Positive electrode sheet, method for processing the same, battery, and electric device

Abstract

A positive electrode sheet, a processing method of the positive electrode sheet, a battery, and a power utilization device, the processing method of the positive electrode sheet comprising: performing a combustion treatment on a specified part of the positive electrode sheet, the specified part comprising at least part of a surface of a positive electrode active material layer of the positive electrode sheet. In the processing method of the positive electrode sheet, the surface of the positive electrode sheet is subjected to the combustion treatment, and the binder floating up can be ablated and reduced by the flame, which is conducive to improving the blockage of the pores by the floating binder, so that the electrolyte wetting performance of the positive electrode sheet can be effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a positive electrode sheet, a processing method thereof, a battery and an electric device. BACKGROUND

[0002] The electrolyte infiltration performance of the positive electrode sheet is a factor affecting the performance of the battery, and improving the electrolyte infiltration performance of the positive electrode sheet is conducive to improving the rate performance, discharge capacity and the like of the battery. However, the current positive electrode sheet, in order to meet the design requirements of high energy density, high cycle stability and the like, the infiltration performance usually needs to be improved. SUMMARY

[0003] In view of the above problems, the present application provides a positive electrode sheet, a processing method thereof, a battery and an electric device, which are conducive to improving the burr problem of the positive electrode sheet at the edge.

[0004] Embodiments of the present application are implemented as follows:

[0005] In a first aspect, the embodiments of the present application provide a processing method of a positive electrode sheet, comprising: performing a combustion treatment on a specified part of the positive electrode sheet, wherein the specified part comprises at least part of the surface of the positive electrode active material layer of the positive electrode sheet.

[0006] The processing method of the positive electrode sheet provided by the embodiments of the present application performs a combustion treatment on the surface of the positive electrode sheet, and the flame can ablate and reduce the floating binder, which is conducive to improving the blockage of the pores by the floating binder, so as to effectively improve the electrolyte infiltration performance of the positive electrode sheet.

[0007] In some embodiments, when the combustion treatment is completed, the burned area in the surface of the positive electrode active material layer reaches a specified temperature, and the specified temperature is 200℃-500℃.

[0008] In these embodiments, the burned area in the surface of the positive electrode active material layer is controlled to reach the specified temperature when the combustion treatment is completed, so that the surface of the positive electrode active material layer can be subjected to the combustion treatment at a suitable temperature, which is conducive to better ablation and reduction of the floating binder, and can better improve the electrolyte infiltration performance of the positive electrode sheet.

[0009] It should be noted that in other embodiments of the present application, the specified temperature may, for example, also be 130℃-500℃, 140℃-500℃, 150℃-500℃ or 160℃-500℃, etc.

[0010] In some embodiments, the specified temperature is 300℃-500℃; optionally, the specified temperature is 350℃-470℃.

[0011] In the embodiments, the control satisfies a further specified temperature, so that the surface of the positive electrode active material layer can be subjected to the combustion treatment at a more suitable temperature, which is beneficial to better ablation of the floating binder and reduction of the floating binder, and can better improve the electrolyte wetting performance of the positive electrode sheet.

[0012] In some embodiments, the binder in the positive electrode active material layer includes polyvinylidene fluoride.

[0013] In the embodiments, the combustion treatment can better remove the floating binder formed by the polyvinylidene fluoride, and can better improve the electrolyte wetting performance of the positive electrode sheet.

[0014] In some embodiments, the positive electrode active material in the positive electrode active material layer includes lithium-containing phosphate.

[0015] In the embodiments, the lithium-containing phosphate and the binder have a large temperature difference in decomposition temperature, which facilitates the control of the specified temperature to be above the decomposition temperature of the binder and below the decomposition temperature of the lithium-containing phosphate, so that the positive electrode active material layer can maintain good electrochemical performance while effectively removing the floating binder to improve the wetting performance.

[0016] In some embodiments, the lithium-containing phosphate includes lithium iron phosphate.

[0017] In the embodiments, the lithium iron phosphate and the binder have a large temperature difference in decomposition temperature, which can maintain good electrochemical performance of the positive electrode active material layer while effectively removing the floating binder to improve the wetting performance; at the same time, the lithium iron phosphate is a commonly used positive electrode active material, and the positive electrode sheet using the lithium iron phosphate often has the problem of poor wetting performance.

[0018] In some embodiments, the combustion treatment includes combusting fuel gas and treating the specified part by a flame.

[0019] In the embodiments, the combustion treatment is performed by combusting the fuel gas, and the airflow generated by the fuel gas can blow away the ablation products of the floating binder, which is beneficial to more sufficient ablation of the floating binder by the flame, and is also beneficial to maintaining good cleanliness of the surface of the positive electrode sheet.

[0020] In some embodiments, in the combustion treatment, the flow rate of the fuel gas is 3L / min to 12L / min; optionally, the flow rate of the fuel gas is 5L / min to 8L / min.

[0021] In the embodiments, a suitable flow rate of the fuel gas is maintained in the combustion treatment, so that the flame can provide suitable heat for the specified part, and the floating binder can be effectively removed by a suitable temperature to improve the wetting performance.

[0022] In some embodiments, the air flow rate in the combustion process is 70 L / min to 260 L / min; optionally, the air flow rate is 120 L / min to 180 L / min.

[0023] In these embodiments, maintaining a suitable air flow rate in the combustion process is conducive to meeting a suitable air-fuel ratio, so that the flame can provide suitable heat for the specified part, and the floating binder can be effectively removed by a suitable temperature to improve the infiltration performance.

[0024] In some embodiments, the air-fuel ratio in the combustion process is (2-5): 1; optionally, the air-fuel ratio is (3-4): 1.

[0025] In these embodiments, meeting a suitable air-fuel ratio in the combustion process is conducive to making the flame provide suitable heat for the specified part, and the floating binder can be effectively removed by a suitable temperature to improve the infiltration performance.

[0026] In some embodiments, in the combustion process, the fuel gas is sprayed toward the positive electrode sheet at a specified distance from the positive electrode sheet, and the specified distance is 5 cm to 10 cm; optionally, the specified distance is 5 cm to 7.5 cm.

[0027] In these embodiments, spraying the fuel gas toward the positive electrode sheet at a suitable specified distance for combustion is conducive to regulating the temperature of the flame acting on the positive electrode sheet, and the floating binder can be better removed to improve the infiltration performance.

[0028] In some embodiments, in the combustion process, the fuel gas is sprayed toward the positive electrode sheet in a specified direction, and the included angle between the specified direction and the thickness direction of the positive electrode sheet is 0° to 30°; optionally, the included angle between the specified direction and the thickness direction of the positive electrode sheet is 0° to 10°.

[0029] In these embodiments, spraying the fuel gas toward the positive electrode sheet at a suitable specified angle for combustion makes the flame better burn the positive electrode sheet, and the floating binder can be more effectively removed to improve the infiltration performance.

[0030] In some embodiments, in the combustion process, the positive electrode sheet passes through the flame at a specified speed, and the specified speed is 40 m / min to 100 m / min; optionally, the specified speed is 50 m / min to 80 m / min.

[0031] In these embodiments, passing the positive electrode sheet through the flame at a suitable specified speed is conducive to controlling the surface of the positive electrode sheet to reach a suitable temperature, and the floating binder can be better removed to improve the infiltration performance.

[0032] In a second aspect, the embodiments of the present application provide a positive electrode tab, which is processed according to the processing method of the positive electrode tab as described above.

[0033] In some embodiments, the positive electrode tab has an electrolyte infiltration speed > 0.27 μg / s, and optionally, the positive electrode tab has an electrolyte infiltration speed > 0.33 μg / s.

[0034] In these embodiments, the positive electrode tab has a high electrolyte infiltration speed, and the positive electrode tab has good electrolyte infiltration performance.

[0035] In some embodiments, the positive electrode tab has a porosity > 29.2%, and optionally, the positive electrode tab has a porosity > 32.6%.

[0036] In these embodiments, the positive electrode tab has a high porosity, which is conducive to improving the electrolyte infiltration performance of the positive electrode tab.

[0037] In a third aspect, the embodiments of the present application provide a battery comprising the positive electrode tab as described above.

[0038] In a fourth aspect, the embodiments of the present application provide a power utilization device comprising the battery as described above.

[0039] The above description is only a summary of the technical solutions of the embodiments of the present application. In order to more clearly understand the technical means of the present application, the following detailed description of the embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following detailed description of the embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0041] Figure 1 The structural schematic diagram of a vehicle is provided for some embodiments of the present application;

[0042] Figure 2 The exploded view of a battery is provided for some embodiments of the present application;

[0043] Figure 3 The exploded view of a battery cell is provided for some embodiments of the present application;

[0044] Figure 4 The structural schematic diagram of an electrode assembly is provided for some embodiments of the present application;

[0045] Figure 5 Process flow chart of the processing method of the positive electrode sheet provided for some embodiments of the present application;

[0046] Figure 6 Schematic diagram of the processing method of the positive electrode sheet provided for some embodiments of the present application in a side view perspective;

[0047] Figure 7 Schematic diagram of the processing method of the positive electrode sheet provided for some embodiments of the present application in a top view perspective.

[0048] Icon:

[0049] 1000 - vehicle;

[0050] 100 - battery; 200 - controller; 300 - motor;

[0051] 10 - box body; 11 - first part; 12 - second part; 13 - containing space;

[0052] 20 - battery cell; 21 - shell; 22 - electrode assembly; 23 - electrode terminal; 24 - pressure relief structure;

[0053] 211 - housing; 212 - cover; 213 - sealed space;

[0054] 221 - positive electrode sheet; 222 - negative electrode sheet; 223 - separator;

[0055] 2221 - first surface of the positive active material layer; 2222 - second surface of the positive active material layer;

[0056] A - thickness direction of the positive electrode sheet; B - specified direction; C - passing direction of the positive electrode sheet; D - gas delivery ignition device; L - specified distance. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0058] The embodiments of the technical scheme of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical scheme of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of the terms "including," "comprising," or "having" and variations thereof herein is intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof. Unless otherwise required by context, singular terms shall include pluralities and vice versa.

[0060] In the description of the embodiments of the present application, the technical terms "first", "second" and the like 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 technical features indicated.

[0061] In the description of the embodiments of the present application, the technical term "and / or", such as "feature 1 and / or feature 2", means that it can be "feature 1" alone, "feature 2" alone, or "feature 1" plus "feature 2". In addition, the character " / " herein generally indicates that the objects before and after are in an "or" relationship.

[0062] In the description of the embodiments of the present application, unless otherwise specified, the meaning of "multiple" in "one or more" is two or more.

[0063] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, or necessarily refer to different or alternative embodiments to each other. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with each other.

[0064] In the embodiments of the present application, the same reference signs represent the same components, and for the sake of brevity, detailed description of the same components is omitted in different embodiments. It should be understood that the height, length, width, etc. of various components in the embodiments of the present application shown in the drawings, and the overall height, length, width, etc. of the integrated device are only exemplary and should not constitute any limitation on the present application.

[0065] From the development of market situation, the application of power battery is more and more extensive. Power battery is not only applied to energy storage power supply system such as hydroelectric, thermal, wind and solar power station, but also widely used in electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, military equipment, aerospace and other fields. With the continuous expansion of the application field of power battery, the demand of its market is also increasing.

[0066] With the continuous development of the new energy industry, the market has put forward more diversified demands for the pole piece of the battery. The electrolyte infiltration performance of the positive pole piece is a factor affecting the performance of the battery, and improving the electrolyte infiltration performance of the positive pole piece is conducive to improving the rate performance, discharge capacity and the like of the battery.

[0067] With the increasing requirement for thick coating of the positive active material layer, the compaction density of the positive pole piece is getting larger and larger, and the pores between the active materials are getting smaller and smaller, which makes it difficult for the electrolyte to infiltrate therein. In some current technical solutions, in order to improve the infiltration performance, the positive pole piece is usually improved based on the above reasons.

[0068] However, research has found that the clogging of pores by the floating binder is an important reason affecting the electrolyte infiltration capacity of the positive pole piece, and the current technical solutions cannot effectively remove the floating binder in the positive pole piece.

[0069] Based on this, the embodiments of the present application propose a positive pole piece and a processing method thereof. The surface of the positive pole piece is subjected to a combustion treatment, and the floating binder can be ablated and reduced by the flame, which is conducive to improving the clogging of pores by the floating binder, thereby effectively improving the electrolyte infiltration performance of the positive pole piece.

[0070] The battery cell using the positive pole piece disclosed in the embodiments of the present application can be used in, but is not limited to, an electric device such as a vehicle, a ship or an aircraft. The embodiments of the present application provide an electric device using a battery as a power source, and the electric device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship, a spacecraft and the like. The electric toy can include a fixed or mobile electric toy, such as a game console, an electric automobile toy, an electric ship toy and an electric aircraft toy, and the spacecraft can include an airplane, a rocket, a space shuttle and a spacecraft and the like.

[0071] The following embodiments are described by taking a vehicle as an example for convenience of description.

[0072] Referring to Figure 1 , Figure 1A structural schematic diagram of a vehicle 1000 is provided for some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle, or a new energy vehicle, which can be a pure electric vehicle, a hybrid vehicle, or a range extended vehicle, etc. The vehicle 1000 is internally provided with a battery 100, which can be arranged at the bottom, head, or tail of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000, for example, the battery 100 can be used as an operating power source of the vehicle 1000. The vehicle 1000 can further include a controller 200 and a motor 300, the controller 200 is used to control the battery 100 to supply power to the motor 300, for example, to meet the power demand of the vehicle 1000 during starting, navigation, and driving.

[0073] In some embodiments of the present application, the battery 100 can not only be used as an operating power source of the vehicle 1000, but also be used as a driving power source of the vehicle 1000, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1000.

[0074] In the present application, the battery 100 refers to a single physical module including one or more battery monomers 20 to provide a certain voltage and capacity, which can be in the form of a battery pack, a battery module, etc. The battery 100 can include a box 10 for packaging one or more battery monomers 20, and the box 10 can avoid the influence of liquid or other foreign matters on the charging or discharging of the battery monomer 20.

[0075] Referring to Figure 2 , Figure 2 An exploded view of the battery 100 is provided for some embodiments of the present application. The battery 100 includes a box 10 and a plurality of battery monomers 20, and the plurality of battery monomers 20 are contained in the box 10. Among them, the box 10 is used to contain the battery monomer 20, and the box 10 can be of various structures. In some embodiments, the box 10 can include a first part 11 and a second part 12, the first part 11 and the second part 12 are mutually covered, and the first part 11 and the second part 12 jointly define a containing space 13 for containing the battery monomer 20. The second part 12 can be a hollow structure with one end open, and the first part 11 is a plate-shaped structure, which is covered on the open side of the second part 12 to form the box 10 with the containing space 13; the first part 11 and the second part 12 can also be hollow structures with one side open, and the open side of the first part 11 is covered on the open side of the second part 12 to form the box 10 with the containing space 13. Of course, the first part 11 and the second part 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0076] In the battery 100, a plurality of battery cells 20 can be connected in series, in parallel, or in a mixed manner, where the mixed manner refers to a manner in which a plurality of battery cells 20 are connected in series and in parallel. The plurality of battery cells 20 can be directly connected in series, in parallel, or in a mixed manner, and the plurality of battery cells 20 can be accommodated in the case 10 as a whole. Alternatively, the plurality of battery cells 20 can be connected in series, in parallel, or in a mixed manner to form a module, and a plurality of modules can be connected in series, in parallel, or in a mixed manner to form a whole and can be accommodated in the case 10. The battery 100 can include other structures, for example, a plurality of battery cells 20 can be electrically connected by a busbar to be connected in parallel, in series, or in a mixed manner.

[0077] The battery cell 20 refers to the smallest unit constituting a battery pack. The battery cell 20 can be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto.

[0078] Referring to FIG. 1, Figure 3 The battery cell 20 can include a case 21, an electrode assembly 22, and an electrolyte, and the electrode assembly 22 and the electrolyte can be accommodated in the case 21.

[0079] The case 21 can include a case body 211 and a cover 212. The case body 211 is a component for fitting the cover 212 to form an internal sealed space 213 of the battery cell 20, and the formed sealed space 213 can be used to accommodate the electrode assembly 22, the electrolyte, and other components. The cover 212 refers to a component that is fitted to an opening of the case body 211 to isolate the internal environment of the battery cell 20 from the external environment, and the shape of the cover 212 can be adapted to the shape of the case body 211 to fit the case body 211. The cover 212 can further include functional components such as an electrode terminal 23, a pressure relief structure 24, etc. A sealing ring can be disposed between the opening of the case body 211 and the cover 212 to seal the case body 211 and the cover 212.

[0080] The case body 211 and the cover 212 can have various shapes and sizes, such as a rectangular parallelepiped shape, a cylindrical shape, a hexagonal prism shape, etc. Specifically, the shape of the case body 211 and the cover 212 can be determined according to the specific shape and size of the electrode assembly 22. The case body 211 and the cover 212 can be made of various materials, such as, but not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, etc. The sealing ring can be made of various materials, such as, but not limited to, PP (polypropylene), PC (polycarbonate), PET (polyethylene terephthalate), etc. The outer surface of the case body 211 can be plated with a plating layer, and the plating layer can be made of various materials, such as, but not limited to, Ni, Cr, etc.

[0081] The battery cell 20 can also be in a soft package form, such as a pouch soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, polybutylene succinate, and the like can be listed.

[0082] Referring to Figure 4 , the electrode assembly 22 includes a negative electrode sheet 222, a separator 223, and a positive electrode sheet 221. The battery cell 20 mainly works by moving metal ions between the positive electrode sheet 221 and the negative electrode sheet 222. During charging and discharging, active ions are repeatedly intercalated and deintercalated between the positive electrode sheet 221 and the negative electrode sheet 222; the separator 223 is disposed between the positive electrode sheet 221 and the negative electrode sheet 222, mainly to prevent short circuiting between the positive and negative electrodes, while allowing ions to pass through. The electrode assembly 22 can be in a jelly-roll structure or a stacked structure, and the embodiments of the present application are not limited thereto.

[0083] The positive electrode sheet 221 includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer is disposed on at least one side of the positive electrode current collector. A primer layer or the like can also be disposed between the positive electrode active material layer and the positive electrode current collector.

[0084] The positive electrode current collector can be a metal foil or a composite current collector, for example, the material of the positive electrode current collector can be aluminum. The composite current collector can include a polymer material substrate and a metal layer formed on at least one side of the polymer material substrate, and the composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0085] The positive electrode active material in the positive electrode active material layer can include at least one of the following materials: lithium-containing phosphate with olivine structure, lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination with two or more. Examples of lithium transition metal oxides can include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3O2(also can be referred to as NCM 523 O2(also can be referred to as NCM 0.5 O2(also can be referred to as NCM 0.25 O2(also can be referred to as NCM 0.25 O2(also can be referred to as NCM 211 O2(also can be referred to as NCM 0.6 O2(also can be referred to as NCM 0.2 O2(also can be referred to as NCM 0.2 O2(also can be referred to as NCM 622 O2(also can be referred to as NCM 0.8 O2(also can be referred to as NCM 0.1 O2(also can be referred to as NCM 0.1 O2(also can be referred to as NCM 811 O2(also can be referred to as NCM 0.85 O2(also can be referred to as NCM 0.15 O2(also can be referred to as NCM 0.05 O2(also can be referred to as NCM

[0086] In some embodiments, the positive active material layer can further optionally include a binder. As an example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0087] In some embodiments, the positive active material layer can further optionally include a conductive agent. As an example, the conductive agent can include at least one of super P carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0088] The negative electrode tab 222 includes a negative current collector and a negative active material layer disposed on at least one side of the negative current collector. A primer layer or the like can be further disposed between the negative current collector and the negative active material layer.

[0089] The negative current collector can be a metal foil or a composite current collector. For example, the material of the negative current collector can be copper, and the composite current collector can include a polymer material substrate and a metal layer formed on at least one side of the polymer material substrate. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0090] The negative active material in the negative active material layer can be a negative active material such as carbon, silicon, or the like. As an example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, lithium titanate, and the like. The silicon-based material can be selected from at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can be selected from at least one of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative active material can also be used.

[0091] In some embodiments, the negative active material layer can also optionally include a binder. The binder can be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0092] In some embodiments, the negative active material layer can also optionally include a conductive agent. The conductive agent can be selected from at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0093] In some embodiments, the negative active material layer can also optionally include other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0094] The separator 223 is between the positive electrode tab 221 and the negative electrode tab 222 and serves to separate them. The type of the separator 223 is not particularly limited in the present application, and any known porous structure separator 223 having good chemical stability and mechanical stability can be used.

[0095] In some embodiments, the material of the separator 223 can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator 223 can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator 223 is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0096] Next, the positive electrode tab 221 and the processing method thereof according to the present application will be described in detail.

[0097] Referring to Figure 5 , in a first aspect, the present application provides a processing method of a positive electrode tab, comprising: performing a combustion treatment on a specified part of the positive electrode tab 221, wherein the specified part includes at least part of the surface of the positive active material layer of the positive electrode tab 221.

[0098] Referring to Figure 6 The surface of the positive electrode active material layer includes a first surface 2221 of the positive electrode active material layer and a second surface 2222 of the positive electrode active material layer. The first surface 2221 of the positive electrode active material layer refers to a surface of the positive electrode active material layer distributed along the thickness direction A of the positive electrode tab, in other words, the first surface of the positive electrode active material layer is substantially perpendicular to the thickness direction A of the positive electrode tab; the second surface 2222 of the positive electrode active material layer refers to a surface of the positive electrode active material layer substantially parallel to the thickness direction A of the positive electrode tab.

[0099] As an example, the specified site at least includes the first surface 2221 of the positive electrode active material layer.

[0100] The processing method of the positive electrode tab provided by the embodiments of the present application can perform combustion treatment on the surface of the positive electrode tab 221, and the binder floating up can be ablated and reduced by the flame, which is conducive to improving the blockage of the floating binder to the pores, can improve the porosity of the positive electrode active material layer, and thus can effectively improve the electrolyte wetting performance of the positive electrode tab 221.

[0101] In addition, it is found that although the combustion treatment consumes the binder in the positive electrode active material layer, since it consumes the floating binder, the adhesion between the positive electrode active material layer and the positive electrode current collector can be maintained. It is also found that although the combustion treatment reduces the resistance of the positive electrode tab 221, it is conducive to improving the electrical performance of the positive electrode tab 221.

[0102] In some embodiments, when the combustion treatment is completed, the burned area in the surface of the positive electrode active material layer reaches a specified temperature, and the specified temperature is 200-500°C.

[0103] As an example, the specified temperature is, for example but not limited to, any one of 200°C, 250°C, 300°C, 350°C, 400°C, 450°C or 500°C or a range value between any two of them.

[0104] When the combustion treatment is completed, it means that after the combustion treatment is completed and before the cooling treatment is performed; for example, it means that the burned area is detected within a certain distance downstream of the flame area when passing through the flame area, and the certain distance is, for example, 5-20 cm.

[0105] The specified temperature can be measured by a temperature measuring device such as an infrared temperature gun when the combustion treatment is completed.

[0106] In these embodiments, the burning area in the surface of the positive electrode active material layer is controlled to reach a specified temperature at the completion of the burning treatment, so that the surface of the positive electrode active material layer can be subjected to the burning treatment at a suitable temperature, which is conducive to better ablation and reduction of the floating binder, and can better improve the electrolyte wetting performance of the positive electrode sheet 221.

[0107] In some embodiments, the specified temperature is 300-500°C; optionally, the specified temperature is 350-470°C.

[0108] In these embodiments, a further specified temperature is satisfied to enable the surface of the positive electrode active material layer to be subjected to the burning treatment at a more suitable temperature, which is conducive to better ablation and reduction of the floating binder, and can better improve the electrolyte wetting performance of the positive electrode sheet 221.

[0109] In some embodiments, the binder in the positive electrode active material layer includes polyvinylidene fluoride.

[0110] For example, the binder in the positive electrode active material layer is mainly polyvinylidene fluoride, such as the binder being polyvinylidene fluoride.

[0111] Polyvinylidene fluoride, abbreviated as PVDF; has a relatively low decomposition temperature, about 280-350°C.

[0112] In these embodiments, the burning treatment can better remove the floating binder formed by polyvinylidene fluoride, and can better improve the electrolyte wetting performance of the positive electrode sheet 221.

[0113] In some embodiments, the positive electrode active material in the positive electrode active material layer includes lithium-containing phosphates.

[0114] For example, the positive electrode active material in the positive electrode active material layer is mainly lithium-containing phosphates, such as the positive electrode active material being lithium-containing phosphates.

[0115] The lithium-containing phosphates include Li 1+y1 Fe y2 Mn y3 M y4 P 1-y5 O 4-y6 , -0.8≤y1≤0.2, 0≤y2≤1, 0≤y3≤1, 0≤y4≤0.1, 0≤y5≤0.1, 0≤y6≤0.4, and M includes one or more of Al, Cu, Mg, Zn, Ni, Ti, V, Zr, Co, Ga, Sn, Sb, Nb, or Ge.

[0116] In these embodiments, the lithium-containing phosphate and the binder have a large temperature difference in decomposition temperature, which facilitates controlling the specified temperature to be above the decomposition temperature of the binder and below the decomposition temperature of the lithium-containing phosphate, so that the cathode active material layer can maintain good electrochemical performance while effectively removing the floating binder to improve the wettability.

[0117] In some embodiments, the lithium-containing phosphate includes lithium iron phosphate.

[0118] As an example, the lithium-containing phosphate is mainly lithium iron phosphate, for example, the lithium-containing phosphate is lithium iron phosphate.

[0119] The lithium iron phosphate includes Li 1+y1 Fe y2 P 1-y5 O 4-y6 y1, y5, and y6 are as previously described, and 0

[0120] In these embodiments, the lithium iron phosphate and the binder have a large temperature difference in decomposition temperature, which facilitates controlling the specified temperature to be above the decomposition temperature of the binder and below the decomposition temperature of the lithium-containing phosphate, so that the cathode active material layer can maintain good electrochemical performance while effectively removing the floating binder to improve the wettability.

[0121] In some embodiments, the combustion treatment includes combusting a fuel gas and treating the specified part by a flame.

[0122] The fuel gas includes a combustible gas, which is combusted at the specified location of the combustion treatment through a gas delivery point ignition device D such as a lance, a burner, or the like; in the process of delivering the fuel gas, a combustion-supporting gas can be delivered together with the fuel gas or separately from the fuel gas.

[0123] In the process of treating the specified part by the generated flame, the flame heats the specified part, so that the specified part is burned by the flame.

[0124] Optionally, the fuel gas includes one or more of methane, propane, or acetylene.

[0125] As an example, the fuel gas can be one of methane, propane, and acetylene.

[0126] As another example, the fuel gas includes multiple combustible gases, one or more of which are selected from methane, propane, or acetylene, and the fuel gas can further include other types of combustible gases, for example, the fuel gas is liquefied gas, coal gas, or natural gas.

[0127] In these embodiments, the combustion process is performed by burning the fuel gas, and the gas flow generated by the fuel gas can blow away the ablation product of the floating binder, which is conducive to the flame ablation of the floating binder more fully, and also conducive to the surface of the positive electrode sheet 221 maintaining better cleanliness.

[0128] In some embodiments, in the combustion process, the flow rate of the fuel gas is 3 L / min to 12 L / min; optionally, the flow rate of the fuel gas is 5 L / min to 8 L / min.

[0129] The flow rate of the specified gas refers to the volume of the specified gas supplied per unit time.

[0130] For example, the flow rate of the fuel gas is any one of 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min, 10 L / min, 11 L / min, or 12 L / min, or a range value between any two of them.

[0131] In these embodiments, a suitable flow rate of the fuel gas is maintained in the combustion process, so that the flame can provide suitable heat for the specified part, and the floating binder can be effectively removed by a suitable temperature to improve the wetting performance.

[0132] In some embodiments, in the combustion process, the flow rate of the air is 70 L / min to 260 L / min; optionally, the flow rate of the air is 120 L / min to 180 L / min.

[0133] For example, the flow rate of the air is any one of 70 L / min, 80 L / min, 90 L / min, 100 L / min, 110 L / min, 120 L / min, 130 L / min, 140 L / min, 150 L / min, 160 L / min, 170 L / min, 180 L / min, 190 L / min, 200 L / min, 210 L / min, 220 L / min, 230 L / min, 240 L / min, 250 L / min, or 260 L / min, or a range value between any two of them.

[0134] In these embodiments, a suitable flow rate of the air is maintained in the combustion process, which is conducive to meeting a suitable air-fuel ratio, so that the flame can provide suitable heat for the specified part, and the floating binder can be effectively removed by a suitable temperature to improve the wetting performance.

[0135] In some embodiments, in the combustion process, the air-fuel ratio is (2-5): 1; optionally, the air-fuel ratio is (3-4): 1.

[0136] As an example, the air-fuel ratio is for example but not limited to any one of the point values of 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1 or the range value between any two of them.

[0137] The air-fuel ratio is a common knowledge in the art, has the meaning known in the art, and can be measured by the instruments and test methods known in the art. As an example, the air-fuel ratio refers to the mass ratio between air and fuel gas, which can be regulated by a method of matching the flow rate of fuel gas and air, for example, mixing fuel gas and air according to a specific flow rate according to the air-fuel ratio requirement, and then burning the mixed gas.

[0138] In these embodiments, a suitable air-fuel ratio is met in the combustion process, so that the flame can provide suitable heat for the specified part, and the floating binder can be effectively removed by suitable temperature to improve the wettability.

[0139] Referring to Figure 6 In some embodiments, in the combustion process, the fuel gas is sprayed toward the positive electrode tab 221 at a specified distance L from the positive electrode tab 221, and the specified distance L is 5-10 cm; optionally, the specified distance L is 5-7.5 cm.

[0140] As an example, the specified distance L is for example but not limited to any one of the point values of 5 cm, 6 cm, 7 cm, 8 cm, 9 cm or 10 cm or the range value between any two of them.

[0141] Referring to Figure 6 The specified distance L refers to the vertical distance between the combustion port of the fuel gas and the first surface 2221 of the positive electrode tab, i.e. the distance from the combustion port of the fuel gas to the first surface 2221 of the positive electrode tab along the thickness direction A of the positive electrode tab.

[0142] In these embodiments, the fuel gas is sprayed toward the positive electrode tab 221 at a suitable specified distance for combustion, which is beneficial to regulate the temperature of the flame acting on the positive electrode tab 221, and the floating binder can be better removed to improve the wettability.

[0143] Referring to Figure 6 In some embodiments, in the combustion process, the fuel gas is sprayed toward the positive electrode tab 221 in a specified direction B, and the included angle between the specified direction B and the thickness direction A of the positive electrode tab is 0-30°; optionally, the included angle between the specified direction B and the thickness direction A of the positive electrode tab is 0-10°.

[0144] As an example, the angle between the specified direction B and the thickness direction A of the positive electrode tab is, for example but not limited to, any one of 0°, 5°, 10°, 15°, 20°, 25°, or 30°, or a range value between any two of them.

[0145] When the angle between the specified direction B and the thickness direction A of the positive electrode tab is 0°, the specified direction B is substantially perpendicular to the first surface 2221 of the positive electrode active material layer; when the angle between the specified direction B and the thickness direction A of the positive electrode tab is 90°, the specified direction B is substantially parallel to the first surface 2221 of the positive electrode active material layer.

[0146] Referring to Figure 6 , the specified direction B refers to the direction of the gas when it is ejected from the combustion port, and the specified direction B is substantially consistent with the axial direction of the combustion port.

[0147] In these embodiments, the gas is ejected at a suitable specified angle towards the positive electrode tab 221 for combustion, so that the flame can better burn the positive electrode tab 221, and the floating binder can be more effectively removed to improve the wettability.

[0148] In some embodiments, in the combustion process, the positive electrode tab 221 passes through the flame at a specified speed, and the specified speed is 40 m / min to 100 m / min; optionally, the specified speed is 50 m / min to 80 m / min.

[0149] As an example, the specified speed is, for example but not limited to, any one of 40 m / min, 50 m / min, 60 m / min, 70 m / min, 80 m / min, 90 m / min, or 100 m / min, or a range value between any two of them.

[0150] Referring to Figure 6 and Figure 7 In the embodiments of the present application, optionally, the position of the gas delivery ignition device D that ejects the ignited gas is fixed, and the positive electrode tab 221 is conveyed relative to the gas delivery ignition device D at a specified speed by means of a belt, a roller, or the like, so that the positive electrode tab 221 passes through the flame at a specified speed.

[0151] As an example, the first surface 2221 of the positive electrode active material layer is placed flat on the conveying surface for conveying, that is, the passing direction C of the positive electrode tab is substantially perpendicular to the thickness direction A of the positive electrode tab.

[0152] In these embodiments, the positive electrode tab 221 passes through the flame at a suitable specified speed, which is conducive to controlling the surface of the positive electrode tab 221 to reach a suitable temperature, and the floating binder can be better removed to improve the wettability.

[0153] In some example embodiments, the positive electrode tab 221 includes a first edge oppositely distributed along a first direction and a second edge oppositely distributed along a second direction; for example, the first direction and the second direction are two directions perpendicular to each other. During the combustion treatment, the positive electrode tab 221 passes through the flame along the second direction, and the flame can at least cover the entire range of the first surface 2221 of the positive electrode active material layer in the first direction (i.e., can cover from one side edge to the opposite side edge in the first direction), so that the entire positive electrode tab 221 passes through the flame along the second direction as described above, and the first surface 2221 of the entire positive electrode active material layer facing the flame is subjected to the combustion treatment.

[0154] In a second aspect, the embodiments of the present application provide a positive electrode tab 221 processed according to the processing method of the positive electrode tab as described above.

[0155] In some embodiments, the positive electrode tab 221 has an electrolyte infiltration speed > 0.27 μg / s, and optionally, the positive electrode tab 221 has an electrolyte infiltration speed ≥ 0.33 μg / s.

[0156] In these embodiments, the positive electrode tab 221 has a high electrolyte infiltration speed, and the positive electrode tab 221 has good electrolyte infiltration performance.

[0157] In some embodiments, the positive electrode tab 221 has a porosity > 29.2%, and optionally, the positive electrode tab 221 has a porosity ≥ 32.6%.

[0158] In these embodiments, the positive electrode tab 221 has a high porosity, which is conducive to improving the electrolyte infiltration performance of the positive electrode tab 221.

[0159] In a third aspect, the embodiments of the present application provide a battery 100 including the positive electrode tab 221 as described above.

[0160] In a fourth aspect, the embodiments of the present application provide a power consumption device including the battery 100 as described above.

[0161] Some specific embodiments are listed below to better illustrate the present application.

[0162] I. Processing the positive electrode tab

[0163] (1) Preparation of the positive electrode tab

[0164] Lithium iron phosphate (LFP), conductive agent carbon black, polyvinylidene fluoride (PVDF), and N-methyl pyrrolidone (NMP) were stirred and mixed uniformly at a weight ratio of 97:2:1:21 to obtain a positive electrode slurry; then the positive electrode slurry was uniformly coated on the positive electrode current collector, and then subjected to drying, cold pressing, and slitting to obtain the positive electrode tab.

[0165] (2) Surface treatment of the positive electrode tab

[0166] The positive electrode tab is placed in the conveying device, the gas is ignited, and the positive electrode tab is passed through the flame by the conveying device, so that the first surface of the entire active material layer facing the flame is treated by the flame.

[0167] Wherein, the placement direction of the positive electrode tab, the passing direction of the positive electrode tab, the configuration position of the gas conveying ignition device, etc. are as shown in Figure 6 and Figure 7 ; The flow rate of the gas, the flow rate of the air, the air-fuel ratio, the included angle between the specified direction and the thickness direction of the positive electrode tab, the specified distance, the specified speed, etc. Process parameter conditions are shown in Table 1.

[0168] Table 1. Process parameter conditions

[0169]

[0170]

[0171] In Table 1, Comparative Example 1 represents that the positive electrode tab is not subjected to combustion treatment.

[0172] In addition, it should be noted that since the composition of the gas and air used in different embodiments may be slightly different, the difference in the flow ratio of the gas and air between different embodiments, and the difference in the air-fuel ratio, are not necessarily 1:1. For example, between Example 1 and Example 2, the flow ratio of the gas and air is different, while the air-fuel ratio of the two is the same.

[0173] II. Test method

[0174] (1) Specified temperature detection

[0175] When the positive electrode tab passes through the flame area, the surface temperature of the positive electrode tab is detected at a distance of 8 cm downstream of the flame area using an infrared temperature gun, and the specified temperature is detected.

[0176] (2) Electrolyte wettability detection

[0177] The positive electrode tab is fixed on a clean glass plate; 0.2mm capillary is used to suck 3mm height electrolyte, and then directly contact with the positive electrode tab, so that the positive electrode tab absorbs the electrolyte, and the time of absorbing the electrolyte is measured, and the electrolyte absorption rate, i.e. the wettability, is obtained by conversion.

[0178] (3) Porosity detection

[0179] In the drying room, use tweezers to select >20 pieces of good-looking round pieces with no powder on the edge and put them into the sample cup. Record the number of pieces and calculate the apparent volume. Place the sample cup containing the sample in the true density tester, close the test system, and according to the program, helium is introduced. The porosity of the sample to be tested is obtained by detecting the pressure of the gas in the sample chamber and the expansion chamber, and then calculating the true volume according to the Boyle law (PV = nRT).

[0180] (4) Resistance detection

[0181] Cut a small round piece with a diameter of 10 mm at the left, middle and right of the positive electrode piece. Turn on the indicator light of the Yuankang Technology electrode resistance meter, place the small round piece in the "probe" of the diaphragm resistance meter, click the "start" button, and read the value when the value is stable. Test two positions for each small round piece, and finally calculate the average value of six measurements, which is the diaphragm resistance of the positive electrode piece.

[0182] (5) Adhesion detection

[0183] Cut the positive electrode piece into a test sample with a size of 20*100mm 2 The test sample is prepared; the test sample is adhered with double-sided tape on the side to be tested, and is pressed with a roller to make the double-sided tape completely adhere to the test sample; the other side of the double-sided tape of the test sample is adhered to the surface of stainless steel, and one end of the test sample is bent in the opposite direction with an angle of 180°; use a high-tension testing machine to test, fix one end of the stainless steel to the lower clamp of the tension testing machine, and fix the bent end of the test sample to the upper clamp, adjust the angle of the test sample to ensure that the upper and lower ends are perpendicular, then stretch the test sample at a speed of 50mm / min until the test sample is completely peeled off from the substrate, record the displacement and force during the process, and the force at the time of force balance is generally considered as the adhesion of the positive electrode piece.

[0184] III. Test results and analysis of results

[0185] The test results of the positive electrode piece are shown in Table 2.

[0186] Table 2

[0187]

[0188]

[0189] Based on Table 1 and Table 2, the brief analysis is as follows:

[0190] In Examples 1 to 21, the positive electrode sheet was subjected to the combustion treatment; in Comparative Example 1, the positive electrode sheet was not subjected to the combustion treatment. In Examples 1 to 21 and Comparative Example 1, the impregnation rate and the porosity of the positive electrode sheet were improved to different degrees. Moreover, in Examples 1 to 21, the adhesion was maintained to be good, and the sheet resistance was not deteriorated but was reduced to different degrees, as compared with Comparative Example 1.

[0191] In Examples 1 to 21, when the temperature of the surface of the electrode sheet reached 300°C or higher, and further reached 350°C or higher, the impregnation rate and the porosity of the positive electrode sheet were able to reach a good level.

[0192] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the same; although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that the technical solutions recorded in the above examples can still be modified, or some or all of the technical features can be replaced 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 above examples, and they should be covered in the scope of the claims and the specification of the present application. In particular, the technical features mentioned in each example can be combined in any way as long as there is no structural conflict. The present application is not limited to the specific examples disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method of processing a positive electrode sheet, characterized by, The method comprises: a combustion treatment is performed on a specified part of a positive electrode tab, wherein the specified part includes at least part of a surface of a positive electrode active material layer of the positive electrode tab; when the combustion treatment is completed, a burned area of the surface of the positive electrode active material layer reaches a specified temperature, and the specified temperature is 300-500°C; the combustion treatment includes combustion of a combustion gas and treatment of the specified part by a flame, and in the combustion treatment, an air-fuel ratio is (2-5):1, and the combustion gas is injected to be combusted at a specified distance from the positive electrode tab, and the specified distance is 5-10 cm.

2. The method of claim 1, wherein The specified temperature is 350-470°C.

3. The method of claim 1, wherein The binder in the positive electrode active material layer includes polyvinylidene fluoride.

4. The method of claim 1, wherein The positive electrode active material in the positive electrode active material layer includes lithium-containing phosphate.

5. The method of claim 4, wherein The lithium-containing phosphate includes lithium iron phosphate.

6. The method of claim 1, wherein In the combustion treatment, the flow rate of the combustion gas is 3-12 L / min.

7. The method of claim 6, wherein the positive electrode sheet is treated by a method comprising: The flow rate of the combustion gas is 5-8 L / min.

8. The method of claim 1, wherein In the combustion treatment, the flow rate of air is 70-260 L / min.

9. The method of claim 8, wherein the positive electrode sheet is treated by a method comprising: The flow rate of air is 120-180 L / min.

10. The method of claim 1 to 9, wherein The air-fuel ratio is (3-4):

1.

11. The method of claim 1 to 9, wherein The specified distance is 5-7.5 cm.

12. The method of claim 1 to 9, wherein In the combustion treatment, the combustion gas is injected to be combusted toward the positive electrode tab in a specified direction, and the included angle between the specified direction and the thickness direction of the positive electrode tab is 0-30°.

13. The method of claim 12, wherein the positive electrode sheet is treated by a method comprising: The included angle between the specified direction and the thickness direction of the positive electrode tab is 0-10°.

14. The method of claim 1 to 9, wherein In the combustion treatment, the positive electrode tab passes through the flame at a specified speed, and the specified speed is 40-100 m / min.

15. The method of claim 14, wherein the positive electrode sheet is treated by a method comprising: The specified speed is 50-80 m / min.

16. A positive electrode sheet characterized by comprising: The positive electrode tab is obtained by the method for treating a positive electrode tab according to any one of claims 1-15.

17. The cathode sheet of claim 16, wherein, The positive electrode tab has an electrolyte infiltration speed >0.27 μg / s.

18. The cathode sheet of claim 17, wherein, The positive electrode tab has an electrolyte infiltration speed ≥0.33 μg / s.

19. The positive electrode plate of any one of claims 16-18, wherein, The positive electrode tab has a porosity >29.2%.

20. The cathode sheet of claim 19, wherein, The positive electrode tab has a porosity ≥32.6%.

21. A battery, characterized by The battery comprises the positive electrode tab according to any one of claims 16-20.

22. An electrical device, comprising: The battery comprises the positive electrode tab according to claim 21.

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