Pole piece, electrode assembly, battery monomer, battery and electric equipment

Abstract

The invention provides a pole piece, an electrode assembly, a battery monomer, a battery and electric equipment, the pole piece comprises a current collector and an active substance layer, the current collector comprises a conductive layer, the active substance layer is arranged on at least one side of the conductive layer along the thickness direction of the pole piece, the conductive layer is provided with a coating part, the active substance layer is arranged on the coating part, and the active substance layer is arranged on the coating part. At least a portion of the coating portion has a melting point of 300 DEG C or less. The melting point of at least one part of the area of the conductive layer is low, so that the part of the conductive layer can be fused when the part of the area in the single battery is short-circuited so as to enable the interior of the single battery to be disconnected, or after the part of the area is fused, the overcurrent capacity of one part of the conductive layer can be reduced, so that the conductive layer can be fused quickly; the active material layer in the short-circuit region collapses, so that the positive electrode and the negative electrode with the pole piece are disconnected, the temperature rise in the battery monomer can be effectively relieved, the risk of thermal runaway of the battery monomer with the pole piece is reduced, and the reliability of the battery monomer is improved.

Description

Technical Field

[0001] 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

[0002] Due to its outstanding advantages such as high energy density and good cycle performance, storage batteries have become the mainstream product of secondary batteries and are widely used in portable appliances, power vehicles, mobile phones, spacecraft and other fields. However, the reliability of batteries is one of the main concerns of users and one of the main factors restricting the development of batteries. Therefore, how to improve the reliability of batteries has become an urgent problem to be solved in the battery field. Summary of the invention

[0003] 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.

[0004] In a first aspect, an embodiment of the present application provides a pole piece, the 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 the melting point of at least a portion of the coating portion is less than or equal to 300°C.

[0005] In the above technical solution, the melting point of at least a part of the coating part 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 part of the coating part is low. Then, when a short circuit occurs in this part of the battery cell, this part of the conductive layer can be melted off in advance to cause internal short circuit of the battery cell, or after this part of the area is melted off, the current carrying capacity of a part of the conductive layer can be reduced, so that the coating part can be melted off quickly, and the active material layer in the short-circuit area collapses, so that the positive and negative electrodes with the pole piece 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 pole piece and improving the reliability of the battery cell.

[0006] 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.

[0007] In the above technical solution, the melting point of at least a part of the coating portion is 200° C. to 250° C., which can make the battery cell with the pole piece more applicable in a wider range and reduce the risk of thermal runaway.

[0008] 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.

[0009] In the above technical scheme, 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 break the circuit inside the battery cell, or the short-circuit area can be reduced after the short-circuit area is melted, so that the current carrying 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 electrodes with the pole piece 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 pole piece and improving the reliability of the battery cell.

[0010] In some embodiments of the first aspect of the present application, the conductive layer also 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.

[0011] 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 a battery cell equipped with the pole piece, the conductive layer corresponding to the short-circuit area can melt, and the active material layer in the short-circuit area collapses, so that the positive and negative electrodes equipped with the pole piece are disconnected, which can effectively alleviate the temperature rise inside 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.

[0012] In some embodiments of the first aspect of the present application, 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.

[0013] In the above technical solution, the current collector also includes an insulating layer, and the provision of the insulating layer is conducive to improving the strength of the current collector. When the thickness of the current collector is constant, the current collector is provided with an insulating layer, and the thickness of the conductive layer of the current collector is small. When the current collector is pierced, the length of the burr generated by the conductive layer of the current collector at the piercing position is also small, and the risk of the burr piercing the isolation membrane and causing an internal short circuit in the battery cell is low, which is conducive to improving the reliability of the battery cell equipped with the pole piece.

[0014] 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.

[0015] 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 easier to melt than the insulating layer. When a short circuit occurs locally inside a 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.

[0016] In some embodiments of the first aspect of the present application, the melting point of the insulating layer is 120°C to 220°C.

[0017] 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 pole piece can have a higher operating temperature and is conducive to controlling the manufacturing cost of the battery cell.

[0018] 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.

[0019] 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 improve the energy density of the battery cell with the pole piece.

[0020] In some embodiments of the first aspect of the present application, the conductive layer is a metal plating layer disposed on the surface of the insulating layer.

[0021] In the above technical solution, the conductive layer is a metal plating layer arranged 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.

[0022] In some embodiments of the first aspect of the present application, the material of the insulating layer includes at least one of polyethylene terephthalate and polypropylene.

[0023] In the above technical solution, polyethylene terephthalate and polypropylene have good insulation performance, heat resistance, dimensional stability, etc. The pole piece is manufactured and formed using the current collector, so that the battery monomer with the pole piece has good reliability. Polyethylene terephthalate and polypropylene are light in weight, which is conducive to reducing the weight of the pole piece, and thus is conducive to reducing the weight of the battery monomer manufactured and formed using the pole piece.

[0024] In some embodiments of the first aspect of the present application, the material of the conductive layer includes an alloy.

[0025] In the above technical solution, the alloy has a lower melting point than any metal constituting the alloy. When an abnormal short circuit occurs inside a battery cell equipped with the pole piece, the conductive layer in the abnormal short circuit area melts and the active material layer in the abnormal area collapses, so that the positive and negative poles are disconnected, thereby achieving internal short circuit in the battery cell and improving the reliability of the battery cell.

[0026] In some embodiments of the first aspect of the present application, the alloy includes one or more of bismuth, lead, tin, cadmium, and zinc.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] In the above technical scheme, if at least a part of the coating portion of the electrode piece 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 low melting point, this part of the conductive layer can be melted off in advance, thereby realizing the disconnection of the positive and negative poles of the electrode assembly, or after this part of the area is melted off, the current carrying capacity of a part of the conductive layer can be reduced, so that the conductive layer can be melted off quickly, 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.

[0032] 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.

[0033] 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.

[0034] In the above technical scheme, 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 current carrying 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.

[0035] 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 a melting point of the transition piece is greater than a melting point of the conductive layer.

[0036] In the above technical solution, the melting point of the conductive layer is lower than the melting point of the adapter, so that the conductive layer is 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.

[0037] In a third aspect, an embodiment of the present application further provides a battery, comprising a battery cell provided in any embodiment of the third aspect.

[0038] In the above technical solution, the battery cell provided in any embodiment of the third aspect has good reliability, and the battery having the battery cell also has good reliability.

[0039] In a fourth aspect, an embodiment of the present application further provides an electrical device, comprising a battery provided in any embodiment of the fourth aspect.

[0040] In the above technical solution, the battery provided in the fourth aspect embodiment has good reliability, which is beneficial to improving the power reliability of electrical equipment powered by the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. 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 related drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0043] Figure 2 An exploded view of a battery provided for some embodiments of the present application;

[0044] Figure 3 A schematic diagram of the structure of a battery provided in some embodiments of the present application;

[0045] Figure 4 A schematic diagram of the structure of a pole piece provided in some embodiments of the present application;

[0046] Figure 5 A schematic diagram of the structure of pole pieces provided in other embodiments of the present application;

[0047] Figure 6 A schematic diagram of a sharp object conducting two pole pieces with opposite polarities provided in some embodiments of the present application;

[0048] Figure 7 Schematic diagram of a sharp object conducting two pole pieces with opposite polarities provided in other embodiments of the present application;

[0049] Figure 8 A schematic diagram of the structure of a pole piece provided in some other embodiments of the present application;

[0050] Fig. 9 A schematic diagram of the structure of a pole piece provided in some further embodiments of the present application;

[0051] Fig.10 This is a schematic diagram of the structure of pole pieces provided in some further embodiments of the present application.

[0052] 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 film; 200-controller; 300-motor; X-thickness direction of pole piece; Y-width direction of pole piece; 2000-sharp object. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0054] 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 which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0055] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0056] 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, further definition and explanation thereof is not required in subsequent drawings.

[0057] At present, from the perspective of market development, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.

[0058] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a battery module or a battery pack. The battery generally includes a box for encapsulating one or more battery cells. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

[0059] In the present 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 the present application do not limit this. Battery cells may be cylindrical, flat, rectangular or other shapes, etc., and the embodiments of the present application do not limit this. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells and soft-pack battery cells, and the embodiments of the present application do not limit this.

[0060] The battery cell includes a housing and an electrode assembly, and the electrode assembly is contained in the housing. The electrode assembly consists of a separator and two pole pieces with opposite polarities. The two pole pieces with opposite polarities are the positive pole piece and the negative pole piece. The battery cell mainly works by the movement of metal ions between the positive pole piece and the negative pole piece. The pole piece includes a current collector and an active material layer, and the active material layer is coated on the surface of the current collector.

[0061] During the battery cell cycle, the battery cell may short-circuit due to the 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, and 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.

[0062] Battery cell short circuits are divided into external short circuits and internal short circuits. External short circuits generally refer to short circuits caused by direct contact between the positive and negative electrodes. External short circuits can generally be solved by setting a fuse on the adapter connected to the positive and / or negative ears. When the current flowing through the adapter exceeds the overcurrent capacity of the fuse, the fuse will melt, disconnecting the positive and negative electrodes of the battery cell, thereby breaking the circuit to avoid continuous heat release from the battery cell. After the external circuit is broken, the battery cell is generally scrapped.

[0063] Internal short circuit refers to when a battery cell is punctured by a sharp object or is hit or squeezed, causing a short circuit in the area inside the battery that is affected by external objects. An internal short circuit is a local short circuit, and only the temperature of the local area continues to rise. If the internal short circuit is not achieved in time, the temperature of the local area will continue to rise and gradually spread to the entire battery cell, which will also cause problems such as burning electrical appliances, causing fires or even explosions, causing serious property and life losses, and the reliability of the battery cell will deteriorate. However, the fuse designed to achieve external short circuit cannot achieve internal short circuit during internal short circuit.

[0064] 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, the active material layer is arranged on at least one side of the conductive layer. The conductive layer has a coating portion, and the active material layer is arranged on the coating portion. The melting point of at least a portion of the coating portion is less than or equal to 300°C.

[0065] 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 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 off in advance to cause internal short circuit in the battery cell, or after this portion of the region is melted off, the current carrying capacity of a portion of the conductive layer can be reduced, so that the conductive layer can be melted off quickly, and the active material layer in the short-circuit area collapses, so that the positive and negative electrodes with the pole piece are disconnected, thereby causing rapid internal short circuit in the battery cell. 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 pole piece and improving the reliability of the battery cell.

[0066] The current collector disclosed in the embodiment of the present application can be used to manufacture pole pieces and battery cells. The battery cells with the pole pieces provided in the embodiment of the present application can be used in, but not limited to, electrical equipment such as vehicles, ships or aircraft. It can be used in a power supply system composed of battery cells and batteries made of the pole pieces disclosed in the present application, which is conducive to alleviating the reliability problems of the battery cells caused by internal short circuits and improving the reliability of the battery cells and batteries.

[0067] The embodiment of the present application provides an electric device using a battery as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, a spacecraft, etc.

[0068] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may 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 may be provided at the bottom, head or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, and 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.

[0069] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve 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.

[0070] Please refer to Figure 2 , Figure 2 An exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 includes a box 10 and a battery cell 20, and the battery cell 20 is contained in the box 10. Among them, the box 10 is used to provide a storage space for the battery cell 20, and the box 10 can adopt a variety of structures. In some embodiments, the box 10 may include a first part 11 and a second part 12, the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define a storage space for accommodating the battery cell 20. The second part 12 may be a hollow structure with one end open, the first part 11 may be a plate-like structure, and the first part 11 covers the open side of the second part 12, so that the first part 11 and the second part 12 jointly define a storage space; the first part 11 and the second part 12 may also be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12. Of course, the box 10 formed by the first part 11 and the second part 12 may be in a variety of shapes, such as a cylinder, a cuboid, etc.

[0071] 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 mixed connection. A mixed connection means that the multiple battery cells 20 are both connected in series and in parallel. The multiple battery cells 20 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in a mixed connection, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 10. The battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 20.

[0072] Each battery cell 20 may be a secondary battery or a primary battery, or 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.

[0073] Please refer to Figure 3 , Figure 3 The schematic diagram of the exploded structure of the battery cell 20 provided in some embodiments of the present application. The battery cell 20 refers to the smallest unit constituting the battery 100. Figure 3 The battery cell 20 includes a housing 21 , an electrode assembly 22 and other functional components. The electrode assembly 22 is accommodated in the housing 21 .

[0074] The housing 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 and 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 the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 211 may be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating component may be provided on the inner side of the end cap 211, and the insulating component may be used to isolate the electrical connection components in the housing 212 from the end cap 211 to reduce the risk of short circuit. Exemplarily, the insulating component may be plastic, rubber, etc.

[0075] The shell 212 is a component used to cooperate with the end cap 211 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 22, the electrolyte and other components. The shell 212 and the end cap 211 can be independent components, and an opening can be set on the shell 212, and the internal environment of the battery cell 20 is formed by covering the opening with the end cap 211 at the opening. Without limitation, the end cap 211 and the shell 212 can also be integrated. Specifically, the end cap 211 and the shell 212 can form a common connection surface before other components are put into the shell, and when it is necessary to encapsulate the interior of the shell 212, the end cap 211 covers the shell 212. The shell 212 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 212 can be determined according to the specific shape and size of the electrode assembly 22. The material of the shell 212 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0076] The electrode assembly 22 is a component in the battery cell 20 where electrochemical reactions occur. The housing 212 may contain one or more electrode assemblies 22. The electrode assembly 22 is mainly formed by winding or stacking two pole pieces 221 with opposite polarities, and a separator 222 ( Figure 5 , Figure 6 The material of the isolation film 222 may be PP (polypropylene) or PE (polyethylene).

[0077] The parts of the two pole pieces 221 with opposite polarity and having active materials constitute the main body of the electrode assembly 22, and the parts of the two pole pieces 221 with opposite polarity and not having active materials each constitute a pole ear 2211, that is, the parts of the two pole pieces 221 with opposite polarity and not having active materials respectively form a positive pole ear and a negative pole ear. The positive pole ear and the negative pole ear can be located at one end of the main body or at both ends of the main body respectively. During the charge and discharge process of the battery 100, the positive active material and the negative active material react with the electrolyte, and the pole ear 2211 connects the electrode terminal 213 to form a current loop.

[0078] like Figure 4 , Figure 5 As shown, in some embodiments, the pole piece 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 pole piece, 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.

[0079] 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 .

[0080] The material of the active material layer 2213 is different according to the polarity of the electrode 221. For example, when the electrode 221 is a positive electrode 221a, the active material layer 2213 can 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 can be carbon or silicon.

[0081] Along the thickness direction X of the pole piece, the active material layer 2213 is arranged 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 arranged 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 be electrically connected to the adapter (not shown in the figure) to lead out the electrode.

[0082] Since the active material layer 2213 is disposed on the coating portion 221211, the region where the conductive layer 22121 overlaps with the active material layer 2213 along the thickness direction X of the electrode 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 be a region where the melting point is less than or equal to 300°C. Figure 5 As shown, Figure 5 The melting point of the A1 region is less than or equal to 300°C, and the melting points of other regions of the coating portion 221211 except the A1 region are greater than 300°C. The coating portion 221211 may also have a melting point of less than or equal to 300°C in all regions. Figure 4 The case where the melting point of the entire area of ​​the coating portion 221211 is less than or equal to 300° C. is shown in FIG.

[0083] 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.

[0084] In the embodiment where the melting point of a part of the coating portion 221211 is less than or equal to 300°C, the material of the part can be selected to have a melting point less than or equal to 300°C, and the material of the other parts of the coating portion 221211 can be selected to have a melting point greater than 300°C. Alternatively, the thickness of the part is set to be smaller than the thickness of the other parts of the coating portion 221211, so that the part with a smaller thickness can be completely melted at a temperature less than or equal to 300°C, and the active material layer 2213 coated on the part with a smaller thickness loses support and collapses. The material of the coating portion 221211 can be pure metal, and the material of the coating portion 221211 can also be an alloy.

[0085] In the embodiment where the melting point of the entire coating portion 221211 is less than or equal to 300° C., the material of the entire coating portion 221211 can be selected to have a melting point less than or equal to 300° C. Alternatively, the thickness of the coating portion 221211 is set to be small enough so that the short-circuit region can be completely melted at a temperature less than or equal to 300° C., and the active material layer 2213 coated in the region with a smaller thickness loses support and collapses.

[0086] Of course, in other embodiments, the melting point of at least a portion of the coating portion 221211 can be less than or equal to 300° C. by other means.

[0087] The thickness described in this application refers to the dimension of the corresponding structure in the thickness direction X of the pole piece.

[0088] The melting point of the coating portion 221211 is a temperature at which the conductive layer 22121 changes (melts) from a solid state to a molten state.

[0089] like Figure 6 , Figure 7 As shown, when the battery cell 20 is punctured by a sharp object 2000, the sharp object 2000 punctures the pole piece 221 with opposite polarity, and the two pole pieces 221 with opposite polarity are short-circuited through the sharp object 2000, and the battery cell 20 forms an internal short circuit in the punctured area, which is also a local internal short circuit. Or in other cases, the battery cell 20 is collided or squeezed, resulting in the contact of the two pole pieces 221 with opposite polarity of the battery cell 20, and the two pole pieces 221 with opposite polarity contact and short circuit, that is, the internal short circuit of the battery cell 20 is formed 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 current 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 open.

[0090] 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. 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 break the circuit inside the battery cell 20, or after this portion of the region is melted, the current carrying capacity of a portion of the conductive layer 22121 can be reduced, so that the coating portion 22121 can be melted quickly, and the active material layer 2213 in the short-circuit area collapses, so that the positive and negative electrodes having the pole piece 221 are disconnected, and then the battery cell 20 is quickly broken. 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 having 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 electrodes with the pole piece 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.

[0091] In some embodiments, the melting point of at least a portion of the coating portion 221211 is 200°C to 250°C.

[0092] 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.

[0093] 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 pole piece 221 to have a wider range of applications and a lower risk of thermal runaway.

[0094] In some embodiments, the melting point of any region of the conductive layer 22121 is less than or equal to 300°C.

[0095] 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 less than or less than 300° C.

[0096] The material of the conductive layer 22121 may be selected from materials with a melting point less than or equal to 300° C. The materials of the coating portion 221211 and the lug portion 221212 may be the same or different.

[0097] 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 less than or equal to 300° C., and the active material layer 2213 in the short-circuit region loses support and collapses.

[0098] 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 battery cell 20 of the conductive layer 22121, 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 current carrying 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 electrodes 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.

[0099] 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.

[0100] By selecting different materials for the coating portion 221211 and the pole ear portion 221212 , it is possible to achieve that the melting point of the coating portion 221211 is 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 .

[0101] Of course, in other embodiments, the melting point of the coating portion 221211 can be made lower than the melting point of the pole ear portion 221212 by other means.

[0102] 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 electrodes 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.

[0103] like Figure 8-Figure 10As shown, in some embodiments, the current collector 2212 further includes an insulating layer 22122 , and a conductive layer 22121 is disposed on at least one side of the insulating layer 22122 along a thickness direction of the insulating layer 22122 .

[0104] Along the thickness direction X of the electrode piece, the insulating layer 22122 may be provided with the conductive layer 22121 on only one side or on both sides. 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 piece.

[0105] The conductive layer 22121 can be bonded 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.

[0106] The material of the insulating layer 22122 includes but is not limited to polypropylene, polyethylene, and polyethylene terephthalate.

[0107] The current collector 2212 also includes an insulating layer 22122, and the provision of the insulating layer 22122 is conducive to improving the strength of the current collector 2212. When the thickness of the current collector 2212 is constant, the current collector 2212 is provided with the insulating layer 22122, and the thickness of the conductive layer 22121 of the current collector 2212 is small. When the current collector 2212 is pierced, the length of the burr generated at the piercing position of the conductive layer 22121 of the current collector 2212 is also small, and the risk of the burr piercing the isolation film 222 and causing an internal short circuit of the battery cell 20 is low, which is conducive to improving the reliability of the battery cell 20 with the pole piece 221.

[0108] Of course, the current collector 2212 may also include only the conductive layer 22121 ( Figure 4 ).

[0109] 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 .

[0110] Only a portion of the conductive layer 22121 may have a melting point lower than the melting point of the insulating layer 22122 , or the entire conductive layer 22121 may have a melting point lower than the melting point of the insulating layer 22122 .

[0111] If the melting point of at least a portion of the coating portion 221211 is lower than the melting point of the insulating layer 22122, the conductive layer 22121 is more likely to melt than the insulating layer 22122. When a short circuit occurs locally in a battery cell 20 having the pole piece 221, the insulating layer 22122 may not melt when the conductive layer 22121 in the short-circuit area melts, 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 operate normally due to the melting of the insulating layer 22122.

[0112] In some embodiments, the melting point of the insulating layer 22122 is 120°C to 220°C.

[0113] 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, when the insulating layer 22122 is made of polyethylene, the melting point of the insulating layer 22122 is 130°C to 145°C. When the insulating layer 22122 is made of polychlorotrifluoroethylene, the melting point of the insulating layer 22122 is 213°C.

[0114] The melting point of the insulating layer 22122 is 120° C. to 220° C., so that the battery cell 20 having the pole piece 221 can have a higher operating temperature and is beneficial to controlling the manufacturing cost of the battery cell 20 .

[0115] 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 .

[0116] The area where the melting point of the coating portion 221211 is less than or equal to 300°C is defined as the first area. The first area is a portion of the coating portion 221211. It can be 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 the melting point of the portion is lower than the melting point of the insulating layer 22122. In other words, the melting point of the first area of ​​the coating portion 221211 is not only less than or equal to 300°C, but also the melting point of the first area is lower than the melting point of the insulating layer 22122.

[0117] 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, and 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 good reliability and can also reduce the risk of the battery cell 20 being scrapped due to internal short circuit.

[0118] like Figure 8 , Fig. 9 As shown, in some embodiments, along the thickness direction X of the pole piece, a conductive layer 22121 is provided on both sides of the insulating layer 22122 .

[0119] 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 .

[0120] Each conductive layer 22121 includes a coating portion 221211 and a pole ear portion 221212 . The pole ear 2211 of the pole piece 221 includes a portion where the insulating layer 22122 and the pole ear portion 221212 overlap, and the pole ear portions 221212 of the two conductive layers 22121 .

[0121] Conductive layers 22121 are provided on both sides of the insulating layer 22122 along the thickness direction X of the pole piece, and active material layers 2213 can be provided on both sides of the current collector 2212 along the thickness direction X of the pole piece, which is beneficial to improving the energy density of the battery cell 20 with the pole piece 221 .

[0122] In some embodiments, the conductive layer 22121 is a metal plating layer disposed on the surface of the insulating layer 22122 .

[0123] It can be understood that the conductive layer 22121 is a metal layer plated on the surface of the insulating layer 22122 .

[0124] The conductive layer 22121 is a metal-plated layer disposed 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.

[0125] In some embodiments, the material of the insulating layer 22122 includes at least one of polyethylene terephthalate and polypropylene.

[0126] The melting point of polyethylene terephthalate is 250 to 255°C, and the melting point of polypropylene is 164 to 170°C.

[0127] Polyethylene terephthalate and polypropylene have good insulation performance, heat resistance, dimensional stability, etc. The pole piece 221 is manufactured and formed using the current collector 2212, so that the reliability of the battery cell 20 with the pole piece 221 is good. Polyethylene terephthalate and polypropylene are light in weight, which is conducive to reducing the weight of the pole piece 221, thereby helping to reduce the weight of the battery cell 20 manufactured and formed using the pole piece 221.

[0128] In other embodiments, the insulating layer 22122 may also be made of other materials.

[0129] In some embodiments, the material of the conductive layer 22121 includes an alloy.

[0130] Alloy refers to a solid product with metallic properties obtained by mixing and melting a metal with another or several metals or non-metals and cooling and solidifying. The melting point of an alloy is lower than the melting point of any of its components.

[0131] Exemplarily, the weight ratio of the component content is as follows: lead 25% to 32%, tin 12%-15% 9% to 15%, zinc 0%-4%, antimony 0%-5%, bismuth balance. The following preparation method is adopted: cut each metal raw material with a purity of more than 99.9% into rice or mung bean-shaped small particles; weigh each component raw material in proportion; then smelt the alloy, turn on the power switch of the heating smelting furnace, put the elements into the smelting furnace after mixing them in proportion, adjust the temperature of the smelting furnace to 400-500℃, when the elements are heated to 400-500℃, stir for 2-3 minutes, wait for the melt to be still, use a spoon to clean the suspended impurities from the surface, and then slowly pour the melt into another clean container, be careful not to mix the bottom impurities, so as to clean the bottom impurities; repeat this 3-5 times of stirring and cleaning, and cast into small pieces for cooling. The maximum melting temperature of the prepared alloy is 144℃, and the minimum is 41.5℃.

[0132] 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 pole piece 221, the conductive layer 22121 in the abnormal short circuit area melts and the active material layer 2213 in the abnormal area collapses, thereby 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.

[0133] In other embodiments, the alloy includes one or more of bismuth, lead, tin, cadmium, and zinc.

[0134] The alloy may be a solid product with metallic properties obtained by melting one of bismuth, lead, tin, cadmium and zinc and other metals or non-metals, cooling and solidifying. The alloy may also be a solid product with metallic properties obtained by melting multiple of bismuth, lead, tin, cadmium and zinc and cooling and solidifying. The alloy may also be a solid product with metallic properties obtained by melting multiple of bismuth, lead, tin, cadmium and zinc and other metals or non-metals, cooling and solidifying.

[0135] Exemplarily, 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 material of the coating portion 221211 is a bismuth-tin alloy in which bismuth accounts for 58% by weight and tin accounts for 42% by weight. The melting and casting process is as follows: the blended bismuth-tin alloy material is placed in a melting pot, and then heated to about 140°C (temperature measurement can be performed using a semiconductor point thermometer or an ordinary thermometer). After melting evenly, the mold can be cast. After casting, cool it for about half an hour. Finally, correct the traces left when the casting is cast to meet the requirements.

[0136] 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.

[0137] 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.

[0138] For example, 20% bismuth, 20% lead, and 60% other elements (such as mercury) can form an alloy with a melting point of 20°C.

[0139] Bismuth (45%), lead (23%), tin (8%), cadmium (5%), and others (such as indium) (19%) by weight can form an alloy with a melting point of 47°C.

[0140] Bismuth (49%), lead (18%), tin (12%), and others (such as indium) (21%) by weight can form an alloy with a melting point of 57°C.

[0141] 50% bismuth, 27% lead, 13% tin and 10% cadmium by weight can form an alloy with a melting point of 70°C.

[0142] 52% bismuth, 40% lead and 8% cadmium by weight can form an alloy with a melting point of 92°C.

[0143] 53% bismuth, 32% lead and 15% tin by weight can form an alloy with a melting point of 96°C.

[0144] 54% bismuth, 26% lead and 20% cadmium by weight can form an alloy with a melting point of 103°C.

[0145] 55.5% bismuth and 44.5% lead by weight can form an alloy with a melting point of 124°C.

[0146] Bismuth accounting for 56% by weight, tin accounting for 40% by weight, and others (such as zinc) accounting for 4% by weight can form an alloy with a melting point of 130°C.

[0147] 29% bismuth, 43% lead and 28% tin by weight can form an alloy with a melting point of 132°C.

[0148] 57% bismuth and 43% tin by weight can form an alloy with a melting point of 138°C.

[0149] 32% lead, 50% tin and 18% galvanneal by weight can form an alloy with a melting point of 145°C.

[0150] 50% lead and 50% lead by weight can form an alloy with a melting point of 160°C.

[0151] 15% bismuth, 41% lead and 44% tin by weight can form an alloy with a melting point of 164°C.

[0152] 33% bismuth and 67% tin by weight can form an alloy with a melting point of 166°C.

[0153] By weight, 67% tin and 33% galvanneal can form an alloy with a melting point of 177°C.

[0154] 38% lead and 62% tin by weight can form an alloy with a melting point of 183°C.

[0155] 20% bismuth and 80% tin by weight can form an alloy with a melting point of 200°C.

[0156] 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.

[0157] According to actual needs, the proportions of bismuth, lead, tin, cadmium, and zinc in the alloy are different. Considering the electrochemical stability and ductility of bismuth, lead, tin, cadmium, and zinc, the weight proportion of each of these metals in the alloy can be less than or equal to 10%. For example, in an embodiment where the alloy includes bismuth, the weight proportion of bismuth can be less than or equal to 10%.

[0158] 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 .

[0159] 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 pole piece 221 .

[0160] In some embodiments, the material of the conductive layer 22121 includes an anti-oxidation material having conductive properties.

[0161] In the embodiment where the material of the conductive layer 22121 is an alloy, the anti-oxidation material can be used as a component element of the alloy, that is, the material of the conductive layer 22121 includes any conductive element with good anti-oxidation performance, such as nickel, copper, zinc, selenium, etc. Exemplarily, the conductive layer 22121 is a bismuth-tin alloy with 58% by weight of bismuth and 42% by weight of tin.

[0162] Of course, the anti-oxidation material can also be an anti-oxidation layer disposed on the surface of the conductive material, the anti-oxidation layer has conductive properties, and the conductive material and the anti-oxidation layer together form the conductive layer 22121. The anti-oxidation 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.

[0163] Oxidation resistant materials include, but are not limited to, nickel.

[0164] 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.

[0165] 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 .

[0166] The embodiment of the present application further provides an electrode assembly 22, and the electrode assembly 22 includes the electrode piece 221 provided in the above embodiment.

[0167] The electrode assembly 22 includes two pole pieces 221 with opposite polarities. The pole piece 221 provided in any of the above embodiments may be a positive pole piece 221a or a negative pole piece 221b as the electrode assembly 22. Alternatively, the two pole pieces 221 with opposite polarities may be the pole piece 221 provided in any of the above embodiments.

[0168] If at least a portion of the coating portion 221211 of the pole piece 221 provided in any of the above embodiments has a low melting point, then when the electrode assembly 22 is short-circuited in an area with a low melting point, this portion of the conductive layer 22121 can be melted off 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 off, the current carrying capacity of a portion of the conductive layer 22121 can be reduced, so that the conductive layer 22121 can be melted off quickly, 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.

[0169] In some embodiments, the electrode assembly 22 includes two pole pieces 221 provided in any of the above embodiments, and the two pole pieces 221 have opposite polarities.

[0170] 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.

[0171] The embodiment of the present application further provides a battery cell 20 , and the battery cell 20 includes the electrode assembly 22 provided in the above embodiment.

[0172] When the electrode assembly 22 provided in the above embodiment is short-circuited, this part of the conductive layer 22121 can be blown in advance to realize the disconnection of the positive and negative poles of the electrode assembly 22, or the conductive layer 22121 is partially blown, which can reduce the current carrying capacity of a part of the conductive layer 22121, so that the conductive layer 22121 can be quickly blown, and then the positive and negative poles of the electrode assembly 22 are quickly disconnected. Therefore, the temperature rise can be effectively alleviated, 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.

[0173] In some embodiments, the battery cell 20 further includes a transition piece, which is 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 .

[0174] 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 .

[0175] 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 in the battery cell 20, which can effectively alleviate the temperature rise inside 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.

[0176] The embodiment of the present application further provides a battery 100 , and the battery 100 includes the battery cell 20 provided in the above embodiment.

[0177] 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.

[0178] The embodiment of the present application further provides an electric device, and the electric device includes the battery 100 provided in the above embodiment.

[0179] 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 .

[0180] The 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, and the pole piece 221 includes 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 alloy.

[0181] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A pole piece, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: The melting point of the insulating layer is 120°C to 220°C.

8. The pole piece according to claim 5, characterized in that: 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, characterized in that: The conductive layer is a metal plating layer disposed on the surface of the insulating layer.

10. The pole piece according to claim 5, characterized in that: 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, characterized in that: The material of the conductive layer includes alloy.

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

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

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

15. The electrode assembly according to claim 14, characterized in that: 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, characterized in that: Comprising the electrode assembly according to claim 14 or 15.

17. The battery cell according to claim 16, characterized in that: 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, characterized in that: Comprising the battery cell according to claim 16 or 17.

19. An electrical equipment, characterized in that: Comprising the battery cell according to claim 16 or 17.

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