Negative electrode sheet, processing method thereof, battery, and electric device

Abstract

A negative electrode sheet, a processing method of the negative electrode sheet, a battery, and a power utilization device, the processing method of the negative electrode sheet comprising: performing a combustion treatment on a specified part of the negative electrode sheet, the specified part at least including an edge of the negative electrode sheet, the combustion treatment comprising combusting a combustion gas and heating the specified part by a flame generated. In the processing method of the negative electrode sheet, the edge of the negative electrode sheet is subjected to the combustion treatment, burrs are ablated by the flame, and the burr problem of the negative electrode sheet at the edge is improved.

Description

TECHNICAL FIELD

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

[0002] The negative electrode sheet is prone to burr at the edge when slitting, and the burr is prone to cause poor self-discharge of the battery. SUMMARY

[0003] In view of the above problems, the present application provides a negative electrode sheet, a processing method thereof, a battery and an electric device, which are beneficial to improve the burr problem of the negative 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 negative electrode sheet, comprising: performing combustion treatment on a specified part of the negative electrode sheet, wherein the specified part at least includes an edge of the negative electrode sheet, and the combustion treatment comprises combustion of a combustion gas and treatment of the specified part by a generated flame.

[0006] The processing method of the negative electrode sheet provided by the embodiments of the present application performs combustion treatment on the edge of the negative electrode sheet, and the burr is ablated by the flame, which is beneficial to improve the burr problem of the negative electrode sheet at the edge. In addition, the burr ablation product is blown away by the airflow generated by the combustion of the combustion gas, which is beneficial to more fully ablate the burr of the edge of the negative electrode sheet by the flame, and also beneficial to keep the surface of the negative electrode sheet clean.

[0007] In some embodiments, the combustion treatment is performed by spraying the combustion gas toward the negative electrode sheet in a specified direction, and an included angle between the specified direction and a thickness direction of the negative electrode sheet is 0°-60°.

[0008] In these embodiments, the combustion gas is sprayed toward the negative electrode sheet in a suitable specified angle, which is beneficial to stabilize the flame, so that the flame can better perform the combustion treatment on the negative electrode sheet, and also beneficial to quickly blow away the ablation product by the airflow, which is beneficial to better reduce the burr failure rate of the edge of the negative electrode sheet.

[0009] In some embodiments, the included angle between the specified direction and the thickness direction of the negative electrode sheet is 0°-30°.

[0010] In these embodiments, the combustion gas is sprayed toward the negative electrode sheet in a further specified angle, which is more beneficial to stabilize the flame, so that the flame can better perform the combustion treatment on the negative electrode sheet, and also more beneficial to quickly blow away the ablation product by the airflow, which is more beneficial to better reduce the burr failure rate of the edge of the negative electrode sheet.

[0011] In some embodiments, in the combustion treatment, the fuel gas is sprayed towards the negative electrode sheet at a specified distance of 3cm-15cm from the negative electrode sheet.

[0012] In these embodiments, the fuel gas is sprayed towards the negative electrode sheet at a specified distance, which is conducive to regulating the temperature of the flame acting on the negative electrode sheet, so that the flame can better burn the negative electrode sheet, and is conducive to better reducing the burr failure rate of the edge of the negative electrode sheet.

[0013] In some embodiments, the specified distance is 5cm-15cm.

[0014] In these embodiments, the fuel gas is sprayed towards the negative electrode sheet at a further specified distance, which is conducive to more appropriately regulating the temperature of the flame acting on the negative electrode sheet, so that the flame can better burn the negative electrode sheet, and is conducive to better reducing the burr failure rate of the edge of the negative electrode sheet.

[0015] In some embodiments, in the combustion treatment, the negative electrode sheet passes through the flame at a specified speed of 50m / min-150m / min.

[0016] In these embodiments, the negative electrode sheet is passed through the flame at a specified speed, which is conducive to controlling the surface of the negative electrode sheet to reach a suitable temperature, so that the flame can better burn the negative electrode sheet, and is conducive to better reducing the burr failure rate of the edge of the negative electrode sheet.

[0017] In some embodiments, the specified speed is 50m / min-80m / min.

[0018] In these embodiments, the negative electrode sheet is passed through the flame at a further specified speed, which is conducive to controlling the surface of the negative electrode sheet to reach a more suitable temperature, so that the flame can better burn the negative electrode sheet, and is conducive to better reducing the burr failure rate of the edge of the negative electrode sheet.

[0019] In some embodiments, in the combustion treatment, the air-fuel ratio is (5-14):1.

[0020] In these embodiments, the combustion treatment satisfies a suitable air-fuel ratio, which is conducive to the sufficient combustion of the fuel gas and the stability of the flame temperature, can better burn the negative electrode sheet, and is conducive to better reducing the burr failure rate of the edge of the negative electrode sheet.

[0021] In some embodiments, the air-fuel ratio is (5-8):1.

[0022] In these embodiments, a further air-fuel ratio is achieved during the combustion process, which is beneficial for the complete combustion of the gas while maintaining a more stable flame temperature. This allows for better combustion of the negative electrode sheet and also helps to remove burr erosion products, thus reducing the burr defect rate at the edge of the negative electrode sheet.

[0023] In some embodiments, the temperature of the flame is 900°C to 1300°C.

[0024] In these embodiments, the flame reaches a specific temperature, which is beneficial for effectively ablating away the burrs at the edges of the negative electrode current collector and the negative electrode active material layer.

[0025] In some embodiments, the designated portion includes a designated surface of the negative electrode sheet, which is the surface of the negative electrode sheet distributed in the thickness direction.

[0026] In these embodiments, the designated area includes the surface of the negative electrode sheet distributed in the thickness direction, so that the combustion treatment can also achieve surface modification of the entire surface of the negative electrode sheet.

[0027] In some embodiments, the fuel gas includes one or more of methane, propane, butane, pentane, pentene, or acetylene.

[0028] In these embodiments, the gas includes a specific type of gas source, which facilitates the control of the flame to reach a suitable temperature, which is beneficial for better ablation of the burrs at the edges of the negative electrode current collector and the negative electrode active material layer; at the same time, the flame generated by the combustion of the gas contains a large amount of strong oxidizing gas, which reacts with the surface of the negative electrode sheet at high temperature, bringing in charged polar functional groups, which is beneficial for improving the surface energy of the negative electrode sheet.

[0029] Secondly, embodiments of this application provide a negative electrode sheet, which is obtained by processing according to the negative electrode sheet processing method described in the above embodiments.

[0030] Thirdly, embodiments of this application provide a battery including a negative electrode as described in the above embodiments.

[0031] Fourthly, embodiments of this application provide an electrical device, including a battery as described in the above embodiments.

[0032] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are described below. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0035] Figure 2 Exploded views of batteries provided for some embodiments of this application;

[0036] Figure 3 Exploded views of a single battery cell provided in some embodiments of this application;

[0037] Figure 4 This is a schematic diagram of the structure of an electrode assembly provided in some embodiments of this application;

[0038] Figure 5 A process flow diagram of the negative electrode sheet processing method provided in some embodiments of this application;

[0039] Figure 6 This is a schematic diagram of the structure of the negative electrode sheet provided in some embodiments of this application;

[0040] Figure 7 A schematic diagram of the negative electrode processing method provided in some embodiments of this application from a side view.

[0041] Figure 8 A schematic diagram from a top view of the method for processing the negative electrode sheet provided in some embodiments of this application;

[0042] Figure 9 The morphological photographs of the edge of the negative electrode sheet provided in some embodiments and comparative examples of this application;

[0043] Figure 10 Photographs showing the test results of the surface energy of the negative electrode sheet provided in some embodiments and comparative examples of this application.

[0044] icon:

[0045] 1000 - Vehicles;

[0046] 100 - Battery; 200 - Controller; 300 - Motor;

[0047] 10-Box body; 11-First part; 12-Second part; 13-Accommodation space;

[0048] 20-Battery cell; 21-Casing; 22-Electrode assembly; 23-Electrode terminal; 24-Pressure relief structure;

[0049] 211-Shell; 212-Cover; 213-Sealed space;

[0050] 221 - Positive electrode; 222 - Negative electrode; 223 - Separator membrane;

[0051] 2221 - Edge of the negative electrode; 2222 - Designated surface of the negative electrode;

[0052] A - Specified direction; B - Thickness direction of the negative electrode sheet; C - Passage direction of the negative electrode sheet; D - Gas delivery and ignition device; L - Specified distance. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0054] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0055] 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 pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0056] In the description of the embodiments of this application, the technical terms "first", "second", etc. are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0057] In the description of the embodiments of this application, the technical terms "and / or", such as "feature 1 and / or feature 2", all refer to "feature 1" alone, "feature 2" alone, or "feature 1" plus "feature 2". In addition, the character " / " in this document generally indicates that the objects before and after it are in an "or" relationship.

[0058] In the description of the embodiments of this application, unless otherwise stated, "multiple" in "one or more" means two or more.

[0059] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0060] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the height, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall height, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0061] From a market perspective, the application of power batteries is becoming increasingly widespread. Power batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of the application areas of power batteries, the market demand is also constantly increasing.

[0062] With the continuous development of the new energy industry, the market has put forward more diversified demands for battery electrodes. Current research on electrodes mainly focuses on material modification, internal microstructure adjustment, and surface treatment.

[0063] In the production process of electrode sheets, an active material layer is usually formed on the surface of the current collector before slitting. During the slitting of the negative electrode sheet, burrs are easily generated at the edges. The presence of burrs can easily cause poor self-discharge of the battery, which may lead to safety accidents.

[0064] In some current technical solutions, in order to reduce the impact of edge burrs, the separator is usually improved, such as thickening the separator 223 at the position corresponding to the edge of the electrode or increasing the number of separator layers. However, this approach increases the material cost of the separator and the time and material costs of battery production and assembly, and it cannot fundamentally solve the hidden danger of burrs.

[0065] Based on this, this application proposes a negative electrode sheet and its processing method, which involves burning the edges of the negative electrode sheet to erode the burrs, thus improving the burr problem at the edges of the negative electrode sheet. This processing method can fundamentally improve the potential hazards of burrs, and is simple to operate and low in cost.

[0066] The battery cell using the negative electrode disclosed in this application can be used, but is not limited to, in electrical devices such as vehicles, ships, or aircraft. This application provides an electrical device that uses a battery as a power source. This device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., while spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0067] For ease of explanation, the following embodiments use a vehicle as an example of an electrical device according to an embodiment of this application.

[0068] See Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery 100 is disposed inside the vehicle 1000, and the battery 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also 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 needs of the vehicle 1000 during startup, navigation, and driving.

[0069] In some embodiments of this application, the battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0070] In this application, battery 100 refers to a single physical module comprising one or more battery cells 20 to provide a certain voltage and capacity, which may be in the form of a battery pack, battery module, etc. Battery 100 may include a housing 10 for encapsulating one or more battery cells 20, the housing 10 preventing liquids or other foreign matter from affecting the charging or discharging of the battery cells 20.

[0071] See Figure 2 , Figure 2This is an exploded view of a battery 100 provided in some embodiments of this application. The battery 100 includes a housing 10 and a plurality of battery cells 20, which are housed within the housing 10. The housing 10 is used to house the battery cells 20 and can have various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which overlap each other, defining a receiving space 13 for accommodating the battery cells 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, overlapping the open side of the second portion 12 to form a housing 10 with the receiving space 13; alternatively, the first portion 11 and the second portion 12 may both be hollow structures with one open side, overlapping the open side of the second portion 12 to form a housing 10 with the receiving space 13. Of course, the first portion 11 and the second portion 12 can have various shapes, such as cylinders, cuboids, etc.

[0072] In battery 100, multiple battery cells 20 can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed configuration, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, multiple battery cells 20 can first be connected in series, parallel, or in a mixed configuration to form modules, and then these modules can be connected in series, parallel, or in a mixed configuration to form a whole, which is also housed within the housing 10. Battery 100 may also include other structures; for example, multiple battery cells 20 can be electrically connected through a busbar component to achieve parallel, series, or mixed configurations of the multiple battery cells 20.

[0073] The battery cell 20 refers to the smallest unit that makes up the 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 to these.

[0074] See Figure 3 The battery cell 20 may include a housing 21, an electrode assembly 22 and an electrolyte, with the electrode assembly 22 and the electrolyte both housed within the housing 21.

[0075] The outer casing 21 may include a housing 211 and a cover 212. The housing 211 is an assembly that fits with the cover 212 to form an internal sealed space 213 of the battery cell 20, wherein the formed sealed space 213 can be used to accommodate the electrode assembly 22, electrolyte, and other components. The cover 212 is a component that covers the opening of the housing 211 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the cover 212 may be adapted to the shape of the housing 211 to fit the housing 211, and functional components such as electrode terminals 23 and pressure relief structures 24 may also be provided on the cover 212. A sealing ring may be provided between the opening of the housing 211 and the cover 212 to achieve a seal between the housing 211 and the cover 212.

[0076] The housing 211 and cover 212 can be of various shapes and sizes, such as cuboids, cylinders, and hexagonal prisms. Specifically, the shapes of the housing 211 and cover 212 can be determined according to the specific shape and size of the electrode assembly 22. The materials of the housing 211 and cover 212 can be various, such as, but not limited to, metals like copper, iron, aluminum, stainless steel, and aluminum alloys. The materials of the sealing ring can be various, such as, but not limited to, materials resistant to electrolyte corrosion, high toughness, and fatigue resistance, such as PP (polypropylene), PC (polycarbonate), and PET (polyethylene terephthalate). A plating layer can be formed on the outer surface of the housing 211, and the plating layer material can be various, such as, but not limited to, corrosion-resistant materials like Ni and Cr.

[0077] The battery cell 20 can also be in a pouch form, such as a bag-type pouch. The material of the pouch can be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0078] See Figure 4 The electrode assembly 22 includes a negative electrode 222, a separator 223, and a positive electrode 221. The battery cell 20 primarily functions by the movement of metal ions between the positive electrode 221 and the negative electrode 222. During charging and discharging, active ions repeatedly insert and extract between the positive and negative electrode 221 and the negative electrode 222. The separator 223, disposed between the positive and negative electrode 221 and the negative electrode 222, primarily serves to prevent short circuits between the positive and negative electrodes while allowing ions to pass through. The electrode assembly 22 can be a wound structure or a stacked structure; the embodiments of this application are not limited to either.

[0079] The positive electrode 221 includes a positive current collector and a positive active material layer. The positive active material layer is disposed on at least one side of the positive current collector. An undercoating layer may also be disposed between the positive active material layer and the positive current collector.

[0080] 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 may 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 (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.).

[0081] The positive electrode active material in the positive electrode active material layer may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 085 Co 015 Al 005 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0082] In some embodiments, the positive electrode active material layer may optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0083] In some embodiments, the positive electrode active material layer may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0084] The negative electrode 222 includes a negative current collector and a negative active material layer. The negative active material layer is disposed on at least one side of the negative current collector. An undercoating layer may also be disposed between the negative current collector and the negative active material layer.

[0085] The negative electrode current collector can be a metal foil or a composite current collector. For example, the material of the negative electrode current collector can be copper. 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.).

[0086] The negative electrode active material in the negative electrode active material layer can be carbon, silicon, or other negative electrode active material materials. As an example, the negative electrode active material material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active material materials may also be used.

[0087] In some embodiments, the negative electrode active material layer may optionally include a binder. The binder may 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).

[0088] In some embodiments, the negative electrode active material layer may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0089] In some embodiments, the negative electrode active material layer may also optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0090] The separator 223 is located between the positive electrode 221 and the negative electrode 222, and plays a role in isolation. In this embodiment, there is no particular limitation on the type of separator 223, and any well-known porous structure separator 223 with good chemical and mechanical stability can be selected.

[0091] In some embodiments, the material of the separator 223 may be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator 223 may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator 223 is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0092] The following section provides a detailed description of the negative electrode 222 and its processing method as proposed in the embodiments of this application.

[0093] See Figure 5 In a first aspect, embodiments of this application provide a method for processing a negative electrode sheet, comprising: performing a combustion treatment on a designated portion of the negative electrode sheet 222, wherein, see... Figure 6 The designated area includes at least the edge 2221 of the negative electrode sheet, and the combustion process includes burning gas and treating the designated area with the generated flame.

[0094] The specified portion includes at least the edge 2221 of the negative electrode sheet, meaning that the specified portion is not limited to only the edge 2221 of the negative electrode sheet, but may also include the non-edge portion of the negative electrode sheet 222.

[0095] The edge 2221 of the negative electrode sheet may include the edge of the negative electrode active material layer and / or the edge of the negative electrode current collector. The edge 2221 of the negative electrode sheet may be located at the edge of a designated surface 2222 of the negative electrode sheet and / or on the side of the negative electrode sheet 222. See also... Figure 7 and Figure 8 The designated surface 2222 of the negative electrode sheet refers to the surface of the negative electrode sheet 222 distributed in the thickness direction. In other words, the designated surface 2222 of the negative electrode sheet is basically perpendicular to the thickness direction B of the negative electrode sheet. The side surface of the negative electrode sheet 222 refers to the surface that is basically parallel to the thickness direction B of the negative electrode sheet.

[0096] As an example, the negative electrode sheet 222 is a die-cut strip, including a first edge distributed opposite to each other along a first direction and a second edge distributed opposite to each other along a second direction. The first edge is the die-cut edge of the die-cut strip, which may be an edge with a negative electrode tab die-cut or an edge without a negative electrode tab die-cut. The designated portion includes at least one of the first edges. Exemplarily, the first direction and the second direction are two directions that are perpendicular to each other.

[0097] The combustion gas includes combustible gases, such as those introduced into the designated location of the combustion process through a gas delivery and ignition device D such as a spray gun or burner; during the delivery of the combustion gas, the auxiliary combustion gas can optionally be delivered together with the combustion gas or delivered separately from the combustion gas.

[0098] During the process of treating a designated area with the generated flame, the flame heats the designated area, causing it to be burned by the flame.

[0099] The negative electrode processing method provided in this application involves burning the edge 2221 of the negative electrode to shave off burrs, which helps to improve the burr problem at the edge of the negative electrode 222. Furthermore, the combustion process using combustion gas allows the airflow generated by the gas to blow away the burr ablation products, facilitating more thorough ablation of the burrs on the edge 2221 of the negative electrode and maintaining a good surface cleanliness of the negative electrode 222.

[0100] See Figure 7 In some embodiments, during the combustion process, combustion gas is injected toward the negative electrode 222 in a designated direction A, and the angle between the designated direction A and the thickness direction B of the negative electrode is 0° to 60°.

[0101] As an example, the angle between the specified direction A and the thickness direction B of the negative electrode sheet is, for example, but not limited to, any one of 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55° or 60°, or a range between any two.

[0102] When the angle between the specified direction A and the thickness direction B of the negative electrode is 0°, the specified direction A is substantially perpendicular to the specified surface 2222 of the negative electrode; when the angle between the specified direction A and the thickness direction B of the negative electrode is 90°, the specified direction A is substantially parallel to the specified surface 2222 of the negative electrode.

[0103] See Figure 7 The specified direction A refers to the direction in which the gas is ejected from the combustion port, and this specified direction A is basically consistent with the axis of the combustion port.

[0104] In these embodiments, injecting gas at a suitable specified angle toward the negative electrode 222 for combustion helps to stabilize the flame, enabling the flame to better burn the negative electrode 222. At the same time, it helps the airflow to quickly blow away the ablation products, which helps to better reduce the burr defect rate of the edge 2221 of the negative electrode.

[0105] In some embodiments, the angle between the specified direction A and the thickness direction B of the negative electrode sheet is 0° to 30°.

[0106] In these embodiments, the combustion of gas by injecting it at a further specified angle toward the negative electrode 222 is more conducive to stabilizing the flame, allowing the flame to better burn the negative electrode 222, and also more conducive to the airflow quickly blowing away the ablation products, which helps to better reduce the burr defect rate of the edge 2221 of the negative electrode.

[0107] See Figure 7 In some embodiments, during the combustion process, combustion gas is injected toward the negative electrode 222 at a specified distance L from the negative electrode 222, and the specified distance L is 3cm to 15cm.

[0108] As an example, the specified distance L is, for example, but not limited to, any one of the following point values: 3cm, 4cm, 5cm, 6cm, 7cm, 8cm, 9cm, 10cm, 11cm, 12cm, 13cm, 14cm, or 15cm, or a range between any two.

[0109] See Figure 7 The specified distance L refers to the vertical distance from the combustion port of the gas to the specified surface 2222 of the negative electrode, that is, the distance from the combustion port of the gas to the specified surface 2222 of the negative electrode along the thickness direction B of the negative electrode.

[0110] In these embodiments, the combustion of gas by injecting gas toward the negative electrode 222 at a suitable specified distance L is beneficial to controlling the temperature of the flame acting on the negative electrode 222, so that the flame can better combust the negative electrode 222, which is beneficial to better reduce the burr defect rate of the edge 2221 of the negative electrode.

[0111] In some embodiments, the specified distance L is 5cm to 15cm.

[0112] In these embodiments, injecting combustion gas towards the negative electrode 222 at a further specified distance L is beneficial for more appropriate control of the temperature of the flame acting on the negative electrode 222, so that the flame can better combust the negative electrode 222, which is beneficial for better reducing the burr defect rate of the edge 2221 of the negative electrode.

[0113] SeeFigure 7 and Figure 8 In some embodiments, during the combustion process, the negative electrode 222 passes through the flame at a specified speed, which is 50 m / min to 150 m / min.

[0114] As an example, the specified speed is, for example, but not limited to, a point value of any one of 50 m / min, 60 m / min, 70 m / min, 80 m / min, 90 m / min, 100 m / min, 110 m / min, 120 m / min, 130 m / min, 140 m / min or 150 m / min, or a range of any two.

[0115] In an embodiment of this application, optionally, the position of the gas delivery and ignition device D for injecting igniting gas is kept fixed, and the negative electrode 222 is transported relative to the gas delivery and ignition device D at a specified speed by means of a belt, roller or the like, so that the negative electrode 222 passes through the flame at a specified speed.

[0116] See Figure 7 and Figure 8 As an example, the designated surface 2222 of the negative electrode is placed flat on the conveying surface for conveying, that is, the passing direction C of the negative electrode is basically perpendicular to the thickness direction B of the negative electrode.

[0117] In these embodiments, passing the negative electrode 222 through the flame at a suitable specified speed helps to control the surface of the negative electrode 222 to reach a suitable temperature, so that the flame can better burn the negative electrode 222, which helps to better reduce the burr defect rate of the edge 2221 of the negative electrode.

[0118] In some embodiments, the specified speed is 50 m / min to 80 m / min.

[0119] In these embodiments, passing the negative electrode 222 through the flame at a further specified speed helps to control the surface of the negative electrode 222 to reach a more suitable temperature, so that the flame can better burn the negative electrode 222, which helps to better reduce the burr defect rate of the edge 2221 of the negative electrode.

[0120] In some embodiments, the air-fuel ratio during combustion is (5-14):1.

[0121] As an example, the air-fuel ratio may be, but is not limited to, any one of the following point values ​​or a range between any two: 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1 or 14:1.

[0122] The air-fuel ratio refers to the mass ratio of air to fuel gas. It can be controlled by designing flow rates that match the fuel gas and air. For example, fuel gas and air are mixed at a specific flow rate according to the required air-fuel ratio, and then the mixture is introduced for combustion. Alternatively, the air-fuel ratio can be calculated based on the flow rates of fuel gas and air fed back from the flow meter.

[0123] In these embodiments, a suitable air-fuel ratio is met during the combustion process, which is conducive to the complete combustion of the gas and the stability of the flame temperature. This allows for better combustion processing of the negative electrode sheet 222, and helps to reduce the burr defect rate of the edge 2221 of the negative electrode sheet.

[0124] In some embodiments, the air-fuel ratio is (5-8):1.

[0125] In these embodiments, a further air-fuel ratio is achieved during the combustion process, which is beneficial for the complete combustion of the gas while maintaining a more stable flame temperature. This allows for better combustion of the negative electrode 222 and also helps to remove burr erosion products, thus reducing the burr defect rate of the negative electrode edge 2221.

[0126] In some embodiments, the temperature of the flame is 900°C to 1300°C.

[0127] As an example, the temperature of the flame is, for example, but not limited to, a point value of 900°C, 1000°C, 1100°C, 1200°C, or 1300°C, or a range of any two.

[0128] The temperature of the flame can be controlled by adjusting the type of fuel, air-fuel ratio, etc.

[0129] The temperature of a flame can refer to, for example, the temperature of the outer flame; for instance, the temperature of the outer flame portion of the flame can be measured to determine this.

[0130] In these embodiments, the flame reaches a specific temperature, which is beneficial for effectively ablating away the burrs at the edges of the negative electrode current collector and the negative electrode active material layer.

[0131] In some embodiments, the designated portion includes a designated surface 2222 of the negative electrode sheet, and the designated surface 2222 of the negative electrode sheet is the surface of the negative electrode sheet 222 distributed in the thickness direction.

[0132] The designated area includes the designated surface 2222 of the negative electrode sheet. That is, the combustion process not only processes the edge 2221 of the negative electrode sheet, but also processes the area outside the edge of the designated surface 2222 of the negative electrode sheet. In other words, the entire designated surface 2222 of the negative electrode sheet is processed through the combustion process.

[0133] As an example, during the combustion process, the negative electrode 222 passes through the flame along the second direction mentioned above, and the flame is able to cover at least the entire range of the designated surface 2222 of the negative electrode 222 in the first direction mentioned above (i.e., it is able to cover from one edge in the first direction to the opposite edge), so that after the entire negative electrode 222 passes through the flame along the second direction mentioned above, the designated surface 2222 of the entire negative electrode 222 is subjected to combustion processing.

[0134] In these embodiments, the designated area includes the surface of the negative electrode sheet 222 distributed in the thickness direction, so that the combustion treatment can also achieve surface modification of the entire surface of the negative electrode sheet.

[0135] In some embodiments, the fuel gas includes one or more of methane, propane, butane, pentane, pentene, or acetylene.

[0136] As an example, the fuel gas can be one of methane, propane, acetylene, butane, pentane, or pentene.

[0137] As another example, the gas may include a variety of combustible gases, one or more of which are selected from methane, propane, butane, pentane, pentene, or acetylene, and may also include other types of combustible gases, such as liquefied petroleum gas, coal gas, or natural gas.

[0138] In these embodiments, the gas includes a specific type of gas source, which facilitates the control of the flame to reach a suitable temperature, which is beneficial for better ablation of the burrs at the edges of the negative electrode current collector and the negative electrode active material layer; at the same time, the flame generated by the combustion of the gas contains a large amount of strong oxidizing gas, which reacts with the surface of the negative electrode 222 at high temperature, bringing in charged polar functional groups, which is beneficial for improving the surface energy of the negative electrode 222.

[0139] Secondly, embodiments of this application provide a negative electrode 222, which is obtained by processing according to the negative electrode processing method of the above embodiments.

[0140] Thirdly, embodiments of this application provide a battery 100, including a negative electrode 222 as described in the above embodiments.

[0141] Fourthly, embodiments of this application provide an electrical device, including the battery 100 as described in the above embodiments.

[0142] The following specific embodiments are provided to better illustrate this application.

[0143] I. Processing the negative electrode sheet

[0144] (1) Preparation of negative electrode sheet

[0145] The active material artificial graphite, conductive agent carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) were dissolved in deionized water at a weight ratio of 96.2:0.8:0.8:1.2 and mixed evenly to prepare a negative electrode slurry. The negative electrode slurry was uniformly coated on the negative electrode current collector copper foil, and then dried, cold-pressed, and slit to obtain the negative electrode sheet.

[0146] (2) Surface treatment of negative electrode sheet

[0147] The negative electrode sheet is placed in a winding device, the gas is ignited, and the negative electrode sheet is passed through the flame by the winding device, so that the entire negative electrode sheet (including the edge part and non-edge part) is treated by the flame.

[0148] Among them, the placement direction of the negative electrode, the passing direction of the negative electrode, and the configuration, quantity, and position of the gas delivery and ignition devices, etc. Figure 7 and Figure 8 As shown in Table 1, the process parameters and conditions for each embodiment, such as the type of gas, the angle between the specified direction and the thickness direction of the negative electrode sheet, the specified distance, and the specified speed, are as follows.

[0149] Table 1. Process Parameter Conditions

[0150]

[0151]

[0152] In addition, this application also provides Comparative Example 1 and Comparative Example 2, wherein Comparative Example 1 does not perform combustion treatment on the negative electrode sheet, and the difference between Comparative Example 2 and Example 1 is that infrared heating is used instead of gas flame combustion.

[0153] II. Testing Methods

[0154] (1) Take photos of the edge of the negative electrode sheet for observation.

[0155] (2) Detect the burr defect rate at the edge of the negative electrode sheet.

[0156] Take a 100mm die-cut strip from the negative electrode sheet, clamp it with a fixture, and make sure the end face of the die-cut strip is facing upwards.

[0157] The edge face condition is observed using a CCD camera. Among them, Class B burrs: along the thickness direction of the negative electrode sheet, the vertical distance from the highest point of a local protrusion on one of the aforementioned specified surfaces of the foil to another of the aforementioned specified surfaces of the foil is measured (i.e., this dimension includes the protrusion height and the foil thickness along the thickness direction of the negative electrode sheet).

[0158] Type B burr warning mechanism: If the size of a Type B burr is ≤ 45% of the electrode thickness, then the Type B burr size is within specifications and production can proceed normally; if the size of a Type B burr is > 45% of the electrode thickness, then it is NG (Not Acceptable). In this application, the burr defect rate is the percentage of items with an NG result.

[0159] (3) Test the surface energy of the specified surface of the negative electrode sheet.

[0160] In the direction perpendicular to the designated surface of the negative electrode sheet provided in Example 1 and Comparative Example 1, a dyne pen was used to draw a line on the designated surface of the negative electrode sheet with a pressure of 10N, and the trace left by the dyne pen on the designated surface of the negative electrode sheet was observed.

[0161] III. Test Results and Result Analysis

[0162] (1) The results of photographing and observing the edge of the negative electrode sheet are illustrated with some examples and comparative examples, such as... Figure 9 As shown.

[0163] according to Figure 9 As can be seen, the negative electrode sheet provided in this application embodiment has improved the edge burr problem to varying degrees compared with Comparative Example 1.

[0164] In addition, according to observations, when the negative electrode sheet provided in Example 6 passes through the flame at a speed of 30 m / min, the negative electrode tabs are sometimes burned out.

[0165] (2) The test results of the burr defect rate of the negative electrode sheet are shown in Table 2.

[0166] Table 2. Burr Defect Rate

[0167]

[0168]

[0169] Based on Tables 1 and 2, a brief analysis is as follows:

[0170] In Examples 1 to 21, the negative electrode sheet underwent combustion treatment; in Comparative Example 1, the negative electrode sheet was not subjected to combustion treatment; and in Comparative Example 2, infrared heating was used for treatment. Compared with Comparative Examples 1 to 21, the burr defect rate was reduced to varying degrees in Examples 1 to 21. However, in Comparative Example 2, which used infrared heating, the burrs were not blown away, leaving them in place. Therefore, compared with Comparative Example 1, the burr defect rate was not effectively improved after heating.

[0171] In Examples 1 to 7, the specified speeds were different. Among them, when the specified speed was between 50 m / min and 150 m / min, the burr defect rate was significantly reduced compared with Comparative Example 1; when the specified speed was further between 50 m / min and 80 m / min, the burr defect rate was reduced even more significantly compared with Comparative Example 1.

[0172] In Examples 1 and 8-9, the angle between the specified direction and the thickness direction of the negative electrode sheet is different. Specifically, when the angle between the specified direction and the thickness direction of the negative electrode sheet is between 0° and 60°, the burr defect rate is significantly reduced compared to Comparative Example 1; when the angle between the specified direction and the thickness direction of the negative electrode sheet is between 0° and 30°, the burr defect rate is reduced even more significantly compared to Comparative Example 1.

[0173] In Examples 1 and 10-13, the specified distances are different. When the specified distance is between 3cm and 15cm, the burr defect rate is significantly reduced compared to Comparative Example 1; when the specified distance is between 5cm and 15cm, the burr defect rate is reduced even more significantly compared to Comparative Example 1.

[0174] In Examples 1 and 14-18, the air-fuel ratios were different. When the air-fuel ratio was (5-14):1, the burr defect rate was significantly reduced compared to Comparative Example 1; when the specified distance was (5-8):1, the burr defect rate was reduced even more significantly compared to Comparative Example 1.

[0175] In Examples 1 and 19-21, the types of gas used were different. Compared with Comparative Example 1, the burr defect rate in each example was significantly reduced.

[0176] (3) The test results of the surface energy of the specified surface of the negative electrode sheet are as follows: Figure 10 As shown.

[0177] according to Figure 10 It is evident that the dyne pen can leave a mark on the designated surface of the negative electrode sheet provided in the embodiment, while leaving virtually no mark on the designated surface of the negative electrode sheet provided in Comparative Example 1, indicating that the designated surface of the negative electrode sheet provided in the embodiment of this application has a higher surface energy.

[0178] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for processing a negative electrode sheet, characterized in that, include: A designated portion of the negative electrode sheet is subjected to a combustion treatment, wherein the designated portion includes at least the edge of the negative electrode sheet, and the combustion treatment includes burning combustion gas and treating the designated portion with the generated flame to ablate burrs. The gaseous fuel includes one or more of methane, propane, butane, pentane, pentene, or acetylene; In the combustion process, the gas is injected toward the negative electrode at a specified distance from the negative electrode sheet for combustion, and the specified distance is 3cm to 15cm.

2. The method for processing the negative electrode sheet according to claim 1, characterized in that, In the combustion process, the gas is injected toward the negative electrode sheet in a specified direction for combustion, and the angle between the specified direction and the thickness direction of the negative electrode sheet is 0° to 60°.

3. The method for processing the negative electrode sheet according to claim 2, characterized in that, The angle between the specified direction and the thickness direction of the negative electrode sheet is 0°~30°.

4. The method for processing the negative electrode sheet according to claim 1, characterized in that, The specified distance is 5cm to 15cm.

5. A method for processing the negative electrode sheet according to any one of claims 1 to 4, characterized in that, In the combustion process, the negative electrode sheet passes through the flame at a specified speed, which is 50 m / min to 150 m / min.

6. The method for processing the negative electrode sheet according to claim 5, characterized in that, The specified speed is 50 m / min to 80 m / min.

7. The method for processing the negative electrode sheet according to any one of claims 1 to 4, characterized in that, In the combustion process, the air-fuel ratio is (5~14):

1.

8. The method for processing the negative electrode sheet according to claim 7, characterized in that, The air-fuel ratio is (5~8):

1.

9. The method for processing the negative electrode sheet according to any one of claims 1 to 4, characterized in that, The temperature of the flame is 900℃~1300℃.

10. The method for processing the negative electrode sheet according to any one of claims 1 to 4, characterized in that, The designated area includes a designated surface of the negative electrode sheet, which is the surface of the negative electrode sheet distributed in the thickness direction.

11. A negative electrode sheet, characterized in that, It is obtained by processing the negative electrode sheet according to any one of claims 1 to 10.

12. A battery, characterized in that, Includes the negative electrode sheet as described in claim 11.

13. An electrical appliance, characterized in that, Includes the battery as described in claim 12.

Images