Solid-state battery density detection method, solid-state battery, and electric device

Abstract

The application relates to a solid-state battery density detection method, a solid-state battery and an electric device. The solid-state battery density detection method comprises the following steps: pre-pressing a sample solid-state battery in a thickness direction; performing isostatic pressing on the sample solid-state battery under different isostatic pressure conditions; in each case after performing isostatic pressing on the sample solid-state battery under a corresponding isostatic pressure condition, obtaining a hardness value of a preset position on a surface of the sample solid-state battery, and obtaining an actual density of the sample solid-state battery; and fitting a functional relationship between the actual density of the sample solid-state battery and the hardness value of the preset position and a ratio of a theoretical density of the sample solid-state battery. The solid-state battery density detection method can efficiently and non-destructively detect the density of a batch of solid-state batteries, improves the detection efficiency of the density of the batch of solid-state batteries, and is beneficial to large-scale application.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method for detecting the density of a solid-state battery, a solid-state battery, and an electrical device. Background Technology

[0002] With the popularization and promotion of new energy vehicles, their charging and discharging performance and range have increasingly attracted people's attention and importance. As the power energy source for new energy vehicles, power batteries are widely used.

[0003] Solid-state batteries, as one of the future development trends of power batteries, have the advantages of high energy density and good safety. The density of solid-state batteries affects their charge and discharge performance.

[0004] In related technologies, determining the density of a solid-state battery requires first performing destructive operations such as stamping, then measuring the density and porosity of the stamped material to determine the battery's density. Because measuring the density of a solid-state battery requires destructive operations like stamping, it is only suitable for small-sample inspections and is difficult to apply to batch testing. Summary of the Invention

[0005] This application addresses the problem that current methods for detecting the density of solid-state batteries are difficult to apply to the batch testing of solid-state batteries. To this end, this application provides a method for detecting the density of solid-state batteries, a solid-state battery, and an electrical device.

[0006] In a first aspect, this application provides a method for detecting the density of a solid-state battery, comprising the following steps:

[0007] The solid-state battery sample was pre-compressed along the thickness direction;

[0008] The sample solid-state battery was subjected to isostatic pressure treatment under different isostatic pressure conditions, including one or more of isostatic pressure, isostatic pressure time, and isostatic pressure ambient temperature.

[0009] After each isostatic pressing process is performed on the sample solid-state battery under corresponding isostatic pressing conditions, the hardness value at a preset position on the surface of the sample solid-state battery is obtained, and the actual density of the sample solid-state battery is obtained.

[0010] Fit the functional relationship between the ratio of the actual density of the sample solid-state battery to the theoretical density of the sample solid-state battery and the hardness value at the preset location;

[0011] The hardness value at a preset location on the solid-state battery under test is obtained, and the density of the solid-state battery under test is determined based on the functional relationship.

[0012] The solid-state battery density detection method according to the first aspect of this application has at least the following beneficial effects:

[0013] The solid-state battery density detection method of this application pre-compresses the sample solid-state battery along its thickness direction, ensuring a tight and stable connection between the positive electrode, solid electrolyte, and negative electrode within the sample solid-state battery. This maintains the sample solid-state battery in a relatively compact state for subsequent transfer and isostatic pressing operations. By performing isostatic pressing on the sample solid-state battery under different conditions, varying degrees of densification are achieved, providing a data basis for subsequently fitting the functional relationship between the ratio of the actual density to the theoretical density of the sample solid-state battery and the hardness value at a preset location. By fitting this functional relationship, the density of the solid-state battery can be obtained by directly measuring its hardness value. This method enables efficient and non-destructive detection of the density of batch solid-state batteries, improving the detection efficiency and facilitating large-scale applications.

[0014] In some embodiments, by fitting a functional relationship between the ratio of the actual density of the sample solid-state battery to the theoretical density of the sample solid-state battery and the hardness value at the preset location, a correlation coefficient between the ratio of the actual density of the sample solid-state battery to the theoretical density of the sample solid-state battery and the hardness value at the preset location is calculated.

[0015] Thus, by calculating the correlation coefficient between the ratio of the actual density to the theoretical density of the sample solid-state battery and the hardness value at the preset location, it is possible to further verify whether there is a high linear positive correlation between the density and hardness of the solid-state battery. This provides strong data support for obtaining the density of the solid-state battery by directly measuring its hardness value based on this functional relationship, enabling accurate detection of the density of batch solid-state batteries.

[0016] In some embodiments, the step of performing isostatic pressing on the sample solid-state battery includes:

[0017] The sample solid-state battery was placed in an isostatic pressure container;

[0018] The isostatic pressure vessel is filled with an isostatic medium.

[0019] Pressure is applied to the outer periphery of the isostatic container and transmitted to the sample solid-state battery through the isostatic medium, so as to cause the volume of the sample solid-state battery to shrink.

[0020] In this way, the densification process of the solid-state battery sample is achieved, further improving the tight contact between the positive electrode, solid electrolyte, and negative electrode within the sample. This also keeps the sample solid-state battery in a relatively compact state, reducing the probability of misalignment between the positive and negative electrodes during subsequent transfer and hardness testing. This improves the accuracy of subsequent hardness testing and, consequently, the accuracy of the functional relationship between the density and hardness of the solid-state battery obtained through data fitting.

[0021] In some embodiments, in the step of isostatic pressing the sample solid-state battery, the isostatic pressure is 200 MPa to 2000 MPa, the isostatic pressing time is 5 min to 30 min, and the isostatic pressing ambient temperature is 25°C to 300°C.

[0022] In this way, by applying pressure evenly to all parts of the solid-state battery sample through an isostatic medium, the length, thickness and width of the solid-state battery sample are uniformly reduced, thereby improving the densification effect of the solid-state battery sample and reducing the probability of structural damage to the solid-state battery sample, thus improving the accuracy of subsequent hardness testing of the solid-state battery sample.

[0023] In some embodiments, in the step of isostatically pressing the sample solid-state battery, the isostatic medium is one of esters, water, and inert gas.

[0024] In this way, the esters, water, and inert gas filled in the isostatic container will not compress themselves, but will uniformly transmit pressure to the solid-state battery in all directions toward the sample solid-state battery, causing the sample solid-state battery to shrink uniformly and improving the densification effect of the sample solid-state battery.

[0025] In some embodiments, prior to the step of isostatic pressing the sample solid-state battery, an isostatic film is encapsulated on the surface of the sample solid-state battery.

[0026] This reduces the likelihood of the liquid isostatic medium contaminating the solid-state battery sample, indirectly improving the accuracy of subsequent hardness testing of the solid-state battery sample.

[0027] In some embodiments, the encapsulation process of sealing an isostatic film on the surface of the sample solid-state battery includes one of heat sealing, ultrasonic roll welding, and laser welding.

[0028] In this way, the isostatic membrane can form a stable surface bond with each surface of the sample solid-state battery, thereby improving the sealing and protection effect of the isostatic membrane on the sample solid-state battery.

[0029] In some embodiments, the isostatic membrane is one of aluminum-plastic film, polyethylene film, polypropylene film, polyvinyl chloride film, and polyethylene terephthalate.

[0030] This gives the isostatic membrane good oil resistance, water resistance and oxidation resistance, improving the protective effect of the isostatic membrane on the solid-state battery sample, and correspondingly reducing the possibility of liquid isostatic medium contaminating the solid-state battery sample.

[0031] In some embodiments, in the step of obtaining the hardness value at a preset location on the surface of the sample solid-state battery, the preset location includes one of the large surface area, the side surface area, and the thinned area of ​​the sample solid-state battery.

[0032] Therefore, after each isostatic pressing process under corresponding isostatic pressure conditions is performed on the sample solid-state battery, the preset position for hardness testing of the sample solid-state battery needs to remain consistent. This preset position can be one of the large surface area, side surface area, and thinning area of ​​the sample solid-state battery, thereby improving the comparability of the obtained hardness values.

[0033] In some embodiments, the step of obtaining the actual density of the sample solid-state battery includes:

[0034] The sample solid-state battery was punched into a circular wafer;

[0035] The mass and volume of the disc are obtained to determine its actual density.

[0036] In this way, the actual density of the sample solid-state battery can be accurately obtained.

[0037] In some embodiments, in the step of pre-compressing the sample solid-state battery along the thickness direction, the pre-compressing pressure is 3 MPa to 20 MPa.

[0038] In this way, while achieving the initial densification effect on the sample solid-state battery, the probability of the sample solid-state battery being damaged by overvoltage is reduced accordingly, thereby improving the accuracy of subsequent hardness testing of the sample solid-state battery.

[0039] Secondly, this application provides a solid-state battery, which is prepared using the solid-state battery density detection method described above.

[0040] Thirdly, this application provides an electrical device, which includes the solid-state battery described above.

[0041] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0042] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0043] Figure 1 This is a schematic diagram of the vehicle structure according to an embodiment of this application.

[0044] Figure 2 This is a schematic diagram of the structure of a sample solid-state battery according to an embodiment of this application.

[0045] Figure 3 This is a flowchart illustrating the solid-state battery density detection method according to an embodiment of this application.

[0046] Figure 4 This is a graph showing the relationship between the density and hardness of a sample solid-state battery according to an embodiment of this application.

[0047] Figure 5 This is a flowchart illustrating step S2 in the solid-state battery density detection method according to an embodiment of this application.

[0048] Figure 6 This is a schematic diagram of the isostatic pressure container used to perform isostatic pressure treatment on a sample solid-state battery, according to an embodiment of this application.

[0049] Figure 7 This is a flowchart illustrating step S6 in the solid-state battery density detection method according to an embodiment of this application.

[0050] Figure 8 This is a schematic diagram of the isostatic membrane structure according to an embodiment of this application.

[0051] Figure 9 This is a cross-sectional structural diagram of a sample solid-state battery according to an embodiment of this application.

[0052] Explanation of reference numerals in the attached drawings: Vehicle 100; Controller 110; Motor 120; Solid-state battery 130; Sample solid-state battery 10; Preset position R; Large area R1; Side area R2; Thinning area R3; Isostatic container 20; Isostatic medium 21; Isostatic membrane 30; Dent 31. Detailed Implementation

[0053] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0055] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0056] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0057] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0058] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0059] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0060] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0061] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0062] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0063] With the popularization and promotion of new energy vehicles, their charging and discharging performance and range have increasingly attracted people's attention and importance. As the power energy source for new energy vehicles, power batteries are widely used.

[0064] Solid-state batteries, as one of the future development trends of power batteries, have the advantages of high energy density and good safety.

[0065] The density of solid-state batteries affects their charge-discharge performance. Currently, determining the density of a solid-state battery requires destructive processes such as stamping, followed by measurement of the stamped density and porosity to determine the battery's density. Because this method involves destructive operations like stamping, it's only suitable for small-sample testing and not for large-scale production.

[0066] Based on the above considerations, and to address the problem that current methods for detecting the density of solid-state batteries are difficult to apply to batch testing of solid-state batteries, this application provides one or more embodiments of a solid-state battery density detection method, a solid-state battery, and an electrical device. In the solid-state battery density detection method, a sample solid-state battery is pre-compressed along its thickness direction, ensuring that the positive electrode, solid electrolyte, and negative electrode within the sample solid-state battery are tightly and stably bonded together along the thickness direction. This maintains the sample solid-state battery in a relatively compact state for subsequent transfer, isostatic pressing, and other operations. By performing isostatic pressing on the sample solid-state battery under different conditions, varying degrees of densification are achieved, providing a data basis for subsequently fitting the functional relationship between the ratio of the actual density to the theoretical density of the sample solid-state battery and the hardness value at a preset location. By fitting a functional relationship between the ratio of the actual density of the sample solid-state battery to its theoretical density and the hardness value at the preset location, the density of the solid-state battery can be obtained by directly measuring its hardness value based on this functional relationship. This allows for efficient and non-destructive detection of the density of batch solid-state batteries, improving the detection efficiency and facilitating large-scale applications.

[0067] The solid-state battery of this application embodiment typically includes: a negative electrode, a solid electrolyte, and a positive electrode. The negative electrode includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer being coated on the surface of the negative electrode current collector.

[0068] The negative electrode current collector can be pure lithium, a lithium alloy, or a lithium metal composite oxide. Lithium alloys are alloy materials, including lithium metal and other metals (such as any one or more of aluminum, magnesium, potassium, sodium, and calcium); lithium metal composite oxides are oxides composed of lithium and other metals (such as silicon, tin, zinc, magnesium, cadmium, cerium, and nickel). The negative electrode current collector may also have a protective layer, which can include any material as long as it has lithium-ion conductivity, does not interfere with battery operation, and does not react with lithium. For example, a ceramic protective layer or a lithium-ion polyacrylic acid protective layer can be provided. Any protective layer can be used for the negative electrode current collector in this application embodiment, as long as the protective layer improves the safety of the negative electrode current collector. The negative electrode active material includes at least one of lithium titanate, silicon anode, silicon-carbon anode, lithium metal anode material, tin-based anode material, and tin oxide anode material.

[0069] In this embodiment of the application, the solid electrolyte may include at least one of sulfide solid electrolyte, oxide solid electrolyte and organic solid electrolyte.

[0070] Sulfide-based solid electrolytes possess high lithium-ion conductivity, readily forming a contact interface between the electrode and the electrolyte, and exhibit high mechanical strength and flexibility. In this application, there are no particular limitations on the type of sulfide-based solid electrolyte, and all known sulfide materials used in the battery field are acceptable.

[0071] Oxide-based solid electrolytes exhibit high safety in air and possess lithium-ion conductivity that is lower than, but relatively higher than, that of sulfide-based solid electrolytes. Furthermore, oxide-based solid electrolytes exhibit high electrochemical safety and mechanical strength, and also have high oxidation voltage. However, solid electrolytes have high grain boundary resistance, making it difficult to form a contact interface between the electrode and the electrolyte, requiring high-temperature heat treatment processes of 1000°C or higher, and these processes are difficult to scale up. In the embodiments of this application, the oxide-based solid electrolyte can be any known oxide material used in the field of lithium batteries.

[0072] Organic solid electrolytes (OSEs) are a type of solid electrolyte. OSEs can readily form electrode interfaces and minimize dendrite growth, thus ensuring stable reactions between OSEs and lithium metal. The disadvantages of OSEs are their relatively low lithium-ion conductivity and the fact that they typically require high-temperature operation. In this embodiment, the OSE comprises polyethylene oxide.

[0073] The positive electrode in this application typically includes a positive current collector and a positive active material layer, with the positive active material layer coated on the surface of the positive current collector.

[0074] The positive electrode current collector can be made of aluminum or stainless steel with a surface treated with carbon, nickel, titanium, or silver, or it can be any of the following: membrane, sheet, foil, mesh, porous body, foam, or nonwoven fabric. The positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc.

[0075] This application provides an electrical device that uses a solid-state battery as a power source. The electrical device can be, but is not limited to, vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc.; spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.

[0076] For ease of explanation, the following embodiments will be described using a vehicle 100 as an example of an electrical device according to an embodiment of this application.

[0077] See Figure 1 Vehicle 100 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A solid-state battery 130 is installed inside vehicle 100, and the solid-state battery 130 can be located at the bottom, front, or rear of vehicle 100. The solid-state battery 130 can be used to power vehicle 100; for example, the solid-state battery 130 can serve as the operating power source for vehicle 100. Vehicle 100 may also include a controller 110 and a motor 120. The controller 110 is used to control the solid-state battery 130 to supply power to the motor 120, for example, to meet the power needs of vehicle 100 during starting, navigation, and driving.

[0078] In some embodiments of this application, the solid-state battery 130 can not only serve as the operating power source for the vehicle 100, but also as the driving power source for the vehicle 100, replacing or partially replacing fuel or natural gas to provide driving force for the vehicle 100.

[0079] See Figure 2 and Figure 3 The solid-state battery density detection method provided in this application includes the following steps:

[0080] S1. Pre-press the sample solid-state battery 10 along the thickness direction;

[0081] S2. The sample solid-state battery 10 is subjected to isostatic pressure treatment under different isostatic pressure conditions, including one or more of isostatic pressure, isostatic pressure time and isostatic pressure ambient temperature.

[0082] S3. After each isostatic pressing process is performed on the sample solid-state battery 10 under the corresponding isostatic pressing conditions, the hardness value of the preset position R on the surface of the sample solid-state battery 10 is obtained, and the actual density of the sample solid-state battery 10 is obtained.

[0083] S4. Fit the functional relationship between the ratio of the actual density of the sample solid-state battery 10 to the theoretical density of the sample solid-state battery 10 and the hardness value of the preset position R.

[0084] S5. Obtain the hardness value of a preset position R on the solid-state battery under test, and determine the density of the solid-state battery under test based on the functional relationship.

[0085] It should be noted that in this application, the sample solid-state battery 10 refers to a conventional pre-molded solid-state battery. Similar to conventional solid-state batteries, the sample solid-state battery 10 has an adhesive film (not shown in the figure) on its large surface and side surfaces. This adhesive film provides structural protection for the surface of the sample solid-state battery 10, reducing the risk of scratches and damage during use.

[0086] In step S1, the sample solid-state battery 10 can be pre-compressed by applying a pressure load to the sample solid-state battery 10 using a flat plate. Specifically, the sample solid-state battery 10 is placed between two pressure plates, and a vertical load is applied to one or both pressure plates using a flat press to achieve the pre-compression treatment of the sample solid-state battery 10.

[0087] In step S1, the sample solid-state battery 10 is pre-pressed to ensure that the positive electrode, solid electrolyte and negative electrode in the sample solid-state battery 10 are tightly and stably connected along the thickness direction of the sample solid-state battery 10. This reduces the probability of the positive electrode and negative electrode being misaligned in the thickness direction of the sample solid-state battery 10, and keeps the sample solid-state battery 10 in a relatively tight state for subsequent transfer, isostatic pressing and other operations.

[0088] Furthermore, by pre-pressing the sample solid-state battery 10, the adhesive film can be more tightly bonded to the corresponding large surface of the sample solid-state battery 10, reducing the risk of the adhesive film detaching from the corresponding large surface of the sample solid-state battery 10 during use.

[0089] In step S2, performing isostatic pressure treatment on the sample solid-state battery 10 under different isostatic pressure conditions means performing isostatic pressure treatment on the sample solid-state battery 10 under multiple different isostatic conditions.

[0090] The isostatic pressing treatment of the sample solid-state battery 10 refers to: based on Pascal's law, placing the sample solid-state battery 10 in a sealed container and filling the sealed container with an isostatic medium (which can be liquid or gas), pressurizing the sealed container through a pressurization system, and utilizing the property of the isostatic medium to uniformly transmit pressure, uniformly pressurizing the sample solid-state battery 10 from all directions, causing the volume of the sample solid-state battery 10 to shrink, thereby achieving densification treatment of the sample solid-state battery 10, effectively eliminating the voids inside the sample solid-state battery 10, and further improving the tight contact effect of the positive electrode, solid electrolyte and negative electrode inside the sample solid-state battery 10. Similarly, the sample solid-state battery 10 is kept in a relatively compact state for subsequent operations such as transfer and hardness testing, making the test results more accurate.

[0091] It should also be noted that in step S2, the isostatic pressure conditions include one or more of isostatic pressure, isostatic pressure time, and isostatic pressure ambient temperature. Isostatic pressure refers to the pressure uniformly applied to the solid-state battery 10 in all directions during the isostatic pressure treatment of the sample solid-state battery 10. Isostatic pressure time refers to the treatment time during which the pressure is uniformly applied to the solid-state battery 10 in all directions during the isostatic pressure treatment of the sample solid-state battery 10. Isostatic pressure ambient temperature refers to the temperature inside the sealed container during the isostatic pressure treatment of the sample solid-state battery 10.

[0092] Different isostatic conditions refer to multiple different isostatic conditions, including the first isostatic condition, the second isostatic condition, ..., the nth isostatic condition. The first isostatic condition may include the first isostatic pressure P1, the first isostatic time t1, and the first isostatic ambient temperature T1. The second isostatic condition may include the second isostatic pressure P2, the second isostatic time t2, and the second isostatic ambient temperature T2, ..., and the nth isostatic condition may include the nth isostatic pressure Pn, the nth isostatic time tn, and the nth isostatic ambient temperature Tn.

[0093] It is easy to understand that after isostatic pressing of the sample solid-state battery 10 under different isostatic pressing conditions, the volume shrinkage of the sample solid-state battery 10 is inconsistent, resulting in inconsistent densification. Correspondingly, the actual density of the sample solid-state battery 10 is also different after isostatic pressing under different isostatic pressing conditions, that is, the density is different.

[0094] In order to control variables and make the data analyzable, in step S3, during the isostatic pressing process of the sample solid-state battery 10 under multiple isostatic pressing conditions, the isostatic pressing time and isostatic pressing temperature are the same for all isostatic pressing conditions, but the isostatic pressing pressure is different for all isostatic pressing conditions, which are variables.

[0095] In step S3, after each isostatic pressing treatment of the sample solid-state battery 10 under the corresponding isostatic pressing condition, the hardness value of the preset position R on the surface of the sample solid-state battery 10 is obtained, and the actual density of the sample solid-state battery 10 is also obtained. This can be understood as follows: after the isostatic pressing treatment of the sample solid-state battery 10 under the first isostatic pressing condition, the hardness value of the preset position R on the surface of the sample solid-state battery 10 at this time is obtained, and the actual density of the sample solid-state battery 10 at this time is detected; after the isostatic pressing treatment of the sample solid-state battery 10 under the second isostatic pressing condition, the hardness value of the preset position R on the surface of the sample solid-state battery 10 at this time is obtained, and the actual density of the sample solid-state battery 10 at this time is detected; and so on.

[0096] In step S3, the process of obtaining the hardness value of a preset position R on the surface of the sample solid-state battery 10 may include the following steps: marking the preset position R on the surface of the sample solid-state battery 10; directly measuring the hardness value of the preset position R using a hardness tester, performing at least six measurements, and taking the average of all hardness values. The preset position R on the surface of the sample solid-state battery 10 can be selected based on actual conditions, such as... Figure 2 The preset position R can be the large surface area R1, the side surface area R2, etc. of the solid-state battery 10. The hardness tester can be, but is not limited to, a Vickers hardness tester, a Rockwell hardness tester, a Brinell hardness tester, a Shore hardness tester, etc. In step S3, after each isostatic pressing treatment under the corresponding isostatic pressing conditions is performed on the sample solid-state battery 10, the hardness is measured at the same preset position R on the surface of the sample solid-state battery 10, thereby improving the comparability of the obtained hardness values.

[0097] In step S3, the actual density of the sample solid-state battery 10 can be obtained in two ways: First, measure the thickness of the sample solid-state battery 10, then punch the solid-state battery 10 into a circular sheet of constant thickness. Measure the mass and diameter of the circular sheet, obtain its volume from the thickness and diameter, and then obtain its density from the mass and volume. This density corresponds to the actual density of the sample solid-state battery 10. Second, directly measure the actual density of the sample solid-state battery 10 using a true density meter.

[0098] It should be further explained that the sample solid-state battery 10 has a theoretical density, which is a known fixed value. The sample solid-state battery 10 has a known theoretical density after it is manufactured and shipped from the factory. The ratio of the actual density of the sample solid-state battery 10 to its theoretical density can be used as the packing density of the sample solid-state battery 10.

[0099] It is understandable that in steps S2 and S3, after each isostatic pressing treatment of the sample solid-state battery 10 under corresponding isostatic pressing conditions, a hardness value at a preset position R of the sample solid-state battery 10 is obtained, and the actual density of the sample solid-state battery 10 is also obtained. After the sample solid-state battery 10 undergoes isostatic pressing treatment under n different static pressing conditions, n hardness values ​​and n actual densities are obtained accordingly.

[0100] In step S4, based on the n hardness values ​​of the sample solid-state battery 10 at the preset position R, the n actual densities of the sample solid-state battery 10, and the n known theoretical densities of the sample solid-state battery 10 obtained in step S3, a functional relationship between the ratio of the actual density to the theoretical density of the sample solid-state battery 10 and the hardness value at the preset position R is established through data fitting. The ratio of the actual density to the theoretical density of the sample solid-state battery 10 is the packing density of the sample solid-state battery 10. Thus, the relationship curve between the packing density of the sample solid-state battery 10 and the hardness value of the sample solid-state battery 10 is obtained. This relationship curve can be obtained through a linear regression model.

[0101] The following specific embodiments further illustrate how to obtain the relationship curve between the density of the sample solid-state battery 10 and the hardness value of the sample solid-state battery 10.

[0102] Based on the above description, let P represent the isostatic pressure of the sample solid-state battery 10 under isostatic pressure treatment, t represent the isostatic pressure time of the sample solid-state battery 10 under isostatic pressure treatment, T represent the isostatic pressure environment temperature of the sample solid-state battery 10 under isostatic pressure treatment, ρA represent the actual density of the sample solid-state battery 10 after isostatic pressure treatment under the corresponding isostatic pressure conditions, ρB represent the theoretical density of the sample solid-state battery 10 after isostatic pressure treatment under the corresponding isostatic pressure conditions, Y represent the ratio of the actual density to the theoretical density of the sample solid-state battery 10, ρA / ρB (which also corresponds to the packing density of the sample solid-state battery), and X represent the hardness value of the sample solid-state battery 10 at its preset position R after isostatic pressure treatment under the corresponding isostatic pressure conditions. This hardness value is obtained by a Shore hardness tester and is expressed as Shore hardness.

[0103] Take six sets of data, see Table 1 below.

[0104]

[0105] Based on the data in Table 1 above, a linear regression model was used to establish a linear functional relationship between Y and X, resulting in Y = 0.0129X + 0.6858. Therefore, see [link to relevant documentation]. Figure 4 The relationship curve between the density of the sample solid-state battery 10 and the hardness value of the sample solid-state battery 10 was obtained.

[0106] It is understandable that by fitting the above data with a linear regression model, it is found that the density of the sample solid-state battery 10 is positively linearly correlated with the hardness value of the sample solid-state battery 10, that is, the higher the hardness of the solid-state battery, the higher its density.

[0107] Thus, in step S5, when it is necessary to test the density of a batch of solid-state batteries, the density of the solid-state battery to be tested can be directly calculated based on the hardness value of the preset position R on the corresponding solid-state battery to be tested, and based on the functional relationship between the density of the sample solid-state battery 10 and the hardness value of the sample solid-state battery 10 obtained in step S4.

[0108] Therefore, it is not necessary to perform individual stamping, thickness measurement, weight measurement, density measurement, or porosity measurement on each batch of solid-state batteries to detect their density. Instead, based on the functional relationship between the density and hardness value of the solid-state battery, the density of the solid-state battery can be obtained by directly measuring the hardness value. This method can efficiently and non-destructively detect the density of batch solid-state batteries, improving the detection efficiency and facilitating large-scale applications.

[0109] As explained above, the solid-state battery density detection method of this application embodiment pre-compresses the sample solid-state battery 10 along its thickness direction, ensuring that the positive electrode, solid electrolyte, and negative electrode within the sample solid-state battery 10 are tightly and stably bonded together along the thickness direction of the sample solid-state battery 10. This maintains the sample solid-state battery 10 in a relatively compact state for subsequent transfer, isostatic pressing, and other operations. By performing isostatic pressing on the sample solid-state battery 10 under different isostatic pressing conditions, the sample solid-state battery 10 achieves different degrees of densification, providing a corresponding data basis for subsequently fitting the functional relationship between the ratio of the actual density to the theoretical density of the sample solid-state battery 10 and the hardness value at a preset position R. By fitting the functional relationship between the ratio of the actual density to the theoretical density of the sample solid-state battery 10 and the hardness value at the preset position R, the density of the solid-state battery can be obtained by directly measuring the hardness value based on this functional relationship. This method can efficiently and non-destructively detect the density of batch solid-state batteries, improving the detection efficiency of batch solid-state battery density and facilitating large-scale applications.

[0110] In some embodiments of this application, the correlation coefficient between the ratio of the actual density of the sample solid-state battery 10 to the theoretical density of the sample solid-state battery 10 and the hardness value of the preset position R is calculated when fitting a functional relationship between the actual density of the sample solid-state battery 10 and the theoretical density of the sample solid-state battery 10 and the hardness value of the preset position R.

[0111] It should be noted that the correlation coefficient between the ratio of the actual density of the sample solid-state battery 10 to the theoretical density of the sample solid-state battery 10 and the hardness value of the preset position R is a measure of the degree of linear correlation between the ratio of the actual density of the sample solid-state battery 10 to the theoretical density of the sample solid-state battery 10 and the hardness value of the preset position R. In this application, the correlation coefficient can also refer to the linear correlation coefficient.

[0112] Specifically, referring to Table 1 above, after obtaining the linear function relationship curves of Y and X based on the above data, the correlation coefficients of Y and X can be obtained using the least squares formula based on the six sets of data in the table, with R... 2 Let R be the correlation coefficient between Y and X. 2 =0.996, indicating a high linear positive correlation between Y and X, which also indicates a high linear positive correlation between the density and hardness of solid-state batteries.

[0113] It should be noted that the least squares formula is as follows: Where X is the hardness of the solid-state battery, Y is the density of the solid-state battery, and n is the number of times the solid-state battery is subjected to isostatic pressing.

[0114] It is understood that the solid-state battery density detection method of this application, after fitting the functional relationship between the ratio of the actual density of the sample solid-state battery 10 to the theoretical density of the sample solid-state battery 10 and the hardness value of the preset position R, can further verify whether there is a high linear positive correlation between the density and hardness of the solid-state battery by calculating the correlation coefficient between the ratio of the actual density of the sample solid-state battery 10 to the theoretical density of the sample solid-state battery 10 and the hardness value of the preset position R. This provides strong data support for obtaining the density of the solid-state battery by directly measuring the hardness value of the solid-state battery based on this functional relationship, and can accurately detect the density of batch solid-state batteries.

[0115] In some embodiments of this application, see Figure 3 , Figure 5 and Figure 6 The steps for isostatic pressing the sample solid-state battery 10 include:

[0116] S21. Place the sample solid-state battery 10 inside the isostatic pressure container 20;

[0117] S22. Fill the isostatic pressure vessel 20 with isostatic medium 21;

[0118] S23. Apply pressure to the outer periphery of the isostatic container 20 and transmit the pressure to the sample solid-state battery 10 through the isostatic medium 21 so that the volume of the sample solid-state battery 10 shrinks.

[0119] Specifically, in step S21, the isostatic pressure container 20 is generally a sealed cylindrical structure, the sample solid-state battery 10 is placed vertically inside the isostatic pressure container 20, and the central axis of the sample solid-state battery 10 coincides with the central axis of the isostatic pressure container 20.

[0120] In step S22, the isostatic medium 21 filled in the isostatic container 20 may be, but is not limited to, esters, water, or inert gases.

[0121] In step S23, pressure can be applied to the outer periphery of the isostatic pressure container 20 through an external pressurization system. The pressure in all directions is uniformly transmitted to the sample solid-state battery 10 through the isostatic pressure medium 21 inside the isostatic pressure container 20, so that all parts of the sample solid-state battery 10 are uniformly pressurized, causing the volume of the sample solid-state battery 10 to shrink, thereby achieving the densification treatment of the sample solid-state battery 10.

[0122] By subjecting the pre-compression-treated solid-state battery sample 10 to isostatic pressing, the sample solid-state battery 10 is densified, further improving the tight contact between the positive electrode, solid electrolyte, and negative electrode within the sample solid-state battery 10. This also keeps the sample solid-state battery 10 in a relatively compact state, reducing the probability of misalignment between the positive and negative electrodes within the sample solid-state battery 10 during subsequent transfer and hardness testing. This improves the accuracy of subsequent hardness testing of the sample solid-state battery 10, and consequently, enhances the accuracy of the functional relationship between the density and hardness of the solid-state battery obtained through data fitting.

[0123] Furthermore, in the step of isostatic pressing the sample solid-state battery 10, the isostatic pressure is 200 MPa to 2000 MPa, the isostatic pressing time is 5 min to 30 min, and the isostatic pressing ambient temperature is 25℃ to 300℃.

[0124] During the isostatic pressing process of the sample solid-state battery 10, by reasonably controlling the isostatic pressure applied to the isostatic pressure container 20, the isostatic pressing time of the sample solid-state battery 10, and the isostatic pressure environment temperature inside the isostatic pressure container 20, the sample solid-state battery 10 can be pressurized evenly in all parts without structural damage.

[0125] The isostatic pressure is controlled within the range of 200 MPa to 2000 MPa, the isostatic pressure time is controlled within the range of 5 min to 30 min, and the isostatic pressure environment temperature is controlled within the range of 25℃ to 300℃. The isostatic pressure medium 21 is used to uniformly apply pressure to various parts of the sample solid-state battery 10, so that the length, thickness and width of the sample solid-state battery 10 are uniformly contracted. This improves the densification effect of the sample solid-state battery 10, reduces the probability of structural damage to the sample solid-state battery 10, and thus improves the accuracy of subsequent hardness testing of the sample solid-state battery 10.

[0126] Furthermore, in the step of isostatically pressing the sample solid-state battery 10, the isostatic medium 21 is one of esters, water, and inert gas.

[0127] In this way, the esters, water, and inert gas filled in the isostatic container 20 will not compress themselves, but will uniformly transmit pressure to the sample solid-state battery 10 in all directions toward the sample solid-state battery 10, causing the sample solid-state battery 10 to shrink uniformly and improving the densification effect of the sample solid-state battery 10.

[0128] It should be noted that when liquid substances such as esters or water are used as isostatic media 21 to perform isostatic treatment on the sample solid-state battery 10, if the isostatic media 21 is in contact with the sample solid-state battery 10 for a long time, it will cause contamination of the sample solid-state battery 10.

[0129] Based on this, in some embodiments of this application, before the step of isostatic pressing the sample solid-state battery 10, the following steps are included: step S6, encapsulating an isostatic film 30 on the surface of the sample solid-state battery 10.

[0130] Specifically, see Figure 7 and Figure 8 Step S6, which involves encapsulating an isostatic film 30 on the surface of the sample solid-state battery 10, includes:

[0131] S61. Select an isostatic membrane of size 30.

[0132] S62. Punch a hole in the isostatic membrane 30 to form a recess 31 on the isostatic membrane 30 for accommodating the sample solid battery 10.

[0133] S63. Place the sample solid-state battery 10 into the pit 31 along the thickness direction of the pit 31, and encapsulate the isostatic pressure film 30 in the sample solid-state battery 10 so that the isostatic pressure film 30 covers the surface of the sample solid-state battery 10.

[0134] In step S1, one of aluminum-plastic film, polyethylene film, polypropylene film, polyvinyl chloride film, and polyethylene terephthalate can be selected as the isostatic film 30, so that the isostatic film 30 has good elasticity and plasticity, making it convenient to encapsulate and cover the sample solid battery 10 with the isostatic film 30.

[0135] Meanwhile, by using the above-mentioned isostatic membrane 30, the isostatic membrane 30 has good oil resistance, water resistance and oxidation resistance, which improves the protective effect of the isostatic membrane 30 on the sample solid battery 10, and also reduces the possibility of liquid isostatic medium 21 contaminating the sample solid battery 10, thereby indirectly improving the accuracy of subsequent hardness testing of the sample solid battery 10.

[0136] Furthermore, the encapsulation process for sealing the isostatic film 30 on the surface of the sample solid-state battery 10 includes one of heat sealing, ultrasonic roll welding, and laser welding.

[0137] By using the above-mentioned encapsulation process to encapsulate the isostatic pressure film 30 on the surface of the sample solid-state battery 10, the isostatic pressure film 30 can form a stable ground surface bond with each surface of the sample solid-state battery 10, thereby improving the sealing and protection effect of the isostatic pressure film 30 on the sample solid-state battery 10.

[0138] In addition, it should be noted that since the sample solid-state battery 10 is wrapped with an adhesive film, when the isostatic pressure film 30 is then encapsulated on the surface of the sample solid-state battery 10, the isostatic pressure film 30 is directly bonded to the adhesive film surface, without contacting the positive or negative electrode on the sample solid-state battery 10. The adhesive film plays the role of isolating and separating the positive or negative electrode on the sample solid-state battery 10 from the isostatic pressure film 30.

[0139] In addition, it should be noted that in the step of isostatic pressure treatment of the sample solid-state battery 10, an inert gas such as helium can also be used as the isostatic pressure medium 21 to transfer pressure to the sample solid-state battery 10, so as to achieve uniform pressurization of the sample solid-state battery 10.

[0140] It should be noted that when the isostatic medium 21 is an inert gas, the inert gas will not cause oxidation or contamination to the sample solid-state battery 10 due to contact with it. In this case, it is not necessary to encapsulate the isostatic film on the surface of the sample solid-state battery 10.

[0141] In this embodiment, since the sample solid-state battery 10 is not encapsulated with an isostatic film, it is more prone to shrinkage and deformation under pressure load during isostatic pressing. This improves the efficiency of densification. Furthermore, applying a moderate pressure load is sufficient to achieve good densification of the sample solid-state battery 10, reducing the probability of the solid electrolyte within the battery becoming granular due to excessive pressure load. This also indirectly improves the accuracy of subsequent hardness testing of the sample solid-state battery 10.

[0142] It should be noted that solid-state batteries are primarily manufactured by stacking positive electrodes, solid electrolytes, and negative electrodes. During the coating process, to reduce the probability of problems such as overpressure, wavy edges, and edge bursting caused by uneven thickness between the coated and uncoated areas during the rolling process, the positive and negative electrodes are typically thinned along the coating direction. This results in the solid-state battery being formed by stacking the positive electrode, solid electrolyte, and negative electrode, with the area near the side of the large surface area being lower than the large surface area, forming a thinned region. In essence, the large surface area of ​​the solid-state battery excluding the thinned region is the large surface area, with a smooth transition between it and the thinned region, exhibiting a slight height difference. The side surface area of ​​the solid-state battery is the side surface area.

[0143] Based on the above explanation, see also... Figure 2 and Figure 9 Large surface area R1, side surface area R2, and thinned area R3 are also distributed on the surface of the sample solid-state battery 10.

[0144] Based on this, in some embodiments of this application, the step of obtaining the hardness value of a preset position R on the surface of the sample solid-state battery 10 includes one of the large surface area R1, the side surface area R2, and the thinning area R3 of the sample solid-state battery 10.

[0145] Specifically, see Figure 9 The thickness H1 of the thinned region R3 in the sample solid-state battery 10 is 5μm to 100μm, and the length L1 of the thinned region R3 is 3mm to 20mm. It is easy to understand that the thickness H1 of the thinned region R3 corresponds to the distance between the bottom and top of the thinned region R3, and can also be understood as the height difference between the thinned region R3 and the large surface area R1.

[0146] It should be understood that after each isostatic pressing process under corresponding isostatic pressing conditions is performed on the sample solid-state battery 10, the preset position R for hardness testing of the sample solid-state battery 10 needs to remain consistent. The preset position R can be one of the large surface area R1, the side surface area R2, and the thinning area R3 of the sample solid-state battery 10, so as to improve the comparability of the obtained hardness values.

[0147] Furthermore, since the thinned area of ​​a solid-state battery is lower than the large surface area, during the pressurization and densification process, there may be instances where the thinned area is not fully compacted. Therefore, the hardness of the thinned area is closer to the overall hardness of the solid-state battery. Thus, preferably, a preset position R is selected as the thinned area R3 of the sample solid-state battery 10. By detecting the hardness of the thinned area R3, the overall hardness of the sample solid-state battery 10 can be more accurately reflected, making the subsequent data-fitted functional relationship between the density and hardness of the solid-state battery more accurate.

[0148] In some embodiments of this application, the step of obtaining the actual density of the sample solid-state battery 10 includes: S31, punching the sample solid-state battery 10 into a wafer; S32, obtaining the mass and volume of the wafer to obtain the actual density of the wafer.

[0149] In steps S31 and S32, after the sample solid-state battery 10 is punched into regular circular pieces, the mass of the circular pieces is obtained by weighing. The thickness and diameter of the circular pieces are measured to calculate the material composition of the circular pieces. The density of the circular pieces is obtained from the mass and volume of the circular pieces, which is also the actual density of the sample solid-state battery 10.

[0150] It is easy to understand that after performing the first isostatic pressing treatment on the sample solid-state battery 10 under the corresponding isostatic pressing conditions, and obtaining a hardness value at a preset position R of the sample solid-state battery 10 at this time, steps S31 and S32 described above can be implemented. The resulting disc can continue to be used as the sample solid-state battery 10 for isostatic pressing treatment under other isostatic pressing conditions. In this way, only one punching operation is required on the sample solid-state battery 10, improving the efficiency of obtaining multiple actual density and hardness data.

[0151] It is easy to understand that by punching the sample solid-state battery 10 into wafers and then obtaining the mass and volume of the wafers, the actual density of the sample solid-state battery 10 can be accurately obtained.

[0152] In some embodiments of this application, the pre-compression pressure in the step of pre-compressing the sample solid-state battery 10 along the thickness direction is 3 MPa to 20 MPa.

[0153] Specifically, the solid-state battery 10 can be pre-compressed by applying a pressure load to the sample solid-state battery 10 using a flat plate. Specifically, the sample solid-state battery 10 is placed between two pressure plates, and a vertical load is applied to one or both pressure plates using a flat press to achieve the pre-compression treatment of the sample solid-state battery 10.

[0154] Excessive pressure can easily damage the structure of the sample solid-state battery 10, while insufficient pressure is difficult to achieve the initial densification effect. Therefore, by controlling the pre-pressure within the range of 3 MPa to 20 MPa, the initial densification effect of the sample solid-state battery 10 can be achieved, while reducing the probability of the sample solid-state battery 10 being damaged by overpressure, thereby improving the accuracy of subsequent hardness testing of the sample solid-state battery 10.

[0155] In addition, see Figure 1 This application also provides a solid-state battery 130, which is prepared using the above-described solid-state battery density detection method.

[0156] The solid-state battery 130 of this application embodiment does not require punching, thickness measurement, weighing, density measurement, or porosity measurement of each batch of solid-state batteries to detect their density. Instead, based on the functional relationship between the density and hardness value of the solid-state battery, the density of the solid-state battery can be obtained by directly measuring the hardness value. This method can efficiently and non-destructively detect the density of a batch of solid-state batteries, improving the detection efficiency of the density of a batch of solid-state batteries and facilitating large-scale applications.

[0157] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0158] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for detecting the density of solid-state batteries, characterized in that, Includes the following steps: The solid-state battery sample was pre-compressed along the thickness direction; The sample solid-state battery was subjected to isostatic pressure treatment under different isostatic pressure conditions, including one or more of isostatic pressure, isostatic pressure time, and isostatic pressure ambient temperature. After each isostatic pressing process is performed on the sample solid-state battery under corresponding isostatic pressing conditions, the hardness value at a preset position on the surface of the sample solid-state battery is obtained, and the actual density of the sample solid-state battery is obtained. Fit the functional relationship between the ratio of the actual density of the sample solid-state battery to the theoretical density of the sample solid-state battery and the hardness value at the preset location; The hardness value at a preset location on the solid-state battery under test is obtained, and the density of the solid-state battery under test is determined based on the functional relationship.

2. The solid-state battery density detection method according to claim 1, characterized in that, After fitting the functional relationship between the ratio of the actual density of the sample solid-state battery to the theoretical density of the sample solid-state battery and the hardness value at the preset location, the correlation coefficient between the ratio of the actual density of the sample solid-state battery to the theoretical density of the sample solid-state battery and the hardness value at the preset location is calculated.

3. The solid-state battery density detection method according to claim 1, characterized in that, The steps for isostatically pressing the sample solid-state battery include: The sample solid-state battery was placed in an isostatic pressure container; The isostatic pressure vessel is filled with an isostatic medium. Pressure is applied to the outer periphery of the isostatic container and transmitted to the sample solid-state battery through the isostatic medium, so as to cause the volume of the sample solid-state battery to shrink.

4. The solid-state battery density detection method according to claim 1 or 3, characterized in that, In the step of isostatic pressing the sample solid-state battery, the isostatic pressure is 200 MPa to 2000 MPa, the isostatic pressing time is 5 min to 30 min, and the isostatic pressing ambient temperature is 25℃ to 300℃.

5. The solid-state battery density detection method according to claim 1 or 3, characterized in that, In the step of isostatically pressing the sample solid-state battery, the isostatic medium is one of esters, water, or an inert gas.

6. The solid-state battery density detection method according to claim 1 or 3, characterized in that, Prior to the isostatic pressing process on the sample solid-state battery, the following steps are included: An isostatic film is encapsulated on the surface of the sample solid-state battery.

7. The solid-state battery density detection method according to claim 6, characterized in that, The encapsulation process for sealing an isostatic film on the surface of the sample solid-state battery includes one of heat sealing, ultrasonic roll welding, and laser welding.

8. The solid-state battery density detection method according to claim 6, characterized in that, The isostatic membrane is one of aluminum-plastic film, polyethylene film, polypropylene film, polyvinyl chloride film, and polyethylene terephthalate.

9. The solid-state battery density detection method according to claim 1, characterized in that, In the step of obtaining the hardness value of a preset location on the surface of the sample solid-state battery, the preset location includes one of the large surface area, the side surface area, and the thinned area of ​​the sample solid-state battery.

10. The solid-state battery density detection method according to claim 1, characterized in that, The steps for obtaining the actual density of the sample solid-state battery include: The sample solid-state battery was punched into a circular wafer; The mass and volume of the disc are obtained to determine its actual density.

11. The solid-state battery density detection method according to claim 1, characterized in that, In the step of pre-compressing the sample solid-state battery along the thickness direction, the pre-compressing pressure is 3 MPa to 20 MPa.

12. A solid-state battery, characterized in that, The solid-state battery is prepared using the solid-state battery density detection method as described in any one of claims 1 to 11.

13. An electrical appliance, characterized in that, Including the solid-state battery as described in claim 12.

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