Battery and preparation method thereof, method for evaluating flatness of battery, battery device and power utilization device

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a battery and a preparation method thereof, a method for evaluating the flatness of the battery, a battery device and a power utilization device, and the surface thickness distribution coefficient SPAN (a-b) = (Ta-Tb) / T50 of the battery meets at least one of the following conditions: SPAN (100) is less than or equal to 4.11%; sPAN (90) is less than or equal to 1.73%; sPAN (80) is less than or equal to 1.24%; sPAN (70) is less than or equal to 0.99%; < = 0.80% of SPAN (60); sPAN (50) is less than or equal to 0.64%. The battery has relatively high capacity and relatively good rate capability.

Description

Technical Field

[0001] This application relates to the field of batteries, specifically to batteries and their preparation methods, methods for evaluating battery flatness, battery devices, and electrical devices. Background Technology

[0002] Solid-state batteries require high external constraint forces (typically >3MPa) to maintain interfacial contact stability due to the solid-solid contact issues between particles. Under high constraint forces, even slight deviations in the surface flatness of the battery can lead to severe uneven stress distribution. This results in the capacity of low-stress areas not being fully utilized, thus affecting the overall battery capacity. Furthermore, the porosity and interfacial contact differences between high-stress and low-stress areas lead to variations in interfacial impedance and lithium-ion flux, impacting capacity utilization and rate performance. Therefore, issues related to battery surface flatness still require improvement. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a battery that can effectively utilize its capacity and rate performance, a method for its preparation, a method for evaluating battery flatness, a battery device, and an electrical device.

[0004] A first aspect of this application provides a battery. According to an embodiment of this application, the surface thickness distribution coefficient SPAN(ab) of the battery is = (T... a -T b ) / T 50 At least one of the following conditions must be met: SPAN (100) ≤ 4.11%; SPAN (90) ≤ 1.73%; SPAN (80) ≤ 1.24%; SPAN (70) ≤ 0.99%; SPAN (60) ≤ 0.80%; SPAN (50) ≤ 0.64%; Among them, T a This represents the a-th percentile of the battery thickness data. T b This represents the b-th percentile of the battery thickness data. T 50 This represents the 50th percentile of the battery thickness data. a + b = 100; The thickness data includes multiple thickness values ​​corresponding to the surface dot matrix of at least one surface of the battery, wherein the dot density of the surface dot matrix is ​​≥0.1 dots / cm. 2 .

[0005] Specifically, the surface thickness distribution coefficient (SPAN) of the battery can eliminate extreme data and avoid interference from outliers. Simultaneously, the SPAN value focuses on intermediate data, more closely reflecting the actual stress area under battery constraint. Furthermore, the SPAN value is directly related to the stress distribution under battery constraint, which directly impacts battery performance. The SPAN value can more accurately reflect differences in battery capacity and rate performance. In the battery of this application, by controlling the SPAN value to meet the above requirements, the battery exhibits high flatness, thereby improving the uniformity of stress distribution. This results in more uniform ion transport and ion flux during cycling, avoiding excessively high local current density, improving the overall utilization rate of active materials, and ultimately leading to higher battery capacity and better rate performance.

[0006] According to embodiments of this application, 50≤ab≤100, or 70≤ab≤90.

[0007] According to embodiments of this application, the battery satisfies at least one of the following conditions: 75≤a≤100; 0≤b≤25.

[0008] According to an embodiment of this application, the dot density of the surface dot matrix is ​​1 dot / cm². 2 ~200 pieces / cm 2 .

[0009] According to an embodiment of this application, the battery includes two large surfaces and two narrow surfaces arranged opposite to each other, the area of ​​the large surfaces being larger than the area of ​​the narrow surfaces, and the surface dot matrix being located on at least one of the large surfaces of the battery.

[0010] According to an embodiment of this application, the distance between two adjacent points of the surface dot matrix does not exceed 1 cm.

[0011] A second aspect of this application provides a method for preparing the aforementioned battery. According to an embodiment of this application, the method includes: coating a positive electrode slurry onto at least one side of a positive electrode current collector to obtain a positive electrode sheet; coating a negative electrode slurry onto at least one side of a negative electrode current collector to obtain a negative electrode sheet; assembling the positive electrode sheet, a separator layer, and the negative electrode sheet to obtain the battery, wherein at least one of the positive electrode slurry and the negative electrode slurry is coated using a wet-wet double-layer coating method. In this wet-wet double-layer coating method, a structure with two upper and lower dies and a double discharge port is used, which allows for simultaneous coating of the upper and lower layers. The second coating can fill the edge accumulation of the first layer, making the overall thickness of the electrode more uniform. The double-dies coating can compensate for pressure fluctuations and avoid the generation of stripe defects. The upper coating slurry fills the pores of the lower layer, further promoting the uniform distribution of the coating, effectively improving the flatness of the coated electrode and the flatness of the produced battery. This results in more uniform stress on the battery, more uniform ion transport and ion flux during cycling, better capacity utilization, and higher rate performance.

[0012] According to embodiments of this application, the above method satisfies at least one of the following conditions: The solid content of the positive electrode slurry is 70%~80%; The fineness of the positive electrode slurry is 10~15μm; The positive electrode slurry 50s -1 Viscosity is 300~800 mPa·s; The double-sided areal density of the positive electrode is 420~450 g·m³. -2 ; The separator layer is an electrolyte layer.

[0013] According to embodiments of this application, the above method satisfies at least one of the following conditions: The solid content of the negative electrode slurry is 40%~50%; The fineness of the negative electrode slurry is 5~10μm; The negative electrode slurry 50s -1 Viscosity is 100~500 mPa·s; The areal density of the negative electrode is 170~190 g·m³. -2 .

[0014] A third aspect of this application provides a method for evaluating the flatness of a battery. According to an embodiment of this application, the method includes: measuring the thickness of a surface dot matrix on at least one surface of the battery to obtain thickness data containing multiple thickness values, wherein the dot density of the surface dot matrix is ​​≥0.1 dots / cm². 2 Determine the a-th percentile T of the thickness data. a The bth percentile T b 50th percentile T50 The surface thickness distribution coefficient SPAN(ab) of the battery was calculated and obtained as follows: (T) a -T b ) / T 50 , a+b=100; if the surface thickness distribution coefficient SPAN(ab) of the battery satisfies at least one of the following conditions (1) to (6), then the flatness of the battery is qualified; otherwise, the flatness of the battery is unqualified. SPAN (100) ≤ 4.11%; SPAN (90) ≤ 1.73%; SPAN (80) ≤ 1.24%; SPAN (70) ≤ 0.99%; SPAN (60) ≤ 0.80%; SPAN(50)≤0.64%.

[0015] This method effectively captures the surface thickness distribution coefficient (SPAN) of the battery. The SPAN index can eliminate extreme data points at the beginning and end, avoiding interference from outliers. Simultaneously, the SPAN index focuses on intermediate data, more closely reflecting the actual stress area under battery restraint. Furthermore, the battery thickness distribution is directly related to the stress distribution under battery restraint, which directly affects battery performance. Quantifying the flatness by testing the SPAN value allows for a more accurate reflection of differences in battery capacity performance.

[0016] According to an embodiment of this application, the thickness data is obtained by measuring with a coordinate measuring machine; and at least one of the following conditions is met: The coordinate measuring machine uses a dot matrix scanning method for measurement. The probe sampling interval of the coordinate measuring machine is 0.01cm~1cm; The probe moving speed of the coordinate measuring machine is 40~80mm / s; The accuracy of the coordinate measuring machine is ±2μm; The testing temperature of the coordinate measuring machine is 25℃.

[0017] In a fourth aspect, this application provides a battery device. According to an embodiment of this application, the battery device includes the battery described above. This battery device has good battery life and fast charging performance.

[0018] In a fifth aspect, this application provides an electrical device. According to embodiments of this application, the electrical device includes the battery or battery device described above. This electrical device has good battery life and fast charging performance. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a battery according to an embodiment of this application.

[0020] Figure label: 10: Large surface area; 20: Overhang area; 30: Positive electrode tab; 40: Negative electrode tab. Detailed Implementation

[0021] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0022] This application is based on the inventor's discoveries and understanding of the following facts and problems: As mentioned earlier, solid-state batteries require high external restraint forces (typically >3MPa) to maintain stable interfacial contact; therefore, the surface flatness of solid-state batteries has a significant impact on their performance. Thus, establishing a reasonable and accurate flatness quantification standard is crucial for ensuring the reliability of solid-state batteries. Through in-depth research and analysis, the inventors have proposed a battery flatness quantification index and control standard based on the surface thickness distribution coefficient (SPAN) value. Batteries that meet the SPAN value requirements exhibit higher capacity and better rate performance.

[0023] In view of this, a first aspect of this application provides a battery. According to an embodiment of this application, the surface thickness distribution coefficient SPAN(ab) of the battery is = (T a -T b ) / T 50 At least one of the following conditions must be met: (1)SPAN(100)≤4.11%; (2)SPAN(90)≤1.73%; (3)SPAN(80)≤1.24%; (4)SPAN(70)≤0.99%; (5)SPAN(60)≤0.80%; (6)SPAN(50)≤0.64%; Among them, T a This represents the a-th percentile of the battery thickness data. T b This represents the b-th percentile of the battery thickness data. T 50 This represents the 50th percentile of the battery thickness data. a + b = 100; The thickness data includes multiple thickness values ​​corresponding to the surface dot matrix of at least one surface of the battery, wherein the dot density of the surface dot matrix is ​​≥0.1 dots / cm. 2 .

[0024] Specifically, the surface thickness distribution coefficient (SPAN) of the battery can eliminate extreme data and avoid interference from outliers. Simultaneously, the SPAN value focuses on intermediate data, more closely reflecting the actual stress area under battery constraint. Furthermore, the SPAN value is directly related to the stress distribution under battery constraint, which directly impacts battery performance. The SPAN value can more accurately reflect differences in battery capacity and rate performance. In the battery of this application, by controlling the SPAN value to meet the above requirements, the battery exhibits high flatness, thereby improving the uniformity of stress distribution. This results in more uniform ion transport and ion flux during cycling, avoiding excessively high local current density, improving the overall utilization rate of active materials, and ultimately leading to higher battery capacity and better rate performance.

[0025] It is understood that the battery can satisfy any one, any two, any three, any four, any five, or all six of the above conditions (1) to (6). In some embodiments, the battery satisfies the above conditions (1) to (6) simultaneously. As a result, the flatness of the battery is further improved, and its capacity and rate performance are also further enhanced.

[0026] In this article, the a percentile of battery thickness data means that a% of the battery thickness data is less than or equal to that value. Similarly, the b percentile of battery thickness data means that b% of the battery thickness data is less than or equal to that value, and the 50th percentile of battery thickness data means that 50% of the battery thickness data is less than or equal to that value.

[0027] According to embodiments of this application, 50 ≤ ab ≤ 100, specifically, 70 ≤ ab ≤ 90. As an example, ab can specifically be 50, 60, 70, 80, 90, 100, or any range between two of them. Therefore, the surface thickness distribution coefficient SPAN value focuses more on intermediate data, more closely reflecting the actual stress area under battery restraint, eliminating extreme data, and avoiding interference from outliers. This allows for a more accurate reflection of the battery's true flatness, and consequently, a more accurate evaluation of the battery's overall performance.

[0028] According to the embodiments of this application, 75 ≤ a ≤ 100. Specifically, a can be 75, 80, 85, 90, 95, 100, or any two of them. This allows for a closer approximation of the actual stress area under battery restraint, eliminating extreme data and avoiding interference from abnormal points. Consequently, it can more accurately reflect the true flatness of the battery, thus improving the overall performance of the battery.

[0029] According to an embodiment of this application, 0 ≤ b ≤ 25. Specifically, b can be 0, 5, 10, 15, 20, 25, or any two of them. This more closely approximates the actual stress area under battery restraint, more accurately reflecting the battery's true flatness, and thus more accurately evaluating the battery's overall performance.

[0030] It is understandable that the more thickness data of the battery, the more accurately the surface thickness distribution coefficient (SPAN) can reflect the flatness of the battery. In some embodiments, the dot density of the surface lattice is ≥1 dot / cm². 2 As an example, the point density can be 1 point / cm². 2 ~200 pieces / cm 2 Specifically, such as 1 per cm 2 10 pieces / cm 2 20 pieces / cm 2 50 pieces / cm 2 80 pieces / cm 2 100 pieces / cm 2 120 pieces / cm 2 150 pieces / cm 2 180 pieces / cm 2 200 pieces / cm 2 Or the range between either or both. This allows for accurate reflection of the battery's flatness and facilitates measurement.

[0031] According to embodiments of this application, the thickness can be tested at any location on the battery, meaning the surface dot matrix can be located at any position on the battery surface. In some embodiments, the battery includes two large surfaces (referring to the rectangular main area on the electrode sheet coated with electrode material, i.e., the core working area after removing special structures such as tabs, empty foil areas, and overhang areas) and two narrow surfaces arranged opposite each other. The area of ​​the large surfaces is larger than the area of ​​the narrow surfaces, and the surface dot matrix is ​​located on at least one large surface of the battery. This allows for better removal of abnormal data, avoidance of interference from abnormal points, and facilitates measurement. In some embodiments, if the overhang area is filled flat, the large surface can extend to the overhang area, i.e., include the overhang area.

[0032] In some embodiments, the battery includes an electrode core and a casing (e.g., an aluminum-plastic film). The thickness test can be performed on the surface of the electrode core (i.e., the surface dot matrix is ​​located on the surface of the electrode core) or on the surface of the casing (i.e., the surface dot matrix is ​​located on the surface of the casing). As an example, Figure 1 The battery surface 10 is shown (including the overhang area 20).

[0033] It is understandable that the dots in the surface dot matrix should be distributed as evenly as possible on the battery surface; the higher the dot density, the more accurate the test results. The specific test area and dot density can be flexibly selected according to actual needs. In some embodiments, the distance between two adjacent dots in the surface dot matrix does not exceed 1 cm, specifically 0.01 cm to 1 cm, such as 0.01 cm, 0.05 cm, 0.10 cm, 0.20 cm, 0.30 cm, 0.40 cm, 0.50 cm, 0.60 cm, 0.70 cm, 0.80 cm, 0.90 cm, 1 cm, or any range between two of these. Therefore, with a suitable dot density, the thickness data of the battery surface can be collected.

[0034] According to the embodiments of this application, it can be understood that there is no particular limitation on the specific type of battery, which can be a primary battery or a secondary battery; the shape of the battery can be a square battery, and according to the outer packaging, the battery can be a hard-shell battery, a soft-pack battery, etc.

[0035] In some embodiments, the battery may include a positive electrode, a negative electrode, a separator, and an outer packaging. The positive electrode, negative electrode, and separator can be manufactured into a cell using a winding or stacking process, and the cell can be housed in the outer packaging. The positive and negative electrode sheets are alternately stacked, and the separator is disposed between adjacent positive and negative electrode sheets.

[0036] In some embodiments, the positive electrode sheet includes a positive current collector and a positive electrode material layer disposed on at least one side of the positive current collector. In some embodiments, the positive electrode material layer may include a positive electrode binder, a positive electrode conductive agent, and a positive electrode active material, and may also include additives with specific functions and effects, such as thickeners, sodium supplements, film-forming additives, flame retardants, high-temperature / low-temperature stabilizers, etc., as needed.

[0037] In some embodiments, the positive current collector can be a metal current collector or a composite current collector. For example, metal current collectors include, but are not limited to, aluminum foil current collectors; composite current collectors may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0038] As an example, positive electrode active materials may include lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium manganese oxide, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate, lithium nickel manganese oxide, lithium-rich manganese-based materials, or positive electrode active materials commonly used in the art.

[0039] As an example, the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), hydrogenated nitrile butadiene rubber (HNBR), ethylene-tetrafluoroethylene-propylene terpolymer, ethylene-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0040] As an example, the positive electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0041] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode material layer disposed on at least one side of the negative electrode current collector.

[0042] As an example, the negative electrode material layer may include a negative electrode active material, a thickener, a negative electrode conductive agent, and a negative electrode binder.

[0043] According to embodiments of this application, the negative electrode current collector can be a metal foil, such as copper foil, carbon-coated copper foil, etc.

[0044] According to embodiments of this application, the negative electrode active material may include graphite, silicon-carbon materials, silicon-oxygen materials, elemental silicon, etc.

[0045] According to embodiments of this application, the negative electrode binder may include, but is not limited to, polyvinylidene fluoride (PVDF) and sodium carboxymethyl cellulose (CMC). At least one of Na, polyvinylpyrrolidone, polytetrafluoroethylene, styrene-butadiene rubber (SBR), and hydrogenated nitrile butadiene rubber (HNBR).

[0046] According to embodiments of this application, the negative electrode conductive agent may include, but is not limited to, conductive carbon black, Super C. At least one of acetylene black, Ketjen black, and carbon nanofibers.

[0047] According to embodiments of this application, the separator layer can be a membrane or an electrolyte layer. Specifically, the electrolyte layer can include a solid electrolyte, and the type of solid electrolyte is not particularly limited, including but not limited to sulfide electrolytes, oxide electrolytes, etc.

[0048] A second aspect of this application provides a method for preparing the aforementioned battery. According to an embodiment of this application, the method includes: coating a positive electrode slurry onto at least one side of a positive electrode current collector to obtain a positive electrode sheet; coating a negative electrode slurry onto at least one side of a negative electrode current collector to obtain a negative electrode sheet; assembling the positive electrode sheet, a separator layer, and the negative electrode sheet to obtain the battery, wherein at least one of the positive electrode slurry and the negative electrode slurry is coated using a wet-wet double-layer coating method. In this wet-wet double-layer coating method, a dual-die and dual-outlet structure is used, allowing for simultaneous coating of the upper and lower layers. The second layer coating fills the edge accumulation of the first layer, making the overall thickness of the electrode sheet more uniform. The dual-die coating compensates for pressure fluctuations, avoiding the generation of stripe-like defects. The upper coating slurry fills the pores of the lower layer, further promoting the uniform distribution of the coating, effectively improving the flatness of the coated electrode sheet and the flatness of the produced battery, thereby making the battery more uniformly stressed, with more uniform ion transport and ion flux during cycling, resulting in better capacity utilization and higher rate performance.

[0049] According to embodiments of this application, the solid content of the positive electrode slurry is 70% to 80%, specifically 70%, 72%, 74%, 76%, 78%, 80%, or any range between two of these. This facilitates coating and film formation, and results in a film layer with high flatness, thereby improving the flatness of the battery.

[0050] According to embodiments of this application, the fineness of the positive electrode slurry is 10μm to 15μm, specifically 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, or any range between two of these. This improves the flatness of the battery, thereby enhancing its capacity and rate performance.

[0051] According to an embodiment of this application, the positive electrode slurry has a 50s... -1 The viscosity is 300 mPa·s to 800 mPa·s, specifically 300 mPa·s, 400 mPa·s, 500 mPa·s, 600 mPa·s, 700 mPa·s, 800 mPa·s, or any two of these ranges. Therefore, the above viscosity is beneficial for the formation of the cathode slurry film, and the resulting film has high flatness, which in turn helps improve the flatness of the battery.

[0052] In this article, 50s -1 Viscosity refers to the viscosity at a shear rate of 50 s / s. -1 The viscosity of a fluid is measured under the following conditions. It can be measured using a cone-plate viscometer or similar device.

[0053] According to an embodiment of this application, the bifacial areal density of the positive electrode is 420 g·m³. -2 ~450g·m -2 Specifically, such as 420g·m-2 425g·m -2 430g·m -2 435g·m -2 440g·m -2 445g·m -2 450g·m -2 Or a range between or any two of them. Therefore, the aforementioned areal density helps improve the flatness of the positive electrode sheet, thereby improving the flatness of the battery.

[0054] According to embodiments of this application, the solid content of the negative electrode slurry is 40% to 50%, specifically 40%, 42%, 44%, 46%, 48%, 50%, or any range between two of these. This facilitates coating and film formation, and results in a film layer with high flatness, thereby improving the flatness of the battery.

[0055] According to embodiments of this application, the fineness of the negative electrode slurry is 5μm to 10μm, specifically 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, or any range between two of these. This improves the flatness of the battery, thereby enhancing its capacity and rate performance.

[0056] According to an embodiment of this application, the negative electrode slurry has a 50s... -1 The viscosity ranges from 100 mPa·s to 500 mPa·s, specifically 100 mPa·s, 150 mPa·s, 200 mPa·s, 250 mPa·s, 300 mPa·s, 350 mPa·s, 400 mPa·s, 450 mPa·s, 500 mPa·s, or any combination thereof. Therefore, the above viscosity is beneficial for the formation of the negative electrode slurry film, and the resulting film has high flatness, which in turn helps improve the flatness of the battery.

[0057] According to an embodiment of this application, the double-sided areal density of the negative electrode is 170 g·m³. -2 ~190g·m -2 Specifically, such as 170g·m -2 172g·m -2 175g·m -2 178g·m -2 180g·m -2 182g·m -2 185g·m -2 188g·m -2 190g·m -2 Or a range between or any two of them. Therefore, the aforementioned areal density helps improve the flatness of the negative electrode sheet, thereby improving the flatness of the battery.

[0058] In one specific implementation, solid-state batteries can be prepared using the following method: (1) Preparation of positive electrode sheet: The positive electrode active material, positive electrode conductive agent and positive electrode binder are dispersed in a solvent to form a positive electrode slurry; the positive electrode slurry is coated on both sides of the positive electrode current collector by wet double layer coating method, and the positive electrode sheet is obtained after drying, rolling and cutting. (2) Preparation of negative electrode sheet: The negative electrode active material, negative electrode conductive agent and negative electrode binder are dispersed in a solvent to form a negative electrode slurry. The negative electrode slurry is coated on one side of the negative electrode current collector by wet double coating method. Ceramic particles and binder are dispersed in a solvent to form a ceramic slurry. The ceramic slurry is coated on the other side of the negative electrode current collector. After drying, rolling and cutting, the negative electrode sheet is obtained. (3) Preparation of solid electrolyte layer: The solid electrolyte and binder are dispersed in a solvent to form a solid electrolyte layer slurry. The solid electrolyte layer slurry is coated on the substrate and dried to form a solid electrolyte layer.

[0059] (4) The solid electrolyte layer is transferred from the substrate surface to the surface of the negative electrode sheet, including the negative electrode active material layer.

[0060] (5) Battery assembly: The negative electrode and positive electrode, including the solid electrolyte layer, are stacked alternately, with the solid electrolyte layer located between the negative electrode and the positive electrode, and the negative electrode located on the outermost side of the battery. After encapsulation, isostatic pressing is performed to obtain a solid battery.

[0061] A third aspect of this application provides a method for evaluating the flatness of a battery. According to an embodiment of this application, the method includes: measuring the thickness of a surface dot matrix on at least one surface of the battery to obtain thickness data containing multiple thickness values, wherein the dot density of the surface dot matrix is ​​≥0.1 dots / cm². 2 Determine the a-th percentile T of the thickness data. a The bth percentile T b 50th percentile T 50 The surface thickness distribution coefficient SPAN(ab) of the battery was calculated and obtained as follows: (T) a -T b ) / T 50 , a+b=100; if the surface thickness distribution coefficient SPAN(ab) of the battery satisfies at least one of the following conditions (1) to (6), then the flatness of the battery is qualified; otherwise, the flatness of the battery is unqualified. (1)SPAN(100)≤4.11%; (2)SPAN(90)≤1.73%; (3)SPAN(80)≤1.24%; (4)SPAN(70)≤0.99%; (5)SPAN(60)≤0.80%; (6)SPAN(50)≤0.64%.

[0062] This method effectively captures the battery surface thickness distribution coefficient (SPAN). The SPAN index can eliminate extreme data points at the beginning and end, avoiding interference from outliers. Simultaneously, the SPAN index focuses on intermediate data, more closely reflecting the actual stress area under battery restraint. Furthermore, the battery thickness distribution is directly related to the stress distribution under battery restraint, which directly affects battery performance. Quantifying the flatness by testing the SPAN value allows for a more accurate reflection of differences in battery capacity performance.

[0063] According to embodiments of this application, the thickness data can be obtained by using a coordinate measuring machine (CMM). It is understood that this application does not particularly limit the specific measurement method, and it can be performed according to the operating instructions of the CMM.

[0064] In some embodiments, the coordinate measuring machine uses a dot-matrix scanning method. This facilitates the acquisition of more measurement data, thereby improving the accuracy of the measurement results.

[0065] In some embodiments, the probe sampling interval of the coordinate measuring machine is 0.01cm to 1cm. This results in a suitable sampling density, which can accurately reflect the flatness of the battery while facilitating measurement.

[0066] In some embodiments, the probe movement speed of the coordinate measuring machine is 40 mm / s to 80 mm / s. This allows for both measurement efficiency and accuracy.

[0067] In some embodiments, the coordinate measuring machine has an accuracy of ±2 μm. This results in more accurate test results.

[0068] In some embodiments, the coordinate measuring machine is tested at a temperature of 25°C. This facilitates operation.

[0069] In a fourth aspect, this application provides a battery device. According to an embodiment of this application, the battery device includes the battery described above. This battery device has good battery life and fast charging performance.

[0070] According to embodiments of this application, the battery device can be a battery pack, a battery module, a chassis (e.g., a CTC integrated chassis, a skateboard chassis, etc.).

[0071] According to an embodiment of this application, the battery pack includes a plurality of batteries that can be stacked or disposed within a housing; the battery pack includes a housing, within which a plurality of batteries or at least one battery pack is disposed; the chassis includes a chassis frame, within which a plurality of batteries or at least one battery pack or at least one battery pack is disposed.

[0072] In a fifth aspect, this application provides an electrical device. According to embodiments of this application, the electrical device includes the battery or battery device described above. This electrical device has good battery life and fast charging performance.

[0073] According to embodiments of this application, the specific type of electrical device is not particularly limited and can be any device that uses a battery or battery device as a power source or energy storage unit. As examples, electrical devices include, but are not limited to, electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), mobile terminals (e.g., mobile phones, laptops, game consoles, wearable devices, etc.), drones, aerospace equipment, satellites, ships, energy storage systems, etc.

[0074] It is understood that, in addition to the battery or battery device mentioned above, the electrical device also includes necessary structures and components, all of which can be made with reference to conventional technologies. For example, an electric vehicle may include a body, chassis, tires, navigation system, radar system, steering system, braking system, lubrication system, cooling system, driving system, etc., which will not be described in detail here.

[0075] The embodiments of this application are described in detail below.

[0076] Example 1 Solid-state battery fabrication: (1) Pure silicon, conductive agent acetylene black, and binder CMC were dispersed in water at a mass ratio of 97.5:0.5:2 to obtain a solid content of 42%, a fineness of 8μm, and a 50s s content of 50μm. -1 A negative electrode slurry with a viscosity of 300 mPa·s was coated onto both sides of the copper foil of the negative electrode current collector using a wet-wet double-layer coating method. After drying and rolling, a layer of negative electrode active material was formed, resulting in a negative electrode sheet with a double-sided areal density of 188.26 g·m³. -2 .

[0077] The positive electrode active material, single-crystal ternary NCM811, the conductive agent, acetylene black, and the binder, HNBR, were dispersed in xylene solvent at a mass ratio of 94.5:0.5:5 to obtain a solid content of 75%, a fineness of 12 μm, and a 50s solids content. -1A positive electrode slurry with a viscosity of 500 mPa·s was coated onto both sides of a positive electrode current collector aluminum foil using a single-layer coating method. After drying and rolling, a positive electrode sheet was obtained with a double-sided areal density of 448.13 g·m³. -2 .

[0078] The sulfide electrolyte Li6PS5Cl (LPSCl) and binder SBR are dispersed in xylene solvent at a mass ratio of 99:1 to obtain a solid electrolyte layer slurry with a solid content of 60%. The solid electrolyte layer slurry is coated on the surface of an aluminum foil substrate and dried to form a solid electrolyte layer. The solid electrolyte layer is then transferred from the aluminum foil substrate to the surface of the active material layer of the negative electrode.

[0079] A negative electrode sheet including a solid electrolyte layer, a positive electrode sheet, and another negative electrode sheet including a solid electrolyte layer are stacked sequentially, with the solid electrolyte layer located between the negative electrode sheet and the positive electrode sheet to obtain an electrode assembly. The electrode assembly is then packaged in an aluminum-plastic film and subjected to isostatic pressing at 80°C and 500 MPa to obtain a solid-state battery.

[0080] Examples 2-6, Comparative Examples 1-2 The preparation method is basically the same as that of the solid-state battery in Example 1. The difference lies in the coating method and areal density of the positive / negative electrodes, as detailed in Table 1.

[0081] Table 1

[0082] Performance testing: 1. Slurry fineness: Drop a small amount of slurry onto the deeper end of the fineness tester groove. Hold the scraper and scrape the slurry from the deeper part of the groove to the shallower part at a uniform speed, so that the slurry fills the groove and is leveled. The position where obvious particle aggregation or scratches first appear in the groove is taken as the fineness value. The same slurry should be tested at least 3 times and the average value should be taken.

[0083] 2. Slurry 50s -1 Viscosity: The slurry was dropped onto the disk of the rotary viscometer. The test was started with the rotor rotating at 50 rpm. The rotor was vertically immersed in the slurry sample cup up to the designated mark. After the reading stabilized, the data was recorded, and the slurry 50s sample was obtained. -1 Viscosity value.

[0084] 3. Surface density: At different positions in the transverse (perpendicular to the coating direction) and longitudinal direction of the electrode, punching machines are used to punch out electrode discs and foil discs with a diameter of 18mm. At least 20 electrode discs are punched out. The mass of each individual electrode disc and foil disc is weighed, and the average value is calculated using the formula: areal density (g / m²) = [mass of electrode disc (g) - mass of foil disc (g)] / disc area (m²). This average value is the electrode areal density.

[0085] 4. Surface thickness distribution coefficient test of solid-state batteries: The solid-state battery was placed vertically and fixed in place. The probe of the coordinate measuring machine was adjusted to contact the surface of the solid-state battery, and the flatness of the dot matrix was scanned. The probe sampling interval was 0.05 mm, and the dot density was 120 dots / cm². 2 The moving speed is 60mm / s, the accuracy is ±2μm, the test temperature is 25℃, the X / Y / Z axis travel distance is ≥2×2×1.5mm, the thickness data of all matrix points is recorded, and the following calculations are performed: , , , , , .

[0086] 5. Electrical performance testing of solid-state batteries: Five solid-state batteries from each embodiment and comparative example were taken and tested in the Ruineng secondary battery performance testing cabinet. The solid-state batteries were charged to 4.2V at 0.1C and discharged to 2.0V at 0.1C. The specific capacity of the positive electrode was calculated and recorded as Q1. Then, the batteries were charged to 4.2V at 0.5C and discharged to 2.0V at 0.1C. The specific capacity of the positive electrode was calculated and recorded as Q2. The discharge capacity at 0.5C / 0.1C is Q1 / Q2×100% and recorded as the rate performance.

[0087] Table 2

[0088] Table 3

[0089] As can be seen from Examples 1-3 and Comparative Examples 1-2, when both the positive and negative electrodes use wet-wet double-layer coating, the smaller the surface thickness distribution coefficient SPAN value of the solid-state battery, the better the flatness, which can ensure better stress uniformity of the solid-state battery, higher capacity utilization, and better rate performance.

[0090] As can be seen from Examples 3-6 and Comparative Examples 1-2, a higher areal density allows the active material layer to distribute mechanical stress more evenly during the rolling process, improving flatness. It also results in a higher active material loading per unit area, which reduces interparticle gaps, improves the contact between the active material and the conductive agent, reduces interfacial impedance, and enhances electron / ion conduction. This is beneficial for improving the flatness of the solid-state battery and enhancing its overall electrical performance.

[0091] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0092] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A battery, characterized in that, The surface thickness distribution coefficient SPAN(ab) of the battery = (T a -T b ) / T 50 At least one of the following conditions must be met: SPAN (100) ≤ 4.11%; SPAN (90) ≤ 1.73%; SPAN (80) ≤ 1.24%; SPAN (70) ≤ 0.99%; SPAN (60) ≤ 0.80%; SPAN (50) ≤ 0.64%; Among them, T a This represents the a-th percentile of the battery thickness data. T b This represents the b-th percentile of the battery thickness data. T 50 This represents the 50th percentile of the battery thickness data. a + b = 100; The thickness data includes multiple thickness values ​​corresponding to the surface dot matrix of at least one surface of the battery, wherein the dot density of the surface dot matrix is ​​≥0.1 dots / cm. 2 .

2. The battery according to claim 1, characterized in that, 50≤ab≤100, or 70≤ab≤90.

3. The battery according to claim 1 or 2, characterized in that, At least one of the following conditions must be met: 75≤a≤100； 0≤b≤25。 4. The battery according to any one of claims 1 to 3, characterized in that, The dot density of the surface lattice is 1 dot / cm². 2 ~200 pieces / cm 2 .

5. The battery according to any one of claims 1 to 4, characterized in that, It includes two large surfaces and two narrow surfaces arranged opposite each other, the area of ​​the large surfaces is larger than the area of ​​the narrow surfaces, and the surface dot matrix is ​​located on at least one of the large surfaces of the battery.

6. The battery according to any one of claims 1 to 5, characterized in that, The distance between any two adjacent points of the surface dot matrix does not exceed 1 cm.

7. A method for preparing the battery according to any one of claims 1 to 6, characterized in that, include: A positive electrode slurry is coated on at least one side of a positive electrode current collector to obtain a positive electrode sheet; A negative electrode slurry is coated on at least one side of a negative electrode current collector to obtain a negative electrode sheet; The positive electrode, the separator layer, and the negative electrode are assembled to obtain the battery. At least one of the positive electrode slurry and the negative electrode slurry is coated using a wet-wet double-layer coating method.

8. The method according to claim 7, characterized in that, At least one of the following conditions must be met: The solid content of the positive electrode slurry is 70%~80%; The fineness of the positive electrode slurry is 10~15μm; The positive electrode slurry 50s -1 Viscosity is 300~800 mPa·s; The double-sided areal density of the positive electrode is 420~450 g·m³. -2 ; The separator layer is an electrolyte layer.

9. The method according to claim 7 or 8, characterized in that, At least one of the following conditions must be met: The solid content of the negative electrode slurry is 40%~50%; The fineness of the negative electrode slurry is 5~10μm; The negative electrode slurry 50s -1 Viscosity is 100~500 mPa·s; The areal density of the negative electrode is 170~190 g·m³. -2 .

10. A method for evaluating battery flatness, characterized in that, include: The thickness of the surface lattice on at least one surface of the battery is measured to obtain thickness data containing multiple thickness values, wherein the dot density of the surface lattice is ≥0.1 dots / cm. 2 ; Determine the a-th percentile T of the thickness data a The bth percentile T b 50th percentile T 50 The surface thickness distribution coefficient SPAN(ab) of the battery was calculated and obtained as follows: (T) a -T b ) / T 50 a + b = 100; The battery is considered to have acceptable flatness if its surface thickness distribution coefficient SPAN(ab) meets at least one of the following conditions; otherwise, the battery is considered to have unacceptable flatness. SPAN (100) ≤ 4.11%; SPAN (90) ≤ 1.73%; SPAN (80) ≤ 1.24%; SPAN (70) ≤ 0.99%; SPAN (60) ≤ 0.80%; SPAN(50)≤0.64%.

11. The method according to claim 10, characterized in that, The thickness data is obtained by measuring with a coordinate measuring machine; and at least one of the following conditions is met: The coordinate measuring machine uses a dot matrix scanning method for measurement. The probe sampling interval of the coordinate measuring machine is 0.01cm~1cm; The probe moving speed of the coordinate measuring machine is 40~80mm / s; The accuracy of the coordinate measuring machine is ±2μm; The testing temperature of the coordinate measuring machine is 25℃.

12. A battery device, characterized in that, The battery includes any one of claims 1 to 6.

13. An electrical appliance, characterized in that, Includes the battery according to any one of claims 1 to 6 or the battery device according to claim 12.

Images