Solid electrolyte membrane, method for preparing same, and all-solid rechargeable battery

Abstract

Disclosed are a solid electrolyte membrane, a method for preparing the same, and an all-solid-state rechargeable battery. The solid electrolyte membrane includes: a first layer including solid electrolyte particles; a second layer disposed on the first layer and including a composite; and a third layer disposed on the second layer and including solid electrolyte particles, and the composite includes: a core including diamagnetic particles; and a shell surrounding the core and including a solid electrolyte.

Description

Technical Field

[0001] The invention discloses a solid electrolyte membrane, its manufacturing method, and an all-solid-state rechargeable battery. Background Technology

[0002] In response to industrial demands, there has been active development of batteries with high energy density and safety. For example, lithium-ion batteries are being commercialized not only in information and communication equipment but also in the automotive sector.

[0003] However, because current lithium-ion batteries on the market use electrolyte solutions that include flammable organic dispersion media, overheating and fire problems can occur if a short circuit occurs inside the battery. Therefore, all-solid-state rechargeable batteries that use solid electrolytes instead of electrolyte solutions are being proposed. Summary of the Invention

[0004] According to some embodiments, a solid electrolyte membrane, a method for manufacturing the membrane, and an all-solid-state rechargeable battery including the membrane are provided, which can improve the ion conductivity and high-rate performance of an all-solid-state rechargeable battery while ensuring battery safety.

[0005] In some embodiments, the solid electrolyte membrane includes: a first layer comprising solid electrolyte particles; a second layer disposed on the first layer and comprising a composite; and a third layer disposed on the second layer and comprising solid electrolyte particles.

[0006] The complex comprises: a core including diamagnetic (diamagnetic) particles; and a shell surrounding the core and including a solid electrolyte.

[0007] In some embodiments, the method of manufacturing the solid electrolyte membrane includes: forming a first layer comprising solid electrolyte particles.

[0008] A second layer comprising the complex is formed on the first layer, and

[0009] A third layer, comprising solid electrolyte particles, is formed on top of the second layer.

[0010] The composite includes: a core comprising antimagnetic particles; and a shell surrounding the core and containing a solid electrolyte.

[0011] Some implementations provide an all-solid-state rechargeable battery comprising: a positive electrode layer; a negative electrode layer; and a solid electrolyte membrane between the positive electrode layer and the negative electrode layer.

[0012] Solid electrolyte membranes according to some embodiments and all-solid-state rechargeable batteries including them can improve ion conductivity and high-rate characteristics while ensuring battery safety. Attached Figure Description

[0013] Figure 1 This is a schematic cross-sectional view of compound 1 according to some embodiments.

[0014] Figure 2 This is a schematic diagram of a solid electrolyte membrane 300 according to some embodiments.

[0015] Figure 3 This is a schematic diagram of the movement path of lithium ions in the solid electrolyte membrane 300 excluding complex 1.

[0016] Figure 4 This is a schematic diagram of the movement path of lithium ions in the second layer 12 according to some embodiments.

[0017] Figure 5 This is a schematic perspective view of a solid electrolyte membrane 300 according to some embodiments.

[0018] Figure 6 This is a schematic cross-sectional view of the second layer 12 in a solid electrolyte membrane 300 according to some embodiments.

[0019] Figure 7 and 8 This is a schematic cross-sectional view of an all-solid-state rechargeable battery 100 according to some embodiments. Detailed Implementation

[0020] In the following description, embodiments will be detailed so that those skilled in the art can readily implement them. However, this disclosure may be embodied in many different forms and is not to be construed as limited to the exemplary embodiments set forth herein.

[0021] The terminology used herein is for descriptive purposes only and is not intended to limit the scope of this disclosure. Unless the context clearly specifies otherwise, singular expressions include plural expressions.

[0022] As used in this article, “combination of” means mixtures of constituent elements, stacks (stacks), complexes, copolymers, alloys, blends, reaction products, etc.

[0023] In this document, it should be understood that terms such as “comprising,” “including,” or “having” are intended to specify the presence of the features, quantities, steps, elements, or combinations thereof embodied, but do not preclude the possibility of the presence or addition of one or more other features, quantities, steps, elements, or combinations thereof.

[0024] In the accompanying drawings, for clarity, the thicknesses of layers, films, panels, regions, etc., are exaggerated, and the same reference numerals denote the same elements throughout the specification. It will be understood that when an element, such as a layer, film, region, or substrate, is referred to as being "on" another element, it may be directly on the other element, or there may be intermediate elements present. Conversely, when an element is referred to as being "directly on" another element, there are no intermediate elements present.

[0025] "Layer" includes not only the shape formed on the entire surface when viewed from a plan view, but also the shape formed on a portion of the surface.

[0026] "Particle size" or "average particle size" can be measured by methods known to those skilled in the art, such as by a particle size analyzer, or by transmission electron microscopy or scanning electron microscopy. Alternatively, the average particle size value can be obtained by measuring using a dynamic light scattering method, performing data analysis, counting the number of particles for each particle size range, and calculating therefrom. The average particle size can refer to the diameter (D) of particles having a cumulative volume of 50% in the particle size distribution. 50 ).

[0027] "Thickness" can be measured by taking a photograph with an optical microscope (such as a scanning electron microscope).

[0028] solid electrolyte membrane

[0029] In some embodiments, the solid electrolyte membrane includes: a first layer comprising solid electrolyte particles; a second layer disposed on the first layer and comprising a composite; and a third layer disposed on the second layer and comprising solid electrolyte particles, wherein the composite comprises: a core comprising antimagnetic particles; and a shell surrounding the core and comprising solid electrolyte.

[0030] Figure 1 This is a schematic diagram of the composite 1 included in the second layer 12 of a solid electrolyte membrane 300 according to some embodiments, and Figure 2 This is a schematic diagram of a solid electrolyte membrane 300 according to some embodiments. Additionally, Figure 3 This is a schematic diagram of the lithium ion migration path in the solid electrolyte membrane 300 excluding complex 1. Figure 4 This is a schematic diagram of the lithium ion movement path in the second layer 12 according to some embodiments. Figure 5 This is a schematic perspective view of a solid electrolyte membrane 300 according to some embodiments, and Figure 6 This is a schematic cross-sectional view of the second layer 12 in a solid electrolyte membrane 300 according to some embodiments. Figures 7 to 8 This is a schematic cross-sectional view of an all-solid-state rechargeable battery 100 according to some embodiments.

[0031] Compared to lithium-ion batteries, all-solid-state rechargeable batteries do not use flammable organic dispersion media and significantly reduce the likelihood of fire or explosion even in the event of a short circuit, thus greatly improving safety. On the other hand, solid electrolytes have the problem of lower lithium-ion conductivity than liquid electrolytes. To shorten the ion migration path in the electrode plates of all-solid-state rechargeable batteries, methods include forming holes or pores to fill with solid electrolyte or adding additives that increase lithium-ion conductivity. However, the method of forming holes or pores and filling the interior with solid electrolyte has limitations regarding the ability to fill the interior with solid electrolyte without any gaps. Adding additives that increase ion conductivity can also cause side reactions between the solid electrolyte and the additives or affect the properties of the slurry used to form the electrode layer, thus limiting the selection of additives.

[0032] To shorten the lithium-ion migration path in a solid electrolyte membrane (SEM), one approach involves using a composite in the SEM, comprising diamagnetic particles in a core and a solid electrolyte in a shell, wherein the solid electrolyte itself has a core-shell structure. However, because the composite with a core containing diamagnetic particles is electrically conductive, its use in a solid electrolyte membrane as is poses a risk of internal short circuits within the battery cells.

[0033] Therefore, some implementations provide a solid electrolyte membrane that can shorten the movement path of lithium ions while suppressing the possibility of internal short circuits in battery cells.

[0034] To improve ion conductivity and high-rate performance by shortening the lithium-ion migration path, the following methods are used: Figure 1 The composite 1 shown is used as a material for a solid electrolyte membrane. To shorten the lithium-ion migration path, composite 1 has a core-shell structure comprising a core 1a including antimagnetic particles and a shell 1b surrounding the core and including a solid electrolyte. Figure 4 As shown, lithium ions 4 can shorten their migration path through complex 1, thereby improving ion conductivity and high-rate performance. In contrast, as... Figure 3 As shown, when complex 1 is not included in the solid electrolyte membrane 300, with Figure 4 In comparison, lithium ions have a longer migration path, resulting in lower ionic conductivity.

[0035] When using compound 1, it is necessary to reduce the risk of internal short circuits in the battery cells that may occur due to the inclusion of antimagnetic particles as the core 1a. For this purpose, such as... Figure 2As shown, a first layer 11 containing solid electrolyte particles and a third layer 13 containing solid electrolyte particles are stacked on the upper and lower layers of the second layer 12, respectively, such that the layer containing the complex 1 can be disposed in the middle, and thus the solid electrolyte membrane 300 can be designed as a three-layer membrane.

[0036] According to some embodiments, in order to further improve the ion conductivity and high-rate performance of the all-solid-state rechargeable battery, the composite 1 itself may be designed to be non-spherical within the second layer 12 of the solid electrolyte membrane. Alternatively, the composite 1 may be non-spherical within the second layer 12, and simultaneously, the composite may be oriented in a direction perpendicular to or nearly perpendicular to the plane direction of the solid electrolyte membrane.

[0037] However, in the conventional method of forming a solid electrolyte membrane by coating a slurry including the aforementioned non-spherical composite onto a substrate, the non-spherical composite 1 is randomly distributed in the second layer 12. Therefore, in order to orient the non-spherical composite 1 in the second layer 12 in a direction perpendicular or nearly perpendicular to the planar direction of the solid electrolyte membrane 300, a method of applying a magnetic field after coating the slurry including the non-spherical composite onto the substrate can be considered.

[0038] In this paper, the orientation of the non-spherical complex is controlled by a magnetic field because the non-spherical complex possesses diamagnetic properties. Since none of the known solid electrolytes possess diamagnetic properties, in some embodiments, such as... Figure 1 As shown, a composite 1 with a core 1a including non-spherical antimagnetic particles is used, and thus the orientation of the composite 1 within the solid electrolyte membrane 300 can be controlled. For example, by oriented the composite 1 in the second layer 12 in a direction perpendicular or nearly perpendicular to the plane of the solid electrolyte membrane 300, the movement path of lithium ions within the solid electrolyte membrane can be shortened and the interfacial contact resistance between the solid electrolytes can be reduced. Therefore, the all-solid-state rechargeable battery 100 including the solid electrolyte membrane 300 according to some embodiments can have improved ion conductivity and high-rate performance.

[0039] The elements constituting the solid electrolyte membrane 300 according to some embodiments will be described in more detail below.

[0040] complex

[0041] Complex 1 has a core 1a-shell 1b structure, and as Figure 1 As shown, composite 1 includes: a core 1a comprising antimagnetic particles; and a shell 1b surrounding the core 1a and comprising a solid electrolyte.

[0042] According to some embodiments, in composite 1, the core 1a (or the diamagnetic particles included in the core) may be non-spherical. For example, composite 1 may have an aspect ratio greater than 1 as expressed by Equation 1.

[0043] [Equation 1]

[0044] Aspect ratio = Major axis length / Minor axis length

[0045] Such non-spherical diamagnetic particles and the composite 1 comprising them can be oriented in a direction perpendicular to or nearly perpendicular to the plane direction of the solid electrolyte membrane (e.g., at 50° to 130° relative to the plane direction of the solid electrolyte membrane 300) by a magnetic field applied from the outside. In this document, the plane direction X of the solid electrolyte membrane 300 refers to a direction parallel to the surface of the wide side of the solid electrolyte membrane. Figure 5 A perspective view of the solid electrolyte membrane 300 and its planar direction X are shown. Additionally, Figure 6 A cross-sectional view of the second layer 12 included in the solid electrolyte membrane 300 is shown, and the planar direction X of the solid electrolyte membrane 300 and the direction Y perpendicular to the planar direction X are shown as lines, respectively.

[0046] According to some embodiments, the performance of an all-solid-state rechargeable battery, including a solid electrolyte membrane, can be improved as the aspect ratio expressed by Equation 1 increases. For example, the aspect ratio expressed by Equation 1 can be greater than or equal to 1.1, greater than or equal to 1.2, greater than or equal to 1.3, greater than or equal to 1.5, greater than or equal to 2, or greater than or equal to 3. There is no particular upper limit to the aspect ratio expressed by Equation 1, but considering the convenience and cost savings in the manufacturing process, it can be in the range of less than or equal to 5,000, less than or equal to 300, less than or equal to 100, less than or equal to 50, less than or equal to 20, or less than or equal to 10. For example, the aspect ratio of core 1a can be from 1.1 to 20 or from 1.5 to 10.

[0047] According to some embodiments, the major axis length of composite 1 can be from 1 μm to 50 μm, or the minor axis length of composite 1 can be from 0.01 μm to 5 μm. Alternatively, the aspect ratio of composite 1, expressed by Equation 1, which is the ratio of the major axis length to the minor axis length, can be greater than 1. In this document, the major axis length and minor axis length of the composite refer to their average values.

[0048] According to some embodiments, in composite 1, shell 1b may be formed to have a uniform thickness or may be formed to be non-uniform.

[0049] According to some embodiments, composite 1 may satisfy one or more of equations 2 and 3. In other words, it may satisfy either equation 2 or equation 3, or both equation 2 and 3. Within the above scope, the orientation effect of the core 1a and the lithium-ion conduction effect of the shell 1b of composite 1 can be coordinated (harmonized). In this document, in equations 2 and 3, the units of the numerator and denominator only need to match each other, so that the units of A1, A2, and B are not particularly limited.

[0050] [Equation 2]

[0051] 0.1 ≤ A1 / B ≤ 100

[0052] [Equation 3]

[0053] 0.01 ≤ A2 / B ≤ 10

[0054] In equations 2 and 3, A1 represents the length of the major axis of core 1a, A2 represents the length of the minor axis of core 1a, and B represents the thickness of shell 1b.

[0055] According to some embodiments, the major axis length of core 1a can be from 1 μm to 50 μm, 1 μm to 20 μm, 2 μm to 15 μm, or 3 μm to 12 μm. Alternatively, the minor axis length of core 1a can be from 10 nm to 5 μm, 100 nm to 5 μm, or 1 μm to 4 μm. Alternatively, the thickness of shell 1b can be from 100 nm to 10 μm, 100 nm to 5 μm, or 300 nm to 3 μm. Within this range, the orientation effect through core 1a and the lithium-ion conduction effect through shell 1c can be coordinated. In this document, the major axis length of core 1a, the minor axis length of core 1a, and the thickness of shell 1b refer to average values. Methods for measuring the major axis length of core 1a, the minor axis length of core 1a, and the thickness of shell 1b may include, for example, cutting a solid electrolyte membrane 500 to obtain a cross-sectional sample, such as... Figure 6 As shown, and its image was captured using a scanning electron microscope (SEM) to detect the composite 1 in the second layer 12 of the solid electrolyte membrane 300. In other words, the long axis length of the core 1a, the short axis length of the core 1a, and the thickness of the shell 1b can be obtained by measuring any ten composites 1 in a cross-sectional sample and calculating their respective average values.

[0056] Alternatively, in composite 1, the weight ratio of core 1a to shell 1b can be 1:1 to 1:500, 1:2 to 1:100, or 1:10 to 1:50. Within this range, the orientation effect through core 1a and the lithium-ion conduction effect through shell 1b can be coordinated.

[0057] According to some embodiments, the major axis of the composite 1 in the solid electrolyte membrane 300 can be oriented in a direction Y perpendicular to or nearly perpendicular to the planar direction X of the solid electrolyte membrane 300. For example... Figure 6 As shown, the orientation angle between the long axis of the composite 1 and the plane direction X of the solid electrolyte membrane 300 can be obtained by measuring the angle between the long axis of the composite 1 (represented by the line) and the plane direction X of the solid electrolyte membrane (or the second layer 12) by referring to the cross-section of the solid electrolyte membrane 300 (or the second layer 12).

[0058] For example, the long axis of the composite 1 in the solid electrolyte membrane 300 can be oriented at an angle ranging from 50° to 130°, 70° to 110°, or 85° to 95° relative to the planar direction X of the solid electrolyte membrane 300, or at a substantially perpendicular angle of 90° (which is the direction Y). Within these ranges, the lithium-ion migration path in the solid electrolyte membrane can be effectively shortened, and the interfacial contact resistance between the solid electrolytes can be reduced.

[0059] In composite 1, the diamagnetic particles of core 1a can have any non-spherical shape with an aspect ratio greater than 1, as expressed by Equation 1, without particular limitation. For example, core 1a may include diamagnetic particles having a needle shape, a plate shape (sheet shape), or an elliptical shape. Alternatively, core 1a may include carbon-based materials selected from artificial graphite, natural graphite, graphene, carbon nanotubes (CNTs), carbon fibers, carbon black, or combinations thereof as diamagnetic particles. In this document, carbon nanotubes (CNTs) may be S-carbon nanotubes (short-length CNTs) or L-carbon nanotubes (long-length CNTs).

[0060] According to some embodiments, shell 1b may include solid electrolytes commonly known in the art. For example, shell 1b may include a solid electrolyte selected from sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, or combinations thereof. As a representative example, the solid electrolyte included in shell 1b may include a sulfide solid electrolyte, and shell 1b of composite 1 may include Li6PS5Cl (a type of silver-germanium sulfide solid electrolyte). In this document, the description of the solid electrolyte particles in the first layer 11, the second layer 12, and the third layer 13 can be applied in the same manner as the solid electrolytes available in shell 1b.

[0061] Based on the total weight of the second layer 12, the content of complex 1 can be from 0.1 wt% to 50 wt%, 0.5 wt% to 40 wt%, 1 wt% to 30 wt%, or 5 wt% to 25 wt%. Within this range, the effect of complex 1 in improving ionic conductivity and high-rate characteristics can be further enhanced.

[0062] To reduce the possibility of internal short circuits in individual battery cells, such as Figure 2 As shown, a solid electrolyte membrane 300 according to some embodiments includes: a first layer 11 comprising solid electrolyte particles 2; a second layer 12 disposed on the first layer 11 and comprising a composite 1; and a third layer 13 disposed on the second layer 12 and comprising solid electrolyte particles 2. In this way, the three layers are designed to include a composite 1 having a core (which includes antimagnetic particles capable of electrical conductivity) in the second layer 12 (intermediate layer), resulting in ensuring the safety of the single cell.

[0063] First and third floors

[0064] The first layer 11 and the third layer 13 include solid electrolyte particles 2. The first layer 11 and the third layer 13 include solid electrolyte particles 2 to ensure the ionic conductivity of the solid electrolyte membrane, wherein, unlike the second layer 12, the first layer 11 and the third layer 13 do not include the complex 1, and thus can suppress internal short circuits caused by the complex 1 included in the second layer 12.

[0065] The solid electrolyte particles 2 included in the first layer 11 and the third layer 13 may include solid electrolytes commonly known in the art, for example, selected from the following solid electrolytes: sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes or combinations thereof.

[0066] The solid electrolyte particles 2 included in the first layer 11 and the third layer 13 are described in detail below.

[0067] Sulfide solid electrolytes

[0068] For example, sulfide solid electrolytes may include Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element, such as I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, and Li2S-P2S5-Z. m S n (m and n are integers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are integers, and M is P, Si, Ge, B, Al, Ga, or In) or a combination thereof.

[0069] Alternatively, sulfide-based solid electrolytes can be obtained, for example, by mixing Li₂S and P₂S₅ in a molar ratio of 50:50 to 90:10 or 50:50 to 80:20, and optionally subjecting the mixture to heat treatment. Within the above mixing ratio range, sulfide-based solid electrolytes with excellent ionic conductivity can be prepared. Ionic conductivity can be further improved by adding SiS₂, GeS₂, B₂S₃, etc., as other components.

[0070] Mechanical grinding or solution methods can be used as mixing methods for sulfur-containing raw materials used in the preparation of sulfide-based solid electrolytes. Mechanical grinding is a method of mixing starting materials into fine particles by placing them in a ball mill reactor and vigorously stirring them. Solution methods can be carried out by mixing the starting materials in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, when heat treatment is performed after mixing, the crystals of the solid electrolyte can be more robust, and the ionic conductivity can be improved. For example, sulfide-based solid electrolytes can be prepared by mixing sulfur-containing raw materials and performing heat treatment two or more times. In this case, sulfide-based solid electrolytes with high ionic conductivity and robustness can be prepared.

[0071] According to some embodiments, sulfide-based solid electrolyte particles can be prepared, for example, by a first heat treatment of mixing sulfur-containing raw materials and firing them at 120°C to 350°C, followed by a second heat treatment of mixing the results of the first heat treatment and firing them at 350°C to 800°C. The first and second heat treatments can be carried out in an inert gas or nitrogen atmosphere, respectively. The first heat treatment can last from 1 hour to 10 hours, and the second heat treatment can last from 5 hours to 20 hours. Small raw materials can be ground during the first heat treatment, and the final solid electrolyte can be synthesized during the second heat treatment. Through two or more such heat treatments, sulfide-based solid electrolytes with high ionic conductivity and high performance can be obtained, and such solid electrolytes are suitable for large-scale production. The temperature of the first heat treatment can be, for example, from 150°C to 330°C or from 200°C to 300°C, and the temperature of the second heat treatment can be, for example, from 380°C to 700°C or from 400°C to 600°C.

[0072] For example, sulfide-based solid electrolyte particles may include argillium-germanium sulfides. Arillium-germanium sulfide-based solid electrolyte particles may have a content close to 10. -4 Up to 10 -2A high ionic conductivity in the range of S / cm, which is the ionic conductivity of a typical liquid electrolyte at room temperature, and can form a tight bond (bonding) between the positive electrode active material and the solid electrolyte without causing a decrease in ionic conductivity, and in addition, can form a tight interface between the electrode layer and the solid electrolyte membrane. A all-solid-state rechargeable battery including the same can have improved battery performance such as rate performance, Coulomb efficiency, and cycle life characteristics.

[0073] The argyrodite-type sulfide solid electrolyte particles may include, for example, a compound represented by Chemical Formula 11.

[0074] [Chemical Formula 11]

[0075] (Li a M 1 b M 2 c )(P d M 3 e )(S f M 4 g )X h

[0076] In Chemical Formula 11, 4 ≤ a ≤ 8, M 1 is Mg, Cu, Ag, or a combination thereof, 0 ≤ b < 0.5, M 2 is Na, K, or a combination thereof, 0 ≤ c < 0.5, M 3 is Sn, Zn, Si, Sb, Ge, or a combination thereof, 0 < d < 4, 0 ≤ e < 1, M 4 is O, SO n or a combination thereof, 1.5 ≤ n ≤ 5, 3 ≤ f ≤ 12, 0 ≤ g < 2, X is F, Cl, Br, I, or a combination thereof, and 0 ≤ h ≤ 2.

[0077] For example, in Chemical Formula 11, a halogen element (X) may be necessarily included, and in this case, it may be expressed as 0 < h ≤ 2. For example, an M 1 element may be necessarily included in Chemical Formula 11, and in this case, it may be expressed as 0 < b < 0.5. In Chemical Formula 11, M 3 can be understood as an element substituting for P and can be 0 < e < 1. In Chemical Formula 11, M 4 substitutes for S and can be, for example, 0 < g < 2, and the ratio f of S can be, for example, 3 ≤ f ≤ 7. If M 4 is SO n , then SO n can be, for example, S4O6, S3O6, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, SO4, or SO5, for example, SO4.

[0078] For example, in chemical formula 11, a+b+c+h=7, d+e=1, and f+g+h=6.

[0079] As specific examples, sulfide solid electrolyte particles of the silver-germanium sulfide type may include Li3PS4 and Li7P3S. 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 Li 6.2 PS 5.2 Br 0.8 Li 5.75 PS 4.75 Cl 1.25 、(Li 5.69 Cu 0.06 PS 4.75 Cl 1.25 、(Li 5.72 Cu 0.03 PS 4.75 Cl 1.25 、(Li 5.69 Cu 0.06 )P(S 4.70 (SO4) 0.05 )Cl 1.25 、(Li 5.69 Cu 0.06 )P(S 4.60 (SO4) 0.15 )Cl 1.25 、(Li 5.72 Cu 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 、(Li 5.72 Na 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 Li 5.75 P(S 4.725 (SO4) 0.025 )Cl 1.25 Or combinations thereof, but not limited to these.

[0080] A sulfide solid electrolyte of the sulfide type can be prepared, for example, by mixing lithium sulfide and phosphorus sulfide, and optionally lithium halide. Heat treatment can be performed after mixing. The heat treatment may include, for example, two or more heat treatment processes. Methods for preparing the sulfide solid electrolyte may include, for example, a first heat treatment in which the raw materials are mixed and fired at 120°C to 350°C, and a second heat treatment in which the result of the first heat treatment is mixed again and fired at 350°C to 800°C.

[0081] The average particle size (D) of sulfide solid electrolyte particles 50 For example, the particle size can be from 0.1 μm to 5.0 μm or from 0.1 μm to 3.0 μm, and can be small particles from 0.1 μm to 1.9 μm or large particles from 2.0 μm to 5.0 μm. Alternatively, sulfide-based solid electrolyte particles can be a mixture of small particles having an average particle size of 0.1 μm to 1.9 μm and large particles having an average particle size of 2.0 μm to 5.0 μm. The average particle size of the sulfide-based solid electrolyte particles can be measured using electron microscopy images, and, for example, the particle size distribution can be obtained by measuring the size (diameter or major axis length) of about 20 particles in a scanning electron microscope image, and D can be calculated from it. 50 .

[0082] Oxide solid electrolytes

[0083] Oxide solid electrolytes may include, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP) (0≤x≤4), Li 1+x+ y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2,0≤y<3)、BaTiO3、Pb(Zr,Ti)O3(PZT)、Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1,0≤y<1), PB(Mg3Nb 2 / 3 O3-PbTiO3 (PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Lithium phosphate (Li3PO4), Lithium titanium phosphate (Li x Ti y(PO4)3, where 0 < x < 2 and 0 < y < 3, Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0 ≤ x ≤ 1, 0 ≤ y ≤ 1), lithium lanthanum titanate (Li x La y TiO3, where 0 < x < 2 and 0 < y < 3), Li2O, LiAlO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2 - based ceramics, garnet - based ceramics Li 3+x La3M2O 12 (where M = Te, Nb or Zr; x is an integer from 1 to 10) or a mixture thereof.

[0084] Halogenated solid electrolytes

[0085] The solid electrolyte film may include, for example, a halide - based solid electrolyte. The halide - based solid electrolyte contains a halogen element as a main component, meaning that the ratio of the halogen element to all the elements constituting the solid electrolyte may be greater than or equal to 50 mol%, greater than or equal to 7 mol%, greater than or equal to 90 mol% or 100 mol%. For example, the halide - based solid electrolyte may not contain a sulfur element.

[0086] The halide - based solid electrolyte may contain a lithium element, a metal element other than lithium, and a halogen element. The metal element other than lithium may be Al, As, B, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hf, In, Mg, Mn, Ni, Sb, Sc, Sn, Ta, Ti, Y, Zn, Zr or a combination thereof. The halogen element may be F, Cl, Br, I or a combination thereof, and for example, may be Cl, Br or a combination thereof. The halide - based solid electrolyte may be represented, for example, by Li a M1X6 (where M is Al, As, B, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hf, In, Mg, Mn, Ni, Sb, Sc, Sn, Ta, Ti, Y, Zn, Zr or a combination thereof, and X is F, Cl, Br, I or a combination thereof, and 2 ≤ a ≤ 3). The halide - based solid electrolyte may include, for example, Li2ZrCl6, Li 2.7 Y 0.7 Zr 0.3 Cl6, Li 2.5 Y 0.5 Zr 0.5 Cl6, Li 2.5 In 0.5 Zr 0.5 Cl6, Li2In 0.5 Zr0.5 Cl6, Li3YBr6, Li3YCl6, Li3YBr2Cl4, Li3YbCl6, Li 2.6 Hf 0.4 Yb 0.6 Cl6 or combinations thereof, but not limited to these.

[0087] According to some embodiments, the solid electrolyte particles included in the first layer 11 and the third layer 13 may be the same as or different from each other. Alternatively, the solid electrolyte particles 2 included in the first layer 11 and the third layer 13 may be the same as or different from the solid electrolyte included in the shell 1b of the composite 1. For example, the shell 1b of the composite 1 may be made of Li6PS5Cl, and the solid electrolyte particles included in the first layer 11 and the third layer 13 may be made of Li6PS5Cl.

[0088] According to some embodiments, in addition to the solid electrolyte particles described above, the first layer 11 and the third layer 13 may each independently further include a binder as an optional component, and / or may further include other components such as alkali metal salts, ionic liquids, and conductive polymers. The components that may be additionally included in the first layer 11 and the third layer 13 are described in detail below.

[0089] adhesive

[0090] The first layer 11 and the third layer 13 may further include an adhesive. The adhesive is used to adhere the solid electrolyte particles 2 within the first layer 11 and / or the third layer 13 to each other. Such an adhesive may include, for example, nitrile rubber, hydrogenated nitrile rubber, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, natural rubber, polydimethylsiloxane, polyethylene oxide, polyvinylpyrrolidone, polyvinylpyridine, chlorosulfonated polyethylene, polyvinyl alcohol, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, polyamide-imide, polyimide, acrylic resin, poly(meth)acrylate, polyacrylonitrile, polystyrene, polyurethane, copolymers thereof, or combinations thereof.

[0091] Based on the total weight of the first layer 11 and the third layer 13, the binder may be included in an amount from 0.1 wt% to 3 wt%, for example, from 0.5 wt% to 2 wt% or from 0.5 wt% to 1.5 wt%. Within this range, the components in the solid electrolyte membrane can be well combined without reducing the ionic conductivity of the solid electrolyte, thereby improving the durability and reliability of the battery.

[0092] Other components

[0093] The first layer 11 and the third layer 13 may each further include one or more other components selected from alkali metal salts, ionic liquids and conductive polymers as optional components.

[0094] For example, the alkali metal salt can be a lithium salt. The lithium salt content in the solid electrolyte layer can be greater than or equal to 1 M, for example, from 1 M to 4 M. In this case, the lithium salt can improve ionic conductivity by improving the lithium ion mobility in the solid electrolyte layer. The lithium salt can be used without type limitations and can include, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiSCN, LiN(CN)2, lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, or combinations thereof.

[0095] For example, lithium salts can be imide lithium salts such as LiTFSI, LiFSI, LiBETI, or combinations thereof. Imide lithium salts can maintain or improve ionic conductivity by maintaining appropriate chemical reactivity with ionic liquids.

[0096] Ionic liquids have melting points below room temperature, so they are liquid at room temperature, and refer to salts composed only of ions or molten salts at room temperature.

[0097] Ionic liquids may be compounds including: a) at least one cation selected from: ammonium-based, pyrrolidine-based pyridine-based pyrimidine-based Based on imidazole Piperidine-based pyrazole-based Based on azole Based on pyridazine Based on Sulfonium-based, triazole-based a) and mixtures thereof, and b) at least one anion selected from the following: BF4 - PF6 - AsF6 - SbF6 - AlCl4 - HSO4 - ClO4 - CH3SO3- CF3CO2 - Cl - ,Br - I - BF4 - SO4 - CF3SO3 - (FSO2)2N - (C2F5SO2)2N - (C2F5SO2)(CF3SO2)N - and (CF3SO2)2N - .

[0098] The ionic liquid may be, for example, one or more selected from the following: bis(trifluoromethanesulfonyl)imide N-methyl-N-propylpyrrolidine bis(3-trifluoromethanesulfonyl)imine N-butyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)amine 1-butyl-3-methylimidazolium and bis(trifluoromethanesulfonyl)amine 1-ethyl-3-methylimidazole .

[0099] The first layer 11 and the third layer 13 may each have a weight ratio of solid electrolyte particles to ionic liquid of 0.1:99.9 to 90:10, for example 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. If these ranges are met, the electrochemical contact area with the electrode is improved, and the ionic conductivity can be maintained or improved. Therefore, the energy density, discharge capacity, rate characteristics, etc., of the all-solid-state rechargeable battery can be improved.

[0100] According to some embodiments, the average thickness of the first layer 11 may be the same as or different from the average thickness of the third layer 13. For example, the average thickness of the first layer 11 and the third layer 13 may be 10 μm to 200 μm, such as 10 μm to 150 μm, 10 μm to 100 μm, 10 μm to 60 μm, 10 μm to 50 μm, 10 μm to 34 μm, or 13 μm to 34 μm, 15 μm to 34 μm, or 20 μm to 34 μm.

[0101] Second floor

[0102] like Figure 2As shown, the second layer 12 is located between the first layer 11 and the third layer 13, and the second layer 12 includes the composite 1 described above. By placing the composite 1 on the second layer 12, which serves as an intermediate layer, internal short circuits in the battery cells can be suppressed, and battery safety can be ensured. According to some embodiments, in addition to the aforementioned composite 1 described above, the second layer 12 may further include solid electrolyte particles 2.

[0103] For the solid electrolyte particles that may be included in the second layer 12, the same description as that for the solid electrolyte in the shell 1b of the aforementioned composite 1 and the solid electrolyte particles in the first layer 11 and the third layer 13 may be applied.

[0104] As some embodiments, the solid electrolyte particles 2 included in the second layer 12 may be the same as or different from the solid electrolyte included in the shell 1b of the composite 1 and the solid electrolyte particles included in one or more of the first layer 11 and the third layer 13.

[0105] For example, the shell 1b of composite 1 may be made of Li6PS5Cl, and the solid electrolyte particles included in the second layer 12 may be made of Li6PS5Cl. Alternatively, the solid electrolyte particles included in the first layer 11 and the third layer 13 may be made of Li6PS5Cl, and the solid electrolyte particles included in the second layer 12 may be made of Li6PS5Cl.

[0106] Alternatively, the second layer 12 may further include the aforementioned adhesive as an optional component, and / or may further include other components such as alkali metal salts, ionic liquids, and conductive polymers. In this document, the description above regarding the first layer 11 and the third layer 13 also applies to the adhesive and other components.

[0107] According to some embodiments, based on the total weight of the second layer 12, the content of the binder included in the second layer 12 can be from 0.1 wt% to 3 wt%, for example, from 0.5 wt% to 2 wt% or from 0.5 wt% to 1.5 wt%. Within this range, the components in the second layer 12 can be well combined without reducing the ionic conductivity of the solid electrolyte, and thus the durability and reliability of the battery can be improved.

[0108] According to some embodiments, based on the total weight of the second layer 12, the content of solid electrolyte particles 2 included in the second layer 12 (i.e., excluding solid electrolytes included in the shell 1b of the composite 1) can be 50% to 99.9% by weight, for example 60% to 99.9% by weight, 65% to 99.5% by weight, 70% to 98% by weight, or 75% to 97% by weight.

[0109] According to some embodiments, the average thickness of the second layer 12 may be the same as or different from the average thickness of one or more of the first layer 11 and the third layer 13. For example, the average thickness of the second layer 12 may be greater than the average thickness of each of the first layer 11 and the third layer 13. For example, the average thickness of the second layer 12 may be in the range of 1.2 to 5 times, 1.3 to 4.8 times, 1.5 to 4.5 times, or 1.8 to 4.5 times the average thickness of each of the first layer 11 and the third layer 13. Alternatively, the average thickness of the second layer 12 may be 10 μm to 200 μm, for example 10 μm to 150 μm, 10 μm to 100 μm, 20 μm to 100 μm, 35 μm to 100 μm, 40 μm to 100 μm, 40 μm to 90 μm, or 50 μm to 80 μm. Within this range, the ionic conductivity due to the complex 1 included in the second layer 12 can be effectively ensured.

[0110] According to some embodiments, the average thickness of the first layer 11 and the third layer 13 can be from 10 μm to 34 μm, respectively, and the average thickness of the second layer 12 can be from 35 μm to 100 μm.

[0111] Manufacturing method of solid electrolyte membrane

[0112] Some embodiments provide a method for manufacturing the solid electrolyte membrane, comprising: forming a first layer comprising solid electrolyte particles, forming a second layer comprising a composite on the first layer, and forming a third layer comprising solid electrolyte particles on the second layer, wherein the composite comprises: a core comprising antimagnetic particles; and a shell surrounding the core and comprising solid electrolyte.

[0113] The foregoing description relates to a method for manufacturing a solid electrolyte membrane according to some embodiments, and in the following, descriptions that are repeated in the description of the solid electrolyte membrane 300 will be omitted, but the process for manufacturing a solid electrolyte membrane according to some embodiments will be further described.

[0114] The formation of the second layer 12 may include: manufacturing the composite 1, preparing a slurry comprising the composite for forming the second layer 12, and applying the slurry for forming the second layer 12 onto the first layer 11. In addition to the composite 1, the slurry for forming the second layer 12 may further include solid electrolyte particles 2, wherein the description of the solid electrolyte particles that may be included in the slurry for forming the second layer 12 is equally applicable herein and will not be repeated.

[0115] The slurry used to form the second layer 12 can be prepared by mixing the composite 1 and the second solvent. The second solvent is not particularly limited, but may include any generally known solvent capable of dispersing the composite 1. As a representative example, the second solvent may include octyl acetate, isobutyl isobutyrate, xylene, toluene, benzene, hexane, or combinations thereof.

[0116] Alternatively, the slurry used to form the second layer 12 may further include one or more components selected from the solid electrolyte particles 2, binders, alkali metal salts, ionic liquids, and conductive polymers previously mentioned as components that may be included in the second layer 12. Additionally, dispersants commonly known in the art (e.g., H-NBR, etc.) may be further added.

[0117] The aforementioned slurry for forming the second layer 12 can be applied onto the first layer 11, and at this time, any method commonly known in the art can be used as the application method without limitation. For example, methods such as bar coating, spin coating, die coating, transfer coating, and spray coating can be used.

[0118] After applying the slurry used to form the aforementioned second layer, the process may further include drying the applied slurry. For example, drying may be performed in a convection oven, and the drying temperature may be 30°C to 100°C, 35°C to 95°C, 40°C to 90°C, 45°C to 80°C, 48°C to 75°C, or 50°C to 70°C. Alternatively, drying may be performed for 10 seconds to 20 minutes, 30 seconds to 15 minutes, 1 minute to 10 minutes, or 2 minutes to 8 minutes.

[0119] According to some embodiments, the method may further include applying a magnetic field to the slurry applied to either the first layer 11 or the third layer 13 for forming the second layer 12. If this is satisfied, the composite 1, which has been randomly distributed in the second layer 12, may have an orientation in a direction Y that is perpendicular to or nearly perpendicular to the planar direction X of the solid electrolyte membrane 300.

[0120] For example, the magnetic field strength can be from 0.1 T (Tesla) to 3 T or from 0.5 T to 2 T. Alternatively, the application time of the magnetic field can be from 0.1 seconds to 10 minutes, 30 seconds to 8 minutes, or 1 minute to 5 minutes. There is no particular limitation on the temperature at which the magnetic field is applied, but the higher the temperature, the weaker the magnetic field strength can be. The strength and application time of the magnetic field can be appropriately controlled to effectively ensure the orientation of composite 1 in the second layer 12.

[0121] After applying a magnetic field, the slurry used to form the second layer 12 can be further dried. Drying allows the second layer 12 to be formed on either the first layer 11 or the third layer 13. For example, drying can be carried out in a convection oven at temperatures ranging from 30°C to 100°C, 35°C to 95°C, 40°C to 90°C, 45°C to 80°C, 48°C to 75°C, or 50°C to 70°C. Alternatively, drying can be carried out for 10 seconds to 20 minutes, 30 seconds to 15 minutes, 1 minute to 10 minutes, or 2 minutes to 8 minutes. Within these ranges, proper orientation of the composite 1 within the second layer 12 can be effectively ensured.

[0122] Alternatively, after drying the slurry for forming the second layer 12 with the magnetic field applied to it to form the second layer 12 on the first layer 11, the second layer 12 may be further compressed, wherein drying, compression, etc., may be carried out under conditions generally known in the art.

[0123] Alternatively, it may further include removing the substrate when necessary after the magnetic field has been applied.

[0124] According to some embodiments, composite 1 can be manufactured by: preparing a mixed solution comprising antimagnetic particles, solid electrolyte particles and a first solvent, drying the mixed solution, and heat-treating the dried product.

[0125] According to some embodiments, when preparing composite 1, the addition ratio of antimagnetic particles to solid electrolyte particles can be 1:1 to 1:500, 1:2 to 1:100, or 1:10 to 1:50.

[0126] There are no particular restrictions on the first solvent, as any commonly known solvent can be used, provided it can disperse both the diamagnetic particles and the solid electrolyte particles. However, acetonitrile can be used as a representative example.

[0127] For example, the drying of the applied slurry for forming the first layer can be performed at 80°C to 150°C, 90°C to 140°C, or 100°C to 130°C. Alternatively, heat treatment can be performed at 200°C to 600°C, 250°C to 550°C, 300°C to 500°C, or 350°C to 450°C. Within this range, a composite 1 in which the orientation effect of the core 1a and the lithium-ion conduction effect of the shell 1b can be effectively manufactured.

[0128] The first layer 11 can be formed by preparing a slurry comprising solid electrolyte particles and a solvent for forming the first layer 11, and then coating it onto a substrate or an already formed second layer 12. In this document, any commonly known solvent may be used, provided it can disperse the solid electrolyte particles 2, and therefore there are no particular limitations; octyl acetate is used as a representative example. As for the method of coating the slurry for forming the second layer, any method commonly known in the art may be used without limitation. For example, methods such as bar coating, spin coating, die coating, transfer coating, and spray coating may be used.

[0129] After applying the slurry for forming the first layer, the applied slurry for forming the second layer can be dried to form the first layer. Herein, drying can be carried out in a convection oven, and the drying temperature can be 30°C to 100°C, or 35°C to 95°C, 40°C to 90°C, 45°C to 80°C, 48°C to 75°C, or 50°C to 70°C. Alternatively, drying can be carried out for 10 seconds to 20 minutes, 30 seconds to 15 minutes, 1 minute to 10 minutes, or 2 minutes to 8 minutes. Within this range, proper orientation of the composite 1 within the second layer 12 can be effectively ensured.

[0130] Alternatively, after drying the slurry used to form the first layer, the first layer may be further rolled (rolled) if necessary. In this document, the rolling conditions may follow those generally known in the art.

[0131] Alternatively, if a substrate is used in the formation of the first layer, the substrate may be removed if necessary.

[0132] Alternatively, the slurry used to form the first layer 11 may further include one or more components selected from binders, alkali metal salts, ionic liquids, and conductive polymers previously mentioned as components that may be included in the second layer 12. Alternatively, dispersants commonly known in the art (e.g., H-NBR, etc.) may be added.

[0133] The third layer 13 can be formed by preparing a slurry comprising solid electrolyte particles and a solvent for forming the third layer 13, and then coating it onto a substrate or the already formed second layer 12. In this document, the solvent is not particularly limited, as any commonly known solvent can be used, provided it can disperse the solid electrolyte particles 2, and octyl acetate is used as a representative example.

[0134] After applying the slurry for forming the third layer, the applied slurry can be dried to form the third layer. For example, drying can be carried out in a convection oven. The drying temperature can be 30°C to 100°C, 35°C to 95°C, 40°C to 90°C, 45°C to 80°C, 48°C to 75°C, or 50°C to 70°C. Alternatively, drying can be carried out for 10 seconds to 20 minutes, 30 seconds to 15 minutes, 1 minute to 10 minutes, or 2 minutes to 8 minutes.

[0135] Alternatively, it may further include drying the aforementioned slurry used to form the third layer to form the third layer 13 on the second layer 12, and then compressing the third layer 13, wherein the compression conditions may follow conditions generally known in the art.

[0136] Alternatively, if a substrate is used in the formation of the third layer, the substrate may be removed if necessary.

[0137] Alternatively, the slurry used to form the third layer 13 may further include one or more components selected from binders, alkali metal salts, ionic liquids, and conductive polymers previously mentioned as components that may be included in the second layer 12. Alternatively, dispersants commonly known in the art (e.g., H-NBR, etc.) may be added.

[0138] According to some embodiments, after forming the aforementioned third layer, the method may further include drying the stack (stack) in which the first, second, and third layers are stacked. For example, the drying of the stack may be carried out in a vacuum oven. For example, the drying temperature of the aforementioned stack may be higher than the drying temperatures of the aforementioned first, second, and third layers, respectively. Alternatively, the drying temperature of the stack may be 50°C to 150°C, 60°C to 130°C, 70°C to 120°C, or 80°C to 100°C. Alternatively, the drying time of the stack may be 30 minutes to 10 hours, 40 minutes to 8 hours, or 1 hour to 5 hours. Within this range, a solid electrolyte membrane 300 in which the first, second, and third layers are stacked can be effectively manufactured.

[0139] All-solid-state rechargeable batteries

[0140] In some embodiments, an all-solid-state rechargeable battery is provided, comprising: a positive electrode layer; a negative electrode layer; and the aforementioned solid electrolyte membrane between the positive electrode layer and the negative electrode layer. Because the all-solid-state rechargeable battery includes the solid electrolyte membrane according to the foregoing embodiments, it can ensure battery safety by effectively suppressing internal short circuits in individual cells, while exhibiting excellent ion conductivity and high-rate performance.

[0141] In the following text, descriptions that are repeated above will be omitted, and reference will be made to... Figure 7 and8 The components of an all-solid-state rechargeable battery according to some embodiments are described in more detail.

[0142] All-solid-state rechargeable batteries can be referred to as all-solid-state batteries or all-solid-state rechargeable lithium batteries.

[0143] Figure 7 This is a cross-sectional view of an all-solid-state battery according to some embodiments. (Refer to...) Figure 7 The all-solid-state battery 100 includes an electrode assembly in a housing, such as a bag. Within the electrode assembly, a negative electrode layer 400 comprising a negative electrode current collector 401 and a negative electrode active material layer 403, a solid electrolyte membrane 300, and a positive electrode layer 200 comprising a positive electrode current collector 201 and a positive electrode active material layer 203 are stacked. The all-solid-state battery 100 may further include an elastic layer 500 outside at least one of the positive electrode layer 200 and the negative electrode layer 400. Meanwhile, Figure 7 An electrode assembly is shown, comprising a negative electrode layer 400, a solid electrolyte membrane 300, and a positive electrode layer 200, but an all-solid-state battery can also be fabricated by stacking two or more electrode assemblies.

[0144] Positive electrode layer

[0145] The positive electrode layer may include, for example, a positive electrode current collector 201 and a positive electrode active material layer 203 on the positive electrode current collector 201.

[0146] The positive electrode current collector 201 can be selected from aluminum foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof. Aluminum foil can be used as the positive electrode current collector, but is not limited thereto.

[0147] The positive electrode active material layer 203 may include a positive electrode active material and may optionally further include a solid electrolyte, a binder, and / or a conductive material.

[0148] Positive electrode active material

[0149] As the positive electrode active material, compounds capable of reversibly inserting and deintercalating lithium (lithiation intercalation compounds) can be used. For example, one or more composite oxides of metals selected from cobalt, manganese, nickel, and combinations thereof with lithium can be used.

[0150] The composite oxide can be a lithium transition metal composite oxide, and specific examples include lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate (LiFePO4)-based compounds, cobalt-free nickel manganese-based oxides, lithium-excess layered oxides, or combinations thereof. For example, the positive electrode active material can be a high-nickel-based positive electrode active material having a nickel content greater than or equal to 80 mol%, based on 100 mol% of metals other than lithium in the lithium transition metal composite oxide. The nickel content in the high-nickel-based positive electrode active material can be greater than or equal to 85 mol%, greater than or equal to 90 mol%, greater than or equal to 91 mol%, or greater than or equal to 94 mol% and less than or equal to 99 mol%, based on 100 mol% of metals other than lithium. High-nickel-based positive electrode active materials can achieve high capacity and can be used in high-capacity, high-density rechargeable lithium batteries.

[0151] As a more specific example, a compound represented by any of the following chemical formulas can be used. Li a A 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Mn 2-b X b O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 < α < 2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤0.5, 0 ≤ c ≤ 0.5, 0 < α < 2); Li a Ni b Co c L 1 d G e O2 (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 0.1); Lia NiG b O2 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn 1-b G b O2 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (0.90 ≤ a ≤1.8, 0.001 ≤ b ≤ 0.1); Li a Mn 1-g G g PO4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); Li (3-f) Fe2(PO4)3 (0 ≤ f ≤ 2); and Li a FePO4 (0.90 ≤ a ≤ 1.8).

[0152] In the above chemical formulas, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; Z is Cr, V, Fe, Sc, Y, or a combination thereof; L 1 It is Mn, Al, or a combination thereof.

[0153] The positive electrode active material may include, for example, lithium nickel-based oxides represented by chemical formula 21, lithium cobalt-based oxides represented by chemical formula 22, lithium iron phosphate-based compounds represented by chemical formula 23, cobalt-free lithium nickel manganese-based oxides represented by chemical formula 24, or combinations thereof.

[0154] [Chemical Formula 21]

[0155] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0156] In chemical formula 21, 0.9 ≤ a1 ≤ 1.8, 0.3 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.7, 0 ≤ z1 ≤ 0.7, 0.9 ≤ x1 + y1 + z1 ≤ 1.1, 0 ≤ b1 ≤ 0.1, M 1 and M 2 Independently, X is one or more elements selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from F, P, and S.

[0157] In chemical formula 21, 0.6≤x1≤1, 0≤y1≤0.4 and 0≤z1≤0.4; or 0.8≤x1≤1, 0≤y1≤0.2 and 0≤z1≤0.2.

[0158] [Chemical Formula 22]

[0159] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0160] In chemical formula 22, 0.9 ≤ a² ≤ 1.8, 0.7 ≤ x² ≤ 1, 0 ≤ y² ≤ 0.3, 0.9 ≤ x² + y² ≤ 1.1, and 0 ≤ b² ≤ 0.1, M 3 X is one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is one or more elements selected from F, P, and S.

[0161] [Chemical Formula 23]

[0162] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0163] In chemical formula 23, 0.9 ≤ a³ ≤ 1.8, 0.6 ≤ x³ ≤ 1, 0 ≤ y³ ≤ 0.4, 0 ≤ b³ ≤ 0.1, M 4 X is one or more elements selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is one or more elements selected from F, P, and S.

[0164] [Chemical Formula 24]

[0165] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0166] In chemical formula 24, 0.9 ≤ a² ≤ 1.8, 0.8 ≤ x⁴ < 1, 0 <y4≤0.2,0≤z4≤0.2,0.9≤x4+y4+z4≤1.1,0≤b4≤0.1,M 5 X is one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from F, P, and S.

[0167] The average particle size (D) of the positive electrode active material 50 The particle size can be from 1 μm to 25 μm, for example, 3 μm to 25 μm, 1 μm to 20 μm, 1 μm to 18 μm, 3 μm to 15 μm, or 5 μm to 15 μm. For example, the positive electrode active material may include an average particle size (D) of 1 μm to 9 μm. 50 Small particles with an average particle size (D) of 10 μm to 25 μm 50 Large particles ( ). Positive electrode active materials with this particle size range can be harmoniously mixed with other components within the positive electrode active material layer, and can achieve high capacity and high energy density. In this paper, the average particle size refers to the diameter (D) of the particles representing 50% of the cumulative volume in the particle size distribution obtained by randomly measuring the size (diameter or major axis length) of 20 particles in a scanning electron microscope image of the positive electrode active material. 50 ).

[0168] The positive electrode active material can be in the form of secondary particles made by agglomerating multiple primary particles or in the form of single particles. In addition, the positive electrode active material can have a spherical or nearly spherical shape, or it can have a polyhedral or irregular shape.

[0169] Simultaneously, the positive electrode active material may include a buffer layer on the particle surface. The buffer layer can be represented as a coating, protective layer, etc., and can be used to reduce the interfacial resistance between the positive electrode active material and the sulfide-based solid electrolyte particles. For example, the buffer layer may include a lithium-metal oxide, wherein the metal is one or more elements selected from, for example, Al, B, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ta, V, W, and Zr. The lithium-metal oxide improves the performance of the positive electrode active material by promoting lithium-ion movement and electron conduction, and is thus improved for reducing the interfacial resistance between the positive electrode active material and the solid electrolyte particles.

[0170] The content of the positive electrode active material can be within the range known in the art and is not particularly limited. For example, based on the total weight of the positive electrode active material layer, the positive electrode active material can be included in an amount of 55% to 99% by weight, such as 65% to 95% by weight or 75% to 91% by weight.

[0171] adhesive

[0172] The binder is used to adhere the positive electrode active material particles to each other and also to adhere the positive electrode active material to the positive electrode current collector 201. Examples of binders may be selected from one or more of the following: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide (including polymers including ethylene oxide), polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, polyacrylonitrile, polymethyl methacrylate, vinylidene fluoride / hexafluoropropylene copolymer, epoxy resin, (meth)acrylate resin, polyester resin, and nylon, but not limited thereto.

[0173] conductive materials

[0174] Conductive materials are included to provide electrode conductivity, and any electrically conductive material can be used as the conductive material unless it causes a chemical change. Examples of conductive materials may include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, carbon nanotubes, etc.; metal-based materials including metal powders or metal fibers of copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0175] Based on the total weight of the positive electrode active material layer 203, the contents of the binder and conductive material can be from 0.1% to 10% by weight or from 0.1% to 5% by weight, respectively.

[0176] In addition to the positive electrode active material, binder, and conductive material, the positive electrode active material layer 203 may further include, for example, additives such as fillers, coating agents, dispersants, and ion-conducting agents. As fillers, coating agents, dispersants, ion-conducting agents, etc., that may be included in the positive electrode layer, known materials commonly used in the positive electrodes of all-solid-state rechargeable batteries can be used.

[0177] solid electrolyte

[0178] The positive electrode active material layer 203 may optionally include a solid electrolyte. The solid electrolyte may include, for example, sulfide-based solid electrolytes, oxide-based solid electrolytes, halide-based solid electrolytes, or combinations thereof, and its specific description may be the same as that described above in the solid electrolyte membrane 300. As a representative example, when the positive electrode active material layer 203 further includes a sulfide-based solid electrolyte, the ionic conductivity of the positive electrode layer can be further improved.

[0179] The solid electrolyte included in the positive electrode active material layer 203 can be used in the same manner as the solid electrolyte included in the shell 1b of the aforementioned composite 1 or the solid electrolyte particles included in the first to third layers 11 to 13 of the aforementioned solid electrolyte membrane 300.

[0180] The solid electrolyte included in the positive electrode active material 203 may be the same as the solid electrolyte included in the shell 1b of the aforementioned composite 1 or the solid electrolyte particles included in the first layer 11 to the third layer 13. For example, when the shell 1b of the composite 1 is composed of Li6PS5Cl, the sulfide solid electrolyte included in the positive electrode active material layer 203 may also be composed of Li6PS5Cl.

[0181] In the positive electrode active material layer 203, the content of solid electrolyte can be from 0.5% to 30% by weight, for example from 1% to 5% by weight, based on the total weight of the positive electrode active material layer 203. If the solid electrolyte is included in the positive electrode active material layer 203 in this amount, the efficiency and cycle life characteristics of the all-solid-state rechargeable battery can be improved without reducing the capacity.

[0182] negative electrode layer

[0183] The negative electrode layer may include, for example, a current collector and a layer of negative electrode active material on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder, a conductive material, and / or a solid electrolyte.

[0184] The negative electrode active material may include materials that can reversibly insert / deintercalate lithium ions, lithium metal, lithium metal alloys, materials that can be doped / dedoped with lithium, or transition metal oxides.

[0185] Materials that can reversibly embed / desorb lithium ions may include, for example, crystalline carbon, amorphous carbon, or a combination thereof as carbon-based negative electrode active materials. The crystalline carbon may be natural graphite or artificial graphite in an irregular, sheet, flake (lamellar), spherical, or fibrous shape. The amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbonized product, calcined coke, etc. <N

[0186] Lithium metal alloys include alloys of lithium and metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0187] Materials that can be doped / undoped with lithium may be Si-based negative electrode active materials or Sn-based negative electrode active materials. The Si-based negative electrode active materials may include silicon, silicon-carbon composites, SiO x (0 < x < 2), Si-Q alloys (where Q is an alkali metal, alkaline earth metal, group 13 element, group 14 element, group 15 element, group 16 element, transition metal, rare earth element, and combinations thereof, but not Si), and the Sn-based negative electrode active materials may include Sn, SnO2, Sn-R alloys (where R is an alkali metal, alkaline earth metal, group 13 element, group 14 element, group 15 element, group 16 element, transition metal, rare earth element, and combinations thereof, but not Sn). At least one of these materials may be mixed with SiO2. The elements Q and R may include Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.

[0188] The silicon-carbon composite may be, for example, a silicon-carbon composite including: a core including crystalline carbon and silicon particles, and an amorphous carbon coating layer provided on the surface of the core. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof. As the amorphous carbon precursor, coal-based pitch, mesophase pitch, petroleum-based pitch, coal-based oil, petroleum-based heavy oil, or polymer resins such as phenolic resin, furan resin, and polyimide resin may be used. Herein, based on the total weight of the silicon-carbon composite, the content of silicon may be 10% by weight to 50% by weight. Additionally, based on the total weight of the silicon-carbon composite, the content of crystalline carbon may be 10% by weight to 70% by weight, and based on the total weight of the silicon-carbon composite, the content of amorphous carbon may be 20% by weight to 40% by weight. Additionally, the thickness of the amorphous carbon coating layer may be 5 nm to 100 nm.

[0189] The average particle size (D 50The silicon particles can be 10 nm to 20 μm or, for example, 10 nm to 500 nm. The silicon particles can exist in an oxidized form, and in this case, the atomic ratio of Si:O, representing the degree of oxidation, can be 99:1 to 33:67. The silicon particles can be SiO₂. x Particles, and in this case, SiO x The range of x in the equation can be greater than 0 and less than 2. Average particle size (D) 50 It can be measured by microscopic images or a particle size analyzer, and can refer to the diameter of particles that have a cumulative volume of 50% in the particle size distribution.

[0190] Si-based or Sn-based negative electrode active materials can be mixed with carbon-based negative electrode active materials. The mixing ratio of Si-based or Sn-based negative electrode active materials to carbon-based negative electrode active materials can be from 1:99 to 90:10 by weight.

[0191] Based on the total weight of the negative electrode active material layer, the content of the negative electrode active material in the negative electrode active material layer can be from 95% to 99% by weight.

[0192] In some embodiments, the negative electrode active material layer may further include a binder and optionally include a conductive material. Based on the total weight of the negative electrode active material layer, the binder content in the negative electrode active material layer may be from 1% to 5% by weight. Alternatively, if a conductive material is further included, the negative electrode active material layer may include 90% to 98% by weight of negative electrode active material, 1% to 5% by weight of binder, and 1% to 5% by weight of conductive material.

[0193] The binder is used to ensure good adhesion between the particles of the negative electrode active material and to the current collector. The binder may include water-insoluble binders, water-soluble binders, or combinations thereof.

[0194] Water-insoluble adhesives may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers (polymers containing ethylene oxide), ethylene propylene copolymers, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, or combinations thereof.

[0195] Water-soluble adhesives can be rubber-based adhesives or polymer resin adhesives. Rubber-based adhesives can be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acryloyl rubber, butyl rubber, fluororubber, and combinations thereof. Polymer resin adhesives can be selected from polyethylene oxide, polyvinylpyrrolidone, polyepoxychlorohydrin, polyphosphazene, polyacrylonitrile, ethylene-propylene-diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0196] When a water-soluble binder is used as the binder for the negative electrode layer, a thickener capable of imparting viscosity may also be used, and the thickener may include, for example, a cellulose compound. Cellulose compounds may include carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, their alkali metal salts, or combinations thereof. The alkali metal may be Na, K, or Li. Based on 100 parts by weight of the negative electrode active material, the amount of thickener used may be from 0.1 parts by weight to 3 parts by weight.

[0197] The conductive material is included to impart conductivity to the electrode, and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, etc.; metal-based materials including metal powders or metal fibers of copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0198] The negative electrode current collector may include one of the following: copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof.

[0199] For example, the negative electrode layer can be a precipitated negative electrode layer. A precipitated negative electrode layer can be a negative electrode layer that does not have a negative electrode active material during battery assembly, but in which lithium metal or the like is precipitated during battery charging and used as a negative electrode active material.

[0200] Figure 8 This is a schematic cross-sectional view including the deposited negative electrode layer. (Refer to...) Figure 8The precipitated negative electrode layer 400' may include a negative electrode current collector 401 and a negative electrode coating 405 on the current collector. In an all-solid-state battery having this precipitated negative electrode layer 400', initial charging begins without a negative electrode active material, and a high-density lithium metal or the like precipitates between the current collector 401 and the negative electrode catalyst layer 405 during charging, forming a lithium metal layer 404, which can serve as the negative electrode active material. Therefore, in an all-solid-state battery that has been charged more than once, the precipitated negative electrode layer 400' may include a current collector 401, a lithium metal layer 404 on the current collector, and a negative electrode coating 405 on the metal layer 404. The lithium metal layer 404 refers to a layer of lithium metal or the like precipitated during battery charging and may be referred to as a metal layer, a negative electrode active material layer, etc.

[0201] The negative electrode coating 405 may include a lithium-loving metal (which acts as a catalyst), a carbon material, or a combination thereof.

[0202] The metal may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or combinations thereof, and may be composed of one or more types of alloys of these. When the metal exists in particulate form, its average particle size (D) 50 It can be less than or equal to about 4 μm or, for example, 10 nm to 4 μm.

[0203] Carbon materials can be, for example, crystalline carbon, amorphous carbon, or combinations thereof. Crystalline carbon can be, for example, natural graphite, artificial graphite, mesophase carbon microspheres, or combinations thereof. Amorphous carbon can be, for example, carbon black, activated carbon, acetylene black, superconducting acetylene black, Ketjen black, or combinations thereof.

[0204] When the negative electrode coating 405 comprises a metal and a carbon material, the metal and carbon material can be mixed, for example, in a weight ratio of 1:10 to 2:1. This effectively promotes the deposition of lithium metal and improves the characteristics of the all-solid-state battery. The negative electrode coating 405 may comprise, for example, a carbon material on which a catalyst metal is supported, or a mixture of metal particles and carbon material particles.

[0205] The negative electrode coating 405 may include, for example, metal and amorphous carbon, and in this case, lithium metal deposition can be effectively promoted.

[0206] The negative electrode coating 405 may further include a binder, and the binder may be a conductive binder. Additionally, the negative electrode coating 405 may further include conventional additives such as fillers, dispersants, and ion conductors.

[0207] The thickness of the negative electrode coating 405 can be, for example, 100 nm to 20 μm, 500 nm to 10 μm, or 1 μm to 5 μm.

[0208] The deposited negative electrode layer 400' may further include a thin film, for example, on the surface of the current collector, i.e., between the current collector and the negative electrode coating. The thin film may include elements capable of forming alloys with lithium. Elements capable of forming alloys with lithium may include, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., which may be used alone or in alloys of more than one. The thin film may further planarize the deposited shape of the lithium metal layer 404 and significantly improve the characteristics of the all-solid-state battery. The thin film may be formed by, for example, vacuum deposition, sputtering, or plating methods. The thickness of the thin film may be, for example, from 1 nm to 500 nm.

[0209] All-solid-state rechargeable batteries can be single-cell batteries (cell cells) with a structure of positive electrode layer / solid electrolyte membrane / negative electrode layer, dual-cell batteries with a structure of negative electrode layer / solid electrolyte membrane / positive electrode layer / solid electrolyte membrane / negative electrode layer, or stacked batteries with a structure of repeated single-cell batteries.

[0210] There are no particular limitations on the shape of all-solid-state rechargeable batteries, and they can be in various forms such as coin-shaped, button-shaped, sheet-shaped, stacked, cylindrical, and flat. Furthermore, all-solid-state batteries can also be used in large batteries used in electric vehicles, etc. For example, all-solid-state rechargeable batteries can also be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). Additionally, they can be used in fields requiring large amounts of energy storage, and can be used in, for example, electric bicycles or power tools.

[0211] In the following description, embodiments and comparative examples are presented. However, it will be understood that the embodiments are for illustrative purposes and are not intended to limit the invention.

[0212] Example 1

[0213] (1) Preparation of the complex

[0214] As diamagnetic particles, needle-shaped artificial graphite with an aspect ratio of 4.0, a minor axis length of 1 μm, and a major axis length of 4 μm was prepared. Additionally, Li₂S, P₂S₅, and LiCl, as raw materials for the solid electrolyte, were mixed in a molar ratio of 5:1:2. The solid electrolyte raw material mixture and the diamagnetic particles were mixed in acetonitrile solvent at a weight ratio of 30:1, then magnetically stirred for 2 hours, dried at 120°C, and heat-treated at 400°C. Thus, a solid electrolyte composite was obtained, comprising: a core containing needle-shaped artificial graphite; and a shell surrounding the core comprising a Li₆PS₅Cl solid electrolyte.

[0215] (2) Preparation of slurry for forming the second layer

[0216] 20% by weight of the composite and 78.3% by weight of Li6PS5Cl solid electrolyte particles (D) as argentite-germanium sulfide crystals were used. 50 =3 μm), 1.3% by weight of acrylamide binder (SX-A334, Zeon Co., Ltd.) and 0.4% by weight of dispersant (H-NBR) were added to octyl acetate solvent and then mixed with a Thinky mixer to prepare a slurry for the second layer.

[0217] (3) Manufacturing of the first layer

[0218] Acrylamide binder (SX-A334, Zeon Co., Ltd.) was added to octyl acetate to prepare an acrylamide binder solution with 4% by weight of binder. The acrylamide binder solution was then added to Li6PS5Cl solid electrolyte particles (D... 50 =3 μm (silver sulfide-germanium ore type crystals), and then mixed with a Thinky mixer to prepare a slurry. Based on 98.5 parts by weight of solid electrolyte, the slurry includes 1.5 parts by weight of acrylamide binder. The prepared slurry is coated onto nonwoven fabric using a doctor blade coater and dried in a convection oven at 50°C for 5 minutes to obtain stacked parts.

[0219] (4) Manufacturing of the second layer

[0220] The prepared slurry for forming the second layer was applied to the first layer using a doctor blade coater, and a magnetic field of 1 T was applied to it at 25°C for 2 minutes. After applying the magnetic field, the magnetically applied slurry was dried in a convection oven at 50°C for 5 minutes. Through the above process, a stack having a second layer formed on the first layer was manufactured.

[0221] (5) Manufacturing of the third layer

[0222] Subsequently, an acrylamide binder (SX-A334, Zeon Co., Ltd.) was added to octyl acetate to prepare an acrylamide binder solution with 4% by weight of binder. The acrylamide binder solution was then added to Li6PS5Cl solid electrolyte particles (D... 50 =3 μm (silver-germanium sulfide type crystals), and then mixed with a Thinky mixer to prepare a slurry for the third layer. Based on 98.5 parts by weight of solid electrolyte, the slurry for the third layer includes 1.5 parts by weight of acrylamide binder. The prepared slurry for the third layer is coated onto the second layer using a doctor blade coater, and then dried in a convection oven at 50°C for 5 minutes to obtain a stacked part having a first layer-second layer-third layer in sequence.

[0223] Subsequently, the stacked components were dried in a vacuum oven at 80°C for more than 2 hours to produce a solid electrolyte membrane 300.

[0224] (6) Fabrication of the positive electrode layer

[0225] By using octyl acetate as a solvent and mixing 13.5% by weight of Li6PS5Cl solid electrolyte (D... 50 =3 μm (silver sulfide-germanium type crystal), 85 wt% positive electrode active material (LiNi 0.8 Co 0.1 Al 0.1 The positive electrode slurry was prepared using O2, 1.0 wt% PVDF binder, and 0.5 wt% carbon nanotubes. The positive electrode slurry was coated onto one surface of an aluminum foil containing a positive electrode current collector, and then dried and compressed to fabricate the positive electrode.

[0226] (7) Fabrication of the negative electrode layer

[0227] A nickel foil with a thickness of 12.5 μm was prepared as the negative electrode current collector. Additionally, a material with a density of approximately 30 nm was prepared as the material for forming the negative electrode coating. 50 Carbon black (CB) with a particle size of approximately 60 nm and D 50 Silver (Ag) particles of varying sizes.

[0228] Carbon black (CB) and silver (Ag) particles were mixed at a weight ratio of 3:1. After adding 0.25 g of the mixed powder to a container, 2 g of NMP solution including 7% by weight PVDF binder (#9300, Kureha Corp.) was added to prepare a mixed solution. The mixed solution was then stirred while NMP was added little by little to prepare a slurry. The prepared slurry was coated onto nickel foil using a doctor blade coater and dried in a convection oven at 80°C for 10 minutes to obtain a stack. The obtained stack was then vacuum dried at 100°C for at least 8 hours, i.e., 10 hours. Through the above process, a negative electrode layer in which a negative electrode coating is formed on the negative electrode current collector was manufactured.

[0229] (8) Manufacturing of all-solid-state rechargeable batteries

[0230] A solid electrolyte membrane 300 was disposed between the positive electrode layer and the negative electrode layer to prepare a stack. The prepared stack was pressed at 80°C with a pressure of 500 MPa for 30 minutes to manufacture an all-solid-state rechargeable battery cell. Through this pressing process, the solid electrolyte membrane was sintered, improving battery characteristics. The pressed positive electrode active material layer has a thickness of approximately 103 μm, the negative electrode coating has a thickness of 7 μm, and the solid electrolyte membrane has a thickness of 60 μm.

[0231] Furthermore, a cross-sectional sample was prepared from the solid electrolyte membrane 300, in which the first layer 11, the second layer 12, and the third layer 13 were stacked sequentially, and its image was captured using a scanning electron microscope (SEM). When measured with SEM, the first layer had an average thickness of 30 μm, the second layer had an average thickness of 60 μm, and the third layer had an average thickness of 30 μm. In this paper, the average thicknesses of the first, second, and third layers were obtained by measuring the thickness at any ten points at equal intervals and calculating their average value.

[0232] In the cross-sectional specimens, any 10 composites in the second layer 12 were randomly selected to measure the shell thickness of each composite, and then the average shell thickness was calculated to be 0.5 μm.

[0233] Comparative Example 1

[0234] The solid electrolyte membrane and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the solid electrolyte membrane was formed as a single layer consisting only of solid electrolyte particles (Li6PS5Cl) instead of a three-layer solid electrolyte membrane.

[0235] Comparative Example 2

[0236] The solid electrolyte membrane and all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the slurry for the second layer was prepared by using needle-shaped artificial graphite with an aspect ratio of 4.0, a short axis length of 1 μm and a long axis length of 4 μm without forming a shell, instead of the composite.

[0237] Comparative Example 3

[0238] The solid electrolyte membrane and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the composite was prepared by using needle-shaped artificial graphite with an aspect ratio of 1.0, a short axis length of 3.5 μm, and a long axis length of 3.5 μm without forming a shell.

[0239] For reference, Table 1 shows the structure of the solid electrolyte (or complex) of Example 1 and Comparative Examples 1 to 3, the structure of the solid electrolyte membrane, the shape of the diamagnetic particles, the aspect ratio of the diamagnetic particles, the short axis length and long axis length of the diamagnetic particles, and the core-to-shell weight ratio of the complex.

[0240] (Table 1)

[0241]

[0242] Evaluation Example 1: Ionic conductivity of the positive electrode layer

[0243] The ionic conductivity of the solid electrolyte membranes in the examples and comparative examples was evaluated.

[0244] Specifically, the solid electrolyte membranes of the examples and comparative examples were each placed in a mold with a diameter of 10 mm and then pressed into pellets (discs) under a pressure of 350 mPa. Indium (In) films were coated on both sides of the pellets to prepare samples for measuring ionic conductivity. The impedance of the samples was measured using an AUTOLAB PGSTAT30 (Metrohm Autolab Co. Ltd.) (potentiostat) to plot the Nyquist plot, from which the ionic conductivity at 45°C was measured. The results are shown in Table 2 below.

[0245] (Table 2)

[0246]

[0247] Referring to Table 2, the solid electrolyte membrane of Example 1 exhibits higher ionic conductivity than the solid electrolyte membranes of Comparative Examples 1 to 3.

[0248] In Example 1, a solid electrolyte membrane was manufactured using a composite having a core-shell structure, comprising: a core including diamagnetic particles having an aspect ratio greater than 1; and a shell surrounding the core and including a solid electrolyte. Therefore, when a magnetic field is applied during the manufacturing process of Example 1, the composite is oriented in the second layer 12 of the solid electrolyte membrane within a range of 50° to 130° relative to the planar direction of the solid electrolyte membrane. The orientation of the composite was confirmed by manufacturing cross-sectional samples of the solid electrolyte membrane, capturing images of them using a scanning electron microscope (SEM) to measure the orientation angles of any 10 composites, and calculating their average value. In the above-described solid electrolyte membrane, due to the orientation of the composite, the lithium-ion path is shortened in the solid electrolyte membrane according to Example 1, and high ion conductivity is ensured.

[0249] In contrast, Comparative Example 1 uses a single-layer solid electrolyte membrane instead of the three-layer solid electrolyte membrane of Example 1 and uses an amorphous solid electrolyte itself instead of the composite of Example 1. Therefore, during the manufacture of the solid electrolyte membrane of Comparative Example 1, even when a magnetic field is applied to it, the amorphous solid electrolyte in the solid electrolyte membrane is not specifically oriented, but randomly oriented.

[0250] Comparative Example 2 uses only needle-shaped artificial graphite without a solid electrolyte shell to replace the composite in the second layer of Example 1. Therefore, when a magnetic field is applied during the manufacturing process of the solid electrolyte membrane according to Comparative Example 2, the needle-shaped artificial graphite without a solid electrolyte shell is oriented almost vertically in the second layer of the solid electrolyte membrane. However, in Comparative Example 2, because a solid electrolyte shell is not formed, a battery safety issue exists in Evaluation Example 2.

[0251] On the other hand, in the solid electrolyte membrane of Comparative Example 3, the composite did not exhibit orientation even when a magnetic field was applied. Therefore, compared to Comparative Example 1, there was no increase in ionic conductivity.

[0252] Evaluation Example 2: Evaluation of the high-rate performance and internal short-circuit occurrence of all-solid-state rechargeable batteries

[0253] For each of the all-solid-state rechargeable batteries in the examples and comparative examples, the high-rate characteristics were evaluated.

[0254] Specifically, the all-solid-state rechargeable battery cells of the examples and comparative examples were charged at 45°C in a thermostat at 0.1 C and constant current to 4.25 V and discharged at 0.1 C and constant current to 2.5 V (first cycle); charged at 0.1 C and constant current to 4.25 V and discharged at 0.33 C and constant current to 2.5 V (second cycle); charged at 0.1 C and constant current to 4.25 V and discharged at 1.0 C and constant current to 2.5 V (third cycle) to evaluate discharge capacity and high-rate performance.

[0255] The discharge capacity and high-rate performance at each cycle are shown in Table 2. In this paper, high-rate performance is defined according to Equation 4.

[0256] [Equation 4]

[0257] High-rate performance [%] = [Discharge capacity in the 3rd cycle (1C rate) / Discharge capacity in the 1st cycle (0.1C rate)] × 100 [%]

[0258] Furthermore, in the above charging and discharging cycles, "X" is given when no internal short circuit occurs, but "O" is given when an internal short circuit occurs, and the results are shown in Table 3.

[0259] (Table 3)

[0260]

[0261] Referring to Table 3, compared with Comparative Examples 1 to 3, Example 1 exhibited superior high-rate performance and excellent discharge capacity in each cycle, and no internal short circuits. Therefore, by using the composite shown in Example 1 to form a three-layer solid electrolyte membrane, the high-rate performance of the all-solid-state rechargeable battery cell is improved, and there is an effect of suppressing internal short circuits.

[0262] Conversely, the cell in Comparative Example 1 did not exhibit an internal short circuit, but as confirmed in Evaluation Example 1, it exhibited low ion conductivity, and the cells in Comparative Examples 2 and 3 exhibited internal short circuits.

[0263] While the invention has been described with respect to exemplary embodiments which are now considered practical, it will be understood that the invention is not limited to the disclosed embodiments. Rather, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0264] <Description of reference numerals in the attached figures>

[0265] 1: Composite, 1a: Core, 1b: Shell, 2: Solid electrolyte particle, 4: Lithium ion, 11: First layer, 12: Second layer, 13: Third layer, 100: All-solid-state rechargeable battery, 200: Positive electrode layer, 201: Positive electrode current collector, 203: Positive electrode active material layer, 300: Solid electrolyte membrane, 400: Negative electrode layer, 400': Precipitated negative electrode layer, 401: Negative electrode current collector, 403: Negative electrode active material layer, 404: Lithium metal layer, 405: Negative electrode coating, 500: Elastic layer

Claims

1. Solid electrolyte membrane, including: The first layer includes solid electrolyte particles; A second layer comprising the complex on the first layer; and A third layer is formed on the second layer and includes solid electrolyte particles. The composite comprises: a core including antimagnetic particles; and a shell surrounding the core and including a solid electrolyte.

2. The solid electrolyte membrane according to claim 1, wherein... The diamagnetic particles have an aspect ratio greater than 1, as expressed by Equation 1: [Equation 1] Aspect ratio = length of major axis / length of minor axis.

3. The solid electrolyte membrane according to claim 2, wherein... The long axis of the composite is oriented in the range of 50° to 130° relative to the plane of the solid electrolyte membrane.

4. The solid electrolyte membrane according to claim 1, wherein... The composite comprises the core and the shell in a weight ratio of 1:1 to 1:

500.

5. The solid electrolyte membrane according to claim 1, wherein... The antimagnetic particles are needle-shaped, plate-shaped, or elliptical.

6. The solid electrolyte membrane according to claim 1, wherein... The core comprises carbon-based materials selected from artificial graphite, natural graphite, graphene, carbon nanotubes (CNTs), carbon fibers, carbon black, or combinations thereof as antimagnetic particles.

7. The solid electrolyte membrane according to claim 1, wherein... The shell includes a solid electrolyte selected from sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, or combinations thereof.

8. The solid electrolyte membrane according to claim 1, wherein... The complex satisfies one or more of equations 2 and 3: [Equation 2] 0.1 ≤ A1 / B ≤ 100 [Equation 3] 0.01 ≤ A2 / B ≤ 10 in, In equations 2 and 3, A1 represents the length of the major axis of the core, A2 represents the length of the minor axis of the core, and B represents the thickness of the shell.

9. The solid electrolyte membrane according to claim 1, wherein... The second layer further includes solid electrolyte particles.

10. The solid electrolyte membrane according to claim 1, wherein... The solid electrolyte particles are sulfide-based solid electrolyte particles.

11. The solid electrolyte membrane according to claim 1, wherein... The major axis length of the core is from 1 μm to 50 μm, and The short axis length of the core is 10 nm to 5 μm.

12. The solid electrolyte membrane according to claim 1, wherein... The composite is included in an amount from 0.1% to 50% by weight, based on the total weight of the second layer.

13. The solid electrolyte membrane according to claim 1, wherein... The average thickness of the first layer is 10 μm to 200 μm, and The average thickness of the third layer is 10 μm to 200 μm.

14. The solid electrolyte membrane according to claim 1, wherein... The average thickness of the second layer is greater than the average thickness of the first layer and the third layer.

15. The solid electrolyte membrane according to claim 1, wherein... The average thickness of the second layer is in the range of 1.2 to 5 times the average thickness of the first layer and the third layer, respectively.

16. The solid electrolyte membrane according to claim 1, wherein... The average thickness of the first layer is 10 μm to 34 μm. The average thickness of the second layer is 35 μm to 100 μm, and The average thickness of the third layer is 10 μm to 34 μm.

17. The solid electrolyte membrane according to claim 1, wherein... Based on the total weight of the second layer, the content of the adhesive included in the second layer is from 0.1% to 3% by weight.

18. The solid electrolyte membrane according to claim 1, wherein... Based on the total weight of the second layer, the content of solid electrolyte particles included in the second layer is from 50% to 99.9% by weight.

19. A method for preparing a solid electrolyte membrane, comprising: Forming a first layer comprising solid electrolyte particles. A second layer comprising the complex is formed on the first layer, and A third layer comprising solid electrolyte particles is formed on the second layer. The composite comprises: a core including antimagnetic particles; and a shell surrounding the core and including a solid electrolyte.

20. The method for preparing a solid electrolyte membrane according to claim 19, wherein... The formation of the second layer includes, The preparation of the complex comprises: The core includes antimagnetic particles; and the shell surrounding the core and comprising the solid electrolyte, Preparation of a slurry comprising the composite for forming the second layer, and The slurry used to form the second layer is applied to the first layer.

21. The method for preparing a solid electrolyte membrane according to claim 20, wherein... The method further includes applying a magnetic field to the slurry coated on the first layer for forming the second layer.

22. The method for preparing a solid electrolyte membrane according to claim 21, wherein... The method further includes drying the slurry used to form the second layer, on which the magnetic field has been applied.

23. The method for preparing a solid electrolyte membrane according to claim 19, wherein... The preparation of the complex includes, The antimagnetic particles, solid electrolyte, and first solvent are mixed to prepare a mixed solution. The mixed solution was dried, and The dried product is then heat-treated.

24. The method for preparing a solid electrolyte membrane according to claim 20, wherein... The slurry for forming the second layer is prepared by mixing the complex and the second solvent.

25. The method for preparing a solid electrolyte membrane according to claim 21, wherein... The magnetic field strength ranges from 0.1 T to 3 T.

26. The method for preparing a solid electrolyte membrane according to claim 21, wherein... The magnetic field is applied for a period of 0.1 seconds to 10 minutes.

27. The method for preparing a solid electrolyte membrane according to claim 19, wherein... The method further includes: After the third layer is formed, the stack of the first, second, and third layers is dried. The drying temperature of the stacked components is higher than the drying temperatures of the first layer, the second layer, and the third layer.

28. The method for preparing a solid electrolyte membrane according to claim 27, wherein... The drying of the stacked components is carried out at a temperature between 70°C and 120°C.

29. All-solid-state rechargeable batteries, including: Positive electrode layer; Negative electrode layer; as well as A solid electrolyte membrane according to any one of claims 1 to 18, located between the positive electrode layer and the negative electrode layer.

30. The all-solid-state rechargeable battery according to claim 29, wherein The negative electrode includes A negative electrode current collector; and a negative electrode coating disposed on the negative electrode current collector and comprising a lithium-philic metal, carbon material, or a combination thereof, and Includes a lithium metal layer formed by charging between the negative electrode current collector and the negative electrode coating.

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