Solid-state battery

Abstract

The application provides a solid-state battery, which comprises a negative electrode sheet, a solid-state electrolyte layer and a positive electrode assembly arranged in sequence, the positive electrode assembly comprises a separator bag and a positive electrode sheet in the separator bag, an edge region of the separator bag is formed into a closed hole part, a plane where the negative electrode sheet is located is a first plane, a projection of the solid-state battery in a thickness direction, and a projection of the solid-state electrolyte layer on the first plane is located in a projection of the closed hole part on the first plane. In the cycle process of the solid-state battery, when lithium dendrites are formed on the negative electrode sheet, and the lithium dendrites extend to the positive electrode assembly along the edge of the solid-state electrolyte layer, the lithium dendrites will preferentially contact the edge region of the separator bag, the edge region of the separator bag is formed into a closed hole part, the lithium dendrites are not easy to grow in the closed hole part and are not easy to pierce the closed hole part, and then the lithium dendrites are not easy to contact the positive electrode sheet in the separator bag, thereby reducing the risk of short circuit in the solid-state battery.

Description

Technical Field

[0001] This application relates to the field of solid-state battery technology, and more particularly to a solid-state battery. Background Technology

[0002] Because solid-state batteries have a solid electrolyte layer, lithium dendrites formed on the negative electrode during cycling are less likely to pierce the solid electrolyte layer. However, lithium dendrites tend to grow outward and extend along the edge of the solid electrolyte layer, coming into contact with the positive electrode of the solid-state battery, causing a short circuit inside the solid-state battery. Utility Model Content

[0003] This application provides a solid-state battery to improve the technical problem that solid-state batteries are prone to internal short circuits.

[0004] To achieve the above objectives, this application provides a solid-state battery comprising a negative electrode, a solid electrolyte layer, and a positive electrode assembly stacked sequentially. The positive electrode assembly includes a separator bag and a positive electrode located within the separator bag. The edge region of the separator bag is formed into a closed-hole portion. Taking the plane where the negative electrode is located as a first plane, and projecting along the thickness direction of the solid-state battery, the edge of the solid electrolyte layer projected onto the first plane is located within the projected portion of the closed-hole portion onto the first plane.

[0005] Optionally, the positive electrode assembly further includes a silicon dioxide layer that covers the outer surface of the closed-cell portion.

[0006] Optionally, the silica layer comprises silica particles with an average particle size of 0.1 μm to 3 μm.

[0007] Optionally, the thickness of the silicon dioxide layer is 1 μm to 10 μm.

[0008] Optionally, the negative electrode is a lithium metal negative electrode.

[0009] Optionally, along the thickness direction of the solid-state battery, the orthogonal projection of the positive electrode sheet onto the first plane lies within the orthogonal projection of the negative electrode sheet onto the first plane.

[0010] Optionally, along the thickness direction of the solid-state battery, the orthogonal projection of the negative electrode sheet onto the first plane lies within the orthogonal projection of the solid electrolyte layer onto the first plane.

[0011] Optionally, the separator bag includes separators located on opposite sides of the positive electrode sheet, the edge regions of the separators protruding from the edge of the positive electrode sheet and hot-pressed together to form the closed-cell portion.

[0012] Optionally, the edge region of the separator protrudes from the edge of the positive electrode sheet by a width of 2mm to 20mm.

[0013] Optionally, the separator includes a base film layer and a first adhesive layer and a second adhesive layer located on opposite sides of the base film layer. The separator is bonded to the positive electrode sheet through the first adhesive layer, and the separator is bonded to the solid electrolyte layer through the second adhesive layer.

[0014] Optionally, the first adhesive layer and the second adhesive layer each independently comprise at least one of polyvinylidene fluoride, polyacrylic acid, sodium carboxymethyl cellulose, and styrene-butadiene rubber; and / or, the thickness of the first adhesive layer is 2 μm to 10 μm, and the thickness of the second adhesive layer is 2 μm to 10 μm.

[0015] Optionally, the positive electrode sheet includes a positive current collector and a positive active material layer located on the positive current collector. The positive electrode assembly also includes a positive electrode tab, one end of which extends into the separator bag and is integrally formed with the positive current collector, and the other end of which is located outside the separator bag.

[0016] Optionally, the length of the portion of the positive electrode tab located outside the separator bag is 0.1 mm to 20 mm; and / or, the positive electrode active material layer includes at least one of lithium cobalt oxide and lithium nickel cobalt manganese oxide.

[0017] Optionally, the solid-state battery includes at least one of all-solid-state batteries and semi-solid-state batteries.

[0018] In the solid-state battery of this application embodiment, during cycling, when lithium metal forms lithium dendrites on the negative electrode and the lithium dendrites extend along the edge of the solid electrolyte layer to contact the positive electrode component, the lithium dendrites will preferentially contact the edge area of ​​the separator bag. The edge area of ​​the separator bag forms a closed part, so the lithium dendrites are not easy to grow in the closed part or puncture the closed part. That is, the closed part can prevent the lithium dendrites from extending into the separator bag, and thus the lithium dendrites are not easy to contact the positive electrode located in the separator bag, thereby reducing the risk of internal short circuit of the solid-state battery.

[0019] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced 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 these drawings without creative effort.

[0021] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0022] Figure 1 This is an exploded view of the solid-state battery structure provided in an embodiment of this application;

[0023] Figure 2 This is a cross-sectional view of the positive electrode component in a solid-state battery provided in an embodiment of this application. Figure 1 ;

[0024] Figure 3 This is a cross-sectional view of the positive electrode component in a solid-state battery provided in an embodiment of this application. Figure 2 ;

[0025] Figure 4 This is a cross-sectional view of the positive electrode component in a solid-state battery provided in an embodiment of this application. Figure 3 ;

[0026] Explanation of reference numerals in the attached figures:

[0027] 10. Solid-state battery; 1. Negative electrode sheet; 2. Solid electrolyte layer; 3. Positive electrode assembly; 31. Separator bag; 31a. Closed pore section; 311. Separator membrane; 3111. Base film layer; 3112. First adhesive layer; 3113. Second adhesive layer; 32. Positive electrode sheet; 321. Positive current collector; 322. Positive active material layer; 33. Positive electrode tab; 34. Silicon dioxide layer. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0029] Please see Figure 1This application provides a solid-state battery 10. The solid-state battery 10 refers to a battery using a solid electrolyte. It should be noted that the solid-state battery 10 may also contain a certain amount of liquid electrolyte (i.e., electrolyte solution). As an example, the solid-state battery 10 includes at least one of an all-solid-state battery and a semi-solid-state battery. A semi-solid-state battery is a battery in which one electrode does not contain liquid electrolyte, while the other electrode contains liquid electrolyte, or where the mass or volume of solid electrolyte in a single battery cell accounts for more than half of the total mass or volume of electrolyte in the single battery cell. An all-solid-state battery is a battery in which there is no liquid electrolyte between the positive and negative electrodes; that is, the battery completely eliminates the liquid electrolyte and separator, using a solid electrolyte as the ion transport channel. As an example, the solid-state battery 10 is a lithium-ion battery.

[0030] Specifically, please see Figures 1 to 4 The solid-state battery 10 includes a negative electrode 1, a solid electrolyte layer 2, and a positive electrode assembly 3, which are stacked sequentially. The positive electrode assembly 3 includes a separator bag 31 and a positive electrode 32, wherein the positive electrode 32 is located inside the separator bag 31. The edge region of the separator bag 31 is formed into a closed portion 31a. Taking the plane where the negative electrode 1 is located as a first plane, and projecting along the thickness direction of the solid-state battery 10, the edge of the solid electrolyte layer 2 in the orthogonal projection of the first plane is located within the orthogonal projection of the closed portion 31a in the first plane.

[0031] In other words, the solid electrolyte layer 2 is located between the negative electrode plate 1 and the positive electrode component 3, with the negative electrode plate 1 and the positive electrode component 3 located on opposite sides of the solid electrolyte layer 2.

[0032] Here, the separator bag 31 refers to the bag body made of separator film 311. Separator film 311 is a microporous and porous film, therefore the separator bag 31 also has the same characteristics as the separator film.

[0033] The edge region of the separator bag 31 is formed into a closed-pore portion 31a. Within the closed-pore portion 31a, the micropores on the separator membrane 311 are closed, thereby causing the micropores on the separator membrane 311 to disappear and / or their pore size to decrease within the closed-pore portion 31a. It can be understood that compared to other regions on the separator bag 31, the porosity of the closed-pore portion 31a on the separator bag 31 is reduced. This not only reduces the channels inside the closed-pore portion 31a but also improves its strength.

[0034] When the positive electrode 32 is placed inside the separator bag 31, the edge region of the separator bag 31 includes the area on the separator bag 31 that is misaligned with the positive electrode 32 and located at the edge of the positive electrode 32. The positive electrode 32 being inside the separator bag 31 means that the positive electrode 32 is not exposed outside the separator bag 31.

[0035] For ease of subsequent description, the plane containing the negative electrode 1 will be referred to as the first plane. The thickness direction of the solid-state battery 10 is consistent with the stacking direction of the negative electrode 1, the solid electrolyte layer 2, and the positive electrode assembly 3 in the solid-state battery 10.

[0036] Please see Figure 1 Along the thickness direction of the solid-state battery 10, the edge of the solid electrolyte layer 2, projected onto the first plane, lies within the projected area of ​​the closed-hole portion 31a on the first plane. It can be understood that the separator bag 31 and the solid electrolyte layer 2 are stacked, with the edge of the separator bag 31 protruding beyond the edge of the solid electrolyte layer 2, and the edge of the solid electrolyte layer 2 corresponding to the closed-hole portion 31a. During lithium dendrite growth, on the one hand, the edge of the solid electrolyte layer 2 can guide the lithium dendrites to extend towards the closed-hole portion 31a; on the other hand, the solid electrolyte layer 2 can prevent the lithium dendrites from contacting areas on the separator bag 31 other than the closed-hole portion 31a. Since the mechanical strength of these areas is relatively low, the risk of these areas being punctured is reduced.

[0037] In this embodiment, the above-described configuration allows the solid-state battery 10 to be in operation during cycling. When lithium metal forms lithium dendrites on the negative electrode 1 and the lithium dendrites extend along the edge of the solid electrolyte layer 2 to contact the positive electrode component 3, the lithium dendrites will preferentially contact the closed portion 31a of the separator bag 31. This makes it difficult for lithium dendrites to grow in the closed portion 31a or to puncture the closed portion 31a. In other words, the closed portion 31a can prevent lithium dendrites from extending into the separator bag 31, and thus makes it difficult for lithium dendrites to contact the positive electrode 32 located in the separator bag 31, thereby reducing the risk of internal short circuits in the solid-state battery 10.

[0038] In some implementations, please refer to Figure 1 Along the thickness direction of the solid-state battery 10, the orthographic projection of the negative electrode 1 onto the first plane lies within the orthographic projection of the solid electrolyte layer 2 onto the first plane. In this case, the area of ​​the orthographic projection of the negative electrode 1 onto the first plane is smaller than the area of ​​the orthographic projection of the solid electrolyte layer 2 onto the first plane. It can be understood that the negative electrode 1 and the solid electrolyte layer 2 are stacked, with the edge of the solid electrolyte layer 2 protruding beyond the edge of the negative electrode 1. This allows the solid electrolyte layer 2 to better prevent lithium dendrites formed on the negative electrode 1 from extending towards the positive electrode assembly 3, reducing the probability of lithium dendrites reaching the positive electrode assembly 3, and thus reducing the risk of internal short circuits in the solid-state battery 10.

[0039] In some implementations, please refer to Figure 1Along the thickness direction of the solid-state battery 10, the orthographic projection of the positive electrode 32 onto the first plane lies within the orthographic projection of the negative electrode 1 onto the first plane. In this case, the area of ​​the orthographic projection of the positive electrode 32 onto the first plane is smaller than the area of ​​the orthographic projection of the negative electrode 1 onto the first plane. That is, the surface area of ​​one side of the negative electrode 1 is larger than the surface area of ​​one side of the positive electrode 32, thereby allowing the lithium ions released from the positive electrode 32 to be deposited on the negative electrode 1 as much as possible, reducing the formation of lithium dendrites, and thus reducing the risk of internal short circuits in the solid-state battery 10.

[0040] In some embodiments, along the thickness direction of the solid-state battery 10, the edge of the negative electrode 1, as projected onto the first plane, lies within the projected area of ​​the closed-cell portion 31a onto the first plane. It is understood that the edge of the separator bag 31 protrudes beyond the edge of the negative electrode 1, and the edge of the negative electrode 1 corresponds to the closed-cell portion 31a.

[0041] In some implementations, please refer to Figure 4 The positive electrode component 3 also includes a silicon dioxide layer 34, which covers the outer surface of the closed-hole portion 31a. The silicon dioxide layer 34 is a material layer containing silicon dioxide, and it is disposed on the separator bag 31 and located outside the separator bag 31, specifically on the closed-hole portion 31a. In this way, when lithium dendrites on the negative electrode 1 extend along the edge of the solid electrolyte layer 2 toward the closed-hole portion 31a, the lithium dendrites will preferentially contact the silicon dioxide layer 34. The silicon dioxide in the silicon dioxide layer 34 can chemically react with the lithium dendrites. On the one hand, the lithium dendrites are chemically reacted and etched away, which is equivalent to slowing down the growth rate of lithium dendrites. On the other hand, the product of the chemical reaction between silicon dioxide and lithium dendrites is relatively hard, which can prevent the lithium dendrites from continuing to extend toward the separator bag 31, reducing the risk of the separator bag 31 being punctured, and thus reducing the risk of short circuit caused by lithium dendrite overlap between the negative electrode 1 and the positive electrode 32. As can be seen, with the positive electrode component 3 also including a silicon dioxide layer 34, the positive electrode component 3 can create a triple barrier to the growth of lithium dendrites. The first barrier is that the silicon dioxide layer 34 can react with lithium dendrites, thus reducing the growth rate of lithium dendrites. The second barrier is that the reaction products between silicon dioxide and lithium dendrites prevent lithium dendrites from extending into the separator bag 31. The third barrier is that the closed portion 31a further prevents lithium dendrites from extending into the separator bag 31. Only by overcoming the above three barriers can the lithium dendrites on the negative electrode 1 enter the separator bag 31 and conduct to the positive electrode 32, thus greatly reducing the risk of short circuit.

[0042] In some embodiments, the silicon dioxide layer 34 is disposed only on the closed-pore portion 31a, which can effectively ensure the energy density of the solid-state battery 10.

[0043] In some embodiments, the silicon dioxide layer 34 comprises silicon dioxide particles with an average particle size of 0.1 μm to 3 μm. Within this range, the specific surface area of ​​the silicon dioxide particles can be effectively increased, thereby promoting the reaction between the silicon dioxide particles and lithium dendrites and reducing the growth rate of lithium dendrites. As an example, the average particle size of the silicon dioxide particles is 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm.

[0044] In some embodiments, the thickness of the silicon dioxide layer 34 is 1 μm to 10 μm. If the silicon dioxide layer 34 is too thin, it cannot effectively etch the lithium dendrites grown on the negative electrode, and the resulting reaction products between the silicon dioxide and lithium dendrites are relatively few, thus failing to provide a good barrier effect. On the other hand, the silicon dioxide layer 34 reduces the energy density of the solid-state battery 10 and also affects the bonding effect between the negative electrode 1, the solid electrolyte layer 2, and the positive electrode component 3, thus affecting lithium-ion transport. As an example, the thickness of the silicon dioxide layer 34 is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm.

[0045] In some embodiments, the negative electrode 1 is a lithium metal negative electrode. The lithium metal negative electrode can be made of lithium metal or a lithium alloy. Lithium metal has a high theoretical specific capacity, which can significantly improve the energy density of the solid-state battery 10. Thanks to the aforementioned positive electrode component 3, the risk of short circuits caused by lithium dendrites on the negative electrode 1 contacting the positive electrode 32 can be effectively mitigated.

[0046] In some implementations, please refer to Figure 3 The separator bag 31 includes separators 311 located on opposite sides of the positive electrode 32. The edge regions of the separators 311 protrude from the edge of the positive electrode 32 and are heat-pressed together to form closed pores 31a. It can be understood that the separator bag 31 includes two layers of separators 311 heat-pressed together. For ease of distinction, the two layers of separators 311 are referred to as the first separator and the second separator, respectively.

[0047] In the fabrication of the positive electrode assembly 3, a first separator, a positive electrode plate 32, and a second separator are sequentially stacked. The first and second separators are located on opposite sides of the positive electrode plate 32, with the positive electrode plate 32 situated between them. The edge regions of both the first and second separators protrude beyond the edge of the positive electrode plate 32, and their edges correspond to each other. Furthermore, the edge regions of the first and second separators are hot-pressed together to form a separator bag 31, within which the positive electrode plate 32 is simultaneously loaded. During hot pressing, the edge regions of the separator 311 can be closed by increasing the pressing temperature, forming closed-pore portions 31a. The hot-pressing temperature is typically related to the material of the separator 311. As an example, the separator 311 is a polyethylene (PE) film, and the hot-pressing temperature can be set to 128°C to 135°C. Within this hot-pressing temperature range, the micropores on the PE film will close.

[0048] By setting the separator bag 31 to be obtained by hot pressing the separator 311, not only can the bag making process and the pore closing process be carried out simultaneously, but the bag filling process is also synchronized with the bag making process, reducing the preparation steps of the positive electrode component 3, reducing the preparation difficulty of the positive electrode component 3, and thus reducing the production cost of the solid-state battery 10.

[0049] In some implementations, please refer to Figure 2 The edge region of the separator 311 protrudes beyond the edge of the positive electrode 32 by a width W1 ranging from 2mm to 20mm. The size of W1 affects the size of the closed portion 31a. Generally, W1 should not be too small, otherwise the closed portion 31a will be too narrow or even difficult to form. However, W1 should not be too large either, otherwise the closed portion 31a will be too wide, thus affecting the energy density of the solid-state battery 10. As an example, W1 can be 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, or 20mm.

[0050] In this embodiment, the negative electrode 1 refers to an electrode containing lithium metal. The lithium metal in the negative electrode 1 can be elemental lithium metal or a lithium alloy. The morphology of the lithium metal in the negative electrode 1 is not limited here; the lithium metal can be in the form of strips, three-dimensional networks, or particles.

[0051] In this embodiment, the negative electrode 1 is not disposed inside the separator bag because the contact effect between the negative electrode 1 and the solid electrolyte layer 2 will affect the deposition effect of lithium metal on the negative electrode 1, thereby affecting the cycle performance of the solid battery 10.

[0052] In some embodiments, the negative electrode 1 is in direct contact with the solid electrolyte layer 2. Since the negative electrode 1 contains lithium metal, which is soft, when the negative electrode 1 and the solid electrolyte layer 2 are stacked, the lithium metal can adapt to the deformation of the surface of the solid electrolyte layer 2, thereby making the interface between the negative electrode 1 and the solid electrolyte layer 2 more consistent and improving the cycle performance of the solid battery 10.

[0053] In addition, it is difficult to set the separator bag outside the negative electrode 1, especially it is difficult to prepare the separator bag by hot pressing. This is because the lithium metal in the negative electrode 1 has a low melting point and is relatively soft. When the separator bag is prepared by hot pressing, the negative electrode 1 is prone to deformation or even melting, which reduces the uniformity of the surface morphology of the negative electrode 1 and thus affects the contact effect between the negative electrode 1 and the solid electrolyte layer 2.

[0054] In some implementations, please refer to Figure 4 The separator 311 includes a base film layer 3111 and a first adhesive layer 3112 and a second adhesive layer 3113 located on opposite sides of the base film layer 3111. The separator 311 is bonded to the positive electrode 32 via the first adhesive layer 3112, and to the solid electrolyte layer 2 via the second adhesive layer 3113. It can be seen that when the separator 311 is made into a separator bag 31, the first adhesive layer 3112 is located on the inner side of the separator bag 31, and the second adhesive layer 3113 is located on the outer side of the separator bag 31. Thus, the outer side of the separator bag 31 is bonded to the solid electrolyte layer 2, and the inner side of the separator bag 31 is bonded to the positive electrode 32. Experiments have shown that this arrangement can improve the deposition of lithium on the negative electrode 1 and reduce the risk of lithium plating.

[0055] In some embodiments, the material of the base film layer 3111 includes polyolefins. As an example, the base film layer 3111 is at least one of polyethylene (PE) film and polypropylene (PP) film. PE film and PP film have good chemical stability and mechanical properties.

[0056] In some embodiments, the material of the first adhesive layer 3112 includes at least one of polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR).

[0057] In some embodiments, the material of the second adhesive layer 3113 includes at least one of polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR).

[0058] It should be noted that the materials of the first adhesive layer 3112 and the second adhesive layer 3113 can be the same or different.

[0059] The thickness of the first adhesive layer 3112 is 2 μm to 10 μm. Within this range, the positive electrode 32 can be effectively bonded to the separator 311, and the first adhesive layer 3112 has little impact on lithium-ion transport. As an example, the thickness of the first adhesive layer 3112 is 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm.

[0060] The thickness of the second adhesive layer 3113 is 2 μm to 10 μm. Within this range, the solid electrolyte layer 2 can be effectively bonded to the separator 311, and the second adhesive layer 3113 has little impact on lithium-ion transport. As an example, the thickness of the first adhesive layer 3112 is 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm.

[0061] In some implementations, please refer to Figure 4 The positive electrode component 3 also includes a silicon dioxide layer 34, which is disposed on the second adhesive layer 3113.

[0062] In some implementations, please refer to Figure 4 The positive electrode 32 includes a positive current collector 321 and a positive active material layer 322 located on the positive current collector 321. The positive electrode assembly 3 also includes a positive electrode tab 33, one end of which extends into the separator bag 31 and is integrally formed with the positive current collector 321, while the other end of which is located outside the separator bag 31. By connecting the positive electrode tab 33 to the positive electrode 32 and by having the positive electrode tab 33 pass through the separator bag 31, charge transfer on the positive electrode 32 is achieved.

[0063] In some implementations, please refer to Figure 2 The length W2 of the portion of the positive electrode tab 33 located outside the separator bag 31 is 0.1mm to 20mm. As an example, W2 is 0.1mm, 0.5mm, 1mm, 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm or 20mm.

[0064] In some embodiments, the positive electrode tab 33 and the positive electrode current collector 321 are integrally formed. As an example, when preparing the positive electrode sheet 32, a blank area can be reserved on the metal foil. Except for the blank area, the positive electrode slurry is coated on the other areas of the metal foil. After the positive electrode slurry dries, the positive electrode active material layer 322 can be obtained. Then, the metal foil is die-cut so that the blank area of ​​the metal foil forms the positive electrode tab 33, and the other areas form the positive electrode current collector 321.

[0065] In some embodiments, positive electrode active material layers 322 are provided on both opposite sides of the positive electrode current collector 321. It is understood that the positive electrode active material layer 322 in the positive electrode sheet 32 ​​has at least two layers. This arrangement helps to reduce the thickness of the solid-state battery 10. Of course, in other embodiments, the positive electrode active material layer 322 may be provided only on one side of the positive electrode current collector 321.

[0066] In some embodiments, the positive electrode active material layer 322 includes a positive electrode active material. As an example, the positive electrode active material includes at least one of lithium cobalt oxide and lithium nickel cobalt manganese oxide.

[0067] In some embodiments, the positive electrode active material layer 322 further includes a conductive agent and a binder. As an example, the conductive agent includes at least one of conductive carbon black, carbon nanotubes (CNTs), mesoporous carbon materials, and vapor-grown carbon fibers (VGCF); the binder includes at least one of polyacrylic acid (PAA), polyvinylidene fluoride (PVDF), and polyvinyl alcohol (PVA).

[0068] In some embodiments, the solid electrolyte layer 2 includes a solid electrolyte. The solid electrolyte includes at least one of a polymer solid electrolyte, an oxide solid electrolyte, and a sulfide solid electrolyte. As an example, the solid electrolyte layer 2 includes an oxide solid electrolyte, which has good mechanical strength. This improves the strength of the solid electrolyte layer 2, allowing it to better block lithium dendrites formed on the negative electrode 1, reducing the probability of lithium dendrites reaching the positive electrode assembly 3, and thus reducing the risk of internal short circuits in the solid-state battery 10.

[0069] In some embodiments, the oxide solid electrolyte includes at least one of lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium tantalum oxide (LLZTO), lithium lanthanum zirconium aluminum oxide (LLAZO), lithium lanthanum zirconium gallium oxide (LLGZO), lithium lanthanum titanium oxide (LLTO), lithium aluminum germanium phosphate (LAGP), and lithium aluminum titanium phosphate (LATP).

[0070] In some implementations, in a single solid-state battery 10, the number of negative electrode plates 1 may be one or more, the number of solid electrolyte layers 2 may be one or more, and the number of positive electrode components 3 may be one or more. However, in any case, the solid electrolyte layer 2 is always kept between the negative electrode plates 1 and the positive electrode components 3.

[0071] In some embodiments, the number of negative electrode plates 1 in a single solid-state battery 10 is 1 to 100.

[0072] In some embodiments, the number of solid electrolyte layers 2 in a single solid-state battery 10 is 1 to 100.

[0073] In some embodiments, the number of positive electrode components 3 in a single solid-state battery 10 is 1 to 100.

[0074] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0075] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0076] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0077] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A solid-state battery, characterized in that, The battery includes a negative electrode, a solid electrolyte layer, and a positive electrode assembly stacked sequentially. The positive electrode assembly includes a separator bag and a positive electrode within the separator bag. The edge region of the separator bag is formed into a closed portion. With the plane where the negative electrode is located as a first plane, the solid electrolyte layer is projected along the thickness direction of the solid battery. The edge of the solid electrolyte layer in the orthogonal projection of the first plane is located within the orthogonal projection of the closed portion in the first plane.

2. The battery according to claim 1, characterized in that, The positive electrode assembly also includes a silicon dioxide layer that covers the outer surface of the closed-cell portion.

3. The battery according to claim 2, characterized in that, The silica layer comprises silica particles with an average particle size of 0.1 μm to 3 μm; and / or, the thickness of the silica layer is 1 μm to 10 μm.

4. The battery according to claim 1, characterized in that, The negative electrode is a lithium metal negative electrode.

5. The solid-state battery according to claim 1, characterized in that, Along the thickness direction of the solid-state battery, the orthogonal projection of the positive electrode sheet onto the first plane lies within the orthogonal projection of the negative electrode sheet onto the first plane; and / or, along the thickness direction of the solid-state battery, the orthogonal projection of the negative electrode sheet onto the first plane lies within the orthogonal projection of the solid electrolyte layer onto the first plane.

6. The solid-state battery according to claim 1, characterized in that, The separator bag includes separators located on opposite sides of the positive electrode sheet. The edge regions of the separators protrude from the edge of the positive electrode sheet and are heat-pressed together to form the closed-cell portion.

7. The solid-state battery according to claim 6, characterized in that, The edge region of the separator protrudes from the edge of the positive electrode sheet by a width of 2mm to 20mm.

8. The solid-state battery according to claim 6, characterized in that, The separator includes a base film layer and a first adhesive layer and a second adhesive layer located on opposite sides of the base film layer. The separator is bonded to the positive electrode sheet through the first adhesive layer and to the solid electrolyte layer through the second adhesive layer.

9. The solid-state battery according to claim 8, characterized in that, The first adhesive layer and the second adhesive layer each independently comprise at least one of polyvinylidene fluoride, polyacrylic acid, sodium carboxymethyl cellulose and styrene-butadiene rubber; and / or, the thickness of the first adhesive layer is 2 μm to 10 μm, and the thickness of the second adhesive layer is 2 μm to 10 μm.

10. The solid-state battery according to claim 1, characterized in that, The positive electrode includes a positive current collector and a positive active material layer on the positive current collector. The positive electrode assembly also includes a positive electrode tab, one end of which extends into the separator bag and is integrally formed with the positive current collector, and the other end of which is located outside the separator bag.

11. The solid-state battery according to claim 10, characterized in that, The length of the portion of the positive electrode tab located outside the separator bag is 0.1 mm to 20 mm; and / or, the positive electrode active material layer includes at least one of lithium cobalt oxide and lithium nickel cobalt manganese oxide.

12. The solid-state battery according to any one of claims 1 to 11, characterized in that, The solid-state battery includes at least one of all-solid-state batteries and semi-solid-state batteries.

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