An electric core, a preparation method thereof, a battery module, a battery pack, and a power utilization device

Abstract

This invention provides a battery cell and its manufacturing method, a battery module, a battery pack, and an electrical device. The battery cell includes a housing and a cell body placed within the housing. The flatness of the battery cell is 'a', and the standard deviation of the surface pressure distribution of the battery cell is 'b', where a ≤ 50 μm and b ≤ 3. By controlling its flatness to 'a' and surface pressure distribution standard deviation to 'b', this invention not only ensures the battery cell's capacity utilization but also enhances its cycle stability.

Description

Technical Field

[0001] This invention relates to the field of batteries, and more particularly to a battery cell and its manufacturing method, a battery module, a battery pack, and electrical equipment. Background Technology

[0002] Solid-state batteries are widely used in electric vehicles, aerospace, portable electronic devices, and large-scale energy storage systems due to their high energy density, excellent ionic conductivity, and potentially high safety. The core component of a solid-state battery is the cell, whose performance directly determines the overall performance of the battery system.

[0003] In actual production, solid-state batteries are usually manufactured through a stacking process. However, due to material properties and process limitations, the surface of the cell often has an uneven surface. This unevenness can lead to poor interface contact after the cell is pressurized and packaged, which in turn causes problems such as increased lithium-ion transport resistance and local short circuits, severely shortening the cycle life of solid-state batteries. Summary of the Invention

[0004] This invention provides a battery cell that, by controlling its flatness to be less than or equal to 50 μm and its surface pressure distribution standard deviation to be less than or equal to 3, not only ensures the battery cell's capacity utilization but also enhances its cycle stability.

[0005] The present invention also provides a method for preparing a battery cell, which can prepare the above-mentioned battery cell, and the preparation method is simple and easy to control.

[0006] The present invention also provides a battery module, which, because it includes the above-mentioned battery cells, has good safety and cycle stability.

[0007] The present invention also provides a battery pack, which, since it includes the above-mentioned cells or battery modules, has good safety and cycle stability.

[0008] The present invention also provides an electrical device, which, because it includes the aforementioned battery, has stable energy output and a long service life.

[0009] In a first aspect, the present invention provides a battery cell, wherein the flatness of the battery cell is a, and the standard deviation of the surface pressure distribution of the battery cell is b, wherein a≤50μm and b≤3.

[0010] In some alternative implementations, a ≤ 20 μm, b ≤ 2.

[0011] In some alternative embodiments, the battery cell includes a housing and a battery cell body disposed within the housing, at least one side of the battery cell body includes an adhesive layer located between the housing and the battery cell body, and the battery cell satisfies the following formula 1 and / or formula 2:

[0012] Formula 1,

[0013] Formula 2;

[0014] Among them, E cell E is the compressive elastic modulus of the battery cell. poly ε is the compressive elastic modulus of the adhesive layer; cycle The breathing effect deformation of the battery cell; T is the thickness of the battery cell; t is the thickness of the adhesive layer.

[0015] In some alternative implementations, 0.04 × 10 9 ≤E cell ≤6×10 9 The preferred value is 1.4 × 10⁻⁶. 9 ≤E cell ≤4.9×10 9 ;

[0016] And / or, 0.03 × 10 9 ≤E poly ≤0.84×10 9 The preferred value is 0.4×10 9 ≤E poly ≤0.75×10 9 ;

[0017] And / or, ε cycle ≤0.03, preferably 0.005≤ε cycle ≤0.02;

[0018] And / or, 5×10 -5 ≤T≤3×10 -3 Preferably 1×10 -4 ≤T≤2×10 -3 ;

[0019] And / or, 5×10 -5 ≤T≤2×10 -3 Preferably 1×10 -5 ≤t≤1×10 -3 In some alternative embodiments, the adhesive layer is made of at least one of epoxy resin, polyimide, polyimide, polyether, polyurethane, polyurea, phenolic resin, melamine, and acrylic resin.

[0020] In some optional embodiments, the battery cell body includes a negative electrode layer, an electrolyte layer, and a positive electrode layer stacked together; wherein, the negative electrode layer includes a negative electrode current collector and a negative electrode coating disposed on at least one side of the negative electrode current collector, the negative electrode coating including a negative electrode active material; the positive electrode layer includes a positive electrode current collector and a positive electrode coating disposed on at least one side of the positive electrode current collector, the positive electrode coating including a positive electrode active material.

[0021] In some alternative embodiments, the negative electrode active material includes: lithium and transition metal oxides;

[0022] And / or, the positive electrode active material includes: oxides of lithium and transition metals;

[0023] And / or, the electrolyte layer comprises a sulfide solid electrolyte.

[0024] In some alternative embodiments, the thickness of the negative electrode layer is 50 μm-200 μm;

[0025] And / or, the thickness of the electrolyte layer is 50 μm-100 μm;

[0026] And / or, the thickness of the positive electrode layer is 100μm-500μm.

[0027] Secondly, the present invention provides a method for preparing a battery cell, comprising the following steps:

[0028] The adhesive is applied to at least one side of the battery cell body, cured to form an adhesive layer, placed inside a housing, and then encapsulated to obtain the battery cell.

[0029] In some alternative embodiments, the adhesive comprises at least one of a polymer prepolymer, a polymer monomer, and a polymer oligomer; the polymer comprises at least one of epoxy resin, polyimide, polyimide, polyether, polyurethane, polyurea, phenolic resin, melamine, and acrylic resin.

[0030] Preferably, the adhesive further includes a catalyst and / or additives;

[0031] Preferably, the curing process is performed at a pressure of 1000 kg-2000 kg, a temperature of 50°C-70°C, and a time of 100 min-150 min.

[0032] Thirdly, the present invention provides a battery module, comprising a battery cell prepared by the method of the first aspect or the method of the second aspect.

[0033] Fourthly, the present invention provides a battery pack comprising a battery cell prepared by the method of the first aspect, a battery cell prepared by the method of the second aspect, or a battery module prepared by the method of the third aspect.

[0034] Fifthly, the present invention provides an electrical device comprising a battery cell according to the first aspect, a battery cell prepared by the preparation method of the second aspect, a battery module as described in the third aspect, or a battery pack according to the fourth aspect.

[0035] The battery cell of the present invention achieves the maximization of the contact area between the electrode and the solid electrolyte and the uniformity of the pressure distribution by controlling its flatness to be less than or equal to 50 μm and the standard deviation of the surface pressure distribution to be less than or equal to 3. On the one hand, this significantly reduces the interfacial impedance inside the battery cell, promotes the uniform transport of lithium ions, and ensures the capacity of the battery cell. On the other hand, the uniform pressure can effectively maintain the long-term close contact of the internal interface of the battery cell and enhance the cycle stability of the battery cell. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In this application, the terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0038] In this application, references to "an embodiment," "an example," or "an example" mean that a specific feature, structure, or characteristic described in connection with that embodiment, example, or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination.

[0039] Solid-state battery cells obtained through lamination processes typically suffer from surface unevenness. This is primarily due to limitations in materials, electrodes, and the manufacturing process itself, making it difficult to achieve a highly smooth surface. This unevenness is amplified significantly when multiple layers are laminated and the resulting cells are fully compressed under isostatic pressure, ultimately leading to undulating surfaces on the cell surface. The larger the cell, the more pronounced the unevenness.

[0040] During solid-state battery charging, significant pressure needs to be applied to both sides of the large surface area of ​​the cell to ensure complete adhesion between the positive and negative electrode plates and the electrolyte layer. This minimizes the ion resistance during the reciprocating motion of lithium ions within and between the positive and negative electrodes, resulting in optimal cell performance. Uneven surfaces on the cell surface can lead to uneven stress during pressurization. In concave areas, insufficient contact between the electrolyte and the electrode plates can cause abnormal cell performance; in convex areas, excessive compression of the electrolyte can cause micro-short circuits, thus affecting the overall stability of the cell.

[0041] Based on the above problems, the present invention provides the following technical solution:

[0042] In a first aspect, the present invention provides a battery cell with a flatness of a and a surface pressure distribution standard deviation of b, wherein a≤50μm and b≤3.

[0043] In this invention, by controlling the cell flatness to be less than or equal to 50 μm and the surface pressure distribution standard deviation to be less than or equal to 3, not only is the capacity of the cell guaranteed, but the cycle stability of the cell is also enhanced. The main reasons for this include: controlling the cell flatness ensures a smooth cell surface, which, combined with a uniform pressure distribution, effectively reduces the contact resistance between the electrodes and the solid electrolyte. Furthermore, under the same pressure, the actual contact area is larger, ensuring the sufficiency and uniformity of the ion transport channels, thereby guaranteeing the capacity and stability of the cell.

[0044] For example, the battery cell includes two large surfaces arranged opposite each other, namely the main surface. The flatness of the battery cell can be directly tested by a laser scanner with a resolution of 0.3 μm.

[0045] For example, the standard deviation of the surface pressure distribution of a battery cell can be tested by the following method:

[0046] Use a dot-matrix thin-film sensor with a dot density of no less than 1 dot / mm. 2 The battery cell and sensor are attached together and placed in a flatbed press. The pressure reaches 15 MPa and is maintained for 2 minutes. Data recording begins after 1 minute and continues until the pressure is released. The data from each point is exported, and its standard deviation can be calculated. The formula for calculating the standard deviation is:

[0047]

[0048] Where μ is the mean of all data, N is the sample size, and x i For any data value.

[0049] For example, a = any value or a range of any two of the following: 50μm, 40μm, 30μm, 20μm, 10μm, 5μm, 2μm, 1μm, 0μm. b = any value or a range of any two of the following: 1, 1.5, 1.7, 2.0, 2.2, 2.5, 2.7, 3.0.

[0050] In some implementations, a ≤ 20 μm and b ≤ 0.2.

[0051] The surface of the battery cells is smoother, and the pressure distribution on the surface of the cells is more uniform under high pressure, which helps to further ensure the capacity of the cells and their cycle stability.

[0052] In some embodiments, the battery cell includes a housing and a battery cell body disposed within the housing, wherein at least one side of the battery cell body includes an adhesive layer located between the housing and the battery cell body, and the battery cell satisfies the following formula 1 and / or formula 2:

[0053] Formula 1,

[0054] Formula 2;

[0055] Among them, E cell E represents the compressive elastic modulus of the battery cell. poly ε is the compressive elastic modulus of the adhesive layer. cycle The deformation due to the breathing effect of the battery cell; T is the thickness of the battery cell; t is the thickness of the adhesive layer.

[0056] In some implementations, the larger side of the battery cell includes the above adhesive layer.

[0057] The above-mentioned battery cells utilize an adhesive layer on the cell body, and define the matching relationship between parameters such as the compressive elastic modulus of the cell and the adhesive layer, the cell thickness, and the cell's breathing effect deformation. This ensures both the adhesive layer's ability to fill unevenness on the cell surface and the absorption of pressure fluctuations caused by volume changes during charge-discharge cycles, thereby guaranteeing the cell's capacity and improving its cycle stability. The main reasons are as follows: During assembly (static): Constraint pressure is applied to the cell, causing compression deformation of both the cell and the adhesive layer. The adhesive layer "flows" and fills the depressions on the cell surface until the pressure is balanced; at this point, the adhesive layer is in a pre-compressed state. During cycling (dynamic): The cell expands, applying additional pressure to the adhesive layer. Due to the pre-compression, further compression (or shearing) deformation requires greater force, thus partially "absorbing" the expansion force and converting it into higher elastic stress within the adhesive layer, rather than converting it entirely into additional constraint pressure on the cell body. When the cell contracts, the elastic potential energy stored in the adhesive layer is released, maintaining contact pressure on the cell and preventing interface separation. Therefore, the pressure and deformation experienced by the cell and the adhesive layer are interdependent in both dynamic and static stages. Equation 1 above, by matching the relationship between the compressive elastic modulus of the cell, the compressive elastic modulus of the adhesive layer, the breathing effect deformation of the cell, the thickness of the cell, and the thickness of the adhesive layer, can make the adhesive layer "flow" under restraint pressure, thereby achieving uniform and gapless contact between the cell body and the adhesive layer interface.

[0058] Furthermore, the compressive elastic modulus of the adhesive layer and the compressive elastic modulus of the cell body should be of the same order of magnitude or slightly lower, and both should be greater than or equal to 0.1 GPa. This allows mechanical waves (stress waves) to be transmitted and dissipated more smoothly when passing through the interface, rather than being reflected back into the cell body in large quantities. Therefore, the present invention further designs Formula 1 and / or Formula 2, which can further utilize the compressive deformation of the adhesive layer to simultaneously achieve interface filling and pressure buffering between the cell body and the adhesive layer.

[0059] It should be noted that the above relationships are limitations on the numerical relationships between the compressive elastic modulus of the battery cell, the compressive elastic modulus of the adhesive layer, the deformation due to the breathing effect of the battery cell, the thickness of the battery cell, and the thickness of the adhesive layer. When calculating, the units of the compressive elastic modulus of the battery cell and the adhesive layer are fixed in Pa, the units of the thickness of the battery cell and the adhesive layer are fixed in m.

[0060] E above cell E poly ε cycle σ, T, and t all refer to the battery cells after packaging and formation.

[0061] It is understood that the battery cell body includes two functional surfaces arranged opposite each other, and the adhesive layer is disposed on the outside of at least one functional surface.

[0062] In some implementations, the housing includes an aluminum-plastic shell.

[0063] The compressive modulus of a battery cell is its ability to resist deformation when compressed in the thickness direction. It is determined by the internal structure of the positive electrode, negative electrode, separator, electrolyte, and pores. Furthermore, it changes with the state of charge. During charging and discharging, the insertion / extraction of lithium and the expansion / contraction of the active material lattice cause changes in its macroscopic thickness and modulus, which is the fundamental cause of internal pressure fluctuations. To further ensure the adhesive layer's ability to fill unevenness on the cell surface and absorb pressure fluctuations caused by volume changes during charge-discharge cycles, in some embodiments, 0.04 × 10⁻⁶ is used. 9 ≤E cell ≤6×10 9 .

[0064] To further ensure the adhesive layer's ability to fill unevenness on the cell surface, in some embodiments, 1.4 × 10 9 ≤E cell ≤4.9×10 9 .

[0065] In some implementations, the method for testing the compressive modulus of a battery cell includes the following procedures:

[0066] Preset SOC: Charge / discharge the battery cell to 50% SOC and let it stand for a sufficient time to allow stress relaxation;

[0067] Apply preload: Apply a preload of 20 N at a rate of 1 mm / min to ensure full contact between the cell and the pressure plate. This point is set as the zero displacement point.

[0068] Compression test: Compression was performed at a quasi-static rate of 1 mm / min, and the pressure-displacement curve was recorded until the pressure reached a preset upper limit of 15 MPa;

[0069] Data processing: Convert pressure to surface pressure (stress), and displacement to strain (Δthickness / initial thickness); the compressive modulus is taken from the slope of the relatively linear part of the curve or the secant modulus of a specific stress range (e.g., 0.5-1.0MPa).

[0070] For example, E cell =0.04×10 9 0.05×10 9 0.07×10 9 1×10 9 1.5×10 9 2×10 9 2.5×10 9 3.0×10 9 3.5×10 94.0×10 9 4.5×10 9 5.0×10 9 6.0×10 9 The range of any value in the range, or any combination of both.

[0071] In some implementations, 0.03 × 10 9 ≤E poly ≤0.84×10 9 .

[0072] The above-mentioned compressive modulus of the adhesive layer ensures that the layer can deform sufficiently under assembly preload to fill typical surface irregularities and ensures that the layer operates in the linear elastic zone throughout its entire lifespan.

[0073] In some implementations, the compressive elastic modulus of the adhesive layer can be referenced to the standard GB / T 1041-2008, with a test temperature of 25°C. Specifically, the adhesive layer can be peeled off from the battery cell before testing.

[0074] For example, E poly =0.03×10 9 0.05×10 9 0.07×10 9 0.1×10 9 0.2×10 9 0.3×10 9 0.4×10 9 0.5×10 9 0.6×10 9 0.7×10 9 0.8×10 9 0.84×10 9 The range of any value in the range, or any combination of both.

[0075] To further ensure that the adhesive layer operates in the linear elastic region throughout its entire lifespan, in some embodiments, 0.4 × 10 9 ≤E poly ≤0.75×10 9 .

[0076] In some implementations, ε cycle ≤0.03.

[0077] The breathing effect deformation of a battery cell is the reversible deformation of the cell during the electrochemical reaction process. The above breathing effect deformation of the cell can ensure that the adhesive layer can deform sufficiently under assembly pre-compression to fill typical surface unevenness and provide basic buffer, thereby further ensuring the cycle performance of the cell.

[0078] The breathing effect deformation of a battery cell = the average breathing effect deformation of the cell over its entire lifespan divided by the initial thickness of the cell. The average breathing effect deformation of a battery cell over its entire lifespan can be tested through the following process:

[0079] The battery cell was placed in a tensile testing machine and compressed to 15 MPa under constant force. The initial thickness of the battery cell was recorded. Subsequently, it was charged and discharged at a rate of 0.5C / 0.33C until the capacity decayed to 80% of the theoretical capacity. The thickness of the battery cell at 0 SOC in each charge and discharge cycle was recorded. The thickness variable = the thickness of the battery cell in the current cycle - the initial thickness. The thickness variable / the battery cell thickness is the breathing effect deformation value of the corresponding cycle. The average value of the breathing effect in each cycle of the entire battery cell charge and discharge cycle is the breathing effect deformation value of the battery cell over its entire life cycle.

[0080] For example, ε cycle = any value from 0.005, 0.007, 0.01, 0.015, 0.02, 0.03, etc., or a range of any two of them.

[0081] To further ensure that the adhesive layer can deform sufficiently under assembly preload to fill typical surface irregularities and provide basic cushioning, thereby ensuring cell cycle performance, in some embodiments, 0.005 ≤ ε cycle ≤0.02.

[0082] In some implementations, 5×10 -5 ≤T≤3×10 -3 .

[0083] With a cell body thickness of the above, the absolute breathing deformation is smaller, which can better achieve the filling of unevenness on the cell surface by the adhesive layer.

[0084] For example, the thickness of the battery cell is T = 5 × 10⁻⁶. -5 6×10 -5 7×10 -5 8×10 -5 9×10 -5 1×10 -4 3×10 -4 5×10 -4 7×10 -4 9×10 -4 1×10 -3 1.5×10 -3 1.7×10 -3 2×10 -3 3×10 -3 The range of any value in the range, or any combination of both.

[0085] To further achieve the filling of unevenness on the cell surface by the adhesive layer, in some embodiments, 1×10 -4 ≤T≤2×10 -3 .

[0086] In some implementations, 5×10 -5 ≤t≤2×10 -3 .

[0087] The adhesive layer of the above thickness provides ample space for deformation, effectively mitigating strain caused by cell expansion while ensuring the normal performance of cell capacity.

[0088] The thickness of the adhesive layer and the battery cell can be obtained by measuring the thickness at at least 50 points using a laser thickness gauge or micrometer, and then averaging the results.

[0089] For example, t = 5 × 10 -5 7×10 -5 9×10 -5 1×10 -4 5×10 -4 7×10 -4 1×10 -3 2×10 -3 The range of any value in the range, or any combination of both.

[0090] To further ensure that the adhesive layer provides sufficient deformation space, thereby more effectively mitigating the strain caused by cell expansion, 1×10 -5 ≤t≤1×10 -3 .

[0091] In some embodiments, the adhesive layer is made of at least one of epoxy resin, polyimide, polyimide, polyether, polyurethane, polyurea, phenolic resin, melamine, and acrylic resin.

[0092] The adhesive layers made of the above materials have good chemical stability, thermal stability, adjustable modulus, and high elastic deformation capability. Specifically, the modulus and high elastic deformation capability can be further adjusted by adjusting the molecular weight of the main material (for polyurethane and polyurea, the ratio and type of soft and hard segments can also be changed).

[0093] In some embodiments, the adhesive layer further includes additives; the additives include at least one of leveling agents and defoamers.

[0094] Leveling agents reduce the surface tension of the adhesive, allowing it to quickly wet and spread on the surface of the battery cell, and level itself before curing, forming a uniform, smooth adhesive layer free of pinholes and orange peel. Defoamers prevent air bubbles from being incorporated during production and use, and promote the rapid escape and collapse of any already incorporated bubbles, resulting in a dense, bubble-free cured adhesive layer.

[0095] In some embodiments, leveling agents include, but are not limited to, polybutyl acrylate oligomers, polyether-modified polydimethylsiloxane, fluorocarbon-modified acrylic acid, polymethylphenylsiloxane, and polyoxyethylene-oxypropylene-modified polysiloxane; defoamers include, but are not limited to, polydimethylsiloxane, polyoxyethylene-polyoxypropylene block polyether, and fatty acid esters.

[0096] In some embodiments, the leveling agent comprises 0.01wt%-0.5wt% of the total mass of the adhesive layer; for example, including but not limited to any value or a range of any two of the following: 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%. The defoamer comprises 0.01wt%-0.5wt% of the total mass of the adhesive layer; for example, including but not limited to any value or a range of any two of the following: 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%.

[0097] The above-mentioned additive ratio can further ensure the filling ability of the adhesive layer on the uneven surface of the battery cell, and can also absorb the pressure fluctuations caused by the volume changes of the battery cell during charge and discharge cycles, thereby improving the cycle stability of the battery cell.

[0098] In some embodiments, the battery cell body includes a negative electrode layer, an electrolyte layer, and a positive electrode layer stacked together; wherein, the negative electrode layer includes a negative electrode current collector and a negative electrode coating disposed on at least one side of the negative electrode current collector, and the negative electrode coating includes a negative electrode active material; the positive electrode layer includes a positive electrode current collector and a positive electrode coating disposed on at least one side of the positive electrode current collector, and the positive electrode coating includes a positive electrode active material.

[0099] It is understood that the above-mentioned battery cell is a solid-state battery cell. Since the battery cell of the present invention has an adhesive layer on the battery cell body and limits the matching relationship between parameters such as the compressive elastic modulus, thickness, breathing effect deformation of the battery cell, and restraint pressure of the battery cell, the problem of uneven surface of solid-state battery cells can be solved.

[0100] In some embodiments, the negative electrode current collector is made of at least one metal selected from Cu, Au, and Ti; the positive electrode current collector is made of at least one metal selected from Ag, Cu, Al, Ni, and Fe.

[0101] In some embodiments, the negative electrode coating comprises, by weight, 80-98 parts of negative electrode active material, 1-10 parts of first binder, 1-10 parts of first conductive agent and 5-15 parts of first solid electrolyte; the positive electrode coating comprises 93-97.5 parts of positive electrode active material, 1-10 parts of second binder, 1-10 parts of second conductive agent and 5-50 parts of second solid electrolyte.

[0102] For example, the negative electrode coating includes a negative electrode active material in the range of any value or any combination of two of the following: 80 parts, 85 parts, 90 parts, 95 parts, 98 parts, etc.; a first binder in the range of any value or any combination of two of the following: 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, etc.; a first conductive agent in the range of any value or any combination of two of the following: 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, etc.; and a first solid electrolyte in the range of any value or any combination of two of the following: 5 parts, 6 parts, 8 parts, 10 parts, 15 parts, etc.

[0103] For example, the positive electrode coating includes a positive electrode active material in the range of any value or any combination of two of the following: 93 parts, 95 parts, 97.5 parts, etc.; a second binder in the range of any value or any combination of two of the following: 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, etc.; a second conductive agent in the range of any value or any combination of two of the following: 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, etc.; and a second solid electrolyte in the range of any value or any combination of two of the following: 5 parts, 6 parts, 8 parts, 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, etc.

[0104] In some embodiments, the negative electrode active material includes at least one metal selected from lithium metal, lithium alloy, carbon material, silicon material, and metal salt.

[0105] For example, lithium alloys include, but are not limited to: lithium indium alloys and lithium magnesium alloys; carbon materials include, but are not limited to: graphite and hard carbon; silicon materials include, but are not limited to: silicon alloys, silicon-carbon composites, and silicon-oxygen composites; silicon alloys include, but are not limited to: lithium titanate.

[0106] In some embodiments, the positive electrode active material includes: oxides of lithium and transition metals; specifically including but not limited to: lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel-cobalt-manganese oxide (NCM), Li-Mn oxide spinel with different element substitution, lithium titanium oxide, and lithium metal phosphates such as lithium iron phosphate.

[0107] In some embodiments, the first adhesive and the second adhesive may be the same or different, including but not limited to at least one of polyacrylic acid (PAA), polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), sodium carboxymethyl cellulose (CMC), and polytetrafluoroethylene (PTFE).

[0108] In some embodiments, the first conductive agent and the second conductive agent may be the same or different, including but not limited to: at least one of carbon black, carbon nanotubes, graphene, and carbon fiber, wherein the carbon black includes Super P and / or acetylene black.

[0109] In some embodiments, the first solid electrolyte and the second solid electrolyte may be the same or different, including but not limited to: sulfide solid electrolytes. Sulfide solid electrolytes include sulfide-based amorphous solid electrolytes and sulfide-based crystalline solid electrolytes.

[0110] In some embodiments, sulfide-based amorphous solid electrolytes include Li₂S-P₂S₅, Li₂O-Li₂S-P₂S₅, Li₂S, P₂S₅, Li₂S-SiS₂, LiI-Li₂S-SiS₂, LiI-Li₂S-P₂S₅, LiI-Li₂S-P₂O₅, LiI-LiBr-Li₂S-P₂S₅, and LiI-Li₃PO₄-P₂S₅; sulfide-based crystalline solid electrolytes include glass-ceramics such as Li₇P₃S₁₁ and Li₂P₃S₁₅. 3.25 P 0.75 S4, thiolated LiSiCION crystals such as Li 3.24 P 0.24 Ge 0.76 S4 and materials with a sulfogermanium sulfide crystal structure, such as Li6PS5X (X = Cl, Br, I).

[0111] To further improve the lithium-ion conductivity of the battery cell, a sulfide system of silver-germanium sulfide is preferred for the solid electrolyte.

[0112] In some embodiments, the electrolyte layer comprises a sulfide solid electrolyte.

[0113] Further defining the materials of the negative electrode layer, electrolyte layer, and positive electrode layer means controlling the expansion of the cell itself from its source, and working in conjunction with the buffering effect of the outer adhesive layer to further improve the cycle stability of the cell.

[0114] The compaction density of the negative electrode layer, positive electrode layer, or electrolyte layer affects the "mechanical properties" of the battery cell. It can further regulate the rigidity of the battery cell body, the uniformity of expansion behavior, and the distribution of internal stress, and limit their range. This can create a more stable and predictable environment for the "dynamic matching" of the adhesive layer and the battery cell body.

[0115] In some embodiments, the compaction density of the negative electrode layer is 1.0 g / cm³. 3 -1.8 g / cm 3 For example, the compaction density of the negative electrode layer is 1 g / cm³. 3 1.2 g / cm 3 1.5 g / cm 3 1.7 g / cm 3 1.8 g / cm 3 The range of any value in the range, or any combination of both.

[0116] In some embodiments, the compaction density of the electrolyte layer is 1.5 g / cm³. 3 -2.5 g / cm 3 For example, the compaction density of the electrolyte layer is 1.5 g / cm³. 3 1.7 g / cm 3 1.8 g / cm 3 2.0 g / cm 3 2.5 g / cm 3 The range of any value in the range, or any combination of both.

[0117] In some embodiments, the compaction density of the positive electrode layer is 2.5 g / cm³. 3 -4 g / cm 3 For example, the compaction density of the positive electrode layer is 2.5 g / cm³. 3 3.0 g / cm 3 3.5 g / cm 3 4.0 g / cm 3 The range of any value in the range, or any combination of both.

[0118] The above-mentioned compacted negative electrode layer, positive electrode layer or electrolyte layer can further balance the relationship between battery capacity utilization and cycle life.

[0119] In some embodiments, the thickness of the negative electrode layer is 50-200 μm. Exemplarily, the thickness of the negative electrode layer is any value or a range of any combination of 50 μm, 70 μm, 100 μm, 150 μm, 200 μm, etc.

[0120] In some embodiments, the thickness of the electrolyte layer is 50-100 μm. Exemplarily, the thickness of the electrolyte layer is any value or a range of any combination of 50 μm, 70 μm, 100 μm, 150 μm, 200 μm, etc.

[0121] In some embodiments, the thickness of the positive electrode layer is 100-500 μm. For example, the thickness of the positive electrode layer is any value or a range of any combination of 100 μm, 150 μm, 200 μm, 300 μm, 400 μm, 500 μm, etc.

[0122] The above-mentioned compacted negative electrode layer, positive electrode layer or electrolyte layer can further balance the relationship between battery capacity and cycle life, and ensure that the cell thickness meets the requirement of 1≤T≤20.

[0123] For example, the above-mentioned battery cell body can be prepared by a method including the following process: stacking a negative electrode layer, a positive electrode layer, and an electrolyte layer in sequence; placing the stacked battery cell in a battery packaging film shell (such as an aluminum-plastic film shell) to obtain the battery cell body of the present invention.

[0124] Secondly, the present invention provides a method for preparing a battery cell, comprising the following steps:

[0125] The adhesive is applied to at least one side of the battery cell body, and a curing process is performed to form an adhesive layer, thus obtaining the battery cell.

[0126] In some embodiments, the process also includes placing the battery cell body, including the adhesive layer, inside a housing for encapsulation.

[0127] In some embodiments, the adhesive comprises at least one of a polymer prepolymer, a polymer monomer, and a polymer oligomer; the polymer comprises at least one of epoxy resin, polyimide, polyimide, polyether, polyurethane, polyurea, phenolic resin, polymelamine, and acrylic resin.

[0128] For example, the adhesive specifically includes at least one of the following: epoxy resin prepolymer, polyimide prepolymer, polyimide prepolymer, polyether prepolymer, polyurethane prepolymer, polyurea prepolymer, phenolic resin prepolymer, polymelamine prepolymer, acrylic resin prepolymer, epoxy resin monomer, polyimide monomer, polyimide monomer, polyether monomer, polyurethane monomer, polyurea monomer, phenolic resin monomer, polymelamine monomer, acrylic resin monomer, epoxy resin oligomer, polyimide oligomer, polyimide oligomer, polyether oligomer, polyurethane oligomer, polyurea oligomer, phenolic resin oligomer, polymelamine oligomer, and acrylic resin oligomer.

[0129] In some embodiments, the adhesive also includes defoamers, catalysts, leveling agents, etc.

[0130] The catalyst includes, but is not limited to, at least one of the following: trimethylamine, triethylamine, aniline, dibutyltin dilaurate, zinc octanoate, triethylenediamine, azobisisobutyronitrile, potassium persulfate, benzoyl peroxide, camphorquinone, etc.

[0131] Leveling agents include, but are not limited to, polybutyl acrylate oligomers, polyether-modified polydimethylsiloxane, fluorocarbon-modified acrylic acid, polymethylphenylsiloxane, and polyoxyethylene-oxypropylene-modified polysiloxane; defoamers include, but are not limited to, polydimethylsiloxane, polyoxyethylene-polyoxypropylene block polyether, and fatty acid esters.

[0132] The catalyst accounts for 0.1%-0.5% of the adhesive solution by mass; the defoamer accounts for 0.1%-0.5% of the adhesive solution; and the leveling agent accounts for 0.1%-0.5% of the adhesive solution.

[0133] In some embodiments, the curing process includes a flatbed hot pressing process, in which the adhesive molecular chains are cross-linked and cured to form an adhesive layer that is fully bonded to the surface of the battery cell.

[0134] In some embodiments, the curing process is carried out at a pressure of 1000 kg to 2000 kg, a temperature of 50°C to 70°C, and a time of 100 min to 150 min.

[0135] Flat plate hot pressing ensures that the adhesive uniformly fills surface defects during the curing process through the synergistic effect of temperature and pressure, forming a stable three-dimensional network structure adhesive layer. This adhesive layer can effectively eliminate surface irregularities of the battery cell, improve the uniformity of interface contact, reduce performance degradation caused by local short circuits, and maintain the structural stability of the battery cell under high restraint pressure.

[0136] For example, the pressure of the curing process is any value or a range of any two of 1000 kg, 1200 kg, 1400 kg, 1600 kg, 1800 kg, 2000 kg, etc.; the temperature is any value or a range of any two of 50°C, 55°C, 60°C, 65°C, 70°C, etc.; and the time is any value or a range of any two of 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, etc.

[0137] Thirdly, the present invention provides a battery module, comprising a battery cell prepared by the method of the first aspect or the method of the second aspect.

[0138] Because the battery module includes the aforementioned cells, it has good safety and cycle stability.

[0139] Fourthly, the present invention provides a battery pack comprising a battery cell prepared by the method of the first aspect, a battery cell prepared by the method of the second aspect, or a battery module prepared by the method of the third aspect.

[0140] Because the battery pack includes the aforementioned cells or battery modules, it has good safety and cycle stability.

[0141] It should be noted that when a battery pack includes multiple (at least two) of the above-mentioned cells or battery modules, these cells or battery modules can be electrically connected by conventional methods in the art, such as series connection, parallel connection, or a hybrid connection that includes both of these connection methods, without any particular limitation.

[0142] Fifthly, the present invention provides an electrical device comprising the above-mentioned battery cells or battery modules / packs.

[0143] It should be noted that the above-mentioned electrical equipment can be any equipment that conventionally requires electricity, such as, but not limited to, computers, electric vehicles, air conditioners, refrigerators, washing machines, microwave ovens, printers, fax machines, etc.

[0144] To further understand the present invention, the technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0145] Unless otherwise specified, all reagents involved in the embodiments of this invention are commercially available products and can be purchased through commercial channels.

[0146] Example 1

[0147] The battery cell in this embodiment includes an aluminum-plastic film and a battery cell body inside the aluminum-plastic film. Adhesive layers are provided on both sides of the battery cell, as detailed in Table 1. The preparation method includes the following processes:

[0148] The method for preparing the negative electrode layer is as follows: silicon-carbon (wherein the mass percentage of silicon is 55 wt%) is used as the negative electrode active material, and solid electrolyte Li is used. 5.7 PS 4.7 Cl 1.3 A negative electrode slurry was prepared by dispersing PVDF and binder in toluene at a mass ratio of 8:1:1. The prepared negative electrode slurry was coated on both sides of an aluminum foil and dried to obtain a negative electrode with a negative electrode active material layer thickness of 150 μm.

[0149] The electrolyte layer is prepared by: using solid electrolyte Li 5.7 PS 4.7 Cl 1.3 An electrolyte layer slurry was prepared by dispersing PVDF and binder in toluene. The obtained electrolyte layer slurry was coated on one side of an aluminum foil and dried to obtain a solid electrolyte layer with a thickness of about 50 μm. The electrolyte layer was then stacked with the above-mentioned negative electrode layer, rolled, and the aluminum foil containing the electrolyte layer was removed to obtain a composite negative electrode layer with the electrolyte layer transferred to the negative electrode layer.

[0150] The method for preparing the positive electrode layer is as follows: using ternary material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), conductive agent acetylene black, solid electrolyte Li 5.7 PS 4.7 Cl 1.3A slurry was prepared by dispersing the binder and adhesive in toluene at a mass ratio of 8:1:1:0.5. The slurry was then coated on both sides of a copper foil and dried to obtain a positive electrode with a positive electrode active material layer thickness of approximately 300 μm.

[0151] The adhesive used is a commercially available adhesive, model number Debon 8463;

[0152] Multilayer laminated cells are prepared by cutting the negative and positive electrode layers to a certain size and stacking them alternately. The laminated cells are then placed in an aluminum-plastic film and vacuum heat-sealed. Isostatic pressing is then performed to compact the cells, resulting in a compacted cell body. The aluminum-plastic film is then removed, and the tab leads are soldered to the cell body. After completion, a certain thickness of adhesive is applied to two opposite large surfaces of the cell body using a self-leveling method. Once the adhesive surface is basically cured, the cell is placed in a flatbed hot press. The initial pressure applied to the cell by the flatbed hot press is 1000 kg, the holding time is 120 min, and the heating temperature of the pressing plate is 60℃. Finally, the cell is encapsulated in an aluminum-plastic film and vacuum heat-sealed on all sides to obtain a cell with a length of 100 mm and a width of 5 mm.

[0153] Example 2

[0154] The differences between this example cell and Example 1 are shown in Table 1. The difference in preparation method between this example cell and Example 1 is that the ternary material LiNi is used when preparing the positive electrode layer. 0.8 Co 0.1 Mn 0.1 O2, conductive agent acetylene black, solid electrolyte Li 5.7 PS 4.7 Cl 1.3 The adhesive and binder were mixed in a mass ratio of 6:1:3:0.5, and the rest was basically the same as in Example 1.

[0155] Example 3

[0156] The differences between this example cell and Example 1 are shown in Table 1. The difference in preparation method between this example cell and Example 1 is that the ternary material LiNi is used when preparing the positive electrode layer. 0.8 Co 0.1 Mn 0.1 O2, conductive agent acetylene black, solid electrolyte Li 5.7 PS 4.7 Cl 1.3 When preparing the negative electrode layer, silicon-carbon and solid electrolyte Li are mixed with binder at a mass ratio of 6:1:3:0.5. 5.7 PS 4.7 Cl 1.3 The PVDF binder was mixed at a mass ratio of 6:3.5:0.5, and the rest was basically the same as in Example 1.

[0157] Example 4

[0158] The differences between this example cell and Example 1 are shown in Table 1. The difference in preparation method between this example cell and Example 1 is that the ternary material LiNi is used when preparing the positive electrode layer. 0.8 Co 0.1 Mn 0.1 O2, conductive agent acetylene black, solid electrolyte Li 5.7 PS 4.7 Cl 1.3 When preparing the negative electrode layer, silicon-carbon and solid electrolyte Li are mixed with binder at a mass ratio of 8:1:0.5:0.5. 5.7 PS 4.7 Cl 1.3 Mix with PVDF adhesive at a mass ratio of 9:0.5:0.5, otherwise basically the same as in Example 1.

[0159] Example 5

[0160] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in its preparation method compared to Example 1 is that the number of battery cell lamination layers is increased, resulting in a battery cell thickness of 20 mm.

[0161] Example 6

[0162] The differences between this example cell and Example 1 are shown in Table 1. The difference in the preparation method between this example cell and Example 1 is that the number of cell lamination layers is reduced, resulting in a cell thickness of 1 mm.

[0163] Example 7

[0164] The differences between this example cell and Example 1 are shown in Table 1. The difference in the preparation method between this example cell and Example 1 is that the number of cell lamination layers is reduced, resulting in a cell thickness of 0.5 mm.

[0165] Example 8

[0166] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in its preparation method compared to Example 1 is that the number of battery cell lamination layers is increased, resulting in a battery cell thickness of 30 mm.

[0167] Example 9

[0168] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in its preparation method compared to Example 1 is that the adhesive is replaced with polyurethane adhesive, model number Debon 8641.

[0169] Example 10

[0170] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in its preparation method compared to Example 1 is that the adhesive is replaced with epoxy adhesive, model H462.

[0171] Example 11

[0172] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in its preparation method compared to Example 1 is that the adhesive is replaced with methacrylate adhesive, model Henkel A320.

[0173] Example 12

[0174] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in its preparation method compared to Example 1 is that the adhesive is replaced with phenolic resin, model number KEB MH4984.

[0175] Example 13

[0176] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in its preparation method compared to Example 1 is that the amount of adhesive injected is controlled so that the adhesive layer thickness is changed to 1000 μm.

[0177] Example 14

[0178] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in its preparation method compared to Example 1 is that the amount of adhesive injected is controlled so that the adhesive layer thickness is changed to 100 μm.

[0179] Example 15

[0180] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in its preparation method compared to Example 1 is that the amount of adhesive injected is controlled so that the adhesive layer thickness is changed to 50 μm.

[0181] Example 16

[0182] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in its preparation method compared to Example 1 is that the amount of adhesive injected is controlled so that the adhesive layer thickness is changed to 2000 μm.

[0183] Example 17

[0184] The differences between this example cell and Example 1 are shown in Table 1. The difference in its preparation method compared to Example 1 is that the silicon-carbon of the negative electrode layer is replaced with pure silicon.

[0185] Example 18

[0186] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in its preparation method compared to Example 1 is that the silicon-carbon anode layer is replaced with pure silicon coated with lithium titanate.

[0187] Comparative Example 1

[0188] The difference from Example 1 is that it does not contain an adhesive layer.

[0189] Comparative Example 2

[0190] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in preparation method between this example and Example 1 is that: when preparing the positive electrode layer, the ternary material LiNi... 0.8 Co 0.1 Mn 0.1 O2, conductive agent acetylene black, solid electrolyte Li 5.7 PS 4.7 Cl 1.3 The binder and silicon carbide were mixed in a mass ratio of 5:1:4:0.5; when preparing the negative electrode layer, silicon carbide and solid electrolyte Li... 5.7 PS 4.7 Cl 1.3 Mix the PVDF adhesive with the PVDF adhesive at a mass ratio of 2:7:1. When preparing the adhesive layer, change the adhesive to silicone adhesive, model MS210, and the coating thickness is 50μm. When stacking the cells, increase the number of stacked layers to make the cell thickness 30 mm.

[0191] Comparative Example 3

[0192] The differences between this example battery cell and Example 1 are shown in Table 1. The difference in preparation method between this example and Example 1 is that: when preparing the positive electrode layer, the ternary material LiNi... 0.8 Co 0.1 Mn 0.1 O2, conductive agent acetylene black, solid electrolyte Li 5.7 PS 4.7 Cl 1.3 The binder and silicon carbide were mixed in a mass ratio of 8:1:1:0.5; when preparing the negative electrode layer, silicon carbide and solid electrolyte Li... 5.7 PS 4.7 Cl 1.3 Mix the PVDF adhesive with the PVDF adhesive at a mass ratio of 8.5:0.5:1. When preparing the adhesive layer, change the adhesive to epoxy adhesive, model KEB EP210, and the coating thickness is 2000μm. When stacking the cells, reduce the number of stacked layers to make the cell thickness 0.5mm.

[0193] Performance testing

[0194] 1. The flatness of the battery cell was directly tested at 50 points on the large surface of the battery cell using a laser scanner with a resolution of 0.3μm, and the average value was calculated.

[0195] 2. The compression modulus of the adhesive layer shall be tested in accordance with GB / T 1041-2008, and the test temperature range shall be 25 ℃.

[0196] 3. Pressure distribution testing uses a dot-matrix thin-film sensor with a dot density of not less than 1 dot / mm². 2The test pressure is 15 MPa. During the test, the battery cell and sensor are attached together and placed in a flatbed press. The pressure is maintained at 15 MPa for 2 minutes, and data recording begins after 1 minute until the pressure is released. The standard deviation of the data collected can be calculated by exporting the data. The formula for calculating the standard deviation is:

[0197]

[0198] Where μ is the mean of all data, N is the sample size, and x i For any data value.

[0199] 4. The breathing effect deformation of the battery cell can be measured by the following method:

[0200] The breathing effect deformation of a battery cell = the average breathing effect deformation of the cell over its entire life cycle divided by the initial thickness of the cell. The average breathing effect deformation of the cell over its entire life cycle is tested through the following process:

[0201] The battery cell was placed in a tensile testing machine and compressed to 15 MPa under constant force. The initial thickness of the battery cell was recorded. Subsequently, it was charged and discharged at a rate of 0.5C / 0.33C until the capacity decayed to 80% of the theoretical capacity. The thickness of the battery cell at 0 SOC in each charge and discharge cycle was recorded. The thickness variable = the thickness of the battery cell in the current cycle - the initial thickness. The thickness variable / the battery cell thickness is the breathing effect deformation value of the corresponding cycle. The average value of the breathing effect in each cycle of the entire battery cell charge and discharge cycle is the breathing effect deformation value of the battery cell over its entire life cycle.

[0202] 5. The cell cycle performance test constraint force is 15MPa, the formation charge-discharge rate is 0.1C / 0.1C, and the specific capacity of the cell in the first cycle after formation is recorded. The charge-discharge rate is 0.5C / 0.33C, and the specific capacity of the cell after 50 cycles is recorded. The test voltage is 2.0V-4.0V.

[0203] The test results are shown in Tables 1 and 2.

[0204] Table 1:

[0205]

[0206] Table 2:

[0207]

[0208] As shown in Tables 1 and 2, compared with Comparative Examples 1-3, the battery cells of Examples 1-18, by setting an adhesive layer on the battery cell body and limiting the matching relationship between the two parameters such as the compressive elastic modulus, thickness, and the battery cell's breathing effect deformation, can not only ensure the adhesive layer's ability to fill unevenness on the battery cell surface, but also absorb the pressure fluctuations caused by the volume changes of the battery cell during charge and discharge cycles, thereby further improving the cycle stability of the battery cell.

[0209] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery cell, characterized in that, The flatness of the battery cell is 'a', and the standard deviation of the surface pressure distribution of the battery cell is 'b', where a ≤ 50 μm and b ≤ 3.

2. The battery cell according to claim 1, characterized in that, a≤20μm, b≤2.

3. The battery cell according to claim 1, characterized in that, The battery cell includes a housing and a battery cell body disposed within the housing. At least one side of the battery cell body includes an adhesive layer located between the housing and the battery cell body. The battery cell satisfies the following formula 1 and / or formula 2: Formula 1, Formula 2; Among them, E cell E is the compressive elastic modulus of the battery cell. poly ε is the compressive elastic modulus of the adhesive layer; cycle The breathing effect deformation of the battery cell; T is the thickness of the battery cell; t is the thickness of the adhesive layer.

4. The battery cell according to claim 1, characterized in that, 0.04×10 9 ≤E cell ≤6×10 9 The preferred value is 1.4 × 10⁻⁶. 9 ≤E cell ≤4.9×10 9 ; And / or, 0.03 × 10 9 ≤E poly ≤0.84×10 9 The preferred value is 0.4×10 9 ≤E poly ≤0.75×10 9 ; And / or, ε cycle ≤0.03, preferably 0.005≤ε cycle ≤0.02; And / or, 5×10 -5 ≤T≤3×10 -3 Preferably 1×10 -4 ≤T≤2×10 -3 ; And / or, 5×10 -5 ≤t≤2×10 -3 Preferably 1×10 -5 ≤t≤1×10 -3 .

5. The battery cell according to any one of claims 1-4, characterized in that, The adhesive layer is made of at least one of epoxy resin, polyimide, polyimide, polyether, polyurethane, polyurea, phenolic resin, melamine, and acrylic resin.

6. The battery cell according to any one of claims 1-5, characterized in that, The battery cell body includes a negative electrode layer, an electrolyte layer, and a positive electrode layer stacked together; wherein, the negative electrode layer includes a negative electrode current collector and a negative electrode coating disposed on at least one side of the negative electrode current collector, and the negative electrode coating includes a negative electrode active material; the positive electrode layer includes a positive electrode current collector and a positive electrode coating disposed on at least one side of the positive electrode current collector, and the positive electrode coating includes a positive electrode active material.

7. The battery cell according to claim 6, characterized in that, The negative electrode active material includes at least one metal selected from lithium metal, lithium alloy, carbon material, silicon material, and metal salt; And / or, the positive electrode active material includes: oxides of lithium and transition metals; And / or, the electrolyte layer comprises a sulfide solid electrolyte.

8. The battery cell according to claim 6 or 7, characterized in that, The thickness of the negative electrode layer is 50μm-200μm; And / or, the thickness of the electrolyte layer is 50 μm-100 μm; And / or, the thickness of the positive electrode layer is 100μm-500μm.

9. A method for preparing a battery cell as described in any one of claims 1-8, characterized in that, Includes the following steps: An adhesive is applied to at least one side of the battery cell body, and a curing process is performed to form an adhesive layer, thereby obtaining the battery cell.

10. The preparation method according to claim 9, wherein the adhesive comprises at least one of a polymer prepolymer, a polymer monomer, and a polymer oligomer; and the polymer comprises at least one of epoxy resin, polyimide, polyimide, polyether, polyurethane, polyurea, phenolic resin, polymelamine, and acrylic resin. Preferably, the adhesive further includes a catalyst and / or additives; Preferably, the curing process is performed at a pressure of 1000 kg-2000 kg, a temperature of 50°C-70°C, and a time of 100 min-150 min.

11. A battery module, characterized in that, This includes the battery cell described in any one of claims 1-8 or the battery cell prepared by the preparation method described in any one of claims 9-10.

12. A battery pack, characterized in that, This includes the battery cell described in any one of claims 1-8, the battery cell prepared by the preparation method described in any one of claims 9-10, or the battery module described in claim 11.

13. An electrical appliance, characterized in that, This includes the battery cell according to any one of claims 1-8, the battery cell prepared by any one of claims 9-10, the battery module according to claim 11, or the battery pack according to claim 12.

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