Battery monomer, battery device and electric equipment

Abstract

The utility model relates to a battery monomer, a battery device and electric equipment, and the battery monomer comprises a shell which is provided with a containing cavity; the electrode assembly is arranged in the containing cavity and comprises a pole piece, the pole piece is provided with a first area and a second area, and the first area is located on the two opposite sides of the second area in the width direction of the pole piece; the porosity of the second region is greater than that of the first region; the pole piece comprises a current collector and a slurry layer, the slurry layer located in the first area is constructed as a first coating area, the slurry layer located in the second area is constructed as a second coating area, and the thickness of the first coating area is larger than that of the second coating area. And the thickness of the connecting position of the first coating area and the second coating area is gradually reduced from the first coating area to the second coating area. When the electrode assembly expands and deforms, the second area can store more electrolyte, or can suck more electrolyte back from the accommodating cavity, so that electrolyte infiltration is improved, and the cycle life of the single battery is prolonged.

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] During cycling, battery cells expand and deform. After expansion and deformation, some electrolyte in the electrode assembly may be squeezed out, affecting the migration rate of lithium ions in the battery cell and thus affecting the overall cycle life of the battery cell. Utility Model Content

[0003] Therefore, it is necessary to provide a battery cell, battery device, and electrical equipment that can improve cycle life in response to the above problems.

[0004] In a first aspect, this application provides a battery cell, including a casing and an electrode assembly. The casing has a receiving cavity; the electrode assembly is disposed within the receiving cavity and includes an electrode sheet. The electrode sheet has a first region and a second region, with the first region located on opposite sides of the second region along the width direction of the electrode sheet; wherein the porosity of the second region is greater than that of the first region. The electrode sheet includes a current collector and a slurry layer coated on the current collector. The slurry layer located in the first region is configured as a first coating region, and the slurry layer located in the second region is configured as a second coating region. The thickness of the first coating region is greater than the thickness of the second coating region, and the thickness at the junction of the first coating region and the second coating region gradually decreases from the first coating region to the second coating region.

[0005] With the above structure, when the electrode assembly expands and deforms, the second region can retain more electrolyte or draw more electrolyte back from the containment cavity, improving electrolyte wetting and thus increasing the cycle life of the battery cell.

[0006] Furthermore, slurry layers of different thicknesses in the first and second coating regions can be smoothly formed during the coating process. Then, after cold pressing, an active material layer of the same thickness is formed, ultimately achieving the respective compaction density and porosity of the first and second regions. This method is convenient and has high production efficiency. It also allows for a smooth transition of the slurry layer between the first and second coating regions, resulting in a more stable electrode structure after cold pressing.

[0007] In some embodiments, the thickness of the first region is the same as the thickness of the second region. This results in a more uniform thickness of the electrode sheet as a whole, thereby making the structure of the electrode assembly formed by winding the electrode sheet more stable.

[0008] In some embodiments, the compaction density of the second region is lower than that of the first region. This structure increases the electrolyte absorption in the second region, mitigating lithium plating issues caused by expansion deformation and thus improving the cycle life of the battery cell.

[0009] In some embodiments, the slurry layer is cold-pressed to form an active material layer, and the active material layer has the same thickness in the first region and the second region.

[0010] Thus, after the electrode is cold-pressed, an active material layer of the same thickness is successfully formed, thereby achieving a compaction density of less than that of the first region and a porosity of greater than that of the first region.

[0011] In some embodiments, the width of the electrode is d1, and the width of the second region is d2, where 0 < d2 < d1. With the above structure, the overall electrolyte absorption of the electrode is improved, enabling the electrode to absorb and store more electrolyte, and to reabsorb more electrolyte after expansion and deformation.

[0012] In some embodiments, the second region includes a plurality of first sub-regions and a plurality of second sub-regions, wherein the first sub-regions and the second sub-regions are arranged alternately along the width direction of the electrode; wherein the porosity of each first sub-region is greater than the porosity of the first region; and / or, the porosity of each second sub-region is greater than the porosity of the first region.

[0013] By dividing the second region into multiple first sub-regions and multiple second sub-regions, the positions of the first and second sub-regions can be arranged more flexibly according to the different expansion deformations at different locations on the electrode assembly, thereby achieving better electrolyte wetting and effectively improving the overall cycle life of the battery cell.

[0014] In some embodiments, the electrode includes a positive electrode and a negative electrode, both having a first region and a second region; the electrode assembly further includes a separator stacked between the positive and negative electrodes, the positive electrode, the separator, and the negative electrode being wound together to form the electrode assembly, with the winding axis parallel to the width direction of the electrode; wherein, the CB value corresponding to the position of the first region on the electrode assembly is equal to the CB value corresponding to the position of the second region, and the CB value is the ratio of the capacity of the negative electrode to the capacity of the positive electrode per unit area.

[0015] Therefore, if the CB value at the first region position on the electrode assembly is equal to the CB value at the second region position, the lithium ion insertion / extraction between the positive and negative electrodes can be successfully achieved, thereby improving the cycle life of the battery cell.

[0016] Secondly, this application also provides a battery device, including the battery cell as described above.

[0017] Thirdly, this application also provides an electrical device, including the battery device described above.

[0018] In the aforementioned battery cells, battery devices, and electrical equipment, when the electrode sheets are wound to form an electrode assembly, the width direction of the electrode sheets is also the height direction of the electrode assembly. At this time, the first region is located on opposite sides of the second region along the height direction of the electrode assembly, that is, the second region is located in the middle position of the electrode assembly along the height direction of the electrode assembly. Since the porosity of the second region is greater than that of the first region, the middle position of the electrode assembly can absorb more electrolyte. Thus, when the electrode assembly expands and deforms, the middle position of the electrode assembly can reabsorb more electrolyte, improve electrolyte wetting, and thereby improve the cycle life of the battery cell. Attached Figure Description

[0019] Figure 1 This is a structural schematic diagram of a vehicle according to one or more embodiments.

[0020] Figure 2 This is an exploded structural diagram of a battery device according to one or more embodiments.

[0021] Figure 3 This is an exploded structural diagram of a battery cell according to one or more embodiments.

[0022] Figure 4 This is a schematic diagram of the structure of the electrode in a battery cell according to one or more embodiments.

[0023] Figure 5 This is a schematic diagram of the structure of a battery cell after electrode coating according to one or more embodiments.

[0024] Figure 6 This is a schematic diagram of the structure of the electrode in a battery cell after cold pressing, according to one or more embodiments.

[0025] Figure 7 This is a schematic diagram of the structure of the electrode in a battery cell according to one or more embodiments.

[0026] Explanation of reference numerals in the attached drawings: 1000, vehicle; 100, battery device; 200, controller; 300, motor; 10, housing; 20, battery cell; 11, first part; 12, second part; 21, top cover; 22, casing; 23, electrode assembly; 24, electrode sheet; 25, first region; 26, second region; 27, current collector; 28, slurry layer; 29, active material layer; 261, first sub-region; 262, second sub-region; 281, first coating region; 282, second coating region; a, width direction. Detailed Implementation

[0027] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0028] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0029] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., 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, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0032] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0033] Currently, judging from market trends, the application of battery devices is becoming increasingly widespread. Battery devices are not only used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as other fields. With the continuous expansion of the application areas of battery devices, the market demand is also constantly increasing.

[0034] A battery cell is the smallest unit that makes up a battery device. A battery cell typically includes a casing and electrode assemblies. The casing usually includes a housing and a top cover. The top cover is sealed at the opening of the housing, and the top cover and housing together enclose a cavity. The electrode assemblies are placed in the cavity, and then electrolyte is injected into the cavity to ensure that the electrode assemblies are fully wetted with electrolyte.

[0035] The electrode assembly is the component in a battery cell where electrochemical reactions occur. It is mainly formed by winding or stacking positive and negative electrode plates, and usually a separator is placed between the positive and negative electrode plates. The portions of the positive and negative electrode plates containing active material constitute the main body of the electrode assembly, while the portions without active material each constitute a tab. The positive and negative electrode tabs can be located together at one end of the main body or at opposite ends. During the charging and discharging process of the battery, the positive and negative active materials react with the electrolyte, and the tabs connect to the electrode terminals to form a current loop.

[0036] During cycling, the electrode assembly undergoes expansion and deformation. When expansion and deformation occur, some of the electrolyte in the electrode assembly may be squeezed out. After the electrolyte is squeezed out, the migration rate of lithium ions in the electrode assembly will be affected, leading to lithium plating, which in turn affects the overall cycle life of the battery cell.

[0037] Based on the above considerations, to address the issue of electrolyte being squeezed out after the electrode assembly expands and deforms, thus affecting the overall cycle life of the battery cell, one or more embodiments of this application propose a battery cell where, when the electrode sheet is wound to form the electrode assembly, the width direction of the electrode sheet is also the height direction of the electrode assembly. At this time, the first region is located on opposite sides of the second region along the height direction of the electrode assembly; that is, the second region is located in the middle position of the electrode assembly along the height direction. Because the porosity of the second region is greater than that of the first region, the middle position of the electrode assembly can absorb a larger capacity of electrolyte. Thus, when the electrode assembly expands and deforms, the middle position of the electrode assembly can reabsorb more electrolyte, improving electrolyte wetting and thereby increasing the cycle life of the battery cell.

[0038] It should be noted that the battery device 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, which are connected in series, parallel, or mixed connections via a busbar.

[0039] 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.

[0040] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cell assemblies housed within the housing.

[0041] 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.

[0042] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0043] The battery cells disclosed in this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft.

[0044] 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 vehicles, 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.

[0045] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0046] Please refer to Figure 1 The vehicle 1000 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 100 is installed inside the vehicle 1000, and the battery device 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during starting, navigation, and driving.

[0047] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0048] Please refer to Figure 2 The battery device 100 includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which overlap each other, collectively defining a space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 together define the space. Alternatively, both the first portion 11 and the second portion 12 may be hollow structures with one open side, with the open side of the first portion 11 covering the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a cuboid, etc.

[0049] In the battery device 100, there can be multiple battery cells 20, which can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed configuration, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also consist of multiple battery cells 20 first connected in series, parallel, or in a mixed configuration to form battery modules, and then these battery modules are connected in series, parallel, or in a mixed configuration to form a whole, which is also housed within the housing 10. The battery device 100 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 20.

[0050] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited to these. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes.

[0051] Please refer to Figure 3 The battery cell 20 refers to the smallest unit that makes up a battery. For example... Figure 3 The battery cell 20 includes a top cover 21, a housing 22, an electrode assembly 23, and other functional components. The top cover 21 and the housing 22 together form the outer shell of the battery cell 20.

[0052] The top cover 21 is a component that closes onto the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the top cover 21 can be adapted to the shape of the housing 22 to fit it. Optionally, the top cover 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the top cover 21 is less prone to deformation under pressure and impact, allowing the battery cell 20 to have higher structural strength and improved safety performance. Functional components such as electrode terminals can be provided on the top cover 21. The electrode terminals can be used to electrically connect to the electrode assembly 23 for outputting or inputting electrical energy into the battery cell 20. In some embodiments, the top cover 21 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The material of the top cover 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose any special limitations on this. In some embodiments, an insulating element may be provided on the inner side of the top cover 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the top cover 21 to reduce the risk of short circuits. Exemplarily, the insulating element may be made of plastic, rubber, etc.

[0053] The housing 22 is a component used to cooperate with the top cover 21 to form the internal environment of the battery cell 20. This internal environment can accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and the top cover 21 can be independent components. An opening can be provided on the housing 22, and the top cover 21 can close the opening to form the internal environment of the battery cell 20. Alternatively, the top cover 21 and housing 22 can be integrated. Specifically, the top cover 21 and housing 22 can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 22, the top cover 21 closes the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the electrode assembly 23. The material of the housing 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. This application embodiment does not impose any special limitations on this.

[0054] Electrode assembly 23 is the component in the battery cell 20 where electrochemical reactions occur. The casing 22 may contain one or more electrode assemblies 23. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body of the electrode assembly 23, while the portions of the positive and negative electrode sheets without active material each constitute a tab. The positive and negative tabs may be located together at one end of the main body or separately at both ends of the main body. During the charging and discharging process of the battery, the positive and negative active materials react with the electrolyte, and the tabs connect to the electrode terminals to form a current loop.

[0055] Please refer to the following: Figure 3 and Figure 4 One embodiment of this application provides a battery cell 20, including a housing and an electrode assembly 23. The housing has a receiving cavity (not shown in the figure), and the electrode assembly 23 is disposed within the receiving cavity and includes an electrode sheet 24. The electrode sheet 24 has a first region 25 and a second region 26, with the first region 25 located on opposite sides of the second region 26 along the width direction a of the electrode sheet 24. The porosity of the second region 26 is greater than that of the first region 25.

[0056] It should be noted that the outer casing refers to a structure that provides housing space and protection for the electrode assembly 23 and other functional components. The outer casing may include a top cover 21 and a housing 22. One end of the housing 22 has an opening, and the top cover 21 is sealed in the opening, so that the housing 22 and the top cover 21 together enclose and form a housing cavity.

[0057] The electrode assembly 23 is disposed within the receiving cavity and includes an electrode 24, wherein the electrode 24 is a component formed by coating an active material onto the current collector 27. The current collector 27 may be, but is not limited to, copper foil or aluminum foil.

[0058] The electrode 24 has a first region 25 and a second region 26, and the first region 25 is located on opposite sides of the second region 26 along the width direction a of the electrode 24. Specifically, the electrode 24 can be wound to form an electrode assembly 23. When the electrode 24 is wound, the width direction a of the electrode 24 is also the height direction of the electrode assembly 23, that is, the height direction of the battery cell 20.

[0059] A battery cell 20 typically includes two large surfaces, two side surfaces, a top surface, and a bottom surface. The large surfaces refer to the surface with the largest area in the battery cell 20. The two large surfaces are parallel to each other, the two side surfaces are parallel to each other, and the two side surfaces are perpendicular to the two large surfaces. The top surface is constructed as the upper surface of the top cover 21, and the bottom surface is the surface that is parallel to and opposite to the top surface.

[0060] Understandably, the shape of the battery cell 20 matches the shape of the electrode assembly 23. Therefore, the electrode assembly 23 also has two large surfaces, two side surfaces, a top surface, and a bottom surface that correspond to the battery cell 20, respectively.

[0061] When the electrode assembly 23 expands and deforms, the two larger surfaces, due to their largest area, experience the greatest expansion deformation, especially the middle position of the larger surfaces. Consequently, the electrolyte in the middle position of the larger surfaces is more easily squeezed out. After the electrolyte is squeezed out, lithium plating is more likely to occur at this position, which in turn affects the cycle life of the battery cell 20.

[0062] Therefore, the first region 25 can be set as two, and located on opposite sides of the second region 26 along the width direction a of the electrode 24, so that the second region 26 along the width direction a of the electrode 24, that is, the height direction of the battery cell 20, corresponds to the middle position of the large surface of the electrode assembly 23.

[0063] Among them, the height direction of the battery cell 20 refers to the direction perpendicular to the top and bottom surfaces, the width direction 'a' of the battery cell 20 refers to the direction perpendicular to the side surface, and the thickness direction of the battery cell 20 refers to the direction perpendicular to the large surface.

[0064] Furthermore, the porosity of the second region 26 is greater than that of the first region 25. Porosity refers to the percentage of pore area per unit area of ​​the electrode 24. Therefore, the second region 26 has a larger pore area for storing electrolyte. On one hand, the second region 26 stores a larger capacity of electrolyte. Thus, even if the deformation of the second region 26 is large, the initial electrolyte content in the second region 26 is greater, allowing more electrolyte to remain after the expansion and deformation. On the other hand, after the electrolyte in the second region 26 is squeezed out, the electrolyte temporarily remains in the receiving cavity, and the second region 26 can also draw back more electrolyte from the receiving cavity, allowing for electrolyte rewetting.

[0065] Therefore, with the above structure, when the electrode assembly 23 expands and deforms, the second region 26 can retain more electrolyte or draw more electrolyte back from the containment cavity, improving electrolyte wetting and thus increasing the cycle life of the battery cell 20.

[0066] In some embodiments, the thickness of the first region 25 is the same as the thickness of the second region 26.

[0067] Specifically, since the electrode 24 is composed of the current collector 27 and the active material coated on the current collector 27, the thickness of the first region 25 and the thickness of the second region 26 specifically refer to the total thickness of the current collector 27 and the active material thereon.

[0068] The thickness of the first region 25 is the same as that of the second region 26, which makes the electrode 24 have a more uniform thickness, thereby making the structure of the electrode assembly 23 formed by winding the electrode 24 more stable.

[0069] In some embodiments, the compaction density of the second region 26 is less than that of the first region 25.

[0070] Specifically, compaction density refers to the weight of an active material per unit volume. The higher the compaction density, the smaller the gap between particles, and vice versa.

[0071] The compaction density of the second region 26 is less than that of the first region 25, so the gaps between the active material particles in the second region 26 are larger. As a result, the second region 26 can store more electrolyte.

[0072] Therefore, the above structure can increase the absorption of electrolyte in the second region 26, improve the lithium plating problem caused by expansion deformation in the second region 26, and thus improve the cycle life of the battery cell 20.

[0073] like Figure 5 and Figure 6As shown, in some embodiments, the electrode 24 includes a current collector 27 and a slurry layer 28 coated on the current collector 27. The slurry layer 28 located in the first region 25 is configured as a first coating region 281, and the slurry layer 28 located in the second region 26 is configured as a second coating region 282. The thickness of the first coating region 281 is greater than the thickness of the second coating region 282.

[0074] Specifically, the current collector 27 can be used as a coating substrate, and the slurry layer 28 is the active material coated on the current collector 27.

[0075] It should be noted that the active material can be divided into positive electrode active material and negative electrode active material. Coating the positive electrode active material onto the current collector 27 forms a positive electrode sheet, and coating the negative electrode active material onto the current collector 27 forms a negative electrode sheet.

[0076] Furthermore, the portion of the electrode 24 coated with an active material layer forms the main body of the electrode assembly 23, while the portion without an active material layer forms the tabs of the electrode assembly 23. The tabs can be located on one side of the main body along the width direction a of the electrode 24, or on opposite sides of the main body along the width direction a of the electrode 24.

[0077] In the specific manufacturing process, a slurry layer 28 of different thicknesses can be coated in the first region 25 and the second region 26 using a coating device; that is, the thickness of the first coating region 281 is greater than the thickness of the second coating region 282. Then, the slurry layer 28 is subjected to a cold pressing operation to form the final electrode 24.

[0078] With the above structure, slurry layers 28 with different thicknesses of the first region 25 and the second region 26 can be smoothly formed during the coating process. Then, after cold pressing, active material layers 29 of the same thickness are formed, and finally the compaction density and porosity of the first region 25 and the second region 26 are achieved respectively. The operation is convenient and the production efficiency is high.

[0079] In some embodiments, the slurry layer 28 is cold-pressed to form an active material layer 29, the active material layer 29 having the same thickness in the first region 25 and the second region 26.

[0080] Specifically, after coating, the electrode 24 is usually cold-pressed to form the slurry layer 28 into an active material layer 29. The fact that the thickness of the first region 25 is the same as the thickness of the second region 26 means that after cold pressing, the active material layer 29 of the first region 25 and the active material layer 29 of the second region 26 have the same thickness.

[0081] Thus, after the electrode 24 is cold-pressed, an active material layer 29 of the same thickness is successfully formed, thereby achieving a compaction density of the second region 26 that is less than that of the first region 25, and a porosity of the second region 26 that is greater than that of the first region 25.

[0082] In some embodiments, the thickness at the junction of the first coating area 281 and the second coating area 282 gradually decreases from the first coating area 281 to the second coating area 282.

[0083] Specifically, a transition zone can be formed at the connection point between the first coating area 281 and the second coating area 282, that is, the thickness of the slurry layer 28 in the transition zone gradually decreases from the first coating area 281 to the second coating area 282.

[0084] This allows the slurry layer 28 to transition smoothly between the first coating area 281 and the second coating area 282, making the structure of the electrode 24 more stable after cold pressing.

[0085] In some embodiments, the width of the electrode 24 is d1, and the width of the second region 26 is d2, wherein 0 < d2 < d1.

[0086] Specifically, the wider the second region 26, the greater the overall electrolyte absorption of the electrode 24, the more electrolyte the electrode 24 can absorb and store, and the more electrolyte can be reabsorbed after expansion and deformation.

[0087] like Figure 7 As shown, in some embodiments, the second region 26 includes a plurality of first sub-regions 261 and a plurality of second sub-regions 262, with each first sub-region 261 and each second sub-region 262 arranged alternately along the width direction a of the electrode 24. The porosity of each first sub-region 261 is greater than the porosity of the first region 25. And / or, the porosity of each second sub-region 262 is greater than the porosity of the first region 25.

[0088] Specifically, the second region 26 can be set as a whole region, or it can be divided into multiple first sub-regions 261 and second sub-regions 262. When the second region 26 includes multiple first sub-regions 261 and multiple second sub-regions 262, each first sub-region 261 and each second sub-region 262 are arranged alternately along the width direction a of the electrode 24.

[0089] Furthermore, the porosity of either the first sub-region 261 or the second sub-region 262 may be greater than the porosity of the first region 25, or both the porosity of the first sub-region 261 and the second sub-region 262 may be greater than the porosity of the first region 25.

[0090] Furthermore, the porosity of the first sub-region 261 and the second sub-region 262 can be the same or different. When the porosity of one of the first sub-region 261 and the second sub-region 262 is greater than the porosity of the first region 25, the porosity of the other can be set to be equal to the porosity of the first region 25.

[0091] By dividing the second region 26 into multiple first sub-regions 261 and multiple second sub-regions 262, the positions of the first sub-regions 261 and the second sub-regions 262 can be arranged more flexibly according to the different expansion deformations at different positions on the electrode assembly 23, thereby better achieving electrolyte wetting and effectively improving the overall cycle life of the battery cell 20.

[0092] In some embodiments, the electrode 24 includes a positive electrode and a negative electrode, both having a first region 25 and a second region 26. The electrode assembly 23 further includes a separator (not shown) stacked between the positive and negative electrodes. The positive electrode, separator, and negative electrode are wound together to form the electrode assembly 23, with the winding axis parallel to the width direction a of the electrode 24. The CB value at the position corresponding to the first region 25 on the electrode assembly 23 is equal to the CB value at the position corresponding to the second region 26, and the CB value is the ratio of the capacity of the negative electrode to the capacity of the positive electrode per unit area.

[0093] Specifically, CB is the ratio of the capacity of the negative electrode active material per unit area to the capacity of the positive electrode active material per unit area.

[0094] Therefore, the CB value at the position corresponding to the first region 25 on the electrode assembly 23 is equal to the CB value at the position corresponding to the second region 26, which enables the successful intercalation and deintercalation of lithium ions between the positive and negative electrodes, thereby improving the cycle life of the battery cell 20.

[0095] Based on the same concept as the battery cell 20 described above, this application also provides a battery device 100, including the battery cell 20 as described above.

[0096] Based on the same concept as the battery device 100 described above, this application also provides an electrical device including the battery device 100 as described above.

[0097] According to one or more embodiments, in specific use of this application, a positive electrode active material and a negative electrode active material are first coated on the current collector 27, wherein the positive electrode active material and the negative electrode active material each have a first region 25 and a second region 26. The first region 25 is located on opposite sides of the second region 26 along the width direction a of the electrode 24, and the thickness of the positive electrode active material or the negative electrode active material in the first region 25 is greater than the thickness of the positive electrode active material or the negative electrode active material in the second region 26.

[0098] Furthermore, the positive and negative active materials are cold-pressed to form a positive active material layer and a negative active material layer, thereby forming a positive electrode sheet and a negative electrode sheet. The porosity of the second region 26 is greater than that of the first region 25, and the compaction density of the second region 26 is less than that of the first region 25.

[0099] During the cycle of the battery cell 20, the second region 26 corresponds to the middle position of the large surface of the electrode assembly 23. It can effectively improve the lithium plating problem caused by the expansion deformation of the middle position of the large surface squeezing out the electrolyte, so that the electrode assembly 23 can be better wetted with electrolyte and effectively improve the cycle life of the battery cell 20.

[0100] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0101] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A battery cell, characterized in that, include: The outer shell has a receiving cavity; and An electrode assembly is disposed within the receiving cavity and includes an electrode sheet having a first region and a second region. The first region is located on opposite sides of the second region along the width direction of the electrode sheet. The porosity of the second region is greater than that of the first region. The electrode includes a current collector and a slurry layer coated on the current collector. The slurry layer located in the first region is configured as a first coating region, and the slurry layer located in the second region is configured as a second coating region. The thickness of the first coating region is greater than the thickness of the second coating region, and the thickness at the connection between the first coating region and the second coating region gradually decreases from the first coating region to the second coating region.

2. The battery cell according to claim 1, characterized in that, The thickness of the first region is the same as the thickness of the second region.

3. The battery cell according to claim 1 or 2, characterized in that, The compaction density of the second region is less than that of the first region.

4. The battery cell according to claim 1, characterized in that, The slurry layer is cold-pressed to form an active material layer, and the active material layer has the same thickness in the first region and the second region.

5. The battery cell according to claim 1, characterized in that, The width of the electrode is d1, and the width of the second region is d2, where 0 < d2 < d1.

6. The battery cell according to claim 1, characterized in that, The second region includes a plurality of first sub-regions and a plurality of second sub-regions, with each first sub-region and each second sub-region arranged alternately along the width direction of the electrode sheet; Wherein, the porosity of each of the first sub-regions is greater than the porosity of the first region; and / or, the porosity of each of the second sub-regions is greater than the porosity of the first region.

7. The battery cell according to claim 1, characterized in that, The electrode includes a positive electrode and a negative electrode, and both the positive electrode and the negative electrode have the first region and the second region; The electrode assembly further includes a separator stacked between the positive electrode and the negative electrode, wherein the positive electrode, the separator, and the negative electrode are wound together to form the electrode assembly, and the winding axis is parallel to the width direction of the electrode. Wherein, the CB value corresponding to the first region position on the electrode assembly is equal to the CB value corresponding to the second region position, and the CB value is the ratio of the capacity of the negative electrode to the capacity of the positive electrode per unit area.

8. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1-7.

9. An electrical appliance, characterized in that, Includes the battery device as described in claim 8.

Images