Negative electrode for all-solid-state battery, method for preparing coating slurry, and all-solid-state battery

Abstract

A negative electrode for an all-solid-state battery, a method of preparing a coating slurry, and an all-solid-state battery are disclosed. The negative electrode includes a negative electrode current collector and a coating layer on the negative electrode current collector. The coating layer includes a carbon-based material and metal particles. The metal particles include a lithium-philic metal. The average particle size of the metal particles is in the range of about 10 nm to about 200 nm. The standard deviation of the particle diameter of the metal particles is equal to or less than about 50% of the average particle diameter.

Description

[0001] This application claims priority to Korean Patent Application No. 10-2024-0146455, filed on October 24, 2024, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] This disclosure relates to a negative electrode for an all-solid-state battery, a method for preparing a coating slurry, and an all-solid-state battery. Background Technology

[0003] The development of high-energy-density and safe batteries is driven by industry demand. For example, lithium-ion batteries are being commercialized not only in formation-related and communication devices, but also in the automotive industry. In the automotive industry, safety is related to human safety.

[0004] All-solid-state batteries use a solid electrolyte instead of a liquid electrolyte. Because all-solid-state batteries do not use flammable organic dispersion media, the possibility of fire or explosion is significantly reduced, even in the event of a short circuit. Therefore, compared to lithium-ion batteries that use liquid electrolytes, all-solid-state batteries offer significantly improved safety. Summary of the Invention

[0005] Example embodiments of this disclosure include a negative electrode for an all-solid-state battery capable of improving lifetime characteristics.

[0006] Example embodiments of this disclosure include methods for preparing coating slurries capable of improving lifetime characteristics.

[0007] According to an example embodiment of this disclosure, the negative electrode for an all-solid-state battery may include a negative electrode current collector and a coating layer on the negative electrode current collector. The coating layer may include a carbon-based material and metal particles. The metal particles may include a lithium-philic metal. The average particle size of the metal particles may be in the range of about 10 nm to about 200 nm. The standard deviation of the particle size of the metal particles may be equal to or less than about 50% of the average particle size.

[0008] According to an example embodiment of this disclosure, a method for preparing a coating slurry may include the steps of: adding a carbonaceous material, metal particles, and a first binder to a solvent to form a first mixture; mixing the first mixture using a mixer; and subjecting the first mixture to a high-pressure dispersion process using a high-pressure disperser to form a dispersion. The high-pressure dispersion process may include pressurizing the first mixture at a pressure ranging from about 2,000 psi to about 30,000 psi and passing the pressurized first mixture through microchannels. The average particle size of the metal particles in the dispersion may be in the range of about 10 nm to about 200 nm. The standard deviation of the particle size of the metal particles in the dispersion may be equal to or less than about 50% of the average particle size.

[0009] According to an example embodiment of this disclosure, an all-solid-state battery may include the negative electrode, the positive electrode, and a solid electrolyte layer between the negative electrode and the positive electrode as discussed above. Attached Figure Description

[0010] Figure 1 A plan view illustrating an all-solid-state battery according to an example embodiment of the present disclosure is shown.

[0011] Figure 2A It shows along Figure 1 A sectional view taken by line A-A'.

[0012] Figure 2B It shows along Figure 1 The sectional view taken by line B-B'.

[0013] Figure 3 It shows along Figure 1 The image shows a cross-sectional view of an all-solid-state battery according to an exemplary embodiment of the present disclosure, taken along line A-A'.

[0014] Figure 4 It shows Figure 2A A sectional view of part "M".

[0015] Figure 5 It shows Figure 2A The portion “M” depicted in the figure shows an enlarged cross-sectional view of the coating layer according to a comparative example of this disclosure.

[0016] Figure 6 It shows the relationship with Figure 2A The portion “M” depicted in the figure corresponds to an enlarged cross-sectional view of the coating layer according to an exemplary embodiment of the present disclosure.

[0017] Figure 7 A perspective view illustrating an all-solid-state battery system according to an example embodiment of the present disclosure is shown.

[0018] Figure 8 A flowchart illustrating a method for preparing a coating slurry according to an example embodiment of the present disclosure is shown.

[0019] Figure 9 , Figure 10 and Figure 11 It shows Figure 8 The diagram shows the steps of the preparation method.

[0020] Figure 12 A graph is shown illustrating the results of counting the number of aggregates in coatings based on some examples and comparative examples.

[0021] Figure 13A and Figure 13BCross-sectional SEM images and surface SEM images of the coating layer of Example 1 are shown respectively.

[0022] Figure 14A and Figure 14B The cross-sectional SEM image and surface SEM image of the coating layer shown in Comparative Example 1 are displayed respectively.

[0023] Figure 15A and Figure 15B The cross-sectional SEM image and surface SEM image of the coating layer shown in Comparative Example 7 are displayed respectively.

[0024] Figure 16 A cross-sectional SEM image and a carbon EDS mapping image of the coating layer in Example 1 are shown.

[0025] Figure 17 The cross-sectional SEM image and carbon EDS mapping image of the coating layer in Comparative Example 1 are shown.

[0026] Figure 18 A cross-sectional SEM image of the coating layer in Comparative Example 7 is shown. Detailed Implementation

[0027] To fully understand the structure and effects of this disclosure, some exemplary embodiments of the disclosure have been described with reference to the accompanying drawings. However, it should be noted that this disclosure is not limited to the following exemplary embodiments and can be implemented in various forms. Rather, the exemplary embodiments are provided merely to disclose the disclosure and to enable those skilled in the art to fully understand its scope.

[0028] In this specification, it is understood that when an element is referred to as being "on" another element, the element may be directly on said other element, or an intervening element may be present between them. In the accompanying drawings, the thickness of some components may be exaggerated for the purpose of effectively explaining the technical content. Throughout the specification, the same reference numerals refer to the same elements.

[0029] Some exemplary embodiments detailed in this specification are discussed with reference to cross-sectional views and / or plan views, which serve as ideal example diagrams of this disclosure. In the drawings, the thickness of layers and regions may be exaggerated for the purpose of effectively explaining the technical content. Therefore, the regions exemplarily shown in the drawings have general properties, and the shapes of the regions exemplarily shown in the drawings are used to exemplarily disclose specific shapes, but are not limited to the scope of this disclosure. It is understood that although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. The exemplary embodiments explained and illustrated herein include supplementary embodiments thereof.

[0030] The terminology used in this specification is for describing various embodiments only and is not intended to limit this disclosure. Unless otherwise specifically stated in this specification, singular expressions may include plural expressions. The term "comprising / including" and / or variations thereof as used in this specification does not exclude the presence or addition of one or more other components.

[0031] In this specification, the term "combination thereof" may refer to mixtures, stacks, complexes, copolymers, alloys, blends, or reaction products.

[0032] In this specification, each of the phrases such as “A or B”, “at least one of A and B (species / man)”, “at least one of A or B (species / man)”, “A, B or C”, “at least one of A, B and C (species / man)” and “at least one of A, B or C (species / man)” may include any one or all possible combinations of the items listed together in the corresponding phrase.

[0033] Unless otherwise specifically defined in this specification, particle size may be the average particle size. Additionally, particle size refers to the average particle size (D) of particles having a cumulative volume of approximately 50% of the particle size distribution. 50 Average particle size (D) 50 The particle size can be measured using methods known to those skilled in the art, such as by a particle size analyzer, transmission electron microscopy (TEM) images, or scanning electron microscopy (SEM) images. Alternatively, data analysis can be performed using a dynamic light scattering measurement device to count the number of particles in each particle size range, and then the average particle size (D) can be calculated. 50 The average particle size (D) can be measured using laser scattering, unlike other methods. 50 In laser scattering, target particles are dispersed in a dispersion solvent and introduced into a laser scattering particle measuring device (e.g., the MT 3000, commercially available from Microtrac). The particles are irradiated with 28 kHz ultrasound at a power of 60 W, and the average particle size (D) is calculated using a 50% standard of particle size distribution within the measuring device. 50 ).

[0034] In an example embodiment, in this specification, the average particle size may refer to the diameter measured by randomly or unsystematically selecting 100 or more particles from an electron microscope image. Alternatively, in this specification, the average particle size may be measured using a particle size analyzer and may refer to the diameter of particles having a cumulative volume of approximately 50% of the particle size distribution.

[0035] When the terms “about” or “substantially” are used in conjunction with numerical values ​​in this specification, it is intended that the relevant numerical value includes a tolerance of ±10% around the stated value. When a range is specified, the range includes all values ​​within that range, such as increments of 0.1%.

[0036] Figure 1 A plan view illustrating an all-solid-state battery according to an example embodiment of the present disclosure is shown. Figure 2A It shows along Figure 1 A sectional view taken by line A-A'. Figure 2B It shows along Figure 1 The sectional view taken by line B-B'.

[0037] Reference Figure 1 , Figure 2A and Figure 2B According to this disclosure, the cell cell (CEL) of an all-solid-state battery may include a positive electrode layer 100, a negative electrode layer 200 opposite to the positive electrode layer 100, and a solid electrolyte layer 300 disposed between the positive electrode layer 100 and the negative electrode layer 200. However, this disclosure is not limited thereto, and the cell cell (CEL) may also include additional functional layers, such as an adhesion enhancement layer, disposed between the positive electrode layer 100 and the solid electrolyte layer 300 or between the negative electrode layer 200 and the solid electrolyte layer 300.

[0038] According to an exemplary embodiment of this disclosure, the positive electrode layer 100 may include a positive electrode current collector 110 and a positive electrode active material layer 120 disposed on the positive electrode current collector 110. The positive electrode active material layer 120 may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0039] The positive electrode current collector 110 can provide a reference surface on which the positive electrode active material layer 120 is disposed. The positive electrode current collector 110 may include a plate or foil containing at least one of, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or alloys thereof.

[0040] and Figure 1 As shown in the example embodiment of this disclosure, the positive electrode current collector 110 may not be provided. Although not shown, in order to increase the adhesion between the positive electrode current collector 110 and the positive electrode active material layer 120, a carbon layer with a thickness in the range of about 0.1 μm to about 4 μm may be further provided between the positive electrode current collector 110 and the positive electrode active material layer 120.

[0041] The positive electrode active material of the positive electrode active material layer 120 may include a material capable of reversibly adsorbing and desorbing lithium ions. The positive electrode active material may include multiple particles. For example, the positive electrode active material may include at least one of lithium transition metal oxides (e.g., lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganese oxide, or lithium iron phosphate), nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but this disclosure is not limited thereto. The positive electrode active material may be used alone or as a mixture of two or more substances.

[0042] Lithium transition metal oxides can be or include, for example, compounds represented by one of the following: Li a A 1-b B b D2 (where 0.90≤a≤1 and 0≤b≤0.5), Li a E 1-b B b O 2-c D c (Where, 0.90≤a≤1, 0≤b≤0.5 and 0≤c≤0.05), LiE 2-b B b O 4-c D c (where 0 ≤ b ≤ 0.5 and 0 ≤ c ≤ 0.05), Li a Ni 1-b-c Co b B c D α (Where, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05 and 0<α<2), Li a Ni 1-b-c Co b B c O 2-α F α (Where, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05 and 0<α<2), Li a Ni 1-b-c Mn b B c D α (Where, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05 and 0<α≤2), Li a Ni 1-b-c Mn b B c O 2-α F α (Where, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05 and 0<α<2), Li a Nib E c G d O2 (where 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5 and 0.001≤d≤0.1), Li a Ni b Co c Mn d G e O2 (where 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5 and 0.001≤e≤0.1), Li a NiG b O2 (where 0.9≤a≤1 and 0.001≤b≤0.1), Li a CoG b O2 (where 0.90≤a≤1 and 0.001≤b≤0.1), Li a MnG b O2 (where 0.90≤a≤1 and 0.001≤b≤0.1), Li a Mn2G b O4 (where 0.90≤a≤1 and 0.001≤b≤0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li 3-f J2(PO4)3 (where 0≤f≤2), Li 3-f Fe2(PO4)3 (where 0≤f≤2) and LiFePO4. In the above compounds, "A" can be or include at least one of Ni, Co, Mn or a combination thereof; "B" can be or include at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof; "D" can be or include at least one of O, F, S, P or a combination thereof; "E" can be or include at least one of Co, Mn or a combination thereof; "F" can be or include at least one of F, S, P or a combination thereof; "G" can be or include at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; "Q" can be or include at least one of Ti, Mo, Mn or a combination thereof; "I" can be or include at least one of Cr, V, Fe, Sc, Y or a combination thereof; and "J" can be or include at least one of V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0043] The positive electrode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt-type structure among the lithium transition metal oxides discussed above. The term "layered rock salt-type structure" may refer to a structure in which oxygen atom layers and metal atom layers are alternately and regularly arranged in the <111> direction of a cubic rock salt-type structure, in which each atom layer forms a two-dimensional plane. The term "cubic rock salt-type structure" may refer to a sodium chloride (NaCl)-type structure, which is a type of crystal structure, for example, having a face-centered cubic lattice (FCC) formed by cations and anions, respectively, that are错开 by 1 / 2 (half) of the unit lattice ridge. The lithium transition metal oxide having a layered rock salt-type structure may be or include a ternary lithium transition metal oxide, such as LiNi x Co y Al z O2 (NCA) or LiNi x Co y Mn z O2 (NCM) (where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1). When the positive electrode active material includes a ternary lithium transition metal oxide having a layered rock salt-type structure, the unit cell CEL may have an increased energy density and improved thermal stability.

[0044] The compound included in the positive electrode active material may be covered with a coating layer (not shown). The positive electrode active material may be used as a mixture of the compound and the compound added with the coating layer. The coating layer added to the surface of the positive electrode active material may include, for example, at least one of oxides, hydroxides, hydroxyoxides, carbonate oxy salts, or bicarbonate salts of the coating elements discussed below. The compound constituting the coating layer may be amorphous or crystalline. The coating elements included in the coating layer may include at least one of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The coating layer may include, for example, Li2O-ZrO2 (LZO). The method for forming the coating layer may be determined by any method that does not adversely affect the physical properties of the positive electrode active material. The method for forming the coating layer may include, for example, spraying or dipping.

[0045] When the positive electrode active material includes nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, the capacity density of the cell electrode (CEL) can be increased to reduce metal stripping from the positive electrode active material during charging. Therefore, the cell electrode CEL can improve its cycle characteristics under charging conditions. The term "cycle characteristics" can refer to the property indicating the degree of degradation of a cell electrode CEL due to charging and discharging. For example, a cell electrode CEL with high cycle characteristics degrades less due to charging and discharging, while a cell electrode CEL with low cycle characteristics degrades more due to charging and discharging.

[0046] The positive electrode active material can have, for example, a spherical or elliptical particle shape. There are no restrictions on the particle size and amount of the positive electrode active material.

[0047] The solid electrolyte of the positive electrode active material layer 120 may have a particulate shape. The solid electrolyte may be dispersed between the positive electrode active materials. The solid electrolyte may include a sulfide-based solid electrolyte having a desired or improved lithium-ion conductivity. The sulfide-based solid electrolyte may include at least one of the following: Li₂S-P₂S₅, Li₂S-P₂S₅-LiX (wherein X is or includes a halogen element), 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, Li₂S-P₂S₅-ZmS n (Where m and n are both positive integers, and "Z" is or includes at least one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (Where p and q are both positive integers, and "M" is or includes at least one of P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (where 0≤x≤2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2) and Li 7-x PS 6-x I x (where 0 ≤ x ≤ 2).

[0048] Sulfide solid electrolytes may be or include argentite-germanium sulfide compounds, such as Li 7-x PS6-x Cl x (where 0≤x≤2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2) and Li 7-x PS 6-x I x (where 0 ≤ x ≤ 2). For example, sulfide solid electrolytes may be or include sulfide-germanium ore-type compounds containing at least one of Li6PS5Cl, Li6PS5Br and Li6PS5I.

[0049] Optionally, the sulfide-based solid electrolyte may be or may include Li 7-a-c M a PS 6-c X c A sulfide-germanium ore type compound (where 0 ≤ a ≤ 2 and 0 ≤ c ≤ 2). In the above chemical formula, X can be or include at least one of F, Br, Cl, or combinations thereof. M can be or include at least one of scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or combinations thereof.

[0050] The sulfide-germanium ore type solid electrolyte can have a density in the range of about 1.5 g / cc to about 2.0 g / cc. When the sulfide-germanium ore type solid electrolyte has a density equal to or greater than about 1.5 g / cc, it is possible to reduce the internal resistance of the all-solid-state battery and hinder or prevent the solid electrolyte layer from experiencing short circuits and penetration caused by the formation of lithium dendrites. The solid electrolyte can have an elastic modulus in the range of, for example, about 15 GPa to about 35 GPa.

[0051] The average particle size of the solid electrolyte in the positive electrode active material layer 120 can be smaller than the average particle size of the first and second solid electrolytes in the solid electrolyte layer 300, as discussed below. For example, the average particle size of the solid electrolyte in the positive electrode active material layer 120 can be approximately equal to or less than approximately 90%, approximately 80%, approximately 70%, approximately 60%, approximately 50%, approximately 40%, approximately 30%, or approximately 20% of the average particle size of the solid electrolytes included in the solid electrolyte layer 300. The average particle size can be the median particle size measured using a laser particle size distribution analyzer.

[0052] The positive electrode active material layer 120 may include a conductive material. The conductive material may be conductive without causing chemical changes in the cell cell (CEL), thereby increasing the conductivity of the positive electrode active material and the solid electrolyte. The conductive material may include carbon-based materials. The conductive material may include one or more of, for example, graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0053] The positive electrode active material layer 120 may further include a binder. The binder can bind the positive electrode active material, solid electrolyte, and conductive material together in the positive electrode active material layer 120. The binder may include materials that improve the adhesion between the positive electrode active material layer 120 and the positive electrode current collector 110. For example, the binder may include at least one of polyvinylidene fluoride, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0054] Based on a total of 100 parts by weight of the positive electrode active material, solid electrolyte, conductive material, and binder, the positive electrode active material may be included in the positive electrode active material layer 120 in an amount ranging from about 85 parts by weight to about 92 parts by weight. Based on a total of 100 parts by weight of the positive electrode active material, solid electrolyte, conductive material, and binder, the binder may be included in the positive electrode active material layer 120 in an amount ranging from about 0.5 parts by weight to about 1.5 parts by weight.

[0055] Based on 100 parts by weight of solid electrolyte, conductive material may be included in the positive electrode active material layer 120 in an amount ranging from about 1 part by weight to about 50 parts by weight. When the conductive material is included in an amount less than about 1 part by weight relative to 100 parts by weight of solid electrolyte, the proportion of conductive material may decrease, thereby reducing the conductivity of the positive electrode active material layer 120. When the conductive material is included in an amount greater than about 50 parts by weight relative to 100 parts by weight of solid electrolyte, the proportion of conductive material may be excessively increased, resulting in incomplete formation of the coating layer covering the surface of the solid electrolyte.

[0056] In addition to the positive electrode active material, solid electrolyte, conductive material and binder, the positive electrode active material layer 120 may also include at least one of additives such as fillers, coating agents, dispersants and ionic conductive agents.

[0057] The negative electrode layer 200 may include a negative electrode current collector 210 and a coating layer 220 on the negative electrode current collector 210. The negative electrode current collector 210 may provide a reference surface on which the coating layer 220 is disposed. The negative electrode current collector 210 may include a material that does not react with lithium, such as a material that does not form an alloy or compound with lithium. For example, the negative electrode current collector 210 may include at least one of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), and alloys thereof. For example, the thickness of the negative electrode current collector 210 may be in the range of about 1 μm to about 20 μm, about 5 μm to about 15 μm, or about 7 μm to about 10 μm.

[0058] The negative electrode current collector 210 may be formed of one of the aforementioned metals, an alloy of two or more of the aforementioned metals, or a coating material, or may include one of the aforementioned metals, an alloy of two or more of the aforementioned metals, or a coating material. The negative electrode current collector 210 may have, for example, a plate shape or a foil shape. In an example embodiment, the negative electrode current collector 210 may not be provided.

[0059] When the cell CEL is charged, the coating layer 220 can induce the growth of lithium metal between the coating layer 220 and the negative electrode current collector 210. The coating layer 220 can form a protective layer for lithium metal and can simultaneously or concurrently reduce or inhibit the deposition and growth of lithium dendrites.

[0060] Coating layer 220 may include metals and carbon. For example, coating layer 220 may include at least one metal, such as or including at least one selected from gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), magnesium (Mg), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Coating layer 220 may include at least one carbon, such as or including at least one selected from carbon black, carbon nanotubes, acetylene black, furnace black, Ketjen black, and graphene. In an example embodiment, coating layer 220 may include a mixture (or composite) of carbon black and silver (Ag).

[0061] In addition to metals and carbon, coating layer 220 may also include additives. Coating layer 220 may include at least one additive, such as or including at least one of binders, fillers, coating agents, dispersants, and ionic conductive agents.

[0062] The thickness of the coating layer 220 can be less than the thickness of the positive electrode active material layer 120. For example, the thickness of the coating layer 220 can be equal to or less than about 50%, about 40%, about 30%, about 20%, about 10%, or about 5% of the thickness of the positive electrode active material layer 120. The thickness of the coating layer 220 can be in the range of, for example, about 1 μm to about 100 μm, about 2 μm to about 80 μm, about 10 μm to about 50 μm, or about 5 μm to about 20 μm. When the coating layer 220 has too small a thickness, lithium dendrites formed between the coating layer 220 and the negative electrode current collector 210 may cause the coating layer 220 to collapse and reduce the cycle characteristics of the cell cell (CEL). When the coating layer 220 has too large a thickness, the cell cell (CEL) may have a reduced energy density, and the internal resistance of the cell cell (CEL) may increase due to the coating layer 220, thereby reducing the cycle characteristics of the cell cell (CEL).

[0063] Although not shown, a carbon layer may also be included to increase the adhesion between the coating layer 220 and the solid electrolyte layer 300. See below for reference. Figure 4 The coating layer 220 according to an example embodiment of the present disclosure will be discussed in further detail.

[0064] A solid electrolyte layer 300 may be disposed between the positive electrode layer 100 and the negative electrode layer 200. The solid electrolyte layer 300 may include a sulfide-based solid electrolyte having a desired or improved lithium-ion conductivity. The solid electrolyte included in the solid electrolyte layer 300 may be the same as or different from the material of the solid electrolyte included in the positive electrode active material layer 120.

[0065] The solid electrolyte layer 300 may include a first solid electrolyte layer 310 and a second solid electrolyte layer 320. The first solid electrolyte layer 310 may be adjacent to the positive electrode layer 100, and the second solid electrolyte layer 320 may be adjacent to the negative electrode layer 200.

[0066] Reference Figure 2A The first solid electrolyte layer 310 may include a first solid electrolyte. The first solid electrolyte may have a spherical or elliptical particle shape. The first solid electrolyte may include a sulfide-based solid electrolyte. The first solid electrolyte may be in an amorphous, crystalline, or mixed state of amorphous and crystalline states. The solid electrolyte may include at least sulfur (S), phosphorus (P), and lithium (Li) from the constituent elements included in the aforementioned sulfide-based solid electrolytes. For example, the solid electrolyte may be or include a material comprising Li₂S-P₂S₅. When Li₂S-P₂S₅ is used as the sulfide-based solid electrolyte material of the solid electrolyte, the molar ratio of Li₂S to P₂S₅ may be in the range of about 50:50 to about 90:10.

[0067] In an example embodiment, the first solid electrolyte may include a pyrrhotgermanium sulfide compound, which includes, for example, Li. 7-x PS 6-x Cl x (where 0≤x≤2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2) and Li 7-x PS 6-x I x (where 0 ≤ x ≤ 2). For example, sulfide solid electrolytes may be or include sulfide-germanium ore-type compounds containing at least one of Li6PS5Cl, Li6PS5Br and Li6PS5I.

[0068] Optionally, the first solid electrolyte may include Li 7-a-c M a PS 6-c X c A sulfide-germanium ore type compound. In the above chemical formula, X can be or include at least one of Cl, Br, or a combination thereof. M can be or include at least one of Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof. Subscripts "a" and "c" can both be real numbers in the range of 0 to 2.

[0069] The sulfide-germanium ore type solid electrolyte can have a density in the range of about 1.5 g / cc to about 2.0 g / cc. When the sulfide-germanium ore type solid electrolyte has a density equal to or greater than about 1.5 g / cc, it is possible to reduce the internal resistance of the all-solid-state battery and hinder or prevent the solid electrolyte layer from experiencing short circuits and penetration caused by the formation of lithium dendrites. The first solid electrolyte can have an elastic modulus in the range of, for example, about 15 GPa to about 35 GPa.

[0070] The first solid electrolyte layer 310 may further include an adhesive. The adhesive included in the first solid electrolyte layer 310 may include at least one of, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, or polyethylene, but this disclosure is not limited thereto. The adhesive of the first solid electrolyte layer 310 may be the same as or different from the adhesive of the positive electrode active material layer 120 or the adhesive of the coating layer 220.

[0071] The second solid electrolyte layer 320 may include a second solid electrolyte. The second solid electrolyte may have a spherical particle shape or an elliptical particle shape.

[0072] The second solid electrolyte may include a sulfide-based solid electrolyte. The description of the second solid electrolyte may be the same as or similar to that of the first solid electrolyte. In an example embodiment, the second solid electrolyte may have substantially the same composition as the first solid electrolyte. Optionally, the second solid electrolyte may have a composition similar to that of the first solid electrolyte.

[0073] The second solid electrolyte can be in direct contact with the coating layer 220. Therefore, the second solid electrolyte can reduce or suppress lithium dendrites formed between the coating layer 220 and the negative electrode current collector 210. The second solid electrolyte can effectively reduce or suppress negative electrode side reactions. Therefore, the all-solid-state battery according to the example of this disclosure can improve the performance of the battery cell.

[0074] The first solid electrolyte layer 310 may have a first thickness TK1, and the second solid electrolyte layer 320 may have a second thickness TK2. The first thickness TK1 and the second thickness TK2 may be the same as or different from each other. In an example embodiment, the first thickness TK1 may be greater than the second thickness TK2. For example, the first thickness TK1 may be in the range of about 1.1 times to 5 times the second thickness TK2.

[0075] Return to reference Figure 1 , Figure 2A and Figure 2B The positive electrode layer 100 and the first solid electrolyte layer 310 can form a positive electrode hybrid layer CSH. The negative electrode layer 200 and the second solid electrolyte layer 320 can form a negative electrode hybrid layer ASH. The positive electrode hybrid layer CSH can be stacked on the negative electrode hybrid layer ASH.

[0076] The negative electrode hybrid layer ASH and the positive electrode hybrid layer CSH can have different areas. For example, the area of ​​the negative electrode hybrid layer ASH can be larger than the area of ​​the positive electrode hybrid layer CSH. The positive electrode hybrid layer CSH can be completely stacked inward with the negative electrode hybrid layer ASH.

[0077] In an exemplary embodiment of this disclosure, the first solid electrolyte layer 310 may have substantially the same area as the positive electrode layer 100. The second solid electrolyte layer 320 may have substantially the same area as the negative electrode layer 200.

[0078] For example, the positive electrode hybrid layer CSH can have a first width WI1 in the first direction D1. The negative electrode hybrid layer ASH can have a second width WI2 in the first direction D1. The first width WI1 can be smaller than the second width WI2. The positive electrode hybrid layer CSH can have a third width WI3 in the second direction D2. The negative electrode hybrid layer ASH can have a fourth width WI4 in the second direction D2. The third width WI3 can be smaller than the fourth width WI4.

[0079] According to this example embodiment, the cell CEL can be manufactured by forming a negative electrode hybrid layer ASH on a first carrier film, forming a positive electrode hybrid layer CSH on a second carrier film, and then stacking the negative electrode hybrid layer ASH and the positive electrode hybrid layer CSH.

[0080] The cell cell CEL according to this example embodiment may further include a gasket GSK. The gasket GSK may surround the positive electrode hybrid layer CSH. The area difference between the negative electrode hybrid layer ASH and the positive electrode hybrid layer CSH will create a step difference on the side surface of the cell cell CEL, and the gasket GSK may fill this step difference. The gasket GSK may surround the four side surfaces of the positive electrode hybrid layer CSH. For example, the thickness of the gasket GSK may be substantially the same as or less than the thickness of the positive electrode hybrid layer CSH. In the example embodiment, the positive electrode current collector 110 may be located at a height (or horizontality) above the gasket GSK.

[0081] The positive electrode current collector 110 may include a positive electrode tab CTB. The positive electrode tab CTB may be or include a protruding region of the positive electrode current collector 110. In an example embodiment, the positive electrode tab CTB may protrude in the second direction D2.

[0082] The negative electrode current collector 210 may include a negative electrode terminal block ATB. The negative electrode terminal block ATB may be or include a protruding region of the negative electrode current collector 210. In an example embodiment, the negative electrode terminal block ATB may protrude in a direction opposite to the second direction D2.

[0083] In the following example embodiments, references to the above are omitted. Figure 1 , Figure 2A and Figure 2B The technical features discussed are repeated in detail, and their differences are discussed in detail.

[0084] Figure 3 It shows along Figure 1 A cross-sectional view of an all-solid-state battery according to an exemplary embodiment of the present disclosure is shown, taken along line A-A'. (Refer to...) Figure 3 The negative electrode layer 200 of the cell cell CEL may further include a lithium metal layer 400 between the negative electrode current collector 210 and the coating layer 220. The lithium metal layer 400 may have an increased thickness during charging of the cell cell CEL. The coating layer 220 may constitute a protective layer for the lithium metal layer 400 and may simultaneously or concurrently reduce or suppress the growth of lithium dendrites from the lithium metal layer 400.

[0085] The lithium metal layer 400 may be or include a thin metal layer comprising lithium or a lithium alloy. The lithium alloy may be or include at least one of, for example, Li-Al alloys, Li-Sn alloys, Li-In alloys, Li-Ag alloys, Li-Au alloys, Li-Zn alloys, Li-Ge alloys, or Li-Si alloys, but any suitable lithium alloy may be applicable. The lithium metal layer 400 may include lithium or one of the aforementioned alloys. Optionally, the lithium metal layer 400 may include various alloys.

[0086] The lithium metal layer 400 may have a fifth width WI5 in the first direction D1. The fifth width WI5 may be the same as or greater than the first width WI1. The fifth width WI5 may be the same as or less than the second width WI2. For example, the fifth width WI5 may be greater than the first width WI1 and less than the second width WI2.

[0087] Coating layer According to some examples and comparative examples of this disclosure described below, the coating 220 can be in a state that has undergone at least one charge / discharge cycle after the battery cell has been manufactured. For example, Figures 4 to 6 The results of a post-evaluation of the coating 220 in a battery cell that has undergone at least one charge / discharge cycle are shown. For example, Figures 4 to 6 The coating layer 220 in a battery cell that has undergone the formation process is depicted. Figures 4 to 6 The results of post-use analysis of coating 220 in a battery cell that has undergone 10 charge / discharge cycles after the formation process are shown.

[0088] Figure 4 It shows Figure 2A A sectional view of part "M". Figure 4 This is an enlarged cross-sectional view of the coating layer 220 according to an exemplary embodiment of the present disclosure. (Refer to...) Figure 4 The coating layer 220 may include a carbon-based material CCM and metal particles MTP. In an example embodiment, the carbon-based material CCM may have a particle shape. The average particle size (D) of the carbon-based material CCM... 50 The average particle size (D) of carbon-based materials (CCM) can range from approximately 10 nm to approximately 1 μm. 50 The average particle size (D) of carbon-based materials (CCM) can be equal to or greater than approximately 10 nm, approximately 20 nm, or approximately 30 nm. 50 The average particle size (D) of carbon-based materials (CCM) can be equal to or smaller than approximately 1 μm, approximately 100 nm, approximately 70 nm, or approximately 50 nm. 50 It can be larger than the average particle size of metal particles (MTP).

[0089] When the average particle size of carbonaceous material CCM (D) 50When the values ​​fall within the above range, all-solid-state batteries can have increased lifespan and minimal volume change during charge and discharge.

[0090] In the example embodiment, the carbon-based material CCM can have a porous structure. For example, the carbon-based material CCM can have a porous structure of approximately 5m. 2 / g to approximately 1,000m 2 / g or approximately 30m 2 / g to approximately 100m 2 Brunauer-Emmett-Teller (BET) specific surface area in the range of / g. Carbon-based materials (CCM) can have a specific surface area equal to or greater than approximately 5m². 2 / g, approximately 10m 2 / g, approximately 20m 2 / g, approximately 30m 2 / g, approximately 40m 2 / g, approximately 50m 2 / g, approximately 60m 2 / g, approximately 100m 2 / g, approximately 200m 2 / g, approximately 300m 2 / g or approximately 400m 2 BET specific surface area per g. Carbon-based materials (CCM) can have a BET specific surface area equal to or less than approximately 1,000 m². 2 / g, approximately 900m 2 / g, approximately 800m 2 / g, approximately 700m 2 / g, approximately 600m 2 / g, approximately 500m 2 / g, approximately 400m 2 / g, approximately 300m 2 / g, approximately 200m 2 / g, approximately 100m 2 / g, approximately 90m 2 / g, approximately 80m 2 / g or approximately 70m 2 / g BET specific surface area.

[0091] When the BET specific surface area of ​​carbon-based materials (CCM) falls within the above range, all-solid-state batteries can have increased lifespan and minimal volume change during charge and discharge.

[0092] Carbon-based material CCMs can include at least one of non-graphitizable carbon (or hard carbon) and graphitizable carbon (or soft carbon). For example, carbon-based material CCMs can include non-graphitizable carbon (or hard carbon).

[0093] For example, carbon-based material CCMs may include at least one of carbon black, carbon nanotubes, acetylene black, furnace black, Ketjen black, and graphene. However, carbon-based material CCMs are not limited to the examples above.

[0094] Carbon-based material CCMs can have at least one of the following shapes: spherical, elliptical, plate-like, and combinations thereof. However, the shape of carbon-based material CCMs is not limited to the examples mentioned above.

[0095] Coating 220 may include a plurality of pores (POR). For example, coating 220 may have a porosity equal to or greater than about 10%. Coating 220 may have a porosity equal to or less than about 60% or about 40%. Coating 220 may have a porosity in the range of about 20% to about 40%. The porosity of coating 220 can be obtained by Equation 1.

[0096] Equation 1: Porosity (%) = {1 - (apparent density / actual density)} × 100.

[0097] Porosity refers to the ratio of pore volume to total volume in a sample. It can be used to indirectly evaluate the presence and size of pores in a sample.

[0098] Apparent density can refer to the density that includes the total volume (apparent volume) of the sample and can be calculated taking into account empty spaces within the sample (such as openings). Apparent density can be a concept that contrasts with true density. Apparent density can be defined as the ratio of the mass of coating 220 to the total volume (apparent volume) of coating 220.

[0099] Apparent density can be measured using Archimedes' principle, mercury porosimetry, or liquid pycnometry. For example, Archimedes' principle can be a method of calculating volume by measuring the buoyancy of a sample applied to a liquid. Mercury porosimetry can be a method of using mercury to study the pore structure within a sample and calculating the total volume of the sample based on the results. Liquid pycnometry can be used to directly measure the volume of a sample and calculate apparent density. However, methods for measuring apparent density are not limited to the examples discussed above.

[0100] True density can refer to the density of the pure material excluding all pores within the sample. True density can be defined as the theoretical density of the coating 220, which does not contain any pores. For example, true density can be measured using a gas specific gravity bottle. The value of true density can be obtained by adsorbing a gas (such as helium) onto the sample and measuring the pressure change caused by the reduction in volume of the adsorbed gas.

[0101] The method for measuring the true density using a gas specific gravity bottle is as follows. The sample chamber, into which the sample is introduced, can be connected to the reference chamber via an expansion valve. The volume of the sample chamber (Vc) and the volume of the reference chamber (Vr) can be measured. When the gas inlet valve is opened to introduce helium into the sample chamber, the equilibrium pressure inside the sample chamber becomes P1, and the volume becomes Vc - Vs. Vs can be the volume of the sample. When the expansion valve is opened, the new equilibrium pressure becomes P2, and the volume becomes Vc - Vs + Vr. This can be written as the simple equation: P1(Vc - Vs) = P2(Vc - Vs + Vr). The equilibrium pressures P1 and P2 can be measured using a pressure sensor, and since the volumes Vc and Vr of the two chambers are known, Vs can be derived. The true density can be calculated by substituting Vs into the pre-measured mass of the sample.

[0102] When the porosity of the coating layer 220 falls within the above-mentioned range, the all-solid-state battery can have increased lifetime and minimal volume change during charge and discharge.

[0103] According to an example embodiment of this disclosure, coating layer 220 may have a relatively small average pore size PRS. Average pore size PRS may refer to the average size of the pores POR present within coating layer 220, and may represent the average size of the pores POR present within coating layer 220. Figure 4 The average lengths of the major and minor axes of 100 randomly or non-systematically selected holes in the coating layer 220 depicted in the figure are measured by POR. Figure 4 Electron microscope images can be schematically represented. The average size can be calculated using either the geometric mean or the arithmetic mean.

[0104] For example, a scanning electron microscope (SEM) image can be obtained from a cross-section of the coating layer 220, and the area of ​​the hole POR can be analyzed from the SEM image using software such as ImageJ. The diameter of a circle having the same area as the hole POR can then be determined as the size of the hole POR.

[0105] Alternatively, the size of the orifice POR can be calculated using the Barrett-Joyner-Halenda (BJH) method based on data obtained from Brunauer-Emmett-Teller (BET) analysis of coating layer 220.

[0106] The average pore size PRS according to exemplary embodiments of this disclosure can be in the range of about 5 nm to about 200 nm, about 10 nm to about 100 nm, or about 10 nm to about 60 nm. In an exemplary embodiment, in coating layer 220, the metal particles MTP discussed below can diffuse toward the negative electrode current collector 210 during battery charging and discharging. In this case, when the metal particle MTP diffusion is irreversibly retained on the negative electrode current collector 210, a pore POR can be formed in the space where the metal particle MTP was originally located. For example, the average pore size PRS can be proportional to the average particle size PTS of the metal particles discussed below.

[0107] According to an exemplary embodiment of this disclosure, the orifice pores (PORs) in the coating layer 220 may have a relatively narrow distribution. The distribution of orifice pores (PORs) according to the examples of this disclosure may refer to the uniformity of the size distribution of the orifice pores. The distribution of orifice pores (PORs) can be defined by the standard deviation of the pore size.

[0108] As discussed above, the standard deviation can be calculated from the sizes of 100 randomly or unsystematically selected aperture sizes (PORs) in an electron microscope image. The standard deviation of aperture size can be defined as the square root of the sum of the squared differences between each aperture size and the average aperture size (PRS) divided by the total number of apertures (e.g., N=100).

[0109] For example, the standard deviation of the hole size according to this disclosure can be statistically calculated based on measurement data obtained from hole size measured by scanning electron microscopy (SEM).

[0110] The distribution or standard deviation of the aperture POR according to the exemplary embodiments of this disclosure may be equal to or less than about 60%, about 50%, or about 40% of the average aperture size PRS. For example, when the average aperture size PRS is about 20 nm, the standard deviation may be equal to or less than about 10 nm. For example, when the average aperture size PRS is about 40 nm, the standard deviation may be equal to or less than about 20 nm.

[0111] The pores (POR) in the coating layer 220 can constitute a resistor for lithium conduction and / or diffusion. A reduction in the average pore size (PRS) of the pores (POR) can lead to improvements in the lifespan and performance of the all-solid-state battery. For example, when the average pore size (PRS) according to this disclosure falls within the aforementioned range, the lifespan and performance of the all-solid-state battery can be improved. A reduction in the distribution of pores (POR) can also lead to improvements in the lifespan and performance of the all-solid-state battery. For example, when the standard deviation of the pore size according to this disclosure falls within the aforementioned range, the lifespan and performance of the all-solid-state battery can be improved.

[0112] The coating layer 220 may include multiple metal particles (MTPs). When the all-solid-state battery is charged and discharged, the metal particles (MTPs) can help promote the migration of lithium ions toward the negative electrode current collector 210.

[0113] Metal particle MTPs may include at least one of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), magnesium (Mg), titanium (Ti), gallium (Ga), zinc oxide (ZnO), germanium (Ge), lead (Pb), antimony (Sb), and indium (In). For example, metal particle MTPs may include at least one of silver (Ag), magnesium (Mg), bismuth (Bi), gold (Au), platinum (Pt), zinc (Zn), and combinations thereof.

[0114] Metal particles (MTPs) according to exemplary embodiments of this disclosure may include lithium-philic metals. Lithophilic metals may exhibit properties represented by Equation 2.

[0115] Equation 2: ΔG=ΔH 523.15K -TΔS 523.15K ≤0.

[0116] For example, at approximately 250 °C, the Gibbs free energy ΔG of a lithiophilic metal in a chemical reaction with molten lithium can be equal to or less than approximately 0 kJ / mol. For instance, at approximately 250 °C, the Gibbs free energy ΔG of the chemical reaction between metal particles (MTP) and molten lithium can range from approximately -1,500 kJ / mol to approximately 0 kJ / mol. Under these conditions, the lithiophilic metal and lithium can spontaneously form alloys.

[0117] Metal particle (MTP) according to exemplary embodiments of this disclosure may be or include nanoparticles. Metal particle (MTP) may include at least one of single-particle LPMs and aggregated aggregates (AGRs). For example, multiple single-particle LPMs may aggregate to form a single particle, which may be defined as an aggregate (AGR).

[0118] The aggregated AGR according to this example embodiment can be in the form of about 10 or fewer single-particle LPM aggregates. For example, similar to single-particle LPMs, the aggregated AGR according to this example embodiment can be nanoscale.

[0119] The metal particles (MTP) can have an average particle size (PTS) in the range of about 5 nm to about 300 nm. For example, the metal particles (MTP) can have an average particle size (PTS) in the range of about 10 nm to about 200 nm. For example, the metal particles (MTP) can have an average particle size (PTS) equal to or greater than about 5 nm or 10 nm. For example, the metal particles (MTP) can have an average particle size (PTS) equal to or less than about 300 nm, about 200 nm, or about 100 nm. When the average particle size (PTS) of the metal particles (MTP) falls within the above range, lithium ions can easily migrate toward the negative electrode current collector 210 during the charging and discharging of the all-solid-state battery. When the average particle size (PTS) of the metal particles (MTP) falls within the above range, the average pore size (PRS) and distribution of the pores (POR) in the coating layer 220 can each have relatively small values ​​as discussed above.

[0120] According to exemplary embodiments of this disclosure, the average particle size (PTS) of the metal particles (MTP) can be relatively small. The average particle size (PTS) of the metal particles (MTP) can refer to the average size of the metal particles (MTP) present in the coating layer 220, or the average size of individual LPM particles and aggregates (AGR). The average particle size (PTS) can be represented by... Figure 4 The average lengths of the major and minor axes of 100 randomly or unsystematically selected metal particles in the coating layer 220 depicted are measured by MTP. The average particle size can be calculated using either the geometric mean or the arithmetic mean.

[0121] According to an exemplary embodiment of this disclosure, the metal particle MTP in the coating layer 220 may have a relatively narrow distribution. The distribution of the metal particle MTP according to the examples of this disclosure may refer to the uniformity of the size distribution of the metal particle MTP. The distribution of the metal particle MTP can be defined by the standard deviation of the particle size of the metal particle MTP.

[0122] As discussed above, the standard deviation can be calculated from the sizes of 100 randomly or unsystematically selected metal particle MTPs in an electron microscope image. The standard deviation of particle size can be defined as the square root of the sum of the squared differences between the particle size of each metal particle MTP and the average particle size PTS, divided by the total number of particles (e.g., N=100).

[0123] For example, the standard deviation of the particle size of the metal particles MTP according to the example of this disclosure can be statistically calculated based on measurement data obtained from particle size measured by scanning electron microscopy (SEM).

[0124] According to exemplary embodiments of this disclosure, the distribution or standard deviation of the metal particle MTP can be equal to or less than about 60%, about 50%, or about 40% of the average particle size PTS. For example, when the average particle size PTS is about 20 nm, the standard deviation can be equal to or less than about 10 nm. For example, when the average particle size PTS is about 40 nm, the standard deviation can be equal to or less than about 20 nm.

[0125] As discussed above, the size of the metal particle MTP can determine the size of the pore size (POR) formed after charge / discharge cycles. For example, a decrease in the average particle size (PTS) and distribution of the metal particle MTP can cause a decrease in the porosity, average pore size (PRS), and pore distribution of the coating layer 220.

[0126] According to an example embodiment of this disclosure, when analyzing coating 220 by post-evaluation, it may be slightly difficult to measure the particle size of metal MTP from SEM images. This is likely because the size of the metal MTP particles is substantially fine. The size of the pore POR can be easily measured by analyzing the area of ​​the pore POR using software such as ImageJ. Therefore, the size and distribution of the pore POR can be analyzed to identify the size and distribution of the corresponding metal MTP particles.

[0127] According to an example embodiment of this disclosure, since the metal particles (MTP) in the coating layer 220 can have a relatively small average particle size (PTS) and distribution, the coating layer 220 can have reduced porosity, average pore size (PRS), and pore distribution. Therefore, the lifetime and performance of the all-solid-state battery according to this disclosure can be improved.

[0128] The metal particles (MTP) in the coating layer 220 can be present in an amount ranging from about 1 wt% to about 50 wt% relative to the total weight of the coating layer 220. For example, the metal particles (MTP) can be present in an amount equal to or greater than about 3 wt%, about 5 wt%, or about 10 wt% relative to the total weight of the coating layer 220. For example, the metal particles (MTP) can be present in an amount equal to or less than about 50 wt%, about 40 wt%, about 30 wt%, about 25 wt%, about 20 wt%, or about 15 wt% relative to the total weight of the coating layer 220. When the amount of metal particles (MTP) falls within the above range, lithium ions can easily migrate toward the negative electrode current collector 210 during the charging and discharging of the all-solid-state battery.

[0129] Figure 5 It shows Figure 2A The portion “M” depicted in the figure shows an enlarged cross-sectional view of a coating layer according to a comparative example of this disclosure. In the following example embodiments, for ease of description, references to the above-mentioned figures are omitted. Figure 4 The features discussed are the same, and their differences are discussed in detail.

[0130] Reference Figure 5 The metal particles MTP in the coating layer 220 can have a relatively large average particle size PTS. Figure 5 The metal particles MTP shown can have an average particle size PTS in the range of about 200 nm to about 1,000 nm. Figure 5 The aggregate AGR can be greater than Figure 4 Bulk aggregates of AGR. Bulk aggregates of AGR can have a size greater than approximately 1 μm.

[0131] Figure 5 The metal particles (MTP) in the coating layer 220 can have a relatively wide distribution. For example, Figure 5 Metal particles (MTP) can have irregular sizes. Figure 5 Metallic particles (MTPs) can have particle sizes with relatively large standard deviations. For example, Figure 5 The standard deviation of the particle size of the metal particles (MTP) shown can be equal to or greater than about 80% or about 100% of the average particle size (PTS). For example, when the average particle size (PTS) is about 500 nm, the standard deviation can be equal to or greater than about 400 nm.

[0132] Figure 5 The coating layer 220 may contain pores POR with relatively large dimensions. Figure 5 The average pore size PRS can range from about 200 nm to about 1,000 nm. Bulk pore POR can be formed by the migration of bulk aggregates AGR.

[0133] Figure 5 The pores (POR) in the coating layer 220 can have a relatively wide distribution. For example, Figure 5 The hole POR can have irregular dimensions. Figure 5 The hole size can have a relatively large standard deviation. For example, Figure 5 The distribution or standard deviation of the hole POR shown may be equal to or greater than approximately 80% or approximately 100% of the average hole size.

[0134] The coating 220 according to the comparative example may have a relatively large distribution of metal particle (MTP), relatively large porosity (POR), and relatively wide porosity. This would constitute a large resistance to the conduction and / or diffusion of lithium in the coating 220. Therefore, the coating 220 according to the comparative example may degrade battery performance and lifespan.

[0135] Figure 6 It shows the relationship with Figure 2A The portion "M" depicted in the figure corresponds to an enlarged cross-sectional view of the coating layer according to an exemplary embodiment of the present disclosure. In the following exemplary embodiments, for ease of description, references to the above-described components are omitted. Figure 4The features discussed are the same, and their differences are discussed in detail.

[0136] Reference Figure 6 The lithium metal layer 400 can be disposed between the coating layer 220 and the negative electrode current collector 210. A detailed description of the lithium metal layer 400 can be found in the above reference. Figure 3 The descriptions provided are essentially the same. For example, Figure 6 The coating 220 can be shown as having undergone at least one charge / discharge cycle of an all-solid-state battery.

[0137] According to an exemplary embodiment of this disclosure, the metal particles (MTPs) distributed in the coating layer 220 may exhibit a trend of gradually decreasing density from the lower to the upper part of the coating layer 220. For example, the density of metal particles (MTPs) in the coating layer 220 adjacent to the negative electrode current collector 210 or the lithium metal layer 400 may be greater than the density of metal particles (MTPs) in the coating layer 220 adjacent to the solid electrolyte layer 300.

[0138] In this disclosure, the density of metal particle MTPs can refer to the number of metal particle MTPs present in a given area and can be analyzed based on electron microscope images.

[0139] For example, based on the specific thickness of the coating layer 220, the number of metal particles (MTP) per unit area in each layer (lower, middle, and upper) can be measured to identify variations in the density of the metal particle MTP in detail.

[0140] Electron microscope images can be used to obtain the density of metal particle MTP per unit area for each of the top, middle, and bottom layers of coating 220, and based on this data, the variation in density can be visualized as a graph (see...). Figure 6 The decreasing density of metal particles (MTP) from the bottom to the top of the coating layer 220 can affect the physical properties and electrical conductivity of the coating layer 220.

[0141] The density distribution of the metal particle MTP according to the exemplary embodiments of this disclosure can be adjusted so that lithium diffusion, conduction, and alloying can occur in the coating layer 220 as needed. For example, a higher density of metal particle MTP can be formed in the lower part of the coating layer 220 where lithium diffusion, conduction, and alloying can occur more significantly, and a lower density of metal particle MTP can be formed in the upper part of the coating layer 220 where lithium diffusion, conduction, and alloying can occur less significantly. Therefore, it is possible to improve or optimize the electrical performance of the all-solid-state battery.

[0142] According to an example embodiment of this disclosure, the porosity (POR) distributed in the coating layer 220 can exhibit a trend of gradually increasing density from the lower to the upper part of the coating layer 220. For example, the porosity can gradually increase from the lower to the upper part of the coating layer 220. The porosity can be substantially the same as the porosity defined above. The change in porosity can also be plotted as follows: Figure 6 The porosity can be inversely proportional to the density of metal particle MTP. According to an example embodiment of this disclosure, the porosity can be as follows: Figure 6 The curves shown in the graph are modified to improve or optimize the electrical performance of all-solid-state batteries.

[0143] Figure 7 A perspective view illustrating an all-solid-state battery system according to an exemplary embodiment of the present disclosure is shown. (Refer to...) Figure 7 The all-solid-state battery system SYS may include an all-solid-state battery 10 and a pressing device PDV. The all-solid-state battery 10 may include at least one cell CEL according to an example embodiment of the present disclosure.

[0144] The pressing device PDV can be configured to apply external pressure to uniformly press the all-solid-state battery 10 disposed therein. The pressing device PDV can uniformly electrodeposit and desorb lithium during charging and discharging, and can hinder or prevent structural degradation of the all-solid-state battery 10.

[0145] The pressing method can be any suitable means capable of applying pressure (e.g., substantially uniform pressure) to the all-solid-state battery 10, and is not limited to the examples mentioned above. For example, the pressing device PDV can be a pressing clamp. The pressing device PDV can include an upper plate UPL and a lower plate LPL, and can also include fastening mechanisms for interconnecting and securing the two plates UPL and LPL. For example, the fastening mechanism (not shown) can include bolts and nuts passing through each corner of the two plates UPL and LPL and fastened to each other. For example, the fastening mechanism can include four bolts and four nuts fastened to pass through the four corners of each of the two plates UPL and LPL.

[0146] The fastening pressure P of the pressing device PDV can be a pressure that reduces the interfacial resistance in the all-solid-state battery 10 and ensures stable performance of the all-solid-state battery 10 during charge and discharge. The fastening pressure P can depend on the construction, size, and other factors of the all-solid-state battery 10. For example, the fastening pressure P can be equal to or less than about 6.0 MPa, about 5.5 MPa, about 5.0 MPa, about 4.5 MPa, about 4.0 MPa, about 3.5 MPa, about 3.0 MPa, about 2.5 MPa, about 2.0 MPa, about 1.5 MPa, or 1.0 MPa. For example, the fastening pressure P can be greater than about 0 MPa, or it can be equal to or greater than about 0.001 MPa, about 0.005 MPa, about 0.01 MPa, about 0.05 MPa, about 0.1 MPa, or 0.5 MPa.

[0147] The all-solid-state battery 10 including the coating layer 220 according to the example embodiments of this disclosure can operate stably even under low clamping pressure P and can have an increased lifespan.

[0148] Even during charging and discharging at both high and low clamping pressures, the coating 220 according to the exemplary embodiments of this disclosure can have small volume changes and maintain a stable lifespan.

[0149] Methods for preparing coating slurry and coating layer Figure 8 A flowchart illustrating a method for preparing a coating slurry according to an example embodiment of the present disclosure is shown. Figure 9 , Figure 10 and Figure 11 It shows Figure 8 The diagram shows the steps of the preparation method.

[0150] Reference Figure 8 A method for preparing a coating slurry according to an example embodiment of the present disclosure may include: preparing a first mixture by mixing a coating material with an adhesive solution including a solvent and a first adhesive (S100); mixing the first mixture using a mixer (S200); subjecting the first mixture to a high-pressure dispersion treatment (S300); and preparing a second mixture by adding a second adhesive to the first mixture (S400).

[0151] Reference Figure 8 and Figure 9 The coating material MAT and the first binder BND1 can be added to a solvent to prepare the first mixture MXT1 (S100). The coating material MAT may include the carbon-based material CCM and metal particles MTP discussed above.

[0152] The coating material may also include additives. For example, the coating material may also include at least one of fillers, coating agents, dispersants, and ionic conductive agents.

[0153] The first binder BND1 can increase the viscosity of the first mixture MXT1, so that the first mixture MXT1 can be prepared in the form of a slurry. For example, the first binder BND1 may include at least one of acrylate binders, polyvinylidene fluoride binders, polyvinylpyrrolidone binders, polyvinyl alcohol binders, and cellulose binders.

[0154] Acrylic adhesives may be or include at least one of, for example, polyacrylic acid (PAA), polymethyl methacrylate, polyisobutyl methacrylate, polyethyl acrylate, polybutyl acrylate, or poly(2-ethylhexyl acrylate).

[0155] Polyvinylidene fluoride (PVDF) adhesives may be or include at least one of, for example, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene), poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), poly(vinylidene fluoride-co-fluoroethylene-hexafluoropropylene), or poly(vinylidene fluoride-co-trichloroethylene). Polyvinylpyrrolidone (PVP) adhesives may be or include, for example, polyvinylpyrrolidone. Polyvinyl alcohol (PVA) adhesives may be or include, for example, polyvinyl alcohol.

[0156] Cellulose-based binders may be or include at least one of, for example, carboxymethyl cellulose (CMC), methyl cellulose (MC), hydroxypropyl cellulose (HPC), methyl hydroxypropyl cellulose (MHPC), ethyl hydroxyethyl cellulose (EHEC), methyl ethyl hydroxyethyl cellulose (MEHEC), or cellulose gum. In an example embodiment, the first binder BND1 may include carboxymethyl cellulose (CMC).

[0157] The first binder BND1 may have desired or improved distributability to uniformly disperse the components of the coating material MAT, and simultaneously or concurrently give the first mixture MXT1 an appropriate or desired viscosity.

[0158] The solvent can be an aqueous solvent or a non-aqueous solvent. In the example embodiment, the solvent can be or include water. In this specification, an aqueous solvent can refer to a solvent that contains water as its main component. For example, an aqueous solvent can include water. In addition, an aqueous solvent may also include at least one of methanol, ethanol, ethylene glycol, diethylene glycol, and glycerol.

[0159] In an example embodiment, the first adhesive BND1 and a solvent may be mixed to form an adhesive solution. The first adhesive BND1 may be present in the adhesive solution in an amount ranging from about 0.5 wt% to about 10 wt%. For example, the amount of the first adhesive BND1 in the adhesive solution may be in the range of about 0.5 wt% to about 5 wt%, about 0.8 wt% to about 3.5 wt%, or about 0.8 wt% to about 3 wt%, or it may be about 1 wt%.

[0160] Reference Figure 8 and Figure 10 The first mixture MXT1 can be mixed using a mixer MXD (S200). In an example embodiment, the mixing process can be carried out using a planetary mixer at a temperature ranging from about 20°C to about 60°C for a duration ranging from about 20 minutes to about 250 minutes. During the mixing process, a binder solution can be added such that the first binder BND1 has an amount ranging from about 1 wt% to about 5 wt% in the first mixture MTX1.

[0161] When the amount of the first binder BND1 in the first mixture MTX1 is less than the above range, the dispersion effect of the metal particles MTP in the dispersion process discussed below may be reduced. When the amount of the first binder BND1 is greater than the above range, the first binder BND1 may be over-adsorbed on the surface of the carbon-based material CCM and the surface of the metal particles MTP, thus hindering lithium-ion migration. Therefore, the internal resistance of the battery may increase.

[0162] The mixing process can give the first mixture MXT1 a viscosity in the range of about 1,000 cps to about 4,000 cps. For example, the viscosity of the first mixture MXT1 can be in the range of about 1,000 cps to about 3,500 cps, about 1,500 cps to about 3,000 cps, about 1,500 cps to about 2,500 cps, or about 2,000 cps to about 2,500 cps.

[0163] When the amount of the first binder BND1 in the first mixture MTX1 falls within the above range, and when the viscosity of the first mixture MTX1 meets the above range, the amount of contact between the first binder BND1 and the coating material MAT can be increased.

[0164] The solid component in the first mixture MTX1 may be present in an amount ranging from about 15 wt% to about 45 wt%. The solid component in the first mixture MTX1 may include the coating material MAT and the first binder BND1. For example, the amount of solid component in the first mixture MTX1 may be in the range of about 15 wt% to about 40 wt%, about 15 wt% to about 35 wt%, about 20 wt% to about 35 wt%, or about 20 wt% to about 30 wt%.

[0165] When the amount of solid components in the first mixture MTX1 deviates from the above range, a solvent can be added during the mixing process to adjust the amount of solid components in the first mixture MTX1.

[0166] Reference Figure 8 and Figure 11 A high-pressure dispersion process (S300) can be performed on the first mixture MXT1. In the high-pressure dispersion step (S300), the high-pressure disperser can perform a high-pressure dispersion process on the first mixture MXT1. Therefore, a dispersion DSP can be obtained.

[0167] Metal particles MTP may be present in the form of blocky aggregates in the first mixture MXT1 mixed by the mixer MXD. Figure 11 The high-pressure disperser shown can break down metal particles (MTP) in the form of bulk aggregates into fine nanoparticles. Figure 11 The high-pressure disperser shown can uniformly or substantially uniformly disperse nano-sized fine metal particles (MTP) in the dispersion DSP.

[0168] For example, a compressor (CPR) can pressurize the first mixture (MXT1) at high pressure. The first mixture (MXT1) can be pressurized at pressures ranging from approximately 2,000 psi to approximately 30,000 psi.

[0169] A high-pressure first mixture MXT1 can be provided into the interaction chamber ITC. The interaction chamber ITC may include a microchannel MCH. The high-pressure first mixture MXT1 can pass through the microchannel MCH.

[0170] A strong shear force can be applied to the first mixture MXT1 passing through the microchannel MCH. Therefore, the metal particles MTP, in the form of bulk aggregates, can be crushed into fine nanoparticles. The first mixture MXT1 can be homogenized. A high-pressure disperser can form a dispersion DSP in which the metal particles MTP are uniformly dispersed in the form of nanoparticles.

[0171] The high-pressure dispersion step (S300) may include repeating the dispersion process two or more times (e.g., about 2 to 10 times). Each dispersion process may be performed for a duration ranging from about 2 hours to about 5 hours. When the number of dispersion steps for the first mixture MXT1 falls within the aforementioned range, the dispersion DSP can have improved dispersibility of the metal particles MTP. With repeated high-pressure dispersion steps (S300), the metal particles MTP can have a reduced average particle size and a narrow size distribution.

[0172] In exemplary embodiments of this disclosure, the number of repetitions discussed above can be adjusted based on the pressure applied to the first mixture MXT1 by the compressor CPR. For example, when the first mixture MXT1 is pressurized at a relatively high pressure (such as 20,000 psi), the dispersion process can be performed twice. For example, when the first mixture MXT1 is pressurized at a relatively low pressure (such as 5,000 psi), the dispersion process can be performed five or more times (e.g., 10 times).

[0173] High-pressure dispersers are not limited to Figure 11 The apparatus shown is not limited to any suitable apparatus capable of performing a high-pressure dispersion process on the first mixture MXT1. For example, a high-pressure disperser may include at least one of Microfludizer (MFD), Jet Mill, Starburst, Nanomizer, G-smasher, Nano Jet Pearl, and Micronox.

[0174] Reference Figure 8 The second binder can be mixed into the dispersion DSP to obtain a second mixture (S400). For example, the prepared second mixture may be in slurry form and may be or include a coating slurry for all-solid-state batteries according to example embodiments of this disclosure.

[0175] The second adhesive may have desired or improved adhesion. For example, the second adhesive may include at least one of rubber-based adhesives, imide-based adhesives, nitrile-based adhesives, acetate-based adhesives, and cyano-based adhesives.

[0176] Imide adhesives may be or include, for example, polyimides or polyamide-imides.

[0177] Nitrile adhesives may be, or include, for example, polyacrylonitrile or acrylonitrile-styrene-butadiene copolymers.

[0178] Acetate-based adhesives may be or include at least one of the following: polyvinyl acetate, polyethylene-covinyl acetate, cellulose acetate, cellulose acetate butyrate, or cellulose acetate propionate.

[0179] Cyano-based binders may be or include, for example, cyanoethyl sucrose.

[0180] In an example embodiment, the second adhesive may be or include a rubber-based adhesive. The second adhesive may be different from the first adhesive BND1. In an example embodiment, the second adhesive may be or include styrene-butadiene rubber (SBR). In another example embodiment, the second adhesive may be or include nitrile rubber (NBR).

[0181] The second adhesive can be provided in a solution state dissolved in a solvent. For example, the solvent can be an aqueous solvent or a non-aqueous solvent. In an example embodiment, the solvent can be or include water.

[0182] The second binder can be mixed into the dispersion DSP. There are no limitations on the mixing method. In an example embodiment, the second binder can be added to the dispersion DSP, and then the mixture can be stirred using a planetary mixer at approximately 20°C to approximately 60°C for approximately 20 minutes to approximately 250 minutes.

[0183] The second binder can be added to the second mixture in an amount ranging from about 0.5 wt% to about 5 wt%. For example, the amount of the second binder in the second mixture can range from about 1 wt% to about 4 wt% or from about 1.5 wt% to about 3 wt%.

[0184] When the amount of the second binder in the second mixture falls within the above range, the second mixture (or coating slurry) can have appropriate or desired adhesive properties and viscosity to increase coating adhesion and dispersion stability.

[0185] The total amount of the first binder and the second binder in the second mixture can be in the range of about 1 wt% to about 10 wt%. When the amount of the first binder and the second binder in the second mixture is less than the above range, the coating material MAT may not be sufficiently dispersed. When the amount of the first binder and the second binder in the second mixture is greater than the above range, the first binder and the second binder may be excessively adsorbed on the surface of the carbon-based material CCM and / or the surface of the metal particles MTP, thereby hindering the migration of lithium ions and increasing the internal resistance of the battery.

[0186] The solid components in the second mixture may include coating material MAT, first adhesive BND1, and second adhesive. For example, the solid components in the second mixture may be present in an amount ranging from about 15 wt% to about 50 wt%, about 15 wt% to about 45 wt%, about 20 wt% to about 45 wt%, or about 20 wt% to about 30 wt%. For example, the second adhesive may be added in the amounts described above so that the amount of solid components in the second mixture falls within the aforementioned range.

[0187] When the amount of solids in the second mixture deviates from the above range, a solvent can be added to adjust the amount of solids in the second mixture. The solvent can be the same as the solvents discussed above. In an example embodiment, the solvent can be an aqueous solvent. For example, the solvent may include water.

[0188] In exemplary embodiments of this disclosure, the second mixture (or coating slurry) may have a relatively low viscosity compared to other slurries having the same amount of solid components. For example, based on measurements of the shear viscosity of a coating slurry for all-solid-state batteries according to this disclosure, the viscosity of the coating slurry can range from about 200 mPa·s to about 1,000 mPa·s (e.g., from about 300 mPa·s to about 700 mPa·s) under conditions of about 20°C and a shear rate of 10 (1 / s).

[0189] Compared to other slurries having the same amount of solid components, the second mixture (or coating slurry) can have relatively desirable or improved dispensability. For example, based on measurements of the shear viscosity of the coating slurry for all-solid-state batteries according to this disclosure, at a temperature of 20°C, the ratio of the thixotropic index (TI), or viscosity at a shear rate of 1 (1 / s), to the viscosity at a shear rate of 10 (1 / s), can be equal to or greater than about 0.2. Specifically, TI can range from about 0.4 to about 0.9.

[0190] The second mixture (or coating slurry) can then be coated onto the negative electrode current collector 210 and dried to form the coating layer 220 according to the present disclosure.

[0191] As discussed above, high-pressure dispersion processes can convert metal particle MTP into Figure 4 The diagram shows fine single-particle LPMs. In the coating layer 220 according to this disclosure, the average particle size (PTS) of the metal particles (MTP) can have a fine size equal to or less than about 100 nm. In the coating layer 220 according to this disclosure, the metal particles (MTP) can have a relatively narrow size distribution (or a standard deviation equal to or less than about 5.0 nm or 3.0 nm). Therefore, the lifetime and performance of the all-solid-state battery including the coating layer 220 according to this disclosure can be improved.

[0192] The present disclosure will now be discussed in detail through examples. However, these exemplary examples are provided to illustrate the present disclosure, and the scope of the present disclosure is not limited to these examples.

[0193] Example 1 1) Silver (Ag) and carbon black are mixed to prepare a coating material. Silver and carbon black are mixed in a weight ratio of 25:75 to form a composition of the coating material.

[0194] 2) Add an aqueous solution of carboxymethyl cellulose (CMC) containing 1 wt% solids to the coating material, and then mix at 25°C for 120 minutes to prepare a first mixture in slurry form. For example, mixing can be performed by stirring the coating material and the CMC aqueous solution at a weight ratio of 43:57.

[0195] Then, in order to adjust the viscosity, additional water was added to finally prepare a first mixture with a solid content of 23 wt% and a viscosity of 1,865 cps.

[0196] 3) Use a microfluidic device (MFD) to perform a high-pressure dispersion process on the first mixture. For example, pressurize the first mixture at 5,000 psi to perform 10 high-pressure dispersion processes. This yields a dispersion.

[0197] 4) After the high-pressure dispersion process, an aqueous dispersion solution containing styrene-butadiene rubber (SBR) is added to the dispersion, and then mixed at 25°C for 60 minutes to prepare a second mixture as a coating slurry. For example, the dispersion and aqueous dispersion solution are mixed by stirring at a weight ratio of 97:3. As a result, a coating slurry with a solid content of 25 wt% is prepared.

[0198] 5) Apply a 20 μm to 30 μm thick coating slurry to the surface of the stainless steel (SUS) current collector using a doctor blade, and then dry the coating in an oven at 80°C. After drying, press the coating to a thickness of 10 μm to 15 μm using a hot roller press at 60°C. The porosity of the coating is approximately 30%. The porosity is obtained using Equation 1 discussed above.

[0199] Example 2 In the high-pressure dispersion process of Example 1, the first mixture was pressurized at 5,000 psi to perform the high-pressure dispersion process seven times. Except for the differences mentioned above, the coating layer was prepared using the same method as in Example 1.

[0200] Example 3 In the high-pressure dispersion process of Example 1, the first mixture was pressurized at 7,000 psi to perform the high-pressure dispersion process seven times. Except for the differences mentioned above, the coating layer was prepared using the same method as in Example 1.

[0201] Example 4 In the high-pressure dispersion process of Example 1, the first mixture was pressurized at 5,000 psi to perform five high-pressure dispersion processes. Except for the differences described above, the coating was prepared using the same method as in Example 1.

[0202] Example 5 In the high-pressure dispersion process of Example 1, the first mixture was pressurized at 7,000 psi to perform five high-pressure dispersion processes. Except for the differences described above, the coating was prepared using the same method as in Example 1.

[0203] Example 6 In the high-pressure dispersion process of Example 1, the first mixture was pressurized at 10,000 psi to perform five high-pressure dispersion processes. Except for the differences described above, the coating was prepared using the same method as in Example 1.

[0204] Example 7 In the high-pressure dispersion process of Example 1, the first mixture was pressurized at 15,000 psi to perform five high-pressure dispersion processes. Except for the differences mentioned above, the coating was prepared using the same method as in Example 1.

[0205] Example 8 In the high-pressure dispersion process of Example 1, the first mixture was pressurized at 7,000 psi to perform three high-pressure dispersion processes. Except for the differences mentioned above, the coating layer was prepared using the same method as in Example 1.

[0206] Example 9 In the high-pressure dispersion process of Example 1, the first mixture was pressurized at 10,000 psi to perform the high-pressure dispersion process three times. Except for the differences mentioned above, the coating layer was prepared using the same method as in Example 1.

[0207] Example 10 In the high-pressure dispersion process of Example 1, the first mixture was pressurized at 15,000 psi to perform three high-pressure dispersion processes. Except for the differences mentioned above, the coating was prepared using the same method as in Example 1.

[0208] Example 11 In the high-pressure dispersion process of Example 1, the first mixture was pressurized at 20,000 psi to perform two high-pressure dispersion processes. Except for the differences described above, the coating was prepared using the same method as in Example 1.

[0209] Comparative Example 1 The coating was prepared using the same method as in Example 1, except that the high-pressure dispersion process in Example 1 was omitted.

[0210] Comparative Example 2 The coating was prepared using the same method as in Example 1, except that in the high-pressure dispersion process of Example 1, the first mixture was pressurized at 5,000 psi to perform the high-pressure dispersion process only once.

[0211] Comparative Example 3 The coating was prepared using the same method as in Example 1, except that in the high-pressure dispersion process of Example 1, the first mixture was pressurized at 7,000 psi to perform the high-pressure dispersion process only once.

[0212] Comparative Example 4 The coating was prepared using the same method as in Example 1, except that in the high-pressure dispersion process of Example 1, the first mixture was pressurized at 10,000 psi to perform the high-pressure dispersion process only once.

[0213] Comparative Example 5 The coating was prepared using the same method as in Example 1, except that, in the high-pressure dispersion process of Example 1, the first mixture was pressurized at 15,000 psi to perform the high-pressure dispersion process only once.

[0214] Comparative Example 6 The coating was prepared using the same method as in Example 1, except that in the high-pressure dispersion process of Example 1, the first mixture was pressurized at 20,000 psi to perform the high-pressure dispersion process only once.

[0215] Comparative Example 7 The coating was prepared using the same method as in Example 1, except that, in the high-pressure dispersion process of Example 1, the first mixture was pressurized at 5,000 psi to perform a three-stage high-pressure dispersion process.

[0216] Table 1 below lists the high-pressure dispersion processes of Examples 1 to 11 and Comparative Examples 1 to 7.

[0217] Table 1:

[0218] Fabrication of the positive electrode layer Preparing LiNi 0.8 Co 0.15 Mn 0.05 O2 (NCM) powder was used as the positive electrode active material. A sulfide-germanium ore type crystal (Li6PS5Cl) solid electrolyte (D...) was used. 50(1 μm or smaller, crystalline) was used as the solid electrolyte. Polytetrafluoroethylene (PTFE, Teflon from DuPont) was prepared as the binder, and carbon black (CB) and carbon nanofibers (CNF) were prepared as conductive materials. The positive electrode active material, solid electrolyte, carbon black, carbon nanofibers and binder were mixed in xylene solvent at a weight ratio of 85.5:10:1.5:1.5:1.5 to form a positive electrode active material composition in sheet form. The mixture was then vacuum dried at 40 °C for 8 hours to produce the positive electrode layer.

[0219] Manufacturing of solid electrolyte layers An acrylamide binder (SX-A334 from Zeon) was added to octyl acetate to prepare a 4 wt% binder solution. The prepared acrylamide binder solution was then added to a sulforaphite-germanium type crystal (Li6PS5Cl solid electrolyte (D... 50 =3μm, crystalline) and mixed using a Thinky Mixer to prepare a slurry. In the slurry, an acrylamide binder is included in an amount of 1.5 parts by weight relative to 98.5 parts by weight of solid electrolyte. The prepared slurry is coated onto a nonwoven fabric using a bar coater and dried in a convection oven at 80°C for 10 minutes to obtain a stack. The stack is then vacuum dried at 70°C for 2 hours.

[0220] Manufacturing of all-solid-state batteries A stack was fabricated by placing a solid electrolyte layer between the positive and negative electrode layers. The fabricated stack was then subjected to isostatic pressing at 490 MPa and 80°C for 60 minutes to manufacture an all-solid-state battery. The solid electrolyte layer was sintered by pressing to improve battery characteristics. The thickness of the sintered solid electrolyte layer was approximately 45 μm. The thickness of the pressed positive electrode active material layer was approximately 120 μm, and the coating thickness was as discussed above.

[0221] The manufactured all-solid-state battery undergoes 10 charge / discharge cycles.

[0222] Experimental Example 1: Analysis of Coating Layers (1) Analysis of silver particle aggregates in the coating layer The number of silver particle aggregates was counted by analyzing the coatings according to the example and comparative examples using scanning electron microscopy (SEM), and the results are shown below. Figure 12 In this context, aggregates are defined as silver particles with a diameter equal to or greater than 200 nm. The definition of aggregates (or a reference for particle size) can vary depending on the state of the silver particles used as the initial coating material.

[0223] Reference Figure 12In Comparative Examples 1 to 7, a relatively large number of bulk aggregates, approximately 100 or more, were observed. In Examples 1 to 11, a considerably small number of bulk aggregates, approximately 80 or fewer, were observed. Therefore, it can be determined that the average particle size of the silver particles is quite small and the size distribution of the silver particles is narrow.

[0224] According to an example embodiment of this disclosure, when the product of the pressure measured in psi and the number of repetitions in a high-pressure dispersion process is greater than 20,000, the silver particles in the coating can have a small size and a narrow distribution.

[0225] (2) Analysis of the average particle size and standard deviation of silver particles in the coating layer Figure 13A and Figure 13B Cross-sectional SEM images and surface SEM images of the coating layer of Example 1 are shown respectively. Figure 14A and Figure 14B The cross-sectional SEM image and surface SEM image of the coating layer shown in Comparative Example 1 are displayed respectively. Figure 15A and Figure 15B The cross-sectional SEM image and surface SEM image of the coating layer shown in Comparative Example 7 are displayed respectively.

[0226] Reference Figure 14A and Figure 14B It can be observed that the silver particles in the coating of Comparative Example 1 have a fairly large size. (Refer to...) Figure 15A and Figure 15B It can be observed that the silver particles in the coating of Comparative Example 7 have relatively large sizes. (Refer to...) Figure 13A and Figure 13B It can be observed that the silver particles in the coating layer of Example 1 have a fairly small size.

[0227] Table 2 below lists the average particle size and standard deviation of the silver particles in the coating in each of Examples 1, Comparative Example 1, and Comparative Example 7.

[0228] Table 2:

[0229] It can be observed that the silver particles in the coating layer of Example 1 have a fairly fine average particle size of 55 nm. It can also be observed that the particle size of the silver particles has a standard deviation of about 40% of the average particle size, and the silver particles have a narrow size distribution.

[0230] It can be observed that the silver particles in the coating of Comparative Example 1 have a fairly large average particle size of 1.25 μm. The particle size of the silver particles has a standard deviation of approximately 120% of the average particle size, and the silver particles exhibit a wide size distribution.

[0231] It can be observed that the silver particles in the coating of Comparative Example 7 have a relatively large average particle size of 180 nm. The particle size of the silver particles exhibits a 95% standard deviation of the average particle size and a wide size distribution. However, it can be determined that, unlike Comparative Example 1, the high-pressure dispersion process resulted in a smaller average particle size and a narrower size distribution compared to Comparative Example 1.

[0232] (3) Analysis of the average size and standard deviation of pores in the coating layer Figure 16 A cross-sectional SEM image and a carbon energy dispersive X-ray spectroscopy (EDS) mapping image of the coating layer in Example 1 are shown. Figure 17 The cross-sectional SEM image and carbon EDS mapping image of the coating layer in Comparative Example 1 are shown. Figure 18 A cross-sectional SEM image of the coating layer in Comparative Example 7 is shown.

[0233] Analyzing with ImageJ Figures 16 to 18 The data is used to measure the area of ​​the hole, and the hole size is obtained based on the diameter of a circle with a hole of the same area.

[0234] Reference Figure 17 It can be observed that the pores in the coating of Comparative Example 1 have a fairly large size. The average pore size is greater than 1 μm. The standard deviation of the pore size is approximately 1.5 μm.

[0235] Reference Figure 18 It can be observed that the pores in the coating of Comparative Example 7 have relatively large sizes. The average pore size is greater than 150 nm. The standard deviation of the pore size is approximately 145 nm.

[0236] Reference Figure 16 It can be observed that the pores in the coating layer of Example 1 have a fairly small size. The average pore size is less than 60 nm. The standard deviation of the pore size is about 25 nm.

[0237] It can be observed that the coating layer of Example 1 has a relatively small average particle size of silver particles and a relatively narrow size distribution of silver particles. Additionally, the pores of Example 1 have a relatively small average size and a relatively narrow size distribution. This is likely because the pressure and number of repetitions of the high-pressure dispersion process were appropriately selected in the manufacturing process of Example 1.

[0238] For example, it can be determined that when the high-pressure dispersion process is designed such that the product of the pressure measured in psi and the number of repetitions is greater than 20,000, the coating can be formed with the desired silver particle size and pore size.

[0239] Experimental Example 2: Evaluation of Negative Electrode Layer and All-Solid-State Battery The evaluation included the lifetime of all-solid-state batteries with negative electrode layers according to Example 1, Comparative Example 1, and Comparative Example 7.

[0240] Lifetime evaluation was conducted by setting the pressing device used for the all-solid-state battery to a clamping pressure of 1 MPa. The evaluation was performed as follows: the all-solid-state battery was charged at a constant current of 0.33C until the voltage reached 4.25V, then discharged at 0.33C until the voltage reached 2.5V, and this charge-discharge cycle was repeated. Lifetime (charge-discharge efficiency) was calculated according to Equation 3. The lifetime evaluation results are listed in Table 3 below.

[0241] Equation 3: Lifetime = (100th discharge capacity / initial discharge capacity) × 100.

[0242] Table 3:

[0243] Referring to Table 3, it can be determined that, compared to Comparative Examples 1 and 7, the all-solid-state battery including the coating according to Example 1 has the desired or improved lifetime characteristics. This is likely because the silver particles (or pores) in the coating have a relatively small average size and a relatively narrow standard deviation.

[0244] In the negative electrode for an all-solid-state battery according to an example of this disclosure, the metal particles in the coating layer can have a relatively small particle size and a relatively narrow distribution. Therefore, the negative electrode according to an example of this disclosure can improve the lifetime and performance of the all-solid-state battery.

[0245] Although some exemplary embodiments of the present disclosure have been discussed with reference to the accompanying drawings, it is understood that various changes in form and detail may be made therein without departing from the spirit and scope of the present disclosure. Therefore, it is understood that the exemplary embodiments described above are illustrative in all respects and not restrictive.

Claims

1. A negative electrode for an all-solid-state battery, the negative electrode comprising: Negative electrode current collector; as well as A coating layer is applied to the negative electrode current collector. The coating layer comprises carbonaceous materials and metal particles. The metal particles include lithium-loving metals. The average particle size of the metal particles is in the range of 10 nm to 200 nm, and Wherein, the standard deviation of the particle size of the metal particles is equal to or less than 50% of the average particle size.

2. The negative electrode according to claim 1, wherein, The coating layer also includes pores. The average size of the pores is in the range of 10 nm to 60 nm, and Wherein, the standard deviation of the hole is equal to or less than 50% of the average size of the hole.

3. The negative electrode according to claim 2, wherein, The porosity of the coating layer gradually increases with the distance from the negative electrode current collector.

4. The negative electrode according to claim 1, wherein, The density of the metal particles in the coating layer gradually decreases as the distance from the negative electrode current collector increases.

5. The negative electrode according to claim 1, wherein, The average particle size of the carbon-based material is greater than the average particle size of the metal particles.

6. The negative electrode according to claim 1, wherein, The carbon-based materials include at least one of carbon black, carbon nanotubes, acetylene black, furnace black, Ketjen black, graphene, and combinations thereof.

7. The negative electrode according to claim 1, wherein, The metal particles include at least one of silver, magnesium, bismuth, gold, platinum, zinc, and combinations thereof.

8. The negative electrode according to claim 1, wherein the negative electrode further comprises a lithium metal layer between the negative electrode current collector and the coating layer.

9. The negative electrode according to claim 1, wherein, The thickness of the coating layer is in the range of 5 μm to 20 μm.

10. A method for preparing a coating slurry, the method comprising the following steps: A first mixture is formed by adding carbonaceous materials, metal particles, and a first binder to a solvent; The first mixture is mixed using a mixer; as well as A dispersion is formed by subjecting the first mixture to a high-pressure dispersion process using a high-pressure disperser. The high-pressure dispersion process includes the following steps: pressurizing the first mixture at a pressure ranging from 2,000 psi to 30,000 psi; and passing the pressurized first mixture through microchannels. The average particle size of the metal particles in the dispersion is in the range of 10 nm to 200 nm, and Wherein, the standard deviation of the particle size of the metal particles in the dispersion is equal to or less than 50% of the average particle size.

11. The method according to claim 10, wherein, Perform the high-pressure dispersion process two or more times.

12. The method according to claim 11, wherein, The high-pressure dispersion process is designed such that the product of the pressure, measured in psi, and the number of repetitions is greater than 20,000.

13. The method of claim 10, further comprising adding a second binder to the dispersion.

14. The method of claim 10, wherein, The high-pressure dispersion process is performed to pulverize the metal particles in the first mixture into nanoparticles.

15. The method according to claim 10, wherein, The carbon-based materials include at least one of carbon black, carbon nanotubes, acetylene black, furnace black, Ketjen black, graphene, and combinations thereof.

16. The method of claim 10, wherein, The metal particles include at least one of silver, magnesium, bismuth, gold, platinum, zinc, and combinations thereof.

17. The method according to claim 10, wherein, The first adhesive includes at least one of acrylate adhesives, polyvinylidene fluoride adhesives, polyvinylpyrrolidone adhesives, polyvinyl alcohol adhesives, cellulose adhesives, and combinations thereof.

18. An all-solid-state battery, the all-solid-state battery comprising: The negative electrode according to any one of claims 1 to 9; Positive electrode; as well as A solid electrolyte layer is located between the negative electrode and the positive electrode.

19. The all-solid-state battery according to claim 18, wherein, The positive electrode includes: Positive electrode current collector; and The positive electrode active material layer is located on the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material and a solid electrolyte.

20. The all-solid-state battery according to claim 18, wherein, The solid electrolyte layer comprises Li 7-a-c M a PS 6-c X c The compound represented is a sulfide-germanium type compound. Wherein, X includes at least one of Cl, Br, and combinations thereof. Wherein, M includes at least one of Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn and combinations thereof, and Each of "a" and "c" is a real number in the range of 0 to 2.

Images