Detection method and device for testing crosstalk characteristic of lithium battery

Abstract

The invention provides a detection method and device for testing crosstalk characteristics of a lithium battery, and belongs to the field of lithium battery detection. Comprising the following steps: respectively assembling two button type half cells by adopting positive and negative electrode materials, and assembling a full cell by adopting the same positive and negative electrode materials; after the electrode shells of the metal lithium sheet counter electrodes of the two button type half cells are electrically connected, a first charge-discharge test is carried out; carrying out charge and discharge test on the full battery by adopting the same charge and discharge test parameters, and eliminating the overpotential of the two button type half batteries; and evaluating the crosstalk degree of the lithium battery based on the test data of the total battery and the two button type half batteries. According to the method, the crosstalk between the pole pieces in the lithium battery is isolated through the reverse series operation, the crosstalk characteristic of the lithium battery is tested, the detection efficiency is improved, the understanding of people on the crosstalk characteristic can be effectively deepened, and a scientific basis is provided for quality control in the battery production process.

Description

Technical Field

[0001] The present invention belongs to the field of lithium battery detection, and in particular relates to a detection method and device for testing crosstalk characteristics of lithium batteries. Background Art

[0002] As a key technology in today's energy storage field, lithium batteries are widely used in electric vehicles, consumer electronics, and energy storage devices. However, with the increase in battery energy density and the complexity of usage scenarios, the crosstalk phenomenon inside lithium batteries has gradually become one of the important issues affecting their performance and safety. The so-called crosstalk refers to the transition metals in the positive and negative electrodes or the gases generated by the reaction passing through the battery separator and entering the other electrode, which has an adverse effect on the normal operation of the battery. This phenomenon gradually appears during the long electrochemical reaction process, posing a serious threat to battery life, performance, and safety.

[0003] During the operation of lithium batteries, the positive and negative electrode materials often produce unstable metal ions or byproducts due to electrochemical reactions. These substances migrate to the opposite electrode through the diaphragm, causing adverse reactions in the electrode materials. For example, the dissolution and migration of the positive transition metal will cause side reactions in the negative electrode, resulting in uneven growth of the solid electrolyte interface (SEI) film, which in turn affects the cycle life and capacity retention of the battery. At the same time, the generation and transmembrane transmission of gas will also affect the pressure balance inside the battery, increasing safety risks such as explosion and fire.

[0004] The existence of crosstalk will not only destroy the electrochemical balance of the battery, causing rapid capacity decay, but also increase the internal resistance of the battery, reduce the charging and discharging efficiency, and in severe cases may even cause catastrophic consequences such as thermal runaway. Therefore, how to effectively suppress the crosstalk problem between the positive and negative electrodes has become an important topic in the research of lithium battery technology.

[0005] Although there are some technical means to reduce crosstalk, such as optimizing the stability of electrode materials or improving the selectivity of separators, there are still many challenges to completely solve this problem. The industry's understanding of the crosstalk characteristics of lithium batteries is not deep enough, and most crosstalk detection methods have high requirements for equipment and cannot meet the needs of fast and simple detection. Summary of the invention

[0006] To solve the above problems, the present invention provides a detection method and device for testing the crosstalk characteristics of lithium batteries. The crosstalk between the pole pieces in the lithium battery is isolated by reverse series operation, and its crosstalk characteristics are tested. This method not only improves the detection efficiency, but also effectively deepens people's understanding of the crosstalk characteristics, and provides a scientific basis for quality control in the battery production process.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] On the one hand, the present invention provides a detection method for testing the crosstalk characteristics of a lithium battery, comprising the following steps: assembling two button-type half-cells using positive and negative electrode materials respectively, and assembling a full battery using the same positive and negative electrode materials; conducting an initial charge and discharge test after electrically connecting the electrode shells of the metal lithium sheets of the two button-type half-cells to the electrodes; conducting a charge and discharge test on the full battery using the same charge and discharge test parameters to eliminate the overpotential of the two button-type half-cells; and evaluating the crosstalk degree of the lithium battery based on the test data of the full battery and the two button-type half-cells.

[0009] Furthermore, the button-type half-cells all use the positive electrode of the button cell shell as the substrate of the metal lithium sheet counter electrode.

[0010] Furthermore, the positive electrode shells of the two button-type half-cells are electrically connected.

[0011] Furthermore, eliminating the overpotential of the two button-type half-cells includes: performing an initial charge and discharge test on the two button-type half-cells to obtain a first specific capacity-voltage curve; performing an initial charge and discharge test on the full cell to obtain a second specific capacity-voltage curve; and obtaining the overpotential by subtracting the first specific capacity-voltage curve from the second specific capacity-voltage curve.

[0012] Furthermore, before conducting the first charge and discharge test, the full battery and the two button-type half-batteries are left alone for at least 8 hours.

[0013] Furthermore, the charge and discharge test is: charging with constant current to a preset voltage, followed by constant voltage charging, with a cutoff ratio of half the constant current value, standing for 2-30 minutes, discharging with a preset voltage and constant current, and collecting the specific capacity-voltage curve during the first charge and discharge.

[0014] Furthermore, the coulombic efficiency of the two button-type half-cells and the full battery is calculated through the specific capacity-voltage curve of the first charge and discharge; and the crosstalk degree of the lithium battery is evaluated based on the difference or ratio of the coulombic efficiency of the two button-type half-cells and the full battery.

[0015] Furthermore, when the difference between the coulombic efficiency of the two button-type half-cells and the full cell is less than 1% of the coulombic efficiency of the two button-type half-cells, it is determined that no crosstalk occurs; or, when the ratio of the coulombic efficiency of the two button-type half-cells and the full cell is less than 1.01, it is determined that no crosstalk occurs.

[0016] On the other hand, the present invention provides a detection device for testing the crosstalk characteristics of a lithium battery, comprising: a charge and discharge test device, the charge and discharge test device is used to perform an initial charge and discharge test on two button-type half-cells and a full battery to obtain a specific capacity-voltage curve of the initial charge and discharge; the metal lithium sheets of the two button-type half-cells are electrically connected to the electrode shells of the electrodes, and the two button-type half-cells are respectively assembled using positive and negative electrode materials; the full battery is assembled using the positive and negative electrode materials; a data processing module, the data processing module calculates an overpotential based on the specific capacity-voltage curves of the two button-type half-cells and the full battery, corrects the specific capacity-voltage curves of the two button-type half-cells based on the overpotential, and calculates the coulomb efficiency through the corrected specific capacity-voltage curves of the two button-type half-cells and the specific capacity-voltage curve of the full battery; a crosstalk discrimination module, the crosstalk discrimination module evaluates the crosstalk degree of the lithium battery based on the difference or ratio between the coulomb efficiencies of the two button-type half-cells and the full battery.

[0017] Furthermore, when the difference between the coulombic efficiency of the two button-type half-cells and the full cell is less than 1% of the coulombic efficiency of the two button-type half-cells, it is determined that no crosstalk occurs; or, when the ratio of the coulombic efficiency of the two button-type half-cells and the full cell is less than 1.01, it is determined that no crosstalk occurs.

[0018] The beneficial effects brought by the technical solution provided by the embodiment of the present invention include:

[0019] The technical solution proposed in the present invention cleverly isolates the crosstalk between the pole pieces through reverse series operation, greatly simplifying the detection process. This method not only improves the detection efficiency and shortens the experimental time, but also makes the detection results more accurate by eliminating the influence of overpotential. The core is to use the reverse series connection of button-type half-cells to clearly evaluate the crosstalk characteristics of lithium batteries through charge and discharge tests. This innovative method not only deepens the understanding of the crosstalk phenomenon of lithium batteries, but also provides a more scientific basis for quality control in battery production, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A schematic diagram of a full battery and two button-type half-batteries in series provided in an embodiment of the present invention;

[0022] Figure 2The first cycle specific capacity-voltage curve and the corresponding first coulombic efficiency obtained by charge and discharge detection in Example 1 of the present invention;

[0023] Figure 3 The first cycle specific capacity-voltage curve and the corresponding first coulombic efficiency obtained by charge and discharge detection in Example 2 of the present invention;

[0024] Figure 4 The first cycle specific capacity-voltage curve and the corresponding first coulombic efficiency obtained by charge and discharge detection in Example 3 of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] The embodiment of the present invention provides a detection method for testing the crosstalk characteristics of a lithium battery, comprising the following steps:

[0027] S1 uses positive and negative electrode materials to assemble two button-type half-cells, and uses the same positive and negative electrode materials to assemble a full battery;

[0028] S2. The first charge and discharge test is performed after the metal lithium sheets of the two button-type half-cells are electrically connected to the electrode housings of the electrodes;

[0029] S3 performs a charge and discharge test on the full battery using the same charge and discharge test parameters to eliminate the overpotential of the two button-type half-cells;

[0030] S4 evaluates the crosstalk level of the lithium battery based on the test data of the full battery and the two button-type half-cells.

[0031] The technical solution proposed in the present invention cleverly isolates the crosstalk between the pole pieces through reverse series operation, greatly simplifying the detection process. This method not only improves the detection efficiency and shortens the experimental time, but also makes the detection results more accurate by eliminating the influence of overpotential. The core is to use the reverse series connection of button-type half-cells to clearly evaluate the crosstalk characteristics of lithium batteries through charge and discharge tests. This innovative method not only deepens the understanding of the crosstalk phenomenon of lithium batteries, but also provides a more scientific basis for quality control in battery production, and has broad application prospects.

[0032] It should be noted that the button-type half-cell structure is a well-known structure, including a positive electrode shell, a negative electrode shell, and a metal lithium sheet counter electrode, a diaphragm, a pole piece, and an electrolyte disposed in the positive electrode shell and the negative electrode shell. The metal lithium sheet counter electrode is electrically connected to the positive electrode shell or the negative electrode shell. In the embodiment of the present invention, the positive electrode material and negative electrode material to be studied are respectively packaged with the metal lithium sheet to form a button half-cell to study the crosstalk characteristics; wherein the diaphragm, positive and negative electrodes are made of the same materials as those in actual production. In order to verify the accuracy of the technical solution proposed in this application, the diaphragm of the embodiment of the present invention adopts Celgard diaphragm, the battery shell adopts CR2025, the positive electrode material adopts lithium-rich manganese-based (LRMO) and lithium iron phosphate (LFP), and the negative electrode material adopts graphite (Graphite) and silicon dioxide (SiO). The electrode prepared by lithium iron phosphate material will not cause crosstalk, which is used as the standard; while the lithium-rich manganese-based will cause crosstalk. It should be pointed out that the positive and negative electrode materials, diaphragms and battery shells used in the present invention are all commercially available products, and battery shells of other specifications can be used. The above selection will not affect the invention points proposed in this application.

[0033] like Figure 1 As shown, a normal battery, that is, a full battery, is composed of a positive electrode, a diaphragm and a negative electrode arranged in sequence, which is formed by filling an electrolyte and coating it with a battery shell, while the reverse series isolation method of the present application, as shown in the right figure, is formed by setting two button-type half-cells, one of which is a button-type half-cell with a positive electrode material, a diaphragm, and a metal lithium sheet electrode arranged in sequence, which is formed by filling an electrolyte and coating it with a battery shell; the other button-type half-cell is a negative electrode material, a diaphragm, and a metal lithium sheet electrode arranged in sequence, which is formed by filling an electrolyte and coating it with a battery shell. It should be pointed out that the button-type battery shell includes a positive electrode shell and a negative electrode shell. The metal lithium sheet electrodes in the two button-type half-cells can be electrically connected to the positive electrode shell or the negative electrode shell. Preferably, the button-type half-cells in the present application all use the positive electrode of the button battery shell as the substrate of the metal lithium sheet electrode. The positive electrode shells of the two button-type half-cells are electrically connected. Specifically, the positive electrode shells of the two button-type half-cells can be directly abutted, which is convenient for assembly.

[0034] Eliminating the overpotential of the two button-type half-cells comprises: performing an initial charge and discharge test on the two button-type half-cells to obtain a first specific capacity-voltage curve; performing an initial charge and discharge test on the full cell to obtain a second specific capacity-voltage curve; and obtaining the overpotential by subtracting the first specific capacity-voltage curve from the second specific capacity-voltage curve.

[0035] Preferably, before conducting the first charge and discharge test, the full battery and the two button-type half-batteries are left for at least 8 hours.

[0036] The charge and discharge test is as follows: constant current charging to a preset voltage, followed by constant voltage charging, with a cutoff ratio of half the constant current value, standing for 2-30 minutes, and then discharging at a preset voltage and constant current, collecting the specific capacity-voltage curve during the first charge and discharge. The preset voltage is a voltage commonly used by lithium batteries made of different materials, such as 2.0-4.8V for lithium-rich manganese-based batteries, 2.5-4.3V or 2.5-4.5V for high-nickel ternary batteries, and 3-4.5V for lithium cobalt oxide batteries. The preset voltage is common knowledge. In the embodiment of the present invention, the constant current is preferably 0.1C-0.2C.

[0037] The coulombic efficiency of the two button-type half-cells and the full battery is calculated through the specific capacity-voltage curve of the first charge and discharge; the crosstalk degree of the lithium battery is evaluated based on the difference or ratio of the coulombic efficiency of the two button-type half-cells and the full battery. When the difference between the coulombic efficiency of the two button-type half-cells and the full battery is less than 1% of the coulombic efficiency of the two button-type half-cells, it is determined that no crosstalk occurs; or, when the ratio of the coulombic efficiency of the two button-type half-cells and the full battery is less than 1.01, it is determined that no crosstalk occurs.

[0038] The embodiment of the present invention further provides a detection device for testing crosstalk characteristics of a lithium battery, comprising:

[0039] A charge and discharge test device, the charge and discharge test device is used to perform an initial charge and discharge test on two button-type half-cells and a full battery to obtain a specific capacity-voltage curve of the initial charge and discharge; the metal lithium sheets of the two button-type half-cells are electrically connected to the electrode shells of the electrodes, and the two button-type half-cells are respectively assembled using positive and negative electrode materials; the full battery is assembled using the positive and negative electrode materials; a data processing module, the data processing module calculates an overpotential based on the specific capacity-voltage curves of the two button-type half-cells and the full battery, corrects the specific capacity-voltage curves of the two button-type half-cells based on the overpotential, and calculates the coulomb efficiency through the corrected specific capacity-voltage curves of the two button-type half-cells and the specific capacity-voltage curve of the full battery; a crosstalk discrimination module, the crosstalk discrimination module evaluates the crosstalk degree of the lithium battery based on the difference or ratio between the coulomb efficiencies of the two button-type half-cells and the full battery.

[0040] When the difference between the coulombic efficiencies of the two button-type half-cells and the full cell is less than 1% of the coulombic efficiencies of the two button-type half-cells, it is determined that no crosstalk occurs; or, when the ratio of the coulombic efficiencies of the two button-type half-cells and the full cell is less than 1.01, it is determined that no crosstalk occurs.

[0041] In order to better illustrate the embodiments of the present invention, the present invention is further described in detail below through specific examples.

[0042] Example 1

[0043] An embodiment of the present invention provides a detection method for testing crosstalk characteristics of a lithium battery, comprising:

[0044] S1 uses positive and negative electrode materials to assemble two button-type half-cells respectively, and uses the same positive and negative electrode materials to assemble a full battery.

[0045] Commercial lithium-rich manganese-based pole pieces and graphite pole pieces are cut into discs with a diameter of 12 mm and transferred to a glove box filled with argon atmosphere. Metal lithium discs with a diameter of 14 mm and corresponding CR2025 battery shells, Celgard diaphragms, and electrolytes are prepared. Two button-type half-cells are packaged in the order of positive electrode shell, metal lithium sheet, diaphragm, pole piece, and negative electrode shell. The pole pieces in the two button-type half-cells are graphite pole pieces and lithium-rich manganese-based pole pieces, respectively.

[0046] Similarly, in a glove box filled with argon atmosphere, the third button battery was packaged in the order of positive electrode shell, lithium-manganese-rich base electrode sheet, diaphragm, graphite electrode sheet, and negative electrode shell using the same materials.

[0047] S2 After the metal lithium sheets of the two button-type half-cells are electrically connected to the electrode shells, the first charge and discharge test is carried out, and the full battery is charged and discharged using the same charge and discharge test parameters to eliminate the overpotential of the two button-type half-cells.

[0048] Two button-type half-cells are connected in series in reverse order, with the positive electrode shells partially overlapping and in contact, a lithium-rich manganese base as the positive electrode and graphite as the negative electrode, and are clamped on the crocodile clamp on the Xinwei charge and discharge tester, creating a system that isolates crosstalk between electrodes; the third button-type battery also uses a lithium-rich manganese base as the positive electrode and graphite as the negative electrode, and is clamped on the crocodile clamp on the Xinwei charge and discharge tester, creating a system that has crosstalk between electrodes.

[0049] After standing for 8 hours until the voltage stabilized, both systems were charged to 4.8V using a 0.1C constant current, then charged at a constant voltage with a cutoff ratio of 0.05C, and stood for 2 minutes, followed by a 0.1C constant current discharge. The specific capacity-voltage curves of the two systems were subtracted by software to obtain the specific value of the overpotential, and the cutoff voltage was adjusted according to the value to make the voltage window after subtracting or adding the overpotential consistent. The first cycle specific capacity-voltage curve is shown in Figure 2 shown.

[0050] S3 evaluates the crosstalk level of the lithium battery based on the test data of the full battery and the two button-type half-cells.

[0051] The coulombic efficiency of the two button-type half-cells is 75.8%, and the coulombic efficiency of the full cell is 66.3%. The difference between the two is 9.5%, 9.5% / 75.8%=12.5%, and crosstalk occurs.

[0052] Or, 75.8% / 66.3%=1.14, and crosstalk occurs.

[0053] Example 2

[0054] The embodiment of the present invention provides a detection method for testing the crosstalk characteristics of a lithium battery. The difference from Embodiment 1 is that the positive electrode in this embodiment adopts a commercial lithium iron phosphate electrode, and the negative electrode adopts the same graphite electrode as that in Embodiment 1.

[0055] After eliminating the overpotential, the first cycle specific capacity-voltage curve is as follows: Figure 3 shown.

[0056] The crosstalk level of the lithium battery is evaluated based on the test data of the full battery and the two button-type half-cells.

[0057] The coulombic efficiency of the two button-type half-cells is 80.5%, and the coulombic efficiency of the full cell is 80.2%. The difference between the two is 0.3%, 0.3% / 80.5%=0.3%, and no crosstalk occurs.

[0058] Or, 80.5% / 80.2%=1.004, no crosstalk occurs.

[0059] Example 3

[0060] The embodiment of the present invention provides a detection method for testing the crosstalk characteristics of a lithium battery. The difference from Example 1 is that the positive electrode in this embodiment adopts the same lithium-rich manganese-based electrode plate as in Example 1, and the negative electrode adopts a silicon oxide electrode plate.

[0061] After eliminating the overpotential, the first cycle specific capacity-voltage curve is as follows: Figure 4 shown.

[0062] The crosstalk level of the lithium battery is evaluated based on the test data of the full battery and the two button-type half-cells.

[0063] The coulombic efficiency of the two button-type half-cells is 70.2%, and the coulombic efficiency of the full cell is 56.3%. The difference between the two is 13.9%, 13.9% / 70.2%=19.8%, and crosstalk occurs.

[0064] Or, 70.2% / 56.3%=1.247, crosstalk occurs.

[0065] It can be seen from Examples 1-3 that the detection method proposed in the embodiments of the present invention can accurately detect the crosstalk conditions and degree of crosstalk of different battery pole pieces, and quantify the crosstalk to guide the research and development process; and the detection method of the present application is fast and effective, which can improve research and development efficiency.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A detection method for testing crosstalk characteristics of lithium batteries, characterized in that: The steps include: Assembling two button-type half-cells using positive and negative electrode materials respectively, and assembling a full cell using the same positive and negative electrode materials; The first charge and discharge test is performed after the metal lithium sheets of the two button-type half-cells and the electrode housings are electrically connected; Performing a charge and discharge test on the full battery using the same charge and discharge test parameters to eliminate the overpotential of the two button-type half-cells; The crosstalk level of the lithium battery is evaluated based on the test data of the full battery and the two button-type half-cells.

2. The detection method according to claim 1, characterized in that: The button-type half-cells all use the positive electrode of the button cell shell as the substrate of the metal lithium sheet counter electrode.

3. The detection method according to claim 2, characterized in that: The positive electrode shells of the two button-type half-cells are electrically connected.

4. The detection method according to claim 1, characterized in that: Eliminating the overpotential of the two button-type half-cells includes: Performing an initial charge-discharge test on the two button-type half-cells to obtain a first specific capacity-voltage curve; Performing a first charge-discharge test on the full battery to obtain a second specific capacity-voltage curve; The overpotential is obtained by subtracting the first specific capacity-voltage curve from the second specific capacity-voltage curve.

5. The detection method according to claim 1, characterized in that: Before performing the first charge and discharge test, the full battery and the two button-type half-batteries are left for at least 8 hours.

6. The detection method according to claim 5, characterized in that: The charge and discharge test is as follows: constant current charging to a preset voltage, followed by constant voltage charging, with a cutoff ratio of half the constant current value, standing for 2-30 minutes, and then discharging at a preset voltage and constant current to collect the specific capacity-voltage curve during the first charge and discharge.

7. The detection method according to claim 6, characterized in that: Calculate the coulombic efficiency of the two button-type half-cells and the full cell through the specific capacity-voltage curve of the first charge and discharge; The crosstalk degree of the lithium battery is evaluated based on the difference or ratio between the coulombic efficiencies of the two button-type half-cells and the full battery.

8. The detection method according to claim 7, characterized in that: When the difference between the coulombic efficiency of the two button-type half-cells and the full cell is less than 1% of the coulombic efficiency of the two button-type half-cells, it is determined that no crosstalk occurs; Alternatively, when the ratio of the coulombic efficiency of the two button-type half-cells and the full cell is less than 1.01, it is determined that no crosstalk occurs.

9. A detection device for testing crosstalk characteristics of lithium batteries, characterized in that: include: A charge and discharge test device, the charge and discharge test device is used to perform an initial charge and discharge test on two button-type half-cells and a full battery to obtain a specific capacity-voltage curve of the initial charge and discharge; the metal lithium sheets of the two button-type half-cells are electrically connected to the electrode housing of the electrode, and the two button-type half-cells are respectively assembled using positive and negative electrode materials; the full battery is assembled using the positive and negative electrode materials; A data processing module, wherein the data processing module calculates an overpotential based on the specific capacity-voltage curves of the two button-type half-cells and the full cell, corrects the specific capacity-voltage curves of the two button-type half-cells based on the overpotential, and calculates the coulombic efficiency through the corrected specific capacity-voltage curves of the two button-type half-cells and the specific capacity-voltage curve of the full cell; A crosstalk determination module is provided, wherein the crosstalk determination module evaluates the crosstalk degree of the lithium battery based on the difference or ratio between the coulombic efficiencies of the two button-type half-cells and the full cell.

10. The detection device according to claim 9, characterized in that: When the difference between the coulombic efficiency of the two button-type half-cells and the full cell is less than 1% of the coulombic efficiency of the two button-type half-cells, it is determined that no crosstalk occurs; Alternatively, when the ratio of the coulombic efficiency of the two button-type half-cells and the full cell is less than 1.01, it is determined that no crosstalk occurs.

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