Porosity measurement method and system
Patent Information
- Application Number
- PCT/CN2026/072081
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-02-18
- Filing Date
- 2026-01-12
- Publication Date
- 2026-08-27
Smart Images
Figure CN2026072081_27082026_PF_FP_ABST
Abstract
Description
Porosity detection methods and systems
[0001] Cross-references to related applications
[0002] This application claims priority to Chinese Patent Application No. 202510178290.7, filed on February 18, 2025, entitled “Method and System for Detecting Porosity”, the entire contents of which are incorporated herein by reference. Technical Field
[0003] This application relates to the field of analytical testing technology, specifically to a method and system for detecting porosity. Background Technology
[0004] Porous materials include porous organic materials, porous inorganic materials, and porous composite materials. They have advantages such as low specific gravity, large specific surface area, good energy absorption, and good permeability, and have been widely used in aerospace, electrochemistry, petrochemical, and construction industries.
[0005] Porosity is a key indicator of porous materials. It reflects the density of the material and is an important parameter affecting the ion or fluid transport performance within porous materials. It may also affect the mechanical properties, thermal conductivity, and electrical conductivity of porous materials.
[0006] Therefore, the detection of porosity in porous materials is particularly important, but the current detection accuracy needs to be further improved. Summary of the Invention
[0007] This application is made in view of the above-mentioned problems, and its purpose is to provide a method and system for detecting porosity that can improve the detection accuracy of porosity.
[0008] In a first aspect, embodiments of this application propose a method for detecting porosity, the method comprising:
[0009] Provide electrode assemblies;
[0010] A sealing material is provided to an electrode assembly, and the assembly is coated to form a coating layer of the sealing material on the outer surface of the electrode assembly, thereby obtaining a coated assembly.
[0011] The first volume of the gas adsorption detection coating component is the sum of the solid volume of the coating component and the closed-pore volume of the coating component;
[0012] Based on the first volume, the solid volume of the coating layer, and the solid volume of the electrode assembly, the pore volume of the electrode assembly is obtained, and the porosity of the electrode assembly is calculated.
[0013] Therefore, according to the detection method provided in the embodiments of this application, by providing a coating layer on the outer surface of the electrode assembly, both the open-pore structure and the closed-pore structure of the electrode assembly are used as the closed-pore structure of the coating assembly. The first volume of the coating assembly is obtained by gas adsorption detection, and the pore volume of the electrode assembly is calculated therefrom, making the detection of pore volume more accurate and improving the detection accuracy of porosity.
[0014] In some embodiments, after the step of providing the electrode assembly, the method further includes:
[0015] The second volume of the gas adsorption detection electrode assembly is the sum of the solid volume of the electrode assembly and the closed-pore volume of the electrode assembly.
[0016] Based on the second volume and the pore volume of the electrode assembly, the open pore volume of the electrode assembly is obtained, and the open pore porosity of the electrode assembly is calculated.
[0017] According to the detection method of the present application, the porosity and open porosity of the electrode assembly can be detected by secondary gas adsorption detection, and the detection accuracy is high.
[0018] In some embodiments, after obtaining the open pore volume of the electrode assembly based on the second volume and the pore volume of the electrode assembly, and calculating the open pore porosity of the electrode assembly, the method further includes:
[0019] Based on the porosity of the electrode assembly and the open-pore porosity of the electrode assembly, the closed-pore porosity of the electrode assembly is calculated.
[0020] The embodiments of this application utilize secondary gas adsorption to obtain the porosity, open-pore porosity, and closed-pore porosity of the electrode assembly, thereby improving the measurement accuracy.
[0021] In some embodiments, the step of providing a sealing material to an electrode assembly and then coating it to form a coating layer covering the outer surface of the electrode assembly to obtain a coated assembly includes:
[0022] In a vacuum environment, a sealing material is provided to the electrode assembly, and after a coating process, the sealing material forms a coating layer that covers the outer surface of the electrode assembly, resulting in a coated assembly.
[0023] A vacuum environment can reduce the risk of air bubbles being trapped between the coating layer and the electrode assembly during the coating process, reduce the risk of introducing pores during testing, and further improve the accuracy of porosity detection.
[0024] In some implementations, the vacuum environment has a pressure of -101 kPa to -50 kPa. This vacuum level reduces the risk of air bubbles being trapped between the coating layer and the electrode assembly during the coating process, reduces the risk of introducing pores during testing, and further improves the accuracy of porosity detection.
[0025] In some embodiments, the viscosity of the sealing material in the molten state is between 5,000 Cps and 100,000 Cps. The relatively high viscosity of the sealing material prevents it from penetrating the porous structure of the electrode assembly, thus improving the accuracy of porosity detection.
[0026] In some embodiments, the viscosity of the sealing material at the second temperature is greater than that at the first temperature, the second temperature is greater than or equal to the melting point of the sealing material, and the second temperature is less than the first temperature. The sealing material can be a temperature-sensitive material that melts at relatively high temperatures and has good fluidity; as the temperature decreases, the viscosity increases and the fluidity decreases; as the temperature further decreases, the sealing material condenses to form a solid; by controlling the coating conditions, the sealing material is prevented from penetrating into the pore structure of the electrode assembly during the sealing process, thereby improving the accuracy of porosity detection.
[0027] In some embodiments, the viscosity of the sealing material at the first temperature is 5000 Cps to 30000 Cps; the sealing material has better fluidity at higher temperatures, which is beneficial for the subsequent uniform coating of the electrode assembly.
[0028] In some embodiments, the viscosity of the sealing material at the second temperature is between 30,000 Cps and 100,000 Cps. The higher viscosity of the sealing component at the second temperature means it will not penetrate the porous structure of the electrode assembly, thus improving the accuracy of porosity detection.
[0029] In some embodiments, the sealing material includes one or more of paraffin wax, methyl palmitate, acrylate, epoxy resin, and phenolic resin.
[0030] In some embodiments, the step of providing a sealing material to an electrode assembly and then coating it to form a coating layer covering the outer surface of the electrode assembly to obtain a coated assembly includes:
[0031] A sealing assembly at a second temperature is provided to an electrode assembly, and the assembly is cooled to form a coating layer of sealing material on the outer surface of the electrode assembly to obtain an intermediate assembly, wherein the viscosity of the sealing material at the second temperature is 30,000 Cps to 100,000 Cps;
[0032] When the outer surface of the intermediate component is the outer surface of the sealing material, the intermediate component is used as the covering component.
[0033] Therefore, the viscosity of the sealing component at the second temperature is relatively high, and it will not penetrate into the pore structure of the electrode component, thus improving the accuracy of porosity detection.
[0034] In some embodiments, when the outer surface of the intermediate component includes the outer surface of the electrode component, the steps of providing a sealing component at a second temperature to the electrode component and cooling it to form a covering layer of sealing material covering the outer surface of the electrode component are repeated at least once until the outer surface of the intermediate component is the outer surface of the sealing material.
[0035] Repeated coating steps ensure that the outer surface of the electrode assembly is completely covered by the sealing component, thereby improving the accuracy of porosity detection.
[0036] In some embodiments, the cooling process involves cooling to a third temperature at a first cooling rate, the third temperature being less than the melting point of the sealing material, and the first cooling rate being 3°C / min to 10°C / min.
[0037] When the first cooling rate is within the above range, the sealing material is less likely to form internal defects and voids during the cooling process.
[0038] In some embodiments, prior to the step of providing a sealing assembly at a second temperature to an electrode assembly, and then cooling it to form a coating layer of sealing material on the outer surface of the electrode assembly to obtain an intermediate assembly, the method further includes:
[0039] The sealing material is heat-treated at a first temperature to melt it.
[0040] The sealing material is cooled to a second temperature at a second cooling rate.
[0041] Pre-melting the sealing material at the first temperature allows for a more uniform distribution of the sealing material, which is beneficial for the uniform coating of the outer surface of the electrode assembly.
[0042] In some embodiments, the second cooling rate is from 0.5°C / min to 5°C / min. When the second cooling rate is within the above range, the sealing material cools uniformly during the cooling process, resulting in consistent performance throughout.
[0043] In some embodiments, the first temperature is between 90°C and 130°C. The sealing material has good fluidity at the first temperature, which is beneficial for the subsequent uniform coating of the electrode assembly.
[0044] In some embodiments, the second temperature is between 50°C and 90°C. The sealing component at this second temperature has a higher viscosity, preventing it from penetrating the porous structure of the electrode assembly and thus improving the accuracy of porosity detection.
[0045] In some embodiments, the gas detected by gas adsorption includes one or more of helium and nitrogen. The molecules of these gases are small enough to enter the micropores, which helps improve the accuracy of the measurement.
[0046] Secondly, this application proposes a porosity detection system, which includes a providing device, a packaging device, a first gas adsorption detection device, and a first calculation device. The providing device is used to provide an electrode assembly; the packaging device is used to provide a sealing material to the electrode assembly, and after a coating process, the sealing material forms a coating layer covering the outer surface of the electrode assembly to obtain a coated assembly; the first gas adsorption detection device is used to detect the first volume of the coated assembly by gas adsorption, the first volume being the sum of the solid volume of the coated assembly and the closed-pore volume of the coated assembly; the first calculation device is used to obtain the pore volume of the electrode assembly based on the first volume, the solid volume of the coating layer, and the solid volume of the electrode assembly, and to calculate the porosity of the electrode assembly.
[0047] The detection system provided according to the embodiments of this application can accurately detect the porosity of electrode assemblies. Attached Figure Description
[0048] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.
[0049] Figure 1 is a schematic diagram of the porosity detection process provided in some embodiments of this application;
[0050] Figure 2 is a schematic diagram of the structure of a solid-state battery provided in some embodiments of this application;
[0051] Figure 3 is a schematic diagram of the structure of an electrode assembly provided in some embodiments of this application;
[0052] Figure 4 is a schematic diagram of the structure of an electrode assembly provided in some other embodiments of this application;
[0053] Figure 5 is a flowchart illustrating step S200 of the porosity detection process provided in some embodiments of this application.
[0054] Figure 6 is a schematic diagram of the porosity detection process provided in some other embodiments of this application;
[0055] Figure 7 is a schematic diagram of the porosity detection process provided in some other embodiments of this application;
[0056] Figure 8 is a schematic diagram of the detection system provided in some embodiments of this application;
[0057] Figure 9 is a schematic diagram of the detection system provided in some other embodiments of this application;
[0058] Figure 10 is a schematic diagram of the detection system provided in some other embodiments of this application;
[0059] The accompanying drawings may not be drawn to scale.
[0060] The reference numerals in the attached drawings are explained as follows: 100, detection system; 10, providing device; 20, packaging device; 30, first gas adsorption detection device; 40, first computing device; 50, second gas adsorption detection device; 60, second computing device; 70, third computing device; 200, solid-state battery; 21, electrode assembly; 22, outer casing; 211, positive electrode; 212, negative electrode; 213, solid electrolyte layer. Detailed Implementation
[0061] The following detailed description discloses embodiments of the electrode assembly, solid-state battery, fabrication method, battery device, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.
[0062] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
[0063] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.
[0064] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.
[0065] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.
[0066] In this application, the term "implementation" means that a specific feature, structure, or characteristic described in connection with an implementation may be included in at least one implementation of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same implementation, nor is it a separate or alternative implementation mutually exclusive with other implementations.
[0067] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0068] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0069] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.
[0070] Solid-state batteries have advantages such as high energy density, excellent cycle characteristics, and high safety characteristics, which has led to their widespread application.
[0071] Solid-state batteries include electrode components, which include a positive electrode, a negative electrode, and a solid electrolyte, with the solid electrolyte located between the positive and negative electrode.
[0072] After densification, the electrode assembly has a porous structure. It is usually necessary to test the porosity of the electrode assembly in order to conduct simulation analysis on the data of the electrode assembly.
[0073] In related technologies, the porosity of electrode components is often detected by helium adsorption, which usually results in inaccurate detection. This is because the pore structure of the electrode components includes open pores and closed pores. Helium gas usually cannot enter the closed pores, so the detected porosity is the open pore porosity, rather than the overall porosity of the electrode components.
[0074] An open hole can be understood as a hole in an electrode assembly that connects to the external environment, while a closed hole can be understood as a closed hole that does not connect to the external environment of the electrode assembly.
[0075] In view of the above problems, this application proposes a porosity detection method that can improve the accuracy of detection. The detection method proposed in this application can be used for porosity detection of electrode assemblies, as well as for porosity detection of other porous structures, such as porous organic materials and porous inorganic materials.
[0076] As shown in Figure 1, the detection method specifically includes:
[0077] Step S100: Provide electrode assembly;
[0078] Step S200: A sealing material is provided to the electrode assembly, and a coating treatment is performed to form a coating layer covering the outer surface of the electrode assembly, thereby obtaining a coated assembly;
[0079] Step S300: Gas adsorption detection of the first volume of the coating component, the first volume being the sum of the solid volume of the coating component and the closed-pore volume of the coating component;
[0080] Step S400: Based on the first volume, the solid volume of the coating layer and the solid volume of the electrode assembly, obtain the pore volume of the electrode assembly and calculate the porosity of the electrode assembly.
[0081] According to the detection method provided in the embodiments of this application, by providing a coating layer on the outer surface of the electrode assembly, both the open-pore structure and the closed-pore structure of the electrode assembly are used as the closed-pore structure of the coating assembly. The first volume of the coating assembly is obtained by gas adsorption detection, and the pore volume of the electrode assembly is calculated thereby, which makes the detection of pore volume more accurate and improves the detection accuracy of porosity.
[0082] In step S100, an electrode assembly is provided.
[0083] Electrode assemblies, as components of a battery cell, are typically located within the battery cell's casing.
[0084] As shown in Figures 2 to 4, in some embodiments, the solid-state battery 200 includes an electrode assembly 21 and a housing 22, with the electrode assembly 21 housed within the housing 22.
[0085] The outer shell 22 can be of various shapes, such as a cylinder or a cuboid. The shape of the outer shell 22 can be determined according to the specific shape of the electrode assembly 21. For example, if the electrode assembly 21 is a cylindrical structure, the outer shell 22 can be a cylindrical structure. If the electrode assembly 21 is a cuboid structure, the outer shell 22 can be a cuboid structure.
[0086] The outer casing 22 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and this application embodiment does not impose any special limitations on this. Optionally, the inner wall of the outer casing 22 may also include an insulating layer, which can separate the outer casing 22 from the electrode assembly 21. The material of the insulating layer can be selected from materials commonly used in the art, and is not particularly limited here.
[0087] The electrode assembly 21 housed within the housing 22 may be one or more.
[0088] The electrode assembly 21 includes a positive electrode 211, a negative electrode 212 and a solid electrolyte, with the solid electrolyte located between the positive electrode 211 and the negative electrode 212.
[0089] The positive electrode 211 includes a positive current collector and a positive active material layer disposed on at least one side of the positive current collector, the positive active material layer including a positive active material.
[0090] As an example, the positive electrode active material may include one or more of the following materials: phosphate, layered transition metal oxide and their respective modified compounds; in the embodiments of this application, the modified compounds of the above-mentioned positive electrode active materials may be doping modification and / or surface coating modification of the positive electrode active material, such as carbon coating modification, fast ion conductor coating modification, etc.
[0091] In some embodiments, the negative electrode 212 includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material. Optionally, the negative electrode active material layer may also include a negative electrode binder.
[0092] In other embodiments, the negative electrode 212 includes a negative current collector and a metal foil disposed on at least one side of the negative current collector, the metal foil being a lithium foil. Optionally, the negative electrode 212 further includes a negative electrode undercoating, which may include at least one of a negative electrode conductive agent and a negative electrode binder.
[0093] As an example, the negative electrode active material may include one or more of the following materials: carbon materials (e.g., carbon materials include one or more of artificial graphite, natural graphite, soft carbon, and hard carbon), silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin oxide compounds, and tin alloys.
[0094] As an example, the negative electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon fibers.
[0095] As an example, the negative electrode binder may include one or more of the following: styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).
[0096] The solid electrolyte can be disposed between the positive electrode 211 and the negative electrode 212 in the form of a film layer. For example, the solid electrolyte can be a solid electrolyte layer 213, with the positive electrode 211, the solid electrolyte layer 213, and the negative electrode 212 stacked together. The solid electrolyte layer 213 can be coated on the surface of the positive active material layer in the positive electrode 211, or on the surface of the negative active material layer in the negative electrode 212. In some embodiments, the solid electrolyte includes one or more of sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, and polymer solid electrolytes.
[0097] The electrode assembly comprises a framework structure and a porous structure. The framework structure can be understood as the solid part of the electrode assembly. The porous structure includes open pores and closed pores, with closed pores existing within the framework structure.
[0098] The solid volume of an electrode assembly refers to the actual volume of matter within the material. This volume is occupied by the solid components of the material and does not include pores; it can be understood as the total volume of the skeletal structure of the electrode assembly.
[0099] The positive electrode active material layer and the negative electrode active material layer may contain porous structures. The positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer may contain interlayer gaps, which may also constitute part of the porous structure.
[0100] The opening volume of the electrode assembly is the total volume of all openings in the electrode assembly.
[0101] The porosity of an electrode assembly is the percentage of the open-pore volume of the electrode assembly relative to its total volume.
[0102] The closed-cell volume of the electrode assembly is the total volume of all closed-cells in the electrode assembly.
[0103] The closed-pore porosity of an electrode assembly is the percentage of the closed-pore volume of the electrode assembly relative to its total volume.
[0104] The pore volume of the electrode assembly is the sum of the total volume of all open pores and the total volume of all closed pores in the electrode assembly.
[0105] The porosity of an electrode assembly is the percentage of the total volume of the pore structure relative to the total volume of the electrode assembly, which is the sum of the open-pore volume and the closed-pore volume relative to the total volume of the electrode assembly.
[0106] The second volume of the electrode assembly refers to the sum of the solid volume and the closed-hole volume of the electrode assembly. In other words, the second volume is the remaining volume of the electrode assembly excluding the open-hole volume.
[0107] The total volume of the electrode assembly includes the sum of the solid volume of the electrode assembly and the pore volume of the electrode assembly.
[0108] In the embodiments of this application, multiple electrode components can be used for parallel experiments. The materials and structures of each electrode component are basically the same, and the experimental error is reduced by parallel experiments.
[0109] In step S200, the coating component is prepared.
[0110] The sealing material forms a coating layer on the outer surface of the electrode assembly, which essentially isolates the electrode assembly from the external environment.
[0111] In some implementations, step S200 is performed in a vacuum environment, specifically by covering the outer surface of the electrode assembly with a sealing material in a vacuum environment. A vacuum environment reduces the risk of air bubbles being trapped between the coating layer and the electrode assembly during the coating process, minimizing the risk of introducing porosity during testing and further improving the accuracy of porosity detection.
[0112] Optionally, the vacuum environment pressure in step S200 is between -101 kPa and -50 kPa, such as -101 kPa, -90 kPa, -80 kPa, -70 kPa, -60 kPa, -50 kPa, or any combination of two values. This vacuum level reduces the risk of air bubbles being trapped between the coating layer and the electrode assembly during the coating process, reduces the risk of introducing pores during testing, and further improves the accuracy of porosity detection.
[0113] In some embodiments, the viscosity of the sealing material at the second temperature is greater than that at the first temperature, the second temperature is less than the first temperature, and the second temperature is greater than or equal to the melting point of the sealing material.
[0114] The aforementioned sealing material can be a temperature-sensitive material, melting and exhibiting good fluidity at relatively high temperatures; as the temperature decreases, its viscosity increases and its fluidity decreases; and as the temperature further decreases, the sealing material condenses to form a solid. By controlling the coating conditions, the sealing material is prevented from penetrating into the pore structure of the electrode assembly during the sealing process, thereby improving the accuracy of porosity detection.
[0115] Optionally, the viscosity of the sealing material in the molten state is between 5000 Cps and 100000 Cps. The relatively high viscosity of the sealing material prevents it from penetrating the pore structure of the electrode assembly, thus improving the accuracy of porosity detection.
[0116] Optionally, the viscosity of the sealing material at the first temperature is between 5000 Cps and 30000 Cps, such as 5000 Cps, 10000 Cps, 15000 Cps, 20000 Cps, 25000 Cps, 30000 Cps, or any combination of two values. The sealing material melts at a relatively high temperature, exhibiting good fluidity, which is beneficial for the subsequent uniform coating of the electrode assembly.
[0117] Optionally, the viscosity of the sealing material at the second temperature is between 30,000 Cps and 100,000 Cps, such as 30,000 Cps, 40,000 Cps, 50,000 Cps, 60,000 Cps, 70,000 Cps, 80,000 Cps, 90,000 Cps, and 100,000 Cps. The relatively high viscosity of the sealing material at relatively low temperatures means it will not penetrate the pore structure of the electrode assembly, thus improving the accuracy of porosity detection.
[0118] For example, the sealing material may include one or more of paraffin wax, methyl palmitate, acrylate, epoxy resin and phenolic resin.
[0119] In some implementations, step S200 includes:
[0120] A sealing assembly at a second temperature is provided to an electrode assembly, and then cooled to form a sealing material covering the outer surface of the electrode assembly, thereby obtaining an intermediate assembly;
[0121] When the outer surface of the intermediate component is the outer surface of the sealing material, the intermediate component is used as the covering component.
[0122] The sealing component at the second temperature has a higher viscosity and will not penetrate into the pore structure of the electrode component, thus improving the accuracy of porosity detection.
[0123] When the outer surface of the intermediate component is the outer surface of the sealing material, the intermediate component is considered as the covering component. The fact that the outer surface of the intermediate component is the outer surface of the sealing material can be understood as the sealing component essentially completely covering the electrode component; in other words, the outer surface of the electrode component is essentially completely covered by the sealing component. In this case, the intermediate component is the final covering component.
[0124] When the outer surface of the intermediate component includes the outer surface of the electrode component, the steps of providing a sealing component at a second temperature to the electrode component and cooling it to form a sealing material coating layer covering the outer surface of the electrode component are repeated at least once until the outer surface of the intermediate component is the outer surface of the sealing material. The outer surface of the intermediate component including the outer surface of the electrode component can be understood as a portion of the outer surface of the electrode component not being covered by the sealing component. In this case, the coating step is repeated until the entire outer surface of the electrode component is covered by the sealing component.
[0125] Optionally, the execution may be repeated at least twice, or optionally two to five times.
[0126] Alternatively, the covering process can be a method of treating the sealing component as a covering layer, such as a cooling process.
[0127] For example, in a vacuum environment, a sealing assembly at a second temperature is provided to an electrode assembly, and the assembly is cooled to form a coating layer of sealing material on the outer surface of the electrode assembly, thereby obtaining a coated assembly.
[0128] As shown in Figure 5, in some embodiments, step S200 may include:
[0129] Step S210: Heat-treat the sealing material at a first temperature to melt the sealing material.
[0130] Melting the sealing component at a relatively high initial temperature ensures that the sealing component is in a completely molten fluid state, which is beneficial for the subsequent coating of the sealing component onto the surface of the electrode component.
[0131] Step S220: Cool the sealing material to a second temperature at a second cooling rate;
[0132] The second temperature is greater than or equal to the melting point of the sealing material. At the second temperature, the sealing material still has fluidity, but the viscosity is relatively high, the fluidity is poor, and it is not easy to penetrate into the pore structure of the electrode assembly.
[0133] For example, the second cooling rate is from 0.5°C / min to 5°C / min, such as 0.5°C / min, 1°C / min, 1.5°C / min, 2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min, 5°C / min, or any combination of two of the above values. When the second cooling rate is within the above range, defects and voids are less likely to form inside the sealing assembly.
[0134] Step S230: Place the electrode assembly in a sealing material at a second temperature so that the sealing material covers the outer surface of the electrode assembly to form a pre-coated assembly;
[0135] Because the sealing material has a higher viscosity at the second temperature, it will not penetrate into the pore structure of the electrode assembly, which reduces the risk of introducing new pore structures during the detection process and improves the accuracy of porosity detection.
[0136] In step S240, the pre-coated component is cooled to a third temperature at a first cooling rate, so that a sealing material forms a coating layer covering the outer surface of the electrode component, resulting in an intermediate component, wherein the third temperature is lower than the melting point of the sealing material. For example, the third temperature can be room temperature.
[0137] In an environment with a melting point lower than that of the sealing component, the sealing component solidifies, and the solidified sealing component forms a coating layer covering the electrode component.
[0138] For example, the first cooling rate is from 3°C / min to 10°C / min, specifically 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min, 5°C / min, 5.5°C / min, 6°C / min, 6.5°C / min, 7°C / min, 7.5°C / min, 8°C / min, 8.5°C / min, 9°C / min, 9.5°C / min, 10°C / min, or any combination of two of the above values. When the first cooling rate is within the above range, defects and voids are less likely to form inside the sealing assembly.
[0139] Step S250: Confirm whether the sealing assembly completely covers the electrode assembly.
[0140] When the outer surface of the intermediate component is the outer surface of the sealing material, the intermediate component is considered as the covering component. The fact that the outer surface of the intermediate component is the outer surface of the sealing material can be understood as the sealing component essentially completely covering the electrode component; in other words, the outer surface of the electrode component is essentially completely covered by the sealing component. In this case, the intermediate component is the final covering component.
[0141] When the outer surface of the intermediate component includes the outer surface of the electrode assembly, steps S230 and S240 are repeated until the outer surface of the intermediate component is the outer surface of the sealing material. The fact that the outer surface of the intermediate component includes the outer surface of the electrode assembly can be understood as meaning that a portion of the outer surface of the electrode assembly is not covered by the sealing component. In this case, the covering step is repeated until the entire outer surface of the electrode assembly is covered by the sealing component.
[0142] Optionally, steps S230 and S240 are repeated at least once; further optionally, steps S230 and S240 are repeated at least twice, for example, two to five times.
[0143] The sealing component can be made of paraffin wax, an organic compound composed of long-chain alkanes with a relatively regular molecular structure. During solidification, paraffin molecules can arrange themselves into a tight crystal structure with strong intermolecular forces, allowing for close molecular packing and reducing the formation of voids. This results in fewer or even no voids in the coating layer; the void volume of the coating layer is negligible compared to the pore volume of the electrode assembly. In other words, the total volume of the coating layer is essentially equal to its solid volume, and the total volume of the coating layer can be obtained by calculating its solid volume.
[0144] Taking paraffin wax as an example, the preparation process of the coated component includes:
[0145] In some embodiments, the melting point of paraffin is 47°C to 64°C;
[0146] Step S211: Melt the paraffin wax at a first temperature. At the first temperature, the viscosity of the paraffin wax is relatively low and its fluidity is good. Optionally, the first temperature is 90°C to 130°C.
[0147] Optionally, the viscosity of paraffin at the first temperature is between 5000 Cps and 30000 Cps.
[0148] Step S221: The paraffin wax is cooled to a second temperature at a second cooling rate. The second temperature is greater than or equal to the melting point of the paraffin wax. At the second temperature, the paraffin wax still has fluidity, but its viscosity is relatively high and its fluidity is poor. Optionally, the second temperature is 50°C to 90°C.
[0149] Optionally, the viscosity of paraffin at the second temperature is between 30,000 Cps and 100,000 Cps.
[0150] Optionally, the time for the paraffin to cool from the first temperature to the second temperature is 3 to 10 minutes.
[0151] Optionally, the second cooling rate is from 0.5°C / min to 5°C / min.
[0152] The cooling rate of paraffin wax has a certain influence on its solidification structure. When the second cooling rate is within the above range, the paraffin wax molecules have enough time to rearrange themselves to form a denser crystal structure, making it less likely to form internal defects and voids.
[0153] Step S231: The electrode assembly is placed in paraffin wax at a second temperature, so that the molten paraffin wax coats the outer surface of the electrode assembly, resulting in a pre-coated assembly. Because the paraffin wax at the second temperature has a high viscosity, it does not penetrate into the pore structure of the electrode assembly, thus improving the accuracy of porosity detection.
[0154] In step S241, the pre-coated component is cooled at a first cooling rate to a temperature below the melting point of paraffin, such as a third temperature, and the molten paraffin solidifies on the outer surface of the electrode component to form a coating layer. Optionally, the third temperature can be from 20°C to 40°C.
[0155] Optionally, the time for the paraffin to cool from the second temperature to below the melting point of the paraffin is 1 to 5 minutes.
[0156] Optionally, the first cooling rate is from 3°C / min to 10°C / min.
[0157] The cooling rate of paraffin wax has a certain influence on its solidification structure. When the cooling rate is within the above range, the paraffin wax molecules have enough time to rearrange themselves to form a denser crystal structure, making it less likely to form internal defects and voids.
[0158] Repeating steps S231 to S241 at least once, optionally at least twice, and further optionally twice to five times, allows the paraffin to substantially completely cover the surface of the electrode assembly, so that the openings of the electrode assembly are not substantially exposed. This reduces the detection error of the first volume caused by the exposure of the openings of the electrode assembly due to incomplete coverage, and improves the accuracy of porosity detection.
[0159] Step S300, gas adsorption detection.
[0160] A sealing material forms a coating layer on the outer surface of the electrode assembly, essentially isolating the electrode assembly from the external environment. In this case, both the open and closed pores of the electrode assembly become closed pores in the coating assembly. In other words, the closed pore volume of the coating assembly is the sum of the open and closed pore volumes of the electrode assembly. The solid volume of the coating assembly is the sum of the solid volume of the coating layer and the solid volume of the electrode assembly.
[0161] The first volume is the sum of the solid volume of the coating component and the closed-cell volume of the coating component, which can be considered as the sum of the solid volume of the coating layer and the total volume of the electrode assembly.
[0162] The encapsulation component can be placed inside a sealed device, and the air inside the sealed device can be extracted to make the sealed device a vacuum environment; optionally, the vacuum degree of the vacuum environment before gas injection is 1 Pa to 120 Pa.
[0163] Gas is injected into a vacuum environment, and the gas can diffuse into the encapsulated components.
[0164] In some embodiments, the gas may include at least one of helium and nitrogen, with helium being the preferred choice. The aforementioned gas is an inert gas that does not react substantially with the coated component, and its small molecular size allows it to enter the micropores, which is beneficial for improving measurement accuracy.
[0165] Taking helium adsorption as an example, the helium pressure during the helium adsorption detection process is 100 kPa to 300 kPa.
[0166] In some implementations, the ambient temperature for helium adsorption detection is 25 to 55°C.
[0167] According to Boyle's Law, when the temperature remains constant, the pressure of a gas is inversely proportional to its volume. Taking helium as an example, the first volume of the coated component can be calculated by the diffusion and adsorption of the gas on the outer surface of the coated component, which is the sum of the solid volume and the closed-cell volume of the coated component.
[0168] Step S400: Calculate the porosity of the electrode assembly.
[0169] In related technologies, the dimensions of the electrode assembly, such as length, width, and height, are measured with a ruler to obtain the total volume of the electrode assembly. However, since the edges of the electrode assembly may be irregular, the measurement error is relatively large, resulting in a large error in the calculated pore volume of the electrode assembly and an increase in the porosity detection error.
[0170] The embodiment of this application obtains the total volume of the electrode assembly by detecting and calculating the first volume, and then obtains the pore volume of the electrode assembly by the difference between the total volume of the electrode assembly and the solid volume of the electrode assembly. This detection method improves the measurement accuracy of the pore volume of the electrode assembly and reduces the detection error of the porosity.
[0171] Specifically,
[0172] M represents the mass of the encapsulated component;
[0173] ρ1 is the density of the sealing material;
[0174] m represents the mass of the electrode assembly;
[0175] ρ is the theoretical density of the electrode assembly. The theoretical density is an intrinsic parameter of the material and can be calculated using lattice parameters obtained by X-ray diffraction (XRD) technology.
[0176] m / ρ represents the solid volume of the electrode assembly;
[0177] V1 represents the solid volume of the cladding layer;
[0178] V2 represents the first volume of the coated component, which is the sum of the solid volume of the coated component and the closed-cell volume of the coated component, that is, the sum of the solid volume of the coating layer and the total volume of the electrode assembly.
[0179] V2-V1 represents the total volume of the electrode assembly, which is the sum of the solid volume and the pore volume of the electrode assembly;
[0180] This indicates the percentage of the solid volume of the electrode assembly;
[0181] τ T The porosity of an electrode assembly is the percentage of the total volume of its pore structure.
[0182] As shown in Figure 6, in some embodiments, the detection method further includes steps S500 and S600.
[0183] Step S500, the second volume of the gas adsorption detection electrode assembly, the second volume is the sum of the solid volume of the electrode assembly and the closed-pore volume of the electrode assembly.
[0184] The electrode assembly can be placed inside a sealed device, and the air inside the sealed device can be extracted to make the sealed device a vacuum environment, and the air in the openings and pores of the electrode assembly can be discharged.
[0185] Gas is injected into a vacuum environment, which can diffuse into the openings and pores of the electrode assembly; optionally, the vacuum level of the vacuum environment before gas injection is 1 Pa to 120 Pa.
[0186] In some embodiments, the gas may include at least one of helium and nitrogen, with helium being the preferred choice. The aforementioned gas is an inert gas that does not react substantially with the electrode assembly, and its small molecular size allows it to enter the micropores, which is beneficial for improving measurement accuracy.
[0187] Taking helium adsorption as an example, the helium pressure during the helium adsorption detection process is 100 kPa to 300 kPa.
[0188] In some implementations, the ambient temperature for helium adsorption detection is 25 to 55°C.
[0189] According to Boyle's law, at a constant temperature, the pressure of a gas is inversely proportional to its volume. Taking helium as an example, the second volume of the electrode assembly can be calculated through the diffusion and adsorption of the gas in the electrode assembly.
[0190] Step S600: Based on the second volume and the pore volume of the electrode assembly, obtain the open pore volume of the electrode assembly, and calculate the open porosity of the electrode assembly. τ B =τ T -τ K ;
[0191] V represents the second volume, which is the sum of the solid volume of the electrode assembly and the closed-pore volume of the electrode assembly;
[0192] τ K This indicates the porosity of the electrode assembly.
[0193] According to the detection method of the present application, the porosity and open porosity of the electrode assembly can be detected by secondary gas adsorption detection, and the detection accuracy is high.
[0194] As shown in Figure 7, in some embodiments, the detection method further includes step S700, calculating the closed-pore porosity of the electrode assembly based on the porosity of the electrode assembly and the open-pore porosity of the electrode assembly. B =τ T -τ K ;
[0195] τ B This indicates the closed-pore porosity of the electrode assembly.
[0196] The embodiments of this application utilize secondary gas adsorption to obtain the porosity, open-pore porosity, and closed-pore porosity of the electrode assembly, thereby improving the measurement accuracy.
[0197] This application also proposes a detection system.
[0198] As shown in Figure 8, the detection system 100 includes a providing device 10, a packaging device 20, a first gas adsorption detection device 30, and a first calculation device 40. The providing device 10 is used to provide an electrode assembly; the packaging device 20 is used to provide sealing material to the electrode assembly, and after a coating process, the sealing material forms a coating layer covering the outer surface of the electrode assembly to obtain a coated assembly; the first gas adsorption detection device 30 is used to detect the first volume of the coated assembly by gas adsorption, the first volume being the sum of the solid volume of the coated assembly and the closed-pore volume of the coated assembly; the first calculation device 40 is used to obtain the pore volume of the electrode assembly based on the first volume, the solid volume of the coating layer, and the solid volume of the electrode assembly, and to calculate the porosity of the electrode assembly.
[0199] The detection system 100 provided according to the embodiments of this application can accurately detect the porosity of the electrode assembly.
[0200] As shown in Figure 9, in some embodiments, the detection system 100 further includes a second gas adsorption detection device 50 and a second calculation device 60. The second gas adsorption detection device 50 is used to detect the second volume of the gas adsorption detection electrode assembly, which is the sum of the solid volume of the electrode assembly and the closed pore volume of the electrode assembly. The second calculation device 60 is used to obtain the open pore volume of the electrode assembly based on the second volume and the pore volume of the electrode assembly, and calculate the open pore porosity of the electrode assembly.
[0201] The detection system 100 provided according to the embodiments of this application can also accurately detect the porosity of the electrode assembly.
[0202] As shown in Figure 10, in some embodiments, the detection system 100 further includes a third computing device 70, which is used to calculate the closed-pore porosity of the electrode assembly based on the porosity of the electrode assembly and the open-pore porosity of the electrode assembly.
[0203] The detection system 100 provided according to the embodiments of this application can also accurately detect the closed-pore porosity of the electrode assembly.
[0204] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.
Claims
1. A method for detecting porosity, comprising: Provide electrode assemblies; A sealing material is provided to the electrode assembly, and the assembly is coated to form a coating layer that covers the outer surface of the electrode assembly, thereby obtaining a coated assembly. The gas adsorption detection measures the first volume of the coating component, where the first volume is the sum of the solid volume of the coating component and the closed-cell volume of the coating component; Based on the first volume, the solid volume of the coating layer, and the solid volume of the electrode assembly, the pore volume of the electrode assembly is obtained, and the porosity of the electrode assembly is calculated.
2. The porosity detection method according to claim 1, wherein, Following the step of providing the electrode assembly, the method further includes: The second volume of the electrode assembly is determined by gas adsorption detection. The second volume is the sum of the solid volume of the electrode assembly and the closed-pore volume of the electrode assembly. Based on the second volume and the pore volume of the electrode assembly, the open pore volume of the electrode assembly is obtained, and the open pore porosity of the electrode assembly is calculated.
3. The porosity detection method according to claim 2, wherein, After the step of obtaining the open pore volume of the electrode assembly based on the second volume and the pore volume of the electrode assembly, and calculating the open pore porosity of the electrode assembly, the method further includes: Based on the porosity of the electrode assembly and the open-pore porosity of the electrode assembly, the closed-pore porosity of the electrode assembly is calculated.
4. The method for detecting porosity according to any one of claims 1 to 3, wherein, The step of providing a sealing material to the electrode assembly and then coating it to form a coating layer covering the outer surface of the electrode assembly to obtain a coated assembly includes: In a vacuum environment, a sealing material is provided to the electrode assembly, and the sealing material is coated to form a coating layer covering the outer surface of the electrode assembly, thereby obtaining a coated assembly.
5. The porosity detection method according to claim 4, wherein, The pressure of the vacuum environment is between -101 kPa and -50 kPa.
6. The method for detecting porosity according to any one of claims 1 to 5, wherein, The viscosity of the sealing material in the molten state is between 5000 Cps and 100000 Cps.
7. The method for detecting porosity according to any one of claims 1 to 6, wherein, The viscosity of the sealing material at the second temperature is greater than that at the first temperature, the second temperature is greater than or equal to the melting point of the sealing material, and the second temperature is less than the first temperature.
8. The porosity detection method according to claim 7, wherein, The viscosity of the sealing material at the second temperature is 30,000 Cps to 100,000 Cps; and / or The viscosity of the sealing material at the first temperature is between 5000 Cps and 30000 Cps.
9. The method for detecting porosity according to any one of claims 1 to 8, wherein, The sealing material includes one or more of paraffin wax, methyl palmitate, acrylate, epoxy resin, and phenolic resin.
10. The method for detecting porosity according to any one of claims 1 to 9, wherein, The step of providing a sealing material to the electrode assembly and then coating it to form a coating layer covering the outer surface of the electrode assembly to obtain a coated assembly includes: The sealing assembly is provided to the electrode assembly at a second temperature and then cooled to form a coating layer of sealing material on the outer surface of the electrode assembly to obtain an intermediate assembly, wherein the viscosity of the sealing material at the second temperature is 30,000 Cps to 100,000 Cps; When the outer surface of the intermediate component is the outer surface of the sealing material, the intermediate component is used as the covering component.
11. The porosity detection method according to claim 10, wherein, When the outer surface of the intermediate component includes the outer surface of the electrode component, the steps of providing the sealing component at a second temperature to the electrode component and cooling it to form a covering layer of the sealing material covering the outer surface of the electrode component are repeated at least once until the outer surface of the intermediate component is the outer surface of the sealing material.
12. The porosity detection method according to claim 10 or 11, wherein, The cooling process involves cooling the material to a third temperature at a first cooling rate, the third temperature being lower than the melting point of the sealing material, and the first cooling rate being 3°C / min to 10°C / min.
13. The method for detecting porosity according to any one of claims 10 to 12, wherein, Prior to the step of providing the sealing assembly at a second temperature to the electrode assembly, and then cooling it to form a coating layer of sealing material covering the outer surface of the electrode assembly to obtain the intermediate assembly, the method further includes: The sealing material is heat-treated at a first temperature to melt the sealing material. The sealing material is cooled to the second temperature at a second cooling rate.
14. The porosity detection method according to claim 13, wherein, The second cooling rate is from 0.5°C / min to 5°C / min.
15. The method for detecting porosity according to any one of claims 7 to 14, wherein, The first temperature is 90°C to 130°C; and / or the second temperature is 50°C to 90°C.
16. The method for detecting porosity according to any one of claims 1 to 15, wherein, The gas detected by the gas adsorption includes one or more of helium and nitrogen.
17. A porosity detection system, comprising: Provides a device for providing electrode assemblies; A packaging device for providing sealing material to the electrode assembly, and subjecting the sealing material to a coating layer covering the outer surface of the electrode assembly to obtain a coated assembly; A first gas adsorption detection device is used to detect the first volume of the coating component by gas adsorption, wherein the first volume is the sum of the solid volume of the coating component and the closed-pore volume of the coating component; A first computing device is configured to obtain the pore volume of the electrode assembly and calculate the porosity of the electrode assembly based on the first volume, the solid volume of the coating layer and the solid volume of the electrode assembly.