Electrode plate manufacturing method and electrode plate

Abstract

The invention relates to an electrode plate manufacturing method and an electrode plate. The method comprises the following steps: performing first acoustic resonance mixing on an electrode active material and VGCF through an acoustic resonance device to obtain a first premix; performing second acoustic resonance mixing on the first premix and PTFE through an acoustic resonance device to obtain a second premix; the mixing strength of the first acoustic resonance mixing is greater than that of the second acoustic resonance mixing; performing fibration treatment on the second premix through a fibration treatment device to obtain an electrode mixture; calendaring the electrode mixture through a rolling device to obtain an electrode film; and performing thermal compounding on the electrode film and the current collector through a rolling device to obtain the electrode plate. By the adoption of the method, the agglomeration structure of the VGCF can be broken through an acoustic resonance mixing mode, so that the VGCF can be distributed in the electrode mixture with high uniformity, and it can be ensured that an electrode plate manufactured based on the electrode mixture has high cohesion.

Description

Technical Field

[0001] This application relates to the field of electrode manufacturing technology, and in particular to an electrode manufacturing method and an electrode. Background Technology

[0002] From consumer electronics to electric vehicles and grid storage, the demand for energy storage solutions is constantly growing across various industries. Consequently, the demand for efficient, sustainable, and cost-effective batteries is also rapidly increasing. In the field of battery electrode manufacturing technology, dry electrode technology has become the primary method for electrode manufacturing due to its advantages such as environmental friendliness and simplicity.

[0003] Currently, electrode sheets manufactured using dry electrode technology suffer from poor cohesion, leading to easy powder shedding and consequently affecting their cycle life. Clearly, this significantly impacts the production yield of the electrode sheets. Summary of the Invention

[0004] Therefore, it is necessary to provide an electrode manufacturing method, an electrode, and an energy storage device that can ensure the manufactured electrode has high cohesion, in order to address the above-mentioned technical problems.

[0005] In a first aspect, this application provides a method for manufacturing an electrode sheet, comprising:

[0006] The electrode active material and VGCF are mixed using an acoustic resonance device to obtain a first premix.

[0007] The first premix and PTFE are mixed using an acoustic resonance device to obtain a second premix; the mixing intensity of the first acoustic resonance mixture is greater than that of the second acoustic resonance mixture.

[0008] The second premix is ​​subjected to fiberization treatment using a fiberization treatment device to obtain an electrode mixture;

[0009] Electrode films are obtained by calendering the electrode mixture using a rolling device;

[0010] Electrode sheets are obtained by thermally bonding the electrode film and the current collector using a rolling device.

[0011] In an exemplary embodiment, the second premix is ​​obtained by second acoustic resonance mixing of the first premix and PTFE using an acoustic resonance device, comprising:

[0012] The first premix and the conductive carbon material are mixed by a third acoustic resonance device to obtain a third premix.

[0013] The third premix and PTFE are mixed using an acoustic resonance device to obtain a second premix; the mixing intensity of the first acoustic resonance mixture is greater than that of the third acoustic resonance mixture, and the mixing intensity of the third acoustic resonance mixture is greater than that of the second acoustic resonance mixture.

[0014] In an exemplary embodiment, the mixing acceleration of the first acoustic resonance mixture is 70g~100g, the mixing acceleration of the second acoustic resonance mixture is 10g~40g, and the mixing acceleration of the third acoustic resonance mixture is 40g~70g.

[0015] In an exemplary embodiment, the mixing time for the first acoustic resonance mixture is 5 min to 30 min, the mixing time for the second acoustic resonance mixture is 3 min to 10 min, and the mixing time for the third acoustic resonance mixture is 5 min to 15 min.

[0016] In one exemplary embodiment, the mass percentage of VGCF in the second premix is ​​0.1% to 5%, and the mass percentage of conductive carbon material in the second premix is ​​0.5% to 5%.

[0017] In one exemplary embodiment, the electrode active material has a mass percentage of 80% to 99% in the second premix, and the PTFE has a mass percentage of 0.1% to 2% in the second premix.

[0018] In an exemplary embodiment, the above-mentioned calendering of the electrode mixture using a rolling device to obtain an electrode film includes:

[0019] The electrode mixture is calendered using a rolling device at a first calendering temperature to obtain an electrode film;

[0020] The above-mentioned method of thermally bonding the electrode film and the current collector using a rolling device to obtain the electrode sheet includes:

[0021] The electrode sheet is obtained by thermally bonding the electrode film and the current collector at a second calendering temperature using a rolling device.

[0022] The first rolling temperature is 50℃~250℃, and the second rolling temperature is 100℃~250℃.

[0023] In one exemplary embodiment, the electrode active material is a positive electrode active material or a negative electrode active material;

[0024] The positive electrode active material is at least one of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, lithium manganese oxide, and lithium cobalt oxide;

[0025] The negative electrode active material is at least one of natural graphite, synthetic graphite, hard carbon, soft carbon, activated carbon, silicon, silicon oxide, silicon carbide, tin, tin oxide, and lithium titanate.

[0026] In an exemplary embodiment, the current collector is any one of the following: aluminum foil coated with a conductive carbon layer, copper foil coated with a conductive carbon layer, nickel foil coated with a conductive carbon layer, stainless steel foil coated with a conductive carbon layer, porous aluminum foil coated with a conductive carbon layer, porous copper foil coated with a conductive carbon layer, porous nickel foil coated with a conductive carbon layer, porous stainless steel foil coated with a conductive carbon layer, and etched aluminum foil coated with a conductive carbon layer.

[0027] Secondly, this application also provides an electrode sheet manufactured using the electrode sheet manufacturing method described in any one of the first aspects of this application.

[0028] Thirdly, this application also provides an energy storage device, which includes the electrode sheet as described in the second aspect of this application.

[0029] The aforementioned electrode manufacturing method, electrode, and energy storage device utilize an acoustic resonance device to perform a first acoustic resonance mixing of the electrode active material and VGCF based on a high mixing intensity. This ensures that the aggregated structure of VGCF is sufficiently broken down. After the manufacturing process steps of first acoustic resonance mixing, second acoustic resonance mixing, and fiberization treatment, the electrode active material, VGCF, and PTFE can be distributed in the electrode mixture with high uniformity. Consequently, the electrode sheet manufactured based on the electrode mixture has high cohesiveness. Furthermore, compared to the mechanical mixing method used in traditional dry electrode technology, PTFE can be more uniformly distributed in the electrode mixture under the action of acoustic resonance mixing. Therefore, the mass percentage of PTFE in the electrode mixture can be appropriately reduced, thereby lowering the manufacturing cost of the electrode sheet. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of VGCF under an electron microscope.

[0032] Figure 2 for Figure 1 A schematic diagram of the structure of VGCF after mechanical mixing with graphite materials under an electron microscope;

[0033] Figure 3 A schematic flowchart illustrating an electrode sheet manufacturing method provided in an embodiment of this application;

[0034] Figure 4 A schematic diagram of the structure of VGCF after being mixed with graphite material through a first acoustic resonance, provided as an embodiment of this application, under an electron microscope;

[0035] Figure 5 A comparative schematic diagram showing the cohesive strength enhancement effect of a graphite electrode sheet manufactured by an electrode sheet manufacturing method provided in this application embodiment;

[0036] Figure 6 This is a schematic diagram of the structure of a roller pressing device provided in an embodiment of this application;

[0037] Figure 7 A schematic flowchart illustrating another electrode sheet manufacturing method provided in this application embodiment;

[0038] Figure 8 This is a structural block diagram of an electrode sheet manufacturing system provided in an embodiment of this application. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0040] This application was made by the inventor based on his understanding and research into the following issues:

[0041] As described in the background section, electrode sheets manufactured using existing dry electrode technology typically suffer from poor cohesion, leading to easy powder shedding and consequently affecting their cycle life. This clearly impacts the production yield of the electrode sheets. Therefore, the cohesion of the manufactured electrode sheets can be improved by introducing a fibrous conductive agent into the electrode mixture, thereby enhancing the cohesion through fiber reinforcement. For example, the fibrous conductive agent can be VGCF (Vapor Grown Carbon Fiber).

[0042] VGCF refers to a type of carbon fiber nanomaterial prepared by chemical vapor deposition. Due to its high electrical conductivity, high thermal conductivity, and high strength, VGCF is primarily used as a conductive agent in lithium-ion batteries and can also be used to reinforce composite materials. In the manufacturing process of electrode sheets using dry electrode technology, introducing VGCF into the electrode mixture and ensuring its uniform distribution ensures that VGCF effectively builds continuous conductive bridges between the active material particles. This not only reduces the resistance of the manufactured electrode sheet but also strengthens the fiber structure, significantly improving the cohesion and flexibility of the electrode sheet.

[0043] Figure 1 This is a schematic diagram of the structure of VGCF under an electron microscope. Figure 2 for Figure 1 A schematic diagram of the structure of VGCF after mechanical mixing with graphite (a negative electrode active material) under an electron microscope, as shown in the figure. Figure 1 As shown, VGCF has an aggregated structure, and this aggregated structure is based on the intermolecular van der Waals forces between fibers in VGCF. Therefore, as... Figure 2 As shown, the shear force provided by the mechanical mixing method commonly used in existing dry electrode manufacturing technologies is insufficient to break the agglomeration structure of VGCF. This results in VGCF maintaining its agglomeration structure and being difficult to distribute evenly in the electrode mixture, thus limiting the effect of VGCF on improving the cohesive force of the electrode sheet.

[0044] Meanwhile, due to its high chemical stability, mechanical stability, and heat resistance, PTFE (Polytetrafluoroethylene) is commonly used as a binder in existing dry electrode manufacturing technologies. During mixing and rolling processes, PTFE can form fibrils under shear force to generate bonding strength. Therefore, to ensure the final production of self-supporting dry electrode sheets, it is necessary to ensure that PTFE is fiberized at the appropriate time. However, the shear force provided by the mechanical mixing method commonly used in existing dry electrode manufacturing technologies may cause PTFE to fiberize prematurely. Premature fiberization of PTFE will hinder its uniform distribution in the electrode mixture.

[0045] Based on this technical problem, the inventors discovered that using an acoustic resonance mixing method with high mixing intensity can effectively break down the agglomeration structure of VGCF. At the same time, there are no mechanical rotating parts such as mechanical rotating blades inside the acoustic resonance device. This not only ensures that the shear force on PTFE is minimal, but also ensures that the temperature rise of PTFE is small. Therefore, the minimal shear force can also prevent PTFE from prematurely becoming fibrous. Thus, by using an acoustic resonance mixing method, it is possible to ensure that VGCF and PTFE are uniformly distributed in the electrode mixture, ensuring that the final manufactured electrode sheet has high cohesion.

[0046] The above is the core idea of ​​this application. The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0047] Figure 3 This is a schematic flowchart illustrating an electrode sheet manufacturing method provided in an embodiment of this application. In one exemplary embodiment, such as... Figure 3 As shown, an electrode sheet manufacturing method is provided. Taking an electrode sheet manufacturing system including an acoustic resonance device, a fiberization treatment device, and a rolling device as an example, the method includes steps 302 to 310. Wherein:

[0048] Step 302: The electrode active material and VGCF are mixed using an acoustic resonance device to obtain a first premix.

[0049] Among them, the acoustic resonance device refers to a device that, based on the principle of resonance amplification, drives the mixing container to generate synchronous resonance by emitting low-frequency sound waves that match the natural frequency of the mixing container and the materials inside the mixing container. This causes the materials to generate three-dimensional, intense macroscopic convection and microscopic turbulence inside the mixing container. Based on this, the materials can generate three-dimensional macroscopic convection and microscopic turbulence by means of vibration inertial force without the contact of mechanical stirring parts, thereby achieving efficient and uniform mixing of materials inside the mixing container.

[0050] In a straightforward manner, the mixing container is fixedly mounted on the vibration platform of the acoustic resonance device, which drives the mixing container to generate synchronous resonance.

[0051] The acoustic resonance device can detect and determine the frequency of low-frequency sound waves that matches the natural frequency of the materials inside the mixing container based on the material conditions inside the mixing container. The low-frequency sound waves of this specific frequency can maximize the acoustic resonance vibration effect, that is, it can make the vibration state of the mixing container and the vibration state of the materials inside the mixing container fully superimposed, rather than canceling each other out.

[0052] Electrode active materials are materials that can participate in redox reactions to store and release charge during the electrochemical energy conversion process of a battery. Electrode active materials typically possess high electrochemical activity, enabling them to undergo reversible chemical reactions with ions in the electrolyte to achieve the conversion between electrical and chemical energy.

[0053] As is easily understood, the first premix is ​​a mixture in which electrode active material and VGCF are uniformly distributed.

[0054] In one exemplary embodiment, the electrode active material is a positive electrode active material or a negative electrode active material;

[0055] The positive electrode active material is at least one of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, lithium manganese oxide, and lithium cobalt oxide;

[0056] The negative electrode active material is at least one of natural graphite, synthetic graphite, hard carbon, soft carbon, activated carbon, silicon, silicon oxide, silicon carbide, tin, tin oxide, and lithium titanate.

[0057] For example, Figure 4 This application provides a schematic diagram of the structure of VGCF after being mixed with graphite material through a first acoustic resonance under an electron microscope, in conjunction with... Figure 1 , Figure 2 and Figure 4 It can be seen that mechanical mixing is difficult to break the agglomeration structure of VGCF, while the acoustic resonance mixing method used in this embodiment can fully break the agglomeration structure of VGCF, so that VGCF can be more fully and evenly distributed on the surface of graphite material. This can also be understood as VGCF being more fully and evenly distributed in the first premix, thereby significantly improving the cohesion of the finally manufactured electrode sheet.

[0058] Step 304: The first premix and PTFE are mixed using an acoustic resonance device to obtain a second premix; the mixing intensity of the first acoustic resonance mixture is greater than that of the second acoustic resonance mixture.

[0059] PTFE refers to a high-performance fluoropolymer material, which is also a semi-crystalline polymer. PTFE has excellent chemical stability, high temperature resistance, corrosion resistance, low coefficient of friction, and good electrical insulation properties. After forming a fibrous structure, it can generate excellent bonding strength.

[0060] As is easily understood, the second premix is ​​a mixture in which electrode active material, VGCF and PTFE are uniformly distributed.

[0061] The mixing intensity of acoustic resonance mixing refers to the strength required to drive the mixing of materials within the mixing container during the acoustic resonance mixing process. Simply put, the greater the mixing intensity of acoustic resonance mixing, the higher the homogeneity of the materials within the mixing container.

[0062] Optionally, the mixing intensity of acoustic resonance mixing can be determined by at least one of acoustic resonance mixing acceleration and mixing time.

[0063] The mixing acceleration of acoustic resonance mixing refers to the inertial acceleration obtained by the mixing container and its internal materials when they vibrate under the driving action of low-frequency sound waves in an acoustic resonance state.

[0064] The mixing time of acoustic resonance mixing refers to the duration of the acoustic resonance state.

[0065] The mixing intensity of the first acoustic resonance mixture being greater than that of the second acoustic resonance mixture can mean that the mixing acceleration of the first acoustic resonance mixture is greater than that of the second acoustic resonance mixture.

[0066] Since VGCF has an agglomerate structure, the agglomerate structure of VGCF can be fully broken down by using an acoustic resonance device to perform a first acoustic resonance mixing with a large mixing intensity, so as to ensure that VGCF can be uniformly distributed in the electrode mixture.

[0067] Since there is no mechanical stirring component in contact with the material during the acoustic resonance mixing process, the shear force exerted by the mixing container on the internal material is extremely small, whether it is the first acoustic resonance mixing, the second acoustic resonance mixing, or the third acoustic resonance mixing mentioned below. Based on this, the temperature rise of the internal material is also extremely small. Therefore, it is beneficial to avoid the situation where PTFE is affected by high temperature or high shear force and forms a fibrous structure in advance, which would make it difficult for PTFE to be evenly distributed in the electrode mixture and thus unable to exert a strong bonding force.

[0068] Because the PTFE in this embodiment can achieve more uniform mixing under the action of the acoustic resonance device, the mass percentage of PTFE in the electrode mixture can be further reduced compared to existing dry electrode technology. For example, the mass percentage of PTFE in existing dry electrode technology is approximately 2% to 5%, while the mass percentage of PTFE in this embodiment can be reduced to below 2%. With reasonable process control, it can even be further reduced to below 1%. It can be seen that by performing a second acoustic resonance mixing of the first premix and PTFE using the acoustic resonance device, not only can the manufacturing cost of the electrode sheet be reduced, but the degree of PTFE's obstruction to ion conduction can also be reduced, thereby reducing the internal resistance of the lithium-ion battery finally manufactured based on the electrode sheet.

[0069] It should be noted that although the shear forces generated during the first and second acoustic resonance mixing processes are very small, the mixing intensity of the first acoustic resonance mixing is greater than that of the second acoustic resonance mixing. Therefore, the shear forces generated during the first acoustic resonance mixing process are inevitably greater than those generated during the second acoustic resonance mixing process. Thus, in order to avoid the large mixing intensity causing PTFE to form a fibrous structure in advance and making it difficult to distribute evenly in the second premix, the execution order between steps 302 and 304 cannot be changed. That is to say, the mixing intensity should be from high to low to ensure that the PTFE is as much as possible affected by shear forces before obtaining the second premix.

[0070] In one exemplary embodiment, the electrode active material has a mass percentage of 80% to 99% in the second premix, and the PTFE has a mass percentage of 0.1% to 2% in the second premix.

[0071] Step 306: The second premix is ​​subjected to fiberization treatment using a fiberization treatment device to obtain an electrode mixture.

[0072] The fiberization treatment device refers to a device that can provide controllable mechanical shear force to the second premix so that the PTFE in the second premix can form a fiber structure.

[0073] Alternatively, the fibrous treatment apparatus may be a high-speed shear mixer, a twin-screw extruder, an air jet mill, a kneading extruder, or other apparatus capable of forming a fibrous structure from PTFE.

[0074] It is easy to understand that the electrode mixture is a mixture in which electrode active material, VGCF and PTFE are uniformly distributed, and the PTFE therein has formed a fibrous structure.

[0075] Step 308: The electrode mixture is calendered using a rolling device to obtain an electrode film.

[0076] Among them, the rolling device refers to a device that includes multiple pairs of rotating rollers to apply rolling pressure to the electrode mixture particles, so that the electrode mixture particles are compressed and stretched to be shaped into an electrode film during the process of passing through multiple pairs of rollers.

[0077] Calendering is a processing method that uses a rolling device to repeatedly roll electrode mixture particles to shape them into an electrode film.

[0078] An electrode film is a film used as the positive or negative electrode portion of an electrode sheet.

[0079] Step 310: The electrode film and the current collector are thermally combined using a roller pressing device to obtain an electrode sheet.

[0080] Among them, the current collector is a material used to collect and conduct current to ensure that the active material in the electrode membrane can effectively participate in the electrochemical reaction. At the same time, the current collector can also provide mechanical support for the electrode membrane.

[0081] Thermal bonding refers to a processing method that involves heating the electrode film and the current collector while applying pressure, thereby enabling the electrode film and the current collector to bond tightly together to obtain an electrode sheet.

[0082] It is readily understood that the electrode sheet in this embodiment is either a positive electrode sheet or a negative electrode sheet. Furthermore, based on the electrode sheet obtained in this embodiment, an energy storage device can be obtained by combining it with an electrode sheet, a separator, an electrolyte, and other materials having the opposite polarity to the electrode sheet obtained in this embodiment. For example, the energy storage device can be a lithium-ion battery.

[0083] In an exemplary embodiment, the current collector is any one of the following: aluminum foil coated with a conductive carbon layer, copper foil coated with a conductive carbon layer, nickel foil coated with a conductive carbon layer, stainless steel foil coated with a conductive carbon layer, porous aluminum foil coated with a conductive carbon layer, porous copper foil coated with a conductive carbon layer, porous nickel foil coated with a conductive carbon layer, porous stainless steel foil coated with a conductive carbon layer, and etched aluminum foil coated with a conductive carbon layer.

[0084] In an exemplary embodiment, the electrode sheet manufacturing method provided in this application uses graphite as the electrode active material, meaning the electrode sheet manufactured by this method is a graphite electrode sheet. Based on this, Figure 5 This is a comparative schematic diagram illustrating the cohesive strength enhancement effect of a graphite electrode sheet manufactured by an electrode sheet manufacturing method according to an embodiment of this application. Figure 5 As shown, after a battery is further manufactured using the graphite electrode sheet produced according to the embodiments of this application, a mechanical tensile test is conducted on the battery including the graphite electrode sheet and the battery manufactured using the existing dry electrode technology (which uses the same graphite material but does not add VGCF during the manufacturing process). The test results show that the cohesive force of the battery corresponding to the embodiments of this application is about 10 N / m, while the cohesive force of the battery corresponding to the existing dry electrode technology is about 6 N / m. It can be seen that because VGCF is added to the electrode sheet produced according to the embodiments of this application, a significant improvement in cohesive force is achieved compared to the battery without VGCF corresponding to the existing dry electrode technology.

[0085] It should be noted that, Figure 1 , Figure 2 , Figure 4 as well as Figure 5 The graphite materials mentioned in the respective embodiments are all the same graphite material, and the manufacturer of this same graphite material is BTR.

[0086] In the above-mentioned electrode sheet manufacturing method, the electrode active material and VGCF are mixed using an acoustic resonance device based on a large mixing intensity. This ensures that the aggregated structure of VGCF is fully broken down. After the manufacturing process steps of first acoustic resonance mixing, second acoustic resonance mixing, and fiberization treatment, the electrode active material, VGCF, and PTFE can be distributed in the electrode mixture with high uniformity. This ensures that the electrode sheet manufactured based on the electrode mixture has high cohesion. At the same time, compared with the mechanical mixing method used in traditional dry electrode technology, PTFE can be more uniformly distributed in the electrode mixture under the action of acoustic resonance mixing. Therefore, the mass percentage of PTFE in the electrode mixture can be appropriately reduced, thereby reducing the manufacturing cost of the electrode sheet.

[0087] In an exemplary embodiment, the second premix is ​​obtained by second acoustic resonance mixing of the first premix and PTFE using an acoustic resonance device, comprising:

[0088] The first premix and the conductive carbon material are mixed by a third acoustic resonance device to obtain a third premix.

[0089] The third premix and PTFE are mixed using an acoustic resonance device to obtain a second premix; the mixing intensity of the first acoustic resonance mixture is greater than that of the third acoustic resonance mixture, and the mixing intensity of the third acoustic resonance mixture is greater than that of the second acoustic resonance mixture.

[0090] The conductive carbon material can be at least one of conductive carbon black, acetylene black, and Ketjen black.

[0091] Both VGCF and conductive carbon materials exist as conductive agents in the subsequent electrode mixture. Based on this, VGCF, which is mainly used to improve the cohesion of the finally manufactured electrode sheet, can be understood as the main conductive agent, while conductive carbon materials can be understood as auxiliary conductive agents.

[0092] Conductive carbon black has a small specific surface area and a relatively small amount of PTFE adsorption. Therefore, using conductive carbon black as an auxiliary conductive agent can fully utilize the binding force of PTFE in forming a fibrous structure. Similarly, acetylene black has a moderate specific surface area and a moderate amount of PTFE adsorption, while Ketjen black has a large specific surface area and a large amount of PTFE adsorption. Therefore, using conductive carbon black as an auxiliary conductive agent to obtain a third premix can ensure that the cohesive force of the final manufactured electrode sheet is high.

[0093] Under the same mass percentage, in terms of improving the conductivity of the final manufactured electrode sheet, Ketjen black is superior to acetylene black, and acetylene black is superior to conductive carbon black; in terms of improving the cohesion of the final manufactured electrode sheet, conductive carbon black is superior to acetylene black, and acetylene black is superior to Ketjen black.

[0094] Preferably, in order to maximize the cohesion of the final manufactured electrode sheet and at the same time minimize the manufacturing cost of the electrode sheet, conductive carbon black can be selected as the conductive carbon material.

[0095] When the conductive carbon black and the first premix are mixed in a third acoustic resonance to obtain the third premix, VGCF, as the main conductive agent, exhibits a one-dimensional linear structure, while the conductive carbon black, as the auxiliary conductive agent, exhibits a zero-dimensional point structure. Based on this, VGCF can build a continuous conductive skeleton inside the electrode sheet and play a fiber reinforcement role, while the conductive carbon black can effectively fill the gap between VGCF and the electrode active material. Therefore, by using VGCF and conductive carbon black in combination, the conductivity and cohesion of the electrode sheet can be significantly enhanced in a synergistic way.

[0096] Although both VGCF and conductive carbon materials have agglomerated structures, the intermolecular van der Waals forces between fibers in VGCF are stronger. Therefore, the agglomerated structure of VGCF is more robust than that of conductive carbon materials. Consequently, VGCF needs to be mixed with a higher mixing intensity for the first acoustic resonance mixing.

[0097] Optionally, the mixing intensity of the first acoustic resonance mixture is greater than the mixing intensity of the third acoustic resonance mixture, and the mixing intensity of the third acoustic resonance mixture is greater than the mixing intensity of the second acoustic resonance mixture. This can be achieved by the mixing acceleration of the first acoustic resonance mixture being greater than the mixing acceleration of the third acoustic resonance mixture, and the mixing acceleration of the third acoustic resonance mixture being greater than the mixing acceleration of the second acoustic resonance mixture.

[0098] This can be understood as follows: the first acoustic resonance mixture is a high-intensity acoustic resonance mixture, the third acoustic resonance mixture is a medium-intensity acoustic resonance mixture, and the second acoustic resonance mixture is a low-intensity acoustic resonance mixture.

[0099] As is readily understood, the third premix is ​​a mixture in which the electrode active material, VGCF, conductive carbon material, and PTFE are uniformly distributed. If the conductive carbon material is conductive carbon black, then the third premix is ​​a mixture in which the electrode active material, VGCF, conductive carbon black, and PTFE are uniformly distributed.

[0100] It should be noted that, similarly, since the mixing intensity of the third acoustic resonance mixing is greater than that of the second acoustic resonance mixing, the shear force generated during the third acoustic resonance mixing process will inevitably be greater than that generated during the second acoustic resonance mixing process. Therefore, in order to avoid the greater mixing intensity causing PTFE to form a fibrous structure in advance and making it difficult to distribute evenly in the second premix, it is necessary to first use an acoustic resonance device to mix the first premix and the conductive carbon material in the third acoustic resonance to obtain the third premix, and then use an acoustic resonance device to mix the third premix and PTFE in the second acoustic resonance to ensure that PTFE can be evenly distributed in the second premix.

[0101] In one exemplary embodiment, the mass percentage of VGCF in the second premix is ​​0.1% to 5%, and the mass percentage of conductive carbon material in the second premix is ​​0.5% to 5%.

[0102] In this embodiment, a conductive carbon material as an auxiliary conductive agent is introduced into a first premix including VGCF. A third premix is ​​obtained by mixing with a third acoustic resonance at a medium mixing intensity. Then, the third premix and PTFE are mixed with a second acoustic resonance at a low mixing intensity to obtain a second premix for subsequent fiberization treatment. Based on this, since PTFE is the last material introduced for mixing, it is possible to ensure that the electrode active material, VGCF, conductive carbon material and PTFE can be uniformly distributed in the finally manufactured electrode sheet without premature fiberization of PTFE. This ensures that the finally manufactured electrode sheet not only has high cohesion but also high reliability.

[0103] In an exemplary embodiment, the mixing acceleration of the first acoustic resonance mixture is 70g~100g, the mixing acceleration of the second acoustic resonance mixture is 10g~40g, and the mixing acceleration of the third acoustic resonance mixture is 40g~70g.

[0104] In this embodiment, the first acoustic resonance mixing can break the agglomeration structure of VGCF with a high mixing acceleration, ensuring that VGCF can be uniformly distributed in the first premix; the second acoustic resonance mixing can break the agglomeration structure of the conductive carbon material with a medium mixing acceleration, while avoiding damage to the already dispersed VGCF; the third acoustic resonance mixing can make PTFE uniformly distributed in the second premix with a low mixing acceleration. Thus, based on the acoustic resonance mixing with three mixing intensity levels from high to low, it can be ensured that the electrode active material, VGCF, conductive carbon material and PTFE are distributed in the second premix with high uniformity, ensuring that the electrode sheet subsequently manufactured has high cohesion and reliability.

[0105] In an exemplary embodiment, the mixing time for the first acoustic resonance mixture is 5 min to 30 min, the mixing time for the second acoustic resonance mixture is 3 min to 10 min, and the mixing time for the third acoustic resonance mixture is 5 min to 15 min.

[0106] In this embodiment, the mixing time of the first acoustic resonance mixing is relatively long, which can ensure that the agglomeration structure of VGCF can be fully broken; the mixing time of the second acoustic resonance mixing is moderate, which can ensure that the agglomeration structure of the conductive carbon material can be fully broken; the mixing time of the third acoustic resonance mixing is relatively short, which can ensure that PTFE is uniformly distributed in the second premix, while also avoiding the reduction of electrode sheet manufacturing efficiency due to excessive mixing time.

[0107] In one exemplary embodiment, the electrode active material has a mass percentage of 80% to 99% in the second premix, the PTFE has a mass percentage of 0.1% to 2% in the second premix, and the sum of the mass percentages of VGCF and conductive carbon material in the second premix is ​​0.6% to 10%.

[0108] In an exemplary embodiment, the above-mentioned calendering of the electrode mixture using a rolling device to obtain an electrode film includes:

[0109] The electrode mixture is calendered using a rolling device at a first calendering temperature to obtain an electrode film;

[0110] The above-mentioned method of thermally bonding the electrode film and the current collector using a rolling device to obtain the electrode sheet includes:

[0111] The electrode sheet is obtained by thermally bonding the electrode film and the current collector at a second calendering temperature using a rolling device.

[0112] The first rolling temperature is 50℃~250℃, and the second rolling temperature is 100℃~250℃.

[0113] The first calendering temperature is 50℃~250℃, which ensures that the electrode mixture can undergo a certain degree of deformation under appropriate temperature conditions to form an electrode film with high flatness. At the same time, it avoids calendering temperature that is too low to improve calendering efficiency, and avoids calendering temperature that is too high to prevent the material properties of the electrode mixture from changing under high temperature.

[0114] The second calendering temperature refers to the temperature conditions experienced by the electrode film during the multi-roll calendering process, when it is tightly bonded to the current collector in the rolling device to form an electrode sheet. In order for the PTFE in the electrode film to flow better and fill the tiny gaps between the electrode film and the current collector, so as to achieve a strong bond between the electrode film and the current collector, the second calendering temperature in the thermal composite process to obtain the electrode sheet needs to be higher than the first calendering temperature in the calendering process to obtain the electrode film.

[0115] In an exemplary embodiment, the above-mentioned calendering of the electrode mixture at a first calendering temperature using a rolling device to obtain an electrode film includes:

[0116] The electrode mixture is calendered by a rolling device at a first calendering temperature and a preset number of calendering cycles to obtain an electrode film.

[0117] The preset number of rolling cycles is greater than 1.

[0118] Optionally, the preset number of calendering cycles can be 2 to 10, and the preset number of calendering cycles corresponds to the number of rollers in the rolling device.

[0119] The preset number of calendering cycles is 2 to 10, which can ensure that the calendered electrode film has high uniformity and flatness. At the same time, it can avoid the problem of low manufacturing efficiency of the electrode film due to excessive calendering cycles.

[0120] For example, Figure 6 This is a schematic diagram of the structure of a roller pressing device provided in an embodiment of this application, as shown below. Figure 6 As shown, the electrode mixture 602 is calendered by the rolling device 60 at a first calendering temperature and a preset number of calendering cycles to obtain an electrode film 604. The electrode film 604 and the current collector 606 are then thermally bonded by the rolling device 60 at a second calendering temperature to obtain an electrode sheet 608.

[0121] Figure 7 A schematic flowchart of another electrode sheet manufacturing method provided in this application embodiment is shown. In an exemplary embodiment, such as... Figure 7As shown, the specific process flow of the electrode sheet manufacturing method provided in this application embodiment is as follows: First, the electrode active material and VGCF are placed inside the mixing container of an acoustic resonance device, and the electrode active material and VGCF are mixed with a high mixing intensity using the acoustic resonance device to obtain a first premix; then, conductive carbon material is added inside the mixing container, and the first premix and conductive carbon material are mixed with a medium mixing intensity using the acoustic resonance device to obtain a third premix; next, PTFE is added inside the mixing container, and the first premix and PTFE are mixed with a low mixing intensity using the acoustic resonance device to obtain a second premix. Further, the second premix is ​​fiberized using a fiberization treatment device to obtain an electrode mixture, and then the electrode mixture is calendered using a rolling device to obtain an electrode film. Finally, the electrode film and current collector are thermally bonded using a rolling device to obtain an electrode sheet. It should be noted that after obtaining the electrode sheet, a conventional battery assembly method can be used to obtain an energy storage device such as a lithium-ion battery, therefore, the specific process flow of battery assembly will not be described in detail here.

[0122] Figure 8 The structural block diagram of an electrode sheet manufacturing system provided in this application embodiment, in an exemplary embodiment, is as follows: Figure 8 As shown, the electrode sheet manufacturing system 80 includes an acoustic resonance device 802, a fiberization treatment device 804, and a rolling device 806. The process flow for implementing the electrode sheet manufacturing method provided in this application based on the electrode sheet manufacturing system 80 is as follows:

[0123] (1) The electrode active material and VGCF are placed inside the mixing container of the acoustic resonance device 802, and the electrode active material and VGCF are mixed by the acoustic resonance device 802 to obtain the first premix.

[0124] The conductive carbon material is added into the mixing container, and the first premix and the conductive carbon material are mixed by the third acoustic resonance device 802 to obtain the third premix.

[0125] PTFE is added into the mixing container, and the third premix and PTFE are mixed by a second acoustic resonance device 802 to obtain the second premix.

[0126] Among them, the mixing intensity of the first acoustic resonance mixture is greater than that of the third acoustic resonance mixture, and the mixing intensity of the third acoustic resonance mixture is greater than that of the second acoustic resonance mixture.

[0127] (2) The second premix is ​​transferred from the mixing container of the acoustic resonance device 802 to the fiberization treatment device 804, and the second premix is ​​fiberized by the fiberization treatment device 804 to obtain the electrode mixture.

[0128] (3) The electrode mixture is transferred from the fiberization treatment device 804 to the rolling device 806, and the electrode mixture is rolled by the rolling device 806 according to the first rolling temperature and the preset rolling number to obtain the electrode film;

[0129] The electrode sheet is obtained by thermally bonding the electrode film and the current collector using the rolling device 806 at the second calendering temperature.

[0130] In this embodiment, firstly, by introducing VGCF into the electrode mixture, the cohesiveness of the final manufactured electrode sheet can be improved; secondly, by employing acoustic resonance mixing with three mixing intensity levels from high to low, the agglomeration structure of VGCF can be fully broken down, thereby ensuring that the electrode active material, VGCF, conductive carbon material, and PTFE are distributed in the second premix with high uniformity, ensuring that the final manufactured electrode sheet not only has high cohesiveness but also high reliability; thirdly, compared to the mechanical mixing method used in traditional dry electrode technology, PTFE can be more uniformly distributed in the electrode mixture under the action of acoustic resonance mixing, thus allowing the mass percentage of PTFE in the electrode mixture to be appropriately reduced, thereby reducing the manufacturing cost of the electrode sheet.

[0131] In one exemplary embodiment, an electrode sheet is also provided, which is manufactured using the steps of any of the electrode sheet manufacturing methods described in the above embodiments.

[0132] In one exemplary embodiment, an energy storage device is also provided, including the electrode sheet described above.

[0133] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0134] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for manufacturing an electrode sheet, characterized in that, The method includes: The electrode active material and VGCF are mixed using an acoustic resonance device to obtain a first premix. The first premix and PTFE are mixed using the acoustic resonance device to obtain a second premix; the mixing intensity of the first acoustic resonance mixture is greater than that of the second acoustic resonance mixture. The second premix is ​​subjected to fiberization treatment using a fiberization treatment device to obtain an electrode mixture; The electrode mixture is calendered using a rolling device to obtain an electrode film; The electrode film and the current collector are thermally combined using the roller pressing device to obtain an electrode sheet.

2. The method according to claim 1, characterized in that, The process of mixing the first premix and PTFE using the acoustic resonance device to obtain the second premix includes: The first premix and the conductive carbon material are mixed by the acoustic resonance device to obtain a third premix. The third premix and PTFE are mixed using the acoustic resonance device to obtain a second premix; the mixing intensity of the first acoustic resonance mixture is greater than that of the third acoustic resonance mixture, and the mixing intensity of the third acoustic resonance mixture is greater than that of the second acoustic resonance mixture.

3. The method according to claim 2, characterized in that, The mixing acceleration of the first acoustic resonance mixture is 70g~100g, the mixing acceleration of the second acoustic resonance mixture is 10g~40g, and the mixing acceleration of the third acoustic resonance mixture is 40g~70g.

4. The method according to claim 2, characterized in that, The mixing time for the first acoustic resonance mixture is 5 min to 30 min, the mixing time for the second acoustic resonance mixture is 3 min to 10 min, and the mixing time for the third acoustic resonance mixture is 5 min to 15 min.

5. The method according to claim 2, characterized in that, The VGCF in the second premix has a mass percentage of 0.1% to 5%, and the conductive carbon material in the second premix has a mass percentage of 0.5% to 5%.

6. The method according to claim 5, characterized in that, The electrode active material has a mass percentage of 80% to 99% in the second premix, and the PTFE has a mass percentage of 0.1% to 2% in the second premix.

7. The method according to claim 1, characterized in that, The step of calendering the electrode mixture using a rolling device to obtain an electrode film includes: The electrode mixture is calendered at a first calendering temperature using a rolling device to obtain the electrode film. The process of thermally bonding the electrode film and the current collector using the roller pressing device to obtain the electrode sheet includes: The electrode sheet is obtained by thermally bonding the electrode film and the current collector at a second calendering temperature using the rolling device. The first rolling temperature is 50℃~250℃, and the second rolling temperature is 100℃~250℃.

8. The method according to claim 1, characterized in that, The electrode active material is a positive electrode active material or a negative electrode active material; The positive electrode active material is at least one of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, lithium manganese oxide, and lithium cobalt oxide. The negative electrode active material is at least one of natural graphite, synthetic graphite, hard carbon, soft carbon, activated carbon, silicon, silicon oxide, silicon carbide, tin, tin oxide, and lithium titanate.

9. The method according to claim 1, characterized in that, The current collector is any one of the following: aluminum foil coated with a conductive carbon layer, copper foil coated with a conductive carbon layer, nickel foil coated with a conductive carbon layer, stainless steel foil coated with a conductive carbon layer, porous aluminum foil coated with a conductive carbon layer, porous copper foil coated with a conductive carbon layer, porous nickel foil coated with a conductive carbon layer, porous stainless steel foil coated with a conductive carbon layer, and corroded aluminum foil coated with a conductive carbon layer.

10. An electrode sheet, characterized in that, The electrode sheet is manufactured using the electrode sheet manufacturing method as described in any one of claims 1 to 9.

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