Floating degree detection method and device, battery management system and electronic equipment

Abstract

The embodiment of the invention discloses a floating degree detection method and device, a storage medium and electronic equipment, and the method comprises the steps: carrying out the powder taking of a pole piece active layer of a battery negative pole piece, and obtaining at least one active powder layer, carrying out emission spectrometry detection on the active powder layer to obtain a target element content, taking the target element content as a thickening agent content for the active powder layer, carrying out thermal weight loss detection on the active powder layer to obtain a material weight loss ratio, and taking the material weight loss ratio as a comprehensive content corresponding to the binder and the thickening agent for the active powder layer; and based on the comprehensive content and the thickening agent content, obtaining the binder content for the active powder layer, and based on the binder content and the thickening agent content corresponding to each active powder layer, determining the material floating degree distribution of the negative pole piece.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a floating degree detection method, device, storage medium and electronic device. Background Art

[0002] When coating the negative electrode of the battery, there is a risk that some negative electrode materials will float up as the water evaporates during the drying process. The floating of some negative electrode materials will reduce the material adhesion of the negative electrode of the battery, and peeling will occur during the subsequent manufacturing process and the cycle of the finished battery. Therefore, in the battery process, an effective evaluation of the distribution of the negative electrode material in the battery plays an extremely important reference role in the parameter setting during the negative electrode coating process. Summary of the invention

[0003] The present application provides a method, device, storage medium and electronic device for detecting floating degree, and the technical solution is as follows:

[0004] In a first aspect, an embodiment of the present application provides a method for detecting a floating degree, the method comprising:

[0005] Performing powder extraction on the active layer of the negative electrode of the battery to obtain at least one active powder layer;

[0006] Performing emission spectroscopy on the active powder layer to obtain a target element content and using the target element content as a thickener content for the active powder layer;

[0007] And, performing a thermal weight loss test on the active powder layer to obtain a material weight loss rate and using the material weight loss rate as the comprehensive content corresponding to the binder and the thickener of the active powder layer;

[0008] Obtaining a binder content for the active powder layer based on the comprehensive content and the thickener content;

[0009] The material floating degree distribution of the negative electrode plate is determined based on the binder content and the thickener content corresponding to each active powder layer.

[0010] In the embodiments of the present application, the inventors studied the floating degree detection of the negative electrode material. In the related art, dyeing with dyes, heavy metals (such as osmium) and other dyeing materials are often used to evaluate the floating degree of the binder SBR. However, due to the limitations of the dyeing materials, it is not environmentally friendly and is affected by the uniformity of the dyeing of the dyeing materials. In order to solve the limitations of the aforementioned related technologies, the present application avoids the use of dyeing materials in the floating degree detection process. Only by performing emission spectroscopy and thermal gravimetric detection on several active powder layers after the active powder layer is taken, the binder content and thickener content corresponding to the active powder layer can be determined. Combined with the binder content and thickener content corresponding to each layer of active powder layer, the floating degree distribution of the negative electrode plate is determined. The floating degree detection is environmentally friendly and is not affected by the uniformity of the dyeing of the dyeing material, which improves the accuracy of the detection, and the detection process is simple and convenient. It can not only quantify the floating situation of the binder SBR, but also quantify the floating situation of the thickener CMC, and the floating degree detection range is wider.

[0011] In a feasible implementation manner, the powder extraction process is performed on the active layer of the negative electrode of the battery to obtain at least one active powder layer, including:

[0012] Determine a target size range from the active layer of the negative electrode of the battery, and obtain a test sample of the active layer of the electrode within the target size range;

[0013] The test sample is subjected to a powder scraping treatment to obtain at least one active powder layer.

[0014] In an embodiment of the present application, the target size range is first determined, and a test sample of the active layer of the electrode is taken within the target size range. Then, the test sample is scraped for powder. The standardized powder taking process can assist in the floating degree detection and reduce the detection error.

[0015] In a feasible implementation manner, determining a target size range from the active layer of the negative electrode of the battery, and obtaining a test sample of the active layer of the electrode within the target size range includes:

[0016] Obtaining a negative electrode plate to be tested of a battery, and determining a target size range of an active layer of the negative electrode plate to be tested;

[0017] Within the target size range, a sampling tool is used to cut a test sample of a target sample size from the pole piece active layer.

[0018] In an embodiment of the present application, a target size range is first determined, and a test sample of the electrode active layer of the target sample size is taken within the target size range. Then, powder is scraped from the test sample. Based on a standardized powder collection process, a test sample of the target sample size that meets the specifications can be obtained, thereby assisting subsequent floating degree detection and reducing or even avoiding detection errors introduced in the sampling stage.

[0019] In a feasible implementation manner, the powdering treatment of the test sample to obtain at least one active powder layer comprises:

[0020] Acquiring the number of active powder layers for the test sample, and determining the thickness of the active powder layer based on the number of active powder layers;

[0021] Based on the active powder layer quantity and the active powder layer thickness, the test sample is subjected to a powder scraping process to obtain at least one active powder layer indicated by the active powder layer quantity.

[0022] In the embodiment of the present application, the thickness of the active powder layer is determined based on the number of active powder layers to accurately indicate the powder scraping process. The powder thickness requirement is determined by standardizing the thickness of the active powder layer to avoid test errors caused by the sampling process.

[0023] In a feasible implementation manner, determining the thickness of the active powder layer based on the number of active powder layers includes:

[0024] Obtain the total thickness of both sides of the negative electrode sheet, the thickness of the foil and the thickness of the primer coating on both sides corresponding to the test sample;

[0025] The thickness of the active powder layer is determined by using a target calculation formula based on the amount of the active powder layer, the total thickness of the negative electrode sheet on both sides, the thickness of the foil and the thickness of the double-sided primer;

[0026] The target calculation formula satisfies the following formula:

[0027]

[0028] Among them, h is the thickness of the active powder layer, n is the number of the active powder layers, H is the total thickness of both sides of the negative electrode sheet, v is the thickness of the foil, and y is the thickness of the double-sided primer.

[0029] In an embodiment of the present application, a method is involved for accurately calculating the thickness of the active powder layer based on the number of active powder layers, the total thickness of the negative electrode sheet on both sides, the foil thickness and the double-sided primer thickness, which further improves the accuracy of sampling and standardizes the sampling process.

[0030] In a feasible implementation manner, the step of performing emission spectroscopy on the active powder layer to obtain the target element content includes:

[0031] Determining a target detection element for the active powder layer, wherein the target detection element is lithium or sodium;

[0032] The target detection element in the active powder layer is detected by emission spectroscopy to obtain the target element content.

[0033] In the embodiments of the present application, the content of the thickener CMC in the active powder layer can be determined by detecting the content of the target element by emission spectroscopy, which can avoid only evaluating the floating degree of the binder SBR and ignoring the risk that the thickener CMC will also float as the water evaporates during the drying process.

[0034] In a feasible implementation manner, obtaining the binder content for the active powder layer based on the comprehensive content and the thickener content includes:

[0035] Calculate the binder content for the active powder layer using a first relationship based on the comprehensive content corresponding to the active powder layer and the thickener content;

[0036] The first relationship satisfies the following formula:

[0037] X=2A-B

[0038] Wherein, X is the binder content of the active powder layer, A is the comprehensive content, and B is the thickener content.

[0039] In the embodiment of the present application, the first relationship can be used to accurately calculate the binder content of the active powder layer, and the distribution of the binder in the negative electrode sheet material can be effectively obtained, providing an effective auxiliary means for solving the floating problem of the negative electrode material during the coating process.

[0040] In a feasible implementation manner, determining the material floating degree distribution of the negative electrode sheet based on the binder content and the thickener content corresponding to each active powder layer includes:

[0041] Determining a binder floating degree distribution diagram for the negative electrode sheet based on the binder content corresponding to each active powder layer; and / or,

[0042] A thickener floating degree distribution diagram for the negative electrode plate is determined based on the thickener content corresponding to each active powder layer.

[0043] In an embodiment of the present application, the binder content / thickener content of each active powder layer can be obtained by drawing a binder floating degree distribution diagram / thickener floating degree distribution diagram. Based on the floating degree distribution diagram, the distribution of the binder / thickener in the negative electrode sheet material can be effectively obtained, providing an effective auxiliary means for solving the floating problem of the negative electrode material during the coating process.

[0044] In a feasible implementation manner, before the powder removal process is performed on the active layer of the negative electrode of the battery, the process further includes:

[0045] Fully discharging the battery so that the battery voltage of the battery is less than or equal to the target voltage;

[0046] Disassembling the battery to obtain the negative electrode sheet of the battery, and soaking the negative electrode sheet in a dimethyl carbonate solution;

[0047] The negative electrode plate is dried.

[0048] In the embodiment of the present application, since the electrolyte evaporates after the battery cell is disassembled, the lithium salt in the electrolyte will adhere to the surface of the negative electrode plate. The above method can be used to avoid the lithium salt from affecting the subsequent analysis and detection of the negative electrode plate.

[0049] In a feasible implementation manner, after the powder extraction process is performed on the active layer of the negative electrode of the battery to obtain at least one layer of active powder, the process further includes:

[0050] The active powder layer is placed in water for soaking treatment to remove the interface side reaction layer and residual lithium ions of the active powder layer.

[0051] In an embodiment of the present application, the active powder layer is immersed for a certain period of time (such as 30 minutes) to remove the surface side reaction layer (also known as the external interface side reaction layer), and the residual lithium ions in the lattice can be freed to avoid the influence of residual lithium ions in the electrolyte and the lattice during subsequent emission spectroscopy detection.

[0052] In a second aspect, an embodiment of the present application provides a floating degree detection device, the device comprising:

[0053] A processing module, used for extracting powder from the active layer of the negative electrode of the battery to obtain at least one active powder layer;

[0054] A detection module, used for performing emission spectroscopy detection on the active powder layer to obtain a target element content and using the target element content as a thickener content for the active powder layer;

[0055] The detection module is further used to perform a thermal weight loss test on the active powder layer to obtain a material weight loss rate and use the material weight loss rate as the comprehensive content corresponding to the binder and thickener of the active powder layer;

[0056] The detection module is further used to obtain the binder content for the active powder layer based on the comprehensive content and the thickener content;

[0057] The distribution determination module is used to determine the material floating degree distribution of the negative electrode plate based on the binder content and the thickener content corresponding to each layer of the active powder layer.

[0058] In a third aspect, an electronic device is provided, characterized in that it comprises: a processor and a memory; wherein the memory stores a computer program, and the computer program is suitable for being loaded by the processor and executing the above-mentioned method steps.

[0059] A fourth aspect is a computer storage medium, wherein the computer storage medium stores a plurality of instructions, wherein the instructions are suitable for being loaded by a processor and executing the above-mentioned method steps.

[0060] In a fifth aspect, an embodiment of the present application provides a computer program product, which stores at least one instruction, and the at least one instruction is loaded by the processor to execute the above-mentioned method steps.

[0061] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or understood by implementing the embodiments of the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0063] Figure 1 It is a flow chart of a floating degree detection method provided in an embodiment of the present application;

[0064] Figure 2 This is a schematic diagram of a powder extraction process provided in an embodiment of the present application;

[0065] Figure 3 It is a schematic diagram of a floating degree distribution diagram combination provided in an embodiment of the present application;

[0066] Figure 4 It is a schematic diagram of a powder extraction process provided in an embodiment of the present application;

[0067] Figure 5 is a schematic diagram of a test sample cut out according to an embodiment of the present application;

[0068] Figure 6 It is a schematic diagram of a scenario for testing the regional thickness of different negative electrode plate regions provided in an embodiment of the present application;

[0069] Figure 7It is a schematic flow chart of a pretreatment step of a specified battery cell provided in an embodiment of the present application;

[0070] Figure 8 It is a schematic diagram of the structure of a floating degree detection device provided in an embodiment of the present application;

[0071] Fig. 9 It is a structural schematic diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0072] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0073] In the description of the present application, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood in specific circumstances. In addition, in the description of the present application, unless otherwise specified, "multiple" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are an "or" relationship.

[0074] In the related art, there are certain limitations in the detection of floating degree. On the one hand, the floating degree detection usually only evaluates the floating degree of the binder SBR, while ignoring the risk that the thickener CMC will also float as the water evaporates during the drying process; on the other hand, the evaluation of the floating degree of the binder SBR is dyed with dyes, heavy metals (such as osmium) and other dyeing materials, which is not environmentally friendly and the test results are affected by the uniformity of heavy metals or dyeing materials.

[0075] The present application is described in detail below with reference to specific embodiments.

[0076] In one embodiment, Figure 1 As shown, a method for detecting the floating degree is proposed, which can be implemented by a computer program and can be run on a floating degree detection device based on the von Neumann system. The computer program can be integrated into an application or run as an independent tool application. Specifically, the floating degree detection method includes:

[0077] S102: extracting powder from the active layer of the negative electrode of the battery to obtain at least one layer of active powder;

[0078] Specifically, the negative electrode plate of the battery is usually composed of a negative electrode current collector and a (negative electrode) plate active layer located on the surface of the negative electrode current collector;

[0079] It can be understood that the active layer of the negative electrode of the battery after negative electrode coating and drying is subjected to powder extraction treatment, and the number of layers of the active powder layer obtained can be one or more layers;

[0080] Schematically, one or more active powder layers are extracted relative to the powder layer thickness of the negative electrode plate of the battery. It can be understood that the active powder layer thickness of each active powder layer is determined according to the powder layer thickness of the negative electrode plate of the battery, and then the powder extraction operation is performed layer by layer on the negative electrode plate of the battery according to the active powder layer thickness of each active powder layer, so as to obtain the active powder layer corresponding to the active powder layer thickness.

[0081] Assume that the active layer of the negative electrode of the battery is divided into n layers of active powder to be taken, and the thickness of the i-th active powder layer can be expressed as H i Characterization (i is a natural number), the total thickness of the n layers of active powder is less than or equal to the thickness of the active layer of the negative electrode of the battery;

[0082] In a specific implementation, usually for the electrode active layer of the negative electrode of the battery, powder is first taken from the first active powder layer, and the scraped powder thickness of the electrode active layer of the negative electrode of the battery is detected at the same time (the difference between the thickness of the original electrode active layer when the first active powder layer is taken and the thickness of the current electrode active layer), and when the scraped powder thickness reaches the thickness H1 of the first active powder layer, the first active powder layer obtained by the powder taking process is independently stored;

[0083] ···

[0084] Then, start taking powder from the i-th active powder layer, and at the same time detect the scraped powder thickness of the active layer of the negative electrode of the battery (the difference between the thickness of the original active layer of the electrode when taking powder from the i-th active powder layer and the thickness of the current active layer of the electrode), and wait until the scraped powder thickness reaches the thickness H of the i-th active powder layer. i , independently storing the i-th active powder layer obtained by the powder extraction process;

[0085] ···

[0086] Then, powder is taken from the nth active powder layer, and the scraped powder thickness of the active layer of the negative electrode of the battery is detected at the same time (the difference between the thickness of the original active layer of the electrode when the nth active powder layer is taken and the thickness of the current active layer of the electrode), and when the scraped powder thickness reaches the thickness Hn of the nth active powder layer, the nth active powder layer obtained by the powder taking process is saved independently;

[0087] The powder extraction process is completed to obtain n layers of active powder.

[0088] In a possible implementation, a negative electrode sheet of a battery to be tested is taken, the negative electrode sheet of the battery is the negative electrode sheet of the battery (before cold pressing), a sampling tool (such as a blade or other tool) is used to cut a sample of a certain specification from the negative electrode sheet of the battery as a test sample, and a powder collecting tool (such as a blade, a coating scraper or other tool) is used to collect powder from the test sample to obtain one or more active powder layers;

[0089] It should be noted that the number of active powder layers when taking powder is determined based on actual working conditions and is not limited here.

[0090] Optionally, when taking out the powder, each active powder layer is stored separately after the powder is taken out. For example, the powder of each active powder layer is put into a sealed bag after the powder is taken out of each active powder layer to avoid powder contamination caused by residue or mixing of different active powder layers.

[0091] Optionally, each time powder is taken during the powder taking process, a high-precision testing tool (such as a micrometer) is used to test the regional thickness of different negative electrode plate areas during the powder scraping process. The regional thickness fluctuation value needs to meet a certain fluctuation range to ensure that the powder taking process is as smooth as possible, avoid inconsistent powder taking depths in different areas, and avoid the introduction of test errors into the subsequent detection process during the powder taking and sample preparation process;

[0092] For example, based on actual working conditions, it can be determined that there are three layers of active powder layers when taking powder, namely the first active powder layer (which can be called the upper layer - active powder layer), the second active powder layer (which can be called the middle layer - active powder layer) and the third active powder layer (which can be called the lower layer - active powder layer). Figure 2 As shown, Figure 2 This is a schematic diagram of a powder extraction process involved in this specification. Take the negative electrode plate of the battery to be tested, the negative electrode plate of the battery is the negative electrode plate of the battery (before cold pressing), and use a powder extraction tool (such as Figure 2 The coating scraper held by the robot in the middle is used to take powder from the test sample of the negative electrode of the battery to obtain Figure 2 The three active powder layers shown are respectively the first active powder layer (which can be called the upper layer - active powder layer), the second active powder layer (which can be called the middle layer - active powder layer) and the third active powder layer (which can be called the lower layer - active powder layer).

[0093] Optionally, the active powder layer can be placed in water for immersion treatment to remove the interface side reaction layer and residual lithium ions of the active powder layer; the active powder layer can be immersed for a certain period of time (such as 30 minutes) to remove the surface side reaction layer (also called the external interface side reaction layer), and the residual lithium ions in the lattice can be freed to avoid the influence of the electrolyte and the residual lithium ions in the lattice during subsequent emission spectroscopy detection.

[0094] Indicatively, the soaking treatment may be followed by a drying treatment.

[0095] S104: performing emission spectroscopy detection on the active powder layer to obtain a target element content and using the target element content as a thickener content for the active powder layer;

[0096] The emission spectrometry test is also called ICP test, and the element content of the active powder layer is detected by ICP test;

[0097] Optionally, the target element content may be a Li element content or a Na element content;

[0098] It can be understood that the purpose of performing emission spectroscopy on the active powder layer is to determine the content of thickener CMC in the active powder layer.

[0099] S106: Performing a thermal weight loss test on the active powder layer to obtain a material weight loss rate and using the material weight loss rate as the comprehensive content of the binder and the thickener corresponding to the active powder layer;

[0100] The thermal gravimetric test is also called the TG test. The TG test can characterize the degree to which the binder and the thickener float as the water evaporates during the drying process. The thermal gravimetric test is performed on each active powder layer to obtain the material weight loss rate of each active powder layer. The material weight loss rate can be used as the comprehensive content of the binder SBR and the thickener CMC corresponding to the active powder layer.

[0101] Exemplarily, the test temperature range of the TG test can be 50°C to 800°C, and the test atmosphere is N2 atmosphere;

[0102] Optionally, the type of binder includes, but is not limited to, one or more of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, polyurethane, fluorinated rubber, polyvinyl alcohol or sodium polyacrylate.

[0103] Optionally, the type of thickener includes but is not limited to one or more thickener materials such as polyacrylic acid (PAA), lithium polyacrylate (PAALi), sodium polyacrylate (PAANa), polymethyl acrylate, polymethyl methacrylate, polyisooctyl acrylate, polyvinyl acrylate, carboxymethyl cellulose, sodium carboxymethyl cellulose, etc.

[0104] S108: Obtaining a binder content for the active powder layer based on the comprehensive content and the thickener content;

[0105] Assume that the active layer of the negative electrode of the battery is divided into n layers of active powder to be taken, and the material weight loss rate of the i-th active powder layer is calculated as the comprehensive content of the binder SBR and the thickener CMC, recorded as A i , then A1+...+A i + ... An = 200%;

[0106] The thickener content of the i-th active powder layer is recorded as B i , then B1+...+B i +...Bn=100%;

[0107] Furthermore, the binder content for the active powder layer may be calculated using a first relational expression based on the comprehensive content corresponding to the active powder layer and the thickener content;

[0108] The first relationship satisfies the following formula:

[0109] X=2A-B

[0110] Wherein, X is the binder content of the active powder layer, A is the comprehensive content, and B is the thickener content.

[0111] Schematically, for any i-th active powder layer, the binder content X i =2A i -Bi;

[0112] Exemplarily, it is assumed that the active layer of the negative electrode of the battery is divided into three layers of active powder layers to be taken, which are respectively called the first active powder layer (which can be called the upper layer-active powder layer), the second active powder layer (which can be called the middle layer-active powder layer) and the third active powder layer (which can be called the lower layer-active powder layer);

[0113] The content of thickener CMC in the three layers of active powder is: the upper layer is recorded as B1, the middle layer is recorded as B2, and the lower layer is recorded as B3. The content of binder SBR is set as X1 in the upper layer, X2 in the middle layer, and X3 in the lower layer. Then, X1, X2, and X3 can be calculated respectively through the first relationship.

[0114] S110: Determine the material floating degree distribution of the negative electrode plate based on the binder content and the thickener content corresponding to each active powder layer.

[0115] Schematically, based on the above steps, the binder content and the thickener content corresponding to each active powder layer can be obtained, and the binder content corresponding to all active powder layers and the thickener content corresponding to all active powder layers can characterize the distribution of the binder floating degree and the thickener floating degree of the negative electrode sheet;

[0116] In schematic form, the material floating degree distribution of the negative electrode sheet can be characterized by drawing a material floating degree distribution diagram, drawing a material floating degree table, and other mathematical and statistical forms.

[0117] Optionally, a binder floating degree distribution diagram for the negative electrode sheet is determined based on the binder content corresponding to each active powder layer, that is, a binder SBR floating degree distribution diagram for the negative electrode sheet is drawn based on the binder content corresponding to all active powder layers;

[0118] Optionally, a thickener floating degree distribution diagram for the negative electrode plate is determined based on the thickener content corresponding to each active powder layer, that is, a thickener CMC floating degree distribution diagram for the negative electrode plate is drawn based on the thickener content corresponding to all active powder layers;

[0119] It can be understood that during the battery management process, by executing the floating degree detection method of one or more embodiments of this specification, an effective evaluation can be performed based on the floating degree distribution of the negative electrode material, which plays an extremely important reference role in parameter setting and negative electrode coating effect during the negative electrode coating process.

[0120] For example, the distribution of the floating degree of the negative electrode material can be used to assist in evaluating the demoulding of the negative electrode during coating.

[0121] Example 1: Figure 3 As shown, Figure 3 is a schematic diagram of a floating degree distribution diagram combination involved in this specification, Figure 3 The middle left picture is the floating degree distribution diagram of the binder SBR, and the right picture is the floating degree distribution diagram of the thickener CMC;

[0122] With respect to the film release on the B side of the pole piece, by collecting normal samples and abnormal samples for comparison, and executing the floating degree detection method of one or more embodiments of this specification, the floating degree distribution diagram of the binder SBR and the thickener CMC of the normal sample and the abnormal sample can be obtained, such as Figure 3 As shown, from Figure 3It can be seen that the CMC distribution of thickeners is basically the same, but the floating degree of abnormal samples is reduced, indicating that the demolding is not caused by the floating of the binder SBR. For further verification, combined with the subsequent SEM observation, it can be observed that the binder SBR of the abnormal sample is in the form of single particles, which does not play the role of binder SBR-SBR connection, which may correspond to the demulsification of the binder SBR.

[0123] Through the above examples, it can be seen that by executing the floating degree detection method of one or more embodiments of this specification, an effective evaluation can be performed based on the floating degree distribution of the material of the negative electrode sheet.

[0124] In the embodiment of the present application, the present application avoids using dyeing materials in the process of floating degree detection. Only by performing emission spectroscopy detection and thermal gravimetric detection on several active powder layers after the active powder layer is taken, the binder content and thickener content corresponding to the active powder layer can be determined. The binder content and thickener content corresponding to each layer of active powder layer are combined to determine the floating degree distribution of the negative electrode material. The floating degree detection is environmentally friendly and is not affected by the uniformity of dyeing of dyeing materials, which improves the accuracy of detection, and the detection process is simple and convenient. It can not only quantify the floating condition of the binder SBR, but also quantify the floating condition of the thickener CMC, and the floating degree detection range is wider.

[0125] See also Figure 4 , Figure 4 This is a schematic diagram of a powder extraction process proposed in this application. Specifically:

[0126] S202: determining a target size range from the active layer of the negative electrode of the battery, and obtaining a test sample of the active layer of the electrode within the target size range;

[0127] In a possible implementation, a battery negative electrode plate to be tested is taken, a target size range is determined from the specifications of the plate active layer of the battery negative electrode plate, and then a test sample of the plate active layer is obtained within the target size range.

[0128] Exemplarily, the test sample selection steps are as follows:

[0129] A2: Obtain a negative electrode plate to be tested of a battery, and determine a target size range of an active layer of the negative electrode plate to be tested;

[0130] The negative electrode sheet to be tested may be a negative electrode sheet before the cold pressing step in the battery production stage;

[0131] The target size range for sampling is preset, usually by determining a target size range on the active layer of the negative electrode to be tested. The target size range is used to indicate the range within which the test sample is to be cut when selecting the test sample.

[0132] A4: Within the target size range, use a sampling tool to cut a test sample of the target sample size from the active layer of the pole piece.

[0133] Within the target size range, a sampling tool (such as a blade or other tool) is used to cut a sample of the target sample size from the negative electrode of the battery as a test sample; for example, if the target size range is 5cm*5cm, a test sample of a target sample size less than or equal to "5cm*5cm" can be cut from a sampling tool (such as a blade or other tool). For example, the target sample size can be "3cm*4cm", Figure 5 As shown, Figure 5 is a schematic diagram of a test sample involved in this specification. Figure 5 It is a test sample taken from the negative electrode of the battery (such as the negative electrode of the battery before cold pressing) using a sampling tool - a blade. The test sample must be taken to ensure that the appearance of the negative electrode of the battery to be tested is good, and defective products are not allowed to ensure that the sampling is representative.

[0134] S204: performing a powder scraping treatment on the test sample to obtain at least one active powder layer.

[0135] Use a powder collecting tool (such as a blade, a coating scraper, etc.) to collect powder from the test sample to obtain one or more active powder layers;

[0136] For example, a reference to the steps of scraping powder is as follows:

[0137] B2: Obtaining the number of active powder layers for the test sample, and determining the thickness of the active powder layer based on the number of active powder layers;

[0138] Schematically, before the powder scraping process is performed, the thickness of the active powder layer is first set based on the number of active powder layers to be taken;

[0139] Optionally, the thickness of each active powder layer to be taken can be customized;

[0140] Optionally, the same thickness of active powder layer may be set for each active powder layer to be taken;

[0141] In a possible implementation manner, firstly obtain the total thickness of both sides of the negative electrode sheet, the thickness of the foil and the thickness of the primer coating on both sides corresponding to the test sample;

[0142] It is schematic, and the total thickness on both sides of the negative electrode sheet, the foil thickness and the double-sided primer thickness can be set in advance during the battery sheet production stage.

[0143] Then, the thickness of the active powder layer is determined by using a target calculation formula based on the amount of the active powder layer, the total thickness of the negative electrode sheet on both sides, the thickness of the foil material and the thickness of the double-sided primer;

[0144] The target calculation formula satisfies the following formula:

[0145]

[0146] Among them, h is the thickness of the active powder layer, n is the number of the active powder layers, H is the total thickness of both sides of the negative electrode sheet, v is the thickness of the foil, and y is the thickness of the double-sided primer.

[0147] Exemplarily, based on actual working conditions, it can be determined that the number of active powder layers when taking powder is three, that is, the first active powder layer (which can be called the upper layer-active powder layer), the second active powder layer (which can be called the middle layer-active powder layer) and the third active powder layer (which can be called the lower layer-active powder layer), and each layer of active powder layer needs to be divided into samples for TG test and samples for ICP test, such as 0.1g of sample for TG test and 0.5g of sample for ICP test;

[0148] Further, the total thickness of the negative electrode sheet on both sides is 100um, the foil thickness is 8um, and the double-sided primer thickness is 2um corresponding to the test sample;

[0149] Then the target calculation formula is used to calculate the thickness of the active powder layer as 15 μm;

[0150] Based on this, the distribution of the thickness of the upper layer of powder to be scraped can be expressed as: active layer surface ~ 15μm below the active layer surface

[0151] Thickness of the middle layer to be scraped: 15μm below the surface of the active layer - 30um below the surface of the active layer

[0152] The thickness of the lower layer of powder to be scraped is: 30um below the surface of the active layer - 45um below the surface of the active layer.

[0153] B4: Based on the amount of active powder layers and the thickness of the active powder layers, the test sample is subjected to a powder scraping process to obtain at least one active powder layer indicated by the amount of active powder layers.

[0154] In a specific embodiment, the thickness of each active powder layer can be represented by H. With the number of active powder layers n and the thickness of the active powder layers H as reference, the powder scraping process is as follows:

[0155] Usually, for the active layer of the negative electrode of the battery, powder is first taken from the first active powder layer, and the scraped powder thickness of the active layer of the negative electrode of the battery is detected at the same time (the difference between the thickness of the original active layer of the electrode when the first active powder layer is taken and the thickness of the current active layer of the electrode), and when the scraped powder thickness reaches the thickness H1 of the first active powder layer, the first active powder layer obtained by the powder taking process is independently stored;

[0156] ···

[0157] Then, start taking powder from the i-th active powder layer, and at the same time detect the scraped powder thickness of the active layer of the negative electrode of the battery (the difference between the thickness of the original active layer of the electrode when taking powder from the i-th active powder layer and the thickness of the current active layer of the electrode), and wait until the scraped powder thickness reaches the thickness H of the i-th active powder layer. i , the i-th active powder layer obtained by the powder extraction process is stored independently;

[0158] ···

[0159] Then, powder is taken from the nth active powder layer, and the scraped powder thickness of the active layer of the negative electrode of the battery is detected at the same time (the difference between the thickness of the original active layer of the electrode when the nth active powder layer is taken and the thickness of the current active layer of the electrode), and when the scraped powder thickness reaches the thickness Hn of the nth active powder layer, the nth active powder layer obtained by the powder taking process is saved independently;

[0160] The powder extraction process is completed to obtain n layers of active powder.

[0161] It should be noted that the number of active powder layers when taking powder is determined based on actual working conditions and is not limited here.

[0162] Optionally, when taking out the powder, each active powder layer is stored separately after the powder is taken out. For example, the powder of each active powder layer is put into a sealed bag after the powder is taken out of each active powder layer to avoid powder contamination caused by residue or mixing of different active powder layers.

[0163] Optional, such as Figure 6 As shown, Figure 6 This is a schematic diagram of a scenario for testing the regional thickness of different negative electrode areas. Each time the powder is taken out during the powder taking process, a high-precision testing tool (such as Figure 6 The regional thickness of different negative electrode sheet areas in the powder scraping process is tested by using a micrometer (as shown). The regional thickness fluctuation value must meet a certain fluctuation range to ensure that the powder taking process is as smooth as possible, avoid inconsistent powder taking depths in different areas, and avoid introducing test errors into the subsequent testing process during the powder taking and sampling process;

[0164] In one or more embodiments of the present application, the above-mentioned powder collection method realizes a standardized powder collection process, which can obtain test samples that meet the target sample size specifications, thereby assisting in subsequent floating degree detection, reducing or even avoiding detection errors introduced in the sampling stage; and determining the thickness of the active powder layer based on the number of active powder layers to accurately indicate the powder scraping process, and to obtain the powder thickness requirements by standardizing the thickness of the active powder layer.

[0165] In one or more embodiments of the present application, the floating degree detection method may further include a preprocessing step;

[0166] See also Figure 7 , Figure 7 It is a flow chart of the pre-processing steps of a specified battery cell. Specifically:

[0167] S302: Fully discharge the battery so that the battery voltage of the battery is less than or equal to the target voltage;

[0168] For example, the battery cell can be fully discharged to below the target voltage, such as the target voltage can be set to 3v;

[0169] S304: disassembling the battery to obtain a negative electrode sheet of the battery, and soaking the negative electrode sheet in a dimethyl carbonate solution;

[0170] Schematically, the battery structure is then disassembled to obtain the negative electrode sheet of the battery, and then the negative electrode sheet is immersed in a dimethyl carbonate solution (DMC solution);

[0171] Optionally, the disassembled graphite negative electrode can be cleaned with dimethyl carbonate solution for a specified number of times (e.g., 3 times), and each time the cleaning is performed for a specified time, such as 10 minutes.

[0172] S306: Drying the negative electrode plate.

[0173] Further, the negative electrode plate is dried, such as placing the negative electrode plate in an oven to obtain a negative electrode plate product after drying, and then the active layer of the negative electrode plate of the battery is powdered to obtain at least one layer of active powder;

[0174] In one or more embodiments of the present specification, since the electrolyte evaporates after the battery cell is disassembled, the lithium salt in the electrolyte will adhere to the surface of the negative electrode plate. The above method can be used to avoid the lithium salt from affecting the subsequent analysis and detection of the negative electrode plate.

[0175] The following will be combined Figure 8 , the floating degree detection device provided in the embodiment of the present application is introduced in detail. It should be noted that, Figure 8 The floating degree detection device shown is used to implement the present application Figure 1 to Figure 7 For the convenience of explanation, only the part related to the embodiment of the present application is shown. For the specific technical details not disclosed, please refer to the present application. Figure 1 to Figure 7 The embodiment shown.

[0176] See also Figure 8, which shows a schematic diagram of the structure of the floating degree detection device of an embodiment of the present application. The floating degree detection device 1 can be implemented as all or part of an electronic device through software, hardware or a combination of both. According to some embodiments, the floating degree detection device 1 includes a processing module 11, a detection module 12 and a distribution determination module 13, which are specifically used to:

[0177] The processing module 11 is used to extract powder from the active layer of the negative electrode of the battery to obtain at least one active powder layer;

[0178] A detection module 12, for performing emission spectroscopy detection on the active powder layer to obtain a target element content and using the target element content as a thickener content for the active powder layer;

[0179] The detection module 12 is further used to perform a thermal weight loss test on the active powder layer to obtain a material weight loss rate and use the material weight loss rate as the comprehensive content corresponding to the binder and thickener of the active powder layer;

[0180] The detection module 12 is further used to obtain the binder content for the active powder layer based on the comprehensive content and the thickener content;

[0181] The distribution determination module 13 is used to determine the material floating degree distribution of the negative electrode sheet based on the binder content and the thickener content corresponding to each layer of the active powder layer.

[0182] Optionally, the processing module 11 is used to:

[0183] Determine a target size range from the active layer of the negative electrode of the battery, and obtain a test sample of the active layer of the electrode within the target size range;

[0184] The test sample is subjected to a powder scraping treatment to obtain at least one active powder layer.

[0185] Optionally, the processing module 11 is used to:

[0186] Obtaining a negative electrode plate to be tested of a battery, and determining a target size range of an active layer of the negative electrode plate to be tested;

[0187] Within the target size range, a sampling tool is used to cut a test sample of a target sample size from the pole piece active layer.

[0188] Optionally, the processing module 11 is used to:

[0189] Acquiring the number of active powder layers for the test sample, and determining the thickness of the active powder layer based on the number of active powder layers;

[0190] Based on the active powder layer quantity and the active powder layer thickness, the test sample is subjected to a powder scraping process to obtain at least one active powder layer indicated by the active powder layer quantity.

[0191] Optionally, the processing module 11 is used to:

[0192] Obtain the total thickness of both sides of the negative electrode sheet, the thickness of the foil and the thickness of the primer coating on both sides corresponding to the test sample;

[0193] The thickness of the active powder layer is determined by using a target calculation formula based on the amount of the active powder layer, the total thickness of the negative electrode sheet on both sides, the thickness of the foil and the thickness of the double-sided primer;

[0194] The target calculation formula satisfies the following formula:

[0195]

[0196] Among them, h is the thickness of the active powder layer, n is the number of the active powder layers, H is the total thickness of both sides of the negative electrode sheet, v is the thickness of the foil, and y is the thickness of the double-sided primer.

[0197] Optionally, the detection module 12 is used to:

[0198] Determining a target detection element for the active powder layer, wherein the target detection element is lithium or sodium;

[0199] The target detection element in the active powder layer is detected by emission spectroscopy to obtain the target element content.

[0200] Optionally, the detection module 12 is used to:

[0201] Calculate the binder content for the active powder layer using a first relationship based on the comprehensive content corresponding to the active powder layer and the thickener content;

[0202] The first relationship satisfies the following formula:

[0203] X=2A-B

[0204] Wherein, X is the binder content of the active powder layer, A is the comprehensive content, and B is the thickener content.

[0205] Optionally, the distribution determination module 13 is used to:

[0206] Determining a binder floating degree distribution diagram for the negative electrode sheet based on the binder content corresponding to each active powder layer; and / or,

[0207] A thickener floating degree distribution diagram for the negative electrode plate is determined based on the thickener content corresponding to each active powder layer.

[0208] Optionally, the device 1 is further used for:

[0209] Fully discharging the battery so that the battery voltage of the battery is less than or equal to the target voltage;

[0210] Disassembling the battery to obtain the negative electrode sheet of the battery, and soaking the negative electrode sheet in a dimethyl carbonate solution;

[0211] The negative electrode plate is dried.

[0212] Optionally, the device 1 is further used for:

[0213] The active powder layer is placed in water for soaking treatment to remove the interface side reaction layer and residual lithium ions of the active powder layer.

[0214] It should be noted that the floating degree detection device provided in the above embodiment only uses the division of the above functional modules as an example when executing the floating degree detection method. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the floating degree detection device provided in the above embodiment and the floating degree detection method embodiment belong to the same concept, and the implementation process thereof is detailed in the method embodiment, which will not be repeated here.

[0215] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0216] The present application also provides a computer storage medium, which can store multiple instructions, and the instructions are suitable for being loaded and executed by a processor as described above. Figure 1 to Figure 7 The floating degree detection method of the embodiment shown in the figure can be specifically implemented by referring to Figure 1 to Figure 7 The specific description of the illustrated embodiment will not be repeated here.

[0217] The present application also provides a computer program product, which stores at least one instruction, and the at least one instruction is loaded and executed by the processor as described above. Figure 1 to Figure 7 The floating degree detection method of the embodiment shown in the figure can be specifically implemented by referring to Figure 1 to Figure 7 The specific description of the illustrated embodiment will not be repeated here.

[0218] Please refer to Fig. 9, is a structural block diagram of an electronic device provided in an embodiment of this specification. The electronic device in this specification may include one or more of the following components: a processor 110, a memory 120, an input device 130, an output device 140, and a bus 150. The processor 110, the memory 120, the input device 130, and the output device 140 may be connected via a bus 150.

[0219] The processor 110 may include one or more processing cores. The processor 110 uses various interfaces and lines to connect various parts of the entire terminal, and executes various functions and processes data of the terminal 100 by running or executing instructions, programs, code sets or instruction sets stored in the memory 120, and calling data stored in the memory 120. Optionally, the processor 110 can be implemented in at least one hardware form of digital signal processing (DSP), field-programmable gate array (FPGA), and programmable logic array (PLA). The processor 110 can integrate one or a combination of a central processing unit (CPU), a graphics processing unit (GPU), and a modem. Among them, the CPU mainly processes the operating system, user interface, and application programs; the GPU is responsible for rendering and drawing display content; and the modem is used to process wireless communications. It can be understood that the above-mentioned modem may not be integrated into the processor 110, but may be implemented separately through a communication chip.

[0220] The memory 120 may include a random access memory (RAM) or a read-only memory (ROM). Optionally, the memory 120 includes a non-transitory computer-readable storage medium. The memory 120 may be used to store instructions, programs, codes, code sets, or instruction sets.

[0221] The input device 130 is used to receive input commands or data, and the input device 130 includes but is not limited to a keyboard, a mouse, a camera, a microphone, or a touch device. The output device 140 is used to output commands or data, and the output device 140 includes but is not limited to a display device and a speaker. In the embodiment of this specification, the input device 130 may be a temperature sensor for obtaining the operating temperature of the terminal. The output device 140 may be a speaker for outputting audio signals.

[0222] In addition, those skilled in the art will appreciate that the structure of the terminal shown in the above drawings does not constitute a limitation on the terminal, and the terminal may include more or fewer components than shown, or combine certain components, or arrange the components differently. For example, the terminal also includes a radio frequency circuit, an input unit, a sensor, an audio circuit, a wireless fidelity (WIFI) module, a power supply, a Bluetooth module, and other components, which will not be described in detail here.

[0223] In the embodiments of this specification, the execution subject of each step may be the electronic device described above. Optionally, the execution subject of each step is the operating system of the terminal. The operating system may be an Android system, an IOS system, or other operating systems, which is not limited in the embodiments of this specification.

[0224] exist Fig. 9 In the electronic device, the processor 110 can be used to call the program stored in the memory 120 and execute it to implement the floating degree detection method as described in the various method embodiments of this specification.

[0225] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0226] The above disclosure is only the preferred embodiment of the present application, which certainly cannot be used to limit the scope of rights of the present application. Therefore, equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A method for detecting floating degree, characterized in that: The method comprises: Performing powder extraction on the active layer of the negative electrode of the battery to obtain at least one active powder layer; Performing emission spectroscopy on the active powder layer to obtain a target element content and using the target element content as a thickener content for the active powder layer; And, performing a thermal weight loss test on the active powder layer to obtain a material weight loss rate and using the material weight loss rate as the comprehensive content corresponding to the binder and the thickener of the active powder layer; Obtaining a binder content for the active powder layer based on the comprehensive content and the thickener content; The material floating degree distribution of the negative electrode plate is determined based on the binder content and the thickener content corresponding to each active powder layer.

2. The method according to claim 1, characterized in that The method of extracting powder from the active layer of the negative electrode of the battery to obtain at least one active powder layer includes: Determine a target size range from the active layer of the negative electrode of the battery, and obtain a test sample of the active layer of the electrode within the target size range; The test sample is subjected to a powder scraping treatment to obtain at least one active powder layer.

3. The method according to claim 2, characterized in that The step of determining a target size range from the active layer of the negative electrode of the battery, and obtaining a test sample of the active layer of the electrode within the target size range includes: Obtaining a negative electrode plate to be tested of a battery, and determining a target size range of an active layer of the negative electrode plate to be tested; Within the target size range, a sampling tool is used to cut a test sample of a target sample size from the pole piece active layer.

4. The method according to claim 2, characterized in that The step of performing a powder scraping treatment on the test sample to obtain at least one active powder layer comprises: Acquiring the number of active powder layers for the test sample, and determining the thickness of the active powder layer based on the number of active powder layers; Based on the active powder layer quantity and the active powder layer thickness, the test sample is subjected to a powder scraping process to obtain at least one active powder layer indicated by the active powder layer quantity.

5. The method according to claim 4, characterized in that The determining the thickness of the active powder layer based on the amount of the active powder layer comprises: Obtain the total thickness of both sides of the negative electrode sheet, the thickness of the foil and the thickness of the primer on both sides corresponding to the test sample; The thickness of the active powder layer is determined by using a target calculation formula based on the amount of the active powder layer, the total thickness of the negative electrode sheet on both sides, the thickness of the foil and the thickness of the double-sided primer; The target calculation formula satisfies the following formula: Among them, h is the thickness of the active powder layer, n is the number of the active powder layers, H is the total thickness of both sides of the negative electrode sheet, v is the thickness of the foil, and y is the thickness of the double-sided primer.

6. The method according to claim 1, characterized in that The step of performing emission spectroscopy on the active powder layer to obtain the target element content includes: Determining a target detection element for the active powder layer, wherein the target detection element is lithium or sodium; The target detection element in the active powder layer is detected by emission spectroscopy to obtain the target element content.

7. The method according to claim 1, characterized in that The method of obtaining the binder content for the active powder layer based on the comprehensive content and the thickener content includes: Calculate the binder content for the active powder layer using a first relationship based on the comprehensive content corresponding to the active powder layer and the thickener content; The first relationship satisfies the following formula: X=2A-B Wherein, X is the binder content of the active powder layer, A is the comprehensive content, and B is the thickener content.

8. The method according to claim 1, characterized in that The determining of the material floating degree distribution of the negative electrode sheet based on the binder content and the thickener content corresponding to each active powder layer includes: Determining a binder floating degree distribution diagram for the negative electrode sheet based on the binder content corresponding to each active powder layer; and / or, A thickener floating degree distribution diagram for the negative electrode plate is determined based on the thickener content corresponding to each active powder layer.

9. The method according to claim 1, characterized in that: Before the powder extraction process is performed on the active layer of the negative electrode of the battery, the method further comprises: Fully discharging the battery so that the battery voltage of the battery is less than or equal to the target voltage; Disassembling the battery to obtain the negative electrode sheet of the battery, and soaking the negative electrode sheet in a dimethyl carbonate solution; The negative electrode plate is dried.

10. The method according to claim 1, characterized in that After the active layer of the battery negative electrode plate is subjected to powder extraction processing to obtain at least one layer of active powder layer, the method further comprises: The active powder layer is placed in water for soaking treatment to remove the interface side reaction layer and residual lithium ions of the active powder layer.

11. A floating degree detection device, characterized in that: The device comprises: A processing module, used for extracting powder from the active layer of the negative electrode of the battery to obtain at least one active powder layer; A detection module, used for performing emission spectroscopy detection on the active powder layer to obtain a target element content and using the target element content as a thickener content for the active powder layer; The detection module is further used to perform a thermal weight loss test on the active powder layer to obtain a material weight loss rate and use the material weight loss rate as the comprehensive content corresponding to the binder and thickener of the active powder layer; The detection module is further used to obtain the binder content for the active powder layer based on the comprehensive content and the thickener content; The distribution determination module is used to determine the material floating degree distribution of the negative electrode plate based on the binder content and the thickener content corresponding to each layer of the active powder layer.

12. A computer storage medium, characterized in that: The computer storage medium stores a plurality of instructions, and the instructions are suitable for being loaded by a processor and executing the method steps according to any one of claims 1 to 10.

13. An electronic device, characterized in that: include: A processor and a memory; wherein the memory stores a computer program, and the computer program is suitable for being loaded by the processor and executing the method steps as claimed in any one of claims 1 to 10.

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