Battery cell, battery apparatus and electrical apparatus

Abstract

Provided are a battery cell (7), a battery apparatus (2) and an electrical apparatus. The battery cell (7) comprises a casing and an electrode assembly; at least part of the electrode assembly is accommodated within the casing; the electrode assembly comprises a positive electrode sheet (81), a separator (83) and a negative electrode sheet (82), the separator (83) being located between the positive electrode sheet (81) and the negative electrode sheet (82); the positive electrode sheet (81), the separator (83) and the negative electrode sheet (82) are wound and form a planar portion and a corner portion, the corner portion being connected to the planar portion; the corner portion comprises a first functional layer (84); the first functional layer (84) is located between the separator (83) and the negative electrode sheet (82) and / or between the separator (83) and the positive electrode sheet (81); the first functional layer (84) comprises a first additive; the first additive comprises one or more of Ti4+, Ge4+ and Sn4+. The provided battery cell (7) has high reliability and 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 No. 202510092312.8, filed on January 21, 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 reliability of battery cells is one of the most pressing issues to be addressed. 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 a casing and an electrode assembly, at least a portion of the electrode assembly being housed within the casing, the electrode assembly including a positive electrode, a separator, and a negative electrode, the separator being located between the positive and negative electrode, the positive electrode, the separator, and the negative electrode being wound together to form a planar portion and a corner portion, the corner portion being connected to the planar portion; the corner portion including a first functional layer, the first functional layer being located between the separator and the negative electrode and / or between the separator and the positive electrode, the first functional layer including a first additive, the first additive comprising Ti 4+ 、Ge 4+ Sn 4+ One or more of them.

[0008] According to the embodiments of this application, when the high-valence transition metal cation in the first additive comes into contact with lithium metal, it can gain electrons and be reduced, thereby reacting with lithium metal to consume the formed lithium dendrites. A first functional layer containing the first additive is provided on any one or both sides of the separator. When lithium dendrites are generated on the surface of the negative electrode, the first additive in the first functional layer can react with lithium metal to reduce lithium deposition. This can suppress the growth of lithium dendrites, reduce the risk of lithium dendrites piercing the separator, and improve the reliability of the battery cell.

[0009] In some embodiments, the first additive includes Ti 4+ 、Ge 4+ Sn 4+ Solid electrolytes containing one or more of the aforementioned transition metal cations exhibit high ionic conductivity, and the products generated from their reaction with lithium metal also possess high ionic conductivity. This allows for the improvement of the conductivity of individual battery cells while simultaneously consuming lithium dendrites during the reaction.

[0010] In some embodiments, the first solid electrolyte includes LATP solid electrolyte, LAGP solid electrolyte, and Li. 10 GeP2S 12 Li 10 SnP2S 12 One or more of them.

[0011] In some embodiments, the mass content of the first additive in the first functional layer is 30% to 95%. This can reduce the risk of lithium dendrite growth and puncture of the separator, thereby improving the reliability of the battery cell. On the other hand, the first functional layer can maintain high conductivity, which is beneficial to improving the lithium ion insertion / extraction efficiency.

[0012] In some embodiments, the mass content of the first additive in the first functional layer is 40% to 85%. This can further improve the reliability and cycle performance of the battery cell.

[0013] In some embodiments, the first functional layer includes a first adhesive, which includes one or more of polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, polymethyl methacrylate, polyacrylate, ethylene / vinyl acetate copolymer, and polyurethane. Thus, the first functional layer can bond the separator to the positive and / or negative electrode sheets, improving the bonding strength between the separator and the electrode sheets, reducing the gap between the electrode sheets and the separator, improving lithium-ion transport efficiency, thereby reducing lithium dendrite growth and improving the cycle performance of the battery cell.

[0014] In some embodiments, the mass content of the first adhesive is 5%-70% based on the total mass of the first functional layer. This allows the first functional layer to have a better bonding effect, further reducing the gap between the separator and the electrode.

[0015] In some embodiments, the mass content of the first binder is 15%-60% based on the total mass of the first functional layer. This is beneficial for further reducing the gap between the separator and the electrode, while the first functional layer can better react to consume lithium dendrites.

[0016] In some embodiments, the thickness of the first functional layer is 5 μm to 60 μm. This helps to further reduce lithium dendrite growth; at the same time, it can have high ionic conductivity, which is beneficial for the rapid transport of lithium ions.

[0017] In some embodiments, the thickness of the first functional layer is 15 μm to 50 μm.

[0018] In some embodiments, the first functional layer is located between the separator and the negative electrode sheet. This allows the first functional layer to come into contact with lithium dendrites appearing on the negative electrode side earlier, facilitating the rapid reaction and consumption of lithium dendrites and further improving the cycle performance of the battery cell.

[0019] In some embodiments, the first functional layer is located only at the corner. Therefore, providing the first functional layer only at the corner can effectively reduce the gap at the corner, while suppressing lithium dendrite growth and improving the cycle performance of the battery cell.

[0020] In some embodiments, the corner portion further includes a second functional layer located between the positive electrode and the separator. The second functional layer includes a second adhesive, and the mass content of the second adhesive is 5%-70% based on the total mass of the second functional layer. Bonding the positive electrode and the separator with the second functional layer can further reduce the gap between the separator and the positive electrode, improve ion transport efficiency, and thus enhance the cycle performance of the battery cell.

[0021] In some embodiments, the mass content of the second adhesive is 15% to 55% based on the total mass of the second functional layer.

[0022] In some embodiments, the second adhesive comprises one or more of polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, polymethyl methacrylate, polyacrylate, ethylene / vinyl acetate copolymer, and polyurethane.

[0023] In some embodiments, the second functional layer further includes a second additive, wherein the ionic conductivity of the second additive is greater than or equal to 10. -4 S / cm. This can further improve the lithium-ion transport efficiency in the battery cell and further improve the cycle performance of the battery cell.

[0024] In some embodiments, the second additive includes a solid electrolyte.

[0025] In some embodiments, the solid electrolyte includes one or more of perovskite-type solid electrolyte, garnet-type solid electrolyte, NaSICON-type solid electrolyte, and thio-LISICON-type solid electrolyte.

[0026] In some embodiments, the mass content of the second additive is 30% to 95% based on the total mass of the second functional layer. This allows the second functional layer to have high ionic conductivity, which is beneficial for the rapid transport of lithium ions.

[0027] In some embodiments, the mass content of the second additive is 45% to 85% based on the total mass of the second functional layer.

[0028] In some embodiments, the thickness of the second functional layer is 5 μm to 60 μm.

[0029] In some embodiments, the second functional layer is located only at the corner portion. Therefore, the second functional layer can better bond the separator of the positive electrode sheet, reduce the gap at the corner, shorten the ion transport path, and improve the cycle performance of the battery cell.

[0030] Secondly, embodiments of this application provide a battery device, including a single battery cell from the first aspect of this application.

[0031] 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

[0032] 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.

[0033] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0034] Figure 2 is a schematic diagram of the explosion of a battery provided in some embodiments of this application.

[0035] Figure 3 is an exploded view of the battery module shown in Figure 2.

[0036] Figure 4 is a schematic diagram of the electrode assembly winding structure in some embodiments of the application.

[0037] The accompanying drawings are not necessarily drawn to scale.

[0038] 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. Receiving space; 6. Battery module; 7. Battery cell; 81. Positive electrode; 82. Negative electrode; 83. Separator; 84. First functional layer; 85. Second functional layer. Detailed Implementation

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates 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.

[0044] 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.

[0045] In this application, the terms "multiple" or "various" refer to two or more kinds.

[0046] 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.

[0047] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0055] The technical solutions described in the embodiments of this application are applicable to battery devices and electrical devices that use battery devices.

[0056] 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.

[0057] Electrical devices can choose the type of battery device according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0058] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0059] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] Figure 3 is an exploded view of the battery module shown in Figure 2.

[0069] 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.

[0070] 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.

[0071] The battery cells mentioned in the embodiments of this application may include lithium-ion battery cells or sodium-ion battery cells.

[0072] A single battery cell includes an electrode assembly. The electrode assembly can be a wound structure or a stacked structure.

[0073] In some embodiments, the electrode assembly has a wound structure.

[0074] Electrode assemblies generally include a positive electrode, a negative electrode, and an insulating element. The insulating element is located between the positive electrode and the negative electrode. The positive electrode, the insulating element, and the negative electrode are wound together to form a planar portion and a corner portion. The corner portion is connected to the planar portion.

[0075] When positive electrode plates, negative electrode plates, and separators are wound to form a wound electrode assembly, gaps can easily form between the positive and negative electrode plates and the separators at the corners due to the different winding radii of the positive and negative electrode plates. These gaps increase the migration path of lithium ions during charging and discharging. Lithium ions extracted from the positive electrode cannot quickly embed into the interior of the negative electrode plate and will undergo lithium deposition on the surface of the negative electrode plate. Lithium deposition will cause the capacity of the battery cell to decrease. In severe cases, the lithium dendrites generated by lithium deposition can pierce the separator, causing a short circuit in the battery cell and affecting the reliability and cycle performance of the battery cell.

[0076] Therefore, the battery cell provided in this application embodiment can reduce lithium plating reaction at the corner by adjusting the structural design of the electrode assembly at the corner, thereby reducing the risk of lithium dendrites piercing the separator and improving the reliability and cycle performance of the battery cell.

[0077] The corner portion includes a first functional layer, the first functional layer includes a first additive, and the first additive contains Ti. 4+ 、Ge 4+ Sn 4+ One or more of them.

[0078] According to an embodiment of this application, Ti 4+ 、Ge 4+ Sn 4+ These high-valence transition metal cations can gain electrons and be reduced when in contact with lithium metal, and then react with lithium metal to consume lithium dendrites. This can inhibit the growth of lithium dendrites, reduce the risk of lithium dendrites piercing the separator, and improve the reliability and cycle performance of the battery cell.

[0079] In this application, the first functional layer can be disposed between the separator and the negative electrode, or between the separator and the positive electrode, or simultaneously between the separator and the positive electrode and between the separator and the negative electrode. Optionally, the first functional layer can be disposed between the separator and the negative electrode. This allows the first functional layer to come into contact with the lithium dendrites deposited on the surface of the negative electrode earlier, which is beneficial for the rapid reaction and consumption of lithium dendrites, further reducing the risk of lithium dendrites piercing the separator and causing internal short circuits in the battery cell, and improving the cycle performance and reliability of the battery cell.

[0080] In some embodiments, the first additive may include Ti 4+ 、Ge 4+ Sn 4+ One or more solid electrolytes.

[0081] According to the embodiments of this application, the solid electrolyte containing the cations of the aforementioned transition metal elements has high ionic conductivity, and the product generated by its reaction with lithium metal also has high ionic conductivity. Thus, the conductivity of the battery cell can be improved while the lithium dendrites are consumed in the reaction.

[0082] In some embodiments, the solid electrolyte may include LATP solid electrolyte, LAGP solid electrolyte, Li 10 GeP2S 12 Li 10 SnP2S 12 One or more of them.

[0083] According to embodiments of this application, the first additive can react with lithium metal to consume lithium metal. A first functional layer containing the first additive is disposed between the negative electrode and the separator. When lithium dendrites are generated during lithium deposition, the first additive in the first functional layer can react with and consume the lithium dendrites, thereby reducing lithium metal deposition. This can suppress lithium dendrite growth, reduce the risk of lithium dendrites piercing the separator, and improve the reliability and cycle performance of the battery cell. In embodiments of this application, the first additive can react with lithium metal to consume lithium metal, and at the same time, it has high ionic conductivity, which is conducive to rapid lithium ion transport and can further improve the electrochemical performance of the battery cell.

[0084] As an example, the reaction processes of LATP, LAGP, and lithium metal can be represented by the following reaction equations: Li + Li₄Ti₅Al x (PO4) 12 →Li⁴⁺xTi₅Al x (PO4) 12 Li+Li4Al 0.5 Ge 1.5 (PO4)3→Li x Al0.5 Ge 1.5 (PO4)3+Li + +e - As can be seen, the above reaction can effectively consume lithium metal, and the reaction products still have high ionic conductivity.

[0085] According to the embodiments of this application, the first functional layer can be formed by coating and drying a slurry containing a first additive. When coating the slurry, the slurry containing the first additive can be coated on the surface of the separator, or it can be coated on the surface of the positive electrode and / or the negative electrode. The embodiments of this application do not limit this.

[0086] In some embodiments, the mass content of the first additive in the first functional layer can be from 30% to 95%. Exemplarily, the mass content of the first additive in the first functional layer can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or any range of the above values. Optionally, the mass content of the first additive in the first functional layer can be from 45% to 85%.

[0087] The content of the first additive in the first functional layer is within the above range. On the one hand, it can effectively react and consume the precipitated lithium dendrites, reducing the risk of lithium dendrite growth and puncturing the separator. On the other hand, by limiting the content of the first additive in the first functional layer to the above range, the first functional layer can maintain a high conductivity, which is beneficial to improving the lithium ion insertion / extraction efficiency.

[0088] In some embodiments, the first functional layer further includes a first adhesive, which may include one or more of polyvinylidene fluoride (PVDF), ethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyacrylate, ethylene / vinyl acetate copolymer (EVA), and polyurethane (PU).

[0089] According to the embodiments of this application, the first adhesive can make the first functional layer have high adhesion, which can play the role of bonding and fixing the separator and the electrode. This can reduce the gap between the separator and the electrode at the corner, shorten the ion transport path at the corner, and enable lithium ions generated by the positive electrode to be quickly inserted into the negative electrode. This can reduce the formation of lithium dendrites on the surface of the negative electrode, thereby improving the cycle performance of the battery cell.

[0090] In some embodiments, based on the total mass of the first functional layer, the mass content of the first adhesive can be 5%-70%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or any range of the above values, and can be selected as 15%-60%.

[0091] According to the embodiments of this application, the mass content of the first binder in the first functional layer is within the above-mentioned range, which is beneficial for the first functional layer to have higher bonding strength, further reducing the gap between the separator and the electrode, and reducing the formation of lithium dendrites; at the same time, the first functional layer can better react to consume lithium dendrites and improve the cycle performance of the battery cell.

[0092] In some embodiments, the thickness of the first functional layer can be from 5 μm to 60 μm. Exemplarily, the thickness of the first functional layer can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, or any range of the above values. Optionally, the thickness of the first functional layer can be from 15 μm to 50 μm.

[0093] Limiting the thickness of the first functional layer within the aforementioned range facilitates the reaction and consumption of lithium metal, further reducing lithium dendrite growth. Simultaneously, it allows for higher ionic conductivity, promoting rapid lithium-ion transport. However, a higher thickness of the first functional layer leads to an increase in the overall thickness of the corner section and a wider gap between the positive and negative electrode plates. This results in increased lithium deposition on the negative electrode surface, affecting the reliability of the battery cell.

[0094] In some embodiments, the first functional layer may be located only at the corner.

[0095] According to embodiments of this application, for a wound-type battery cell, the contact between the separator and the electrode is better in the planar portion, with a small or no gap; however, the gap is larger at the corners due to the different winding radii of the separator, positive electrode, and negative electrode, making lithium plating more likely to occur at the corners. By placing the first functional layer only at the corners, the separator and electrode can be better bonded and fixed, reducing the gap between them, which helps to further suppress the growth of lithium dendrites and improve the cycle performance of the battery cell.

[0096] In some embodiments, the corner portion further includes a second functional layer located at least between the positive electrode and the separator. The second functional layer includes a second adhesive. Based on the total mass of the second functional layer, the mass content of the second adhesive can be 5%-70%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or any range of the above values, optionally 15%-55%.

[0097] According to the embodiments of this application, the second functional layer provided between the positive electrode and the separator can serve to bond and fix the separator and the positive electrode, which helps to reduce the gap between the positive electrode and the separator at the corner, further shorten the ion transport path, reduce lithium dendrite precipitation, and improve the cycle performance of the battery cell.

[0098] In some embodiments, the second adhesive may include one or more of polyvinylidene fluoride (PVDF), ethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyacrylate, ethylene / vinyl acetate copolymer (EVA), and polyurethane (PU).

[0099] The above-mentioned binders all have good bonding properties, which can improve the bonding strength between the positive electrode, negative electrode and the separator, further reduce the gap between the positive electrode and the negative electrode, shorten the lithium ion transport path, and thus reduce lithium deposition on the surface of the negative electrode, thereby improving the reliability of the battery cell.

[0100] In some embodiments, the second functional layer further includes a second additive, wherein the ionic conductivity of the second additive is greater than or equal to 10. -4 S / cm, selectable as 10 -4 S / cm-10 -1 S / cm.

[0101] According to an embodiment of this application, adding a second additive with high ionic conductivity to the second functional layer can improve the transmission rate of the cells at the corner, thereby improving the problem of decreased ionic conductivity caused by setting the second functional layer at the corner, and further improving the cycle performance of the battery cell.

[0102] In some embodiments, the second additive may include one or more of the following: perovskite solid electrolyte, garnet solid electrolyte, NaSICON solid electrolyte, and thio-LISICON solid electrolyte.

[0103] As an example, the second additive may include LLTO (Li 3x La 2 / 3-x TiO3, LixLa 2 / 3- x / 3TiO3), garnet-type LLZO (Li7La3Zr2O) 12 ), NaSICON type LAGP (Li 1.5 Al 0.5 Ge 1.5 (PO4)3), Li with thio-LISICON structure 10 GeP2S 12 and Li 10 SnP2S 12 One or more of them.

[0104] In some embodiments, the mass content of the second additive in the second functional layer can be from 30% to 95%. Exemplarily, the mass content of the second additive in the second functional layer can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or any range of the above values. Optionally, the mass content of the second additive in the second functional layer can be from 45% to 85%.

[0105] The content of the second additive in the second functional layer is within the above range, which can make the second functional layer have high ionic conductivity, which is conducive to the rapid transport of lithium ions. At the same time, it can make the second functional layer have high bonding strength, which is beneficial to improving the cycle performance of the battery cell.

[0106] In some implementations, the thickness of the second functional layer can be from 5 μm to 60 μm. Exemplarily, the thickness of the second functional layer can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, or any range of the above values. Optionally, the thickness of the second functional layer can be from 15 μm to 50 μm.

[0107] In some embodiments, the second functional layer may be located only at the corner.

[0108] According to the embodiments of this application, the second functional layer is disposed only at the corner to better bond and fix the separator and the electrode, reduce the gap between the separator and the electrode, which is beneficial to further suppress the growth of lithium dendrites and improve the cycle performance of the battery cell.

[0109] Figure 4 shows a partial schematic diagram of the structure of the electrode assembly in some embodiments of this application. The electrode assembly includes a positive electrode 81, a negative electrode 82, and an insulating member 83. The insulating member 83 is located between the positive electrode 81 and the negative electrode 82. The positive electrode 81, the insulating member 83, and the negative electrode 82 are wound together to form a wound structure. The wound structure has a corner portion and a planar portion. At the corner portion, a first functional layer 84 is provided between the negative electrode 82 and the insulating member 83, and a second functional layer is provided between the positive electrode 81 and the insulating member 83.

[0110] In this application, the first functional layer and its composition can be determined using methods known in the art, such as the following: discharging the battery cell (generally leaving it fully discharged), disassembling the battery cell to obtain the electrode assembly, and measuring and analyzing the cross-section of the corner of the electrode assembly using SEM (scanning electron microscope) to obtain the layer structure composition and thickness of each layer. The thickness of each layer can also be measured using a laser thickness gauge. In this application, the cross-section of the electrode assembly refers to the cross-section formed by slicing along the thickness direction of the separator.

[0111] In this application, the cross-section of the electrode assembly can be morphologically observed and combined with compositional analysis, such as energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis, to determine the elemental composition and confirm the chemical composition of each layer in the electrode assembly. Additionally, instruments such as focused electron beam (FIB) microscopy (e.g., the FEI Scios 2HiVa system) and ion section polishing instruments (e.g., the JEOL IB-09010CP argon ion section polishing instrument) can be used to polish the cross-section to obtain a clear cross-section.

[0112] The structure and chemical composition of each layer in the electrode assembly can also be determined by disassembling the electrode assembly. For example, the battery cell can be discharged (generally to a fully discharged state), the battery cell can be disassembled, and the separator can be removed. The separator can be soaked in dimethyl carbonate (DMC) for a certain period of time (e.g., 2-10 hours). Then, the separator can be removed and dried at a certain temperature and time (e.g., 60°C, 4 hours). After drying, the separator can be removed and baked at a certain temperature and time (e.g., 400°C, 2 hours). A sample can be taken from a randomly selected area (located in the corner) of the baked separator (a blade can be used to scrape off the powder for sampling). The sample can be analyzed by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), etc., to determine the elemental composition and confirm its chemical composition. Similarly, the positive and negative electrode plates can be measured in the same way.

[0113] [Positive electrode plate]

[0114] In some embodiments, the positive electrode includes a positive current collector and a positive electrode film layer located on at least one surface of the positive current collector. As an example, the positive 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 positive current collector.

[0115] In some embodiments, the positive electrode film layer includes a positive electrode active material.

[0116] In some embodiments, the positive electrode active material includes one or more of lithium phosphate, layered lithium transition metal oxide, Prussian blue compounds, polyanionic compounds, and sodium transition metal oxide.

[0117] 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.

[0118] Lithium-containing phosphates may include one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and their respective modified compounds.

[0119] 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.

[0120] 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.

[0121] The higher the Ni content in layered lithium-containing transition metal oxides, the higher the energy density of the battery cell.

[0122] In some embodiments, layered lithium-containing transition metal oxides may include Li a Ni b Co c M d O e A fWherein, 0 < a ≤ 1.2; 0.8 ≤ b < 1; 0 < c < 1; 0 < 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.

[0123] 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 One or more of O2.

[0124] 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.

[0125] In some embodiments, as an example, sodium transition metal oxides may include, but are not limited to:

[0126] 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;

[0127] Na 0.67 Mn 0.7 Ni z M2 0.3-z O2, where M 2 is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn, and Ba, and 0 < z ≤ 0.1;

[0128] Na a Li b Ni c Mn d Fe e O2, where 0.67 < a ≤ 1, 0 < b < 0.2, 0 < c < 0.3, 0.67 < d + e < 0.8, and b + c + d + e = 1.

[0129] In some embodiments, by way of example, the polyanionic compound may include, but is not limited to:

[0130] 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, and X 1 is one or more of F, Cl, and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, and 0 ≤ j ≤ 2;

[0131] Na n M 4 PO4X 2 where M 4 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, and X 2 is one or more of F, Cl, and Br, 0 < n ≤ 2;

[0132] 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, and 0 < q ≤ 2;

[0133] Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0134] In some embodiments, by way of example, Prussian blue compounds may include, but are not limited to:

[0135] A u M 6 v [M 7 (CN)6] w ·xH2O, where A is H + , NH4 + , one or more of alkali metal cations and alkaline earth metal cations, M 6 and M 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 2+ , Sr 2+ , Ba 2+ and Ra 2+ one or more of, M 6 and M 7 are each independently cations of one or more transition metal elements of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn and W. Optionally, A is one or more of Li + , Na + and K + , M 6 is cations of one or more transition metal elements of Mn, Fe, Co, Ni and Cu, M 7 is cations of one or more transition metal elements of Mn, Fe, Co, Ni and Cu.

[0136] In the enumeration of the positive electrode active materials in the embodiments of the present application, the molar content of O is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of O to change, and the actual molar content of O will fluctuate.

[0137] The modified compounds of the above positive electrode active materials may be doping modification and / or surface coating modification of the positive electrode active materials.

[0138] In some embodiments, the positive electrode film layer may optionally include a positive electrode binder. As an example, the positive electrode 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.

[0139] In some implementations, the weight percentage of the positive electrode binder in the positive electrode film layer is greater than or equal to 0.5%, which is beneficial for obtaining good adhesion performance.

[0140] 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.

[0141] In some embodiments, the positive current collector may 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 substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may 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 substrate. The polymer substrate may include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and other substrates.

[0142] In some embodiments, the thickness of the positive current collector is from 4 μm to 20 μm. It is optionally from 6 μm to 18 μm, and more preferably from 8 μm to 16 μm.

[0143] 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 the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0144] [Negative electrode plate]

[0145] The negative electrode includes a negative current collector and a negative electrode film layer located on at least one side of the negative current collector. As an example, the negative 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 negative current collector.

[0146] In some embodiments, the negative electrode film layer includes a negative electrode active material. As an example, the negative electrode active material may include one or more of artificial graphite, natural graphite, mesophase microcarbon spheres, hard carbon, soft carbon, silicon, and silicon-carbon composite materials.

[0147] 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.

[0148] 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.

[0149] In some embodiments, the negative electrode film layer may further include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0150] In some embodiments, the negative electrode film layer may also include other additives. As an example, other additives may include thickeners, such as carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0151] In some embodiments, the negative electrode current collector may 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.

[0152] The composite current collector may include a polymeric material substrate and a metallic material layer formed on at least one side of the polymeric material substrate. As an example, the metallic material may include, but is not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0153] 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.

[0154] The negative electrode sheet can be prepared as follows: The negative electrode active material, negative electrode binder, negative electrode conductive agent, and optional other additives are dispersed in a solvent and stirred evenly to form a negative electrode slurry; the negative electrode slurry is coated onto a negative electrode current collector, and after drying, rolling, and other processes, a negative electrode sheet is formed. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0155] [Electrolytes]

[0156] A single battery cell includes an electrolyte.

[0157] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0158] 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.

[0159] In some embodiments, the electrolyte includes cations, which may include one or more of lithium ions and sodium ions.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] In some embodiments, the electrolyte may optionally include a second additive. For example, the second additive may include a negative electrode film-forming second additive, or a positive electrode film-forming second additive, or a second additive capable of improving certain battery performance, such as a second additive that improves battery overcharge performance, a second additive that improves battery high-temperature performance, a second additive that improves battery low-temperature power performance, etc.

[0164] [Isolation Component]

[0165] 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.

[0166] 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.

[0167] 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.

[0168] Example

[0169] 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.

[0170] Example 1

[0171] Positive electrode sheet

[0172] Lithium iron phosphate (LiFePO4), conductive carbon black, and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 95:3:2 and then added to N-methylpyrrolidone (NMP) solvent to obtain a uniformly dispersed positive electrode slurry. The positive electrode slurry was coated onto the surface of the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0173] Negative electrode sheet

[0174] A negative electrode slurry is prepared by uniformly mixing graphite (a negative electrode active material), Super P (a conductive agent), carboxymethyl cellulose (CMC) (a thickener), and styrene-butadiene rubber (SBR) (a negative electrode binder) in deionized water at a mass ratio of 95:3:1:1. The negative electrode slurry is then uniformly coated onto copper foil (a current collector) and dried at 85°C. After cold pressing and slitting, the negative electrode sheet is obtained.

[0175] Separating membrane

[0176] A polyethylene (PE) film with a thickness of 13μm was selected.

[0177] electrolyte

[0178] 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.

[0179] battery cell

[0180] The first additive LATP (Li 1.3 Al 0.3 Ti 1.7 (PO4)3) and the binder polyvinylidene fluoride (PVDF) are mixed at a mass ratio of 65:35 and then added to the solvent N-methylpyrrolidone (NMP) and uniformly dispersed to obtain the first functional slurry;

[0181] The second additive LLTO(Li 0.33 La 0.56 TiO3) and the binder polyvinylidene fluoride (PVDF) were mixed at a mass ratio of 70:30 and then added to the solvent NMP and uniformly dispersed to obtain the second functional slurry;

[0182] The first functional slurry is uniformly coated on a portion of the separator membrane near the negative electrode, and the second functional slurry is uniformly coated on a portion of the separator membrane near the positive electrode. After drying, the first functional layer and the second functional layer are obtained respectively. The thickness of the first functional layer is 35 μm and the thickness of the second functional layer is 30 μm.

[0183] The positive electrode, negative electrode, and separator prepared above are stacked in sequence, with the separator positioned between the positive and negative electrode sheets to provide isolation. The first functional layer is located on the side closer to the positive and negative electrode sheets, and the second functional layer is located on the side closer to the positive electrode sheet. Then, the electrode assembly is wound up, with both the first and second functional layers located at the corners of the electrode assembly. The electrode assembly is then welded with tabs and installed in an aluminum shell. It is baked at 80°C to remove water, followed by the injection of electrolyte and sealing. The battery cell is then produced by sequentially undergoing processes such as settling, hot and cold pressing, formation, shaping, and capacity testing.

[0184] Example 2-14

[0185] The difference from Example 1 is that the composition parameters of the battery cells are different. For details of the parameter adjustments, please refer to Table 1.

[0186] Table 1

[0187] Example 15

[0188] The preparation method of the battery cell is similar to that of Example 1, except that the first functional layer is located at both the corner and flat parts of the electrode assembly; the other parameters are consistent with those of Example 1.

[0189] Example 16

[0190] The preparation method of the battery cell is similar to that of Example 1, except that the second functional layer is located at both the corner and flat parts of the electrode assembly; all other parameters are consistent with those of Example 1.

[0191] Comparative Example 1

[0192] The preparation method of the battery cell is similar to that of Example 1, except that the first functional layer and the second functional layer are not set; otherwise, they are consistent with Example 1.

[0193] Comparative Example 2

[0194] The preparation method of the battery cell is similar to that of Example 1, except that the first functional layer is located only in the planar part of the electrode assembly, and the other parameters are consistent with those of Example 1.

[0195] Test section

[0196] 1. Capacity

[0197] The battery cell is charged at a constant current of 0.1C to the upper limit of the cutoff voltage, charged at a constant voltage to 0.05C, and then discharged at a constant current of 0.1C to the lower limit of the cutoff voltage. The specific capacity of the battery cell is the ratio of the initial discharge capacity of the battery cell to the mass of the positive electrode active material.

[0198] 2. Cyclic performance

[0199] At 25°C, the battery cell was charged at a constant current of 0.1C to 3.65V, then charged at a constant voltage to 0.05C, left to stand for 5 minutes, and then discharged at a constant current of 0.1C to 2.8V. The initial discharge capacity C0 was recorded. The above charge and discharge process was repeated, and the discharge capacity Cn of each cycle was recorded until the cycle capacity retention rate (Cn / C0*100%) reached 80%. The number of cycles was recorded.

[0200] 3. Reliability

[0201] Battery cells with a discharge capacity decay to 80% were disassembled in a low-humidity room with a relative humidity of less than 5%, and the lithium plating state on the surface of the negative electrode was observed to evaluate reliability. Based on the content of deposited lithium metal on the surface of the negative electrode, they were classified into the following four levels:

[0202] Severe lithium plating: Continuous, sheet-like deposits of silvery lithium metal are observed on the surface of the negative electrode.

[0203] Obvious lithium plating: Discontinuous, blocky lithium metal deposits are observed on the surface of the negative electrode.

[0204] Slight lithium plating: Obvious dot-like lithium metal deposits are observed on the surface of the negative electrode.

[0205] No lithium deposition: No obvious lithium metal deposition is observed on the surface of the negative electrode.

[0206] For detailed performance test results, please refer to Table 2.

[0207] Table 2

[0208] As can be seen from Example 1, Comparative Example 1 and Comparative Example 2, setting a first functional layer at the corner of the electrode assembly can effectively improve the lithium plating problem of the negative electrode at the corner, while increasing the cycle number of the battery cell.

[0209] As can be seen from Examples 1 and 15 and 16, when the first functional layer or the second functional layer is set only at the corner, compared with setting the first functional layer / second functional layer on the planar part of the electrode assembly, the lithium plating of the battery cell is similar, but the specific capacity is improved to a certain extent. This shows that setting the first functional layer / second functional layer only at the corner can make the battery cell have better performance.

[0210] 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 a housing and an electrode assembly, wherein at least a portion of the electrode assembly is housed within the housing, the electrode assembly comprising a positive electrode, a separator, and a negative electrode, the separator being located between the positive electrode and the negative electrode; the positive electrode, the separator, and the negative electrode are wound together to form a planar portion and a corner portion, the corner portion being connected to the planar portion; The corner portion includes a first functional layer, which is located between the separator and the negative electrode and / or between the separator and the positive electrode. The first functional layer includes a first additive containing Ti. 4+ 、Ge 4+ Sn 4+ One or more of them.

2. The battery cell of claim 1, wherein, The first additive includes Ti 4+ 、Ge 4+ Sn 4+ One or more solid electrolytes.

3. The battery cell of claim 2, wherein, The solid electrolyte includes LATP solid electrolyte, LAGP solid electrolyte, and Li. 10 GeP2S 12 Li 10 SnP2S 12 One or more of them.

4. The battery cell of any one of claims 1-3, wherein, Based on the total mass of the first functional layer, the mass content of the first additive is 30% to 95%.

5. The battery cell of claim 4, wherein, Based on the total mass of the first functional layer, the mass content of the first additive is 40% to 85%.

6. The battery cell of any one of claims 1-5, wherein, The first functional layer includes a first adhesive, which includes one or more of polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, polymethyl methacrylate, polyacrylate, ethylene / vinyl acetate copolymer, and polyurethane.

7. The battery cell of claim 6, wherein, Based on the total mass of the first functional layer, the mass content of the first adhesive is 5%-70%.

8. The battery cell of claim 7, wherein, Based on the total mass of the first functional layer, the mass content of the first adhesive is 15%-60%.

9. The battery cell of claim 8, wherein, The thickness of the first functional layer is 15 μm to 50 μm.

10. The battery cell according to any one of claims 1-9, wherein, The first functional layer is located between the insulating element and the negative electrode sheet.

11. The battery cell according to any one of claims 1-10, wherein, The first functional layer is located only at the corner.

12. The battery cell of any one of claims 1-11, wherein, The corner portion further includes a second functional layer located between the positive electrode and the separator. The second functional layer includes a second adhesive, and the mass content of the second adhesive is 5%-70% based on the total mass of the second functional layer.

13. The battery cell of claim 12, wherein, Based on the total mass of the second functional layer, the mass content of the second adhesive is 15% to 55%.

14. The battery cell of claim 12 or 13, wherein, The second adhesive comprises one or more of polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, polymethyl methacrylate, polyacrylate, ethylene / vinyl acetate copolymer, and polyurethane.

15. The battery cell of any one of claims 12-14, wherein, The second functional layer further comprises a second additive, the ionic conductivity of which is greater than or equal to 10 -4 S / cm.

16. The battery cell of claim 15, wherein, The second additive includes a solid electrolyte.

17. The battery cell of claim 16, wherein, The solid electrolyte includes one or more of the following: perovskite solid electrolyte, garnet solid electrolyte, NaSICON solid electrolyte, and thio-LISICON solid electrolyte.

18. The battery cell of any one of claims 15-17, wherein, Based on the total mass of the second functional layer, the mass content of the second additive is 30% to 95%.

19. The battery cell of claim 18, wherein, Based on the total mass of the second functional layer, the mass content of the second additive is 45% to 85%.

20. The battery cell of any one of claims 12-19, wherein, The thickness of the second functional layer is 5 μm to 60 μm.

21. The battery cell according to any one of claims 12-20, characterized in that, The second functional layer is located only at the corner.

22. A battery device comprising a battery cell according to any one of claims 1 to 21.

23. An electrical device comprising a battery cell according to any one of claims 1 to 21 or a battery device according to claim 22.

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