Battery cell, battery device and power-consuming device

Abstract

Battery cell comprising a cathode foil, a separator film, an anode foil and an electrolyte solution, wherein the cathode foil and the anode foil are arranged in a stacked configuration, the separator film being located between the cathode foil and the anode foil; wherein the cathode foil comprises a main cathode body and a cathode tab section connected to the main cathode body, the ratio of the size of the long side to the size of the short side of the main cathode body being (3 to 8):1; the separator film comprises a base film and an adhesive layer arranged on at least one side of the separator film, the adhesive layer being a continuous layer with a porous structure; wherein the electrolyte solution comprises a first solvent, the first solvent comprising one or more of dimethyl carbonate and linear carboxylic acid esters having the structure shown in formula (1): R1 - (C=O) - O - R2 Formula (1); where R1 and R2 each independently comprise C1 to C5 alkyl or haloalkyl groups.

Description

CROSS-REFERENCE TO RELATED REGISTRATION

[0001] The present application claims priority over Chinese patent application No. 202510831235.3 dated June 20, 2025, entitled “Battery cell and method for its manufacture, battery device, battery device and power-consuming device”, which is hereby incorporated in its entirety by reference. TECHNICAL AREA

[0002] The present application relates to the field of battery technology and in particular to a battery cell and a method for its manufacture, a battery device, a battery assembly and a power-consuming device. STATE OF THE ART

[0003] As the range of applications for secondary batteries has expanded in recent years, secondary batteries are used in several areas, such as energy storage systems like hydropower, thermal power, wind power and solar power plants, as well as in many areas such as power tools, electric bicycles, electric motorcycles, electric vehicles and the like.

[0004] With the significant advances in secondary batteries, the demands on their performance have increased. The search for a battery with high energy density, good cycle life, and low self-discharge is one of the main focuses for experts in this field. CONTENT OF THE PRESENT INVENTION

[0005] The present application is filed in view of the above-mentioned problems and aims to provide a battery cell and a method for its manufacture, a battery device, a battery device and a power-consuming device, the battery cell having a high energy density, good cycle performance and low self-discharge.

[0006] To achieve the above-mentioned objectives, a first aspect of the present application provides a battery cell comprising a cathode foil, a separating film, an anode foil and an electrolyte solution, wherein the cathode foil and the anode foil are provided to be stacked, with the separating film located between the cathode foil and the anode foil;

[0007] wherein the cathode foil comprises a cathode main body and a cathode tab section connected to the cathode main body, wherein the ratio of the size of the long side to the size of the short side of the cathode main body is (3 to 8):1;

[0008] The release film comprises a base film and an adhesive layer arranged on at least one side of the release film, wherein the adhesive layer is a continuous layer with a porous structure;

[0009] wherein the electrolyte solution comprises a first solvent, wherein the first solvent comprises one or more of dimethyl carbonate and linear carboxylic acid esters having the structure shown in formula (1): R1 - (C=O) - O - R2 Formula (1); where R1 and R2 each independently comprise C1 to C5 alkyl or haloalkyl groups.

[0010] By controlling the ratio of the size of the long side to the size of the short side of the cathode main body of the cathode foil to (3 to 8):1, when forming a stacked battery with a cathode foil with such a large length-to-width ratio, the space occupied by the tab section of the battery can be relatively smaller, which benefits the improvement of the energy density of the battery cell;by using one or more of dimethyl carbonate and linear carboxylic acid esters with the structure shown in formula (1) as the first solvent in the electrolyte solution, which has a low viscosity and is advantageous for improving the electrical conductivity of the electrolyte solution, thereby reducing the problem of insufficient wetting of the electrolyte solution in the stacked battery with a large length-to-width ratio of the electrode foil, this enables the individual battery cell to achieve good cycle performance;By providing an adhesive layer on at least one side of the base film of the separator film, this porous and continuous adhesive layer can effectively bond the separator film to the cathode foil and / or the anode foil, thereby reducing the battery's self-discharge caused by misalignment of the cathode and anode foils due to gas formation from low-viscosity solvents during the cycling process. This maintains a low self-discharge rate of the battery cell. In the present application, the structural arrangement of the length-to-width ratio of the electrode foil, the electrolyte solvent, and the separator film, and the coordinated action of these factors, ensures that the battery cell not only exhibits high energy density but also good cycle performance and low self-discharge.

[0011] In each embodiment, the thickness of the single-sided adhesive layer is specified as being between 0.5 µm and 5 µm. This makes it easier to achieve a higher energy density and lower self-discharge for the battery cell.

[0012] In each embodiment, the thickness of the single-sided adhesive layer is specified as being between 1 µm and 4 µm. This makes it easier to achieve a better balance between high energy density and low self-discharge in the battery cell.

[0013] In each embodiment, the adhesive layer material comprises one or more polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymers. This contributes to the adhesive layer exhibiting good bonding performance.

[0014] In each embodiment, the separating film also includes a ceramic coating, the ceramic coating is arranged between the base film and the adhesive layer, the material of the ceramic coating comprises an adhesive and inorganic ceramic particles, this contributes to improving the thermal stability and mechanical strength of the separating film.

[0015] In each embodiment, the ratio of the size of the long side to the size of the short side of the cathode main body is (4 to 6):1. This allows the battery cell to achieve a better balance between high energy density, good cycle performance, and low self-discharge.

[0016] In each embodiment, the linear carboxylic acid ester comprises one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate. This helps to improve the problem of insufficient wetting of the electrolyte solution in stacked batteries with a large length-to-width ratio of the electrode foil, thereby enabling the battery cell to achieve both high energy density and good cycle performance.

[0017] In each embodiment, the mass fraction of the first solvent is between 10% and 60%, based on the mass of the electrolyte solution. This contributes to the electrolyte solution having a suitable viscosity and high electrical conductivity, which reduces the problem of insufficient wetting of the electrolyte solution in stacked batteries with a large length-to-width ratio of the electrode foil and allows the battery cell to better meet cycle performance requirements.

[0018] In each embodiment, the mass fraction of the first solvent is specified as being between 15% and 35%, based on the mass of the electrolyte solution. This allows the battery cell to achieve a better balance between high energy density, good cycle performance, and low self-discharge.

[0019] In each embodiment, the dimethyl carbonate and the linear carboxylic acid ester are designed to have an electrical conductivity of 10 mS / cm to 16 mS / cm at room temperature. This contributes to improving the cycle performance of the battery cell.

[0020] In each embodiment, the electrolyte solution also comprises a lithium salt, wherein the lithium salt comprises one or more lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide; wherein the total mass fraction of lithium hexafluorophosphate and / or lithium bis(fluorosulfonyl)imide is 12% to 18%, based on the mass of the electrolyte solution. This contributes to improving the electrical conductivity of the electrolyte solution and increasing the cycle performance and dynamic properties of the battery cell.

[0021] In each embodiment, the mass ratio of lithium hexafluorophosphate to lithium bis(fluorosulfonyl)imide is (1.2 to 3:1). This helps to improve the electrical conductivity of the electrolyte solution, solve the problem of insufficient wetting of the electrolyte solution in stacked batteries with a large length-to-width ratio of the electrode foil, and improve the cycle performance and dynamic properties of the battery cell.

[0022] In each embodiment, the electrolyte solution further comprises an additive, wherein the additive includes one or more of vinylene carbonate, fluoroethylene carbonate, and 1,3-propanesulfonate lactone; the mass fraction of the additive, based on the mass of the electrolyte solution, is less than or equal to 5%. This contributes to a better balance of cycle performance and dynamic properties in the battery cell.

[0023] In each embodiment, the mass fraction of the additive is specified as 0.5% to 3%, based on the mass of the electrolyte solution. This helps to better balance the cycle performance and dynamic properties of the battery cell.

[0024] In each embodiment, the battery cell also comprises a softpack outer shell. The cathode foil, separator film, anode foil, and electrolyte solution are arranged within the softpack outer shell, which has a thickness of 70 µm to 200 µm. This contributes to improving the energy density of the battery cell and can also reduce the problem of expansion of the softpack outer shell due to gas formation during the cycling process of low-viscosity solvents.

[0025] In each embodiment, the anode foil comprises an anode main body and an anode tab section connected to the anode main body, the anode main body comprising an anode current collector and an anode film layer, the anode film layer comprising a first anode film layer and a second anode film layer arranged on the anode current collector, the first anode film layer being located between the anode current collector and the second anode film layer;

[0026] wherein the first anode film layer and the second anode film layer each comprise graphite, wherein the average value of the longest diameter of the graphite in the first anode film layer is 7 µm to 18 µm, wherein the average value of the longest diameter of the graphite in the second anode film layer is 6 µm to 10 µm, and wherein the average value of the longest diameter of the graphite in the first anode film layer is larger than the average value of the longest diameter of the graphite in the second anode film layer. In this way, battery cells can achieve a better balance between fast-charging performance and energy density.

[0027] In each embodiment, the graphite in the first anode film layer and the second anode film layer each independently comprises a graphite particle body and a coating layer of amorphous carbon on the surface of the graphite particle body, the thickness of which is 100 nm to 500 nm. This will contribute to further improving the electrical conductivity of the graphite particles and increasing the dynamic properties of the battery.

[0028] In each embodiment, the thickness of the second anode film layer is provided to be 30% to 70% of the total thickness of the anode foil.

[0029] In each embodiment, the graphitization degree of the graphite in the first anode film layer and the second anode film layer is independently 90% to 94%. This contributes to improving the gram capacity of the anode and the energy density of the battery.

[0030] In each embodiment, the cathode tab section is connected to the short side of the cathode main body, and the anode tab section is connected to the short side of the anode main body. This contributes to improving the energy density of the battery cell.

[0031] In each embodiment, the one-sided coating area density of the anode film layer is 0.13 g / 1540.25 mm². 2 up to 0.22 g / 1540.25 mm 2 This will result in battery cells achieving a better balance between fast charging performance and energy density.

[0032] In each embodiment, the one-sided coating area density of the anode film layer is 0.14g / 1540.25 mm². 2 up to 0.195g / 1540.25 mm 2 This will result in battery cells achieving a better balance between fast charging performance and energy density.

[0033] In each embodiment, the ratio of the thickness of the anode foil to the thickness of the anode current collector is (15 to 25):1.

[0034] In each embodiment, the anode foil density is specified as being between 1.3 g / cc and 1.52 g / cc. This will allow battery cells to achieve a better balance between fast-charging performance and energy density.

[0035] In each embodiment, the anode foil density is specified as being between 1.35 g / cc and 1.50 g / cc. This will allow battery cells to achieve a better balance between fast-charging performance and energy density.

[0036] In each embodiment, the main cathode body comprises a cathode current collector and a cathode film layer, the cathode film layer being arranged on the cathode current collector and comprising lithium-containing transition metal phosphate, wherein the lithium-containing transition metal phosphate comprises one or more aluminum elements with a mass fraction of 200 ppm to 2500 ppm, vanadium elements with a mass fraction of 300 ppm to 2000 ppm, and titanium elements with a mass fraction of 1500 ppm to 3500 ppm. This can improve the fast-charging performance, cycle performance, and / or energy density of the battery cell.

[0037] In each embodiment, the main cathode body also comprises a lower coating, the lower coating being located between the cathode current collector and the cathode film layer, the lower coating comprising a conductive material, and the thickness of the lower coating being 0.5 µm to 3 µm. This contributes to reducing the internal resistance of the battery and improving its dynamic properties.

[0038] In each embodiment, the one-sided coating area density of the cathode film layer is 0.33g / 1540.25 mm². 2 up to 0.45g / 1540.25 mm 2 This will result in battery cells achieving a better balance between fast charging performance and energy density.

[0039] In each embodiment, the one-sided coating area density of the cathode film layer is 0.30g / 1540.25 mm². 2up to 0.40g / 1540.25 mm 2 This will result in battery cells achieving a better balance between fast charging performance and energy density.

[0040] In each embodiment, the ratio of the thickness of the cathode foil to the thickness of the cathode current collector is (10 to 20):1.

[0041] In each embodiment, the density of the cathode foil is specified as being between 2.3 g / cc and 2.65 g / cc. This will allow battery cells to achieve a better balance between fast-charging performance and energy density.

[0042] In each embodiment, the density of the cathode foil is specified as being between 2.35 g / cc and 2.6 g / cc. This will allow battery cells to achieve a better balance between fast-charging performance and energy density.

[0043] According to a second aspect of the present application, a method for manufacturing a battery cell according to the first aspect of the present application is provided, comprising the following steps:

[0044] Stacking the cathode foil, separator film, and anode foil one after the other to form an electrode assembly; inserting the electrode assembly into the outer packaging to form a dry cell battery, and filling the dry cell battery with electrolyte solution;

[0045] wherein the cathode foil comprises a cathode main body and a cathode tab section connected to the cathode main body, wherein the ratio of the size of the long side to the size of the short side of the cathode main body is (3 to 8):1;

[0046] The release film comprises a base film and an adhesive layer arranged on at least one side of the release film, wherein the adhesive layer is a continuous layer with a porous structure;

[0047] wherein the electrolyte solution comprises a first solvent, wherein the first solvent comprises one or more of dimethyl carbonate and linear carboxylic acid esters having the structure shown in formula (1): R1 - (C=O) - O - R2 Formula (1); where R1 and R2 each independently comprise C1 to C5 alkyl or haloalkyl groups.

[0048] In this way, the structural arrangement of the length-width ratio of the electrode foil, the electrolyte solvent and the adhesive layer in the separating film, and the coordinated action of these factors, ensures that the manufactured battery cell not only has a high energy density, but also good cycle performance and low self-discharge.

[0049] In each embodiment, the method for producing the separating film comprises the following steps: dissolving an adhesive and a pore-forming agent in an organic solvent to obtain an adhesive solution; applying the adhesive solution to the base film and removing the pore-forming agent after drying to form an adhesive layer on the base film. This allows for the production of a porous, continuous adhesive layer, which is advantageous for reducing the battery's self-discharge.

[0050] According to a third aspect of the present application, a battery device is provided comprising one or more of the battery cells according to the first aspect of the present application and the battery cell produced according to the method for producing a battery cell according to the second aspect of the present application.

[0051] According to a fourth aspect of the present application, a power-consuming device is provided which comprises one or more of the battery cell according to the first aspect of the present application, the battery cell which is produced according to the method for producing a battery cell according to the second aspect of the present application, and the battery device according to the third aspect of the present application.

[0052] Details of one or more embodiments of the present application are set out in the following drawings and description. Further features, objectives and advantages of the present application will become apparent from the description, the drawings and the claims. BRIEF DESCRIPTION OF THE DRAWING

[0053] For a better description and illustration of the embodiments or examples contained in this application, reference may be made to one or more of the attached drawings. Additional details or examples used to describe the attached drawings should not be considered as limiting the scope of the disclosed application, any of the embodiments or examples currently described, or the best forms of the application as currently understood. Furthermore, the same reference numerals are used in all attached drawings for the same components. In the figures: Fig. Figure 1 shows a schematic structural representation of the cathode foil in a battery cell according to an embodiment of the present application; Fig. Figure 2 shows a schematic structural representation of the anode foil in a battery cell according to an embodiment of the present application; Fig. Figure 3 schematically shows a structural representation of the separating film in a battery cell according to an embodiment of the present application; Fig. Figure 4 is a schematic representation of a battery device serving as the power-consuming device of a power supply, according to an embodiment of the present application. Explanation of reference symbols:

[0054] 1. Cathode foil; 11. Cathode main body; 12. Cathode tab section; 2. Separator film; 21. Base film; 22. Adhesive layer; 23. Ceramic coating; 3. Anode foil; 31. Anode main body; 32. Anode tab section; 6. Current-consuming device. DETAILED DESCRIPTION

[0055] The following sections describe in detail embodiments of the battery cell and methods for its manufacture, the battery device, and the current-consuming device of the present application with reference to the accompanying drawings. However, an unnecessarily detailed description can be omitted. For example, a detailed description of known facts and a repeated description of essentially the same structure can be avoided. This is to prevent the following description from becoming unnecessarily long and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following description serve to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0056] The “range” disclosed in the present application can be defined in terms of a lower limit and an upper limit. A specific range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the respective range. The range thus defined can include or exclude the end values; each end value can be included or excluded independently and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also considered.If, in addition, minimum range values ​​of 1 and 2 and maximum range values ​​of 3, 4, and 5 are listed, all of the following ranges are anticipated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In the present application, unless otherwise specified, the range "a to b" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the range "0 to 5" means that all real numbers between "0 to 5" are listed in this article, and "0 to 5" is simply an abbreviation for these combinations of numbers. Furthermore, if a parameter is expressed as an integer ≥ 2, this is equivalent to listing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or the like.For example, if a parameter is described as an integer from the range "2 to 10", this corresponds to listing the integers 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[0057] In this application, unless otherwise specified, the terms “several” or “different” are used and refer to a quantity greater than or equal to 2. For example, “one or more” means one or two or more.

[0058] Unless otherwise stated, all embodiments and optional embodiments of the present application may be combined to form a new technical solution.

[0059] The reference herein to an “embodiment” means that a particular feature, structure, or property described in connection with the embodiment may be included in at least one embodiment or embodiment of the present application. The occurrence of this phrase at various points in the description does not necessarily all refer to the same embodiment, nor is it an independent or alternative embodiment that mutually excludes other embodiments. It is expressly and implicitly clear to those skilled in the art that the embodiments described herein may be combined with other embodiments. The term “elaboration” is used in this article in a similar sense.

[0060] It is understood by those skilled in the art that the sequence of steps in methods according to different embodiments or exemplary embodiments does not imply a strict execution order and does not represent a restriction of the implementation process; the detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present application may be carried out sequentially or in any order, but preferably sequentially. For example, if a method comprises steps (a) and (b), this means that the method may comprise steps (a) and (b) carried out sequentially, or steps (b) and (a) carried out sequentially.For example, the procedure mentioned may also include step (c), which means that step (c) can be inserted into the procedure in any order; for example, the procedure may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), and so on.

[0061] In the present application, open technical features or solutions described by terms such as "containing," "including," or "comprising" do not exclude further, unlisted elements unless otherwise specified. This can be interpreted as providing both a closed feature or solution consisting of the listed members and an open feature or solution that includes additional members beyond those listed. For example, A includes members a1, a2, and a3. Unless otherwise specified, A may or may not include further members. This can be understood as describing both the feature or solution "A consists of a1, a2, and a3" and the feature or solution "A includes not only a1, a2, and a3, but also further members." In this application, A (e.g.,B), unless otherwise stated, that B is a non-restrictive example of A, and it is understood that A is not restricted to B.

[0062] In the present application, "alternative," "optional," and "option" mean that something is optional, i.e., that there are two parallel options to choose from: "present" or "not present." If a technical solution offers multiple "options," each "option" is independent unless otherwise specified and there are no contradictions or mutual restrictions.

[0063] With the significant advancements in secondary batteries, the demands on their performance have increased. Finding a battery with high energy density, good cycle life, and low self-discharge is a key focus for experts in this field.

[0064] Based on this and with reference to the Fig. 1, Fig. 2 and Fig.3 The first aspect of the present application provides a battery cell, the battery cell is a stacked battery, the battery cell comprises a cathode foil 1, a separating film 2, an anode foil 3 and an electrolyte solution, the cathode foil 1 and the anode foil 3 are arranged stacked, and the separating film 2 is located between the cathode foil 1 and the anode foil 3.

[0065] The cathode foil 1 comprises a main cathode body section 11 and a cathode tab section 12, which is connected to the main cathode body section 11, the ratio of the size of the long side (as in Fig. 1, denoted by d1) to the size of the short side (as in Fig.1 denoted by d2) of the cathode main body section 11 is (3 to 8):1; the separating film 2 comprises a base film 21 and an adhesive layer 22 arranged on at least one side of the base film 21, the adhesive layer 22 being a continuous layer with a porous structure; the electrolyte solution comprises a first solvent, the first solvent comprising one or more of dimethyl carbonate and linear carboxylic acid esters having the structure shown in formula (1); R1 - (C=O) - O - R2 Formula (1);

[0066] In formula (1), R1 and R2 each independently comprise C1 to C5 alkyl or haloalkyl groups.

[0067] In the present application, the main body of the cathode 11 is the main body of the cathode film 1; this area serves primarily for the application of the cathode film layer, and an insulating coating may be arranged at its edge. The cathode tab section 12 denotes the conductive area extending from the main body of the cathode 11 and serving for connection to an external circuit; an insulating coating may be arranged at the base of the cathode tab section 12. The long side of the main body of the cathode 11 is the side with the greater length in the plane in which the main body of the cathode 11 is located, and the short side of the main body of the cathode 11 is the side with the shorter length in the plane in which the main body of the cathode 11 is located. The dimensions of the long side and the short side of the main body of the cathode 11 can be measured directly after disassembling the stacked battery.

[0068] The morphology of the adhesive layer 22 can be observed using a scanning electron microscope (SEM). Without restriction, the battery cell can be fully discharged and then disassembled in a glove box to remove the electrode assembly, and the cathode foil 1, the anode foil 3, and the separator film 2 can be detached. The separator film 2 in the center of the battery is selected, and a 5 mm × 5 mm piece of the separator film 2 is cut off with scissors as a test sample. The sample is placed in anhydrous ethanol and gently shaken. After removal, the sample is dried to remove any residual electrolyte solution and electrode foil residue from the sample surface. The dried separator film 2 is placed on a glass slide, and the morphology of the adhesive layer 22 on the separator film 2 is observed using a scanning electron microscope.

[0069] In the present application, the type and content of organic components in the electrolyte solution can be determined using equipment and methods known in this field. For example, the organic components in the electrolyte solution can be analyzed qualitatively and quantitatively by gas chromatography with reference to GB / T9722-2006 "General rules for the gas chromatography of chemical reagents". In one embodiment of the present application, a freshly prepared electrolyte solution can be used as a sample, the free electrolyte solution of a fresh battery can be used as a sample, or a battery that is completely discharged (discharged to the lower limit of the reverse voltage, so that the state of charge of the battery is approximately 0% SOC) can be reverse disassembled and the free electrolyte solution obtained from the battery can be taken as a sample, which can be determined by an ion chromatography analysis method.

[0070] In one embodiment of the present application, the type and content of the inorganic component / lithium salt concentration in the electrolyte solution have meanings known in this field and can be determined using equipment and methods known in this field; for example, the concentration of the inorganic component / lithium salt concentration in the electrolyte solution can be analyzed qualitatively or quantitatively using the ion chromatography analysis method with reference to the standard JY / T020-1996 "General rules for ion chromatography analysis methods".In one embodiment of the present application, a freshly prepared electrolyte solution can be taken as a sample, the free electrolyte solution of a fresh battery can be taken as a sample, or a battery that is completely discharged (discharged to the lower limit of the reverse voltage, so that the state of charge of the battery is approximately 0% SOC) is disassembled backwards and the free electrolyte solution obtained from the battery can be taken as a sample, which are detected by an ion chromatography analysis method.

[0071] In the embodiments of the present application, after quantitative and qualitative determination of each component in the electrolyte solution, the composition of the solvent in the electrolyte solution and the mass fraction of each solvent can be determined.

[0072] In the battery cell described above, by controlling the ratio of the size of the long side to the size of the short side of the main cathode body 11 of the cathode foil 1 to (3 to 8):1 when forming a stacked battery with a cathode foil 1 with such a large length-to-width ratio, the space occupied by the tab section of the battery can be relatively smaller, which benefits the energy density of the battery cell. However, if the length-to-width ratio of the cathode foil 1 of the stacked battery is large, the path that the electrolyte solution can travel longitudinally in the battery is longer.which can easily lead to insufficient wetting of the electrolyte solution in some areas of the electrode foil and impair the battery's cycle performance. In the present application, the use of one or more dimethyl carbonate and linear carboxylic acid esters with the structure shown in formula (1) as the first solvent in the electrolyte solution, which has a low viscosity and is advantageous for improving the electrical conductivity of the electrolyte solution, reduces the problem of insufficient wetting of the electrolyte solution in the stacked battery with a large length-to-width ratio of the electrode foil. This allows the individual battery cell to achieve good cycle performance. The aforementioned low-viscosity first solvent tends to gasify during the cycling process, which can lead to misalignment of the cathode and anode foils.In particular, in stacked battery cells, since the electrode foil arrangement is formed by stacking several independent electrode foils, compared to wound battery cells, which are created by winding a single-piece electrode foil, the probability of misalignment between the electrode foils in the stacked battery cell is higher in the lateral direction of the battery due to gas formation in the electrolyte solution. This leads to self-discharge of the battery due to misalignment of the cathode foil and the anode foil. In the present application, by providing an adhesive layer 22 on at least one side of the base film 21 of the separator film 2, this porous and continuous adhesive layer 22 can effectively bond the separator film 2 to the cathode foil 1 and / or the anode foil 3, thereby reducing the self-discharge of the battery.which is caused by misalignment of the cathode foil and the anode foil due to gas formation from low-viscosity solvent during the cycling process, thereby maintaining a low self-discharge of the battery cell. In the present application, the structural arrangement of the length-to-width ratio of the electrode foil, the electrolyte solvent, and the separating film 2, and the coordinated action of these factors, ensures that the battery cell not only has a high energy density but also good cycle performance and low self-discharge.

[0073] It is understandable that the ratio of the size of the long side to the size of the short side of the cathode main body may be 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.8:1, 5:1, 5.2:1, 5.5:1, 5.8:1, 6:1, 6.2:1, 6.5:1, 6.8:1, 7:1, 7.2:1, 7.5:1, 7.8:1, 8:1 or any ratio within the range formed by any two of the above ratios.

[0074] It should be noted that the adhesive layer 22 is a porous continuous layer, meaning that it contains numerous interconnected or unconnected pores linked together by a solid framework, thus forming a continuous three-dimensional layer structure. Compared to discontinuous adhesive layers, which consist of several isolated island structures, the porous continuous adhesive layer 22 can bond the separator film 2 more effectively to the cathode foil 1 and / or the anode foil 3, thereby making the connection between the cathode foil 1, the separator film 2, and the anode foil 3 more robust.During the battery cycle process, it helps to maintain the interfacial contact between the cathode foil and the anode foil and the separating film 2 and to reduce the self-discharge of the battery caused by misalignment of the cathode foil and the anode foil due to gas formation by low-viscosity solvent during the cycle process.

[0075] Particularly in stacked batteries whose active cathode material contains lithium-containing transition metal phosphate (such as lithium iron phosphate), the lithium-containing transition metal phosphate particles exhibit significant rebound during the battery's cycling process. Furthermore, gas is generated during cycling due to the low-viscosity solvent, which can easily lead to the detachment of the cathode and anode foils, as well as to slippage and misalignment of the cathode and anode foils relative to the separating film 2, thus causing self-discharge of the battery. By providing a porous, continuous adhesive layer 22 on the separating film 2, the self-discharge of this type of battery can be effectively reduced.

[0076] In some embodiments, the thickness of the adhesive layer 22 on one side is 0.5 µm to 5 µm. Controlling the thickness of the adhesive layer 22 on one side within the aforementioned range contributes to giving the battery cell a higher energy density and lower self-discharge. Understandably, the one-sided thickness of the adhesive layer 22 can be 0.5 µm, 0.8 µm, 1 µm, 1.2 µm, 1.5 µm, 1.8 µm, 2 µm, 2.2 µm, 2.5 µm, 2.8 µm, 3 µm, 3.2 µm, 3.5 µm, 3.8 µm, 4 µm, 4.2 µm, 4.5 µm, 4.8 µm, 5 µm or any value within the range formed by any two of the above values, but is not limited to it.

[0077] The thickness of the adhesive layer 22 can be determined by cutting the release film 2 in the thickness direction and directly measuring the cross-section of the release film 2 using a scanning electron microscope. Alternatively, the thickness values ​​of the adhesive layer 22 can be checked at several (e.g., 10) locations at regular intervals in the scanning electron microscope image of the cross-section of the release film 2, and then the average value can be determined.

[0078] Alternatively, the thickness of the adhesive layer on one side can be 22 1 µm to 4 µm. This will make it easier to achieve a better balance between high energy density and low self-discharge in the battery cell.

[0079] In some embodiments, the material of the adhesive layer 22 comprises one or more polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP). The use of the aforementioned organic polymer as an adhesive for the adhesive layer 22 results in good adhesive performance.

[0080] In some embodiments, the release film 2 further comprises a ceramic coating 23 arranged between the base film 21 and the adhesive layer 22. The material of the ceramic coating 23 comprises an adhesive and inorganic ceramic particles. Applying the aforementioned ceramic coating 23 between the base film 21 and the adhesive layer 22 improves the thermal stability and mechanical strength of the release film 2. Understandably, the adhesive in the ceramic coating 23 can be a commonly used adhesive such as PVDF, and the inorganic ceramic particles can consist of, for example, aluminum oxide, zirconium dioxide, titanium oxide, boehmite, or the like, but are not limited to these materials.

[0081] In some embodiments, the ratio of the size of the long side to the size of the short side of the cathode main body 11 (4 to 6) is 1. Controlling the ratio of the size of the long side to the size of the short side of the cathode main body 11 within the above-mentioned range is advantageous to allow the battery cell a better balance between higher energy density, better cycle performance and lower self-discharge.

[0082] In some embodiments, the linear carboxylic acid ester comprises one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate. The aforementioned linear carboxylic acid ester exhibits a low viscosity, which facilitates wetting with the electrolyte solution and reduces the problem of insufficient electrolyte wetting in the stacked battery with a large length-to-width ratio of the electrode foil. This contributes to the battery cell achieving both high energy density and good cycle performance.

[0083] In some embodiments, the mass fraction of the first solvent is 10% to 60%, based on the mass of the electrolyte solution. Controlling the mass fraction of the first solvent in the electrolyte solution within the aforementioned range helps ensure that the electrolyte solution has a suitable viscosity and high electrical conductivity. This reduces the problem of insufficient wetting of the electrolyte solution in stacked batteries with a large length-to-width ratio of the electrode foil and allows the battery cell to better meet cycle performance requirements.

[0084] Understandably, the mass fraction of the first solvent can be 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, or any value within the range formed by any two of the above values, but is not limited to these. The electrolyte solution can contain dimethyl carbonate but no linear carboxylic ester, it can contain linear carboxylic ester but no dimethyl carbonate, or it can contain both dimethyl carbonate and linear carboxylic ester.

[0085] Furthermore, in some embodiments, the mass fraction of the first solvent is 15% to 35%, based on the mass of the electrolyte solution. By controlling the mass fraction of the first solvent in the electrolyte solution within the aforementioned range, the battery cell can achieve a better balance between higher energy density, better cycle performance, and lower self-discharge.

[0086] In some embodiments, the electrolyte solution exhibits an electrical conductivity of 9.5 mS / cm to 20 mS / cm at room temperature. Adding dimethyl carbonate and / or linear carboxylic esters as a first solvent to the electrolyte solution can help achieve a higher electrical conductivity. Controlling the electrical conductivity of the electrolyte solution within the aforementioned range is advantageous for improving the cycle performance of the battery cell.

[0087] It is understood that the electrical conductivity of the electrolyte solution at normal temperature will be 9.5 mS / cm, 10 mS / cm, 10.5 mS / cm, 11 mS / cm, 11.5 mS / cm, 12 mS / cm, 12.5 mS / cm, 13 mS / cm, 13.5 mS / cm, 14 mS / cm, 14.5 mS / cm, 15 mS / cm, 15.5 mS / cm, 16 mS / cm, 16.5 mS / cm, 17 mS / cm, 17.5 mS / cm, 18 mS / cm, 18.5 mS / cm, 19 mS / cm, 19.5 mS / cm, 20 mS / cm, or any value within the range formed by any two of the above values, but not limited thereto. The normal temperature is usually between 20°C and 25°C.

[0088] In some specific examples, the electrolyte solution exhibits an electrical conductivity of 10 mS / cm to 16 mS / cm at normal temperature.

[0089] In some embodiments, the electrolyte solution further comprises a lithium salt consisting of one or more of lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI); wherein the sum of the mass fractions of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide is 12% to 18%, based on the mass of the electrolyte solution.

[0090] By combining lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide as lithium salts and controlling the sum of the mass fractions of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide within the above-mentioned range, the electrical conductivity of the electrolyte solution is improved and the cycle performance and dynamic properties of the battery cell are increased.

[0091] Understandably, the total mass fraction of lithium hexafluorophosphate and / or lithium bis(fluorosulfonyl)imide in the electrolyte solution can be 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18% or any value within the range formed by any two of the above values, but is not limited to that.

[0092] In some embodiments, the mass ratio of lithium hexafluorophosphate to lithium bis(fluorosulfonyl)imide is (1.2 to 3:1). Controlling the mass ratio of lithium hexafluorophosphate to lithium bis(fluorosulfonyl)imide within the above-mentioned range is advantageous for improving the electrical conductivity of the electrolyte solution, reducing the problem of insufficient wetting of the electrolyte solution in stacked batteries with a large length-to-width ratio of the electrode foil, and improving the cycle performance and dynamic properties of the battery cell.Understandably, the mass ratio of lithium hexafluorophosphate to lithium bis(fluorosulfonyl)imide can be 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1 or any ratio within the range formed by any two of the above ratios, but is not limited to it.

[0093] In some embodiments, the electrolyte solution further comprises an additive consisting of one or more vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS). The addition of the above-mentioned additive to the electrolyte solution optimizes the solid electrolyte interface (SEI) film, helping the battery cell achieve a better balance between cycle performance and dynamic properties.

[0094] In some embodiments, the mass fraction of the additive, based on the mass of the electrolyte solution, is less than or equal to 5%. Excessive use of additive can increase the impedance of the battery cell; however, in the stacked battery with a large length-to-width ratio of the electrode foil of the present application, the use of the aforementioned additive, which constitutes less than 5% of the mass fraction of the electrolyte solution, is more advantageous in order to provide the battery cell with a better balance between cycle performance and dynamic characteristics.

[0095] Understandably, the mass fraction of the additive in the electrolyte solution can be 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, or any value within the range formed by any two of the above values, but not limited to them.

[0096] Furthermore, in some specific examples, the mass fraction of the additive ranges from 0.5% to 3%, based on the mass of the electrolyte solution. This helps to better balance the cycle performance and dynamic properties of the battery cell.

[0097] In some embodiments, the battery cell further comprises a softpack outer shell in which the cathode foil 1, the separating film 2, the anode foil 3, and the electrolyte solution are arranged, the thickness of the softpack outer shell being between 70 µm and 200 µm. That is to say, the battery cell of the present application can be a softpack battery cell, wherein the thickness of the softpack outer shell is controlled within the aforementioned range, which has a positive effect on the energy density of the battery cell; it can also give the outer shell greater strength and reduce the problem of expansion of the softpack outer shell due to gas formation during the cycling process of low-viscosity solvent.

[0098] The thickness of the softpack outer shell can understandably be 70µm, 80µm, 90µm, 100µm, 110µm, 120µm, 130µm, 140µm, 150µm, 160µm, 170µm, 180µm, 190µm, 200µm or any value within the range formed by any two of the above values, but is not limited to that.

[0099] In some specific examples, plastic can be used as a material for the softpack outer shell; in further training, non-limiting examples of plastic can include one or more of polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.

[0100] In some embodiments, the anode foil 3 comprises an anode main body 31 and an anode tab section 32 connected to this anode main body 31. The anode main body 31 comprises an anode current collector and an anode film layer. The anode film layer comprises a first anode film layer and a second anode film layer arranged on the anode current collector. The first anode film layer is located between the anode current collector and the second anode film layer. The first anode film layer and the second anode film layer each comprise graphite, wherein the average value of the longest diameter of the graphite in the first anode film layer is 7 µm to 18 µm, and the average value of the longest diameter of the graphite in the second anode film layer is 6 µm to 10 µm.and wherein the average value of the longest diameter of the graphite in the first anode film layer is greater than the average value of the longest diameter of the graphite in the second anode film layer.

[0101] In the present application, the anode main body 31 is the main body of the anode foil 3; this area serves mainly for applying the anode film layer; the anode tab section 32 designates the conductive area extending from the anode main body 31 and serving for connection to an external circuit.

[0102] By using a structure with an upper and a lower layer for the anode film layer, the average value of the longest diameter of the graphite in the first anode film layer and the second anode film layer is kept within the aforementioned range, with the average value of the longest diameter of the graphite in the first anode film layer being larger than the average value of the longest diameter of the graphite in the second anode film layer; the upper second anode film layer consists of graphite with a smaller particle size, which allows more lithium ions to be incorporated into the spaces, thus facilitating the incorporation of lithium ions from the electrolyte solution into the anode film layer, which has a positive effect on the fast charging performance of the battery cell;The use of graphite with a larger particle size in the lower first anode film layer is advantageous for improving the compaction density of the anode film layer and enables the battery cell to achieve a better balance between fast charging performance and energy density.

[0103] It is understood that the average value of the longest diameter of the graphite in the first anode film layer may be 7 µm, 8 µm, 9 µm, 10 µm, 11 µm, 12 µm, 13 µm, 14 µm, 15 µm, 16 µm, 17 µm, 18 µm or any value within the range formed by any two of the above values; wherein the average value of the longest diameter of the graphite in the second anode film layer may be 6 µm, 7 µm, 8 µm, 9 µm, 10 µm or any value within the range formed by any two of the above values.

[0104] The test procedure for determining the average longest diameter is as follows: In the scanning electron microscope image, 500 graphite particles are randomly selected, the largest diameter of each graphite particle is measured, and the average value is calculated. The largest diameter of the graphite particle refers to the maximum length dimension that can be measured in all possible orientations of the particle in the SEM image above.

[0105] Furthermore, the ratio of the thickness of the second anode film layer to the total thickness of the anode foil 3 can be between 30% and 70%. The total thickness of the anode foil 3 refers to the thickness of the main anode body 31 within the anode foil 3.

[0106] In some embodiments, the graphite in the first anode film layer and the second anode film layer each independently comprises a graphite particle body and a coating layer of amorphous carbon arranged on the surface of the graphite particle body, the thickness of which is 100 nm to 500 nm. That is, the graphite in the first anode film layer can comprise a coating layer of amorphous carbon, the graphite in the second anode film layer can comprise a coating layer of amorphous carbon, or both the graphite in the first anode film layer and in the second anode film layer can comprise a coating layer of amorphous carbon.By applying a coating layer of amorphous carbon of the aforementioned thickness to the surface of graphite, the electrical conductivity of the graphite particles can be further improved, thereby increasing the dynamic properties of the battery.

[0107] The thickness of the coating layer of amorphous carbon on the surface of the graphite particle body can understandably be 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, 220 nm, 250 nm, 280 nm, 300 nm, 320 nm, 350 nm, 380 nm, 400 nm, 420 nm, 450 nm, 480 nm, 500 nm or any value within the range formed by any two of the above values, but is not limited to that.

[0108] Furthermore, the graphite in the first and second anode film layers can each be either artificial graphite or a mixture of artificial and natural graphite, independently of each other.

[0109] In some embodiments, the degree of graphitization of the graphite in the first anode film layer and the second anode film layer is independently 90% to 94%. The use of graphite with the aforementioned degree of graphitization promotes the intercalation of lithium ions, which has a positive effect on the gram capacity of the anode and the energy density of the battery.

[0110] In some embodiments, the cathode tab section 12 is connected to the short side of the cathode main body 11, and the anode tab section 32 is connected to the short side of the anode main body 31. Thus, the cathode tab section 12 is located on a side face of the short side of the cathode main body 11, and the anode tab section 32 is located on a side face of the short side of the anode main body 31, which, compared to arranging the tab section on the long side, is more conducive to improving the energy density of the battery cell.

[0111] In some embodiments, the one-sided coating area density of the anode film layer is 0.13 g / 1540.25 mm². 2 up to 0.22 g / 1540.25 mm 2Controlling the one-sided coating area density of the anode film layer within the aforementioned range is advantageous for achieving a better balance between fast-charging performance and energy density in the battery cell. For example, the one-sided coating area density of the anode film layer can be 0.13 g / 1540.25 mm². 2 , 0.14g / 1540.25mm 2 , 0.15g / 1540.25mm 2 , 0.16g / 1540.25mm 2 , 0.17g / 1540.25mm 2 , 0.18g / 1540.25mm 2 , 0.19g / 1540.25mm 2 , 0.20g / 1540.25mm 2 , 0.21g / 1540.25mm 2 , 0.22g / 1540.25mm 2 or any value within the range formed by any two of the above values, but not limited to that range.

[0112] Optionally, the one-sided coating area density of the anode film layer is 0.14 g / 1540.25 mm². 2 up to 0.195 g / 1540.25 mm 2 .

[0113] In some embodiments, the anode foil density at 0% state of charge is 1.3 g / cc to 1.52 g / cc. Controlling the anode foil density within the aforementioned range is advantageous in order to provide the battery cell with a better balance between fast-charging performance and energy density. The compression density of the anode foil can understandably be 1.3g / cc, 1.31g / cc, 1.32g / cc, 1.33g / cc, 1.34g / cc, 1.35g / cc, 1.36g / cc, 1.37g / cc, 1.38g / cc, 1.39g / cc, 1.4g / cc, 1.41g / cc, 1.42g / cc, 1.43g / cc, 1.44g / cc, 1.45g / cc, 1.46g / cc, 1.47g / cc, 1.48g / cc, 1.49g / cc, 1.50g / cc, 1.51g / cc, 1.52g / cc, or any value within the range formed by any two of the above values, but is not limited to them.

[0114] Furthermore, the compaction density of the anode foil can optionally be 1.35 g / cc to 1.50 g / cc.

[0115] In some embodiments, the main cathode body 11 comprises a cathode current collector and a cathode film layer, the cathode film layer is arranged on the cathode current collector, the cathode film layer comprises lithium-containing transition metal phosphate, and this lithium-containing transition metal phosphate comprises one or more of aluminum element with a mass fraction of 200 ppm to 2500 ppm, vanadium element with a mass fraction of 300 ppm to 2000 ppm mass fraction and titanium element with a mass fraction of 1500 ppm to 3500 ppm.

[0116] The addition of the above-mentioned amount of aluminum element to lithium-containing transition metal phosphate improves the electronic conductivity of the active cathode material and increases the fast-charging performance and cycle performance of the battery cell; the addition of the above-mentioned amount of vanadium element to lithium-containing transition metal phosphate is advantageous for improving the specific capacity of the active cathode material, which in turn is advantageous for improving the energy density of the battery cell; the addition of the above-mentioned amount of titanium element to lithium-containing transition metal phosphate is advantageous for improving the crystal structure stability of the active cathode material and thus increases the cycle performance of the battery cell.

[0117] The content of aluminum element in lithium-containing transition metal phosphate can understandably be 200 ppm, 500 ppm, 800 ppm, 1000 ppm, 1200 ppm, 1500 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2500 ppm or any value within the range formed by any two of the above values, but is not limited thereto; The vanadium element content in lithium-containing transition metal phosphate may be 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1100 ppm, 1200 ppm, 1300 ppm, 1400 ppm, 1500 ppm, 1600 ppm, 1700 ppm, 1800 ppm, 1900 ppm, 2000 ppm or any value within the range formed by any two of the above values, but is not limited thereto;The titanium content in lithium-containing transition metal phosphate can be 1500 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2500 ppm, 2800 ppm, 3000 ppm, 3200 ppm, 3500 ppm, or any value within the range formed by any two of the above values, but is not limited to that.

[0118] In some embodiments, the main cathode body 11 also includes a lower coating. This lower coating is located between the cathode current collector and the cathode film layer. The lower coating comprises a conductive material and has a thickness of 0.5 µm to 3 µm. In a stacked battery with a large length-to-width ratio of the electrode foil, the path traveled by the electrons from the main cathode body 11 to the cathode tab section 12 is relatively long, resulting in a relatively high internal resistance (DCR) of the battery cell. By incorporating the aforementioned lower coating between the cathode current collector and the cathode film layer, the internal resistance of the battery is reduced, and the battery's dynamic properties are improved.

[0119] The thickness of the lower coating can understandably be 0.5 µm, 0.6 µm, 0.7 µm, 0.8 µm, 0.9 µm, 1.0 µm, 1.2 µm, 1.5 µm, 1.8 µm, 2.0 µm, 2.2 µm, 2.5 µm, 2.8 µm, 3 µm or any value within the range formed by any two of the above values, but is not limited to that.

[0120] In some embodiments, the one-sided coating area density of the cathode film layer is 0.33 g / 1540.25 mm². 2 up to 0.45g / 1540.25 mm 2 Controlling the one-sided coating area density of the cathode film layer within the aforementioned range is advantageous for achieving a better balance between fast-charging performance and energy density in the battery cell. Understandably, the one-sided coating area density of the cathode film layer can be 0.33 g / 1540.25 mm². 2 , 0.34g / 1540.25mm 2 , 0.35g / 1540.25mm 2 , 0.36g / 1540.25mm 2 , 0.37g / 1540.25mm2 , 0.38g / 1540.25mm 2 , 0.39g / 1540.25mm 2 , 0.40g / 1540.25mm 2 , 0.41g / 1540.25mm 2 , 0.42g / 1540.25mm 2 , 0.43g / 1540.25mm 2 , 0.44g / 1540.25mm 2 , 0.45g / 1540.25mm 2 or any value within the range formed by any two of the above values, but not limited to that range.

[0121] Optionally, the one-sided coating area density of the cathode film layer is 0.30g / 1540.25 mm². 2 up to 0.40g / 1540.25 mm 2 .

[0122] In some embodiments, the density of the cathode foil at 0% state of charge is 2.3 g / cc to 2.65 g / cc. Controlling the density of the cathode foil within the aforementioned range is advantageous in order to provide the battery cell with a better balance between fast-charging performance and energy density. The density of the cathode foil can understandably be 2.3g / cc, 2.32g / cc, 2.35g / cc, 2.38g / cc, 2.4g / cc, 2.42g / cc, 2.45g / cc, 2.48g / cc, 2.5g / cc, 2.52g / cc, 2.55g / cc, 2.58g / cc, 2.6g / cc, 2.62g / cc, 2.65g / cc or any value within the range formed by any two of the above values, but is not limited to it.

[0123] Furthermore, the compression density of the anode foil can optionally be set from 2.35g / cc to 2.6g / cc.

[0124] In some embodiments, the ratio of the thickness of the cathode foil 1 to the thickness of the cathode current collector is (10 to 20):1, and the ratio of the thickness of the anode foil 3 to the thickness of the anode current collector is (15 to 25):1. Therefore, the thickness of the cathode current collector in the cathode foil 1 and the thickness of the anode current collector in the anode foil 3 are relatively small, which further improves the energy density of the battery cell. The thickness of the cathode foil 1 refers to the thickness of the main cathode body 11 in the cathode foil 1; the total thickness of the anode foil 3 refers to the thickness of the main anode body 31 in the anode foil 3.

[0125] A second aspect of the present application concerns a method for manufacturing the above-mentioned battery cell, which comprises the following steps:

[0126] The cathode foil 1, the separating film 2 and the anode foil 3 are stacked one on top of the other to form an electrode assembly; the electrode assembly is inserted into the outer packaging to form a dry battery, and the electrolyte solution is poured into the dry battery.

[0127] The cathode foil 1 comprises a cathode main body section 11 and a cathode tab section 12, which is connected to the cathode main body section 11, the ratio of the size of the long side to the size of the short side of the cathode main body section 11 being (3 to 8):1;

[0128] The separating film 2 comprises a base film 21 and an adhesive layer 22, which is arranged on at least one side of the base film 21, wherein the adhesive layer 22 is a continuous layer with a porous structure;

[0129] wherein the electrolyte solution comprises a first solvent, wherein the first solvent comprises one or more of dimethyl carbonate and linear carboxylic acid esters having the structure shown in formula (1): R1 - (C=O) - O - R2 Formula (1); where R1 and R2 each independently comprise C1 to C5 alkyl or haloalkyl groups.

[0130] In the above-described method for manufacturing the battery cell, the structural arrangement of the length-width ratio of the electrode foil, the electrolyte solvent and the adhesive layer 22 in the separating film 2 and the coordinated action of these factors ensure that the manufactured battery cell not only has a high energy density, but also good cycle performance and low self-discharge.

[0131] In some embodiments, the method for producing the release film 2 comprises the following steps: dissolving an adhesive and a pore-forming agent in an organic solvent to obtain an adhesive solution; applying the adhesive solution to the base film 21 and removing the pore-forming agent after drying to form an adhesive layer 22 on the base film 21.

[0132] The manufacturing process described above enables the production and formation of a porous continuous adhesive layer 22 on the base film 21, which is advantageous for improving the bond between the separating film 2 and the cathode foil 1 and the anode foil 3 after hot pressing of the electrode assembly and for reducing the self-discharge of the battery caused by misalignment of the cathode foil and the anode foil due to gas formation by low-viscosity solvent during the cycling process.

[0133] In some specific examples, the adhesive consists of one or more of PVDF and PVDF-HFP; polyethylene glycol (PEG) is used as a pore former, and N-methylpyrrolidone (NMP) is used as an organic solvent.

[0134] A third aspect of the present application provides a battery device comprising one or more battery cells of the first aspect of the present application and of the battery cell produced according to the manufacturing method of the second aspect of the present application.

[0135] Several battery cells are connected together and arranged in a specific sequence and can be placed directly into a housing to assemble a battery device. Alternatively, one or more of the battery cells can be combined to form a battery module, then several battery modules are connected together to form a whole, and finally the entire battery module is housed in a casing to form the battery device.

[0136] In some specific examples, the battery device is a battery module that can comprise one or more of the aforementioned battery cells; the exact number can be selected by a person skilled in the art depending on the application and capacity of the battery module. Within the battery module, several battery cells can be arranged sequentially along the module's longitudinal axis. Of course, the arrangement can also be any other. The multiple battery cells can be additionally secured by fastening elements.

[0137] Optionally, the battery module can also include an outer shell with a receiving space, and the multiple battery cells are contained within the receiving space.

[0138] In some specific examples, the battery device is a battery pack composed of several of the above-mentioned battery modules; the number of battery modules contained in the battery pack can be one or more, and the exact number can be chosen by the expert depending on the application and capacity of the battery pack.

[0139] The battery pack can comprise a battery box and several battery modules arranged within the battery box. The battery box consists of an upper and a lower housing; the upper housing can be placed on top of the lower housing, thus forming a sealed compartment for the battery modules. The arrangement of the multiple battery modules within the battery box is arbitrary.

[0140] The fourth aspect of the present application provides a power-consuming device, the power-consuming device comprising one or more of the battery cell according to the first aspect of the present application, the battery cell produced according to the method for producing a battery cell according to the second aspect of the present application, and the battery device according to the third aspect.

[0141] The battery cell and the power-consuming device of the present application are described below with reference to the attached drawings.

[0142] Unless otherwise stated, references to battery components, material types or ingredients refer to both lithium-ion batteries and sodium-ion batteries.

[0143] In one embodiment of the present application, a battery cell is provided.

[0144] A typical battery cell comprises a cathode foil, an anode foil, an electrolyte solution, and a separating film. During the charging and discharging process, active ions are inserted and removed between the cathode and anode foils. The electrolyte solution conducts ions between the cathode and anode foils. The separating film is placed between the cathode and anode foils, primarily to prevent a short circuit between the cathode and anode while allowing the passage of ions.

[0145] The cathode foil comprises a cathode current collector and a cathode film layer arranged on at least one surface of the cathode current collector.

[0146] As a non-restrictive example, the cathode current collector has two surfaces facing each other in its thickness direction, and the cathode film layer is provided on any one or both of the two facing surfaces of the cathode current collector.

[0147] In some embodiments, the cathode current collector can consist of a metal foil or a composite current collector. For example, aluminum foil can be used as the metal foil. The composite current collector can comprise a base layer of polymer material and a metal layer formed on at least one surface of the polymer base layer. The composite current collector can be produced by depositing the metal material onto a polymer material substrate. Examples of metal materials in the cathode current collector include, but are not limited to, one or more of aluminum, aluminum alloy, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloy. Examples of polymer material substrates in the cathode current collector include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and similar substrates.

[0148] In some embodiments, the active cathode material may comprise an active cathode material for the battery that is known in this field.

[0149] As non-limiting examples, the active cathode material of the lithium-ion battery may comprise one or more of the following materials: lithium-containing phosphate with an olivine structure, lithium-containing transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials suitable for use as battery active cathode materials may also be employed. These active cathode materials may be used alone or in combination with two or more. Examples of lithium-containing transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, and their modified compounds.Non-limiting examples of lithium-containing phosphate with an olivine structure may include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate-carbon composites, lithium manganese phosphate, lithium manganese phosphate-carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate-carbon composites. Non-limiting examples of lithium cobalt oxide may include LiCoO₂; non-limiting examples of lithium nickel oxide may include LiNiO₂; non-limiting examples of lithium manganese oxide may include LiMnO₂, LiMn₂O₄, and the like; non-limiting examples of lithium nickel cobalt manganese oxide may include LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also abbreviated as NCM) 333 ), LiNi0 ,5 Co 0,2 Mn 0,3 O2 (also abbreviated as NCM) 523 ),LiNi 0,5 Co 0,25 Mn 0,25 O2 (also abbreviated as NCM) 211 ),LiNi 0,6 Co 0,2 Mn0,2 O2 (also abbreviated as NCM) 622 ),LiNi 0,8 Co 0,1 Mn 0,1 O2 (also abbreviated as NCM) 811 ) and the like; non-limiting examples of lithium nickel cobalt aluminum oxide include LiNi 0,85 Co 0,1 Al 0,05 O2 include.

[0150] Understandably, lithium (Li) is extracted and consumed during the charging and discharging process of a battery, and the Li content in the cathode foil varies as the battery is discharged to different states. Unless otherwise specified, the Li content in the examples of cathode material listed in this application refers to the initial state of the material. When the cathode material is applied to the cathode foil of a battery system and subjected to the charge and discharge cycle, the Li content of the cathode material in the electrode foil typically changes. The Li content can be measured in moles, but is not limited to this. Regarding the statement "the Li content refers to the initial state of the material," the initial state of the material refers to the state before the material is added to the cathode slurry.It is understood that new materials obtained through appropriate modification based on the listed cathode material also fall within the scope of the cathode material, and the above-mentioned suitable modification refers to an acceptable modification method for the cathode material, and a non-restrictive example of this is coating modification.

[0151] In the list of cathode materials in the present application, the oxygen (O) content is only a theoretical value. The release of oxygen from the crystal lattice changes the molar content of oxygen, and the actual O content fluctuates. The O content can be measured in molar amounts, but is not limited to this.

[0152] As non-limiting examples, the active cathode material of the sodium-ion battery may comprise one or more of the following materials: one or more sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. However, the present application is not limited to these materials, and other conventionally known materials suitable for use as the active cathode material of a sodium-ion battery may also be used.

[0153] As an optional technical solution in the present application, the polyanionic compound can be a class of compounds containing sodium ions, transition metal ions and tetrahedral (YO4) n- exhibit anionic units. The transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be one or more of P, S, and / or Si; n represents the valence state of (YO4) n- .

[0154] Polyanionic compound can also be a class of compounds containing sodium ions, transition metal ions, tetrahedral (YO4) n- They contain anionic units and halide anions. The transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be one or more of P, S, and Si, and n represents the valence state of (YO4)n-; halogens can be one or more of F, Cl, and Br.

[0155] Polyanionic compounds can also be a class of compounds containing sodium ions, tetrahedral (YO4) n- anionic units, polyhedral units (ZO) y ) m+ and optionally contain halide anions. Y can be one or more of P, S, and Si, and n represents the valence state of (YO4)n-; Z represents a transition metal, which can be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; m represents the valence state of (ZO y )m+ Halogens can be one or more of F, Cl, and Br.

[0156] The polyanionic compounds are, for example, one or more of NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated NVP), Na4Fe3(PO4)2 (P2O7), NaM'PO4F (M' is one or more of V, Fe, Mn and Ni) and Na3(VO3)3 y ) 2(PO4) 2F 3-2y (0≤y≤1).

[0157] Prussian blue compounds can be a class of compounds containing sodium ions, transition metal ions, and cyanide ions (CN⁻). - The transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Prussian blue compounds include, for example, Na₂. a Me b Me' c (CN) 6, where Me and Me' are each independently one or more of Ni, Cu, Fe, Mn, Co and Zn, where 0 <a≤2, 0<b<1, 0<c<1.

[0158] The weight fraction of the active cathode material in the cathode film layer is 80 to 100 percent by weight, based on the total weight of the cathode film layer.

[0159] In some embodiments, the cathode film layer optionally includes an adhesive. Examples of such adhesives include, but are not limited to, one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin. The weight fraction of the adhesive in the cathode film layer is 0 to 20 percent by weight, based on the total weight of the cathode film layer.

[0160] In some embodiments, the cathode film layer optionally includes a conductive material. Examples of such materials include, but are not limited to, one or more of superconducting carbon, carbon black, carbon black, Ketjen carbon black, carbon dot, carbon nanotube, graphene, and carbon nanofiber. The weight fraction of the conductive material in the cathode film layer ranges from 0 to 20 percent by weight, based on the total weight of the cathode film layer.

[0161] In some embodiments, it is provided that the cathode foil can be produced in the following way: the above-mentioned components for producing the cathode foil, for example the active cathode material, the conductive agent, the adhesive and all other components, are dispersed in a solvent (e.g. N-methylpyrrolidone) to form a cathode slurry; the cathode slurry is applied to both sides of the cathode current collector and, after drying, cold-pressed by a cold roller and formed into a cathode foil.

[0162] The anode foil comprises an anode current collector and a negative anode film layer arranged on at least one surface of the anode current collector, wherein the anode film layer comprises an active anode material.

[0163] As non-limiting examples, the anode current collector has two surfaces facing each other in the thickness direction, and the anode film layer is provided on one or both of the two facing surfaces of the anode current collector.

[0164] In some embodiments, the anode current collector can consist of a metal foil or a composite current collector. For example, copper foil can be used as the metal foil. The composite current collector can comprise a base layer of polymer material and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be produced by depositing the metal material onto a polymer material substrate. Examples of the metal material in the anode current collector can include, but are not limited to, one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. Examples of the polymer material substrate in the anode current collector can include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and the like.

[0165] In some embodiments, the active anode material may be an active anode material known in this field for use in the battery.

[0166] As non-limiting examples, the active anode material of the lithium-ion battery may comprise one or more of the following materials: synthetic graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like. The silicon-based material may comprise one or more of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material may comprise one or more of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials suitable for use as battery active anode materials may also be employed. These active anode materials may be used alone or in combination with one or more of them.

[0167] As non-limiting examples, the active anode material of a sodium-ion battery typically consists of a hard carbon material, a two-dimensional metal carbide, or a nitride. Hard carbon material is typically preferred as the active anode material of a sodium-ion secondary battery.

[0168] In some embodiments, the anode film layer optionally includes an adhesive. The adhesive may comprise one or more of the following: styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0169] In some embodiments, the anode film layer optionally includes a conductive material. This conductive material can comprise one or more of the following: superconducting carbon, carbon black, carbon black, Ketjen carbon black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0170] In some embodiments, the anode film layer may optionally include other additives, such as a thickening agent (e.g. sodium carboxymethylcellulose (CMC-Na)).

[0171] In some embodiments, the anode foil can be produced by the following method: Dispersing the aforementioned components for the production of the anode foil, such as the active anode material, the conductive agent, the adhesive, and all other components, in a solvent (a non-limiting example of the solvent is deionized water) to form an anode slurry; applying the anode slurry to the surface of at least one side of the anode current collector, and after drying, cold pressing, and other processes, the anode foil can be obtained. The surface of the anode current collector coated with the anode slurry can be a single surface of the anode current collector or two surfaces of the anode current collector.

[0172] The electrolyte solution has the function of conducting ions between the cathode foil and the anode foil.

[0173] In some embodiments, the electrolyte solution comprises an electrolyte salt and a solvent.

[0174] In some embodiments, the electrolyte salt of the lithium-ion battery comprises lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI); it may also comprise one or more of lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobisoxalatophosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP).

[0175] In some embodiments, the solvent comprises one or more of dimethyl carbonate (DMC) and linear carboxylic acid esters with the structure shown in formula (1); R1 - (C=O) - O - R2 formula (1); wherein R1 and R2 each independently comprise C1 to C5 alkyl or haloalkyl groups. It may also comprise one or more of fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), 1,4-butyrolactone (GBL), cyclopentane sulfone (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0176] In some embodiments, the battery cell also includes a separating film. The separating film comprises a base film and an adhesive layer arranged on at least one side of the base film, the adhesive layer being a continuous layer with a porous structure.

[0177] In some embodiments, it is provided that an electrode arrangement is produced from the cathode foil, the anode foil and the separating film by a lamination process.

[0178] In some embodiments, the battery cell may include an outer packaging. The outer packaging can be used to package the electrode assembly and the electrolyte.

[0179] In some embodiments, the outer packaging of the battery cell can be a soft pack, for example, a bag-like soft pack. Plastic can be used as the material for the soft pack; in a further development, non-limiting examples of plastics can include one or more of polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.

[0180] In the present application, unless otherwise specified, the term "battery cell" refers to the basic unit that enables the conversion of chemical energy to electrical energy. It generally comprises at least a cathode foil, an anode foil, and an electrolyte solution. During the charging and discharging process of the battery, active ions are inserted and removed between the cathode foil and the anode foil. The electrolyte solution conducts active ions between the cathode foil and the anode foil.

[0181] Furthermore, the present application also provides a power-consuming device comprising at least one battery cell or battery device provided in the present application. The battery cell and battery device can be used either as the power supply for the power-consuming device or as the energy storage unit of the power-consuming device. The power-consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, and the like), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, and the like), electric trains, ships and satellites, energy storage systems, and the like.

[0182] Depending on the usage requirements, a battery cell or a battery device can be selected as the power-consuming device.

[0183] Fig. Figure 4 shows an example of a power-consuming device 6. The power-consuming device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like. To meet the power-consuming device's requirements for high battery performance and energy density, a battery-powered device can be used.

[0184] As another example, the device could be a mobile phone, a tablet computer, a laptop computer, or the like. The device typically needs to be lightweight and thin, and a battery cell can be used as the power source.

[0185] To clarify the technical problems, solutions, and positive effects addressed by this application, it is described in more detail below with reference to the exemplary embodiments and accompanying drawings. Obviously, the described embodiments are only some of the embodiments of this application, not all of them. The following description of at least one exemplary embodiment serves only for illustration and is in no way intended to limit the scope of this application and its application. All other embodiments that a person skilled in the art in this field could derive from the embodiments in this application without any creative activity are within the scope of protection of this application.

[0186] If no specific techniques or conditions are indicated in the examples, the techniques or conditions described in the relevant literature or the product instructions must be followed. Any reagents or instruments used without manufacturer information are exclusively commercially available products. Example 1:(1) Production of the cathode foil

[0187] The active cathode material, lithium iron phosphate (LFP), the conductive material, Super P, and the adhesive, PVDF, are mixed in a mass ratio of 97:1:2. N-methylpyrrolidone is added as a solvent, and the mixture is stirred homogeneously to obtain a cathode slurry. Aluminum foil serves as the cathode current collector, which comprises a main cathode body and a cathode tab section connected to the main body. The cathode tab section is connected to the short side of the main cathode body.

[0188] A primer slurry containing PVDF and electrically conductive carbon is applied to the surfaces of both sides of the main body of the cathode current collector. After curing, a 1 µm thick base coat forms, with a mass ratio of PVDF to electrically conductive carbon in the primer paste of 1:5. The prepared cathode slurry is then evenly applied to this base coat on both sides of the main body of the cathode and subsequently dried, cold-pressed, and slotted to produce the cathode foil.

[0189] The ratio of the size of the long side to the size of the short side of the cathode foil's main body is 5:1. The compaction density of the cathode foil is 2.5 g / cc, and the one-sided coating area density is 0.4 g / 1540.25 mm². 2 . (2) Preparation of the anode foil

[0190] Synthetic graphite, conductive agent Super P, thickening agent sodium carboxymethylcellulose, and adhesive styrene-butadiene rubber are mixed in a mass ratio of 96:1:1.2:1.8. Deionized water is then added as a solvent, and the mixture is stirred uniformly to obtain the first anode slurry. The average maximum diameter of the synthetic graphite is 12 µm. The synthetic graphite comprises a graphite particle body and a 200 nm thick coating layer of amorphous carbon arranged on the surface of the graphite particle body. The degree of graphitization of the synthetic graphite is 92%.

[0191] Copper foil serves as the anode current collector. The anode current collector comprises an anode main body and an anode tab section connected to this main body. The anode tab section is connected to the short side of the main body. The first anode slurry prepared above is applied evenly to the surfaces of both sides of the main body, dried, and cold-pressed to obtain the first anode film layer. The one-sided coating density of the first anode film layer is 0.1 g / 1540.25 mm². 2 .

[0192] Synthetic graphite, the conductive agent Super P, the thickening agent sodium carboxymethylcellulose, and the adhesive styrene-butadiene rubber are mixed in a mass ratio of 96:1:1.2:1.8. Deionized water is then added as a solvent, and the mixture is stirred uniformly to obtain the second anode slurry. The average diameter of the synthetic graphite particles is 8 µm. The synthetic graphite comprises a graphite particle body and a 200 nm thick coating layer of amorphous carbon arranged on the surface of the graphite particle body. The degree of graphitization of the synthetic graphite is 92%.

[0193] The second anode slurry prepared above is applied evenly to the first anode film layer on both sides of the anode body, dried, and cold-pressed to obtain the second anode film layer; the anode foil is obtained after cutting. The one-sided coating density of the second anode film layer is 0.1 g / 1540.25 mm². 2 The total one-sided coating area density of the anode film layer is 0.2 g / 1540.25 mm². 2 The compaction density of the anode foil is 1.42 g / cc. (3) Release film

[0194] Polyvinylidene fluoride is dissolved in N-methylpyrrolidone, stirred thoroughly, and then polyethylene glycol is added as a pore-forming agent. The mixture is stirred thoroughly to obtain an adhesive layer solution. The mass fraction of polyvinylidene fluoride and polyethylene glycol is 20% and 15%, respectively, of the total mass of the adhesive layer solution.

[0195] The aforementioned adhesive solution is applied to both sides of a polyethylene base film coated with ceramic layers on both sides. After pre-evaporation at 80 °C and drying at 110 °C, it is immersed in deionized water to dissolve polyethylene glycol, creating a release film with a porous, continuous adhesive layer on both sides. The polyethylene base film has a thickness of 7 µm, the ceramic layer has a thickness of 2 µm on one side, and the adhesive layer has a thickness of 1.5 µm on one side. The adhesive in the ceramic coating consists of polyvinylidene fluoride, and the inorganic ceramic particles are made of aluminum oxide. (4) Electrolyte solution

[0196] In an argon atmosphere glovebox with a water content of <10 ppm, dimethyl carbonate, ethylene carbonate, and methyl acetate are mixed to obtain an organic solvent, and then the dry lithium salts LiPF6 and LiFSI are added. Fluoroethylene carbonate at a mass fraction of 1% is added to the above solution to obtain an electrolyte solution. In the electrolyte solution, the total mass fraction of dimethyl carbonate and methyl acetate is 50%, and the volume ratio of dimethyl carbonate to methyl acetate is 1:1; the sum of the mass fractions of LiPF6 and LiFSI is 18%, and the mass ratio of LiPF6 to LiFSI is 2:1. The electrolyte solution has an electrical conductivity of 15 mS / cm at 25°C. (5) Battery installation

[0197] The prepared cathode foil, separator film, and anode foil are stacked sequentially, with the separator film positioned between the cathode and anode foils to provide insulation. Hot pressing bonds the adhesive layer on the separator film to the cathode and anode foils, creating a stacked, bare battery core. This stacked core is embedded in a 100 µm thick polypropylene softpack outer shell, dried, and then filled with the electrolyte solution. After vacuum sealing, resting, forming, and adjustment, a lithium battery cell is obtained. Example 2:

[0198] The present embodiment is essentially identical to embodiment 1, with the following exception: in step (1) by adjusting the length of the cathode foil the ratio of the size of the long side to the size of the short side of the cathode main body of the cathode foil is set to 3:1, while the short side of the cathode main body remains unchanged. Example 3:

[0199] The present embodiment is essentially identical to embodiment 1, with the following exception: in step (1) by adjusting the length of the cathode foil the ratio of the size of the long side to the size of the short side of the cathode main body of the cathode foil is set to 8:1, while the short side of the cathode main body remains unchanged. Example 4:

[0200] The present embodiment is essentially identical to embodiment 1, except that in step (3) the one-sided thickness of the adhesive layer is 0.5 µm. Example 5:

[0201] The present embodiment is essentially identical to embodiment 1, except that in step (3) the one-sided thickness of the adhesive layer is 2.5 µm. Example 6:

[0202] The present embodiment is essentially identical to embodiment 1, with the following exception: in step (4), ethylene carbonate, methyl acetate, and ethyl acetate are mixed to form an organic solvent, and the dry lithium salts LiPF6 and LiFSI are added; fluoroethylene carbonate is added to the above solution at a mass fraction of 0.3% to obtain an electrolyte solution. The total mass fraction of methyl acetate and ethyl acetate in the electrolyte solution is 20%, and the volume ratio of methyl acetate to ethyl acetate is 1:1; the sum of the mass fractions of LiPF6 and LiFSI is 12%, and the mass ratio of LiPF6 to LiFSI is 1.2:1. The electrolyte solution has an electrical conductivity of 10 mS / cm at 25°C. Example 7:

[0203] The present embodiment is essentially identical to embodiment 1, with the following exception: in step (2) by adjusting the type of artificial graphite in the first anode slurry and the second anode slurry, the average value of the longest diameter of the artificial graphite in the first anode film layer is set to 18 µm, wherein the average value of the longest diameter of the artificial graphite in the second anode film layer is 10 µm. Example 8:

[0204] The present embodiment is essentially identical to embodiment 1, with the following exception: in step (2) the average value of the longest diameter of the artificial graphite in the first anode slurry is 8 µm; the average value of the longest diameter of the artificial graphite in the second anode slurry is 6 µm. Comparative example 1:

[0205] The comparative example is essentially identical to embodiment 1, with the following exception: in step (3), water is used instead of N-methylpyrrolidone as the solvent for the adhesive layer solution, and no polyvinyl alcohol is added to the adhesive layer solution. The resulting adhesive layer is a discontinuous adhesive layer consisting of several adhesive particles formed as isolated island structures. Comparative example 2:

[0206] The comparative example is essentially identical to embodiment 1, with the following exception: in step (1) by adjusting the length of the cathode foil the ratio of the size of the long side to the size of the short side of the cathode main body of the cathode foil is set to 10:1, while the short side of the cathode main body remains unchanged. Comparative example 3:

[0207] The comparative example is essentially identical to embodiment 1, with the following exception: In step (4) ethylene carbonate and propylene carbonate are mixed in a volume ratio of 1:1 to obtain an organic solvent. Test procedure: (1) Energy density test

[0208] The battery cell is charged at 25 °C at 0.33 C to 3.65 V and then charged at a constant voltage of 3.65 V to 0.05 C; left to stand for 5 minutes; discharged at 0.33 C to 2 V, the total discharged capacity C0 of the battery cell and the total discharge energy E0 are recorded in Wh; The length, width, and thickness of each battery cell are measured, and the volume is calculated and denoted by V, where the unit is L; The volume energy density of the battery cell = E0 / V, unit: Wh / L. (2) Cyclic performance test

[0209] First step: the battery cell is charged at 25 °C at 0.33 C to 3.65 V and then charged at a constant voltage of 3.65 V to 0.05 C; left to stand for 5 minutes; discharged at 0.33 C to 2 V, the capacity at this point is noted as C0 (in this step the initial capacity is measured in practice);

[0210] Second step: the battery is charged to 3.45 V at 0.5C0 and to 3.65 V at 0.33C0; left to stand for 10 minutes; discharged at 1C0 to 2V, then discharged at 0.33C to 2V until the capacity drops to less than or equal to 80% of the initial capacity, and the number of cycles is recorded at this point. (3) Testing the battery's self-discharge performance

[0211] The battery cell is left at room temperature for 1 hour, and its initial open-circuit voltage (OCV) is measured with a 6.5-digit digital multimeter and recorded as OCV1. After this test, the battery cell is left at 45°C for 120 hours, then at room temperature for 1 hour, and the open-circuit voltage is measured again, recorded as OCV2, and the self-discharge rate is calculated. The formula for calculating the self-discharge rate is: (OCV2-OCV1) / 120. 10 battery cells are measured and the average value is determined. (4) Testing the coating area density of the film layer

[0212] The coating area density is tested using the following method: Fifteen electrode foils and fifteen current collectors (from the same production batch as the current collectors used for the electrode foil) with a size of 1540.25 mm² 2Samples are punched out, their mass is measured, and the average value is determined. The average mass of the electrode foil is M1 (in g), and the average mass of the current collector is M2 (in g); if the film layer is applied to both sides of the current collector, the one-sided coating area density is (M1-M2) / 2S. (5) Compaction density test for the electrode foil

[0213] The battery cell with 0% state of charge (SOC) is disassembled to remove the electrode foil and cut it into small discs with an area of ​​1540.25 mm². 2 to punch out, the weight M and thickness L of the small discs are measured; another layer of electrode foils is taken, the remaining empty current collector foil is removed from the membrane layer of the surface to also cut these into small discs with 1540.25 mm 2To punch out the mass M0 of the empty current collector film, the density PD is PD = (M-M0) / 1.54025 / (L- L0), where L0 is the thickness of the current collector film. (6) Test for the average value of the longest diameter of the graphite

[0214] In the scanning electron microscope (SEM) image of the anode film layer, 500 graphite particles are randomly selected, the largest diameter of each graphite particle is measured, and the average value is calculated. The largest diameter of the graphite particle refers to the maximum length dimension that can be measured in all possible orientations of the particle in the SEM image above.

[0215] The parameters and performance data of the battery cells in the above-mentioned embodiments and comparison examples are shown in Table 1. In Table 1, “ / ” means non-existence. Table 1 registration Length-to-width ratio of the cathode Average value of the longest diameter (µm) of the graphite in the first anode film layer Average value of the longest diameter (µm) of the graphite in the second anode film layer Total mass fraction (%) of dimethyl carbonate and linear carboxylic acid ester in the electrolyte solution Total weight fraction (%) and mass ratio of LiPF6 and LiFSI in the electrolyte solution One-sided adhesive layer thickness (µm) Morphology of the adhesive layer Active cathode material Energy density (Wh / L) Number of cycles (rounds) Self-discharge rate (mV / h) Example 1 5:1 12 8 50 18 1,5 porous continuous layer LFP 405 3500 0,125 Example 2 3:1 12 8 50 18 1,5 porous continuous layer LFP 398 3513 0,125 Example 3 8:1 12 8 50 18 1,5 porous continuous layer LFP 412 3427 0,125 Example 4 5:1 12 8 50 18 0,5 porous continuous layer LFP 411 3428 0,145 Example 5 5:1 12 8 50 18 2,5 porous continuous layer LFP 384 3505 0,110 Example 6 5:1 12 8 20 12 1,5 porous continuous layer LFP 405 3385 0,125 Example 7 5:1 18 10 50 18 1,5 porous continuous layer LFP 396 3512 0,125 Example 8 5:1 8 6 50 18 1,5 porous continuous layer LFP 403 3475 0,125 Comparative example 1 5:1 12 8 50 18 1,5 island-like discontinuous layer LFP 405 2956 0,138 Comparative example 2 10:1 12 8 50 18 1,5 porous continuous layer LFP 425 2870 0,125 Comparative example 3 5:1 12 8 / 18 1,5 porous continuous layer LFP 405 2753 0,125

[0216] As can be seen from Table 1, the battery cell of the embodiments of the present application exhibits a high energy density, good cycle performance, and low self-discharge. In comparison to embodiment 1, comparative example 1 uses water instead of N-methylpyrrolidone as the solvent for the adhesive layer solution, and no polyvinyl alcohol is added to the adhesive layer solution. Since the resulting adhesive layer is an island-like discontinuous layer, the adhesion between the separator film and the cathode foil as well as the anode foil is low, leading to poor cycle performance and high self-discharge of the battery cell.When comparing example 2 with embodiment 1, the ratio of the size of the long side to the size of the short side of the cathode main body of the cathode foil is too large, which increases the energy density of the battery cell but significantly reduces the cycle life. When comparing example 3 with embodiment 1, neither dimethyl carbonate nor linear carboxylic acid esters with the structure described in formula (1) are used in the electrolyte solvent, which significantly reduces the cycle life of its battery cell.

[0217] The above description of the respective embodiments aims to highlight the differences between the individual embodiments; their identical or similar aspects may relate to one another. To maintain brevity, these differences are not elaborated upon further in this document.

[0218] It should be noted that the present application is not limited to the embodiments mentioned above. The embodiments mentioned above are merely examples, and all embodiments that exhibit essentially the same structure and effects as the technical idea within the technical solution of the present application are all included within the technical scope of the present application. Furthermore, other embodiments in which various modifications conceivable by a person skilled in the art are added to the embodiments, and some components of the embodiments are combined to form the other embodiments, are also included within the scope of the present application without departing from the core of the present application. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] CN 202510831235.3

[0001]

Claims

[1] Battery cell comprising a cathode foil, a separator film, an anode foil and an electrolyte solution, wherein the cathode foil and the anode foil are arranged stacked, the separator film being located between the cathode foil and the anode foil; wherein the cathode foil comprises a main cathode body and a cathode tab section connected to the main cathode body, the ratio of the size of the long side to the size of the short side of the main cathode body being (3 to 8):1; the separator film comprises a base film and an adhesive layer arranged on at least one side of the separator film, the adhesive layer being a continuous layer with a porous structure; wherein the electrolyte solution comprises a first solvent, the first solvent comprising one or more of dimethyl carbonate and linear carboxylic acid esters having the structure shown in formula (1): R1 - (C=O) - O - R2 Formula (1); where R1 and R2 each independently comprise C1 to C5 alkyl or haloalkyl groups. [2] Battery cell according to claim 1, wherein the thickness of the one-sided adhesive layer is 0.5 µm to 5 µm. [3] Battery cell according to claim 2, wherein the thickness of the one-sided adhesive layer is 1 µm to 4 µm. [4] Battery cell according to one of claims 1 to 3, wherein the adhesive layer comprises one or more of polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymer. [5] Battery cell according to one of claims 1 to 4, wherein the separating film further comprises a ceramic coating arranged between the base film and the adhesive layer, wherein the material of the ceramic coating comprises inorganic ceramic particles. [6] Battery cell according to any one of claims 1 to 5, wherein the ratio of the size of the long side to the size of the short side of the cathode main body (4 to 6) is 1. [7] Battery cell according to any one of claims 1 to 6, wherein the linear carboxylic acid ester comprises one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate and isopropyl formate. [8] Battery cell according to any one of claims 1 to 7, wherein the mass fraction of the first solvent is 10% to 60%, based on the mass of the electrolyte solution. [9] Battery cell according to claim 8, wherein the mass fraction of the first solvent is 15% to 35%, based on the mass of the electrolyte solution. [10] Battery cell according to any one of claims 1 to 9, wherein the dimethyl carbonate and the linear carboxylic acid ester have an electrical conductivity of 10 mS / cm to 16 mS / cm at room temperature. [11] Battery cell according to any one of claims 1 to 10, wherein the electrolyte solution also comprises a lithium salt, wherein the lithium salt comprises one or more of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide; wherein the total mass fraction of lithium hexafluorophosphate and / or lithium bis(fluorosulfonyl)imide is 12% to 18%, based on the mass of the electrolyte solution. [12] Battery cell according to claim 11, wherein the mass ratio of lithium hexafluorophosphate to lithium bis(fluorosulfonyl)imide is (1.2 to 3):

1. [13] Battery cell according to any one of claims 1 to 12, wherein the electrolyte solution further comprises an additive, wherein the additive comprises one or more of vinylene carbonate, fluoroethylene carbonate and 1,3-propanesulfonate lactone; the mass fraction of the additive, based on the mass of the electrolyte solution, is less than or equal to 5%. [14] Battery cell according to claim 13, wherein the mass fraction of the additive is 0.5% to 3%, based on the mass of the electrolyte solution. [15] Battery cell according to any one of claims 1 to 14, wherein the battery cell further comprises a softpack outer shell, wherein the cathode foil, the separating film, the anode foil and the electrolyte solution are arranged in the softpack outer shell, wherein the thickness of the softpack outer shell is 70 µm to 200 µm. [16] Battery cell according to one of claims 1 to 15, wherein the anode foil comprises an anode main body and an anode tab section connected to the anode main body, wherein the anode main body comprises an anode current collector and an anode film layer, wherein the anode film layer comprises a first anode film layer and a second anode film layer arranged on the anode current collector, wherein the first anode film layer is located between the anode current collector and the second anode film layer; wherein the first anode film layer and the second anode film layer each comprise graphite, wherein the average value of the longest diameter of the graphite in the first anode film layer is 7 µm to 18 µm, wherein the average value of the longest diameter of the graphite in the second anode film layer is 6 µm to 10 µm, and wherein the average value of the longest diameter of the graphite in the first anode film layer is greater than the average value of the longest diameter of the graphite in the second anode film layer. [17] Battery cell according to claim 16, wherein the graphite in the first anode film layer and the second anode film layer each independently comprises a graphite particle body and a coating layer of amorphous carbon arranged on the surface of the graphite particle body, wherein the thickness of the coating layer of amorphous carbon is 100 nm to 500 nm. [18] Battery cell according to one of claims 16 to 17, wherein the thickness of the second anode film layer is 30% to 70% of the total thickness of the anode foil. [19] Battery cell according to one of claims 16 to 18, wherein the graphitization degree of the graphite in the first anode film layer and the second anode film layer is independently 90% to 94%. [20] Battery cell according to one of claims 16 to 19, wherein the cathode tab section is connected to the short side of the cathode main body, wherein the anode tab section is connected to the short side of the anode main body. [21] Battery cell according to one of claims 16 to 20, wherein the one-sided coating area density of the anode film layer is 0.13 g / 1540.25 mm² 2 up to 0.22 g / 1540.25 mm 2 amounts. [22] Battery cell according to claim 21, wherein the one-sided coating area density of the anode film layer is 0.14g / 1540.25 mm² 2up to 0.195g / 1540.25 mm 2 amounts. [23] Battery cell according to one of claims 16 to 22, wherein the ratio of the thickness of the anode foil to the thickness of the anode current collector is (15 to 25):

1. [24] Battery cell according to any one of claims 1 to 23, wherein the compression density of the anode foil is 1.3 g / cc to 1.52 g / cc. [25] Battery cell according to any one of claims 1 to 24, wherein the compression density of the anode foil is 1.35g / cc to 1.50g / cc. [26] Battery cell according to any one of claims 1 to 25, wherein the main cathode body comprises a cathode current collector and a cathode film layer, wherein the cathode film layer is arranged on the cathode current collector, wherein the cathode film layer comprises lithium-containing transition metal phosphate, wherein the lithium-containing transition metal phosphate comprises one or more of aluminum elements with a mass fraction of 200 ppm to 2500 ppm, the vanadium element with a mass fraction of 300 ppm to 2000 ppm and titanium elements with a mass fraction of 1500 ppm to 3500 ppm. [27] Battery cell according to claim 26, wherein the main cathode body further comprises a lower coating, wherein the lower coating is located between the cathode current collector and the cathode film layer, wherein the lower coating comprises a conductive medium, wherein the thickness of the lower coating is 0.5 µm to 3 µm. [28] Battery cell according to one of claims 26 to 27, wherein the one-sided coating area density of the cathode film layer is 0.33g / 1540.25 mm² 2 up to 0.45g / 1540.25 mm 2 amounts. [29] Battery cell according to claim 28, wherein the one-sided coating area density of the cathode film layer is 0.30g / 1540.25 mm² 2 up to 0.40g / 1540.25 mm 2 amounts. [30] Battery cell according to one of claims 26 to 29, wherein the ratio of the thickness of the cathode foil to the thickness of the cathode current collector is (10 to 20):

1. [31] Battery cell according to any one of claims 1 to 30, wherein the density of the cathode foil is 2.3g / cc to 2.65g / cc. [32] Battery cell according to any one of claims 1 to 31, wherein the density of the cathode foil is 2.35g / cc to 2.6g / cc. [33] Battery device comprising one or more battery cells according to any one of claims 1 to 32. [34] Power consumption device comprising one or more of the battery cell according to any one of claims 1 to 32 and the battery device according to claim 33.

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