Negative electrode-free battery cell, battery apparatus, and electric apparatus

Abstract

The present application discloses a negative electrode-free battery cell, a battery apparatus, and an electric apparatus. The negative electrode-free battery cell comprises a positive electrode sheet, a negative electrode sheet, and a separator, wherein the separator is located between the positive electrode sheet and the negative electrode sheet, and the separator comprises: a first base film, and a second base film located between the first base film and the negative electrode sheet; a porosity of the first base film is less than a porosity of the second base film, and the porosity of the second base film is 50%-90%. The negative electrode-free battery cell provided in the present application exhibits relatively low expansion and improved cycling performance.

Description

Negative electrode battery cells, battery devices and electrical devices

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application 202510117694.5, filed on January 24, 2025, entitled “Anode-free 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 negative electrode-free 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 process of battery development, how to improve the cycle performance of batteries is one of the urgent problems to be solved. Summary of the Invention

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

[0007] In a first aspect, embodiments of this application provide a negative electrode-free battery cell, including a positive electrode, a negative electrode, and a separator, wherein the separator is located between the positive electrode and the negative electrode, and the separator includes: a first base film; and a second base film located between the first base film and the negative electrode; wherein the porosity of the first base film is less than the porosity of the second base film, and the porosity of the second base film is 50%-90%.

[0008] According to embodiments of this application, by making the side of the separator closer to the negative electrode (i.e., the second base film) have a higher porosity, when the deposition space on the surface of the negative electrode is insufficient, the metal will extend into the pores of the separator. This reduces the continuous compression of the separator by metal deposition on the negative side, thereby reducing the volume expansion of the battery cell caused by metal deposition. Furthermore, by making the side of the separator closer to the positive electrode (i.e., the first base film) have a lower porosity, the portion of the separator closer to the positive electrode can have higher strength, resulting in higher dendrite resistance and higher puncture strength, reducing the risk of short circuit in the battery cell caused by metal deposition puncturing the separator.

[0009] In some embodiments, the porosity of the second base film is 70%-80%. This allows the separator to have more space to accommodate metal deposition, which is beneficial for metal deposition in the pores of the separator, thereby reducing the volume expansion of the battery cell caused by the increase in the thickness of the negative electrode sheet.

[0010] In some embodiments, the thickness h of the second base film satisfies: in, Here, H represents the porosity of the second base film, and H is the theoretical deposition thickness of the active metal on the surface of the negative electrode sheet, wherein the active metal is lithium or sodium. This allows the active metal to be deposited as completely as possible within the pores of the second base film, further reducing the increase in the thickness of the negative electrode sheet during battery cell charging and minimizing the volume expansion of the battery cell.

[0011] In some embodiments, the thickness of the second base film is 10 μm-50 μm. This provides ample space for accommodating the deposition of active metals, while the isolation membrane can possess high strength.

[0012] In some embodiments, the second base membrane comprises a mesh membrane formed of fibers.

[0013] In some embodiments, the fiber diameter is 0.2 μm-10 μm.

[0014] In some embodiments, the aspect ratio of the fiber is 1000-10000.

[0015] In some embodiments, the tensile strength of the fiber is 1.5g-15g.

[0016] In some embodiments, the pore size of the mesh membrane is 2μm-100μm.

[0017] In some embodiments, the material of the second base film includes one or more of polypropylene nonwoven fabric, polyethylene nonwoven fabric, polyamide nonwoven fabric, and polyethylene terephthalate nonwoven fabric.

[0018] In some embodiments, the porosity of the first base membrane is 20%-50%. This reduces the risk of metal deposition puncturing the isolation membrane while maintaining a high ion transport rate.

[0019] In some embodiments, the porosity of the first base film is 33%-45%.

[0020] In some embodiments, the thickness of the first base film is 7 μm-12 μm. This reduces the risk of metal deposition puncturing the separator and causing internal short circuits in the battery cell, thereby improving the reliability of the battery cell.

[0021] In some embodiments, the material of the first base film includes one or more of polyethylene, polypropylene, and polyimide.

[0022] In some embodiments, the separator includes a first adhesive layer located between the first base film and the second base film, the first adhesive layer comprising a first adhesive. This reduces the misalignment between the first and second base films, improving the structural stability of the separator.

[0023] In some embodiments, the first adhesive layer further includes first inorganic particles, wherein the volume distribution particle size Dv of the first inorganic particles is... 1 The thickness of 50 is 0.2μm-0.5μm. This can improve the strength of the adhesive layer, further reduce the risk of metal deposition puncturing the separator and causing internal short circuits in the battery cell, thereby improving the reliability of the battery cell.

[0024] In some embodiments, the mass content of the first inorganic particles in the first adhesive layer can be 85%-95%.

[0025] In some embodiments, the separator includes a second adhesive layer located between the first base film and the positive electrode sheet, and the second adhesive layer includes a second adhesive.

[0026] In some embodiments, the second adhesive layer comprises second inorganic particles, wherein the volume distribution particle size Dv of the second inorganic particles is... 2 50 is 0.04μm-0.16μm.

[0027] In some embodiments, the mass content of the second inorganic particles in the second adhesive layer is 85%-95%.

[0028] In some embodiments, the separator includes a third adhesive layer located between the second base film and the negative electrode sheet, and the third adhesive layer includes a third adhesive.

[0029] In some embodiments, the first adhesive, the second adhesive, and the third adhesive each independently comprise one or more of thermoplastic polypropylene, polyethylene glycol, polyvinyl alcohol, polystyrene, and ethylene propylene diene monomer (EPDM) rubber.

[0030] In some embodiments, the first inorganic particle and the second inorganic particle each independently comprise one or more of boehmite, alumina, aluminum oxide, silicon dioxide, and zirconium oxide.

[0031] In some embodiments, the thickness of the first adhesive layer is 1 μm-3 μm.

[0032] In some embodiments, the thickness of the second adhesive layer is 1 μm-3 μm.

[0033] In some embodiments, the thickness of the third adhesive layer is 1 μm-3 μm.

[0034] In some embodiments, the thickness of the isolation membrane is 15μm-65μm.

[0035] Secondly, embodiments of this application provide a battery device, including a single negative electrode-free battery cell according to the first aspect of this application.

[0036] Thirdly, embodiments of this application provide an electrical device, including a single negative electrode-free battery cell according to the first aspect of this application or a battery device according to the second aspect of this application. Attached Figure Description

[0037] 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.

[0038] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0039] Figure 2 is a schematic diagram of the explosion of a battery provided in some embodiments of this application.

[0040] Figure 3 is an exploded view of the battery module shown in Figure 2.

[0041] The accompanying drawings are not necessarily drawn to scale.

[0042] 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

[0043] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the negative electrode-free 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 for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] In this application, the terms "multiple" or "various" refer to two or more kinds.

[0050] 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.

[0051] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0059] The technical solutions described in the embodiments of this application are applicable to battery devices and electrical devices that use battery devices.

[0060] 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.

[0061] Electrical devices can choose the type of battery device according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0062] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0063] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] Figure 3 is an exploded view of the battery module shown in Figure 2.

[0073] 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.

[0074] 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.

[0075] The battery cell provided in this application embodiment is a negative electrode-free battery cell, which may include at least one of a negative electrode-free lithium metal battery cell and a negative electrode-free sodium metal battery cell.

[0076] A negative electrode-free battery cell typically refers to a battery cell in which no negative electrode active material layer is actively formed on the negative electrode side during the battery cell manufacturing process. For example, the negative electrode active material layer is not formed at the negative electrode through coating or deposition processes, or it is formed from a carbonaceous active material layer. During the first charge, ions gain electrons on the negative electrode side and deposit metal on the surface of the negative electrode current collector. During discharge, the metal can be converted back into ions and return to the positive electrode, achieving cyclic charging and discharging. Compared to other battery cells, a negative electrode-free battery cell can achieve a higher energy density due to the absence of a negative electrode active material layer. In some embodiments, to improve battery cell performance, some conventional materials that can be used as negative electrode active materials, such as carbon materials, can also be placed on the negative electrode side of the negative electrode-free battery cell. Although these materials have a certain capacity, because their content is small and they are not used as the main negative electrode active material in the battery cell, such a battery cell can still be considered a negative electrode-free battery cell. The Cell Balance (CB) value of a negative electrode-free battery cell is typically very small; for example, in some embodiments, the CB value of a negative electrode-free battery cell can be less than or equal to 0.1. The CB value is the capacity per unit area of ​​the negative electrode divided by the capacity per unit area of ​​the positive electrode in the battery cell. Because a negative electrode-free battery cell contains little or no negative electrode active material, the capacity per unit area of ​​the negative electrode is small, and therefore the CB value is very small, typically less than or equal to 0.1.

[0077] A single negative electrode-free 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 to this.

[0078] Electrode assemblies generally include a positive electrode, a negative electrode, and a separator.

[0079] The separator, located between the positive and negative electrodes, serves to isolate them. In a negative electrodeless battery cell, during the first charge, ions gain electrons on the negative electrode side and deposit metal on the surface of the negative electrode current collector. This metal deposition on the negative electrode side significantly increases the thickness of the negative electrode, compressing the separator. This results in substantial volume expansion of the battery cell during charging, and if the compressive pressure reaches a certain level, there is a risk of puncturing the separator, connecting the positive and negative electrodes, and causing a short circuit. Related technologies generally employ 3D current collectors to mitigate the expansion of negative electrodeless battery cells during charging and discharging. 3D current collectors have abundant porous structures, allowing some or all of the metal to deposit within the pores during charging, reducing metal deposition on the negative electrode surface and thus alleviating the volume expansion of the negative electrode. Because the pores of the 3D current collector extend into the interior of the current collector and the pore size is tortuous, after metal is deposited in the pores of the current collector, there will be some metal residue in the pores of the current collector when the battery cell is fully discharged, which will lead to a decrease in the coulombic efficiency of the battery cell and is not conducive to the full utilization of the battery cell's capacity.

[0080] In view of this, embodiments of this application provide a separator for a negative electrode-free battery cell. By adjusting the design of the separator, the expansion of the negative electrode-free battery cell during the charging process can be reduced, while the negative electrode-free battery cell has a high coulombic efficiency.

[0081] [Isolation membrane]

[0082] In some embodiments, the separator membrane includes:

[0083] First base film,

[0084] The second base film is located between the first base film and the negative electrode plate;

[0085] The porosity of the first base membrane is less than that of the second base membrane, and the porosity of the second base membrane is 50%-90%.

[0086] In this embodiment, a composite separator design is employed, resulting in a higher porosity on the side of the separator closest to the negative electrode (i.e., the second base film). When there is insufficient deposition space on the surface of the negative electrode, metal will extend into the pores of the separator, thereby reducing the continuous compression of the separator by metal deposition on the negative side, and thus reducing the volume expansion of the battery cell caused by metal deposition. Furthermore, the separator is designed with a lower porosity on the side closest to the positive electrode (i.e., the first base film), which allows the portion of the separator closest to the positive electrode to have higher strength, resulting in higher dendrite resistance and higher puncture strength, reducing the risk of short circuits in the battery cell caused by metal deposition puncturing the separator.

[0087] According to the embodiments of this application, during the discharge process of a battery cell, the metal deposited in the pores of the separator is closer to the positive electrode and will be converted into ions and return to the positive electrode earlier. This can reduce the metal residue during the discharge process, enabling the battery cell to have high coulombic efficiency and improve the cycle performance of the battery cell.

[0088] In this embodiment, the porosity of the second base membrane can be 50%-90%, for example, it can be 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 62%, 65%, 68%, 70%, 75%, 80%, 85%, 90%, or any range of the above values. Optionally, the porosity of the second base membrane can be 70%-80%.

[0089] Limiting the porosity of the second base film to the above-mentioned range allows the separator to have more space to accommodate metal deposition, which is beneficial for metal deposition in the pores of the separator and reduces the volume expansion of the battery cell caused by the increase in the thickness of the negative electrode sheet. At the same time, the separator can have higher mechanical strength, which is beneficial for maintaining good structural stability. The higher the porosity of the second base film, the more active metal can be deposited in it. However, excessively high porosity of the second base film will lead to a decrease in the strength of the separator, which is not conducive to the stretching and assembly of the separator.

[0090] In some embodiments, the thickness h of the second base film satisfies: in, H represents the porosity of the second base film, and H represents the theoretical deposition thickness of the active metal on the surface of the negative electrode. The active metal is lithium or sodium.

[0091] According to embodiments of this application, during the deposition process, the metal can be deposited as much as possible into the pores of the separator, starting from the surface of the negative electrode sheet. This reduces the volume expansion of the battery cell caused by the increased thickness of the negative electrode sheet. The thickness h of the second base film is related to the porosity. product This refers to the actual pore depth of the second base film in the thickness direction, which defines the thickness h and porosity of the second base film. The product of the active metal thickness and the negative electrode thickness is not less than the theoretical deposition thickness of the active metal. The separator provides sufficient deposition space for the active metal, allowing it to be deposited as much as possible in the pores of the second base film. This further reduces the increase in the thickness of the negative electrode during battery cell charging, thus reducing the volume expansion of the battery cell. Furthermore, limiting the thickness of the second base film to the above range ensures it has sufficient pore space to accommodate metal deposition, reducing the risk of lithium dendrite growth piercing the separator and causing a short circuit in the battery cell, thereby improving the reliability of the battery cell.

[0092] In this application, the theoretical deposition thickness of the active metal can be obtained by methods known in the art. For example, it can be calculated as follows: the theoretical deposition thickness of the active metal on the surface of the negative electrode sheet H = [(a×b×c) / d] / ρ / s; where,

[0093] a represents the coating weight of the positive electrode film, in g / cm³. 2 ;

[0094] b represents the solid content (%) of the positive electrode slurry that forms the positive electrode film.

[0095] c represents the charge capacity of a single battery cell, in mAh / g;

[0096] d represents the theoretical specific capacity of the active metal (Li or Na), in mAh / g;

[0097] ρ is the theoretical density of the active metal, in g / cm³. 3 ;

[0098] s is the area of ​​one side of the negative electrode plate, in mm. 2 .

[0099] In some embodiments, the theoretical deposition thickness H of the active metal on the surface of the negative electrode can be 22.44 μm.

[0100] In some embodiments, the thickness of the second base film can be 10 μm-50 μm, for example, it can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or any range of the above values. Optionally, the thickness of the second base film can be 15 μm-45 μm.

[0101] When the thickness of the second base film is within the above-mentioned range, it can provide more space to accommodate the deposition of active metals, while the separator can have higher strength. The thicker the second base film, the more space it can accommodate the deposition of active metals, and it can further delay the arrival of lithium dendrites at the positive electrode. However, if the thickness of the second base film is too thick, it will lead to an increase in the thickness of the positive electrode of the electrode assembly, a decrease in the proportion of active materials in the battery cell, and a decrease in the energy density of the battery cell.

[0102] In some embodiments, the second base film may include a mesh film formed of fibers.

[0103] The mesh membrane in this application refers to a membrane with a mesh structure formed by the arrangement of fibers. In a mesh membrane, the fibers can be arranged in an ordered or disordered manner. Mesh membranes can be prepared by methods known in the art, such as, but not limited to, carding, air-jet bonding, spunbonding, melt-blowing, needle punching, hydroentangling, chemical bonding, and thermal bonding.

[0104] In some embodiments, the fiber diameter can be 0.2μm-10μm, for example, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 2.0μm, 3.0μm, 4.0μm, 5.0μm, 6.0μm, 7.0μm, 8.0μm, 9.0μm, 10.0μm, or any range of the above values, and can be selected as 0.5μm-1.5μm.

[0105] According to embodiments of this application, the fiber diameter refers to the diameter of the fiber. Limiting the fiber diameter to the above-mentioned range is beneficial for the mesh membrane to achieve both high mechanical strength and processing performance. When the fiber diameter is small, processing is more difficult, the formed mesh structure is prone to collapse, resulting in poor structural stability of the separator membrane; when the fiber diameter is large, the formed mesh membrane is thicker, has poor consistency, and its porosity is difficult to control.

[0106] In some embodiments, the aspect ratio of the fiber can be 1000-10000, for example, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, or any range of the above values, and can be selected as 4000-8000.

[0107] According to embodiments of this application, the aspect ratio of a fiber refers to the ratio of the length to the diameter of an individual fiber. Limiting the aspect ratio of the fiber to the above range is beneficial for the mesh membrane to achieve both high strength and processing performance. When the aspect ratio of the fiber is large, the processing is more difficult, and the resulting mesh structure is prone to collapse; when the fiber diameter is small, the resulting mesh membrane is thicker, has poor consistency, and its porosity is difficult to control.

[0108] In some embodiments, the tensile strength of the fiber can be 1.5g-15g, for example, 1.5g, 2g, 3g, 4g, 5g, 6g, 7g, 8g, 9g, 10g, 11g, 12g, 13g, 14g, 15g, or any range of the above values, and can be selected as 3g-8g.

[0109] According to embodiments of this application, the tensile strength of a fiber refers to the weight it bears when the fiber breaks. Limiting the tensile strength of the fiber to the above range is beneficial for the mesh membrane to achieve both high strength and processing performance. When the tensile strength of the fiber is low, the resulting mesh membrane has low strength, leading to a decrease in the overall strength of the separator and poor structural stability; when the tensile strength of the fiber is high, the processing difficulty is greater.

[0110] In some embodiments, the pore size of the mesh membrane is 2μm-100μm, for example, it can be 2μm, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, or any range of the above values, and can be selected as 30μm-100μm.

[0111] According to embodiments of this application, the pore size of the mesh membrane refers to the equivalent diameter of the pores formed by the fibers surrounding the pores, that is, the diameter of the equivalent circle with the same area as the pores. Limiting the pore size of the mesh membrane to the above range allows the mesh membrane to achieve both good porosity and high strength. When the pore size of the mesh membrane is small, its porosity is poor, which is not conducive to lithium metal deposition; when the pore size is large, the support of the mesh membrane is poor, leading to deviations in the strength of the separator.

[0112] In this application, the fiber diameter, aspect ratio, and pore size of the mesh membrane can be determined using methods known in the art, which facilitates measurement via transmission electron microscopy (TEM) images of the mesh membrane. The tensile strength of the fiber can be determined using methods and instruments known in the art. For example, the fiber can be clamped in a fixture, stretched using loads of different masses, and the mass of the applied load when the fiber breaks is recorded as the tensile strength of the fiber.

[0113] According to embodiments of this application, the porosity of the second base membrane can be adjusted by adjusting the filament diameter, aspect ratio, and pore size of the fibers forming the mesh membrane.

[0114] In some embodiments, the material of the second base film may include one or more of polypropylene (PP), polyethylene (PE), polyamide (PA), and polyethylene terephthalate (PET).

[0115] According to an embodiment of this application, the second base film can be prepared from fibers formed from the above-described materials using methods known in the art.

[0116] In some embodiments, the porosity of the first base membrane can be 20%-50%, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 46%, 48%, 50%, or any range of the above values. Optionally, the porosity of the first base membrane can be 33%-45%.

[0117] The porosity of the first base film is within the aforementioned range, which provides high resistance to dendrite penetration and reduces the risk of metal deposition puncturing the separator. Simultaneously, the porosity of the first base film within the aforementioned range also provides a high degree of ion transport channels, facilitating rapid ion transport.

[0118] In this application, the porosity of the first base film and the second base film have meanings known in the art and can be obtained by known methods and instruments. For example, a mercury porosimeter can be used for testing in accordance with GB / T 21650.1-2008.

[0119] In some embodiments, the thickness of the first base film can be 5 μm-15 μm. For example, it can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or any range of the above values. Optionally, the thickness of the first base film can be 7 μm-12 μm.

[0120] The thickness of the first base film is within the above range, which can have a high dendrite puncture resistance, which helps to reduce the risk of internal short circuits in battery cells caused by metal deposition puncturing the separator and improves the reliability of battery cells.

[0121] In some embodiments, the material of the first base film may include one or more of polyethylene (PE), polypropylene (PP), and polyimide (PI).

[0122] In some embodiments, the separator may include a first adhesive layer located between a first base film and a second base film, the first adhesive layer including a first adhesive.

[0123] According to embodiments of this application, the first base film and the second base film can be bonded and fixed by a first adhesive layer, which can reduce the misalignment between the first base film and the second base film and improve the structural stability of the separator. In other embodiments, the first base film and the second base film can also be fixed by thermal bonding, without the need for a first adhesive layer.

[0124] In some embodiments, the first adhesive layer may include first inorganic particles.

[0125] Inorganic particles can improve the strength of the bonding layer, further reducing the risk of metal deposition puncturing the separator and causing internal short circuits in the battery cell, thereby improving the reliability of the battery cell.

[0126] In some embodiments, the mass content of the first inorganic particles in the first adhesive layer can be 85%-95%, for example, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, or any range of the above values. Optionally, the mass content of the first inorganic particles in the first adhesive layer can be 90%-92%.

[0127] In some embodiments, the separator may include a second adhesive layer located between the first base film and the positive electrode sheet, and the second adhesive layer includes a second adhesive.

[0128] In some embodiments, the second adhesive layer may include second inorganic particles.

[0129] In some embodiments, the mass content of the second inorganic particles in the second adhesive layer can be 85%-95%, for example, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, or any range of the above values. Optionally, the mass content of the second inorganic particles in the second adhesive layer can be 90%-92%.

[0130] In some embodiments, the first inorganic particle and the second inorganic particle may each independently include one or more of boehmite, alumina, silicon dioxide, and zirconium trioxide.

[0131] The materials of the first inorganic particle and the second inorganic particle can be the same or different, and can be chosen to be the same.

[0132] In some embodiments, the separator may further include a third adhesive layer located between the second base film and the negative electrode sheet, and the third adhesive layer includes a third adhesive.

[0133] In some embodiments, the first adhesive, the second adhesive, and the third adhesive may each independently include one or more of thermoplastic polypropylene (PP), polyethylene glycol (PEG), polyvinyl alcohol (PVA), polystyrene (PS), and ethylene propylene diene monomer (EPDM).

[0134] The first adhesive, the second adhesive, and the third adhesive can be of the same type or different types, and can be chosen to be the same.

[0135] In some embodiments, the volume distribution particle size Dv of the first inorganic particles 150 can be 0.2μm-0.5μm, for example, it can be 0.2μm, 0.3μm, 0.4μm, 0.5μm, or any range of the above values.

[0136] In some embodiments, the volume distribution particle size Dv of the second inorganic particles 2 50 can be 0.04μm-0.16μm, for example, it can be 0.04μm, 0.05μm, 0.06μm, 0.07μm, 0.08μm, 0.09μm, 0.10μm, 0.11μm, 0.12μm, 0.13μm, 0.14μm, 0.15μm, 0.16μm, or any range of the above values.

[0137] In this application, the volume distribution particle size Dv of the first inorganic particle is... 1 50 and the volume distribution of the second inorganic particles, particle size Dv 2 The 50 has a well-known meaning in the art, representing the particle size corresponding to a cumulative volume distribution percentage of 50% for inorganic particles, which can be measured using known methods and instruments. For example, it can be measured using a laser particle size analyzer (e.g., Malvern Master Size 3000) with reference to standard GB / T 19077-2016.

[0138] In some embodiments, the thickness of the first adhesive layer can be 1 μm-3 μm, for example, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3.0 μm, or any range of the above values. Optionally, the thickness of the first adhesive layer can be 1.5 μm-2.0 μm.

[0139] In some embodiments, the thickness of the second adhesive layer can be 1 μm-3 μm, for example, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3.0 μm, or any range of the above values. Optionally, the thickness of the second adhesive layer can be 1.5 μm-2.0 μm.

[0140] In some embodiments, the thickness of the third adhesive layer can be 1 μm-3 μm, for example, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3.0 μm, or any range of the above values. Optionally, the thickness of the third adhesive layer can be 1.5 μm-2.0 μm.

[0141] In some embodiments, the thickness of the isolation membrane can be 15μm-65μm, for example, it can be 15μm, 18μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, or any range of the above values.

[0142] [Positive electrode plate]

[0143] In some embodiments, the positive electrode includes a positive current collector and a positive electrode film layer located on at least one side of the positive current collector, the positive electrode film layer including a positive active material.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] Lithium-containing phosphates may include one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and their respective modified compounds.

[0148] 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.

[0149] 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.

[0150] The higher the Ni content in layered lithium-containing transition metal oxides, the higher the energy density of the battery cell.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] In some embodiments, as an example, sodium transition metal oxides may include, but are not limited to:

[0155] Na 1-x Cu h Fe k Mn l M1 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;

[0156] 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, where 0 < z ≤ 0.1;

[0157] 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.

[0158] In some embodiments, as an example, the polyanionic compound may include, but is not limited to:

[0159] 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, and M 3It is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu and Zn, X 1 It is one or more of F, Cl and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0160] Na n M 4 PO4X 2 M 4 It is one or more of Mn, Fe, Co, Ni, Cu and Zn, X 2 It is one or more of F, Cl and Br, where 0 < n ≤ 2;

[0161] Na p M 5 q (SO4)3, where M 5 It is one or more of Mn, Fe, Co, Ni, Cu and Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0162] 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.

[0163] In some embodiments, as an example, Prussian blue compounds may include, but are not limited to:

[0164] A u M 6 v [M 7 (CN)6] w ·xH2O, where A is H + NH4 + M is one or more of alkali metal cations and alkaline earth metal cations. 6 and M 7 Each is independently one or more 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 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 one or more of K-, 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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] [Negative electrode plate]

[0174] In some embodiments, the negative electrode includes a negative current collector.

[0175] In some embodiments, the negative electrode sheet may include a conductive coating located on at least one side of the surface of the negative electrode current collector.

[0176] In some embodiments, the conductive coating may 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.

[0177] In some embodiments, the conductive coating may also include other additives. For example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc.

[0178] 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. 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).

[0179] The negative electrode sheet does not exclude other additional functional layers besides the conductive coating. For example, in some embodiments, the negative electrode sheet may also include a protective layer covering the surface of the conductive coating.

[0180] [Electrolytes]

[0181] A single battery cell includes an electrolyte.

[0182] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0183] 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.

[0184] In some embodiments, the electrolyte includes cations, which may include one or more of lithium ions and sodium ions.

[0185] 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.

[0186] 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.

[0187] As an example, organic solvents may include, but are not limited to, ethylene carbonate (EC), propylene carbonate (PC), butenyl 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.

[0188] 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.

[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 sodium iron pyrophosphate, the conductive agent carbon black (carbon nanotubes), and the binder polyvinylidene fluoride (PVDF) were thoroughly mixed in the solvent N-methylpyrrolidone (NMP) at a weight ratio of 90:2:3 to form a uniform positive electrode slurry. The positive electrode slurry was then coated onto the surface of the positive electrode current collector aluminum foil with a coating weight of 350 mg / 1540 mm². 2 After drying and cold pressing, a positive electrode sheet is obtained.

[0194] Negative electrode sheet

[0195] Carbon nanotubes (CNTs) and sodium carboxymethyl cellulose (CMC-Na) were thoroughly mixed in deionized water at a weight ratio of 1:1 to form an interface modification layer slurry. The interface modification layer slurry was coated on the surface of the copper foil of the negative electrode current collector with a coating thickness of 2 μm. After drying, the negative electrode sheet was obtained.

[0196] Separating membrane

[0197] First inorganic particles and first binder are mixed at a mass ratio of 90:10 to obtain first inorganic slurry; second inorganic particles and second binder are mixed at a mass ratio of 90:10 to obtain second inorganic slurry.

[0198] The first inorganic slurry is sprayed onto one side of the first base film to form a first adhesive layer, and the second inorganic slurry is sprayed onto the other side of the first base film to form a second adhesive layer. After drying, the first composite base film is obtained.

[0199] The second base film is bonded to the composite base film, so that the second base film comes into contact with the first adhesive layer, and the second composite base film is obtained by rolling.

[0200] The third adhesive is sprayed onto the side of the second base film away from the first base film, and after drying, a third adhesive layer is formed, resulting in a release film.

[0201] The specific parameters of the separator are detailed in Table 1.

[0202] electrolyte

[0203] In an argon-filled glove box with a water content of <1ppm, diethylene glycol dimethyl ether and tetrahydrofuran were mixed at a mass ratio of 1:3, sodium hexafluorophosphate (NaPF6) was added, and the mixture was stirred until homogeneous to obtain an electrolyte with a NaPF6 concentration of 1.0 mol / L.

[0204] battery cell

[0205] The positive electrode, negative electrode, and separator are stacked in sequence, with the second adhesive layer located on the positive electrode side and the third adhesive layer located on the negative electrode layer. Electrolyte is then injected to obtain a negative electrode-free battery cell.

[0206] Comparative Example 1

[0207] The preparation method of the battery cell is similar to that in Example 1, except that the parameters of the separator are different. Specifically, it is prepared by the following method:

[0208] Inorganic alumina particles and PEG binder were mixed at a mass ratio of 90:10 to obtain a separator slurry. The separator slurry was uniformly coated on both sides of a polyethylene base film with a thickness of 13 μm and a porosity of 45%. After drying and rolling, a coating was formed with a thickness of 4 μm on one side, thus obtaining the separator film.

[0209] Comparative Examples 2-3

[0210] The preparation method of the battery cell is similar to that in Example 1, except that the parameters of the separator are different. For details of the parameter adjustments, please refer to Table 1.

[0211] Test section

[0212] 1. Cyclic performance

[0213] The battery cell was charged at room temperature at a rate of 0.33C to a voltage of 3.65V, and then discharged at a rate of 0.33C to a voltage of 1.5V. The reversible capacity was measured as C0. This charging and discharging process was repeated until the discharge capacity Cn of the battery cell met the requirement of C0. n / C0≤80%, record the total number of loops; where C n It is the reversible capacity at the nth cycle.

[0214] 2. Expansion force

[0215] A battery cell is clamped between a first clamping plate and a second clamping plate. A KRE sensor is placed between the clamping plate and the battery cell. The battery cell is then charged at a rate of 0.33C at room temperature until the voltage equals 3.65V. The expansion force F1 of the KRE sensor is recorded. Then, the battery cell is discharged at a rate of 0.33C until the voltage equals 1.5V. The expansion force F2 of the KRE sensor is recorded. The difference between F1 and F2 is the expansion force of the battery cell during the charging and discharging process.

[0216] The test results are detailed in Table 2.

[0217] Table 2

[0218] Based on the data in Table 2, this application embodiment adjusts the structural design of the separator to make the side of the separator closer to the negative electrode sheet have higher porosity, which can provide more deposition space for active metals on the negative electrode side, thereby reducing the expansion of the battery cell caused by the increase in the thickness of the negative electrode sheet, and improving the cycle performance of the battery cell.

[0219] Compared to Example 1, Examples 2-6 show that by adjusting the porosity of the second or first base film, the expansion of the battery cell can be further reduced and the cycle performance of the battery cell can be improved. However, excessive porosity may lead to a decrease in the strength of the separator, which is not conducive to the assembly and stretching of the separator.

[0220] Compared to Example 1, Examples 7-10 show that adjusting the thickness of the second or first base film can reduce the expansion of the battery cell and improve its cycle performance. However, excessive thickness of the separator may lead to a decrease in the proportion of active material in the battery cell, affecting the energy density of the battery cell.

[0221] Compared to the examples, Examples 11-14 show that by adjusting the particle size of inorganic particles, the strength of the inorganic coating can be improved, the puncture resistance of the separator can be enhanced, the risk of internal short circuit in the battery cell caused by lithium dendrites puncturing the separator can be reduced, and the cycle performance of the battery cell can be improved.

[0222] 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 negative electrode-free battery cell, comprising a positive electrode, a negative electrode, and a separator, wherein the separator is located between the positive electrode and the negative electrode, and the separator comprises: First base film; The second base film is located between the first base film and the negative electrode sheet; The porosity of the first base film is less than that of the second base film, and the porosity of the second base film is 50%-90%.

2. The anode-free battery cell according to claim 1, wherein, The porosity of the second base film is 70%-80%.

3. The anode-free battery cell according to claim 1 or 2, wherein The thickness h of the second base film satisfies: wherein, is the porosity of the second base film, H is the theoretical deposition thickness of an active metal on the surface of the negative electrode tab, the active metal being lithium or sodium.

4. The anode-free battery cell of claim 3, wherein, The thickness of the second base film is 10μm-50μm.

5. The anode-free battery cell of any one of claims 1-4, wherein, The second base membrane comprises a mesh membrane formed of fibers, the mesh membrane satisfying at least one of the following conditions (1) to (4): (1) The diameter of the fiber is 0.2μm-10μm; (2) The aspect ratio of the fiber is 1000-10000; (3) The tensile strength of the fiber is 1.5g-15g; (4) The pore size of the mesh membrane is 2μm-100μm.

6. The anode-free battery cell of any one of claims 1-5, wherein, The material of the second base film includes one or more of polypropylene, polyethylene, polyamide, and polyethylene terephthalate.

7. The anode-free battery cell of any one of claims 1-6, wherein, The porosity of the first base membrane is 20%-50%.

8. The anode-free battery cell according to claim 7, wherein, The porosity of the first base membrane is 33%-45%.

9. The anode-free battery cell of any one of claims 1-8, wherein, The thickness of the first base film is 5μm-15μm.

10. The anode-free battery cell of claim 9, wherein, The thickness of the first base film is 7μm-12μm.

11. The anode-free battery cell according to any one of claims 1 to 10, wherein, The material of the first base film includes one or more of polyethylene, polypropylene, and polyimide.

12. The anode-free battery cell of any one of claims 1-11, wherein, The separator includes a first adhesive layer located between the first base film and the second base film, and the first adhesive layer includes a first adhesive.

13. The anode-free battery cell of claim 12, wherein, The first adhesive layer further comprises first inorganic particles, the volume distribution particle size Dv 1 50 is 0.2 μm - 0.5 μm.

14. The anode-free battery cell of claim 13, wherein, The mass content of the first inorganic particles in the first adhesive layer can be 85%-95%.

15. The anode-free battery cell of any one of claims 1-14, wherein, The separator includes a second adhesive layer located between the first base film and the positive electrode sheet, and the second adhesive layer includes a second adhesive.

16. The anode-free battery cell of claim 15, wherein, The second adhesive layer includes second inorganic particles, the volume distribution particle size Dv 2 50 is 0.04 μm - 0.16 μm.

17. The anode-free battery cell of claim 16, wherein, The mass content of the second inorganic particles in the second adhesive layer is 85%-95%.

18. The anode-free battery cell of any one of claims 1-17, wherein, The separator includes a third adhesive layer located between the second base film and the negative electrode sheet, and the third adhesive layer includes a third adhesive.

19. The anode-free battery cell of any one of claims 12-18, wherein, The isolation membrane satisfies at least one of the following conditions (1) to (5): (1) The first adhesive, the second adhesive and the third adhesive each independently comprise one or more of thermoplastic polypropylene, polyethylene glycol, polyvinyl alcohol, polystyrene and ethylene propylene diene monomer (EPDM) rubber; (2) The first inorganic particle and the second inorganic particle each independently include one or more of the following: boehmite, alumina, aluminum oxide, silicon dioxide, and zirconium oxide; (3) The thickness of the first adhesive layer is 1μm-3μm; (4) The thickness of the second adhesive layer is 1μm-3μm; (5) The thickness of the third adhesive layer is 1μm-3μm.

20. The anode-free battery cell of any one of claims 1-19, wherein, The thickness of the isolation membrane is 15μm-65μm.

21. A battery device comprising a non-negative electrode battery cell according to any one of claims 1 to 20.

22. An electrical device comprising a single negative electrode-free battery cell according to any one of claims 1 to 20 or a battery device according to claim 21.

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