Battery cell, battery device, and electric device

Abstract

The present application discloses a battery cell, a battery device, and an electric device. The battery cell comprises an electrode sheet, and the electrode sheet comprises a current collector and a tab connected to the current collector; and the melting point of the tab is 600°C-1500°C, the plastic deformation of the tab is greater than or equal to 60%, and the plastic deformation of the tab is greater than the plastic deformation of the current collector. The battery cell provided in the present application has improved cycle performance.

Description

Battery cells, battery packs and electrical devices

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application 202510115558.2, filed on January 24, 2025, entitled “Battery cell, battery device and power consumption device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, specifically to a battery cell, a battery device, and an electrical device. Background Technology

[0004] Batteries are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric car toys, electric toy ships, electric toy airplanes, and power tools.

[0005] In the development of battery cells, improving the cycle performance of battery cells is one of the urgent problems to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a battery cell, a battery device, and an electrical device.

[0007] In a first aspect, embodiments of this application provide a battery cell, the battery cell including an electrode sheet, the electrode sheet including a current collector and a tab connected to the current collector; the melting point of the tab is 600℃-1500℃, the plastic deformation of the tab is greater than or equal to 60%, and the plastic deformation of the tab is greater than the plastic deformation of the current collector.

[0008] According to the embodiments of this application, the current collector is made of a material with low plastic deformation, which is beneficial for meeting the design requirements of a high-expansion negative electrode system and reducing the risk of electrode cracking. Simultaneously, the plastic deformation of the tab is higher than that of the current collector, and the melting point of the tab is lower than that of the current collector, thus defining the specific range of the tab's plastic deformation and melting point. The low melting point helps reduce die-cutting power and allows for deformation during welding to ensure a stable connection with the adapter plate, reducing weld beads and the risk of incomplete welds. The high plastic deformation facilitates rapid fusion between the tab and the adapter plate during welding, improving welding reliability and machinability, increasing the strength of the welded area, reducing the risk of weld breakage or detachment, and improving the cycle performance of the battery cell. Therefore, by combining a high-strength current collector with a high-plastic-deformation, low-melting-point tab structure, the electrode in a high-energy-density battery cell can have better machinability, while the battery cell can also have improved cycle performance.

[0009] In some embodiments, the plastic deformation of the tab is 75%-95%.

[0010] In some embodiments, the melting point of the tab is 800°C-1100°C.

[0011] In some embodiments, the plastic deformation of the current collector is 15%-70%, optionally 30%-65%, and further optionally 40%-60%.

[0012] In some embodiments, the tensile strength of the tab is 300MPa-1000MPa, optionally 320MPa-500MPa.

[0013] In some embodiments, the elongation of the electrode tab is 3.0%-8.5%.

[0014] In some embodiments, the elastic modulus of the tab is 5 GPa-45 GPa, and optionally 6 GPa-20 GPa.

[0015] In some embodiments, the thermal conductivity of the tab is 80 W / (m·K)-500 W / (m·K), optionally 100 W / (m·K)-450 W / (m·K).

[0016] In some embodiments, the thickness of the tab is 4μm-10μm.

[0017] In some embodiments, the material of the tab includes one or more of Cu, Ag, Au, Sn, and Ni.

[0018] In some embodiments, the tensile strength of the current collector is 400MPa-1500MPa, and optionally 600MPa-1200MPa.

[0019] In some embodiments, the elongation of the current collector is 1.5%-6%, optionally 2.0%-5%.

[0020] In some embodiments, the elastic modulus of the current collector is 30 GPa-75 GPa, and optionally 40 GPa-70 GPa.

[0021] In some embodiments, the thermal conductivity of the current collector is 5 W / (m·K)-150 W / (m·K), optionally 6 W / (m·K)-120 W / (m·K).

[0022] In some embodiments, the thickness of the current collector is 2 μm-10 μm.

[0023] In some embodiments, the material of the current collector includes one or more of Ti, Ti alloys, Ni, and Ni alloys.

[0024] In some embodiments, the current collector includes a coated area with active material and an empty foil area without active material, and the tab is connected to the empty foil area.

[0025] In some embodiments, the peel strength between the tab and the empty foil area is greater than or equal to 4 N / mm.

[0026] In some embodiments, the width of the connection area between the tab and the empty foil area is 2.5mm-5mm.

[0027] In some embodiments, the distance between the connection area of ​​the tab and the empty foil area and the coating area is 0.1mm-1mm.

[0028] In some embodiments, the current collector further includes an insulating layer covering the connection area, wherein the connection area does not extend beyond the edge of the insulating layer.

[0029] In some embodiments, the insulating layer is made of one or more of polyolefins, polyesters, polyamides, and polyurethanes.

[0030] In some embodiments, along the width direction of the tab, the size of the tab is L1, the size of the current collector is L2, and 0.4≤L1 / L2≤0.95.

[0031] In some embodiments, 0.4 ≤ L1 / L2 ≤ 0.475.

[0032] In some embodiments, the electrode plates include one or both of positive and negative electrode plates.

[0033] In some embodiments, the electrode sheet is a negative electrode sheet, which includes a negative electrode film layer located on at least one side of the current collector, and the negative electrode film layer includes a negative electrode active material.

[0034] In some embodiments, the negative electrode active material includes one or more of Li, Sn, Zn, carbon-based materials, and silicon-based materials.

[0035] In some embodiments, silicon-based materials include silicon-carbon composite materials.

[0036] Secondly, embodiments of this application provide a battery device, including a single battery cell from the first aspect of this application.

[0037] Thirdly, embodiments of this application provide an electrical device, including a battery cell from the first aspect of this application or a battery device from the second aspect of this application. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0039] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0040] Figure 2 is a schematic diagram of the explosion of a battery provided in some embodiments of this application.

[0041] Figure 3 is an exploded view of the battery module shown in Figure 2.

[0042] Figure 4 is a tensile deformation curve of the current collector in some embodiments of this application.

[0043] The accompanying drawings are not necessarily drawn to scale.

[0044] The reference numerals in the attached drawings are explained as follows: 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 5a. First housing section; 5b. Second housing section; 5c. Reception space; 6. Battery module; 7. Battery cell. Detailed Implementation

[0045] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the battery cell, battery device, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0046] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0047] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0048] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0049] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0050] Unless otherwise specified, in this application, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0051] In this application, the terms "multiple" or "various" refer to two or more kinds.

[0052] In the description of the embodiments of this application, unless otherwise specified, "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," "over," and "on top" 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.

[0053] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0054] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this application. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0055] The battery device mentioned in the embodiments of this application can be a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application can include battery cells, battery modules, or battery packs.

[0056] A single battery cell is the smallest unit that makes up a battery, and it can independently perform the functions of charging and discharging. When there are multiple battery cells, they are connected in series, parallel, or mixed connections through a busbar.

[0057] In some embodiments, the battery device may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0058] In some embodiments, the battery device may be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0059] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0060] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0061] The technical solutions described in the embodiments of this application are applicable to battery devices and electrical devices that use battery devices.

[0062] Battery devices can be used as the power source for electrical devices or as energy storage units for electrical devices. Electrical devices can be, but are not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0063] Electrical devices can choose the type of battery device according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0064] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0065] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0066] As shown in Figure 1, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0067] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0068] In some embodiments, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0069] Figure 2 is an exploded view of a battery provided in some embodiments of this application. As shown in Figure 2, the battery device 2 includes a housing 5 and a battery cell (not shown), with the battery cell housed within the housing 5.

[0070] The housing 5 is used to house individual battery cells, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a housing space 5c for housing the individual battery cells. The second housing portion 5b may be a hollow structure with one end open, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, with the open side of the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as cylinders, cuboids, etc.

[0071] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

[0072] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be called the upper box cover, and the second box section 5b can also be called the lower box.

[0073] In battery device 2, there can be one or more battery cells. If there are multiple battery cells, they can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells are connected in both series and parallel configurations. Multiple battery cells can be directly connected in series, in parallel, or in a mixed configuration, and then the whole assembly of multiple battery cells is housed in housing 5. Alternatively, multiple battery cells can first be connected in series, in parallel, or in a mixed configuration to form battery module 6, and then multiple battery modules 6 can be connected in series, in parallel, or in a mixed configuration to form a whole assembly, which is then housed in housing 5.

[0074] Figure 3 is an exploded view of the battery module shown in Figure 2.

[0075] As shown in Figure 3, in some embodiments, there are multiple battery cells 7, which are first connected in series, parallel, or mixed to form a battery module 6. The multiple battery modules 6 are then connected in series, parallel, or mixed to form a whole and housed in a casing.

[0076] Multiple battery cells 7 in battery module 6 can be electrically connected through a busbar component to achieve parallel, series, or mixed connection of multiple battery cells 7 in battery module 6.

[0077] The battery cells provided in this application embodiment may include at least one of lithium-ion battery cells and sodium-ion battery cells.

[0078] The battery cell includes an electrode assembly. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited in this regard.

[0079] Electrode assemblies generally include electrode plates and separators. Electrode plates include positive electrode plates and negative electrode plates.

[0080] The demand for high-energy-density battery cells is increasing. Methods to improve the energy density of battery cells include increasing the specific capacity of the active material. High-specific-capacity active materials, especially anode materials, are usually accompanied by significant expansion. This expansion subjectes the current collector to considerable tensile forces, which can lead to electrode cracking or even breakage, affecting the cycle performance of the battery cell. High-strength current collectors have high structural stability and can reduce the risk of electrode cracking due to active material layer expansion. However, high-strength current collectors have high hardness and high melting point, requiring higher temperatures and power during die-cutting. Furthermore, they are difficult to eutecticly fuse with the adapter plate, making welding challenging and prone to incomplete welds, thus affecting the processability and cycle performance of the battery cell.

[0081] Therefore, embodiments of this application provide a battery cell, which includes electrode sheets, each electrode sheet including a current collector and a tab connected to the current collector; the tab has a melting point of 600℃-1500℃, a plastic deformation of ≥60%, and the plastic deformation of the tab is greater than that of the current collector. By adjusting the structure of the electrode sheets and selecting different types of current collector and tab combinations, embodiments of this application can improve the cycle performance and processing performance of the battery cell.

[0082] The electrode includes a current collector and a tab connected to the current collector. The plastic deformation of the tab is greater than that of the current collector, and the plastic deformation of the tab can be greater than or equal to 60%, for example, it can be 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, or any range of the above values, and can be selected as 75%-95%.

[0083] The melting point of the tab can be 600℃-1500℃, for example, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1450℃, 1500℃, or any combination of the above values. It can be selected as 700℃-1200℃, or 800℃-1100℃.

[0084] In this application, the plastic deformation of the tab and current collector refers to the proportion of tensile strain with a tangent modulus less than 30 GPa to the total tensile strain in the tensile deformation curve. As shown in Figure 4, in the tensile deformation curve, the plastic deformation is the ratio of strain with a tangent modulus less than 30 GPa to the total tensile strain. The tensile deformation curves of the tab and current collector can be determined using methods known in the art, such as performing a static tensile test using a tensile testing machine to obtain the tangent modulus-strain curve from the stress-strain curve by differentiating the stress-strain curve.

[0085] In this application, the melting point of the electrode has a meaning known in the art and can be determined using methods and instruments known in the art. For example, it can be determined by the following method: Take a test sample of the electrode or current collector, grind the test sample into a fine powder, and place it in a capillary tube (the height can be 2-3 mm). Heat it using a device with a heating stage and a thermometer. Fix the capillary tube on the heating stage so that the temperature sensing part of the thermometer is at the same height as the sample in the capillary tube. Heat at a relatively slow rate (the heating rate can be 1 / 2 ohm, and the heating rate can be the same as the thermometer device). Observe the changes in the state of the sample. When the sample begins to show obvious signs of melting, record the temperature at this time, which is the initial melting temperature of the metal; when the sample is completely melted into a transparent liquid, record the temperature at this time, which is the total melting temperature. Take the average of the initial melting temperature and the total melting temperature as the melting point of the metal.

[0086] According to the embodiments of this application, a structural design employing a current collector and an external tab allows the plastic deformation of the tab to be higher than that of the current collector, while the melting point of the tab is lower than that of the current collector. The specific ranges of the plastic deformation and melting point of the tab are defined. The low melting point helps reduce die-cutting power and allows for deformation during welding, ensuring a stable connection with the adapter plate, reducing weld beads, and lowering the risk of incomplete welds. The high plastic deformation facilitates rapid fusion between the tab and the adapter plate during welding, improving welding reliability and processability, increasing the strength of the welded area, reducing the risk of weld breakage or detachment, and improving the cycle performance of the battery cell. Therefore, by combining a high-strength current collector with a high-plastic-deformation, low-melting-point tab structural design, the electrode in a high-energy-density battery cell can have better processability, while the battery cell can also have improved cycle performance.

[0087] In some embodiments, the tensile strength of the electrode tab can be 300MPa-1000MPa. Optionally, it can be 320-500MPa. For example, it can be 300MPa, 320MPa, 350MPa, 400MPa, 450MPa, 500MPa, 520MPa, 550MPa, 600MPa, 650MPa, 700MPa, 750MPa, 800MPa, 850MPa, 900MPa, 950MPa, 1000MPa, or any range of the above values.

[0088] By controlling the tensile strength of the tab within the aforementioned range, it is beneficial for the tab to be ultrasonically welded to the adapter plate, which can reduce the risk of incomplete welding. Simultaneously, the tab can possess high mechanical strength. According to the embodiments of this application, a high-strength current collector can reduce the volume expansion of the electrode plate under full charge conditions, reducing the risk of electrode plate cracking. However, a high-strength current collector is not conducive to ultrasonic welding with the adapter plate, easily leading to incomplete welding and desoldering risks. The embodiments of this application employ a lower-strength external tab design, which improves the welding effect with the adapter plate.

[0089] In some embodiments, the elastic modulus of the tab can be 5 GPa-45 GPa, for example, it can be 5 GPa, 6 GPa, 7 GPa, 8 GPa, 9 GPa, 10 GPa, 11 GPa, 12 GPa, 13 GPa, 14 GPa, 15 GPa, 16 GPa, 17 GPa, 18 GPa, 19 GPa, 20 GPa, 21 GPa, 22 GPa, 23 GPa, 24 GPa, 25 GPa, 26 GPa, 27 GPa, 28 GPa, 29 GPa, 30 GPa, 31 GPa, 32 GPa, 33 GPa, 34 GPa, 35 GPa, 36 GPa, 37 GPa, 38 GPa, 39 GPa, 40 GPa, 41 GPa, 42 GPa, 43 GPa, 44 GPa, 45 GPa, or any range of the above values. Optionally, it can be 6 GPa-20 GPa. Further options include 8GPa-18GPa.

[0090] In some embodiments, the elongation of the tab can be 3%-8.5%, for example, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, or any range of the above values, and can be selected as 3.5%-7%.

[0091] According to the embodiments of this application, controlling the elongation of the electrode tab within the above-mentioned range is beneficial to further improve the welding effect with the adapter piece.

[0092] In some embodiments, the thermal conductivity of the electrode is 80 W / (m·K)-500 W / (m·K), optionally 80 W / (m·K), 100 W / (m·K), 120 W / (m·K), 140 W / (m·K), 160 W / (m·K), 180 W / (m·K), 200 W / (m·K), 250 W / (m·K), 300 W / (m·K), 350 W / (m·K), 400 W / (m·K), 450 W / (m·K), 500 W / (m·K), or any range of the above values. Optionally, it is 100 W / (m·K)-450 W / (m·K), or optionally 250 W / (m·K)-450 W / (m·K).

[0093] According to the embodiments of this application, limiting the thermal conductivity of the electrode tab to the above range is beneficial for welding the electrode tab and the adapter piece, improving welding strength and reducing the risk of incomplete welding.

[0094] In some embodiments, the thickness of the tab can be 4μm-10μm, for example, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, or any range of the above values.

[0095] In some embodiments, the material of the tab may include one or more of Cu, Ag, Au, Sn, and Ni.

[0096] In some embodiments, the plastic deformation of the current collector can be 15%-70%, for example, it can be 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or any range of the above values, and can be selected as 30%-65%, and more preferably 40%-60%.

[0097] According to the embodiments of this application, the plastic deformation of the current collector is limited to the above range, which can have high mechanical strength. In high-energy-density battery cells, it can suppress the expansion of the low-activity material layer, reduce the risk of current collector breakage caused by expansion, and improve the cycle performance and reliability of the battery cell.

[0098] In some embodiments, the tensile strength of the current collector can be 400MPa-1500MPa, optionally 600MPa-1200MPa, for example, 400MPa, 500MPa, 600MPa, 700MPa, 800MPa, 900MPa, 1000MPa, 1100MPa, 1200MPa, 1300MPa, 1400MPa, 1500MPa, or any range of the above values.

[0099] According to the embodiments of this application, the current collector has relatively low plastic deformation and high tensile strength, and has good mechanical properties. Even if the active material layer undergoes a large volume change under full charge, the electrode is not prone to cracking and wrinkling, which is beneficial to improving the cycle life of the battery cell.

[0100] In some embodiments, the elongation of the current collector can be 1.5%-6%, for example, it can be 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, or any range of the above values, and can be selected as 2.0%-5%.

[0101] According to the embodiments of this application, the elongation of the current collector is within the above range, and the current collector has high structural stability. During the charge and discharge cycle of the battery cell, the volume change of the current collector can be reduced, thereby reducing the reliability risk caused by electrode cracking and improving the cycle performance of the battery cell.

[0102] In some embodiments, the elastic modulus of the current collector can be 30 GPa-75 GPa, optionally 40 GPa-70 GPa, for example, 30 GPa, 35 GPa, 40 GPa, 45 GPa, 50 GPa, 55 GPa, 60 GPa, 65 GPa, 70 GPa, or any range of the above values, optionally 45 GPa-65 GPa.

[0103] According to the embodiments of this application, the elastic modulus of the current collector is limited to the above range. The current collector has a lower elastic deformation, which is beneficial to reduce the expansion of the electrode and improve the cycle performance of the battery cell.

[0104] In some embodiments, the thermal conductivity of the current collector can be 5 W / (m·K)-150 W / (m·K). For example, it can be 5W / (m·K), 6W / (m·K), 7W / (m·K), 8W / (m·K), 9W / (m·K), 10W / (m·K), 20W / (m·K), 30W / (m·K), 40W / (m·K), 50W / (m·K), 60W / (m·K), 70W / (m·K), 80W / (m·K), 90W / (m·K), 100W / (m·K), 110W / (m·K), 120W / (m·K), 130W / (m·K), 140W / (m·K), 150W / (m·K), or any range of the above values, optionally 6W / (m·K)-120W / (m·K), and further optionally 15W / (m·K)-85W / (m·K).

[0105] In some embodiments, the current collector and thickness can be 2μm-10μm, for example, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, or any range of the above values.

[0106] In some embodiments, the material of the current collector may include one or more of Ti, Ti-Ni alloy, Ti-Cu alloy, Ti-Mo alloy, Ni, and Ni alloy.

[0107] As an example, Ti alloys may include one or more of Ti-Ni alloys, Ti-Cu alloys, and Ti-Mo alloys; Ni alloys may include one or more of Ni-Fe alloys, Ni-Cu alloys, Ni-Cr alloys, Ni-Mo alloys, and Ni-W alloys.

[0108] In this application, the elastic modulus of the current collector and the tab are both known in the art and can be determined using known methods and instruments. For example, a static tensile test can be performed using a tensile testing machine to measure the elongation of the test sample under different loads, and the elastic modulus can be calculated based on the stress-strain curve. During the tensile test, the tensile rate can be 50 mm / min.

[0109] In this application, the tensile strength of the current collector and the tab has a meaning known in the art and can be measured using methods and instruments known in the art. For example, the tensile strength can be tested at room temperature (25°C) with reference to GB / T 228.1-2010. During the tensile test, the tensile rate can be 50 mm / min.

[0110] In this application, the elongation of the current collector and the tab has a meaning known in the art and can be measured using methods and instruments known in the art. For example, a tensile testing machine can be used. The extensometer is mounted on the tensile testing machine, the current collector sample or the tab sample is mounted in the fixture, the initial position of the extensometer is calibrated, and then the tensile testing machine is run to break the test sample, and the elongation of the sample is read. During the tensile test, the tensile rate can be 50 mm / min.

[0111] In this application, the thermal conductivity of the tabs and current collectors are both well-known in the art and can be measured using methods and instruments known in the art. For example, the thermal conductivity can be calculated by measuring the heat flow of the sample under a known temperature difference. By setting heat flow meters and temperature sensors on both sides of the sample, the heat flow through the sample and the temperature difference on both sides of the sample can be measured, and the thermal conductivity can be calculated according to the law of thermal conduction.

[0112] In this application, the thickness of the current collector and the tab can be measured and analyzed using SEM (scanning electron microscope) of the electrode cross-section, or by using a laser thickness gauge. This application allows for microscopic morphology observation of the electrode cross-section, enabling the observation of the interface between the current collector and the active material layer, thereby determining the thickness of each layer. In this application, the electrode cross-section refers to the cross-section formed by slicing along the electrode thickness direction. Microscopic morphology observation of the electrode cross-section, combined with compositional analysis such as energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), can determine the elemental composition of each layer of the positive electrode. Furthermore, instruments such as focused electron beam (FIB) microscopes (e.g., FEI Scios 2HiVa equipment) and ion cross-section polishers (e.g., JEOL's IB-09010CP argon ion cross-section polisher) can be used to polish the cross-section to obtain a clear cross-section.

[0113] In some embodiments, along the width direction of the tab, the size of the tab is L1, the size of the current collector is L2, and 0.4≤L1 / L2≤0.95, for example, it can be 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.9, or any range of the above values; optionally, 0.4≤L1 / L2≤0.475.

[0114] In this application, the size of the tab in the tab width direction refers to the size of the bottom edge of the tab on the side of the connection area closer to the coating area. The size of the current collector in the tab width direction refers to: if the electrode assembly is a stacked structure, then it is the actual size of the current collector in this direction; if the electrode assembly is a wound structure, then it is the size of the straight area in this direction after excluding the wound corner area.

[0115] According to the embodiments of this application, by limiting the size of the tab and the current collector within the above-mentioned range, the tab can have better current carrying capacity, further reduce the temperature rise of the tab, and improve the cycle performance of the battery cell.

[0116] In some embodiments, if the electrode assembly has a stacked structure, the number of tabs can be the same as the number of electrode plates; if the electrode assembly has a wound structure, the number of tabs can be greater than 0.5 times the number of electrode plates. This ensures that at least one tab is provided on each layer / turn of electrode plate to improve current carrying capacity.

[0117] In some embodiments, the current collector includes a coated area with active material and an empty foil area without active material, and the tab is connected to the empty foil area.

[0118] In some embodiments, the width of the empty foil area can be 2mm-5mm, for example, 2mm, 3mm, 4mm, 5mm, or any range of the above values.

[0119] In this application, the width of the empty foil area refers to the distance from the edge of the coating area to the edge of the current collector. When the width of the empty foil area is narrow, the area of ​​the welding area is small, which is prone to poor welding and leads to unstable electrode welding. When the width of the empty foil area is wide, the proportion of active material is low, and the energy density of the battery cell decreases.

[0120] In some embodiments, the peel strength between the tab and the empty foil area can be greater than or equal to 4 N / mm.

[0121] According to the embodiments of this application, the low glass strength at the welding position between the tab and the empty foil area leads to weak connection stability between the tab and the current collector, making the tab prone to detachment during battery cell assembly; simultaneously, the tab's overcurrent capacity deteriorates, affecting the rate performance of the battery cell. In this application, the tab and the empty foil area can be connected by welding.

[0122] In some embodiments, the width of the connection area between the tab and the empty foil area can be 2.5mm-5mm, for example, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, 5.0mm, or any range of the above values.

[0123] According to the embodiments of this application, when the width of the connection area formed by welding the tab and the empty foil area is too wide, it will waste the space of the tab and reduce the volumetric energy density of the battery cell; when the width of the connection area is too narrow, the welding stability of the tab will decrease, the welding failure rate will increase, the overcurrent capacity will be weakened, and the reliability and rate performance of the battery cell will be affected.

[0124] In some embodiments, there is a gap between the connection area of ​​the tab and the empty foil area and the coating area. The width of the gap can be 0.1mm-1mm, for example, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.63mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, or any range of the above values.

[0125] According to the embodiments of this application, setting a gap between the connection area of ​​the tab and the empty foil area and the coating area can reduce the welding area from intruding into the active material layer, which would lead to poor welding. However, if the gap is too large, it will waste a certain amount of height space, which will reduce the energy density of the battery cell.

[0126] In some embodiments, the current collector further includes an insulating layer covering the connection area, wherein the connection area does not extend beyond the edge of the insulating layer.

[0127] According to an embodiment of this application, by providing an insulating layer in the connection area, the risk of weld slag generated during electrode welding falling into the coating area of ​​the current collector and puncturing the separator can be reduced.

[0128] In some embodiments, the edge of the insulating layer may extend beyond the edge of the solder area, thereby providing a higher level of protection.

[0129] As an example, the edge of the insulation layer can extend beyond the edge of the solder area by more than 0.25 mm, and can be selected as 0.25 mm to 1 mm, thereby providing better protection.

[0130] In some embodiments, the insulating layer may include an insulating adhesive, which may include one or more of polyolefins, polyesters, polyamides, and polyurethanes.

[0131] An insulating layer is formed by applying insulating adhesive to the connection area. The insulating adhesive can be applied continuously or applied topically. The insulating adhesive can be a type of commonly used insulating adhesive in the art, and this application does not limit this.

[0132] In some embodiments, the electrode sheet can be a positive electrode sheet.

[0133] [Positive electrode plate]

[0134] In some embodiments, the positive electrode includes a current collector and a positive electrode film layer located on at least one side of the current collector, the positive electrode film layer being located in the coating area of ​​the current collector, and the positive electrode film layer including a positive electrode active material.

[0135] As an example, the current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the current collector.

[0136] In some embodiments, the positive electrode active material may include one or more of lithium phosphate, layered lithium transition metal oxide, Prussian blue compounds, polyanionic compounds, and sodium transition metal oxide.

[0137] If the positive electrode active material is one or more of lithium phosphate and layered lithium transition metal oxide, then the positive electrode active material can be used in lithium-ion battery cells; if the positive electrode active material is one or more of Prussian blue compounds, polyanionic compounds, and sodium transition metal oxide, then the positive electrode material can be used in sodium-ion battery cells.

[0138] Lithium-containing phosphates may include one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and their respective modified compounds.

[0139] Examples of layered lithium-containing transition metal oxides may include one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds.

[0140] In some embodiments, the layered lithium-containing transition metal oxide may include Ni. The molar amount of Ni may account for more than 70% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide; optionally, the molar amount of Ni may account for more than 80% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide; more preferably, the molar amount of Ni may account for more than 90% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide.

[0141] The higher the Ni content in layered lithium-containing transition metal oxides, the higher the energy density of the battery cell.

[0142] In some embodiments, layered lithium-containing transition metal oxides may include Li a Ni b Co c M d O e A f Wherein, 0 < a ≤ 1.2; 0.8 ≤ b < 1; 0 < c < 1; 0 < d < 1; b + c + d = 1; 1 ≤ e ≤ 2; 0 ≤ f ≤ 1; M includes, but is not limited to, one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B; A includes, but is not limited to, one or more of N, F, S, and Cl. This can further improve the energy density of individual battery cells.

[0143] In some embodiments, as an example, layered lithium-containing transition metal oxides may include, but are not limited to, LiNi. 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.9 Co 0.06 Mn 0.04 O2, LiNi 0.92 Co 0.06 Mn 0.02 O2, LiNi 0.96 Co 0.02 Mn 0.02 O2, LiNi 0.96 Co 0.02 Mn 0.02 O2N 0.02 One or more of them.

[0144] During the charging and discharging process of a battery cell, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this application, the molar Li content refers to the initial state of the material, i.e., the state before feeding. After charge-discharge cycles, the molar Li content may change when the positive electrode active material is applied to the battery cell.

[0145] In some embodiments, as an example, sodium transition metal oxides may include, but are not limited to:

[0146] Na 1-x Cu h Fe k Mn l M 1 m O 2-y M 1 It is one or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn, and Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0147] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2, where M 2 It is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn and Ba, 0 <z≤0.1;

[0148] Na a Li b Ni c Mn d Fe e O2, of which 0.67 <a≤1,0<b<0.2,0<c<0.3,0.67<d+e<0.8,b+c+d+e=1。

[0149] In some embodiments, as an example, the polyanionic compound may include, but is not limited to:

[0150] A 1 f M 3 g (PO4) i O j X 1 3-j, where A is one or more of H, Li, Na, K, and NH4, M 3 is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, and Zn, X 1 is one or more of F, Cl, and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0151] Na n M 4 PO4X 2 , where M 4 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, X 2 is one or more of F, Cl, and Br, 0 < n ≤ 2;

[0152] Na p M 5 q (SO4)3, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0153] Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, ½, 1, 1.5, 2, or 3.

[0154] In some embodiments, by way of example, Prussian blue compounds may include, but are not limited to:

[0155] A— u M— 6 v [M— 7 (CN)6]— w ·xH₂O, where A is H— + 、NH4— + 、an alkali metal cation, and an alkaline earth metal cation, M— and M—[[ID=%]] 7 are each independently one or more of transition metal cations, 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A is H— + 、Li— + 、Na— + 、K— + 、NH4— + 、Rb— + 、Cs— + 、Fr— + 、Be— 2+ 、Mg— 2+ 、Ca—<q 2+ 、Sr Note: There seems to be an error in the original text where the closing tag for is incorrect as [[ID=%]] instead of . Also, the closing tag for seems to be incorrect as <q 2+ instead of 2+ . I've translated it as accurately as possible with these issues in mind.2+ Ba 2+ and Ra 2+ One or more of them, M 6 and M 7 Each is an independently selected cation of one or more transition metal elements chosen from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, and W. Optionally, A is Li. + Na + and K + One or more of them, M 6 It is a cation of one or more transition metal elements selected from Mn, Fe, Co, Ni, and Cu, M 7 It is a cation of one or more transition metal elements selected from Mn, Fe, Co, Ni and Cu.

[0156] In the examples of positive electrode active materials in this application, the molar content of O is only a theoretical value. Oxygen release from the crystal lattice will cause the molar content of O to change, and the actual molar content of O will fluctuate.

[0157] The modified compounds for the above-mentioned positive electrode active materials can be obtained by doping and / or surface coating of the positive electrode active materials.

[0158] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0159] In some implementations, the weight percentage of the binder in the positive electrode film layer is greater than or equal to 0.5%, which is beneficial for obtaining good adhesion performance.

[0160] In some embodiments, the positive electrode film layer further includes a conductive agent. As an example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0161] In some embodiments, when used as the positive electrode, the current collector may also be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be made by forming a metal material, such as aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, on the polymer material substrate. The polymer material substrate may include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and other substrates.

[0162] In some embodiments, when the electrode is a positive electrode, the thickness of the current collector can be from 4 μm to 20 μm. It can be optionally from 6 μm to 18 μm, and more preferably from 8 μm to 16 μm.

[0163] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto a current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0164] In some embodiments, the electrode sheet can be a negative electrode sheet.

[0165] [Negative electrode plate]

[0166] The negative electrode includes a current collector and a negative electrode film layer located on at least one side of the current collector. The negative electrode film layer is located in the coating area of ​​the current collector and includes a negative electrode active material.

[0167] As an example, the current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the current collector.

[0168] As an example, the negative electrode active material may include one or more of Li, Sn, Zn, carbon-based materials, and silicon-based materials. Silicon-based materials may include silicon-carbon composite materials.

[0169] Carbon-based materials may include one or more of the following: artificial graphite, natural graphite, mesophase microcarbon spheres, hard carbon, and soft carbon.

[0170] Silicon-based composite materials can be prepared by methods known in the art. For example, they can be prepared by vapor deposition using graphite and silicon materials as raw materials.

[0171] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0172] In some embodiments, the negative electrode film layer may also include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc.

[0173] In some embodiments, when used as the negative electrode, the current collector may also be a metal foil or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, aluminum foil, and aluminum alloy foil. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one side of the polymeric material substrate. Examples of metal materials include, but are not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymeric material substrates include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0174] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet may also include a conductive undercoat layer sandwiched between the negative electrode current collector and the negative electrode film layer and located on the surface of the negative electrode current collector, which may be composed of a conductive agent and a binder; in some embodiments, the negative electrode sheet may also include a protective layer covering the surface of the negative electrode film layer.

[0175] [Electrolytes]

[0176] A single battery cell includes an electrolyte.

[0177] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0178] In some embodiments, the electrolyte includes anion, which may include bis(fluorosulfonyl)imide anion (FSI). - ), bis(trifluoromethanesulfonyl)imide anion (TFSI) - ), dioxaborate anion (BOB) - ), difluorooxalate borate anion (DFOB) - ), difluorodioxanol phosphate anion (DFOP) - ), tetrafluorooxalate phosphate anion (TFOP) - ), difluorophosphate anion (PO2F2) - ), hexafluorophosphate anion (PF6) -), tetrafluoroborate anion (BF4) - ), hexafluoroarsenate anion (AsF6) - ), trifluoromethanesulfonate anion (CF3SO3) - One or more of the following.

[0179] In some embodiments, the electrolyte includes cations, which may include one or more of lithium ions and sodium ions.

[0180] In some embodiments, the concentration of the electrolyte salt may be 0.3 mol / L or higher, optionally 0.7 mol / L or higher, and further optionally 4 mol / L or lower, optionally 2.5 mol / L or lower, or 1.7 mol / L or lower. When the concentration of the electrolyte salt is within the above range, the electrolyte can have a suitable ionic conductivity.

[0181] Organic solvents may include, but are not limited to, one or more of esters, ethers, sulfones, and nitriles. Esters may include, but are not limited to, one or more of carbonates, phosphate esters, carboxylic esters, sulfate esters, and sulfonates. Carbonates may include cyclic carbonates and / or chain carbonates; optionally, carbonates may include both cyclic and chain carbonates. Chain carbonates may include low-viscosity polar chain carbonates, aliphatic branched carbonates, etc.

[0182] As an example, organic solvents may include, but are not limited to, ethylene carbonate (EC), propylene carbonate (PC), butene carbonate, ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), dimethyl ether tetraethylene glycol (TEGDME), ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL), trimethyl phosphate, 3-methoxypropionitrile, H(CF2)2OCH3, C4F9O CH3, H(CF2)2OCH2CH3, H(CF2)2OCH2CF3, H(CF2)2CH2O(CF2)2H, CF3CHFCF2OCH3, CF3CHFCF2OCH2CH3, 2-trifluoromethylhexafluoropropyl methyl ether, 2-trifluoromethylhexafluoropropyl ethyl ether, 2-trifluoromethylhexafluoropropyl propyl ether, 3-trifluoromethyloctafluorobutyl methyl ether, 3-trifluoromethyloctafluorobutyl ethyl ether, 3-trifluoromethyloctafluorobutyl propyl ether, 4-trifluoromethyl One or more of the following: decafluoropentyl methyl ether, 4-trifluoromethyl decafluoropentyl ethyl ether, 4-trifluoromethyl decafluoropentyl propyl ether, 5-trifluoromethyl dodecylfluorohexyl methyl ether, 5-trifluoromethyl dodecylfluorohexyl ethyl ether, 5-trifluoromethyl dodecylfluorohexyl propyl ether, 6-trifluoromethyl tetradecafluoroheptyl methyl ether, 6-trifluoromethyl tetradecafluoroheptyl ethyl ether, 6-trifluoromethyl tetradecafluoroheptyl propyl ether, 7-trifluoromethyl hexadecylfluorooctyl methyl ether, 7-trifluoromethyl hexadecylfluorooctyl ethyl ether, and 7-trifluoromethyl hexadecylfluorooctyl propyl ether.

[0183] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, additives that improve battery low-temperature power performance, etc.

[0184] [Isolation Component]

[0185] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

[0186] In some embodiments, the separator includes a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous membrane with good chemical and mechanical stability can be selected.

[0187] In some embodiments, the material of the separator may include at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation. The separator may be a single component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating may also be applied to the surface of the separator.

[0188] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0189] Example

[0190] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0191] Example 1

[0192] Positive electrode sheet

[0193] The positive electrode active material LiNi prepared above 0.8 Co 0.1 Mn 0.1 O2, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are mixed in solvent N-methylpyrrolidone (NMP) at a mass ratio of 98:1:1 and stirred until homogeneous to obtain a positive electrode slurry. The positive electrode slurry is then coated onto the surface of the positive electrode current collector aluminum foil, and subsequently dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0194] Negative electrode sheet

[0195] A negative electrode slurry was prepared by uniformly mixing the negative electrode active material (graphite:silicon oxide = 1:1), thickener sodium carboxymethyl cellulose (CMC-Na), conductive agent super P, and binder styrene-butadiene rubber (SBR) in deionized water at a mass ratio of 95:1:1:3. The negative electrode slurry was uniformly coated on the negative electrode current collector Ti foil, and then cold-pressed and slit to obtain the negative electrode sheet. Cu tabs were attached to the negative electrode current collector, and the Cu tabs were fixed to the current collector by ultrasonic welding. The width of the welding area was 3.5 mm, the distance between the edge of the welding area and the edge of the negative electrode film was 0.5 mm, and the surface of the welding area was covered with insulating adhesive.

[0196] Separating membrane

[0197] A polyethylene (PE) film with a thickness of 12μm was selected.

[0198] electrolyte

[0199] The electrolyte solvent is a mixture of ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1. The electrolyte salt is LiPF6, and the concentration of the electrolyte salt is 1 mol / L.

[0200] battery cell

[0201] The positive electrode, negative electrode, and separator are stacked in sequence and then injected with electrolyte to obtain a coin cell.

[0202] Example 2-11

[0203] The preparation method of the battery cell is similar to that in Example 1, except that the parameters of the negative electrode are different. The specific parameter adjustments are shown in Table 1.

[0204] Comparative Example 1

[0205] The preparation method of the battery cell is similar to that of Example 1, except that the parameters of the negative electrode are different. Specifically, the negative electrode current collector and the electrode tab are integrally formed, and the material is Ti.

[0206] Comparative Example 2

[0207] The preparation method of the battery cell is similar to that in Example 1, except that the parameters of the negative electrode are different. Specifically, the negative electrode current collector and the electrode tab are integrally formed, and the material is Cu.

[0208] Test section

[0209] 1. Welding strength of electrode lugs

[0210] Using a tensile testing machine, clamp one end of the fixture with the tab of the negative electrode sheet and the other end with the negative electrode sheet away from the tab. The electrode sheet width is 40mm. Stretch at a speed of 50mm / min and record the tensile force when the tab is stretched to separate from the current collector.

[0211] 2. Full charge extension rate

[0212] Before preparing the wound battery cell, mark two points on the negative electrode sheet, making the distance between the two marks 10cm. Then assemble the battery cell and charge it to 4.25V at a constant current of 0.33C. Disassemble the battery cell to obtain the negative electrode sheet and remeasure the distance L (cm) between the two marks. Then the full charge elongation (%) = (L-10) / 10×100%.

[0213] 3. Capacity retention rate at 45℃

[0214] At 45°C, the battery cell is charged to 4.25V at a constant current of 0.33C, left to stand for 5 minutes, and then discharged to 2.8V at a constant current of 0.33C. The discharge capacity C0 is recorded. The above charge and discharge steps are repeated for 500 cycles, and the discharge capacity C1 of the 500th cycle is recorded. The capacity retention rate after 500 cycles at 45°C is calculated as C1 / C0×100%.

[0215] The test results are detailed in Table 2.

[0216] Table 2

[0217] As can be seen from Example 1 and Comparative Examples 1 and 2, using a high-strength Ti current collector paired with a low-melting-point, high-plastic-deformation Cu tab can significantly improve the welding strength between the tab and the current collector, while also enabling the battery cell to have a high cycle capacity retention rate.

[0218] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery cell, comprising an electrode sheet, the electrode sheet comprising a current collector and a tab connected to the current collector; The electrode has a melting point of 600℃-1500℃, and its plastic deformation is greater than or equal to 60%, and the plastic deformation of the electrode is greater than that of the current collector.

2. The battery cell of claim 1, wherein, The plastic deformation of the electrode lugs is 75%-95%; and / or The melting point of the electrode is 800℃-1200℃.

3. The battery cell according to claim 1 or 2, wherein, The plastic deformation of the current collector is 15%-70%.

4. The battery cell according to claim 3, wherein, The plastic deformation of the current collector is 30%-65%.

5. The battery cell according to any one of claims 1-4, wherein, The electrode tab satisfies at least one of the following conditions: (1) The tensile strength of the electrode lug is 300MPa-1000MPa; (2) The elastic modulus of the electrode tab is 5GPa-45GPa; (3) The elongation of the electrode tab is 3%-8.5%; (4) The thermal conductivity of the electrode is 80 W / (m·K)-500 W / (m·K); (5) The thickness of the electrode tab is 4μm-10μm.

6. The battery cell according to claim 5, wherein, The electrode tab satisfies at least one of the following conditions: (1) The tensile strength of the electrode lug is 320MPa-500MPa; (2) The elastic modulus of the electrode tab is 6 GPa-20 GPa; (3) The thermal conductivity of the electrode is 100W / (m·K)-450W / (m·K).

7. The battery cell according to any one of claims 1-6, wherein, The material of the electrode tab includes one or more of Cu, Ag, Au, Sn, and Ni.

8. The battery cell according to any one of claims 1-7, wherein, The current collector satisfies at least one of the following conditions: (1) The tensile strength of the current collector is 400MPa-1500MPa; (2) The elastic modulus of the current collector is 30 GPa-75 GPa; (3) The elongation of the current collector is 1.5%-6%; (4) The thermal conductivity of the current collector is 5 W / (m·K)-150 W / (m·K); (5) The thickness of the current collector is 2μm-10μm.

9. The battery cell according to claim 8, wherein, The current collector satisfies at least one of the following conditions: (1) The tensile strength of the current collector is 600MPa-1200MPa; (2) The elastic modulus of the current collector is 40 GPa-70 GPa; (3) The elongation of the current collector is 2%-5%; (4) The thermal conductivity of the current collector is 6 W / (m·K)-120 W / (m·K); (5) The plastic deformation of the current collector is 40%-60%.

10. The battery cell according to any one of claims 1-9, wherein, The material of the current collector includes one or more of Ti, Ti alloys, Ni, and Ni alloys.

11. The battery cell according to any one of claims 1-10, wherein, The current collector includes a coated area with active material and an empty foil area without active material, and the tab is connected to the empty foil area.

12. The battery cell according to claim 11, wherein, The peel strength between the tab and the empty foil area is greater than or equal to 4 N / mm.

13. The battery cell according to claim 11 or 12, wherein, The width of the connection area between the electrode tab and the empty foil area is 2.5mm-5mm.

14. The battery cell according to claim 13, wherein, The distance between the connecting area and the coating area is 0.1mm-1mm.

15. The battery cell according to claim 13 or 14, wherein, The current collector also includes an insulating layer covering the connection area, wherein the connection area does not extend beyond the edge of the insulating layer.

16. The battery cell according to claim 15, wherein, The insulating layer is made of one or more of polyolefins, polyesters, polyamides, and polyurethanes.

17. The battery cell according to any one of claims 1-16, wherein, Along the width direction of the electrode tab, the size of the electrode tab is L1, the size of the current collector is L2, and 0.4≤L1 / L2≤0.

95.

18. The battery cell according to claim 17, wherein, 0.4≤L1 / L2≤0.

475.

19. The battery cell according to any one of claims 1-18, wherein, The electrode plates include one or both of positive and negative electrode plates.

20. The battery cell according to claim 19, wherein, The electrode sheet is a negative electrode sheet, and the negative electrode sheet includes a negative electrode film layer located on at least one side of the current collector, and the negative electrode film layer includes a negative electrode active material.

21. The battery cell according to claim 20, wherein, The negative electrode active material includes one or more of Li, Sn, Zn, carbon-based materials, and silicon-based materials.

22. The battery cell according to claim 21, wherein, The silicon-based material includes silicon-carbon composite materials.

23. A battery device comprising a battery cell according to any one of claims 1 to 22.

24. An electrical device comprising a battery cell according to any one of claims 1 to 22 or a battery device according to claim 23.

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