In-situ detection system and test method for transition metal dissolution and release of positive electrode material
By incorporating an organic sensing layer into the battery, a four-electrode battery system has been developed, which solves the problem of difficult monitoring of transition metal dissolution during electrochemical cycling. This system enables low-cost, rapid, and accurate qualitative assessment, making it suitable for large-scale testing of battery products.
Patent Information
- Application Number
- CN202410474939.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-19
- Publication Date
- 2025-10-24
AI Technical Summary
The lack of low-cost, universal, non-destructive in-situ detection methods in the current technology to monitor the dissolution of transition metals in cathode materials during electrochemical cycling makes it difficult to assess battery performance degradation and safety hazards.
A four-electrode battery system with a transition metal ion coupling layer is adopted. By setting an organic layer that strongly chelates transition metal ions between the positive and negative electrode membranes, in-situ detection of transition metal dissolution is achieved using electrochemical impedance spectroscopy. Combined with the chelating characteristics of organic compounds with specific C=O and CN bonds, rapid and accurate qualitative evaluation is achieved.
It enables non-destructive, rapid, and accurate qualitative analysis of transition metal dissolution during battery cycling, making it suitable for large-scale testing of battery products, reducing testing costs and improving the universality of testing.
Smart Images
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Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the field of ion batteries, in particular to a positive electrode material transition metal dissolution in-situ detection system and a test method. BACKGROUND
[0002] As a key component of a secondary battery system, the structure and electrochemical performance of a positive electrode material have always been a focus of attention and research in the industry. However, in the process of electrochemical reaction, the crystal structure change of the positive electrode material in the cycle process, the distortion of the coordination environment of the transition metal atoms with the Jahn-Teller effect and the attack of the electrolyte on the metal-oxygen bond of the positive electrode material will all cause the dissolution of the transition metal atoms in the positive electrode material. For example, the dissolution of Ni and Mn elements in the ternary positive electrode material of a lithium ion battery; the dissolution of V and Mn elements in the layered positive electrode material of a zinc ion battery.
[0003] The dissolution of transition metal atoms triggers a series of battery performance degradation effects: (1) the loss of transition metal atoms in the active material will cause the destruction of the electrode structure; (2) most transition metal ions migrate under the action of an electric field and undergo a disproportionation reaction with the negative electrode-electrolyte interface film (SEI), causing a significant increase in the interface resistance, catalyzing the decomposition of organic components to produce gas in the organic system, causing performance degradation and safety hazards; (3) the residual transition metal ions in the electrolyte continuously catalyze the decomposition of the electrolyte, causing a vicious cycle. Therefore, the dissolution of transition metal ions and the series of problems derived therefrom have become one of the key factors affecting the performance of the battery.
[0004] At present, there have been many studies on the structure design and modification of electrode materials for the dissolution of transition metal ions, such as high-entropy metal atom doping, gradient structure, and coating structure design. In addition, various test methods can be used to detect the dissolution of transition metal elements, such as X-ray fluorescence spectroscopy, inductively coupled plasma, etc., to infer the mechanism of transition metal dissolution and its influence on the degradation mechanism of battery performance.
[0005] However, for a long time, there have been few studies on non-destructive in-situ detection technology for the dissolution of transition metal ions in the process of electrochemical cycling. A few in-situ detection technologies, such as in-situ X-ray fluorescence spectroscopy, require specific molds and specific instruments to achieve, and the instrument and testing cost is high, the detection method cannot be popularized, and it is not suitable for large-scale detection and analysis of battery products. Therefore, it is of great significance to develop a low-cost, universal non-destructive detection method for the dissolution of transition metal ions in the service process of the positive electrode material and the qualitative analysis of the structure degradation of the positive electrode material. SUMMARY
[0006] Based on this, the application provides a four-electrode battery system with a transition metal ion coupling layer for in-situ detection of transition metal dissolution of a positive electrode material, and a test method for the system.
[0007] To achieve the above object, the application adopts the following technical solutions.
[0008] The application provides a positive electrode material transition metal dissolution in-situ detection system and a test method, which comprises the following steps:
[0009] (1) The detection system comprises a battery core and a battery shell. The battery core comprises a positive electrode sheet, a positive electrode separator, a sensing layer, a negative electrode separator, and a negative electrode sheet. The key components of the battery core are stacked in the above order, and the battery shell is arranged outside the positive electrode sheet and the negative electrode sheet. The positive electrode sheet tab, the sensing layer tab, and the negative electrode sheet tab are exposed.
[0010] (2) The battery detection system is subjected to tab welding, top sealing, and side sealing processes.
[0011] (3) Electrolyte is injected into the battery detection system, and a final sealing process is performed.
[0012] (4) The battery detection system is left to form a battery, and battery electrochemical cycle aging test and transition metal dissolution in-situ detection test are performed.
[0013] The detection system is assembled in a drying room or a glove box.
[0014] The sensing layer is an organic material that can strongly chelate transition metal ions. Preferably, an organic material with C=N, C-N, C=O, and S=O chemical bonds can be selected.
[0015] The sensing layer preparation step is: the organic material, the conductive agent, and the binder are printed on the negative electrode separator by 3D printing / silk screen printing in advance; or the organic material is combined with a carbon nanotube, graphene, or other substrate to form a self-supporting membrane by suction filtration. Preferably, the binder can be polyvinylidene fluoride, sodium carboxymethyl cellulose, etc.; the conductive agent can be carbon nanotubes, graphene, etc., and the selected solvent can be water, N-methyl pyrrolidone, N,N-dimethylformamide, etc. More preferably, a flexible self-supporting transition metal chelating layer can be formed by directly suction filtering a conductive polymer.
[0016] The area of the sensing layer is much smaller than that of the positive and negative electrodes. Preferably, the area of the chelating layer is 1 / 5-1 / 10 of the area of the positive and negative electrodes, and the shape can be a narrow rectangle, a circle, an annular ring, etc.
[0017] A positive electrode tab is provided on the top of the positive electrode sheet, a negative electrode tab is provided on the top of the negative electrode sheet, and a sensing layer tab is provided on the side of the sensing layer. The positive electrode tab is parallel to the negative electrode tab, and two tabs are provided at both ends of one side of the sensing layer, perpendicular to the positive and negative electrode tabs.
[0018] Furthermore, a battery electrochemical cycling aging test and in-situ detection of transition metal dissolution are performed. Preferably, the battery cycling test equipment can be a battery testing system or an electrochemical workstation, with the positive and negative terminals of the testing system connected to the positive and negative tabs of the battery, respectively. The in-situ detection equipment for transition metal dissolution can be an electrochemical workstation, with the positive and negative terminals connected to the tabs of the sensor layer, respectively. The electrochemical cycling aging test step is a constant current charge and discharge test of the battery; the in-situ detection test for transition metal dissolution is an electrochemical impedance spectroscopy test of the sensor layer.
[0019] In the above solution, the testing method is applicable to secondary ion battery systems, preferably lithium ion battery systems, sodium ion battery systems, zinc ion battery systems, etc.
[0020] In the above scheme, the specific mechanism of the in-situ detection system and testing method for transition metal dissolution of cathode materials is as follows:
[0021] Electrochemical cycle tests are performed on the positive and negative electrodes under certain conditions. During the repeated charge and discharge process, due to the Jahn-Taylor effect, electrolyte attack and other reasons, the transition metal ions in the positive electrode material are dissolved, migrate to the sensing layer under the action of voltage and are firmly adsorbed, causing the impedance of the sensing layer to change accordingly.
[0022] The present invention provides the following beneficial effects:
[0023] (1) The present invention is a non-destructive detection technology for transition metal dissolution. It can perform a qualitative analysis of the dissolution of transition metals inside the electrode material without destroying the battery structure, and can serve as one of the bases for evaluating the structural degradation of the positive electrode material.
[0024] (2) The present invention is an in-situ detection technology for transition metal dissolution, which can timely perform qualitative analysis of the dissolution of transition metals inside electrode materials, and has high time resolution and high accuracy.
[0025] (3) The present invention is compatible with existing battery assembly equipment and battery testing systems and has strong feasibility. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 This is an example of a schematic diagram of the appearance of the sensing layer of the present invention;
[0027] Figure 2 is the schematic diagram of the positive electrode material transition metal dissolution in-situ detection system and the schematic diagram of the test method according to the present application;
[0028] Figure 3 is a flexible display diagram of the dopamine doped polypyrrole self-supporting transition metal chelating layer selected in the embodiment of the present application;
[0029] Figure 4 is an EDS diagram of the vanadium element distribution in the dopamine doped polypyrrole sensing layer selected in the detection system of the aqueous zinc ion battery with V2O5 as the positive electrode material in Example 1 of the present application after 200 cycles;
[0030] Figure 5 are impedance diagrams of the sensing layer in the detection system of the aqueous zinc ion battery with V2O5 as the positive electrode material in Example 1 of the present application before and after 200 cycles;
[0031] Figure 6 is an impedance diagram of the dopamine sensing layer selected in the detection system of the organic lithium ion battery with LiMn2O4 as the positive electrode material in Example 2 of the present application before and after 100 cycles;
[0032] Figure 7 is an impedance diagram of the Naifon sensing layer selected in the detection system of the organic lithium ion battery with LiMn2O4 as the positive electrode material in Example 3 of the present application before and after 50 cycles;
[0033] Figure 8 is an impedance diagram of the Naifon sensing layer selected in the detection system of the organic lithium ion battery with Ti3C2T x MXene as the negative electrode material in Comparative Example 1 of the present application before and after 50 cycles. DETAILED DESCRIPTION
[0034] The present application will be further described in detail below with specific embodiments, and the given examples are only for illustrating the present application, but not for limiting the scope of the present application.
[0035] In the following examples, the experimental methods are all conventional methods unless otherwise specified.
[0036] In the following examples, the materials, reagents, etc. can be obtained from commercial channels unless otherwise specified.
[0037] In the following examples:
[0038] Positive electrode sheet preparation method: first, the positive electrode material, polyvinylidene fluoride (PVDF) and Super P are weighed according to the mass ratio of 7:2:1, then placed in a ball mill jar, ball milling for 10 min, then add appropriate amount of N-methyl pyrrolidone (NMP) solution, continue to ball mill for 30 min, form a certain flowability of the positive electrode slurry. For water-based zinc ion battery system, the prepared slurry is uniformly coated on a stainless steel foil; for organic lithium ion battery system, the prepared slurry is uniformly coated on an aluminum foil. After preliminary drying, the coated electrode is placed in a 80℃ vacuum drying oven for 24h, and then cut according to a certain size after drying.
[0039] Battery system assembly method: stack the cut electrode core components and battery shell according to the stacking order of step (1) and package. The position of the tab is shown in Figure 2 . For zinc ion battery, directly assemble in normal atmospheric environment; for lithium ion battery, assemble in an argon atmosphere glove box with water and oxygen content <0.01ppm.
[0040] Battery detection system test method: connect the assembled detection system according to the Figure 2 schematic diagram for wiring test. The positive and negative electrode charge and discharge cycle test is completed by a certain number of constant current charge and discharge in a new Wei battery test system; the transition metal dissolution release in situ detection is completed by impedance test on Ivium electrochemical workstation.
[0041] Example 1
[0042] The test system is selected as a water-based zinc ion battery, the positive electrode material is V2O5 positive electrode material, the negative electrode is metal zinc, the separator is selected as a glass fiber separator, the electrolyte is selected as 2M ZnSO4 aqueous solution, and the sensing layer is selected as a self-supporting film of dopamine doped polypyrrole rich in C=O bond and having conductivity. The self-supporting film is cut into a long rectangle with a volume of 1 / 5 of the volume of the positive electrode sheet. Assembled into a four-electrode detection system according to the foregoing method. The electrochemical cycle aging test is completed in a new Wei battery test system, and the test current density is 0.5Ag -1 . The transition metal in situ monitoring is completed on Ivium electrochemical workstation in the Netherlands, and the test frequency range is 0.1Hz-100000Hz.
[0043] Figure 3 The self-supporting layer is flexible. After the battery is disassembled, the sensing layer is tested and analyzed by energy dispersive X-ray spectroscopy (EDS) Figure 4 ), a large amount of vanadium elements on the sensing layer are obtained, indicating that the sensing layer chelates the dissolved vanadium ions in the positive electrode material. Figure 5To detect the electrochemical impedance spectroscopy of the test system before the cycle started and after 200 cycles, the chelation of vanadium ions affected the molecular structure of the organic matter, thereby increasing the impedance resistance value of the sensing layer.
[0044] Example 2
[0045] The test system selected was an organic lithium ion battery, the positive electrode material was LiMn2O4, the negative electrode was metal lithium, the separator selected was a polypropylene separator, the electrolyte selected was a 1M LiPF6 EC+DMC+DEC solution, and the transition metal ion chelated organic matter selected was polydopamine peroxide. The sensing layer preparation steps were: mixing polydopamine nanoparticles, carbon nanotubes, and polyvinylidene fluoride in N,N-dimethylformamide solvent, printing onto the polypropylene negative electrode separator by 3D printing, and printing the shape as an open ring. The four-electrode battery detection system was assembled according to the foregoing method. The electrochemical cycle aging test was completed in a new Wei battery test system, and the test current density was 1.0 A g -1 . The in-situ monitoring of transition metals was completed on a Dutch Ivium electrochemical workstation, and the test frequency range was 0.01 Hz-100000 Hz.
[0046] Figure 6 To test the electrochemical impedance spectroscopy of the sensing layer of the test system before and after 100 cycles.
[0047] Example 3
[0048] The test system selected was an organic lithium ion battery, the positive electrode material was LiMn2O4, the negative electrode was metal lithium, the separator selected was a polypropylene separator, the electrolyte selected was a 1M LiPF6 EC+DMC+DEC solution, and the transition metal ion chelated organic matter selected was a Naifon solution rich in S=O bonds. The sensing layer preparation steps were: mixing the Naifon solution, carbon nanotubes, and sodium carboxymethyl cellulose in deionized water, printing onto the polypropylene negative electrode separator by screen printing, and printing the shape as a 3 / 4 rectangle. The four-electrode battery detection system was assembled according to the foregoing method. The electrochemical cycle aging test was completed in a new Wei battery test system, and the test current density was 1.0 Ag -1 . The in-situ monitoring of transition metals was completed on a Dutch Ivium electrochemical workstation, and the test frequency range was 0.1 Hz-100000 Hz.
[0049] Figure 7 To test the electrochemical impedance spectroscopy of the sensing layer of the test system before and after 50 cycles.
[0050] Comparative Example 1
[0051] The test system is selected as an organic lithium ion battery, the negative electrode material is MXene nanotube, the negative electrode sheet and the positive electrode sheet are prepared by the same method, only the aluminum foil is replaced by copper foil, and the positive electrode is metal lithium. The remaining assembly, test conditions and methods are the same as those in Example 3.
[0052] Figure 8 In order to test the impedance spectrogram of the sensing layer of the system before and after 50 cycles, since there is no transition metal ion release in the whole system, the impedance value of the sensing layer has no obvious change.
[0053] The applicant declares that the detailed method of the present application is illustrated by the above examples, but the present application is not limited to the above detailed method, that is, it does not mean that the present application must rely on the above detailed method to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the raw materials used in the present application, addition of auxiliary materials, selection of specific methods, etc. fall within the protection scope and disclosure scope of the present application.
Claims
1. A positive electrode material transition metal dissolution in-situ detection system and test method, characterized in that, The method comprises the following steps: stacking the positive electrode sheet, the positive electrode separator, the sensing layer, the negative electrode separator, and the negative electrode sheet in sequence; placing the battery shell outside the positive electrode sheet and the negative electrode sheet, respectively, and adjusting the exposed positive electrode tab, the sensing layer tab, and the negative electrode tab; welding the tabs, top sealing, and side sealing of the battery detection system; injecting electrolyte into the battery detection system and completely sealing the detection system; performing battery electrochemical cycle aging test and transition metal dissolution in-situ detection test on the final battery detection system.
2. The positive electrode material transition metal dissolution in-situ detection system and test method according to claim 1, characterized in that, The sensing layer is a flexible film obtained by printing transition metal chelates, conductive agents, and binders on the negative electrode separator by screen printing / 3D printing technology or directly by suction filtration; the area of the sensing layer is much smaller than that of the positive and negative electrodes; preferably, the area of the sensing layer accounts for 1 / 5-1 / 10 of the area of the positive and negative electrodes, and the shape can be narrow rectangle, circle, or circular ring.
3. The transition metal chelate in claim 2 is an organic compound having strong chelation with transition metal ions; preferably, it is an organic compound rich in C=O, C=N, C-N, and S=O chemical bonds.
4. The in-situ detection system and test method for transition metal dissolution of cathode materials according to claim 1, characterized in that The top end of the positive electrode sheet is provided with a positive electrode tab, the top end of the negative electrode sheet is provided with a negative electrode tab, and the side end of the sensing layer is provided with a sensing layer tab; preferably, the positive electrode tab and the negative electrode tab are parallel, two tabs are arranged at the two ends of the sensing layer and placed on one side, and are perpendicular to the positive and negative electrode tabs, forming a four-electrode test system.
5. The positive electrode material transition metal dissolution in-situ detection system and test method of claim 1, wherein, The battery electrochemical cycle aging test is a constant current charge and discharge test through the positive and negative electrode tabs; and the transition metal dissolution in-situ detection test is an electrochemical impedance test through the two electrode tabs of the sensing layer.
6. The positive electrode material transition metal dissolution in-situ detection system and test method according to claims 1-5, characterized in that, The detection system and test method are used for positive electrode materials with easily dissolved transition metal ions, and the battery system can be organic and aqueous batteries.
7. The use of the positive electrode material transition metal dissolution in-situ detection system and test method according to claims 1-5, characterized in that, The detection system can be used for non-destructive, in-situ, and qualitative monitoring of the transition metal dissolution of the positive electrode material during service and the structural degradation of the positive electrode material.