Pole piece processing system, pole piece processing method, pole piece, battery and power utilization device

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a pole piece processing system, a pole piece processing method, a pole piece, a battery and a power utilization device. The pole piece processing system comprises a flame heating unit, wherein the flame heating unit is used for carrying out flame heating treatment on the pole piece. The method for treating the pole piece comprises the following steps: carrying out flame heating treatment on 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 is less than the lowest temperature of the decomposition temperature, the oxidation temperature and the ignition temperature of the active substance. In the flame heating treatment process, the binder floating on the surface of the pole piece can be softened (melted) or ablated. After the floating binder is softened (melted) or ablated, the number of capillary pores of the pole piece is increased, and channels for electrolyte infiltration in the pole piece are increased, so that the electrolyte can infiltrate the pole piece more easily, and the electrolyte wettability of the pole piece is improved.

Description

Technical Field

[0001] 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

[0002] With the development of the new energy industry, battery research has become more and more popular, and market requirements have continued to increase. However, there are still many problems that need to be solved, such as poor electrolyte wettability of the electrode.

[0003] When the electrode is not wetted by electrolyte, it is difficult for the electrode that is not wetted by electrolyte 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, etc. Therefore, the electrolyte wettability of the electrode is related to the 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. Summary of the invention

[0004] In view of the above problems, the present application provides a pole piece processing system, a method for processing a pole piece, a pole piece, a battery, and an electrical device, which can improve the electrolyte wetting performance of the pole piece.

[0005] 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.

[0006] The pole piece processing system of the embodiment of the present application performs flame heating treatment on the pole piece by setting a flame heating unit. During the flame heating treatment process, the binder floating on the surface of the pole piece can be softened (melted) or ablated. After the floating binder is softened (melted) or ablated, the number of capillaries in the pole piece increases, and the channels for electrolyte infiltration in the pole piece are increased, making it easier for the electrolyte to infiltrate the pole piece, thereby improving the electrolyte wettability of the pole piece.

[0007] 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. There is no need to increase the production line modification time and equipment, which has a good cost advantage.

[0008] In some embodiments, the flame heating unit generates flames on opposite sides of the pole piece surface. In this way, the two opposite surfaces of the pole piece can be subjected to flame heating treatment, so that the adhesive on the two surfaces of the pole piece is softened (melted) or ablated, which is beneficial to improving the processing efficiency of the pole piece.

[0009] 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 is not only conducive to rapid heating of the pole piece, but also can improve the situation in which carbon deposition on the pole piece surface during the flame heating process causes the reduction of the porosity on the pole piece surface, helps to improve the overall capillary pore distribution of the pole piece, and further accelerates the electrolyte infiltration rate of the pole piece.

[0010] In some embodiments, the electrode processing system further includes a conveying unit, which is used to convey the electrode. Under the action of the conveying unit, the electrode enters the flame heating unit and other processes in an orderly manner for processing, and can work continuously and uninterruptedly. Moreover, by adjusting the running speed of the conveying unit, the flame generated by the rapid passage of the electrode through the flame heating unit can be adjusted to achieve rapid heating of the electrode, which is conducive to improving processing efficiency.

[0011] In the second aspect, the present application provides a method for processing an electrode, wherein the electrode comprises an active layer, and the active layer comprises an active substance and a binder; the method for processing the electrode comprises: performing flame heating treatment on 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.

[0012] In the method of the embodiment of the present application, the electrode is treated by flame heating and the temperature of the active layer is controlled during the flame heating process, so that the binder floating on the surface of the electrode can be softened (melted) or ablated. After the floating binder is softened (melted) or ablated, the number of capillaries in the electrode increases, and the channels for electrolyte infiltration in the electrode are increased, making it easier for the electrolyte to infiltrate the electrode, thereby improving the electrolyte wettability of the electrode.

[0013] 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.

[0014] In some embodiments, the flame used in the flame heating treatment includes a premixed combustion flame. The embodiments of the present application use a premixed combustion flame to perform flame heating treatment on the pole piece, which is not only conducive to rapid heating of the pole piece, but also can improve the situation in which carbon deposition on the pole piece surface during the flame heating treatment leads to a decrease in the porosity of the pole piece surface, which helps to improve the overall capillary pore distribution of the pole piece and further accelerate the electrolyte infiltration rate of the pole piece.

[0015] In some embodiments, the temperature of the premixed combustion flame is 500-1200° C., optionally 600-1000° C. The pole piece is subjected to flame heating treatment using a high-temperature flame, so that the pole piece can be quickly heated to a desired temperature.

[0016] 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:

[0017] (1) Air flow rate 50-250 L / min, optionally 80-150 L / min;

[0018] (2) Gas fuel flow rate 2 to 15 L / min, optionally 5 to 10 L / min;

[0019] (3) Air-fuel ratio 1 to 7, optionally 3 to 5.

[0020] The embodiment of the present application uses a flameless gas burner to generate a premixed combustion flame, which can quickly heat the active layer to the required temperature. At the same time, under certain air flow, gas fuel flow, and air-fuel ratio, the gas fuel can be fully burned, the flame produced by the combustion has fewer free carbon particles, and the flame has a lower blackness, which can improve the situation in which carbon deposits appear on the surface of the pole piece during the flame heating process, resulting in a decrease in the porosity of the pole piece surface.

[0021] In some embodiments, during the flame heating treatment step, the pole piece moves relative to the flame. By moving, the residence time of the pole piece under the flame can be adjusted, so as to achieve rapid and instant heating of the pole piece, and help improve the treatment efficiency. At the same time, since the flame has a high temperature, by controlling the movement of the pole piece relative to the flame, the contact time between the flame and the pole piece can be reduced, and the pole piece temperature can be controlled within a suitable range.

[0022] In some embodiments, the pole piece moves at a speed of 40 to 100 m / min relative to the flame, 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, so as to achieve rapid and instantaneous heating of the pole piece, and control the temperature of the active layer in the pole piece during the flame heating process within a desired range.

[0023] 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 pole piece binders, and less than the lowest temperature among the decomposition temperature, oxidation temperature, and ignition temperature of common pole piece active materials, which can effectively soften (melt) or ablate the binder floating on the surface of the pole piece, and at the same time improve the decomposition, oxidation or 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 pole piece.

[0024] In a third aspect, the present application provides a pole piece, the porosity of the pole piece is 30% to 50%, optionally 30% to 47%; the pole piece is processed according to the method described in the second aspect of the present application.

[0025] 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 channel 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.

[0026] In a fourth aspect, the present application provides a battery, comprising the electrode described in the third aspect of the present application.

[0027] The battery of the embodiment of the present application includes the above-mentioned pole piece, which can be a positive pole piece, a negative pole piece, or both. Since the floating binder in the pole piece of the battery is softened (melted) and ablated, the pole piece has a higher porosity, which is conducive to improving the wettability of the electrolyte to the pole piece, thereby helping to improve the electrochemical performance of the battery.

[0028] In a fifth aspect, the present application provides an electrical device, wherein the electrical device comprises the battery described in the fourth aspect.

[0029] The battery disclosed in the embodiments of the present application can be used in an electrical device using the battery as a power source, or in various energy storage systems using the battery as an energy storage element, for providing electrical energy. Electrical devices may include, but are not limited to, mobile phones, tablets, laptops, electric toys, electric 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 a secondary battery may be selected according to its use requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying any creative work.

[0031] Figure 1 A schematic diagram of the structure of the pole piece processing system provided in Example A1 of the present application;

[0032] Figure 2 is a schematic diagram of a battery module according to an embodiment of the present application;

[0033] Figure 3 A schematic diagram of a battery pack according to an embodiment of the present application;

[0034] Figure 4 for Figure 3 An exploded view of a battery pack according to an embodiment of the present application is shown;

[0035] Figure 5 A schematic diagram of a battery according to an embodiment of the present application;

[0036] Figure 6 for Figure 5 An exploded view of a battery according to an embodiment of the present application is shown;

[0037] Figure 7 A schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0038] Reference numerals:

[0039] 10-pole piece; 20-transmission unit; 21-unwinding guide roller; 22-winding guide roller; 30-flame heating unit; D-transmission direction of pole piece; 1-battery pack; 2-upper box; 3-lower box; 4-battery module; 5-battery cell; 51-housing; 52-electrode assembly; 53-cover plate. DETAILED DESCRIPTION

[0040] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field 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" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0042] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0043] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0044] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0045] 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.

[0046] 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, and 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.

[0047] The mass of the relevant components mentioned in the specification of the examples of this application can 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 specification of the examples of this application, it is within the scope disclosed in the specification of the examples of this application. Specifically, the mass described in the specification of the examples of this application can be mass units known in the chemical industry such as μg, mg, g, and kg.

[0048] With the development of the new energy industry, battery research has become more and more popular, and market requirements have continued to increase. However, there are still many problems that need to be solved, such as poor wettability of the electrode.

[0049] When the electrode is not wetted by electrolyte, it is difficult for the electrode not wetted by electrolyte to participate in the electrochemical reaction of the battery, reducing the ions that can be freely conducted between the positive and negative electrodes, thus 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, etc. Therefore, the electrolyte wettability of the electrode is related to the various electrochemical properties of the battery, such as charge and discharge capacity, rate performance, cycle performance, etc.

[0050] After analysis, it is found that the electrolyte wetting performance of the pole piece is affected by various factors in the pole piece processing process. For example, energy density is an important indicator of the battery. The greater the energy density, the more electrical energy the battery can release. In order to increase the energy density of the battery, the battery pole piece can be made by thick coating. That is, in the process of preparing the pole piece, the ratio of active material to current collector is increased, that is, the coating amount of the pole piece slurry is increased. However, the increase in the coating amount of the pole piece slurry also leads to an increase in the thickness of the pole piece, which easily reduces the electrolyte infiltration rate of the pole piece.

[0051] At the same time, the method of thick coating of the pole piece leads to an increase in the thickness of the pole piece, which is inconsistent with the market's pursuit of battery portability, small size and other requirements. Therefore, in the process of pole piece manufacturing, it is often necessary to increase the compaction density of the pole piece as much as possible. However, this will compress the pores between the active materials in the pole piece smaller and smaller, and the electrolyte is not easy to infiltrate them. Moreover, in the production process of the pole piece, after the pole piece slurry is coated on the current collector, it is often necessary to remove the solvent in the pole piece slurry through processes such as drying to form a stable pole piece. During the drying process, the solvent in the pole piece slurry migrates and evaporates to the surface of the pole piece through capillary force, while 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 pole piece as the solvent evaporates, resulting in the problem of binder floating. The floating of the binder will block the pores of the pole piece, so that the electrolyte cannot penetrate into the capillary pores of the pole piece, thereby reducing the electrolyte infiltration rate of the pole piece and affecting the various electrochemical properties of the battery.

[0052] 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 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 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.

[0053] 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 has 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.

[0054] The present application is further described below in conjunction with the examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of the present application.

[0055] A first aspect of an embodiment of 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.

[0056] The pole piece processing system refers to the process equipment used to make and process pole pieces. Flame heating is a method of using flame to burn the sample to increase the temperature of the sample.

[0057] The pole piece processing system of the embodiment of the present application performs flame heating treatment on the pole piece by setting a flame heating unit. During the flame heating treatment process, the binder floating on the surface of the pole piece can be softened (melted) or ablated. After the floating binder is softened (melted) or ablated, the number of capillaries in the pole piece increases, and the channels for electrolyte infiltration in the pole piece are increased, making it easier for the electrolyte to infiltrate the pole piece, thereby improving the electrolyte wettability of the pole piece.

[0058] 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. There is no need to increase the production line modification time and equipment, which has a good cost advantage.

[0059] In some embodiments, the flame heating unit generates flames on opposite sides of the pole piece surface. In this way, the two opposite surfaces of the pole piece can be subjected to flame heating treatment, so that the adhesive on the two surfaces of the pole piece is softened (melted) or ablated, which is beneficial to improving the treatment efficiency of the pole piece.

[0060] In some embodiments, the flame heating unit comprises a flameless gas burner.

[0061] A gas burner is a device that converts gas fuel into heat energy through combustion. According to the different combustion flames, gas burners can be divided into flamed gas burners and flameless gas burners. Among them, the flame formed by the burner in the flamed gas burner has strong light radiation, and its working principle is gas diffusion combustion. The light radiation of the flame formed by the flameless gas burner is weak, and its working principle is gas premixed combustion (there is partial diffusion combustion in the actual flameless gas burner, that is, the working principle belongs to local premixed combustion).

[0062] Among them, gas diffusion combustion and gas premixed combustion are two different combustion modes of gas. In gas diffusion combustion, the gas fuel and the oxidant (air or oxygen) are not in contact before ignition and are sent into the combustion chamber separately for combustion. For example, the combustion of torches, kerosene lamps, alcohol lamps, etc. belongs to gas diffusion combustion. Gas diffusion combustion has the disadvantages of poor combustion stability and low heat release rate, and because the gas fuel and the oxidant are not in contact before ignition, the combustion is not complete and carbon particles are produced, which easily forms carbon deposits on the surface of the sample heated by the flame.

[0063] Gas premixed combustion is the 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. By controlling the content of the oxidant in the premix, the gas fuel can be completely burned, reducing the carbon smoke generated during the combustion process. In addition, gas premixed combustion also has the characteristics of fast combustion speed. The hydrocarbons in the gas fuel do not have time to decompose, resulting in fewer free carbon particles in the flame and lower flame blackness.

[0064] 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 on the surface of the electrode during the flame heating process causes the porosity of the electrode surface to decrease, which helps to improve the overall capillary distribution of the electrode and further accelerate the electrolyte infiltration rate of the electrode.

[0065] Exemplarily, the flameless gas burner of the embodiment of the present application includes a jet-type gas burner, that is, a lance burner.

[0066] In some embodiments, the gas fuel used by 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 the advantages of high thermal intensity and high combustion temperature during the combustion process, and can achieve rapid flame heating of the electrode.

[0067] In some embodiments, the pole piece processing system further includes a conveying unit, and the conveying unit is used to convey the pole piece.

[0068] Under the action of the conveying unit, the pole piece enters 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 arranged manner, which are used to unwind and wind the pole piece respectively. Placing the pole piece on the unwinding guide roller and the winding guide roller, and operating the winding guide roller, the pole piece 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 running speed of the conveying unit, the flame generated by the rapid passage of the pole piece through the flame heating unit can be adjusted, thereby achieving rapid heating of the pole piece and facilitating improving processing efficiency.

[0069] In some embodiments, the electrode processing system further includes a temperature measuring unit, which is used to measure the temperature of the electrode. 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 that is undergoing flame heating treatment, and can also be used to measure the temperature of the electrode that has completed 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 two values).

[0070] In some embodiments, the temperature measurement unit includes an infrared temperature measurement module. By means of infrared temperature measurement, non-contact temperature measurement of the electrode can be achieved.

[0071] In some embodiments, the pole piece 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 pole piece temperature data measured by the temperature measuring unit and control the flame heating unit according to the temperature data, so as to accurately and effectively soften (melt) or ablate the floating binder in the pole piece, thereby reducing the adverse effects on other components in the pole piece.

[0072] In some embodiments, the pole piece processing system further includes a drying unit, which is used to dry the pole piece coated with the electrode slurry, and the drying unit and the flame heating unit are arranged in sequence along the conveying direction of the pole piece. Among them, the pole piece coated with the electrode slurry refers to a pole piece 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 pole piece, which means that the pole piece 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 pole piece, affecting the structure of the pole piece. In this regard, after being processed by the flame heating unit, these floating binders can be softened (melted) or ablated.

[0073] In some embodiments, the electrode processing system further includes a rolling unit, which is used to roll the electrode, and the rolling unit and the flame heating unit are arranged in sequence along the transmission direction of the electrode; or, the drying unit, the rolling unit and the flame heating unit are arranged in sequence along the transmission direction of the electrode. Rolling methods generally include cold pressing, hot pressing, etc. Rolling can enhance the bonding force inside the electrode and make the electrode have the required compaction density.

[0074] In some embodiments, the electrode processing system further includes a cooling unit, which is used to cool the electrode, and the flame heating unit and the cooling unit are arranged in sequence along the transmission direction of the electrode. After the flame heating unit processes the electrode, the electrode usually needs to be rolled up. Too high a temperature of the electrode is not conducive to rolling up. Therefore, by cooling the electrode with the cooling unit, the temperature of the electrode can be reduced, which is conducive to the subsequent rolling up of the electrode.

[0075] A 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 a electrode in an 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.

[0076] Among them, the active material is the substance in the pole piece 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 coated on at least one side of the current collector. After the solvent evaporates, the slurry dries to form the active layer of the pole piece.

[0077] 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. Usually, the pole piece includes a current collector and an active layer arranged 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 the area 3 to 10 cm downstream of the flame heating (such as any point value of 3cm, 4cm, 5cm, 6cm, 7cm, 8cm, 9cm, 10cm or any range value between 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 treatment.

[0078] The softening temperature is the temperature at which the three-dimensional long-range ordered state of the macromolecular chain structure of a non-crystalline polymer changes to a disordered viscous flow state. The melting temperature is the temperature at which the three-dimensional long-range ordered state of the macromolecular chain structure of a crystalline polymer changes to a disordered viscous flow state, also known as the melting point, which is the lower limit of the molding processing temperature of crystalline polymers. Generally speaking, the melting temperature range is relatively narrow, while the softening temperature range is relatively wide.

[0079] The decomposition temperature of an active substance refers to the temperature at which the molecular structure of the active substance is destroyed or the crystal lattice is distorted, although the combustion reaction does not occur. The oxidation temperature of an active substance is the minimum temperature required for the active substance to undergo an oxidation reaction. The ignition temperature of an active substance, also known as the ignition temperature, is the minimum temperature at which the active substance burns.

[0080] In the method of the embodiment of the present application, the electrode is treated by flame heating and the surface temperature of the active layer is controlled during the flame heating process, so that the binder floating on the surface of the electrode can be softened (melted) or ablated. After the floating binder is softened (melted) or ablated, the number of capillaries in the electrode increases, and the channels for electrolyte infiltration in the electrode increase, making it easier for the electrolyte to infiltrate the electrode, thereby improving the electrolyte wettability of the electrode.

[0081] 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.

[0082] In some embodiments, the mass concentration of the solvent in the active layer is as low as ppm level, such as less than 1000 ppm. The active layer with such a low concentration is a dried active layer, and there is a floating binder on its surface. In the embodiment of the present application, the pole piece with the dried active layer is subjected to flame heating treatment, and the floating binder can be treated to improve the performance of the pole piece.

[0083] In some embodiments, the flame used in the flame heating process includes a premixed combustion flame.

[0084] Premixed combustion, also known as gas premixed combustion, is a combustion method of gas fuel, and the 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 lower flame blackness. Therefore, the embodiment of the present application adopts a premixed combustion flame to perform flame heating treatment on the pole piece, which is not only conducive to rapid heating of the pole piece, but also can improve the situation where carbon deposition on the pole piece surface during the flame heating treatment leads to a decrease in the porosity of the pole piece surface, which helps to improve the overall capillary distribution of the pole piece and further accelerate the electrolyte infiltration rate of the pole piece.

[0085] In some embodiments, the temperature of the premixed combustion flame is 500-1200°C, optionally 600-1000°C, including but not limited to any point value 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 value 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 thermocouple, 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 desired temperature.

[0086] 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:

[0087] (1) Air flow rate 50-250 L / min, optionally 80-150 L / min;

[0088] (2) Gas fuel flow rate 2 to 15 L / min, optionally 5 to 10 L / min;

[0089] (3) Air-fuel ratio 1 to 7, optionally 3 to 5.

[0090] Wherein, the air flow rate includes but is not limited to any point value among 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, 250L / min or the range value between any two of them.

[0091] 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.

[0092] The air-fuel ratio refers to the mass ratio of air to gaseous fuel in the mixture formed by premixing gaseous fuel and air. The air-fuel ratio includes but is not limited to any point value among 1, 2, 3, 4, 5, 6, 7 or a range of values ​​between any two of them.

[0093] The embodiment of the present application uses a flameless gas burner to generate a premixed combustion flame, which can quickly heat the active layer to the required temperature. At the same time, under certain air flow, gas fuel flow, and air-fuel ratio, the gas fuel can be fully burned, the flame produced by the combustion has fewer free carbon particles, and the flame has a lower blackness, which can improve the situation in which carbon deposits appear on the surface of the pole piece during the flame heating process, resulting in a decrease in the porosity of the pole piece surface.

[0094] In some embodiments, during the flame heating process, the pole piece moves relative to the flame. By moving, the residence time of the pole piece under the flame can be adjusted, so that rapid and instant heating of the pole piece can be achieved, which is conducive to improving the processing efficiency. At the same time, since the flame has a high temperature, by controlling the movement of the pole piece relative to the flame, the contact time between the flame and the pole piece can be reduced, and the pole piece temperature can be controlled within a suitable range.

[0095] In some embodiments, the moving speed 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 point value 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 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, so as to achieve rapid and instantaneous heating of the pole piece, and control 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 the unwinding guide roller and the winding guide roller, and the pole piece is pulled by the winding guide rail, so as to achieve the 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 moving speed of the pole piece relative to the flame can be adjusted.

[0096] In some embodiments, in the flame heating step, the surface temperature of the active layer is 180-500°C, optionally 300-500°C, including but not limited to any point value of 180°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C or any range value between 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 pole piece binders, and less than the lowest temperature of the decomposition temperature, oxidation temperature, and ignition temperature of common pole piece active materials. The binder floating on the surface of the pole piece can be effectively softened (melted) or ablated, while improving the decomposition, oxidation or combustion of the active material during the flame heating process, maintaining the lattice stability of the active material and the structural stability of the pole piece.

[0097] In some embodiments, before flame heating treatment, the porosity of the pole piece is 25% to 32%, including but not limited to any point value of 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32% or any range value between the two. Generally, the positive pole piece and the negative pole piece have different porosities due to the density of the active material, the particle size, the type of binder used, or other factors. For the positive pole piece, its porosity before flame heating can be 30% to 32%, including but not limited to any point value of 30%, 31%, 32% or any range value between the two. For the negative pole piece, its porosity before flame heating treatment can be 25% to 28%, including but not limited to any point value of 25%, 26%, 27%, 28% or any range value between the two. The porosity of the electrode can be calculated by using the apparent volume and the real volume of the electrode, that is, porosity = (V0-V) / V*100%, where V0 is the apparent volume of the electrode and V is the real volume of the electrode. The method of the embodiment of the present application is suitable for processing electrodes with different porosities. The porosity of the electrode can be increased by flame heating treatment, thereby improving the electrolyte wettability of the electrode.

[0098] In some embodiments, before flame heating treatment, the film resistance of the electrode piece is 0.001-0.5Ω, including but not limited to any point value of 0.001Ω, 0.002Ω, 0.005Ω, 0.01Ω, 0.05Ω, 0.1Ω, 0.2Ω, 0.3Ω, 0.4Ω, 0.5Ω or any range value between two thereof. Generally, the positive electrode piece and the negative electrode piece have different film resistances. For the positive electrode piece, its film resistance before flame heating is usually 0.001-0.01Ω, including but not limited to any point value of 0.001Ω, 0.002Ω, 0.005Ω, 0.01Ω or any range value between two thereof. For the negative electrode plate, its membrane resistance before flame heating is usually 0.1-0.5Ω, including but not limited to any point value of 0.1Ω, 0.2Ω, 0.3Ω, 0.4Ω, 0.5Ω or any range value between two of them. The membrane resistance of the electrode plate can be directly tested by a membrane resistance meter. The method of the embodiment of the present application is suitable for processing electrodes with different membrane resistances. The structure of the electrode plate can be improved by flame heating treatment, for example, the porosity of the electrode plate can be increased, which is beneficial to reduce the membrane resistance of the electrode plate.

[0099] In some embodiments, before flame heating treatment, the bonding force of the pole piece is 18 to 23 N / m, including but not limited to any point value of 18 N / m, 19 N / m, 20 N / m, 21 N / m, 22 N / m, 23 N / m or any range value between two. Generally, the positive pole piece and the negative pole piece have different bonding forces due to different types of binders used or other factors. For the positive pole piece, its bonding force before flame heating can be 18 to 20 N / m, including but not limited to any point value of 18 N / m, 19 N / m, 20 N / m or any range value between two. For the negative pole piece, its bonding force before flame heating can be 20 to 23 N / m, including but not limited to any point value of 20 N / m, 21 N / m, 22 N / m, 23 N / m or any range value between two. The bonding force of the pole piece reflects the bonding strength between the active material, binder, conductive agent, current collector and other components in the pole piece. The pole piece can be bonded to the surface of the substrate, and a tensile test is performed on the pole piece using a tensile machine. The displacement and force during the entire process of peeling the pole piece 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 pole piece. The method of the embodiment of the present application is suitable for processing pole pieces with different bonding forces. After flame heating treatment, the bonding force of the pole piece is improved, or the original level is maintained. That is, the pole piece after flame heating treatment will still have good bonding force and can meet the requirements.

[0100] 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 pole piece, and the temperature in the flame heating is determined according to the softening temperature or melting temperature of the binder.

[0101] In some embodiments, the mass content of the binder in the active layer includes but is not limited to 0.5% to 10%, and can be optionally 1% to 5%, for example, 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%, any one of the values ​​or the range between any two of them, and can also be set to other contents as needed.

[0102] In some embodiments, the electrode sheet includes any one or both of a positive electrode sheet and a negative electrode sheet. Whether it is a positive electrode sheet or a negative electrode sheet, there is a phenomenon that the binder floats during the drying process. The method of the embodiment of the present application is applicable to both positive electrode sheets and negative electrode sheets.

[0103] In some embodiments, the pole piece is a positive pole piece, and the active material includes one or more of metal inorganic active materials and organic active materials. The metal inorganic active materials include but are not limited to 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 materials include but are not limited to one or more of quinone compounds, carboxylate compounds, anhydride compounds, and amide compounds.

[0104] In some embodiments, the pole piece is a negative pole piece, 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. The carbon-based material includes, but is not limited to, one or more of graphite (natural graphite, artificial graphite), hard carbon, soft carbon, mesophase carbon microspheres, and graphene. The titanium-based active material includes, but is not limited to, one or more of lithium titanate and titanium dioxide. The silicon-based active material includes, but is not limited to, one or more of silicon and silicon dioxide. Nitrides include, but are not limited to, lithium nitride.

[0105] 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.

[0106] In some embodiments, the active layer further includes a conductive agent, which is used to collect microcurrents between active materials and between active materials and current collectors to improve electronic conductivity, and can also promote the infiltration of electrolyte into the electrode sheet.

[0107] 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.

[0108] In some embodiments, the mass content of the conductive agent in the active layer includes but is not limited to 0.5% to 10%, and can be optionally 1% to 5%, for example, 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%, any one of the points or any range values ​​between two of them, and can also be set to other contents as needed.

[0109] 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%, and may optionally be 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 any range between two of them, and may also be set to other contents as required.

[0110] In some embodiments, the pole piece further includes a current collector, and the active layer is disposed on at least one side of the current collector. The current collector on the pole piece is used as a substrate for the active layer to attach and to transmit electrons in the battery chemical reaction. The current collector includes but is not limited to a metal current collector, a carbon current collector, a conductive resin current collector, a composite current collector of metal and resin, and more specifically, copper, aluminum, nickel, titanium, iron and their respective alloys, stainless steel, carbon fiber, carbon nanotube (CNT), graphite, and the like.

[0111] In some embodiments, before the flame heating step, the pole piece is subjected to any one or both of a drying treatment and a roll pressing treatment.

[0112] In the production process of the electrode, the active material is generally mixed with a binder, a conductive agent, a solvent and other necessary components to form a slurry, which is then coated on the current collector and dried to form an 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 in turn leads to various problems that are not conducive to the electrochemical performance of the electrode.

[0113] Usually, after the drying process, a rolling process is also included. The rolling process usually includes cold pressing, hot pressing, etc. After rolling, the bonding force inside the pole piece can be enhanced and the pole piece can have the required compaction density. The rolling process can be arranged after the drying process and before the flame heating process.

[0114] 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 wetting performance of the electrode.

[0115] In some embodiments, after the flame heating step, a step of cooling the pole piece is included. The cooling method includes but is not limited to air cooling and circulating water cooling. By cooling the pole piece, the pole piece temperature can be reduced, which is helpful for subsequent processing of the pole piece, such as winding the pole piece.

[0116] A third aspect of an embodiment of the present application provides a pole piece, the porosity of which is 30% to 50%, optionally 30% to 47%; the pole piece is obtained by processing according to the method of the second aspect above.

[0117] Due to the difference in material type and content between the positive electrode sheet and the negative electrode sheet, as well as other factors, the positive electrode sheet and the negative electrode sheet have different porosities after flame heating treatment. 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%, 50% or any range between two values.

[0118] Alternatively, the electrode sheet is a negative electrode sheet, and the porosity of the negative electrode sheet is 30% to 35%, including but not limited to any point value of 30%, 31%, 32%, 33%, 34%, 35% or a range value between any two of them.

[0119] 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.

[0120] In some embodiments, the porosity of the pole piece of the embodiment of the present application is increased by 14% or more than that before flame heating treatment, for example, by 14% to 50%, including but not limited to any point value of 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50% or any range value between two thereof. Corresponding to the porosity, after flame heating treatment, the porosity change rate of the positive pole piece and the negative pole piece is also different. For the positive electrode sheet, the porosity is increased by 19% to 50% compared with that before the flame heating treatment, and is optionally 40% to 50%, including but not limited to any point value of 19%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, or any range value between two thereof. For the negative electrode sheet, the porosity is increased by 14% to 26% compared with that before the flame heating treatment, and is optionally 22% to 26%, including but not limited to any point value of 14%, 16%, 18%, 20%, 22%, 24%, 26%, or any range value between two thereof.

[0121] In some embodiments, the electrode of the embodiment of the present application has an electrolyte absorption rate that is increased by 18% or more compared to that before flame heating treatment, and 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 value between two of them. Affected by different porosities, the change rate of electrolyte absorption speed of the positive electrode and the negative electrode is also different. For the positive electrode plate, the liquid absorption rate of the electrolyte is increased by 34% to 100% compared with that 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 the two. For the negative electrode plate, the liquid absorption rate of the electrolyte is increased by 18% to 40% compared with that 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 the two. The electrode plate of the embodiment of the present application has a high porosity, so that it has a fast absorption rate of the electrolyte.

[0122] 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, and 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 any range value between two of them. The rate of change of 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, and optionally reduced by 25% to 30%, including but not limited to any point value of 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30% or any range value between two of them. For the negative electrode sheet, the diaphragm resistance is reduced by 8% to 15% compared with that before the flame heating treatment, and optionally by 12% to 15%, including but not limited to any one of 8%, 10%, 12%, 14%, 15% or any range between two values. After the flame heating treatment, the diaphragm resistance of the electrode sheet is improved.

[0123] A fourth aspect of an embodiment of the present application provides a battery, which includes the electrode sheet according to the third aspect.

[0124] The battery of the embodiment of the present application includes the above-mentioned pole piece, which can be a positive pole piece, a negative pole piece, or both. Since the floating binder in the pole piece of the battery is softened (melted) and ablated, the pole piece has a higher porosity, which is conducive to improving the wettability of the electrolyte to the pole piece, thereby helping to improve the electrochemical performance of the battery.

[0125] In some embodiments, the battery of the embodiment of the present application includes one or more of a primary battery and a secondary battery. Batteries can be divided into primary batteries and secondary batteries according to whether the battery can be recharged and reused. A primary battery cannot be recharged to restore it after discharge, and a secondary battery can continue to be used by activating the active material by charging after the battery is discharged. The pole piece of the embodiment of the present application can be applied to both primary batteries and secondary batteries, and has a wide range of uses.

[0126] In some embodiments, the battery of the embodiment 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 a separator. 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.

[0127] In some embodiments, the battery further includes an electrolyte. The electrolyte can serve as a carrier for ion transport in the battery.

[0128] 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 contain a solid electrolyte, such as a polymer electrolyte, an inorganic solid electrolyte, etc., but is not limited thereto.

[0129] 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).

[0130] 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).

[0131] The electrolyte may also 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.

[0132] In some embodiments, the battery further includes a separator stacked between the positive electrode sheet and the negative electrode sheet. In some batteries, a separator is required to separate the positive electrode sheet from the negative electrode sheet so that electrons in the battery cannot pass freely, preventing the two electrodes from contacting and short-circuiting, while allowing ions in the electrolyte to pass freely between the positive and negative electrodes.

[0133] The diaphragm can be any known porous structure isolation membrane 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).

[0134] The positive electrode sheets and the negative electrode sheets are alternately stacked, and a separation film is set between the positive electrode sheets and the negative electrode sheets to play an isolating role, so as to obtain a bare cell, or a bare cell after winding. The cell is placed in a casing, the electrolyte is injected, and the cell is 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 has a specific functional output; then one or more battery modules are installed in the 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.

[0135] refer to Figure 2 , which is an example of a battery module 4. In the battery module 4, a plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0136] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0137] refer to Figure 3 and Figure 4 , which is taken as an example of a battery pack 1. The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 to form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0138] In some embodiments, the battery may include an outer packaging, which may be used to encapsulate the electrode assembly consisting of the positive electrode sheet, the negative electrode sheet, the separator, and the electrolyte.

[0139] The outer packaging of the battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.; or a soft package, such as a bag-type soft package. The material of the soft package can be plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0140] The shape of the battery can be cylindrical, square or any other shape. For example, Figure 5 A square-structured battery is used as an example.

[0141] In some embodiments, reference Figure 6 The outer package may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate are enclosed to form a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process or a lamination process. One or more electrode assemblies 52 are encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52.

[0142] An embodiment of the present application further provides an electrical device, which includes the above-mentioned battery.

[0143] The battery disclosed in the embodiments of the present application can be used in electrical devices that use the battery as a power source, or various energy storage systems that use the battery as an energy storage element to provide electrical energy. Electrical devices may include, but are not limited to, mobile phones, tablets, laptops, electric toys, electric 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, the battery cell, battery module, or battery pack in the battery can be selected according to its use requirements.

[0144] Figure 7 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the high power and high energy density requirements of the power consumption device for the battery, a battery pack or a battery module can be used.

[0145] The following describes the invention in conjunction with specific embodiments.

[0146] Example A1

[0147] This embodiment provides a pole piece processing system, referring to Figure 1 , the pole piece processing system includes:

[0148] 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;

[0149] 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 a gas fuel, is used to spray out a premixed combustion flame, 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 the premixed combustion flame. The size of the spray gun nozzle is: 2 to 3 cm wide and 5 to 20 cm long, and 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 from 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.

[0150] The electrode processing system of this embodiment also includes: a drying unit, a rolling unit, a cooling unit, and a temperature measuring unit ( Figure 1 The drying unit, rolling unit, cooling unit, and temperature measuring unit are not shown in the figure. The drying unit, rolling unit, flame heating unit 30, and cooling unit are arranged in the conveying direction of the electrode piece ( Figure 1 Direction D) in sequence.

[0151] The drying unit is used to dry the electrode sheet coated with the electrode slurry, the rolling unit rolls the electrode sheet treated by the drying unit, and the cooling unit cools the electrode sheet treated by flame heating, so that the winding guide roller 22 can wind up the electrode sheet 10. The temperature measuring unit measures the temperature of the electrode sheet 10 during flame heating.

[0152] In this embodiment, the electrode processing system also includes an automatic temperature control unit ( Figure 1 The automatic temperature control unit is used to control the combustion conditions of the spray gun according to the temperature of the pole piece 10 measured by the temperature measuring unit.

[0153] The working process of the pole piece processing system of this embodiment includes:

[0154] The electrode slurry is coated on the current collector, dried by the drying unit and rolled by the rolling unit to form a pole piece 10 with a dry active layer. The pole piece 10 is quickly passed through the flame generated by the spray gun under the conveying unit 20, so as to achieve flame heating treatment of the pole piece 10.

[0155] 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.

[0156] Example B1

[0157] This embodiment provides a method for processing a positive electrode sheet, which is to process the positive electrode sheet in the electrode sheet processing system in embodiment A1, and specifically includes the following steps:

[0158] 1) Preparation of positive electrode

[0159] The nickel-cobalt-manganese (NCM) ternary material, conductive agent carbon black, polyvinylidene fluoride (PVDF), and N-methylpyrrolidone (NMP) are stirred and mixed evenly 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.

[0160] 2) Flame heating treatment of positive electrode

[0161] The obtained positive electrode is used Figure 1 The pole piece processing system shown in the figure performs flame heating treatment. During the treatment process, the premixed combustion flame generated by the spray gun contacts the positive pole piece. The air flow rate in the spray gun is 250L / min, the natural gas flow rate is 6L / min, the air-fuel ratio is 3, and the flame temperature is 600℃. The pole piece conveying speed is controlled to be 100m / min. The pole piece temperature during the conveying process and the carbon deposition on the pole piece surface are recorded.

[0162] Example B2

[0163] This embodiment provides a method for processing a positive electrode sheet, which is different from the embodiment B1 only in that: step 2) controls the sheet conveying speed to be 80 m / min. Other steps are the same as the embodiment B1.

[0164] Example B3

[0165] This embodiment provides a method for processing a positive electrode sheet, which is different from the embodiment B1 only in that: step 2) controls the sheet conveying speed to be 60 m / min. Other steps are the same as the embodiment B1.

[0166] Example B4

[0167] This embodiment provides a method for processing a positive electrode sheet, which is different from the embodiment B1 only in that: step 2) controls the sheet conveying speed to be 40 m / min. Other steps are the same as the embodiment B1.

[0168] Comparative Example B1

[0169] 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).

[0170] Comparative Example B2

[0171] This comparative example provides a method for processing a positive electrode sheet, which is different from Example B1 only in that: Step 2) controls the sheet conveying speed to be 10 m / min. Other steps are the same as Example B1.

[0172] In this comparative example, the electrode was burned out during the processing.

[0173] Comparative Example B3

[0174] This comparative example provides a method for processing a positive electrode sheet, which is different from Example B1 only in that the spray gun is replaced by an alcohol lamp, the flame (external flame) temperature of the alcohol lamp is 400° C., and the electrode sheet conveying speed is controlled to be 10 m / min. Others are the same as Example B1.

[0175] In this comparative example, the combustion of the alcohol lamp belongs to diffusion combustion, and the flame formed is clearly divided into the flame core, inner flame and outer flame. Considering that the flame temperature of the alcohol lamp is relatively low, in the process of processing the positive electrode, the electrode tape 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.

[0176] Example C1

[0177] This embodiment provides a method for processing a negative electrode sheet, which is to process the negative electrode sheet in the sheet processing system in embodiment A1, and specifically includes the following steps:

[0178] 1) Preparation of negative electrode sheet

[0179] The active material artificial graphite, the conductive agent carbon black, the binder styrene-butadiene rubber (SBR), and the thickener sodium hydroxymethyl cellulose (CMC) are dissolved in the solvent deionized water in a mass ratio of 96.2:0.8:0.8:1.2, and the negative electrode slurry is prepared after being evenly mixed; the negative electrode slurry is evenly coated on the negative electrode collector copper foil once or multiple times, and the negative electrode sheet is obtained after drying, cold pressing, and slitting.

[0180] 2) Flame heating treatment of negative electrode

[0181] The obtained negative electrode sheet is used Figure 1 The processing system shown performs flame treatment. During the treatment process, the premixed combustion flame generated by the spray gun contacts the negative electrode piece. The air flow rate in the spray gun is 180L / min, the natural gas flow rate is 6L / min, the air-fuel ratio is 4, and the flame temperature is 800°C. The electrode piece conveying speed is controlled to be 100m / min, and the electrode piece temperature during the conveying process and the carbon deposition on the electrode piece surface are recorded.

[0182] Example C2

[0183] This embodiment provides a method for processing a negative electrode sheet, which is different from the embodiment C1 only in that: step 2) controls the sheet conveying speed to be 80 m / min. Other steps are the same as the embodiment C1.

[0184] Example C3

[0185] This embodiment provides a method for processing a negative electrode sheet, which is different from the embodiment C1 only in that: step 2) controls the sheet conveying speed to be 60 m / min. Other steps are the same as the embodiment C1.

[0186] Example C4

[0187] This embodiment provides a method for processing a negative electrode sheet, which is different from the embodiment C1 only in that: step 2) controls the sheet conveying speed to be 40 m / min. Other steps are the same as the embodiment C1.

[0188] Comparative Example C1

[0189] This comparative example provides a method for processing a negative electrode plate, which is different from Example C1 only in that the negative electrode plate is not subjected to the flame heating treatment in step 2).

[0190] Comparative Example C2

[0191] This comparative example provides a method for processing a positive electrode sheet, which is different from Example C1 only in that: Step 2) controls the sheet conveying speed to be 10 m / min. Other steps are the same as Example C1.

[0192] In this comparative example, the electrode was burned out during the processing.

[0193] The electrode processing conditions of each embodiment and comparative example are shown in Table 1, and the electrode temperature (specifically the active layer temperature) and the electrode carbon deposition conditions of each embodiment and comparative example during the processing are shown in Table 2. Among them, the "active layer surface temperature" in Table 2 is the active layer surface temperature about 6 cm downstream of the flame heating (also the electrode surface temperature). The active layer surface temperature about 6 cm downstream is selected, on the one hand, to facilitate temperature measurement, and on the other hand, this area is very close to the flame heating area, and the measured temperature can be considered to be the same as the active layer surface temperature of the flame heating treatment.

[0194] The performance of the electrodes after treatment in each embodiment and comparative example was tested, including the electrolyte absorption rate, porosity, membrane resistance, adhesion, etc. The results are shown in Table 3 below.

[0195] Table 1. Pole piece processing conditions of various embodiments and comparative examples

[0196]

[0197]

[0198] Table 2. Surface temperature of the pole piece and carbon deposition of the pole piece in each embodiment and comparative example

[0199]

[0200] Table 3. Pole performance test results

[0201]

[0202] The data in Table 3 are 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.

[0203] Table 4. Change rate of pole piece performance of each embodiment and comparative example

[0204]

[0205]

[0206] In Table 4, the various change rates of Examples B1 to B4 and Comparative Examples B1 to B3 are the change rates compared to Comparative Example B1, and the various change rates of Examples C1 to C4 and Comparative Examples C1 to C2 are the change rates compared to Comparative Example C1.

[0207] For example:

[0208] 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%;

[0209] 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%;

[0210] 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%;

[0211] The liquid absorption rate change rate of the electrode piece of Example C2 = (the liquid absorption rate of the electrode piece of Example C2 - the liquid absorption rate change rate of the electrode piece of Comparative Example C1) / the liquid absorption rate change rate of the electrode piece of Comparative Example C1 * 100%.

[0212] The change rates of other items are calculated in the same way.

[0213] The test results show:

[0214] After the pole pieces of Example B1 to Example B4 and Example C1 to Example C4 are subjected to flame heating treatment under appropriate conditions, their liquid absorption rate is significantly improved compared to before the flame heating treatment. Among them, the liquid absorption rate of the positive pole pieces in Example B1 to Example B4 after flame heating treatment is increased by more than 34%, and even up to 100%; the liquid absorption rate of the negative pole pieces in Example C1 to Example C4 after flame heating treatment can also be increased by more than 18%. The significant improvement in the liquid absorption rate reflects that the wettability of the pole pieces by the electrolyte has been greatly improved after the pole pieces have been subjected to flame heating treatment.

[0215] Combined with the change in the porosity of the pole piece, it can be found that one of the reasons for the increase in the liquid absorption rate of the pole piece is that the porosity of the pole piece is improved after the flame heating treatment. The improvement in porosity is mainly due to the fact that during the flame heating process, the binder floating on the surface of the pole piece is softened (melted) or ablated by heat, so that the pole piece exposes more capillaries and increases the channel for the electrolyte to infiltrate the pole piece. Moreover, in the flame combustion treatment, a spray gun is used to generate a premixed combustion flame, so that no carbon deposits are formed on the surface of the pole piece to cause pore blockage (for example, the negative pole piece 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 test; and the negative pole piece of the embodiment C3 is not observed in appearance after 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 pole piece. Therefore, in Embodiments B1 to B4 and Embodiments 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.

[0216] 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 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 before the flame heating treatment, and the maximum 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 before the flame heating treatment, and the maximum 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 improved. In addition to improving the wettability of the electrolyte to the electrode, it can also greatly reduce the diaphragm resistance of the electrode and improve the electrochemical performance of the electrode.

[0217] In addition, the test results show that after flame heating treatment under appropriate conditions, the pole pieces still have good bonding strength.

[0218] In contrast, after flame heating treatment of the pole piece under inappropriate conditions, for example, after flame heating treatment of Comparative Example B2 and Comparative Example C2, the pole piece surface temperature is too high (higher than the lowest temperature among the decomposition temperature, oxidation temperature and ignition temperature of the active material in the pole piece), resulting in the pole piece being burned and damaged. For another example, after flame heating treatment of Comparative Example B3, the pole piece surface temperature is too low (lower than the softening or melting temperature of the active material in the binder), and the change rate of the liquid absorption rate of the pole piece is very small compared with that before flame heating treatment; at the same time, its porosity is lower than that of the pole piece without flame heating treatment, and the membrane resistance is increased.

[0219] In summary, during the flame heating process of the electrode, the porosity of the electrode can be effectively improved by controlling the electrode temperature within a certain range, thereby improving the wettability of the electrode by the electrolyte and helping to increase the membrane resistance of the electrode.

[0220] Appendix: The above-mentioned related performance test methods are as follows:

[0221] (1) Electrode electrolyte absorption rate

[0222] Fix the electrode on a clean glass plate, use a 0.2mm (inner diameter) capillary to absorb 3mm high electrolyte (the electrolyte composition includes EC, DMC and EMC in 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 it takes to absorb the electrolyte and obtain the electrolyte absorption rate by conversion.

[0223] (2) Electrode porosity

[0224] In a drying room, use tweezers to select >20 round electrodes with good appearance and no powder falling on the edges and put 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 the expansion chamber, calculate the true volume of all electrodes according to Bohr's law (PV=nRT), and thus obtain the porosity of the sample to be tested [porosity=(V0-V) / V*100%, where V0 is the apparent volume of the electrode and V is the true volume of the electrode].

[0225] (3) Diaphragm resistance

[0226] Use Yuanneng Technology's diaphragm resistor to test the diaphragm resistance. Cut small discs with a diameter of 10 mm from the left, middle, and right sides of the electrode. Turn on the indicator light of the Yuanneng Technology electrode resistor, place the probe in the appropriate position of the diaphragm resistor, click the "start" button, and wait for the reading to stabilize before reading. Each small disc tests two positions, and finally calculates the average of six measurements, which is the diaphragm resistance of the electrode.

[0227] (4) Adhesion

[0228] Cut the pole piece into 20*100mm 2 The test specimens of different sizes are kept for later use; the double-sided tape is used to adhere the side of the specimen to be tested, and it is compacted with a roller to make the double-sided tape fit the specimen completely; the other side of the double-sided tape of the specimen is adhered to the stainless steel surface, and one end of the specimen is bent in the opposite direction with a bending angle of 180°; the high-speed rail tensile testing machine is used for testing, one end of the stainless steel is fixed to the clamp below the tensile testing machine, the bent end of the specimen is fixed to the clamp above, 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.

[0229] 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 replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate 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%; The pole piece is obtained by processing according to any one of claims 5 to 11.

13. A battery, characterized in that: The battery comprises the electrode sheet according to claim 12.

14. An electrical device, characterized in that: The electrical device comprises the battery according to claim 13.

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