Battery cell, battery device, and electric device

Abstract

The application relates to the battery technical field, and provides a battery monomer, a battery device and a power utilization equipment. The battery monomer comprises a shell, an electrode assembly and a cladding piece. The electrode assembly is arranged in the shell; wherein the electrode assembly comprises a first pole piece, a second pole piece and a separator; one of the first pole piece and the second pole piece is a positive pole piece, and the other is a negative pole piece; the separator is arranged between the first pole piece and the second pole piece; the first pole piece, the separator and the second pole piece are stacked and wound; the cladding piece is wrapped on the outer ring of the electrode assembly; the cladding piece is wrapped on more than one ring of the electrode assembly; the first pole piece, the separator and the second pole piece are stacked and wound, so that the electrode assembly forms a flat area and a bending area connected to both ends of the flat area; the end position of the cladding piece and the starting position of the cladding piece form an overlapping area along the winding direction of the cladding piece, and the overlapping area is at least partially located in the bending area. The cladding piece can limit the rebound force of the bending area, and reduce the possibility of pole piece fracture and lithium precipitation.

Description

Technical Field

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

[0002] In related technologies, a battery cell includes a casing and electrodes. Electrode expansion can lead to breakage and lithium plating. For example, a large gap may exist between the outermost positive and negative electrodes. When the electrodes expand and press against the casing, it may cause electrode breakage and lithium plating, affecting the battery cell's lifespan and reliability. Utility Model Content

[0003] In view of this, embodiments of this application provide a battery cell, a battery device, and an electrical appliance that can reduce the possibility of electrode breakage and lithium plating.

[0004] The technical solution of this application embodiment is implemented as follows:

[0005] This application provides a single battery cell, including:

[0006] case;

[0007] Electrode assembly, disposed within the housing;

[0008] Covering components;

[0009] The electrode assembly includes a first electrode, a second electrode, and a separator. One of the first electrode and the second electrode is a positive electrode, and the other is a negative electrode. The separator is disposed between the first electrode and the second electrode. The first electrode, the separator, and the second electrode are stacked and wound together. The covering member covers the outer ring of the electrode assembly, and the covering member covers the electrode assembly more than one turn.

[0010] The first electrode, the separator, and the second electrode are stacked and wound together to form a flat region and a bent region connecting the two ends of the flat region in the electrode assembly;

[0011] The end position of the covering and the beginning position of the covering form an overlapping area along the winding direction of the covering, and the overlapping area is at least partially located in the bending area.

[0012] In this embodiment, after the covering material is wound once, it continues winding beyond the starting position. The overlapping area should not be interpreted as the entire length of the covering material winding beyond the first turn, but rather the portion from the starting position to the ending position of the covering material when it is less than one turn in the last winding. The covering material can restrain the electrode assembly, limiting the increase in gap between the electrodes and the relative displacement of the electrodes during long-term cycling and storage. This reduces the possibility of electrode expansion causing the top shell of the electrodes, reduces the possibility of electrode breakage and lithium plating, and can improve the service life and reliability of the battery cells. The bending area has the greatest rebound force, and the gap between the first and second electrodes is relatively likely to change. The overlapping area is at least partially located in the bending area, which can limit the rebound force of the bending area, increase the covering force of the electrode assembly, make the electrode assembly structure compact, and reduce the possibility of electrode assembly deformation caused by electrode expansion.

[0013] In some embodiments, the starting position and the ending position of the covering are both located in the bending area.

[0014] In this embodiment, the starting and ending positions of the covering are located in the bending area, which can further enhance the covering effect of the covering on the electrode assembly and reduce the possibility of displacement of the first and second electrodes due to the spring force in the bending area.

[0015] In some embodiments, the length of the overlapping region is greater than or equal to 1 mm.

[0016] In this embodiment, the length of the overlapping area is greater than or equal to 1 mm, which can reduce the possibility of displacement of the coating due to electrode expansion and improve the reliability of the coating. For example, when the coating is adhesive tape, a preset length of greater than or equal to 1 mm can reduce the possibility of the adhesive tape detaching from the electrode assembly due to electrode expansion.

[0017] In some embodiments, the thickness of the covering is 5 to 100 μm.

[0018] Limiting the thickness of the cladding to this range allows the cladding to meet structural strength requirements while minimizing its thickness, thereby reducing the space occupied by the cladding within the casing and improving the energy density of the battery cells.

[0019] In some embodiments, the difference between the width of the covering and the width of the negative electrode sheet is greater than or equal to 1 mm.

[0020] Thus, by limiting the difference between the width of the cladding and the width of the negative electrode, the protective effect of the cladding on the positive and negative electrodes can be improved.

[0021] In some embodiments, the thickness of the coating is 5~100μm; the difference between the width of the coating and the width of the negative electrode sheet is greater than or equal to 1mm.

[0022] Limiting the thickness of the cladding within this range allows for minimizing its thickness while maintaining structural strength, thereby reducing the internal space occupied by the cladding and improving the energy density of the battery cell. By limiting the difference in width between the cladding and the negative electrode, the protective effect of the cladding on both the positive and negative electrodes can be enhanced.

[0023] In some embodiments, the covering is aligned with the winding direction of the first electrode, the separator, and the second electrode.

[0024] In this way, the covering material is applied along the outer surface of the entire electrode assembly, resulting in a tighter fit between the covering material and the electrode assembly. The finished covering material is also flatter, improving the structural stability of the electrode assembly. Furthermore, the winding direction of the covering material aligns with that of the first electrode, the separator, and the second electrode, which is beneficial for the production line in processing individual battery cells.

[0025] In some embodiments, the first electrode is located outside the second electrode, and the starting position of the cover overlaps the ending position of the first electrode.

[0026] The coating experiences the greatest rebound force at the end of the first electrode sheet. Starting the coating from the end of the first electrode sheet reduces the possibility of the outermost first electrode sheet rebounding or loosening, thus making the structure of the wound electrode assembly compact and reducing the possibility of the electrode assembly expanding and deforming after long-term use.

[0027] In some embodiments, the end position of the first electrode extends beyond the end position of the second electrode, and the starting position of the cover is aligned with the end position of the second electrode along the winding direction.

[0028] The end point of the first electrode extends beyond the end point of the second electrode, and the first electrode forms a step at the end point of the second electrode. The covering starts from the end point of the second electrode, that is, the covering starts from the step. This can strengthen the covering effect of the covering component on the first and second electrodes and reduce the possibility of electrode assembly deformation caused by electrode expansion.

[0029] In some embodiments, the first electrode is a negative electrode and the second electrode is a positive electrode.

[0030] In some embodiments, the isolation element includes a first isolation element and a second isolation element, wherein the first isolation element and the second isolation element are respectively stacked on both sides of the second electrode sheet;

[0031] The first electrode is located outside the second electrode, and both the first and second spacers are located inside the first electrode. The end position of the first electrode extends beyond the end position of the second electrode, and the end position of the spacers is aligned with the end position of the first electrode along the winding direction.

[0032] Thus, the outermost part of the electrode assembly is the first electrode plate, which is not covered by any insulating material. This facilitates the contact between the covering material and the first electrode plate for covering, thereby increasing the binding force of the covering material on the electrode assembly.

[0033] In some embodiments, the first electrode is a negative electrode and the second electrode is a positive electrode;

[0034] The starting position of the first electrode is located in the flat area and avoids the bending area; the starting position of the separator is flush with the starting position of the first electrode, and the starting position of the second electrode is located in the second ring of the first electrode.

[0035] In this embodiment, the starting position of the first electrode avoids the bending area, that is, the starting position of the first electrode avoids the bending area at one end and faces the bending area at the other end, but is spaced apart from the bending area at the other end by a first preset distance, which can reduce the possibility that the starting position of the first electrode will come into contact with the bending area after the first electrode expands, causing the electrode to break and lithium to be deposited.

[0036] In some embodiments, the starting position of the first electrode is oriented in the same direction as the winding direction of the first electrode.

[0037] In this embodiment, the starting position of the first electrode is spaced a certain distance from the bending area it faces in order to avoid the bending area. This reduces the possibility that the first electrode will expand and damage the bending area after the starting position of the first electrode comes into contact with it.

[0038] In some embodiments, the starting position of the first electrode is oriented opposite to the winding direction of the first electrode.

[0039] In this embodiment, the first electrode forms a corner in the bending area, which can reduce the possibility of the first electrode expanding and the bending area being damaged after the initial position of the first electrode comes into contact with the bending area.

[0040] In some embodiments, the isolation element includes a first isolation element and a second isolation element, wherein the first isolation element and the second isolation element are respectively stacked on both sides of the second electrode sheet;

[0041] The first electrode is located outside the second electrode, and both the first and second separators are located inside the first electrode.

[0042] In this embodiment, the outermost layer of the electrode assembly is a negative electrode sheet, which facilitates contact and coating between the coating component and the negative electrode sheet, improving the binding force of the coating component on the electrode assembly. Compared to an outermost layer being a separator, this increases the friction between the coating component and the electrode assembly, reducing the possibility of coating failure.

[0043] In some embodiments, the covering is adhesive tape.

[0044] In this embodiment, the adhesive force of the adhesive tape is used to enhance the binding effect on the electrode assembly.

[0045] This application also provides a battery device, including any of the battery cells described in any of the embodiments of this application.

[0046] This application also provides an electrical device, including the battery device described in this application embodiment, the battery device being used to store or provide electrical energy.

[0047] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0048] The embodiments of this application have the following beneficial effects:

[0049] The battery cell, battery device, and electrical equipment provided in this application embodiment utilize a covering component that binds the electrode assembly, limiting the increase in gap between electrodes and relative displacement of electrodes during long-term cycling and storage. This reduces the likelihood of electrode expansion causing top shell formation, electrode breakage, and lithium plating, thereby improving the battery cell's lifespan and reliability. After one turn of the covering component, it continues winding beyond the starting position to form an overlap area. The overlap area refers to the portion of the covering component from its starting position to its ending position when it is less than one turn in the final winding. The bending area has the greatest resilience, and the gap between the first and second electrodes is relatively more likely to change. The overlap area, located within the bending area, limits the resilience of the bending area, increasing the covering force on the electrode assembly, making the electrode assembly structure compact, and reducing the possibility of electrode assembly deformation due to electrode expansion. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the structure of an electrical device in one embodiment of this application;

[0051] Figure 2 This is a schematic diagram of the exploded structure of a battery device in one embodiment of this application;

[0052] Figure 3This is a schematic diagram of the structure of the cover and electrode assembly in one embodiment of this application;

[0053] Figure 4 This is a schematic diagram of the structure of an electrode assembly in one embodiment of this application.

[0054] Explanation of reference numerals in the attached figures:

[0055] 100. Battery cell; 10. Casing; 20. Electrode assembly; 201. Straight section; 202. Bending section; 30. Cover; 21. First electrode; 22. Second electrode; 220. First positive bend; 23. Separator; 231. First separator; 232. Second separator; 1000. Electrical device; 200. Battery assembly; 210. Battery box; 211. Box body; 212. Cover; 300. Controller; 400. Motor. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0057] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but should not be used to limit the scope of this application.

[0058] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0059] In the description of this specification, references to terms such as "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine the different embodiments or examples described in this application, as well as the features of those different embodiments or examples.

[0060] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0061] In related technologies, a battery cell includes a casing and electrodes. Electrode expansion can lead to breakage and lithium plating. For example, a large gap may exist between the outermost positive and negative electrodes. When the electrodes expand and press against the casing, it may cause electrode breakage and lithium plating, affecting the battery cell's lifespan and reliability.

[0062] In view of this, embodiments of this application provide a battery cell that can reduce the possibility of electrode breakage and lithium plating.

[0063] This application also provides a battery device, which includes the battery cell described in any one of the embodiments of this application.

[0064] This application also provides an electrical device, which includes the battery device described in this application, for storing or providing electrical energy.

[0065] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0066] Please refer to Figure 1 This application will use a vehicle as an example to illustrate an embodiment of an electrical device 1000. The vehicle 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 200 is installed inside the vehicle, and the battery device 200 can be located at the bottom, front, or rear of the vehicle. The battery device 200 can be used to power the vehicle; for example, the battery device 200 can serve as the vehicle's operating power source. The vehicle may also include a controller 300 and a motor 400. The controller 300 controls the battery device 200 to supply power to the motor 400, for example, to meet the power needs of the vehicle during starting, navigation, and driving.

[0067] Please refer to Figure 2This is an exploded view of a battery device 200 provided in some embodiments of this application. The battery device 200 includes a battery case 210 and battery cells 100, with the battery cells 100 housed within the battery case 210. The battery case 210 provides space for the battery cells 100, and can have various structures. For example, the battery case 210 includes a case body 211 and a cover 212, with the cover 212 covering the case body 211 to form a housing space, within which the battery cells 100 are disposed.

[0068] In the battery device 200, there can be multiple battery cells 100, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 100 are connected in both series and parallel configurations. Multiple battery cells 100 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 100 is housed within the battery box 210. Alternatively, the battery device 200 can also consist of multiple battery cells 100 first connected in series, parallel, or in a mixed manner to form battery modules, and then these battery modules are connected in series, parallel, or in a mixed manner to form a whole, which is also housed within the battery box 210. The battery device 200 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 100.

[0069] In some embodiments, the battery device 200 includes a battery management system, which is a core component responsible for monitoring and managing the status of individual battery cells 100. Its main functions include: real-time monitoring of parameters such as voltage, current, and temperature of individual battery cells 100 to ensure that the battery is in a safe working state; balancing the charge of each individual battery cell 100 in the battery cell group 100 through active or passive means to extend the battery life; controlling and regulating the temperature of individual battery cells 100 to avoid performance degradation or safety risks caused by overheating or overcooling; detecting faults in the battery cell group 100 and the BMS itself, and taking corresponding protective measures, such as cutting off power and alarming.

[0070] As an example, the battery management system can be housed in the enclosure 211 to support and protect the battery management system.

[0071] As an example, the battery management system can also be located outside the housing 211 and connected to the battery cells 100, sensors and other devices inside the housing 211 via wires.

[0072] 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.

[0073] The battery cell can be a 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. The embodiments of this application take lithium-ion batteries as an example for illustration.

[0074] Please see Figures 2 to 4 The battery cell 100 includes an electrode assembly 20. The electrode assembly 20 includes a positive electrode, a negative electrode, and a separator 23. The positive electrode can be a positive electrode sheet, the negative electrode can be a negative electrode sheet, and the separator 23 is disposed between the negative and positive electrodes. During the charging and discharging process of the battery cell 100, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator 23, disposed between the positive and negative electrodes, serves to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0075] In some embodiments, the positive electrode sheet may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector.

[0076] 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.

[0077] As an example, the positive current collector can be a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as a metal foil, pure metals, alloys, or surface-treated metals can be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0078] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3O2 (Also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1O2 (Also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0079] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0080] As an example, the negative electrode current collector can be a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as a metal foil, pure metals, alloys, or surface-treated metals can be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer material substrate and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0081] As an example, 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.

[0082] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cell 100. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for battery cell 100 may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0083] As an example, negative electrode active materials can be filled or / and deposited within the negative electrode current collector.

[0084] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0085] In some embodiments, the separator 23 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.

[0086] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator 23 can be a single component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be applied to the surface of the separator.

[0087] In some embodiments, the separator 23 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.

[0088] In some embodiments, the electrode assembly 20 is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0089] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0090] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0091] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0092] As an example, multiple separators 23 can be provided, each disposed between any adjacent positive or negative electrode plates.

[0093] As an example, the separator 23 can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0094] In some embodiments, the electrode assembly 20 can be cylindrical, flat, or polygonal. This application uses a flat cylindrical electrode assembly 20 as an example for illustration.

[0095] In some embodiments, the electrode assembly 20 is provided with tabs that can conduct current from the electrode assembly 20. The tabs include a positive tab and a negative tab.

[0096] In some implementations, please refer to Figure 2 The battery cell 100 may include a housing 10. The housing 10 may be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film, etc. In some embodiments, the housing 10 may be a sealed structure or a non-sealed structure. As an example, when the housing 10 is a non-sealed structure, the housing 10 serves to protect the electrode assembly 20, and a sealing bag is also included between the housing 10 and the electrode assembly 20. The sealing bag is used to encapsulate the electrode assembly 20 and the electrolyte. Specifically, the sealing bag may be a bag-shaped insulating component or an aluminum-plastic film. When the housing 10 is a sealed structure, it is used to encapsulate the electrode assembly 20 and the electrolyte, etc.

[0097] In some embodiments, the housing 10 includes an end cap and a housing body, the housing body having an opening, and the end cap covering the opening. The housing body may have one or more openings. The end cap may also be provided one or more.

[0098] The following, in conjunction with the appendix Figures 2 to 4The present application provides a detailed description of the battery cell using specific embodiments. In the embodiments of this application, the winding direction of the electrode assembly is as indicated by arrow S. The reverse direction of the winding direction of the electrode assembly is as indicated by arrow S'.

[0099] In some embodiments, please refer to Figures 2 to 4 The battery cell 100 includes a housing 10 and an electrode assembly 20. The electrode assembly 20 is disposed within the housing 10; wherein, the electrode assembly 20 includes a first electrode 21, a second electrode 22 and a separator 23, the separator 23 is disposed between the first electrode 21 and the second electrode 22, and the first electrode 21, the separator 23 and the second electrode 22 are stacked and wound together.

[0100] The first electrode 21 and the second electrode 22 have opposite polarities, one of which is a positive electrode and the other is a negative electrode. The first electrode 21 can be configured as the positive electrode and the second electrode 22 as the negative electrode. Alternatively, the first electrode 21 can be configured as the negative electrode and the second electrode 22 as the positive electrode. This embodiment uses the example of the first electrode 21 being the negative electrode, the second electrode 22 being the positive electrode, and lithium ions as the active ion. The first electrode 21 and the second electrode 22 can be collectively referred to as electrodes.

[0101] It is understandable that the winding direction S of the first electrode 21, the separator 23, and the second electrode 22 is the same.

[0102] In some embodiments, please refer to Figure 3 and Figure 4 The first electrode 21, the spacer 23, and the second electrode 22 are stacked and wound together to form a flat region 201 and a bent region 202 connecting the two ends of the flat region 201 in the electrode assembly 20. After winding, the electrode assembly 20 needs to undergo a shaping process. During the shaping process, the wound body is shaped and pressed into a flat cylindrical winding structure, thereby forming the flat region 201 and the bent region 202. The flat region 201 refers to the area in the electrode assembly 20 that is flat after being shaped and pressed, while the bent region 202 refers to the area in the electrode assembly 20 that is bent after being shaped and pressed. The two opposite ends of the flat region 201 form the bent region 202. In the winding direction S, the flat region 201 and the bent region 202 are arranged alternately and connected.

[0103] In some embodiments, please refer to Figure 3 and Figure 4 The first electrode 21 is the negative electrode, and the second electrode 22 is the positive electrode. The starting position A of the first electrode 21 is located in the straight region 201 and avoids the bending region 202. The starting position B of the second electrode 22 is located in the second ring of the first electrode 21. That is to say, the first electrode 21 is more than half a ring to one ring longer than the second electrode 22.

[0104] In this embodiment, the starting position A of the first electrode 21 avoids the bending region 202, that is, the starting position A of the first electrode 21 avoids the bending region 202 at one end and faces the bending region 202 at the other end, but is spaced apart from the bending region 202 at the other end by a first preset distance. This can reduce the possibility that after the first electrode 21 expands, the starting position A of the first electrode 21 will come into contact with the bending region 202, causing electrode breakage and lithium plating. For example, the first preset distance can be 1 / 5 to 4 / 5 of the length of the straight region 201. The starting position B of the second electrode 22 is located in the second ring of the first electrode 21. For example, the starting position B of the second electrode 22 is spaced apart from the bending area 202 by a second preset distance. For example, the second preset distance can be 1 / 10 to 1 / 5 of the length of the straight area 201, so as to prevent the starting position B of the second electrode 22 from touching the bending area 202, and to make full use of the length of the second electrode 22 so that the first ring of the first electrode 21 can have a corresponding second electrode 22, so that the first ring of the first electrode 21 can exert its capacity, effectively increasing the capacity of the battery cell 100, and making the active material of the inner ring first electrode 21 more than that of the second electrode 22, so that the lithium ions extracted from the second electrode 22 can be inserted into the first electrode 21 and fully received by the first electrode 21, reducing the lithium plating of the first electrode 21.

[0105] Further, please refer to Figure 3 and Figure 4 The starting position C of the isolator 23 is flush with the starting position A of the first electrode 21. Since the starting position A of the first electrode 21 exceeds the starting position B of the second electrode 22, the starting position C of the isolator 23 also exceeds the starting position B of the second electrode 22. In this way, the isolator 23 can prevent short circuits between the positive and negative electrodes.

[0106] In some other embodiments not shown, the starting position C of the isolator 23 extends beyond the starting position A of the first electrode 21.

[0107] In some embodiments where the starting position A of the first electrode 21 is located in the straight region 201 and avoids the bending region 202, please refer to [the relevant documentation]. Figure 3 and Figure 4 The starting position A of the first electrode 21 faces the opposite direction to the winding direction S of the first electrode 21. That is to say, the first electrode 21 forms a corner in the bending area 202, which can reduce the possibility of the first electrode 21 expanding and the bending area 202 being damaged after the starting position A of the first electrode 21 comes into contact with the bending area 202.

[0108] In some embodiments (not shown), the starting position A of the first electrode 21 is located in the flat region 201 and avoids the bending region 202. In other embodiments, the starting position A of the first electrode 21 is oriented in the same direction as the winding direction of the first electrode 21. That is, the starting position A of the first electrode 21 is spaced a certain distance from the bending region 202 it faces, in order to avoid the bending region 202. This reduces the possibility that the first electrode 21 expands and the starting position A of the first electrode 21 comes into contact with the bending region 202, which could damage the bending region 202.

[0109] In some embodiments, the width of the negative electrode is greater than the width of the positive electrode, which can reduce the possibility of lithium ion deposition due to lack of negative electrode reception and improve the reliability of the battery cell 100.

[0110] In some embodiments, the width of the separator 23 is greater than the width of the negative electrode sheet, which can reduce the possibility of short circuit and improve the reliability of the battery cell 100.

[0111] In some embodiments, please refer to Figure 3 The battery cell 100 includes a cover 30, which covers the outer ring of the electrode assembly 20. The cover 30 covers the electrode assembly 20 at least once, and the starting position D and the ending position D' of the cover 30 can be connected end to end. It can be wound once, or the cover 30 can be wound once and then continue to be wound beyond the starting position D.

[0112] In some embodiments, please refer to Figure 3 The winding direction S of the covering 30 can be the same as that of the electrode assembly 20. That is, the winding direction S of the covering 30 is consistent with that of the first electrode 21, the separator 23, and the second electrode 22. In this way, the covering 30 covers the entire outer surface of the electrode assembly 20, resulting in a tighter fit and a smoother surface, thus improving the structural stability of the electrode assembly 20. The consistency of the winding direction S between the covering 30 and the first electrode 21, the separator 23, and the second electrode 22 also facilitates the processing of individual battery cells on the production line. For example… Figure 3 As shown, a covering is attached to the end of the first electrode 21, and the electrode assembly is covered in the same feeding direction.

[0113] In other embodiments not shown, the winding direction of the cover 30 may also be opposite to the winding direction of the electrode assembly 20.

[0114] In some embodiments, the covering 30 can be adhesive tape, which strengthens the binding effect on the electrode assembly 20 through its adhesive strength.

[0115] In some embodiments, the covering 30 extends beyond the electrode assembly 20 at both ends along its height direction. The height direction of the electrode assembly 20 is perpendicular to the winding direction S of the electrode assembly 20. Thus, the covering 30 can completely cover the edges of the first electrode 21 and the second electrode 22, reducing the possibility of the covering 30 being forced to fold and expose the first electrode 21 and the second electrode 22, improving the protection of the electrodes, and reducing the possibility of lithium plating at the electrode edges.

[0116] That is, the width of the cladding 30 is greater than the width of the negative electrode sheet, and the difference between the width of the cladding 30 and the width of the negative electrode sheet is greater than or equal to 1 mm (millimeters), for example, it can be 1 mm, 2 mm, 5 mm, 8 mm, or 10 mm or more, etc. The width of the cladding 30 refers to the dimension of the cladding 30 along the height direction of the electrode assembly 20. The width of the negative electrode sheet refers to the dimension of the negative electrode sheet along the height direction of the electrode assembly 20. It can be understood that the width of the negative electrode sheet is greater than the width of the positive electrode sheet; therefore, the width of the cladding 30 is also greater than the width of the positive electrode sheet.

[0117] Thus, by limiting the difference between the width of the cladding 30 and the width of the negative electrode, the protective effect of the cladding 30 on the positive and negative electrodes can be improved.

[0118] Furthermore, the width of the covering 30 is greater than the width of the separator 23, so that the covering 30 can cover the entire electrode assembly 20, thereby improving the protective effect of the covering 30 on the electrode assembly 20.

[0119] The battery cell 100 provided in this application embodiment has a covering 30 that can restrain the electrode assembly 20, limiting the increase in gaps between the electrodes and the relative displacement of the electrodes during long-term cycling and storage. This reduces the possibility of electrode expansion causing electrode top shell damage, reduces the possibility of electrode breakage and lithium plating, and can improve the service life and reliability of the battery cell 100.

[0120] In some embodiments, the cover 30 covers the electrode assembly 20 more than one turn. When the last turn of the winding is less than one turn, the end position D' of the cover 30 and the starting position D of the cover 30 form an overlapping area along the winding direction of the cover 30. The overlapping area is at least partially located in the bending area 202.

[0121] After the covering part 30 is wound once, it continues to be wound beyond the starting position D. The overlapping area should not be understood as the entire length of the covering part 30 after it exceeds one turn, but rather the part from the starting position D corresponding to the covering part 30 to the ending position D' of the covering part when the covering part 30 is less than one turn in the last turn.

[0122] The number of wrapping rings of the covering element 30 is not limited; it can be more than one ring but less than two rings, two rings, more than two rings but less than three rings, etc., covering the electrode assembly 20, etc., which will not be elaborated here. Figure 3 As shown, the covering 30 covers the electrode assembly 20 by more than one turn and less than two turns.

[0123] The overlapping area is at least partially located in the bending area 202. It can be that the entire overlapping area is located in the bending area 202, or that part of the overlapping area is located in the bending area 202 and part of the overlapping area is located in the straight area 201. When the entire overlapping area is located in the bending area 202, the binding effect on the bending area 202 can be further improved.

[0124] In this embodiment, the bending area 202 has the greatest rebound force, and the gap between the first electrode 21 and the second electrode 22 is more likely to change. The overlapping area is located in the bending area 202, which can limit the rebound force of the bending area 202, improve the covering force on the electrode assembly 20, make the electrode assembly 20 structure compact, and reduce the possibility of the electrode assembly 20 deforming due to electrode expansion.

[0125] In some embodiments, please refer to Figure 3 The overlap distance between the ending position D' of the covering element 30 and the starting position D of the covering element 30 along the winding direction of the covering element 30 is a preset length L. In other words, the length of the overlap area is the preset length L. The preset length L should not be understood as the length of the covering element 30 after one more turn, but rather as the distance from the starting position D of the covering element 30 to the ending position D' of the covering element 30 on the last turn. The preset length L can be understood as being less than the length of one turn around the outer edge of the electrode assembly.

[0126] In some embodiments, the preset length L is greater than or equal to 1 mm, meaning the length of the overlapping area is greater than or equal to 1 mm, such as 1 mm, 2 mm, 5 mm, 8 mm, or 10 mm or more. This reduces the possibility of displacement of the covering 30 due to electrode expansion, improving the reliability of the covering 30. For example, when the covering 30 is adhesive tape, a preset length greater than or equal to 1 mm can reduce the possibility of the adhesive tape detaching from the electrode assembly 20 due to electrode expansion.

[0127] In some embodiments, the thickness of the covering 30 is 5~100 μm (micrometers), for example, it can be 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm, etc. Limiting the thickness of the covering 30 within this range allows the covering 30 to meet structural strength requirements while minimizing its thickness, thereby reducing the space volume occupied by the covering 30 within the casing 10, which is beneficial to improving the energy density of the battery cell 100.

[0128] In some embodiments, please refer to Figure 3 The first electrode 21 is located outside the second electrode 22, and the starting position D of the covering 30 overlaps the ending position A' of the first electrode 21. The covering 30 experiences the greatest rebound force at the ending position A' of the first electrode 21. By starting the covering from the ending position A', the possibility of the outermost first electrode 21 rebounding or loosening can be reduced, making the structure of the wound electrode assembly 20 compact and reducing the possibility of the electrode assembly 20 expanding and deforming after long-term use.

[0129] In some embodiments, please refer to Figure 3 The first electrode 21 is the negative electrode, and the second electrode 22 is the positive electrode. The negative electrode is located outside the positive electrode, and the end position A' of the negative electrode extends beyond the end position B' of the positive electrode. The separator 23 includes a first separator 231 and a second separator 232, which are respectively stacked on both sides of the second electrode 22; both the first separator 231 and the second separator 232 are located inside the first electrode 21.

[0130] In other words, the outermost layer of the electrode assembly 20 is a negative electrode sheet, which facilitates the contact and coating of the coating member 30 with the negative electrode sheet, thereby increasing the binding force of the coating member 30 on the electrode assembly 20. In contrast, if the outermost layer is a separator 23, the friction between the coating member 30 and the electrode assembly 20 can be increased, reducing the possibility of coating failure.

[0131] Further, please refer to Figure 3 The starting position D of the covering 30 is aligned with the ending position B' of the second electrode 22 along the winding direction. The ending position A' of the first electrode 21 extends beyond the ending position B' of the second electrode 22, and the first electrode 21 forms a step at the ending position B' of the second electrode 22. The covering starts from the ending position B' of the second electrode 22, that is, from the step, which can strengthen the covering effect of the covering 30 on the first electrode 21 and the second electrode 22 and reduce the possibility of electrode assembly 20 deformation due to electrode expansion.

[0132] In some embodiments, please refer to Figure 3 The starting position D and the ending position D' of the covering 30 are both located in the bending area 202, which can further enhance the covering effect of the covering 30 on the electrode assembly 20 and reduce the possibility of displacement of the first electrode 21 and the second electrode 22 due to the spring force of the bending area 202.

[0133] As an example, the starting position D of the covering 30 and the ending position D' of the covering 30 can be located in the same bending area 202.

[0134] In other embodiments, the starting position D of the covering 30 and the ending position D' of the covering 30 may be located in two bending areas 202, respectively.

[0135] Further, please refer to Figure 3 The starting position D of the covering 30, the ending position B' of the second electrode 22, and the ending position A' of the first electrode 21 are located in the same bending area 202. In this way, the covering effect of the covering 30 on the ending positions B' of the second electrode 22 and A' of the first electrode 21 can be strengthened, and the possibility of displacement of the ending positions B' of the second electrode 22 and A' of the first electrode 21 due to the springback force of the bending area 202 can be reduced.

[0136] Further, please refer to Figure 3 The end position C' of the separator 23 is aligned with the end position A' of the first electrode 21 along the winding direction. Thus, the outermost part of the electrode assembly 20 is the first electrode 21, which is not covered by the separator 23. This facilitates the contact between the covering member 30 and the first electrode 21 for covering, thereby increasing the binding force of the covering member 30 on the electrode assembly 20.

[0137] In some other embodiments not shown, the end position C' of the separator 23 extends beyond the end position A' of the first electrode 21 along the winding direction.

[0138] As an optional embodiment, please refer to Figure 3 The first electrode 21 is the negative electrode, and the second electrode 22 is the positive electrode. The ending positions A' of the positive electrode, B' of the negative electrode, and C' of the separator 23 are all located in the same bending area 202. In this way, the covering effect of the covering 30 on the ending positions A' of the positive electrode, B' of the negative electrode, and C' of the separator 23 can be strengthened, and the possibility of displacement of the ending positions A' of the positive electrode, B' of the negative electrode, and C' of the separator 23 due to the springback force of the bending area 202 can be reduced.

[0139] Furthermore, the starting position D and ending position D' of the coating 30, the ending position A' of the positive electrode, the ending position B' of the negative electrode, and the ending position C' of the separator 23 are all located in the same bending area 202. This enhances the coating effect of the coating 30 on the electrode assembly 20.

[0140] In some embodiments, please refer to Figure 2 and Figure 3The battery cell 100 includes a housing 10, an electrode assembly 20, and a covering 30, wherein the covering 30 is adhesive tape. The electrode assembly 20 is disposed within the housing 10. The electrode assembly 20 includes a first electrode 21, a second electrode 22, and a separator 23, wherein the separator 23 is a separator film, the first electrode 21 is a negative electrode, and the second electrode 22 is a positive electrode. The negative electrode, the separator 23, and the positive electrode are stacked and wound to form a flat region 201 and a bent region 202 connecting the two ends of the flat region 201. The starting position A of the negative electrode is located in the flat region 201 and avoids the bent region 202; the starting position B of the positive electrode is located in the second turn of the negative electrode. The covering 30 is aligned with the winding direction S of the negative electrode, the separator 23, and the positive electrode. A separator 23 is disposed between the negative electrode and the positive electrode. The separator 23 includes a first separator 231 and a second separator 232, which are stacked on both sides of the positive electrode. Both the first separator 231 and the second separator 232 are located inside the negative electrode. The negative electrode is located outside the positive electrode, and its ending position A' extends beyond the ending position B' of the positive electrode. The ending position C' of the separator 23 is aligned with the ending position A' of the negative electrode along the winding direction. The ending positions A' of the positive electrode, B' of the negative electrode, and C' of the separator 23 are all located in the same bending region 202. The starting position A of the negative electrode faces the opposite direction to the winding direction S of the negative electrode. The cladding 30 covers the outer ring of the electrode assembly 20, with the cladding 30 covering the electrode assembly 20 by more than one but less than two turns. After one turn, the cladding 30 continues winding beyond the starting position D. The ending position D' of the cladding 30 overlaps with the starting position D of the cladding 30 along the winding direction, and the entire overlap area is located in the bending area 202. Both the ending position D' and the starting position D of the cladding 30 are located in the bending area 202, and the overlap distance along the winding direction of the cladding 30 is greater than 1 mm. The thickness of the cladding 30 is 5~100 μm, and the width of the cladding 30 is greater than the width of the negative electrode sheet. The starting position D of the cladding 30 overlaps with the ending position A' of the negative electrode sheet, and the starting position D of the cladding 30 is aligned with the ending position B' of the positive electrode sheet along the winding direction.

[0141] In this embodiment, the covering 30 can restrain the electrode assembly 20, limiting the increase in gap between the electrodes and the relative displacement of the electrodes during long-term cycling and storage of the battery cell 100. This reduces the possibility of electrode expansion causing top shell damage, electrode breakage, and lithium plating, thereby improving the lifespan and reliability of the battery cell 100. The overlap region has a length greater than or equal to 1 mm, which reduces the possibility of electrode expansion causing displacement of the covering 30, improving the reliability of the covering 30 and reducing the possibility of the adhesive tape detaching from the electrode assembly 20 due to electrode expansion. The bending region 202 has the greatest resilience, and the gap between the first electrode 21 and the second electrode 22 is relatively likely to change. The overlap region is located in the bending region 202, which limits the resilience of the bending region 202, increases the covering force on the electrode assembly 20, makes the electrode assembly 20 structure compact, and reduces the possibility of electrode expansion causing deformation of the electrode assembly 20. The thickness of the cladding 30 is limited to the range of 5~100μm to minimize its thickness while maintaining structural strength, thereby reducing the space occupied by the cladding 30 within the casing 10 and improving the energy density of the battery cell 100. By limiting the difference in width between the cladding 30 and the negative electrode sheet, the protective effect of the cladding 30 on the positive and negative electrodes is enhanced. The cladding 30 is applied along the outer surface of the electrode assembly 20, resulting in a tighter fit and a smoother surface, thus improving the structural stability of the electrode assembly 20. The cladding 30's winding direction S aligns with that of the negative electrode sheet, separator 23, and positive electrode sheet, which also facilitates battery cell processing on the production line. The coating 30 experiences the greatest rebound force at the end position A' of the negative electrode sheet. Starting the coating from the end position A' reduces the possibility of the outermost negative electrode sheet rebounding or loosening, ensuring a tight structure for the wound electrode assembly 20 and reducing the possibility of expansion and deformation after prolonged use. The outermost layer of the electrode assembly 20 is the negative electrode sheet, facilitating contact between the coating 30 and the negative electrode sheet for coating, thus increasing the binding force of the coating 30 on the electrode assembly 20. Compared to the outermost layer being the separator 23, this increases the friction between the coating 30 and the electrode assembly 20, reducing the possibility of coating failure. The starting position D and the ending position D' of the coating 30 are both located in the same bending area 202, further strengthening the coating effect of the coating 30 on the electrode assembly 20 and reducing the possibility of displacement of the first electrode sheet 21 and the second electrode sheet 22 due to the rebound force in the bending area 202. The starting position A of the negative electrode avoids the bending area 202, that is, the starting position A of the negative electrode avoids the bending area 202 at one end and faces the bending area 202 at the other end, but is spaced apart from the bending area 202 at the other end by a first preset distance. This can reduce the possibility that the starting position A of the negative electrode will come into contact with the bending area 202 after the negative electrode expands, causing the electrode to break and lithium to be deposited.The starting position A of the negative electrode sheet faces the opposite direction to the winding direction S of the negative electrode sheet. The negative electrode sheet forms a corner in the bending area 202, which can reduce the possibility of the negative electrode sheet expanding and damaging the bending area 202 after the starting position A of the negative electrode sheet comes into contact with it. The ending position A' of the negative electrode sheet extends beyond the ending position B' of the positive electrode sheet, and a step is formed at the ending position B' of the positive electrode sheet. The encapsulation starts from the ending position B' of the positive electrode sheet, that is, from the step, which can strengthen the encapsulation effect of the encapsulating component 30 on the negative and positive electrode sheets and reduce the possibility of the electrode assembly 20 deforming due to electrode sheet expansion. The ending positions A' of the positive electrode, B' of the negative electrode, and C' of the separator 23 are all located in the same bending area 202. This strengthens the covering effect of the covering 30 on these three positions, reducing the possibility of displacement caused by the springback force of the bending area 202. The ending position C' of the separator 23 is aligned with the ending position A' of the negative electrode along the winding direction. The outermost layer of the electrode assembly 20 is the negative electrode, which is not covered by the separator 23. This facilitates contact between the covering 30 and the negative electrode for covering, increasing the binding force of the covering 30 on the electrode assembly 20.

[0142] In related technologies, electrode assemblies are made by winding or stacking positive electrode sheets, negative electrode sheets, and separators. In electrode assemblies made by winding, there is a situation where the negative electrode sheet is directly opposite the negative electrode sheet in the inner ring of the winding structure, and there is no positive electrode sheet in the middle. The negative electrode active material in this part of the inner ring cannot be effectively utilized, which makes it difficult to effectively improve the energy density of the electrode assembly.

[0143] In some embodiments, please refer to Figure 4 The battery cell 100 includes a housing 10 and an electrode assembly 20, with the electrode assembly 20 disposed within the housing 10. The electrode assembly 20 includes a positive electrode, a negative electrode, and a separator 23. The positive electrode includes a positive current collector and a positive active material coated on the positive current collector; the negative electrode includes a negative current collector and a negative active material coated on the negative current collector; a separator 23 is disposed between the positive electrode and the negative electrode, and the positive electrode, separator 23 and negative electrode are stacked and wound together to form a flat region 201 and a bent region 202 connected to both ends of the flat region 201; wherein, the flat region 201 corresponds to a plurality of positive flat portions of the positive electrode and a plurality of negative flat portions of the negative electrode, and the bent region 202 corresponds to a plurality of positive bent portions of the positive electrode and a plurality of negative bent portions of the negative electrode; the starting position B of the positive electrode is located on the second ring of the negative electrode, the negative electrode is located on the outside of the positive electrode, and the first positive bent portion 220 of the positive electrode is not coated with positive active material.

[0144] In this embodiment, the starting position B of the positive electrode sheet is located in the second ring of the negative electrode sheet. The two ends of the first positive bend 220 of the positive electrode sheet are respectively connected to the positive straight portion. That is to say, the first ring of the negative electrode sheet can have a corresponding positive straight portion, which satisfies the requirement that the negative active material is aligned with the positive active material, allowing the first ring of the negative electrode sheet to exert its capacity. For example, current can be generated through the tabs, which can effectively improve the capacity density of the electrode assembly 20 and the battery cell 100. The first positive bend 220 of the positive electrode sheet is not coated with positive active material and does not provide positive active material to participate in the chemical reaction, so that the negative active material is in excess and sufficient, which can meet the excess design requirements of the electrode assembly 20 for the negative electrode capacity and reduce the risk of lithium plating in the electrode assembly 20.

[0145] In some embodiments, please refer to Figure 4 At least the portion where the first straight portion of the positive electrode connects to the first bent portion of the positive electrode is not coated with positive electrode active material.

[0146] In this way, the excess design requirements of the electrode assembly 20 for the negative electrode capacity can be further met, and the risk of lithium plating of the electrode assembly 20 can be reduced.

[0147] In some embodiments, please refer to Figure 2 and Figure 4 The battery cell 100 includes a housing 10 and an electrode assembly 20, which is disposed within the housing 10. The electrode assembly 20 includes a positive electrode, a negative electrode, and a separator 23, which is a separator membrane. The positive electrode includes a positive current collector and a positive active material coated on the positive current collector; the negative electrode includes a negative current collector and a negative active material coated on the negative current collector; a separator 23 is disposed between the positive electrode and the negative electrode, and the positive electrode, separator 23 and negative electrode are stacked and wound together to form a flat region 201 and a bent region 202 connecting the two ends of the flat region 201 in the electrode assembly 20; the starting position A of the negative electrode is located in the flat region 201 and avoids the bent region 202; wherein, the flat region 201 corresponds to a plurality of positive flat portions of the positive electrode and a plurality of negative flat portions of the negative electrode, and the bent region 202 corresponds to a plurality of positive bent portions of the positive electrode and a plurality of negative bent portions of the negative electrode; the starting position B of the positive electrode is located in the second turn of the negative electrode, the negative electrode is located outside the positive electrode, and the starting position A of the negative electrode faces the opposite direction to the winding direction S of the negative electrode. The first positive bend 220 of the positive electrode sheet is not coated with positive active material. At least the portion of the first straight portion of the positive electrode sheet connected to the first bend is not coated with positive active material. The separator 23 includes a first separator 231 and a second separator 232, which are respectively stacked on both sides of the positive electrode sheet; both the first separator 231 and the second separator 232 are located inside the negative electrode sheet.

[0148] In this embodiment, the starting position B of the positive electrode sheet is located in the second ring of the negative electrode sheet. The two ends of the first positive bend 220 of the positive electrode sheet are respectively connected to the positive straight portion. That is to say, the first ring of the negative electrode sheet can have a corresponding positive straight portion, which satisfies the requirement that the negative active material is aligned with the positive active material, allowing the first ring of the negative electrode sheet to exert its capacity. For example, current can be generated through the tabs, which can effectively improve the capacity density of the electrode assembly 20 and the battery cell 100. The first positive bend 220 of the positive electrode sheet is not coated with positive active material and does not provide positive active material to participate in the chemical reaction, so that the negative active material is in excess and sufficient, which can meet the excess design requirement of the electrode assembly 20 for the negative electrode capacity and reduce the risk of lithium plating in the electrode assembly 20. At least the part of the positive straight portion connected to the first bend of the positive electrode sheet is not coated with positive active material, which can further meet the excess design requirement of the electrode assembly 20 for the negative electrode capacity and reduce the risk of lithium plating in the electrode assembly 20. After winding, the electrode assembly 20 needs to undergo a shaping process. During this process, the winding is shaped and pressed into a flat cylindrical structure, thus forming a straight region 201 and a bent region 202. The straight region 201 refers to the area in the electrode assembly 20 that is straight after being shaped and pressed, while the bent region 202 refers to the area in the electrode assembly 20 that is bent after being shaped and pressed. The two opposite ends of the straight region 201 form the bent region 202. In the winding direction S, the straight region 201 and the bent region 202 are arranged alternately and connected. The starting position A of the negative electrode avoids the bending area 202, that is, the starting position A of the negative electrode avoids the bending area 202 at one end and faces the bending area 202 at the other end, but is spaced apart from the bending area 202 at the other end by a first preset distance. This can reduce the possibility that the starting position A of the negative electrode will come into contact with the bending area 202 after the negative electrode expands, causing the electrode to break and lithium to be deposited.

[0149] The above description is merely a preferred embodiment of this application and is not intended to limit the application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A battery cell, characterized in that, include: case; Electrode assembly, disposed within the housing; Covering components; The electrode assembly includes a first electrode, a second electrode, and a separator. One of the first electrode and the second electrode is a positive electrode, and the other is a negative electrode. The separator is disposed between the first electrode and the second electrode. The first electrode, the separator, and the second electrode are stacked and wound together. The covering member covers the outer ring of the electrode assembly, and the covering member covers the electrode assembly more than one turn. The first electrode, the separator, and the second electrode are stacked and wound together to form a flat region and a bent region connecting the two ends of the flat region in the electrode assembly; The end position of the covering and the beginning position of the covering form an overlapping area along the winding direction of the covering, and the overlapping area is at least partially located in the bending area.

2. The battery cell according to claim 1, characterized in that, The starting position and the ending position of the covering are both located in the bending area.

3. The battery cell according to claim 1, characterized in that, The length of the overlapping area is greater than or equal to 1 mm.

4. The battery cell according to claim 1, characterized in that, The thickness of the covering is 5~100μm; and / or, The difference between the width of the covering and the width of the negative electrode sheet is greater than or equal to 1 mm.

5. The battery cell according to claim 1, characterized in that, The wrapping material is wound in the same direction as the first electrode, the separator, and the second electrode.

6. The battery cell according to claim 1, characterized in that, The first electrode is located outside the second electrode, and the starting position of the covering overlaps the ending position of the first electrode.

7. The battery cell according to claim 6, characterized in that, The end position of the first electrode extends beyond the end position of the second electrode, and the starting position of the covering is aligned with the end position of the second electrode along the winding direction.

8. The battery cell according to any one of claims 1 to 7, characterized in that, The first electrode is the negative electrode, and the second electrode is the positive electrode.

9. The battery cell according to claim 8, characterized in that, The isolation element includes a first isolation element and a second isolation element, which are respectively stacked on both sides of the second electrode sheet; The first electrode is located outside the second electrode, and both the first and second spacers are located inside the first electrode. The end position of the first electrode extends beyond the end position of the second electrode, and the end position of the spacers is aligned with the end position of the first electrode along the winding direction.

10. The battery cell according to claim 1, characterized in that, The first electrode is a negative electrode, and the second electrode is a positive electrode; The starting position of the first electrode is located in the flat area and avoids the bending area; the starting position of the separator is flush with the starting position of the first electrode, and the starting position of the second electrode is located in the second ring of the first electrode.

11. The battery cell according to claim 10, characterized in that, The starting position of the first electrode is oriented in the same direction as or opposite to the winding direction of the first electrode.

12. The battery cell according to claim 10, characterized in that, The isolation element includes a first isolation element and a second isolation element, which are respectively stacked on both sides of the second electrode sheet; The first electrode is located outside the second electrode, and both the first and second separators are located inside the first electrode.

13. The battery cell according to any one of claims 1 to 7, characterized in that, The covering is adhesive paper.

14. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1 to 13.

15. An electrical appliance, characterized in that, Includes the battery device of claim 14, for storing or providing electrical energy.

Images