Pole piece, pole piece preparation method, battery monomer, battery and power utilization device

Abstract

The invention provides a pole piece, a pole piece preparation method, a battery monomer, a battery and a power utilization device. The pole piece comprises a current collector and an active substance layer, the current collector comprises a first area and a second area which are arranged in the width direction of the current collector, the active substance layer is arranged in the first area, at least part of the second area is provided with a passivation layer, and at least part of sharp burrs on the surface of the second area are eliminated through the passivation layer. Therefore, the risks of short circuit and thermal runaway of the battery caused by piercing of the diaphragm by sharp burrs in the second area are reduced, and the reliability of the battery is improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a pole piece, a pole piece preparation method, a battery cell, a battery, and an electrical device. Background Art

[0002] Batteries, as devices that generate electrical energy, have been widely used in a variety of fields, including small power plants, electric vehicles, and energy storage. However, in the event of a short circuit, batteries can easily fail, even catch fire or explode, causing serious harm. Therefore, battery safety issues have greatly limited their application and widespread adoption.

[0003] Each electrode inside the battery needs to be separated by a diaphragm insulation spacer. Due to the low structural strength of the diaphragm, the diaphragm is easily damaged during the production and use of the battery, thereby affecting the self-discharge performance of the battery. In severe cases, it may cause the battery to short-circuit, thermal runaway, fire, explosion and other risks, resulting in insufficient battery reliability and urgent need for improvement. Summary of the Invention

[0004] In view of the above problems, the present application provides a pole piece, a pole piece preparation method, a battery cell, a battery and an electrical device, which can improve the problems of battery short circuit and thermal runaway caused by damaged diaphragm and improve the reliability of the battery.

[0005] In a first aspect, the present application provides a pole piece, comprising: a current collector, comprising a first region and a second region, the second region and the first region being arranged along the width direction of the current collector; an active material layer, arranged in the first region; wherein at least a portion of the second region is provided with a passivation layer.

[0006] In the embodiment of the present application, the electrode includes a current collector and an active material layer. The current collector includes a first region and a second region arranged along its width direction. The active material layer is arranged in the first region, and at least part of the second region is provided with a passivation layer. The passivation layer is used to eliminate at least part of the sharp burrs on the surface of the second region to reduce the risk of battery short circuit and thermal runaway caused by the sharp burrs in the second region piercing the separator, thereby improving the reliability of the battery.

[0007] In some embodiments, the second region includes a tab. Along the width direction of the current collector, the tab and the second region have the same size. A passivation layer is disposed on the tab.

[0008] In the technical solution of the embodiment of the present application, the second region of the current collector includes the pole tab. A passivation layer is provided on at least a portion of the pole tab to eliminate at least a portion of the sharp burrs of the pole tab, thereby reducing the risk of the burrs of the pole tab piercing the diaphragm and causing insufficient battery reliability.

[0009] In some embodiments, the tab includes two first surfaces opposite to each other along a thickness direction thereof and a first side surface connected to the first surface, and the passivation layer is disposed on the first surface and / or the first side surface.

[0010] In the technical solution of the embodiment of the present application, a passivation layer is arranged on the first surface and / or second surface of the tab to eliminate at least part of the sharp burrs on the first surface and / or second surface of the tab, so as to reduce the risk of the burrs of the tab piercing the diaphragm and causing insufficient battery reliability.

[0011] In some embodiments, the second region includes a tab and an edge portion disposed between the tab and the active material layer, and a passivation layer is disposed on at least one of the tab and the edge portion.

[0012] In the technical solution of the embodiment of the present application, the second region includes the electrode tab and the edge portion arranged between the electrode tab and the active material layer. A passivation layer is provided in at least a portion of the edge portion to eliminate at least part of the sharp burrs on the surface of the edge portion, so as to reduce the risk of the burrs on the edge portion piercing the diaphragm and causing insufficient battery reliability.

[0013] In some embodiments, the passivation layer disposed on the edge portion is made of an insulating material.

[0014] In the technical solution of the embodiment of the present application, the passivation layer at the edge is made of an insulating material. By setting a passivation layer of an insulating material at the edge, when the diaphragm portion corresponding to the edge of the electrode is missing, the passivation layer of the insulating material can insulate the positive and negative electrode sheets, thereby reducing the risk of short circuit inside the battery and improving the reliability of the battery.

[0015] In some embodiments, the thickness L of the passivation layer satisfies 1 μm≤L≤30 μm.

[0016] In the technical solution of the embodiment of the present application, when the thickness L of the passivation layer is within the above-mentioned range, it can further smooth the sharp burrs in the second region and reduce the damage of the burrs in the second region to the diaphragm. At the same time, the passivation layer will not be too thick, causing the passivation treatment to have too much influence on the physical and chemical properties of the second region itself, thereby causing the problem of decreased battery performance.

[0017] In some embodiments, the thickness L of the passivation layer satisfies 22 μm≤L≤24 μm.

[0018] In the technical solution of the embodiment of the present application, when the thickness L of the passivation layer is within the above range, it can not only smooth the sharp burrs in the second region and reduce the damage of the burrs in the second region to the diaphragm, but also prevent the passivation layer from being easily scratched and fallen off under the action of external force, thereby exposing the second region because the passivation layer is too thin; and since the passivation layer will not be too thick, the preparation cost of the electrode can also be reduced.

[0019] In some embodiments, the passivation layer is one of an aluminum oxide layer, a copper oxide layer, an aluminum chromate layer, a copper chromate layer, an aluminum nitride layer, and a copper nitride layer.

[0020] In the technical solution of the embodiment of the present application, the passivation layer is one of an aluminum oxide layer, a copper oxide layer, an aluminum chromate layer, a copper chromate layer, an aluminum nitride layer, and a copper nitride layer. The above-mentioned passivation layer is used to eliminate at least part of the sharp burrs on the surface of the second region to reduce the risk of battery short circuit and thermal runaway caused by the sharp burrs in the second region piercing the mold.

[0021] In some embodiments, the passivation layer is an aluminum chromate layer or a copper chromate layer.

[0022] In the technical solution of the embodiment of the present application, the passivation layer is an aluminum chromate layer or a copper chromate layer. The aluminum chromate layer or the copper chromate layer is relatively loose and has a greater thickness. It is not easy for the second area to be exposed due to scratches during production and use.

[0023] In a second aspect, the present application provides a method for preparing a pole piece, which is used to prepare the pole piece of any embodiment of the first aspect.

[0024] performing a passivation treatment on the second region of the pole piece;

[0025] A passivation layer is formed on at least a portion of the second region of the pole piece.

[0026] In the technical solution of the embodiment of the present application, the second area of ​​the pole piece is passivated to form a passivation layer on at least part of the second area. The passivation layer is used to eliminate at least part of the sharp burrs on the surface of the second area, so as to reduce the risk of battery short circuit and thermal runaway caused by the sharp burrs in the second area piercing the separator, thereby improving the reliability of the battery.

[0027] In some embodiments, the step of “passivating the second region of the electrode piece” includes:

[0028] The second region is passivated using a passivation treatment solution, or is heat-treated using a heat source to form a passivation layer on the second region, or is passivated using plasma.

[0029] In the technical solution of the embodiment of the present application, the second region is treated with a passivation treatment liquid or heated by a heat source to form a passivation layer on the second region, or the second region is passivated by plasma to reduce the risk of battery short circuit and thermal runaway caused by sharp burrs in the second region piercing the mold, thereby improving the reliability of the battery.

[0030] In some embodiments, the step of “passivating the second region with a passivation solution” includes:

[0031] Applying a passivation treatment solution to at least a portion of the second region to obtain an intermediate,

[0032] The passivation treatment solution is a chromic acid treatment solution, a chromium salt treatment solution, or a chromium-free treatment solution, and the second region of the current collector includes copper or aluminum;

[0033] The intermediate is dried at 120° C. and allowed to stand for 24 hours to form a passivation layer in the second region. The passivation layer includes an aluminum chromate passivation layer, a copper chromate passivation layer, or an aluminum oxide passivation layer.

[0034] In the technical solution of the embodiment of the present application, a passivation treatment liquid is applied to at least a portion of the second region to obtain an intermediate; and the intermediate is dried to form a passivation layer in the second region, so as to reduce the risk of battery short circuit and thermal runaway caused by sharp burrs in the second region piercing the separator, thereby improving the reliability of the battery.

[0035] In some embodiments, the chromium salt treatment solution uses a mixture of NaCrO2:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5, or the chromium salt treatment solution uses a mixture of Na2CrO4:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5, or the chromium salt treatment solution uses a mixture of Na2Cr2O7:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5; the chromic acid treatment solution uses a mixture of H2CrO4:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5, or the chromic acid treatment solution uses a mixture of H2Cr2O7:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5; the chromium-free treatment solution uses a mixture of hydrogen peroxide:water:ammonium bifluoride in a weight ratio of 5-10:100:5-10.

[0036] In the technical solution of the embodiment of the present application, a processing liquid with the above-mentioned ratio is applied to the second area to form a passivation layer in the second area, thereby reducing the risk of battery short circuit and thermal runaway caused by sharp burrs in the second area piercing the separator, thereby improving the reliability of the battery.

[0037] In some embodiments, the step of “heat-treating the second region using a heat source” includes:

[0038] The second region includes copper, and the second region of the pole piece is heated to 300℃-360℃ to form a passivation layer in the second region, and the passivation layer includes a copper oxide layer; alternatively, the second region includes aluminum, and the second region of the pole piece is heated to 140℃-160℃ to form a passivation layer in the second region, and the passivation layer includes an aluminum oxide layer.

[0039] In the technical solution of the embodiment of the present application, the second area of ​​the electrode is heated to form a passivation layer in the second area, so as to reduce the risk of battery short circuit and thermal runaway caused by sharp burrs in the second area piercing the mold, thereby improving the reliability of the battery.

[0040] In some embodiments, the step of “passivating the second region using plasma” includes:

[0041] The nitrogen-containing plasma is bombarded on the second region to form a passivation layer on the second region. The second region includes copper or aluminum, and the passivation layer includes an aluminum nitride layer or a copper nitride layer.

[0042] In the technical solution of the embodiment of the present application, nitrogen-containing plasma is used to bombard the second region to form a passivation layer in the second region, thereby reducing the risk of battery short circuit and thermal runaway caused by sharp burrs in the second region piercing the mold, thereby improving the reliability of the battery.

[0043] In a third aspect, an embodiment of the present application provides a battery cell, comprising a pole piece provided by any of the above-mentioned embodiments of the first aspect.

[0044] In a fourth aspect, an embodiment of the present application provides a battery, comprising the battery cell provided in the embodiment of the third aspect above.

[0045] In a fifth aspect, an embodiment of the present application provides an electrical device, comprising the battery provided in the embodiment of the fourth aspect above. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0047] Figure 1 is a structural schematic diagram of a vehicle provided in one embodiment of the present application;

[0048] Figure 2 1 is a schematic structural diagram of a battery provided in one embodiment of the present application;

[0049] Figure 3 This is a schematic structural diagram of a battery module provided in one embodiment of the application;

[0050] Figure 4 This is a schematic structural diagram of a battery cell provided in one embodiment of the present application;

[0051] Figure 5 This is a schematic diagram of a partial structure of the second region of a pole piece provided in one embodiment of the present application;

[0052] Figure 6 This is a schematic structural diagram of a pole piece provided in one embodiment of the present application;

[0053] Figure 7 yes Figure 6 Cross-sectional view at AA in the middle;

[0054] Figure 8 This is a schematic structural diagram of a pole piece provided in one embodiment of the present application;

[0055] Figure 9 yes Figure 8 Cross-sectional view at the middle BB;

[0056] Figure 10 This is a schematic structural diagram of a pole piece provided in one embodiment of the present application;

[0057] Figure 11 yes Figure 10 Cross-sectional view at CC;

[0058] Figure 12 This is a schematic structural diagram of a pole piece provided in one embodiment of the present application;

[0059] Figure 13 yes Figure 12 Cross-sectional view at DD in the middle;

[0060] Figure 14 It is a flowchart of the electrode preparation method of an embodiment of the present application.

[0061] The accompanying drawings in the specific implementation manner are as follows:

[0062] 1. Vehicle; 101. Motor; 102. Controller; 2. Battery; 202. Housing; 2021. First housing portion; 2022. Second housing portion; 201. Battery module; 3. Battery cell; 4. Housing; 5. Electrode assembly; 6. Top cover assembly;

[0063] 7. Pole piece;

[0064] 71. Current collector; 711. First region; 712. Second region; 7121. Tab; 7122. Edge; 7123. First surface; 7124. Second surface;

[0065] 72. Active material layer;

[0066] 73. Passivation layer. DETAILED DESCRIPTION

[0067] 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.

[0068] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the embodiments of the present application should have the common meanings understood by technicians in the field to which the embodiments of the present application belong.

[0069] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application.

[0070] In addition, the technical terms "first," "second," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. In the description of the embodiments of the present application, the meaning of "plurality" is more than two, unless otherwise specifically defined.

[0071] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0072] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0073] Currently, 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 vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0074] In this application, battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, and the embodiments of this application are not limited thereto. Battery cells may be cylindrical, flat, rectangular, or in other shapes, and the embodiments of this application are not limited thereto.

[0075] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery generally includes a casing that encloses one or more battery cells. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0076] A battery cell consists of an electrode assembly and electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet comprises a positive current collector and a positive active material layer, which is coated on the surface of the positive current collector. The positive current collector comprises a positive current collector portion, which is coated with the positive active material layer, and a positive electrode tab connected to the positive current collector portion. The positive current collector portion is coated with the positive active material layer, while the positive electrode tab is not coated with the positive active material layer.

[0077] The positive electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, aluminum foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0078] The positive electrode active material layer includes a positive electrode active material, which may include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, a composite material of lithium iron manganese phosphate and carbon, and their respective modified compounds. These positive electrode active materials may be used alone or in combination of two or more.

[0079] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode current collector; the negative electrode current collector includes a negative electrode current collecting part and a negative electrode tab connected to the negative electrode current collecting part, the negative electrode current collecting part is coated with the negative electrode active material layer, and the negative electrode tab is not coated with the negative electrode active material layer.

[0080] The negative electrode current collector may be a metal foil or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, aluminum foil, and aluminum alloy foil. The composite current collector may include a polymer base layer and a metal material layer formed on at least one surface of the polymer base layer. As examples, the metal material may include one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As examples, the polymer base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE). The negative electrode active material layer includes a negative electrode active material, which may include, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin oxide, and tin alloys. The present application is not limited to these materials, and other conventionally known materials that can be used as negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0081] The separator can be made of one or more of fiberglass, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and polyimide. The separator can be a single-layer film or a multi-layer composite film. In the case of a multi-layer composite film, the materials of each layer can be the same or different.

[0082] During the manufacturing and use of batteries, some batteries may experience internal short circuits due to damaged diaphragms, leading to accidents such as thermal runaway, spontaneous combustion and explosion.

[0083] The above problem is that after the slitting and die-cutting processes, some sharp burrs will form on the surface of the electrode. During subsequent processing and use, these sharp burrs may pierce the battery's diaphragm, causing the positive and negative electrodes inside the battery to short-circuit, leading to risks such as thermal runaway, spontaneous combustion and explosion, resulting in insufficient battery reliability.

[0084] Based on the above problems, the present application provides a pole piece, which includes a current collector and an active material layer. The current collector includes a first region and a second region arranged along its width direction. The active material layer is arranged in the first region, and at least part of the second region is provided with a passivation layer. The passivation layer is used to eliminate at least part of the sharp burrs on the surface of the second region to reduce the risk of battery short circuit and thermal runaway caused by the sharp burrs in the second region piercing the separator, thereby improving the reliability of the battery.

[0085] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical devices using batteries.

[0086] Electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may include fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may include pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0087] It should be understood that the technical solutions described in the embodiments of the present application are not limited to the batteries and electrical equipment described above, but can also be applied to all batteries including boxes and electrical equipment using batteries. However, for the sake of simplicity, the following embodiments are explained using electric vehicles as an example.

[0088] Please refer to Figure 1 , Figure 1Schematic diagram of the structure of vehicle 1 provided for some embodiments of the present application. Vehicle 1 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 2 is provided inside the vehicle 1, and the battery can be provided at the bottom, head or tail of the vehicle 1. Battery 2 can be used to power the vehicle 1. For example, battery 2 can serve as an operating power source for the vehicle 1. Vehicle 1 can also include a controller 102 and a motor 101. The controller 102 is used to control the battery to power the motor 101, for example, for starting, navigating and operating power requirements of the vehicle 1 during driving.

[0089] In some embodiments of the present application, the battery can serve not only as an operating power source for the vehicle 1 , but also as a driving power source for the vehicle 1 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1 .

[0090] In order to meet different power requirements, the battery 2 may include a plurality of battery cells, which refers to the smallest unit that constitutes a battery module or a battery pack. A plurality of battery cells can be connected in series and / or in parallel via electrode terminals for use in various applications. The battery 2 mentioned in this application includes a battery module or a battery pack. Among them, a plurality of battery cells can be connected in series, in parallel, or in mixed connection, and mixed connection refers to a mixture of series and parallel connection. In the embodiment of the present application, a plurality of battery cells can directly constitute a battery pack, or they can first constitute a battery module, and then the battery module constitutes a battery pack.

[0091] Figure 2 A schematic structural diagram of a battery 2 according to an embodiment of the present application is shown.

[0092] like Figure 2 As shown, the battery includes a box body 202 and a battery cell (not shown), and the battery cell is accommodated in the box body 202.

[0093] The housing 202 may be a simple three-dimensional structure such as a single rectangular parallelepiped, cylinder, or sphere, or a complex three-dimensional structure composed of a combination of simple three-dimensional structures such as rectangular parallelepiped, cylinder, or sphere. The housing 202 may be made of an alloy material such as aluminum alloy or iron alloy, a polymer material such as polycarbonate or polyisocyanurate foam, or a composite material such as glass fiber and epoxy resin.

[0094] The housing 202 is used to accommodate battery cells and can have various structures. In some embodiments, the housing 202 can include a first housing portion 2021 and a second housing portion 2022. The first housing portion 2021 and the second housing portion 2022 overlap each other, and the first housing portion 2021 and the second housing portion 2022 together define a storage space for accommodating the battery cells 3. The second housing portion 2022 can be a hollow structure with one end open. The first housing portion 2021 is a plate-like structure, and the first housing portion 2021 overlaps the open side of the second housing portion 2022 to form the housing 202 with a storage space. The first housing portion 2021 and the second housing portion 2022 can also both be hollow structures with one end open, and the open side of the first housing portion 2021 overlaps the open side of the second housing portion 2022 to form the housing 202 with a storage space. Of course, the first box body 2021 and the second box body 2022 can be in various shapes, such as cylinder, cuboid, etc.

[0095] In order to improve the sealing performance after the first box body 2021 and the second box body 2022 are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body 2021 and the second box body 2022.

[0096] Assuming that the first box body portion 2021 covers the top of the second box body portion 2022, the first box body portion 2021 can also be called an upper box cover, and the second box body portion 2022 can also be called a lower box cover.

[0097] In battery 2, there can be one or more battery cells. If there are multiple battery cells, they can be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections. Multiple battery cells can be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell system is housed within the housing 202. Alternatively, multiple battery cells can be first connected in series, in parallel, or in a hybrid connection to form a battery module 201, and then multiple battery modules 201 can be connected in series, in parallel, or in a hybrid connection to form a single system, which is then housed within the housing 202.

[0098] Figure 3 A schematic structural diagram of a battery module 201 according to an embodiment of the present application is shown.

[0099] In some embodiments, as Figure 2 and Figure 3 As shown, there are multiple battery cells 3, which are first connected in series, in parallel, or in series to form a battery module 201. The multiple battery modules 201 are then connected in series, in parallel, or in series to form a whole, and are accommodated in the box 202.

[0100] The multiple battery cells 3 in the battery module 201 can be electrically connected via a busbar component to achieve parallel connection, series connection, or mixed connection of the multiple battery cells 3 in the battery module 201 .

[0101] In the present application, the battery cell 3 may include a lithium-ion battery cell 3, a sodium-ion battery cell 3, or a magnesium-ion battery cell 3, etc., and the embodiments of the present application do not limit this. The battery cell 3 may be cylindrical, flat, rectangular, or in other shapes, and the embodiments of the present application do not limit this. Battery cells 3 are generally divided into three types based on the packaging method: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, and the embodiments of the present application do not limit this. However, for the sake of simplicity, the following embodiments are all described using a prismatic battery cell 3 as an example.

[0102] Figure 4 This is a schematic diagram of the structure of a battery cell 3 provided in some embodiments of the present application. A battery cell 3 is the smallest unit that makes up a battery. Figure 4 The battery cell 3 includes a top cover assembly 6, a shell 4 and an electrode assembly 5.

[0103] The electrode assembly 5 is a component in the battery cell 3 where electrochemical reactions occur. One or more electrode assemblies 5 may be contained in the housing 4. The electrode assembly 5 is mainly formed by winding or stacking electrode sheets, which are divided into positive electrode sheets and negative electrode sheets, and a separator is usually provided between the positive electrode sheets and the negative electrode sheets. The parts of the positive electrode sheets and the negative electrode sheets with active materials constitute the electrode body, and the parts of the positive electrode sheets and the negative electrode sheets without active materials each constitute a tab. The positive electrode tab and the negative electrode tab may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs connect the electrode terminals to form a current loop.

[0104] The housing 4 is a component used to cooperate with the top cover assembly 6 to form the internal environment of the battery cell 3, wherein the formed internal environment can be used to accommodate the electrode assembly 5, electrolyte (not shown in the figure), and other components. The housing 4 and the top cover assembly 6 can be independent components. An opening can be provided on the housing 4, and the internal environment of the battery cell 3 is formed by covering the opening with the top cover assembly 6. Alternatively, the top cover assembly 6 and the housing 4 can be integrated. Optionally, the top cover assembly 6 and the housing 4 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 4 needs to be encapsulated, the top cover assembly 6 is then closed over the housing 4. The housing 4 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylinder, a hexagonal prism, etc. The shape of the housing 4 can be determined according to the specific shape and size of the electrode assembly 5. The housing 4 can be made of various materials, and optionally, the housing 4 can be made of copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0105] See also Figures 5 to 7 , Figure 5 This is a schematic diagram of a partial structure of the second region of a pole piece provided in one embodiment of the present application; Figure 6 This is a schematic structural diagram of a pole piece provided in one embodiment of the present application; Figure 7 yes Figure 6 Cross-sectional view at AA in the middle.

[0106] First, as Figures 5 to 7 As shown, the present application provides a pole piece 7, which includes a current collector 71 and an active material layer 72. The current collector 71 includes a first region 711 and a second region 712, and the second region 712 and the first region 711 are arranged along the width direction of the current collector; the active material layer 72 is arranged in the first region 711; wherein, at least part of the second region 712 is provided with a passivation layer 73.

[0107] In the embodiment of the present application, the pole piece 7 includes a current collector 71 and an active material layer 72. The current collector 71 includes a first region 711 and a second region 712 arranged along its width direction. The active material layer 72 is arranged in the first region 711, and at least part of the second region 712 is provided with a passivation layer 73. The passivation layer 73 is used to eliminate at least part of the sharp burrs on the surface of the second region 712 to reduce the risk of battery short circuit and thermal runaway caused by the sharp burrs of the second region 712 piercing the mold, thereby improving the reliability of the battery.

[0108] like Figure 5 As shown, during the preparation of the pole piece 7, after processes such as die-cutting and slitting, some sharp burrs may be generated on the surface of the current collector 71 of the pole piece 7, and these sharp burrs can easily puncture the diaphragm. In order to improve this situation, in the pole piece 7 of the embodiment of the present application, a passivation layer 73 is formed on the second region 712 of the current collector 71. Specifically, a passivation layer 73 is formed on the surface of at least part of the sharp burrs on the surface of the second region 712 to make the sharp burrs smooth, so as to reduce the damage ability of the burrs on the surface of the second region 712 to the diaphragm. Here, "making the sharp burrs smooth" means that a passivation layer 73 is formed on the tip surface of the burr to increase the curvature of the tip part of the burr. Optionally, the burr length L1 satisfies 40μm≤L1≤200μm. For example, L1 is 40μm, 45μm, 100μm, 200μm, etc.

[0109] In the solutions of these embodiments, the burrs may be spherical, ellipsoidal, irregular, etc., and the orientation of the particles may be in any direction, which is not further limited by the present invention.

[0110] The “pole piece 7” can be a positive electrode piece or a negative electrode piece; the “current collector 71” can be a positive electrode current collector or a negative electrode current collector.

[0111] "At least a portion of the second region 712 is provided with a passivation layer 73" means that the passivation layer 73 is formed on at least a portion of the surface of the second region 712. The surface of the second region 712 includes two end surfaces in the thickness direction and a side surface connecting the two end surfaces. Sharp burrs may also exist on either of the two end surfaces of the second region 712 in the thickness direction or the side surface connecting the two end surfaces.

[0112] Optionally, a passivation layer 73 is formed on the entire surface of the second region 712 to reduce the risk of sharp burrs on the surface of the second region 712 piercing the separator and causing an internal short circuit in the battery.

[0113] Optionally, the thickness of the passivation layer 73 on the second region 712 is uniform everywhere, so as to improve the flatness of the second region 712 .

[0114] In some embodiments, as Figure 6 and Figure 7 As shown, the thickness L of the passivation layer 73 satisfies 1 μm≤L≤30 μm.

[0115] For example, the thickness of the passivation layer 73 may be 1 μm, 5 μm, 7.5 μm, 20 μm, or 25 μm, or a range consisting of any of the above values.

[0116] In these embodiments, when the thickness L of the passivation layer 73 is within the above range, it can further smooth the sharp burrs in the second region 712 and reduce the damage of the burrs in the second region 712 to the diaphragm. At the same time, the passivation layer 73 will not be too thick, causing the passivation treatment to have too great an impact on the physical and chemical properties of the second region 712 itself, thereby causing the problem of decreased battery performance.

[0117] In some other embodiments, the thickness L of the passivation layer 73 satisfies 22 μm≤L≤24 μm.

[0118] For example, the thickness of the passivation layer 73 may be 22 μm, 23 μm, or 24 μm.

[0119] In these embodiments, when the thickness L of the passivation layer 73 is within the above range, it can smooth the sharp burrs in the second region 712 and reduce the damage of the burrs in the second region 712 to the diaphragm, but also prevent the passivation layer 73 from being easily scratched and fallen off under the action of external force, thereby exposing the second region 712, because the passivation layer 73 is too thin. Moreover, since the passivation layer 73 is not too thick, the preparation cost of the electrode can also be reduced.

[0120] In some embodiments, as Figure 6 and Figure 7As shown, the passivation layer 73 is one of an aluminum oxide layer, a copper oxide layer, an aluminum chromate layer, a copper chromate layer, an aluminum nitride layer, and a copper nitride layer. Relevant technicians can select any of the passivation layers 73 in the above embodiments according to actual needs, or reasonably select other passivation layers 73.

[0121] In these embodiments, the passivation layer 73 is one of an aluminum oxide layer, a copper oxide layer, an aluminum chromate layer, a copper chromate layer, an aluminum nitride layer, and a copper nitride layer. The passivation layer 73 is used to eliminate at least a portion of the sharp burrs on the surface of the second region 712, thereby reducing the risk of the sharp burrs in the second region 712 piercing the mold, resulting in a battery short circuit and thermal runaway.

[0122] In some embodiments, as Figure 6 and Figure 7 As shown, the passivation layer 73 is an aluminum chromate layer or a copper chromate layer.

[0123] In these embodiments, the passivation layer 73 is an aluminum chromate layer or a copper chromate layer. The aluminum chromate layer or the copper chromate layer is relatively loose and thicker, and is not easily scratched during production and use to expose the second area 712.

[0124] In some embodiments, as Figure 6 and Figure 7 As shown, the second region 712 includes a tab 7121 . Along the width direction of the current collector, the tab 7121 and the second region 712 have the same size. A passivation layer 73 is provided on the tab 7121 .

[0125] In these embodiments, the second region 712 of the current collector 71 includes a pole tab 7121. A passivation layer 73 is provided on at least a portion of the pole tab 7121 to eliminate at least a portion of the sharp burrs of the pole tab 7121, thereby reducing the risk of the burrs of the pole tab 7121 piercing the diaphragm and causing insufficient battery reliability.

[0126] The tab 7121 and the second region 712 have the same size in the width direction of the current collector, which means that the second region 712 of the current collector 71 serves as the tab 7121 and is electrically connected to other components, and the tab 7121 is in direct contact with the first region.

[0127] Optionally, a passivation layer 73 is formed on the entire surface of the tab 7121 to eliminate sharp burrs on the surface of the tab 7121, thereby reducing the risk of battery short circuit and thermal runaway caused by sharp burrs on the surface of the tab 7121 piercing the separator, thereby improving battery reliability.

[0128] In some embodiments, as Figure 5 and Figure 6As shown, the tab 7121 includes two first surfaces 7123 oppositely arranged along its thickness direction and a first side surface 7124 connected to the first surface 7123 , and the passivation layer 73 is arranged on the first surface 7123 and / or the first side surface 7124 .

[0129] In these embodiments, the passivation layer 73 is disposed on the first surface 7123 and / or the first side 7124 of the tab 7121 to eliminate at least some of the sharp burrs of the tab 7121 on its first surface 7123 and / or the first side 7124, so as to reduce the risk of the burrs of the tab 7121 piercing the diaphragm, resulting in insufficient battery reliability.

[0130] Specifically, the passivation layer 73 is disposed on one of the first surfaces 7123 , or the passivation layer 73 is disposed on both first surfaces 7123 , or the passivation layer 73 is disposed on the first side surface 7124 .

[0131] See also Figures 8 to 13 , Figure 8 This is a schematic structural diagram of a pole piece provided in one embodiment of the present application; Figure 9 yes Figure 8 Cross-sectional view at the middle BB; Figure 10 This is a schematic structural diagram of a pole piece provided in one embodiment of the present application; Figure 11 yes Figure 10 Cross-sectional view at CC; Figure 12 This is a schematic structural diagram of a pole piece provided in one embodiment of the present application; Figure 13 yes Figure 12 Cross-sectional view at DD in the middle.

[0132] In other embodiments, Figures 8 to 13 As shown, the second region 712 includes a tab 7121 and an edge portion 7122 disposed between the tab 7121 and the active material layer 72 . A passivation layer 73 is disposed on at least one of the tab 7121 and the edge portion 7122 .

[0133] In the technical solution of the embodiment of the present application, the second region 712 includes a pole ear 7121 and an edge portion 7122 arranged between the pole ear 7121 and the active material layer 72. A passivation layer 73 is provided in at least a portion of the edge portion 7122 to eliminate at least part of the sharp burrs on the surface of the edge portion 7122, thereby reducing the risk of the burrs on the edge portion 7122 piercing the diaphragm and causing insufficient battery reliability.

[0134] The size and function of the tab 7121 in this embodiment are the same as those of the tab 7121 in the above embodiment. The size of the second region 712 in the width direction of the current collector in this embodiment is larger than the size of the second region 712 in the width direction of the current collector in the above embodiment. The size difference between the two is the size of the edge portion 7122 in the width direction of the current collector.

[0135] There are differences in the structures of the current collectors 71 of the positive electrode sheet and the negative electrode sheet. If the first region 711 of one is smaller than that of the other in the width direction of the current collector, an edge portion 7122 will be formed between the active material layer 72 and the tab 7121 on the current collector 71 with the smaller first region 711. The edge portion 7122 and the other electrode sheet 7 should be insulated by an isolation film.

[0136] However, in the actual production process, the edge portion 7122 and the current collector 71 of the other electrode 7 may not be completely isolated by the isolation membrane due to insufficient isolation membrane size, isolation membrane misalignment, process precision problems during the winding process that lead to misalignment of the positive and negative electrodes, burrs on the edge piercing the separator, etc., which may cause the battery to have a high risk of internal short circuit. Therefore, in the embodiment of the present application, a solution is adopted to form an insulating passivation layer 73 on the edge portion 7122. When the edge portion 7122 and the other electrode 7 cannot be completely isolated by the isolation membrane, the passivation layer 73 can still maintain insulation, thereby improving the reliability of the battery. Exemplarily, the insulating passivation layer 73 is an aluminum oxide passivation layer.

[0137] Optional, such as Figure 8 and Figure 13 As shown, the second region 712 includes a tab 7121 and an edge portion 7122, wherein the edge portion 7122 is disposed between the tab 7121 and the active material layer 72. A passivation layer 73 may be formed on a surface of at least one of the tab 7121 or the edge portion 7122.

[0138] Optionally, a passivation layer 73 is formed on the entire surface of the lug 7121 and the edge portion 7122 of the current collector 71 to eliminate sharp burrs on the surface of the lug 7121 and the edge portion 7122 of the pole piece 7, so as to reduce the risk of battery short circuit and thermal runaway caused by the sharp burrs on the surface of the lug 7121 and the edge portion 7122 of the pole piece 7 piercing the separator, thereby improving the reliability of the battery.

[0139] In some embodiments, as Figure 8 and Figure 9 As shown, the passivation layer 73 disposed on the edge portion 7122 is made of insulating material.

[0140] In these embodiments, the passivation layer 73 of the edge portion 7122 is made of an insulating material. By providing the passivation layer 73 of the insulating material on the edge portion 7122, when the diaphragm portion corresponding to the edge portion 7122 of the electrode 7 is missing, the passivation layer 73 of the insulating material can insulate the positive and negative electrode sheets 7, thereby reducing the risk of internal short circuit in the battery and improving the reliability of the battery.

[0141] By forming a passivation layer 73 of insulating material on the edge portion 7122, the passivation layer 73 can assist and replace the insulation capability of the separator. Therefore, even if the separator corresponding to the edge portion 7122 is damaged, the passivation layer 73 can still insulate the positive and negative electrode sheets, thereby reducing the risk of internal short circuits in the battery.

[0142] For example, the passivation layer 73 made of insulating material may be an aluminum oxide passivation layer or an aluminum chromate passivation layer.

[0143] It should be clear that the passivation layer 73 of insulating material is only arranged on the edge portion 7122, and the passivation layer 73 set on the tab 7121 should be a conductive material. For example, the passivation layer 73 of conductive material can be a copper oxide passivation layer, a copper chromate passivation layer, an aluminum nitride passivation layer, or a copper nitride passivation layer.

[0144] See also Figure 14 , Figure 14 It is a flowchart of the electrode preparation method of an embodiment of the present application.

[0145] Second, as Figure 14 As shown, the present application provides a method for preparing a pole piece, which is used to prepare the pole piece of any embodiment of the first aspect above.

[0146] Step S1: performing passivation treatment on the second region of the electrode;

[0147] Step S2: forming a passivation layer on at least a portion of the second region of the electrode.

[0148] In the technical solution of the embodiment of the present application, the second area of ​​the pole piece is passivated to form a passivation layer on at least part of the second area. The passivation layer is used to eliminate at least part of the sharp burrs on the surface of the second area, so as to reduce the risk of battery short circuit and thermal runaway caused by the sharp burrs in the second area piercing the separator, thereby improving the reliability of the battery.

[0149] Optionally, during the pole piece preparation process, the second region may be passivated downstream of the pole piece slitting device.

[0150] In some embodiments, step S1 includes:

[0151] Step S11: passivating the second region with a passivation treatment solution, or performing heat treatment on the second region using a heat source to form a passivation layer on the second region, or performing passivation treatment on the second region using plasma.

[0152] In these embodiments, the second region is treated with a passivation treatment solution or heated with a heat source to form a passivation layer on the second region, or the second region is passivated using plasma to reduce the risk of sharp burrs in the second region piercing the separator, resulting in battery short circuit and thermal runaway, thereby improving battery reliability.

[0153] The passivation treatment solution is a chromic acid treatment solution, a chromium salt treatment solution, or a chromium-free treatment solution. The chromium salt treatment solution uses a mixture of NaCrO2:water:ammonium bifluoride at a weight ratio of 5-10:100:1-5, or a mixture of Na2CrO4:water:ammonium bifluoride at a weight ratio of 5-10:100:1-5, or a mixture of Na2Cr2O7:water:ammonium bifluoride at a weight ratio of 5-10:100:1-5. Exemplarily, the chromium salt treatment solution uses a mixture of NaCrO2:water:ammonium bifluoride at a weight ratio of 5:100:2.

[0154] The chromic acid treatment solution is a mixture of H2CrO4:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5. The chromic acid treatment solution is a mixture of H2Cr2O7:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5. For example, the chromic acid treatment solution is a mixture of H2CrO4:water:ammonium bifluoride in a weight ratio of 7:100:5.

[0155] The chromium-free treatment solution is a mixture of hydrogen peroxide: water: ammonium bifluoride at a weight ratio of 5-10:100; 5-10. For example, the chromium-free treatment solution is a mixture of hydrogen peroxide: water: ammonium bifluoride at a weight ratio of 7:100:8.

[0156] "The second area is heated by a heat source", the heat source can be one or more of flame, laser, and electromagnetic induction.

[0157] The passivation layer is one of an aluminum oxide layer, a copper oxide layer, an aluminum chromate layer, a copper chromate layer, an aluminum nitride layer, and a copper nitride layer.

[0158] Exemplarily, the preparation method of each passivation layer is as follows:

[0159] 1. Copper oxide layer: The current collector is copper foil, which is heated to 300℃~360℃ in air to obtain a copper oxide layer;

[0160] 2. Aluminum oxide layer: The current collector is aluminum foil, which is heated to 140°C to 160°C in air to obtain an aluminum oxide layer;

[0161] 3. Aluminum chromate layer: The second area is treated with a chromium salt treatment solution of a mixture of Na2Cr2O7: water: ammonium bifluoride in a weight ratio of 5-10:100:1-5, or a chromic acid treatment solution of a mixture of H2Cr2O7: water: ammonium bifluoride in a weight ratio of 5-10:100:1-5;

[0162] 4. Copper chromate layer: Treat the second area with chromic acid treatment solution or chromium salt treatment solution;

[0163] 5. Aluminum nitride: Aluminum nitride is prepared using plasma-enhanced chemical vapor deposition (PECVD) technology. Ion gas (nitrogen and argon at flow rates of 40 L / h and 25 L / h, respectively) flows from a tungsten electrode nozzle into the plasma arc region, connecting the electrical circuit between the tungsten electrode and the aluminum foil to form a plasma transferred arc. The plasma transferred arc has a current of 130 A and a voltage of 40 V. The nitrogen-containing plasma bombards the aluminum foil surface to form an aluminum nitride layer.

[0164] 6. Copper nitride: It is prepared using plasma enhanced chemical vapor deposition technology. The ion gas (nitrogen and argon flow rates are 35L / h and 25L / h, respectively) flows from the tungsten electrode nozzle to the plasma arc area, connecting the electrical circuit between the tungsten electrode and the aluminum foil to form a plasma transferred arc. The current of the plasma transferred arc is 140A and the voltage is 40V. The nitrogen-containing plasma bombards the surface of the copper foil to form a copper nitride layer.

[0165] In some embodiments, step S11 includes:

[0166] Step S111: applying a passivation treatment solution to at least a portion of the second region to obtain an intermediate, wherein the passivation treatment solution is a chromic acid treatment solution, a chromium salt treatment solution, or a chromium-free treatment solution, and the second region of the current collector includes copper or aluminum;

[0167] Step S112: drying the intermediate at 120° C. and leaving it to stand for 24 hours to form a passivation layer in the second region. The passivation layer includes an aluminum chromate passivation layer, a copper chromate passivation layer, or an aluminum oxide passivation layer.

[0168] In these embodiments, a passivation treatment liquid is applied to at least a portion of the second region to obtain an intermediate; and the intermediate is dried to form a passivation layer in the second region, thereby reducing the risk of sharp burrs in the second region piercing the separator, causing battery short circuit and thermal runaway, thereby improving battery reliability.

[0169] In some embodiments, the chromium salt treatment solution uses a mixture of NaCrO2:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5, or the chromium salt treatment solution uses a mixture of Na2CrO4:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5, or the chromium salt treatment solution uses a mixture of Na2Cr2O7:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5; the chromic acid treatment solution uses a mixture of H2CrO4:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5, or the chromic acid treatment solution uses a mixture of H2Cr2O7:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5; the chromium-free treatment solution uses a mixture of hydrogen peroxide:water:ammonium bifluoride in a weight ratio of 5-10:100:5-10.

[0170] In these embodiments, a processing liquid with the above-mentioned ratio is applied to the second region to form a passivation layer in the second region, thereby reducing the risk of battery short circuit and thermal runaway caused by sharp burrs in the second region piercing the separator, thereby improving battery reliability.

[0171] In some embodiments, step S11 includes:

[0172] Step S113: If the second region includes copper, the second region of the pole piece is heated to 300°C-360°C to form a passivation layer in the second region, and the passivation layer includes a copper oxide layer; or, if the second region includes aluminum, the second region of the pole piece is heated to 140°C-160°C to form a passivation layer in the second region, and the passivation layer includes an aluminum oxide layer.

[0173] In these embodiments, the second region of the pole piece is heated to form a passivation layer in the second region, thereby reducing the risk of battery short circuit and thermal runaway caused by sharp burrs in the second region piercing the separator, thereby improving battery reliability.

[0174] In some embodiments, step S11 includes:

[0175] Step S114 : bombarding the second region with nitrogen-containing plasma to form a passivation layer in the second region. The second region includes copper or aluminum, and the passivation layer includes an aluminum nitride layer or a copper nitride layer.

[0176] In these embodiments, nitrogen-containing plasma is used to bombard the second region to form a passivation layer in the second region, thereby reducing the risk of sharp burrs in the second region piercing the separator, causing battery short circuit and thermal runaway, thereby improving battery reliability.

[0177] The positive electrode active material includes a material that can reversibly extract and insert lithium ions. The positive electrode active material can be a material known in the art. In some embodiments, as an example, the positive electrode active material may include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, a composite material of lithium iron manganese phosphate and carbon, and their respective modified compounds. These positive electrode active materials may be used alone or in combination of two or more.

[0178] The positive electrode slurry includes a solvent, a positive electrode active material, an optional positive electrode conductor and an optional positive electrode binder, and the passivation solution includes the passivation solution of the first aspect of the present application; the positive electrode slurry is coated on at least one surface of the positive electrode current collector to form a positive electrode active material layer.

[0179] The present application does not particularly limit the type of positive electrode conductive agent. In some embodiments, as examples, the positive electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, carbon nanofibers, and activated carbon.

[0180] In some embodiments, as an example, the positive electrode binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyhexafluoropropylene, styrene-butadiene rubber, sodium carboxymethyl cellulose, polyvinyl pyrrolidone, polyvinyl ether, polymethyl methacrylate, polyamide, polyacrylonitrile and polyacrylate.

[0181] The negative electrode active material may be a material known in the art. In some embodiments, as an example, the negative electrode active material may include, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloy materials. Tin-based materials may include one or more of elemental tin, tin oxide, and tin alloy materials. The present application is not limited to these materials, and other conventionally known materials that can be used as negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0182] The negative electrode slurry is generally prepared by dispersing the negative electrode active material, an optional negative electrode conductive agent, an optional negative electrode binder, and other optional additives in a solvent and stirring the mixture until uniform. The solvent may be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.

[0183] The present application has no particular limitation on the type of negative electrode conductive agent. As an example, the negative electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0184] The present application has no particular restriction on the type of negative electrode binder. As an example, the negative electrode binder may include one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA) and carboxymethyl chitosan (CMCS).

[0185] The negative electrode film layer may optionally include other additives. For example, the other additives may include a thickener, such as sodium carboxymethyl cellulose (CMC), a PTC thermistor material, and the like.

[0186] The following describes the electrode provided by the present invention through specific embodiments.

[0187] Example 1: Figure 8 and Figure 9 As shown, weigh the positive electrode active material LiNi 0.5 Co 0.2 Mn 0.3 1 kg of O2 (NCM523), 20 g of carbon nanotubes as a positive electrode conductor, and 20 g of PVDF as a positive electrode binder were added to 1 kg of N-methylpyrrolidone (NMP) as a solvent, and then stirred in a blender for 30 minutes to form a stable and uniform positive electrode slurry. The positive electrode slurry is evenly coated on the surface of a 200 mm wide and 13 μm thick aluminum foil, and then placed in an oven and dried at 80°C and cold pressed to obtain a positive electrode active material layer 72, the width of the active material layer 72 is 114 mm; the cold-pressed electrode piece 7 is die-cut, the height of the pole ear 7121 is 20 mm, and the width is 20 mm, and the die-cut electrode piece 7 is striped; after striping, the width of the first area 711 is 57 mm, and the width of the edge 7122 of the collector 71 is 3 mm; the edge 7122 of the collector 71 is passivated using a chromium salt treatment solution, the chromium salt treatment solution uses a mixture of NaCrO2: water: ammonium bifluoride with a weight ratio of 5:100:2, and the temperature of the chromium salt treatment solution is 160°C~170°C; so that an aluminum oxide passivation layer is formed on the edge 7122; the thickness of the passivation layer 73 is 23±1 μm.

[0188] Example 2: Figure 8 and Figure 9 As shown, weigh the positive electrode active material LiNi 0.5 Co 0.2 Mn 0.3 1 kg of O2 (NCM523), 20 g of carbon nanotubes as a positive electrode conductor, and 20 g of PVDF as a positive electrode binder were added to 1 kg of N-methylpyrrolidone (NMP) as a solvent, and then stirred in a blender for 30 minutes to form a stable and uniform positive electrode slurry. The positive electrode slurry is evenly coated on the surface of an aluminum foil with a width of 150 mm and a thickness of 13 μm, and then placed in an oven and dried at 80°C and cold pressed to obtain a positive electrode active material layer 72. The width of the active material layer 72 is 96 mm. The cold-pressed electrode piece 7 is die-cut. The height of the tab 7121 is 20 mm and the width is 20 mm. The die-cut electrode piece 7 is stripped. After stripping, the width of the first area 711 is 48 mm, and the width of the aluminum foil at the edge 7122 of the current collector 71 is 3 mm. The edge 7122 of the current collector 71 is passivated using a chromium salt treatment solution. The chromium salt treatment solution uses a mixture of Na2Cr2O7: water: ammonium bifluoride with a weight ratio of 6:100:5. The temperature of the chromium salt treatment solution is 170°C to 180°C. This forms an aluminum chromate passivation layer on the edge. The thickness of the passivation layer 73 is 25±1 μm.

[0189] Example 3: Figure 6 and Figure 7 As shown, 1 kg of negative electrode active material (a mixture of natural graphite and artificial graphite with a particle size of 15 μm, with a weight ratio of natural graphite to artificial graphite of 1:9), 10 g of acetylene black as a negative electrode conductive agent, 30 g of styrene-butadiene rubber as a negative electrode binder, and 20 g of sodium carboxymethyl cellulose were weighed and added to 1 kg of deionized water and stirred to obtain a negative electrode slurry. A 200 mm wide and 6 μm thick copper foil was taken and the negative electrode slurry was coated on both sides of the copper foil with a coating width of 170 mm. The electrode piece 7 After drying, cold pressing is performed to obtain the negative electrode active material layer; the cold-pressed electrode piece 7 is die-cut, and the height of the tab 7121 is 20 mm and the width is 20 mm. The die-cut electrode piece 7 is stripped; after stripping, the width of the first region 711 is 65 mm. A heat source is used to heat the second region 712 of the current collector 71, and the surface temperature of the second region 712 is 300°C to 350°C; so that a copper oxide passivation layer is formed in the second region 712, and the thickness of the passivation layer 73 is 23±1 μm.

[0190] Comparative Example 1: The positive electrode slurry preparation process is the same as that of Example 1. A 200 mm wide and 13 μm thick aluminum foil is taken, and the positive electrode slurry is coated on the upper and lower surfaces of the aluminum foil with a coating width of 114 mm; then it is placed in an oven and dried at 80°C and cold pressed to obtain a positive electrode active material layer; the cold-pressed electrode piece is die-cut, and the height of the electrode ear is 20 mm and the width is 20 mm. The die-cut electrode piece is stripped; after stripping, the width of the first area 711 is 57 mm, the width of the edge portion 7122 of the current collector is 3 mm, and the second area 712 is not provided with an insulating material or a passivation layer.

[0191] Comparative Example 2: The negative electrode slurry preparation process is the same as Example 2. A 200 mm wide and 6 μm thick copper foil is taken, and the negative electrode active material is coated on both sides of the copper foil with a coating width of 170 mm; the electrode is dried and cold pressed to obtain a negative electrode active material layer; the cold-pressed electrode is die-cut, and the height of the electrode ear is 20 mm and the width is 20 mm. The die-cut electrode is stripped; after stripping, the width of the first area 711 is 65 mm, and the second area 712 is not provided with an insulating material or a passivation layer.

[0192] The insulation properties of the electrodes prepared in Example 1, Example 2, Example 3, Comparative Example 1, and Comparative Example 2 were tested. The test method is as follows, and the results are shown in Table 1.

[0193] Insulation test method: Samples of the electrodes prepared in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were taken, each sample having a length of 5 cm. An insulation resistance meter was used to energize the sample at an AC voltage of 200 V for 15 seconds to observe whether breakdown occurred.

[0194] Table 1 Insulation test results of the pole pieces provided in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2

[0195] Number of samples Number of breakdowns Example 1 320 3 Example 2 330 5 Example 3 316 4 Comparative Example 1 310 26 Comparative Example 2 317 33

[0196] According to the data provided in Table 1, in the embodiment of the present application, by providing a passivation layer in at least a portion of the second region and eliminating at least a portion of the sharp burrs on the surface of the second region through the passivation layer, the risk of the sharp burrs in the second region piercing the separator, resulting in a short circuit and thermal runaway of the battery, can be reduced, thereby improving the reliability of the battery.

[0197] In a third aspect, an embodiment of the present application provides a battery cell, comprising a pole piece provided by any of the above-mentioned embodiments of the first aspect.

[0198] In a fourth aspect, an embodiment of the present application provides a battery, comprising the battery cell provided in the embodiment of the third aspect above.

[0199] In a fifth aspect, an embodiment of the present application provides an electrical device, comprising the battery provided in the embodiment of the fourth aspect above.

[0200] like Figures 1 to 13 As shown, an embodiment of the present application provides a pole piece 7, which includes a current collector 71 and an active material layer 72. The current collector 71 includes a first region 711 and a second region 712, which are arranged along the width of the current collector with the second region 712 and the first region 711. The active material layer 72 is disposed on the first region 711. The second region 712 of the current collector 71 includes a tab 7121, which is the same size as the second region 712 along the width of the current collector. A passivation layer 73 is disposed on the tab 7121. Alternatively, the second region 712 includes a tab and an edge portion 7122 disposed at one end of the tab 7121 facing the first region 711. The tab 7121 and the edge portion 7122 are disposed on the passivation layer 73, and the passivation layer 73 disposed on the edge portion 7122 is made of an insulating material. The thickness L of the passivation layer 73 satisfies 22 μm ≤ L ≤ 24 μm, and the passivation layer 73 is one of an aluminum chromate layer and a copper chromate layer.

[0201] In the embodiment of the present application, the pole piece 7 includes a current collector 71 and an active material layer 72. The current collector 71 includes a first region 711 and a second region 712 arranged along its width direction. The active material layer 72 is arranged in the first region 711, and at least part of the second region 712 is provided with a passivation layer 73. The passivation layer 73 is used to eliminate at least part of the sharp burrs on the surface of the second region 712 to reduce the risk of battery short circuit and thermal runaway caused by the sharp burrs of the second region 712 piercing the mold, thereby improving the reliability of the battery 2.

[0202] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A pole piece, characterized in that: include: a current collector comprising a first region and a second region, wherein the first region and the second region are arranged along a width direction of the current collector; an active material layer, disposed in the first region; Wherein, at least a portion of the second region is provided with a passivation layer.

2. The pole piece according to claim 1, characterized in that: The second region includes a tab. Along the width direction of the current collector, the tab and the second region have the same size. The passivation layer is disposed on the tab.

3. The pole piece according to claim 2, characterized in that: The tab includes two first surfaces arranged opposite to each other along a thickness direction thereof and a first side surface connected to the first surface, and the passivation layer is arranged on the first surface and / or the first side surface.

4. The pole piece according to claim 1, characterized in that: The second region includes a tab and an edge portion disposed between the tab and the active material layer, and the passivation layer is disposed on at least one of the tab and the edge portion.

5. The pole piece according to claim 4, characterized in that: The passivation layer disposed on the edge portion is made of insulating material.

6. The pole piece according to claim 1, characterized in that: The thickness L of the passivation layer satisfies 1 μm≤L≤30 μm.

7. The pole piece according to claim 6, characterized in that: The thickness L of the passivation layer satisfies 22 μm≤L≤24 μm.

8. The pole piece according to claim 1, characterized in that: The passivation layer is one of an aluminum oxide layer, a copper oxide layer, an aluminum chromate layer, a copper chromate layer, an aluminum nitride layer, and a copper nitride layer.

9. The pole piece according to claim 1, characterized in that: The passivation layer is an aluminum chromate layer or a copper chromate layer.

10. A method for preparing a pole piece, for preparing the pole piece according to any one of claims 1 to 9, characterized in that: performing a passivation process on the second region of the pole piece; A passivation layer is formed on at least a portion of the second region of the pole piece.

11. The method for preparing a pole piece according to claim 10, characterized in that: The step of “passivating the second region of the pole piece” includes: The second region is passivated using a passivation treatment solution, or is heat-treated using a heat source to form a passivation layer on the second region, or is passivated using plasma.

12. The method for preparing a pole piece according to claim 11, characterized in that: The step of “passivating the second region with a passivation treatment solution” includes: Applying a passivation treatment solution on at least a portion of the second region to obtain an intermediate, wherein the passivation treatment solution is a chromic acid treatment solution, a chromium salt treatment solution, or a chromium-free treatment solution, and the second region of the current collector includes copper or aluminum; The intermediate is dried at 120° C. and allowed to stand for 24 hours to form a passivation layer in the second region. The passivation layer includes an aluminum chromate passivation layer, a copper chromate passivation layer, or an aluminum oxide passivation layer.

13. The method for preparing a pole piece according to claim 12, characterized in that: The chromium salt treatment liquid adopts a mixture of NaCrO2:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5, or the chromium salt treatment liquid adopts a mixture of Na2CrO4:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5, or the chromium salt treatment liquid adopts a mixture of Na2Cr2O7:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5; the chromic acid treatment liquid adopts a mixture of H2CrO4:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5; the chromic acid treatment liquid adopts a mixture of H2Cr2O7:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5; the chromic acid treatment liquid adopts a mixture of H2Cr2O7:water:ammonium bifluoride in a weight ratio of 5-10:100:1-5; the chromium-free treatment liquid adopts a mixture of hydrogen peroxide:water:ammonium bifluoride in a weight ratio of 5-10:100:5-10.

14. The method for preparing a pole piece according to claim 11, characterized in that: The step of “heat-treating the second region using a heat source” includes: The second region includes copper, and the second region of the pole piece is heated to 300°C-360°C to form the passivation layer in the second region, and the passivation layer includes a copper oxide layer; or, the second region includes aluminum, and the second region of the pole piece is heated to 140°C-160°C to form the passivation layer in the second region, and the passivation layer includes an aluminum oxide layer.

15. The method for preparing a pole piece according to claim 11, characterized in that: The step of “passivating the second region using plasma” includes: The second region is bombarded with nitrogen-containing plasma to form the passivation layer in the second region. The second region includes copper or aluminum, and the passivation layer includes an aluminum nitride layer or a copper nitride layer.

16. A battery cell, characterized in that: The pole piece comprises any one of claims 1 to 10.

17. A battery, characterized in that: The battery cell comprises the battery cell according to claim 16.

18. An electrical device, characterized in that: The battery comprising the battery as claimed in claim 17.

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