mechanism.

[0036] The base 1 is provided with a slide rail 7, and the test fixture 5 is slidably connected to the slide rail 7, so that the test fixture 5 can be adjusted to a suitable position.

[0037] The test fixture 5 includes a positive electrode fixture 51, a reference fixture 52, and a negative electrode fixture 53, and the plurality of the test fixtures are detachable.

[0038] The test fixtures 5 are made of gold-plated copper, which has excellent electrical conductivity and abrasion resistance.

[0039] The slide rail 7 includes a track 740, mounting holes 710, studs 720, and nuts 730. The mounting holes 710 are evenly distributed on the track 740. The studs 720 are installed between the test fixture 5 and the track 740, and the nuts 730 are fitted onto the studs 720. When the test fixture 5 moves and adjusts its position on the slide rail 7, it can be fixed by: passing the studs 720 through the corresponding mounting holes 710 on the test fixture 5 and the track 740, and then screwing the nuts 730 onto the studs 720. The threaded engagement locks the test fixture 5 in place on the guide rail.

[0040] The multiple test fixtures 5 include a spring 510, an upper clamping plate 530, a lower clamping plate 520, and a pressure sensor 540. The spring 510 connects the upper clamping plate 530 and the lower clamping plate 520. The pressure sensor 540 is located at the bottom of the upper clamping plate 530. The lower clamping plate 520 has mounting holes 710 and studs 720, which are used to fix the lower clamping plate 520 to the track 740. The studs 720 pass through the positioning holes 550, and their threaded sections engage with the nuts 730. Rotating the nuts 730 locks the test fixtures 5 in place. The elastic deformation of the spring 510 allows the upper clamping plate 530 and the lower clamping plate 520 to generate a clamping force on the object being tested, ensuring that the object is stably fixed during the test and preventing test data deviation due to loosening. The pressure sensor 540 can sense the pressure value applied by the upper clamping plate 530 to the object being tested in real time and feed the value back to the pressure display 4.

[0041] The working principle is as follows: First, place the testing device on the insulating base to ensure stability. Rotate the active rod 8 to drive the four corner guide posts 2 to slide up and down synchronously, thereby adjusting the height of the clamping plate 3 so that the distance between the clamping plate 3 and the base 1 matches the thickness of the soft-pack battery being tested. Place the soft-pack battery on the base 1, and press down to fix the battery by adjusting the clamping plate 3 to ensure that the battery will not shift during the test. The slide rail 7 on the base 1 can slide the test fixture 5 along the track 740. According to the position and spacing of the battery tabs, adjust the positive clamp 51, reference clamp 52, and negative clamp 53 to the appropriate positions. After adjustment, use the stud 720 to pass through the mounting hole 710 on the track 740 and tighten the nut 730 to fix the test fixture 5 on the slide rail 7. A spring 510 inside the test fixture 5 connects the upper clamping plate 530 and the lower clamping plate 520. Through the elastic deformation of the spring 510, the upper clamping plate 530 and the lower clamping plate 520 clamp the battery tabs. A pressure sensor 540 at the bottom of the upper clamping plate 530 senses the clamping force in real time and feeds the pressure value back to the pressure display 4 on the clamping plate 3, ensuring that the clamping force is uniform and moderate, and preventing excessive twisting or loosening of the tabs. The device is connected to external electrochemical testing equipment via the fixture's external leads 6 to obtain the battery's impedance data.

[0042] Comparative Example 1:

[0043] Prepare two sets of pouch cells, labeled A and B. Connect the cells to the instrument using a standard clamp. Then, use the software of the electrochemical workstation to set the upper limit frequency of the load to 1000Hz and the lower limit frequency to 0.1Hz. Select the voltage perturbation based on the principle of AC impedance. After each test, remove the cells and reconnect the clamps. Test each type of cell three times. Record the results as A-1, A-2, A-3, B-1, B-2, and B-3. Analyze the overlap of the three Nyquist spectra.

[0044] Example 1:

[0045] Prepare two sets of pouch cells, labeled a and b. Connect the cells to the instrument using this device. Then, use the software of the electrochemical workstation to set the upper limit frequency of the load to 1000Hz and the lower limit frequency to 0.1Hz. Select the voltage perturbation based on the principle of AC impedance. After each test, remove the cells and reconnect the clamps. Test each type of cell three times. Record the results as a-1, a-2, a-3, b-1, b-2, and b-3. Analyze the overlap of the three Nyquist spectra.

[0046] Example 2:

[0047] Prepare two sets of pouch cells, denoted as m and n. First, connect the cells to the instrument using a standard clamp and perform the test using an electrochemical workstation. Record the results as m-1 and n-1. After the test, connect the cells to the instrument using this device and perform the test again using an electrochemical workstation. Record the results as m-2 and n-2. Compare the results with the Nyquist spectra analysis.

[0048] Comparative Example 1 Results Reference Figure 6 :

[0049] The statistical results of Comparative Example 1 show that, under the three repeated tests, the Nyquist spectrum curves of each battery group (A and B) have poor overlap and poor data consistency, indicating that the data from the three tests are greatly affected by fixture factors.

[0050] Example 1 Results Reference Figure 7 :

[0051] The statistical results from Example 1 show that, under the three repeated tests, the Nyquist spectrum curves of each battery group (a and b) have a high degree of overlap and good data consistency, indicating that the data from the three tests are less affected by fixture factors.

[0052] Example 2 Results Reference Figure 8 :

[0053] The statistical results from Example 2 show that, under different fixture testing conditions, the impedance of the test results of the two groups of batteries, m and n, is smaller than that of the ordinary fixture, indicating that the impedance of the device has little impact on the battery test.

[0054] Results Analysis: Based on the test results of Comparative Example 1, Example 1 and Example 2, it can be seen that the device provided in this patent can effectively ensure the stability of the test, improve the repeatability and consistency of the test results, and at the same time, the contact resistance is small and has little impact on the test results.

[0055] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. An electrochemical impedance spectroscopy device for soft-pack batteries, characterized in that: The device includes a base (1), a clamping plate (3), a pressure display (4), a test fixture (5), a fixture lead wire (6), and an active rod (8). The base (1) has guide posts (2) at its four corners. The top of the multiple guide posts (2) is slidably connected to a clamping plate (3) parallel to the base (1). The clamping plate (3) is equipped with a pressure display (4). The base (1) is provided with multiple test fixtures (5). The tail end of the multiple test fixtures (5) is provided with a fixture lead wire (6). The lower end of the active rod (8) is rotatably connected to the base (1), and the upper end of the active rod (8) is threadedly connected to the clamping plate (3).

2. The electrochemical impedance spectroscopy device for soft-pack batteries according to claim 1, characterized in that: The base (1) is provided with a slide rail (7), and the test fixture (5) is slidably connected to the slide rail (7).

3. The electrochemical impedance spectroscopy device for soft-pack batteries according to claim 1, characterized in that: The test fixture (5) includes a positive electrode fixture (51), a reference fixture (52), and a negative electrode fixture (53).

4. The electrochemical impedance spectroscopy device for soft-pack batteries according to claim 1, characterized in that: The test fixtures (5) mentioned above are made of copper plated with gold.

5. The electrochemical impedance spectroscopy device for a soft-pack battery according to claim 2, characterized in that: The slide rail (7) includes a track (740), mounting holes (710), studs (720), and nuts (730). The mounting holes (710) are evenly distributed on the track (740). The studs (720) are installed between the test fixture (5) and the track (740). The nuts (730) are installed on the studs (720) and lock the test fixture (5).

6. The electrochemical impedance spectroscopy device for a soft-pack battery according to claim 3, characterized in that: The multiple test fixtures (5) include a spring (510), an upper clamping plate (530), a lower clamping plate (520), and a pressure sensor (540). The spring (510) is connected between the upper clamping plate (530) and the lower clamping plate (520). The pressure sensor (540) is located at the bottom of the upper clamping plate (530). The lower clamping plate (520) is provided with multiple positioning holes (550). The lower clamping plate (520) is fixed on the track (740) through mounting holes (710) and studs (720).

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