Battery cell, battery device, electric equipment and manufacturing method of battery cell

Abstract

The invention provides a single battery, a battery device, electric equipment and a manufacturing method of the single battery, and the single battery comprises a shell with a containing cavity; the electrode assembly is arranged in the accommodating cavity, the electrode assembly comprises a pole piece, and the pole piece comprises a current collector and an active material layer arranged on at least one side of the current collector in the thickness direction; in the width direction of the current collector, the thickness difference of the active material layer is less than or equal to 10%. According to the invention, the energy density of the single battery can be improved, and the endurance of the single battery is ensured.

Description

Technical Field

[0001] This application relates to the field of batteries, and in particular to battery cells, battery devices, electrical equipment, and methods for manufacturing battery cells. Background Technology

[0002] Energy conservation and emission reduction are key to the sustainable development of the automotive industry, and electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of this sustainable development. For electric vehicles, battery technology is a crucial factor in their development.

[0003] However, the battery cells in this technology suffer from low energy density, which affects the battery device's range. Summary of the Invention

[0004] In view of the above problems, this application provides a battery cell, a battery device, an electrical device, and a method for manufacturing a battery cell, which can improve the energy density of the battery cell and ensure the battery cell's range.

[0005] In a first aspect, this application provides a battery cell, comprising: a casing having a receiving cavity; an electrode assembly disposed in the receiving cavity, the electrode assembly comprising an electrode sheet, the electrode sheet comprising a current collector and an active material layer disposed on at least one side of the current collector in the thickness direction; the thickness difference of the active material layer along the width direction of the current collector is ≤10%.

[0006] By limiting the thickness difference of the active material layer along the width of the current collector to ≤10%, there are no thinning zones in the active material layer along the width of the electrode. This ensures that the thickness of the active material layer is consistent or nearly consistent throughout the current collector, maximizing the amount of active material loaded per unit area of ​​the electrode. This effectively increases the energy density of the battery cell and improves its range. Furthermore, this structural design, resulting in a consistent or nearly consistent active material layer thickness throughout the current collector of the battery cell, fundamentally avoids lithium plating caused by poor control of thinning zones, reducing safety risks such as battery short circuits and thermal runaway, and improving the reliability of the battery cell.

[0007] In some embodiments, the electrode assembly includes a pair of electrodes, one of which is a cathode electrode and the other is an anode electrode. The cathode electrode includes a cathode current collector and a cathode active material layer disposed on at least one side of the cathode current collector in the thickness direction. The anode electrode includes an anode current collector and an anode active material layer disposed on at least one side of the anode current collector in the thickness direction. In the thickness direction, the orthographic projection of the anode active material layer covers the orthographic projection of the cathode active material layer. The thickness difference between the cathode active material layer and the anode active material layer is ≤10%.

[0008] With the above configuration, neither the anode nor the cathode of the battery cell needs to be thinned, and the thickness of the corresponding regions of their active material layers is consistent or nearly consistent. A thickness difference of ≤10% in the cathode active material layer effectively increases the active material loading and significantly increases the amount of lithium ions released. The full-coverage anode projection design and a thickness difference of ≤10% in the anode active material layer allow for a larger effective reaction area at the anode edge, providing sufficient active sites and space to accommodate them. This achieves a dynamic balance between the amount of lithium ions released from the cathode and the amount of lithium ions accommodated at the anode, effectively avoiding lithium plating caused by insufficient anode edge area and excessive lithium ion deposition in related technologies, thus improving the reliability of the battery cell.

[0009] In some embodiments, the thickness difference of the active material layer along the width direction of the current collector is less than or equal to 6 μm. By limiting the absolute value of the thickness difference of the active material layer along the width direction to ≤6 μm, it is beneficial to ensure the uniformity of the active material distribution, avoid the problem of uneven charging and discharging current density caused by local thickness deviations, and ensure the energy density requirements.

[0010] In some embodiments, the active material layer includes a main body portion and an edge portion distributed along the width direction of the current collector. In the thickness direction, the thickness dimension of the main body portion is M1, and the thickness dimension of the edge portion is M2, wherein 90% ≤ M2 / M1 ≤ 110%. This configuration structurally ensures that the active material loading at the edge portion is substantially consistent with that of the main body portion, guaranteeing the energy density of the battery cell. Furthermore, a thickness difference of less than 10% balances the structural stability and electrochemical performance of the active material layer, avoiding problems such as insufficient drying and stress concentration during cold pressing caused by excessive edge thickness. Simultaneously, it provides a clear zoning standard for thickness detection during production, facilitating process control, improving production consistency, reducing the risk of lithium plating in battery cells, and ensuring the reliability of the battery cells.

[0011] In some embodiments, the main body and the edge portion are integrally formed. With this configuration, while ensuring the required thickness in each region of the active material layer, extensive process design and debugging are unnecessary during molding, simplifying the process and reducing the precision requirements of the equipment. For the edge portion, secondary processing steps such as thinning and calibration can be eliminated, reducing equipment investment, energy consumption, and maintenance costs, shortening the production cycle, and improving efficiency.

[0012] In some embodiments, the difference between the thickness dimension M1 of the main body and the thickness dimension M2 of the edge is less than or equal to 6 μm. This setting effectively adapts to the design requirements of electrode sheets with different thickness specifications, ensuring that the thickness of the edge is consistent with the thickness of the main body, reducing the probability of energy density loss or structural defects caused by differences in thickness. Furthermore, a difference of less than or equal to 6 μm between the thickness dimension M1 of the main body and the thickness dimension M2 of the edge ensures uniform current distribution during charging and discharging, reduces the risk of local overcharging and over-discharging, suppresses lithium plating, and requires the electrode forming process of the battery cell to provide a more stable thickness base, avoiding problems such as bright edges and stretching deformation caused by excessive thickness deviation between the edge and the main body. This enhances the stability of the manufacturing process and the battery safety performance, achieving synergistic optimization of precision, performance, and process.

[0013] In some embodiments, the edge portion includes a region of the active material layer within 10 mm of its own edge in the width direction.

[0014] By ensuring that the active material layer is within 10mm of its own edge in the width direction, the distribution of the active material layer can be rationally planned to meet the requirements of the molding process. Furthermore, after testing, it was found that the thickness of the active material layer in the 10mm edge region is consistent with or close to the thickness of the main body. Compared with related technologies, this effectively increases the active material content in the edge region, which can stably achieve an energy density increase of about 6% in this region. This strengthens the overall energy density advantage of the cell and gives the battery cell a comprehensive advantage of no thinning, low cost, and high performance.

[0015] In some embodiments, in the width direction, the cathode active material layer has a first edge, and the anode active material layer has a second edge that is on the same side as the first edge and spaced apart from it. The minimum vertical distance between the first edge and the second edge is d1, where 0 <d1≤3mm。

[0016] By limiting the size of d1 and combining the advantages of the non-thinning electrode structure of the battery cell, the limitations of d1 size control in related technologies are overcome. On the one hand, because the electrode edge is not thinned and the thickness is uniform, there is no need to reserve a larger d1 size to avoid the risk of lithium plating and short circuit caused by uneven thinning. The d1 size can be minimized to close to 0. Under the premise of ensuring safe spacing, the ineffective space at the edge of the bipolar electrode is reduced, the space utilization of the electrode assembly is improved, and the energy density advantage of the battery cell is enhanced.

[0017] In some embodiments, the cathode electrode further includes an insulating layer, the cathode current collector includes a first main body region and a first tab region distributed along the width direction, the cathode active material layer is disposed in the first main body region, the insulating layer is disposed on the side of the cathode active material layer facing the first tab region, the insulating layer partially covers the first main body region and the first tab region, and the thickness of the edge portion of the cathode active material layer is greater than the thickness of the insulating layer.

[0018] The above-mentioned design allows for a thicker edge portion of the electrode compared to related technologies, ensuring that the active material loading at the edge meets the standards and guaranteeing energy density. Furthermore, the insulating layer prevents metal debris generated during die-cutting of the anode electrode from piercing the separator and contacting the cathode electrode, thus avoiding short circuits and improving the reliability of the individual battery cells.

[0019] In some embodiments, the orthographic projection of the insulating layer does not coincide with the orthographic projection of the cathode active material layer in a plane perpendicular to the thickness direction of the cathode current collector.

[0020] By employing the above design, while ensuring effective insulation, the effective reaction area of ​​the active material layer is maximized. This avoids situations where the insulating layer covers the active material layer, preventing localized areas from participating in the electrochemical reaction. It ensures that the active material in both the edge and main body regions can fully function, guaranteeing the energy density requirements of the battery cells. Furthermore, the non-projection overlap design avoids excessive local thickness caused by the overlapping of the insulating and active material layers. It also facilitates sufficient electrolyte wetting of the edges of the active material layer, preventing insufficient wetting caused by the insulating layer blocking the edges. This further optimizes the battery's electrochemical performance and structural stability, achieving a synergistic improvement in insulation performance and activity efficiency.

[0021] Secondly, this application provides a battery device including the aforementioned battery cell.

[0022] Thirdly, this application provides an electrical device including the aforementioned battery device.

[0023] Fourthly, this application provides a method for manufacturing a single battery cell, comprising the following steps: The active material, conductive agent, and binder are mixed and stirred to form an active substance powder. The active material powder is rolled to form an active material layer; An active material layer is laminated onto a current collector to form an electrode. The thickness difference of the active material layer along the width direction of the current collector is ≤10%. Electrodes and separators are stacked together to form a single battery cell.

[0024] One embodiment of this application provides a method for manufacturing a battery cell using a dry electrode process. This process eliminates the need for solvents in the preparation of the mixture and removes the high-energy-consuming drying equipment. As a result, the electrode forming process eliminates the need for complex steps such as slurry stirring and drying. The electrode can achieve the required uniformity of the active material layer thickness through three core steps: mixing, rolling, and lamination. This significantly simplifies the production process, reduces equipment investment, energy consumption, and maintenance costs, shortens the production cycle, and improves production efficiency. Furthermore, the manufacturing method can reasonably control the thickness of the active material layer, achieving a thickness difference of ≤10% in the width direction. This avoids the thickness unevenness and bulging issues caused by solvent evaporation and surface tension in related technologies. Simultaneously, it eliminates the need for secondary processing such as thinning and calibration, avoiding physical damage caused by mechanical thinning. This ensures the structural integrity and performance consistency of the electrode, providing process assurance for the high energy density and high reliability of the battery cell.

[0025] In some embodiments, the step of mixing and stirring the active material, conductive agent, and binder into active material powder includes: controlling the stirring speed and stirring temperature to form a portion of the binder into bonding fibers, which are used to connect the active material. This arrangement facilitates the calendering and molding of the active material layer, ensuring the reliability of the formed battery cell.

[0026] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0027] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the structure of a vehicle according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a battery device according to an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a single battery cell according to an embodiment of this application; Figure 4 This is a partial structural schematic diagram of the anode plate of a battery cell according to an embodiment of this application; Figure 5 yes Figure 4 A cross-sectional view along the AA direction; Figure 6 This is a partial structural schematic diagram of the cathode electrode of a battery cell according to an embodiment of this application; Figure 7 yes Figure 6 A cross-sectional view along the BB direction; Figure 8 This is a partial structural schematic diagram of the mating of the cathode electrode and the anode electrode according to another embodiment of this application; Figure 9 This is a schematic flowchart of a method for manufacturing a battery cell according to an embodiment of this application.

[0028] Marker explanation: 1. Vehicle; 100. Battery unit; 300. Controller; 400. Motor; 200. Battery cell assembly; 10. Box; 10a. First box; 10b. Second box; 20. Battery cell; 21. Outer shell; 211. Housing; 212. End cap; 22. Electrode assembly; 22a. Electrode body; 22b. Electrode tab; 220, Electrode; 2201, Current collector; 2202, Active material layer; 2202a, Main body; 2202b, Edge; 221. Cathode electrode; 2211, Cathode current collector; 2211a, First main body region; 2211b, First tab region; 2212, Cathode active material layer; 2212a, First edge; 222, Anode electrode; 2221, Anode current collector; 2222, Anode active material layer; 2222a, Second edge; 223. Insulation layer; 23. Electrode terminals; X represents the width direction; Y represents the thickness direction. Detailed Implementation

[0029] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0030] It should be noted that, unless otherwise stated, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by those skilled in the art to which the embodiments of this application pertain.

[0031] In the description of the embodiments of this application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and 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. Therefore, they should not be construed as limitations on the embodiments of this application.

[0032] Furthermore, technical terms such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of the embodiments of this application, "a plurality of" means two or more, unless otherwise explicitly defined.

[0033] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0034] In the description of the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through 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. "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.

[0035] Currently, judging from market trends, the application of power batteries is becoming increasingly widespread. Power batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of power battery applications, market demand is also constantly increasing.

[0036] In the development of power battery technology, driving range has always been a key indicator restricting its application. Industry practice shows that battery devices using related technologies suffer from short driving range and insufficient continuous working time, especially in range-sensitive scenarios such as new energy vehicles and portable energy storage devices. Through disassembly and data analysis of mainstream technical solutions, it was found that one of the core issues causing poor driving range lies in the electrode preparation process. Typically, after the slurry formed by mixing active material and solvent is coated onto the current collector surface, the wet film area tends to exhibit an arc-shaped profile, thicker in the middle and thinner at the edges, due to factors such as the surface tension of the slurry itself and the operating precision of the coating equipment. To remove the solvent from the slurry and ensure the active material adheres firmly to the current collector, the coated electrode needs to be dried. Because the wet film is thinner at the edges, the solvent evaporates significantly faster than in the middle, resulting in a higher surface tension at the edges. Driven by this surface tension difference, the incompletely dried slurry flows and accumulates towards the edges, ultimately leading to edge bulging and uneven thickness in the dried electrode.

[0037] To address the aforementioned issues, related technologies typically employ edge thinning techniques during coating. By reducing the amount of slurry coating in the edge area of ​​the electrode, the thickness of the wet film at the edge is further reduced. This balances the slurry flow trend during the drying process, resulting in the electrode of the formed battery cell being thicker in the middle and thinner on both sides in the width direction. This can suppress edge bulging to some extent. However, it also results in insufficient coating of active material in the edge thinning area, reducing the capacity per unit area of ​​the electrode and consequently causing a decrease in the overall energy density of the battery cell, making it difficult to meet the range requirements.

[0038] Research has found that by adjusting the electrode structure of a battery cell, the electrode can include a current collector and an active material layer disposed on at least one side of the current collector in its thickness direction. Furthermore, the thickness difference of the active material layer along the width direction of the current collector should be ≤10%, ensuring a more uniform thickness across different regions. This guarantees energy density requirements and improves battery life. In the molding process, active materials, conductive agents, and binders can be mixed and stirred to form active material powder. This powder is then rolled to form an active material layer, which is then laminated onto the current collector. This eliminates the need for a drying step, preventing edge bulging and ensuring the reliability of the battery cell.

[0039] The technical solutions described in this application are applicable to battery devices and electrical equipment. Electrical equipment can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical equipment.

[0040] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0041] For example, such as Figure 1 As shown, vehicle 1 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. The interior of vehicle 1 can house a motor 400, a controller 300, and a battery device 100. The controller 300 controls the battery device 100 to supply power to the motor 400. For example, the battery device 100 can be located at the bottom, front, or rear of vehicle 1. The battery device 100 can be used to power vehicle 1; for example, it can serve as the operating power source for the vehicle 1's electrical system, such as meeting the power requirements for starting, navigation, and operation. In another embodiment of this application, the battery device 100 can not only serve as the operating power source for vehicle 1 but also as the driving power source, replacing or partially replacing gasoline or natural gas to provide driving power to vehicle 1.

[0042] It should be understood that the technical solutions described in the embodiments of this application are not limited to the above-mentioned vehicle 1.

[0043] In some embodiments, the battery device 100 may also be used in energy storage devices, such as energy storage cabinets or energy storage containers.

[0044] like Figure 2 As shown, a battery device 100 provided in one embodiment of this application may include one or more battery cell assemblies 200 for providing voltage and capacity in some embodiments.

[0045] The battery cell assembly 200 may include multiple battery cells 20, which are connected in series, parallel, or mixed connection via a busbar. Mixed connection means that some of the multiple battery cells 20 are connected in series and others in parallel.

[0046] The battery cell 20 can be a secondary battery cell 20, which refers to a battery cell 20 that can be used again after being discharged by recharging to activate the active materials.

[0047] As an example, the battery cell 20 can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc.

[0048] As an example, the battery cell 20 can be a prismatic battery cell, which includes prismatic battery cells, blade-shaped battery cells, and multi-prismatic battery cells, such as hexagonal prismatic battery cells.

[0049] In some embodiments, the battery cell assembly 200 is typically formed by arranging a plurality of battery cells 20. As an example, the battery cell assembly 200 can be a battery module, which is formed by arranging and fixing a plurality of battery cells 20 into a single module. As an example, a battery module can be formed by bundling multiple battery cells 20 together with cable ties.

[0050] In some embodiments, the battery device 100 may be a battery pack, which includes a housing 10 and one or more battery cell assemblies 200, the battery cell assemblies 200 being housed within the housing 10. As an example, the battery cell assembly 200 may be a battery module, and the battery cell assembly 200 may be housed within the housing 10 by securing a battery module to the housing 10. As an example, the battery cell assembly 200 may also be housed within the housing 10 by directly securing multiple battery cells 20 to the housing 10.

[0051] In some embodiments, the housing 10 is used to house the battery cell 20, and the housing 10 can have various structures.

[0052] In some embodiments, the housing 10 may include a first housing 10a and a second housing 10b. The first housing 10a and the second housing 10b are fastened together to form a closed space inside the housing 10 to house the battery cell assembly 200. Here, "closed" refers to covering or closing, and can be sealed or unsealed. The first housing 10a may be a top cover or a bottom plate.

[0053] In some embodiments, the housing 10 may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, thereby forming an enclosed space inside the housing 10 to accommodate the battery cell assembly 200. As an example, the frame may include multiple side beams.

[0054] In some embodiments, the housing 10 may be part of the chassis structure of the vehicle 1. For example, a portion of the housing 10 may be at least a portion of the floor of the vehicle 1, or a portion of the housing 10 may be at least a portion of the crossbeams and longitudinal beams of the vehicle 1.

[0055] In some embodiments, the battery device 100 may be an energy storage device.

[0056] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, energy storage devices can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours.

[0057] In some embodiments, the energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0058] The battery device 100 may include multiple battery cells 20, which are connected in series, parallel, or mixed connection via a busbar. Mixed connection means that some of the multiple battery cells 20 are connected in series and some in parallel.

[0059] like Figures 3 to 5 As shown, one embodiment of this application also provides a battery cell 20, including a housing 21 and an electrode assembly 22. The housing 21 has a receiving cavity, and the electrode assembly 22 is disposed in the receiving cavity.

[0060] In some embodiments, the outer casing 21 may be a steel casing, an aluminum casing, a plastic casing (such as a polypropylene casing), or a composite metal casing, etc.

[0061] In some embodiments, the housing 21 can be a sealed structure or a non-sealed structure. As an example, when the housing 21 is a non-sealed structure, it serves to protect the electrode assembly 22, and a sealing bag is included between the housing 21 and the electrode assembly 22. The sealing bag is used to encapsulate the electrode assembly 22 and the electrolyte. Specifically, the sealing bag can be a bag-shaped insulating component or an aluminum-plastic film. When the housing 21 is a sealed structure, it is used to encapsulate the electrode assembly 22 and the electrolyte, among other components.

[0062] In some embodiments, the casing 21 of the battery cell 20 may be a square casing, a prismatic casing, or a casing of other shapes.

[0063] In some embodiments, the housing 21 includes a housing 211 and an end cap 212, the housing 211 having an opening, and the end cap 212 being connected to the housing 211 and covering the opening.

[0064] The housing 211 is a component used to fit the end cap 212 to form an internal cavity of the battery cell 20. The formed internal cavity can be used to accommodate the electrode assembly 22, electrolyte, and other components.

[0065] The housing 211 and the end cap 212 can be separate components. For example, an opening can be provided on the housing 211, and the end cap 212 can be used to close the opening to form an internal cavity for the battery cell 20.

[0066] The housing 211 can be of various shapes and sizes, such as cuboid or cylindrical. Specifically, the shape of the housing 211 can be determined according to the specific shape and size of the electrode assembly 22. The housing 211 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0067] The shape of the end cap 212 can be adapted to the shape of the housing 211 to fit the housing 211. The material of the end cap 212 can be the same as or different from the material of the housing 211. Optionally, the end cap 212 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.), so that the end cap 212 is not easily deformed when subjected to compression and impact, so that the battery cell 20 can have higher structural strength and improve reliability.

[0068] The end cap 212 is connected to the housing 211 by welding, bonding, snap-fitting or other means.

[0069] The housing 211 may be open at one end or open at both ends. In some examples, the housing 211 may be a structure with an opening on one side, and an end cap 212 is provided and covers the housing 211. In other examples, the housing 211 may also be a structure with openings on both sides, and two end caps 212 are provided, with the two end caps 212 respectively covering the two openings of the housing 211.

[0070] In some embodiments, the electrode assembly 22 is a component in the battery cell 20 where an electrochemical reaction occurs. The housing 21 may contain one or more electrode assemblies 22. Optionally, the electrode assembly 22 is housed within the housing 21.

[0071] The electrode assembly 22 can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0072] In some embodiments, the electrode assembly 22 is a wound structure. The cathode electrode and the anode electrode are wound into a wound structure.

[0073] In some embodiments, the electrode assembly 22 is a stacked structure.

[0074] As an example, multiple cathode electrodes and multiple anode electrodes can be set, and multiple cathode electrodes and multiple anode electrodes can be stacked alternately.

[0075] As an example, multiple cathode electrodes can be provided, and the anode electrodes can be folded to form multiple stacked folded segments, with a cathode electrode sandwiched between adjacent folded segments.

[0076] As an example, both the cathode and anode plates are folded to form multiple stacked folded segments.

[0077] As an example, multiple spacers can be provided, each positioned between any adjacent cathode or anode electrode.

[0078] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent cathode or anode plates.

[0079] In some embodiments, the electrode assembly 22 may be cylindrical, flat, or polygonal, etc.

[0080] In some embodiments, the battery cell 20 further includes an electrode terminal 23, which may be disposed on the end cap 212 or the housing 211, and is electrically connected to the electrode assembly 22.

[0081] In some embodiments, the battery cell 20 further includes an electrolyte housed within the casing 21. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid.

[0082] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0083] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0084] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0085] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell 20, such as additives that improve the overcharge / fast charge performance of the battery cell 20, additives that improve the high-temperature performance of the battery cell 20, additives that improve the low-temperature performance of the battery cell 20, etc.

[0086] like Figures 1 to 5 As shown, one embodiment of this application provides a battery cell 20, which may include a housing 21 and an electrode assembly 22. The housing 21 has a receiving cavity, and the electrode assembly 22 is disposed in the receiving cavity. The electrode assembly 22 includes an electrode sheet 220. The electrode sheet 220 includes a current collector 2201 and an active material layer 2202 disposed on at least one side of the current collector 2201 in the thickness direction Y. Along the width direction X of the current collector 2201, the thickness difference of the active material layer 2202 is ≤10%.

[0087] Electrode 220 can be understood as at least one of a cathode electrode and an anode electrode. Figure 4 , Figure 5 The electrode 220 shown can be selected as an anode electrode 222.

[0088] In some embodiments, for the wound electrode assembly 22, the width direction X of the current collector 2201 can be understood as the width direction of the electrode 220, that is, the direction perpendicular to the winding axis of the electrode 220.

[0089] In some embodiments, the electrode assembly 22 may include an electrode body 22a and a tab 22b. For a stacked electrode assembly 22, the width direction X of the current collector 2201 can be understood as the arrangement direction of the electrode body 22a and the tab 22b.

[0090] When the electrode assembly is a hybrid structure of winding and stacking, the width direction X of the two can be the same. The winding part or the stacking part can be used as the judgment standard. For specific direction judgment requirements, refer to the above-mentioned winding electrode assembly 22 and stacking electrode assembly 22.

[0091] It should be noted that the percentage representing the thickness difference of the active material layer 2202 is typically used to indicate the deviation, non-uniformity, or out-of-tolerance ratio of the active material layer 2202. The formula can be: Thickness difference = (Actual thickness of any region of active material layer 2202 - Standard thickness) / Standard thickness × 100%.

[0092] In some embodiments, the standard thickness may be the thickness of one of the main regions of the active material layer 2202, for example, the thickness of the central region of the electrode 220 along the thickness direction Y.

[0093] Of course, in some optional embodiments, the standard thickness can also be the average thickness of each region of the active material layer 2202. For example, the active material layer can be divided into n regions, where n≥2, and the average of the thickness values ​​of each region can be used as the standard thickness.

[0094] Optionally, the thickness difference of the active material layer 2202 is less than or equal to 5%. In some optional embodiments, the thickness difference of the active material layer 2202 may be less than or equal to 4%, 3%, 2% or 1%, and optionally, the thickness difference may be 0.

[0095] In one embodiment of this application, the battery cell 20 is formed by first mixing and stirring the active material, conductive agent, and binder to form an active material powder. The active material powder is then rolled to form an active material layer 2202. The active material layer 2202 is then laminated onto a current collector 2201 to form an electrode 220. The thickness difference of the active material layer 2202 in the width direction X of the current collector 2201 is ≤10%. The electrode 220 is then stacked with a separator to form the battery cell 20. During the forming of the electrode 220, complex processes such as slurry mixing and drying are not required to complete the forming of the battery cell 20.

[0096] Therefore, the battery cell 20 provided in one embodiment of this application, by limiting the thickness difference of the active material layer 2202 on the electrode 220 along the width direction X of the current collector 2201 to ≤10%, ensures that there is no thinning area of ​​the active material layer 2202 in the width direction X of the electrode 220. This makes the thickness of the active material layer 2202 at all locations on the current collector 2201 consistent or nearly consistent along the width direction X, thereby maximizing the active material loading per unit area of ​​the electrode 220 and effectively improving the energy density of the battery cell 20 and increasing its range. Furthermore, the structural design of the battery cell 20 with consistent or nearly consistent thickness of the active material layer 2202 at all locations on the current collector 2201 fundamentally avoids lithium plating caused by poor control of the thinning area, reduces safety risks such as battery short circuits and thermal runaway, and improves the reliability of the battery cell 20.

[0097] In some embodiments, the difference in thickness of the active material layer 2202 along the width direction X of the current collector 2201 is less than or equal to 6 μm.

[0098] The difference in thickness is equal to the actual thickness of any region of the active material layer 2202 minus the standard thickness.

[0099] As explained above, the standard thickness can be the thickness of one of the main regions of the active material layer 2202, for example, the thickness of the central region of the electrode 220 along the thickness direction Y, or it can be the average thickness of each region of the active position layer.

[0100] Optionally, the difference in thickness of the active material layer 2202 is less than or equal to 5 μm. In some optional embodiments, the difference in thickness of the active material layer 2202 may be less than or equal to 4 μm, 3 μm, 2 μm or 1 μm. Optionally, the difference in thickness of the active material layer 2202 may be 0.

[0101] The battery cell 20 provided in one embodiment of this application limits the absolute value of the thickness difference in the width direction X of the active material layer 2202 to ≤6μm, which helps to ensure the uniformity of the distribution of active material, avoid the problem of uneven charging and discharging current density caused by local thickness deviation, and ensure the energy density requirement.

[0102] Continue reading Figures 1 to 5 As shown, in some embodiments, the active material layer 2202 includes a main body portion 2202a and an edge portion 2202b distributed along the width direction X of the current collector 2201. In the thickness direction Y, the thickness dimension of the main body portion 2202a is M1, and the thickness dimension of the edge portion 2202b is M2, wherein 90%≤M2 / M1≤110%.

[0103] In some embodiments, the main body portion 2202a may have an edge portion 2202b on one side of the width direction X. Alternatively, the main body portion 2202a may have edge portions 2202b on both sides of the width direction X. When the main body portion 2202a has edge portions 2202b on both sides of the width direction X, the extension dimensions of the two edge portions 2202b in the width direction X may have a difference or be equal.

[0104] In some embodiments, the main body portion 2202a and the edge portion 2202b may be successively provided in the width direction X, and the materials may be the same.

[0105] When there is a difference in thickness between the main body portion 2202a and the edge portion 2202b of the active material layer 2202, the thickness of one of the edge portion 2202b and the main body portion 2202a can be greater than the thickness of the other. In some optional embodiments, the thickness of the main body portion 2202a can be greater than the thickness of the edge portion 2202b.

[0106] In some embodiments, the standard thickness may be the thickness dimension of the main body 2202a.

[0107] When the thickness of all regions of the main body 2202a is equal, the standard thickness can be the thickness of any position of the main body 2202a. When the thickness of some regions of the main body 2202a deviates due to factors such as processing technology, the standard thickness can be the average value of the thickness of all regions of the main body 2202a.

[0108] The thickness dimension M1 of the main body 2202a can be the vertical distance between the two end faces of the main body 2202a in the thickness direction Y. The thickness dimension M2 of the edge portion 2202b can be the vertical distance between the two end faces of the edge portion 2202b in the thickness direction Y.

[0109] Optionally, when the thickness dimensions of all regions of the main body 2202a are equal, M1 can be the thickness dimension at any position of the main body 2202a. When the thickness dimensions of some regions of the main body 2202a deviate, M1 can be the average value of the thickness dimensions of all regions of the main body 2202a.

[0110] Optionally, when the thickness dimensions of all regions of the edge portion 2202b are equal, M2 can be the thickness dimension at any position of the edge portion 2202b. When the thickness dimensions of some regions of the edge portion 2202b deviate, M2 can be the average value of the thickness dimensions of all regions of the edge portion 2202b.

[0111] Optionally, M1 = M2.

[0112] One embodiment of the battery cell 20 provided in this application structurally ensures that the active material loading of the edge portion 2202b is substantially consistent with that of the main body portion 2202a, thereby guaranteeing the energy density of the battery cell 20. On the other hand, a thickness ratio difference of less than 10% can balance the structural stability and electrochemical performance of the active material layer 2202, avoiding problems such as insufficient drying and cold-pressing stress concentration caused by excessive edge thickness. At the same time, it provides a clear zoning standard for thickness detection during the production process, facilitating process control, improving production consistency, reducing the risk of lithium plating in the battery cell 20, and ensuring the reliability of the battery cell 20.

[0113] In some embodiments, the main body 2202a and the edge portion 2202b are integrally formed.

[0114] The main body 2202a and the edge part 2202b can be formed as a continuous whole through the same process. Their materials and compositions can be identical. During molding, the active material powder can be rolled to form an integral active material layer 2202, and then the active material film layer is laminated onto the current collector 2201 to form the electrode 220. Dry rolling and lamination can be used for integrated molding.

[0115] The battery cell 20 provided in one embodiment of this application, through the above-described configuration, ensures the thickness requirements of each region of the active material layer 2202, while eliminating the need for extensive process design and debugging during molding, thus simplifying the process and reducing the precision requirements of the equipment. For the edge portion 2202b, secondary processing steps such as thinning and calibration can be omitted, reducing equipment investment, energy consumption, and maintenance costs, shortening the production cycle, and improving efficiency.

[0116] Meanwhile, the integrated structure can avoid interface defects (such as delamination and cracks) that may occur in segmented molding, improve the structural integrity and mechanical strength of the active material layer 2202, ensure continuous current conduction between the main body 2202a and the edge part 2202b, reduce interface polarization, improve the cycle stability of the battery cell 20, and optimize the electrolyte wetting effect without interface gaps, reduce the risk of local overheating, and take into account structural stability, production efficiency and safety performance.

[0117] In some embodiments, the difference between the thickness dimension M1 of the main body portion 2202a and the thickness dimension M2 of the edge portion 2202b is less than or equal to 6 μm.

[0118] Optionally, the difference between the thickness dimension M1 of the main body portion 2202a and the thickness dimension M2 of the edge portion 2202b is less than or equal to 5 μm. In some optional embodiments, the difference between the thickness dimension M1 of the main body portion 2202a and the thickness dimension M2 of the edge portion 2202b may be less than or equal to 4 μm, 3 μm, 2 μm or 1 μm. Optionally, the difference between M1 and M2 may be 0.

[0119] One embodiment of this application provides a battery cell 20 that, through the above-described configuration, effectively adapts to the design requirements of electrode sheets 220 with different thicknesses. This helps ensure that the thickness of the edge portion 2202b is consistent with the thickness of the main body portion 2202a, reducing the probability of energy density loss or structural defects caused by differences in thickness. Simultaneously, a difference of less than or equal to 6 μm between the thickness dimension M1 of the main body portion 2202a and the thickness dimension M2 of the edge portion 2202b ensures uniform current distribution during charging and discharging, reduces the risk of local overcharging and over-discharging, and suppresses lithium plating. Furthermore, this parameter requires the electrode sheet 220 forming process of the battery cell 20 to provide a more stable thickness base, avoiding problems such as bright edges and stretching deformation caused by excessive thickness deviation between the edge and the main body portion 2202a. This enhances the stability of the manufacturing process and the battery safety performance, achieving synergistic optimization of precision, performance, and process.

[0120] In some embodiments, the edge portion 2202b includes a region of the active material layer 2202 within 10 mm of its own edge in the width direction X. For example, Figure 5 The value of N in the figure is less than or equal to 10 mm.

[0121] The edge can be understood as: the two edges of the active material layer 2202 along the width direction X of the current collector 2201, and the edge portion 2202b is formed by extending a predetermined size from each edge to the main body portion 2202a along the width direction X. The value of the predetermined size extended on each side of the width direction X can be 10mm or less than 10mm, such as 8mm, 5mm, etc.

[0122] The active material layer 2202 has edge portions 2202b on both sides in the width direction X. In the width direction X, the remaining position of the active material layer 2202, excluding the edge portions 2202b, can be the main body portion 2202a.

[0123] One embodiment of the battery cell 20 provided in this application allows for the rational planning of the distribution of the active material layer 2202 in the edge portion 2202b, which includes an area within 10mm of its own edge in the width direction X, thus meeting the requirements of the molding process. Furthermore, after testing, it is found that the thickness of the active material layer 2202 in the 10mm edge region is consistent with or nearly consistent with the thickness of the main body portion 2202a. Compared with related technologies, this effectively increases the active material content in the edge portion 2202b, and can stably achieve an energy density increase of approximately 6% in this region. This gives the battery cell 20 the comprehensive advantages of no thinning, low cost, and high performance.

[0124] like Figures 3 to 7As shown, in some embodiments, the electrode assembly 22 includes a pair of electrode sheets 220, one of which is a cathode electrode sheet 221 and the other is an anode electrode sheet 222. The cathode electrode sheet 221 includes a cathode current collector 2211 and a cathode active material layer 2212 disposed on at least one side of the cathode current collector 2211 in the thickness direction Y. The anode electrode sheet 222 includes an anode current collector 2221 and an anode active material layer 2222 disposed on at least one side of the anode current collector 2221 in the thickness direction Y. In the thickness direction Y, the orthographic projection of the anode active material layer 2222 covers the orthographic projection of the cathode active material layer 2212. The thickness difference between the cathode active material layer 2212 and the anode active material layer 2222 is ≤10%.

[0125] The cathode electrode 221 and anode electrode 222 in the electrode assembly 22 are matched in number and arranged accordingly, and are separated by an isolation element to form an electrochemical reaction unit.

[0126] Optionally, the thickness difference of the anodic active material layer 2222 of the anode electrode 222 is ≤10%.

[0127] Optionally, the thickness difference of the cathode active material layer 2212 of the cathode electrode 221 is ≤10%.

[0128] The thickness direction Y can be the thickness direction of either the anode electrode 222 or the cathode electrode 221.

[0129] The thickness direction Y can be selected to be perpendicular to the width direction X.

[0130] The setting where the orthographic projection of the anode active material layer 2222 covers the orthographic projection of the cathode active material layer 2212 can be understood as follows: when projected along the thickness direction Y, the projected area of ​​the anode active material layer 2222 is larger than the projected area of ​​the cathode active material layer 2212. This ensures that the projection of the anode active material layer 2222 includes the projection area of ​​the cathode active material layer 2212, and the projection of the cathode active material layer 2212 does not exceed the projection of the anode active material layer 2222.

[0131] In one embodiment of this application, a battery cell 20 is provided. Through the above-described configuration, neither the anode electrode 222 nor the cathode electrode 221 requires thinning. The thickness of the corresponding regions of the active material layers 2202 of both electrodes is consistent or nearly consistent. The thickness difference of the cathode active material layer 2212 of the cathode electrode 221 is ≤10%, which effectively increases the active material loading and significantly increases the amount of lithium ions released. The full-coverage design of the anode orthogonal projection and the thickness difference of the anode active material layer 2222 of the anode electrode 222 being ≤10% enable the anode edge 2202b to form a larger effective reaction area, providing sufficient active sites and storage space. This achieves a dynamic balance between the amount of lithium ions released from the cathode and the amount of lithium ions stored in the anode, effectively avoiding lithium plating caused by insufficient anode edge area and excessive lithium ion deposition in related technologies, thus improving the reliability of the battery cell 20.

[0132] Furthermore, both bipolar plates 220 meet the uniformity requirement of thickness difference ≤10%, which can avoid charge and discharge imbalance caused by thickness deviation of a single electrode 220, ensure that the loading of active materials on both electrodes reaches the optimal level, and synergistically enhance the overall energy density of the battery cell 20.

[0133] As an example, the cathode current collector 2211 has two surfaces opposite each other in its own thickness direction Y, and the cathode active material layer 2212 is disposed on either or both of the two opposite surfaces of the cathode current collector 2211.

[0134] As an example, the cathode current collector 2211 may be a metal foil, a conductive polymer material, a carbon material, or a composite current collector 2201. For example, as a metal foil, pure metals, alloys, or surface-treated metals may be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloys, titanium, or silver. The composite current collector 2201 may include a polymer material substrate and a metal layer. The composite current collector 2201 may 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.).

[0135] As an example, the cathode active material layer 2212 includes a cathode active material, which 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 cathode active materials may also be used. These cathode 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 manganese iron phosphate, and lithium manganese iron 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 0.3 O2 (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 0.1 O2 (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.

[0136] As an example, the anode current collector 2221 has two surfaces opposite each other in its own thickness direction Y, and the anode active material layer 2222 is disposed on either or both of the two opposite surfaces of the anode current collector 2221.

[0137] As an example, the anode current collector 2221 may be a metal foil, a conductive polymer material, a carbon material, or a composite current collector 2201. For example, as a metal foil, pure metals, alloys, or surface-treated metals may be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloys, titanium, or silver. The composite current collector 2201 may include a polymer material base layer and a metal layer. The composite current collector 2201 may 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.).

[0138] As an example, anolyte active material may be filled or deposited within the anolyte current collector 2221.

[0139] In some embodiments, the cathode current collector 2211 may be made of aluminum, and the anode current collector 2221 may be made of copper.

[0140] As an example, the anode active material layer 2222 includes an anode active material, which may be an anode active material known in the art for use in battery cells 20. As an example, the anode 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 anode active materials for battery cells 20 may also be used. These anode active materials may be used alone or in combination of two or more.

[0141] In some embodiments, the electrode assembly 22 further includes an isolator disposed between the cathode and the anode.

[0142] In some embodiments, the separator 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.

[0143] 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. When the separator is a multi-layer composite film, the materials of each layer can be the same or different. The separator 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. Inorganic particle coating, organic particle coating, or organic / inorganic composite coating can also be applied to the surface of the separator.

[0144] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the cathode and the anode, serving both to transport ions and to isolate the positive and negative electrodes.

[0145] like Figures 3 to 8 As shown, in some embodiments, in the width direction X, the cathode active material layer 2212 has a first edge 2212a, and the anode active material layer 2222 has a second edge 2222a on the same side as the first edge 2212a and spaced apart from it. The minimum vertical distance from the first edge 2212a to the second edge 2222a is d1, where 0 <d1≤3mm。

[0146] The first edge 2212a and the second edge 2222a are located on the same side of the cathode active material layer 2212 in the width direction X. Along the width direction X, the second edge 2222a and the first edge 2212a can be spaced apart. After the anode electrode 222 and the cathode electrode 221 are stacked together with the separator, the anode active material layer 2222 on the anode electrode 222 completely covers the cathode active material layer 2212 on the cathode electrode 221. The anode active material layer 2222 on the anode electrode 222 will be positioned relative to the cathode electrode 221 in the width direction X. The cathode active material layer 2212 protrudes, making the area of ​​the anode active material layer 2222 on the anode electrode 222 larger than the area of ​​the cathode active material layer 2212 on the cathode electrode 221. This ensures that the anode active material layer 2222 on the anode current collector 2221 completely covers the cathode active layer on the cathode current collector 2211, thereby ensuring that ions deposited from the cathode electrode 221 can be embedded into the anode electrode 222 after passing through the isolation membrane, and ensuring that ions deposited from the cathode electrode 221 will not scatter outside the anode electrode 222.

[0147] The first edge 2212a may be the boundary of the cathode active material layer 2212 in the width direction X, and may optionally include a straight trajectory extension or a non-straight trajectory extension. When it is a non-straight trajectory, the first edge 2212a may include a broken line trajectory extension, a wavy line trajectory extension, or a combination of both. The second edge 2222a may be the boundary of the anode active material layer 2222 in the width direction X, and may optionally include an extension along a straight trajectory.

[0148] The minimum vertical distance d1 between the first edge 2212a and the second edge 2222a can be any value between 0 and 3 mm, including the 3 mm value. In some optional embodiments, the value of d1 can be less than or equal to 2 mm. In some embodiments, the value of d1 can be less than or equal to 1 mm. d1 can be selected as 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, 0.5 mm, 0.4 mm, 0.3 mm, 0.2 mm, or 0.1 mm.

[0149] The battery cell 20 provided in one embodiment of this application, by limiting the size of d1 and combining the advantage of the electrode 220 of the battery cell 20 without thinning, breaks through the control limitations of the d1 size in related technologies. On the one hand, because the electrode 220 has no thinning at the edge and uniform thickness, there is no need to reserve a larger d1 size to avoid the risk of lithium plating and short circuit caused by uneven thinning, so that the d1 size can be minimized to close to 0. Under the premise of ensuring a safe distance, the ineffective space at the edge of the bipolar electrode 220 is reduced, the space utilization rate of the electrode assembly 22 is improved, and the energy density advantage of the battery cell 20 is enhanced.

[0150] like Figure 6 as well as Figure 7 As shown, in some embodiments, the cathode electrode 221 further includes an insulating layer 223. The cathode current collector 2211 includes a first main body region 2211a and a first tab region 2211b distributed along the width direction X. The cathode active material layer 2212 is disposed in the first main body region 2211a. The insulating layer 223 is disposed on the side of the cathode active material layer 2212 facing the first tab region 2211b. The insulating layer 223 partially covers the first main body region 2211a and the first tab region 2211b. The thickness M2 of the edge portion 2202b of the cathode active material layer 2212 is greater than the thickness M3 of the insulating layer 223.

[0151] The first main body region 2211a can be used as the main area to carry the core active material and realize the ion reaction. The first tab region 2211b can be used as the area to form the tab 22b and conduct current. The cathode active material layer 2212 is coated on the first main body region 2211a. The insulating layer 223 can be made of insulating materials such as PP and PE, and can be set by coating or bonding; the insulating layer 223 is located on the side of the cathode active material layer 2212 facing the first tab region 2211b.

[0152] The insulating layer 223 and the cathode active material layer 2212 can be distributed along the width direction X. The first edge 2212a of the cathode active material layer 2212 is disposed toward the insulating layer 223 in the width direction X, and the shape of the side of the insulating layer 223 toward the first edge 2212a of the cathode active material layer 2212 in the width direction X can match the shape of the overlap allowance adjustment part.

[0153] The thickness of the insulating layer 223 can be understood as the vertical distance between the two end faces of the insulating layer 223 along the thickness direction Y of the electrode 220.

[0154] The thickness of the insulating layer 223 can be equal in all regions. In this case, the thickness of the insulating layer 223 can be understood as the thickness of any region of the insulating layer 223. Of course, in some embodiments, when the thickness of the formed insulating layer 223 varies due to factors such as processing technology, the thickness of the insulating layer 223 can be the average thickness of all regions.

[0155] In one embodiment of this application, the battery cell 20, through the above-described configuration, ensures that the thickness M2 of the edge portion 2202b of the electrode 220 is thicker than that of related technologies, thereby guaranteeing that the active material loading of the edge portion 2202b meets the standard and ensuring energy density. Furthermore, the insulating layer 223 prevents metal debris generated during die-cutting of the anode electrode 222 from piercing the separator and contacting the cathode electrode 221, thus preventing short circuits and improving the reliability of the battery cell 20.

[0156] like Figure 6 as well as Figure 7 As shown, in some embodiments, the orthographic projection of the insulating layer 223 onto the plane perpendicular to the thickness direction Y of the cathode current collector 2211 does not coincide with the orthographic projection of the cathode active material layer 2212 onto the plane perpendicular to the thickness direction Y of the cathode current collector 2211.

[0157] The non-overlapping orthographic projection can also be understood as follows: when projecting along the thickness direction Y, the projection area of ​​the insulating layer 223 and the projection area of ​​the cathode active material layer 2212 have no overlap and are staggered.

[0158] The battery cell 20 provided in one embodiment of this application, through the above-described configuration, maximizes the effective reaction area of ​​the active material layer 2202 while ensuring insulation and isolation. On the one hand, it avoids the situation where the active material cannot participate in the electrochemical reaction due to the insulating layer 223 covering the active material layer 2202, ensuring that the active material at the edge 2202b and the main body 2202a of the cathode electrode 221 can fully play its role, thus guaranteeing the energy density requirements of the battery cell 20. On the other hand, the non-projection overlap design avoids excessive local thickness caused by the superposition of the insulating layer 223 and the active material layer 2202, and facilitates the electrolyte to fully wet the edge 2202b of the active material layer 2202, avoiding insufficient local wetting caused by the insulating layer 223 blocking the edge. This optimizes the electrochemical performance and structural stability of the battery, achieving a synergistic improvement in insulation performance and activity efficiency.

[0159] like Figures 3 to 8As shown, a battery cell 20 provided in one embodiment of this application includes a housing 21 and an electrode assembly 22. The housing 21 has a receiving cavity, and the electrode assembly 22 is disposed in the receiving cavity. The electrode assembly 22 includes a cathode electrode 221, an anode electrode 222, and a separator located between the two. The cathode electrode 221 includes a cathode current collector 2211 and a cathode active material layer 2212 disposed on at least one side of the cathode current collector 2211 in the thickness direction Y. The anode electrode 222 includes an anode current collector 2221 and an anode active material layer 2222 disposed on at least one side of the anode current collector 2221 in the thickness direction Y. In the thickness direction Y, the orthographic projection of the anode active material layer 2222 covers the orthographic projection of the cathode active material layer 2212. The thickness difference between the cathode active layer 2212 and the anode active layer 2222 is 0. Both the cathode active material layer 2212 and the anode active material layer 2222 include a main body portion 2202a and an edge portion 2202b. The thickness difference between the main body portion 2202a and the edge portion 2202b of the cathode active material layer 2212 is 0, and the thickness difference between the main body portion 2202a and the edge portion 2202b of the anode active material layer 2222 is also 0. In the width direction X, the cathode active material layer 2212 has a first edge 2212a, and the anode active material layer 2222 has a second edge 2222a that is on the same side as the first edge 2212a and spaced apart from it. The minimum vertical distance between the first edge 2212a and the second edge 2222a is d1, where d1 = 1 mm. The cathode electrode 221 further includes an insulating layer 223. The cathode current collector 2211 includes a first main body region 2211a and a first tab region 2211b distributed along the width direction X. The cathode active material layer 2212 is disposed in the first main body region 2211a. The insulating layer 223 is disposed on the side of the cathode active material layer 2212 facing the first tab region 2211b. The insulating layer 223 partially covers the first main body region 2211a and the first tab region 2211b. The thickness of the edge portion 2202b of the cathode active material layer 2212 is greater than the thickness of the insulating layer 223. The orthographic projection of the insulating layer 223 onto the plane perpendicular to the thickness direction Y of the cathode current collector 2211 does not coincide with the orthographic projection of the cathode active material layer 2212 onto the plane perpendicular to the thickness direction Y of the cathode current collector 2211.

[0160] Secondly, this application provides a battery device 100, including the aforementioned battery cell 20.

[0161] Thirdly, this application provides an electrical device including the aforementioned battery device 100.

[0162] like Figure 9 As shown, and in combination Figures 1 to 8As shown, in a fourth aspect, this application provides a method for manufacturing a battery cell 20, which can be used to form the battery cell 20 provided in the above embodiments, including the following steps: S100. Mix and stir the active material, conductive agent, and binder to form an active substance powder.

[0163] S200: Roll the active material powder to form an active material layer 2202.

[0164] S300. The active material layer 2202 is composited on the current collector 2201 to form an electrode 220. The thickness difference of the active material layer 2202 along the width direction X of the current collector 2201 is ≤10%.

[0165] S400, The electrode 220 and the separator are stacked to form a battery cell 20.

[0166] Steps S100 to S300 can be used to form at least one of the anode electrode 222 and the cathode electrode 221.

[0167] In step S400, the electrode 220 and the separator can be stacked to form the electrode assembly 22 by winding or stacking. The electrode assembly 22 is then installed onto the housing 21 and electrically connected to the electrode terminals 23 to form the battery cell 20.

[0168] The manufacturing method of the battery cell 20 provided in one embodiment of this application eliminates the need for solvents in the preparation of the mixture and omits high-energy-consuming drying equipment. This allows the electrode 220 to be manufactured without complex processes such as slurry stirring and drying. The electrode 220 can be manufactured through three core processes: mixing, rolling, and compounding, which can meet the requirements for uniform thickness of the active material layer 2202. This significantly simplifies the production process, reduces equipment investment, energy consumption and maintenance costs, shortens the production cycle, and improves production efficiency. On the other hand, the manufacturing method can reasonably control the thickness of the active material layer 2202, achieving the requirement that the thickness difference in the width direction X is ≤10%. This avoids the thickness unevenness and bulging problems caused by solvent evaporation and surface tension in related technologies. At the same time, it eliminates the need for secondary processing such as thinning and calibration, avoiding physical damage caused by mechanical thinning. This ensures the structural integrity and performance consistency of the electrode 220, providing process assurance for the high energy density and reliability of the battery cell 20.

[0169] In some embodiments, the step of mixing and stirring the active material, conductive agent, and binder into an active substance powder includes: by controlling the stirring speed and stirring temperature, forming a portion of the binder into bonding fibers, which are used to connect the active material.

[0170] In some optional embodiments, in step S100, the adhesive may include a fibrous first adhesive and a second adhesive. The fibrous first adhesive includes one or more of polytetrafluoroethylene (PTFE), a copolymer of PTFE and perfluorosulfonic acid, and PTFE-modified polymers. The second adhesive includes one or more of polyurethane, polyvinylidene fluoride (PVDF), polyethylene oxide (PEE), polypropylene, paraffin wax, polylactic acid (PLA) and acrylonitrile-butadiene-styrene copolymer, acrylates, carboxymethyl cellulose, and fluorinated acrylates. Exemplarily, the active material for the anode electrode 222, the conductive agent, and the first and second adhesives can be mixed and stirred in dry form to form an active material powder.

[0171] The fiberized first binder of this application embodiment can achieve initial fiberization during the mechanical shearing process to obtain the mixture, and the first binder can form fibers by adjusting the mechanical shearing parameters; during hot pressing, the first binder forms fibers. The hot pressing process can also cause the second binder to become a thin film, thereby improving the adhesive strength of the second binder.

[0172] In some embodiments, the stirring temperature can be selected from 60°C to 120°C, and the stirring speed can be selected from 3000 rpm to 5000 rpm.

[0173] Optionally, the stirring temperature is independently selected from any value of 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or a range between any two.

[0174] Optionally, the stirring speed is independently selected from any value of 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, 5000 rpm, or a range between any two.

[0175] With the above settings, in step S100, the active material layer 2202 is calendered and formed, ensuring the reliability of the formed battery cell 20.

[0176] In some embodiments, the active material layer 2202 can be laminated onto the current collector 2201 by hot pressing to form an electrode 220. The hot pressing temperature is 100°C to 160°C, and the pressure is 10 tons to 50 tons. This ensures the bonding strength between the active material layer 2202 and the current collector 2201.

[0177] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized by, The application relates to a battery cell and a battery device. The battery cell comprises: a housing having a receiving cavity; an electrode assembly arranged in the receiving cavity, the electrode assembly comprising a pair of electrode sheets, one of the pair of electrode sheets being a cathode electrode sheet, and the other being an anode electrode sheet, the cathode electrode sheet comprising a cathode current collector and a cathode active material layer arranged on at least one side of the cathode current collector in a thickness direction, the anode electrode sheet comprising an anode current collector and an anode active material layer arranged on at least one side of the anode current collector in the thickness direction, the anode active material layer covering the cathode active material layer in a planar projection in the thickness direction; 2. The battery cell of claim 1, wherein, a thickness difference of the cathode active material layer and the anode active material layer in a width direction of the cathode current collector and the anode current collector is less than or equal to 10%.

3. The battery cell of claim 1, wherein, a thickness difference of at least one of the cathode active material layer and the anode active material layer in the width direction is less than or equal to 6 microns.

4. The battery cell of claim 3, wherein, at least one of the cathode active material layer and the anode active material layer comprises a main body portion and an edge portion arranged along the width direction, a thickness dimension of the main body portion is M1, and a thickness dimension of the edge portion is M2, wherein 90%<=M2 / M1<=110%.

5. The battery cell of claim 3, wherein, the main body portion and the edge portion are in an integral structure.

6. The battery cell of claim 3, wherein, a thickness difference between the thickness dimension M1 of the main body portion and the thickness dimension M2 of the edge portion is less than or equal to 6 microns.

7. The battery cell of claim 1, wherein, the edge portion comprises a region of at least one of the cathode active material layer and the anode active material layer within a range of 10 mm from an edge of itself in the width direction.

8. The battery cell of claim 1, wherein, in the width direction, the cathode active material layer has a first edge, and the anode active material layer has a second edge arranged on the same side as the first edge and spaced apart from the first edge, and a minimum vertical distance between the first edge and the second edge is d1, wherein 0 9. The battery cell of claim 8, wherein, the cathode electrode sheet further comprises an insulating layer, the cathode current collector comprises a first main body region and a first tab region arranged along the width direction, the cathode active material layer is arranged in the first main body region, the insulating layer is arranged on a side of the cathode active material layer facing the first tab region, the insulating layer partially covers the first main body region and the first tab region, and a thickness of the edge portion of the cathode active material layer is greater than a thickness of the insulating layer.

10. A battery device characterized by comprising: in a plane perpendicular to the thickness direction of the cathode current collector, a planar projection of the insulating layer does not overlap a planar projection of the cathode active material layer.

11. An electrical device, characterized by The application further relates to a battery device comprising the battery cell.

12. A method for manufacturing a battery cell, characterized by, The application further relates to a battery device comprising the battery cell. The application further relates to a battery device comprising the battery cell. The application further relates to a battery device comprising the battery cell. The application further relates to a battery device comprising the battery cell. The application further relates to a battery device comprising the battery cell. The application further relates to a battery device comprising the battery cell. The application further relates to a battery device comprising the battery cell. The application further relates to a battery device comprising the battery cell. The application further relates to a battery device comprising the battery cell. The application further relates to a battery device comprising the battery cell. The application further relates to a battery device comprising the battery cell. 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The application further relates to a battery device comprising the battery cell. The application further relates to a battery device comprising the battery cell. The application further relates to 13. The method of manufacturing a battery cell according to claim 12, wherein The step of mixing and stirring the active material, the conductive agent, and the binder to form the active material powder includes forming a portion of the binder into binder fibers for connecting the active material by controlling a stirring speed and a stirring temperature.

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