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

Abstract

A negative electrode sheet and a processing method therefor, and a battery and an electric device. The processing method for a negative electrode sheet comprises: performing a combustion treatment on a specified part of a negative electrode sheet, wherein the specified part at least comprises an edge of the negative electrode sheet, and the combustion treatment comprises combusting a fuel gas and heating the specified part by means of generated flames. In the processing method for a negative electrode sheet, a combustion treatment is performed on an edge of the negative electrode sheet, so as to ablate burrs by means of flames, thereby ameliorating the problem of there being burrs on the edge of the negative electrode sheet.

Description

Negative electrode sheet and processing method thereof, battery and electrical equipment

[0001] Cross-references

[0002] This application claims priority to Chinese patent application No. 202310720761.3, filed on June 16, 2023, entitled “Negative electrode sheet and its processing method, battery and electrical equipment”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a negative electrode plate and a processing method thereof, a battery, and an electrical device. Background Art

[0004] When the negative electrode is cut, burrs are likely to form on the edge, and the presence of burrs can easily cause poor self-discharge of the battery.

[0005] Summary of the Invention

[0006] In view of the above problems, the present application provides a negative electrode plate and a processing method thereof, a battery and an electrical device, which are conducive to improving the burr problem at the edge of the negative electrode plate.

[0007] The embodiment of the present application is implemented as follows:

[0008] In a first aspect, an embodiment of the present application provides a method for processing a negative electrode plate, comprising: performing a combustion treatment on a designated portion of the negative electrode plate, wherein the designated portion includes at least the edge of the negative electrode plate, and the combustion treatment comprises burning gas and processing the designated portion through the generated flame.

[0009] The negative electrode plate processing method provided in the embodiments of the present application performs a combustion treatment on the edge of the negative electrode plate, ablating burrs through the flame, which is beneficial for improving the burr problem at the edge of the negative electrode plate. In addition, the combustion treatment is performed by burning gas, and the airflow generated by the gas can blow away the burr ablation products, which is beneficial for the flame to more fully ablate the burrs on the edge of the negative electrode plate, while also helping to maintain a good cleanliness of the surface of the negative electrode plate.

[0010] In some embodiments, during 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°.

[0011] In these embodiments, injecting gas toward the negative electrode plate for combustion at a suitable specified angle is beneficial to stabilizing the flame so that the flame can better burn the negative electrode plate. At the same time, it is beneficial for the airflow to quickly blow away the ablation products, which is beneficial to better reduce the burr defect rate at the edge of the negative electrode plate.

[0012] In some embodiments, the angle between the designated direction and the thickness direction of the negative electrode sheet is 0° to 30°.

[0013] In these embodiments, injecting gas toward the negative electrode plate for combustion at a further specified angle is more conducive to stabilizing the flame, so that the flame can better burn the negative electrode plate, and is more conducive to the airflow to quickly blow away the ablation products, which is conducive to better reducing the burr defect rate on the edge of the negative electrode plate.

[0014] In some embodiments, during the combustion process, fuel gas is injected toward the negative electrode sheet at a specified distance from the negative electrode sheet for combustion, and the specified distance is 3 cm to 15 cm.

[0015] In these embodiments, spraying gas toward the negative electrode plate for combustion at a suitable specified distance is beneficial to regulating the temperature of the flame acting on the negative electrode plate, so that the flame can better burn the negative electrode plate, which is beneficial to better reduce the burr defect rate on the edge of the negative electrode plate.

[0016] In some embodiments, the designated distance is 5 cm to 15 cm.

[0017] In these embodiments, spraying gas toward the negative electrode plate for combustion at a further specified distance is beneficial for more appropriately regulating the temperature of the flame acting on the negative electrode plate, so that the flame can better burn the negative electrode plate, which is beneficial for better reducing the burr defect rate on the edge of the negative electrode plate.

[0018] In some embodiments, during the combustion process, the negative electrode plate passes through the flame at a specified speed, which is 50 m / min to 150 m / min.

[0019] In these embodiments, passing the negative electrode plate through the flame at a suitable specified speed is beneficial to controlling the surface of the negative electrode plate to reach a suitable temperature, so that the flame can better burn the negative electrode plate, which is beneficial to better reduce the burr defect rate on the edge of the negative electrode plate.

[0020] In some embodiments, the specified speed is 50 m / min to 80 m / min.

[0021] In these embodiments, passing the negative electrode plate through the flame at a further specified speed is beneficial to controlling the surface of the negative electrode plate to reach a more suitable temperature, so that the flame can better burn the negative electrode plate, which is beneficial to better reduce the burr defect rate on the edge of the negative electrode plate.

[0022] In some embodiments, during the combustion process, the air-fuel ratio is (5-14):1.

[0023] In these embodiments, a suitable air-fuel ratio is satisfied during the combustion process, which is beneficial to the complete combustion of the fuel gas and the stability of the flame temperature, and can better perform the combustion process on the negative electrode sheet, which is beneficial to better reduce the burr defect rate on the edge of the negative electrode sheet.

[0024] In some embodiments, the air-fuel ratio is (5-8):1.

[0025] In these embodiments, a further air-fuel ratio is met during the combustion process, which is beneficial to the full combustion of the gas while better maintaining the stability of the flame temperature, and can better perform combustion treatment on the negative electrode sheet. At the same time, the burr ablation products can be better blown away, which is beneficial to better reduce the burr defect rate at the edge of the negative electrode sheet.

[0026] In some embodiments, the temperature of the flame is 900°C to 1300°C.

[0027] In these embodiments, the flame meets a specific temperature, which is conducive to better ablating burrs at the edges of the negative electrode current collector and the negative electrode active material layer.

[0028] In some embodiments, the designated portion includes a designated surface of the negative electrode sheet, and the designated surface of the negative electrode sheet is a surface distributed in the thickness direction of the negative electrode sheet.

[0029] In these embodiments, the designated portion includes the surface of the negative electrode sheet distributed in the thickness direction, so that the combustion treatment can also achieve surface modification on the entire surface of the negative electrode sheet.

[0030] In some embodiments, the fuel gas includes one or more of methane, propane, butane, pentane, pentene, or acetylene.

[0031] In these embodiments, the fuel gas includes a specific type of gas source, which facilitates the control of the flame to reach a suitable temperature, and is beneficial to better ablate 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 fuel gas contains a large amount of strongly oxidizing gas, which reacts with the surface of the negative electrode plate at high temperature to introduce charged polar functional groups, which is beneficial to increase the surface energy of the negative electrode plate.

[0032] In a second aspect, an embodiment of the present application provides a negative electrode sheet, which is obtained by processing according to the negative electrode sheet processing method of the above embodiment.

[0033] In a third aspect, an embodiment of the present application provides a battery, comprising a negative electrode plate as described in the above embodiment.

[0034] In a fourth aspect, an embodiment of the present application provides an electrical device comprising a battery as described in the above embodiment.

[0035] The above description is only an overview of the technical solutions of the embodiments of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0037] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0038] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0039] FIG3 is an exploded view of a battery cell provided in some embodiments of the present application;

[0040] FIG4 is a schematic structural diagram of an electrode assembly provided in some embodiments of the present application;

[0041] FIG5 is a process flow chart of a method for processing a negative electrode sheet according to some embodiments of the present application;

[0042] FIG6 is a schematic structural diagram of a negative electrode sheet provided in some embodiments of the present application;

[0043] FIG7 is a schematic diagram of a side view of a method for processing a negative electrode sheet provided in some embodiments of the present application;

[0044] FIG8 is a schematic diagram of a top view of a method for processing a negative electrode sheet provided in some embodiments of the present application;

[0045] FIG9 is a photograph of the edge of the negative electrode provided in some embodiments and comparative examples of the present application;

[0046] FIG10 is a photograph of the test results of the surface energy of the negative electrode sheets provided in some embodiments and comparative examples of the present application.

[0047] icon:

[0048] 1000-vehicles;

[0049] 100-battery; 200-controller; 300-motor;

[0050] 10-box; 11-first part; 12-second part; 13-accommodation space;

[0051] 20 - battery cell; 21 - housing; 22 - electrode assembly; 23 - electrode terminal; 24 - pressure relief structure;

[0052] 211-housing; 212-cover; 213-sealed space;

[0053] 221-positive electrode sheet; 222-negative electrode sheet; 223-separator;

[0054] 2221 - edge of the negative electrode sheet; 2222 - designated surface of the negative electrode sheet;

[0055] A-specified direction; B-thickness direction of the negative electrode sheet; C-passing direction of the negative electrode sheet; D-gas delivery and ignition device; L-specified distance. DETAILED DESCRIPTION

[0056] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0057] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0059] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0060] In the description of the embodiments of this application, the technical term "and / or," such as "Feature 1 and / or Feature 2," refers to "Feature 1" alone, "Feature 2" alone, or "Feature 1" plus "Feature 2." Furthermore, the character " / " in this document generally indicates an "or" relationship between the preceding and following related objects.

[0061] In the description of the embodiments of the present application, unless otherwise specified, the “multiple” in “one or more” means two or more than two.

[0062] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0063] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the heights, lengths, widths, and other dimensions of the various components in the embodiments of this application, as well as the overall heights, lengths, widths, and other dimensions of the integrated device shown in the drawings are merely illustrative and do not constitute any limitation on this application.

[0064]

[0065] Market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0066] With the continued development of the new energy industry, the market has put forward more diverse demands on battery electrodes. For electrode research, some current technical solutions mainly focus on material modification, internal microstructure adjustment, and surface treatment.

[0067] In the production process of pole pieces, since an active material layer is usually formed on the surface of the current collector before cutting, the negative pole piece is prone to burrs at the edge when cutting. The presence of burrs can easily cause poor self-discharge of the battery, which may lead to safety accidents.

[0068] In some current technical solutions, in order to reduce the impact of edge burrs, the isolation membrane is usually improved, such as thickening the isolation membrane 223 at the position corresponding to the edge of the electrode or increasing the number of layers of the isolation membrane. However, this operation method will increase the material cost of the isolation membrane and the time cost and material cost of producing and assembling the battery, and it cannot fundamentally solve the hidden danger of burrs.

[0069] Based on this, the present invention proposes a negative electrode plate and a treatment method thereof. This method, which burns the edge of the negative electrode plate and ablates the burrs through the flame, is beneficial for improving the burr problem at the edge of the negative electrode plate. This treatment method can fundamentally improve the hidden dangers of burrs, while also being simple to operate and low-cost.

[0070] The battery cell using the negative electrode plate disclosed in the embodiment of the present application can be used, but is not limited to, in electrical devices such as vehicles, ships, or aircraft. The embodiment of the present application provides an electrical device using a battery as a power source. The electrical device can be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, and the like. Among them, the electric toy can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like. The spacecraft can include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0071] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device in the embodiments of the present application.

[0072] Refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an 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 power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

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

[0074] In this application, a battery 100 refers to a single physical module that includes one or more battery cells 20 to provide a certain voltage and capacity. It can be in the form of a battery pack, a battery module, etc. The battery 100 can include a housing 10 for enclosing the one or more battery cells 20. The housing 10 can prevent liquids or other foreign matter from affecting the charging or discharging of the battery cells 20.

[0075] Referring to FIG2 , FIG2 is an exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 includes a housing 10 and a plurality of battery cells 20, wherein the plurality of battery cells 20 are housed in the housing 10. The housing 10 is used to house the battery cells 20, and the housing 10 can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, wherein the first portion 11 and the second portion 12 overlap each other, and the first portion 11 and the second portion 12 jointly define a housing space 13 for accommodating the battery cells 20. The second portion 12 can be a hollow structure with one end open, and the first portion 11 is a plate-like structure, and the first portion 11 overlaps the open side of the second portion 12 to form the housing 10 with the housing space 13; the first portion 11 and the second portion 12 can also be hollow structures with one side open, and the open side of the first portion 11 overlaps the open side of the second portion 12 to form the housing 10 with the housing space 13. Of course, the first part 11 and the second part 12 can be in various shapes, such as a cylinder, a cuboid, etc.

[0076] In the battery 100, multiple battery cells 20 can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections among the multiple battery cells 20. Multiple battery cells 20 can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure of the multiple battery cells 20 is housed within the housing 10. Alternatively, multiple battery cells 20 can be first connected in series, in parallel, or in a hybrid configuration to form a module, which is then connected in series, in parallel, or in a hybrid configuration to form a complete structure housed within the housing 10. The battery 100 may also include other structures. For example, multiple battery cells 20 can be electrically connected via a busbar to enable parallel, series, or hybrid connection of the multiple battery cells 20.

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

[0078] 3 , the battery cell 20 may include a housing 21 , an electrode assembly 22 , and an electrolyte, and both the electrode assembly 22 and the electrolyte are accommodated in the housing 21 .

[0079] The outer shell 21 may include a shell 211 and a cover 212. The shell 211 is a component used to cooperate 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 refers to a component that covers the opening of the shell 211 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the cover 212 can be adapted to the shape of the shell 211 to cooperate with the shell 211. Functional components such as electrode terminals 23 and pressure relief structures 24 can also be provided on the cover 212. A sealing ring can be configured between the opening of the shell 211 and the cover 212 to achieve sealing between the shell 211 and the cover 212.

[0080] The shell 211 and the cover 212 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shapes of the shell 211 and the cover 212 can be determined according to the specific shape and size of the electrode assembly 22. The material of the shell 211 and the cover 212 can be various, such as but not limited to metals such as copper, iron, aluminum, stainless steel, and aluminum alloy. The material of the sealing ring can be various, such as but not limited to PP (polypropylene), PC (polycarbonate), PET (polyethylene terephthalate) and other materials that are resistant to electrolyte corrosion, high toughness and fatigue resistance. A coating can be formed on the outer surface of the shell 211, and the material of the coating can be various, such as but not limited to corrosion-resistant materials such as Ni and Cr.

[0081] The battery cell 20 may also be in the form of a soft pack, such as a pouch-type soft pack. The soft pack may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[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 relies on the movement of metal ions between the positive electrode sheet 221 and the negative electrode sheet 222 to work. During the charge and discharge process, active ions are embedded and released back and forth between the positive electrode sheet 221 and the negative electrode sheet 222; the separator 223 is arranged between the positive electrode sheet 221 and the negative electrode sheet 222, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through. The electrode assembly 22 can be a wound structure or a laminated structure, and the embodiments of the present application are not limited to this.

[0083] The positive electrode sheet 221 includes a positive electrode current collector and a positive electrode active material layer. 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 may be disposed between the positive electrode active material layer and the positive electrode current collector.

[0084] The positive electrode current collector may be a metal foil or a composite current collector. For example, the positive electrode current collector may be made of aluminum. The composite current collector may include a polymer material base layer and a metal layer formed on at least one side of the polymer material base layer. The composite current collector may 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 made 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 may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional 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 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 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds, etc. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0086] In some embodiments, the positive electrode active material layer may further optionally include a binder. As an example, the binder may 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 electrode active material layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

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

[0089] Among them, 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 may include a polymer material base layer 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 polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0090] The negative electrode active material in the negative electrode active material layer may be a negative electrode active material such as carbon and silicon. As an example, the negative electrode active 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. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present 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.

[0091] In some embodiments, the negative electrode active material layer may further 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).

[0092] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0093] In some embodiments, the negative electrode active material layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0094] The isolation membrane 223 is located between the positive electrode plate 221 and the negative electrode plate 222 and serves as an isolation. The embodiment of the present application has no particular restriction on the type of isolation membrane 223 and any well-known porous structure isolation membrane 223 with good chemical stability and mechanical stability can be selected.

[0095] In some embodiments, the material of the isolation membrane 223 can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The isolation membrane 223 can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane 223 is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0096] Next, the negative electrode sheet 222 and the processing method thereof proposed in the embodiment of the present application are described in detail.

[0097] Referring to Figure 5, in the first aspect, an embodiment of the present application provides a method for processing a negative electrode plate, comprising: performing combustion treatment on a designated portion of the negative electrode plate 222, wherein, referring to Figure 6, the designated portion includes at least the edge 2221 of the negative electrode plate, and the combustion treatment comprises burning gas and processing the designated portion through the generated flame.

[0098] The designated portion includes at least the edge 2221 of the negative electrode sheet, which means that the designated portion is not limited to only the edge 2221 of the negative electrode sheet, and may also include a non-edge portion of the negative electrode sheet 222 .

[0099] 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 located on a side surface of the negative electrode sheet 222. Referring to Figures 7 and 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 substantially perpendicular to the thickness direction B of the negative electrode sheet; the side surface of the negative electrode sheet 222 refers to the surface substantially parallel to the thickness direction B of the negative electrode sheet.

[0100] As an example, the negative electrode sheet 222 is die-cut into strips, including first edges oppositely distributed along a first direction and second edges oppositely distributed along a second direction. The first edge is the die-cut edge of the die-cut strip. The first edge can 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 perpendicular to each other.

[0101] The fuel gas includes combustible gas, which is introduced into a designated location for combustion treatment through a gas delivery and ignition device D such as a spray gun or burner for combustion; during the process of delivering the fuel gas, an auxiliary fuel may optionally be delivered together with the fuel gas or separately from the fuel gas.

[0102] During the process of treating the designated portion by the generated flame, the flame heats the designated portion so that the designated portion is burned by the flame.

[0103] The negative electrode plate processing method provided in the embodiment of the present application performs a combustion treatment on the edge 2221 of the negative electrode plate, ablating the burrs through the flame, which is beneficial to improving the burr problem at the edge of the negative electrode plate 222. In addition, the combustion treatment is performed by burning gas. The airflow generated by the gas can blow away the burr ablation products, which is beneficial for the flame to more fully ablate the burrs on the edge 2221 of the negative electrode plate, and also helps to maintain a good cleanliness of the surface of the negative electrode plate 222.

[0104] 7 , in some embodiments, during the combustion process, fuel gas is injected toward the negative electrode sheet 222 in a specified direction A for combustion, and the angle between the specified direction A and the thickness direction B of the negative electrode sheet is 0° to 60°.

[0105] 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 point value of 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55° or 60°, or a range value between any two of them.

[0106] When the angle between the specified direction A and the thickness direction B of the negative electrode sheet is 0°, the specified direction A is basically perpendicular to the specified surface 2222 of the negative electrode sheet; when the angle between the specified direction A and the thickness direction B of the negative electrode sheet is 90°, the specified direction A is basically parallel to the specified surface 2222 of the negative electrode sheet.

[0107] 7 , the designated direction A refers to the direction in which the gas is ejected from the burner port, and the designated direction A is substantially consistent with the axial direction of the burner port.

[0108] In these embodiments, injecting fuel gas toward the negative electrode plate 222 at a suitable specified angle for combustion is beneficial to stabilizing the flame so that the flame can better burn the negative electrode plate 222, and is also beneficial for the airflow to quickly blow away the ablation products, which is beneficial to better reduce the burr defect rate at the edge 2221 of the negative electrode plate.

[0109] In some embodiments, the angle between the designated direction A and the thickness direction B of the negative electrode sheet is 0° to 30°.

[0110] In these embodiments, injecting gas toward the negative electrode plate 222 for combustion at a further specified angle is more conducive to stabilizing the flame, so that the flame can better burn the negative electrode plate 222, and is more conducive to the airflow to quickly blow away the ablation products, which is conducive to better reducing the burr defect rate of the edge 2221 of the negative electrode plate.

[0111] 7 , in some embodiments, during the combustion process, fuel gas is injected toward the negative electrode plate 222 at a specified distance L from the negative electrode plate 222 for combustion, and the specified distance L is 3 cm to 15 cm.

[0112] As an example, the specified distance L is, for example but not limited to, any one of 3cm, 4cm, 5cm, 6cm, 7cm, 8cm, 9cm, 10cm, 11cm, 12cm, 13cm, 14cm or 15cm, or a range of values ​​between any two of them.

[0113] 7 , the designated distance L refers to the vertical distance from the gas combustion port to the designated surface 2222 of the negative electrode plate, that is, the distance from the gas combustion port to the designated surface 2222 of the negative electrode plate along the thickness direction B of the negative electrode plate.

[0114] In these embodiments, the fuel gas is sprayed toward the negative electrode plate 222 at a suitable specified distance L for combustion, which is beneficial to regulating the temperature of the flame acting on the negative electrode plate 222, so that the flame can better burn the negative electrode plate 222, which is beneficial to better reduce the burr defect rate of the edge 2221 of the negative electrode plate.

[0115] In some embodiments, the designated distance L is 5 cm to 15 cm.

[0116] In these embodiments, spraying gas toward the negative electrode plate 222 for combustion at a further specified distance L is beneficial for more appropriately regulating the temperature of the flame acting on the negative electrode plate 222, so that the flame can better burn the negative electrode plate 222, which is beneficial for better reducing the burr defect rate of the edge 2221 of the negative electrode plate.

[0117] 7 and 8 , in some embodiments, during the combustion process, the negative electrode sheet 222 passes through the flame at a specified speed, which is 50 m / min to 150 m / min.

[0118] As an example, the specified speed is, but is not limited to, 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 values ​​between any two of them.

[0119] In an embodiment of the present application, optionally, the position of the gas conveying and ignition device D that sprays the ignition gas remains fixed, and the negative electrode plate 222 is conveyed at a specified speed relative to the gas conveying and ignition device D by means of a belt, roller, etc., so that the negative electrode plate 222 passes through the flame at a specified speed.

[0120] 7 and 8 , as an example, the designated surface 2222 of the negative electrode sheet is placed flat on the conveying surface for conveyance, that is, the passing direction C of the negative electrode sheet is substantially perpendicular to the thickness direction B of the negative electrode sheet.

[0121] In these embodiments, passing the negative electrode plate 222 through the flame at a suitable specified speed is beneficial to controlling the surface of the negative electrode plate 222 to reach a suitable temperature, so that the flame can better burn the negative electrode plate 222, which is beneficial to better reduce the burr defect rate of the edge 2221 of the negative electrode plate.

[0122] In some embodiments, the specified speed is 50 m / min to 80 m / min.

[0123] In these embodiments, passing the negative electrode plate 222 through the flame at a further specified speed is beneficial to controlling the surface of the negative electrode plate 222 to reach a more suitable temperature, so that the flame can better burn the negative electrode plate 222, which is beneficial to better reduce the burr defect rate of the edge 2221 of the negative electrode plate.

[0124] In some embodiments, during the combustion process, the air-fuel ratio is (5-14):1.

[0125] As an example, the air-fuel ratio is, for example but not limited to, any one of 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1 or 14:1, or a range between any two of them.

[0126] The air-fuel ratio refers to the mass ratio between air and gas. It can be controlled by matching the gas and air flow rates. For example, gas and air are mixed at a specific flow rate based on the required air-fuel ratio, and then the mixture is introduced for combustion. Alternatively, the air-fuel ratio can be calculated based on the gas and air flow rates reported by a flow meter.

[0127] In these embodiments, a suitable air-fuel ratio is satisfied during the combustion process, which is beneficial to the complete combustion of the gas and the stability of the flame temperature, and can better perform the combustion process on the negative electrode plate 222, which is beneficial to better reduce the burr defect rate of the edge 2221 of the negative electrode plate.

[0128] In some embodiments, the air-fuel ratio is (5-8):1.

[0129] In these embodiments, a further air-fuel ratio is satisfied during the combustion process, which is beneficial to the full combustion of the gas while better maintaining the stability of the flame temperature, and can better perform the combustion process on the negative electrode plate 222. At the same time, the burr ablation products can be better blown away, which is beneficial to better reduce the burr defect rate of the edge 2221 of the negative electrode plate.

[0130] In some embodiments, the temperature of the flame is 900°C to 1300°C.

[0131] As an example, the temperature of the flame is, for example but not limited to, any one of 900° C., 1000° C., 1100° C., 1200° C., or 1300° C., or a range of values ​​therebetween.

[0132] The temperature of the flame can be controlled by adjusting the type of gas, air-fuel ratio, etc.

[0133] The temperature of the flame refers to, for example, the outer flame temperature; for example, the outer flame portion of the flame can be measured to determine the temperature.

[0134] In these embodiments, the flame meets a specific temperature, which is conducive to better ablating burrs at the edges of the negative electrode current collector and the negative electrode active material layer.

[0135] 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 a surface distributed in the thickness direction of the negative electrode sheet 222 .

[0136] The designated portion includes the designated surface 2222 of the negative electrode plate, that is, the combustion treatment not only processes the edge 2221 of the negative electrode plate, but also processes the portion outside the edge of the designated surface 2222 of the negative electrode plate, that is, the designated surface 2222 of the entire negative electrode plate is processed through the combustion treatment.

[0137] As an example, during the combustion treatment, the negative electrode plate 222 passes through the flame along the second direction mentioned above, and the flame can at least cover the entire range of the designated surface 2222 of the negative electrode plate in the first direction mentioned above (that is, it can cover from one side edge in the first direction to the opposite other side edge), so that after the entire negative electrode plate 222 passes through the flame along the second direction mentioned above, the entire designated surface 2222 of the negative electrode plate is burned.

[0138] In these embodiments, the designated portion includes the surface of the negative electrode sheet 222 distributed in the thickness direction, so that the combustion treatment can also achieve surface modification on the entire surface of the negative electrode sheet.

[0139] In some embodiments, the fuel gas includes one or more of methane, propane, butane, pentane, pentene, or acetylene.

[0140] As an example, the fuel gas may be methane, propane, or one of acetylene, butane, pentane, and pentene.

[0141] As another example, the fuel gas includes multiple 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, for example, the fuel gas is liquefied gas, coal gas or natural gas.

[0142] In these embodiments, the fuel gas includes a specific type of gas source, which facilitates the control of the flame to reach a suitable temperature, and is beneficial to better ablate 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 fuel gas contains a large amount of strongly oxidizing gas, which reacts with the surface of the negative electrode plate 222 at high temperature to introduce charged polar functional groups, which is beneficial to increase the surface energy of the negative electrode plate 222.

[0143] In a second aspect, an embodiment of the present application provides a negative electrode sheet 222 , which is obtained by processing according to the negative electrode sheet processing method of the above embodiment.

[0144] In a third aspect, an embodiment of the present application provides a battery 100 comprising the negative electrode plate 222 according to the above embodiment.

[0145] In a fourth aspect, an embodiment of the present application provides an electrical device, comprising a battery 100 as described in the above embodiment.

[0146] Some specific embodiments are listed below to better illustrate the present application.

[0147] 1. Processing of negative electrode

[0148] (1) Preparation of negative electrode sheet

[0149] The active material artificial graphite, the conductive agent carbon black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) are dissolved in the solvent deionized water in a weight ratio of 96.2:0.8:0.8:1.2, and mixed evenly to prepare the negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector copper foil, and the negative electrode sheet is obtained after drying, cold pressing, and slitting.

[0150] (2) Surface treatment of negative electrode

[0151] The negative electrode sheet is placed in a winding device, the gas is ignited, and the negative electrode sheet is passed through the flame through the winding device, so that the entire negative electrode sheet (including the edge portion and the non-edge portion) is flame-treated.

[0152] Among them, the placement direction of the negative electrode sheet, the passing direction of the negative electrode sheet, the number and position of the gas delivery and ignition devices, etc. are shown in Figures 7 and 8; the process parameter conditions 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 in each embodiment are shown in Table 1.

[0153] Table 1. Process parameter conditions

[0154]

[0155] In addition, the present application also provides comparative examples 1 and 2, wherein, in comparative example 1, the negative electrode plate is not subjected to combustion treatment, and the difference between comparative example 2 and embodiment 1 is that infrared heating is used instead of gas flame combustion.

[0156] 2. Test Method

[0157] (1) Take photos of the edge of the negative electrode

[0158] (2) Detect the burr defect rate on the edge of the negative electrode

[0159] Take the 100mm die-cut strip of the negative electrode, clamp it with a clamp, and place the end of the die-cut strip facing upwards.

[0160] Use a CCD camera to observe the edge end surface condition. For Class B burrs, measure the vertical distance from the highest point of a local raised portion on one designated surface of the foil to the other designated surface of the foil along the thickness direction of the negative electrode sheet (i.e., this dimension includes the raised height and the foil thickness along the thickness direction of the negative electrode sheet).

[0161] Class B burr warning mechanism: If the size of a Class B burr is ≤ 45% of the electrode thickness, the Class B burr size is within specifications and production can proceed normally. If the size of a Class B burr is greater than 45% of the electrode thickness, the product is considered NG. In this application, the burr defect rate refers to the percentage of test results that are NG.

[0162] (3) Test the surface energy of the above-specified surface of the negative electrode

[0163] In the direction perpendicular to the above-mentioned 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 above-mentioned designated surface of the negative electrode sheet with a pressure of 10N, and the mark left by the dyne pen on the above-mentioned designated surface of the negative electrode sheet was observed.

[0164] 3. Test results and analysis

[0165] (1) The detection results of photographing and observing the edge of the negative electrode piece are illustrated with some embodiments and comparative examples, as shown in FIG9 .

[0166] As can be seen from FIG9 , the burr problem on the edge of the negative electrode sheet provided in the embodiment of the present application is improved to varying degrees compared with that in comparative example 1.

[0167] In addition, according to observation, the negative electrode tabs provided in Example 6 were burned in some cases when the negative electrode tabs passed through the flame at a speed of 30 m / min.

[0168] (2) The test results of the burr defect rate on the edge of the negative electrode are shown in Table 2.

[0169] Table 2. Burr defect rate

[0170]

[0171] Combining Table 1 and Table 2, a brief analysis is as follows:

[0172] In Examples 1 to 21, the negative electrode plates were burned; in Comparative Example 1, they were not burned; and in Comparative Example 2, infrared heating was used. Compared with Comparative Examples 1 and 2, Examples 1 to 21 showed varying degrees of reduction in the burr defect rate. However, in Comparative Example 2, infrared heating was used, but since the ablated burrs were not blown away, the burrs remained in place. Therefore, compared with Comparative Example 1, the burr defect rate was not significantly improved after heating.

[0173] In Examples 1 to 7, the specified speeds varied. When the specified speed was between 50 m / min and 150 m / min, the burr defect rate was significantly reduced compared to Comparative Example 1. When the specified speed was further between 50 m / min and 80 m / min, the burr defect rate was even more significantly reduced compared to Comparative Example 1.

[0174] In Examples 1 and 8-9, the angles between the designated direction and the thickness direction of the negative electrode sheet were different. When the angle between the designated direction and the thickness direction of the negative electrode sheet was between 0° and 60°, the burr defect rate was significantly reduced compared to Comparative Example 1. When the angle between the designated direction and the thickness direction of the negative electrode sheet was between 0° and 30°, the burr defect rate was even more significantly reduced compared to Comparative Example 1.

[0175] The designated distances in Example 1 and Examples 10 to 13 were different. When the designated distance was 3 cm to 15 cm, the burr defect rate was significantly reduced compared to Comparative Example 1. When the designated distance was 5 cm to 15 cm, the burr defect rate was even more significantly reduced compared to Comparative Example 1.

[0176] The air-fuel ratios in Example 1 and Examples 14 to 18 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 designated distance was (5-8):1, the burr defect rate was even more significantly reduced compared to Comparative Example 1.

[0177] In Example 1 and Examples 19 to 21, the types of gases are different. Compared with Comparative Example 1, the burr defect rate of each example is significantly reduced.

[0178] (3) The test results of the surface energy test on the specified surface of the negative electrode are shown in FIG10 .

[0179] As can be seen from Figure 10, the dyne pen can leave a mark on the designated surface of the negative electrode plate provided in the embodiment, while basically no mark is left on the designated surface of the negative electrode plate provided in Comparative Example 1, indicating that the designated surface of the negative electrode plate provided in the embodiment of the present application has a higher surface energy.

[0180] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for processing a negative electrode sheet, wherein: include: A combustion treatment is performed on a designated portion of the negative electrode plate, wherein the designated portion at least includes an edge of the negative electrode plate, and the combustion treatment includes burning a fuel gas and treating the designated portion with the generated flame.

2. The method for processing a negative electrode sheet according to claim 1, wherein: During the combustion process, the fuel gas is sprayed toward the negative electrode sheet in a specified direction for combustion, and an angle between the specified direction and the thickness direction of the negative electrode sheet is 0° to 60°.

3. The method for processing a negative electrode sheet according to claim 2, wherein: The angle between the designated direction and the thickness direction of the negative electrode sheet is 0° to 30°.

4. The method for processing a negative electrode sheet according to any one of claims 1 to 3, wherein: In the combustion process, the fuel gas is sprayed toward the negative electrode sheet at a specified distance from the negative electrode sheet for combustion, and the specified distance is 3 cm to 15 cm.

5. The method for processing a negative electrode sheet according to claim 4, wherein: The designated distance is 5 cm to 15 cm.

6. The method for processing a negative electrode sheet according to any one of claims 1 to 5, wherein: During the combustion process, the negative electrode plate passes through the flame at a specified speed, and the specified speed is 50 m / min to 150 m / min.

7. The method for processing a negative electrode sheet according to claim 6, wherein: The specified speed is 50 m / min to 80 m / min.

8. The method for processing a negative electrode sheet according to any one of claims 1 to 7, wherein: In the combustion process, the air-fuel ratio is (5-14):

1.

9. The method for processing a negative electrode sheet according to claim 8, wherein: The air-fuel ratio is (5-8):

1.

10. The method for processing a negative electrode sheet according to any one of claims 1 to 9, wherein: The temperature of the flame is 900°C to 1300°C.

11. The method for processing a negative electrode sheet according to any one of claims 1 to 10, wherein: The designated portion includes a designated surface of the negative electrode sheet, and the designated surface of the negative electrode sheet is a surface of the negative electrode sheet distributed in a thickness direction.

12. The method for processing a negative electrode sheet according to any one of claims 1 to 11, wherein: The fuel gas includes one or more of methane, propane, butane, pentane, pentene or acetylene.

13. A negative electrode sheet, wherein: The negative electrode sheet is obtained by processing according to the processing method of any one of claims 1 to 12.

14. A battery, wherein: Comprising the negative electrode sheet as described in claim 13.

15. An electrical device, wherein: Comprising the battery of claim 14.

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