Solid-state battery and preparation method and application thereof

Abstract

The invention belongs to the technical field of secondary batteries, and particularly relates to a solid-state battery and a preparation method and application thereof. According to the present invention, the limiting frame having the same composition as the electrolyte membrane or the active material layer on the second pole piece is arranged on the periphery of the second pole piece, and the arrangement of the pole core outer coating film is matched, such that the deviation and the slippage of the pole piece during the non-diaphragm lamination process and the cell transfer process of the traditional pole piece are avoided, and the cell abnormality after the isostatic pressing is avoided; meanwhile, the composition of the limiting frame is the same as that of the electrolyte membrane or the active material layer on the second pole piece, and the stress deformation degree is consistent with that of the electrolyte membrane or the active material layer on the second pole piece, so that stress deformation dislocation possibly caused by the expansion influence of the pole piece of the battery cell in the cycle process of the battery cell can be avoided.

Description

Technical Field

[0001] This application belongs to the technical field of secondary batteries, and particularly relates to a solid-state battery, a preparation method thereof, and an application thereof. Background Art

[0002] A solid-state battery is a battery in which both the electrode and electrolyte materials used within the operating temperature range are in a solid state and do not contain any liquid components. Compared with traditional lithium-ion batteries that use organic liquids as electrolytes, solid-state lithium batteries can fundamentally eliminate safety hazards caused by electrolyte leakage, flammability, etc.

[0003] During the production process of a solid-state battery, it is necessary to stack the positive and negative electrode sheets after the positive electrode, negative electrode, electrolyte membrane or composite electrolyte membrane, and the negative / positive electrode sheets without the composite electrolyte membrane. After stacking, processes such as hot pressing and shaping, tab welding, aluminum-plastic film encapsulation, and isostatic pressing are carried out. Currently, the stacking methods involve 45° swing stacking, double-feed stacking, and integrated cutting and stacking. During the stacking process, the positive and negative electrodes are wrapped by a separator. After the electrode sheets are stacked, the electrode core is wound and fixed by the separator, and then transferred to the next process. However, during the stacking process, the electrode sheets may shift, and during the subsequent transfer process of the electrode core, the electrode sheets are prone to slip, changing the original alignment, resulting in steps and short circuits between the positive and negative electrodes, which deteriorate further during the subsequent densification process, and may even cause the membrane to break, ultimately leading to battery abnormalities.

[0004] In order to avoid the problems of electrode sheet offset during the stacking process and slip during the transfer process, the prior art discloses a method of preparing a glue frame on the battery electrode sheet to fix the electrode sheet. However, the use of the glue frame introduces other types of materials, adds new preparation processes to the glue frame preparation process, and the glue frame may cause stress deformation misalignment under the influence of the expansion of the electrode sheet of the battery cell during the cycling process of the battery cell, affecting the battery performance and ultimately leading to battery abnormalities. Summary of the Invention

[0005] Therefore, the technical problem to be solved by this application is to overcome the problems in the prior art that when using a glue frame to solve the problems of electrode sheet offset during the stacking process and slip during the transfer process of a solid-state battery, it will increase the preparation process and cause stress deformation misalignment and affect the battery performance during the cycling process of the battery cell. Thus, a solid-state battery, a preparation method thereof, and an application thereof are provided.

[0006] To this end, this application provides the following technical solutions:

[0007] According to one aspect of this application, a solid-state battery is provided, including: an electrode core and a coating wrapped on the surface of the electrode core.

[0008] The electrode core includes a composite electrode sheet and a second electrode sheet stacked together.

[0009] The composite electrode includes a first electrode and an electrolyte membrane, and the electrolyte membrane is located on both surfaces of the first electrode in its own thickness direction;

[0010] The second electrode has two opposite surfaces in its own thickness direction, and at least one surface is provided with a limiting border around its perimeter for accommodating the composite electrode;

[0011] The composition of the limiting border is the same as that of the electrolyte membrane or the same as that of the active material layer on the second electrode;

[0012] The polarities of the first electrode and the second electrode are opposite.

[0013] According to the above technical means, in the present application, by providing a limiting border with a composition the same as that of the electrolyte membrane or the same as that of the active material layer on the second electrode around the perimeter of the second electrode, in cooperation with the setting of the outer film of the electrode core, the offset and slip of the electrode during the traditional non-separator lamination process and the electrode core transfer process are avoided, and the abnormality of the electrode core after isostatic pressing is avoided; at the same time, since the composition of the limiting border is the same as that of the electrolyte membrane or the same as that of the active material layer on the second electrode, the degree of stress deformation is consistent with that of the electrolyte membrane or the active material layer on the second electrode, and the stress deformation misalignment that may be caused by the expansion of the electrode core during the cycling of the electrode core can be avoided. The material used for the limiting border in the present application is the slurry in the electrode preparation process, and there is no need to separately configure a mixing device for the limiting frame and no separate glue solution preparation process, which simplifies the operation.

[0014] In some optional embodiments, the width of the limiting border is 0.1 - 3 mm. By limiting the width of the limiting border to the above range in the present application, the fracture of the limiting border can be effectively avoided while taking into account the energy density of the battery. If the width of the limiting border < 0.1 mm, it may cause fractures at the edge of the final electrode core. If the width of the limiting border > 3 mm, the border area is too large, resulting in loss of energy density.

[0015] In some optional embodiments, when the limiting border is only provided on one surface of the second electrode, the thickness of the limiting border is 99.5% - 100.5% of the thickness of the composite electrode;

[0016] Or, when the limiting border is provided on both surfaces of the second electrode, the total thickness of the limiting borders on both sides is 99.5% - 100.5% of the thickness of the composite electrode.

[0017] By limiting the thickness of the limiting frame, the present application realizes the fitting of the second pole piece and the composite pole piece, avoiding the slippage of the pole pieces after lamination and the formation of steps between the composite pole piece and the second pole piece due to the thickness difference. Preferably, the present application provides a limiting frame on one surface of the second pole piece, thus avoiding the alignment problem of two adjacent limiting frames during the subsequent lamination process.

[0018] In some alternative embodiments, when the composition of the limiting frame is the same as that of the electrolyte membrane, it includes a solid electrolyte and a binder with a mass ratio of 93-98:2-7;

[0019] and / or, when the material of the limiting frame is the same as that of the active material layer on the second pole piece, it includes an active material, an electrolyte, a conductive agent, and a binder with a mass ratio of 72-94.3:0-26:1.2-2:2-5.

[0020] By limiting the composition of the limiting frame, the present application can directly use the slurry for preparing the pole piece or the electrolyte membrane, without remaking a new slurry, simplifying the processing procedure and shortening the preparation process. The mechanical properties are consistent among the same formulations, and the compression amount is consistent after isostatic pressing. By limiting the specific composition, better electrical conductivity and bonding properties can be obtained, avoiding powder falling during use and further improving the battery performance.

[0021] In some alternative embodiments, the active material includes at least one of a positive electrode active material and a negative electrode active material;

[0022] and / or, the binder includes, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), hydrogenated styrene-butadiene block copolymer (SEBS), and polyisobutylene (PIB);

[0023] and / or, the conductive agent includes, but is not limited to, at least one of carbon fiber (VGCF), conductive carbon black (SP), Ketjen black, and acetylene black.

[0024] According to another aspect of the present application, a method for preparing the above-mentioned solid-state battery is provided, including the following steps:

[0025] S1. Prepare a first pole piece, compound the first pole piece with an electrolyte membrane, and die-cut to obtain a composite pole piece;

[0026] S2. Prepare a second pole piece, coat a limiting slurry around at least one side surface thereof, and dry to form a second pole piece with a limiting frame;

[0027] S3. Stack the laminated sheets, alternately arranging the composite electrode sheet and the second electrode sheet with a limiting frame in sequence, embed the composite electrode sheet into the limiting frame, perform film coating, and then perform hot pressing.

[0028] In the manufacturing method provided by the present application, by coating a limiting slurry on at least one surface of the second electrode sheet, after drying, a limiting frame with the same composition as the electrolyte membrane or the same as the active material layer on the second electrode sheet can be obtained. Then, stack the laminated sheets, alternately arranging the composite electrode sheet and the second electrode sheet with a limiting frame in sequence, and embed the composite electrode sheet into the limiting frame. Combine with film coating outside the electrode core. In this way, it avoids the deviation and slippage of the electrode sheet during the non-separator lamination process of the traditional electrode sheet and the cell transfer process, and avoids the abnormality of the cell after isostatic pressing. At the same time, since the composition of the limiting frame is the same as that of the electrolyte membrane or the same as the active material layer on the second electrode sheet, the degree of stress deformation is consistent with that of the electrolyte membrane or the active material layer on the second electrode sheet, which can avoid the stress deformation misalignment that may be caused by the expansion of the electrode sheet of the cell during the cycling process of the cell and improve the battery performance. In addition, since the composition of the limiting frame is the same as that of the electrolyte membrane or the same as the active material layer on the second electrode sheet, the slurries of the electrode sheet and the electrolyte membrane can be directly used during preparation without remaking new slurries, which simplifies the processing procedure and shortens the preparation process.

[0029] In some optional embodiments, it further includes: tab welding, isostatic pressing.

[0030] Through isostatic pressing in the present application, densification of the electrode core can be achieved, and the energy density can be improved.

[0031] In some optional embodiments, a thermoplastic material is used for film coating;

[0032] In the present application, when a thermoplastic material is used for film coating, the thermoplastic material will shrink during the subsequent hot pressing process, achieving a tight wrapping of the electrode core, having an auxiliary limiting effect, and being able to further avoid the slippage and deviation of the electrode sheet during the lamination and cell transfer processes.

[0033] In some optional embodiments, the temperature of the hot pressing is 50 - 110 °C, the time is 5 - 50 min, and the pressure is 0.3 - 0.8 MPa.

[0034] In the present application, by adjusting the parameters of the hot pressing to the above range, the thermoplastic material can shrink smoothly under the above conditions and fit on each plane of the cell, further improving the battery performance.

[0035] In some optional embodiments, the thickness of the thermoplastic material is 6 - 100 μm.

[0036] In this application, by limiting the thickness of the thermoplastic material to the above range, it is possible to ensure that the thermoplastic material film does not break during the pressurization and heating process, and at the same time, the time required for softening and shrinking can be ≤ 50 min, controlling a reasonable time range and improving production efficiency.

[0037] And / or, the thermoplastic material includes at least one of a polyvinyl chloride film, a polyethylene terephthalate film, and an oriented polystyrene film.

[0038] In some alternative embodiments, in S1, the method of laminating the first electrode sheet with the electrolyte membrane includes at least one of roll pressing, flat pressing, and isostatic pressing.

[0039] According to another aspect of the present application, there is provided an electrical device including the above-mentioned solid-state battery or a solid-state battery prepared by the above-mentioned preparation method.

[0040] The technical solution of the present application has the following advantages:

[0041] (1) For the solid-state battery provided by the present application, by providing a limiting frame with the same composition as the electrolyte membrane or the same as the active material layer on the second electrode sheet around the second electrode sheet, in cooperation with the setting of the outer film of the electrode core, it avoids the offset and slip of the electrode sheet during the traditional non-separator lamination process of the electrode sheet and the transfer process of the battery cell, and avoids the abnormality of the battery cell after isostatic pressing; at the same time, since the composition of the limiting frame is the same as the electrolyte membrane or the same as the active material layer on the second electrode sheet, the stress deformation degree is consistent with the electrolyte membrane or the active material layer on the second electrode sheet, and it can avoid the stress deformation misalignment that may be caused by the expansion of the electrode sheet of the battery cell during the cycling process of the battery cell. The material used for the limiting frame of the present application is the slurry in the preparation process of the electrode sheet, and there is no need to separately configure a mixing device for the limiting frame and no separate glue solution preparation process, which simplifies the operation.

[0042] (2) For the solid-state battery provided by the present application, by limiting the width of the limiting frame to the above range, it can effectively avoid the fracture of the limiting frame while taking into account the energy density of the battery.

[0043] (3) For the solid-state battery provided by the present application, by limiting the thickness of the limiting frame, effective fitting of the second electrode sheet and the composite electrode sheet can be achieved, and slippage of the electrode sheet after lamination and thickness difference can be avoided, so as to prevent the formation of a step between the composite electrode sheet and the second electrode sheet after isostatic pressing. The present application preferably provides a limiting frame on one surface of the second electrode sheet, so as to avoid the alignment problem of two adjacent limiting frames during the subsequent lamination process.

[0044] (4) For the solid-state battery provided by the present application, by limiting the composition of the limiting frame, good electrical conductivity and bonding performance can be obtained, powder falling during use can be avoided, and the battery performance can be further improved.

[0045] (5) The manufacturing method of the solid-state battery provided by this application involves coating a limiting slurry on at least one surface of the second electrode sheet. After drying, a limiting border with the same composition as the electrolyte membrane or the active material layer on the second electrode sheet can be obtained. Then, laminating is carried out, enabling the composite electrode sheet and the second electrode sheet with the limiting border to be alternately arranged in sequence, and the composite electrode sheet is embedded within the limiting border. Coupled with the encapsulation treatment outside the electrode core, this avoids the offset and slippage of the electrode sheets during the traditional non-separator laminating process and the electrode core transfer process, and prevents abnormalities in the electrode core after isostatic pressing. At the same time, since the composition of the limiting border is the same as that of the electrolyte membrane or the active material layer on the second electrode sheet, the degree of stress deformation is consistent with that of the electrolyte membrane or the active material layer on the second electrode sheet, which can avoid the stress deformation misalignment that may be caused by the expansion of the electrode sheets of the electrode core during the battery cycling process and improve the battery performance. Additionally, since the composition of the limiting border is the same as that of the electrolyte membrane or the active material layer on the second electrode sheet, the slurries of the electrode sheet and the electrolyte membrane can be directly used during preparation without the need to remake new slurries, simplifying the processing procedures and shortening the manufacturing process.

[0046] (6) The manufacturing method of the solid-state battery provided by this application uses a thermoplastic material for encapsulation treatment. During the subsequent hot pressing process, the thermoplastic material will shrink, achieving a tight encapsulation of the electrode core and having an auxiliary limiting effect, which can further avoid the slippage and offset of the electrode sheets during the laminating and electrode core transfer processes.

[0047] (7) The manufacturing method of the solid-state battery provided by this application further includes isostatic pressing treatment, which can achieve the densification of the electrode core and improve the energy density.

[0048] (8) The manufacturing method of the solid-state battery provided by this application can enable the thermoplastic material to shrink flat under the above conditions and fit on each plane of the electrode core by adjusting the hot pressing treatment parameters, further improving the battery performance.

[0049] (9) The manufacturing method of the solid-state battery provided by this application can ensure that the thermoplastic material film does not break during the pressurization and heating process and can make the time required for softening and shrinking ≤ 50 min by limiting the thickness of the thermoplastic material to the above range, controlling a reasonable time range, and improving the production efficiency.

[0050] (10) The electrical equipment provided by this application has the same advantages as the solid-state battery provided by this application due to the adoption of the solid-state battery provided by this application, which will not be elaborated here.

[0051] The additional aspects and advantages of this application will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of this application. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] To more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings required for the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0053] Figure 1 is a flowchart of the preparation method of the solid-state battery in Embodiment 1 of the present application;

[0054] Figure 2 is a schematic diagram of the coating area of the second electrode sheet in Embodiment 1 of the present application;

[0055] Figure 3 is a schematic diagram of the structure of the electrode core obtained after stacking in Embodiment 1 of the present application;

[0056] Figure 4 is a schematic diagram of the structure of the encapsulation in Embodiment 1 of the present application;

[0057] Figure 5 is a top view of the heating platform in Embodiment 1 of the present application;

[0058] Reference numerals:

[0059] 1, the first heating surface; 2, the second heating surface; 3, the third heating surface; 4, the fourth heating surface. Specific embodiments

[0060] The following will describe the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, rather than for limiting the protection scope of the present invention.

[0061] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the text of this application are intended to cover non-exclusive inclusion.

[0063] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order, or primary-secondary relationship of the indicated technical features.

[0064] Referring to "embodiments" herein means that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appearing at various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0065] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of the specific range. The range defined in this way can include the end values and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. In this application, unless otherwise stated, the numerical range "a - b" represents the abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only the abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter can be, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0066] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone.

[0067] In the description of the embodiments of this application, the term "at least one" refers to one or more than two (including two).

[0068] Unless otherwise specified, all steps of this application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out sequentially, or may also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may also include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0069] For those embodiments where specific experimental steps or conditions are not indicated, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments whose manufacturers are not indicated, they are all conventional reagent products that can be obtained commercially.

[0070] As described in the background art, in the prior art, a glue frame is used to solve the problems of the offset of the electrode sheet during the lamination process of the solid-state battery and the slippage during the transfer process. However, the use of the glue frame increases the preparation process, and the glue frame will be affected by the expansion of the electrode sheet of the battery cell during the cycling process, resulting in stress deformation misalignment and affecting the battery performance.

[0071] Based on this, this application provides a solid-state battery, including: a core and a coating wrapped on the surface of the core,

[0072] The core includes a composite electrode sheet and a second electrode sheet stacked together,

[0073] The composite electrode sheet includes a first electrode sheet and an electrolyte membrane, and the electrolyte membrane is located on both surface sides of the first electrode sheet in its own thickness direction;

[0074] The second electrode sheet has two opposite surfaces in its own thickness direction, and at least one surface is provided with a limiting frame around it for accommodating the composite electrode sheet;

[0075] The limiting frame is made of the same material as the electrolyte membrane or the same as the active material layer on the second electrode sheet;

[0076] The polarities of the first electrode sheet and the second electrode sheet are opposite.

[0077] According to the above technical means, in the present application, a limiting border is provided around the second pole piece, which is composed of the same material as the electrolyte membrane or the active material layer on the second pole piece. In combination with the arrangement of the outer film of the pole core, it avoids the pole piece offset and slip caused during the non-separator lamination process of the traditional pole piece and the cell transfer process, and avoids the abnormality of the cell after isostatic pressing. At the same time, since the composition of the limiting border is the same as that of the electrolyte membrane or the active material layer on the second pole piece, the stress deformation degree is consistent with that of the electrolyte membrane or the active material layer on the second pole piece, which can avoid the stress deformation misalignment that may be caused by the expansion of the cell pole piece during the cell cycle. The material used for the limiting border in the present application is the slurry in the pole piece preparation process, without the need to separately configure a mixing device for the limiting frame and without a separate glue solution preparation process, which simplifies the operation.

[0078] In some optional embodiments, the width of the limiting border is 0.1-3 mm. As an example, the width of the limiting border can be 0.1 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.3 mm, 2.5 mm, 2.7 mm, 3 mm, or within the range composed of any of the above values. By limiting the width of the limiting border to the above range in the present application, it can effectively avoid the fracture of the limiting border while taking into account the energy density of the battery. If the width of the limiting border <0.1 mm, it may cause fractures at the edge of the final cell. If the width of the limiting border >3 mm, the border area is too large, resulting in losses in terms of energy density.

[0079] In some optional embodiments, when the limiting border is only provided on one surface of the second pole piece, the thickness of the limiting border is 99.5%-100.5% of the thickness of the composite pole piece. Optionally, the two thicknesses are equal.

[0080] Or, when the limiting border is provided on both surfaces of the second pole piece, the total thickness of the limiting borders on both sides is 99.5%-100.5% of the thickness of the composite pole piece; optionally, the two thicknesses are equal.

[0081] By limiting the thickness of the limiting border in the present application, the fitting of the second pole piece and the composite pole piece is achieved, avoiding the pole piece slip after lamination and the step formed between the composite pole piece and the second pole piece due to the thickness difference after isostatic pressing. The present application preferably provides a limiting border on one surface of the second pole piece, so as to avoid the alignment problem of adjacent two limiting borders during the subsequent lamination process.

[0082] In some optional embodiments, when the composition of the limiting frame is the same as that of the electrolyte membrane, it contains a solid electrolyte and a binder with a mass ratio of 93-98:2-7. When the material of the limiting frame is the same as the composition of the active material layer on the second electrode sheet, it contains an active material, an electrolyte, a conductive agent, and a binder with a mass ratio of 72-94.3:0-26:1.2-2:2-5.

[0083] Through the limitation of the composition of the limiting frame in this application, the slurry for preparing the electrode sheet or the electrolyte membrane can be directly used without remaking a new slurry, which simplifies the processing procedure and shortens the preparation process. The mechanical properties are consistent among the same formulations, and the compression amount is the same after isostatic pressing. Through the limitation of the specific composition, good electrical conductivity and bonding properties can be obtained, avoiding powder falling during use and further improving the battery performance.

[0084] In some optional embodiments, the active material includes at least one of a positive electrode active material or a negative electrode active material;

[0085] Those skilled in the art can understand that the selection of the active material is related to the polarity of the second electrode sheet. If the second electrode sheet is a negative electrode sheet, then the active material is a negative electrode active material; if the second electrode sheet is a positive electrode sheet, then the active material is a positive electrode active material. The selection of specific solid electrolytes, negative electrode active materials, and positive electrode active materials are all conventional in the art. For example, the solid electrolyte includes but is not limited to Li 10 GeP2S 12 (LGPS), Li6PS5Cl (LPSCl), sulfide solid electrolyte (LPS, commonly Li3PS4 or Li7P3S 11 etc.) of at least one; the negative electrode active material includes but is not limited to at least one of nano-silicon, silicon-carbon material, and graphite; the positive electrode active material includes but is not limited to at least one of NCM5 series, NCM6 series, NCM8 series, NCM9 series, and lithium-rich manganese-based positive electrode material (LRM).

[0086] And / or, the binder includes but is not limited to at least one of polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), hydrogenated styrene-butadiene block copolymer (SEBS), and polyisobutylene (PIB);

[0087] And / or, the conductive agent includes but is not limited to at least one of carbon fiber (VGCF), conductive carbon black (SP), Ketjen black, and acetylene black.

[0088] According to another aspect of the present application, a preparation method of the above-mentioned solid-state battery is provided, including the following steps:

[0089] S1. Prepare the first electrode sheet, laminate it with the electrolyte membrane, and die-cut to obtain a composite electrode sheet.

[0090] S2. Prepare the second electrode sheet, coat a limiting slurry around the perimeter of at least one side surface thereof, and dry it to form a second electrode sheet with a limiting border.

[0091] S3. Stack the sheets, alternately arrange the composite electrode sheet and the second electrode sheet with the limiting border in sequence, embed the composite electrode sheet into the limiting border, perform film wrapping, and hot pressing treatment.

[0092] In the preparation method provided by this application, by coating a limiting slurry on at least one side surface of the second electrode sheet, a limiting border having the same composition as the electrolyte membrane or the active material layer on the second electrode sheet can be obtained after drying. Then, stack the sheets, alternately arrange the composite electrode sheet and the second electrode sheet with the limiting border in sequence, and embed the composite electrode sheet into the limiting border. Combine with film wrapping treatment outside the electrode core, thus avoiding the offset and slip of the electrode sheet during the traditional non-separator sheet stacking process and the electrode core transfer process, and avoiding the abnormality of the electrode core after isostatic pressing. At the same time, since the composition of the limiting border is the same as the electrolyte membrane or the active material layer on the second electrode sheet, the stress deformation degree is consistent with the electrolyte membrane or the active material layer on the second electrode sheet, which can avoid the stress deformation misalignment that may be caused by the expansion of the electrode sheet of the electrode core during the cycling process of the battery, and improve the battery performance. In addition, the composition of the limiting border is the same as the electrolyte membrane or the active material layer on the second electrode sheet. During preparation, the slurries of the electrode sheet and the electrolyte membrane can be directly used without remaking new slurries, simplifying the processing procedure and shortening the preparation process.

[0093] In some optional embodiments, it further includes: tab welding, isostatic pressing treatment.

[0094] Through isostatic pressing treatment in this application, densification of the electrode core can be achieved, and the energy density can be improved.

[0095] In some optional embodiments, a thermoplastic material is used for film wrapping;

[0096] In this application, when film wrapping treatment is performed using a thermoplastic material, the thermoplastic material will shrink during the subsequent hot pressing treatment, achieving a tight wrapping of the electrode core, having an auxiliary limiting effect, and being able to further avoid the slip and offset of the electrode sheet during the sheet stacking and electrode core transfer processes.

[0097] In some optional embodiments, the temperature of the hot pressing treatment is 50 - 110 °C, the time is 5 - 50 min, and the pressure is 0.3 - 0.8 MPa. As an example, the temperature of the hot pressing treatment can be 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, or within the range composed of any of the above values; the time of the hot pressing treatment can be 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, or within the range composed of any of the above values; the pressure of the heat treatment can be 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, or within the range composed of any of the above values.

[0098] In this application, by adjusting the parameters of the hot pressing treatment to the above ranges, the thermoplastic material can be flattened and shrunk under the above conditions, adhered to each plane of the battery cell, and further improve the battery performance.

[0099] In some optional embodiments, the thickness of the thermoplastic material is 6 - 100 μm; as an example, the thickness of the thermoplastic material can be 6 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or within the range composed of any of the above values.

[0100] In this application, by limiting the thickness of the thermoplastic material to the above range, it can be ensured that the thermoplastic material film does not break during the pressurization and heating process, and at the same time, the time required for softening and shrinking can be ≤ 50 min, controlling a reasonable time range and improving production efficiency.

[0101] And / or, the thermoplastic material includes at least one of a polyvinyl chloride film, a polyethylene terephthalate film, and an oriented polystyrene film.

[0102] In some optional embodiments, in S1, the method of laminating the first electrode sheet with the electrolyte membrane includes at least one of roll pressing, flat pressing, and isostatic pressing.

[0103] In this application, the first electrode sheet includes a first current collector and a first active material layer located on at least one surface of the first electrode sheet; the second electrode sheet includes a second current collector and a second active material layer located on at least one surface of the second electrode sheet. Among them, the materials, compositions, and preparation methods used in the first current collector, the second current collector, the first active layer, and the second active layer are all conventional in the art and can include any technologies disclosed in the prior art. The materials, compositions, and preparation methods used in the electrolyte membrane are all conventional in the art and can include any technologies disclosed in the prior art.

[0104] According to another aspect of the present application, there is provided an electrical device including the above-mentioned solid-state battery or the solid-state battery prepared by the above-mentioned preparation method.

[0105] It can be understood that in the electrical device provided by the present application, the solid-state battery can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device can be, but is not limited to, a mobile device (such as a mobile phone, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0106] The electrical device provided by the present application has the same advantages as the above-mentioned solid-state battery due to the adoption of the solid-state battery provided by the present application, and will not be elaborated here.

[0107] Next, the present application will be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way.

[0108] Embodiment 1

[0109] This embodiment provides a solid-state battery. The flowchart of its preparation method is as Figure 1 shown. The specific preparation method and operation parameters are as follows:

[0110] S1. Prepare the first electrode sheet. In this embodiment, the first electrode sheet is a positive electrode sheet. The first electrode sheet is compounded with the electrolyte membrane and die-cut to obtain a compound electrode sheet for use. In this embodiment, the positive electrode sheet includes an 8-μm-thick aluminum foil with 2-μm carbon layer foils on both sides; 270-μm active material layers are included on both sides of the positive electrode sheet, and the composition of the active material layer is: N9C 0.5 M 0.5 : LPSCl: PIB: SP = 72: 26: 2: 2; the electrolyte membrane is coated on the same carbon-coated aluminum foil, and the single-sided thickness of the electrolyte membrane is 80 μm, and the composition is: LPSCl: PIB = 98: 2. The electrolyte membrane is compounded on the positive electrode sheet by roll pressing;

[0111] S2. Die-cut the electrode roll of the second electrode sheet to obtain the second electrode sheet, and then coat the limiting slurry on the four peripheral edges of one surface of the second electrode sheet. In this embodiment, the second electrode sheet is a negative electrode sheet. In this embodiment, the composition of the coated limiting slurry is the same as that of the negative electrode slurry, and the composition of the negative electrode slurry includes: pure silicon: SP: CNTs: CMC: SBR = 94.3: 1.1: 0.5: 2.8: 1.3. The slurry is extruded and coated on the edge of the negative electrode sheet with a width of 0.1-3 mm by the pressure of an extrusion die head. The area to be coated is as Figure 2 shown and is Figure 2Four sides with a width of 1.5 mm; drying to obtain a limiting border on one side surface of the second electrode sheet, and the thickness of the limiting border is equal to the thickness of the above-mentioned composite electrode sheet;

[0112] S3, stack the second electrode sheets, composite electrode sheets, second electrode sheets, and composite electrode sheets in sequence after drying, so that the composite electrode sheets are embedded in the limiting borders on the second electrode sheets.

[0113] S4, transfer the stacked electrode core (as shown in Figure 3 ) to the film wrapping platform, and a thermoplastic film with a thickness of 50 μm is arranged on the film wrapping platform, as shown in Figure 4 . The heat-shrinkable film is polyvinyl chloride, and the film is provided with two square openings (in this embodiment, the openings are to reduce the overlapping part of the film near the bottom), and the film is provided with a left-right symmetric structure. Place the stacked battery cell in the dashed box on one side of the film, and wrap all five sides except the electrode tab surface of the electrode core in the film.

[0114] S5, clamp and transfer the electrode core wrapped with the film to the heating platform. The top view of the heating platform is as shown in Figure 5 , and 5 heating surfaces are provided. Place the large surface of the battery cell on the second heating surface 2 (i.e., the bottom heating surface) in Figure 5 , move the first heating surface 1, the third heating surface 3, and the fourth heating surface 4 to heat in the stacking thickness direction, and do not heat the side for subsequent welding of the electrode tabs. Finally, heat the other large surface with the top heating surface above the second heating surface. The parameters of the second heating surface and the top heating surface are 0.6 MPa and 75 °C, the parameter of the first heating surface is 0.3 MPa and 70 °C, and the parameters of the third heating surface 3 and the fourth heating surface 4 are 0.3 MPa and 90 °C, and the heating time is 20 min. After heating, the thermoplastic material shrinks and is shaped, binds the inside of the electrode core, tightly wraps the electrode core, and prevents the electrode sheets from slipping during the transfer of the electrode core.

[0115] S6, after thermoplastic shaping, perform welding of the electrode tab adapter, aluminum-plastic film encapsulation, electrode tab welding, isostatic densification treatment, and test the capacity and internal resistance of the battery cell.

[0116] Example 2

[0117] This embodiment provides a solid-state battery. Compared with Example 1, the difference is that the composition of the limiting border is the same as that of the electrolyte membrane, that is, the limiting slurry in step S2 is the electrolyte slurry, and the composition is LPSCl:PIB = 98:2.

[0118] Example 3

[0119] This embodiment provides a solid-state battery. Compared with Example 1, the difference is that the width of the limiting border is 0.5 mm.

[0120] Example 4

[0121] This embodiment provides a solid - state battery. Compared with Embodiment 1, the difference is that the width of the limiting border is 2.6 mm.

[0122] Embodiment 5

[0123] This embodiment provides a solid - state battery. Compared with Embodiment 1, the difference is that the limiting borders are arranged on both side surfaces of the second pole piece. The thicknesses of the limiting borders on both sides are the same, and the total thickness of the limiting borders on both sides is equal to the thickness of the composite pole piece, that is, in step S2, the limiting paste is coated on both side surfaces of the second pole piece. It should be noted that during the lamination process, the limiting borders on adjacent pole pieces should be aligned.

[0124] Embodiment 6

[0125] This embodiment provides a solid - state battery. Compared with Embodiment 2, the difference is that the polarities of the first pole piece and the second pole piece are interchanged, that is, the first pole piece is the negative pole piece and the second pole piece is the positive pole piece.

[0126] Comparative Example 1

[0127] This comparative example provides a solid - state battery. Compared with Embodiment 1, the difference is that an existing - technology glue frame is used instead of the limiting border. The material of the glue frame is UV glue, and it is formed by means such as screen printing and then light curing.

[0128] Comparative Example 2

[0129] This comparative example provides a solid - state battery. Compared with Embodiment 1, the difference is that no limiting border is arranged on the second pole piece, that is, the first pole piece and the second pole piece are directly laminated.

[0130] Comparative Example 3

[0131] This comparative example provides a solid - state battery. Compared with Embodiment 1, the difference is that it does not include the encapsulation film.

[0132] Test Example

[0133] The solid - state batteries provided in each embodiment and comparative example are subjected to performance tests as follows:

[0134] 1. Cycling performance

[0135] Under the condition of a clamping pressure of 25 MPa, at 25 °C, the voltage range is 2.5 - 4.25 V. Charging: constant current of 0.1C until constant voltage and then the current < 0.05C; Discharging: constant current of 0.1C until 2.5 V, and cycle charge - discharge 50 times to obtain the discharge capacity retention rate.

[0136] 2. Capacity

[0137] Capacity test: Under the clamping pressure condition of 25 MPa, at 25 °C, the voltage range is 2.5 - 4.25 V, charging: constant current of 0.1C until constant voltage and the current < 0.05C; discharging: constant current discharge of 0.1C until 2.5 V, and then conduct the discharge capacity test.

[0138] 3. AC impedance

[0139] Use an AC impedance analyzer to conduct an AC impedance test at a frequency of 1 KHz and read the impedance value.

[0140] 4. Short - circuit rate

[0141] Select 10 battery cells from the examples and comparative examples respectively for charge - discharge using the above strategy. After 10 cycles, disassemble them and test the voltage of a single positive electrode sheet. If the electrode sheet voltage < 0.2 V, it is determined that the positive electrode sheet has a short - circuit abnormality and the battery cell is short - circuited. The number of stacked layers of the selected battery cells is 8 layers of positive electrode sheets and 9 layers of negative electrode sheets.

[0142] The specific test results are shown in the following table:

[0143] Table 1

[0144] Group Cycling performance Capacity / mAh AC impedance / Ω Short - circuit rate Example 1 97％ 5560 0.05 2.5％ Example 2 99％ 5591 0.04 2.5％ Example 3 95％ 5565 0.05 5％ Example 4 96％ 5574 0.05 1.25％ Example 5 98％ 5582 0.04 1.25％ Example 6 97％ 5509 0.05 2.5％ Comparative Example 1 82％ 5496 0.07 50％ Comparative Example 2 75％ 5478 0.09 60％ Comparative Example 3 80％ 5492 0.08 20％

[0145] It can be seen from the test results in the above table that the limiting border in the examples of the present application has advantages in cycle performance, capacity, AC impedance and short - circuit compared with the rubber frames in the prior art and the comparative examples without a limiting border or without a coating film. The material of the limiting border is the composition material of the active material layer of the electrode sheet or the composition material of the electrolyte membrane. No other component materials are introduced, minimizing the impact on the electrode sheet during the manufacturing process, reducing the influence of the limiting border on the capacity and cycle of the battery cell, and improving the short - circuit situation at the same time.

[0146] Obviously, the above - mentioned examples are only for clear illustration and not a limitation of the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A solid-state battery, characterized in that, Comprising: a core and a coating film covering the surface of the core, the core includes a composite electrode sheet and a second electrode sheet arranged in a stacked manner, the composite electrode sheet includes a first electrode sheet and an electrolyte film, and the electrolyte film is located on both surfaces of the first electrode sheet in the thickness direction of the first electrode sheet itself; the second electrode sheet has two opposite surfaces in its own thickness direction, and at least one of the surfaces is provided with a limiting frame around its perimeter for accommodating the composite electrode sheet; the composition of the limiting frame is the same as that of the electrolyte film or the same as that of the active material layer on the second electrode sheet; the polarities of the first electrode sheet and the second electrode sheet are opposite.

2. The solid-state battery according to claim 1, wherein The width of the limiting frame is 0.1 - 3 mm.

3. The solid-state battery according to claim 1, characterized in that, When the limiting frame is only provided on one surface of the second electrode sheet, the thickness of the limiting frame is 99.5% - 100.5% of the thickness of the composite electrode sheet; Or, when the limiting frame is provided on both surfaces of the second electrode sheet, the total thickness of the limiting frames on both sides is 99.5% - 100.5% of the thickness of the composite electrode sheet.

4. The solid-state battery according to any one of claims 1-3, characterized in that, When the composition of the limiting frame is the same as that of the electrolyte film, it includes a solid electrolyte and a binder with a mass ratio of 93 - 98:2 - 7; and / or, when the composition of the limiting frame is the same as that of the active material layer on the second electrode sheet, it includes an active material, an electrolyte, a conductive agent, and a binder with a mass ratio of 72 - 94.3:0 - 26:1.2 - 2:2 - 5.

5. The solid-state battery according to claim 4, characterized in that, The active material includes at least one of a positive electrode active material or a negative electrode active material; and / or, the binder includes at least one of polyvinylidene fluoride, polyacrylic acid, styrene - butadiene rubber, and sodium carboxymethyl cellulose; and / or, the conductive agent includes at least one of carbon fiber, conductive carbon black, Ketjen black, and acetylene black.

6. A method for preparing a solid-state battery according to any one of claims 1-5, characterized in that, Including the following steps: S1, prepare a first electrode sheet, composite the first electrode sheet with an electrolyte film, and die - cut to obtain a composite electrode sheet; S2, prepare a second electrode sheet, coat a limiting paste around the perimeter of at least one side surface thereof, and dry to form a second electrode sheet with a limiting frame; S3, stack the sheets, alternately arrange the composite electrode sheet and the second electrode sheet with the limiting frame in sequence, embed the composite electrode sheet into the limiting frame, coat with a film, and perform hot - pressing treatment.

7. The method for preparing a solid-state battery according to claim 6, wherein It also includes: tab welding and isostatic pressing treatment.

8. The manufacturing method of the solid-state battery according to claim 6, characterized in that, Coat with a film using a thermoplastic material; and / or, the temperature of the hot - pressing treatment is 50 - 110°C, the time is 5 - 50 min, and the pressure is 0.3 - 0.8 MPa.

9. The method for preparing a solid-state battery according to claim 8, wherein The thickness of the thermoplastic material is 6 - 100 μm; and / or, the thermoplastic material includes at least one of a polyvinyl chloride film, a polyethylene terephthalate film, and an oriented polystyrene film; and / or, in S1, the method of composite - bonding the first electrode sheet and the electrolyte film includes at least one of roll - pressing, flat - pressing, and isostatic pressing.

10. An electrical device, characterized in that, It includes a solid - state battery according to any one of claims 1 - 5 or a solid - state battery prepared by the preparation method according to any one of claims 6 - 9.

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