Battery cell, battery device, and electric device

Abstract

The application provides a battery monomer, a battery device and a power utilization device. The battery monomer comprises a shell and an electrode assembly. The electrode assembly is accommodated in the shell. The electrode assembly is in a winding shape. The electrode assembly has a flat area and a bending area. The bending area is arranged at the end of the flat area. The electrode assembly comprises a positive electrode sheet and a negative electrode sheet. The positive electrode sheet and the negative electrode sheet are opposite in polarity. The positive electrode sheet has a first end, which is located at the end of the outermost circle of the positive electrode sheet. The negative electrode sheet has a second end, which is located at the end of the outermost circle of the negative electrode sheet. At least one of the first end and the second end is arranged in the bending area. The battery monomer provided by the application is beneficial to reducing the risk of purple spots or lithium precipitation of the electrode sheet.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery cell, a battery device, and an electrical device. Background Technology

[0002] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0003] In the development of battery cell technology, in addition to improving the performance of battery cells, their reliability is also a crucial consideration. Therefore, improving the reliability of battery cells is a continuous challenge in battery cell technology. Utility Model Content

[0004] This application provides a battery cell, a battery device, and an electrical device to improve the reliability of the battery cell.

[0005] This application is achieved through the following technical solution:

[0006] In a first aspect, the battery cell provided in this application includes a casing and an electrode assembly. The electrode assembly is housed within the casing and is wound. The electrode assembly has a straight region and a bent region, with the bent region located at the end of the straight region. The electrode assembly includes a positive electrode and a negative electrode. The positive electrode has a first terminal end located at the end of the outermost ring of the positive electrode, and the negative electrode has a second terminal end located at the end of the outermost ring of the negative electrode. At least one of the first and second terminal ends is located in the bent region.

[0007] According to the battery cell provided in the embodiments of this application, by setting at least one of the first end of the positive electrode and the second end of the negative electrode in the bending region of the electrode assembly, and there is enough space between the bending region and the outer casing, there is enough space near the first end or the second end of the bending region. In this way, even if the gas generated by the battery cell during the cycle operation accumulates near the first end or the second end of the bending region, there is still enough electrolyte near the first end or the second end of the bending region for the transport of metal ions such as lithium ions. This helps to reduce the risk of purple spots or lithium plating on the electrode.

[0008] According to some embodiments of this application, the battery cell is an alkali metal battery or a sodium-ion battery.

[0009] In the above-mentioned scheme, during the cyclic operation of alkali metal batteries or sodium-ion batteries, the electrode assembly will generate a lot of gas, and more gas will accumulate near the first or second termination end. However, by setting at least one of the first and second termination ends in the bending region, the present application provides more space near the first or second termination end in the bending region to accommodate more gas and electrolyte, so as to facilitate the migration of metal ions such as sodium ions and reduce the risk of purple spots or sodium precipitation on the electrode sheet of the electrode assembly.

[0010] According to some embodiments of this application, the negative electrode sheet includes a negative current collector and an active material layer disposed on at least one side of the negative current collector, the active material layer including an elemental active metal.

[0011] In the above-mentioned scheme, the active material layer of the negative electrode sheet, including the active metal, will generate more gas during the cycle operation of the battery cell. More gas will accumulate near the first or second termination end. However, this application sets at least one of the first and second termination ends to be located in the bending region. Therefore, there is more space near the first or second termination end in the bending region to accommodate more gas and electrolyte, so as to facilitate the migration of metal ions such as sodium ions. This helps to reduce the risk of purple spots or sodium precipitation on the electrode sheet of the electrode assembly, thereby improving the reliability of the battery cell.

[0012] According to some embodiments of this application, the active metal element includes at least one of lithium, sodium, potassium, zinc, or aluminum.

[0013] In the above-mentioned scheme, when the active metal element includes at least one of lithium, sodium, potassium, zinc or aluminum, the battery cell will generate more gas during the cycle operation, and more gas will accumulate near the first or second termination end. However, by setting at least one of the first and second termination ends in the bending region, the present application provides more space near the first or second termination end in the bending region to accommodate more gas and electrolyte, so as to facilitate the migration of metal ions such as sodium ions. This helps to reduce the risk of purple spots or sodium precipitation on the electrode plates of the electrode assembly, thereby improving the reliability of the battery cell.

[0014] According to some embodiments of this application, the battery cell further includes an electrolyte, which includes a solvent, and the solvent includes at least one of an ether solvent or an ester solvent.

[0015] In the above scheme, ether solvents and ester solvents will generate hydrogen gas during the cycle of the battery cell. This application sets at least one of the first and second termination ends in the bending region, so that there is more space near the first or second termination end of the bending region to accommodate more gas and electrolyte, so as to facilitate the migration of metal ions such as sodium ions, which helps to reduce the risk of purple spots or sodium precipitation on the electrode plate of the electrode assembly, thereby providing reliable performance of the battery cell.

[0016] According to some embodiments of this application, the solvent includes ether solvents, which include at least one of 1,2-dimethoxypropane, dimethoxymethane, ethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, pentaethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, or 1,3-dioxane.

[0017] In the above-mentioned scheme, the ether solvent is compatible with various alkali metal batteries. During the cycling process of alkali metal batteries, hydrogen gas is generated. By setting at least one of the first and second termination ends in the bending region, there is more space near the first or second termination end in the bending region to accommodate more gas and electrolyte, so as to facilitate the migration of metal ions such as sodium ions. This helps to reduce the risk of purple spots or sodium precipitation on the electrode plates of the electrode assembly, thereby providing reliable performance of the battery cell.

[0018] According to some embodiments of this application, the battery cell is a pouch cell.

[0019] In the above scheme, the gas generated by the soft-pack battery cell during the formation or aging process is more difficult to be discharged to the outside of the casing than that of the hard-shell battery cell. By setting at least one of the first and second termination ends to be located in the bending area, when the gas generated by the electrode assembly accumulates at the first or second termination end of the bending area during the formation or aging process of the soft-pack battery cell, there is more electrolyte near the first or second termination end of the bending area, which facilitates the transport of metal ions such as lithium ions around the bubbles in the electrolyte. This helps to reduce the risk of purple spots or lithium plating on the electrode assembly of the soft-pack battery cell.

[0020] According to some embodiments of this application, the gap between the bending area and the outer shell is greater than the gap between the straight area and the outer shell.

[0021] In the above scheme, the bending area and the outer shell can accommodate more electrolyte and air bubbles. During the cycle of the battery cell, when the gas generated by the electrode assembly accumulates near the first end, it is beneficial to improve the smoothness and reliability of the transfer of metal ions such as lithium ions in the electrolyte, and further helps to reduce the risk of purple spots or lithium plating in the electrode assembly.

[0022] According to some embodiments of this application, the maximum gap between two adjacent loops of the electrode in the bending region is greater than the maximum gap between two adjacent loops of the electrode in the straight region.

[0023] In the above scheme, the interior of the bending region has a large space, which can accommodate more electrolyte and gas. This helps to reduce the amount of gas accumulated near the first or second end of the bending region and reduce the size of the bubbles near the first or second end, which facilitates the transport of metal ions such as lithium ions near the first or second end. This further helps to reduce the problem of lithium plating or purple spots in the electrode assembly.

[0024] According to some embodiments of this application, the first and second termination ends are located in the bending area.

[0025] In the above scheme, the first end of the positive electrode and the second end of the negative electrode are both located in the bending area, which helps to reduce the risk of lithium plating or purple spots on the electrodes adjacent to the first and second ends.

[0026] According to some embodiments of this application, along the winding direction of the electrode sheet, the outermost negative electrode sheet is positioned beyond the first end of the positive electrode sheet.

[0027] In the above scheme, along the winding direction of the electrode sheets, the outermost negative electrode sheet extends beyond the outermost end of the positive electrode sheet. In this way, during the charging process of the battery cell, there are always enough negative electrode sheets to receive the lithium ions released from the positive electrode sheet, which helps to further reduce the risk of lithium plating in the electrode assembly.

[0028] According to some embodiments of this application, the electrode assembly includes at least two bending regions, including a first bending region and a second bending region, with a first termination end located in the first bending region and a second termination end located in the second bending region.

[0029] In the above scheme, during battery cycling, it helps reduce the risk of excessive gas accumulation in the same bending area, further reducing the size of bubbles near the first or second termination point, and thus reducing the risk of purple spots or lithium plating on the electrode assembly. Furthermore, by placing the first and second termination points in different bending areas, it facilitates extending the outermost negative electrode beyond the outermost edge of the positive electrode, further reducing the risk of lithium plating on the electrode.

[0030] According to some embodiments of this application, along the winding direction of the electrode assembly, the negative electrode sheet extends beyond the positive electrode sheet, and the number of turns n1 of the negative electrode sheet extending beyond the positive electrode sheet satisfies: 0 < n1 < 5.

[0031] In the above scheme, the negative electrode is wound no more than 5 turns more than the positive electrode, and the first end of the positive electrode and the second end of the negative electrode are located in different bending areas. This helps to reduce the risk of lithium plating on the electrode while also improving the energy density of the battery cell.

[0032] According to some embodiments of this application, the electrode assembly includes a straight region and two bent regions, with the first bent region and the second bent region located at opposite ends of the straight region.

[0033] In the above scheme, the gas generated by the battery cell during the cycle accumulates near the first bending area and the second bending area, so that there is enough space between the first bending area and the second bending area and the outer casing to accommodate more gas. This helps to further reduce the amount of gas accumulated at the indentation of the electrode and further reduce the risk of purple spots or lithium plating on the electrode.

[0034] According to some embodiments of this application, the first and second termination ends are located in the same bending area.

[0035] In the above scheme, the first and second termination ends are located in the same bending area, which reduces the risk of purple spots or lithium plating on the electrode, and also makes it easier to control the size of the positive and negative electrode sheets, which helps to simplify the manufacturing process of the electrode assembly.

[0036] According to some embodiments of this application, a first termination end and a second termination end are spaced apart along the winding direction of the electrode assembly.

[0037] In the above scheme, the gas accumulated near the first end and the gas accumulated near the second end are spaced apart. This helps to reduce the size of the bubbles, improve the smoothness of lithium ion migration in the electrolyte, and further reduce the risk of lithium plating or purple spots on the electrode.

[0038] According to some embodiments of this application, along the winding direction of the electrode assembly, the number of turns n2 of the negative electrode sheet beyond the positive electrode sheet satisfies: 0.5 < n2 < 5.5.

[0039] In the above scheme, the negative electrode is wound more than half a turn but less than five and a half turns than the positive electrode. The first end of the positive electrode and the second end of the negative electrode are located in the same bending area and are spaced apart. In this way, the lithium ions and other metal ions released from the positive electrode are always received by the negative electrode. Furthermore, the spaced arrangement of the first end of the positive electrode and the second end of the negative electrode helps to further reduce the risk of lithium plating on the electrode of the battery cell.

[0040] According to some embodiments of this application, the negative electrode sheet includes a body segment and a folded segment. The folded segment is connected to the outermost end of the body segment, and a second termination end is located at the end of the folded segment away from the body segment. The body segment is wound up, and the folded segment is folded relative to the body segment.

[0041] In the above scheme, the folded section can increase the length of the negative electrode sheet, allowing it to exceed the length of the positive electrode sheet. This ensures that lithium ions released from the positive electrode sheet are always received by the negative electrode sheet, reducing the risk of lithium plating. Simultaneously, after the folded section is folded, the second end of the negative electrode sheet remains in the bending region, reducing the crease between the second end and adjacent electrodes. This helps reduce gas accumulation near the second end, further reducing the risk of lithium plating.

[0042] According to some embodiments of this application, the folded segment is located in the bending area.

[0043] In the above scheme, there is a lot of space between the bending area and the outer shell. By setting the folding section in the bending area and utilizing the extra space between the bending area and the outer shell, the structural stability of the folding section can be improved. It also eliminates the need to reserve more space for the folding section, making it easier to set up and improving the energy density of the battery cell.

[0044] According to some embodiments of this application, the number of folded layers n3 of the folded segment relative to the body segment satisfies: 1≤n3≤5.

[0045] In the above scheme, the number of folded sections n3 satisfies: 1≤n3≤5, which is beneficial to improve the energy density of the battery cell and reduce the risk of lithium plating on the electrode.

[0046] Secondly, the battery device provided in the embodiments of this application includes the battery cell provided in any of the above embodiments, and the battery cell is used to provide electrical energy.

[0047] The battery device 10 provided in this application embodiment has the same technical effect as the battery cell provided in any of the above embodiments, and will not be described again here.

[0048] Thirdly, the electrical device provided in the embodiments of this application includes the battery device provided in the above embodiments, and the battery device is used to provide electrical energy.

[0049] The power device provided in this application embodiment has the same technical effect as the battery device provided in any of the above embodiments, and will not be described again here.

[0050] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0051] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 A schematic diagram of the structure of a vehicle provided in an embodiment of this application;

[0053] Figure 2 This is a schematic diagram of the exploded structure of a battery device provided in an embodiment of this application;

[0054] Figure 3 This is a partial structural diagram of the battery module in the battery device provided in the embodiments of this application;

[0055] Figure 4 This is a schematic diagram of the exploded structure of a single battery cell provided in an embodiment of this application;

[0056] Figure 5 This is a schematic diagram of the structure of an electrode assembly in a battery cell provided in an embodiment of this application;

[0057] Figure 6 This is a schematic diagram of the structure of an electrode assembly in another battery cell provided in an embodiment of this application;

[0058] Figure 7 This is a schematic diagram of the structure of an electrode assembly in a battery cell provided in an embodiment of this application;

[0059] Figure 8 This is a schematic diagram of the structure of an electrode assembly in a battery cell provided in an embodiment of this application.

[0060] The accompanying drawings are not drawn to scale.

[0061] Explanation of reference numerals in the attached figures:

[0062] 1-Vehicle;

[0063] 10 - Battery assembly; 11 - Housing; 111 - First sub-housing; 112 - Second sub-housing;

[0064] 20-Battery Module;

[0065] 30-Battery cell; 31-Casing; 311-Shell; 312-End cap; 32-Electrode assembly; 32a-Bending area; 321a-First bending area; 322a-Second bending area; 32b-Straight area; 321-Electrode body; 322-Taper; 323-Positive electrode; 323a-First termination; 324-Negative electrode; 324a-Second termination; 3241-Body segment; 3242-Folded segment; 33-Electrode terminal;

[0066] X - Winding direction. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0068] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0069] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0070] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.

[0071] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0072] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0073] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0074] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0075] In this application, "multiple" refers to two or more (including two), and similarly, "multiple groups" refers to two or more (including two), and "multiple pieces" refers to two or more (including two).

[0076] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0077] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form a single module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0078] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0079] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0080] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0081] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0082] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0083] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0084] The battery cell may be, but is not limited to, lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc.

[0085] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0086] In some embodiments, the positive electrode can be a positive electrode sheet, which may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector.

[0087] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0088] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative current collector.

[0089] In some embodiments, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0090] In some embodiments, the diaphragm is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0091] As an example, the separator can be a single-layer thin film or a multi-layer composite thin film, without particular limitation. When the separator is a multi-layer composite thin film, the materials of each layer can be the same or different, without particular limitation. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0092] In some embodiments, the membrane is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0093] In some embodiments, the electrode assembly is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0094] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0095] In some embodiments, the housing includes an end cap and a casing, the casing having an opening, and the end cap closing the opening to form a sealed space for accommodating substances such as electrode assemblies and electrolytes. The casing may have one or more openings. The end cap may also be provided one or more times.

[0096] In some embodiments, electrode terminals are provided on the housing, and the electrode terminals are electrically connected to the tabs of the electrode assembly. The electrode terminals can be directly connected to the tabs or indirectly connected to the tabs through a current collector. The electrode terminals can be located on the end cap or on the housing.

[0097] In some implementations, an explosion-proof valve is provided on the housing. The explosion-proof valve is used to release the internal pressure of the battery cells.

[0098] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries. There are no particular limitations in the embodiments of this application.

[0099] In related technologies, the electrode assemblies of battery cells are typically formed through a winding process. During the winding process, the outermost ring of the electrode assembly usually has a terminal end. During the disassembly of problematic battery cells, the inventors discovered that some electrode terminals were prone to purple spots or lithium plating.

[0100] To address this, the inventors conducted a systematic analysis and a series of experiments, discovering that after the electrode assembly is wound, a shaping process typically results in a flat region and a bent region. The electrode sheets in the flat region are straight, while those in the bent region are bent. The ends of some electrode sheets are located in the flat region. During battery cell cycling, gas is inevitably generated, accumulating at the ends of the flat region. Since the space between the flat region and the outer casing is small, the electrolyte near the first end is insufficient when gas accumulates. During battery cell cycling, lithium ions and other metal ions cannot pass through the gas and embed into the electrode sheets covered by gas bubbles, affecting lithium ion transport. Insufficient lithium embedding in some areas of the electrode sheets causes purple spots, while some lithium ions cannot be accepted by the electrode sheets, resulting in lithium plating. This severely impacts the reliability of the battery cell.

[0101] In view of this, the battery cell provided in this application includes a casing and an electrode assembly. The electrode assembly is housed within the casing and is in a wound shape. The electrode assembly has a straight region and a bent region, with the bent region located at the end of the straight region. The electrode assembly includes a positive electrode and a negative electrode. The positive electrode has a first terminal end located at the end of the outermost ring of the positive electrode, and the negative electrode has a second terminal end located at the end of the outermost ring of the negative electrode. At least one of the first and second terminal ends is located in the bent region.

[0102] The battery cell provided in this application embodiment has at least one of the first terminal end of the positive electrode and the second terminal end of the negative electrode located in the bending region of the electrode assembly, and there is sufficient space between the bending region and the outer casing, so that there is enough space near the first terminal end or the second terminal end. In this way, even if the gas generated by the battery cell during cycle operation accumulates near the first terminal end or the second terminal end of the bending region, there is still enough electrolyte near the first terminal end or the second terminal end for the transport of metal ions such as lithium ions. This helps to reduce the risk of purple spots or lithium plating on the electrode.

[0103] The technical solutions described in the embodiments of this application are applicable to battery cells, battery devices including battery cells, and electrical devices using battery devices.

[0104] The battery device disclosed in this application can be used, but is not limited to, in electrical devices such as vehicles, ships, or aircraft. A power system for such an electrical device can be constructed using the battery device disclosed in this application.

[0105] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric bicycles, electric motorcycles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0106] For ease of explanation, the following embodiments will be described using a vehicle as an example of an electrical device according to an embodiment of this application.

[0107] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1 provided in an embodiment of this application. Vehicle 1 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 10 is installed inside vehicle 1, and the battery device 10 can be located at the bottom, front, or rear of vehicle 1. The battery device 10 can be used to power vehicle 1; for example, the battery device 10 can serve as the operating power source for vehicle 1's electrical system, such as meeting the power requirements for starting, navigation, and operation of vehicle 1.

[0108] The vehicle 1 may also include a controller 1b and a motor 1a. The controller 1b is used to control the battery device 10 to supply power to the motor 1a, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0109] In some embodiments of this application, the battery device 10 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0110] Please refer to Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the structure of the battery device 10 provided in the embodiments of this application. Figure 3This is a schematic diagram of the structure of the battery module 20 in the battery device 10 provided in this application embodiment. The battery device 10 includes a housing 11 and battery cells 30, with the battery cells 30 housed within the housing 11. The housing 11 provides space for the battery cells 30, and the housing 11 can adopt various structures.

[0111] In some embodiments, the housing 11 may include a first sub-housing 111 and a second sub-housing 112, the first sub-housing 111 and the second sub-housing 112 covering each other, the first sub-housing 111 and the second sub-housing 112 together defining a receiving space for accommodating the battery cell 30. The second sub-housing 112 may be a hollow structure with one end open, and the first sub-housing 111 may be a plate-like structure, the first sub-housing 111 covering the open side of the second sub-housing 112, so that the first sub-housing 111 and the second sub-housing 112 together define the receiving space; the first sub-housing 111 and the second sub-housing 112 may also be hollow structures with one side open, the open side of the first sub-housing 111 covering the open side of the second sub-housing 112.

[0112] In the battery device 10, there can be multiple battery cells 30, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 30 are connected in both series and parallel configurations. Multiple battery cells 30 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 30 is housed within the housing 11. Alternatively, the battery device 10 can also consist of multiple battery cells 30 first connected in series, parallel, or in a mixed manner to form a battery module 20, and then multiple battery modules 20 connected in series, parallel, or in a mixed manner to form a whole, which is also housed within the housing 11. The battery device 10 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 30.

[0113] Among them, the battery cell 30 can be a secondary battery or a primary battery; the battery cell 30 can also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited to these.

[0114] Please refer to Figure 4 , Figure 4 This is an exploded structural diagram of the battery cell 30 in the battery device 10 provided in this application embodiment. Figure 4 As shown, the battery cell 30 includes a housing 31, an electrode assembly 32, and electrode terminals 33. The housing 31 includes a casing 311 and an end cap 312. The casing 311 has an opening, and the end cap 312 closes the opening to isolate the internal environment of the battery cell 30 from the external environment.

[0115] The housing 311 is an assembly used to cooperate with the end cap 312 to form the internal environment of the battery cell 30, wherein the formed internal environment can accommodate the electrode assembly 32, the electrolyte, and other components. The housing 311 and the end cap 312 can be independent components. The housing 311 can have various shapes and sizes. Specifically, the shape of the housing 311 can be determined according to the specific shape and size of the electrode assembly 32. The housing 311 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, and plastic.

[0116] End cap 312 refers to a component that covers the opening of housing 311 to isolate the internal environment of battery cell 30 from the external environment. The shape of end cap 312 can be adapted to the shape of housing 311 to fit it. Optionally, end cap 312 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 312 is not easily deformed under pressure and impact, giving battery cell 30 higher structural strength and improved reliability. Functional components such as electrode terminals 33 can be provided on end cap 312. Electrode terminals 33 can be used for electrical connection with electrode assembly 32 to output or input electrical energy to battery cell 30. The material of end cap 312 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose special limitations on this. In some embodiments, an insulating structure may be provided on the inner side of the end cap 312. The insulating structure can be used to isolate the electrical connection components within the housing 311 from the end cap 312 to reduce the risk of short circuits. For example, the insulating structure may be made of plastic, rubber, etc.

[0117] Electrode assembly 32 is the component in the battery cell 30 where electrochemical reactions occur. The housing 311 may contain one or more electrode assemblies 32. The electrode assembly 32 is mainly formed by winding positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets to separate them and prevent internal short circuits. The portions of the positive and negative electrode sheets containing active material constitute the electrode body 321 of the electrode assembly 32, while the portions of the positive and negative electrode sheets without active material each constitute a tab 322. The positive and negative tabs may be located together at one end of the electrode body 321 or separately at both ends of the electrode body 321. During the charging and discharging process of the battery cell 30, the positive and negative active materials react with the electrolyte, and the tabs 322 connect to the electrode terminals 33 to form a current loop.

[0118] Firstly, such as Figure 4 and Figure 5As shown, the battery cell 30 provided in this application includes a housing 31 and an electrode assembly 32. The electrode assembly 32 is housed within the housing 31 and is in a wound shape. The electrode assembly 32 has a straight region 32b and a bending region 32a, with the bending region 32a located at the end of the straight region 32b. The electrode assembly 32 includes a positive electrode 323 and a negative electrode 324. The positive electrode 323 has a first terminal end 323a located at the end of the outermost ring of the positive electrode 323. The negative electrode 324 has a second terminal end 324a located at the end of the outermost ring of the negative electrode 324. At least one of the first terminal end 323a and the second terminal end 324a is located in the bending region 32a.

[0119] The electrode assembly 32 may include multiple electrode sheets, which are wound together to form the electrode assembly 32. The electrode sheets include positive electrode sheets and negative electrode sheets. If the electrode assembly 32 is wound, the positive electrode sheets and negative electrode sheets of the electrode assembly 32 are wound together along the winding direction X.

[0120] The electrode assembly 32 has a flat region 32b and a bent region 32a. The electrode sheet in the flat region 32b can be flat, while the electrode sheet in the bent region 32a can be bent. Thus, during the winding process of the electrode assembly 32, the electrode assembly 32 can be shaped, such as by performing a hot pressing process to form the flat region 32b.

[0121] The bending region 32a is located at the end of the straight region 32b. Optionally, the straight region 32b may have a bending region 32a at one end, or bending regions 32a may be provided at both opposite ends of the straight region 32b. Optionally, an electrode assembly 32 may have one, two, or more bending regions 32a.

[0122] Similarly, the electrode assembly 32 may have one or more flat regions 32b. For example, after the electrode assembly 32 is wound, it can be hot-pressed in one direction to form a flat region 32b and bending regions 32a connecting the two sides of the flat region 32b. Alternatively, after the electrode assembly 32 is wound, it can be hot-pressed in two mutually perpendicular directions to form multiple flat regions 32b and multiple bending regions 32a connecting adjacent flat regions 32b, wherein the electrode sheets in two flat regions 32b connected to the same bending region 32a are perpendicular to each other. Of course, the electrode assembly 32 can also be other irregularly shaped structural forms.

[0123] For a battery cell 30 with a flat region 32b and a bent region 32a, the outer casing 31 can be square. In this way, there is usually a large space between the bent region 32a and the outer casing 31, and more electrolyte can be accommodated between the bent region 32a and the outer casing 31.

[0124] The battery cell 30 may also include an electrolyte, which is disposed inside the housing 31 and serves as a channel for the transport of metal ions such as lithium ions during the cyclic operation of the battery cell 30.

[0125] If at least one of the first terminal end 323a of the positive electrode 323 and the second terminal end 324a of the negative electrode 324 is located in the bending region 32a, then optionally, either the first terminal end 323a or the second terminal end 324a may be located in the bending region 32a, or both the first terminal end 323a and the second terminal end 324a may be located in the bending region 32a. The electrode assembly 32 may include multiple positive electrode 323s or multiple negative electrode 324s, and at least one of the multiple first terminal ends 323a and multiple second terminal ends 324a may be located in the bending region 32a, or both the multiple first terminal ends 323a and multiple second terminal ends 324a may be located in the bending region 32a.

[0126] The first termination end 323a or the second termination end 324a compresses the adjacent electrode sheet it is attached to, causing creases in the adjacent electrode sheet. During the cycle operation of the battery cell 30, especially during the formation or aging process, the electrode assembly 32 generates a large amount of gas. This gas accumulates near the creases formed by the first termination end 323a or the second termination end 324a on the adjacent electrode sheet and forms bubbles in the electrolyte. Because there is a large space between the bending area 32a and the outer casing 31, even if the gas generated by the electrode assembly 32 accumulates near the first termination end 323a or the second termination end 324a of the bending area 32a, there is still enough electrolyte near the first termination end 323a or the second termination end 324a for the transport of lithium ions and other metal ions. Lithium ions and other metal ions can bypass the bubbles and repeatedly detach and embed between the positive electrode sheet 323 and the negative electrode sheet 324. This helps to reduce the risk of purple spots or lithium plating on the electrode sheet of the electrode assembly 32.

[0127] Optionally, the battery cell 30 can be a pouch battery cell, or the battery cell 30 can be a prismatic battery cell or a cylindrical battery cell.

[0128] It is understood that the electrode assembly 32 may include multiple positive electrode plates 323, and the multiple first terminal ends 323a of the multiple positive electrode plates 323 may be located in the same bending region 32a, or the first terminal ends 323a of different positive electrode plates 323 may be located in different bending regions 32a.

[0129] The electrode assembly 32 may include multiple negative electrode plates 324. Multiple second terminal ends 324a of the multiple negative electrode plates 324 may be located in the same bending region 32a, or the second terminal ends 324a of different negative electrode plates 324 may be located in different bending regions 32a.

[0130] The first termination end 323a and the second termination end 324a can be set in the same bending area 32a, or the first termination end 323a and the second termination end 324a can be located in different bending areas 32a. The specific settings can be made according to actual needs.

[0131] The battery cell 30 provided in this application embodiment has at least one of the first terminal end 323a of the positive electrode 323 and the second terminal end 324a of the negative electrode 324 located in the bending region 32a of the electrode assembly 32. There is sufficient space between the bending region 32a and the outer casing 31, so that there is sufficient space near the first terminal end 323a or the second terminal end 324a of the bending region 32a. Thus, even if the gas generated by the battery cell 30 during cyclic operation accumulates near the first terminal end 323a or the second terminal end 324a of the bending region 32a, there is still sufficient electrolyte near the first terminal end 323a or the second terminal end 324a of the bending region 32a for the transport of metal ions such as lithium ions. This helps to reduce the risk of purple spots or lithium plating on the electrode.

[0132] In some embodiments, the battery cell 30 is an alkali metal battery or a sodium-ion battery.

[0133] Alkali metal batteries are batteries that achieve cycling by depositing and consuming alkali metal on the negative electrode 324. Taking sodium metal batteries as an example, a layer of sodium metal can be pre-formed on the negative electrode 324 during preparation, or a sodium metal layer can be deposited during charging of the alkali metal battery without pre-forming it. Because sodium alkali metal is formed during cycling, it is relatively active and will react with the electrolyte, producing a large amount of gas, and the proportion of H2 in the gas is >90%. Hydrogen gas remains in the alkali metal battery, which may pose a risk of thermal runaway.

[0134] Sodium-ion batteries achieve cyclic charging or discharging by repeatedly inserting and deintercalating sodium ions between the positive electrode 323 and the negative electrode 324. When the alkali metal battery is a sodium metal battery, it is also a sodium-ion battery.

[0135] Therefore, during the cyclic operation of alkali metal batteries or sodium-ion batteries, the electrode assembly 32 will generate more gas, and more gas will accumulate near the first termination end 323a or the second termination end 324a. By setting at least one of the first termination end 323a and the second termination end 324a in the bending region 32a, there is more space near the first termination end 323a or the second termination end 324a in the bending region 32a to accommodate more gas and electrolyte, so as to facilitate the migration of metal ions such as sodium ions, which helps to reduce the risk of purple spots or sodium precipitation on the electrode sheet of the electrode assembly 32.

[0136] In some embodiments, the negative electrode 324 includes a negative current collector and an active material layer disposed on at least one side of the negative current collector, the active material layer including an elemental active metal.

[0137] An active metal is a metal that can provide active metal ions. For example, the active metal in a lithium-alkali metal battery is elemental lithium, and the active metal in a sodium-alkali metal battery is elemental sodium. Specifically, an alkali metal battery is a battery that uses an active metal as the negative electrode, and the active metal can include lithium metal, sodium metal, etc.

[0138] In the aforementioned types of alkali metal batteries, the active metal ions such as lithium and sodium on the negative electrode 324 are relatively active and will undergo side reactions with water, solvent in the electrolyte and residual alkali in the positive electrode active material, resulting in a large amount of gas production, and the proportion of H2 in the gas is >90%.

[0139] For battery cells 30 whose active material layer of negative electrode 324 includes active metal, a large amount of gas is generated during cycle operation. More gas accumulates near the first termination end 323a or the second termination end 324a. By setting at least one of the first termination end 323a and the second termination end 324a to be located in the bending region 32a, there is more space near the first termination end 323a or the second termination end 324a in the bending region 32a to accommodate more gas and electrolyte, so as to facilitate the migration of metal ions such as sodium ions. This helps to reduce the risk of purple spots or sodium precipitation on the electrode assembly 32, thereby improving the reliability of the battery cell 30.

[0140] In some embodiments, the active metal element includes at least one of lithium, sodium, potassium, zinc, or aluminum.

[0141] Thus, alkali metal batteries include at least one of lithium metal batteries, sodium metal batteries, potassium metal batteries, zinc metal batteries, or aluminum metal batteries. The active metal ions in these alkali metal batteries are relatively reactive and will undergo side reactions with the electrolyte, producing a large amount of gas, with H2 comprising >90% of the gas.

[0142] Therefore, when the active metal element includes at least one of lithium, sodium, potassium, zinc, or aluminum, the battery cell 30 will generate more gas during cycle operation, and more gas will accumulate near the first termination end 323a or the second termination end 324a. By setting at least one of the first termination end 323a and the second termination end 324a in the bending region 32a, there is more space near the first termination end 323a or the second termination end 324a in the bending region 32a to accommodate more gas and electrolyte, so as to facilitate the migration of metal ions such as sodium ions. This helps to reduce the risk of purple spots or sodium precipitation on the electrode sheet of the electrode assembly 32, thereby providing reliable performance of the battery cell 30.

[0143] In some embodiments, the battery cell 30 further includes an electrolyte, which includes a solvent, and the solvent includes at least one of an ether solvent or an ester solvent.

[0144] Ether solvents refer to organic solvents containing ether groups, and ester solvents refer to organic solvents containing ester groups. During the cycling process of battery cell 30, ether solvents and ester solvents will generate hydrogen gas. This application sets at least one of the first termination end 323a and the second termination end 324a to be located in the bending region 32a. Therefore, there is more space near the first termination end 323a or the second termination end 324a in the bending region 32a to accommodate more gas and electrolyte, so as to facilitate the migration of metal ions such as sodium ions. This helps to reduce the risk of purple spots or sodium precipitation on the electrode sheet of the electrode assembly 32, thereby providing reliable performance of battery cell 30.

[0145] In some embodiments, the solvent includes ether solvents, which include at least one of 1,2-dimethoxypropane, dimethoxymethane, ethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, pentaethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, or 1,3-dioxane.

[0146] The aforementioned ether solvents are compatible with various alkali metal batteries. During the cycling process of alkali metal batteries, hydrogen gas is generated. This application sets at least one of the first termination end 323a and the second termination end 324a to be located in the bending region 32a. This provides more space near the first termination end 323a or the second termination end 324a in the bending region 32a to accommodate more gas and electrolyte, which facilitates the migration of metal ions such as sodium ions. This helps reduce the risk of purple spots or sodium precipitation on the electrode assembly 32, thereby providing reliable performance for the battery cell 30.

[0147] In some embodiments, the battery cell 30 is a pouch cell.

[0148] The outer casing 31 of the pouch cell includes aluminum foil. Exemplarily, the outer casing 31 of the pouch cell may include aluminum foil and a polymer film disposed on the side of the aluminum foil facing away from the electrode assembly. In this way, the outer casing 31 of the pouch cell is relatively soft, and under the action of positive or negative pressure inside the outer casing 31, the outer casing 31 will undergo corresponding deformation.

[0149] For hard-shell battery cells 30 such as those with aluminum or steel casings, the gas generated during formation or aging can be extracted to the outside of the casing 31 through negative pressure. However, for soft-pack battery cells, the casing 31 is made of a softer material and is prone to deformation under negative pressure, making it difficult to expel the gas inside the battery cell 30 through negative pressure.

[0150] Therefore, for pouch cell, the gas generated during formation or aging is more difficult to escape to the outside of the casing 31 compared to hard-shell cell 30. By setting at least one of the first termination end 323a and the second termination end 324a to be in the bending region 32a, during the formation or aging of the pouch cell, when the gas generated by the electrode assembly 32 accumulates in the first termination end 323a or the second termination end 324a in the bending region, there is more electrolyte near the first termination end 323a or the second termination end 324a in the bending region 32a. This facilitates the transport of metal ions such as lithium ions around the bubbles in the electrolyte, which helps to reduce the risk of purple spots or lithium plating on the electrode assembly 32 of the pouch cell.

[0151] In some embodiments, the gap between the bending region 32a and the outer shell 31 is greater than the gap between the straight region 32b and the outer shell 31.

[0152] Since the gap between the bending region 32a and the outer shell 31 is larger than the gap between the straight region 32b and the outer shell 31, the space between the bending region 32a and the outer shell 31 of the electrode assembly 32 is also larger than the gap between the straight region 32b and the outer shell 31. Thus, the space between the bending region 32a and the outer shell 31 can accommodate more electrolyte and air bubbles. During the cycling process of the battery cell 30, if the gas generated by the electrode assembly 32 accumulates near the first terminal 323a, it helps improve the smoothness and reliability of the transfer of lithium ions and other metal ions in the electrolyte, further reducing the risk of purple spots or lithium plating on the electrode assembly 32.

[0153] In some embodiments, the maximum gap between two adjacent turns of the electrode in the bending region 32a is greater than the maximum gap between two adjacent turns of the electrode in the straight region 32b.

[0154] Optionally, the maximum gap between two adjacent electrode rings can be obtained using CT (Computed Tomography) scanning. Specifically, an image of the end face of the electrode assembly can be obtained using a CT scanner, and the gap between two adjacent electrode rings can be determined by measuring the image.

[0155] The maximum gap between two adjacent loops of the electrode in the bending region 32a can be the maximum gap between any two adjacent loops of the electrode in the bending region 32a. Similarly, the maximum gap between two adjacent loops of the electrode in the straight region 32b can be the maximum gap between any two adjacent loops of the electrode in the straight region 32b.

[0156] Since the maximum gap between the electrodes in the bending region 32a is greater than the maximum gap between the electrodes in the straight region 32b, the interior of the bending region 32a has a larger space, which can accommodate more electrolyte and gas. This helps to reduce the amount of gas accumulated near the first termination end 323a or the second termination end 324a of the bending region 32a, and reduces the size of the bubbles near the first termination end 323a or the second termination end 324a. This facilitates the transport of metal ions such as lithium ions near the first termination end 323a or the second termination end 324a of the bending region 32a, and further helps to reduce the problem of lithium plating or purple spots in the electrode assembly 32.

[0157] In some embodiments, such as Figure 6 As shown, the first termination end 323a and the second termination end 324a are located in the bending area 32a.

[0158] Optionally, the second termination end 324a and the first termination end 323a may be located in the same bending area 32a, or the second termination end 324a and the first termination end 323a may be located in different bending areas 32a.

[0159] Thus, the first end 323a of the positive electrode 323 and the second end 324a of the negative electrode 324 are both located in the bending region 32a, which helps to reduce the risk of lithium plating or purple spots on the electrodes adjacent to the first end 323a and the second end 324a.

[0160] In some embodiments, such as Figure 6 As shown, along the winding direction X of the electrode sheet, the outermost negative electrode sheet 324 is positioned beyond the first end 323a of the positive electrode sheet 323.

[0161] Thus, along the winding direction X of the electrode, the outermost negative electrode 324 extends beyond the outermost end of the positive electrode 323. In this way, during the charging process of the battery cell 30, there are always enough negative electrode 324 to receive the lithium ions and other metal ions released from the positive electrode 323, which helps to further reduce the risk of lithium plating in the electrode assembly 32.

[0162] In some embodiments, such as Figure 6 As shown, the electrode assembly 32 includes at least two bending regions 32a, which include a first bending region 321a and a second bending region 322a. A first termination end 323a is located in the first bending region 321a, and a second termination end 324a is located in the second bending region 322a.

[0163] Thus, since the first termination end 323a and the second termination end 324a are located in different bending regions 32a, the creases caused by the compression of adjacent electrode sheets by the first termination end 323a and the second termination end 324a are located in different bending regions 32a. During battery cycling, this helps reduce the risk of excessive gas accumulation in the same bending region 32a, further reducing the size of bubbles near the first termination end 323a or the second termination end 324a, and reducing the risk of purple spots or lithium plating on the electrode assembly 32.

[0164] Furthermore, by placing the first termination end 323a and the second termination end 324a in different bending regions 32a, it is easier to make the outermost negative electrode 324 extend beyond the outermost end of the positive electrode 323, which helps to further reduce the risk of lithium plating on the electrode.

[0165] In some embodiments, such as Figure 6 As shown, along the winding direction X of the electrode assembly 32, the negative electrode 324 extends beyond the positive electrode 323, and the number of turns n1 of the negative electrode 324 extending beyond the positive electrode 323 satisfies: 0 < n1 < 5.

[0166] The negative electrode 324 is wound no more than 5 turns more than the positive electrode 323, and the first end 323a of the positive electrode 323 and the second end 324a of the negative electrode 324 are respectively located in different bending regions 32a. This helps to reduce the risk of lithium plating on the electrode while also improving the energy density of the battery cell 30.

[0167] In some embodiments, such as Figure 6 As shown, the electrode assembly 32 includes a straight region 32b and two bent regions 32a, with the first bent region 321a and the second bent region 322a located at opposite ends of the straight region 32b.

[0168] Thus, the first end 323a creates an indentation on the adjacent electrode in the first bending region 321a, and the second end 324a creates an indentation on the adjacent electrode in the second bending region 322a. The gas generated by the battery cell 30 during the cycle accumulates near the first bending region 321a and the second bending region 322a, so that there is enough space between the first bending region 321a and the second bending region 322a and the outer casing 31 to accommodate more gas. This helps to further reduce the amount of gas accumulated at the indentation of the electrode and further reduce the risk of purple spots or lithium plating on the electrode.

[0169] In some embodiments, such as Figure 7 As shown, the first termination end 323a and the second termination end 324a are located in the same bending area 32a.

[0170] Optionally, the first termination end 323a and the second termination end 324a can be aligned with each other, or the first termination end 323a and the second termination end 324a can be spaced apart from each other.

[0171] The first end 323a and the second end 324a are located in the same bending area 32a. This reduces the risk of purple spots or lithium plating on the electrode, and also makes it easier to control the size of the positive electrode 323 and the negative electrode 324, which helps to simplify the manufacturing process of the electrode assembly 32.

[0172] In some embodiments, such as Figure 7 As shown, along the winding direction X of the electrode assembly 32, the first end 323a and the second end 324a are spaced apart.

[0173] The first termination end 323a and the second termination end 324a are spaced apart. The indentations of the first termination end 323a and the second termination end 324a on the adjacent electrode are spaced apart. During the cycle operation of the battery cell 30, the gas generated accumulates near the first termination end 323a and the second termination end 324a. The gas accumulated near the first termination end 323a and the gas accumulated near the second termination end 324a are spaced apart. This helps to reduce the size of the bubbles, improve the smoothness of lithium ion migration in the electrolyte, and further reduce the risk of lithium plating or purple spots on the electrode.

[0174] In some embodiments, along the winding direction X of the electrode assembly 32, the number of turns n2 of the negative electrode 324 beyond the positive electrode 323 satisfies: 0.5 < n2 < 5.5.

[0175] Thus, along the winding direction X of the electrode assembly 32, the negative electrode 324 is wound more than half a turn and less than five and a half turns more than the positive electrode 323. The first end 323a of the positive electrode 323 and the second end 324a of the negative electrode 324 are located in the same bending area 32a and are spaced apart. In this way, the lithium ions and other metal ions released from the positive electrode 323 are always received by the negative electrode 324. The spaced arrangement of the first end 323a of the positive electrode 323 and the second end 324a of the negative electrode 324 helps to further reduce the risk of lithium plating on the electrodes of the battery cell 30.

[0176] In some embodiments, such as Figure 8 The negative electrode 324 includes a body segment 3241 and a folded segment 3242. The folded segment 3242 is connected to the outermost end of the body segment 3241, and a second termination end 324a is located at the end of the folded segment 3242 away from the body segment 3241. The body segment 3241 is wound up, and the folded segment 3242 is folded relative to the body segment 3241.

[0177] The folded section 3242 increases the length of the negative electrode 324, allowing it to exceed the length of the positive electrode 323. This ensures that lithium ions and other metal ions released from the positive electrode 323 are always received by the negative electrode 324, reducing the risk of lithium plating. Simultaneously, after folding, the second end 324a of the negative electrode 324 remains within the bending region 32a, reducing the creases on adjacent electrodes and minimizing gas accumulation near the second end 324a, further reducing the risk of lithium plating.

[0178] In some embodiments, please continue reading Figure 8 Folded section 3242 is located in bending area 32a.

[0179] Since there is ample space between the bending area 32a and the outer casing 31, the folding section 3242 is placed in the bending area 32a. The arrangement of the folding section 3242 utilizes the extra space between the bending area 32a and the outer casing 31, which helps to improve the structural stability of the folding section 3242. Furthermore, it eliminates the need to reserve more space for the folding section 3242, making its arrangement easier and also helping to improve the energy density of the battery cell 30.

[0180] In some embodiments, the number of layers n3 of the folded segment 3242 folded relative to the body segment 3241 satisfies: 1≤n3≤5.

[0181] Optionally, n3 can be 1, 2, 3, 4, or 5, etc.

[0182] Understandably, the higher the value of n3, the longer the negative electrode 324 extends beyond the positive electrode 323, which is more conducive to reducing the risk of lithium plating on the electrode. Conversely, the lower the value of n3, the more conducive it is to reducing the space occupied by the folded section 3242, thereby improving the energy density of the battery cell 30.

[0183] Therefore, after systematic analysis and long-term practice, the inventors found that setting the number of layers n3 of the folded segment 3242 satisfies: 1≤n3≤5, which is beneficial to improving the energy density of the battery cell 30 while also reducing the risk of lithium plating on the electrode.

[0184] Secondly, the battery device 10 provided in the embodiments of this application includes the battery cell 30 provided in any of the above embodiments, and the battery cell 30 is used to provide electrical energy.

[0185] The battery device 10 provided in this application embodiment has the same technical effect as the battery cell 30 provided in any of the above embodiments, and will not be described again here.

[0186] Thirdly, the power supply device provided in the embodiments of this application includes the battery device 10 provided in the above embodiments, and the battery device 10 is used to provide electrical energy.

[0187] The power supply device provided in this application has the same technical effect as the battery device 10 provided in any of the above embodiments, and will not be described again here.

[0188] In some embodiments, such as Figures 4 to 8 As shown, the battery cell 30 includes a housing 31 and an electrode assembly 32. The electrode assembly 32 is housed within the housing 31 and is in a wound shape. The electrode assembly 32 has a straight section 32b and a bent section 32a, with the bent section 32a located at the end of the straight section 32b. The electrode assembly 32 includes a positive electrode 323 and a negative electrode 324. The positive electrode 323 has a first terminal end 323a, and the negative electrode 324 has a second terminal end 324a. The first terminal end 323a is located at the end of the outermost ring of the positive electrode 323, and the second terminal end 324a is located at the end of the outermost ring of the negative electrode 324. Both the first terminal end 323a and the second terminal end 324a are located in the bent section 32a. The battery cell 30 is a pouch battery cell, and the gap between the bent section 32a and the housing 31 is greater than the gap between the straight section 32b and the housing 31. The gap between two adjacent turns of the electrode in the bending region 32a is greater than the gap between two adjacent turns of the electrode in the straight region 32b. Along the winding direction X of the electrode, the outermost negative electrode 324 extends beyond the first end 323a of the positive electrode 323.

[0189] The battery cell 30 provided in this application embodiment has a first terminal end 323a of the positive electrode 323 and a second terminal end 324a of the negative electrode 324 located in the bending region 32a of the electrode assembly 32. There is enough space between the bending region 32a and the outer casing 31, so that there is enough space near the first terminal end 323a and the second terminal end 324a. In this way, even if the gas generated by the battery cell 30 during cycle operation accumulates near the first terminal end 323a and the second terminal end 324a, there is still enough electrolyte near the first terminal end 323a and the second terminal end 324a for the transport of metal ions such as lithium ions. This helps to reduce the risk of purple spots or lithium plating on the electrode.

[0190] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, include: shell; An electrode assembly is housed within the housing. The electrode assembly has a wound structure and has a straight section and a bent section, with the bent section located at the end of the straight section. The electrode assembly includes a positive electrode and a negative electrode. The positive electrode has a first terminal end located at the end of the outermost ring of the positive electrode. The negative electrode has a second terminal end located at the end of the outermost ring of the negative electrode. At least one of the first terminal end and the second terminal end is located in the bending region.

2. The battery cell as described in claim 1, characterized in that, The battery cell is an alkali metal battery or a sodium-ion battery.

3. The battery cell as described in claim 2, characterized in that, The negative electrode sheet includes a negative current collector and an active material layer disposed on at least one side of the negative current collector, wherein the active material layer includes an elemental active metal.

4. The battery cell according to claim 3, characterized in that, The active metal element includes one of lithium, sodium, potassium, zinc, or aluminum.

5. The battery cell according to claim 1, characterized in that, Also includes: An electrolyte, wherein the electrolyte includes a solvent, and the solvent includes at least one of an ether solvent or an ester solvent.

6. The battery cell according to claim 5, characterized in that, The solvent includes ether solvents, which include one of 1,2-dimethoxypropane, dimethoxymethane, ethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, pentaethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, or 1,3-dioxopentane.

7. The battery cell according to claim 1, characterized in that, The battery cell is a pouch cell.

8. The battery cell according to claim 1, characterized in that, The gap between the bending area and the outer shell is greater than the gap between the straight area and the outer shell.

9. The battery cell according to claim 1, characterized in that, The maximum gap between two adjacent loops of the electrode in the bending region is greater than the maximum gap between two adjacent loops of the electrode in the straight region.

10. The battery cell according to any one of claims 1 to 9, characterized in that, Both the first and second termination ends are located in the bending area.

11. The battery cell according to claim 10, characterized in that, Along the winding direction of the electrode sheets, the outermost negative electrode sheet extends beyond the first end of the positive electrode sheet.

12. The battery cell according to claim 10, characterized in that, The electrode assembly includes at least two bending regions, each including a first bending region and a second bending region, wherein the first termination end is located in the first bending region and the second termination end is located in the second bending region.

13. The battery cell according to claim 12, characterized in that, Along the winding direction of the electrode assembly, the negative electrode extends beyond the positive electrode, and the number of turns n1 by which the negative electrode extends beyond the positive electrode satisfies: 0 < n1 < 5.

14. The battery cell according to claim 12, characterized in that, The electrode assembly includes a straight region and two bent regions, with the first bent region and the second bent region located at opposite ends of the straight region.

15. The battery cell according to claim 10, characterized in that, The first and second termination ends are located in the same bending area.

16. The battery cell according to claim 15, characterized in that, Along the winding direction of the electrode assembly, the first and second termination ends are spaced apart.

17. The battery cell according to claim 15, characterized in that, Along the winding direction of the electrode assembly, the number of turns n2 of the negative electrode sheet beyond the positive electrode sheet satisfies: 0.5 < n2 < 5.

5.

18. The battery cell according to claim 15, characterized in that, The negative electrode sheet includes a body section and a folded section. The folded section is connected to the outermost end of the body section, and the second tail end is located at the end of the folded section away from the body section. The main body segment is wound up, and the folded segment is folded relative to the main body segment.

19. The battery cell according to claim 18, characterized in that, The folded section is located in the bending area.

20. The battery cell according to any one of claims 18 to 19, characterized in that, The number of folds n3 of the folded segment relative to the main body segment satisfies: 1≤n3≤5.

21. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1 to 20.

22. An electrical appliance, characterized in that, Includes the battery device as described in claim 21, wherein the battery device is used to provide electrical energy.

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