Method for manufacturing positive electrode for all-solid-state battery and positive electrode for all-solid-state battery manufactured using the same

Abstract

The present disclosure relates to a method of manufacturing a positive electrode for a full solid-state battery and a positive electrode for a full solid-state battery manufactured using the method. The method includes the steps of: preparing a positive electrode mixture including a positive electrode active material layer, a solid electrolyte, a conductive material, and a fibrous binder; forming the positive electrode active material layer; and attaching the positive electrode active material layer on a current collector. The positive electrode active material layer has a loading level in the range of about 25 mg / cm 2 to about 100 mg / cm 2 .

Description

[0001] This patent application claims priority to Korean Patent Application No. 10-2024-0173065, filed on November 28, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to a method for manufacturing a positive electrode for an all-solid-state battery, a positive electrode for an all-solid-state battery manufactured using the method, and an all-solid-state battery including the positive electrode. Background Technology

[0003] Driven by increasing demand, there is active development of batteries with high energy density and stability. For example, lithium-ion batteries are being commercialized not only in information-related devices and communication equipment, but also in sectors such as automobiles. In the automotive industry, safety is paramount because it is related to protecting human life.

[0004] Typically, all-solid-state batteries have been proposed, in which a solid electrolyte is used instead of a liquid electrolyte. All-solid-state batteries do not use flammable organic dispersants, thus significantly reducing the likelihood of fire and explosion even in the event of a short circuit. Therefore, such all-solid-state batteries offer improved safety compared to lithium-ion batteries that use liquid electrolytes. Summary of the Invention

[0005] This disclosure describes a method for manufacturing a thick positive electrode for all-solid-state batteries using a solvent-free dry process. Therefore, processability and productivity during the manufacturing of all-solid-state batteries can be improved.

[0006] This disclosure also describes a positive electrode for all-solid-state batteries having desired or improved ionic conductivity and capacity.

[0007] Example embodiments of this disclosure may include a method for manufacturing a positive electrode for an all-solid-state battery. The method may include the steps of: preparing a positive electrode mixture comprising a positive electrode active material, a solid electrolyte, a conductive material, and a fibrous binder; forming a positive electrode active material layer by rolling the positive electrode mixture using multiple rolls; and attaching the positive electrode active material layer to one or both sides of a positive electrode current collector. The positive electrode active material layer attached to one side of the positive electrode current collector may have a concentration of approximately 25 mg / cm³. 2 Approximately 100 mg / cm 2 The load level is within the range.

[0008] Exemplary embodiments of this disclosure may include a positive electrode for an all-solid-state battery, the positive electrode comprising a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector. The positive electrode active material layer may include a positive electrode active material, a solid electrolyte, a conductive material, and a fibrous binder. The loading level of the positive electrode active material layer is approximately 25 mg / cm³. 2 Approximately 100 mg / cm 2 Within this range, the positive electrode for all-solid-state batteries can be manufactured using the methods described above. Attached Figure Description

[0009] The accompanying drawings are included to provide a further understanding of this disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0010] Figure 1 This is a cross-sectional view of an all-solid-state battery.

[0011] Figure 2 This is a plan view of an all-solid-state battery.

[0012] Figure 3 This is a flowchart illustrating a process for manufacturing a positive electrode for an all-solid-state battery according to an exemplary embodiment of the present disclosure.

[0013] Figure 4 This is a conceptual diagram illustrating a hybrid process in a manufacturing method according to an example embodiment of the present disclosure.

[0014] Figure 5 This is a conceptual diagram illustrating a shear-mixing process in a manufacturing method according to an example embodiment of the present disclosure.

[0015] Figure 6 yes Figure 5 An enlarged view of part M1 in the image.

[0016] Figure 7 This is a conceptual diagram illustrating a calendering process in a manufacturing method according to an example embodiment of the present disclosure.

[0017] Figure 8 This is a cross-sectional view of the positive electrode for an all-solid-state battery according to another exemplary embodiment of this disclosure.

[0018] Figure 9 yes Figure 8 An enlarged view of the M2 section.

[0019] Figure 10 and Figure 11 Each graph shows the performance of the positive electrode used in all-solid-state batteries. Detailed Implementation

[0020] To fully understand the structure and effects of this disclosure, 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 this disclosure and to allow those skilled in the art to fully understand its scope.

[0021] In the description, when an element is referred to as being "on" another element, the element may be formed directly on said other element, or an intervening element may exist between them. Additionally, 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.

[0022] Unless otherwise specifically indicated in the specification, singular expressions may also include plural expressions. Furthermore, unless otherwise specifically indicated, the phrase "A or B" may indicate "A but not B," "B but not A," and "A and B." The terms "including / comprise" and / or variations thereof used in the specification do not exclude the presence or addition of one or more other components.

[0023] In the specification, the term "combination of them" may refer to mixtures, stacks, complexes, copolymers, alloys, blends, or reaction products.

[0024] 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%.

[0025] Figure 1 This is a cross-sectional view of an all-solid-state battery. Figure 2 This is a plan view of an all-solid-state battery.

[0026] Reference Figure 1 The all-solid-state battery 10 may include a positive electrode layer 100, a negative electrode layer 200 facing 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, the exemplary embodiments disclosed herein are not limited thereto. The all-solid-state battery 10 may also include additional functional layers (such as an adhesion enhancement layer, for example) 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.

[0027] 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. Although not shown, the positive electrode active material layer 120 may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0028] The positive electrode current collector 110 can provide a substrate on which a positive electrode active material layer 120 is disposed. The positive electrode current collector 110 may include, for example, a plate or foil containing at least one of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) and alloys thereof.

[0029] For example, with Figure 1 As shown in the example embodiments of this disclosure, the positive electrode current collector 110 may be omitted. 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 provided between the positive electrode current collector 110 and the positive electrode active material layer 120.

[0030] The positive electrode active material may include materials capable of reversibly inserting / deintercalating lithium ions. The positive electrode active material may include multiple particles. The positive electrode active material may include, for example, at least one of the following: lithium transition metal oxides, such as 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, and lithium iron phosphate; nickel sulfide; copper sulfide; lithium sulfide; iron oxide; vanadium oxide; etc., but not necessarily limited thereto. The positive electrode active material may be included individually or as a mixture of two or more of them.

[0031] Lithium transition metal oxides can be or include, for example, compounds represented by any 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 Ni1-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 Ni b 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-fJ2(PO4)3 (where 0 ≤ f ≤ 2); Li 3-f Fe2(PO4)3 (where 0 ≤ f ≤ 2); and LiFePO4. In such compounds, the capital letter "A" is or includes at least one of Ni, Co, Mn, and combinations thereof, the capital letter "B" is or includes at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof, the capital letter "D" is or includes at least one of O, F, S, P, and combinations thereof, the capital letter "F" is or includes at least one of F, S, P, and combinations thereof, the capital letter "G" is or includes at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof, the capital letter "Q" is or includes at least one of Ti, Mo, Mn, and combinations thereof, the capital letter "I" is or includes at least one of Cr, V, Fe, Sc, Y, and combinations thereof, and the capital letter "J" is or includes at least one of V, Cr, Mn, Co, Ni, Cu, and combinations thereof.

[0032] 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 above lithium transition metal oxides. The "layered rock salt-type structure" is, for example, a structure in which oxygen atom layers and metal atom layers are alternately and regularly arranged in the <111> direction of the cubic rock salt-type structure, so that each atomic layer can form a two-dimensional plane. The "cubic rock salt structure" refers to the sodium chloride-type (NaCl-type) structure as a type of crystal structure. For example, it refers to a structure in which face-centered cubic lattices (fcc) formed by respective cations and anions are offset by about 1 / 2 of the edges of the unit lattice from each other. The lithium transition metal oxide having such a layered rock salt-type structure may be or include, for example, 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) (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 energy density of the all-solid-state battery 10 can be increased and the thermal stability can be improved.

[0033] The compounds included in the positive electrode active material can be covered by a coating layer (not shown). The positive electrode active material can include a mixture of the above-mentioned compounds and compounds to which the coating layer has been added. For example, the coating layer added to the surface of the positive electrode active material can include, for example, oxides, hydroxides, hydroxyoxides, oxycarbonates, or hydroxycarbonates of the following coating elements. The compounds constituting such a coating layer can be amorphous or crystalline. The coating elements included in the coating layer can include at least one of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, and combinations thereof. The coating layer can include, for example, Li₂O-ZrO₂ (LZO). The method of forming the coating layer can be determined within a range that does not negatively affect the properties of the positive electrode active material. The method of forming the coating layer can include, for example, spraying, dipping, etc.

[0034] When the positive electrode active material includes, for example, a ternary lithium transition metal oxide (such as NCA or NCM) containing Ni, the capacity density of the all-solid-state battery 10 increases, thus reducing metal dissolution of the positive electrode active material during the state of charge. As a result, the cycle characteristics of the all-solid-state battery 10 during the state of charge can be improved. "Cycle characteristics" refers to the degree of degradation of the all-solid-state battery 10 caused by charging / discharging. An all-solid-state battery 10 with high cycle characteristics can have a smaller degree of degradation caused by charging / discharging, while an all-solid-state battery 10 with low cycle characteristics can have a larger degree of degradation caused by charging / discharging.

[0035] The positive electrode active material can have a particle shape such as spheres, ellipsoids, etc. There are no particular limitations on the particle size and amount of the positive electrode active material. In an example embodiment, the positive electrode active material is polycrystalline and may include secondary particles formed by the aggregation of at least two primary particles. For example, the secondary particles may include multiple primary particles aggregated together. The secondary particles may have a generally spherical or elliptical shape.

[0036] Solid electrolytes can be dispersed among the active materials of the positive electrode. The solid electrolyte dispersed among the active materials of the positive electrode can have a particulate shape. Solid electrolytes dispersed among the active materials of the positive electrode can include sulfide-based solid electrolytes with desired or improved ionic conductivity. Sulfide-based solid electrolytes can include, for example, Li₂S-P₂S₅, Li₂S-P₂S₅-LiX (where X is 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, and Li₂S-P₂S₅-Z. m S n (m and n are positive numbers, and the uppercase letter "Z" is one or more of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are positive numbers, and the uppercase letter "M" is one or more of P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) and Li 7-x PS 6-x I x At least one of (0≤x≤2).

[0037] Sulfide solid electrolytes may be or include silver-germanium sulfide compounds, such as Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) and Li 7-x PS 6-x I xOne or more of the following (0 ≤ x ≤ 2). For example, sulfide-based solid electrolytes can be or include argillium sulfide compounds, including one or more of Li6PS5Cl, Li6PS5Br, and Li6PS5I. Arganium sulfide solid electrolytes can have a density in the range of about 1.5 g / cc to about 2.0 g / cc. Because argillium sulfide solid electrolytes have a density in the range of about 1.5 g / cc or greater, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuits of the solid electrolyte film due to lithium dendrite formation can be reduced or prevented. The solid electrolyte can have an elastic modulus in the range of, for example, about 15 GPa to about 35 GPa.

[0038] The solid electrolyte included in the positive electrode active material layer 120 may have a smaller median average particle size (D50) than the median average particle size (D50) of the solid electrolyte included in the solid electrolyte layer 300, which will be described below. For example, the median average particle size (D50) of the solid electrolyte included in the positive electrode active material layer 120 may be equal to approximately 90% or less, approximately 80% or less, approximately 70% or less, approximately 60% or less, approximately 50% or less, approximately 40% or less, approximately 30% or less, or approximately 20% or less of the median average particle size (D50) of the solid electrolyte included in the solid electrolyte layer 300. For example, the median average particle size (D50) may be the median particle size measured using a laser particle size distribution analyzer.

[0039] The positive electrode active material layer 120 may include a conductive material. The conductive material exhibits conductivity without causing chemical changes in the all-solid-state battery 10, thus increasing the conductivity of both 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.

[0040] The positive electrode active material layer 120 may further include an adhesive. The adhesive may be configured to bond the positive electrode active material, solid electrolyte, conductive material, etc., to each other within the positive electrode active material layer 120. The adhesive may include a material configured to improve the bonding force between the positive electrode active material layer 120 and the positive electrode current collector 110. The adhesive may include at least one of, for example, polyvinylidene fluoride, styrene-butadiene rubber (SBR), polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, poly(methyl methacrylate), etc.

[0041] According to exemplary embodiments of this disclosure, the binder for the positive electrode active material layer 120 may be or include binders used in dry processes. The binder may be, but is not limited to, at least one of polyvinylidene fluoride, styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, poly(methyl methacrylate), etc.

[0042] Based on the total weight parts of the positive electrode active material, solid electrolyte, conductive material, and binder, the positive electrode active material layer 120 may include a positive electrode active material in an amount ranging from about 85 parts by weight to about 92 parts by weight. Based on the total weight parts of the positive electrode active material, solid material, conductive material, and binder, the positive electrode active material layer 120 may include a binder in an amount ranging from about 0.5 parts by weight to about 1.5 parts by weight.

[0043] Based on 100 parts by weight of solid electrolyte, the positive electrode active material layer 120 may include a conductive material in an amount ranging from about 1 part by weight to about 50 parts by weight. When the positive electrode active material layer 120 includes less than about 1 part by weight of conductive material based on 100 parts by weight of solid electrolyte, the proportion of conductive material decreases, and therefore the conductivity of the positive electrode active material layer 120 may decrease. When the positive electrode active material layer 120 includes more than about 50 parts by weight of conductive material based on 100 parts by weight of solid electrolyte, the proportion of conductive material is quite high, and therefore it may not be possible to properly form a coating layer covering the surface of the solid electrolyte.

[0044] In addition to the positive electrode active material, solid electrolyte, conductive material and binder, the positive electrode active material layer 120 may also include additives, such as at least one of fillers, coating agents and dispersants and ionic conductive additives.

[0045] The negative electrode layer 200 may include a negative electrode current collector 210 and a negative electrode coating layer 220 on the negative electrode current collector 210. The negative electrode current collector 210 may provide a substrate on which the negative electrode coating layer 220 is disposed. The negative electrode current collector 210 may include a material that is substantially non-reactive with lithium, i.e., a material that does not form both an alloy and a compound with lithium. For example, the negative electrode current collector 210 may include at least one metal, such as or including at least one of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The negative electrode current collector 210 may have a thickness ranging from about 1 μm to about 20 μm (e.g., about 5 μm to about 15 μm, and for example, about 7 μm to about 10 μm).

[0046] The negative electrode current collector 210 can be formed using one of the metals described above, or it can include an alloy or coating material of two or more metals. The negative electrode current collector 210 can have, for example, a plate or foil shape. For example, in the exemplary embodiment, the negative electrode current collector 210 can be omitted.

[0047] The negative electrode coating 220 allows lithium metal to grow between the negative electrode coating 220 and the negative electrode current collector during charging of the all-solid-state battery. The negative electrode coating 220 can form a protective layer for the lithium metal and can simultaneously or concurrently reduce or suppress dendrite precipitation and growth.

[0048] The negative electrode coating 220 may include metals and carbon. For example, the negative electrode coating 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), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The negative electrode coating 220 may include at least one carbon, such as or including at least one selected from carbon black, acetylene black, furnace black, Ketjen black, and graphene. In an example embodiment, the negative electrode coating 220 may include a mixture of carbon black and silver (Ag).

[0049] In addition to metals and carbon, the negative electrode coating layer 220 may also include other additives. The negative electrode coating layer 220 may also include, for example, at least one additive, such as or including at least one of binders, fillers, coating agents, dispersants, and ionic conductive additives.

[0050] The negative electrode coating layer 220 can have a thinner thickness than the positive electrode active material layer 120. The thickness of the negative electrode coating layer 220 can, for example, be in the range of about 50% or less, about 40% or less, about 30% or less, about 20% or less, about 10% or less, or about 5% or less of the thickness of the positive electrode active material layer 120. The negative electrode current collector 210 can have a thickness in the range of, for example, about 1 μm to about 20 μm, about 2 μm to about 10 μm, or about 3 μm to about 7 μm. When the thickness of the negative electrode coating layer 220 is too thin, lithium dendrites formed between the negative electrode coating layer 220 and the negative electrode current collector 210 may cause the negative electrode coating layer 220 to collapse, which may reduce the cycle characteristics of the all-solid-state battery 10. When the thickness of the negative electrode coating layer 220 increases significantly, the energy density of the all-solid-state battery 10 decreases and the internal resistance of the all-solid-state battery increases due to the negative electrode coating layer 220, so the cycle characteristics of the all-solid-state battery 10 may decrease.

[0051] For example, although not shown, a carbon layer may also be included to improve the adhesion between the negative electrode coating layer 220 and the solid electrolyte layer 300.

[0052] 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 ionic conductivity. The solid electrolyte in the solid electrolyte layer 300 may be the same as or different from any of the materials included in the solid electrolyte in the aforementioned positive electrode active material layer 120.

[0053] 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.

[0054] The second solid electrolyte layer 320 can be in direct contact with the negative electrode coating layer 220. Therefore, the second solid electrolyte layer 320 can reduce or suppress the formation of lithium dendrites between the negative electrode coating layer 220 and the negative electrode current collector 210. The second solid electrolyte layer 320 can effectively reduce or suppress side reactions of the negative electrode. Therefore, the all-solid-state battery 10 according to this disclosure can have improved battery performance.

[0055] The solid electrolyte in the solid electrolyte layer 300 can have a particle shape, such as spherical or elliptical.

[0056] The solid electrolyte in the solid electrolyte layer 300 may include a sulfide-based solid electrolyte. The solid electrolyte in the solid electrolyte layer 300 may be amorphous, crystalline, or a mixture of amorphous and crystalline states. Furthermore, the solid electrolyte may be a material comprising at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements, such as those found in the aforementioned sulfide-based solid electrolyte materials. For example, the solid electrolyte may be a material comprising Li₂S-P₂S₅. When a material comprising Li₂S-P₂S₅ is included as the sulfide-based solid electrolyte material in the solid electrolyte, the mixing ratio of Li₂S and P₂S₅ (Li₂S:P₂S₅) is, for example, in the range of about 50:50 to about 90:10.

[0057] In an example embodiment, the solid electrolyte in the solid electrolyte layer 300 may be or include Li 7- a M a PS 6-c X c A sulfide-germanium ore type compound. Here, X can be or include at least one of Cl, Br and combinations thereof; M can be or include at least one of Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn and combinations thereof, and a and c are both real numbers in the range of 0 to 2.

[0058] The sulfide-germanium ore type solid electrolyte has a density in the range of about 1.5 g / cc to about 2.0 g / cc. Because the sulfide-germanium ore type solid electrolyte has a density of about 1.5 g / cc or greater, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuits of the solid electrolyte film caused by lithium dendrite formation can be reduced or prevented. The solid electrolyte in the solid electrolyte layer 300 has an elastic modulus in the range of, for example, about 15 GPa to about 35 GPa.

[0059] The solid electrolyte layer 300 may also include an adhesive. The adhesive included in the solid electrolyte layer 300 is, or includes, at least one of, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited thereto. The adhesive of the solid electrolyte layer 300 may be the same as or different from the adhesive included in the positive electrode active material layer 120 or the adhesive included in the negative electrode coating layer 220.

[0060] Return to reference Figure 1 The first solid electrolyte layer 310 may have a first thickness t1, and the second solid electrolyte layer 320 may have a second thickness t2. The solid electrolyte layer 300 may have a third thickness T. The first thickness t1 and the second thickness t2 may be different from each other. The second thickness t2 may be greater than the first thickness t1.

[0061] The smaller the thickness of the solid electrolyte layer 300, the higher its energy density. However, conversely, reducing or suppressing the formation of lithium dendrites that can lead to short circuits can be challenging.

[0062] In solid electrolytes, voids may be generated at the interface between the solid electrolyte layer and the electrode, which may act as interfacial resistance and lead to the degradation of battery performance.

[0063] Interfacial resistance can be reduced by applying pressure to both the electrodes and the solid electrolyte layer. In an example embodiment, because sulfide-based solid electrolytes have mechanically flexible properties and high ionic conductivity, an all-solid-state battery with improved interfacial resistance can be fabricated by applying pressure.

[0064] In the exemplary embodiments of this disclosure, the positive electrode layerThe positive electrode layer 100 and the negative electrode layer 200 may include a pressing step during the manufacturing process. In an example embodiment of this embodiment, different pressures may be applied to the positive electrode layer 100 and the negative electrode layer 200 respectively, or different pressures may be applied to at least one of the positive electrode layer 100 and the negative electrode layer 200, during the pressing step. In an example embodiment of this embodiment, the positive electrode layer 100 may be manufactured by applying a relatively higher pressure to it compared to the negative electrode layer 200. For example, when the positive electrode active material and the negative electrode active material comprise nanoscale particles, the contact area with the solid electrolyte is increased, thus improving the interfacial resistance. In an exemplary embodiment, the positive electrode active material is polycrystalline to improve adhesion to the electrode, capacity characteristics, and lifetime characteristics, and may include secondary particles in which at least two primary particles aggregate. In this case, the interfacial resistance between the positive electrode layer 100 and the first solid electrolyte layer 310 may be greater than the interfacial resistance between the negative electrode layer 200 and the second solid electrolyte layer 320, so the positive electrode laminate may be manufactured by applying a pressure higher than that of the negative electrode laminate. However, the example embodiments of this disclosure are not limited thereto. For various reasons, the positive electrode layer 100 and the negative electrode layer 200 can be manufactured by a pressing process in which different pressures are applied to them respectively.

[0065] In exemplary embodiments of this disclosure, process-related problems that may arise from differences in the interface resistance between the positive electrode layer 100 and the first solid electrolyte layer 310 and the negative electrode layer 200 and the second solid electrolyte layer 320 can be addressed or resolved by dividing the solid electrolyte layer 300 into a first solid electrolyte layer 310 and a second solid electrolyte layer 320. For example, the method for manufacturing an all-solid-state battery described below can provide an all-solid-state battery manufactured by applying different pressures to the positive electrode laminate and the negative electrode laminate, respectively.

[0066] In an exemplary embodiment of this disclosure, the solid electrolyte layer 300 is divided into a first solid electrolyte layer 310 and a second solid electrolyte layer 320, and the thicknesses of the first solid electrolyte layer 310 and the second solid electrolyte layer 320 are each adjusted differently, thereby increasing the energy density and reducing or suppressing the formation of lithium dendrites in the negative electrode. Therefore, an all-solid-state battery 10 with reduced short-circuit risk, improved shock stability, and high energy density can be provided.

[0067] The ratio t2 / t1 of the second thickness t2 to the first thickness t1 can be in the range of about 1 to about 20. For example, the ratio t2 / t1 can be in the range of about 2 to about 15, about 4 to about 11, or about 4.5 to about 5.5. When the ratio t2 / t1 of the second thickness t2 to the first thickness t1 falls within the above range, the formation of lithium dendrites is reduced or suppressed, while the energy density increases, thus providing an all-solid-state battery 10 with reduced short-circuit risk, improved shock stability, and high energy density.

[0068] The first thickness t1 can be in the range of about 30 μm or less. For example, the first thickness t1 can be about 25 μm or less, about 20 μm or less, about 14 μm or less, or about 10 μm or less. The first thickness t1 can also be in the range of about 0.1 μm or greater. For example, the first thickness t1 can be about 1 μm or greater, about 2 μm or greater, about 4 μm or greater, or about 5 μm or greater. When the first thickness t1 exceeds the above range, the energy density of the all-solid-state battery 10 may decrease. When the first thickness t1 is less than the above range, the first thickness t1 is smaller than the diameter of the active material particles in the positive electrode, and therefore it may be difficult to form an interface.

[0069] The second thickness t2 can be in the range of about 30 μm or greater. For example, the second thickness t2 can be about 35 μm or greater, about 40 μm or greater, about 45 μm or greater, about 50 μm or greater, about 55 μm or greater, or about 60 μm or greater. The second thickness t2 can also be in the range of about 120 μm or less. For example, the second thickness t2 can be about 90 μm or less, about 60 μm or less. When the second thickness t2 is less than the above range, reducing or suppressing the formation of lithium dendrites in the negative electrode may be challenging, and therefore there may be a risk of short circuit. When the second thickness t2 is greater than the above range, the energy density of the all-solid-state battery 10 may decrease.

[0070] The third thickness T can be in the range of about 120 μm or less. For example, the third thickness T can be about 90 μm or less, or about 60 μm or less. The third thickness T can also be in the range of about 10 μm or more. For example, the third thickness T can be about 30 μm or more, or about 50 μm or more. When the third thickness T is greater than the above ranges, the energy density of the all-solid-state battery 10 may decrease.

[0071] Reference Figure 1 and Figure 2 The areas of the positive electrode layer 100 and the negative electrode layer 200 can be different from each other. For example, the area of ​​the negative electrode layer 200 can be larger than the area of ​​the positive electrode layer 100. The positive electrode layer 100 can be substantially completely superimposed on the negative electrode layer 200 within the negative electrode layer 200.

[0072] In an example embodiment, the first solid electrolyte layer 310 may have substantially the same area as the positive electrode layer 100. In an example embodiment, the second solid electrolyte layer 320 may have substantially the same area as the negative electrode layer 200.

[0073] Reference Figure 1 and Figure 2 The first solid electrolyte layer 310 may have a first width W1 in the first direction D1. The second solid electrolyte layer 320 may have a second width W2 in the first direction D1. The first width W1 may be smaller than the second width W2.

[0074] The difference between the second width W2 and the first width W1 can be about 10 mm or less. For example, the difference between the second width W2 and the first width W1 can be in the range of about 8 mm or less, about 5 mm or less, or 3 mm or less. The difference between the second width W2 and the first width W1 can also be in the range of about 0.1 mm or more, about 0.5 mm or more, or about 1 mm or more. When the difference exceeds the above range, the size of the positive electrode layer 100 becomes relatively small, so the discharge capacity may decrease and the energy density of the all-solid-state battery 10 may decrease. When the difference is less than the above range, reducing or suppressing the formation of lithium dendrites in the negative electrode may be challenging, and therefore there may be a risk of short circuit.

[0075] The ratio W2 / W1 of the second width W2 to the first width W1 can be in the range of about 1 to about 1.6. For example, the ratio W2 / W1 of the second width W2 to the first width W1 can be about 1 to about 1.5, about 1 to about 1.4, about 1 to about 1.3, about 1 to about 1.2 or about 1 to about 1.1.

[0076] When the ratio (W2 / W1) of the second width W2 to the first width W1 exceeds the above range, the energy density of the all-solid-state battery 10 may decrease.

[0077] Reference Figure 1 and Figure 2 The first solid electrolyte layer 310 may have a third width W3 in the second direction D2. The second solid electrolyte layer 320 may have a fourth width W4 in the second direction D2. The third width W3 may be smaller than the fourth width W4.

[0078] The difference between the third width W3 and the fourth width W4 can be in the range of about 10 mm or less. For example, the difference between the third width W3 and the fourth width W4 can be about 8 mm or less, about 5 mm or less, or 3 mm or less. The difference between the fourth width W4 and the third width W3 can also be in the range of about 0.1 mm or more, about 0.5 mm or more, or about 1 mm or more. When the difference exceeds the above range, the size of the positive electrode layer 100 becomes relatively small, so the discharge capacity may decrease and the energy density of the all-solid-state battery 10 may decrease. When the difference is less than the above range, reducing or suppressing the formation of lithium dendrites in the negative electrode may be challenging, and therefore there may be a risk of short circuit.

[0079] The ratio W4 / W3 of the fourth width W4 to the third width W3 can be in the range of about 1 to about 1.6. For example, the ratio W4 / W3 of the fourth width W4 to the third width W3 can be in the range of about 1 to about 1.5, about 1 to about 1.4, about 1 to about 1.3, about 1 to about 1.2 or about 1 to about 1.1.

[0080] When the ratio W4 / W3 of the fourth width W4 to the third width W3 exceeds the above range, the energy density of the all-solid-state battery 10 may decrease.

[0081] Figure 3 This is a flowchart illustrating a method for manufacturing a positive electrode for an all-solid-state battery according to an exemplary embodiment of the present disclosure. (Refer to...) Figure 3 A method for manufacturing a positive electrode for an all-solid-state battery may include: preparing a positive electrode mixture comprising a positive electrode active material, a solid electrolyte, a conductive material and a fibrous binder (S100); shearing and mixing the positive electrode mixture (S200); forming a positive electrode active material layer by rolling the positive electrode mixture using multiple rolls (S300); and attaching the positive electrode active material layer to a positive electrode current collector (S400).

[0082] The preparation of a positive electrode mixture comprising a positive electrode active material, a solid electrolyte, a conductive material, and a fibrous binder (S100) can be carried out using, for example, a stirrer. Based on the total weight of the positive electrode mixture, the amount of the solid electrolyte can range from about 5 wt% to about 30 wt%, the amount of the positive electrode active material can range from about 70 wt% to about 95 wt%, and the amount of each of the fibrous binder and the conductive material can range from about 0.5 wt% to about 3 wt%. The positive electrode active material, the solid electrolyte, and the conductive material can be combined with… Figure 1 and Figure 2 The positive electrode active material, solid electrolyte, and conductive material described in [the previous text] are essentially the same or similar. The following sections primarily describe the differences.

[0083] The positive electrode mixture can be mixed under dry conditions without solvent. Alternatively, the positive electrode mixture may include a small amount of solvent, for example, less than about 0.1 ppm. The drying conditions can be completely solvent-free. Positive electrode mixtures manufactured under dry conditions can reduce or suppress deterioration reactions with sulfide-based solid electrolytes. Sulfide-based solid electrolytes can react with moisture and solvents, potentially leading to their degradation. Therefore, the positive electrode for all-solid-state batteries can have desired or improved ionic conductivity.

[0084] Preparing a positive electrode mixture according to an example embodiment of this disclosure may include mixing a positive electrode active material in powder form, a solid electrolyte, a conductive material, and a fibrous binder. Figure 4 This is described in detail in the text.

[0085] Shear-mixed positive electrode mixture (S200) can finely fibrillate fibrous binders and can mix or disperse positive electrode mixtures mixed in powder form.

[0086] Shear mixing can refer to a process where high shear stress accelerates the fibrillation of a fibrous binder included in the positive electrode mixture to achieve microfibrillation, and the microfibrillated binder contains entangled fibers, causing the positive electrode mixture to form a block-like structure with elasticity and ductility. In this case, high shear stress can also achieve a more uniform dispersion of the positive electrode mixture. Figure 5 The shear mixing process described below will be presented in more detail.

[0087] By using multiple roll-calendered positive electrode mixtures to form a positive electrode active material layer (S300), the thickness of the positive electrode active material layer can be made substantially uniform.

[0088] Calendering can refer to a mechanical process that forms an electrode layer by passing a block of positive electrode mixture, which has undergone a shear-mixing process and exhibits elasticity and ductility, through two or more rolls in a substantially uniform amount; and a mechanical process that compresses the electrode layer into a thin layer by passing it through rolls. Calendering can improve the physical properties of the electrode by making the electrode layer substantially equal in thickness and adjusting its density. Calendering can also be a process of producing a high-density positive electrode active material layer by compressing the positive electrode mixture. Furthermore, calendering can increase the mechanical strength of the positive electrode active material layer. A positive electrode active material layer with increased mechanical strength can exhibit the effect of reducing or preventing electrode deformation or separation even after multiple charge and discharge cycles.

[0089] The calendering process can ensure a substantially uniform thickness during the manufacture of the positive electrode active material. By applying pressure to the positive electrode mixture using multiple rollers, a positive electrode active material layer with a substantially uniform thickness can be manufactured. Furthermore, the calendering process can reduce interfacial resistance during the manufacture of the positive electrode active material layer. Through the calendering process, the contact area between the solid electrolyte and the positive electrode active material in the positive electrode active material layer is widened, thus reducing the interfacial resistance. By reducing the interfacial resistance between the solid electrolyte and the positive electrode active material, ion migration pathways within the electrode can be effectively formed.

[0090] Calendering processes can include rolling processes. Rolling processes can be performed using multiple rolls. This will be described below. Figure 7 The calendering process is described in more detail in the text.

[0091] Attaching the positive electrode active material layer to the positive electrode current collector (S400) can be or may include attaching the positive electrode active material layer to the positive electrode current collector after the calendering process is completed. For example, the positive electrode active material layer can be attached to one or both sides of the positive electrode current collector. One side of the positive electrode current collector can refer to the top surface or the bottom surface of the positive electrode current collector. That is, the positive electrode active material layer can be attached to at least one side of the top surface and the bottom surface of the positive electrode current collector.

[0092] For example, after the calendering process, the positive electrode active material layer can be additionally attached to the positive electrode current collector. This is because the positive electrode layer can be manufactured under dry conditions. Unlike the above, when manufacturing the positive electrode layer using a wet process, an additional drying process may be necessary after applying the positive electrode slurry, including the solvent, to the positive electrode current collector. In other words, when manufacturing the positive electrode layer under dry conditions, this additional drying process is unnecessary. Without this additional drying process, all-solid-state batteries can exhibit improved efficiency during the manufacturing process. The aforementioned positive electrode layer may include a positive electrode current collector and a positive electrode active material layer attached thereto. The positive electrode current collector can be combined with… Figure 1 and Figure 2 The positive electrode current collectors described in the text are basically the same or similar.

[0093] Attaching the positive electrode active material layer to the positive electrode current collector (S400) can be performed, for example, by a hot-pressing process. The hot-pressing process can induce strong adhesion between the positive electrode active material layer and the positive electrode current collector, and can improve the mechanical and electrical properties of the positive electrode used in all-solid-state batteries.

[0094] Hot pressing can be performed at temperatures ranging from approximately 50°C to approximately 200°C. Alternatively, compression can be achieved using multiple rollers. Besides compression with multiple rollers, the compression process can also be performed using any method that allows the positive electrode active material layer to be attached to the positive electrode current collector. When hot compression is performed at temperatures below approximately 50°C, the adhesion between the positive electrode active material layer and the positive electrode current collector may be relatively weak. That is, attaching the positive electrode active material layer to the positive electrode current collector can be challenging. When hot compression is performed at temperatures above approximately 200°C, micro-deformation may occur on the surface of the positive electrode current collector. Micro-deformation on the surface of the positive electrode current collector may lead to, for example, a decrease in battery performance.

[0095] Figure 4 This is a conceptual diagram illustrating a hybrid process in a manufacturing method according to an exemplary embodiment of the present disclosure. (Refer to...) Figure 4 In the mixing process according to an exemplary embodiment of the present disclosure, a positive electrode mixture AMM can be manufactured by mixing a positive electrode active material AAM, a solid electrolyte SE, a conductive material CM, and a fibrous binder BND in a mixer.

[0096] No additional solvent may be required during the mixing process. That is, the mixing process can be carried out under dry conditions. The positive electrode mixture obtained through the mixing process can be bonded to a fibrous binder (BND).

[0097] The fibrous adhesive BND can be, but is not limited to, at least one of polyvinylidene fluoride, styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, poly(methyl methacrylate), etc. Additionally, the fibrous adhesive can be combined with the above-mentioned... Figure 1 The adhesives described are essentially the same or similar.

[0098] Figure 5 This is a conceptual diagram illustrating a shear-mixing process in a manufacturing method according to an exemplary embodiment of the present disclosure. (Refer to...) Figure 5 Shear mixing process can be Figure 4 The mixing process of the positive electrode mixture AMM is described. The shear mixing process can be performed by a shearing member SM. The shearing member SM can act as a shearing element for the positive electrode mixture AMM. Furthermore, the shearing member SM can be configured to mix the mixture.

[0099] During the shear mixing process (S200), the shearing member SM can apply shear force to the positive electrode mixture AMM. The mixing uniformity of the positive electrode mixture AMM can vary depending on the intensity of the shear force.

[0100] Shear force refers to the force that occurs between two parallel surfaces when they move at different speeds. During shear mixing processes, particles can generate friction and can be dispersed substantially uniformly using shear force. In other words, shear force can break up particle agglomeration and help the individual particles mix more evenly. Specifically, shear force can ensure that the individual particles or multiple particles of the positive electrode active material, solid electrolyte, conductive material, and fibrous binder included in the positive electrode mixture are mixed substantially uniformly.

[0101] Shear mixing processes can rearrange powder particles and deagglomerate aggregates. The rearrangement of powder particles caused by shear mixing allows solid particles to realign themselves under the influence of shear forces. During this process, the positive electrode active material AAM, solid electrolyte SE, conductive material CM, and fibrous binder BND can be mixed in a substantially uniform ratio. Furthermore, in the manufacture of the positive electrode for all-solid-state batteries, powder particle rearrangement helps achieve a substantially uniform distribution of conductive and ion migration pathways, which can improve battery efficiency.

[0102] In shear mixing processes, deaggregation refers to the process by which aggregates of particles are broken down by shear forces. Deaggregation can improve the homogeneity of the mixture and increase the contact area between the electrolyte and the electrode.

[0103] During the shearing and mixing process, kneaders, three-roll mills, etc., can be used, but the exemplary embodiments of the inventive concept are not limited to these.

[0104] During the shear mixing process, shear strength can be expressed as shear rate and shear stress.

[0105] Shear rate can be defined as the value obtained by dividing the speed difference between two parallel planes by the distance between them when two planes move at different speeds. In other words, shear rate indicates how quickly a material deforms under shear force. As the shear rate increases, materials that are sheared together deform more rapidly. Dry processes may require high shear rates.

[0106] The shear mixing process according to exemplary embodiments of this disclosure can have a high shear rate. When the shear rate is high during the shear mixing process, particles move rapidly and their strong bonds are broken, which allows the mixing process to proceed more uniformly. Furthermore, when the shear rate of the shear mixing process is high, substantially uniform mixing can be achieved in a short time. Additionally, a high shear rate during the shear mixing process allows for the achievement of high shear forces. Moreover, a high shear rate during the shear mixing process can improve the uniformity of the positive electrode active material, solid electrolyte, conductive material, and fibrous binder in the electrode, which can improve battery performance.

[0107] In the shear-mixing process according to an exemplary embodiment of the present disclosure, the shear rate can be approximately 1000 s. -1 approximately 10000s -1 Within the range. When the shear rate is less than 1000 s⁻¹ -1 During shear mixing, the interparticle friction may be reduced. That is, when the shear rate is less than 1000 s⁻¹. -1 At that time, it may not be possible to achieve proper uniform mixing between the particles of the positive electrode mixture.

[0108] When shear stress increases, particles can undergo strong shear mixing. That is, shear stress is a value obtained by dividing the shear force by the area, and it represents the intensity of the shear force applied to the particles. Furthermore, shear stress can refer to the shear force applied to a specific region of the particle. High shear stress makes it easier to break the bonds between solid particles. Additionally, high shear stress can effectively compress materials and increase their density. In other words, when shear stress is high, the shear mixing process can promote substantially uniform mixing between materials, which can improve or optimize electrode performance.

[0109] In the shear mixing process according to an exemplary embodiment of this disclosure, the shear stress can be in the range of about 0.5 MPa to about 10,000 MPa. For example, the shear stress can be in the range of about 0.5 MPa to about 0.8 MPa. When the shear stress is less than about 0.5 MPa, the mixing and dispersion of the positive electrode active material may be uneven.

[0110] Figure 6 yes Figure 5 The enlarged image shows the "M1" section. (See reference.) Figure 6 The positive electrode active material mixture may include the positive electrode active material AAM, the solid electrolyte SE, the conductive material CM, and the fibrous binder BND. For example... Figure 6 As described herein, the solvent may not be included in the positive electrode mixture. Additionally, as... Figure 6 As described above, the positive electrode active material AAM, solid electrolyte SE, conductive material CM, and fibrous binder BND can be mixed substantially uniformly. This is likely due to the positive electrode mixture being mixed as described above. Figure 4 and Figure 5 The described shear mixing process results in a substantially uniform mixture. The fibrous binder included in the positive electrode mixture can be, but is not limited to, at least one of polyvinylidene fluoride, styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, poly(methyl methacrylate), etc. Additionally, the fibrous binder can be combined with... Figure 1The adhesives described in the text are essentially the same or similar.

[0111] Figure 7 This is a conceptual diagram illustrating a calendering process in a manufacturing method according to an example embodiment of the present disclosure. Figure 3 As shown, calendering may include rolling.

[0112] Roll pressing can refer to a process in which pressure is applied to a positive electrode mixture (AMM) using multiple rollers (RL). Roll pressing can be performed, for example, from one to four times. Furthermore, roll pressing can be performed more than four times, but is not limited to this.

[0113] The rolling process can be performed at pressures ranging from approximately 20 MPa to approximately 50 MPa. When rolling is performed at pressures below approximately 20 MPa, the mechanical strength of the positive electrode active material layer may be poor. Additionally, when rolling is performed at pressures below approximately 20 MPa, the interfacial resistance between the positive electrode active material and the solid electrolyte may increase. When rolling is performed at pressures above approximately 50 MPa, cracks in the solid electrolyte may occur due to the considerably high pressure during the rolling process. Electrode cracks can lead to performance degradation in the all-solid-state battery.

[0114] The rolling process can be performed in a temperature range of approximately 50°C to approximately 200°C. When the rolling process during the pressing period is performed at a temperature below approximately 50°C, it may be difficult to achieve the mechanical deformation required for manufacturing the positive electrode active material layer. When mechanical deformation is difficult to achieve, higher pressure rolling may be required. However, performing rolling with higher pressure may lead to cracks on the electrode.

[0115] When the rolling process is performed at temperatures above approximately 200°C during calendering, it may damage the materials included in the positive electrode mixture. In other words, rolling processes performed at high temperatures can cause damage to the positive electrode active material, solid electrolyte, conductive materials, and fibrous binder. Damage to the materials included in the positive electrode mixture may lead to a decrease in battery performance.

[0116] Figure 8 This is a cross-sectional view of the positive electrode for an all-solid-state battery according to another exemplary embodiment of this disclosure. (Refer to...) Figure 8 In the positive electrode of an all-solid-state battery, the positive electrode active material layer 120 can be disposed on the positive electrode current collector 110. That is, the positive electrode active material layer 120 can be disposed on the top surface of the positive electrode current collector 110. The adhesion of the positive electrode active material layer 120 to the positive electrode current collector 110 can be achieved through the above-mentioned... Figure 3 The hot pressing process described above is used. Figure 8 The positive electrode active material layer 120 and the positive electrode current collector 110 can be related to the above. Figure 1 The positive electrode active material layer 120 and the positive electrode current collector 110 are substantially the same or similar.

[0117] The loading level of the positive electrode active material layer 120 can be approximately 25 mg / cm². 2 Approximately 100 mg / cm 2 Within a certain range. Additionally, the loading level of the positive electrode active material layer 120 can be approximately 25 mg / cm³. 2 Approximately 80 mg / cm 2 Approximately 35 mg / cm 2 Approximately 100 mg / cm 2 Approximately 35 mg / cm 2 Approximately 80 mg / cm 2 or approximately 35 mg / cm 2 Approximately 55 mg / cm 2 .

[0118] Loading level can refer to the degree to which the positive electrode material is thickly or heavily coated in the positive electrode of an all-solid-state battery. For example, loading level can indicate the amount of positive electrode active material included in the electrode. As the loading level increases, a larger amount of active material can be included per unit area. Additionally, as the loading level increases, the energy density of the battery can increase. However, for example, when the loading level is quite high, the ionic conductivity and / or electrical conductivity of the battery may decrease. Furthermore, when the loading level is quite high, the performance of the battery may degrade. For example, when the loading level exceeds a certain threshold (such as approximately 60 mg / cm²), the battery performance may decline. 2 or approximately 100 mg / cm 2 When this happens, the battery's performance may decrease.

[0119] According to exemplary embodiments of the present disclosure, the positive electrode active material layer 120 manufactured under dry conditions does not exhibit a decrease in ionic conductivity even with increasing load levels. Furthermore, the positive electrode active material layer 120 manufactured according to exemplary embodiments of the present disclosure does not exhibit a decrease in ionic conductivity even with load levels of approximately 35 mg / cm². 2 Even in thicker electrode plates, or over a larger area, no decrease in ionic conductivity is observed. Furthermore, the positive electrode active material layer 120 manufactured according to the example embodiments of this disclosure, even when using a loading level of approximately 35 mg / cm², does not exhibit this characteristic. 2 Even with thicker electrode plates over a larger area, there is no noticeable decrease in battery performance.

[0120] Positive electrode active material layers manufactured using wet processes may undergo additional high-temperature drying processes. Due to the reaction between the solvent and sulfide-based solid electrolytes, positive electrode active material layers manufactured using wet processes may exhibit reduced ionic conductivity. Therefore, with increasing load levels, positive electrode active material layers manufactured using wet processes may exhibit decreased ionic conductivity. Furthermore, batteries including positive electrode active material layers manufactured using wet processes may exhibit performance degradation with increasing load levels.

[0121] Figure 9 It is Figure 8 The enlarged view of the "M2" section shown. (Refer to...) Figure 9 The positive electrode active material layer 120 may include a positive electrode active material AAM, a solid electrolyte SE, a conductive material CM, and a fibrous binder BND. The positive electrode active material AAM, the solid electrolyte SE, the conductive material CM, and the fibrous binder BND can be substantially uniformly dispersed in the positive electrode active material layer 120. Figure 8 This is due to the above regarding... Figure 5 The high shear rate during the described shear mixing process is the cause. Additionally, the substantially uniform dispersion is due to the high shear stress during the shear mixing process. (See reference...) Figure 6 and Figure 9 , Figure 9 The distance between the positive electrode active material AAM can be less than Figure 6 The distance between the positive electrode active materials AAM shown in the diagram. This difference is due to... Figure 7 This is caused by the rolling process in the calendering process described herein. Therefore, the adhesion of the mixture included in the positive electrode active material layer manufactured after the calendering process can be increased.

[0122] A method for manufacturing a positive electrode for an all-solid-state battery may include manufacturing the positive electrode for the all-solid-state battery under dry conditions. By using the manufacturing method according to an example of this disclosure, even when the loading level of the positive electrode active material layer is about 35 mg / cm³, 2 Or, on a larger scale, it can reduce or prevent the decrease in the ionic conductivity of the battery. In other words, it can improve the performance of all-solid-state batteries.

[0123] Example 1 (Preparation of positive electrode mixture) As a solid electrolyte, Li6PS5Cl (D50 = 1.0 μm, crystalline) with a sulforaphite-germanium-type crystal structure was prepared. A positive electrode active material and a solid electrolyte were prepared such that the weight ratio of the positive electrode active material to the solid electrolyte was approximately 90:10. NCM811 was used as the positive electrode active material, a carbon-based conductive material (e.g., carbon black) was used as the conductive material, and PTFE was prepared as the binder. The positive electrode active material, solid electrolyte, conductive material, and fibrous binder were mixed to prepare a positive electrode mixture. The positive electrode mixture was obtained by dry mixing using a mixer.

[0124] Shear mixing process: The uniformity of the positive electrode mixture was improved by a shear mixing process. This process takes approximately 1500 seconds. -1 The process is carried out under conditions of a shear rate and a shear stress of approximately 0.5 MPa. Shear mixing allows for a more uniform distribution of particles in the mixture and increases or optimizes the contact between the solid electrolyte and the active material.

[0125] Rolling: The shear-mixed positive electrode mixture is rolled into a layer of positive electrode active material using a calendering machine. In this case, the rolling process pressure is set to approximately 30 MPa, and the rolling process is carried out at approximately 120°C. The calendering process is a crucial stage for maintaining the uniform thickness of the positive electrode layer and adjusting its density, and is adjusted to achieve a final loading level of approximately 25 mg / cm³. 2 .

[0126] Hot pressing of the positive electrode active material layer: A calendered positive electrode active material layer is positioned on a positive electrode current collector (e.g., aluminum foil) for a hot-pressing process. Hot compression is performed at approximately 200°C, thereby firmly bonding the positive electrode active material layer to the current collector.

[0127] Example 2 In addition to a load level of 40 mg / cm 2 In addition, the positive electrode active material layer is prepared in the same manner as in Example 1.

[0128] Example 3 In addition to a load level of 50 mg / cm 2 In addition, the positive electrode active material layer is prepared in the same manner as in Example 1.

[0129] Comparison Example 1 Preparation of positive electrode active material: As a solid electrolyte, Li6PS5Cl (D50 = 1.0 μm, crystalline) with a sulforaphite-germanium-type crystal structure was prepared. A positive electrode active material and a solid electrolyte were prepared such that the weight ratio of the positive electrode active material to the solid electrolyte was approximately 90:10. NCM811 was used as the positive electrode active material, a carbon-based conductive material (e.g., carbon black) was used as the conductive material, and PTFE was prepared as the binder. The positive electrode active material, solid electrolyte, conductive material, and binder were mixed to prepare a positive electrode mixture. A solvent with low polarity (e.g., xylene) was used. The positive electrode mixture in slurry form was stirred for a sufficient time to ensure uniform distribution of the components.

[0130] Coating: The manufactured positive electrode paste is applied to the surface of a current collector (e.g., aluminum foil). In this process, the positive electrode paste is applied to a uniform thickness according to the coating device settings, and the coating device is adjusted to achieve a target loading level of approximately 25 mg / cm² as the positive electrode. 2 The load level.

[0131] dry: The solvent is evaporated from the coated slurry via a drying process. Drying is carried out at a temperature of approximately 80°C to approximately 120°C. During this stage, the solvent is completely evaporated to form the positive electrode for the all-solid-state battery.

[0132] Comparison Example 2 In addition to a load level of 30 mg / cm 2 In addition, the positive electrode active material layer is prepared in the same manner as in Comparative Example 1.

[0133] Comparison Example 3 In addition to a load level of 50 mg / cm 2 In addition, the positive electrode active material layer is prepared in the same manner as in Comparative Example 1.

[0134] Evaluation Example 1: Evaluation of the specific capacity of the positive electrode Positive electrodes manufactured according to Examples 1 to 3 and Comparative Examples 1 to 3, respectively, were connected to a charge and discharge tester and subjected to discharge tests. During the discharge process, each battery was discharged at a constant C rate, and current and voltage data were recorded until the discharge was completed. The discharge capacity of the battery was measured during this process. Figure 10 A graph showing the measured data is provided.

[0135] Evaluation Example 2: Evaluation of Charge and Discharge Rates For all-solid-state batteries using the positive electrodes manufactured in Examples 1 to 3 and Comparative Examples 1 to 3 respectively, the charging and discharging characteristics are evaluated by performing the following charging and discharging tests.

[0136] Charge and discharge tests were performed by placing the all-solid-state battery in a thermostatic bath at approximately 45°C. Charging was conducted at a constant current (CC). The battery was charged at approximately 0.05C to approximately 2.8V and discharged at approximately 0.05C to approximately 1.0V in CC mode.

[0137] The charging and discharging capacity of the first cycle were measured while performing a single charge and discharge test using this method. Figure 11 A graph showing the measured data is provided.

[0138] Reference Figure 10 Compared to the battery manufactured using a wet process according to Comparative Example 3, the batteries manufactured using dry processes according to Examples 1 to 3 respectively have the desired or improved specific capacity. Specifically, when the load level is approximately 35 mg / cm³... 2 When the specific capacity is greater than or equal to that of the wet-manufactured battery according to Comparative Example 3, the specific capacity is significantly reduced.

[0139] Reference Figure 11 Compared to batteries manufactured using wet processes according to Comparative Examples 2 and 3, respectively, batteries manufactured using dry processes according to Examples 1 to 3 have desired or improved charge and discharge rates. Specifically, when the load level is approximately 35 mg / cm³... 2 When the rate is higher, the battery manufactured by the wet process according to Comparative Example 3 has a significantly reduced charge and discharge rate.

[0140] When using the method for manufacturing a positive electrode for an all-solid-state battery according to an exemplary embodiment of this disclosure, the positive electrode for the all-solid-state battery can be manufactured using a dry process without the use of solvents. Positive electrodes for all-solid-state batteries manufactured using such methods can reduce or minimize the degradation of sulfide-based solid electrolytes, which can improve ionic conductivity. Therefore, processability and productivity during the manufacturing of all-solid-state batteries can be improved.

[0141] The positive electrode for an all-solid-state battery according to another example embodiment of this disclosure can have improved ionic conductivity and capacity.

[0142] Although exemplary embodiments of this disclosure have been described herein with reference to the accompanying drawings, this disclosure may be implemented in other specific forms without altering the technical concept or essential characteristics thereof. Therefore, it should be understood that the above exemplary embodiments are for illustrative purposes in all respects and not for limitation.

Claims

1. A method for manufacturing a positive electrode for an all-solid-state battery, the method comprising the following steps: A positive electrode mixture comprising a positive electrode active material, a solid electrolyte, a conductive material, and a fibrous binder is prepared. The positive electrode active material layer is formed by rolling the positive electrode mixture using multiple rolls. as well as The positive electrode active material layer is attached to one or both sides of the positive electrode current collector. The positive electrode active material layer attached to each side of the positive electrode current collector has a density of 25 / cm. 2 Up to 100 mg / cm 2 The load level is within the range.

2. The method according to claim 1, wherein, The positive electrode mixture is mixed under dry conditions without solvent.

3. The method according to claim 1, wherein, The positive electrode mixture includes less than 0.1 ppm of solvent.

4. The method according to claim 1, wherein, The steps for preparing the positive electrode mixture include a shear mixing process. The shear mixing process has a time of 1000s -1 up to 10000s -1 The shear rate within the range.

5. The method according to claim 4, wherein, The shear mixing process has shear stress in the range of 0.5 MPa to 10000 MPa.

6. The method according to claim 1, wherein, The step of calendering the positive electrode includes a rolling process, wherein the rolling process is carried out in a pressure range of 20 MPa to 50 MPa.

7. The method according to claim 6, wherein, The rolling process is carried out in a temperature range of 50°C to 200°C.

8. The method according to claim 1, wherein, The step of attaching the positive electrode active material layer to the positive electrode current collector includes hot-pressing the positive electrode active material layer at a temperature in the range of 50°C to 200°C.

9. The method according to claim 1, wherein, The solid electrolyte includes sulfide solid electrolytes.

10. The method according to claim 1, wherein, Based on the total weight of the positive electrode mixture, the amount of the solid electrolyte is in the range of 5 wt% to 30 wt%.

11. The method according to claim 1, wherein, The positive electrode active material includes at least one of lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, and lithium iron phosphate.

12. The method according to claim 1, wherein, Based on the total weight of the positive electrode mixture, the amount of the positive electrode active material is in the range of 70 wt% to 95 wt%.

13. The method according to claim 1, wherein, The fibrous adhesive includes at least one of styrene-butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, and poly(methyl methacrylate).

14. The method according to claim 1, wherein, The amount of the fibrous binder is in the range of 0.5 wt% to 3 wt% based on the total weight of the positive electrode mixture.

15. The method according to claim 1, wherein, Based on the total weight of the positive electrode mixture, the amount of the conductive material is in the range of 0.5 wt% to 3 wt%.

16. A positive electrode for an all-solid-state battery, the positive electrode comprising: Positive electrode current collector; as well as The positive electrode active material layer is located on the positive electrode current collector. The positive electrode active material layer comprises a positive electrode active material, a solid electrolyte, a conductive material, and a fibrous binder. The loading level of the positive electrode active material layer is 25 mg / cm³. 2 Up to 100 mg / cm 2 Within the range.

17. The positive electrode according to claim 16, wherein, The solid electrolyte in the positive electrode active material layer includes sulfide solid electrolytes.

18. The positive electrode according to claim 17, wherein, Based on the total weight of the positive electrode active material layer, the amount of the sulfide solid electrolyte is in the range of 5 wt% to 30 wt%.

19. The positive electrode according to claim 16, wherein, The fibrous adhesive includes at least one of polyvinylidene fluoride, styrene-butadiene rubber, polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, and poly(methyl methacrylate).

20. The positive electrode according to claim 16, wherein, Based on the total weight of the positive electrode active material layer, the amount of the fibrous binder is in the range of 0.5 wt% to 3 wt%.

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