Electrode sheet, electrode assembly, cell, battery, and electric device

Abstract

Provided are an electrode sheet, an electrode assembly, a cell, a battery, and an electric device. The electrode sheet comprises a current collector and an active material layer; the current collector comprises a conductive layer; in the thickness direction of the electrode sheet, the active material layer is arranged on at least one side of the conductive layer; the conductive layer has a coated portion; the active material layer is arranged on the coated portion; and the melting point of at least part of the coated portion is less than or equal to 300°C. The melting point of at least partial area of the conductive layer is low, and therefore, when a short circuit occurs at the partial area inside the cell, the part of the conductive layer can be melted to cause an open circuit inside the cell, or the overcurrent capability of the conductive layer can be partially reduced after the partial area is melted, so that the conductive layer can be quickly melted, the active material layer in the short-circuit area collapses, and a positive electrode and a negative electrode that comprise the electrode sheet are disconnected, thereby effectively alleviating the temperature rise inside the cell, and thus reducing the risk of thermal runaway of the cell comprising the electrode sheet, and improving the reliability of the cell.

Description

Electrode pieces, electrode assemblies, battery cells, batteries and electrical equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202311426752X, filed on October 30, 2023, entitled “Pole piece, electrode assembly, battery cell, 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 pole piece, an electrode assembly, a battery cell, a battery, and an electrical device. Background Art

[0004] Due to their outstanding advantages, such as high energy density and excellent cycle performance, batteries have become the mainstream secondary battery product and are widely used in portable appliances, electric vehicles, mobile phones, spacecraft, and other fields. However, battery reliability is a major concern for users and a major factor restricting battery development. Therefore, how to improve battery reliability has become a pressing issue in the battery industry.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide a pole piece, an electrode assembly, a battery cell, a battery, and an electrical device to improve the reliability of the battery.

[0007] In a first aspect, embodiments of the present application provide a pole piece, comprising a current collector and an active material layer. The current collector comprises a conductive layer. The active material layer is disposed on at least one side of the conductive layer along the thickness direction of the pole piece. The conductive layer has a coating portion, the active material layer is disposed on the coating portion, and at least a portion of the coating portion has a melting point of less than or equal to 300°C.

[0008] In the above technical solution, the melting point of at least a portion of the coating portion of the conductive layer where the active material layer is arranged is less than or equal to 300°C, that is, the melting point of at least a portion of the coating portion is low. Then, when a short circuit occurs in this portion of the battery cell, this portion of the conductive layer can be melted in advance to cause the internal circuit of the battery cell to be broken, or after this portion of the area is melted, the overcurrent capacity of a portion of the conductive layer can be reduced, so that the coating portion can be quickly melted, and the active material layer in the short-circuit area collapses, so that the positive and negative poles with the electrode are disconnected, and then the battery cell is quickly broken. Therefore, the temperature rise inside the battery cell can be effectively alleviated, thereby reducing the risk of thermal runaway of the battery cell with the electrode and improving the reliability of the battery cell.

[0009] In some embodiments of the first aspect of the present application, the melting point of at least a portion of the coating portion is 200°C to 250°C.

[0010] In the above technical solution, the melting point of at least a portion of the coating portion is 200° C. to 250° C., which enables the battery cell equipped with the electrode to have a wider range of applications and a lower risk of thermal runaway.

[0011] In some embodiments of the first aspect of the present application, the melting point of any region of the conductive layer is less than or equal to 300°C.

[0012] In the above technical solution, the melting point of any area of ​​the conductive layer is less than or equal to 300°C, that is, the melting point of any area of ​​the conductive layer is low. When a short circuit occurs in any area inside the battery cell, the conductive layer can be melted in advance at the short-circuit position to cause the battery cell to be disconnected internally, or after the short-circuit area is melted, the overcurrent capacity of a part of the conductive layer can be reduced, so that the conductive layer can be quickly melted, and the active material layer in the short-circuit area collapses, so that the positive and negative poles with the electrode are disconnected, and then the battery cell is quickly disconnected. Therefore, it can effectively alleviate the temperature rise inside the battery cell, thereby reducing the risk of thermal runaway of the battery cell with the electrode and improving the reliability of the battery cell.

[0013] In some embodiments of the first aspect of the present application, the conductive layer further includes a pole ear portion, the pole ear portion and the coating portion are arranged along the width direction of the pole piece, the active material layer is not provided on the pole ear portion, and the melting point of the coating portion is lower than the melting point of the pole ear portion.

[0014] In the above technical solution, the melting point of the coating portion is lower than that of the pole ear portion, so that the coating portion is easier to melt than the pole ear portion. When a short circuit occurs inside the battery cell equipped with the pole piece, the conductive layer corresponding to the short-circuit area can be melted, and the active material layer in the short-circuit area collapses, so that the positive and negative poles equipped with the pole piece are disconnected, which can effectively alleviate the internal temperature rise of the battery cell, thereby reducing the risk of thermal runaway of the battery cell equipped with the pole piece and improving the reliability of the battery cell.

[0015] In some embodiments of the first aspect of the present application, the current collector further includes an insulating layer, and the conductive layer is provided on at least one side of the insulating layer along a thickness direction of the insulating layer.

[0016] In the above technical solution, the current collector also includes an insulating layer, which helps improve the strength of the current collector. If the current collector has a certain thickness, the insulating layer reduces the thickness of the current collector's conductive layer. When the current collector is punctured, the length of the burr generated at the puncture site is also reduced. This reduces the risk of the burr piercing the separator and causing an internal short circuit in the battery cell, thereby improving the reliability of the battery cell equipped with this electrode.

[0017] In some embodiments of the first aspect of the present application, the melting point of at least a portion of the coating portion is lower than the melting point of the insulating layer.

[0018] In the above technical solution, the melting point of at least a part of the coating portion is lower than the melting point of the insulating layer, so the conductive layer is more likely to melt relative to the insulating layer. When a short circuit occurs locally inside the battery cell equipped with the pole piece, the insulating layer may not melt when the conductive layer in the short-circuit area melts, thereby reducing the risk of other electrochemical reactions occurring inside the battery cell equipped with the pole piece due to the melting of the insulating layer, thereby causing other problems that reduce reliability, and reducing the risk of the battery cell equipped with the pole piece not being able to work normally due to the melting of the insulating layer.

[0019] In some embodiments of the first aspect of the present application, the melting point of the insulating layer is 120°C to 220°C.

[0020] In the above technical solution, the melting point of the insulating layer is 120° C. to 220° C., so that the battery cell equipped with the electrode can have a higher operating temperature and is conducive to controlling the manufacturing cost of the battery cell.

[0021] In some embodiments of the first aspect of the present application, the conductive layer is provided on both sides of the insulating layer along the thickness direction of the pole piece.

[0022] In the above technical solution, conductive layers are provided on both sides of the insulating layer along the thickness direction of the pole piece, and active material layers can be provided on both sides of the current collector along the thickness direction of the pole piece, which is beneficial to improving the energy density of the battery cell with the pole piece.

[0023] In some embodiments of the first aspect of the present application, the conductive layer is a metal plating layer provided on the surface of the insulating layer.

[0024] In the above technical solution, the conductive layer is a metal plating layer provided on the surface of the insulating layer. It can be understood that the conductive layer is plated on the surface of the insulating layer, which is convenient for processing.

[0025] In some embodiments of the first aspect of the present application, a material of the insulating layer includes at least one of polyethylene terephthalate and polypropylene.

[0026] In the above technical solution, polyethylene terephthalate and polypropylene have excellent insulation properties, heat resistance, and dimensional stability. Using these current collectors to manufacture pole pieces improves the reliability of battery cells equipped with these pole pieces. Polyethylene terephthalate and polypropylene are also lightweight, which helps reduce the weight of the pole pieces, and thus the weight of the battery cells manufactured using these pole pieces.

[0027] In some embodiments of the first aspect of the present application, the material of the conductive layer includes an alloy.

[0028] In the above technical solution, the alloy has a lower melting point than any of the metals that constitute the alloy. When an abnormal short circuit occurs inside a battery cell equipped with the electrode, the conductive layer in the abnormal short circuit area melts and the active material layer in the abnormal area collapses, causing the positive and negative poles to be disconnected, thereby achieving internal short circuit in the battery cell and improving the reliability of the battery cell.

[0029] In some embodiments of the first aspect of the present application, the alloy includes one or more of bismuth, lead, tin, cadmium, and zinc.

[0030] In the above technical solution, bismuth, lead, tin and cadmium are used to manufacture fusible alloys, which is beneficial to improving the reliability of battery cells equipped with the pole pieces.

[0031] In some embodiments of the first aspect of the present application, the material of the conductive layer includes an anti-oxidation material with conductive properties.

[0032] In the above technical solution, the material of the conductive layer includes an anti-oxidation material, which improves the corrosion resistance of the conductive layer.

[0033] In a second aspect, an embodiment of the present application further provides an electrode assembly, comprising the electrode piece provided in any embodiment of the first aspect.

[0034] In the above technical solution, if at least a portion of the coating portion of the electrode provided in any embodiment of the first aspect has a low melting point, then when the electrode assembly is short-circuited in the area with a lower melting point, this portion of the conductive layer can be melted in advance, thereby realizing the disconnection of the positive and negative poles of the electrode assembly, or after this portion of the area is melted, the overcurrent capacity of a portion of the conductive layer can be reduced, so that the conductive layer can be quickly melted, and then the positive and negative poles of the electrode assembly can be quickly disconnected, thereby effectively alleviating the temperature rise, thereby reducing the risk of thermal runaway of the battery cell equipped with the electrode assembly, and improving the reliability of the battery cell.

[0035] In some embodiments of the second aspect of the present application, the electrode assembly includes two pole pieces provided by any embodiment of the first aspect, and the two pole pieces have opposite polarities.

[0036] In a third aspect, an embodiment of the present application further provides a battery cell, comprising the electrode assembly provided in any embodiment of the second aspect.

[0037] In the above technical solution, when the electrode assembly provided in any embodiment of the second aspect is short-circuited, this part of the conductive layer can be melted in advance to realize the disconnection of the positive and negative poles of the electrode assembly, or the conductive layer is partially melted, which can reduce the overcurrent capacity of a part of the conductive layer, so that the conductive layer can be quickly melted, and then the positive and negative poles of the electrode assembly are quickly disconnected, thereby effectively alleviating the temperature rise, thereby reducing the risk of thermal runaway of the battery cell equipped with the electrode assembly and improving the reliability of the battery cell.

[0038] In some embodiments of the third aspect of the present application, the battery cell further includes a transition piece, the transition piece is electrically connected to the conductive layer, and the melting point of the transition piece is greater than the melting point of the conductive layer.

[0039] In the above technical solution, the melting point of the conductive layer is lower than the melting point of the adapter, which makes the conductive layer easier to melt than the adapter. When a short circuit occurs inside the battery cell, the conductive layer corresponding to the short-circuit area can melt, and the active material layer corresponding to the short-circuit area collapses, disconnecting the positive and negative poles of the battery cell, thereby achieving internal short circuit of the battery cell, which can effectively alleviate the temperature rise inside the battery cell, thereby reducing the risk of thermal runaway of the battery cell and improving the reliability of the battery cell.

[0040] In a third aspect, an embodiment of the present application further provides a battery, comprising the battery cell provided in any embodiment of the third aspect.

[0041] In the above technical solutions, the battery cell provided by any embodiment of the third aspect has good reliability, and the battery equipped with the battery cell also has good reliability.

[0042] In a fourth aspect, an embodiment of the present application further provides an electrical device, comprising the battery provided in any embodiment of the fourth aspect.

[0043] In the above technical solutions, the battery provided in the fourth embodiment has good reliability, which is beneficial to improving the power reliability of electrical equipment powered by the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] 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.

[0045] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0046] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0047] FIG3 is a schematic structural diagram of a battery provided in some embodiments of the present application;

[0048] FIG4 is a schematic diagram of the structure of a pole piece provided in some embodiments of the present application;

[0049] FIG5 is a schematic structural diagram of pole pieces provided in other embodiments of the present application;

[0050] FIG6 is a schematic diagram of a sharp object conducting electricity through two pole pieces with opposite polarities according to some embodiments of the present application;

[0051] FIG7 is a schematic diagram of a sharp object conducting electricity between two pole pieces with opposite polarities according to other embodiments of the present application;

[0052] FIG8 is a schematic structural diagram of pole pieces provided in some other embodiments of the present application;

[0053] FIG9 is a schematic structural diagram of a pole piece provided in some further embodiments of the present application;

[0054] FIG10 is a schematic structural diagram of pole pieces provided in yet other embodiments of the present application.

[0055] Icons: 1000-vehicle; 100-battery; 10-casing; 11-first part; 12-second part; 20-battery cell; 21-casing; 211-end cover; 212-shell; 213-electrode terminal; 22-electrode assembly; 221-pole piece; 221a-positive electrode piece; 221b-negative electrode piece; 2211-ear; 2212-current collector; 22121-conductive layer; 221211-coating part; 221212-ear part; 2213-active material layer; 22122-insulating layer; 222-isolation membrane; 200-controller; 300-motor; X-thickness direction of pole piece; Y-width direction of pole piece; 2000-sharp object. DETAILED DESCRIPTION

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0057] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0058] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0059] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0060] 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.

[0061] 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 for enclosing one or more battery cells. The casing can mitigate the problem of liquids or other foreign matter affecting the charging or discharging of the battery cells.

[0062] In this application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells 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 this application do not limit this.

[0063] A battery cell consists of a housing and an electrode assembly, which is housed within the housing. The electrode assembly consists of a separator and two electrode plates with opposite polarity. These two electrode plates are the positive and negative electrodes. A battery cell primarily operates by the movement of metal ions between the positive and negative electrodes. The electrode plates consist of a current collector and an active material layer, with the active material layer coated on the surface of the current collector.

[0064] During the battery cell cycle, the battery cell may short-circuit due to contact between the positive and negative poles. After the short circuit occurs, if the circuit is not disconnected in time, the battery cell will continue to release heat. The temperature is very high, enough to melt general metals. If the heat cannot be dissipated in time, it will burn electrical appliances, and may also cause fires or even explosions, causing serious property and life losses.

[0065] Battery cell short circuits are categorized as external and internal. External short circuits generally refer to short circuits caused by direct contact between the positive and negative electrodes. External short circuits can be prevented by installing a fuse on the adapter connected to the positive and / or negative lugs. When the current flowing through the adapter exceeds the fuse's current capacity, the fuse melts, disconnecting the positive and negative electrodes of the battery cell and thus breaking the circuit to prevent continued heat release. Once external short circuiting is achieved, the battery cell is generally scrapped.

[0066] An internal short circuit occurs when a battery cell is punctured by a sharp object, hit, or squeezed, causing a short circuit in the area within the battery exposed to external forces. An internal short circuit is a localized short circuit, resulting in a sustained temperature rise in that area. If internal short circuiting is not promptly achieved, the temperature rise in that area will gradually spread throughout the battery cell, potentially damaging electrical appliances, causing fires or even explosions, resulting in serious property and life loss, and deteriorating the reliability of the battery cell. However, the fuse designed to provide external short circuiting cannot achieve this internal short circuiting.

[0067] Based on the above considerations, in order to alleviate the reliability problems of battery cells caused by internal short circuits, an embodiment of the present application provides a pole piece, which includes a current collector and an active material layer. The current collector includes a conductive layer. Along the thickness direction of the pole piece, an active material layer is provided on at least one side of the conductive layer. The conductive layer has a coating portion, and the active material layer is provided on the coating portion. The melting point of at least a portion of the coating portion is less than or equal to 300°C.

[0068] The melting point of at least a portion of the coating portion of the conductive layer where the active material layer is provided is less than or equal to 300°C, that is, the melting point of at least a portion of the conductive layer is low. Then, when a short circuit occurs in this portion of the battery cell, this portion of the conductive layer can be melted in advance to cause an internal short circuit in the battery cell, or after this portion of the region is melted, the overcurrent capacity of a portion of the conductive layer can be reduced, so that the conductive layer can be quickly melted, and the active material layer in the short-circuit area collapses, so that the positive and negative poles with the electrode are disconnected, and then the battery cell is quickly short-circuited. Therefore, the temperature rise inside the battery cell can be effectively alleviated, thereby reducing the risk of thermal runaway of the battery cell with the electrode and improving the reliability of the battery cell.

[0069] The current collectors disclosed in the embodiments of this application can be used to manufacture pole pieces and battery cells. Battery cells equipped with the pole pieces provided in the embodiments of this application can be used, but are not limited to, in electrical equipment such as vehicles, ships, or aircraft. They can be used in power supply systems comprising battery cells and batteries manufactured from the pole pieces disclosed in this application. This helps alleviate reliability issues caused by internal short circuits in battery cells and improves the reliability of both the battery cells and the battery.

[0070] The embodiments of the present application provide an electric device that uses a battery as a power source. The electric device may 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, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0071] Please refer to Figure 1, which is a schematic structural 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.

[0072] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0073] Please refer to Figure 2, which 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 battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a storage space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for the battery cell 20. The second portion 12 can be a hollow structure with one end open. The first portion 11 can be a plate-like structure, with the first portion 11 overlapping the open side of the second portion 12, so that the first portion 11 and the second portion 12 together define a storage space. Alternatively, the first portion 11 and the second portion 12 can each be a hollow structure with one end open, with the open side of the first portion 11 overlapping the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0074] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0075] Each battery cell 20 may be a secondary battery or a primary battery, and may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0076] Please refer to Figure 3, which shows an exploded schematic diagram of a battery cell 20 provided in some embodiments of the present application. A battery cell 20 is the smallest unit that makes up a battery 100. As shown in Figure 3, a battery cell 20 includes a housing 21, an electrode assembly 22, and other functional components. The electrode assembly 22 is housed within the housing 21.

[0077] The outer shell 21 includes an end cap 211 and a shell 212. The end cap 211 refers to a component that covers the opening of the shell 212 to separate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 211 can be adapted to the shape of the shell 212 to match the shell 212. Optionally, the end cap 211 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 211 is not easily deformed when squeezed or collided, so that the battery cell 20 can have a higher structural strength and improved reliability. Functional components such as electrode terminals 213 can be provided on the end cap 211. The electrode terminal 213 can be used to electrically connect to the electrode assembly 22 for outputting or inputting electrical energy of the battery cell 20. In some embodiments, the end cap 211 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 211 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating component can be provided inside the end cap 211 to isolate the electrical connection components within the housing 212 from the end cap 211 to reduce the risk of short circuits. Exemplary materials include plastic, rubber, etc.

[0078] The housing 212 is a component that cooperates with the end cap 211 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the electrode assembly 22, electrolyte, and other components. The housing 212 and the end cap 211 can be separate components. An opening can be provided in the housing 212, and the end cap 211 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 211 and the housing 212 can be integrated. Specifically, the end cap 211 and the housing 212 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 212 is to be enclosed, the end cap 211 is placed over the housing 212. The housing 212 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylinder, or a hexagonal prism. Specifically, the shape of the housing 212 can be determined based on the specific shape and size of the electrode assembly 22. The housing 212 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, and plastic.

[0079] The electrode assembly 22 is the component within the battery cell 20 where the electrochemical reaction occurs. The housing 212 may contain one or more electrode assemblies 22. The electrode assembly 22 is primarily formed by winding or stacking two electrode sheets 221 of opposite polarity. A separator 222 (shown in Figures 5 and 6 ) is typically positioned between the two electrode sheets 221. The separator 222 can be made of materials such as PP (polypropylene) or PE (polyethylene).

[0080] The portions of the two oppositely polarized electrode sheets 221 containing active material form the main body of the electrode assembly 22, while the portions of the two oppositely polarized electrode sheets 221 not containing active material each form a tab 2211. Specifically, the portions of the two oppositely polarized electrode sheets 221 not containing active material form the positive tab and the negative tab, respectively. The positive tab and the negative tab can be located together at one end of the main body or separately at opposite ends of the main body. During the charge and discharge process of the battery 100, the positive and negative active materials react with the electrolyte, and the tabs 2211 connect to the electrode terminals 213 to form a current circuit.

[0081] As shown in Figures 4 and 5, in some embodiments, the electrode 221 includes a current collector 2212 and an active material layer 2213, the current collector 2212 includes a conductive layer 22121, and the active material layer 2213 is provided on at least one side of the conductive layer 22121 along the thickness direction X of the electrode, wherein the conductive layer 22121 has a coating portion 221211, the active material layer 2213 is provided on the coating portion 221211, and the melting point of at least a portion of the coating portion 221211 is less than or equal to 300°C.

[0082] Along the thickness direction X of the electrode sheet, the active material layer 2213 may be provided on only one side of the current collector 2212 , or may be provided on both sides of the current collector 2212 .

[0083] The material of the active material layer 2213 varies depending on the polarity of the electrode 221. For example, if the electrode 221 is a positive electrode 221a, the active material layer 2213 may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. If the electrode 221 is a negative electrode 221b, the active material layer 2213 may be carbon or silicon.

[0084] Along the thickness direction X of the pole piece, the active material layer 2213 is provided on one surface of the coating portion 221211 of the conductive layer 22121. Along the width direction Y of the pole piece, the conductive layer 22121 includes a coating portion 221211 and a pole ear portion 221212, and the pole ear portion 221212 is connected to one end of the coating portion 221211 along the width direction Y of the pole piece. The active material layer 2213 is provided on the surface of the coating portion 221211 along the thickness direction X of the pole piece, and the pole ear portion 221212 is not provided with the active material layer 2213. The pole ear 2211 of the pole piece 221 includes a pole ear portion 221212. The pole ear portion 221212 is used to electrically connect to the adapter (not shown in the figure) to lead out the electrode.

[0085] Since the active material layer 2213 is provided in the coating portion 221211, the region where the conductive layer 22121 overlaps the active material layer 2213 when viewed along the thickness direction X of the electrode sheet is the coating portion 221211. The melting point of at least a portion of the coating portion 221211 may be less than or equal to 300°C. The coating portion 221211 may have a portion with a melting point less than or equal to 300°C, as shown in Figure 5. In Figure 5, the melting point of region A1 is less than or equal to 300°C, while the melting point of the coating portion 221211, excluding region A1, is greater than 300°C. The coating portion 221211 may also have a melting point of less than or equal to 300°C across all regions. Figure 4 illustrates a case where the melting point of the coating portion 221211 is less than or equal to 300°C across all regions.

[0086] The melting point of at least a portion of the coating portion 221211 is less than or equal to 300° C. The material of at least a portion of the coating portion 221211 is a low melting point alloy.

[0087] In an embodiment where a portion of the coating portion 221211 has a melting point of less than or equal to 300°C, the material of this portion can be selected to have a melting point of less than or equal to 300°C, while the material of the remaining portions of the coating portion 221211 can be selected to have a melting point greater than 300°C. Alternatively, the thickness of this portion can be set to be smaller than the thickness of the remaining portions of the coating portion 221211, so that the thinner portion completely melts at a temperature of less than or equal to 300°C, causing the active material layer 2213 coated in the thinner portion to lose support and collapse. The coating portion 221211 can be made of pure metal or an alloy.

[0088] In embodiments where the melting point of the entire coating portion 221211 is less than or equal to 300°C, the entire coating portion 221211 can be made of a material having a melting point less than or equal to 300°C. Alternatively, the thickness of the coating portion 221211 can be set to be sufficiently small so that the short-circuit region completely melts at a temperature less than or equal to 300°C, causing the active material layer 2213 coated in the thinner region to lose support and collapse.

[0089] Of course, in other embodiments, the melting point of at least a portion of the coating portion 221211 can be made less than or equal to 300° C. by other means.

[0090] The thickness described in this application refers to the dimension of the corresponding structure in the thickness direction X of the pole piece.

[0091] The melting point of the coating portion 221211 is a temperature at which the conductive layer 22121 transitions (melts) from a solid state to a molten state.

[0092] As shown in Figures 6 and 7, when a battery cell 20 is punctured by a sharp object 2000, the sharp object 2000 pierces the pole piece 221 of opposite polarity, and the two pole pieces 221 of opposite polarity are short-circuited through the sharp object 2000, forming an internal short circuit in the punctured area of ​​the battery cell 20, which is also a local internal short circuit. Alternatively, in other cases, the battery cell 20 is collided or squeezed, causing the two pole pieces 221 of opposite polarity of the battery cell 20 to contact, and the two pole pieces 221 of opposite polarity contact and short circuit, that is, forming an internal short circuit in the battery cell 20 in the contact area. The temperature of the internal short-circuit area continues to rise. If the melting point of the conductive layer 22121 of the collector 2212 of the electrode 221 in the short-circuit area is low, when the temperature rises to the melting point of the conductive layer 22121 in the short-circuit area, the conductive layer 22121 corresponding to the short-circuit area melts, and the active material layer 2213 coated on the conductive layer 22121 in the short-circuit area collapses due to loss of support, and the short-circuit area is disconnected.

[0093] Therefore, the melting point of at least a portion of the coating portion 221211 is less than or equal to 300°C, that is, the melting point of at least a portion of the coating portion 221211 is low. Then, when a short circuit occurs in this portion of the battery cell 20, this portion of the conductive layer 22121 can be melted in advance to cause an internal short circuit in the battery cell 20, or after this portion of the area is melted, the current capacity of a portion of the conductive layer 22121 can be reduced, so that the coating portion 22121 can be quickly melted, and the active material layer 2213 in the short-circuit area collapses, so that the positive and negative poles with the pole piece 221 are disconnected, and then the battery cell 20 is quickly short-circuited. Therefore, the temperature rise inside the battery cell 20 can be effectively alleviated, thereby reducing the risk of thermal runaway of the battery cell 20 with the pole piece 221 and improving the reliability of the battery cell 20. Generally, thermal runaway will occur when the temperature of the battery cell 20 exceeds 300°C, and the coating portion 221211 in the internal short-circuit area has melted at 300°C, and the active material layer 2213 in the internal short-circuit area has collapsed, causing the positive and negative poles with the electrode 221 to be disconnected, thereby causing the battery cell 20 to be quickly short-circuited internally. The temperature of the battery cell 20 will not continue to rise, thereby reducing the risk of thermal runaway of the battery cell 20 and improving the reliability of the battery cell 20.

[0094] In some embodiments, the melting point of at least a portion of the coating portion 221211 is 200°C to 250°C.

[0095] The melting point of the coating portion 221211 may be 200° C., 210° C., 220° C., 230° C., 240° C., 250° C., etc. For example, if at least a portion of the coating portion 221211 is made of tin, the melting point of tin is 231.89° C.

[0096] The melting point of at least a portion of the coating portion 221211 is 200° C. to 250° C., which enables the battery cell 20 having the electrode piece 221 to have a wider range of applications and a lower risk of thermal runaway.

[0097] In some embodiments, the melting point of any region of the conductive layer 22121 is less than or equal to 300°C.

[0098] The conductive layer 22121 includes a coating portion 221211 and a pole ear portion 221212 , and the melting points of the coating portion 221211 and the pole ear portion 221212 are both lower than or lower than 300° C.

[0099] The conductive layer 22121 may be made of a material having a melting point less than or equal to 300° C. The materials of the coating portion 221211 and the tab portion 221212 may be the same or different.

[0100] Alternatively, the thickness of the conductive layer 22121 is set to be small enough so that the short-circuit region can be completely melted at a temperature of 300° C. or less, and the active material layer 2213 in the short-circuit region loses support and collapses.

[0101] The melting point of any area of ​​the conductive layer 22121 is less than or equal to 300°C, that is, the melting point of any area of ​​the conductive layer 22121 is low. When a short circuit occurs in any area inside the conductive layer 22121 battery cell 20, the conductive layer 22121 can be melted in advance at the short-circuit position to cause an internal short circuit in the battery cell 20, or after the short-circuit area is melted, the overcurrent capacity of a part of the conductive layer 22121 can be reduced, so that the conductive layer 22121 can be quickly melted, and the active material layer 2213 in the short-circuit area collapses, so that the positive and negative poles with the electrode 221 are disconnected, and then the battery cell 20 is quickly short-circuited. Therefore, the temperature rise inside the battery cell 20 can be effectively alleviated, thereby reducing the risk of thermal runaway of the battery cell 20 with the electrode 221 and improving the reliability of the battery cell 20.

[0102] In other embodiments, the conductive layer 22121 also includes a pole ear portion 221212, the pole ear portion 221212 and the coating portion 221211 are arranged along the width direction Y of the pole piece, the pole ear portion 221212 is not provided with an active material layer 2213, and the melting point of the coating portion 221211 is lower than the melting point of the pole ear portion 221212.

[0103] By selecting different materials for the coating portion 221211 and the pole ear portion 221212 , the melting point of the coating portion 221211 can be made lower than the melting point of the pole ear portion 221212 , that is, the melting point of the material forming the coating portion 221211 is lower than the melting point of the material forming the pole ear portion 221212 .

[0104] Of course, in other embodiments, the melting point of the coating portion 221211 may be made lower than the melting point of the tab portion 221212 by other means.

[0105] The melting point of the coating portion 221211 is lower than the melting point of the pole ear portion 221212, so that the coating portion 221211 is easier to melt than the pole ear portion 221212. When a short circuit occurs inside the battery cell 20 having the pole piece 221, the conductive layer 22121 corresponding to the short-circuit area can be melted, and the active material layer 2213 in the short-circuit area collapses, so that the positive and negative poles having the pole piece 221 are disconnected, which can effectively alleviate the internal temperature rise of the battery cell 20, thereby reducing the risk of thermal runaway of the battery cell 20 having the pole piece 221 and improving the reliability of the battery cell 20.

[0106] As shown in FIG8-FIG10 , in some embodiments, the current collector 2212 further includes an insulating layer 22122 , and a conductive layer 22121 is provided on at least one side of the insulating layer 22122 along the thickness direction of the insulating layer 22122 .

[0107] The conductive layer 22121 may be provided on only one side of the insulating layer 22122 or on both sides along the thickness direction X of the electrode. The active material layer 2213 is provided on the side of the conductive layer 22121 away from the insulating layer 22122 along the thickness direction X of the electrode.

[0108] The conductive layer 22121 can be adhered to the surface of the insulating layer 22122 located in the thickness direction X of the pole piece, or it can be arranged on one side of the insulating layer 22122 along the thickness direction X of the pole piece in other connection methods, such as welding, magnetron sputtering, vacuum evaporation, electrochemical plating, water plating and other methods or a combination of methods.

[0109] The material of the insulating layer 22122 includes but is not limited to polypropylene, polyethylene, and polyethylene terephthalate.

[0110] The current collector 2212 also includes an insulating layer 22122. The provision of the insulating layer 22122 helps to improve the strength of the current collector 2212. When the thickness of the current collector 2212 is constant, the provision of the insulating layer 22122 on the current collector 2212 reduces the thickness of the conductive layer 22121 of the current collector 2212. When the current collector 2212 is punctured, the length of the burr generated at the puncture site of the conductive layer 22121 of the current collector 2212 is also short. This reduces the risk of the burr piercing the separator 222 and causing an internal short circuit in the battery cell 20, thereby improving the reliability of the battery cell 20 equipped with the electrode 221.

[0111] Of course, the current collector 2212 may also include only the conductive layer 22121 (shown in FIG. 4 ).

[0112] In some embodiments, the melting point of at least a portion of the coating portion 221211 is lower than the melting point of the insulating layer 22122 .

[0113] The melting point of only a portion of the conductive layer 22121 may be lower than the melting point of the insulating layer 22122 , or the melting point of the entire conductive layer 22121 may be lower than the melting point of the insulating layer 22122 .

[0114] The melting point of at least a portion of the coating portion 221211 is lower than the melting point of the insulating layer 22122, so the conductive layer 22121 is more likely to melt relative to the insulating layer 22122. When a short circuit occurs locally in the battery cell 20 having the pole piece 221, when the conductive layer 22121 in the short-circuit area melts, the insulating layer 22122 may not melt, thereby reducing the risk of other electrochemical reactions occurring inside the battery cell 20 having the pole piece 221 due to the melting of the insulating layer 22122, thereby causing other problems that reduce reliability, and reducing the risk of the battery cell 20 having the pole piece 221 not being able to work normally due to the melting of the insulating layer 22122.

[0115] In some embodiments, the melting point of the insulating layer 22122 is 120° C. to 220° C.

[0116] For example, the melting point of the insulating layer 22122 may be 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, etc. For example, if the insulating layer 22122 is made of polyethylene, the melting point of the insulating layer 22122 is 130°C to 145°C. If the insulating layer 22122 is made of polychlorotrifluoroethylene, the melting point of the insulating layer 22122 is 213°C.

[0117] The melting point of the insulating layer 22122 is 120° C. to 220° C., which enables the battery cell 20 having the electrode piece 221 to have a higher operating temperature and helps to control the manufacturing cost of the battery cell 20 .

[0118] In some embodiments, the coating portion 221211 includes a first region having a melting point less than or equal to 300° C., and the melting point of the first region is lower than the melting point of the insulating layer 22122 .

[0119] The region of the coating portion 221211 having a melting point less than or equal to 300°C is defined as a first region. The first region is a portion of the coating portion 221211. It is understood that the melting point of the portion of the coating portion 221211 is not only less than or equal to 300°C but also less than the melting point of the insulating layer 22122. In other words, the melting point of the first region of the coating portion 221211 is not only less than or equal to 300°C but also less than the melting point of the insulating layer 22122.

[0120] The melting point of the first area of ​​the coating portion 221211 is less than or equal to 300°C, and the melting point of the first area is relatively low. When an internal short circuit occurs in the first area of ​​the battery cell 20 equipped with the pole piece 221, the first area melts due to the high temperature generated by the short circuit, thereby breaking the circuit. Since the melting point of the first area is lower than the melting point of the insulating layer 22122, the insulating layer 22122 will not melt when the first area melts, and the active material layer 2213 in other areas outside the first area will not collapse. The battery cell 20 equipped with the pole piece 221 can still work normally. The battery cell 20 equipped with the pole piece 221 has better reliability and can also reduce the risk of the battery cell 20 being scrapped due to internal short circuits.

[0121] As shown in FIG. 8 and FIG. 9 , in some embodiments, along the thickness direction X of the electrode piece, a conductive layer 22121 is provided on both sides of the insulating layer 22122 .

[0122] The active material layer 2213 may be provided on both sides of the two conductive layers 22121 facing away from the insulating layer 22122 , or the active material layer 2213 may be provided on the side of one of the two conductive layers 22121 facing away from the insulating layer 22122 .

[0123] Each conductive layer 22121 includes a coating portion 221211 and a pole lug portion 221212 . The pole lug 2211 of the pole piece 221 includes a portion where the insulating layer 22122 and the pole lug portion 221212 overlap, and the pole lug portions 221212 of the two conductive layers 22121 .

[0124] Conductive layers 22121 are provided on both sides of the insulating layer 22122 along the thickness direction X of the electrode, and active material layers 2213 can be provided on both sides of the current collector 2212 along the thickness direction X of the electrode, which is beneficial to improving the energy density of the battery cell 20 with the electrode 221.

[0125] In some embodiments, the conductive layer 22121 is a metal plating layer disposed on the surface of the insulating layer 22122 .

[0126] It can be understood that the conductive layer 22121 is a metal layer plated on the surface of the insulating layer 22122.

[0127] The conductive layer 22121 is a metal plating layer provided on the surface of the insulating layer 22122. It can be understood that the conductive layer 22121 is plated on the surface of the insulating layer 22122 for easy processing.

[0128] In some embodiments, the material of the insulating layer 22122 includes at least one of polyethylene terephthalate and polypropylene.

[0129] The melting point of polyethylene terephthalate is 250 to 255°C, and the melting point of polypropylene is 164 to 170°C.

[0130] Polyethylene terephthalate and polypropylene have excellent insulation properties, heat resistance, and dimensional stability. The pole piece 221 is manufactured using this current collector 2212, which improves the reliability of the battery cell 20 equipped with this pole piece 221. Polyethylene terephthalate and polypropylene are lightweight, which helps reduce the weight of the pole piece 221, and thus helps reduce the weight of the battery cell 20 manufactured using this pole piece 221.

[0131] In other embodiments, the insulating layer 22122 may also be made of other materials.

[0132] In some embodiments, the material of the conductive layer 22121 includes an alloy.

[0133] An alloy is a solid product with metallic properties obtained by melting a metal with one or more other metals or non-metals and then cooling and solidifying it. The melting point of an alloy is lower than the melting point of any of its component metals.

[0134] For example, the weight ratio of the components is as follows: 25%-32% lead, 12%-15% tin, 9%-15% zinc, 0%-4% antimony, and the remainder bismuth. The following preparation method is used: Each metal raw material with a purity of at least 99.9% is cut into small, rice- or mung-bean-sized pellets; the raw materials are weighed proportionally; and the alloy is then smelted. The heating furnace is switched on, and the elements are mixed and placed into the furnace for smelting. The furnace temperature is adjusted to 400-500°C. Once the elements reach 400-500°C, stir for 2-3 minutes. Once the melt has settled, use a spoon to remove any suspended impurities from the surface. The melt is then slowly poured into a clean container, taking care not to mix in any impurities from the bottom. This process is repeated 3-5 times, followed by casting into small pieces and cooling. The resulting alloy has a maximum melting temperature of 144°C and a minimum of 41.5°C.

[0135] The alloy has a lower melting point than any of the metals that make up the alloy. When an abnormal short circuit occurs inside the battery cell 20 having the electrode 221, the conductive layer 22121 in the abnormal short circuit area melts and the active material layer 2213 in the abnormal area collapses, disconnecting the positive and negative poles, thereby achieving internal short circuit in the battery cell 20 and improving the reliability of the battery cell 20.

[0136] In other embodiments, the alloy includes one or more of bismuth, lead, tin, cadmium, and zinc.

[0137] The alloy may be a solid product with metallic properties obtained by melting a mixture of one of bismuth, lead, tin, cadmium, and zinc with other metals or non-metals, cooling and solidifying. The alloy may also be a solid product with metallic properties obtained by melting a mixture of multiple of bismuth, lead, tin, cadmium, and zinc, cooling and solidifying. The alloy may also be a solid product with metallic properties obtained by melting a mixture of multiple of bismuth, lead, tin, cadmium, and zinc with other metals or non-metals, cooling and solidifying.

[0138] For example, the melting point of pure bismuth is 232°C, the melting point of pure lead is 328°C, the melting point of pure tin is 232°C, and the melting point of pure cadmium is 328°C. Bismuth, lead, tin, cadmium, and other metals or non-metals can be mixed to form an alloy with a melting point below 300°C. In some embodiments, at least a portion of the coating portion 221211 is made of a bismuth-tin alloy with 58% by weight of bismuth and 42% by weight of tin. The melting and casting process is as follows: the blended bismuth-tin alloy is placed in a melting pot and then heated to about 140°C (the temperature can be measured using a semiconductor point thermometer or an ordinary thermometer). After uniform melting, it can be cast. After casting, it can be cooled for about half an hour. Finally, the residual marks left during the casting of the casting are corrected to meet the requirements.

[0139] For example, the material of at least a portion of the coating portion 221211 can be an alloy formed by 50% by weight of bismuth, 27% by weight of lead, 13% by weight of tin, and 10% by weight of cadmium. The melting point of the alloy formed by 50% by weight of bismuth, 27% by weight of lead, 13% by weight of tin, and 10% by weight of cadmium is 70°C.

[0140] For example, the material of at least a portion of the coating portion 221211 can be an alloy formed by 52% by weight of bismuth, 40% by weight of lead, and 8% by weight of cadmium. The melting point of the alloy formed by 52% by weight of bismuth, 40% by weight of lead, and 8% by weight of cadmium is 92°C.

[0141] For example, 20% bismuth, 20% lead, and 60% other elements (such as mercury) can form an alloy with a melting point of 20°C.

[0142] Bismuth, lead, tin, and cadmium account for 45% by weight, 23% by weight, 8% by weight, and other elements (such as indium) account for 19% by weight, forming an alloy with a melting point of 47°C.

[0143] Bismuth, lead, and tin account for 49% by weight, 18% by weight, and other elements (such as indium) account for 21% by weight, forming an alloy with a melting point of 57°C.

[0144] By weight, 50% bismuth, 27% lead, 13% tin, and 10% cadmium can form an alloy with a melting point of 70°C.

[0145] By weight, 52% bismuth, 40% lead, and 8% cadmium can form an alloy with a melting point of 92°C.

[0146] By weight, 53% bismuth, 32% lead, and 15% tin can form an alloy with a melting point of 96°C.

[0147] By weight, 54% bismuth, 26% lead, and 20% cadmium can form an alloy with a melting point of 103°C.

[0148] Bismuth, which accounts for 55.5% by weight, and lead, which accounts for 44.5% by weight, can form an alloy with a melting point of 124°C.

[0149] An alloy with a melting point of 130°C can be formed by 56% bismuth, 40% tin, and 4% other elements (such as zinc) by weight.

[0150] By weight, 29% bismuth, 43% lead, and 28% tin can form an alloy with a melting point of 132°C.

[0151] Bismuth, which accounts for 57% by weight, and tin, which accounts for 43%, can form an alloy with a melting point of 138°C.

[0152] By weight, 32% lead, 50% tin, and 18% galvanneal can form an alloy with a melting point of 145°C.

[0153] 50% lead and 50% lead by weight can form an alloy with a melting point of 160°C.

[0154] By weight, 15% bismuth, 41% lead, and 44% tin can form an alloy with a melting point of 164°C.

[0155] Bismuth, which accounts for 33% by weight, and tin, which accounts for 67% by weight, can form an alloy with a melting point of 166°C.

[0156] By weight, 67% tin and 33% galvanneal can form an alloy with a melting point of 177°C.

[0157] 38% lead and 62% tin by weight can form an alloy with a melting point of 183°C.

[0158] 20% bismuth and 80% tin by weight can form an alloy with a melting point of 200°C.

[0159] It should be noted that the preparation method of the alloy can refer to the relevant technology and will not be described in detail in this application.

[0160] The proportions of bismuth, lead, tin, cadmium, and zinc in the alloy may vary depending on actual needs. Considering the electrochemical stability and ductility of bismuth, lead, tin, cadmium, and zinc, each of these metals may account for less than or equal to 10% by weight of the alloy. For example, in embodiments where the alloy includes bismuth, the weight proportion of bismuth may be less than or equal to 10%.

[0161] Introducing zinc into the conductive layer 22121 is also beneficial to reducing the surface density of the conductive layer 22121 , thereby facilitating improving the energy density of the battery cell 20 .

[0162] Bismuth, lead, tin, cadmium, and zinc are used to manufacture fusible alloys, which are beneficial to improving the reliability of the battery cell 20 having the electrode piece 221 .

[0163] In some embodiments, the conductive layer 22121 is made of an anti-oxidation material having conductive properties.

[0164] In embodiments where the conductive layer 22121 is made of an alloy, the anti-oxidation material may be a component of the alloy. Specifically, the conductive layer 22121 may be made of any conductive element with good anti-oxidation properties, such as nickel, copper, zinc, or selenium. For example, the conductive layer 22121 is a bismuth-tin alloy comprising 58% by weight of bismuth and 42% by weight of tin.

[0165] Of course, the antioxidant material can also be an antioxidant layer provided on the surface of the conductive material, the antioxidant layer having conductive properties, and the conductive material and the antioxidant layer together form the conductive layer 22121. The antioxidant layer can be formed on the surface of the conductive material by magnetron sputtering, vacuum evaporation, electrochemical plating, water plating, or a combination of methods.

[0166] Oxidation resistant materials include, but are not limited to, nickel.

[0167] The material of the conductive layer 22121 includes an anti-oxidation material with conductive properties, which improves the corrosion resistance of the conductive layer 22121.

[0168] In other embodiments, a passivation treatment process may be adopted on the surface of the conductive layer 22121 , and the surface of the conductive layer 22121 may be passivated by ozone, thereby improving the anti-oxidation and anti-corrosion properties of the conductive layer 22121 .

[0169] The embodiment of the present application further provides an electrode assembly 22 , which includes the electrode piece 221 provided in the above embodiment.

[0170] The electrode assembly 22 includes two electrodes 221 with opposite polarities. The electrode 221 provided in any of the above embodiments can be the positive electrode 221a or the negative electrode 221b of the electrode assembly 22. Alternatively, the two electrodes 221 with opposite polarities can be the electrode 221 provided in any of the above embodiments.

[0171] If at least a portion of the coating portion 221211 of the electrode piece 221 provided in any of the above embodiments has a low melting point, then when the electrode assembly 22 is short-circuited in the area with a lower melting point, this portion of the conductive layer 22121 can be melted in advance, thereby realizing the disconnection of the positive and negative poles of the electrode assembly 22, or after this portion of the area is melted, the overcurrent capacity of a portion of the conductive layer 22121 can be reduced, so that the conductive layer 22121 can be quickly melted, and then the positive and negative poles of the electrode assembly 22 can be quickly disconnected, thereby effectively alleviating the temperature rise, thereby reducing the risk of thermal runaway of the battery cell 20 equipped with the electrode assembly 22, and improving the reliability of the battery cell 20.

[0172] In some embodiments, the electrode assembly 22 includes two electrode pieces 221 provided in any of the above embodiments, and the two electrode pieces 221 have opposite polarities.

[0173] That is, the positive electrode sheet 221a and the negative electrode sheet 221b of the electrode assembly 22 both adopt the electrode sheet 221 provided by any of the above embodiments, which can further effectively alleviate the temperature rise, thereby reducing the risk of thermal runaway of the battery cell 20 equipped with the electrode assembly 22 and improving the reliability of the battery cell 20.

[0174] The embodiment of the present application further provides a battery cell 20 , which includes the electrode assembly 22 provided in the above embodiment.

[0175] When the electrode assembly 22 provided in the above embodiment is short-circuited, this part of the conductive layer 22121 can be melted in advance to realize the disconnection of the positive and negative poles of the electrode assembly 22, or the conductive layer 22121 is partially melted, which can reduce the overcurrent capacity of a part of the conductive layer 22121, so that the conductive layer 22121 can be quickly melted, and then the positive and negative poles of the electrode assembly 22 are quickly disconnected, thereby effectively alleviating the temperature rise, thereby reducing the risk of thermal runaway of the battery cell 20 equipped with the electrode assembly 22, and improving the reliability of the battery cell 20.

[0176] In some embodiments, the battery cell 20 further includes a transition piece electrically connected to the conductive layer 22121 , and the melting point of the transition piece is greater than the melting point of the conductive layer 22121 .

[0177] The adapter is used to electrically connect to the tab 2211 to lead out the electrode of the battery cell 20 , thereby facilitating the charging and discharging of the battery cell 20 .

[0178] The melting point of the conductive layer 22121 is lower than the melting point of the adapter, which makes the conductive layer 22121 easier to melt than the adapter. When a short circuit occurs inside the battery cell 20, the conductive layer 22121 corresponding to the short-circuit area can melt, and the active material layer 2213 corresponding to the short-circuit area collapses, disconnecting the positive and negative poles of the battery cell 20, thereby achieving internal short circuit of the battery cell 20, which can effectively alleviate the internal temperature rise of the battery cell 20, thereby reducing the risk of thermal runaway of the battery cell 20 and improving the reliability of the battery cell 20.

[0179] The embodiment of the present application further provides a battery 100 , which includes the battery cell 20 provided in the above embodiment.

[0180] The battery cell 20 provided in the above embodiment has good reliability, and the battery 100 including the battery cell 20 also has good reliability.

[0181] An embodiment of the present application further provides an electric device, which includes the battery 100 provided in the above embodiment.

[0182] The battery 100 provided in the above embodiment has good reliability, which is beneficial to improving the power reliability of the electrical equipment powered by the battery 100.

[0183] An embodiment of the present application provides a battery cell 20, which includes a housing 21 and an electrode assembly 22. The electrode assembly 22 includes two pole pieces 221 with opposite polarities. The pole pieces 221 include a current collector 2212 and an active material layer 2213. The current collector 2212 includes an insulating layer 22122 and two conductive layers 22121. Along the thickness direction X of the pole piece, the two conductive layers 22121 are respectively arranged on both sides of the insulating layer 22122. The conductive layer 22121 has a coating portion 221211, and the active material layer 2213 is arranged on the coating portion 221211. The melting point of at least a portion of the coating portion 221211 is less than or equal to 300°C. The conductive layer 22121 is made of an alloy.

[0184] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A pole piece, wherein: include: a current collector including a conductive layer; An active material layer, wherein the active material layer is disposed on at least one side of the conductive layer along the thickness direction of the electrode sheet; The conductive layer has a coating portion, the active material layer is disposed on the coating portion, and the melting point of at least a portion of the coating portion is less than or equal to 300°C.

2. The pole piece according to claim 1, wherein: The melting point of at least a portion of the coating portion is 200°C to 250°C.

3. The pole piece according to claim 1, wherein: The melting point of any region of the conductive layer is less than or equal to 300°C.

4. The pole piece according to claim 1, wherein: The conductive layer further includes a pole ear portion, the pole ear portion and the coating portion are arranged along the width direction of the pole piece, the pole ear portion is not provided with the active material layer, and the melting point of the coating portion is lower than the melting point of the pole ear portion.

5. The pole piece according to claim 1, wherein: The current collector further includes an insulating layer, and the conductive layer is disposed on at least one side of the insulating layer along a thickness direction of the insulating layer.

6. The pole piece according to claim 5, wherein: The melting point of at least a portion of the coating portion is lower than the melting point of the insulating layer.

7. The pole piece according to claim 5, wherein: The melting point of the insulating layer is 120°C to 220°C.

8. The pole piece according to claim 5, wherein: The conductive layer is disposed on both sides of the insulating layer along the thickness direction of the pole piece.

9. The pole piece according to claim 5, wherein: The conductive layer is a metal plating layer disposed on the surface of the insulating layer.

10. The pole piece according to claim 5, wherein: The material of the insulating layer includes at least one of polyethylene terephthalate and polypropylene.

11. The pole piece according to any one of claims 1 to 10, wherein: The material of the conductive layer includes alloy.

12. The pole piece according to claim 11, wherein: The alloy includes one or more of bismuth, lead, tin, cadmium and zinc.

13. The pole piece according to claim 1, wherein: The material of the conductive layer includes an anti-oxidation material with conductive properties.

14. An electrode assembly, wherein: Comprising a pole piece according to any one of claims 1-13.

15. The electrode assembly according to claim 14, wherein: The electrode assembly comprises two pole pieces according to any one of claims 1 to 13, and the two pole pieces have opposite polarities.

16. A battery cell, wherein: Comprising the electrode assembly according to claim 14 or 15.

17. The battery cell according to claim 16, wherein: The battery cell further includes a transition piece, the transition piece is electrically connected to the conductive layer, and the melting point of the transition piece is greater than the melting point of the conductive layer.

18. A battery, wherein: Comprising the battery cell according to claim 16 or 17.

19. An electrical device, wherein: Comprising the battery cell according to claim 16 or 17.

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