Electrode sheet processing system, electrode sheet treatment method, electrode sheet, battery and electrical apparatus

Abstract

The present application belongs to the technical field of batteries, and particularly relates to an electrode sheet processing system, an electrode sheet treatment method, an electrode sheet, a battery and an electrical apparatus. The electrode sheet processing system comprises a flame heating unit, the flame heating unit being used for carrying out flame heating treatment on an electrode sheet. The electrode sheet treatment method comprises: performing flame heating treatment on an electrode sheet, so as to allow the surface temperature of an active layer to be greater than or equal to the softening temperature or melting temperature of a binder and less than the lowest temperature among the decomposition temperature, the oxidation temperature and the ignition temperature of an active substance. During the flame heating treatment, the binder that ascends to the surface of the electrode sheet can be softened (melted) or ablated. After the ascending binder is softened (melted) or ablated, the number of capillary pores of the electrode sheet is increased, such that pathways in the electrode sheet for electrolyte infiltration are increased, allowing an electrolyte to more easily infiltrate the electrode sheet and thus improving the electrolyte infiltration of the electrode sheet.

Description

Pole piece processing system, pole piece processing method, pole piece, battery, and electrical device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on June 29, 2023, with application number 202310783837.7 and invention name “Pole piece processing system, method for processing pole piece, pole piece, battery, and electrical device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the field of battery technology, and in particular relates to a pole piece processing system, a pole piece processing method, a pole piece, a battery, and an electrical device. Background Art

[0003] With the development of the new energy industry, battery research is becoming increasingly popular, and market requirements are constantly increasing. However, there are still many problems that need to be solved, such as poor electrolyte wettability of electrodes.

[0004] When the electrode is not wetted by the electrolyte, it is difficult for the electrode to participate in the electrochemical reaction of the battery, reducing the ions that can be freely conducted between the positive and negative electrodes, thereby affecting the charge and discharge capacity of the battery. At the same time, when the electrode cannot participate in the electrochemical reaction of the battery, it will also cause the battery interface resistance to increase, affecting the battery's rate performance, discharge capacity and cycle performance. Therefore, the electrolyte wettability of the electrode is related to various electrochemical properties of the battery, such as the charge and discharge capacity, rate performance, cycle performance, etc. Improving the electrolyte wettability of the electrode is of great significance to improving battery performance.

[0005] Summary of the Invention

[0006] In view of the above problems, the present application provides a pole piece processing system, a pole piece processing method, a pole piece, a battery, and an electrical device, which can improve the electrolyte infiltration performance of the pole piece.

[0007] In a first aspect, the present application provides a pole piece processing system, comprising: a flame heating unit, wherein the flame heating unit is used to perform flame heating treatment on the pole piece.

[0008] The electrode processing system of the present embodiment employs a flame heating unit to perform flame heating on the electrode. During the flame heating process, the adhesive that has risen to the surface of the electrode can be softened (melted) or ablated. After the floating adhesive is softened (melted) or ablated, the number of capillaries in the electrode increases, increasing the number of channels for electrolyte infiltration in the electrode, making it easier for the electrolyte to infiltrate the electrode, thereby improving the electrolyte wettability of the electrode.

[0009] In addition, the electrode processing system of the embodiment of the present application can be integrated into the existing electrode production line. It only requires adding a flame heating unit to the existing electrode production line, without requiring a large amount of additional production line modification time and equipment, which has a good cost advantage.

[0010] In some embodiments, the flame heating unit generates flames on opposite sides of the pole piece surface. In this way, both opposite surfaces of the pole piece can be subjected to flame heating treatment, so that the adhesive on both surfaces of the pole piece is softened (melted) or ablated, which is beneficial to improving the processing efficiency of the pole piece.

[0011] In some embodiments, the flame heating unit includes a flameless gas burner. The flame heating unit of the present application is provided with a flameless gas burner, which not only facilitates rapid heating of the electrode, but also improves the situation in which carbon deposits on the electrode surface during the flame heating process, resulting in reduced porosity on the electrode surface, helps to improve the overall capillary pore distribution of the electrode, and further accelerates the electrolyte infiltration rate of the electrode.

[0012] In some embodiments, the electrode processing system further includes a conveyor unit for conveying the electrode. The conveyor unit allows the electrode to enter the flame heating unit and other processing steps in an orderly manner, enabling continuous and uninterrupted operation. Furthermore, by adjusting the operating speed of the conveyor unit, the flame generated by the flame heating unit can be adjusted to rapidly pass through the electrode, achieving rapid heating of the electrode and improving processing efficiency.

[0013] In the second aspect, the present application provides a method for processing an electrode, wherein the electrode includes an active layer, and the active layer includes an active substance and a binder; the method for processing the electrode includes: flame heating the electrode so that the surface temperature of the active layer is greater than or equal to the softening temperature or melting temperature of the binder, and less than the lowest temperature among the decomposition temperature, oxidation temperature, and ignition temperature of the active substance.

[0014] In the method of the embodiment of the present application, by treating the electrode by flame heating and controlling the temperature of the active layer during the flame heating process, the binder that floats to the surface of the electrode can be softened (melted) or ablated. After the floated binder is softened (melted) or ablated, the number of capillaries in the electrode increases, increasing the number of channels for electrolyte infiltration in the electrode, making it easier for the electrolyte to infiltrate the electrode, thereby improving the electrolyte wettability of the electrode.

[0015] At the same time, during the flame heating process, the temperature of the active layer is lower than the lowest temperature among the decomposition temperature, oxidation temperature and ignition temperature of the active material. The decomposition, oxidation and combustion of the active material during the flame heating process can be prevented, and the lattice stability of the active material and the structural stability of the electrode can be maintained.

[0016] In some embodiments, the flame used in the flame heating process includes a premixed combustion flame. The embodiments of the present application utilize a premixed combustion flame to perform flame heating on the electrode piece, which not only facilitates rapid heating of the electrode piece, but also improves the situation in which carbon deposits on the electrode piece surface during the flame heating process, resulting in reduced porosity on the electrode piece surface. This helps improve the overall capillary pore distribution of the electrode piece and further accelerates the electrolyte infiltration rate of the electrode piece.

[0017] In some embodiments, the temperature of the premixed combustion flame is 500-1200° C., optionally 600-1000° C. The use of a high-temperature flame to perform flame heating on the pole piece can rapidly heat the pole piece to a desired temperature.

[0018] In some embodiments, the premixed combustion flame is generated by a flameless gas burner, and the flameless gas burner includes any one or more of the following technical parameters:

[0019] (1) Air flow rate 50-250 L / min, optionally 80-150 L / min;

[0020] (2) Gas fuel flow rate 2 to 15 L / min, optionally 5 to 10 L / min;

[0021] (3) Air-fuel ratio 1 to 7, optionally 3 to 5.

[0022] The present embodiment uses a flameless gas burner to generate a premixed combustion flame, which can rapidly heat the active layer to the desired temperature. Furthermore, under certain conditions of air flow, gas fuel flow, and air-fuel ratio, the gas fuel can fully burn, resulting in a flame with fewer free carbon particles and a lower flame blackness. This can alleviate the problem of carbon deposits on the electrode surface during flame heating, which can lead to reduced porosity on the electrode surface.

[0023] In some embodiments, during the flame heating step, the electrode piece is moved relative to the flame. This movement adjusts the electrode piece's residence time under the flame, achieving rapid, instantaneous heating of the electrode piece and improving treatment efficiency. Furthermore, because the flame has a relatively high temperature, controlling the electrode piece's movement relative to the flame can reduce the contact time between the flame and the electrode piece, thereby controlling the electrode piece temperature within a suitable range.

[0024] In some embodiments, the pole piece moves at a speed relative to the flame of 40 to 100 m / min, and optionally 60 to 80 m / min. The pole piece of the embodiment of the present application moves rapidly relative to the flame, and the pole piece has a short residence time under the flame, thereby achieving rapid and instantaneous heating of the pole piece, and controlling the temperature of the active layer in the pole piece during the flame heating process within a desired range.

[0025] In some embodiments, the surface temperature of the active layer is 180-500°C, optionally 300-500°C. These temperature ranges are greater than or equal to the softening temperature or melting temperature of common electrode adhesives, and less than the lowest temperature among the decomposition temperature, oxidation temperature, and ignition temperature of common electrode active materials. This can effectively soften (melt) or ablate the adhesive floating on the surface of the electrode, while improving the decomposition, oxidation, or combustion of the active material during flame heating treatment, maintaining the lattice stability of the active material and the structural stability of the electrode.

[0026] In a third aspect, the present application provides a pole piece, wherein the porosity of the pole piece is 30% to 50%, optionally 30% to 47%.

[0027] The electrode provided in the embodiment of the present application has a high porosity, which is conducive to increasing the channels for the electrolyte to infiltrate the electrode, making it easier for the electrolyte to infiltrate the electrode, thereby improving the wettability of the electrolyte to the electrode.

[0028] In some embodiments, the pole piece includes any one or more of the following technical parameters:

[0029] (1) The liquid absorption rate is 0.3μg / s to 12μg / s;

[0030] (2) The diaphragm resistance is 0.001Ω~0.43Ω;

[0031] (3) Adhesion strength 18~23N / m.

[0032] The electrode provided in the embodiment of the present application has a high liquid absorption rate, low membrane resistance, and still has good adhesion.

[0033] In some embodiments, the electrode sheet includes a positive electrode sheet, and the positive electrode sheet has a porosity of 35% to 50%, a liquid absorption rate of 0.3 μg / s to 0.5 μg / s, a membrane resistance of 0.0016Ω to 0.002Ω, and a bonding force of 18 to 20 N / m; or,

[0034] The electrode sheet includes a negative electrode sheet, and the porosity of the negative electrode sheet is 30% to 35%, the liquid absorption rate is 9 μg / s to 12 μg / s, the membrane resistance is 0.39Ω to 0.43Ω, and the bonding force is 20 to 23 N / m.

[0035] By selecting and matching the porosity, liquid absorption rate, membrane resistance and bonding strength of the positive and negative electrode sheets, they can be well used in batteries.

[0036] In some embodiments, the electrode is processed according to the method for processing an electrode described in the second aspect of the present application. After the flame heating treatment, the adhesive floating on the surface of the electrode is softened (melted) or ablated, exposing more capillary pores in the electrode. Therefore, the treated electrode has a high porosity, which is conducive to increasing the channels for the electrolyte to infiltrate the electrode, making it easier for the electrolyte to infiltrate the electrode, thereby improving the wettability of the electrolyte to the electrode.

[0037] In a fourth aspect, the present application provides a battery, comprising the electrode described in the third aspect of the present application.

[0038] The battery of the embodiment of the present application includes the above-mentioned electrode sheet, which can be either a positive electrode sheet or a negative electrode sheet, or can include both positive and negative electrode sheets. Because the floating binder in the battery electrode sheet is softened (melted) and ablated, the electrode sheet has a higher porosity, which is conducive to improving the wettability of the electrolyte to the electrode sheet, thereby helping to improve the electrochemical performance of the battery.

[0039] In a fifth aspect, the present application provides an electrical device, which includes the battery described in the fourth aspect.

[0040] The battery disclosed in the embodiments of the present application can be used in an electrical device using a battery as a power source, or in various energy storage systems using a battery as an energy storage element, for providing electrical energy. The electrical device may include, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, and the like. Among them, the electric toy may include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, and an electric airplane toy, and the like, and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, and the like. As the electrical device, a battery cell, a battery module, or a battery pack in a secondary battery can be selected according to its usage requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0042] FIG1 is a schematic structural diagram of a pole piece processing system provided in Example A1 of the present application;

[0043] FIG2 is a schematic diagram of a battery module according to an embodiment of the present application;

[0044] FIG3 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0045] FIG4 is an exploded view of the battery pack shown in FIG3 according to an embodiment of the present application;

[0046] FIG5 is a schematic diagram of a battery according to an embodiment of the present application;

[0047] FIG6 is an exploded view of the battery shown in FIG5 according to one embodiment of the present application;

[0048] FIG7 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0049] Figure numerals: 10 - pole piece; 20 - conveying unit; 21 - unwinding guide roller; 22 - rewinding guide roller; 30 - flame heating unit; D - conveying direction of pole piece; 1 - battery pack; 2 - upper box; 3 - lower box; 4 - battery module; 5 - battery cell; 51 - shell; 52 - electrode assembly; 53 - cover plate. DETAILED DESCRIPTION

[0050] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0052] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0053] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0054] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0055] In the description of the embodiments of the present application, the term "at least one" refers to one or more, and "plurality" refers to two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple, respectively.

[0056] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0057] The masses of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the proportional relationship between the masses of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the masses described in the examples of this application may be mass units known in the chemical industry, such as μg, mg, g, and kg.

[0058] With the development of the new energy industry, battery research is becoming increasingly popular, and market requirements are constantly increasing. However, there are still many problems that need to be solved, such as poor wettability of electrodes.

[0059] If the electrode is not well wetted by the electrolyte, it will be difficult for the electrode to participate in the electrochemical reaction of the battery, reducing the ions that can be freely conducted between the positive and negative electrodes, thereby affecting the charge and discharge capacity of the battery. At the same time, if the electrode cannot participate in the electrochemical reaction of the battery, it will also cause the battery interface resistance to increase, affecting the battery's rate performance, discharge capacity and cycle performance. Therefore, the electrolyte wettability of the electrode is related to various electrochemical properties of the battery, such as charge and discharge capacity, rate performance, and cycle performance.

[0060] Analysis has shown that the electrolyte wetting performance of the electrode is affected by various factors during the electrode processing. For example, energy density is a key battery indicator; the higher the energy density, the more electricity the battery can release. To increase the battery's energy density, a thick coating method can be used to produce the battery electrode. Specifically, during the electrode preparation process, the ratio of active material to current collector is increased, which in turn increases the amount of electrode slurry applied. However, this increased electrode slurry coating also increases the electrode thickness, which can reduce the electrode's electrolyte wetting rate.

[0061] At the same time, the method of thick coating of the electrode leads to an increase in the thickness of the electrode, which is inconsistent with the market's pursuit of battery portability and small size. Therefore, during the electrode manufacturing process, it is often necessary to increase the compaction density of the electrode as much as possible. However, this will cause the pores between the active materials in the electrode to be compressed smaller and smaller, making it difficult for the electrolyte to penetrate them. Moreover, in the electrode manufacturing process, after the electrode slurry is coated on the current collector, it is often necessary to remove the solvent in the electrode slurry through drying and other processes to form a stable electrode. During the drying process, the solvent in the electrode slurry migrates to the surface of the electrode through capillary force and evaporates. The commonly used binder has a light density and a large specific surface area, and it is easy to migrate to the surface of the electrode as the solvent evaporates, resulting in the problem of binder floating. The floating binder will block the pores of the electrode, preventing the electrolyte from penetrating into the capillary pores of the electrode, thereby reducing the electrolyte infiltration rate of the electrode and affecting the various electrochemical properties of the battery.

[0062] In order to improve the wetting performance of the electrolyte on the electrode, the embodiment of the present application provides a flame heating unit capable of generating flames in the electrode processing system to perform flame heating treatment on the electrode. Alternatively, in the electrode processing method, a process of flame heating the electrode is provided. During the flame heating process, the adhesive that floats to the surface of the electrode can be softened (melted) or ablated. After the floated adhesive is softened (melted) or ablated, the electrode exposes more capillaries, increases the channels for the electrolyte to infiltrate the electrode, makes it easier for the electrolyte to infiltrate the electrode, and thus improves the electrolyte wettability of the electrode. At the same time, the method of the embodiment of the present application has the advantages of obvious effect and low cost.

[0063] The electrode heating system or electrode processing method disclosed in the embodiments of the present application can be used to produce positive electrode sheets or negative electrode sheets with excellent performance and wide applicability. Moreover, the prepared electrode sheets can be applied to batteries and electrical devices that use batteries as power sources. The electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0064] The present application will be further described below with reference to the following examples. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application.

[0065] A first aspect of an embodiment of the present application provides a pole piece processing system, comprising: a flame heating unit, which is used to perform flame heating treatment on the pole piece.

[0066] The electrode processing system refers to the process equipment used to make and process the electrode. Flame heating is a method of using flame to burn the sample to increase the temperature of the sample.

[0067] The electrode processing system of the present embodiment employs a flame heating unit to perform flame heating on the electrode. During the flame heating process, the adhesive that has risen to the surface of the electrode can be softened (melted) or ablated. After the floating adhesive is softened (melted) or ablated, the number of capillaries in the electrode increases, increasing the number of channels for electrolyte infiltration in the electrode, making it easier for the electrolyte to infiltrate the electrode, thereby improving the electrolyte wettability of the electrode.

[0068] In addition, the electrode processing system of the embodiment of the present application can be integrated into the existing electrode production line. It only requires adding a flame heating unit to the existing electrode production line, without requiring a large amount of additional production line modification time and equipment, which has a good cost advantage.

[0069] In some embodiments, the flame heating unit generates flames on opposite sides of the pole piece surface. In this way, both opposite surfaces of the pole piece can be subjected to flame heating treatment, so that the adhesive on both surfaces of the pole piece is softened (melted) or ablated, which is beneficial to improving the processing efficiency of the pole piece.

[0070] In some embodiments, the flame heating unit comprises a flameless gas burner.

[0071] A gas burner is a device that converts gas fuel into heat energy through combustion. Gas burners can be categorized as either flamed or flameless, depending on the type of flame they use. Flamed gas burners produce a strong light-emitting flame, operating on the principle of gas diffusion combustion. Flameless gas burners, on the other hand, produce a weaker light-emitting flame, operating on the principle of gas premixed combustion (actual flameless gas burners involve partial diffusion combustion, meaning they operate on the principle of partial premixed combustion).

[0072] Gas diffusion combustion and premixed gas combustion are two different types of gas combustion. In gas diffusion combustion, the gas fuel and oxidant (air or oxygen) are not in contact before ignition and are fed separately into the combustion chamber for combustion. For example, combustion by torches, kerosene lamps, alcohol lamps, etc. is a type of gas diffusion combustion. Gas diffusion combustion has the disadvantages of poor combustion stability and low heat release rate. In addition, because the gas fuel and oxidant are not in contact before ignition, incomplete combustion produces carbon particles, which easily form carbon deposits on the surface of the sample heated by the flame.

[0073] Premixed gas combustion occurs when the gas fuel and oxidant are mixed and contacted before ignition. Premixed gas combustion offers advantages such as high thermal intensity and high combustion temperature. By controlling the oxidant content in the premix, the gas fuel can be completely burned, reducing the amount of soot produced during combustion. Furthermore, premixed gas combustion boasts a rapid combustion rate, preventing the hydrocarbons in the gas fuel from breaking down quickly. This results in fewer free carbon particles in the flame and a lower flame density.

[0074] Therefore, the embodiment of the present application sets a flameless gas burner in the flame heating unit, which is not only conducive to the rapid heating of the electrode, but also can improve the situation where carbon deposition occurs on the surface of the electrode during the flame heating process, resulting in a reduction in the porosity of the electrode surface, and helps to improve the overall capillary pore distribution of the electrode, and further accelerate the electrolyte infiltration rate of the electrode.

[0075] Illustratively, the flameless gas burner according to the embodiment of the present application includes a jet-type gas burner, that is, a lance burner.

[0076] In some embodiments, the gas fuel used in the flameless gas burner includes one or more of natural gas, hydrogen, carbon monoxide, methane, ethane, ethylene, propylene, acetylene, and propyne. These gas fuels have advantages such as high thermal intensity and high combustion temperature during combustion, enabling rapid flame heating of the electrode.

[0077] In some embodiments, the pole piece processing system further includes a conveying unit, which is used to convey the pole piece.

[0078] Under the action of the conveying unit, the electrode pieces enter the flame heating unit and other processes in an orderly manner for processing, and can work continuously and uninterruptedly. The conveying unit may include an unwinding guide roller and a winding guide roller arranged in an array, which are used to unwind and wind the electrode pieces respectively. The electrode pieces are placed on the unwinding guide roller and the winding guide roller, and the winding guide roller is operated, so that the electrode pieces can be moved relative to the flame heating unit under the traction of the winding guide rail. The running speed of the winding guide roller can be set to 40 to 100 m / min, optionally 60 to 80 m / min, including but not limited to any one of 40 m / min, 45 m / min, 50 m / min, 55 m / min, 60 m / min, 65 m / min, 70 m / min, 75 m / min, 80 m / min, 85 m / min, 90 m / min, 95 m / min, 100 m / min or any range value between the two, or set to other running speeds according to actual needs. By regulating the operating speed of the conveying unit, the flame generated by the rapid passage of the electrode through the flame heating unit can be adjusted, thereby achieving rapid heating of the electrode and improving processing efficiency.

[0079] In some embodiments, the electrode processing system further includes a temperature measuring unit, which is used to measure the electrode temperature. By providing the temperature measuring unit, the electrode temperature can be timely and accurately understood and the electrode status can be monitored. The temperature measuring unit can be used to measure the surface temperature of the electrode, the internal temperature of the electrode, or the surface temperature and the internal temperature of the electrode at the same time. At the same time, the temperature measuring unit can be used to measure the temperature of the electrode undergoing flame heating treatment, or to measure the temperature of the electrode after flame heating treatment. For example, it can be used to measure the temperature of the electrode 3 to 10 cm downstream of flame heating (such as any one of 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm or any range between the two).

[0080] In some embodiments, the temperature measurement unit includes an infrared temperature measurement module, which can be used to measure the temperature of the electrode in a non-contact manner.

[0081] In some embodiments, the electrode processing system further includes an automatic temperature control unit, which is used to control the heating conditions of the flame heating unit, such as controlling the gas fuel flow rate, air flow rate, etc. in the flame heating unit. The automatic temperature control unit can receive the electrode temperature data measured by the temperature measuring unit and control the flame heating unit based on the temperature data to accurately and effectively soften (melt) or ablate the floating binder in the electrode, thereby reducing the adverse effects on other components in the electrode.

[0082] In some embodiments, the electrode processing system further includes a drying unit, which is used to dry the electrode coated with the electrode slurry, and the drying unit and the flame heating unit are arranged in sequence along the conveying direction of the electrode. Among them, the electrode coated with the electrode slurry refers to the electrode containing a wet film formed by coating the electrode slurry on the current collector (usually one surface or two surfaces of the current collector). At this time, the electrode slurry is not dried and still contains a solvent. The drying unit and the flame heating unit are arranged in sequence in the conveying direction of the electrode, which means that the electrode first passes through the drying unit and then passes through the flame heating unit. After being processed by the drying unit, the binder in the electrode slurry floats to the surface of the electrode, affecting the structure of the electrode. In this regard, these floating binders can be softened (melted) or ablated after being processed by the flame heating unit.

[0083] In some embodiments, the electrode processing system further includes a rolling unit for rolling the electrode, wherein the rolling unit and the flame heating unit are sequentially arranged along the direction of conveyance of the electrode; alternatively, the drying unit, the rolling unit, and the flame heating unit are sequentially arranged along the direction of conveyance of the electrode. Rolling methods generally include cold pressing and hot pressing, which can enhance the internal bonding strength of the electrode and achieve the desired compaction density.

[0084] In some embodiments, the electrode processing system further includes a cooling unit for cooling the electrode. The flame heating unit and the cooling unit are sequentially arranged along the electrode conveying direction. After the electrode is processed by the flame heating unit, it is usually necessary to reel the electrode. Excessively high electrode temperature is not conducive to reeling. Therefore, cooling the electrode by the cooling unit can reduce the electrode temperature and facilitate subsequent reeling of the electrode.

[0085] The second aspect of an embodiment of the present application provides a method for processing an electrode, which includes an active layer, and the active layer includes an active substance and a binder. The method for processing the electrode in the embodiment of the present application includes: flame heating the electrode so that the surface temperature of the active layer is greater than or equal to the softening temperature or melting temperature of the binder, and is less than the lowest temperature among the decomposition temperature, oxidation temperature, and ignition temperature of the active substance.

[0086] Among them, the active material is the substance in the electrode used to participate in the electrochemical reaction of the battery and can serve as a medium for the transmission of ions in the electrochemical reaction. The binder is a polymer compound used to bind the various components in the active layer (such as active materials and other substances) and the current collector. It mainly plays the role of bonding and maintaining the firmness of the active material in the active layer, and enhancing the bonding strength between the active layer and the current collector. The binder is mixed with the active material, solvent and other necessary components to form a slurry and is coated on at least one side of the current collector. After the solvent evaporates, the slurry dries to form the active layer of the electrode.

[0087] In the embodiments of the present application, the surface layer of the active layer refers to the outermost layer of the active layer in contact with the outside world. Generally, the pole piece includes a current collector and an active layer provided on at least one side of the current collector, so the surface layer of the active layer is usually also the surface layer of the pole piece. Generally, the area within 40% of the thickness of the pole piece along the thickness direction of the pole piece and from the outside to the inside can be regarded as the surface layer of the pole piece. For example, for a commonly used pole piece with a thickness of 50 to 300 μm, the area with a thickness of 0 to 20 μm (along the thickness direction of the pole piece and from the outside to the inside) can be regarded as the surface layer of the pole piece, that is, the surface layer of the active layer. In the active layer, the area outside the surface layer of the active layer can be regarded as the inside of the active layer. During the flame heating process, the surface temperature of the active layer can be the temperature of the area of ​​the active layer surface that is being heated by the flame, or the temperature of the area of ​​the active layer surface downstream of the flame heating, for example, the temperature of an area 3 to 10 cm downstream of the flame heating (such as any one point value of 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm or a range value between any two of them). This area is close to the flame heating area, and its temperature can usually be considered to be the same as the surface temperature of the active layer during flame heating.

[0088] The softening temperature is the temperature at which the three-dimensional long-range order of the macromolecular chain structure of an amorphous polymer transitions to a disordered viscous flow state. The melting temperature, also known as the melting point, is the temperature at which the three-dimensional long-range order of the macromolecular chain structure of a crystalline polymer transitions to a disordered viscous flow state. This temperature is the lower limit of the molding and processing temperature for crystalline polymers. Generally speaking, the melting temperature range is relatively narrow, while the softening temperature range is relatively wide.

[0089] The decomposition temperature of an active substance is the temperature at which its molecular structure is destroyed or its crystal lattice is distorted, even though combustion has not occurred. The oxidation temperature of an active substance is the minimum temperature required for oxidation to occur. The ignition temperature of an active substance, also known as the ignition temperature, is the minimum temperature at which combustion occurs.

[0090] In the method of the embodiment of the present application, by treating the electrode by flame heating and controlling the surface temperature of the active layer during the flame heating process, the binder that floats to the surface of the electrode can be softened (melted) or ablated. After the floated binder is softened (melted) or ablated, the number of capillaries in the electrode increases, increasing the number of channels for electrolyte infiltration in the electrode, making it easier for the electrolyte to infiltrate the electrode, thereby improving the electrolyte wettability of the electrode.

[0091] At the same time, during the flame heating process, the surface temperature of the active layer is lower than the lowest temperature among the decomposition temperature, oxidation temperature and ignition temperature of the active material, which can reduce the decomposition, oxidation and combustion of the active material during the flame heating process and maintain the lattice stability of the active material and the structural stability of the electrode.

[0092] In some embodiments, the solvent concentration in the active layer is as low as ppm, such as less than 1000 ppm. The active layer with such a low concentration is a dried active layer, and has floating binder on its surface. In the embodiments of the present application, flame heating is performed on the electrode with the dried active layer to treat the floating binder and improve electrode performance.

[0093] In some embodiments, the flame employed in the flame heating process comprises a premixed combustion flame.

[0094] Premixed combustion, also known as gas premixed combustion, is a combustion method for gas fuels, and a premixed combustion flame is a flame generated by this combustion method. Gas premixed combustion is a combustion that occurs after the gas fuel and the oxidant are mixed and contacted before ignition. Gas premixed combustion has the advantages of high thermal intensity and high combustion temperature, and by controlling the content of the oxidant in the premix, the gas fuel can be completely burned, reducing the carbon soot generated during the combustion process; in addition, gas premixed combustion has the characteristics of fast combustion speed, and the hydrocarbons in the gas fuel do not have time to decompose, resulting in fewer free carbon particles in the flame and a lower flame blackness. Therefore, the embodiment of the present application adopts a premixed combustion flame to perform flame heating treatment on the electrode, which is not only conducive to rapid heating of the electrode, but also can improve the situation where carbon deposits appear on the surface of the electrode during the flame heating treatment, resulting in a reduction in the surface porosity of the electrode, which helps to improve the overall capillary pore distribution of the electrode and further accelerate the electrolyte infiltration rate of the electrode.

[0095] In some embodiments, the temperature of the premixed combustion flame is 500-1200°C, optionally 600-1000°C, including but not limited to any one of 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, 1200°C or any range between two of them. The premixed combustion flame is uniform and has no obvious stratification, so the temperature of the premixed combustion flame refers to the temperature of any area of ​​the entire flame. The temperature of the premixed combustion flame can be obtained by contact measurement using a galvanic couple, light, etc., or by non-contact measurement using imaging, laser spectroscopy, radiation, etc. The pole piece is subjected to flame heating treatment using a high-temperature flame, so that the pole piece can be quickly heated to the required temperature.

[0096] In some embodiments, the premixed combustion flame is generated by a flameless gas burner, which includes any one or more of the following technical parameters:

[0097] (1) Air flow rate 50-250 L / min, optionally 80-150 L / min;

[0098] (2) Gas fuel flow rate 2 to 15 L / min, optionally 5 to 10 L / min;

[0099] (3) Air-fuel ratio 1 to 7, optionally 3 to 5.

[0100] Wherein, the air flow rate includes but is not limited to any one of 50L / min, 60L / min, 70L / min, 80L / min, 90L / min, 100L / min, 110L / min, 120L / min, 130L / min, 140L / min, 150L / min, 160L / min, 170L / min, 180L / min, 190L / min, 200L / min, 210L / min, 220L / min, 230L / min, 240L / min, and 250L / min, or a range between any two of the values.

[0101] The gas fuel flow rate includes but is not limited to any point value of 2L / min, 3L / min, 4L / min, 5L / min, 6L / min, 7L / min, 8L / min, 9L / min, 10L / min, 11L / min, 12L / min, 13L / min, 14L / min, 15L / min, or a range value between any two of them.

[0102] The air-fuel ratio refers to the mass ratio of air to fuel in the mixture formed by premixing the fuel and air. This includes, but is not limited to, any of 1, 2, 3, 4, 5, 6, and 7, or a range between any two of these values.

[0103] The present embodiment uses a flameless gas burner to generate a premixed combustion flame, which can rapidly heat the active layer to the desired temperature. Furthermore, under certain conditions of air flow, gas fuel flow, and air-fuel ratio, the gas fuel can fully burn, resulting in a flame with fewer free carbon particles and a lower flame blackness. This can alleviate the problem of carbon deposits on the electrode surface during flame heating, which can lead to reduced porosity on the electrode surface.

[0104] In some embodiments, during the flame heating step, the electrode piece is moved relative to the flame. This movement adjusts the electrode piece's residence time under the flame, achieving rapid, instantaneous heating and improving treatment efficiency. Furthermore, because the flame has a relatively high temperature, controlling the electrode piece's relative movement can reduce the contact time between the flame and the electrode piece, thereby keeping the electrode piece temperature within a suitable range.

[0105] In some embodiments, the speed of movement of the pole piece relative to the flame is 40 to 100 m / min, optionally 60 to 80 m / min, including but not limited to any one of 40 m / min, 45 m / min, 50 m / min, 55 m / min, 60 m / min, 65 m / min, 70 m / min, 75 m / min, 80 m / min, 85 m / min, 90 m / min, 95 m / min, and 100 m / min, or a range of values ​​between any two of them. The pole piece of the embodiment of the present application moves rapidly relative to the flame, and the pole piece has a short residence time under the flame, thereby achieving rapid and instantaneous heating of the pole piece, and controlling the temperature of the active layer in the pole piece during the flame heating process within the desired range. In actual operation, the pole piece can be placed on an unwinding guide roller and a winding guide roller, and the pole piece is pulled by a winding guide rail, so as to achieve movement of the pole piece relative to the flame. By controlling the tape speed on the unwinding guide roller and the winding guide roller, the movement speed of the pole piece relative to the flame can be adjusted.

[0106] In some embodiments, during the flame heating treatment step, the surface temperature of the active layer is 180-500°C, optionally 300-500°C, including but not limited to any one of 180°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, and 500°C, or a range of values ​​between any two of them. The surface temperature of the active layer can be measured by an infrared temperature measurement module or other temperature tester. These temperature ranges are greater than or equal to the softening temperature or melting temperature of common electrode adhesives, and less than the lowest temperature of the decomposition temperature, oxidation temperature, and ignition temperature of common electrode active materials. The adhesive floating on the surface of the electrode can be effectively softened (melted) or ablated, while improving the decomposition, oxidation, or combustion of the active material during the flame heating treatment, maintaining the lattice stability of the active material and the structural stability of the electrode.

[0107] In some embodiments, before flame heating treatment, the porosity of the electrode sheet is 25% to 32%, including but not limited to any one of 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32% or any range between two values. Generally, the positive electrode sheet and the negative electrode sheet have different porosities due to the density and particle size of the active material, the type of binder used, or other factors. For the positive electrode sheet, its porosity before flame heating can be 30% to 32%, including but not limited to any one of 30%, 31%, 32% or any range between two values. For the negative electrode sheet, its porosity before flame heating treatment can be 25% to 28%, including but not limited to any one of 25%, 26%, 27%, 28% or any range between two values. The porosity of the electrode can be calculated using the apparent volume and true volume of the electrode, i.e., porosity = (V0-V) / V*100%, where V0 is the apparent volume of the electrode and V is the true volume of the electrode. The method of the embodiment of the present application is applicable to treating electrode pieces with different porosities. Flame heating can increase the porosity of the electrode piece, thereby improving the electrolyte wettability of the electrode piece.

[0108] In some embodiments, before flame heating, the electrode sheet has a sheet resistance of 0.001 to 0.5 Ω, including but not limited to any one of 0.001 Ω, 0.002 Ω, 0.005 Ω, 0.01 Ω, 0.05 Ω, 0.1 Ω, 0.2 Ω, 0.3 Ω, 0.4 Ω, and 0.5 Ω, or a range between any two of them. Typically, the positive electrode sheet and the negative electrode sheet have different sheet resistances. For the positive electrode sheet, its sheet resistance before flame heating is typically 0.001 to 0.01 Ω, including but not limited to any one of 0.001 Ω, 0.002 Ω, 0.005 Ω, and 0.01 Ω, or a range between any two of them. For the negative electrode, its membrane resistance before flame heating is generally 0.1 to 0.5Ω, including but not limited to any one of 0.1Ω, 0.2Ω, 0.3Ω, 0.4Ω, and 0.5Ω, or a range of values ​​between any two of them. The membrane resistance of the electrode can be directly measured using a membrane resistance meter. The method of the embodiment of the present application is applicable to processing electrodes with different membrane resistances. The flame heating treatment can improve the structure of the electrode, for example, increase the porosity of the electrode, which is conducive to reducing the membrane resistance of the electrode.

[0109] In some embodiments, before flame heating, the bonding strength of the electrode sheet is 18 to 23 N / m, including but not limited to any one of 18 N / m, 19 N / m, 20 N / m, 21 N / m, 22 N / m, and 23 N / m, or a range of values ​​therebetween. Typically, the positive electrode sheet and the negative electrode sheet have different bonding strengths due to the different types of binders used or other factors. For the positive electrode sheet, the bonding strength before flame heating can be 18 to 20 N / m, including but not limited to any one of 18 N / m, 19 N / m, and 20 N / m, or a range of values ​​therebetween. For the negative electrode sheet, the bonding strength before flame heating can be 20 to 23 N / m, including but not limited to any one of 20 N / m, 21 N / m, 22 N / m, and 23 N / m, or a range of values ​​therebetween. The bonding strength of the electrode sheet reflects the bonding strength between the active material, binder, conductive agent, current collector, and other components in the electrode sheet. The electrode can be bonded to the surface of the substrate, and a tensile test is performed on the electrode using a tensile test machine. The displacement and force during the entire process of peeling the electrode from the substrate are recorded to obtain the force when the force is balanced. This force is generally considered to be the bonding force of the electrode. The method of the embodiment of the present application is applicable to processing electrode pieces with different bonding forces. After flame heating treatment, the bonding force of the electrode is improved or maintained at a considerable level. That is, the electrode after flame heating treatment will still have good bonding force and can meet the requirements.

[0110] In some embodiments, the binder includes one or more of an oil-soluble binder, a water-soluble binder, and an emulsion-type binder. The oil-soluble binder includes, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polyimide (PI), polytetrafluoroethylene (PTFE), polybutyl acrylate (PBA), and polyacrylonitrile (PAN). The water-soluble binder includes, but is not limited to, one or more of carboxymethyl cellulose (CMC), carboxymethyl cellulose salt, polyacrylic acid (PAA), polyacrylate, polyvinyl alcohol (PVA), sodium alginate (SA), and cyclodextrin (CD). The emulsion-type binder includes, but is not limited to, one or more of styrene-butadiene rubber (SBR), vinyl acetate resin, acrylic resin (EVA), and chlorinated rubber (CR). Different binders can be selected according to the type of active material in the electrode, and the temperature during flame heating is determined based on the softening temperature or melting temperature of the binder.

[0111] In some embodiments, the mass content of the binder in the active layer includes but is not limited to 0.5% to 10%, optionally 1% to 5%, for example, any one of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10% or a range between any two of them, and can also be set to other contents as needed.

[0112] In some embodiments, the electrode sheet includes either or both of a positive electrode sheet and a negative electrode sheet. Both positive and negative electrode sheets experience the phenomenon of binder floating during drying. The methods of the present invention are applicable to both positive and negative electrode sheets.

[0113] In some embodiments, the electrode is a positive electrode, and the active material includes one or more of a metal inorganic active material and an organic active material. The metal inorganic active material includes, but is not limited to, one or more of lithium iron phosphate, lithium manganese phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide (nickel cobalt manganese ternary material), and lithium nickel cobalt aluminum oxide (nickel cobalt aluminum ternary material). The organic active material includes, but is not limited to, one or more of a quinone compound, a carboxylate compound, an anhydride compound, and an amide compound.

[0114] In some embodiments, the electrode is a negative electrode, and the active material includes one or more of a carbon-based active material, a titanium-based active material, a silicon-based active material, a nitride, and metallic lithium. Carbon-based materials include, but are not limited to, one or more of graphite (natural graphite, artificial graphite), hard carbon, soft carbon, mesocarbon microspheres, and graphene. Titanium-based active materials include, but are not limited to, one or more of lithium titanate and titanium dioxide. Silicon-based active materials include, but are not limited to, one or more of silicon and silicon dioxide. Nitrides include, but are not limited to, lithium nitride.

[0115] In some embodiments, the mass content of the active substance in the active layer includes but is not limited to 90% to 98%, optionally 95% to 98%, for example, any point value of 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or a range value between any two of them, and can also be set to other contents as needed.

[0116] In some embodiments, the active layer further includes a conductive agent, which is used to collect microcurrents between the active materials and between the active materials and the current collector, thereby improving electronic conductivity. The conductive agent can also promote the infiltration of the electrolyte into the electrode.

[0117] In some embodiments, the conductive agent includes one or more of acetylene black (SP), carbon nanotubes, conductive carbon black (super-P), Ketjen black, carbon fiber, and graphene.

[0118] In some embodiments, the mass content of the conductive agent in the active layer includes but is not limited to 0.5% to 10%, optionally 1% to 5%, for example, any one of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10% or a range between any two of them, and can also be set to other contents as needed.

[0119] In some embodiments, the active layer may further include a thickener, such as carboxymethyl cellulose (CMC). The mass content of the thickener in the active layer includes, but is not limited to, 0.5% to 5%, optionally 1% to 5%, including but not limited to any one of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%, or a range therebetween. Other content levels may also be used as needed.

[0120] In some embodiments, the electrode sheet further includes a current collector, with the active layer disposed on at least one side of the current collector. The current collector on the electrode sheet serves as a substrate for the active layer to attach to and transports electrons during the battery's chemical reactions. Current collectors include, but are not limited to, metal current collectors, carbon current collectors, conductive resin current collectors, and metal-resin composite current collectors. More specifically, examples include copper, aluminum, nickel, titanium, iron, and their respective alloys, stainless steel, carbon fiber, carbon nanotubes (CNTs), and graphite.

[0121] In some embodiments, before the flame heating step, the electrode piece is subjected to any one or both of a drying process and a roller pressing process.

[0122] During the electrode manufacturing process, the active material is typically mixed with a binder, conductive agent, solvent, and other necessary components to form a slurry. This slurry is then coated onto a current collector and dried to form the active layer. During the drying process, the solvent evaporates, and the binder migrates to the surface of the active layer, causing the binder to float, which can lead to various problems that are detrimental to the electrode's electrochemical performance.

[0123] Typically, after drying, a roll pressing step is also performed. Roll pressing methods typically include cold pressing and hot pressing. Roll pressing can enhance the internal bonding strength of the electrode sheet and achieve the desired compaction density. The roll pressing step can be performed after the drying step and before the flame heating step.

[0124] The method of the embodiment of the present application performs flame heating treatment on the electrode after drying and / or rolling treatment, which can solve the problem of adhesive floating during the drying process and improve the electrolyte infiltration performance of the electrode.

[0125] In some embodiments, after the flame heating step, a cooling step is included for the electrode. Cooling methods include, but are not limited to, air cooling and circulating water cooling. Cooling the electrode can reduce its temperature, facilitating subsequent processing of the electrode, such as winding the electrode.

[0126] A third aspect of an embodiment of the present application provides a pole piece, the porosity of the pole piece is 30% to 50%, optionally 30% to 47%.

[0127] In some embodiments, the liquid absorption rate of the electrode piece can be 0.3 μg / s to 12 μg / s, including but not limited to any point value among 0.3 μg / s, 0.4 μg / s, 0.5 μg / s, 0.8 μg / s, 1 μg / s, 2 μg / s, 3 μg / s, 5 μg / s, 8 μg / s, 9 μg / s, 10 μg / s, 11 μg / s, 12 μg / s, etc., or a range of values ​​between any two points. Specifically, for the positive electrode piece, the liquid absorption rate can be 0.3 μg / s to 0.5 μg / s; for the negative electrode piece, the liquid absorption rate can be 9 μg / s to 12 μg / s.

[0128] In some embodiments, the sheet resistance of the electrode sheet may be 0.001Ω to 0.43Ω, including but not limited to any one of 0.001Ω, 0.0015Ω, 0.0018Ω, 0.002Ω, 0.008Ω, 0.01Ω, 0.05Ω, 0.08Ω, 0.1Ω, 0.2Ω, 0.25Ω, 0.3Ω, 0.35Ω, 0.38Ω, 0.4Ω, 0.41Ω, 0.42Ω, 0.43Ω, etc., or a range between any two of the values. Specifically, for the positive electrode sheet, the sheet resistance may be 0.0016Ω to 0.002Ωs; for the negative electrode sheet, the sheet resistance may be 0.39Ω to 0.43Ω.

[0129] In some embodiments, the bonding force of the electrode sheet can be 18 to 23 N / m, including but not limited to any one of 18 N / m, 19 N / m, 20 N / m, 21 N / m, 22 N / m, and 23 N / m, or any range therebetween. Specifically, for the positive electrode sheet, the bonding force is 18 to 20 N / m; for the negative electrode sheet, the bonding force is 20 to 23 N / m.

[0130] In some embodiments, the electrode sheet includes a positive electrode sheet, and the porosity of the positive electrode sheet is 35% to 50%, the liquid absorption rate is 0.3 μg / s to 0.5 μg / s, the membrane resistance is 0.0016Ω to 0.002Ω, and the bonding force is 18 to 20 N / m; or, the electrode sheet includes a negative electrode sheet, and the porosity of the negative electrode sheet is 30% to 35%, the liquid absorption rate is 9 μg / s to 12 μg / s, the membrane resistance is 0.39Ω to 0.43Ω, and the bonding force is 20 to 23 N / m.

[0131] In some embodiments, the electrode pieces of the embodiments of the present application are processed according to the method for processing electrode pieces of the second aspect.

[0132] Due to differences in material type and content between the positive and negative electrode sheets, as well as other factors, the positive and negative electrode sheets have different porosities after flame heating. Specifically, the electrode sheet is a positive electrode sheet, and the porosity of the positive electrode sheet is 35% to 50%, including but not limited to any one of 35%, 36%, 37%, 38%, 39%, 40%, 42%, 44%, 46%, 48%, and 50%, or any range therebetween.

[0133] Alternatively, the electrode is a negative electrode, and the porosity of the negative electrode is 30% to 35%, including but not limited to any one of 30%, 31%, 32%, 33%, 34%, 35% or a range between any two of them.

[0134] After flame heating treatment, the adhesive floating on the surface of the electrode is softened (melted) or ablated, and the electrode exposes more capillaries. Therefore, the treated electrode has a high porosity, which is beneficial to increase the channels for electrolyte infiltration in the electrode, making it easier for the electrolyte to infiltrate the electrode, thereby improving the electrolyte wettability of the electrode.

[0135] In some embodiments, the porosity of the electrode sheet of the embodiment of the present application is increased by 14% or more compared to that before flame heating treatment, for example, by 14% to 50%, including but not limited to any one of 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, and 50%, or a range of values ​​therebetween. Corresponding to the porosity, after flame heating treatment, the porosity change rate of the positive electrode sheet and the negative electrode sheet is also different. For the positive electrode sheet, the porosity is increased by 19% to 50% compared to before the flame heat treatment, and optionally 40% to 50%, including but not limited to any one of 19%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, and 50%, or a range between any two of them. For the negative electrode sheet, the porosity is increased by 14% to 26%, and optionally 22% to 26%, including but not limited to any one of 14%, 16%, 18%, 20%, 22%, 24%, and 26%, or a range between any two of them, compared to before the flame heat treatment.

[0136] In some embodiments, the electrode of the embodiment of the present application has an electrolyte absorption rate increased by 18% or more compared to before flame heating treatment, optionally increased by 18% to 100%, including but not limited to any point value of 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, or any range therebetween. Due to the influence of different porosities, the rate of change of the electrolyte absorption rate of the positive electrode and the negative electrode also varies. For the positive electrode plate, the liquid absorption rate of the electrolyte is increased by 34% to 100% compared to before the flame heating treatment, and optionally increased by 78% to 100%, including but not limited to any point value of 34%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 78%, 80%, 85%, 90%, 95%, 100%, or any range value between two of them. For the negative electrode plate, the liquid absorption rate of the electrolyte is increased by 18% to 40% compared to before the flame heating treatment, and optionally increased by 34% to 40%, including but not limited to any point value of 18%, 20%, 25%, 30%, 35%, 40%, or any range value between two of them. The electrode of the embodiment of the present application has a high porosity, which enables it to absorb the electrolyte very quickly.

[0137] In some embodiments, the electrode of the embodiment of the present application has a diaphragm resistance reduced by more than 8% compared to before flame heating treatment, optionally reduced by 8% to 30%, including but not limited to any point value of 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, or a range of values ​​between any two. The rate of change of the diaphragm resistance of different electrodes is also different. For the positive electrode, the diaphragm resistance is reduced by 16% to 30% compared to before flame heating treatment, optionally reduced by 25% to 30%, including but not limited to any point value of 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, or a range of values ​​between any two. For the negative electrode, the sheet resistance is reduced by 8% to 15% compared to before the flame heat treatment, and optionally by 12% to 15%, including but not limited to any of 8%, 10%, 12%, 14%, and 15%, or any range therebetween. After the flame heat treatment, the sheet resistance of the electrode is improved.

[0138] A fourth aspect of an embodiment of the present application provides a battery, which includes the electrode according to the third aspect.

[0139] The battery of the embodiment of the present application includes the above-mentioned electrode sheet, which can be either a positive electrode sheet or a negative electrode sheet, or can include both positive and negative electrode sheets. Because the floating binder in the battery electrode sheet is softened (melted) and ablated, the electrode sheet has a higher porosity, which is conducive to improving the wettability of the electrolyte to the electrode sheet, thereby helping to improve the electrochemical performance of the battery.

[0140] In some embodiments, the battery of the present invention includes one or more primary batteries and secondary batteries. Batteries can be divided into primary batteries and secondary batteries based on whether they can be recharged and reused. Primary batteries cannot be recharged to restore their original state after discharge, while secondary batteries can be recharged to activate their active materials and continue to be used after discharge. The electrode of the present invention can be applied to both primary and secondary batteries, thus having a wide range of applications.

[0141] In some embodiments, the battery of the embodiments of the present application includes one or more of a battery cell, a battery module, and a battery pack. In the case where the battery is a secondary battery, the secondary battery is divided into a battery cell, a battery module, and a battery pack according to different packaging forms. Among them, the battery cell is the most basic unit of a secondary battery, including an electrode assembly and an electrolyte. The electrode assembly usually includes a positive electrode sheet, a negative electrode sheet, and an insulator. The battery cell mainly relies on the movement of metal ions in the electrolyte between the positive electrode sheet and the negative electrode sheet to work. In some battery packaging technologies, one or more battery cells can be integrated into a battery module first, and then one or more battery modules can be installed in the battery box to form a battery pack. In other battery packaging technologies, one or more battery cells can also be directly installed in the box to form a battery pack, eliminating the intermediate state of the battery module, thereby reducing the mass of the battery pack and increasing the energy density of the battery.

[0142] In some embodiments, the battery further comprises an electrolyte, which can serve as a carrier for ion transport in the battery.

[0143] In some embodiments, the electrolyte may be an electrolyte solution, which may include a solvent and a lithium salt dissolved in the solvent. The electrolyte may also include a solid electrolyte, such as a polymer electrolyte, an inorganic solid electrolyte, etc., but is not limited thereto.

[0144] The solvent in the electrolyte may include a non-aqueous organic solvent, for example, one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB) and ethyl butyrate (EB).

[0145] The lithium salt may include one or more of LiPF6 (lithium hexafluorophosphate), LiBF4 (lithium tetrafluoroborate), LiClO4 (lithium perchlorate), LiAsF6 (lithium hexafluoroarsenate), LiFSI (lithium bis(fluorosulfonyl)imide), LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluorooxalatoborate), LiBOB (lithium bis(oxalatoborate), LiPO2F2 (lithium difluorophosphate), LiDFOP (lithium difluorooxalatophosphate) and LiTFOP (lithium tetrafluorooxalatophosphate), for example, one or more of LiPF6 (lithium hexafluorophosphate), LiBF4 (lithium tetrafluoroborate), LiBOB (lithium bis(oxalatoborate), LiDFOB (lithium difluorooxalatoborate), LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and LiFSI (lithium bis(fluorosulfonyl)imide).

[0146] The electrolyte may also optionally contain other additives, such as vinylene carbonate (VC), vinyl ethylene carbonate (VEC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethylethylene carbonate (TFPC), succinonitrile (SN), adiponitrile (ADN), glutaronitrile (GLN), hexanetrinitrile (HTN), 1,3-propane sultone (1,3-PS), vinyl sulfate (DTD), methylene disulfonate (MMDS), 1-propylene-1,3-sultone (PST), 4-methylethylene sulfate (PCS), 4-ethylethylene sulfate (PES), 4-propylethylene sulfate (PEGLST), propylene sulfate (TS), 1,4-butane sultone (1,4-BS), ethylene sulfite (DTO), dimethyl sulfite (DMS), diethyl sulfite (DES), sulfonate cyclic quaternary ammonium salt, tris(trimethylsilyl) phosphate (TMSP) and tris(trimethylsilyl) borate (TMSB), but are not limited thereto.

[0147] In some embodiments, the battery further includes a separator stacked between the positive electrode and the negative electrode. In some batteries, a separator is required to separate the positive and negative electrodes, preventing electrons from freely passing through the battery and short-circuiting the electrodes while allowing ions in the electrolyte to pass freely between the positive and negative electrodes.

[0148] The diaphragm can be any known porous structure separator with electrochemical stability and mechanical stability, such as single-layer or multi-layer films of one or more of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP) and polyvinylidene fluoride (PVDF).

[0149] The positive and negative electrode sheets are alternately stacked, and a separator is provided between the positive and negative electrode sheets to serve as an isolation function, thereby obtaining a bare cell, or a bare cell after winding. The cell is placed in a casing, injected with electrolyte, and sealed to obtain a battery cell. One or more battery cells are integrated to form a battery module, which can provide higher voltage and capacity and have a specific functional output; then one or more battery modules are installed in a battery box, and a battery management system is usually added to form a battery pack, which is usually a product provided to users. Alternatively, one or more battery cells can be directly installed in the box to form a battery pack.

[0150] Referring to Figure 2 , an example battery module 4 is shown. Within the battery module 4 , multiple battery cells 5 may be arranged sequentially along the length of the battery module 4 . Alternatively, the arrangement may be arranged in any other manner. Furthermore, the multiple battery cells 5 may be secured together using fasteners.

[0151] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0152] Refer to Figures 3 and 4, which illustrate an example battery pack 1. The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be positioned over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0153] In some embodiments, the battery may include an outer packaging that can be used to encapsulate the electrode assembly consisting of the positive electrode sheet, the negative electrode sheet, the separator, and the electrolyte.

[0154] The battery outer packaging can be a hard shell, such as a hard plastic shell, aluminum shell, or steel shell; or a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0155] The shape of the battery can be cylindrical, square or any other shape. For example, FIG5 is an example of a square battery.

[0156] In some embodiments, referring to FIG6 , the outer packaging may include a housing 51 and a cover plate 53 . The housing 51 may include a bottom plate and side plates connected to the bottom plate, which together form a housing cavity. The housing 51 has an opening communicating with the housing cavity, and the cover plate 53 can be positioned over the opening to seal the housing cavity. The positive electrode sheet, the negative electrode sheet, and the separator may be wound or laminated to form an electrode assembly 52 . One or more electrode assemblies 52 are encapsulated within the housing cavity. Electrolyte is infiltrated into the electrode assembly 52 .

[0157] An embodiment of the present application further provides an electrical device, which includes the above-mentioned battery.

[0158] The battery disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources, or various energy storage systems that use batteries as energy storage elements to provide electrical energy. Electrical devices may include but are not limited to mobile phones, tablets, laptops, electric toys, power tools, battery cars, electric cars, ships, spacecraft, and the like. Among them, electric toys may include fixed or mobile electric toys, for example, game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, and the like. As the electrical device, a battery cell, a battery module, or a battery pack in the battery can be selected according to its usage requirements.

[0159] Figure 7 shows an example of an electric device. This device can be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the battery, a battery pack or battery module can be used.

[0160] The following describes the details in conjunction with specific embodiments.

[0161] Example A1

[0162] This embodiment provides a pole piece processing system. Referring to FIG1 , the pole piece processing system includes:

[0163] A conveying unit 20 for conveying the pole piece 10, the conveying unit 20 comprising an unwinding guide roller 21 and a winding guide roller 22;

[0164] The flame heating unit 30 includes a spray gun burner (hereinafter referred to as the spray gun), which uses natural gas (premixed with air) as gas fuel, is used to spray out premixed combustion flames, and flame heats the pole piece 10. The spray gun includes a spray gun nozzle, and the premixed natural gas-air mixture is burned and then sprayed out through the spray gun nozzle to spray out premixed combustion flames. The size of the spray gun nozzle is: 2 to 3 cm wide and 5 to 20 cm long. The size of the spray gun nozzle can be adjusted as needed. Corresponding to the shape of the spray gun nozzle, the premixed combustion flame sprayed out of the spray gun nozzle has a rectangular cross-section, and the size of the rectangular cross-section corresponds to the size of the spray gun nozzle. In the pole piece heating system of this embodiment, two spray guns using the same combustion conditions are provided, and the two are equidistantly located on both sides of the surface of the pole piece 10, and the premixed combustion flames generated by the two are perpendicular to the surface of the pole piece 10.

[0165] The electrode processing system of this embodiment further includes: a drying unit, a rolling unit, a cooling unit, and a temperature measuring unit (the drying unit, rolling unit, cooling unit, and temperature measuring unit are not shown in FIG1 ). The drying unit, rolling unit, flame heating unit 30, and cooling unit are arranged in sequence in the direction of electrode conveyance (direction D in FIG1 ).

[0166] The drying unit is used to dry the electrode sheet coated with electrode slurry, the rolling unit rolls the electrode sheet after the drying unit, and the cooling unit cools the electrode sheet after the flame heating treatment to facilitate the winding guide roller 22 to wind up the electrode sheet 10. The temperature measuring unit measures the temperature of the electrode sheet 10 during the flame heating treatment.

[0167] In this embodiment, the electrode processing system further includes an automatic temperature control unit (not shown in FIG. 1 ), which is used to control the combustion conditions of the spray gun according to the temperature of the electrode 10 measured by the temperature measuring unit.

[0168] The workflow of the electrode processing system of this embodiment includes:

[0169] The electrode slurry is coated on the current collector, dried in a drying unit, and rolled in a rolling unit to form a pole piece 10 having a dry active layer. The pole piece 10 is quickly conveyed by a conveying unit 20 through the flame generated by the spray gun, thereby achieving flame heating treatment of the pole piece 10.

[0170] During the flame heating process, the temperature measuring unit monitors the temperature of the electrode 10 in real time; at the same time, the automatic temperature control unit receives the temperature data of the electrode 10 measured by the temperature measuring unit, and adjusts the combustion conditions of the spray gun according to the data to maintain the temperature of the electrode 10 within the required temperature range.

[0171] Example B1

[0172] This embodiment provides a method for processing a positive electrode sheet, which is to process the positive electrode sheet in the sheet processing system of embodiment A1, specifically comprising the following steps:

[0173] 1) Preparation of positive electrode sheet

[0174] Nickel-cobalt-manganese (NCM) ternary material, conductive agent carbon black, polyvinylidene fluoride (PVDF), and N-methylpyrrolidone (NMP) are stirred and mixed in a mass ratio of 96.9:2:1:21 to obtain a positive electrode slurry; the positive electrode slurry is then evenly coated on the positive electrode current collector aluminum foil, and then dried, cold pressed, and cut to obtain a positive electrode sheet.

[0175] 2) Flame heating treatment of positive electrode

[0176] The resulting positive electrode plates were flame-heated using the plate processing system shown in Figure 1. During the treatment, a premixed combustion flame generated by a spray gun contacted the positive electrode plates. The air flow rate in the spray gun was 250 L / min, the natural gas flow rate was 6 L / min, the air-fuel ratio was 3, and the flame temperature was 600°C. The plate feed speed was controlled at 100 m / min. The plate temperature and carbon deposits on the plate surface were recorded during the feed process.

[0177] Example B2

[0178] This embodiment provides a method for processing a positive electrode sheet, which differs from embodiment B1 only in that: step 2) controlling the sheet conveying speed to be 80 m / min. Other steps are the same as embodiment B1.

[0179] Example B3

[0180] This embodiment provides a method for processing a positive electrode sheet, which differs from embodiment B1 only in that: step 2) controlling the sheet conveying speed to be 60 m / min. Other steps are the same as embodiment B1.

[0181] Example B4

[0182] This embodiment provides a method for processing a positive electrode sheet, which differs from embodiment B1 only in that: step 2) controlling the sheet conveying speed to be 40 m / min. Other steps are the same as embodiment B1.

[0183] Comparative Example B1

[0184] This comparative example provides a method for processing a positive electrode plate, which differs from Example B1 only in that the positive electrode plate is not subjected to the flame heating treatment in step 2).

[0185] Comparative Example B2

[0186] This comparative example provides a method for processing a positive electrode sheet, which differs from Example B1 only in that: Step 2) controls the sheet conveying speed to 10 m / min. Other steps are the same as Example B1.

[0187] In this comparative example, the electrode was burned during the processing.

[0188] Comparative Example B3

[0189] This comparative example provides a method for processing a positive electrode sheet. The only difference from Example B1 is that the spray gun is replaced with an alcohol lamp, the flame (outer flame) temperature of the alcohol lamp is 400°C, and the electrode sheet conveying speed is controlled to 10 m / min. Other aspects are the same as Example B1.

[0190] In this comparative example, the combustion of the alcohol lamp is diffusion combustion, and the flame formed is clearly divided into the flame core, inner flame, and outer flame. Considering the low flame temperature of the alcohol lamp, during the treatment of the positive electrode, the electrode conveying speed is controlled at a low speed of 10m / min to increase the contact time between the electrode and the flame, thereby increasing the electrode temperature during the flame heating process.

[0191] Example C1

[0192] This embodiment provides a method for processing a negative electrode sheet, which is to process the negative electrode sheet in the sheet processing system of embodiment A1, specifically comprising the following steps:

[0193] 1) Preparation of negative electrode sheet

[0194] The active material artificial graphite, the conductive agent carbon black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) are dissolved in the solvent deionized water in a mass ratio of 96.2:0.8:0.8:1.2, and mixed evenly to prepare a negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector copper foil once or multiple times, and the negative electrode sheet is obtained after drying, cold pressing, and slitting.

[0195] 2) Flame heating treatment of negative electrode

[0196] The obtained negative electrode plate was flame treated using the processing system shown in Figure 1. During the treatment process, the premixed combustion flame generated by the spray gun came into contact with the negative electrode plate. The air flow rate in the spray gun was 180L / min, the natural gas flow rate was 6L / min, the air-fuel ratio was 4, and the flame temperature was 800℃. The electrode plate conveying speed was controlled to be 100m / min, and the electrode plate temperature during the conveying process and the carbon deposition on the electrode plate surface were recorded.

[0197] Example C2

[0198] This embodiment provides a method for processing a negative electrode sheet, which differs from embodiment C1 only in that: step 2) controlling the sheet conveying speed to be 80 m / min. Other steps are the same as embodiment C1.

[0199] Example C3

[0200] This embodiment provides a method for processing a negative electrode sheet, which differs from embodiment C1 only in that: step 2) controlling the sheet conveying speed to be 60 m / min. Other steps are the same as embodiment C1.

[0201] Example C4

[0202] This embodiment provides a method for processing a negative electrode sheet, which differs from embodiment C1 only in that: step 2) controlling the sheet conveying speed to be 40 m / min. Other steps are the same as embodiment C1.

[0203] Comparative Example C1

[0204] This comparative example provides a method for processing a negative electrode plate, which differs from Example C1 only in that the negative electrode plate is not subjected to the flame heating treatment in step 2).

[0205] Comparative Example C2

[0206] This comparative example provides a method for processing a positive electrode sheet, which differs from Example C1 only in that: Step 2) controls the sheet conveying speed to 10 m / min. Other steps are the same as Example C1.

[0207] In this comparative example, the electrode was burned during the processing.

[0208] The electrode treatment conditions for each embodiment and comparative example are shown in Table 1. The electrode temperature (specifically, the active layer temperature) and electrode carbon deposition during the treatment process for each embodiment and comparative example are shown in Table 2. The "active layer surface temperature" in Table 2 refers to the active layer surface temperature approximately 6 cm downstream of the flame heating (also the electrode surface temperature). The active layer surface temperature approximately 6 cm downstream was selected for ease of temperature measurement and, since this area is very close to the flame heating area, the measured temperature can be considered equivalent to the active layer surface temperature during flame heating.

[0209] The performance tests of the treated electrodes of the embodiments and comparative examples were conducted, including the electrolyte absorption rate, porosity, membrane resistance, adhesion, etc. The results are shown in Table 3 below.

[0210] Table 1. Pole processing conditions of various embodiments and comparative examples

[0211] Table 2. Surface temperature of the pole piece and carbon deposition of the pole piece in each embodiment and comparative example

[0212] Table 3. Pole performance test results

[0213] The data in Table 3 were processed to obtain the change rates of various properties of the electrode pieces after treatment in each embodiment and comparative example compared with the electrode pieces without treatment, as shown in Table 4.

[0214] Table 4. Change rate of pole piece performance of each embodiment and comparative example

[0215] In Table 4, the change rates of Examples B1 to B4 and Comparative Examples B1 to B3 are the change rates compared with Comparative Example B1, and the change rates of Examples C1 to C4 and Comparative Examples C1 to C2 are the change rates compared with Comparative Example C1.

[0216] For example:

[0217] Liquid absorption rate change rate of the electrode piece of Example B1 = (liquid absorption rate of the electrode piece of Example B1 - liquid absorption rate change rate of the electrode piece of Comparative Example B1) / liquid absorption rate change rate of the electrode piece of Comparative Example B1 * 100%;

[0218] Liquid absorption rate change rate of the electrode piece of Example B2 = (liquid absorption rate of the electrode piece of Example B2 - liquid absorption rate change rate of the electrode piece of Comparative Example B1) / liquid absorption rate change rate of the electrode piece of Comparative Example B1 * 100%;

[0219] Liquid absorption rate change rate of the electrode piece of Example C1 = (liquid absorption rate of the electrode piece of Example C1 - liquid absorption rate change rate of the electrode piece of Comparative Example C1) / liquid absorption rate change rate of the electrode piece of Comparative Example C1 * 100%;

[0220] The liquid absorption rate change rate of the embodiment C2 electrode = (the liquid absorption rate of the embodiment C2 electrode - the liquid absorption rate change rate of the comparative example C1 electrode) / the liquid absorption rate change rate of the comparative example C1 electrode * 100%.

[0221] The change rates of other items are calculated in the same way.

[0222] The test results show:

[0223] After flame heating under appropriate conditions, the electrode plates of Examples B1 to B4 and Examples C1 to C4 exhibited significantly improved liquid absorption rates compared to those before flame heating. Specifically, the positive electrode plates of Examples B1 to B4 exhibited increased liquid absorption rates of over 34%, and even as high as 100%, after flame heating. The negative electrode plates of Examples C1 to C4 also exhibited increased liquid absorption rates of over 18%. This significant increase in liquid absorption rate reflects the significant improvement in electrolyte wettability of the electrode plates after flame heating.

[0224] Combined with the change in the porosity of the electrode, it can be found that one of the reasons for the increase in the liquid absorption rate of the electrode is that the porosity of the electrode is improved after the flame heating treatment. The increase in porosity is mainly due to the fact that during the flame heating process, the binder that floats to the surface of the electrode is softened (melted) or ablated by heat, exposing more capillaries in the electrode and increasing the channels for the electrolyte to infiltrate the electrode. Moreover, during the flame combustion treatment, a premixed combustion flame is generated by a spray gun, so that no carbon deposits are formed on the surface of the electrode to cause pore blockage (for example, the negative electrode of the comparative example C1 is found to have a C content of 99.19wt% and an O content of 0.81wt% by X-ray energy spectrometer EDS testing; and the negative electrode of the embodiment C3 is not observed to have carbon deposits on its appearance after the flame heating treatment, and the EDS test shows that its C content is 99.22wt% and the O content is 0.78wt%, which is equivalent to before the flame heating treatment), which is conducive to further improving the porosity of the electrode. Therefore, in Examples B1 to B4 and Examples C1 to C4, by performing appropriate flame heating treatment on the electrode pieces, the porosity of the electrode pieces can be effectively increased, thereby improving the wettability of the electrode pieces by the electrolyte.

[0225] At the same time, corresponding to the porosity of the electrode, within a certain range, as the porosity of the electrode increases, the diaphragm resistance of the electrode also gradually decreases. For example, after the positive electrode in Example B1 to Example B4 is flame-heated, the reduction rate of its diaphragm resistance is reduced by more than 16% compared with that before the flame heating treatment, and the highest can be close to 30%; after the negative electrode in Example C1 to Example C4 is flame-heated, the reduction rate of its diaphragm resistance is reduced by more than 8% compared with that before the flame heating treatment, and the highest can be close to 15%. The diaphragm resistance of the electrode is affected by the surface morphology of the electrode. After the electrode is flame-heated under certain conditions, the surface morphology of the electrode changes, such as the porosity is increased. In addition to improving the wettability of the electrolyte to the electrode, this can also greatly reduce the diaphragm resistance of the electrode and improve the electrochemical performance of the electrode.

[0226] In addition, the test results show that after flame heating treatment under appropriate conditions, the electrode still has good adhesion.

[0227] In contrast, when flame heating is performed on the electrode under inappropriate conditions, such as in Comparative Examples B2 and C2, the electrode surface temperature is too high (higher than the lowest of the decomposition temperature, oxidation temperature, and ignition temperature of the active material in the electrode), resulting in burnout and damage. For another example, in Comparative Example B3, the electrode surface temperature is too low (lower than the softening or melting temperature of the active material in the binder) after flame heating. The electrode's liquid absorption rate changes very little compared to before flame heating. At the same time, its porosity decreases compared to that of the electrode without flame heating, and the membrane resistance increases.

[0228] In summary, during the flame heating process of the electrode, controlling the electrode temperature within a certain range can effectively improve the porosity of the electrode, thereby improving the wettability of the electrode by the electrolyte, and is beneficial to increasing the diaphragm resistance of the electrode.

[0229] Appendix: The above-mentioned related performance test methods are as follows:

[0230] (1) Electrode electrolyte absorption rate

[0231] Fix the electrode on a clean glass plate, use a 0.2mm (inner diameter) capillary to absorb 3mm height of electrolyte (the electrolyte composition includes EC, DMC and EMC with a volume ratio of 3:2:1, and 1mol / L lithium salt LiPF6), and then vertically contact the electrode to allow the electrode to absorb the electrolyte. Measure the time for the electrolyte to be completely absorbed, and obtain the electrolyte absorption rate by conversion.

[0232] (2) Electrode porosity

[0233] In a drying room, use tweezers to select >20 round electrodes with good appearance and no powder falling on the edges and place them into the sample cup. Record the number of electrodes and calculate the apparent volume of all electrodes. Place the sample cup containing the sample in a true density tester, close the test system, and introduce helium according to the procedure. By detecting the pressure of the gas in the sample chamber and expansion chamber, and then calculating the true volume of all electrodes according to Bohr's law (PV=nRT), the porosity of the sample to be tested is obtained [porosity=(V0-V) / V*100%, where V0 is the apparent volume of the electrode and V is the true volume of the electrode].

[0234] (3) Diaphragm resistance

[0235] Use a Yuanneng Technology Sheet Resistance Tester to test the sheet resistance. Cut small 10mm diameter discs from the left, center, and right sides of the electrode. Turn on the Yuanneng Technology Sheet Resistance Tester's indicator light, position the probe appropriately, click the "Start" button, and wait for the display to stabilize before reading. Test two locations on each disc. Calculate the average of the six measurements to determine the sheet resistance for that electrode.

[0236] (4) Adhesion

[0237] Cut the pole piece into 20*100mm 2 The test specimens of different sizes are kept aside; the double-sided tape is used to stick to the side of the specimen that needs to be tested, and it is compacted with a pressure roller to make the double-sided tape fit the specimen completely; the other side of the double-sided tape of the specimen is stuck to the stainless steel surface, and one end of the specimen is bent in the opposite direction with a bending angle of 180°; a high-speed rail tensile testing machine is used for testing, one end of the stainless steel is fixed to the lower fixture of the tensile testing machine, and the bent end of the specimen is fixed to the upper fixture, and the angle of the specimen is adjusted to ensure that the upper and lower ends are in a vertical position, and then the specimen is stretched at a speed of 50 mm / min until the specimen is completely peeled off from the substrate, and the displacement and force in the process are recorded. It is generally believed that the force when the force is balanced is the bonding force of the electrode.

[0238] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A pole piece processing system, characterized in that: include: A flame heating unit is used to perform flame heating treatment on the pole piece.

2. The pole piece processing system according to claim 1, characterized in that: The flame heating unit generates flames located on opposite sides of the pole piece surface.

3. The pole piece processing system according to claim 1 or 2, characterized in that: The flame heating unit includes a flameless gas burner.

4. The pole piece processing system according to any one of claims 1 to 3, characterized in that: The pole piece processing system further includes a conveying unit, and the conveying unit is used to convey the pole piece.

5. A method for processing a pole piece, characterized in that: The pole piece includes an active layer, and the active layer includes an active substance and a binder; the method for processing the pole piece includes: flame heating the pole piece so that the surface temperature of the active layer is greater than or equal to the softening temperature or melting temperature of the binder, and less than the lowest temperature among the decomposition temperature, oxidation temperature and ignition temperature of the active substance.

6. The method for processing a pole piece according to claim 5, characterized in that: The flame used in the flame heating process includes a premixed combustion flame.

7. The method for processing a pole piece according to claim 6, characterized in that: The temperature of the premixed combustion flame is 500-1200°C, optionally 600-1000°C.

8. The method for processing a pole piece according to claim 6 or 7, characterized in that: The premixed combustion flame is generated by a flameless gas burner, and the flameless gas burner includes any one or more of the following technical parameters: (1) Air flow rate 50-250 L / min, optionally 80-150 L / min; (2) Gas fuel flow rate 2 to 15 L / min, optionally 5 to 10 L / min; (3) Air-fuel ratio 1 to 7, optionally 3 to 5.

9. The method for processing a pole piece according to any one of claims 5 to 8, characterized in that: During the flame heating step, the pole piece moves relative to the flame.

10. The method for processing a pole piece according to claim 9, characterized in that: The moving speed of the pole piece relative to the flame is 40-100 m / min, optionally 60-80 m / min.

11. The method for processing a pole piece according to any one of claims 5 to 10, characterized in that: The surface temperature of the active layer is 180-500°C, and optionally 300-500°C.

12. A pole piece, characterized in that: The porosity of the pole piece is 30% to 50%, and optionally 30% to 47%.

13. The pole piece according to claim 12, characterized in that: The pole piece includes any one or more of the following technical parameters: (1) The liquid absorption rate is 0.3μg / s to 12μg / s; (2) The membrane resistance is 0.001Ω~0.43Ω; (3) Adhesion force: 18~23N / m.

14. The pole piece according to claim 12 or 13, characterized in that: The electrode sheet includes a positive electrode sheet, and the positive electrode sheet has a porosity of 35% to 50%, a liquid absorption rate of 0.3 μg / s to 0.5 μg / s, a membrane resistance of 0.0016Ω to 0.002Ω, and a bonding force of 18 to 20 N / m; or, The pole piece includes a negative pole piece, and the negative pole piece has a porosity of 30% to 35%, a liquid absorption rate of 9 μg / s to 12 μg / s, a membrane resistance of 0.39Ω to 0.43Ω, and a bonding force of 20 to 23 N / m.

15. The pole piece according to any one of claims 12 to 14, characterized in that: The pole piece is obtained by processing according to the method for processing a pole piece according to any one of claims 5 to 11.

16. A battery, characterized in that: The battery comprises the pole piece according to any one of claims 12 to 15.

17. An electrical device, characterized in that: The electrical device comprises the battery according to claim 16.

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