Negative electrode plate, method of manufacturing the same, secondary battery and electric device
Patent Information
- Authority / Receiving Office
- KR · KR
- Patent Type
- Patents
- Current Assignee / Owner
- CONTEMPORARY AMPEREX TECHNOLOGY (HONG KONG) LIMITED
- Filing Date
- 2022-10-14
- Publication Date
- 2026-07-29
Smart Images
Figure 112024100141186-PCT00010_ABST
Abstract
Description
Technology Field
[0001] The present application relates to the field of batteries, specifically to a negative electrode plate, a method for manufacturing the same, a secondary battery, and an electric device. Background Technology
[0002] Since secondary batteries possess high capacity and a long lifespan, they are widely applied in electronic devices such as mobile phones, laptop computers, electric scooters, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools.
[0003] As the scope of battery applications becomes increasingly widespread, performance requirements for secondary batteries are also becoming more stringent. To enhance the performance of secondary batteries, electrode plates, such as negative electrode plates, are generally optimized and improved. However, when current negative electrode plates are applied to secondary batteries, their rapid charging and safety performance remain poor, necessitating further improvements.
[0004] The present application is made in consideration of the above-mentioned problem and aims to provide a negative electrode plate, a method for manufacturing the same, a secondary battery, and an electric device.
[0005] A first aspect of the present application provides a method for manufacturing a cathode electrode plate, the method comprising: providing a cathode current collector; coating a photosensitive adhesive on at least one surface of the cathode current collector and curing it to form a photosensitive layer; patterning light into a preset pattern and irradiating the photosensitive layer with light from the surface of the photosensitive layer detached from the cathode current collector to expose the photosensitive layer; developing the exposed photosensitive layer to obtain a photosensitive layer having a concave portion; filling the concave portion with a cathode slurry and curing the cathode slurry to form a cathode film layer; and removing at least a portion of the photosensitive layer to obtain a cathode electrode plate.
[0006] Accordingly, the present application allows for accurate control and regulation of the structural form and distribution form of the concave portions of the photosensitive adhesive by exposing and developing the photosensitive adhesive; the photosensitive adhesive assists in the formation of pores in the cathode film layer, thereby accurately controlling and regulation of the pore structure of the cathode film layer; and the cathode film layer assists in absorbing the electrolyte through the pore structure, which is advantageous for improving the migration speed of active ions in the liquid phase and the desolvation speed from the cathode film layer to the cathode active material, thereby improving the kinetic performance of the cathode electrode plate, and when the cathode electrode plate is applied to a secondary battery, the rapid charging performance of the secondary battery can be improved; the improvement in the kinetic performance of the cathode electrode plate can reduce the problem of concentration difference polarization, and since active ions are partially precipitated, it is not easy to form dendrites, thereby improving the safety performance of the secondary battery.
[0007] In any embodiment, the step of removing at least a portion of the photosensitive layer includes a step in which the time for removing the photosensitive layer is 10s to 60s; and the degree of removal of the photosensitive adhesive can be controlled by adjusting and controlling the processing time.
[0008] In any embodiment, after the step of developing the photosensitive layer, the method further includes the step of heat-treating the developed photosensitive layer; optionally, the temperature of the heat treatment is 200°C to 250°C; and / or the time of the heat treatment is 10 min to 20 min. By further heat-treating the developed photosensitive layer, additional crosslinking may occur within the photosensitive layer, thereby improving the adhesion performance of the photosensitive layer and improving the bonding strength between the photosensitive layer and the negative current collector (5211).
[0009] In any embodiment, a photosensitive adhesive is coated on at least one surface of a negative current collector and cured to form a photosensitive layer, wherein (1) the coating speed is 20 m / min to 70 m / min; (2) the curing temperature is 60°C to 90°C; (3) the curing time is 60 s to 90 s; and (4) the photosensitive layer satisfies at least one of conditions (1) to (4), wherein the photosensitive layer comprises a positive photosensitive adhesive or a negative photosensitive adhesive.
[0010] In any embodiment, the thickness of the photosensitive layer is recorded as T1 μm; the thickness of the cathode film layer is recorded as T2 μm, and 1.0 ≤ T1 / T2 ≤ 1.5. The thickness of the photosensitive layer should be similar to the thickness of the cathode film layer, and such installation is advantageous for reproducing a preset pattern on the cathode film layer and assists in the formation of pores in the cathode film layer. The photosensitive adhesive is a fluid liquid, and in order to cure it, it must generally be heat-treated, and the molding state of the photosensitive adhesive can be controlled by adjusting and controlling the conditions of the heat treatment.
[0011] In any embodiment, the step of patterning light into a preset pattern and exposing the photosensitive layer by irradiating light onto the photosensitive layer from the surface of the photosensitive layer separated from the cathode current collector comprises the step of exposing the photosensitive layer by irradiating light onto the photosensitive layer from the surface of the photosensitive layer separated from the cathode current collector using a mask plate; optionally, the method also satisfies at least one of conditions (I) to (III), wherein (I) the exposure time is 1 s to 10 s; (II) the mask plate comprises a plurality of pores, and the pore diameter is 10 μm to 2500 μm; and (III) the gap between the mask plate and the photosensitive layer is 0 to 400 μm, optionally 0 to 200 μm. The exposure time can control the degree of crosslinking and development effect of the exposed area, and the result of subsequent pore formation can be controlled by controlling the exposure time. By controlling the gap between the mask plate and the photosensitive layer, the pattern of the mask plate can be reproduced on the photosensitive material at the same rate.
[0012] In any embodiment, the cathode slurry comprises a cathode active material, and the cathode active material comprises at least one or several of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material and lithium titanate.
[0013] A second aspect of the present application comprises a cathode plate, wherein the cathode plate comprises a cathode current collector; and a cathode film layer installed on at least one surface of the cathode current collector and comprising a first pore; wherein the size of the first pore along the thickness direction of the cathode plate is H1 μm; and the size of the cathode film layer along the thickness direction of the cathode plate is H μm, optionally 0.2 ≤ H1 / H ≤ 1.0; and more optionally 0.5 ≤ H1 / H ≤ 1.0.
[0014] Accordingly, the present application can improve the mobility of active ions in the liquid phase and the rate of desolvation to the cathode active material by installing a first pore in the cathode film layer and absorbing the electrolyte into the cathode film layer through the first pore, thereby further improving the kinetic performance of the cathode plate and improving the rapid charging performance and safety performance of a secondary battery using the cathode plate. If the present application satisfies the above range, the gram capacity of the cathode plate can be secured by improving the liquid absorption capacity and securing the space occupied by the cathode active material.
[0015] In any embodiment, the cathode plate satisfies at least one of conditions (a) to (c), wherein (a) the first pore diameter is recorded as D μm, 10 ≤ D ≤ 500, and optionally, 10 ≤ D ≤ 100; (b) 10 ≤ H ≤ 300; and (c) 50 ≤ H ≤ 300. Accordingly, if the present application satisfies at least one of the above conditions, the kinetic performance of the cathode plate can be further improved.
[0016] In any embodiment, a plurality of first pores are provided, and the plurality of first pores are provided spaced apart, and the spacing between two adjacent first pores is recorded as W μm, 100 ≤ W ≤ 1000; optionally, 100 ≤ W ≤ 200. If the spacing between two adjacent pores is within the above range, the total porosity of the cathode film layer can be secured, and the gram capacity of the cathode plate can be secured on the basis of improving the kinetic performance of the cathode plate.
[0017] A third aspect of the present application provides a secondary battery comprising a negative electrode plate according to any one embodiment of the second aspect of the present application.
[0018] A fourth aspect of the present application further provides an electric device comprising a secondary battery of any one embodiment of the third aspect of the present application. Brief explanation of the drawing
[0019] In order to more clearly explain the technical solution according to the embodiments of the present application, the drawings to be used in the embodiments of the present application are briefly introduced below. The drawings in the following description are merely some embodiments of the present application, and it is obvious to those skilled in the art that other drawings can be obtained from these drawings without any creative work. FIG. 1 is a schematic diagram of an embodiment for manufacturing a cathode plate of the present application. FIG. 2 is a schematic diagram of an embodiment for manufacturing the cathode plate of the present application. FIG. 3 is a schematic diagram of an embodiment for manufacturing the cathode plate of the present application. FIG. 4 is a schematic diagram of an embodiment for manufacturing the cathode plate of the present application. FIG. 5 is a schematic diagram of an embodiment for manufacturing the cathode plate of the present application. FIG. 6 is a schematic diagram of an embodiment for manufacturing the cathode plate of the present application. FIG. 7 is a schematic diagram of an embodiment for manufacturing a cathode plate of the present application. FIG. 8 is a schematic diagram of the structure of an electrode assembly of a secondary battery of the present application. FIG. 9 is a schematic diagram of one embodiment of the secondary battery of the present application. FIG. 10 is an exploded schematic diagram of an embodiment of the secondary battery of FIG. 9. FIG. 11 is a schematic diagram of one embodiment of the battery module of the present application. FIG. 12 is a schematic diagram of one embodiment of the battery pack of the present application. FIG. 13 is an exploded schematic diagram of an embodiment of the battery pack shown in FIG. 12. FIG. 14 is a schematic diagram of one embodiment of an electric device including a secondary battery of the present application as a power source. The drawing was not produced according to actual proportions. Specific details for implementing the invention
[0020] The embodiments of the negative electrode plate and its manufacturing method, secondary battery, and electric device disclosed in this application are described in detail below. However, unnecessary detailed descriptions may be omitted in some cases. For example, detailed descriptions of known matters and redundant descriptions of structures that are substantially identical may be omitted. This is intended to prevent the following description from becoming unnecessarily long and to aid the understanding of those skilled in the art. Furthermore, the 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.
[0021] The “range” disclosed in this application is limited in the form of lower and upper limits, and a given range is limited by the selection of one lower limit and one upper limit, and the selected lower limit and upper limit define the boundaries of a specific range. A range limited in this way may or may not include endpoint values and may be arbitrarily combined. That is, any lower limit and any upper limit may be combined to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, it should be understood that ranges of 60 to 110 and 80 to 120 are also expected. Additionally, if minimum range values 1 and 2 are listed and maximum range values 3, 4, and 5 are listed, 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 may all be expected. In this application, unless otherwise specified, the numeric range “a to b” represents an abbreviated expression of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numeric range “0 to 5” means that all real numbers between “0 to 5” are listed in this specification, and “0 to 5” is merely an abbreviated expression of a combination of these numeric values. Additionally, when a specific parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter is an integer, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
[0022] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with one another to form a new technical solution. Unless otherwise specified, all technical features and optional technical features of this application may be combined with one another to form a new technical solution.
[0023] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, and are preferably performed sequentially. For example, the statement that a method comprises steps (a) and (b) indicates that the method may comprise steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the statement that a mentioned method may further comprise step (c) indicates that step (c) may be added to the method in any order, for example, the method may comprise steps (a), (b), and (c), steps (a), (c), and (b), or steps (c), (a), and (b).
[0024] Unless otherwise specified, “comprehensive” and “include” as used in this application may mean open and closed forms. For example, “include” and “contain” may indicate that other unlisted components may be included or contained, or that only the listed components are included or contained.
[0025] Unless otherwise specified, the term “or” in this application is inclusive. For example, the phrase “A or B” indicates “A, B, or both A and B.” More specifically, any of the following conditions satisfy the “A or B” condition: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or A and B are both true (or exist).
[0026] In this application, the terms “plural” and “various” mean two or more.
[0027] During the charging process of a secondary battery, the negative electrode plate generally undergoes the following electrochemical process: (1) Active ions (e.g., lithium ions, sodium ions, etc.) released from the positive active material enter the electrolyte and, following the electrolyte, enter the pores of the negative film layer, completing liquid phase conduction of the active ions within the pores, and liquid phase conduction includes liquid phase diffusion; (2) The active ions complete charge exchange with electrons at the surface of the negative active material; (3) The active ions are desolvated and solid phase conduction occurs from the surface of the negative active material into the crystal of the negative active material.
[0028] In a rapid charging system, the liquid phase migration speed and desolvation speed of active ions are slow. To improve these problems and increase the liquid absorption capacity of the cathode film layer, through holes are generally installed in the cathode film layer. Since the electrolyte enters the cathode film layer through the through holes, it is advantageous for the liquid phase migration of active ions.
[0029] However, the inventor discovered that when forming pores in the related technology, pore-forming agents are generally used to exert an etching effect upon volatilization, and pores are etched in the cathode film layer; however, the diameter of the pores produced by this pore-forming method cannot be controlled, which can lead to non-uniform performance of the entire cathode film layer. Furthermore, active ions such as lithium ions may still exhibit concentration difference polarization problems in parts of the cathode film layer. Lithium precipitation easily occurs on the surface of the cathode film layer away from the cathode current collector, and the precipitated metallic lithium increases the barrier for lithium ions entering the cathode active material, thereby exacerbating the concentration difference polarization problem. Additionally, lithium ions may precipitate further on the surface of the cathode film layer, leading to the formation of additional lithium dendrites. These lithium dendrites can penetrate the separator and short-circuit the positive and negative electrode plates, potentially causing safety risks. Moreover, because the liquid-phase conductivity of active ions is slow, the rapid charging performance of the secondary battery is poor.
[0030] In light of this, the inventor proposes a method for manufacturing a cathode plate and uses photolithography technology to transfer a preset pattern onto the cathode plate to assist in the formation of pores in the cathode plate. By accurately controlling and regulating the distribution of pores, the safety performance and rapid charging performance of the cathode plate can be improved when applied to a secondary battery.
[0031] Method for manufacturing a cathode plate
[0032] In a first aspect, the present application proposes a method for manufacturing a cathode plate, and said method,
[0033] Step of providing a negative current collector (S100);
[0034] A step (S200) of forming a photosensitive layer by coating and curing a photosensitive adhesive on at least one surface of a cathode current collector;
[0035] A step (S300) of patterning light into a preset pattern and exposing the photosensitive layer by irradiating the photosensitive layer with light from the surface of the photosensitive layer separated from the cathode current collector;
[0036] A step of developing an exposed photosensitive layer to obtain a photosensitive layer having a concave portion (S400);
[0037] A step (S500) of filling a concave portion with a cathode slurry and curing the cathode slurry to form a cathode film layer;
[0038] It includes the step (S600) of obtaining a cathode plate by removing at least a portion of the photosensitive layer.
[0039] According to the method of the embodiment of the present application, by exposing and developing a photosensitive adhesive, the structural form and distribution form of the concave portion of the photosensitive adhesive can be accurately controlled and controlled; the photosensitive adhesive assists in the formation of pores in the cathode film layer, thereby accurately controlling and controlling the pore structure of the cathode film layer, and the cathode film layer assistly absorbs the electrolyte through the pore structure, which is advantageous for improving the migration speed of active ions in the liquid phase and the desolvation speed from the cathode film layer to the cathode active material, thereby improving the kinetic performance of the cathode electrode plate, and when the cathode electrode plate is applied to a secondary battery, the rapid charging performance of the secondary battery can be improved; the improvement in the kinetic performance of the cathode electrode plate can reduce the problem of concentration difference polarization, and active ions are partially precipitated, making it difficult to form dendrites, thereby improving the safety performance of the secondary battery.
[0040] As illustrated in FIG. 1, in some embodiments, the negative current collector (5211) of step (S100) may use a metal foil or a composite current collector. For example, the metal foil may be copper foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (e.g., a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
[0041] Step (S200) is a process for forming a photosensitive layer (5214), and in some embodiments, the negative current collector (5211) of step (S200) includes two surfaces facing each other in its own thickness direction, and the photosensitive layer (5214) may be installed on one of the two surfaces or on both surfaces. As shown in FIG. 1, the photosensitive layer (5214) is coated on one surface of the negative current collector (5211).
[0042] The photosensitive layer (5214) refers to a film layer structure composed of a photosensitive adhesive, which is a light-sensitive polymer compound. When the polymer compound is irradiated by an external radiation source (e.g., ultraviolet radiation of a certain amount), a photochemical reaction occurs rapidly, causing molecular crosslinking and polymerization to occur and harden, and the molecules can be transformed from their original linear structure into a three-dimensional crosslinked network structure. Depending on the different classification of the exposure light source wavelength, the photosensitive adhesive includes at least one or several of G-ray photosensitive adhesive, I-ray photosensitive adhesive, KrF photosensitive adhesive, and ArF photosensitive adhesive. Depending on the location where it dissolves during the development process, the photosensitive adhesive can be classified into a positive photosensitive adhesive and a negative photosensitive adhesive. The exposed portion of the positive photosensitive adhesive dissolves during the development process, but the exposed portion of the negative photosensitive adhesive does not dissolve during the development process, and the unexposed portion dissolves.
[0043] Optionally, the photosensitive adhesive may be composed of a photosensitive resin with the addition of a monomer crosslinking agent, a photosensitive agent, a polymerization inhibitor, etc., and the photosensitive adhesive has excellent light transmittance, can be rapidly cured under irradiation of a light source, and can be adhered to a negative current collector (5211). For example, the photosensitive adhesive may include photopolymerizable, photocrosslinkable, and photodegradable photosensitive adhesives. A photopolymerizable photosensitive adhesive may be considered a positive photosensitive adhesive and contains a vinyl monomer, which can absorb light energy during the exposure process to generate free radicals, and the free radicals subsequently cross-polymerize to finally produce a polymer. A photodegradable photosensitive adhesive may also be considered a positive photosensitive adhesive and can cause a photochemical reaction after absorbing light energy, causing a distinct change in the affinity and solubility of the material, and during the development process, the photosensitive resin dissolves. The photocrosslinkable photosensitive adhesive can be considered a negative photosensitive adhesive and comprises polyvinyl alcohol olourate; during the exposure process, the double bonds within the molecule are broken, and a crosslinking reaction occurs between the chains to form a stable network structure, thereby preventing the exposed area from dissolving in the developer. The specific material types of the various types of photosensitive adhesives mentioned above can be selected from materials generally used in the prior art and are not repeated here.
[0044] In some embodiments, when a photosensitive adhesive is coated on a cathode current collector (5211), the coating speed is 20 m / min to 70 m / min, and by controlling and adjusting the coating speed of the photosensitive adhesive to control the amount of photosensitive adhesive coated, the thickness of the photosensitive layer (5214) formed by the photosensitive adhesive can be controlled. For example, the coating speed may be a range consisting of 20 m / min, 25 m / min, 30 m / min, 35 m / min, 40 m / min, 45 m / min, 50 m / min, 60 m / min, 70 m / min, or any two of the above values.
[0045] The photosensitive adhesive is a fluid liquid and, in order to cure it, generally requires heat treatment, for example, by baking the photosensitive adhesive in an oven; optionally, the curing temperature is 60°C to 90°C; and / or the curing time is 60s to 90s. For example, the curing temperature may be a range consisting of 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or any two of the above values. The curing time may be a range consisting of 60s, 65s, 70s, 75s, 80s, 85s, 90s, or any two of the above values. The curing temperature and time may be arbitrarily matched, for example, the curing temperature may be 60°C and the curing time may be 90s.
[0046] Optionally, the thickness of the photosensitive layer (5214) is recorded as T1 μm; the thickness of the cathode film layer (5212) is recorded as T2 μm, and 1.0 ≤ T1 / T2 ≤ 1.5.
[0047] The thickness of the photosensitive layer (5214) should be similar to the thickness of the cathode film layer (5212), and such installation is advantageous for replicating a preset pattern on the cathode film layer (5212) and assists in the formation of pores on the cathode film layer (5212). For example, T1 / T2 may be a range consisting of 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 or any two of the above values.
[0048] Step (S300) is a process of exposing the photosensitive layer (5214), and the preset pattern refers to an incident light area that is controlled and adjusted according to the distribution shape of the pores to be installed in the cathode film layer (5212). Considering that the photosensitive adhesive includes a positive photosensitive adhesive and a negative photosensitive adhesive, if a positive photosensitive adhesive is used, the preset pattern may be identical to the exposed area; and if a negative photosensitive adhesive is used, the preset pattern may be identical to the non-exposed area. FIG. 2 illustrates the exposure process, and the arrow in FIG. 2 indicates the direction of incident light.
[0049] The purpose of exposure is to create a difference between the exposed area and the unexposed area of the photosensitive adhesive, which is advantageous for subsequent development. The exposure time not only determines the degree of crosslinking and the development effect of the exposed area, but also affects the clarity of the pattern formed on the photosensitive adhesive. The reason is as follows: if the exposure time is too long, the photosensitive adhesive in the exposed area may be excessively crosslinked, and the photosensitive adhesive may be crosslinked at the boundary between the exposed and unexposed areas; if the exposure time is too short, the photosensitive adhesive in the exposed area may not be sufficiently crosslinked. Optionally, the exposure time may be 1 s to 10 s. For example, the exposure time may be a range consisting of 1 s, 2 s, 3 s, 4 s, 5 s, 6 s, 7 s, 8 s, 9 s, 10 s, or any two of the above values.
[0050] In some embodiments, the exposure light source is various, such as the full ultraviolet spectrum (300 nm to 450 nm), G-line (436 nm), I-line (365 nm), deep ultraviolet (DUV, including 248 nm and 193 nm), and extreme ultraviolet (EUV). Depending on the type of photosensitive adhesive, a light source corresponding to the photosensitive adhesive is selected; for example, if the photosensitive adhesive is a G-line photosensitive adhesive, a G-line light source is selected as the exposure light source. Also, for example, if the photosensitive adhesive is a KrF photosensitive adhesive, a deep ultraviolet light source is selected as the exposure light source. The light intensity is 40 mJ / cm² 2 Up to 75 mj / cm 2 It can be. For example, the luminous intensity is 40 mJ / cm² 2 , 45 mj / cm 2 , 50 mj / cm 2 , 55 mj / cm 2 , 60 mj / cm 2 , 65 mj / cm 2 , 70 mj / cm 2 , 75 mj / cm 2 Alternatively, it may be a range composed of any two of the above values. The exposure time and the light intensity of the exposure work together to adjust and control the clarity of the pattern formed on the photosensitive adhesive.
[0051] To facilitate the exposure process, a mask plate (5215), such as a metal template having through holes, is generally used and combined, and the pore diameter may be 10 μm to 2500 μm; the gap between the mask plate (5215) and the photosensitive layer (5214) may be 0 to 400 μm, and optionally 0 to 200 μm. By adjusting the gap between the mask plate (5215) and the photosensitive layer (5214), the pattern of the mask plate (5215) can be replicated on the photosensitive layer (5214) at the same rate.
[0052] The installation of the mask plate (5215) is associated with a preset pattern, and a mask plate (5215) that matches the required preset pattern is selected. Optionally, the type of pores in the mask plate (5215) may have various shapes such as regular polygonal pores, irregular polygonal pores, circular pores, elliptical pores, etc., and specifically, the pores may be diamond pores, rectangular pores, triangular pores, or elliptical pores.
[0053] Step (S400) is a developing process, in which the exposed photosensitive layer (5214) and the developer chemically react to obtain a photosensitive layer (5214) having a concave portion (52141). Specifically, the exposed area of the positive photosensitive adhesive can be washed away by reacting with the developer and dissolving, and the unexposed area of the negative photosensitive adhesive can be washed away by reacting with the developer and dissolving, thereby leaving a groove or through hole corresponding to the photosensitive layer (5214). For example, the developer may include tetramethylammonium hydroxide, n-butyl acetate, or a 0.4% KOH solution. FIG. 3 illustrates a developing process using a positive photosensitive adhesive, and FIG. 4 illustrates a developing process using a negative photosensitive adhesive.
[0054] After step (S400), the method may further include a step (S700) of heat-treating the developed photosensitive layer (5214). By further heat-treating the developed photosensitive layer (5214), additional crosslinking may occur within the photosensitive layer (5214), thereby improving the adhesion performance of the photosensitive layer (5214) and improving the bonding strength between the photosensitive layer (5214) and the cathode current collector (5211). Optionally, the temperature of the heat treatment is 200°C to 250°C; and / or the time of the heat treatment is 10 min to 20 min. For example, the temperature of the heat treatment may be a range consisting of 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, or any two of the above values. The time of heat treatment may be a range consisting of 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, or any two of the above values. The temperature and time of the heat treatment may be arbitrarily matched, for example, the temperature of the heat treatment may be 200℃ and the time of the heat treatment may be 20 min.
[0055] Step (S500) is a manufacturing process for a cathode film layer (5212). A cathode slurry is coated onto a photosensitive layer (5214), and a cathode film layer (5212) is formed through a curing process such as drying and cold pressing. The cathode slurry is filled into the concave portion (52141), and the cathode slurry is dried to form the cathode film layer (5212). FIG. 5 illustrates the manufacturing process of the cathode film layer (5212), and this is merely an example of manufacturing, and the thickness ratio between layers does not represent the structure of the cathode electrode plate (521).
[0056] Step (S600) is an adhesive removal process, removing the photosensitive adhesive that has not reacted with the developer to expose a portion of the cathode current collector (5211); of course, the photosensitive adhesive may not be completely removed, and some photosensitive adhesive remaining on the surface of the cathode current collector (5211) corresponds to the portion where the photosensitive layer (5214) has been removed along the thickness direction of the cathode electrode plate (521). In some embodiments, the photosensitive adhesive may be removed using wet adhesive removal or dry adhesive removal, and, for example, using a remover such as O2 / N2 plasma, Cl2 / HBr, a hydroxylamine compound, or an HF / HNO3 solution buffered with H2O, reacts with the photosensitive layer (5214) of the cathode electrode plate (521) to dissolve or wash away the photosensitive adhesive, but does not react with the cathode active material; After the above process, the photosensitive layer (5214) may be completely removed, or a portion of the photosensitive layer (5214) may be removed and another portion retained. Optionally, the processing time may be 10 to 60 seconds, and the degree of removal of the photosensitive adhesive may be controlled by adjusting and controlling the processing time. The degree of removal of the photosensitive adhesive may also be controlled by adjusting and controlling the concentration of the remover. FIG. 6 illustrates an adhesive removal process, in which the adhesive is not completely removed, a portion of the photosensitive layer (5214) is retained, and the first pore (5213) is a blind pore. FIG. 7 illustrates another adhesive removal process, in which the adhesive is completely removed, and the first pore (5213) is a straight through hole.
[0057] In the present application, a linear through hole refers to a through hole that penetrates the cathode film layer (5212) along the thickness direction of the cathode electrode plate (521), and there is basically no photosensitive layer (5214) remaining on the cathode electrode plate (521); and a blind pore refers to a pore structure that does not penetrate the cathode film layer (5212).
[0058] A first pore (5213) is present in the cathode film layer (5212), which is advantageous for absorbing the electrolyte into the cathode film layer (5212) through the first pore (5213), thereby improving the amount of liquid absorbed by the cathode electrode plate (521), and accelerating the liquid phase migration speed of active ions so that the active ions can be desolvated more quickly and enter the cathode active material of the cathode film layer (5212), and by improving the migration speed of active ions in the system, the kinetic performance of the cathode electrode plate (521) can be improved, the risk of concentration difference polarization can be reduced, the safety performance of the secondary battery using the cathode electrode plate (521) can be improved, and the rapid charging performance of the secondary battery can be improved.
[0059] In some embodiments, the negative electrode slurry comprises a negative electrode active material, and the negative electrode active material may be a negative electrode active material for a battery known in the art. As an example, the negative electrode active material may include at least one of materials such as artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide, and tin alloys. However, the present invention is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.
[0060] In some embodiments, the cathode slurry optionally further comprises a cathode binder. The cathode binder may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).
[0061] In some embodiments, the cathode slurry optionally further comprises a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
[0062] In some embodiments, the cathode slurry may optionally further include other auxiliary agents such as a thickener (e.g., sodium carboxymethylcellulose (CMC-Na)).
[0063] cathode plate (521)
[0064] A second aspect of the present application further provides a negative electrode plate (521), and the negative electrode plate (521) can be manufactured by the method of any embodiment of the first aspect of the present application.
[0065] In some embodiments, the cathode plate (521) comprises a cathode current collector (5211) and a cathode film layer (5212) installed on at least one surface of the cathode current collector (5211), and the cathode film layer (5212) comprises a first pore (5213), and the size of the first pore (5213) along the thickness direction of the cathode plate (521) is H1 μm; the size of the cathode film layer (5212) along the thickness direction of the cathode plate (521) is H μm, and 0.2 ≤ H1 / H ≤ 1.0; optionally, 0.5 ≤ H1 / H ≤ 1.0.
[0066] H1 / H=1 indicates that the first pore (5213) is a straight through hole penetrating the cathode film layer (5212). H1 / H<1 indicates that the first pore (5213) does not completely penetrate the cathode film layer (5212), in which case the photosensitive layer (5214) can still be considered to remain between the first pore (5213) and the cathode current collector (5211), and the photosensitive layer (5214) is located in the cathode film layer (5212) and installed on the surface of the cathode current collector (5211). For example, H1 / H may be a range consisting of 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or any two of the above values.
[0067] The present application can improve the speed of movement of active ions in the liquid phase and the speed of desolvation to the negative electrode active material by installing a first pore (5213) in the negative electrode film layer (5212) and absorbing the electrolyte into the negative electrode film layer (5212) through the first pore (5213), thereby further improving the kinetic performance of the negative electrode plate (521) and improving the rapid charging performance and safety performance of the secondary battery using the negative electrode plate (521). If the present application satisfies the above range, the gram capacity of the negative electrode plate (521) can be secured by improving the liquid absorption capacity and securing the space occupied by the negative electrode active material.
[0068] Through research, the inventor discovered that the pore diameter and distribution pattern of the first pore (5213) and the cathode film layer (5212) have a certain influence on the liquid phase movement of active ions, and if at least one of the following conditions is satisfied, the kinetic performance of the cathode plate (521) can be further improved.
[0069] In some embodiments, 50≤H≤300. For example, the size of the cathode film layer (5212) along the thickness direction, i.e., the depth of the first pore (5213), may be a range consisting of 50 μm, 60 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 250 μm, 300 μm, or any two of the above values.
[0070] The size of the cathode film layer (5212) along the thickness direction is within the above range, so that the gram capacity of the cathode plate (521) can be secured.
[0071] In some embodiments, 10 ≤ H1 ≤ 300. For example, the size of the first pore (5213) along the thickness direction, i.e., the depth of the first pore (5213), may be a range consisting of 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 250 μm, 300 μm, or any two of the above values. In this application, the depth of the first pore (5213) is less than or equal to the thickness of the cathode film layer (5212).
[0072] If the pore depth of the first pore (5213) is too small, it does not help with liquid absorption; if the pore depth is too large, active ions can be deposited directly on the negative electrode current collector (5211); and if the pore depth of the first pore (5213) is within an appropriate range, it is advantageous for absorbing electrolyte and improves the kinetic performance of the negative electrode plate (521).
[0073] In some embodiments, the pore diameter of the first pore (5213) is recorded as D μm, 10 ≤ D ≤ 500, and optionally, 10 ≤ D ≤ 100. For example, the pore diameter of the first pore (5213) may be a range consisting of 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 300 μm, 400 μm, 500 μm, or any two of the above values.
[0074] If the pore diameter of the first pore (5213) is too small, it is not advantageous for liquid absorption; if the pore diameter is too large, the space occupied by the negative electrode active material is too small, so it is not advantageous for securing the gram capacity of the negative electrode plate (521); if the pore diameter is within an appropriate range, it is advantageous for absorbing the electrolyte, improving the kinetic performance of the negative electrode plate (521), and securing the gram capacity of the negative electrode plate (521).
[0075] In some embodiments, a plurality of first pores (5213) are installed, and the plurality of first pores (5213) are installed at intervals, and the distance between two adjacent first pores is recorded as W μm, 100 ≤ W ≤ 1000; optionally, 100 ≤ W ≤ 200. For example, three adjacent pores may form an equilateral triangle, and the distance between two adjacent pores may be adjusted to W μm ≥ 100 μm. For example, the distance between two adjacent pores may be a range consisting of 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 400 μm, 450 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, or any two of the above values.
[0076] If the spacing between two adjacent pores is within the above range, the total porosity of the cathode film layer (5212) can be secured, and the gram capacity of the cathode plate (521) can be secured on the basis of improving the kinetic performance of the cathode plate (521).
[0077] secondary battery
[0078] In a third aspect, the present application proposes a secondary battery. The secondary battery (5) includes a negative electrode plate (521) according to any one embodiment of the second aspect of the present application, and can improve the rapid charging performance and safety performance of the secondary battery.
[0079] [Bipolar plates]
[0080] The above secondary battery (5) further includes a positive electrode plate (522).
[0081] In some embodiments, the positive electrode plate (522) comprises a positive current collector and a positive film layer installed on at least one surface of the positive current collector. For example, the positive current collector has two surfaces facing each other in its thickness direction, and the positive film layer is installed on either or both of the two facing surfaces of the positive current collector.
[0082] The above-mentioned positive film layer comprises a positive active material, and the positive active material may be a positive active material for a secondary battery known in the art. As an example, the positive active material may include at least one of a layered positive active material (e.g., ternary, lithium nickelate / sodium, lithium cobaltate / sodium, lithium manganate / sodium, lithium / sodium-rich layered and rock salt-like layered materials), an olivine-type phosphate active material, and a spinel-structured positive active material (e.g., spinel lithium manganate, spinel nickel-manganate, lithium-rich spinel lithium manganate, and nickel-manganate, etc.).
[0083] For example, the general formula of a layered cathode active material is Li x A y Ni a Co b Mn c M (1-a-b-c) Y zAnd, where, 0≤x≤2.1, 0≤y≤2.1, and 0.9≤x+y≤2.1; 0≤a≤1, 0≤b≤1, 0≤c≤1, and 0.1≤a+b+c≤1; and 1.8≤z≤3.5; A is selected from one or more of Na, K, and Mg; M is selected from one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y is selected from one or more of O and F. Optionally, y=0. Specifically, the layered cathode active material is lithium cobaltate LCO, lithium nickelate LNO, lithium manganate LMO, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811) and LiNi 0.5 Co 0.2 Mn 0.3 It may include at least one or several of O2(NCM523).
[0084] For example, the general formula of an olivine-type phosphate active material is Li x A y Me a M b P 1-c X c Y zAnd, where, 0≤x≤1.3, 0≤y≤1.3 and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5 and 0.9≤a+b≤1.5; 0≤c≤0.5 and 3≤z≤5; A is selected from one or more of Na, K, and Mg; Me is selected from one or more of Mn, Fe, Co, and Ni; M is selected from one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X is selected from one or more of S, Si, Cl, B, C, and N; and Y is selected from one or more of O and F. Specifically, the olivine-type phosphate active material includes at least one or several of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.
[0085] For example, the general formula of a spinel structured cathode active material is Li x A y Mn a M 2-a Y z And, where, 0≤x≤2, 0≤y≤1, and 0.9≤x+y≤2; 0.5≤a≤2; 3≤z≤5; A is selected from one or more of Na, K, and Mg; M is selected from one or more of Ni, Co, B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y is selected from one or more of O and F. Specifically, the spinel structured cathode active material is LiMn2O4, LiNi 0.5 Mn 1.5 O4, LiCr 0.3 Mn 1.7 O4, Li 1.1 Al0.1 Mn 1.9 O4, Li2Mn2O4 and Li 1.5 It is selected from at least one or several of Mn2O4.
[0086] In some embodiments, the anode film layer optionally further comprises an anode conductive agent. The present application does not particularly limit the type of anode conductive agent, and as an example, the anode conductive agent may comprise at least one or a combination selected from superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage content of the anode conductive agent is 5% or less based on the total mass of the anode film layer.
[0087] In some embodiments, the anode film layer optionally further comprises an anode binder. The present application does not particularly limit the type of anode binder, and as an example, the anode binder may comprise at least one or a combination selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin. In some embodiments, the mass percentage content of the anode binder is 5% or less based on the total mass of the anode film layer.
[0088] In some embodiments, the positive current collector may use a metal foil or a composite current collector. As an example of a metal foil, an aluminum foil or an aluminum alloy foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer, and as an example, the metal material may include at least one or a combination selected from aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, and the polymer material base layer may include at least one or a combination selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).
[0089] The anode film layer is generally formed by coating an anode slurry onto an anode current collector, followed by drying and cold pressing. The anode slurry is generally formed by dispersing an anode active material, a selective conductive agent, a selective binder, and any other components in a solvent and stirring uniformly. The solvent may be N-methylpyrrolidone (NMP), but is not limited thereto.
[0090] [Electrolytes]
[0091] The above secondary battery (5) further includes an electrolyte.
[0092] The electrolyte performs ion transfer between the positive electrode plate (522) and the negative electrode plate (521). The present application does not specifically limit the type of electrolyte, so it may be selected as needed. For example, the electrolyte may be a liquid, a gel, or all solid.
[0093] In some embodiments, the electrolyte uses an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.
[0094] In some embodiments, the electrolyte uses an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.
[0095] As an example, the lithium salt may include at least one or a combination selected from lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonimide (LiFSI), lithium bistrifluoromethanesulfonimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobisoxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).
[0096] As an example, the organic solvent may include at least one or a combination selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), butyrolactone (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).
[0097] In some embodiments, the electrolyte optionally further comprises additives. For example, the additives may include a negative electrode film-forming additive and a positive electrode film-forming additive, and may further include additives capable of improving specific performance of the battery, such as an additive that improves battery overcharge performance, or an additive that improves the high or low temperature performance of the battery.
[0098] [Separator]
[0099] The above secondary battery further includes a separator (523).
[0100] In some embodiments, the secondary battery (5) further comprises a separator (523). The present application does not particularly limit the type of separator (523) and any known porous structure separator (523) having excellent chemical stability and mechanical stability may be selected.
[0101] In some embodiments, the material of the separator (523) may be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator (523) may be a single-layer film or a multi-layer composite film, but is not particularly limited. If the separator (523) is a multi-layer composite film, the material of each layer may be the same or different, but is not particularly limited.
[0102] As illustrated in FIG. 8, in some embodiments, the positive electrode plate (522), the negative electrode plate (521), and the separator (523) can be manufactured into an electrode assembly (52) through a winding process or a lamination process.
[0103] The present application does not specifically limit the shape of the secondary battery and may be cylindrical, rectangular, or any other shape. FIG. 9 is an exemplary secondary battery (5) with a rectangular structure.
[0104] In some embodiments, as illustrated in FIGS. 9 and 10, the outer packaging may include a case (51) and a cover plate (53). Here, the case (51) may include a bottom plate and a side plate connected to the bottom, and the bottom plate and the side plate form a receiving cavity by means of an enclosure. The case (51) has an opening communicating with the receiving cavity, and the cover plate (53) is positioned to cover the opening and seal the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator may form an electrode assembly (52) through a winding process or a lamination process. The electrode assembly (52) is sealed and packaged in the receiving cavity. Electrolyte is infiltrated into the electrode assembly (52). The number of electrode assemblies (52) included in the secondary battery (5) may be one or multiple and may be adjusted as needed.
[0105] The method for manufacturing the secondary battery (5) of the present application is known. In some embodiments, a positive electrode plate, a separator, a negative electrode plate, and an electrolyte may be assembled to form a secondary battery (5). As an example, an electrode assembly may be formed by winding the positive electrode plate, the separator, and the negative electrode plate through a winding process or a lamination process, the electrode assembly is placed in an external package, dried, and then an electrolyte is injected, and a secondary battery (5) is obtained by undergoing processes such as vacuum packaging, storage, formation, and molding.
[0106] In some embodiments of the present application, the secondary battery (5) according to the present application may be assembled into a battery module, and the number of secondary batteries (5) included in the battery module may be multiple, and the specific number may be adjusted according to the application and capacity of the battery module.
[0107] FIG. 11 is a schematic diagram of an exemplary battery module (4). As shown in FIG. 11, in the battery module (4), a plurality of secondary batteries (5) may be installed in a sequential arrangement along the length direction of the battery module (4). Of course, they may also be arranged in any other arbitrary manner. In addition, the plurality of secondary batteries (5) may be secured by fasteners.
[0108] Optionally, the battery module (4) may further include an outer case having a receiving space, and a plurality of secondary batteries (5) are received in the receiving space.
[0109] In some embodiments, the above-described battery module may be assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.
[0110] FIGS. 12 and 13 are schematic diagrams of an exemplary battery pack (1). As illustrated in FIGS. 12 and 13, the battery pack (1) may include a battery box and a plurality of battery modules (4) installed in the battery box. The battery box comprises an upper box body (2) and a lower box body (3), wherein the upper box body (2) is intended to cover the lower box body (3) to form a sealed space for accommodating the battery modules (4). A plurality of battery modules (4) may be arranged in the battery box in any manner.
[0111] electrical device
[0112] In a fourth aspect, the present application provides an electric device comprising at least one of a secondary battery, a battery module, and a battery pack of the present application. The secondary battery, the battery module, and the battery pack may be used as a power source for the electric device and may also be used as an energy storage unit for the electric device. The electric device includes, but is not limited to, mobile devices (e.g., mobile phones, laptop computers, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
[0113] The electrical device can select a secondary battery, battery module, or battery pack depending on usage demand.
[0114] FIG. 14 is a schematic diagram of an exemplary electric device. The electric device (6) is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the demand of the electric device for high power and high energy density, a battery pack (1) or a battery module may be used.
[0115] Other examples of electrical devices may include mobile phones, tablet computers, and laptop computers. Generally, the electrical devices are required to be thin and light, and can use secondary batteries as a power source.
[0116] Examples
[0117] The embodiments of the present application are described below. The embodiments described below are illustrative and are used merely to interpret the present application and should not be understood as limiting the present application. Where specific techniques or conditions are not disclosed in the embodiments, they shall be performed in accordance with the techniques or conditions described in literature within the art or product descriptions. Reagents or equipment used without manufacturer's indication are general products available on the market.
[0118] Example 1
[0119] 1. Manufacture of positive electrode plates
[0120] An aluminum foil with a thickness of 12 μm is used as the positive current collector.
[0121] A positive active material, carbon black as a conductive agent, and polyvinylidene fluoride (PVDF) as a binder are sufficiently stirred and mixed in an appropriate amount of NMP as a solvent in a weight ratio of 97.5:1.4:1.1 to form a uniform positive slurry; the positive slurry is uniformly coated on the surface of an aluminum foil as a positive current collector, and after drying and cold pressing, a positive electrode plate is obtained.
[0122] 2. Manufacture of cathode plate
[0123] A copper foil with a thickness of 8 μm is used as the negative current collector.
[0124] A positive photosensitive adhesive (specifically comprising epoxy resin DER331J, polyurethane-modified epoxy resin EPU-10, acrylic acid, oxalic anhydride, benzyl triethylammonium chloride, p-benzenediphenol, terephthalic anhydride, and benzoin ethyl ether) is coated on a cathode current collector at a coating speed of 50 m / min, baked in an oven after coating at a baking temperature of 60°C and a baking time of 120 s, and the photosensitive adhesive is cured into a photosensitive layer.
[0125] Luminous intensity 65 mJ / cm² under mask cover 2 The photosensitive layer is irradiated using ultraviolet light (wavelength 365 nm), and the exposure time is 5 s. The mask plate is a metal template with circular pores, and the pore diameter is 2 mm.
[0126] Tetramethylammonium hydroxide, a developer, is sprayed onto the photosensitive adhesive, the spraying speed is 20 to 70 m / min, and the flow rate is 0.1 to 1 L / min, and the exposed area of the positive photosensitive adhesive is dissolved and washed, so that a cylindrical array remains on the photosensitive layer.
[0127] The developed photosensitive layer is heat-treated, the heat treatment temperature is 250℃, and the heat treatment time is 10 min.
[0128] Artificial graphite as a cathode active material, carbon black as a conductive agent, styrene-butadiene rubber (SBR) as a binder, and sodium carboxymethylcellulose (CMC) as a thickener are sufficiently stirred and mixed in an appropriate amount of deionized water as a solvent in a weight ratio of 96.8:0.7:1.3:1.2 to form a uniform cathode slurry. The cathode slurry is coated into the pores of a photosensitive layer, and a cathode film layer is formed after drying and cold pressing.
[0129] An HF / HNO3 solution buffered with H2O (the concentration is 3 wt% / 20 wt%) is used and reacted with the photosensitive adhesive of the cathode plate for 50 seconds, so that the photosensitive adhesive is dissolved, and after treatment, the cathode film layer has a first pore, and the cathode film layer having the first pore and the cathode current collector form a cathode plate.
[0130] 3. Separator
[0131] A porous polyethylene (PE) membrane is used as a separator.
[0132] 4. Preparation of Electrolyte
[0133] In an environment with a moisture content of less than 10 ppm, an electrolyte solvent is obtained by mixing non-aqueous organic solvents, ethylene carbonate EC and diethyl carbonate DMC, in a 1:1 volume ratio, and then a lithium salt is mixed with the mixed solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.
[0134] 5. Manufacturing of secondary batteries
[0135] The above positive electrode plate, separator, and negative electrode plate are sequentially stacked so that the separator is positioned between the positive electrode plate and the negative electrode plate to act as an insulator, and then wound to obtain an electrode assembly. The electrode assembly is placed in an external packaging case and dried, then an electrolyte is injected, and a lithium-ion battery is obtained through processes such as vacuum packaging, storage, chemical formation, and molding.
[0136] Example 2
[0137] A lithium-ion battery is manufactured in a manner similar to Example 1, and the difference from Example 1 is that in Examples 2-1 to 2-3, during the process of manufacturing the negative electrode plate, the reaction time between the HF / HNO3 solution buffered with H2O and the photosensitive layer of the negative electrode plate is controlled to control the depth of the pores.
[0138] Comparative Example 1
[0139] Comparative Example 1 manufactures a lithium-ion battery in a manner similar to Example 1, and the difference from Example 1 is that in the process of manufacturing the negative electrode plate in Comparative Example 1, the manufacturing process of the negative electrode plate is as follows.
[0140] A copper foil with a thickness of 8 μm is used as the negative current collector.
[0141] Artificial graphite as a cathode active material, carbon black as a conductive agent, styrene-butadiene rubber (SBR) as a binder, and sodium carboxymethylcellulose (CMC) as a thickener are sufficiently stirred and mixed in an appropriate amount of deionized water as a solvent in a weight ratio of 96.8:0.7:1.3:1.2 to form a uniform cathode slurry. The cathode slurry is coated onto the surface of a cathode current collector, and a cathode film layer is formed after drying and cold pressing.
[0142] The relevant parameters of Example 1, Example 2 and Comparative Example 1 are as shown in Table 1.
[0143] Table 1
[0144]
[0145] In Table 1, the adhesive removal time refers to the reaction time of the photosensitive layer of the cathode electrode plate with the HF / HNO3 solution buffered with H2O. H1 represents the size of the first pore (depth of H1) along the thickness direction of the cathode electrode plate. H represents the size of the cathode film layer (thickness of H) along the thickness direction of the cathode electrode plate.
[0146] As can be seen from Table 1, the cathode film layer of Comparative Example 1 has no artificial pore formation, so there is a risk of concentration difference polarization, poor kinetic performance, and poor rapid charging performance. Compared to Comparative Example 1, the embodiment of the present application forms pores through an etching process, thereby reducing the risk of concentration difference polarization and improving kinetic performance, which can improve rapid charging performance and safety performance.
[0147] Example 3
[0148] Example 3 manufactures a lithium-ion battery in a manner similar to Example 1, and the difference from Example 1 is that Examples 3-1 to 3-6 adjust the specifications of the coating mask plate, and the specifications of the mask plate affect the pore diameter parameter of the first pore.
[0149] The relevant parameters of Example 1 and Example 3 are as shown in Table 2.
[0150] Table 2
[0151]
[0152] As can be seen from Table 2, by adjusting the specifications of the mask plate and controlling the pore structure of the cathode film layer, the rapid charging performance and safety performance of the secondary battery can be controlled.
[0153] Example 4
[0154] Example 4 manufactures a lithium-ion battery in a manner similar to Example 1, and the difference from Example 1 is that in the process of manufacturing the negative electrode plate, heat treatment after development is not performed in Example 4, and the specific manufacturing process of the negative electrode plate is as follows.
[0155] A copper foil with a thickness of 8 μm is used as the negative current collector.
[0156] A positive photosensitive adhesive (specifically comprising epoxy resin DER331J, polyurethane-modified epoxy resin EPU-10, acrylic acid, oxalic anhydride, benzyl triethylammonium chloride, p-benzenediphenol, terephthalic anhydride, and benzoin ethyl ether) is coated on a cathode current collector at a coating speed of 50 m / min, baked in an oven after coating at a baking time of 60°C and a baking temperature of 120 s, and the photosensitive adhesive is cured into a photosensitive layer.
[0157] Luminous intensity 65 mJ / cm² under mask cover 2 The photosensitive layer is irradiated using ultraviolet light (wavelength 365 nm), and the exposure time is 5 s. The mask plate is a metal template with circular pores, and the pore diameter is 2 mm.
[0158] Tetramethylammonium hydroxide, a developer, is sprayed onto the photosensitive adhesive, the spraying speed is 20 to 70 m / min, and the flow rate is 0.1 to 1 L / min, and the exposed area of the positive photosensitive adhesive is dissolved and washed, so that a cylindrical array remains on the photosensitive layer.
[0159] Artificial graphite as a cathode active material, carbon black as a conductive agent, styrene-butadiene rubber (SBR) as a binder, and sodium carboxymethylcellulose (CMC) as a thickener are sufficiently stirred and mixed in an appropriate amount of deionized water as a solvent in a weight ratio of 96.8:0.7:1.3:1.2 to form a uniform cathode slurry. The cathode slurry is coated into the pores of a photosensitive layer, and a cathode film layer is formed after drying and cold pressing.
[0160] An HF / HNO3 solution buffered with H2O (the concentration is 3 wt% / 20 wt%) is used and reacted with the photosensitive layer of the cathode plate for 60 seconds, so that the photosensitive adhesive is dissolved, and after treatment, the cathode film layer has a first pore, and the cathode film layer having the first pore and the cathode current collector form the cathode plate.
[0161] The relevant parameters of Example 1 and Example 4 are as shown in Table 3.
[0162] Table 3
[0163]
[0164] As can be seen from Table 3, Example 4 did not perform heat treatment after forming the photosensitive layer, whereas Example 1 performed heat treatment, which allows the photosensitive layer to be more crosslinked and improves the bonding strength between the negative electrode current collector and the photosensitive layer, resulting in superior structural stability inside the negative electrode plate and preventing easy delamination between layers, which is advantageous for improving the rapid charging performance of the secondary battery.
[0165] Measurement part
[0166] A. Parameter testing of the cathode plate
[0167] 1. Thickness H of the cathode film layer and depth H1 of the first pore
[0168] After measuring the thickness of the cathode plate at at least 12 different locations along the thickness direction of the cathode plate using a multimeter, the average value is used as the thickness h1 of the cathode plate; then, the thickness of the cathode film layer is obtained by subtracting the thickness of the cathode current collector.
[0169] 2. Pore diameter, depth H1 of the first pore, and spacing between two adjacent first pores
[0170] Observations are made using a scanning electron microscope (SEM) (the SEM model is Thermo Scientific Apreo 2).
[0171] B. Parameter testing of secondary batteries
[0172] 1. Secondary battery rapid charging performance test
[0173] At 25℃, the secondary battery prepared above is charged with a constant current of 0.33C to a charge cutoff voltage of 4.4V, then charged with a constant voltage of 0.05C, left for 5 min, then discharged with a constant current of 0.33C to a discharge cutoff voltage of 2.8V, and the actual capacity is recorded as C0.
[0174] Next, the secondary battery is charged with a constant current sequentially at 0.5C0, 1C0, 1.5C0, 2C0, 2.5C0, 3C0, 3.5C0, 4C0, and 4.5C0 until the full battery cutoff voltage of 4.4V, and after each charge is complete, it is discharged at 1C0 until the full battery discharge cutoff voltage of 2.8V, while charging at different rates of 10%, 20%, 30%… … The corresponding negative potential is recorded when charging to 80% SOC (State of Charge), a rate-negative potential curve is plotted under different SOC conditions, and after linear fitting, the corresponding charging rate is obtained when the negative potential is 0V under different SOC conditions, wherein the charging rate is the charging window of the said SOC state and is recorded as C10%SOC, C20%SOC, C30%SOC, C40%SOC, C50%SOC, C60%SOC, C70%SOC, and C80%SOC, respectively, and the secondary battery is charged from 10% SOC to 80% SOC by calculating according to the formula (60 / C20%SOC + 60 / C30%SOC + 60 / C40%SOC + 60 / C50%SOC + 60 / C60%SOC + 60 / C70%SOC + 60 / C80%SOC) × 10%. Obtain the required charging time T. A shorter charging time T indicates superior rapid charging performance of the secondary battery.
[0175] Although this application has been described with reference to preferred embodiments, improvements may be made and components thereof may be replaced with equivalents without departing from the scope of this application. In particular, each technical feature mentioned in each embodiment may be combined in any manner provided that 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. Explanation of the symbols
[0176] 1: Battery pack; 2: Upper box body; 3: Lower box body; 4: Battery module; 5: Secondary battery; 51: Case; 52: Electrode assembly; 521: Cathode plate; 5211: Cathode current collector; 5212: Cathode film layer; 5213: First pore; 5214: Photosensitive layer; 52141: Recess; 5215: Mask plate 522: Positive electrode plate; 523: Separator; 53: Cover plate; 6: Electrical device.
Claims
Claim 1 A method for manufacturing a cathode electrode plate comprises the steps of: providing a cathode current collector; coating a photosensitive adhesive on at least one surface of the cathode current collector and curing it to form a photosensitive layer; patterning light into a preset pattern and irradiating the photosensitive layer with the light from the surface of the photosensitive layer separated from the cathode current collector to expose the photosensitive layer; developing the exposed photosensitive layer to obtain a photosensitive layer having a concave portion; filling the concave portion with a cathode slurry and curing the cathode slurry to form a cathode film layer; removing at least a portion of the photosensitive layer to obtain the cathode electrode plate, wherein a first pore is formed in the cathode film layer and an electrolyte is absorbed into the cathode film layer through the first pore, wherein the size of the first pore along the thickness direction of the cathode electrode plate is H1 μm; and the size of the cathode film layer along the thickness direction of the cathode electrode plate is H μm, and the cathode electrode plate having a thickness of 0.2 ≤ H1 / H ≤ 1.0 Method of manufacturing. Claim 2 A method according to claim 1, wherein the step of removing at least a portion of the photosensitive layer comprises a step in which the time for removing the photosensitive layer is 10s to 60s. Claim 3 A method according to claim 1, further comprising, after the step of developing the photosensitive layer, a step of heat-treating the developed photosensitive layer, wherein the temperature of the heat treatment is 200℃ to 250℃ and the time of the heat treatment is 10 min to 20 min. Claim 4 A method according to any one of claims 1 to 3, wherein, in the step of forming a photosensitive layer by coating and curing a photosensitive adhesive on at least one surface of the cathode current collector, (1) the coating speed is 20 m / min to 70 m / min; (2) the curing temperature is 60℃ to 90℃; (3) the curing time is 60 s to 90 s; and (4) the photosensitive layer satisfies at least one of conditions (1) to (4), wherein the photosensitive layer comprises a positive photosensitive adhesive or a negative photosensitive adhesive. Claim 5 A method according to any one of claims 1 to 3, wherein the thickness of the photosensitive layer is recorded as T1 μm; the thickness of the cathode film layer is recorded as T2 μm, and 1.0 ≤ T1 / T2 ≤ 1.
5. Claim 6 In any one of claims 1 to 3, the step of patterning light into a preset pattern and exposing the photosensitive layer by irradiating the light from the surface of the photosensitive layer separated from the cathode current collector to the photosensitive layer comprises the step of exposing the photosensitive layer by irradiating the light from the surface of the photosensitive layer separated from the cathode current collector using a mask plate; the method further satisfies at least one of conditions (I) to (III), wherein (I) the exposure time is 1 s to 10 s; (II) the mask plate comprises a plurality of pores, and the pore diameter is 10 μm to 2500 μm; and (III) the gap between the mask plate and the photosensitive layer is 0 to 400 μm. Claim 7 A method according to any one of claims 1 to 3, wherein the cathode slurry comprises a cathode active material, and the cathode active material comprises at least one or several of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate. Claim 8 A cathode plate manufactured by the method according to claim 1, comprising: a cathode current collector; and a cathode film layer installed on at least one surface of the cathode current collector and comprising a first pore, wherein an electrolyte is absorbed into the cathode film layer through the first pore, the size of the first pore along the thickness direction of the cathode plate is H1 μm; the size of the cathode film layer along the thickness direction of the cathode plate is H μm, and 0.2 ≤ H1 / H ≤ 1.
0. Claim 9 In claim 8, the cathode plate satisfies at least one of the following: (a) the first pore diameter is recorded as D μm and 10 ≤ D ≤ 500; (b) 10 ≤ H1 ≤ 300; and (c) 50 ≤ H ≤ 300. Claim 10 In claim 8, the first pores are installed in plurality, the plurality of first pores are installed at intervals, the interval between two adjacent first pores is recorded as W μm, and the cathode plate is 100 ≤ W ≤ 1000. Claim 11 A secondary battery comprising a negative electrode plate according to any one of claims 8 to 10. Claim 12 An electric device including a secondary battery according to paragraph 11.