Electrode preparation method and preparation system, electrode and battery

Abstract

The invention provides an electrode preparation method and system, an electrode and a battery. The electrode preparation method comprises the following steps: freezing and embrittling a binder; the binding agent is smashed into binding agent powder; mixing the binder powder with an active substance to form a mixed material; the mixed material is subjected to pre-fibration, and a pre-fibration material is formed; carrying out roll forming on the pre-fibration material to form an electrode diaphragm; and compounding the electrode diaphragm with a current collector to form the electrode. According to the electrode preparation method disclosed by the invention, the adhesive is frozen and embrittled, so that the toughness of the adhesive is remarkably reduced, and the brittleness of the adhesive is increased, and therefore, the adhesive can be uniformly crushed into fine particles, the mixing uniformity and the pre-fibration degree of the adhesive and other materials can be improved, and the uniformity of the thickness of the electrode is further effectively improved; and moreover, high-speed film formation of the electrode diaphragm is facilitated, the production efficiency of the electrode can be effectively improved, and meanwhile, the uniformity of electrode resistance can be ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode production, and more specifically, to an electrode preparation method, a preparation system, an electrode, and a battery. Background Art

[0002] Currently, commercially available dispersed polytetrafluoroethylene (PTFE) and its copolymers are usually aggregates with a particle size of 300 microns to 1000 microns. There is a strong van der Waals force between their molecules, resulting in the inability to break up PTFE into fine particles during the mixing process, making it difficult for PTFE to be uniformly dispersed with the main electrode material or other additives. Uneven dispersion of PTFE (i.e., the binder) will cause the PTFE aggregates to not be fully fibrillated, reducing the utilization rate of PTFE, resulting in poor thickness uniformity of the electrode membrane and membrane rupture during the high-speed film-forming process, affecting the preparation efficiency of the dry electrode. In addition, the binder is a poor conductor of electrons and ions, and uneven dispersion will affect the resistance of the electrode, thus affecting the rate performance of the battery. Summary of the Invention

[0003] The present invention provides a new technical solution for an electrode preparation method, which can at least solve the problems of uneven dispersion of the binder and insufficient fibrillation of the binder during the preparation of existing electrodes.

[0004] The present invention also provides a new technical solution for an electrode preparation system.

[0005] The present invention also provides a new technical solution for an electrode.

[0006] The present invention also provides a new technical solution for a battery.

[0007] According to a first aspect of the present invention, there is provided an electrode preparation method, including: freezing and embrittling a binder; pulverizing the binder into binder powder; mixing the binder powder with an active material to form a mixed material; pre-fibrillating the mixed material to form a pre-fibrillated material; roll-pressing the pre-fibrillated material into an electrode membrane; and laminating the electrode membrane with a current collector to form an electrode.

[0008] Optionally, the particle size of the binder powder is 100 nm to 100000 nm.

[0009] Optionally, the binder is configured to be polytetrafluoroethylene or its copolymer.

[0010] Optionally, the binder is frozen to -10°C to -179°C for embrittlement.

[0011] Optionally, the binder is frozen to -50°C to -100°C for embrittlement.

[0012] Optionally, the refrigerant used to freeze the binder is dry ice or liquid nitrogen.

[0013] Optionally, the method of pulverizing the binder into binder powder is jet milling.

[0014] Optionally, the binder powder is mixed with the active material at a temperature below the crystallization temperature of the binder to form a mixed material; and / or, the mixed material is pre-fibrillated at a temperature higher than the crystallization temperature of the binder to form a pre-fibrillated material.

[0015] Optionally, in the step of mixing the binder powder with the active material, the mixing temperature is controlled to be 0°C to 19°C; and / or, in the step of pre-fibrillating the mixed material to form a pre-fibrillated material, the pre-fibrillation temperature is controlled to be 60°C to 150°C.

[0016] Optionally, in the step of roll-pressing the pre-fibrillated material into an electrode diaphragm, the temperature of the roll used is 20°C to 150°C.

[0017] Optionally, the electrode preparation method further includes: granulating the pre-fibrillated material before preparing the electrode diaphragm.

[0018] According to a second aspect of the present invention, there is provided an electrode preparation system, including: a freezing device for freezing the binder to a brittle temperature; a pulverizing device for pulverizing the binder into binder powder; a mixing device for mixing the binder powder with the active material to form a mixed material; a pre-fibrillating device for pre-fibrillating the mixed material to form a pre-fibrillated material; a film-forming device for preparing the pre-fibrillated material into an electrode diaphragm with a preset thickness; and a composite device for composite the electrode diaphragm with a current collector to form an electrode.

[0019] Optionally, the electrode preparation system further includes: a granulating device for granulating the pre-fibrillated material before preparing the electrode diaphragm.

[0020] Optionally, the pulverizing device is configured as a jet milling device or a mechanical pulverizing device.

[0021] According to a third aspect of the present invention, there is provided an electrode, which is made by the electrode preparation method described in any one of the above or the electrode preparation system described in any one of the above.

[0022] According to a fourth aspect of the present invention, there is provided a battery, including the above electrode.

[0023] According to the method for preparing an electrode of the present invention, by freeze-brittle the binder, the toughness of the binder is significantly decreased and the brittleness is increased, so that the binder can be uniformly crushed into fine particles, which can improve the uniformity of mixing of the binder and other materials and the degree of pre-fibrillation, and further effectively improve the uniformity of the electrode thickness. Moreover, it is beneficial to the high-speed film formation of the electrode membrane, which can effectively improve the production efficiency of the electrode, and at the same time ensure the uniformity of the electrode resistance. In addition, by uniformly mixing the binder and other materials, the uniformity of the electrode resistance can be ensured, thereby ensuring the rate performance of the battery, and the amount of the binder can be reduced, and further the resistance of the electrode can be improved and the battery performance can be enhanced.

[0024] Other features and advantages of the present invention will become clear from the following detailed description of the exemplary embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings incorporated in and forming a part of this specification illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0026] Figure 1 is a dispersion effect diagram of the binder in the mixed materials in the prior art;

[0027] Figure 2 is a dispersion effect diagram of the binder in the mixed materials according to an embodiment provided by the present invention;

[0028] Figure 3 is a flowchart of a method for preparing an electrode according to an embodiment provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Now, various exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and values set forth in these embodiments do not limit the scope of the present invention.

[0030] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present invention, its application, or its use.

[0031] Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be considered as part of the specification.

[0032] In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values.

[0033] It should be noted that like reference numerals and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof in subsequent figures is not required.

[0034] First, a method for preparing an electrode according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings.

[0035] As Figure 3 shown, the method for preparing an electrode according to an embodiment of the present invention includes: S100 to S500.

[0036] S100. Freeze - embrittle the binder;

[0037] Specifically, before pulverizing the binder, the binder can be frozen using a refrigerant. As the temperature decreases, the toughness of the binder significantly decreases while the brittleness increases, thereby achieving embrittlement. This makes the binder easier to break and pulverize, and thus can be more efficiently and uniformly pulverized into smaller particles.

[0038] S200. Pulverize the binder into binder powder;

[0039] In detail, after the binder is freeze - embrittled, the embrittled binder is conveyed to a pulverizing device for pulverization. The pulverizing device can pulverize the embrittled binder into binder powder, and the pulverizing device can be a mechanical pulverizer or a pneumatic pulverizer.

[0040] S300. Mix the binder powder with the active material to form a mixed material;

[0041] Specifically, after the binder is pulverized, the binder powder and the active material are mixed evenly under predetermined conditions, and the required mixed material can be obtained after mixing evenly.

[0042] S400. Pre - fibrillate the mixed material to form a pre - fibrillated material;

[0043] That is to say, after the mixed material is formed, a pair - roll machine or an open mill can be used to perform pre - fibrillation treatment on the mixed material to form a fibrillated mixed material, that is, a pre - fibrillated material. This can effectively improve the mechanical strength of the subsequent formed electrode film and is beneficial to increasing the film - forming speed.

[0044] S500. Roll - press the pre - fibrillated material into an electrode film;

[0045] In detail, after the pre - fibrillated material is formed, a film - forming device can be used to roll - press the pre - fibrillated material into an electrode film with a predetermined thickness.

[0046] S600. Composite the electrode film with a current collector to form an electrode.

[0047] Specifically, the current collector has a first side and a second side that are oppositely arranged in its thickness direction. After forming the electrode film, the composite device can be used to composite the electrode film on the first side and the second side of the current collector respectively, so that the electrode films are provided on both sides of the current collector, and the required electrode can be obtained in this way.

[0048] Thus, according to the electrode preparation method provided by this embodiment, by freezing and embrittling the binder, the toughness of the binder is significantly decreased and the brittleness is increased, so that the binder can be uniformly crushed into fine particles, which can improve the uniformity of mixing of the binder and other materials and the degree of pre-fibrillation, and further effectively improve the uniformity of the electrode thickness. Moreover, it is beneficial to the high-speed film formation of the electrode film, which can effectively improve the production efficiency of the electrode, and at the same time, the uniformity of the electrode resistance can be ensured; in addition, by mixing the binder and other materials evenly, the uniformity of the electrode resistance can be ensured, so that the rate performance of the battery can be ensured, and the amount of the binder can be reduced, and further the resistance of the electrode can be improved and the battery performance can be enhanced.

[0049] In some specific embodiments of the present invention, the particle size of the binder powder is 100 nm to 100,000 nm.

[0050] That is to say, after the binder is frozen and embrittled, it can be crushed into binder powder with a particle size of 100 nm to 100,000 nm. For example, the particle size can be 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm and 1000 nm, 5000 nm, 10000 nm, 50000 nm and 100000 nm, etc. In this range, the uniformity of mixing of the binder and other materials and the degree of pre-fibrillation can be ensured.

[0051] According to some specific embodiments of the present invention, the binder is configured as polytetrafluoroethylene or its copolymer.

[0052] In this embodiment, the binder is polytetrafluoroethylene (i.e., PTFE) or a copolymer of polytetrafluoroethylene. PTFE can fibrillate without using a solvent to wrap the material, and then form a film after pressing, which can effectively reduce the manufacturing cost of the electrode, and is not easy to burn, and can effectively improve the safety of the battery.

[0053] In some specific embodiments of the present invention, the binder is frozen to -10 °C to -179 °C for embrittlement.

[0054] Specifically, when the binder is cryogenically treated, the binder can be frozen to a temperature range of -10°C to -179°C. For example, the binder can be frozen to specific temperature points such as -10°C, -30°C, -50°C, -70°C, -90°C, -110°C, -130°C, -150°C, and -179°C. Within this temperature range, the toughness of the binder can be reduced and the binder can be embrittled, so that the binder can be uniformly crushed into fine particles, which can improve the uniformity of the mixture of the binder and other materials, and can also prevent irreversible changes in the internal structure of the binder due to too low temperature, affecting its subsequent performance.

[0055] According to some specific embodiments of the present invention, the binder is frozen to -50°C to -100°C for embrittlement.

[0056] That is to say, if the binder is frozen to a temperature higher than -50°C, it will result in insufficient embrittlement of the binder. Although the binder can be crushed, it is difficult to crush the binder into smaller particles; if the binder is frozen to a temperature lower than -100°C, although the binder can be better embrittled, it will significantly increase the energy consumption, thus greatly increasing the production cost of the electrode. In this embodiment, when the binder is cryogenically treated, the binder can be frozen to a temperature range of -50°C to -100°C. For example, the binder can be frozen to specific temperature points such as -50°C, -55°C, -60°C, -65°C, -75°C, -80°C, -85°C, -95°C, and -100°C. Within this temperature range, the degree of embrittlement of the binder can be ensured, and the binder can be crushed into particles with appropriate particle size; at the same time, this temperature range can avoid excessive energy consumption, thus effectively controlling the production cost of the electrode.

[0057] In some specific embodiments of the present invention, the refrigerant used for freezing the binder is dry ice or liquid nitrogen.

[0058] Specifically, when the binder is cryogenically treated, the freezing device can use dry ice or liquid nitrogen as the refrigerant. For example, when using dry ice as the refrigerant, the flow rate of dry ice is 5 kg / h to 20 kg / h, and when using liquid nitrogen as the refrigerant, the flow rate of liquid nitrogen is 1 kg / h to 10 kg / h, so that the PTFE can be positioned within the temperature range of -10°C to -179°C.

[0059] It should be noted that the flow rate of the refrigerant can be determined according to the specific material of the refrigerant and the required freezing temperature, which will not be elaborated in this embodiment.

[0060] Further, when liquid nitrogen is used as the refrigerant, the binder can be directly placed in a container filled with liquid nitrogen. By virtue of the low-temperature characteristics of liquid nitrogen, the binder can be quickly and fully frozen. Liquid nitrogen not only has a relatively low cost, but also can be in full contact with the binder, thus ensuring the efficiency and uniformity of freezing. Furthermore, it can ensure the uniformity of the crushed binder, and is conducive to quickly freezing the binder to a relatively low temperature, which can ensure the production efficiency of the electrode sheet.

[0061] According to some specific embodiments of the present invention, the method of crushing the binder into binder powder is jet milling.

[0062] That is to say, the binder can be crushed by mechanical crushing and jet milling. In this embodiment, a jet milling device can be used to perform jet milling on the binder. During jet milling, the air flow pressure is greater than 3 bar. Jet milling can crush the binder into finer particles with a narrower particle size distribution, and the particles after jet milling have a relatively regular shape, which can ensure the uniformity of the electrode film, thereby improving the product quality of the electrode.

[0063] In some alternative examples of the present invention, the binder is crushed by a mechanical crusher, and during crushing, the linear velocity of the crusher is greater than 20 m / s.

[0064] In some specific embodiments of the present invention, below the crystallization temperature of the binder, the binder powder is mixed with the active material to form a mixed material.

[0065] Specifically, if the binder powder is mixed with the active material above the crystallization temperature of the binder, it will affect the uniformity of the mixing of the binder powder and the active material. Therefore, in this embodiment, the binder powder and the active material are mixed below the crystallization temperature of the binder, so as to avoid the crystal form transformation of PTFE during the mixing process, thereby ensuring the mixing uniformity of PTFE and further ensuring the thickness uniformity of the electrode film.

[0066] In some alternative examples of the present invention, above the crystallization temperature of the binder, the mixed material is pre-fibrillated to form a pre-fibrillated material.

[0067] Specifically, a pair-roll machine or an open mill is used to pre-fibrillate the mixed material to obtain a fibrillated mixed material. For example, when using an open mill for pre-fibrillation, the pre-fibrillation can be carried out at a temperature higher than the crystallization temperature of the binder. For example, the temperature of the two rotors of the open mill can be controlled within the range of 20°C to 150°C, and the specific temperature points can be 20°C, 40°C, 60°C, 80°C, 100°C, 120°C, 140°C, 150°C, etc. The speed ratio of the two rotors can be set to 1 to 20, for example, 1, 4, 8, 12, 16, 20, etc., and the speed of the first rotor can be controlled to 0.01 m / min to 100 m / min, for example, 0.01 m / min, 20 m / min, 40 m / min, 60 m / min, 80 m / min, 100 m / min, etc. During this process, the crystal form of PTFE will change, and the PTFE molecular chains will stretch and elongate to achieve fibrillation, which can wrap other particles like a spider web to form a uniform and stable mixture, ensuring the product quality of the electrode.

[0068] According to some specific embodiments of the present invention, in the step of mixing the binder powder and the active material, the mixing temperature is controlled to be 0°C to 19°C.

[0069] That is to say, when mixing the binder powder and the active material, the mixing temperature can be controlled to be 0°C to 19°C, for example, specific temperature points such as 0°C, 2°C, 4°C, 6°C, 8°C, 10°C, 12°C, 15°C, 17°C, 19°C, etc. Within this temperature range, even if heat is generated by friction during the mixing of the binder powder and the active material, it is not sufficient to cause the crystal form change of PTFE, so as to ensure the mixing uniformity of PTFE, and further ensure the uniformity of the electrode thickness.

[0070] In some optional examples of the present invention, in the step of pre-fibrillating the mixed material to form a pre-fibrillated material, the pre-fibrillation temperature is controlled to be 60°C to 150°C.

[0071] Specifically, when pre-fibrillating the mixed material, the pre-fibrillation temperature can be controlled to be 60°C to 100°C, for example, specific temperature points such as 60°C, 70°C, 80°C, 90°C, 100°C, 120°C, 150°C, etc., so that the binder can fully undergo crystal form change, which is beneficial for the binder to better wrap its particles and enhance the stability of the mixture.

[0072] In some specific embodiments of the present invention, in the step of roll-pressing the pre-fibrillated material into an electrode membrane, the temperature of the roll used is 20°C to 150°C.

[0073] That is to say, the roller is configured as a hot roller, and during the process of roller pressing the pre-fibrillated material by using the roller, the pre-fibrillated material can be heated by the roller. Specifically, the temperature of the roller can be adjusted to 20°C to 150°C, for example, 20°C, 40°C, 60°C, 80°C, 100°C, 120°C, 140°C, 150°C, etc. Within this temperature range, it can ensure that the pre-fibrillated material has good plasticity during the roller pressing process, making it easier to form during the roller pressing process, and can effectively improve the forming quality of the electrode film.

[0074] Furthermore, when the mixed material is pre-fibrillated, the temperatures of the two rotors of the open mill are set to 60°C to 120°C, for example, 60°C, 70°C, 80°C, 90°C, 110°C, 120°C, etc.; the speed ratio of the two rotors is set to 1.5 to 6, for example, 1.5, 3, 4.5, 6, etc., and the speed of the first rotor is 20 m / min to 70 m / min, for example, 20 m / min, 30 m / min, 50 m / min, 70 m / min, etc.

[0075] In some optional examples of the present invention, before preparing the electrode film, the pre-fibrillated material is granulated.

[0076] Specifically, in order to ensure that the pre-fibrillated material enters the film-forming device more uniformly, before preparing the electrode film, the pre-fibrillated material can be granulated by using a granulator to form pre-fibrillated material particles. The size of the pre-fibrillated material particles can be spherical particles of 10 μm to 2000 μm, specifically, it can be 10 μm, 100 μm, 200 μm, 500 μm, 800 μm, 1000 μm, 1500 μm, 2000 μm, etc. In this way, the mixed material can enter the film-forming device uniformly, and the phenomenon of agglomeration of the pre-fibrillated material can be avoided, thereby ensuring the film-forming quality.

[0077] In some specific embodiments of the present invention, the mixed material includes 0.5 wt.% to 10 wt.% of a binder, 80 wt.% to 99 wt.% of an active substance, 0 wt.% to 5 wt.% of a conductive agent, and 0 wt.% to 20 wt.% of a solid electrolyte.

[0078] That is to say, during the process of mixing the binder powder with the active material to form a mixed material, a conductive agent and a solid electrolyte are also added, so that the mixed material contains a binder, an active material, a conductive agent, and a solid electrolyte. Specifically, the content of the binder in the mixed material is 0.5 wt.% to 10 wt.%, for example, 0.5 wt.%, 2 wt.%, 3.5 wt.%, 5 wt.%, 6.5 wt.%, 8 wt.%, 9.5 wt.%, and 10 wt.%, etc.; the content of the active material is 80 wt.% to 99 wt.%, for example, 80 wt.%, 83 wt.%, 86 wt.%, 89 wt.%, 92 wt.%, 95 wt.%, 98 wt.%, and 99 wt.%, etc.; the content of the conductive agent is 0 wt.% to 5 wt.%, for example, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, and 5 wt.%, etc.; the content of the solid electrolyte is 0 wt.% to 20 wt.%, for example, 1 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%, etc.

[0079] It should be noted that the content of each component in the mixed material can be determined according to actual needs, and will not be elaborated in this embodiment.

[0080] The electrode preparation method of the embodiment of the present invention will be specifically described below with reference to specific embodiments.

[0081] Example 1

[0082] First, use dry ice as a refrigerant to freeze the PTFE raw material particles to about 50 °C to embrittle the PTFE raw material particles; then use the method of air flow pulverization to pulverize the embrittled PTFE raw material particles to obtain PTFE powder with a particle size of 50000 nm; then, use a high-speed mixer to mix the PTFE powder, the active material, the conductive agent, and the solid electrolyte at about 15 °C; then, use a calender to pre-fibrillate the mixed material at 80 °C to obtain a pre-fibrillated material; then, use a granulator to granulate the pre-fibrillated material to form a particle size of about 1000 um. After granulation, use a film-forming device to prepare the pre-fibrillated material into an electrode membrane with a thickness of 50 um to 100 um, and use a composite device to composite the electrode membrane on both sides of the current collector to obtain the required electrode.

[0083] Among them, the weight content of the PTFE powder is 2%, the weight content of graphite (i.e., the active material) is 81%, the weight content of the conductive agent is 2%, the weight content of the solid electrolyte is 15%, and the thickness of the current collector is 4 um to 12 um.

[0084] Example 2

[0085] The difference from Example 1 is that liquid nitrogen is used as a refrigerant to freeze the PTFE raw material particles to about 100 °C to embrittle the PTFE raw material particles.

[0086] Comparative Example 1

[0087] The PTFE raw material particles are mixed evenly with the active substance, conductive agent, and solid electrolyte at about 15 °C using a high-speed mixer to obtain a mixed material. The linear velocity of the mixing is 20 m / s. Then, the mixed material is pre-fibrillated at 80 °C to obtain a pre-fibrillated material. The linear velocity of the pre-fibrillation is 40 m / s. Next, a film-forming device is used to prepare the pre-fibrillated material into an electrode membrane, and a composite device is used to composite the electrode membrane on both sides of the current collector.

[0088] The test results of the above examples and comparative examples are shown in the following table.

[0089] Table 1: Thickness parameters of electrodes prepared by different electrode preparation methods

[0090]

[0091]

[0092] Table 2: Maximum film-forming roller speed of different electrode preparation methods

[0093] Item Example 1 Example 2 Comparative Example Maximum film-forming roller speed m / min 30 30 10

[0094] Table 3: Resistance parameters of electrodes prepared by different electrode preparation methods

[0095] Item Example 1 Example 2 Comparative Example Resistivity at point a / Ωcm 2.540 2.447 2.609 Resistivity at point b / Ωcm 2.563 2.571 2.311 Resistivity at point c / Ωcm 2.498 2.470 2.494 Resistivity at point d / Ωcm 2.573 2.520 2.532 Resistivity at point e / Ωcm 2.668 2.374 2.755 Resistivity at point f / Ωcm 2.722 2.378 2.656 Resistivity at point g / Ωcm 2.583 2.488 2.377 Resistivity at point h / Ωcm 2.826 2.450 2.735 Thickness standard deviation 0.1326 0.0810 0.1956 Resistance variance / % 3.894 2.531 5.883

[0096] As can be seen from Tables 1 to 3, the preparation method of the embodiments of the present invention can improve the uniformity of the electrode thickness, is conducive to the high-speed film formation of the electrode membrane, can effectively improve the production efficiency of the electrode, and can ensure the uniformity of the electrode resistance at the same time.

[0097] All in all, according to the electrode preparation method provided in this embodiment, by embrittling the binder by freezing, the toughness of the binder is significantly reduced and the brittleness is increased, so that the binder can be uniformly crushed into fine particles, which can improve the uniformity of the mixing of the binder and other materials and the degree of pre-fibrillation. Furthermore, the uniformity of the electrode thickness can be effectively improved, and it is conducive to the high-speed film formation of the electrode membrane, which can effectively improve the production efficiency of the electrode, and can ensure the uniformity of the electrode resistance at the same time. In addition, mixing the binder and other materials evenly can ensure the uniformity of the electrode resistance, thereby ensuring the rate performance of the battery, and can reduce the amount of the binder, and further improve the resistance of the electrode and improve the battery performance.

[0098] An embodiment of the present invention further provides an electrode preparation system, including: a freezing device, a pulverizing device, a mixing device, a pre-fibrillation device, a film-forming device, and a composite device. The freezing device is used to freeze the binder to the embrittlement temperature, the pulverizing device is used to pulverize the binder into binder powder, the mixing device is used to mix the binder powder with the active material to form a mixed material, the pre-fibrillation device is used to pre-fibrillate the mixed material to form a pre-fibrillated material, the film-forming device is used to prepare the pre-fibrillated material into an electrode film sheet with a preset thickness, and the composite device is used to composite the electrode film sheet with the current collector to form an electrode.

[0099] In other words, the electrode preparation system according to the embodiment of the present invention mainly consists of a freezing device, a pulverizing device, a mixing device, a pre-fibrillation device, a film-forming device, and a composite device. Among them, the freezing device can be a dry ice freezer or a liquid nitrogen freezer. Through the freezing device, the binder can be frozen to the required temperature. The pulverizing device can pulverize the frozen binder into fine binder powder. The mixing device can be a high-speed mixer, and the mixing temperature of the high-speed mixer can be adjusted. The high-speed mixer can mix the binder powder, the active material conductive agent, and the solid electrolyte at different temperatures. After mixing, the required mixed material can be obtained; the fibrillating device can be a pair-roll mill or an open mill, and the fibrillating device can perform pre-fibrillation treatment on the mixed material. After the pre-fibrillation treatment, the pre-fibrillated mixed material can be obtained; the film-forming device and the composite device can be integrated into a roll press, and the roll press is composed of at least three independent electrodes and rolls controlled by a speed reducer, so that the roll press can press the mixed material into an electrode film sheet and can composite the electrode film sheet with the current collector to form the required electrode.

[0100] Thus, according to the electrode preparation method provided in this embodiment, the freezing device can freeze and embrittle the binder, significantly reducing the toughness and increasing the brittleness of the binder, so that the binder can be uniformly pulverized into fine particles, improving the uniformity of the mixture of the binder and other materials and the degree of pre-fibrillation, effectively improving the uniformity of the electrode thickness, facilitating the high-speed film formation of the electrode film sheet, effectively improving the production efficiency of the electrode, and ensuring the uniformity of the electrode resistance at the same time; in addition, mixing the binder and other materials evenly can ensure the uniformity of the electrode resistance, thereby ensuring the rate performance of the battery, and reducing the amount of the binder, thus improving the resistance of the electrode and enhancing the battery performance.

[0101] According to some specific embodiments of the present invention, the electrode preparation system further includes: a granulating device, and the granulating device is used to granulate the mixed material before preparing the electrode film sheet.

[0102] That is to say, in order to ensure that the mixed material enters the film forming device more uniformly, the electrode preparation system of the present invention is further configured with a granulating device (i.e., a granulator), and the granulator can granulate the mixed material to form mixed material particles with a size of 10um to 2000um, so that the mixed material can enter the film forming device uniformly, avoiding the agglomeration phenomenon of the mixed material, and thus ensuring the film forming quality.

[0103] In some specific embodiments of the present invention, the pulverizing device is configured as a pneumatic pulverizing device or a mechanical pulverizing device.

[0104] Specifically, the pulverizing device can be a mechanical pulverizing device, which has a relatively low cost and low energy consumption. The pulverizing device can also be a pneumatic pulverizing device (for example, a low-temperature pneumatic pulverizer), and the pneumatic pulverizing device can pulverize the binder into finer particles with a narrower particle size distribution, and the particles after pneumatic pulverization have a more regular shape, which can ensure the uniformity of the electrode film and thus improve the product quality of the electrode.

[0105] The embodiment of the present invention also provides an electrode, which is made by the electrode preparation method or the electrode preparation system described in any of the above embodiments. Since the electrode preparation method and the electrode preparation system according to the embodiments of the present invention have the above technical effects, the electrode according to the embodiments of the present invention also has corresponding technical effects, which will not be elaborated in this embodiment.

[0106] The embodiment of the present invention also provides a battery, including the electrode described in the above embodiment. Since the electrode preparation method and the electrode preparation system according to the embodiments of the present invention have the above technical effects, the battery according to the embodiments of the present invention also has corresponding technical effects, which will not be elaborated in this embodiment.

[0107] The differences between the above embodiments are mainly described. As long as the different optimization features between the embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, it will not be elaborated here.

[0108] Although some specific embodiments of the present invention have been described in detail by examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A method for preparing an electrode, characterized in that: include: Freeze and embrittle the binder; crushing the binder into binder powder; mixing the binder powder with the active material to form a mixed material; Prefiberizing the mixed material to form a prefiberized material; Rolling the pre-fiberized material into an electrode membrane; The electrode membrane is combined with a current collector to form an electrode.

2. The electrode preparation method according to claim 1, characterized in that: The particle size of the binder powder is 100nm to 100000nm.

3. The electrode preparation method according to claim 1, characterized in that: The binder is configured as polytetrafluoroethylene or a copolymer thereof.

4. The electrode preparation method according to claim 1, characterized in that: The binder is frozen to -10°C to -179°C to be brittle.

5. The electrode preparation method according to claim 1, characterized in that: The binder is frozen to -50°C to -100°C to be brittle.

6. The electrode preparation method according to claim 1, characterized in that: The refrigerant used to freeze the binder is dry ice or liquid nitrogen.

7. The electrode preparation method according to claim 1, characterized in that: The method of pulverizing the binder into binder powder is air flow pulverization.

8. The electrode preparation method according to claim 1, characterized in that: Mixing the binder powder with the active material at a temperature lower than the crystal transition temperature of the binder to form a mixed material; And / or, the mixed material is pre-fiberized at a temperature higher than the crystal transition temperature of the binder to form a pre-fiberized material.

9. The electrode preparation method according to claim 8, characterized in that: In the step of mixing the binder powder with the active material, the mixing temperature is controlled to be 0°C to 19°C; And / or, in the step of pre-fiberizing the mixed material to form a pre-fiberized material, the pre-fiberization temperature is controlled to be 60°C to 150°C.

10. The electrode preparation method according to claim 1, characterized in that: In the step of rolling the pre-fiberized material into an electrode membrane, the temperature of the roller used is 20°C to 150°C.

11. The electrode preparation method according to claim 1, characterized in that: Also includes: Before preparing the electrode membrane, the pre-fiberized material is granulated.

12. An electrode preparation system, characterized in that: include: A freezing device, the freezing device is used to freeze the binder to a brittle temperature; A pulverizing device, the pulverizing device is used to pulverize the binder into binder powder; A mixing device for mixing a binder powder with an active substance to form a mixed material; A prefiberizing device, the prefiberizing device is used to prefiberize the mixed material to form a prefiberized material; A film-forming device, wherein the film-forming device is used to prepare the pre-fiberized material into an electrode film of a preset thickness; A composite device is provided, wherein the composite device is used to composite an electrode membrane with a current collector to form an electrode.

13. The electrode preparation system according to claim 12, characterized in that: Also includes: A granulation device is used to granulate the pre-fiberized material before preparing the electrode membrane.

14. The electrode preparation system according to claim 12, characterized in that: The pulverizing device is configured as a jet pulverizing device or a mechanical pulverizing device.

15. An electrode, characterized in that: The electrode is manufactured by the electrode manufacturing method according to any one of claims 1 to 11 or the electrode manufacturing system according to any one of claims 12 to 14.

16. A battery, characterized in that: Comprising the electrode according to claim 15.

Images