Electrode assembly, battery cell, battery, and manufacturing method and equipment of the electrode assembly

Abstract

An embodiment of the present application provides an electrode assembly, a battery cell, a battery, and a manufacturing method and device for the electrode assembly. The electrode assembly includes a positive electrode sheet and a negative electrode sheet, and the positive electrode sheet and the negative electrode sheet are wound or folded to form a bending region; the positive electrode sheet includes a plurality of bending portions located in the bending region, and each bending portion includes a positive current collector layer and a positive active material layer, and the positive active material layer is disposed on at least one surface of the positive current collector layer in the thickness direction of the positive electrode sheet; wherein, a barrier layer is provided between the positive current collector layer and the positive active material layer, and the barrier layer is used to block the electron transfer between the positive current collector layer and the positive active material layer, thereby weakening or preventing the delithiation reaction of the positive active material layer in the bending portion, and the positive active material layer does not intercalate / deintercalate lithium ions or the number of intercalated / deintercalated lithium ions is small. Therefore, the occurrence probability of lithium deposition can be reduced or the phenomenon of lithium deposition can be avoided, thereby improving battery safety.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular, to an electrode assembly, a battery cell, a battery, and a manufacturing method and device for the electrode assembly. Background Art

[0002] With the rapid development of smart phones, tablet computers, electric vehicles, etc., the application of lithium-ion batteries has become increasingly widespread, and thus higher requirements are also put forward for lithium batteries. While paying attention to the safety performance of the battery, people also require the lithium battery to have better electrical performance. Lithium plating is one of the main factors affecting the electrical performance and safety performance of the battery. Once lithium plating occurs in the battery, not only will the electrical performance of the battery be reduced, but with the accumulation of the amount of lithium plating, dendrites are likely to form. The dendrites may pierce the diaphragm and cause an internal short circuit in the battery, posing a safety hazard.

[0003] Therefore, how to effectively avoid or reduce the risk of lithium plating in the battery has become a technical problem to be solved urgently at present. Summary of the Invention

[0004] The present application provides an electrode assembly, a battery cell, a battery, and a manufacturing method and device thereof, aiming to reduce or avoid lithium plating and improve the safety of the battery.

[0005] In a first aspect, an embodiment of the present application provides an electrode assembly, including: a positive electrode tab and a negative electrode tab, the positive electrode tab and the negative electrode tab are wound or folded to form a bent area;

[0006] The positive electrode tab includes a plurality of bent portions located in the bent area, the bent portion includes a positive current collector layer and a positive active material layer, and the positive current collector layer is provided with a positive active material layer on at least one surface in the thickness direction of the positive electrode tab;

[0007] Wherein, a barrier layer is provided between the positive current collector layer and the positive active material layer, and the barrier layer is used to block the electron transfer between the positive current collector layer and the positive active material layer.

[0008] In the above technical solution, a barrier layer is provided between the positive current collector layer and the positive active material layer of the bent portion, and the barrier layer can block the electron transfer between the positive current collector layer and the positive active material layer, thereby weakening or preventing the delithiation reaction of the positive active material layer at the bent portion of the positive electrode tab. Even if the negative active material at the bent portion of the negative electrode tab falls off, since there are no lithium ions to be inserted or the number of lithium ions to be inserted is small, the probability of lithium plating can be reduced or the phenomenon of lithium plating can be avoided, thereby improving the battery safety.

[0009] In some embodiments, the positive current collector layer is provided with a positive active material layer on the inner side surface in the thickness direction, and a barrier layer is provided between the positive active material layer and the positive current collector layer on the inner side surface of at least one bent portion.

[0010] In the above technical solution, a barrier layer is provided between the positive electrode active material layer and the positive electrode current collector layer where at least one bending portion is located on the inner side surface. The barrier layer can prevent electron transfer between the positive electrode current collector layer and the positive electrode active material layer on its inner side surface, and can reduce the phenomenon of lithium deposition on the negative electrode active material layer on the outer side surface of the negative electrode tab.

[0011] In some embodiments, a positive electrode active material layer is provided on the outer side surface of the positive electrode current collector layer in the thickness direction, and a barrier layer is provided between the positive electrode active material layer and the positive electrode current collector layer where at least one bending portion is located on the outer side surface.

[0012] In the above technical solution, a barrier layer is provided between the positive electrode active material layer and the positive electrode current collector layer where at least one bending portion is located on the outer side surface. The barrier layer can prevent electron transfer between the positive electrode current collector layer and the positive electrode active material layer on its outer side surface, and can reduce the phenomenon of lithium deposition on the negative electrode active material layer on the inner side surface of the negative electrode tab.

[0013] In some embodiments, positive electrode active material layers are provided on both the inner side surface and the outer side surface of the positive electrode current collector layer in the thickness direction, and barrier layers are provided between the positive electrode active material layer and the positive electrode current collector layer where at least one bending portion is located on the inner side surface and between the positive electrode active material layer and the positive electrode current collector layer where at least one bending portion is located on the outer side surface.

[0014] In the above technical solution, barrier layers are provided between the positive electrode active material layer and the positive electrode current collector layer where at least one bending portion is located on the inner side surface and between the positive electrode active material layer and the positive electrode current collector layer where at least one bending portion is located on the outer side surface. The barrier layer can prevent electron transfer between the positive electrode current collector layer and the positive electrode active material layer on the outer side surface and can also prevent electron transfer between the positive electrode current collector layer and the positive electrode active material layer on the inner side surface, and can reduce the phenomenon of lithium deposition on the negative electrode active material layer on both the inner and outer side surfaces of the negative electrode tab.

[0015] In some embodiments, the positive electrode tab and the negative electrode tab are wound to form a winding structure, and the winding structure includes a bending area;

[0016] The innermost tab in the bending area is the negative electrode tab, and a barrier layer is provided at the innermost bending portion in the bending area.

[0017] Since the bending degree of the negative electrode tab is the largest in the area closer to the inner side in the bending area, the phenomenon of powder falling is more serious than in other areas, and the phenomenon of lithium deposition is more likely to occur. In the above technical solution, a barrier layer is provided at the innermost bending portion in the bending area. The barrier layer can prevent electron transfer between at least a part of the innermost positive electrode current collector layer and the positive electrode active material layer, and can reduce the phenomenon of lithium deposition in the innermost part of the bending area of the negative electrode tab.

[0018] In some embodiments, both ends of the barrier layer extending along the bending direction of the bent portion are located in the bending region.

[0019] In the above technical solution, the entire barrier layer is located in the bending region, reducing or avoiding the influence of the barrier layer on the part of the positive electrode tab outside the bending region.

[0020] In some embodiments, the electrode assembly includes a straight region connected to the bending region;

[0021] Both ends of the barrier layer extending along the bending direction of the bent portion are located in the straight region, or one end of the barrier layer extending along the bending direction of the bent portion is located in the straight region and the other end is located in the bending region.

[0022] In the above technical solution, it is possible to block the transmission of more electrons between the positive current collector layer and the positive active material layer, reducing the occurrence of lithium deposition.

[0023] In some embodiments, one end or both ends of the barrier layer extending in the first direction do not extend beyond the positive active material layer, and the first direction is perpendicular to the bending direction of the bending region.

[0024] In the above technical solution, it is possible to block the transmission of some electrons between the positive current collector layer and the positive active material layer, reducing the occurrence of lithium deposition, and at the same time ensuring the energy density of the electrode assembly.

[0025] In some embodiments, the barrier layers are multiple and discontinuous, and the multiple barrier layers are arranged at intervals along the bending direction of the bending region, or the multiple barrier layers are arranged at intervals along the first direction, and the first direction is perpendicular to the bending direction of the bending region.

[0026] In the above technical solution, it is possible to block the transmission of some electrons between the positive current collector layer and the positive active material layer, reducing the occurrence of lithium deposition, and at the same time ensuring the energy density of the electrode assembly.

[0027] In some embodiments, one surface of the barrier layer is attached to the positive current collector layer, and the other surface is attached to the positive active material layer.

[0028] In the above technical solution, the barrier layer is firmly connected to the positive current collector layer and the positive active material layer, reducing or avoiding the position movement of the barrier layer during the use of the battery cell.

[0029] In some embodiments, the barrier layer is an insulating layer.

[0030] In the above technical solution, the insulating layer has a relatively large resistance and can completely block the electron transmission between the positive current collector layer and the positive active material layer, thereby reducing the occurrence of lithium deposition.

[0031] In some embodiments, the barrier layer includes at least one of an insulating glue layer, a ceramic insulating layer, and an insulating tape.

[0032] In the above technical solution, one or a combination of several of the insulating adhesive layer, the ceramic insulating layer, and the insulating tape can effectively block the electron transfer between the positive current collector layer and the positive active material layer, thereby reducing the occurrence of lithium plating.

[0033] In some embodiments, the composition of the insulating adhesive layer includes at least one of styrene-butadiene rubber, polyacrylate, polyvinyl chloride, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene polymer, epoxy resin, butadiene-acrylonitrile polymer, polyurethane rubber, poly(methyl acrylate), and poly(ethyl acrylate).

[0034] In the above technical solution, the insulating adhesive layer with the above composition can effectively block the electron transfer between the positive current collector layer and the positive active material layer, thereby reducing the occurrence of lithium plating.

[0035] In some embodiments, the two surfaces of the insulating adhesive layer are respectively bonded to the positive current collector layer and the positive active material layer.

[0036] In the above technical solution, the above insulating adhesive layer is firmly connected to the positive current collector layer and the positive active material layer, reducing or avoiding the position movement of the insulating adhesive layer during the use of the battery cell.

[0037] In some embodiments, the ceramic insulating layer is a mixture of ceramic particles and a polymer binder; the ceramic particles include at least one of aluminum oxide, titanium oxide, barium sulfate, and zirconium oxide;

[0038] The composition of the polymer binder includes at least one of styrene-butadiene rubber, polyacrylate, polyvinyl chloride, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene polymer, epoxy resin, butadiene-acrylonitrile polymer, polyurethane rubber, poly(methyl acrylate), and poly(ethyl acrylate).

[0039] In the above technical solution, the polymer binder can bond to the positive current collector layer and the positive active material layer, and the ceramic particles can block the electron transfer between the positive current collector layer and the positive active material layer, thereby reducing the occurrence of lithium plating.

[0040] In some embodiments, the base material of the insulating tape is polyethylene terephthalate, polyvinyl chloride, polyethylene, or oriented polypropylene.

[0041] The insulating tape with the above material can block the electron transfer between the positive current collector layer and the positive active material layer, thereby reducing the occurrence of lithium plating.

[0042] In a second aspect, an embodiment of the present application provides a battery cell, including a housing and the above electrode assembly;

[0043] The electrode assembly is accommodated in the housing.

[0044] In a third aspect, an embodiment of the present application provides a battery, including a box body and the above-mentioned battery cell;

[0045] The battery cell is accommodated in the box body.

[0046] In a fourth aspect, an embodiment of the present application provides an electrical device, including the above-mentioned battery.

[0047] In a fifth aspect, an embodiment of the present application provides a manufacturing method for an electrode assembly. The manufacturing method includes:

[0048] providing a positive electrode plate, a negative electrode plate, and a barrier layer;

[0049] winding or folding the positive electrode plate and the negative electrode plate to form a bending area;

[0050] wherein, the positive electrode plate includes a plurality of bending parts located in the bending area. The bending part includes a positive current collector layer and a positive active material layer. The positive current collector layer is provided with a positive active material layer on at least one surface in the thickness direction of the positive electrode plate;

[0051] A barrier layer is provided between the positive current collector layer and the positive active material layer, and the barrier layer is used to block the electron transfer between the positive current collector layer and the positive active material layer.

[0052] In some embodiments, the manufacturing method further includes:

[0053] Before winding or folding the positive electrode plate and the negative electrode plate, a barrier layer is provided between the positive current collector layer and the positive active material layer on at least one surface in the thickness direction of the positive electrode plate.

[0054] In some embodiments, an isolation film for isolating the positive electrode plate and the negative electrode plate is provided, and the positive electrode plate, the isolation film, and the negative electrode plate are wound or folded to form a bending area.

[0055] In a sixth aspect, an embodiment of the present application provides a manufacturing device for an electrode assembly, including:

[0056] a first providing device for providing a positive electrode plate;

[0057] a second providing device for providing a negative electrode plate;

[0058] a third providing device for providing a barrier layer; and

[0059] an assembling device for winding or folding the positive electrode plate and the negative electrode plate to form a bending area;

[0060] wherein, the positive electrode plate includes a plurality of bending parts located in the bending area. The bending part includes a positive current collector layer and a positive active material layer. The positive current collector layer is provided with a positive active material layer on at least one surface in the thickness direction of the positive electrode plate;

[0061] A barrier layer is provided between the positive current collector layer and the positive active material layer, and the barrier layer is used to block the electron transfer between the positive current collector layer and the positive active material layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. Obviously, the following described drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the drawings.

[0063] Figure 1 It is a schematic structural diagram of a vehicle provided by some embodiments of the present application;

[0064] Figure 2 It is an exploded view of a battery provided by some embodiments of the present application;

[0065] Figure 3 For Figure 2 It is a schematic structural diagram of the battery module shown;

[0066] Figure 4 For Figure 3 It is an exploded view of the battery cell shown;

[0067] Figure 5 It is a schematic structural diagram of an electrode assembly provided by some embodiments of the present application;

[0068] Figure 6 It is a schematic structural diagram of an electrode assembly provided by some other embodiments of the present application;

[0069] Figure 7 It is a partial enlarged view of an electrode assembly provided by some embodiments of the present application;

[0070] Figure 8 It is a partial view of a part of the electrode assembly located in the bending area provided by some embodiments of the present application;

[0071] Figure 9 It is a partial view of a part of the electrode assembly located in the bending area provided by some other embodiments of the present application;

[0072] Figure 10 It is a partial view of a part of the electrode assembly located in the bending area provided by some further embodiments of the present application;

[0073] Figure 11 For Figure 5 It is a partial view of the electrode assembly shown;

[0074] Figure 12A partial view of the portion of the electrode assembly provided in some embodiments of the present application that is located in the bending region;

[0075] Figure 13 A flowchart of a manufacturing method of an electrode assembly provided in some embodiments of the present application;

[0076] Figure 14 A flowchart of a manufacturing method of an electrode assembly provided in some other embodiments of the present application;

[0077] Figure 15 A flowchart of a manufacturing method of an electrode assembly provided in some further embodiments of the present application;

[0078] Figure 16 A schematic block diagram of a manufacturing apparatus of an electrode assembly provided in some embodiments of the present application.

[0079] In the drawings, the drawings are not drawn to actual scale. Detailed implementation manners

[0080] The following further describes in detail the implementation manners of the present application in conjunction with the drawings and embodiments. The detailed descriptions and drawings of the following embodiments are used to exemplarily illustrate the principle of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0081] In the description of the present application, it should be noted that unless otherwise stated, the meaning of "a plurality" is two or more; the orientation or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range.

[0082] The orientation terms appearing in the following description are all the directions shown in the drawings and do not limit the specific structure of the present application. In the description of the present application, it should also be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0083] In this application, the term "and / or" is merely a description of the association relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, in this application, the character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0084] In the embodiments of this application, the same reference numerals represent the same components. And for the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the thickness, length, width, etc. of various components in the embodiments of this application shown in the drawings, as well as the overall thickness, length, width, etc. of the integrated device, are only exemplary descriptions and should not constitute any limitation to this application.

[0085] In this application, the battery cell can include a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, etc., and the embodiments of this application do not limit this. The battery cell can be in a cylindrical shape, a flat shape, a cuboid shape, or other shapes, etc., and the embodiments of this application also do not limit this. Generally, the battery cell is divided into three types according to the packaging method: cylindrical battery cell, square battery cell, and soft-pack battery cell, and the embodiments of this application also do not limit this.

[0086] The battery mentioned in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide a higher voltage and capacity. For example, the battery mentioned in this application can include a battery module or a battery pack, etc. The battery generally includes a box for encapsulating one or more battery cells. The box can prevent liquids or other foreign objects from affecting the charging or discharging of the battery cell.

[0087] The battery cell includes an electrode assembly and an electrolyte. The electrode assembly is composed of a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell mainly operates by the movement of metal ions between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material body. The positive electrode active material body is coated on the surface of the positive electrode current collector. The positive electrode current collector without the coated positive electrode active material body protrudes from the positive electrode current collector with the coated positive electrode active material body. The positive electrode current collector without the coated positive electrode active material body serves as the positive electrode tab. Taking a lithium-ion battery as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium, or lithium manganate, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material body. The negative electrode active material body is coated on the surface of the negative electrode current collector. The negative electrode current collector without the coated negative electrode active material body protrudes from the negative electrode current collector with the coated negative electrode active material body. The negative electrode current collector without the coated negative electrode active material body serves as the negative electrode tab. The material of the negative electrode current collector can be copper, and the negative electrode active material can be carbon or silicon, etc. To ensure that large currents can pass through without fusing, the number of positive electrode tabs is multiple and they are folded together, and the number of negative electrode tabs is multiple and they are folded together. The material of the separator can be PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly can be a wound structure or a stacked structure, and the embodiments of the present application are not limited thereto.

[0088] The development of battery technology needs to consider multiple design factors simultaneously. For example, performance parameters such as energy density, cycle life, discharge capacity, charge and discharge rate, etc. In addition, the safety of the battery also needs to be considered.

[0089] For a lithium-ion battery, during charging, lithium ions are deintercalated from the positive electrode and intercalated into the negative electrode; during discharging, lithium ions are deintercalated from the negative electrode and intercalated into the positive electrode. When a lithium-ion battery is charging, some abnormal situations may occur leading to lithium plating. For example, the lithium intercalation space in the negative electrode is insufficient, the resistance to lithium ion migration is too large, or lithium ions quickly detach from the positive electrode but cannot be intercalated into the negative electrode in equal amounts. The lithium ions that cannot be intercalated into the negative electrode can only obtain electrons on the surface of the negative electrode, thus forming lithium metal, which is the lithium plating phenomenon.

[0090] The inventors found that lithium plating is likely to occur in the bending area of the electrode assembly. After further research, it was found that during the winding or folding process of the positive electrode sheet and the negative electrode sheet, the part of the negative electrode sheet in the bending area is prone to powder shedding, resulting in the detachment of the negative electrode active material of the negative electrode sheet. This causes some of the lithium ions deintercalated from the positive electrode sheet during charging to be unable to be intercalated into the negative electrode sheet, resulting in the lithium plating phenomenon.

[0091] In view of this, an embodiment of the present application provides a technical solution. By arranging a barrier layer between the positive current collector and the positive active material layer of the positive electrode plate at the bent portion, the barrier layer is used to block the electron transfer between the positive current collector layer and the positive active material layer, so as to weaken or prevent the delithiation reaction of the positive active material layer at the bent portion. The positive active material layer does not intercalate or deintercalate lithium ions, or the number of intercalated or deintercalated lithium ions is small, thereby reducing the occurrence of lithium deposition phenomenon and improving the safety and service life of the battery cell.

[0092] The technical solution described in the embodiment of the present application is applicable to batteries and electrical equipment using the batteries.

[0093] The electrical equipment can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle 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 electric vehicle or an extended-range electric vehicle, etc.; the spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, etc.; the electric toy includes a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and a railway electric tool, for example, an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact electric drill, a concrete vibrator, a planer, etc. The embodiment of the present application does not impose special restrictions on the above electrical equipment.

[0094] For the convenience of description, the following embodiments take the electrical equipment as a vehicle as an example for illustration.

[0095] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a vehicle 1000 provided by some embodiments of the present application. A battery 100 is arranged inside the vehicle 1000, and the battery 100 can be arranged at the bottom, head or tail of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000. For example, the battery 100 can be used as the operating power source of the vehicle 1000.

[0096] The vehicle 1000 may further include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300. For example, it is used for the working power requirements during the start, navigation and driving of the vehicle 1000.

[0097] In some embodiments of the present application, the battery 100 can not only be used as the operating power source of the vehicle 1000, but also be used as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0098] Please refer to Figure 2 , Figure 2Exploded view of the battery 100 provided by some embodiments of the present application. The battery 100 includes a box body 10 and battery cells 20 ( Figure 2 not shown), and the battery cells 20 are accommodated in the box body 10.

[0099] The box body 10 is used to accommodate the battery cells 20, and the box body 10 can be of various structures. In some embodiments, the box body 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 an accommodation space 13 for accommodating the battery cells 20. The second part 12 may be a hollow structure with one end open, and the first part 11 may be a plate-like structure. 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 the accommodation space 13; the first part 11 and the second part 12 may also both 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 first part 11 and the second part 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0100] In the battery 100, the number of battery cells 20 can be one or multiple. If there are multiple battery cells 20, the multiple battery cells 20 can be connected in series, parallel, or in a mixed connection. A mixed connection means that there are both series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, parallel, or in a mixed connection together, and then the whole formed by the multiple battery cells 20 is accommodated in the box body 10; of course, it can also be that multiple battery cells 20 are first connected in series, parallel, or in a mixed connection to form battery modules 30, and then the multiple battery modules 30 are connected in series, parallel, or in a mixed connection to form a whole and are accommodated in the box body 10.

[0101] In some embodiments, please refer to Figure 3 , Figure 3 is Figure 2 the schematic structural view of the battery module 30 shown. The battery 100 includes multiple battery modules 30. The battery module 30 includes multiple battery cells 20, and the multiple battery cells 20 are first connected in series, parallel, or in a mixed connection to form the battery module 30. The multiple battery modules 30 are then connected in series, parallel, or in a mixed connection to form a whole and are accommodated in the box body 10.

[0102] The multiple battery cells 20 in the battery module 30 can be electrically connected through a busbar component 31 to achieve parallel, series, or mixed connection of the multiple battery cells 20 in the battery module 30.

[0103] Please refer to Figure 4 , Figure 4 is Figure 3Exploded view of the battery cell 20 shown. In the embodiment of the present application, the battery cell 20 includes a housing 21 and an electrode assembly 22, and the electrode assembly 22 is accommodated in the housing 21.

[0104] In some embodiments, the housing 21 can also be used to accommodate an electrolyte, such as an electrolytic solution. The housing 21 can be in various structural forms.

[0105] In some embodiments, the housing 21 can include a housing body 211 and a cover body 212. The housing body 211 is a hollow structure with an opening on one side, and the cover body 212 is covered on the opening of the housing body 211 and forms a sealed connection to form a sealed space 213 for accommodating the electrode assembly 22 and the electrolyte.

[0106] When assembling the battery cell 20, the electrode assembly 22 can be first placed into the housing body 211, the electrolyte can be filled into the housing body 211, and then the cover body 212 can be covered on the opening of the housing body 211.

[0107] The housing body 211 can be in various shapes, such as a cylinder, a cuboid, etc. The shape of the housing body 211 can be determined according to the specific shape of the electrode assembly 22. For example, if the electrode assembly 22 is a cylinder structure, a cylinder housing body 211 can be selected; if the electrode assembly 22 is a cuboid structure, a cuboid housing body 211 can be selected. Of course, the cover body 212 can also be in various structures, such as a plate-like structure, a hollow structure with an opening at one end, etc. Exemplarily, in Figure 4 the housing body 211 is a cuboid structure, the cover body 212 is a plate-like structure, and the cover body 212 is covered on the opening of the housing body 211.

[0108] In some embodiments, the battery cell 20 can further include a positive electrode terminal 23, a negative electrode terminal 24, and a pressure relief mechanism 25. The positive electrode terminal 23, the negative electrode terminal 24, and the pressure relief mechanism 25 are all installed on the cover body 212. The positive electrode terminal 23 and the negative electrode terminal 24 are both used for electrically connecting with the electrode assembly 22, that is, the positive electrode terminal 23 is used for electrically connecting with the positive electrode plate 222, and the negative electrode terminal 24 is used for electrically connecting with the negative electrode plate 221. The pressure relief mechanism 25 is used for relieving the pressure inside the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value.

[0109] Exemplarily, as Figure 4 shown, the pressure relief mechanism 25 is located between the positive electrode terminal 23 and the negative electrode terminal 24. The pressure relief mechanism 25 can be components such as an explosion-proof valve, an explosion-proof sheet, an air valve, a pressure relief valve, or a safety valve.

[0110] It is understandable that the outer shell 21 is not limited to the above structure. The outer shell 21 can also be other structures. For example, the outer shell 21 includes a housing 211 and two cover bodies 212. The housing 211 is a hollow structure with openings on opposite sides. One cover body 212 is correspondingly covered on one opening of the housing 211 and forms a sealed connection to form a sealed space 213 for accommodating the electrode assembly 22 and the electrolyte. In this structure, the positive electrode terminal 23 and the negative electrode terminal 24 can be installed on the same cover body 212, or can be installed on different cover bodies 212; a pressure relief mechanism 25 can be installed on one cover body 212, or pressure relief mechanisms 25 can be installed on both cover bodies 212.

[0111] It should be noted that in the embodiments of the present application, the number of electrode assemblies 22 accommodated in the outer shell 21 can be one or multiple. Exemplarily, in Figure 4 , there are two electrode assemblies 22.

[0112] Please refer to Figure 5 and Figure 6 , Figure 5 which are schematic structural diagrams of the electrode assembly 22 provided in some embodiments of the present application; Figure 6 which are schematic structural diagrams of the electrode assembly 22 provided in some other embodiments of the present application. The electrode assembly 22 includes a negative electrode tab 221 and a positive electrode tab 222. The negative electrode tab 221 and the positive electrode tab 222 are wound or folded to form a bending area A.

[0113] Among them, the positive electrode tab 222 includes a plurality of bending parts 2220 located in the bending area A. The bending parts 2220 include a positive current collector layer 2220a ( Figure 5 and Figure 6 not shown) and a positive active material layer 2220b ( Figure 5 and Figure 6 not shown). The positive current collector layer 2220a is provided with a positive active material layer 2220b on at least one side in the thickness direction of the positive electrode tab 222. A barrier layer 223 is provided between the positive current collector layer 2220a and the positive active material layer 2220b. The barrier layer 223 is used to block the electron transfer between the positive current collector layer 2220a and the positive active material layer 2220b.

[0114] A barrier layer 223 is provided between the positive current collector layer 2220a and the positive active material layer 2220b of the bent portion 2220. The barrier layer 223 can block the electron transfer between the positive current collector layer 2220a and the positive active material layer 2220b, thereby weakening or preventing the de-lithiation reaction of the positive active material layer 2220b of the positive electrode plate 222 at the bent portion 2220. Even if the negative active material detachment phenomenon occurs at the bent portion 2220 of the negative electrode plate 221, since there are no lithium ions to be inserted or the number of lithium ions to be inserted is small, the probability of lithium deposition can be reduced or the lithium deposition phenomenon can be avoided, thereby improving the battery safety.

[0115] It should be noted that only when the electron transfer occurs from the positive current collector layer 2220a to the interface of the positive active material layer 2220b can the positive active material layer 2220b release ions. The barrier layer 223 blocks the electron transfer between the positive current collector layer 2220a and the positive active material layer 2220b, so the barrier layer 223 can actually play a role in preventing the positive active material layer 2220b from releasing ions.

[0116] Exemplarily, the ions released by the particles in the positive active material layer 2220b are lithium ions, that is, the barrier layer 223 plays a role in preventing the particles from releasing lithium ions.

[0117] As Figure shown, the positive electrode plate 222 and the negative electrode plate 221 can be first laminated and then wound to form a winding structure including a bent area A, for example, a flat winding structure. As ​ shown, the positive electrode plate 222 and the negative electrode plate 221 can be first laminated and then bent to form a folding structure including a bent area A, for example, the positive electrode plate 222 and the negative electrode plate 221 are laminated and then continuously folded in an S shape to form a folding structure.

[0118] In some embodiments, the electrode assembly 22 may further include a separator 224, and the separator 224 is used to isolate the positive electrode plate 222 and the negative electrode plate 221 to reduce the risk of short circuit between the positive electrode plate 222 and the negative electrode plate 221.

[0119] The material of the separator 224 can be PP (polypropylene) or PE (polyethylene), etc.

[0120] If the electrode assembly 22 is a winding structure, the positive electrode plate 222, the separator 224, the negative electrode plate 221 and the separator 224 can be laminated in sequence, and then the four are wound to form a winding structure; if the electrode assembly 22 is a folding structure, the separator 224, the positive electrode plate 222, the separator 224, the negative electrode plate 221 and the separator 224 can be laminated in sequence, and then the five are folded to form a folding structure.

[0121] Whether the electrode assembly 22 is in a wound structure or a folded structure, the electrode assembly 22 may further include a flat region B. The flat region B is connected to the bent region A, and bent regions A may be provided at both opposite ends of the flat region B. The flat region B is the region where the electrode assembly 22 has a flat structure. The portions of the positive electrode tab 222 located in the flat region B and the portions of the negative electrode tab 221 located in the flat region B are both arranged substantially flat. In the extending direction of the portion of the positive electrode tab 222 located in the flat region B, the two bent regions A are located at both ends of the flat region B. The bent region A is the region where the wound structure has a bent structure. The portions of the positive electrode tab 222 located in the bent region A (the bent portion 2220) and the portions of the negative electrode tab 221 located in the bent region A are both bent and distributed. Exemplarily, the portions of the positive electrode tab 222 located in the bent region A (the bent portion 2220) and the portions of the negative electrode tab 221 located in the bent region A are both arc-shaped.

[0122] In some embodiments, as ​ and ​ shown, both ends of the barrier layer 223 extending along the bending direction C of the bent portion 2220 are located in the bent region A, that is, the entire barrier layer 223 is located in the bent region A, reducing or avoiding the influence of the barrier layer 223 on the portion of the positive electrode tab 222 outside the bent region A.

[0123] It should be noted that if one end or both ends of the barrier layer 223 are just located at the boundary position between the flat region B and the bent region A, it is also regarded as the barrier layer 223 being located in the bent region A. The bending direction C of the bent portion 2220 is the circumferential direction of the arc where the bent portion 2220 is located. Exemplarily, as ​ shown, both ends of the barrier layer 223 extending along the bending direction C of the bent portion 2220 are located at the boundary between the bent region A and the flat region B.

[0124] In some embodiments, as ​ shown, ​ is a partial view of the portion of the electrode assembly provided in some embodiments of the present application located in the bent region A. Both ends of the barrier layer 223 extending along the bending direction C of the bent portion 2220 are located in the bent region A, and there is a distance between one end or both ends of the barrier layer 223 and the boundary position between the flat region B and the bent region A. Exemplarily, as ​ shown, neither end of the barrier layer 223 extends to the boundary position between the flat region B and the bent region A, and the barrier layer 223 is not provided in some regions at both ends of the bent portion 2220. Electron transfer can occur between the positive current collector layer 2220a and the positive active material layer 2220b in this portion of the region, and the positive active material layer 2220b can release lithium ions. In this way, the barrier layer 223 can both block the transfer of some electrons between the positive current collector layer 2220a and the positive active material layer 2220b, reducing the occurrence of lithium deposition, and ensure the energy density of the electrode assembly.

[0125] In some other embodiments, both ends of the barrier layer 223 extending along the bending direction C of the bending portion 2220 are located in the straight region B. In still some other embodiments, one end of the barrier layer 223 extending along the bending direction C of the bending portion 2220 is located in the straight region B, and the other end is located in the bending region A.

[0126] In some embodiments, please refer to ​ , ​ which is a partial enlarged view of the electrode assembly 22 provided in some embodiments of the present application. The positive electrode tab 222 includes a positive current collector 2221 and positive active material bodies 2222 provided on both sides in the thickness direction of the positive current collector 2221. The positive current collector 2221 may have a portion where the positive active material bodies 2222 are not coated, and this portion can be used as a positive electrode tab for electrically connecting to the positive electrode terminal 23 (see ​ ). The negative electrode tab 221 includes a negative current collector 2211 and negative active material bodies 2212 provided on both sides in the thickness direction of the negative current collector 2211. The negative current collector 2211 may have a portion where the negative active material bodies 2212 are not coated, and this portion can be used as a negative electrode tab for electrically connecting to the negative electrode terminal 24 (see ​ ).

[0127] It can be understood that the positive current collector layer 2220a of the bending portion 2220 is the portion of the positive current collector 2221 located in the bending region A, and the positive active material layer 2220b of the bending portion 2220 is the portion of the positive active material bodies 2222 located in the bending region A.

[0128] In the embodiments of the present application, in the bending portion 2220, the positive active material layer 2220b may be provided on the inner side surface 2220c of the positive current collector layer 2220a, or the positive active material layer 2220b may be provided on the outer side surface 2220d of the positive current collector layer 2220a, or the positive active material layer 2220b may be provided on both the outer side surface 2220d and the inner side surface 2220c of the positive current collector layer 2220a. In the electrode assembly 22, if there is a positive active material layer 2220b provided with the barrier layer 223, the occurrence of lithium deposition can be effectively reduced. It can be understood that the inner side surface 2220c of the positive current collector layer 2220a is located inside the outer side surface 2220d, and the inner side surface 2220c of the positive current collector layer 2220a is closer to the straight region B than the outer side surface 2220d.

[0129] In some embodiments, please refer to ​ , ​ which is a partial enlarged view of the electrode assembly 22 provided in some embodiments of the present application. One surface of the barrier layer 223 is attached to the positive current collector layer 2220a, and the other surface is attached to the positive active material layer 2220b.

[0130] Attaching refers to adhesion, coating, or spraying. By means of attachment, the barrier layer 223 is firmly connected to the positive current collector layer 2220a and the positive active material layer 2220b, reducing or avoiding the displacement of the barrier layer 223 during the use of the battery cell 20.

[0131] For the convenience of description, in the following embodiments, the electrode assembly 22 is taken as a wound structure as an example to elaborate in detail on the arrangement form of the barrier layer 223.

[0132] In some embodiments, please refer to ​ , ​ is a partial view of a part of the electrode assembly 22 provided in some embodiments of the present application located in the bending area A. The positive active material layer 2220b is provided on the inner side surface 2220c of the positive current collector layer 2220a in the thickness direction of the positive electrode plate 222. At least one bending portion 2220 is provided with a barrier layer 223 between the positive active material layer 2220b and the positive current collector layer 2220a on the inner side surface 2220c. The barrier layer 223 can prevent at least some of the particles in the positive active material layer 2220b on the inner side surface 2220c of the positive current collector layer 2220a from releasing lithium ions to the negative electrode plate 221, and can reduce the occurrence of lithium deposition phenomenon in the part of the negative electrode plate 221 located in the bending area A and inside the barrier layer 223.

[0133] The thickness direction of the positive electrode plate 222 is also the thickness direction of the positive current collector layer 2220a.

[0134] In this embodiment, the positive active material layer 2220b may or may not be provided on the outer side surface 2220d of the positive current collector layer 2220a. ​ shows exemplarily that the positive active material layers 2220b are provided on both the outer side surface 2220d and the inner side surface 2220c of the positive current collector layer 2220a. Of course, the barrier layer 223 may be provided only between the positive active material layer 2220b and the positive current collector layer 2220a on the inner side surface 2220c of one bending portion 2220, or the barrier layer 223 may be provided between the positive active material layer 2220b and the positive current collector layer 2220a on the inner side surface 2220c of multiple bending portions 2220.

[0135] It should be noted that as ​As shown, there is a certain distance between both ends of the barrier layer 223 and the boundary position between the straight region B and the bent region A. The positive electrode active material layer 2220b of the bent portion 2220 includes a third portion connected to the positive electrode current collector layer 2220a and a fourth portion corresponding to the barrier layer 223. The thickness of the fourth portion can be the same as that of the third portion. In this way, when manufacturing the positive electrode active material layer 2220b, the thicknesses of all parts of the positive electrode active material layer 2220b are basically the same, and the manufacturing process is more convenient. Of course, the thickness of the fourth portion can also be less than that of the third portion. For example, the sum of the thickness of the fourth portion and the thickness of the barrier layer 223 is equal to the thickness of the third portion. In this way, the thicknesses of each part of the bent portion 2220 along the bending direction C are relatively close or basically the same, and the force is more uniform.

[0136] In some embodiments, please refer to ​ , ​ is a partial view of a part of the electrode assembly 22 provided in some other embodiments of the present application located in the bent region A. The positive electrode current collector layer 2220a is provided with a positive electrode active material layer 2220b on the outer side surface 2220d in the thickness direction of the positive electrode plate 222. At least one bent portion 2220 is provided with a barrier layer 223 between the positive electrode active material layer 2220b and the positive electrode current collector layer 2220a located on the outer side surface 2220d. The barrier layer 223 can prevent the electron transfer between the positive electrode current collector layer 2220a and the positive electrode active material layer 2220b on its inner side surface 2220c, and can reduce the phenomenon of lithium deposition in the negative electrode active material layer on the outer side surface 2220d of the negative electrode plate 221.

[0137] In this embodiment, the positive electrode active material layer 2220b may or may not be provided on the inner side surface 2220c of the positive electrode current collector layer 2220a. ​ exemplarily shows that the positive electrode active material layer 2220b is provided on both the outer side surface 2220d and the inner side surface 2220c of the positive electrode current collector layer 2220a. Of course, the barrier layer 223 may be provided only between the positive electrode active material layer 2220b and the positive electrode current collector layer 2220a on the inner side surface 2220c of one bent portion 2220, or the barrier layer 223 may be provided between the positive electrode active material layer 2220b and the positive electrode current collector layer 2220a on the inner side surface 2220c of multiple bent portions 2220. In some implementations, please refer to ​ , ​A partial view of a portion of the electrode assembly 22 provided in some embodiments of the present application located in the bending region A. The positive electrode active material layer 2220b is provided on both the outer side surface 2220d and the inner side surface 2220c of the positive electrode current collector layer 2220a, and at least one bending portion 2220 is provided with a barrier layer 223 between the positive electrode active material layer 2220b on the inner side surface 2220c and the positive electrode current collector layer 2220a and between the positive electrode active material layer 2220b on the outer side surface 2220d and the positive electrode current collector layer 2220a.

[0138] In this way, the barrier layer 223 can prevent the electron transfer between the positive electrode active material layer 2220b on the outer side surface 2220d and the positive electrode current collector layer 2220a, and can also prevent the electron transfer between the positive electrode active material layer 2220b on the inner side surface 2220c and the positive electrode current collector layer 2220a, which can reduce the phenomenon of lithium deposition in the negative electrode active material layer on the inner and outer side surfaces 2220d of the negative electrode tab 221. ​ In the figure, it is exemplarily shown that the barrier layer 223 is provided on both the inner positive electrode active material layer 2220b and the outer positive electrode active material layer 2220b in at least one bending portion 2220.

[0139] In the embodiments of the present application, the barrier layer 223 may be provided on all the bending portions 2220 located in the bending region A, or the barrier layer 223 may be provided on a part of the bending portions 2220 located in the bending region A. For example, the barrier layer 223 is provided on one, two or three bending portions 2220 located at the innermost side of the bending region A.

[0140] In some embodiments, please refer to ​ , ​ For ​ a partial view of the electrode assembly 22 shown in the figure. Taking the example that the positive electrode tab 222 and the negative electrode tab 221 are wound to form a wound structure including a bending region, the innermost tab in the bending region A is the negative electrode tab 221, and the innermost bending portion 2220 in the bending region A is provided with the barrier layer 223.

[0141] Since the innermost tab in the bending region A is the negative electrode tab 221, the degree of bending of the negative electrode tab 221 is greater in the region closer to the inner side in the bending region A, and the phenomenon of powder falling is more serious than in other regions, and the phenomenon of lithium deposition is more likely to occur. Therefore, the barrier layer 223 is provided on the innermost bending portion 2220 in the bending region A, which can effectively reduce lithium deposition.

[0142] It should be noted that the barrier layer 223 may be provided between the positive electrode active material layer 2220b and the positive electrode current collector layer 2220a where the innermost bending part 2220 of the bending area A is located on the inner side surface 2220c; or the barrier layer 223 may be provided between the positive electrode active material layer 2220b and the positive electrode current collector layer 2220a where the innermost bending part 2220 of the bending area A is located on the outer side surface 2220d. Additionally, the barrier layer 223 may be provided both between the positive electrode active material layer 2220b and the positive electrode current collector layer 2220a where the innermost bending part 2220 of the bending area A is located on the inner side surface 2220c and between the positive electrode active material layer 2220b and the positive electrode current collector layer 2220a where the innermost bending part 2220 of the bending area A is located on the outer side surface 2220d.

[0143] In some embodiments, one or both ends of the barrier layer 223 extending in the first direction do not extend beyond the positive electrode active material layer 2220b, and the first direction is perpendicular to the bending direction C of the bending area A.

[0144] In this way, there are areas at one or both ends of the bending part 2220 perpendicular to the bending direction C that are not covered by the barrier layer 223. This can not only block the transmission of some electrons between the positive electrode current collector layer 2220a and the positive electrode active material layer 2220b, reducing the occurrence of lithium deposition, but also ensure the energy density of the electrode assembly.

[0145] In some embodiments, please refer to ​ , ​ is a partial view of the part of the electrode assembly provided in still other embodiments of the present application located in the bending area A. The barrier layer 223 is a plurality of non - continuous ones, and the plurality of barrier layers 223 are arranged at intervals along the bending direction C of the bending area A, or the intervals of the plurality of barrier layers 223 along the first direction, and the first direction is perpendicular to the bending direction C of the bending area A.

[0146] The plurality of barrier layers 223 are non - continuously arranged, and there is a certain interval between adjacent barrier layers 223 in the bending direction C of the bending area A or the first direction. There are areas of the bending part 2220 that are not covered by the barrier layer 223. In this way, it can not only block the transmission of some electrons between the positive electrode current collector layer 2220a and the positive electrode active material layer 2220b, reducing the occurrence of lithium deposition, but also ensure the energy density of the electrode assembly. ​ shows, by way of example, that the barrier layer 223 is a plurality of non - continuous ones, and the plurality of barrier layers 223 are arranged at intervals along the bending direction C of the bending area A.

[0147] It should be noted that when multiple barrier layers 223 are arranged at intervals along the bending direction C of the bending area A, the multiple barrier layers 223 can all be located in the bending area A, or some of the barrier layers 223 at one or both ends of the multiple barrier layers 223 in the bending direction C of the bending area A can be partially extended to the straight area B, and the remaining barrier layers 223 are located in the bending area A. When the multiple barrier layers 223 are arranged at intervals along the first direction, the multiple barrier layers 223 can all be located in the bending area A, or some of the barrier layers 223 at one or both ends of the multiple barrier layers 223 in the first direction can be partially extended to the straight area B, and the remaining barrier layers 223 are located in the bending area A.

[0148] In some embodiments, the barrier layer 223 is an insulating layer. The insulating layer has a relatively large resistance and can completely block the transmission of some electrons in the positive current collector layer 2220a and the positive active material layer 2220b, reducing the occurrence of lithium deposition.

[0149] In some embodiments, the barrier layer 223 includes at least one of an insulating adhesive layer, a ceramic insulating layer, and an insulating tape. According to requirements, selecting one or a combination of several of the insulating adhesive layer, the ceramic insulating layer, and the insulating tape for the barrier layer 223 can effectively block the electron transmission between the positive current collector layer 2220a and the positive active material layer 2220b, thereby reducing the occurrence of lithium deposition.

[0150] In some embodiments, the composition of the insulating adhesive layer includes at least one of styrene-butadiene rubber, polyacrylate, polyvinyl chloride, polyvinylidene fluoride, vinylidene fluoride - hexafluoropropylene polymer, epoxy resin, butadiene - acrylonitrile polymer, polyurethane rubber, poly(methyl acrylate), and poly(ethyl acrylate).

[0151] The insulating adhesive layer with the above composition can effectively block the electron transmission between the positive current collector layer 2220a and the positive active material layer 2220b, thereby reducing the occurrence of lithium deposition.

[0152] In some embodiments, the two surfaces of the insulating adhesive layer are respectively bonded to the positive current collector layer 2220a and the positive active material layer 2220b.

[0153] Both surfaces of the insulating adhesive layer are sticky and are respectively bonded to the positive current collector layer 2220a and the positive active material layer 2220b, thereby reducing or avoiding the position movement of the insulating adhesive layer during the use of the battery cell 20.

[0154] In some other embodiments, the composition of the insulating adhesive layer further includes a colorant, such that there are differences in at least one of the pixel distribution, brightness, color, etc. between the insulating layer and the positive current collector layer 2220a. When manufacturing the electrode sheet, a vision inspection device can be used to locate the position of the insulating adhesive layer of the positive electrode sheet 222. The position of the insulating adhesive layer is the position where the bending region A is formed. After determining the position of the insulating adhesive layer, it is convenient to determine the starting position of winding.

[0155] In some embodiments, the ceramic insulating layer is a mixture of ceramic particles and a polymer binder; the ceramic particles include at least one of alumina, titanium oxide, barium sulfate, and zirconia; the components of the polymer binder include at least one of styrene-butadiene rubber, polyacrylate, polyvinyl chloride, polyvinylidene fluoride, vinylidene fluoride - hexafluoropropylene polymer, epoxy resin, butadiene - acrylonitrile polymer, polyurethane rubber, polymethyl acrylate, and polyethyl acrylate.

[0156] In the above technical solution, the polymer binder can bond with the positive current collector layer 2220a and the positive active material layer 2220b, and the ceramic particles can block the electron transfer between the positive current collector layer 2220a and the positive active material layer 2220b, thereby reducing the occurrence of lithium plating.

[0157] In some embodiments, the base material of the insulating tape is polyethylene terephthalate, polyvinyl chloride, polyethylene, or oriented polypropylene.

[0158] The insulating tape of the above material can block the electron transfer between the positive current collector layer 2220a and the positive active material layer 2220b, thereby reducing the occurrence of lithium plating.

[0159] Please refer to ​ , ​ , which is a flowchart of the manufacturing method of the electrode assembly 22 provided by some embodiments of the present application. The manufacturing method of the electrode assembly 22 includes:

[0160] S100: Provide a positive electrode sheet 222, a negative electrode sheet 221, and a barrier layer 223;

[0161] S200: Wind or fold the positive electrode sheet 222 and the negative electrode sheet 221 to form a bending region A;

[0162] Wherein, the positive electrode sheet 222 includes a plurality of bending portions 2220 located in the bending region A. The bending portions 2220 include a positive current collector layer 2220a and a positive active material layer 2220b. The positive current collector layer 2220a is provided with a positive active material layer 2220b on at least one surface in the thickness direction of the positive electrode sheet 222.

[0163] A barrier layer 223 is provided between the positive current collector layer 2220a and the positive active material layer 2220b, and the barrier layer 223 is used to block the electron transfer between the positive current collector layer 2220a and the positive active material layer 2220b.

[0164] In some embodiments, please refer to ​ , ​ which is a flowchart of a manufacturing method of the electrode assembly 22 provided in still some other embodiments of the present application. The manufacturing method of the electrode assembly 22 further includes:

[0165] S150: Before winding or folding the positive electrode sheet 222 and the negative electrode sheet 221, a barrier layer 223 is provided between the positive current collector layer 2220a and the positive active material layer 2220b on at least one surface in the thickness direction of the positive electrode sheet 222.

[0166] Taking the barrier layer 223 as an insulating adhesive layer as an example, before winding or folding the positive electrode sheet 222 and the negative electrode sheet 221, the material of the insulating adhesive layer can be first coated on the positive active material layer 2220b of the positive electrode sheet 222, and after curing, the insulating adhesive layer is obtained, and then the positive electrode sheet 222 and the negative electrode sheet 221 are wound or folded.

[0167] In some embodiments, please refer to ​ , ​ which is a flowchart of a manufacturing method of the electrode assembly 22 provided in still some other embodiments of the present application. An isolation film 224 for isolating the positive electrode sheet 222 and the negative electrode sheet 221 is provided, and the positive electrode sheet 222, the isolation film 224 and the negative electrode sheet 221 are wound or folded to form a bent area A.

[0168] It should be noted that for the related structure of the electrode assembly 22 manufactured by the above manufacturing method of the electrode assembly 22, reference can be made to the electrode assembly 22 provided in the above embodiments.

[0169] Please refer to ​ , ​ which is a schematic block diagram of a manufacturing device 2000 of the electrode assembly 22 provided in some embodiments of the present application. The manufacturing device 2000 includes a first providing device 1100, a second providing device 1200, a third providing device 1300 and an assembling device 1400.

[0170] The first providing device 1100 is used to provide the positive electrode sheet 222. The second providing device 1200 is used to provide the negative electrode sheet 221; the third providing device 1300 is used to provide the barrier layer 223. The assembling device 1400 is used to wind or fold the positive electrode sheet 222 and the negative electrode sheet 221 to form a bent area A.

[0171] Among them, the positive electrode sheet 222 includes a plurality of bending portions 2220 located in the bending region A. The bending portion 2220 includes a positive current collector layer 2220a and a positive active material layer 2220b. The positive active material layer 2220b is disposed on at least one surface of the positive current collector layer 2220a in the thickness direction of the positive electrode sheet 222.

[0172] A barrier layer 223 is provided between the positive current collector layer 2220a and the positive active material layer 2220b. The barrier layer 223 is used to block the electron transfer between the positive current collector layer 2220a and the positive active material layer 2220b.

[0173] In some embodiments, the manufacturing apparatus 2000 further includes a fourth providing device (not shown in the figure), and the fourth providing device is used to provide a separator film 224 for separating the positive electrode sheet 222 and the negative electrode sheet 221. The assembling apparatus 1400 is used to wind or fold the positive electrode sheet 222, the separator film 224, and the negative electrode sheet 221 to form the bending region A.

[0174] Although the present application has been described with reference to the preferred embodiments, various modifications can be made thereto and components thereof can be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any manner. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An electrode assembly, characterized in that, Comprising: A positive electrode tab and a negative electrode tab, the positive electrode tab and the negative electrode tab being wound or folded to form a bent region; The positive electrode tab includes a plurality of bent portions located in the bent region, the bent portion includes a positive current collector layer and a positive active material layer, the positive active material layer is disposed on the inner side surface of the positive electrode tab in the thickness direction of the positive electrode tab, and the positive active material layer is disposed on the outer side surface of the positive electrode tab in the thickness direction; Wherein, a barrier layer is provided between the positive current collector layer and the positive active material layer, and the barrier layer is used to block the electron transfer between the positive current collector layer and the positive active material layer; At least one bent portion has the barrier layer provided between the positive active material layer on the inner side surface and the positive current collector layer, and at least one bent portion has the barrier layer provided between the positive active material layer on the outer side surface and the positive current collector layer.

2. The electrode assembly according to claim 1, characterized in that, The positive electrode tab and the negative electrode tab are wound to form a wound structure, and the wound structure includes the bent region; The innermost tab of the bent region is the negative electrode tab, and the bent portion of the innermost side of the bent region is provided with the barrier layer.

3. The electrode assembly according to claim 1 or 2, characterized in that, Both ends of the barrier layer extending along the bending direction of the bent portion are located in the bent region.

4. The electrode assembly according to claim 1 or 2, characterized in that: The electrode assembly includes a flat region connected to the bent region; Both ends of the barrier layer extending along the bending direction of the bent portion are located in the flat region, or one end of the barrier layer extending along the bending direction of the bent portion is located in the flat region and the other end is located in the bent region.

5. The electrode assembly according to claim 1 or 2, characterized in that, One end or both ends of the barrier layer extending in the first direction do not extend beyond the positive active material layer, and the first direction is perpendicular to the bending direction of the bent region.

6. The electrode assembly according to claim 1 or 2, characterized in that: The barrier layers are a plurality of non - continuous ones, and the plurality of barrier layers are arranged at intervals along the bending direction of the bent region, or the plurality of barrier layers are arranged at intervals along the first direction, and the first direction is perpendicular to the bending direction of the bent region.

7. The electrode assembly according to claim 1 or 2, characterized in that One surface of the barrier layer is attached to the positive current collector layer, and the other surface is attached to the positive active material layer.

8. The electrode assembly according to claim 1 or 2, characterized in that, The barrier layer is an insulating layer.

9. The electrode assembly according to claim 8, wherein, The barrier layer includes at least one of an insulating adhesive layer, a ceramic insulating layer, and an insulating tape.

10. The electrode assembly according to claim 9, characterized in that, The composition of the insulating adhesive layer includes at least one of styrene - butadiene rubber, polyacrylate, polyvinyl chloride, polyvinylidene fluoride, vinylidene fluoride - hexafluoropropylene polymer, epoxy resin, butadiene - acrylonitrile polymer, polyurethane rubber, poly(methyl acrylate), and poly(ethyl acrylate).

11. The electrode assembly according to claim 9, wherein Both surfaces of the insulating adhesive layer are adhesively bonded to the positive current collector layer and the positive active material layer respectively.

12. The electrode assembly according to claim 9, wherein, The ceramic insulating layer is a mixture of ceramic particles and a polymer binder; the ceramic particles include at least one of alumina, titanium oxide, barium sulfate, and zirconia; The composition of the polymer binder includes at least one of styrene - butadiene rubber, polyacrylate, polyvinyl chloride, polyvinylidene fluoride, vinylidene fluoride - hexafluoropropylene polymer, epoxy resin, butadiene - acrylonitrile polymer, polyurethane rubber, poly(methyl acrylate), and poly(ethyl acrylate).

13. The electrode assembly according to claim 9, wherein, The base material of the insulating tape is polyethylene terephthalate, polyvinyl chloride, polyethylene or oriented polypropylene.

14. A battery cell, characterized in that, comprising a housing and an electrode assembly according to any one of claims 1 to 13; The electrode assembly is accommodated in the housing.

15. A battery, characterized in that: comprising a box body and a battery cell according to claim 14; The battery cells are accommodated in the box.

16. An electrical device, characterized in that, Including the battery according to claim 15.

17. A method for manufacturing an electrode assembly, characterized in that: The manufacturing method comprises: Provide positive electrode sheet, negative electrode sheet and barrier layer; Winding or folding the positive electrode sheet and the negative electrode sheet to form a bending area; The positive electrode sheet includes a plurality of bent portions located in the bent area, the bent portion includes a positive current collecting layer and a positive active material layer, the positive current collecting layer is provided with the positive active material layer on the inner side surface in the thickness direction of the positive electrode sheet, and the positive active material layer is provided on the outer side surface of the positive current collecting layer in the thickness direction; A barrier layer is provided between the positive electrode current collecting layer and the positive electrode active material layer, and the barrier layer is used to block the electron transmission between the positive electrode current collecting layer and the positive electrode active material layer; the barrier layer is provided between the positive electrode active material layer on the inner side and at least one bending portion is located, and the barrier layer is provided between the positive electrode active material layer on the outer side and the positive electrode current collecting layer.

18. The manufacturing method according to claim 17, characterized in that, A separator is provided for isolating the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the separator and the negative electrode sheet are wound or folded to form the bending area.

19. A manufacturing device for an electrode assembly, characterized in that, include: A first providing device is used to provide a positive electrode sheet; A second providing device is used to provide a negative electrode sheet; a third providing device for providing a barrier layer; as well as An assembling device, configured to wind or fold the positive electrode sheet and the negative electrode sheet to form a bending region; The positive electrode sheet includes a plurality of bent portions located in the bent area, the bent portion includes a positive current collecting layer and a positive active material layer, the positive current collecting layer is provided with the positive active material layer on the inner side surface in the thickness direction of the positive electrode sheet, and the positive active material layer is provided on the outer side surface of the positive current collecting layer in the thickness direction; A barrier layer is provided between the positive electrode current collecting layer and the positive electrode active material layer, wherein the barrier layer is used to block electron transmission between the positive electrode current collecting layer and the positive electrode active material layer; The barrier layer is provided between the positive electrode active material layer and the positive electrode current collecting layer on the inner side surface of at least one bend, and the barrier layer is provided between the positive electrode active material layer and the positive electrode current collecting layer on the outer side surface of at least one bend.

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