Positive electrode, method for manufacturing the same, and all-solid-state rechargeable battery

Abstract

This invention relates to a positive electrode, a method for manufacturing the same, and an all-solid-state rechargeable battery. The positive electrode includes a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material, a sulfide-based solid electrolyte, a binder, and a conductive material. The conductive material includes carbon nanotubes and carbon nanoparticles, and the carbon nanotubes are included in an amount of 40 wt% to 90 wt% based on 100 wt% of the total amount of carbon nanotubes and carbon nanoparticles, and the carbon nanoparticles are included in an amount of 10 wt% to 60 wt%.

Description

Technical Field

[0001] The positive electrode, its manufacturing method, and the all-solid-state rechargeable battery are disclosed. Background Technology

[0002] Portable information devices (such as cell phones, laptops, smartphones, etc.) or electric vehicles already use rechargeable lithium batteries with high energy density and easy portability as their power source. Recently, research has been actively conducted to use rechargeable lithium batteries with high energy density as a power source or energy storage source for hybrid vehicles or electric vehicles.

[0003] Because commercially available rechargeable lithium-ion batteries use electrolytes containing flammable organic solvents, there are safety concerns: the batteries can explode or catch fire in the event of an impact or puncture. Accordingly, all-solid-state rechargeable batteries using solid electrolytes instead of liquid electrolytes have been proposed. All-solid-state rechargeable batteries are those in which all materials are composed of solids, and they offer the advantages of being safe because there is no risk of electrolyte leakage and explosion, and they are easy to manufacture into thin batteries.

[0004] The positive electrode of an all-solid-state rechargeable battery contains various organic and inorganic materials, such as the positive electrode active material, solid electrolyte, conductive material, and binder. However, in the case of sulfide-based solid electrolytes with excellent ionic conductivity, there are concerns that sulfide-based solid electrolytes are easily degraded by air, moisture, polar solvents, or under high-temperature conditions, thereby affecting the performance of the all-solid-state battery. Summary of the Invention

[0005] [Technical Issues]

[0006] According to one embodiment, a positive electrode and an all-solid-state rechargeable battery are provided that can improve the dispersibility and conductivity of the slurry. Alternatively, according to another embodiment, a positive electrode and an all-solid-state rechargeable battery are provided that can improve the quality and yield of the positive electrode plate.

[0007] [Technical Solution]

[0008] In one embodiment, a positive electrode is provided, comprising: a positive electrode current collector; and a positive electrode active material layer on the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material, a sulfide-based solid electrolyte, a binder, and a conductive material, the conductive material comprising carbon nanotubes and carbon nanoparticles, and comprising carbon nanotubes in an amount of 40 wt% to 90 wt% and carbon nanoparticles in an amount of 10 wt% to 60 wt% based on 100 wt% of the total amount of carbon nanotubes and carbon nanoparticles.

[0009] In another embodiment, a method for manufacturing a positive electrode is provided, the method comprising: dry mixing a positive electrode active material, a sulfide solid electrolyte, and carbon nanoparticles, and adding a binder and carbon nanotubes to the dry-mixed mixture and mixing to obtain a positive electrode active material slurry, wherein carbon nanotubes are added in an amount of 40 wt% to 90 wt% based on 100 wt% of the total amount of carbon nanotubes and carbon nanoparticles, and carbon nanoparticles are added in an amount of 10 wt% to 60 wt%.

[0010] In another embodiment, an all-solid-state rechargeable battery is provided, the all-solid-state rechargeable battery including the aforementioned positive electrode; negative electrode; and a solid electrolyte layer between the positive electrode and the negative electrode.

[0011] [Beneficial Effects]

[0012] According to embodiments, a positive electrode capable of improving the dispersibility and conductivity of slurry and an all-solid-state rechargeable battery can be provided. Furthermore, according to embodiments, a positive electrode capable of improving the quality and yield of the positive electrode plate, a method for manufacturing the same, and an all-solid-state rechargeable battery can be provided. Attached Figure Description

[0013] Figure 1 and Figure 2 A cross-sectional view of an all-solid-state rechargeable battery according to an embodiment is shown for illustrative purposes.

[0014] Figure 3 A schematic diagram of the positive electrode active material layer of an all-solid-state rechargeable battery cell according to a comparative example is shown for illustrative purposes.

[0015] Figure 4 This is a schematic diagram illustrating the aggregation trend of carbon nanoparticles according to an embodiment.

[0016] Figure 5 This is a schematic diagram illustrating the positive electrode active material layer of an all-solid-state rechargeable battery according to an embodiment.

[0017] Figure 6 This is a cross-sectional image of the positive electrode active material layer prepared in Comparative Example 1, taken using a scanning electron microscope (SEM) at 10,000x magnification.

[0018] Figure 7 A graph showing the viscosity change of the positive electrode active material slurry obtained from Comparative Examples 1 and 2, and Examples 1 and 2, according to the shear rate (1 / s).

[0019] Figure 8 To show the magnified Figure 7 An enlarged view of the rectangular portion.

[0020] Figure 9 The graph shows the results of the measurement of electronic conductivity and ionic conductivity of the positive electrodes obtained from Comparative Examples 1 to 3, as well as Examples 1 and 2, by electrochemical impedance spectroscopy (EIS).

[0021] Figure 10 A graph showing the change in discharge capacity of the all-solid-state rechargeable battery cells manufactured in Comparative Example 1 and Examples 1 and 2.

[0022] Figure 11 A graph showing the measurement results of the average discharge voltage of the all-solid-state rechargeable battery cells manufactured in Comparative Example 1 and Examples 1 and 2. Detailed Implementation

[0023] Embodiments of the invention will now be described in detail. However, this is presented by way of example, and the invention is not limited thereto; rather, it is defined only by the scope of the claims described later.

[0024] As used herein, unless otherwise specifically defined, 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 an intervening element present.

[0025] In this specification, unless otherwise indicated, singular expressions may include plural expressions. Additionally, unless otherwise indicated, “A or B” may mean “including A, including B, or including both A and B”.

[0026] In this specification, "combination thereof" may refer to mixtures of components, laminates, composites, copolymers, alloys, blends, reaction products, etc.

[0027] In this specification, unless otherwise specified, particle size may refer to average particle size. Alternatively, particle size may refer to average particle size (D50), which means the diameter of particles having a cumulative volume of 50 vol% in the particle size distribution. Average particle size (D50) can be measured by methods well known to those skilled in the art, for example, by a particle size analyzer or by transmission electron microscopy or scanning electron microscopy images. Optionally, data analysis is performed using a dynamic light scattering measurement device, and the number of particles for each particle size range is counted. Thus, the average particle size (D50) value can be readily obtained by calculation. Optionally, it can be measured using laser diffraction. When measured by laser diffraction, more specifically, the particles to be measured are dispersed in a dispersion medium and then introduced into a commercially available laser diffraction particle size measurement device (e.g., Microtrac MT 3000), and irradiated with ultrasonic waves of approximately 28 kHz at a power of 60 W to calculate the average particle size (D50) based on 50% of the particle size distribution in the measurement device.

[0028] positive electrode

[0029] In one embodiment, the positive electrode includes: a positive electrode current collector; and a positive electrode active material layer on the positive electrode current collector, wherein the positive electrode active material layer includes a positive electrode active material, a sulfide-based solid electrolyte, a binder, and a conductive material, the conductive material including carbon nanotubes and carbon nanoparticles, and including carbon nanotubes in an amount of 40 wt% to 90 wt% and carbon nanoparticles in an amount of 100 wt% to 100 wt% of the total amount of carbon nanotubes and carbon nanoparticles.

[0030] The positive electrode active material layer comprises the positive electrode active material, a sulfide-based solid electrolyte, a binder, and a conductive material. That is, the positive electrode slurry of an all-solid-state rechargeable battery is composed of various inorganic and organic materials (such as the positive electrode active material, solid electrolyte, conductive material, and binder). Among the solid electrolytes, sulfide-based solid electrolytes with excellent ionic conductivity are used; however, sulfide-based solid electrolytes are prone to degradation due to air, moisture, polar solvents, or high temperatures. Therefore, when using sulfide-based solid electrolytes, low-polarity solvents are used instead of polar solvents, considering reactivity. Carbon nanotubes are used as conductive materials due to their excellent electrochemical properties; however, due to their strong interactions, they tend to aggregate in solution. This aggregation of carbon nanotubes increases the viscosity of the positive electrode slurry, thereby reducing the slurry's storage stability and the production quality of the electrode plate, and also reducing conductivity. Correspondingly, there are methods to improve the phase stability of slurries by increasing the dispersibility of carbon nanotubes themselves, but these methods are limited by the low dispersibility of carbon nanotubes in low-polarity solvents chosen in consideration of the reactivity of sulfide-based solid electrolytes.

[0031] In the implementation, we propose a positive electrode that can improve the dispersibility of the slurry and the conductivity of the battery, as well as improve the quality and yield of the electrode plate.

[0032] conductive materials

[0033] The positive electrode active material layer includes carbon nanotubes and carbon nanoparticles as conductive materials. Figure 3 A schematic diagram of the positive electrode active material layer of the all-solid-state rechargeable battery according to a comparative example is shown, illustrating a case where the positive electrode active material layer includes only carbon nanotubes as conductive materials and does not include carbon nanoparticles. Furthermore, Figure 5 A schematic diagram showing the positive electrode active material layer of an all-solid-state rechargeable battery according to an embodiment is provided. Figure 3 As shown, ions move through the solid electrolyte 2 to ensure pathways for ion conduction, and the connectivity between the positive electrode active material 1 and the carbon nanotubes 11, which serve as conductive materials, is ensured by the carbon nanotubes 11 to ensure pathways for electron conduction. However, carbon nanotubes can be dispersed non-uniformly within the positive electrode active material layer, resulting in somewhat low conductivity. Meanwhile, carbon nanoparticles (such as carbon black) can be more advantageous than carbon nanotubes in terms of dispersibility. Accordingly, in embodiments, by mixing carbon nanoparticles (such as carbon black) with carbon nanotubes and using them as conductive materials to assist in the positive electrode, the network of electron and ion conduction can be improved without hindering the connectivity of the solid electrolyte. Therefore, as... Figure 5 As shown, by using carbon nanoparticles 12 as a conductive material in addition to carbon nanotubes 11 in the positive electrode active material layer, and... Figure 3 Compared to the previous method, this ensures a more uniform and denser path for electron conduction.

[0034] For example, carbon nanotubes can be single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), or combinations thereof. Optionally, carbon nanotubes can be short-length CNTs (S-carbon nanotubes), long-length CNTs (L-carbon nanotubes), or combinations thereof, and particularly, L-carbon nanotubes. When such carbon nanotubes are used as conductive materials in the positive electrode active material layer, the electronic network can be improved by ensuring the connectivity between the positive electrode active material and the conductive material distributed between the solid electrolyte.

[0035] Carbon nanoparticles can be, for example, carbon black, acetylene black, Ketjen black, superconducting acetylene black, or combinations thereof. When using carbon nanoparticles, compared to using carbon nanotubes alone, it is not only advantageous in ensuring the dispersibility of the slurry, but also easier in terms of manufacturing processes because it eliminates the need to prepare the slurry in a pre-dispersed form.

[0036] In the positive electrode active material layer, carbon nanotubes are included in an amount of 40 wt% to 90 wt%, and carbon nanoparticles are included in an amount of 10 wt% to 60 wt%, based on a total amount of 100 wt% of carbon nanotubes and carbon nanoparticles. Within these ranges, by improving the dispersibility in the positive electrode slurry while maintaining a balance between electronic and ionic conduction, the resistance of the electrode plate can be reduced, the performance of the battery cell can be improved, and structural stability can also be promoted.

[0037] According to an embodiment, in the positive electrode active material layer, carbon nanoparticles can form aggregates by connecting primary particles to each other. Optionally, the primary particles and aggregates can be aggregated together to form clusters. In this case, the cluster-shaped units of the carbon nanoparticles in the positive electrode active material layer can be extended from nanometer units to micrometer units, thereby synergistically improving electronic conductivity and ionic conductivity.

[0038] Figure 4 A schematic diagram illustrating the aggregation trend of carbon nanoparticles in the positive electrode active material layer according to an embodiment. In the positive electrode active material layer, carbon nanoparticles can be aggregated by, for example... Figure 4 The primary particles shown in A are interconnected to form a structure like... Figure 4 The aggregates shown in B. Additionally, primary particles and aggregates can aggregate together to form, as in... Figure 4 The agglomerate shown in C. Here, the agglomerate can be an agglomerate in which primary particles and aggregates are clustered together by a weaker attraction than that of aggregates. In this case, connecting the carbon nanoparticles in the positive electrode active material layer ensures a more uniform and dense pathway for electron conduction, and improves the electron conduction network throughout the entire positive electrode active material layer.

[0039] According to the embodiments, the average particle size (D50) of the primary particles of carbon nanoparticles can be 1 nm to 50 nm, for example 3 nm to 45 nm, 5 nm to 43 nm, or 10 nm to 40 nm. Within this range, electronic conductivity and ionic conductivity can be improved in a coordinated manner without hindering the connectivity of the solid electrolyte.

[0040] Based on 100 wt% of the positive electrode active material layer, the positive electrode active material layer may include 0.01 wt% to 5 wt% of conductive material.

[0041] According to an embodiment, the positive electrode active material layer may further include a low-polarity solvent having a polarity index (PI) of 0.074 to 0.281. When such a low-polarity solvent is used, it does not increase the cell resistance due to its low reactivity with sulfide-based solid electrolytes, thus improving battery performance. In this document, polarity index may refer to the relative polarity index when the polarity index of water is set to 9.0, and polarity index values ​​disclosed in commonly known literature may be used.

[0042] In embodiments, the low-polarity solvent may have a polarity index of 0.074 to 0.281 and is selected from pyridine solvents, benzene solvents, acetate solvents, ketone solvents, ester solvents, ether solvents, carbonate solvents, acrylate solvents, aldehyde solvents, piperidine solvents, sulfite solvents, alkyl solvents, formate solvents, or combinations thereof. Pyridine solvents are solvents containing a pyridine ring in their structure, and examples include 2,6-di-tert-butylpyridine, 2-vinylpyridine, acetylpyridine, 2-chloropyridine, etc. Benzene solvents are solvents containing a benzene ring in their structure, and examples include bromobenzene, p-chlorotoluene, benzyl dichloroethylene, N,N-dimethylamine, styrene oxide, methoxybenzene (anisole), butyl benzoate, benzaldehyde, phenylacetonitrile, etc. Acetate solvents are solvents containing an acetate in their structure, and examples include ethyl chloroacetate, 2-ethylhexyl acetate, etc. Ketone solvents are solvents whose structure contains a ketone group, and examples include methyl isopentyl ketone, di-tert-butyl ketone, ethylpentyl ketone, diisobutyl ketone, cyclopentanone, 4-heptanone, 5-methyl-3-heptanone, etc. Ester solvents are solvents whose structure contains an ester group, and examples include methyl lauryl acid, n-butyl propionate, diketene, methyl oleate, etc. Ether solvents are solvents whose structure contains an ether group, and examples include 1,8-cineole, etc. Carbonate solvents are solvents whose structure contains a carbonate group, and examples include diethyl carbonate, diethyl carbonate, etc. Acrylate solvents include n-butyl acrylate, n-butyl methacrylate, isobutyl methacrylate, etc. Aldehyde solvents are solvents whose structure contains an aldehyde group, and examples include ethylhexanal, etc. Piperidine solvents are solvents whose structure contains piperidine, and examples include 1-formylpiperidine, etc. Sulfite solvents are solvents whose structure contains a sulfite group, and examples include vinyl sulfite. Alkyl solvents are solvents whose structure contains an alkyl group, and examples include 1,2,3-trichloropropane, chlorocyclohexane, etc. Formate solvents are solvents whose structure contains a formate group, and examples include amyl formate, etc.

[0043] For example, based on 100 wt% of the positive electrode active material layer, the positive electrode active material layer may include a low-polarity solvent in an amount of 500 ppm or less. Examples of such low-polarity solvents include 2,6-di-tert-butylpyridine, bromobenzene, benzyl chloride, p-chlorotoluene, benzyl dichloroethylene, o-dichlorobenzene, N,N-dimethylamine, benzyl bromide, 1,2,3-trichloropropane, methoxybenzene (anisole), ethoxybenzene, 2-vinylpyridine, chlorocyclohexane, methyl lauryl, ethyl chloroacetate, 2-ethylhexyl acetate, o-chlorobenzyl chloride, diethyl carbonate, ethyl trichloroacetate, n-butyl acrylate, methyl isopentyl ketone, di-tert-butyl ketone, styrene oxide, diketene, ethylhexanal, n-butyl methacrylate, diisopropyl ketone, and sec-pentyl acetate. Esters, methyl amyl acetate, n-butyl propionate, n-pentyl propionate, n-pentyl propionate, 1-formylpiperidine, butyl benzoate, 4-heptanone, 1,8-cineole, isobutyl methacrylate, phenylacetonitrile, methyl benzoate, isobutyl isobutyrate, octyl acetate, acetylpyridine, methyl oleate, methyl pentamethylene ketone, 5-methyl-3-heptanone, pentyl formate, diisobutyl ketone, ethyl pentamethylene sulfite, dibutyl ketone, cyclopentanone, 2-chloropyridine, ethyl phenylacetate, diethyl carbonate, benzaldehyde, isoamyl acetate, methyl hexyl ketone, ethyl benzoate, phenyl acetate, or combinations thereof. When using the aforementioned low-polarity solvents, an appropriate viscosity of the slurry can be achieved, ensuring uniform coating on the electrode plates. Furthermore, without increasing the individual cell resistance due to the low reactivity with sulfide-based solid electrolytes, it can contribute to improved conductivity and battery performance.

[0044] Positive electrode active material

[0045] As the positive electrode active material, compounds capable of reversibly inserting and deintercalating lithium (lithiation intercalation compounds) can be used. For example, at least one of the composite oxides of lithium and metals selected from cobalt, manganese, nickel and combinations thereof can be used.

[0046] The composite oxide can be a lithium transition metal composite oxide, and specific examples include lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, cobalt-free nickel manganese oxides, lithium-rich layered oxides, or combinations thereof.

[0047] As an example, the positive electrode active material can be a high-nickel positive electrode active material, wherein the nickel content in the lithium transition metal composite oxide, based on 100 mol% of metals other than lithium, is greater than or equal to 80 mol%. In the high-nickel positive electrode active material, the nickel content, based on 100 mol% of metals other than lithium, 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 can be less than or equal to 99 mol%. High-nickel positive electrode active materials can achieve high capacity and therefore can be applied to high-capacity, high-density rechargeable lithium batteries.

[0048] 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); Li a 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 Mn1-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); Li a FePO4 (0.90≤a≤1.8).

[0049] In the above chemical formulas, A represents Ni, Co, Mn, or a combination thereof; X represents Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D represents O, F, S, P, or a combination thereof; G represents Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q represents Ti, Mo, Mn, or a combination thereof; Z represents Cr, V, Fe, Sc, Y, or a combination thereof; and L... 1 It is Mn, Al, or a combination thereof.

[0050] The positive electrode active material may include, for example, lithium nickel oxides represented by chemical formula 1, lithium cobalt oxides represented by chemical formula 2, lithium iron phosphate compounds represented by chemical formula 3, cobalt-free lithium nickel manganese oxides represented by chemical formula 4, or combinations thereof.

[0051] [Chemical Formula 1]

[0052] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0053] In chemical formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, 0≤z1≤0.7, 0.9≤x1+y1+z1≤1.1 and 0≤b1≤0.1, M 1 and M 2 Each element is independently selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zr, or combinations thereof, and X is selected from F, P, S, or combinations thereof.

[0054] In Chemical Formula 1, 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.

[0055] [Chemical Formula 2]

[0056] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0057] In Chemical Formula 2, 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 is an element selected from Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, Zr, or a combination thereof, and X is an element selected from F, P, S, or a combination thereof.

[0058] [Chemical Formula 3]

[0059] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0060] In Chemical Formula 3, 0.9 ≤ a3 ≤ 1.8, 0.6 ≤ x3 ≤ 1, 0 ≤ y3 ≤ 0.4, and 0 ≤ b3 ≤ 0.1, M 4 is an element selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, Zr, or a combination thereof, and X is an element selected from F, P, S, or a combination thereof.

[0061] [Chemical Formula 4]

[0062] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0063] In Chemical Formula 4, 0.9 ≤ a2 ≤ 1.8, 0.8 ≤ x4 < 1, 0 < y4 ≤ 0.2, 0 ≤ z4 ≤ 0.2, 0.9 ≤ x4 + y4 + z4 ≤ 1.1, and 0 ≤ b4 ≤ 0.1, M 5X is an element selected from Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zr or combinations thereof, and X is an element selected from F, P, S or combinations thereof.

[0064] The average particle size (D50) of the positive electrode active material can be 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 small particles with an average particle size (D50) of 1 μm to 9 μm and large particles with an average particle size (D50) of 10 μm to 25 μm. Positive electrode active materials with this particle size range can be coherently mixed with other components within the positive electrode active material layer, and high capacity and high energy density can be achieved. In this document, average particle size refers to the diameter (D50) of particles with a cumulative volume of 50 vol% obtained by randomly measuring the size (diameter or length of the major axis) of approximately 20 particles in a scanning electron microscope image of the positive electrode active material.

[0065] The positive electrode active material can take the form of secondary particles made by aggregating multiple primary particles or as a single particle. In addition, the positive electrode active material can have a spherical or near-spherical shape, or it can have a polyhedral or irregular shape.

[0066] Simultaneously, the positive electrode active material may include a buffer layer on the surface of the particles. The buffer layer can be expressed 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 may be one or more elements selected from, for example, Al, B, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ta, V, W, Zr, and combinations thereof. Lithium-metal oxides improve the performance of the positive electrode active material by promoting lithium-ion movement and electron conduction, and are beneficial for reducing the interfacial resistance between the positive electrode active material and the solid electrolyte particles.

[0067] Based on 100 wt% of the positive electrode active material layer, the positive electrode active material can be included in an amount of 55 wt% to 95 wt%, for example 65 wt% to 94 wt% or 75 wt% to 91 wt%.

[0068] adhesive

[0069] The binder is used to ensure good adhesion between the positive electrode active material particles and also to ensure good adhesion between the positive electrode active material and the current collector. For example, the binder may include, but is not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, nylon, etc. Representative examples include: the binder may be a fluorinated binder, such as polyvinyl fluoride, polytetrafluoroethylene, and polyvinylidene fluoride.

[0070] Based on 100 wt% of the positive electrode active material layer, a binder may be included in an amount of 0.1 wt% to 5 wt%, for example 0.1 wt% to 3 wt% or 0.5 wt% to 2 wt%.

[0071] solid electrolyte

[0072] The positive electrode active material layer includes a sulfide-based solid electrolyte. For example, the sulfide-based solid electrolyte may include a sulfide-germanium sulfide. Optionally, the positive electrode active material layer may further include other solid electrolytes besides the aforementioned sulfide-based solid electrolytes. For example, the positive electrode active material layer may further include oxide-based solid electrolytes, halide-based solid electrolytes, or combinations thereof. Meanwhile, the description of the solid electrolyte layer below also applies to the aforementioned sulfide-based solid electrolytes and other solid electrolytes.

[0073] Based on 100 wt% of the positive electrode active material layer, the solid electrolyte may be included in amounts of 0.1 wt% to 35 wt%, for example 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%.

[0074] In the positive electrode active material layer, based on 100 wt% of the total amount of positive electrode active material and solid electrolyte, it may include 65 wt% to 99 wt% of positive electrode active material and 1 wt% to 35 wt% of solid electrolyte, for example, it may include 80 wt% to 90 wt% of positive electrode active material and 10 wt% to 20 wt% of solid electrolyte. If the solid electrolyte is included in the positive electrode in this amount, the efficiency and cycle life characteristics of the all-solid-state rechargeable battery can be improved without reducing the capacity.

[0075] Other conductive materials

[0076] In addition to the aforementioned carbon nanotubes and carbon nanoparticles, the positive electrode active material layer may optionally further include other conductive materials. The conductive material is used to impart conductivity to the electrode, and any electronically conductive material can be used, as long as it does not cause a chemical change in the constructed battery. For example, conductive materials may include: carbon-based materials such as natural graphite, artificial graphite, carbon fibers, and carbon nanofibers; metallic materials containing copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0077] Based on 100 wt% of the positive electrode active material layer, the amount of conductive material in the positive electrode active material layer can be 0.01 wt%~5 wt% or 0.05 wt%~3 wt%, 0.08 wt%~2 wt%, 0.1 wt%~2 wt% or 0.2 wt%~1 wt%.

[0078] Aluminum foil can be used as the positive electrode current collector, but it is not limited to this.

[0079] Methods for manufacturing positive electrodes

[0080] In another embodiment, a method for manufacturing a positive electrode is provided, the method comprising: dry mixing a positive electrode active material, a sulfide-based solid electrolyte, and carbon nanoparticles; and adding a binder and carbon nanotubes to the dry-mixed mixture and mixing to obtain a positive electrode active material slurry, wherein carbon nanotubes are added in an amount of 40 wt% to 90 wt% and carbon nanoparticles in an amount of 100 wt% to 100 wt% of the total amount of carbon nanotubes and carbon nanoparticles. The above description pertains to a method for manufacturing a positive electrode according to an embodiment, and descriptions repeating the foregoing will be omitted below; the manufacturing process of the positive electrode according to the embodiment will be described in detail.

[0081] According to the embodiments, dry mixing can be carried out by adding carbon nanoparticles in powder form to a dry mixture of positive electrode active material and sulfide-based solid electrolyte and mixing them.

[0082] The addition of binder and carbon nanotubes can be carried out by adding a mixed solution including binder and carbon nanotubes to the dry-mixed mixture, and the aforementioned low-polarity solvent used for the positive electrode can be used as the solvent for the mixed solution.

[0083] Optionally, the addition of the binder and carbon nanotubes can be carried out by adding a binder solution comprising the binder and a first low-polarity solvent, and a carbon nanotube solution comprising carbon nanotubes and a second low-polarity solvent, to the dry-mixed mixture and mixing.

[0084] Alternatively, the binder solution can be added to the dry-mixed mixture first and mixed, and then the carbon nanotube solution can be added and mixed.

[0085] The first and second low-polarity solvents may be, for example, low-polarity solvents having a polarity index of 0.074 to 0.281, and the description of the low-polarity solvent in the positive electrode described above is equally applicable to this low-polarity solvent.

[0086] The first low-polarity solvent and the second low-polarity solvent may be the same as each other or may be different from each other.

[0087] Next, the positive electrode active material slurry can be coated onto the aforementioned positive electrode current collector. At this time, any method known in the art can be used for coating without limitation. For example, coating equipment (scalpel coater, comma coater, gate coater, slot coater, gravure coater, spray coater, etc.) can be used for coating. The same applies to the positive electrode described above for the positive electrode current collector.

[0088] After the positive electrode active material slurry is coated, the coated positive electrode active material slurry can be dried and rolled to form a positive electrode active material layer on the positive electrode current collector. In this document, the conditions used for drying and rolling are as generally known in the art.

[0089] All-solid-state rechargeable batteries

[0090] In another embodiment, an all-solid-state rechargeable battery is provided, comprising: the aforementioned positive electrode; a negative electrode; and a solid electrolyte layer between the positive and negative electrodes. Because the all-solid-state rechargeable battery includes the positive electrode according to the above embodiment, a balance between electron and ion conduction is ensured, reducing the resistance of the electrode plates and improving the performance of individual battery cells, while effectively ensuring structural stability.

[0091] The following text will omit descriptions that are repeated above and will refer to... Figure 1 and Figure 2 The components of the all-solid-state rechargeable battery according to the embodiments are described in more detail.

[0092] All-solid-state rechargeable batteries can also be expressed as all-solid-state batteries or all-solid-state rechargeable lithium batteries.

[0093] Figure 1 This is a cross-sectional view of an all-solid-state rechargeable battery according to an embodiment. (Reference) Figure 1The all-solid-state rechargeable battery 100 may have an electrode assembly, comprising a negative electrode 400 including a negative electrode current collector 401 and a negative electrode active material layer 403, a solid electrolyte layer 300, and a positive electrode 200 including a positive electrode active material layer 203 and a positive electrode current collector 201, stacked within a battery housing. The all-solid-state rechargeable battery 100 may further include at least one elastic layer 500 on the outer side of at least one of the positive electrode 200 and the negative electrode 400. Although an electrode assembly including the negative electrode 400, the solid electrolyte layer 300, and the positive electrode 200 is shown... Figure 1 However, all-solid-state rechargeable batteries can also be manufactured by stacking two or more electrode components.

[0094] negative electrode

[0095] The negative electrode for an all-solid-state rechargeable battery includes a negative electrode current collector and a negative electrode active material layer on the negative electrode 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 conductive material.

[0096] The negative electrode active material may include materials capable of reversibly inserting / deintercalating lithium ions, lithium metal, lithium metal alloys, materials capable of doping and dedoping lithium, or transition metal oxides.

[0097] Materials capable of reversibly inserting / deintercalating lithium ions can include carbon-based negative electrode active materials, such as crystalline carbon, amorphous carbon, or combinations thereof. Examples of crystalline carbon include graphite, such as amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, and examples of amorphous carbon include soft or hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0098] Lithium metal alloys may include alloys of lithium with metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0099] Materials capable of doping and dedoping with lithium can include Si-based or Sn-based negative electrode active materials. Si-based negative electrode active materials can include silicon, silicon-carbon composites, and SiO₂. xwhere \(0 < x < 2\), a Si-Q alloy (where Q is an element selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, transition metals, rare earth elements, or a combination thereof, and is not Si), or a combination thereof. The Sn-based negative electrode active material may include Sn, \(SnO_2\), a Sn-R alloy (where R is an element selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, transition metals, rare earth elements, or a combination thereof, and is not Sn), or a combination thereof. The element Q and the element R may be one or a combination selected from 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.

[0100] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to an embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, it may include secondary particles (cores) in which primary silicon particles are assembled and an amorphous carbon coating (shell) on the surface of the secondary particles. Amorphous carbon may also be present between the primary silicon particles. For example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in the amorphous carbon matrix.

[0101] Optionally, the silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles and an amorphous carbon coating on the surface of the core.

[0102] The Si-based negative electrode active material or the Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material.

[0103] Based on the total weight of the negative electrode active material layer, the amount of the negative electrode active material in the negative electrode active material layer may be 95 wt% - 99 wt%.

[0104] In an embodiment, the negative electrode active material layer further includes a binder and may optionally further include a conductive material. Based on the total weight of the negative electrode active material layer, the amount of the binder in the negative electrode active material layer may be 1 wt% - 5 wt%. Additionally, when further including a conductive material, the negative electrode active material layer may include 90 wt% - 98 wt% of the negative electrode active material, 1 wt% - 5 wt% of the binder, and 1 wt% - 5 wt% of the conductive material.

[0105] 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 non-aqueous binders, aqueous binders, dry binders, or combinations thereof.

[0106] Examples of non-aqueous adhesives include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, or combinations thereof.

[0107] The waterborne adhesive may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepoxychloropropane, polyphosphazene, poly(meth)acrylonitrile, ethylene-propylene-diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0108] When an aqueous binder is used as a negative electrode binder, a viscosity-imparting tackifier may be used in conjunction, and the tackifier may include, for example, a cellulose compound. As a cellulose compound, one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, or their alkali metal salts may be mixed and used. As an alkali metal, Na, K, or Li may be used. The amount of such tackifier used may be 0.1 to 3 parts by weight based on 100 parts by weight of the negative electrode active material.

[0109] Dry adhesives are polymeric materials capable of being fibrous, such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or combinations thereof.

[0110] Conductive materials are used to impart conductivity to electrodes, and any electronically conductive material can be used as long as it does not cause a chemical change in the battery in which it is constructed. Specific examples include: carbon-based materials, such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials in the form of metal powders or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0111] The negative electrode current collector can be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof.

[0112] As another example, the negative electrode for an all-solid-state rechargeable battery can be a deposition-type negative electrode. A deposition-type negative electrode does not include a negative electrode active material during battery assembly, but refers to a negative electrode in which lithium metal or the like is deposited or electrodeposited on the negative electrode during battery charging, and this serves as the negative electrode active material.

[0113] Figure 2 This is a schematic cross-sectional view of an all-solid-state rechargeable battery including a deposited negative electrode. (Reference) Figure 2 The deposited negative electrode 400' may include a negative electrode current collector 401 and a negative electrode coating 405 on the negative electrode current collector. In an all-solid-state rechargeable battery having such a deposited negative electrode 400', initial charging begins in a state where no negative electrode active material is present, and during charging, lithium metal is deposited or electrodeposited between the negative electrode current collector 401 and the negative electrode coating 405, or deposited or electrodeposited on the negative electrode coating 405 to form a lithium metal layer 404, which can be used as a negative electrode active material. Accordingly, in an all-solid-state rechargeable battery in which one or more charges have been performed, the deposited negative electrode 400' may include, for example, a negative electrode current collector 401, a lithium metal layer 404 on the negative electrode current collector, and a negative electrode coating 405 on the metal layer. The lithium metal layer 404 refers to a layer in which lithium metal or the like is deposited during the battery charging process, and may be referred to as a metal layer, lithium layer, lithium electrodeposition layer, or negative electrode active material layer.

[0114] The negative electrode coating 405 may also be referred to as a lithium electrode deposition induction layer or a negative electrode catalyst layer, and may include metals, carbon-containing materials or combinations thereof.

[0115] The metal may be a lithium-loving metal, and may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or combinations thereof, and may consist of one of these or an alloy of several of them. When the metal exists in particulate form, its average particle size (D50) may be less than or equal to about 4 μm, for example, 10 nm to 4 μm.

[0116] Carbonaceous 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. As an example, carbonaceous materials may refer to amorphous carbon.

[0117] When the negative electrode coating 405 comprises both metal and carbonaceous materials, the mixing ratio of the metal and carbonaceous materials can be, for example, a weight ratio of 1:10 to 2:1. In this case, lithium metal deposition can be effectively promoted, and the characteristics of the all-solid-state rechargeable battery can be improved. The negative electrode coating 405 may comprise, for example, a carbonaceous material on which a catalyst metal is loaded, or may comprise a mixture of metal particles and carbonaceous material particles.

[0118] The negative electrode coating 405 may include, for example, a lithium-loving metal and amorphous carbon, and in this case, lithium metal deposition may be effectively promoted. As a specific example, the negative electrode coating 405 may include a composite in the form of a lithium-loving metal supported on amorphous carbon.

[0119] The negative electrode coating 405 may further include a binder, and the binder may be, for example, a conductive binder. Additionally, the negative electrode coating 405 may further include fillers, dispersants, ion-conducting materials, etc., as general additives.

[0120] 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.

[0121] As an example, the deposited negative electrode 400' may further include a thin film on the surface of the negative electrode current collector (i.e., between the negative electrode 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 be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and may consist of one of these or an alloy of several of them. The thin film may further planarize the deposited form of the lithium metal layer 404 and further improve the characteristics of the all-solid-state rechargeable battery. The thin film may be formed, for example, by methods such as vacuum deposition, sputtering, or electroplating. The thickness of the thin film may be, for example, 1 nm to 500 nm.

[0122] The lithium metal layer 404 may comprise lithium metal or a lithium metal alloy. The lithium metal alloy may be, for example, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, or a Li-Si alloy.

[0123] The thickness of the lithium metal layer 404 can be 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 100 μm, or 1 μm to 50 μm. If the thickness of the lithium metal layer 404 is too thin, it will be difficult to function as a lithium storage tank, and if it is too thick, the battery volume will increase and the performance may decrease.

[0124] When this deposition-type negative electrode is applied, the negative electrode coating 405 can be used to protect the lithium metal layer 404 and suppress the deposition and growth of lithium dendrites. Accordingly, short circuits and capacity degradation in the all-solid-state battery are suppressed, and cycle life characteristics are improved.

[0125] solid electrolyte layer

[0126] The solid electrolyte layer includes a solid electrolyte. The solid electrolyte may be of the type of inorganic solid electrolyte, and may include, for example, sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, or combinations thereof. According to embodiments, the solid electrolyte layer may include a sulfide solid electrolyte.

[0127] Sulfide solid electrolytes

[0128] Sulfide solid electrolytes may include, for example, 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 (where m and n are integers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Lithium Phosphate (Li3PO4), Li2S-SiS2-Li p MO q (where p and q are integers, and M is P, Si, Ge, B, Al, Ga, or In) or a combination thereof.

[0129] Such 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 by heat treatment. Within the above mixing ratio range, sulfide-based solid electrolytes with excellent ionic conductivity can be produced. In this paper, other components such as SiS₂, GeS₂, and B₂S₃ can be added to further improve the ionic conductivity.

[0130] Mechanical grinding or solution processing can be used as mixing methods for sulfur-containing raw materials used in the preparation of sulfide-based solid electrolytes. Mechanical grinding involves placing the raw materials in a ball mill reactor and vigorously stirring them to break them down into microparticles. Solution processing involves mixing the raw materials in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, heat treatment after mixing can make the solid electrolyte crystals more stable and improve ionic conductivity. For example, sulfide-based solid electrolytes can be prepared by mixing sulfur-containing raw materials and subjecting them to two or more heat treatments. In this case, sulfide-based solid electrolytes with high ionic conductivity and stability can be prepared.

[0131] According to the embodiments, the sulfide-based solid electrolyte can be prepared, for example, by a first heat treatment of mixing sulfur-containing raw materials and sintering at 120°C to 350°C, and a second heat treatment of mixing the results of the first heat treatment and sintering 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 be carried out for 1 to 10 hours, and the second heat treatment for 5 to 20 hours. The first heat treatment can grind fine raw materials, and the second heat treatment can synthesize the final solid electrolyte. Through two or more such heat treatments, a sulfide-based solid electrolyte with high ionic conductivity and high performance can be obtained, and this solid electrolyte is suitable for large-scale production. The temperature of the first heat treatment can be, for example, 150°C to 330°C or 200°C to 300°C, and the temperature of the second heat treatment can be, for example, 380°C to 700°C or 400°C to 600°C.

[0132] As an example, sulfide solid electrolytes may include argillium sulfide-type sulfides. Argyranium sulfide-type solid electrolytes have a content close to 10. -4 ~10 -2 High ionic conductivity in the range of S / cm (which is the ionic conductivity of a typical liquid electrolyte at room temperature), and the ability to form a tight bond between the positive electrode active material and the solid electrolyte without causing a decrease in ionic conductivity; furthermore, a tight interface can be formed between the electrode layer and the solid electrolyte layer. All-solid-state rechargeable batteries, including those with sulfide solid electrolytes of the sulfide type, can have improved battery performance, such as rate performance, coulombic efficiency, and cycle life characteristics.

[0133] Sulfide solid electrolytes of the sulfide type can include, for example, compounds represented by chemical formula 11.

[0134] [Chemical Formula 11]

[0135] (Li a M 1 b M 2 c (P) d M 3 e (S) f M 4 g )X h

[0136] In chemical formula 11, 4 ≤ a ≤ 8, M 1 For Mg, Cu, Ag or combinations thereof, 0 ≤ b < 0.5, M 2 For Na, K, or combinations thereof, 0 ≤ c < 0.5, M 3is 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.

[0137] For example, in Chemical Formula 11, it may essentially include a halide element (X), and in this case, it can be expressed as 0 < h ≤ 2. For example, in Chemical Formula 11, it may essentially include element M 1 , and in this case, it can be expressed as 0 < b < 0.5. In Chemical Formula 11, M 3 can be understood as the element substituted at the P position and can be 0 < e < 1. In Chemical Formula 11, M 4 can be the element substituted at the S position and can be, for example, 0 < g < 2, and f as the proportion of S can be, for example, 3 ≤ f ≤ 7. When M 4 is SO n , SO n can be, for example, S4O6, S3O6, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, SO4 or SO5, and can be, for example, SO4.

[0138] For example, in Chemical Formula 11, it can satisfy a + b + c + h = 7, d + e = 1 and f + g + h = 6.

[0139] As a specific example, the argyrodite-type sulfide solid electrolyte particles may include Li3PS4, 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 Cu0.06 )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.

[0140] A sulfide solid electrolyte of the sulfide type can be prepared, for example, by mixing lithium sulfide, 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 steps. As an example herein, the preparation of the sulfide solid electrolyte may include: a first heat treatment of mixing the raw materials and sintering at 120°C to 350°C, and a second heat treatment of mixing the result of the first heat treatment again and sintering at 350°C to 800°C.

[0141] Sulfide-based solid electrolytes can be in the form of particles, and the average particle size (D50) can be, for example, 0.1 μm to 5.0 μm or 0.1 μm to 3.0 μm, and can be small particles of 0.1 μm to 1.9 μm or large particles of 2.0 μm to 5.0 μm. Sulfide-based solid electrolyte particles can be a mixture of small particles with an average particle size of 0.1 μm to 1.9 μm and large particles with an average particle size of 2.0 μm to 5.0 μm. The average particle size of sulfide-based solid electrolyte particles can be measured using electron microscopy images, and for example, can be obtained by measuring the size (diameter or length of the major axis) of about 20 particles in a scanning electron microscope image to obtain the particle size distribution, and then calculating the D50 from there.

[0142] Oxide solid electrolytes

[0143] 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 yP 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, 0 < x < 2, 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), lanthanum lithium titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3), Li2O, LiAlO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2 - type ceramics, garnet - type ceramics Li 3+ x La3M2O 12 (where M is Te, Nb or Zr; and x is an integer from 1 to 10) or a mixture thereof.

[0144] Halogenated solid electrolytes

[0145] The solid electrolyte layer may further include, for example, halide - type solid electrolytes. Halide - type solid electrolytes contain a halogen element as a main component, which may mean that the ratio of the halogen element to all the elements constituting the solid electrolyte is greater than or equal to 50 mol%, greater than or equal to 70 mol%, greater than or equal to 90 mol% or 100 mol%. As an example, the halide - type solid electrolyte may not contain a sulfur element.

[0146] Halogenated solid electrolytes may contain lithium, metals other than lithium, and halogens. Metals 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 combinations thereof. Halogens may be F, Cl, Br, I, or combinations thereof, and as an example, may be Cl, Br, or combinations thereof. Halogenated solid electrolytes may, for example, be composed of 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 combinations thereof, and X is F, Cl, Br, I or combinations thereof, and 2≤a≤3) represents this. Halogenated solid electrolytes 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 Zr 0.5 Cl6, Li3YBr6, Li3YCl6, Li3YBr2Cl4, Li3YbCl6, Li 2.6 Hf 0.4 Yb 0.6 Cl6 or combinations thereof, but not limited to these.

[0147] adhesive

[0148] The solid electrolyte layer may further include an adhesive. The 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, poly(meth)acrylate, polyacrylonitrile, polystyrene, polyurethane, copolymers thereof, or combinations thereof.

[0149] Based on 100 wt% of the solid electrolyte layer, a binder may be included in amounts of 0.1 wt% to 3 wt%, for example 0.5 wt% to 2 wt%, or 0.5 wt% to 1.5 wt%. When a binder is included within the above ranges, the battery's durability and reliability can be improved because the components in the solid electrolyte layer can be well combined without reducing the ionic conductivity of the solid electrolyte.

[0150] Other components

[0151] The solid electrolyte layer may optionally further comprise an alkali metal salt and / or an ionic liquid and / or a conductive polymer.

[0152] Alkali metal salts can be, for example, lithium salts. The amount of lithium salt in the solid electrolyte layer can be greater than or equal to 1M, for example, 1M to 4M. In this case, the lithium salt can improve the ionic conductivity by improving the lithium ion mobility of the solid electrolyte layer.

[0153] Lithium salts are used without limitation of type and may 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.

[0154] As an example, the lithium salt can be an imide lithium salt, such as LiTFSI, LiFSI, LiBETI, or a combination thereof. Imide lithium salts can maintain or improve ionic conductivity by appropriately maintaining their chemical reactivity with ionic liquids.

[0155] Ionic liquids are salts that are liquid at room temperature, consist only of ions, have a melting point at or below room temperature, or are salts that melt at room temperature.

[0156] Ionic liquids may be, in the form of a) at least one cation selected from ammonium, pyrrolidine, pyridinium, pyrimidine, imidazolium, piperidinium, pyrazolium, oxazoline, pyridazine, phosphonium, thioonium, or triazolium cations, or mixtures thereof, and b) cations selected from 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 - A compound containing at least one anion.

[0157] The ionic liquid may be selected from, for example, N-methyl-N-propylpyrrolidone bis(trifluoromethanesulfonyl)imine, N-butyl-N-methylpyrrolidone bis(3-trifluoromethanesulfonyl)imine, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide, or combinations thereof.

[0158] The weight ratio of solid electrolyte to ionic liquid in the solid electrolyte layer can be 0.1:99.9 to 90:10, and 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. Solid electrolyte layers satisfying these ranges can maintain or improve ionic conductivity as the electrochemical contact area with the electrode is improved. Accordingly, the energy density, discharge capacity, rate performance, etc., of all-solid-state rechargeable batteries can be improved.

[0159] All-solid-state rechargeable batteries can be single cells with a structure of positive electrode / solid electrolyte layer / negative electrode, dual cells with a structure of negative electrode / solid electrolyte layer / positive electrode / solid electrolyte layer / negative electrode, or stacked cells in which the structure of single cells is repeated.

[0160] The shape of all-solid-state rechargeable batteries is not particularly limited and can be, for example, coin-shaped, button-shaped, sheet-shaped, stacked, cylindrical, flat, etc. Furthermore, all-solid-state rechargeable batteries can 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-scale energy storage, and can be used in, for example, electric bicycles or power tools. Moreover, all-solid-state rechargeable batteries can be used in various fields such as portable electronic devices. Detailed Implementation

[0161] The following describes embodiments and comparative examples of the present invention. The embodiments described below are merely examples of the present invention, and the present invention is not limited to the embodiments described below.

[0162] Example 1

[0163] 1. Manufacturing of the positive electrode

[0164] LiNi coated with Li2O-ZrO2 0.8 Co 0.15 Mn 0.05 O2 positive electrode active material, lithium sulfide silver germanite type solid electrolyte Li6PS5Cl (D50=3 μm), and carbon black in powder form with an average particle size (D50) of 50 nm were dry-mixed in a dry atmosphere with a temperature of 25°C and a dew point of -40°C to -45°C.

[0165] Subsequently, a binder solution in which polyvinylidene fluoride binder is mixed in 2-ethylhexyl acetate solvent and a carbon nanotube solution in which L-carbon nanotubes (SWCNTs) are mixed with 2-ethylhexyl acetate as solvent are prepared. The binder solution is added to the dry-mixed mixture and mixed, and at this point, the amount of solvent is removed to satisfy 84 wt% positive electrode active material, 15 wt% Li6PS5Cl, 0.3 wt% carbon black and 1 wt% binder. The carbon nanotube solution is added to the mixture in which the binder solution is added and mixed to prepare a positive electrode active material slurry. At this point, based on 100 wt% of the total amount of carbon nanotubes and carbon nanoparticles (carbon black), the carbon nanotubes are adjusted to 75 wt% and the carbon black is adjusted to 25 wt%.

[0166] Subsequently, an aluminum foil with a thickness of 12 μm was used as the positive electrode current collector, and the positive electrode active material slurry was applied using a doctor blade coater at a concentration of 22 mg / cm³. 2 The amount of coating is applied to one surface of the positive electrode current collector and dried in a convection oven at 80°C for 10 minutes, and then rolled to manufacture the positive electrode.

[0167] 2. Manufacturing of the solid electrolyte layer

[0168] A sulfide-germanium ore-type solid electrolyte Li6PS5Cl (D50 = 3 μm) was added to a binder solution in which an acrylic binder (SX-A334, Zeon) was dissolved in isobutyl isobutyrate (IBIB) solvent, and the mixture was stirred to prepare a solid electrolyte layer composition. The composition comprised 98.5 wt% solid electrolyte and 1.5 wt% binder. The composition was coated onto a release PET film using a doctor blade coater and dried at room temperature to prepare a solid electrolyte layer.

[0169] 3. Manufacturing of the negative electrode

[0170] An Ag / C composite was prepared by mixing carbon black with an initial particle size (D50) of about 30 nm and silver (Ag) with an average particle size (D50) of about 60 nm in a weight ratio of 3:1. 0.25 g of the composite was then added to 2 g of an NMP solution containing 7 wt% polyvinylidene fluoride binder and mixed to prepare a negative electrode coating composition. This negative electrode coating composition was applied to a nickel foil current collector using a doctor blade coater and vacuum dried to prepare a precipitated negative electrode in which the negative electrode coating is formed on the current collector.

[0171] 4. Manufacturing of all-solid-state rechargeable battery cells

[0172] The prepared positive electrode, negative electrode, and solid electrolyte layer are cut and stacked on the positive electrode, followed by the negative electrode. This is then sealed into a bag and subjected to warm isostatic pressing (WIP) at 85°C and 500 MPa for 30 minutes to fabricate an all-solid-state rechargeable battery cell.

[0173] Example 2

[0174] The positive electrode and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the total amount of carbon nanotubes and carbon nanoparticles was 100 wt%, with 50 wt% carbon nanotubes and 50 wt% carbon black.

[0175] Comparative Example 1

[0176] The positive electrode and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that carbon nanoparticles were not used, and instead, 85 wt% LiNi was mixed in. 0.8 Co 0.15 Mn 0.05 The positive electrode active material consists of O2, 13 wt% of lithium-sulfur silver-germanium mineral-type solid electrolyte Li6PS5Cl, 1 wt% of polyvinylidene fluoride binder, and 1 wt% of carbon nanotubes.

[0177] Comparative Example 2

[0178] The positive electrode and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the total amount of carbon nanotubes and carbon nanoparticles was 100 wt%, with carbon nanotubes comprising 25 wt% and carbon black comprising 75 wt%.

[0179] Comparative Example 3

[0180] The positive electrode and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the total amount of carbon nanotubes and carbon nanoparticles was 100 wt%, with carbon nanotubes comprising 95 wt% and carbon black comprising 5 wt%.

[0181] Evaluation Example 1: SEM Analysis

[0182] To observe the positive electrode active material layer prepared in Comparative Example 1, a cross-sectional sample was prepared, and images taken using a scanning electron microscope (SEM) at 10,000x magnification are shown. Figure 6 middle.

[0183] refer to Figure 6 In Comparative Example 1, where only carbon nanotubes are used and no carbon nanoparticles are used as conductive materials, it can be confirmed that the carbon nanotubes 11 in the positive electrode active material layer are aggregated and exist non-uniformly.

[0184] Evaluation Example 2: Evaluation of Residual Solvent Content

[0185] The positive electrode active material layers prepared in Examples 1 and 2 were collected and analyzed by gas chromatography to measure the residual amount (ppm) of 2-ethylhexyl acetate as a solvent in the positive electrode active material layers, and the results are shown in Table 1.

[0186] (Table 1)

[0187]

[0188] Referring to Table 1, it can be confirmed that, based on 100 wt% of the positive electrode active material layer, the positive electrode active material prepared in Examples 1 and 2 includes a low-polarity solvent in an amount of 500 ppm or less.

[0189] Evaluation Example 3: Viscosity Evaluation

[0190] To confirm the viscosity change of the slurry with varying amounts of carbon nanoparticles, the viscosity changes of the positive electrode active material slurries obtained from Comparative Examples 1 and 2, as well as Examples 1 and 2, with respect to shear rate (1 / s) are shown in... Figure 7 Medium. And, magnified. Figure 7 An enlarged view of the rectangular portion is shown in Figure 8In addition, the viscosity values ​​of Comparative Example 1 and Comparative Example 2, as well as Example 1 and Example 2, are shown in Table 2 when the shear rates are 0.1 (1 / s), 1 (1 / s), and 10 (1 / s). In this paper, for the positive electrode slurry in which moisture is controlled at a dew point of -45°C, the viscosity was measured using a rheometer viscometer at a temperature of 25°C with a specified shear rate range of 0.01 to 1000.

[0191] (Table 2)

[0192]

[0193] refer to Figure 7 , Figure 8 Based on the results in Table 2, in the cases of Examples 1 and 2, compared with Comparative Example 1 in which no carbon nanoparticles were added, the area of ​​the hysteresis loop was reduced by mixing carbon nanotubes and carbon nanoparticles, and thus it can be confirmed that the dispersibility of the slurry was further improved.

[0194] Evaluation Example 4: Evaluation of Electrical Conductivity and Structural Stability

[0195] Using the positive electrodes obtained from Comparative Examples 1 to 3, and Examples 1 and 2, the measurement results of the electronic conductivity (σ_el) and ionic conductivity (σ_ion) of the positive electrode plates, measured by electrochemical impedance spectroscopy (EIS), are shown below. Figure 9 In this paper, EIS was measured by punching a single-sided positive electrode plate into 10π, assembling it into a torque cell, and setting it to 45°C in a temperature control chamber.

[0196] refer to Figure 9 It can be confirmed that, compared with Comparative Examples 1 and 3, in the cases of Examples 1 and 2, both electronic conductivity and ionic conductivity increase with the increase of the amount of carbon nanoparticles used with carbon nanotubes.

[0197] However, in the case of Comparative Example 2, due to the high content of carbon nanoparticles used with carbon nanotubes, the electronic conductivity and ionic conductivity are excellent. However, it was confirmed that there is a problem with structural stability because delamination occurs between the aluminum substrate (foil) that serves as the positive electrode current collector and the positive electrode active material layer.

[0198] Evaluation Example 5: Evaluation of Charge / Discharge Characteristics

[0199] To evaluate the discharge capacity and average discharge voltage of the all-solid-state rechargeable battery cells manufactured in Comparative Example 1 and Example 2, the battery cells were charged at 45°C in a thermostat with a constant current of 0.1C until the cell voltage reached 4.25V, and discharged at a constant current of 0.1C until the cell voltage reached 2.5V (first cycle); charged at a constant current of 0.1C until the cell voltage reached 4.25V, and discharged at a constant current of 0.33C until the cell voltage reached 2.5V (second cycle); charged at a constant current of 0.1C until the cell voltage reached 4.25V, and discharged at a constant current of 1.0C until the cell voltage reached 2.5V (third cycle).

[0200] The changes in discharge capacity of the all-solid-state rechargeable battery cells manufactured in Comparative Example 1 and Examples 1 and 2 are shown in Figure 10 And in Table 3.

[0201] Furthermore, the measurement results of the average discharge voltage of the all-solid-state rechargeable battery cells manufactured in Comparative Example 1, as well as Examples 1 and 2, are shown in... Figure 11 And in Table 4.

[0202] (Table 3)

[0203]

[0204] (Table 4)

[0205]

[0206] refer to Figure 10 , Figure 11 The evaluation results in Tables 3 and 4 confirm that, compared with Comparative Example 1, in Examples 1 and 2 using mixed carbon nanoparticles, the discharge capacity and average discharge voltage increased in three charge / discharge cycles.

[0207] Although preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts defined in the following claims are also within the scope of the present invention.

[0208] Explanation of reference numerals in the attached figures

[0209] 1: Positive electrode active material; 2: Sulfide solid electrolyte.

[0210] 11: Carbon nanotubes 12: Carbon nanoparticles

[0211] 100: All-solid-state battery; 200: Positive electrode

[0212] 201: Positive electrode current collector; 203: Positive electrode active material layer

[0213] 300: Solid electrolyte layer; 400: Negative electrode

[0214] 401: Negative electrode current collector; 403: Negative electrode active material layer

[0215] 400': Depositional negative electrode; 404: Lithium metal layer

[0216] 405: Negative electrode coating; 500: Elastic layer

Claims

1. A positive electrode, comprising: Positive electrode current collector; and positive electrode active material layer, on the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material, a sulfide solid electrolyte, a binder, and a conductive material. The conductive material includes carbon nanotubes and carbon nanoparticles, and Based on 100 wt% of the total amount of the carbon nanotubes and the carbon nanoparticles, the carbon nanotubes are included in an amount of 40 wt% to 90 wt%, and the carbon nanoparticles are included in an amount of 10 wt% to 60 wt%.

2. The positive electrode according to claim 1, wherein The carbon nanotubes are single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, or combinations thereof.

3. The positive electrode according to claim 1, wherein... The carbon nanoparticles are carbon black, acetylene black, Ketjen black, superconducting acetylene black, or a combination thereof.

4. The positive electrode according to claim 1, wherein The carbon nanotubes are L-carbon nanotubes.

5. The positive electrode according to claim 1, wherein The carbon nanoparticles form aggregates by connecting primary particles to each other.

6. The positive electrode according to claim 5, wherein The primary particles of the carbon nanoparticles have an average particle size of 1 nm to 50 nm.

7. The positive electrode according to claim 1, wherein... The sulfide solid electrolyte includes a sulfide solid electrolyte of the silver-germanium sulfide type represented by chemical formula 11. [Chemical Formula 11] (Li a M 1 b M 2 c (P) d M 3 e )(S f M 4 g )X h in, In chemical formula 11, 4 ≤ a ≤ 8, M 1 For Mg, Cu, Ag or combinations thereof, 0 ≤ b < 0.5, M 2 For Na, K, or combinations thereof, 0 ≤ c < 0.5, M 3 For Sn, Zn, Si, Sb, Ge or combinations thereof, 0 <d<4,0≤e<1,M 4 for O, SO n or combinations thereof, 1.5≤n≤5, 3≤f≤12, 0≤g<2, X is F, Cl, Br, I or combinations thereof, and 0≤h≤2.

8. The positive electrode according to claim 1, wherein The adhesive is a fluorine-based adhesive.

9. The positive electrode according to claim 1, wherein Based on 100 wt% of the positive electrode active material layer, the positive electrode active material layer comprises The positive electrode active material comprises 55 wt% to 95 wt%; 0.1 wt% to 35 wt% of the aforementioned sulfide solid electrolyte; and The adhesive is present in amounts of 0.1 wt% to 5 wt%.

10. The positive electrode according to claim 1, wherein The positive electrode active material layer further includes a low polarity solvent with a polarity index of 0.074 to 0.

281.

11. The positive electrode according to claim 10, wherein Based on 100 wt% of the positive electrode active material layer, the positive electrode active material layer includes the low polarity solvent in an amount of less than or equal to 500 ppm.

12. The positive electrode according to claim 1, wherein The low-polarity solvent has a polarity index of 0.074 to 0.281 and is selected from pyridine solvents, benzene solvents, acetate solvents, ketone solvents, ester solvents, ether solvents, carbonate solvents, acrylate solvents, aldehyde solvents, piperidine solvents, sulfite solvents, alkyl solvents, formate solvents, or combinations thereof.

13. The positive electrode according to claim 10, wherein The low-polarity solvent is 2,6-di-tert-butylpyridine, bromobenzene, benzyl chloride, p-chlorotoluene, benzylene dichloroisocyanurate, o-dichlorobenzene, N,N-dimethylamine, benzyl bromide, 1,2,3-trichloropropane, methoxybenzene, ethoxybenzene, 2-vinylpyridine, chlorocyclohexane, methyl laurate, ethyl chloroacetate, 2-ethylhexyl acetate, o-chlorobenzyl chloride, anisole, diethyl carbonate, ethyl trichloroacetate, n-butyl acrylate, methyl... Isoamyl ketone, di-tert-butyl ketone, styrene oxide, diketene, ethylhexanal, n-butyl methacrylate, diisopropyl ketone, sec-amyl acetate, methyl amyl acetate, n-butyl propionate, n-amyl propionate, 1-formylpiperidine, butyl benzoate, 4-heptanone, 1,8-cineole, isobutyl methacrylate, phenylacetonitrile, methyl benzoate, isobutyl isobutyrate, octyl acetate, acetylpyridine, methyl oleate Methylpentyl ketone, 5-methyl-3-heptanone, amyl formate, diisobutyl ketone, ethylpentyl ketone, vinyl sulfite, dibutyl ketone, cyclopentanone, 2-chloropyridine, ethyl phenylacetate, diethyl carbonate, benzaldehyde, isoamyl acetate, methyl hexyl ketone, ethyl benzoate, phenyl acetate, 2,3,4-trifluorotoluene, butyl butyrate, 2,6-dimethylpyridine, p-anisaldehyde, n-hexyl acetate, n-butyl acetate, 1-cyanobutyl Alkane, quinoline, heptyl acetate, benzyl acetate, cyclohexanone, 2,4,6-trimethylpyridine, methyl decanoate, 3-heptanone, 3-methylpyridine, methyl n-butyl ketone, isophorone, 4-ethylpyridine, 2-methylpyridine, methyl isobutylenyl ketone, 4-methylpyridine, 2,4-dimethylpyridine, 3,4-dimethylpyridine, 3,5-dimethylpyridine, cyclohexyl acetate, triethyl phosphate, or combinations thereof.

14. A method for manufacturing a positive electrode, comprising: The positive electrode active material, sulfide solid electrolyte, and carbon nanoparticles are dry-mixed, and The binder and carbon nanotubes are added to the dry-mixed mixture and then mixed to obtain a slurry of positive electrode active material. The carbon nanotubes are added in an amount of 40 wt% to 90 wt% based on 100 wt% of the total amount of the carbon nanotubes and the carbon nanoparticles, and the carbon nanoparticles are added in an amount of 10 wt% to 60 wt%.

15. The method for manufacturing a positive electrode according to claim 14, wherein... The addition of the binder and the carbon nanotubes is performed by adding a binder solution comprising the binder and a first low-polarity solvent, and a carbon nanotube solution comprising the carbon nanotubes and a second low-polarity solvent, to the dry-mixed mixture.

16. The method for manufacturing a positive electrode according to claim 15, wherein... The first low-polarity solvent and the second low-polarity solvent have a polarity index of 0.074 to 0.

281.

17. The method for manufacturing a positive electrode according to claim 15, wherein... First, the binder solution is added to the dry-mixed mixture and mixed, then the carbon nanotube solution is added and mixed.

18. An all-solid-state rechargeable battery, comprising: The positive electrode according to any one of claims 1 to 13; negative electrode; and A solid electrolyte layer is located between the positive electrode and the negative electrode.

19. The all-solid-state rechargeable battery according to claim 18, wherein The negative electrode includes: Negative electrode current collector; and A negative electrode coating is disposed on the negative electrode current collector and includes a lithium-philic metal, a carbon-containing material, or a combination thereof.

20. The all-solid-state rechargeable battery according to claim 19, wherein The all-solid-state rechargeable battery further includes a lithium metal layer formed by charging between the negative electrode current collector and the negative electrode coating.

Images