New energy cell core feature identification method based on coating technology and application

Abstract

The application provides a new energy cell core characteristic identification method based on a coating technology and application, wherein the identification method comprises the following steps: selecting a part of samples in a to-be-tested pole piece for micro-layer peeling treatment to obtain electrode material powder; performing distillation reflux treatment on the electrode material powder to remove a dispersant and / or a binder to obtain an electrode active material; testing the electrode active material to obtain a test result; the test comprises a first test or comprises a first test and a second test, the first test comprises a Raman spectrum test and / or an X-ray diffraction test, and the second test comprises a transmission electron microscope test; and the type of the electrode active material is determined according to the test result. The new energy cell core characteristic identification method based on the coating technology can exclude the interference of the binder and the dispersant in the negative electrode material and determine the type of the electrode active material in the coated pole piece material by combining micro-layer peeling, distillation reflux and Raman spectrum test.

Description

Technical Field

[0001] This application relates to the field of secondary batteries and their testing technology, and in particular to a method and application for identifying the core characteristics of new energy battery cell electrodes based on coating technology. Background Technology

[0002] With the continuous development of lithium-ion battery technology, people's requirements for its energy density and cycle life are constantly increasing, and battery costs also need to be reduced. The composition of the positive and negative electrode sheets, especially the composition of the negative electrode sheet, is closely related to achieving the above objectives.

[0003] Taking the composition of the negative electrode sheet as an example, it involves the material composition of the negative electrode material layer, the number of coating layers, and the composition of each coating layer. The number of coating layers is divided into single-layer coating and multi-layer coating, with double-layer coating being more widely used. Double-layer coating technology, by coating the current collector with different compositions, can effectively adjust the performance of the negative electrode. It is mainly used in the preparation of silicon-based / graphite negative electrodes to alleviate at least the following problems: 1. Process time reduced by 50%, achieving "high adhesion of the bottom layer + high activity of the top layer" in a single coating, eliminating the need for secondary unwinding / drying / rewinding; 2. Improved cycle life, with binder layering inhibiting migration, reducing interfacial stress, and decreasing the electrode foil detachment rate by 80%; 3. Reduced cost, using different types of graphite in the upper and lower layers significantly reducing raw material costs. It comprehensively outperforms traditional single-layer solutions in terms of efficiency, performance, and cost, and has become the preferred process for leading battery manufacturers to expand their production lines by 2025.

[0004] To further improve battery performance, it is necessary to study the composition of at least some of the positive and negative electrode sheets, especially the negative electrode sheet, to understand their electrode material composition, coating layer settings, and especially the material composition of each layer when there are two or more coating layers, so as to implement improvements.

[0005] However, the inventors discovered that the related technology has at least the following drawbacks:

[0006] (1) It can only detect single-layer materials, and the detection accuracy needs to be improved;

[0007] (2) It is difficult to distinguish the types, composition and structural design of coating materials with two or more layers, which makes it difficult to accurately control the key parameters of the negative electrode sheet. This cannot meet the needs of R&D personnel to fully understand the negative electrode preparation process, and affects the further improvement of battery energy density and cycle life.

[0008] Therefore, there is an urgent need to develop a method for identifying the core characteristics of electrode sheets in new energy battery cells based on coating technology, so as to accurately analyze and identify coated electrode materials, thereby optimizing the preparation process of negative electrodes and other electrodes and improving battery performance. Summary of the Invention

[0009] In view of this, one objective of this application is to provide a method for identifying the core characteristics of new energy battery cell electrodes based on coating technology. By combining micro-layer peeling, distillation reflux and Raman spectroscopy / XRD testing, the interference of binders and dispersants in the negative electrode material can be eliminated, and the type of electrode active material in the coated electrode material can be determined.

[0010] Another objective of this application relates to the application of a method for identifying the core characteristics of electrode sheets in new energy battery cells based on coating technology.

[0011] To achieve the above objectives, a first aspect of this application proposes a method for identifying the core characteristics of electrode sheets in new energy battery cells based on coating technology, comprising the following steps:

[0012] S101. Select a portion of the sample from the electrode to be tested and perform micro-layer peeling to obtain electrode material powder;

[0013] S102. The electrode material powder is subjected to distillation and reflux treatment to remove the dispersant and / or binder, thereby obtaining the electrode active material;

[0014] S103. Test the electrode active material to obtain test results; the test includes a first test or a first test and a second test, the first test includes Raman spectroscopy and / or X-ray diffraction, and the second test includes transmission electron microscopy.

[0015] S104. Determine the type of the electrode active material based on the test results.

[0016] In some embodiments, determining the type of the electrode active material based on the test results includes:

[0017] Based on the results of the first test, determine the substance type or class of the electrode active material; and / or,

[0018] The coating characteristics of the electrode active material are determined based on the results of the second test.

[0019] In some embodiments, the micro-layer peeling process is performed multiple times, and steps S102 to S104 are repeated after each micro-layer peeling process.

[0020] Based on the type of electrode active material determined in step S104 after multiple micro-layer peeling processes, the number of electrode material coating layers in the electrode sheet and / or the thickness of each electrode material coating layer are obtained.

[0021] In some embodiments, obtaining the number of electrode material coating layers and / or the thickness of each electrode material coating layer in the electrode sheet includes:

[0022] If the type of electrode active material obtained in step S104 is consistent after two consecutive micro-layer peeling processes, then they are determined to belong to the same electrode material coating layer.

[0023] If the types of electrode active materials obtained in step S104 after two adjacent micro-layer peeling processes are inconsistent, it is determined that they are not the same electrode material coating layer.

[0024] The number of times the type of the electrode active material determined in step S104 after two adjacent microlayer peeling processes is inconsistent is taken as the number of electrode material coating layers; and / or,

[0025] The thickness of the electrode material coating layer is the sum of the thicknesses of all micro-layer peeling processes that are determined to belong to the same electrode material coating layer after all consecutive micro-layer peeling processes in step S104.

[0026] In some embodiments, the thickness of each microlayer peeling process is 1 to 40 μm.

[0027] In some embodiments, the electrode to be tested includes one of a fresh positive electrode, a fresh negative electrode, a positive electrode after battery cycling, and a negative electrode after battery cycling.

[0028] In some embodiments, the electrode under test has at least one electrode material coating layer.

[0029] Optionally, the electrode to be tested has two or more electrode material coating layers.

[0030] In some embodiments, the electrode to be tested is a fresh negative electrode or a negative electrode after battery cycling, having at least two layers of electrode material coating with different graphite types in each layer.

[0031] In some embodiments, the dispersant includes an aqueous dispersant.

[0032] In some embodiments, the aqueous dispersant includes at least one of carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, sodium carboxyethyl cellulose, and lithium carboxyethyl cellulose, with carboxymethyl cellulose being the preferred choice.

[0033] In some embodiments, the adhesive includes a water-based adhesive.

[0034] In some embodiments, the aqueous adhesive includes at least one of styrene-butadiene and its modified organic emulsion, styrene acrylate and its modified organic emulsion, polyethylene emulsion, and polyacrylic adhesive, and may be selected as styrene-butadiene and its modified organic emulsion.

[0035] In some embodiments, the electrode active material includes one of graphite, silicon oxide, lithium cobalt oxide, lithium nickel oxide, lithium copper oxide, lithium titanate, ternary cathode material, LiMn2O4, and LiFePO4, and may be selected as graphite.

[0036] In some embodiments, the temperature of the distillation process is 200–300°C, and the vacuum degree of the distillation reflux process is 0.1–0.5 Pa.

[0037] In some embodiments, the Raman spectroscopy test conditions are: a scanning range of 100–3200 cm⁻¹. -1 The laser power is 50-200mW.

[0038] In some embodiments, the X-ray diffraction test is performed under the following conditions: the scanning angle range is 10 to 80°.

[0039] In some embodiments, the method for identifying the core characteristics of new energy cell electrode sheets based on coating technology further includes a step of cleaning and drying the electrode surface before the micro-layer peeling process.

[0040] In some embodiments, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes a step of collecting and sieving the electrode material powder before the distillation reflux treatment; the average particle size of the sieved electrode material powder is 5 to 15 μm.

[0041] In some embodiments, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes a step of drying the electrode material powder before the distillation reflux treatment.

[0042] In some embodiments, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes a step of collecting the volatile organic compounds discharged from the distillation reflux treatment after the distillation reflux treatment.

[0043] In some embodiments, the electrode to be tested includes a positive electrode after battery cycling or a negative electrode after battery cycling. The method for identifying the core characteristics of the electrode of a new energy cell based on coating technology further includes: if the test results cannot be used to determine the type of the electrode active material, then another part of the sample of the electrode to be tested is selected and steps S101 to S104 are repeated until step S104 can determine the type of the electrode active material based on the test results, at which point the replacement of samples from different parts of the electrode to be tested is stopped.

[0044] In some embodiments, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes the step of analyzing and detecting the content of each component in the electrode to be tested.

[0045] The second aspect of this application relates to the application of the method for identifying the core characteristics of new energy cell electrode sheets based on coating technology described in this application in the production of secondary batteries.

[0046] In some embodiments, when the electrode is a negative electrode having two layers of electrode material coating with different graphite types in each layer, the electrode must satisfy at least one of the following characteristics:

[0047] (1) The compaction density of the electrode material coating layer on the side away from the current collector is 1.5–1.8 g / cm³. 3 ;

[0048] (2) The areal density of the electrode material coating layer on the side away from the current collector is 2-3 mg / cm³. 2 ;

[0049] (3) The compaction density of the electrode material coating layer near the current collector is 1.2–1.5 g / cm³. 3 ;

[0050] (4) The areal density of the electrode material coating layer near the current collector is 4–6 mg / cm³. 2 ;

[0051] (5) The thickness ratio of the electrode material coating layer on the side away from the current collector to the electrode material coating layer on the side closer to the current collector is 1:(3-6).

[0052] The method for identifying the core characteristics of new energy battery cell electrodes based on coating technology described in this application can bring at least the following beneficial effects:

[0053] 1. By combining microlayer exfoliation, distillation reflux, and Raman spectroscopy / XRD tests, the interference of binders and dispersants in the negative electrode material can be eliminated, and the type of electrode active material in the coated electrode material can be determined.

[0054] 2. By performing transmission electron microscopy on the electrode active material obtained after microlayer peeling and distillation reflux, the coating characteristics of the electrode active material can be analyzed, and it can be determined whether the electrode active material is a coated electrode active material, thus achieving comprehensive detection of the coated electrode structure.

[0055] 3. When performing multiple micro-layer peeling processes, the number of coating layers, the thickness of each coating layer, and the type of active material of the electrode can be obtained by combining multiple micro-layer peeling with distillation reflux, Raman spectroscopy / XRD testing, etc. This enables effective decomposition of unknown electrodes, solves the problem of accurately distinguishing coating material types in existing technologies, and overcomes the limitation of related technologies that can only detect single-layer materials. It provides important reference data for the research and development of coating electrodes with single or multiple layers, and helps researchers better understand the actual effects of coating technology, especially double-layer coating technology.

[0056] 4. The micro-layer peeling technology and distillation reflux method adopted are simple and feasible to operate, easy to industrialize, and have good practical value and prospects for promotion and application.

[0057] 5. This method for identifying the core characteristics of new energy battery cell electrodes based on coating technology can serve as an effective means of investigating infringement risks. By analyzing the materials and other aspects of competitors' double-layer coating technology, it can assess their technical characteristics and provide important references for enterprises' R&D and strategic decision-making.

[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] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings.

[0060] in:

[0061] Figure 1 This is a flowchart illustrating an exemplary embodiment of the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology.

[0062] Figure 2 This is a schematic diagram of the structure of a coated electrode sheet as shown in an exemplary embodiment of this application.

[0063] Figure 3 The image shows a cross-sectional view of a scanning electron microscope (SEM) of the core characteristic identification method of the electrode sheet of a new energy battery cell based on coating technology, as shown in Comparative Example 1.

[0064] Figure label:

[0065] 1-Current collector; 2-First electrode material coating layer; 3-Second electrode material coating layer. Detailed Implementation

[0066] 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.

[0067] In this application, the disclosure of numerical ranges includes all values ​​throughout the range and the disclosure of further subdivisions of the range, including the endpoints and subranges given for these ranges.

[0068] Unless otherwise specified, all raw materials and equipment involved in this application are self-made through commercial means or known methods; and all methods involved are conventional methods unless otherwise specified.

[0069] When the term “and / or” is used in a list containing two or more items, it means that any of the listed items can be used alone or in combination with any one or more of the listed items. For example, the expression “A and / or B” is intended to mean A or B or A and B, that is, A only, B only, or a combination of A and B.

[0070] This application describes a method for identifying the core characteristics of new energy battery cell electrodes based on coating technology. It is applicable to electrodes formed by coating, where the electrode material layer includes an electrode active material and a binder, or includes an electrode active material, a dispersant, and a binder. The electrode active material can be identified by Raman spectroscopy or X-ray diffraction (XRD).

[0071] The core characteristic identification method for new energy battery cell electrodes based on coating technology in this application is applicable to electrodes with a single layer of electrode material coated on the current collector, as well as electrodes with multiple layers (two or more) of electrode material coated on the current collector; it is applicable to both fresh electrodes and recycled electrodes. However, because the composition of each part of a fresh electrode is stable, while the composition of a recycled electrode is unstable due to factors such as lithium plating, the identification methods for the two differ slightly. The electrode can be either a positive electrode or a negative electrode.

[0072] The following describes a method for identifying the core characteristics of new energy battery cell electrodes based on coating technology, according to an embodiment of this application, with reference to the accompanying drawings.

[0073] Figure 1 This is a flowchart illustrating an exemplary embodiment of a method for identifying core characteristics of new energy battery cell electrodes based on coating technology. This method is applicable to the identification of fresh coated electrode materials. Figure 1 As shown, the method includes the following steps:

[0074] S101. Select a portion of the sample from the electrode to be tested and perform micro-layer peeling to obtain electrode material powder.

[0075] In the embodiments of this application, the micro-layer peeling technology can solve the problem of difficulty in distinguishing the upper and lower layers of double coatings when the coating consists of two or more layers.

[0076] In some embodiments, the electrode to be tested includes either a fresh positive electrode or a fresh negative electrode.

[0077] In some embodiments, the electrode under test includes a current collector and an electrode material layer disposed on the current collector. Exemplary current collectors include, but are not limited to, aluminum foil, copper foil, etc.

[0078] In some embodiments, the electrode under test has at least one electrode material coating layer.

[0079] As an optional example, the electrode under test has two or more electrode material coating layers (e.g., 2 to 20 layers, including but not limited to 5, 10 or 15 layers, etc.), and may further be configured to have two electrode material coating layers.

[0080] In some embodiments, the electrode material coating layer includes an electrode active material and a binder. In this case, the electrode to be tested is generally a positive electrode.

[0081] In other embodiments, the electrode material coating layer includes an electrode active material, a dispersant (also called a thickener in some cases), and a binder. In this case, the electrode to be tested is generally a negative electrode.

[0082] For example, the electrode active material includes, but is not limited to, graphite, silicon oxides (e.g., SiO2). X (0 < x < 2), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium copper oxide (Li2CuO2), lithium titanate (Li4Ti5O2) 12 One of the following: ternary cathode material (e.g., NCM or NCA series ternary cathode material), LiMn2O4, LiFePO4, etc., with graphite as an option.

[0083] For example, the dispersant includes an aqueous dispersant. Optionally, the aqueous dispersant includes, but is not limited to, at least one of carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, sodium carboxyethyl cellulose, and lithium carboxyethyl cellulose, and is further optionally carboxymethyl cellulose (CMC).

[0084] For example, the adhesive includes an aqueous adhesive. Optionally, the aqueous adhesive includes at least one of styrene-butadiene and its modified organic emulsion (SBR), styrene acrylate and its modified organic emulsion, polyethylene emulsion, and polyacrylic acid adhesive (PAA), with styrene-butadiene and its modified organic emulsion (SBR) being the preferred choice.

[0085] It should be noted that when there are two or more electrode material coating layers, the multilayer electrode material coating layers are stacked on the current collector, and the types of electrode active materials in adjacent electrode material coating layers are different.

[0086] It should also be noted that the electrode material coating layer also includes conductive agents, such as conductive carbon black, which are used in secondary batteries, especially lithium-ion batteries. However, since the mass content of conductive agents in the electrode material coating layer is generally small (generally not exceeding 0.8 wt%), and the conductive agents have almost no impact on the identification results of the identification method of the core characteristics of new energy cell electrode sheets based on coating technology in the embodiments of this application, conductive agents can be disregarded.

[0087] As an optional example, the electrode to be tested is a fresh negative electrode or a negative electrode after battery cycling, which has at least two layers of electrode material coating with different graphite types in each layer.

[0088] In some implementations, the method for selecting a portion of the sample from the electrode to be tested for micro-layer peeling is as follows: the two ends of the sample to be tested are fixed on the fixture of the micro-layer peeling device, the single-layer peeling thickness is set (that is, the thickness of a single micro-layer peeling when the number of micro-layer peeling processes is multiple), the high-precision peeling blade performs peeling work according to the set parameters, and the powder sample is collected from the bottom after completion.

[0089] In the embodiments of this application, the micro-layer peeling process has advantages over other peeling methods, such as more flexible regional testing, higher precision, controllable peeling depth, good separation effect, and simple operation.

[0090] In some embodiments, the method for identifying the core characteristics of new energy cell electrode sheets based on coating technology further includes a step of cleaning and drying the electrode surface before the micro-layer peeling process.

[0091] For example, when the electrode is a battery-cycled electrode (positive electrode or negative electrode), the method for cleaning the electrode surface before the micro-layer peeling process is to clean the electrode surface with organic solvents such as alcohol and dimethyl carbonate (DMC) to remove the electrolyte.

[0092] For example, when the electrode is a fresh electrode (positive electrode or negative electrode), the method for cleaning the surface of the electrode before the microlayer peeling process is to clean the surface of the electrode with an ultrapure water vapor cleaner for 5-25 minutes, such as 10 minutes, 15 minutes or 20 minutes.

[0093] For example, during the drying process of the electrode surface before the microlayer peeling treatment, the drying temperature is 50-90°C, such as 60°C or 75°C, and the drying time is 4-6 hours, such as 5 hours.

[0094] S102. The electrode material powder obtained in step S101 is subjected to distillation and reflux treatment to remove the dispersant and / or binder, thereby obtaining the electrode active material.

[0095] In the embodiments of this application, dispersants and binders are removed using evaporation reflux technology, enabling formulation analysis of the electrode sheet, particularly the identification of the electrode active materials. Specifically, the purpose of removing dispersants and / or binders is to reduce interference with subsequent identification of the electrode active materials. Distillation reflux treatment is a simpler and more convenient method for removing dispersants and / or binders.

[0096] In some embodiments, the distillation process is carried out at a temperature of 200–300°C, including but not limited to 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, or 290°C.

[0097] In some embodiments, the vacuum degree of the distillation reflux treatment is 0.1 to 0.5 Pa, including but not limited to 0.15 Pa, 0.2 Pa, 0.25 Pa, 0.3 Pa, 0.35 Pa, 0.4 Pa, or 0.45 Pa.

[0098] In the embodiments of this application, the temperature and vacuum degree of the distillation process are within the above-mentioned range, which can separate dispersants and binders such as CMC, SBR, and PAA with little residue, and can perform single-component separation.

[0099] In some embodiments, the distillation reflux treatment time is 0.5 to 12 hours, including but not limited to 1 hour, 3 hours, 6 hours, 9 hours, or 12 hours.

[0100] In some embodiments, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes a step of drying the electrode material powder before the distillation reflux treatment.

[0101] For example, the method of drying the electrode material powder before the distillation reflux treatment includes, but is not limited to, vacuum drying, spray drying, etc., with vacuum drying being an option.

[0102] Optionally, the electrode material powder is dried at a temperature of 60-80°C before the distillation reflux treatment, including but not limited to 65°C, 70°C, or 75°C; the drying time is 4-8 hours, including but not limited to 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, or 7.5 hours; the drying is carried out in a vacuum drying oven.

[0103] In some embodiments, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes the steps of collecting and sieving the electrode material powder before the distillation reflux treatment.

[0104] For example, the particle size of the sieved electrode material powder is 5 to 15 μm, including but not limited to 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm or 14 μm.

[0105] As an optional example, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes the steps of sequentially collecting, sieving, and drying the electrode material powder before the distillation reflux treatment.

[0106] In some embodiments, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes a step of collecting the volatile organic compounds discharged from the distillation reflux treatment after the distillation reflux treatment.

[0107] In the embodiments of this application, the types of volatile organic compounds generally vary depending on the type of binder or the type of binder and dispersant.

[0108] For example, when the dispersant is carboxymethyl cellulose (CMC) and the binder is styrene-butadiene and its modified organic emulsion (SBR), the volatile organic compounds include, but are not limited to, PAA, polyvinylidene fluoride (PVDF), acrylic binders, polyurethane binders, etc.

[0109] S103. The electrode active material obtained in step S102 is tested to obtain test results; the test includes a first test or a first test and a second test, the first test includes Raman spectroscopy and / or X-ray diffraction (XRD test), and the second test includes transmission electron microscopy.

[0110] In the embodiments of this application, Raman spectroscopy and X-ray diffraction (XRD) are key characterization techniques for identifying active materials in battery electrodes. They can identify different types of materials and different forms of the same material. Their principles are based on molecular vibrational energy levels and crystal structure diffraction, respectively.

[0111] The material essence of Raman spectroscopy is that after a sample is irradiated by a laser, photons couple with the vibrational / rotational energy levels of molecules, resulting in energy exchange and a wavelength shift (Raman shift). Different vibrational modes of chemical bonds / functional groups correspond to specific Raman shifts (cm²). - 1) Forming the "molecular fingerprint" of materials. Taking graphite as an example, the principle of identifying different types of graphite through the structural information reflected by Raman spectroscopy is that: the larger the Average D / G (area) value, the higher the degree of defects and disorder in the carbon material, and the more ordered the sp... 2 A relatively small number of carbon atoms indicates a higher degree of graphitization and a more ordered and complete structure. Taking lithium iron phosphate as another example, observe the characteristic peaks of lithium iron phosphate in its Raman spectrum, such as those at 400-600 cm⁻¹. -1 The vibrational modes of the Fe-O group in the range of 600-800 cm⁻¹ -1 PO4 in the interval 3- Ion vibration modes. High intensity and stable positions of these characteristic peaks indicate a stable crystal structure and superior performance of lithium iron phosphate. Weakened intensity or shifted positions of the characteristic peaks may indicate defects or instability in the crystal structure, affecting the battery's cycle performance and rate performance. Furthermore, by comparing the characteristic peaks with those on a standard lithium iron phosphate card, it can be determined whether the active material used on the positive electrode side is lithium iron phosphate.

[0112] The material nature of X-ray diffraction (XRD) is X-rays. When a crystal is irradiated, coherent diffraction peaks are generated when the interplanar spacing d satisfies nλ = 2d·sinθ. The interplanar spacing (d value) can then be calculated using the diffraction angle (2θ), and the phase can be determined by comparing it with a standard card. Taking XRD testing of graphite as an example, the higher the degree of graphitization, the more complete and ordered the graphite crystal structure, the smaller and more uniform the interlayer spacing, the less resistance there is to lithium ion insertion and extraction between graphite layers, and the smoother the transport channels, which is beneficial for improving rate performance. Taking lithium iron phosphate as another example, observe the characteristic diffraction peaks of lithium iron phosphate in the XRD pattern, such as those located at angles of 31.6°, 35.2°, 42.6°, 47.6°, 53.7°, and 57.8°. Higher peak intensity and fewer impurity peaks indicate higher material purity, a more complete crystal structure, and better material performance.

[0113] For example, an example of identifying graphite by XRD and an example of mechanism analysis: When studying the characterization of graphene powder, X-ray diffraction analysis was used to find that the XRD spectrum of graphite has four strong peaks, located at 12.9° (001 plane), 26.5° (002 plane), 42.4° (100 plane) and 54.3° (004 plane), respectively. Among them, the strong peak at 26.5° is the characteristic peak of graphite, corresponding to the (002) plane, and the interlayer spacing is calculated to be 0.335 nm.

[0114] Mechanism Analysis: X-ray diffraction identifies substances based on the differences in diffraction angles and intensities of X-rays refracted by substances with different crystal structures. Graphite has a layered crystal structure, with its atoms arranged in a hexagonal planar network, and the layers interacting through van der Waals forces. When X-rays irradiate a graphite crystal, diffraction occurs at specific angles, forming characteristic diffraction peaks. For example, the characteristic peak of graphite appears at around 26.5°, due to its specific crystal structure and interatomic spacing. By comparing the XRD pattern of a sample with the diffraction peak positions and intensities of graphite in a standard card, it is possible to determine whether the substance is graphite.

[0115] Example and Mechanism Analysis of Identifying Lithium Iron Phosphate (LiFePO4) as the Positive Electrode Material using XRD: Taking a lithium-ion battery with LiFePO4 as the positive electrode and graphite as the negative electrode as an example, XRD was used to analyze the material changes during the charge-discharge process. During charge-discharge, lithium ions intercalate and deintercalate within the LiFePO4 material, causing changes in its crystal structure, which in turn alters the XRD pattern.

[0116] Mechanism Analysis: Lithium iron phosphate (LFP) possesses an olivine-type structure, and the position and intensity of its XRD characteristic peaks are closely related to factors such as atomic arrangement and interplanar spacing within the crystal structure. During charging and discharging, the lattice of LFP changes with the insertion and extraction of lithium ions; for example, the cell volume changes, and the interplanar spacing of some crystal planes also changes, leading to changes in the position and intensity of diffraction peaks in the XRD pattern. By analyzing the XRD patterns of LFP before and after charging and discharging, as well as under different charging and discharging states, we can understand its structural changes and thus determine whether the substance is indeed LFP and its performance characteristics. For instance, during charging, LFP gradually transforms into FePO4, and during discharging, it reverts to LiFePO4. This structural transformation can be detected by XRD, thus enabling its identification.

[0117] In some implementations, to further improve the accuracy of determining the type of electrode active material based on the first test results, Raman spectroscopy and X-ray diffraction (XRD) tests can be combined in the first test.

[0118] In some embodiments, when the electrode active material is graphite, the Raman spectroscopy test conditions are: a scanning range of 100–3200 cm⁻¹. -1 The laser power ranges from 5 to 200 mW. Raman spectroscopy testing conditions within this range minimize sample damage and are suitable for fine structural analysis. Higher power results in stronger signals that penetrate deeper into the sample.

[0119] For example, the scanning range of Raman spectroscopy testing includes, but is not limited to, 200–3200 cm⁻¹. -1300~3200cm -1 400~3200cm -1 500~3200cm -1 600~3200cm -1 700~3200cm -1 800~3200cm -1 900~3200cm -1 Or 1000~3200cm -1 wait.

[0120] For example, the laser power for Raman spectroscopy testing includes, but is not limited to, 60mW, 70mW, 80mW, 90mW, 100mW, 110mW, 120mW, 130mW, 140mW, 150mW, 160mW, 170mW, 180mW, or 190mW.

[0121] In other embodiments, when the electrode active material is non-graphite, especially the positive electrode active material, the Raman test conditions are: scan range 50-3200 cm⁻¹. -1 The laser wavelength is 532 / 633 / 785nm (ternary high-nickel), and the laser power is 0.2~0.5mW.

[0122] In some embodiments, the X-ray diffraction test conditions are as follows: scanning angle range: 10°-80°, graphite (002) crystal plane, focusing on the region where 2θ is between 25°-30°, step size of 0.01°, and spectrum correction: the spectrum is corrected using the internal standard method. The angle deviation is calculated based on the standard diffraction peak angle of silicon (111) (28.44135°) and the measured angle, and the angle of the (002) diffraction peak of graphite is corrected. Graphitization degree calculation: the graphitization degree G is calculated using the Franklin formula (Mering-Maire formula). The formula is: G = (0.3440 - d... 002 ) / (0.3440-0.3354)×100%, where 0.3440nm is the interlayer spacing of completely non-graphitized carbon and 0.3354nm is the interlayer spacing of ideal graphite crystal.

[0123] In the embodiments of this application, projection electron microscopy utilizes an electron beam with an extremely short wavelength as a "light source" to penetrate the sample. The electron beam changes direction (scattering) and energy (loss) due to its interaction with sample atoms. These changes are collected, amplified, and ultimately projected onto a detector by an electromagnetic lens system, forming an image with contrast (for morphology and structural observation) or diffraction patterns (for crystal structure analysis). This can be used to detect the surface coating characteristics of electrode active materials—whether the electrode active material has a coating layer or not.

[0124] For example, the conditions for the transmission electron microscopy test are: accelerating voltage of 100–200 kV and current density of 0.1–0.2 A / cm². 2 When the conditions for transmission electron microscopy are within the above range, higher resolution and clearer lattice fringes can be obtained.

[0125] For example, the accelerating voltages tested by the transmission electron microscope include, but are not limited to, 120kV, 140kV, 160kV, or 180kV.

[0126] For example, the current density measured by the transmission electron microscopy includes, but is not limited to, 0.12 A / cm². 2 0.14A / cm 2 0.15A / cm 2 0.17A / cm 2 0.19A / cm 2 Or 0.2A / cm 2 wait.

[0127] S104. Determine the type of the electrode active material based on the test results.

[0128] In the embodiments of this application, since the test results can reflect the characterization features of different materials, the type of electrode active material can be identified and determined based on the test results—the identification of different types of substances and the identification of different types of the same substance (if the test in step S103 also includes a second test, the type of electrode active material here also includes the identification of whether the same substance has a coating layer). The material type obtained by identification and determination is the type of electrode active material in the electrode material powder obtained by the micro-layer peeling treatment of the electrode sample to be tested in step S101. At least this method can be used to identify that the electrode to be tested contains the corresponding electrode active material.

[0129] Therefore, in some embodiments, determining the type of the electrode active material based on the test results includes:

[0130] Based on the results of the first test, determine the substance type or class of the electrode active material; and / or,

[0131] The coating characteristics of the electrode active material are determined based on the results of the second test.

[0132] To further identify the number of electrode material layers, thickness, and type of active electrode material in each layer of the coated electrode material, in some embodiments, the micro-layer peeling process is performed multiple times, and steps S102 to S104 are repeated after each micro-layer peeling process. Furthermore, the number of electrode material coating layers in the electrode sheet and / or the thickness of each electrode material coating layer can be obtained based on the type of active electrode material determined in step S104 after multiple micro-layer peeling processes.

[0133] In some embodiments, the method for determining the number of electrode material coating layers and / or the thickness of each electrode material coating layer in the electrode sheet based on the type of electrode material determined in step S104 after multiple microlayer peeling processes includes:

[0134] If the type of electrode active material obtained in step S104 is consistent after two consecutive micro-layer peeling processes, then they are determined to belong to the same electrode material coating layer.

[0135] If the types of electrode active materials obtained in step S104 after two adjacent micro-layer peeling processes are inconsistent, it is determined that they are not the same electrode material coating layer.

[0136] The number of times the type of the electrode active material determined in step S104 after two adjacent microlayer peeling processes is inconsistent is taken as the number of electrode material coating layers; and / or,

[0137] The thickness of the electrode material coating layer is the sum of the thicknesses of all micro-layer peeling processes that are determined to belong to the same electrode material coating layer after all consecutive micro-layer peeling processes in step S104.

[0138] In the embodiments of this application, when the test in step S103 does not include the second test, the consistency of the electrode active material type means that the substance type and model of the electrode active material determined in step S104 after two adjacent micro-layer peeling treatments are the same; when the test in step S103 includes the second test, the consistency of the electrode active material type means that the substance type, model, and coating characteristics of the electrode active material determined in step S104 after two adjacent micro-layer peeling treatments are the same. Conversely, when the test in step S103 does not include the second test, the inconsistency of the electrode active material type means that at least one of the substance type and model of the electrode active material determined in step S104 after two adjacent micro-layer peeling treatments is different; when the test in step S103 includes the second test, the inconsistency of the electrode active material type means that at least one of the substance type, model, and coating characteristics of the electrode active material determined in step S104 after two adjacent micro-layer peeling treatments is different.

[0139] To facilitate understanding of the method for determining the type of electrode material obtained in step S104 after multiple micro-layer peeling processes, and thus obtaining the number of electrode material coating layers and / or the thickness of each electrode material coating layer in the electrode sheet, the following explanation is provided using three micro-layer peeling processes as an example:

[0140] For example, the electrode sample to be tested (e.g., the sample in step S101) underwent three micro-exfoliation processes, with the remaining portion being the current collector. The thickness of the first micro-exfoliation process was 'a', the thickness of the second micro-exfoliation process was 'b', and the thickness of the third exfoliation process was 'c'. After the first, second, and third micro-exfoliation processes, steps S101 to S104 were performed sequentially.

[0141] (I) The test in step S103 is the first test. If the electrode active material obtained in step S104 after the first micro-layer exfoliation treatment is determined to be graphite A based on the first test result, the electrode active material obtained in step S104 after the second micro-layer exfoliation treatment is determined to be graphite A based on the first test result, and the electrode active material obtained in step S104 after the third micro-layer exfoliation treatment is determined to be graphite A based on the first test result, then it is determined that the electrode sample to be tested has only one electrode material coating layer (i.e., single-layer coating) with a thickness of a+b+c.

[0142] (ii) The test in step S103 is the first test. If the electrode active material obtained in step S104 after the first micro-exfoliation treatment is determined to be graphite A based on the first test result, the electrode active material obtained in step S104 after the second micro-exfoliation treatment is graphite A based on the first test result, and the electrode active material obtained in step S104 after the third micro-exfoliation treatment is graphite B based on the first test result, then it is determined that the electrode sample to be tested has two electrode material coating layers (i.e., double coating): the first and second micro-exfoliation treatments are for the same electrode material coating layer, which is the electrode material coating layer away from the current collector; the third micro-exfoliation treatment is for another electrode material coating layer, which is the electrode material coating layer closer to the current collector. The thickness of the electrode material coating layer away from the current collector is a+b, and the thickness of the electrode material coating layer closer to the current collector is c.

[0143] (III) The test in step S103 is the first test. If the electrode active material obtained in step S104 after the first micro-exfoliation treatment is determined to be graphite A based on the first test result, and the electrode active material obtained in step S104 after the second micro-exfoliation treatment is determined to be graphite B based on the first test result, and the electrode active material obtained in step S104 after the third micro-exfoliation treatment is determined to be graphite B based on the first test result, then it is determined that the electrode sample to be tested has two electrode material coating layers (i.e., double coating): the first micro-exfoliation treatment is one electrode material coating layer, which is the electrode material coating layer away from the current collector; the second and third micro-exfoliation treatments are another identical electrode material coating layer, which is the electrode material coating layer closer to the current collector. The thickness of the electrode material coating layer away from the current collector is a, and the thickness of the electrode material coating layer closer to the current collector is b+c.

[0144] IV) The test in step S103 is the first test. If the electrode active material obtained in step S104 after the first micro-exfoliation treatment is graphite A, the electrode active material obtained in step S104 after the second micro-exfoliation treatment is graphite B, and the electrode active material obtained in step S104 after the third micro-exfoliation treatment is graphite C, then the electrode sample to be tested is determined to have three electrode material coating layers (i.e., three-layer coating): the first micro-exfoliation treatment is one electrode material coating layer, which is the electrode material coating layer away from the current collector; the second micro-exfoliation treatment is another electrode material coating layer, which is the middle electrode material coating layer; and the third micro-exfoliation treatment is yet another electrode material coating layer, which is the electrode material coating layer closer to the current collector. The thickness of the electrode material coating layer away from the current collector is a, the thickness of the electrode material coating layer closer to the current collector is c, and the thickness of the middle electrode material coating layer is b.

[0145] V) The test in step S103 is the first test. If the electrode active material obtained in step S104 after the first micro-exfoliation treatment is determined to be substance A based on the first test result, the electrode active material obtained in step S104 after the second micro-exfoliation treatment is determined to be substance B based on the first test result, and the electrode active material obtained in step S104 after the third micro-exfoliation treatment is determined to be substance C based on the first test result, then it is determined that the electrode sample to be tested has three electrode material coating layers (i.e., three-layer coating): the first micro-exfoliation treatment is one electrode material coating layer, which is the electrode material coating layer away from the current collector; the second micro-exfoliation treatment is another electrode material coating layer, which is the middle electrode material coating layer; and the third micro-exfoliation treatment is yet another electrode material coating layer, which is the electrode material coating layer closer to the current collector. The thickness of the electrode material coating layer away from the current collector is a, the thickness of the electrode material coating layer closer to the current collector is c, and the thickness of the middle electrode material coating layer is b.

[0146] VI) The test in step S103 is the first test. If the electrode active material obtained in step S104 after the first micro-exfoliation treatment is determined to be substance A based on the first test result, the electrode active material obtained in step S104 after the second micro-exfoliation treatment is determined to be substance A based on the first test result, and the electrode active material obtained in step S104 after the third micro-exfoliation treatment is determined to be substance B based on the first test result, then it is determined that the electrode sample to be tested has two electrode material coating layers (i.e., double coating): the first and second micro-exfoliation treatments are for the same electrode material coating layer, which is the electrode material coating layer away from the current collector; the third micro-exfoliation treatment is for another electrode material coating layer, which is the electrode material coating layer closer to the current collector. The thickness of the electrode material coating layer away from the current collector is a+b, and the thickness of the electrode material coating layer closer to the current collector is c.

[0147] VII) The tests in step S103 are the first test and the second test. If, after the first micro-exfoliation treatment, step S104 determines that the electrode active material obtained is graphite A based on the first test result, and the second test result determines that the electrode active material has a coating layer; after the second micro-exfoliation treatment, step S104 determines that the electrode active material obtained is graphite A based on the first test result, and the second test result determines that the electrode active material does not have a coating layer; after the third micro-exfoliation treatment, step S104 determines that the electrode active material obtained is graphite A based on the first test result, and the second test result determines that the electrode active material does not have a coating layer; then it is determined that the electrode sample to be tested has two electrode material coating layers (i.e., double coating): the first micro-exfoliation treatment is one electrode material coating layer, which is the electrode material coating layer away from the current collector; the second and third micro-exfoliation treatments are another identical electrode material coating layer, which is the electrode material coating layer closer to the current collector. The thickness of the electrode material coating layer away from the current collector is 'a', and the thickness of the electrode material coating layer closer to the current collector is 'b+c'.

[0148] VIII) The tests in step S103 are the first test and the second test. If, after the first micro-layer peeling treatment, step S104 determines that the electrode active material obtained is substance A based on the first test result, and the second test result determines that the electrode active material has a coating layer; after the second micro-layer peeling treatment, step S104 determines that the electrode active material obtained is substance A based on the first test result, and the second test result determines that the electrode active material does not have a coating layer; after the third micro-layer peeling treatment, step S104 determines that the electrode active material obtained is substance B based on the first test result, and the second test result determines that the electrode active material does not have a coating layer; then it is determined that the electrode sample to be tested has three electrode material coating layers (i.e., three-layer coating): the first micro-layer peeling treatment is one electrode material coating layer, which is the electrode material coating layer away from the current collector; the second micro-layer peeling treatment is another electrode material coating layer, which is the middle electrode material coating layer; and the third micro-layer peeling treatment is yet another electrode material coating layer, which is the electrode material coating layer closer to the current collector. The thickness of the electrode material coating layer on the side furthest from the current collector is a, the thickness of the electrode material coating layer on the side closest to the current collector is c, and the thickness of the electrode material coating layer in the middle is b.

[0149] It should be noted that in I) to VIII) above, graphite A, graphite B and graphite C represent three different types of graphite, and substance A, substance B and substance C represent three different substances.

[0150] It should also be noted that in the embodiments of this application, the overall thickness of the electrode is measured before the microlayer is peeled off, and then the thickness of the current collector is measured. When setting the peeling thickness, excessive peeling and scratching of the current collector can be avoided.

[0151] In some embodiments, the thickness of each microlayer exfoliation treatment is 1–40 μm, including but not limited to 3 μm, 5 μm, 7 μm, 9 μm, 11 μm, 13 μm, 15 μm, 17 μm, 19 μm, 21 μm, 23 μm, 25 μm, 27 μm, 29 μm, 31 μm, 33 μm, 35 μm, 37 μm, 39 μm, 41 μm, 43 μm, 45 μm, 47 μm, or 49 μm, and optionally 5–10 μm. The thickness of each microlayer exfoliation treatment within the above range can be adjusted according to the required analytical precision and the different thicknesses of the sample, allowing for the gradual analysis of the components of each layer of the electrode.

[0152] It should be noted that, regardless of whether the micro-layer peeling process in step S101 is performed once or multiple times (more than twice), the micro-layer peeling process ends at the current collector, that is, only the electrode material layer on the surface of the current collector is micro-peeled. In addition, if the micro-layer peeling process in step S101A is performed once, its peeling thickness can be 1 to 40 μm, or it can be more than 1 μm but less than the total thickness of multiple micro-layer peelings.

[0153] In some embodiments, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes the step of analyzing and detecting the content of each component in the electrode to be tested.

[0154] For example, when the electrode to be tested is a negative electrode material composed of carbon material, aqueous binder and aqueous dispersant, and the carbon material is composed of graphite and carbon-based conductive agent, the content of each component in the electrode to be tested is analyzed and detected using the detection method described in the applicant's Chinese patent application with publication number CN 119845776 A (invention title: an analytical detection method and application for the content of a negative electrode material formulation).

[0155] As an optional example, the electrode to be tested is a fresh negative electrode for a lithium-ion battery (labeled as negative electrode A), and the electrode material coating layer includes graphite, carboxymethyl cellulose (CMC), and styrene-butadiene and its modified organic emulsion (SBR). It is necessary to determine the type of graphite, the number of electrode material coating layers, and the thickness of each coating layer. Therefore, this method for identifying the core characteristics of new energy battery cell electrodes based on coating technology includes the following steps:

[0156] Step 1: Take negative electrode sample A, clean and dry its surface, then perform multiple micro-layer peeling processes until only the current collector remains. Collect and sieve the products from each micro-layer peeling process to obtain multiple samples with an average particle size of 5~

[0157] 15μm anode material powder.

[0158] Each microlayer peeling process involves a thickness of 1–40 μm.

[0159] Step 2: Dry the multiple portions of negative electrode material powder obtained in Step 1, and then heat them at 200–300°C respectively.

[0160] Distillation and reflux treatment was carried out under a vacuum of 0.1 to 0.5 Pa to remove CMC and SBR, and the volatile organic compounds discharged during the distillation process were collected to obtain multiple negative electrode active materials.

[0161] Step 3: Perform Raman spectroscopy and transmission electron microscopy tests on the multiple negative electrode active materials obtained in Step 2. Analyze their surface defects by Raman spectroscopy and analyze their coating layer characteristics by transmission electron microscopy.

[0162] The conditions for Raman spectroscopy testing were as follows: a scanning range of 100–3200 cm⁻¹. -1 The laser power was 5–200 mW; the transmission electron microscope (TEM) testing conditions were: accelerating voltage of 100–200 kV and current density of 0.1–0.2 A / cm². 2 .

[0163] Step 4: Based on the Raman spectroscopy test results of each negative electrode active material in Step 3, determine the type of graphite corresponding to each negative electrode active material. Based on the transmission electron microscopy test results of each negative electrode active material in Step 3, determine the coating characteristics of each negative electrode active material (i.e., whether the graphite is graphite with a coating layer or graphite without a coating layer).

[0164] Step 5: Based on the judgment result of Step 4, further determine whether the graphite type and coating characteristics of the negative electrode active material are completely the same after two adjacent micro-layer peeling treatments in Step 1, and whether the graphite type and coating characteristics of the negative electrode active material are different after at least one of the two adjacent micro-layer peeling treatments in Step 1, and whether they belong to different negative electrode material layers.

[0165] Step 6: The number of times that the type of graphite of the negative electrode active material and the coating characteristics are inconsistent after two consecutive micro-layer peeling treatments as determined in Step 5 is taken as the number of negative electrode material coating layers. The thickness of the negative electrode material coating layer is taken as the sum of the thicknesses of all micro-layer peeling treatments that are determined to belong to the same negative electrode material coating layer after all consecutive micro-layer peeling treatments.

[0166] As another alternative example, the electrode to be tested is known to be a fresh negative electrode for lithium-ion batteries (labeled as negative electrode A), and the electrode material coating layers include graphite, carboxymethyl cellulose (CMC), and styrene-butadiene and its modified organic emulsion (SBR). It is necessary to determine the type of graphite, the number of electrode material coating layers, and the thickness of each coating layer. Therefore, this method for identifying the core characteristics of new energy battery cell electrodes based on coating technology includes the following steps:

[0167] Step 1: Take negative electrode sample A, clean and dry its surface, then perform multiple micro-layer peeling processes until only the current collector remains. Collect and sieve the products from each micro-layer peeling process to obtain multiple samples with an average particle size of 5~

[0168] 15μm negative electrode material powder.

[0169] Each microlayer peeling has a thickness of 1–40 μm.

[0170] Step 2: Dry the multiple negative electrode material powders obtained in Step 1, and then perform distillation reflux treatment at 200-300℃ and 0.1-0.5Pa vacuum to remove CMC and SBR, and collect the volatile organic compounds discharged during the distillation process to obtain multiple negative electrode active materials.

[0171] Step 3: Perform Raman spectroscopy tests on the multiple negative electrode active materials obtained in Step 2 to analyze their surface defects.

[0172] The conditions for Raman spectroscopy testing were as follows: a scanning range of 100–3200 cm⁻¹. -1 The laser power is 5–200 mW.

[0173] Step 4: Determine the type of graphite corresponding to each negative electrode active material based on the Raman spectroscopy test results of each negative electrode active material in Step 3.

[0174] Step 5: Based on the judgment result of Step 4, further determine whether the graphite type of the negative electrode active material after two adjacent micro-layer peeling treatments in Step 1 is exactly the same negative electrode material coating layer, and whether the graphite type of the negative electrode active material after two adjacent micro-layer peeling treatments in Step 1 is different, and whether they belong to different negative electrode material layers.

[0175] Step 6: The number of times the type of graphite of the negative electrode active material determined in Step 5 is inconsistent after two consecutive micro-layer peeling treatments is taken as the number of negative electrode material coating layers. The thickness of the negative electrode material coating layer is taken as the sum of the thicknesses of all micro-layer peeling treatments that were determined to belong to the same negative electrode material coating layer after all consecutive micro-layer peeling treatments.

[0176] In some embodiments, when the electrode to be tested includes a positive electrode after battery cycling or a negative electrode after battery cycling, the method for identifying the core characteristics of the electrode of a new energy cell based on coating technology further includes: if the test results cannot be used to determine the type of the electrode active material, then another part of the sample in the electrode to be tested is selected and steps S101 to S104 are repeated until step S104 can determine the type of the electrode active material based on the test results, at which point the replacement of samples from different parts of the electrode to be tested is stopped.

[0177] It should be noted that when the electrode to be tested includes a positive electrode after battery cycling or a negative electrode after battery cycling and the micro-layer peeling process is repeated multiple times, in order to save time, if the type of electrode active material cannot be determined based on the test results in step S104 after the first micro-layer peeling process, another part of the sample in the electrode to be tested can be selected and steps S101 to S104 can be repeated until the type of electrode active material can be determined based on the test results in step S104. Then, the sample from different parts of the electrode to be tested is replaced, and the subsequent multiple micro-layer peeling processes and steps S102 to S104 after each micro-layer peeling process are performed. This enables the identification of the type, type, and coating characteristics of the electrode active material in each coating layer of the coated electrode material, as well as the identification of the number of coating material layers and the thickness of each coating material layer.

[0178] The method for identifying the core characteristics of new energy battery cell electrodes based on coating technology in this application embodiment can bring at least the following beneficial effects:

[0179] 1. By combining microlayer exfoliation, distillation reflux, and Raman spectroscopy / XRD tests, the interference of binders and dispersants in the negative electrode material can be eliminated, and the type of electrode active material in the coated electrode material can be determined.

[0180] 2. By performing transmission electron microscopy on the electrode active material obtained after microlayer peeling and distillation reflux, the coating characteristics of the electrode active material can be analyzed, and it can be determined whether the electrode active material is a coated electrode active material, thus achieving comprehensive detection of the coated electrode structure.

[0181] 3. When performing multiple micro-layer peeling processes, the number of coating layers, the thickness of each coating layer, and the type of active material of the electrode can be obtained by combining multiple micro-layer peeling with distillation reflux, Raman spectroscopy / XRD testing, etc. This enables effective decomposition of unknown electrodes, solves the problem of accurately distinguishing coating material types in existing technologies, and overcomes the limitation of related technologies that can only detect single-layer materials. It provides important reference data for the research and development of coating electrodes with single or multiple layers, and helps researchers better understand the actual effects of coating technology, especially double-layer coating technology.

[0182] 4. The micro-layer peeling technology and distillation reflux method adopted are simple and feasible to operate, easy to industrialize, and have good practical value and prospects for promotion and application.

[0183] 5. This method for identifying the core characteristics of new energy battery cell electrodes based on coating technology can serve as an effective means of investigating infringement risks. By analyzing the materials and other aspects of competitors' double-layer coating technology, it can assess their technical characteristics and provide important references for enterprises' R&D and strategic decision-making.

[0184] The method for identifying the core characteristics of new energy cell electrode sheets based on coating technology in this application embodiment can be prevented from being applied to the production of secondary batteries, especially lithium-ion batteries.

[0185] In some embodiments, when the electrode is a negative electrode having two layers of electrode material coating with different graphite types in each layer, the electrode must satisfy at least one of the following characteristics:

[0186] (1) The compaction density of the electrode material coating layer on the side away from the current collector is 1.5–1.8 g / cm³. 3 ;

[0187] (2) The areal density of the electrode material coating layer on the side away from the current collector is 2-3 mg / cm³. 2 ;

[0188] (3) The compaction density of the electrode material coating layer near the current collector is 1.2–1.5 g / cm³. 3 ;

[0189] (4) The areal density of the electrode material coating layer near the current collector is 4–6 mg / cm³. 2 ;

[0190] (5) The thickness ratio of the electrode material coating layer on the side away from the current collector to the electrode material coating layer on the side closer to the current collector is 1:(3-6).

[0191] In the embodiments of this application, when the electrode is a negative electrode with two layers of electrode material coating and each layer has a different type of graphite, the compaction density of the electrode material coating layer on the side of the electrode away from the current collector is 1.5–1.8 g / cm³. 3 This can improve energy density, increase mechanical strength, and reduce interfacial impedance, thus improving rate performance; the areal density of the electrode material coating layer on the side of the electrode away from the current collector is 2–3 mg / cm³. 2 It achieves a balance between capacity and rate performance, meeting certain energy requirements while ensuring ion transport efficiency. The coating process is of moderate difficulty, facilitating large-scale production. The compaction density of the electrode material coating layer on the side of the electrode closest to the current collector is 1.2–1.5 g / cm³. 3 This ensures electrode stability without hindering electrolyte penetration due to excessively low porosity; the areal density of the electrode material coating layer on the side of the electrode closest to the current collector is 4–6 mg / cm³. 2 This can significantly increase battery capacity and is suitable for large-capacity batteries with high energy density requirements. The thickness ratio of the electrode material coating layer on the side away from the current collector to the electrode material coating layer on the side close to the current collector is 1:(3~6). It can be designed according to actual needs, and the thickness ratio can be flexibly matched according to different application scenarios to optimize the battery system, reduce costs, and improve cycle performance.

[0192] For example, the compaction density of the electrode material coating layer on the side of the electrode sheet away from the current collector includes, but is not limited to, 1.55 g / cm³. 3 1.6g / cm 3 1.65g / cm 3 1.7g / cm 3 Or 1.75g / cm 3 wait.

[0193] For example, the areal density of the electrode material coating layer on the side of the electrode away from the current collector includes, but is not limited to, 2.1 mg / cm³. 2 2.2 mg / cm 2 2.3 mg / cm 2 2.4 mg / cm 2 2.5 mg / cm 2 2.6 mg / cm 2 2.7 mg / cm 2 2.8 mg / cm 2 Or 2.9 mg / cm 2 wait.

[0194] For example, the compaction density of the electrode material coating layer on the side of the electrode sheet near the current collector includes, but is not limited to, 1.25 g / cm³. 3 1.3g / cm 3 1.35g / cm 3 1.4g / cm 3 Or 1.45g / cm 3 wait.

[0195] For example, the areal density of the electrode material coating layer on the side of the electrode sheet closest to the current collector includes, but is not limited to, 4.1 mg / cm³. 2 4.2 mg / cm 2 4.3 mg / cm 2 4.4 mg / cm 2 4.5 mg / cm 2 4.6 mg / cm 2 4.7 mg / cm 2 4.8 mg / cm 2 4.9 mg / cm 2 5mg / cm 2 5.1 mg / cm 2 5.2 mg / cm 2 5.3 mg / cm 2 5.4 mg / cm 2 5.5 mg / cm 2 5.6 mg / cm2 5.7 mg / cm 2 5.8 mg / cm 2 Or 5.9 mg / cm 2 wait.

[0196] For example, the thickness ratio of the electrode material coating layer on the side of the electrode sheet away from the current collector and the electrode material coating layer on the side of the electrode sheet close to the current collector includes, but is not limited to, 1:3.5, 1:4, 1:4.5, 1:5 or 1:5.5.

[0197] The following non-limiting embodiments further illustrate certain features of the present technology.

[0198] In the following embodiments and comparative examples involving micro-layer peeling, the overall thickness of the electrode sheet is measured before micro-layer peeling, and then the thickness of the current collector is measured. When setting the peeling thickness, excessive peeling and scratching of the current collector can be avoided.

[0199] Example 1

[0200] A fresh negative electrode (labeled as negative electrode A1-1) is known to include a current collector 1 and a first negative electrode material coating layer 2 and a second negative electrode material coating layer 3 (e.g., ...) stacked sequentially on the surface of the current collector 1 from the side away from the current collector 1 to the side closer to the current collector 1. Figure 2 (As shown); the first negative electrode material coating layer 2 and the second negative electrode material coating layer 3 are both composed of negative electrode active material, negative electrode conductive agent, negative electrode dispersant and negative electrode binder, and the negative electrode conductive agent is conductive carbon black (Super), the negative electrode dispersant is carboxymethyl cellulose (CMC) and the negative electrode binder is styrene-butadiene and its modified organic emulsion (SBR); the negative electrode active material in the first negative electrode material coating layer 2 is 4C fast-charging graphite and contains a coating layer; the negative electrode active material in the second negative electrode material coating layer 3 is 2C fast-charging graphite and does not contain a coating layer; the thickness of the first negative electrode material coating layer 2 is 10μm and the thickness of the second negative electrode material coating layer 3 is 40μm.

[0201] The inventors, knowing the following information about the fresh negative electrode A1-1: "The fresh negative electrode A1-1 is a negative electrode with a negative electrode material layer coated on a current collector. The negative electrode material coating layer is composed of a negative electrode active material, a negative electrode conductive agent, a negative electrode dispersant, and a negative electrode binder. The negative electrode conductive agent is conductive carbon black (Super), the negative electrode dispersant is carboxymethyl cellulose (CMC), the negative electrode binder is styrene-butadiene and its modified organic emulsion (SBR), the negative electrode active material is graphite, and the total thickness of the negative electrode material coating layer is 50 μm," but not knowing the number of coating layers, the thickness of each coating layer, or the type of graphite in the coating layer, used the core characteristic identification method for new energy battery cell electrodes based on coating technology in this embodiment to identify the above information.

[0202] The core characteristic identification method for new energy battery cell electrodes based on coating technology in this embodiment includes the following steps:

[0203] Step 1: The negative electrode A1-1 sample was subjected to micro-layer peeling treatment every 10μm from the side away from the current collector to the side closer to the current collector until only the current collector was retained. A total of 5 micro-layer peeling treatments were performed. After each micro-layer peeling treatment, the product obtained was placed in a 200-mesh standard sieve and shaken for 30 minutes for sieving. Five negative electrode material powders with an average particle size of 5-15μm were collected.

[0204] The micro-layer peeling process is as follows: the two ends of the negative electrode A1-1 sample are fixed on the fixture of the micro-layer peeling device (electrode binber floating tester, Chuanyuan Technology Co., Ltd.), the single-layer peeling thickness is set to 10μm by the software of the micro-layer peeling device, and the process is repeated five times, with powder samples collected from the bottom in each instance.

[0205] Step 2: Place the 5 portions of negative electrode material powder obtained in Step 1 into a vacuum drying oven and dry them at 70°C for 6 hours. Then, distill and reflux each dried powder at 250°C and 0.3Pa vacuum for 4 hours to remove CMC and SBR. Collect the volatile organic compounds discharged during the distillation process to obtain 5 portions of negative electrode active material.

[0206] Step 3: Perform Raman spectroscopy and transmission electron microscopy tests on the five negative electrode active materials obtained in Step 2 respectively, and determine the type of graphite material based on the results of Raman spectroscopy and transmission electron microscopy tests.

[0207] The method of determining the type of graphite material based on the results of Raman spectroscopy and transmission electron microscopy includes: analyzing their surface defects through Raman spectroscopy to determine the type of graphite corresponding to each negative electrode active material; and analyzing their coating characteristics (i.e., whether the graphite is coated or uncoated) through transmission electron microscopy.

[0208] The conditions for Raman spectroscopy testing were: a scanning range of 100–3200 cm⁻¹. -1 The laser power was 100mW; the conditions for transmission electron microscopy testing were: acceleration voltage of 8kV and current density of 30mA.

[0209] The results of Raman spectroscopy and transmission electron microscopy tests of the five negative electrode active materials obtained in step 2, and the information on the graphite type obtained based on their test results are shown in Table 1.

[0210] Table 1

[0211]

[0212]

[0213] Note: In Table 1, "x#" represents the xth negative electrode active material obtained after the xth micro-layer exfoliation and distillation reflux treatment, and is labeled as negative electrode active material x#. Taking "1#" as an example, it represents the first negative electrode active material obtained after the first micro-layer exfoliation and distillation reflux treatment, and is labeled as negative electrode active material 1#.

[0214] Step 4: Based on the judgment results in Table 1 of Step 3, further determine whether the graphite type and coating characteristics of the negative electrode active material are completely the same after two adjacent micro-layer peeling treatments in Step 1, and whether the graphite type and coating characteristics of the negative electrode active material are different after at least one of the two adjacent micro-layer peeling treatments in Step 1, and whether they belong to different negative electrode material layers.

[0215] Specifically:

[0216] Since only the negative electrode active material 1# in Table 1 has 4C graphite as its graphite type and contains a coating layer, the negative electrode active material 1# is a negative electrode material coating layer.

[0217] Since the graphite type of negative electrode active materials 2# to 5# in Table 1 is all 2C graphite and none of them contain a coating layer, negative electrode active materials 2#, 3#, 4# and 5# belong to the same negative electrode material coating layer.

[0218] Step 5: The number of times that the type of graphite of the negative electrode active material and the coating characteristics determined in Step 4 are inconsistent after two consecutive micro-layer peeling treatments is taken as the number of negative electrode material coating layers. The thickness of the negative electrode material coating layer is taken as the sum of the thicknesses of all micro-layer peeling treatments that are determined to belong to the same negative electrode material coating layer after all consecutive micro-layer peeling treatments.

[0219] Specifically:

[0220] Based on step 4, it is determined that the negative electrode sample of this embodiment has two negative electrode material coating layers, wherein:

[0221] Because the micro-layer exfoliation process is performed earlier for negative electrode active material 1#, the thickness of the negative electrode material coating layer on the side away from the current collector is the same as the thickness of the first micro-layer exfoliation process for negative electrode active material 1#, which is 10μm.

[0222] Because the microlayer peeling treatment of negative electrode active materials 2#, 3#, 4#, and 5# is performed later, the thickness of the negative electrode material coating layer on the side closest to the current collector is the sum of the thicknesses of the second, third, fourth, and fifth microlayer peeling treatments for negative electrode active materials 2#, 3#, 4#, and 5#, respectively, which is 40μm.

[0223] Application Example 1

[0224] Based on the core characteristic identification method of new energy cell electrode sheets based on coating technology in Example 1, the identification results are used in the design of lithium-ion battery negative electrode sheets, as follows:

[0225] Adopting such Figure 2 The negative electrode sheet shown has a thickness ratio of 1:4 for the first negative electrode material coating layer 101 and the second negative electrode material coating layer 102, and the compaction density of the first negative electrode material coating layer 101 is 1.6 g / cm³. 3 The compaction density of the second negative electrode material coating layer 102 is 1.4 g / cm³. 3 The areal density of the first negative electrode material coating layer 101 is 2.5 g / cm³. 3 The areal density of the second negative electrode material coating layer 102 is 5 g / cm³. 3 .

[0226] Example 2

[0227] This embodiment is basically the same as Embodiment 1, with the main difference being that the negative electrode sample A1 was assembled into a lithium-ion battery and cycled 359 times, and is labeled as negative electrode A1-2. Meanwhile, since some areas of the negative electrode after cycling may be affected by lithium plating, white spots, black spots, foreign matter breakdown, etc., it is necessary to first determine whether Raman spectroscopy can determine the type of graphite material. If not, different areas of the same electrode need to be selected for identification until it is determined that Raman spectroscopy can determine the type of graphite material, and then the identification method of this application is used for identification. Specifically:

[0228] The core characteristic identification method for new energy battery cell electrodes based on coating technology in this embodiment includes the following steps:

[0229] Step 1: Take the middle part of the negative electrode A1-2 as a sample, clean the surface with anhydrous ethanol to remove the electrolyte, and dry it at 60℃ for 4 hours. Then, perform the first micro-layer exfoliation treatment of 10μm from the side away from the current collector to the side closer to the current collector. After the first micro-layer exfoliation treatment, place the product in a 200-mesh standard sieve and shake for 30 minutes to sieve, and collect the negative electrode material powder with a particle size of 5-15μm.

[0230] The micro-layer peeling process is as follows: the two ends of the negative electrode A1-2 sample are fixed on the fixture of the micro-layer peeling device (electrode binber floating tester, Chuanyuan Technology Co., Ltd.), the single-layer peeling thickness is set to 10μm through the software of the micro-layer peeling device, and the powder sample is collected in the sample box at the bottom of the device.

[0231] Step 2: Place the negative electrode material powder obtained in Step 1 in a vacuum drying oven and dry it at 70°C for 6 hours. Then, distill and reflux the dried powder at 250°C and 0.3Pa vacuum for 3 hours to remove CMC and SBR. Collect the volatile organic compounds discharged during the distillation process to obtain the negative electrode active material, which is labeled as negative electrode active material M1#.

[0232] Step 3: Perform Raman spectroscopy and transmission electron microscopy tests on the negative electrode active material M1# obtained in Step 2, and determine the type of graphite material based on the results of the Raman spectroscopy and transmission electron microscopy tests.

[0233] The determination of graphite material type based on Raman spectroscopy and transmission electron microscopy results includes: analyzing surface defects through Raman spectroscopy to determine the type of negative electrode active material M1# graphite; and analyzing coating characteristics (i.e., whether the graphite is coated or uncoated) through transmission electron microscopy.

[0234] The conditions for Raman spectroscopy testing were: a scanning range of 100–3200 cm⁻¹. -1 The laser power was 100mW; the conditions for transmission electron microscopy testing were: acceleration voltage of 8kV and current density of 30mA.

[0235] The results of Raman spectroscopy and transmission electron microscopy tests are shown in Table 2.

[0236] Table 2

[0237]

[0238] Based on Table 2, the type of graphite material cannot be determined.

[0239] Step 4: Take a portion of the left side of the negative electrode A1-2 as a sample, clean the surface with anhydrous ethanol to remove the electrolyte, and dry it at 60℃ for 4 hours. Then, perform the first micro-layer exfoliation treatment of 10μm from the side away from the current collector to the side closer to the current collector. After the first micro-layer exfoliation treatment, place the product in a 200-mesh standard sieve and shake for 30 minutes for sieving to collect negative electrode material powder with an average particle size of 5-15μm.

[0240] The micro-layer peeling process involves fixing both ends of the negative electrode A1-2 sample onto the fixture of the micro-layer peeling device, setting the single-layer peeling thickness to 10 μm using software, and collecting the powder sample in the sample box at the bottom of the device.

[0241] Step 5: Place the negative electrode material powder obtained in Step 4 in a vacuum drying oven and dry it at 70°C for 6 hours. Then, distill and reflux the dried powder at 250°C and 0.3Pa vacuum for 4 hours to remove CMC and SBR. Collect the volatile organic compounds discharged during the distillation process to obtain the negative electrode active material, which is labeled as negative electrode active material L1#.

[0242] Step 6: Perform Raman spectroscopy and transmission electron microscopy tests on the negative electrode active material L1# obtained in Step 5, and determine the type of graphite material based on the results of the Raman spectroscopy and transmission electron microscopy tests.

[0243] The determination of graphite material type based on Raman spectroscopy and transmission electron microscopy results includes: analyzing surface defects through Raman spectroscopy to determine the type of negative electrode active material L1# graphite; and analyzing coating characteristics (i.e., whether the graphite is coated or uncoated) through transmission electron microscopy.

[0244] The conditions for Raman spectroscopy testing were: a scanning range of 100–3200 cm⁻¹. -1 The laser power was 100mW; the conditions for transmission electron microscopy testing were: acceleration voltage of 8kV and current density of 30mA.

[0245] The results of Raman spectroscopy and transmission electron microscopy tests are shown in Table 3.

[0246] Table 3

[0247]

[0248] As can be seen, the type of graphite material can be identified based on the test results in Table 3.

[0249] Step 7: Continue to perform micro-layer peeling treatment on the left side of the negative electrode A1-2 sample from the side away from the current collector to the side closer to the current collector, every 10 μm, until only the current collector is retained. A total of 4 micro-layer peeling treatments were performed (corresponding to the 2nd, 3rd, 4th and 5th micro-layer peeling treatments respectively). After each micro-layer peeling treatment, the product obtained was placed in a 200-mesh standard sieve and shaken for 30 minutes for sieving, and 4 portions of negative electrode material powder with a particle size of 5-15 μm were collected.

[0250] The micro-layer peeling process is as follows: the two ends of the sample on the left side of the negative electrode A1-2 are fixed on the fixture of the micro-layer peeling device, the single-layer peeling thickness is set to 10μm by the software, the peeling is set to 4 times by the software, and the powder sample is collected in the sample box at the bottom of the device.

[0251] Step 8: Place the four negative electrode material powders obtained in Step 7 into a vacuum drying oven and dry them at 70°C for 6 hours. Then, distill and reflux each dried powder at 250°C and 3Pa vacuum for 4 hours to remove CMC and SBR. Collect the volatile organic compounds discharged during the distillation process to obtain four negative electrode active materials.

[0252] Step 9: Perform Raman spectroscopy and transmission electron microscopy tests on the four negative electrode active materials obtained in Step 8, and determine the type of graphite material based on the results of the Raman spectroscopy and transmission electron microscopy tests.

[0253] The method of determining the type of graphite material based on the results of Raman spectroscopy and transmission electron microscopy includes: analyzing their surface defects through Raman spectroscopy to determine the type of graphite corresponding to each negative electrode active material; and analyzing their coating characteristics (i.e., whether the graphite is coated or uncoated) through transmission electron microscopy.

[0254] The conditions for Raman spectroscopy testing were: a scanning range of 100–3200 cm⁻¹. -1 The laser power was 100mW; the conditions for transmission electron microscopy testing were: acceleration voltage of 8kV and current density of 30mA.

[0255] The results of Raman spectroscopy and transmission electron microscopy of the four negative electrode active materials obtained in step 8, and the information on the graphite type obtained based on their test results are shown in Table 4.

[0256] Table 4

[0257]

[0258] Note: In Table 1, "Lx#" represents the xth negative electrode active material obtained after the xth micro-layer peeling and distillation reflux treatment of the left side of the negative electrode A1-2, and is labeled as negative electrode active material Lx#. Taking "L2#" as an example, it represents the second negative electrode active material obtained after the second micro-layer peeling and distillation reflux treatment of the left side of the negative electrode A1-2, and is labeled as negative electrode active material L2#.

[0259] Step 10: Based on the judgment results in Table 3-4, further determine whether the graphite type and coating characteristics of the negative electrode active material are completely identical after the first micro-layer peeling treatment to the fifth micro-layer peeling treatment on the left side of the negative electrode A1-2, which belong to the same negative electrode material coating layer, or whether the graphite type and coating characteristics of the negative electrode active material are different after at least one of the two micro-layer peeling treatments, which belong to different negative electrode material layers.

[0260] Specifically:

[0261] Since only the negative electrode active material L1# in Table 3 has 4C graphite as its graphite type and contains a coating layer, the negative electrode active material 1# is a negative electrode material coating layer.

[0262] Since the graphite type of negative electrode active materials L2# to L5# in Table 4 is 2C graphite and none of them have a coating layer, negative electrode active materials L2#, L3#, L4# and L5# belong to the same negative electrode material coating layer.

[0263] Step 11: Based on the judgment results in Table 3-4, the number of times that the type of graphite and the coating characteristics of the negative electrode active material determined in Step 10 are inconsistent between two adjacent micro-layer peeling treatments from the first to the fifth micro-layer peeling treatment on the left side of the negative electrode sheet A1-2 is taken as the number of negative electrode material coating layers. The thickness of the negative electrode material coating layer is taken as the sum of the thicknesses of all micro-layer peeling treatments that are determined to belong to the same negative electrode material coating layer in Step 10 after all consecutive micro-layer peeling treatments.

[0264] Specifically:

[0265] Based on step 10, it is determined that the negative electrode sample of this embodiment has two negative electrode material coating layers, wherein:

[0266] Because the micro-layer exfoliation process of negative electrode active material L1# is performed earlier, the thickness of the negative electrode material coating layer on the side away from the current collector is the same as the thickness of the first micro-layer exfoliation process corresponding to negative electrode active material L1#, which is 10μm.

[0267] Because the microlayer peeling treatment of negative electrode active materials L2#, L3#, L4#, and L5# is performed later in the process, the thickness of the negative electrode material coating layer on the side closest to the current collector is the sum of the thicknesses of the second, third, fourth, and fifth microlayer peeling treatments for negative electrode active materials L2#, L3#, L4#, and L5#, respectively, which is 40 μm.

[0268] Example 3

[0269] A fresh negative electrode (labeled as negative electrode A2-1) is known to include a current collector 1 and a first negative electrode material coating layer 2 and a second negative electrode material coating layer 3 (e.g., ...) stacked sequentially on the surface of the current collector 1 from the side away from the current collector to the side closer to the current collector 1. Figure 2 (As shown); the first negative electrode material coating layer 2 and the second negative electrode material coating layer 3 are both composed of negative electrode active material, negative electrode conductive agent, negative electrode dispersant and negative electrode binder, and the negative electrode conductive agent is conductive carbon black (Super), the negative electrode dispersant is carboxymethyl cellulose (CMC) and the negative electrode binder is styrene-butadiene and its modified organic emulsion (SBR); the negative electrode active material in the first negative electrode material coating layer 2 is 2C fast-charging graphite and does not contain a coating layer; the negative electrode active material in the second negative electrode material coating layer 3 is 6C fast-charging graphite and contains a coating layer; the thickness of the first negative electrode material coating layer 2 is 20μm and the thickness of the second negative electrode material coating layer 3 is 100μm.

[0270] The inventors, knowing the following information about the fresh negative electrode A2-1: "The fresh negative electrode A2-1 is a negative electrode with a negative electrode material layer coated on a current collector. The negative electrode material coating layer is composed of a negative electrode active material, a negative electrode conductive agent, a negative electrode dispersant, and a negative electrode binder. The negative electrode conductive agent is conductive carbon black (Super), the negative electrode dispersant is carboxymethyl cellulose (CMC), the negative electrode binder is styrene-butadiene and its modified organic emulsion (SBR), the negative electrode active material is graphite, and the total thickness of the negative electrode material coating layer is 120 μm," but not knowing the number of coating layers, the thickness of each coating layer, or the type of graphite in the coating layer, used the core characteristic identification method for new energy battery cell electrodes based on coating technology in this embodiment to identify the above information.

[0271] The core characteristic identification method for new energy battery cell electrodes based on coating technology in this embodiment includes the following steps:

[0272] Step 1: Clean the surface of the negative electrode A2-1 sample with an ultrapure water vapor cleaner for 15 min and dry it at 75℃ for 6 h. Then, perform micro-layer peeling treatment every 20 μm from the side away from the current collector to the side closer to the current collector until only the current collector is retained. A total of 6 micro-layer peeling treatments were performed. After each micro-layer peeling treatment, the product obtained was placed in a 180-mesh standard sieve and shaken for 45 min for sieving. Six negative electrode material powders with an average particle size of 8-12 μm were collected.

[0273] The micro-layer peeling process is as follows: the two ends of the sample on the left side of the negative electrode A2-1 are fixed on the fixture of the micro-layer peeling device (electrode binber floating tester, Chuanyuan Technology Co., Ltd.), the single-layer peeling thickness is set to 20μm through the software of the micro-layer peeling device, the software is set to peel 6 times, and the powder sample is collected in the sample box at the bottom of the device.

[0274] Step 2: Place the 6 portions of negative electrode material powder obtained in Step 1 into a vacuum drying oven and dry them at 65°C for 5 hours. Then, distill and reflux each dried powder at 280°C and 0.2Pa vacuum for 4 hours to remove CMC and SBR. Collect the volatile organic compounds discharged during the distillation process to obtain 6 portions of negative electrode active material.

[0275] Step 3: Perform Raman spectroscopy and transmission electron microscopy tests on the 6 negative electrode active materials obtained in Step 2 respectively, and determine the type of graphite material based on the results of Raman spectroscopy and transmission electron microscopy tests.

[0276] The method of determining the type of graphite material based on the results of Raman spectroscopy and transmission electron microscopy includes: analyzing their surface defects through Raman spectroscopy to determine the type of graphite corresponding to each negative electrode active material; and analyzing their coating characteristics (i.e., whether the graphite is coated or uncoated) through transmission electron microscopy.

[0277] The conditions for Raman spectroscopy testing were: a scanning range of 200–3200 cm⁻¹. -1 The laser power was 150mW; the conditions for transmission electron microscopy testing were: acceleration voltage of 6kV and current density of 40mA.

[0278] The Raman spectroscopy and transmission electron microscopy results of the six negative electrode active materials obtained in step 2, and the information on the graphite type obtained based on their test results are shown in Table 5.

[0279] Table 5

[0280]

[0281] Note: In Table 5, "x#" represents the xth negative electrode active material obtained after the xth micro-layer exfoliation and distillation reflux treatment, and is labeled as negative electrode active material x#. Taking "1#" as an example, it represents the first negative electrode active material obtained after the first micro-layer exfoliation and distillation reflux treatment, and is labeled as negative electrode active material 1#.

[0282] Step 4: Based on the judgment results in Table 5 of Step 3, further determine whether the graphite type and coating characteristics of the negative electrode active material are completely the same after two adjacent micro-layer peeling treatments in Step 1, and whether the graphite type and coating characteristics of the negative electrode active material are different after at least one of the two adjacent micro-layer peeling treatments in Step 1, and whether they belong to different negative electrode material layers.

[0283] Specifically:

[0284] Since only the graphite type of negative electrode active material 1# in Table 5 is 2C and does not contain a coating layer, negative electrode active material 1# is a negative electrode material coating layer.

[0285] Since the graphite type of negative electrode active materials 2# to 6# in Table 5 is all 6C and all contain a coating layer, negative electrode active materials 2#, 3#, 4#, 5# and 6# belong to the same negative electrode material coating layer.

[0286] Step 5: The number of times that the type of graphite of the negative electrode active material and the coating characteristics determined in Step 4 are inconsistent after two consecutive micro-layer peeling treatments is taken as the number of negative electrode material coating layers. The thickness of the negative electrode material coating layer is taken as the sum of the thicknesses of all micro-layer peeling treatments that are determined to belong to the same negative electrode material coating layer after all consecutive micro-layer peeling treatments.

[0287] Specifically:

[0288] Based on step 4, it is determined that the negative electrode sample of this embodiment has two negative electrode material coating layers, wherein:

[0289] Because the micro-layer exfoliation process is performed earlier for negative electrode active material 1#, the thickness of the negative electrode material coating layer on the side away from the current collector is the same as the thickness of the first micro-layer exfoliation process for negative electrode active material 1#, which is 20μm.

[0290] Because the microlayer peeling treatment of negative electrode active materials 2#, 3#, 4#, 5#, and 6# is performed later, the thickness of the negative electrode material coating layer corresponding to the side closest to the current collector is the sum of the thicknesses of the second, third, fourth, fifth, and sixth microlayer peeling treatments for negative electrode active materials 2#, 3#, 4#, 5#, and 6#, respectively, which is 100 μm.

[0291] Application Example 2

[0292] Based on the core characteristic identification method of new energy cell electrode sheets based on coating technology in Example 3, the identification results are used in the design of lithium-ion battery negative electrode sheets, as follows:

[0293] Adopting such Figure 2 The negative electrode sheet shown has a thickness ratio of 1:5 for the first negative electrode material coating layer 101 and the second negative electrode material coating layer 102, and the compaction density of the first negative electrode material coating layer 101 is 1.7 g / cm³. 3 The compaction density of the second negative electrode material coating layer 102 is 1.3 g / cm³. 3 The areal density of the first negative electrode material coating layer 101 is 3 g / cm³. 3 The areal density of the second negative electrode material coating layer 102 is 6 g / cm³. 3 .

[0294] Example 4

[0295] This embodiment is basically the same as embodiment 1, except that:

[0296] Step 3 only involves Raman spectroscopy testing, without transmission electron microscopy (TEM). The type of graphite material is determined based on the Raman spectroscopy results. Table 1 does not include TEM results.

[0297] In step 4, based on the judgment results in Table 1 of step 3, it is further determined that the graphite types of the negative electrode active materials after two adjacent micro-layer peeling treatments in step 1 are exactly the same negative electrode material coating layer, while the graphite types of the negative electrode active materials after two adjacent micro-layer peeling treatments in step 1 are different negative electrode material layers. Since only negative electrode active material 1# in Table 1 has a graphite type of 4C, negative electrode active material 1# is a single negative electrode material coating layer.

[0298] Since the graphite type of negative electrode active materials 2# to 5# in Table 1 is all 2C, negative electrode active materials 2#, 3#, 4# and 5# belong to the same negative electrode material coating layer.

[0299] In step 5, the number of times the type of graphite of the negative electrode active material determined in step 4 is inconsistent after two consecutive micro-layer peeling treatments is taken as the number of negative electrode material coating layers, and the sum of the thicknesses of all micro-layer peeling treatments that are determined to belong to the same negative electrode material coating layer after all consecutive micro-layer peeling treatments is taken as the thickness of the negative electrode material coating layer.

[0300] Example 5

[0301] This embodiment is basically the same as embodiment 1, except that:

[0302] In step 3, Raman spectroscopy is replaced with X-ray diffraction (XRD).

[0303] The degree of graphitization of the samples was analyzed by XRD testing, thereby determining the type of graphite corresponding to each negative electrode active material.

[0304] The conditions for XRD testing were as follows: X-ray tube voltage (XG Voltage): 40kV, X-ray tube current (XG Current): 25mA, Scan mode: fixed time θ-2θ, Scan range: 25-29.5°, Step: 0.01°, Preset time: 1s, Slit condition: DS-1°, SS-1°, RS-0.3mm, Unit of intensity (Unit): CPS.

[0305] Sample preparation is required before XRD testing. The preparation method for the five negative electrode active material samples is as follows: add 40% silicon powder (by mass of the negative electrode active material) to each of the five negative electrode active material samples, mix evenly, fill the glass sample cell, level it, and gently compact it.

[0306] The XRD and transmission electron microscopy test results of the five negative electrode active materials obtained in step 2, and the information on the graphite type obtained based on their test results are shown in Table 6.

[0307] Table 6

[0308]

[0309] Note: In Table 6, "x#" represents the xth negative electrode active material obtained after the xth micro-layer exfoliation and distillation reflux treatment, and is labeled as negative electrode active material x#. Taking "1#" as an example, it represents the first negative electrode active material obtained after the first micro-layer exfoliation and distillation reflux treatment, and is labeled as negative electrode active material 1#.

[0310] Example 6

[0311] This embodiment is basically the same as embodiment 1, except that:

[0312] The method for identifying the core characteristics of new energy battery cell electrodes based on coating technology identifies the negative electrode sample A1-1 by replacing the negative electrode dispersant with CMC-Na and the negative electrode binder with PAA, and marking it as negative electrode A3-1.

[0313] In step 1, the negative electrode sample A1-1 is replaced with the negative electrode sample A3-1.

[0314] Step 2 is as follows: The five negative electrode material powders obtained in Step 1 are placed in a vacuum drying oven and dried at 80°C for 3 hours. Then, each dried powder is distilled and refluxed at 250°C and 0.2Pa vacuum for 4 hours to remove PAA and sodium carboxymethyl cellulose (CMC-Na). The volatile organic compounds discharged during the distillation process are collected to obtain five negative electrode active materials.

[0315] Comparative Example 1

[0316] The method for identifying this comparative example is as follows:

[0317] The electrode sheet was cut and prepared using an argon ion polishing instrument. The negative electrode sheet A1-1 sample from Example 1 was tested using a field emission scanning electron microscope. The results are as follows: Figure 3 As shown. From Figure 3 As can be seen, field emission scanning electron microscopy (FEM) cannot distinguish how many layers the negative electrode material coating has, nor can it identify the type of graphite material.

[0318] Comparative Example 2 (compared to Example 1, the peeling was not a microlayer peeling)

[0319] This comparative example is basically the same as Example 1, except that:

[0320] In step 1, the negative electrode material coating layer on the surface of the current collector is peeled off in one step.

[0321] Step 2 involves only 1 part of negative electrode material powder and yields 1 part of negative electrode active material;

[0322] Steps 3 to 5 only involve one negative electrode active material and its test results, making it impossible to determine the specific type of graphite material, the number of coating layers, or the thickness of each layer of the negative electrode material coating.

[0323] Comparative Example 3 (excluding distillation reflux treatment compared to Example 1)

[0324] This comparative example is basically the same as Example 1, except that:

[0325] Step 2 is excluded;

[0326] In step 3, the five negative electrode material powders obtained in step 1 were subjected to Raman spectroscopy and transmission electron microscopy tests, respectively.

[0327] The results of Raman spectroscopy and transmission electron microscopy tests of the five negative electrode material powders obtained in step 1, and the information on the graphite type obtained based on their test results are shown in Table 7.

[0328] Table 7

[0329]

[0330]

[0331] Note: In Table 7, "Tx#" represents the xth negative electrode material powder obtained after the xth micro-layer exfoliation treatment, denoted as negative electrode material powder Tx#. Taking "T1#" as an example, it represents the first negative electrode material powder obtained after the first micro-layer exfoliation treatment, denoted as negative electrode material powder T1#.

[0332] As can be seen from Table 7, the results of Raman spectroscopy and transmission electron microscopy were affected because CMC and SBR were not removed. The graphite type could not be accurately determined based on the results, and thus the subsequent steps of determining the number of coating layers and the thickness of each coating layer could not be performed.

[0333] 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.

[0334] 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.

[0335] 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 method for identifying core characteristics of electrode sheets in new energy battery cells based on coating technology, characterized in that, Includes the following steps: S101. Select a portion of the sample from the electrode to be tested and perform micro-layer peeling to obtain electrode material powder; S102. The electrode material powder is subjected to distillation and reflux treatment to remove the dispersant and / or binder, thereby obtaining the electrode active material; S103. Test the electrode active material to obtain test results; the test includes a first test or a first test and a second test, the first test includes Raman spectroscopy and / or X-ray diffraction, and the second test includes transmission electron microscopy. S104. Determine the type of the electrode active material based on the test results; The micro-layer peeling process is performed multiple times, and steps S102 to S104 are repeated after each micro-layer peeling process. Based on the type of electrode active material determined in step S104 after multiple micro-layer peeling processes, the number of electrode material coating layers and the thickness of each electrode material coating layer in the electrode sheet are obtained. The thickness of each microlayer peeling process is 1–40 μm; Obtaining the number of electrode material coating layers and the thickness of each electrode material coating layer in the electrode sheet includes: If the type of electrode active material obtained in step S104 is consistent after two consecutive micro-layer peeling processes, then they are determined to belong to the same electrode material coating layer. If the types of electrode active materials obtained in step S104 after two adjacent micro-layer peeling processes are inconsistent, it is determined that they are not the same electrode material coating layer. The number of times the type of the electrode active material determined in step S104 after two adjacent micro-layer peeling processes is inconsistent is taken as the number of electrode material coating layers. The thickness of the electrode material coating layer is the sum of the thicknesses of all micro-layer peeling processes that are determined to belong to the same electrode material coating layer after all consecutive micro-layer peeling processes in step S104.

2. The method for identifying core characteristics of new energy battery cell electrode sheets based on coating technology according to claim 1, characterized in that, The step of determining the type of electrode active material based on the test results includes: Based on the results of the first test, determine the substance type or class of the electrode active material; and / or, The coating characteristics of the electrode active material are determined based on the results of the second test.

3. The method for identifying core characteristics of new energy battery cell electrode sheets based on coating technology according to claim 1, characterized in that, The electrode to be tested includes one of the following: a fresh positive electrode, a fresh negative electrode, a positive electrode after battery cycling, and a negative electrode after battery cycling. And / or, the electrode under test has at least one electrode material coating layer; And / or, the dispersant includes an aqueous dispersant; And / or, the adhesive includes a water-based adhesive; And / or, the electrode active material includes one of graphite, silicon oxide, lithium cobalt oxide, lithium nickel oxide, lithium copper oxide, lithium titanate, ternary cathode material, LiMn2O4, and LiFePO4.

4. The method for identifying core characteristics of new energy battery cell electrode sheets based on coating technology according to claim 3, characterized in that, The electrode to be tested has two or more layers of electrode material coating.

5. The method for identifying core characteristics of new energy battery cell electrode sheets based on coating technology according to claim 3, characterized in that, The electrode to be tested is a fresh negative electrode or a negative electrode after battery cycling, which has at least two layers of electrode material coating and each layer has a different type of graphite. And / or, the aqueous dispersant includes at least one of carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, sodium carboxyethyl cellulose, and lithium carboxyethyl cellulose; And / or, the aqueous adhesive includes at least one of styrene-butadiene and its modified organic emulsion, styrene acrylate and its modified organic emulsion, polyethylene emulsion, and polyacrylic adhesive.

6. The method for identifying core characteristics of new energy battery cell electrode sheets based on coating technology according to claim 5, characterized in that, The aqueous dispersant is carboxymethyl cellulose; And / or, the aqueous binder is styrene-butadiene and its modified organic emulsion.

7. The method for identifying core characteristics of new energy battery cell electrode sheets based on coating technology according to claim 1, characterized in that, The temperature of the distillation reflux treatment is 200–300°C, and the vacuum degree of the distillation reflux treatment is 0.1–0.5 Pa; And / or, the conditions for the Raman spectroscopy test are: a scanning range of 100–3200 cm⁻¹. -1 The laser power is 5–200 mW; And / or, the conditions for the X-ray diffraction test are: a scanning angle range of 10 to 80°.

8. The method for identifying core characteristics of new energy battery cell electrode sheets based on coating technology according to any one of claims 1 to 7, characterized in that, The method for identifying the core characteristics of new energy battery cell electrodes based on coating technology also includes the steps of cleaning and drying the electrode surface before the micro-layer peeling process; And / or, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes the steps of collecting and sieving the electrode material powder before the distillation reflux treatment; the average particle size of the sieved electrode material powder is 5-15 μm; And / or, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes a step of drying the electrode material powder before the distillation reflux treatment; And / or, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes the step of collecting the volatile organic compounds discharged from the distillation reflux treatment after the distillation reflux treatment; And / or, the electrode to be tested includes a positive electrode after battery cycling or a negative electrode after battery cycling. The method for identifying the core characteristics of the electrode of a new energy cell based on coating technology further includes: if the test results cannot be used to determine the type of the electrode active material, then another part of the sample in the electrode to be tested is selected and steps S101 to S104 are repeated until step S104 can determine the type of the electrode active material based on the test results, at which point the sample of different parts of the electrode to be tested is stopped. And / or, the method for identifying the core characteristics of new energy battery cell electrodes based on coating technology further includes the step of analyzing and detecting the content of each component in the electrode to be tested.

9. The application of the core characteristic identification method for new energy cell electrode sheets based on coating technology as described in any one of claims 1 to 8 in the production of secondary batteries.

10. The application according to claim 9, characterized in that, When the electrode is a negative electrode with two layers of electrode material coating and each layer has a different type of graphite, the electrode must satisfy at least one of the following characteristics: (1) The compaction density of the electrode material coating layer on the side away from the current collector is 1.5–1.8 g / cm³. 3 ; (2) The areal density of the electrode material coating layer on the side away from the current collector is 2-3 mg / cm³. 2 ; (3) The compaction density of the electrode material coating layer near the current collector is 1.2–1.5 g / cm³. 3 ; (4) The areal density of the electrode material coating layer near the current collector is 4–6 mg / cm³. 2 ; (5) The thickness ratio of the electrode material coating layer on the side away from the current collector to the electrode material coating layer on the side closer to the current collector is 1:(3~6).

Images