Solid-state battery cell and method of manufacturing the same, battery device, power using device

Abstract

This application discloses a solid-state battery cell, its preparation method, battery device, and power-consuming device. The preparation method of the solid-state battery cell includes the following steps: providing an electrode assembly and a heat-shrinkable film, wherein the electrode assembly includes a main body and tabs extending from the main body; the main body includes a positive electrode, a solid electrolyte membrane, and a negative electrode stacked together, with the solid electrolyte membrane located between the positive and negative electrode; the negative electrode includes a negative current collector and a base coating layer located on at least one surface of the negative current collector; folding the heat-shrinkable film in half to cover the main body, and sealing the sides of the folded heat-shrinkable film; and performing isostatic pressing on the electrode assembly to shrink the heat-shrinkable film and tighten the main body. The battery cell prepared according to the method provided in this application has improved cycle performance.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a battery cell and its preparation method, a battery device, and an electrical device. Background Technology

[0002] Batteries are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric car toys, electric toy ships, electric toy airplanes, and power tools.

[0003] In the development of battery cells, improving the cycle performance of battery cells is one of the urgent problems to be solved. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a solid-state battery cell, its preparation method, a battery device, and an electrical device.

[0005] In a first aspect, embodiments of this application provide a method for preparing a solid-state battery cell, comprising the following steps:

[0006] An electrode assembly and a heat-shrinkable film are provided respectively. The electrode assembly includes a main body and an electrode tab extending from the main body. The main body includes a positive electrode, a solid electrolyte membrane, and a negative electrode stacked together. The solid electrolyte membrane is located between the positive electrode and the negative electrode. The negative electrode includes a negative current collector and a base coating layer located on at least one surface of the negative current collector.

[0007] Fold the heat shrink film in half to cover the main body, and seal and fix the sides of the folded heat shrink film.

[0008] The electrode assembly is subjected to isostatic pressing to shrink the heat-shrink film and secure the main body.

[0009] In this embodiment, a heat-shrinkable film is wrapped around the outer side of the main body of the electrode assembly. After wrapping the heat-shrinkable film with the other side, the sides of the heat-shrinkable film are fixed by sealing. This fixes the heat-shrinkable film onto the surface of the electrode assembly. Then, an isostatic pressing process is performed. The heating temperature during the isostatic pressing process causes the heat-shrinkable film to shrink, thus tightly wrapping the surface of the electrode assembly and providing a fastening force. Even after the isostatic pressing film is removed, the presence of the heat-shrinkable film can still provide a continuous fastening effect, allowing the electrode assembly to maintain a high degree of density after the isostatic pressing film is removed. This reduces the risk of the negative electrode undercoating peeling off, thereby improving the electrochemical performance of the battery cell.

[0010] In some embodiments, the heat-shrinkable film has a shrinkage rate of 5% to 30% in one direction.

[0011] In some embodiments, the heat-shrinkable film includes one or more of polyethylene film, polypropylene film, polyethylene terephthalate film, polyvinyl chloride film, polytetrafluoroethylene film, and polyimide film.

[0012] In some embodiments, the edge sealing method includes one or both of ultrasonic roll welding and laser welding.

[0013] In some embodiments, the weld width of the ultrasonic roll welding is 0.5 mm to 30 mm.

[0014] In some embodiments, the amplitude of the ultrasonic roll welding is 10 μm to 60 μm.

[0015] In some embodiments, the pressure of the ultrasonic roll welding is from 0.05 MPa to 2.5 MPa.

[0016] In some embodiments, the welding speed of the ultrasonic roll welding process is from 1 m / min to 10 m / min.

[0017] In some embodiments, providing the electrode assembly includes: stacking the positive electrode, the solid electrolyte membrane, and the negative electrode in sequence, and then performing a compaction process to obtain the electrode assembly.

[0018] In some embodiments, the compaction pressure is between 5 tons and 40 tons.

[0019] In some embodiments, the temperature of the compaction process is 25°C to 150°C.

[0020] In some embodiments, the compaction process takes 3 to 20 minutes.

[0021] In some embodiments, the isostatic pressing process includes: encapsulating the electrode assembly with an isostatic film, performing isostatic pressing, and then removing the isostatic film.

[0022] In some embodiments, the temperature of the isostatic pressing treatment is 25°C to 250°C.

[0023] In some embodiments, the pressure of the isostatic pressing process is from 100 MPa to 2000 MPa.

[0024] In some embodiments, the isostatic pressing process takes 3 to 30 minutes.

[0025] In some embodiments, the pressure transmission medium in the isostatic pressing process includes any one of water, ester, and inert gas.

[0026] In some embodiments, the isostatic membrane includes one or more of aluminum-plastic membrane, polyethylene membrane, polypropylene membrane, polytetrafluoroethylene membrane, and polyimide membrane.

[0027] Secondly, embodiments of this application provide a solid-state battery cell prepared according to the method of the first aspect of this application.

[0028] Thirdly, embodiments of this application provide a battery device, including a solid-state battery cell obtained by the preparation method according to the first aspect of this application or a solid-state battery cell according to the second aspect of this application.

[0029] Fourthly, embodiments of this application provide an electrical device, including a solid-state battery cell obtained by the preparation method according to the first aspect of this application, or a solid-state battery cell according to the second aspect of this application, or a battery device according to the third aspect of this application. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0031] Figure 1 The diagram shows the structural features of a vehicle provided in some embodiments of this application.

[0032] Figure 2 This is an exploded schematic diagram of a battery provided for some embodiments of this application.

[0033] Figure 3 for Figure 2 The diagram shows an exploded view of the battery module.

[0034] Figure 4 This is a schematic diagram of the structure of the heat shrink film in some embodiments of this application.

[0035] Figure 5 This is a schematic diagram of the structure of the electrode assembly in some embodiments of this application.

[0036] Figure 6 This is a schematic diagram of the structure of the electrode assembly covered by heat-shrink film folded in half in some embodiments of this application.

[0037] Figure 7 This is a schematic diagram of the structure after heat shrink film sealing in some embodiments of this application.

[0038] Figure 8 This is a schematic diagram of the structure of an electrode assembly covered with heat-shrinkable film in some embodiments of this application.

[0039] The accompanying drawings are not necessarily drawn to scale.

[0040] The reference numerals in the attached drawings are explained as follows: 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 5a. First housing section; 5b. Second housing section; 5c. Reception space; 6. Battery module; 7. Battery cell. Detailed Implementation

[0041] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the battery cell, battery device, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0042] 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.

[0043] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0044] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0045] 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.

[0046] Unless otherwise specified, in this application, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0047] In this application, the terms "multiple" or "various" refer to two or more kinds.

[0048] In the description of the embodiments of this application, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0049] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0050] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this application. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0051] The battery device mentioned in the embodiments of this application can be a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application can include battery cells, battery modules, or battery packs.

[0052] A single battery cell is the smallest unit that makes up a battery, and it can independently perform the functions of charging and discharging. When there are multiple battery cells, they are connected in series, parallel, or mixed connections through a busbar.

[0053] In some embodiments, the battery device may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0054] In some embodiments, the battery device may be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0055] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0056] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0057] The technical solutions described in the embodiments of this application are applicable to battery devices and electrical devices that use battery devices.

[0058] Battery devices can be used as the power source for electrical devices or as energy storage units for electrical devices. Electrical devices can be, but are not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0059] Electrical devices can choose the type of battery device according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0060] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0061] Figure 1 The diagram shows the structural features of a vehicle provided in some embodiments of this application.

[0062] like Figure 1 As shown, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0063] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0064] In some embodiments, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0065] Figure 2 This is a schematic diagram of a battery explosion provided for some embodiments of this application. For example... Figure 2 As shown, the battery device 2 includes a housing 5 and battery cells (not shown), with the battery cells housed within the housing 5.

[0066] The housing 5 is used to house individual battery cells, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a housing space 5c for housing the individual battery cells. The second housing portion 5b may be a hollow structure with one end open, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, with the open side of the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as cylinders, cuboids, etc.

[0067] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

[0068] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be called the upper box cover, and the second box section 5b can also be called the lower box.

[0069] In battery device 2, there can be one or more battery cells. If there are multiple battery cells, they can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells are connected in both series and parallel configurations. Multiple battery cells can be directly connected in series, in parallel, or in a mixed configuration, and then the whole assembly of multiple battery cells is housed in housing 5. Alternatively, multiple battery cells can first be connected in series, in parallel, or in a mixed configuration to form battery module 6, and then multiple battery modules 6 can be connected in series, in parallel, or in a mixed configuration to form a whole assembly, which is then housed in housing 5.

[0070] Figure 3 for Figure 2 The diagram shows an exploded view of the battery module.

[0071] like Figure 3 As shown, in some embodiments, there are multiple battery cells 7, which are first connected in series, parallel, or mixed to form a battery module 6. The multiple battery modules 6 are then connected in series, parallel, or mixed to form a whole and housed in a casing.

[0072] Multiple battery cells 7 in battery module 6 can be electrically connected through a busbar component to achieve parallel, series, or mixed connection of multiple battery cells 7 in battery module 6.

[0073] The battery cells mentioned in the embodiments of this application may include lithium-ion battery cells or sodium-ion battery cells.

[0074] The battery cell includes an electrode assembly. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to this.

[0075] The battery cells provided in the embodiments of this application are negative electrode-free battery cells, and may include at least one of negative electrode-free lithium metal battery cells and negative electrode-free sodium metal battery cells.

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

[0077] A negative electrode-free solid-state battery cell is a battery that uses a solid material as the electrolyte, building upon the negative electrode-free battery cell design. A solid-state battery cell typically includes a casing and an electrode assembly within the casing. The electrode assembly generally includes a positive electrode, a negative electrode, and a solid electrolyte membrane. The solid electrolyte membrane is located between the positive and negative electrodes, serving to isolate the positive and negative electrodes and transport active ions. In a negative electrode-free solid-state battery cell, the positive and negative electrodes are in solid-solid contact with the solid electrolyte. To reduce the gap at the solid-solid contact interface and the porosity inside the battery cell, solid-state battery cells generally undergo isostatic pressing. This isostatic pressing densifies the interior of the solid-state battery cell, thereby increasing its energy density. The negative electrode of a negative electrode-free solid-state battery cell typically has a base coating coated on the surface of the negative electrode current collector. The main material of the negative electrode current collector is stainless steel or copper foil. The base coating material has poor adhesion to the negative electrode current collector. During the removal of the isostatic pressing membrane after isostatic pressing, pressure changes inside the battery cell can easily cause the base coating to detach, thus affecting the electrochemical performance of the battery cell.

[0078] Therefore, this application provides a solid-state battery cell. By adjusting the preparation of the solid-state battery cell, the risk of the negative electrode bottom coating peeling off during the removal of the hydrostatic membrane can be reduced, thereby improving the electrochemical performance of the battery cell.

[0079] The solid-state battery cell provided in this application embodiment can be prepared by the following method:

[0080] S10, respectively providing an electrode assembly and a heat-shrinkable film, the electrode assembly including a main body and an electrode tab extending from the main body, the main body including a positive electrode, a solid electrolyte membrane and a negative electrode stacked together, the solid electrolyte membrane being located between the positive electrode and the negative electrode; the negative electrode including a negative current collector and a base coating layer located on at least one side of the surface of the negative current collector;

[0081] S20, fold the heat shrink film in half to cover the main body, and seal and fix the sides of the folded heat shrink film.

[0082] S30, the electrode assembly is subjected to isostatic pressing to shrink the heat-shrink film and secure the main body.

[0083] The solid-state battery cell preparation method provided in this application involves wrapping a heat-shrinkable film around the outer side of the main body of the electrode assembly. After folding the heat-shrinkable film in half to wrap around the electrode assembly, the opposite sides of the folded heat-shrinkable film are fixed by edge sealing. This fixes the heat-shrinkable film onto the surface of the electrode assembly. Then, isostatic pressing is performed. The heating temperature during the isostatic pressing process causes the heat-shrinkable film to shrink, thus tightly wrapping the surface of the electrode assembly and providing a fastening force. Even after the isostatic pressing film is removed, the presence of the heat-shrinkable film still provides a continuous fastening effect, allowing the electrode assembly to maintain a high degree of density after the isostatic pressing film is removed. This reduces the risk of the negative electrode undercoating peeling off, thereby improving the electrochemical performance of the battery cell.

[0084] To better understand the method provided in the embodiments of this application, the process of step S20 can be referred to... Figures 4 to 7 . Figure 4 The initial state of the heat-shrinkable film in some embodiments of this application is shown. Figure 5 Schematic diagrams of electrode assemblies in some embodiments of this application are shown. The length of the heat-shrinkable film is denoted as L1, and the width of the heat-shrinkable film is denoted as W1, where L1 > W1; the length of the electrode assembly is denoted as L2, the width as W2, and the thickness as D2, where L2 > W2. (Refer to...) Figure 4 The heat-shrink film can be cut to fit the dimensions of the electrode assembly. The heat-shrink film is cut at its midpoint along its length; specifically, the length of the cut area is denoted as L. ′ 1. The width of the cropping area is W1 ′ This allows the dimensions of the heat-shrinkable film and the electrode assembly to satisfy the following relationship:

[0085] L1 = 2L2 + d2

[0086] W1≥W2+d2

[0087] L ′ 1 = W2

[0088] W1 ′ =d2

[0089] Reference Figure 6 Fold the heat-shrink film in half to initially cover the main body of the electrode assembly, aligning the length of the heat-shrink film with the length of the electrode assembly, the width of the heat-shrink film with the width of the electrode assembly, and aligning the cut area of ​​the heat-shrink film with the thickness side of the electrode assembly. (Refer to...) Figure 7 The folded heat shrink film is then sealed at the edges. The two length edges on the same side after folding are sealed and fixed to ensure that the heat shrink film is stably wrapped around the surface of the electrode assembly.

[0090] Reference Figure 8The edge of the heat-shrink film can be further trimmed after the edge is fixed to reduce the width of the edge and thus reduce the proportion of hardware volume in the battery cell.

[0091] In some embodiments, the shrinkage rate of the heat shrink film in one direction can be from 5% to 30%. Exemplarily, the shrinkage rate of the heat shrink film in one direction can be 5%, 10%, 15%, 20%, 25%, 30%, or any range of the foregoing values. Optionally, the shrinkage rate of the heat shrink film in one direction can be from 8% to 25%.

[0092] By limiting the shrinkage rate of the heat-shrinkable film to the above range, the heat-shrinkable film can be tightly wrapped around the outside of the electrode assembly after shrinkage, providing a higher fastening force to the electrode assembly, reducing the dimensional changes of the electrode assembly after the removal of the isostatic film, thereby reducing the risk of the negative electrode bottom coating peeling off and improving the cycle performance of the battery cell.

[0093] In some embodiments, the thickness of the heat-shrinkable film can be from 30 μm to 200 μm. Exemplarily, the thickness of the heat-shrinkable film can be 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, or any range of the above values. Optionally, the thickness of the heat-shrinkable film can be from 50 μm to 160 μm.

[0094] In this application, the thickness of the heat-shrink film refers to the thickness of the heat-shrink film after it has been heated and shrunk. Limiting the thickness of the heat-shrink film to the aforementioned range allows it to maintain high strength during heat shrinkage, providing a durable fastening force. A thinner heat-shrink film results in lower strength and a risk of breakage; a thicker film increases the overall thickness of the electrode assembly and the volume proportion of mechanical structures within the battery cell, leading to a decrease in the energy density of the battery cell and affecting its capacity.

[0095] In some embodiments, the heat shrink film includes one or more of polyethylene film, polypropylene film, polyethylene terephthalate film, polyvinyl chloride film, polytetrafluoroethylene film, and polyimide film.

[0096] In some embodiments, the edge sealing method may include one or both of ultrasonic roll welding and laser welding.

[0097] In some embodiments, the edge sealing and fixing method can be ultrasonic roll welding.

[0098] In some embodiments, the weld width of the ultrasonic roll welding process can be 0.5mm-30mm, for example, it can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.2mm, 1.5mm, 1.8mm, 2.0mm, 5.0mm, 8.0mm, 10.0mm, 15.0mm, 20.0mm, 25.0mm, 30.0mm, or any range of the above values. Optionally, the weld width of the ultrasonic roll welding process can be 1mm-20mm.

[0099] In some embodiments, the amplitude of ultrasonic roll welding can be from 10 μm to 60 μm, for example, it can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, or any range of the above values.

[0100] In some embodiments, the pressure for ultrasonic roll welding can be 0.05MPa-2.5MPa, for example, it can be 0.05MPa, 0.06MPa, 0.07MPa, 0.08MPa, 0.09MPa, 0.1MPa, 0.5MPa, 1.0MPa, 1.5MPa, 2.0MPa, 2.5MPa, or any range of the above values.

[0101] In some embodiments, the welding speed of ultrasonic roll welding can be from 1 m / min to 10 m / min, for example, it can be 1 m / min, 2 m / min, 3 m / min, 4 m / min, 5 m / min, 6 m / min, 7 m / min, 8 m / min, 9 m / min, 10 m / min, or any range of the above values.

[0102] In some embodiments, step S10, providing the electrode assembly may include: stacking the positive electrode, the solid electrolyte membrane, and the negative electrode in sequence, and then performing a compaction process to obtain the electrode assembly.

[0103] Compaction processing allows the positive and negative electrode sheets to come into close contact with the solid electrolyte membrane, reducing the internal gaps of the electrode assembly and increasing the density of the electrode assembly.

[0104] In some embodiments, the compaction pressure can be from 5 tons to 80 tons. For example, the compaction pressure can be 5 tons, 10 tons, 15 tons, 20 tons, 25 tons, 30 tons, 35 tons, 40 tons, 45 tons, 50 tons, 55 tons, 60 tons, 65 tons, 70 tons, 75 tons, 80 tons, or any range of the above values.

[0105] In some embodiments, the compaction temperature can be from 25°C to 100°C. Exemplarily, the compaction temperature can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, or any range of the above values.

[0106] In some embodiments, the compaction time can be from 5 min to 30 min. Exemplarily, the compaction time can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, or any range of the above values.

[0107] In some embodiments and in some cases, the isostatic pressing process includes: encapsulating the electrode assembly with an isostatic film, performing the isostatic pressing process, and then removing the isostatic film.

[0108] In this application, isostatic pressing is a well-known concept in the art. It utilizes Pascal's principle to place an electrode assembly sealed in an isostatic membrane in a high-pressure cylinder filled with a pressure-transmitting medium. A certain pressure is applied to the pressure-transmitting medium in the cylinder using high-pressure equipment. The pressure is transmitted evenly to the electrode assembly through the pressure-transmitting medium, causing the electrode assembly to undergo a certain volume deformation under the action of isostatic pressure. This achieves isostatic pressing, which further improves the density of the electrode assembly, thereby providing higher energy density and meeting the requirements of solid-state batteries.

[0109] Isostatic pressing can make the electrode assembly more compact, reduce the internal porosity of the battery cell, and increase the energy density of the battery cell. On the other hand, the heating during the isostatic pressing process can cause the heat-shrink film to shrink, making the heat-shrink film cover the surface of the main body more tightly, further improving the fastening effect on the electrode assembly, reducing the dimensional rebound of the electrode assembly after the isostatic pressing film is removed, reducing the risk of the negative electrode bottom coating peeling off, and further improving the cycle performance of the battery cell.

[0110] Specifically, the electrode assembly can be placed in a sealed high-pressure container, and at a preset temperature and pressure, the electrode assembly is uniformly squeezed from all sides using a pressure-transmitting medium, which can further improve the density of the electrode assembly and thus provide higher energy density to meet the needs of solid-state batteries.

[0111] In some embodiments, the isostatic pressing temperature can be from 25°C to 300°C. Exemplarily, the isostatic pressing temperature can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, or any range of the above values.

[0112] In some embodiments, the pressure for isostatic pressing can be from 100 MPa to 2000 MPa. Exemplarily, the pressure for isostatic pressing can be 100 MPa, 200 MPa, 300 MPa, 400 MPa, 500 MPa, 600 MPa, 700 MPa, 800 MPa, 900 MPa, 1000 MPa, 1200 MPa, 1500 MPa, 1800 MPa, 2000 MPa, or any range of the above values.

[0113] In some embodiments, the isostatic pressing time can be from 3 min to 30 min. Exemplarily, the isostatic pressing time can be 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, or any range of the above values.

[0114] In some embodiments, the pressure transmission medium in the isostatic pressing process may include any one of water, ester, or inert gas.

[0115] In some embodiments, the isostatic membrane may include one or more of aluminum-plastic membrane, polyethylene membrane, polypropylene membrane, polytetrafluoroethylene membrane, and polyimide membrane.

[0116] [Positive electrode plate]

[0117] In some embodiments, the positive electrode includes a positive current collector and a positive film layer located on at least one surface of the positive current collector.

[0118] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0119] In some embodiments, the positive electrode active material includes one or more of lithium phosphate, layered lithium transition metal oxide, Prussian blue compounds, polyanionic compounds, and sodium transition metal oxide.

[0120] If the positive electrode active material is one or more of lithium phosphate and layered lithium transition metal oxide, then the positive electrode active material can be used in lithium-ion battery cells; if the positive electrode active material is one or more of Prussian blue compounds, polyanionic compounds, and sodium transition metal oxide, then the positive electrode material can be used in sodium-ion battery cells.

[0121] Lithium-containing phosphates may include one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and their respective modified compounds.

[0122] Examples of layered lithium-containing transition metal oxides may include one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds.

[0123] In some embodiments, the layered lithium-containing transition metal oxide may include Ni. The molar amount of Ni may account for more than 70% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide; optionally, the molar amount of Ni may account for more than 80% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide; more preferably, the molar amount of Ni may account for more than 90% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide.

[0124] The higher the Ni content in layered lithium-containing transition metal oxides, the higher the energy density of the battery cell.

[0125] In some embodiments, layered lithium-containing transition metal oxides may include Li a Ni b Co c M d O e A f Wherein, 0 < a ≤ 1.2; 0.8 ≤ b < 1; 0 < c < 1; 0 < d < 1; 1 ≤ e ≤ 2; 0 ≤ f ≤ 1; M includes, but is not limited to, one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B; A includes, but is not limited to, one or more of N, F, S, and Cl. This can further improve the energy density of individual battery cells.

[0126] In some embodiments, as an example, layered lithium-containing transition metal oxides may include, but are not limited to, LiNi. 0.8 Co0.1 Mn 0.1 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.9 Co 0.06 Mn 0.04 O2, LiNi 0.92 Co 0.06 Mn 0.02 O2, LiNi 0.96 Co 0.02 Mn 0.02 One or more of O2.

[0127] During the charging and discharging process of a battery cell, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this application, the molar Li content refers to the initial state of the material, i.e., the state before feeding. After charge-discharge cycles, the molar Li content may change when the positive electrode active material is applied to the battery cell.

[0128] In some embodiments, as an example, sodium transition metal oxides may include, but are not limited to:

[0129] Na 1-x Cu h Fe k Mn l M 1 m O 2-y M 1 It is one or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn, and Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0130] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2, where M 2 It is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn and Ba, 0 <z≤0.1;

[0131] Na a Li b Ni c Mn d Fe e O2, of which 0.67 <a≤1,0<b<0.2,0<c<0.3,

[0132] 0.67 < d + e < 0.8, b + c + d + e = 1.

[0133] In some embodiments, by way of example, the polyanionic compound may include, but is not limited to:

[0134] A 1 f M 3 g (PO4) i O j X 1 3-j , where A is one or more of H, Li, Na, K, and NH4, M 3 is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, and Zn, X 1 is one or more of F, Cl, and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0135] Na n M 4 PO4X 2 , where M 4 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, X 2 is one or more of F, Cl, and Br, 0 < n ≤ 2;

[0136] Na p M 5 q (SO4)3, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0137] Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0138] In some embodiments, by way of example, the Prussian blue compound may include, but is not limited to:

[0139] A u M 6 v [M 7 (CN)6] w ·xH2O, where A is H + , NH4 + , an alkali metal cation, and an alkaline earth metal cation, M 6 and M7 Each independently represents one or more of transition metal cations, where 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, and 0 < x < 6. For example, A is H + , Li + , Na + , K + , NH4 + , Rb + , Cs + , Fr + , Be 2+ , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ and Ra 2+ One or more of these, M 6 and M 7 Each independently represents a cation of one or more transition metal elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, and W. Optionally, A is Li + , Na + and K + One or more of these, M 6 is a cation of one or more transition metal elements selected from Mn, Fe, Co, Ni, and Cu, and M 7 is a cation of one or more transition metal elements selected from Mn, Fe, Co, Ni, and Cu.

[0140] In the enumeration of the positive electrode active materials in the embodiments of the present application, the molar content of O is only the theoretical value, and the release of oxygen from the lattice will cause the molar content of O to change, and the actual molar content of O will show fluctuations.

[0141] The modified compounds of the above positive electrode active materials can be doping modification and / or surface coating modification of the positive electrode active materials.

[0142] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0143] In some implementations, the weight percentage of the binder in the positive electrode film layer is greater than or equal to 0.5%, which is beneficial to obtaining good adhesion performance.

[0144] In some embodiments, the positive electrode film layer further includes a conductive agent. As an example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0145] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be made by forming a metal material, such as aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, on the polymer substrate. The polymer substrate may include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and other substrates.

[0146] In some embodiments, the thickness of the positive current collector is from 4 μm to 20 μm. It is optionally from 6 μm to 18 μm, and more preferably from 8 μm to 16 μm.

[0147] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0148] [Negative electrode plate]

[0149] In some embodiments, the negative electrode sheet includes a negative current collector and a base coating layer located on at least one surface of the negative current collector.

[0150] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector. The negative electrode current collector can be made of materials such as metal foil, carbon-coated metal foil, or porous metal plate, and copper foil is optional.

[0151] As an example, the material of the base coating may include conductive carbon coating, conductive metal coating, etc.

[0152] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, aluminum foil, and aluminum alloy foil. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one side of the polymeric material substrate. Examples of metal materials include, but are not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymeric material substrates include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0153] [Solid electrolyte]

[0154] Solid electrolyte membranes include solid electrolytes, which may include at least one of sulfide solid electrolytes, oxide solid electrolytes, and organic solid electrolytes.

[0155] Sulfide solid electrolytes have high 10 -2 S / cm to 10 -3 A lithium-ion conductivity of S / cm facilitates the formation of contact interfaces between electrodes and exhibits high mechanical strength and flexibility. In this application embodiment, 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. In this application embodiment, the sulfide-based solid electrolyte may include Li6PS5Cl (LPSCl), Thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S4), Li2S-P2S5-LiCl, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5, Li3PS4, Li7P3S 11 , LiI-Li2S-B2S3, Li3PO4-Li2S-Si2S, Li3PO4-Li2S-SiS2, LiPO4-Li2S-SiS, Li 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 and Li7P3S 11 One or more of them.

[0156] Oxide-based solid electrolytes exhibit high safety in air and have a 10 -3S / cm to 10 -4 The lithium-ion conductivity (S / cm) is lower than that of sulfide-based solid electrolytes, but relatively higher. Furthermore, oxide-based solid electrolytes exhibit high electrochemical safety and mechanical strength. However, oxide-based solid electrolytes have high oxidation voltage. Additionally, solid electrolytes have high grain boundary resistance, making it difficult to form a contact interface between the electrode and 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. In the embodiments of this application, the oxide-based solid electrolyte includes perovskite solid electrolyte, sodium superionic conductor solid electrolyte (NASICON), lithium superionic conductor solid electrolyte (LISICON), and lithium lanthanum zirconium oxide solid electrolyte (LLZO).

[0157] 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 (PEO).

[0158] The thickness of the solid electrolyte membrane can be selected differently depending on the properties of the desired all-solid-state battery. Specifically, in some embodiments, the thickness of the solid electrolyte membrane can be from 0.1 μm to 1000 μm; in other embodiments, the thickness of the solid electrolyte membrane can be from 1 μm to 500 μm; in still other embodiments, the thickness of the solid electrolyte membrane can be from 20 μm to 30 μm; this application does not limit it in this regard.

[0159] For ease of subsequent description and understanding, the preparation method of the battery cell and the battery cell in the embodiments of this application can use sulfide-based solid electrolytes.

[0160] Example

[0161] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0162] Example 1

[0163] Positive electrode sheet

[0164] Under an argon atmosphere, the positive electrode active material LiNi0.8Co0.1Mn0.1O2 (NCM811), the binder polyvinylidene fluoride (PVDF), and the conductive agent carbon fiber are dispersed in the solvent p-xylene at a mass ratio of 98:1:1, with the solid content controlled at 60%. After stirring evenly, the mixture is coated onto the positive electrode current collector aluminum foil and dried to obtain the positive electrode sheet.

[0165] Negative electrode sheet

[0166] Silicon carbide, conductive carbon, and polyvinylidene fluoride (PVDF) binder are mixed and dispersed in a solvent of xylene at a mass ratio of 90:7:3, with the solid content controlled at 55%. The mixture is stirred evenly to obtain a negative electrode slurry. The negative electrode slurry is then evenly coated onto the surface of the copper foil of the negative electrode current collector and dried to obtain a negative electrode sheet.

[0167] Solid electrolyte membrane

[0168] In an argon atmosphere, the sulfide solid electrolyte Li6PS5Cl and the binder nitrile rubber (NBR) are dispersed in p-xylene (solid content is 50%) at a mass ratio of 99:1. After stirring evenly, the mixture is coated onto a PET film and dried to obtain an electrolyte membrane.

[0169] Solid-state battery cells

[0170] S10, the above electrolyte membrane is covered on the surface of the positive electrode sheet, and the electrolyte membrane is transferred to the positive electrode sheet by cold pressing at 10MPa. The PET film is removed to obtain a positive / solid electrolyte membrane composite electrode sheet. Then the negative electrode sheet is attached to the other side of the solid electrolyte membrane for stacking. Then it is shaped and compacted to form a compacted electrode assembly. The compaction pressure is 30t, the time is 15min, and the temperature is 100℃.

[0171] S20, fold a polypropylene heat shrink film with a shrinkage rate of 20% and wrap it around the main body of the electrode assembly. After folding, the heat shrink film can completely cover the surface of the main body. Then, the folded heat shrink film is sealed by ultrasonic roll welding to make the heat shrink film stably cover the surface of the main body.

[0172] S30: After encapsulating the electrode assembly with an aluminum-plastic film, it undergoes isostatic pressing treatment at a temperature of 200℃, a pressure of 200MPa, and a time of 20min. The pressure transmission medium is helium. After the isostatic pressing treatment is completed, the aluminum-plastic film is removed. The electrode assembly is then encapsulated to obtain a solid-state battery cell.

[0173] Examples 2-9

[0174] The preparation method of solid-state battery cells is similar to that in Example 1, except that the parameters of the heat-shrink film are different. For details of the parameter adjustments, please refer to Table 1.

[0175] Comparative Example 1

[0176] Positive electrode sheet

[0177] Under an argon atmosphere, the positive electrode active material LiNi0.8Co0.1Mn0.1O2 (NCM811), the binder polyvinylidene fluoride (PVDF), and the conductive agent carbon fiber are dispersed in the solvent p-xylene at a mass ratio of 98:1:1, with the solid content controlled at 60%. After stirring evenly, the mixture is coated onto the positive electrode current collector aluminum foil and dried to obtain the positive electrode sheet.

[0178] Negative electrode sheet

[0179] Silicon carbide, conductive carbon, and polyvinylidene fluoride (PVDF) binder are mixed and dispersed in a solvent of xylene at a mass ratio of 90:7:3, with the solid content controlled at 55%. The mixture is stirred evenly to obtain a negative electrode slurry. The negative electrode slurry is then evenly coated onto the surface of the copper foil of the negative electrode current collector and dried to obtain a negative electrode sheet.

[0180] Solid electrolyte membrane

[0181] In an argon atmosphere, the sulfide solid electrolyte Li6PS5Cl and the binder nitrile rubber (NBR) are dispersed in p-xylene (solid content is 50%) at a mass ratio of 99:1. After stirring evenly, the mixture is coated onto a PET film and dried to obtain an electrolyte membrane.

[0182] Solid-state battery cells

[0183] The electrolyte membrane is covered on the surface of the positive electrode, and the electrolyte membrane is transferred to the positive electrode by cold pressing at 10MPa. The PET film is removed to obtain a positive / solid electrolyte membrane composite electrode. Then, the negative electrode is attached to the other side of the solid electrolyte membrane and assembled to obtain an electrode assembly.

[0184] The electrode assembly is subjected to isostatic pressing at a temperature of 200℃, a pressure of 200 MPa, and a time of 20 min, with helium as the pressure transmission medium. The isostatically pressed electrode assembly is then encapsulated to obtain a solid-state battery cell.

[0185] Test section

[0186] 1. Stability of the bottom coating of the negative electrode sheet

[0187] The negative electrode sheet was obtained by disassembling the battery cell. The negative electrode sheet was cut into 100mm×25mm samples. The coated side was bonded to double-sided adhesive. A tensile testing machine was used to pull the negative electrode current collector at a 90° angle to test the adhesion of the bottom coating of the negative electrode sheet.

[0188] 2. Number of battery cell cycles

[0189] At 25°C, the battery cell was charged to 4.3V at a constant current of 0.1C, then charged to 0.05C at a constant voltage. After standing for 5 minutes, it was discharged to 2.8V at a constant current of 0.1C. The initial discharge capacity C0 was recorded. The above charge and discharge process was repeated, and the discharge capacity Cn of each cycle was recorded until the cycle capacity retention rate (Cn / C0*100%) was below 80%. The number of cycles was recorded.

[0190] 3. Short-circuit failure rate

[0191] Take 200 battery cells and perform charge-discharge cycle testing according to the above cycle test method. If voltage protection or capacity protection occurs during the test, it is considered a short circuit. Record the proportion of short circuits.

[0192] For detailed performance test results, please refer to Table 1.

[0193] Table 1

[0194]

[0195] According to the embodiments of this application, by sealing the electrode assembly, the peeling off of the negative electrode coating after isostatic decoction of the battery cell can be reduced, thereby improving the cycle performance of the battery cell.

[0196] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing a solid-state battery cell, characterized in that, Includes the following steps: An electrode assembly and a heat-shrinkable film are provided respectively. The electrode assembly includes a main body and an electrode tab extending from the main body. The main body includes a positive electrode, a solid electrolyte membrane, and a negative electrode stacked together. The solid electrolyte membrane is located between the positive electrode and the negative electrode. The negative electrode includes a negative current collector and a base coating layer located on at least one surface of the negative current collector. Fold the heat shrink film in half to cover the main body, and seal and fix the sides of the folded heat shrink film. The electrode assembly is subjected to isostatic pressing to shrink the heat-shrink film and secure the main body.

2. The preparation method according to claim 1, characterized in that, The heat-shrinkable film has a shrinkage rate of 5% to 30% in one direction.

3. The preparation method according to claim 1 or 2, characterized in that, The thickness of the heat-shrinkable film is from 30 μm to 200 μm.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The heat shrink film includes one or more of the following: polyethylene film, polypropylene film, polyethylene terephthalate film, polyvinyl chloride film, polytetrafluoroethylene film, and polyimide film.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The edge sealing and fixing methods include one or both of ultrasonic roll welding and laser welding.

6. The preparation method according to claim 5, characterized in that, The ultrasonic roll welding process satisfies at least one of the following conditions: (1) The weld width of the ultrasonic roll welding is 0.5 mm to 30 mm; (2) The amplitude of the ultrasonic roll welding is 10 μm to 60 μm; (3) The pressure of the ultrasonic roll welding is from 0.05 MPa to 2.5 MPa; (4) The welding speed of the ultrasonic roll welding process is 1 m / min to 10 m / min.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The provision of the electrode assembly includes: stacking the positive electrode, the solid electrolyte membrane, and the negative electrode in sequence, and then performing a compaction process to obtain the electrode assembly.

8. The preparation method according to claim 7, characterized in that, The compaction process satisfies at least one of the following conditions: (1) The compaction pressure is 5 to 40 tons; (2) The temperature of the compaction treatment is 25°C to 150°C; (3) The compaction time is 3 min to 20 min.

9. The preparation method according to any one of claims 1 to 8, characterized in that, The isostatic pressing process includes: encapsulating the electrode assembly with an isostatic pressing film, performing isostatic pressing, and then removing the isostatic pressing film.

10. The preparation method according to claim 9, characterized in that, The isostatic pressing process satisfies at least one of the following conditions: (1) The temperature of the isostatic pressing treatment is 25°C to 250°C; (2) The pressure of the isostatic pressing treatment is 100MPa to 2000MPa; (3) The isostatic pressing treatment time is 3 min to 30 min; (4) The pressure transmission medium for isostatic pressure treatment includes any one of water, ester, and inert gas.

11. The preparation method according to claim 9 or 10, characterized in that, The isostatic pressure membrane includes one or more of the following: aluminum-plastic membrane, polyethylene membrane, polypropylene membrane, polytetrafluoroethylene membrane, and polyimide membrane.

12. A solid-state battery cell, characterized in that, The preparation method according to any one of claims 1 to 10 is used.

13. A battery device, characterized in that, Includes solid-state battery cells obtained by the preparation method according to any one of claims 1 to 11 or solid-state battery cells according to claim 12.

14. An electrical appliance, characterized in that, Includes solid-state battery cells obtained by the preparation method according to any one of claims 1 to 11, solid-state battery cells according to claim 12, or battery devices according to claim 13.

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