Solid electrolyte composite, positive electrode active material slurry including the same, and method for preparing the same

Abstract

The present disclosure relates to a solid electrolyte composite, a positive electrode active material slurry including the same, and a method for preparing the same. More specifically, the present disclosure relates to a solid electrolyte composite including a sulfide-based solid electrolyte and a surface modifier on a surface of the sulfide-based solid electrolyte. The surface modifier includes a chain hydrocarbon chain and a polar functional group bonded to the chain hydrocarbon chain, and the surface modifier is attached to the surface of the sulfide-based solid electrolyte via the polar functional group.

Description

[0001] This application claims priority to Korean Patent Application No. 10-2024-0174658, filed on November 29, 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 solid electrolyte complex, a positive electrode active material slurry including the solid electrolyte complex, and a solid electrolyte slurry including the solid electrolyte complex. Background Technology

[0003] The demand for high-energy-density and safe batteries is increasing, driven by industry needs. 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 typically emphasized due to its direct link to protecting human life.

[0004] All-solid-state batteries exist, which use solid electrolytes instead of liquid electrolytes. 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, all-solid-state batteries offer significantly improved safety compared to lithium-ion batteries that use liquid electrolytes. Summary of the Invention

[0005] Example embodiments of this disclosure include solid electrolyte complexes having desired or improved solvent stability.

[0006] Example embodiments of this disclosure include a positive electrode and a solid electrolyte layer having desired or improved lifetime characteristics and ionic conductivity.

[0007] According to exemplary embodiments of this disclosure, a solid electrolyte complex may include a sulfide-based solid electrolyte and a surface modifier on the surface of the sulfide-based solid electrolyte. The surface modifier includes a chain-like hydrocarbon chain and polar functional groups bonded to the chain-like hydrocarbon chain. The surface modifier is attached to the surface of the sulfide-based solid electrolyte via the polar functional groups.

[0008] According to an example embodiment of this disclosure, the positive electrode active material slurry may include a positive electrode active material and a solid electrolyte complex. The solid electrolyte complex includes a sulfide-based solid electrolyte and a surface modifier on the surface of the sulfide-based solid electrolyte. The surface modifier includes a chain-like hydrocarbon chain and polar functional groups bonded to the chain-like hydrocarbon chain. The surface modifier is attached to the surface of the sulfide-based solid electrolyte via the polar functional groups.

[0009] According to an example embodiment of this disclosure, a method for preparing a solid electrolyte complex may include the following steps: preparing a sulfide-based solid electrolyte; preparing a surface modifier; and mixing the sulfide-based solid electrolyte with the surface modifier. The surface modifier comprises a chain-like hydrocarbon chain and polar functional groups bonded to the chain-like hydrocarbon chain. The surface modifier is attached to the surface of the sulfide-based solid electrolyte via the polar functional groups. 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 another exemplary embodiment of this disclosure, taken along line A-A'.

[0014] Figure 4 An enlarged view of a solid electrolyte complex according to an example embodiment of the present disclosure is shown.

[0015] Figure 5 It shows Figure 2A The “M” region in the diagram shows an enlarged cross-sectional view of the positive electrode active material layer according to a comparative example of this disclosure.

[0016] Figure 6 It shows Figure 2A The “M” region in the diagram shows an enlarged cross-sectional view of the positive electrode active material layer according to an exemplary embodiment of the present disclosure.

[0017] Figure 7 A graph showing XPS analysis results of solid electrolytes according to embodiments and comparative embodiments of the present disclosure is displayed.

[0018] Figure 8 This is a flowchart illustrating a method for preparing a solid electrolyte complex according to an example embodiment. Detailed Implementation

[0019] 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.

[0020] 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.

[0021] Some exemplary embodiments detailed in this specification are discussed with reference to 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 shown in the drawings have general characteristics, and the shapes of the regions shown in the drawings are intended to 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.

[0022] 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, the singular forms “a,” “an,” and “the” may include the plural forms. The term “comprising / including” and / or variations thereof as used in this specification do not exclude the presence or addition of one or more other components.

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

[0024] 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.

[0025] Unless otherwise specifically defined in this specification, particle size may be the average particle size. Furthermore, particle size refers to the average particle size (Dsize) of particles having a cumulative volume of approximately 50% in 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, from which the average particle size (D) can then be calculated. 50 The average particle size (D) can also be measured using laser scattering. 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 ).

[0026] 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.

[0027] 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%.

[0028] 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'.

[0029] 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 facing the positive electrode layer 100, and a solid electrolyte layer 300 disposed between the positive electrode layer 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.

[0030] Positive electrode layer 100 According to an example embodiment of the present 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.

[0031] 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), and alloys thereof.

[0032] 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.

[0033] Positive electrode active material layer 120 The positive electrode active material layer 120 according to an example embodiment of the present disclosure may include a positive electrode active material and a solid electrolyte.

[0034] The positive electrode active material of the positive electrode active material layer 120 may include materials 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 lithium transition metal oxides (e.g., at least one of 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, or vanadium oxide, but this disclosure is not limited thereto. The positive electrode active material may be used alone or in a mixture of two or more compounds.

[0035] 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 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, Li3-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, and combinations thereof; "B" can be or include at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; "D" can be or include at least one of O, F, S, P, and combinations thereof; "E" can be or include at least one of Co, Mn, and combinations thereof; "F" can be or include at least one of F, S, P, and combinations thereof; "G" can be or include at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; "Q" can be or include at least one of Ti, Mo, Mn, and combinations thereof; "I" can be or include at least one of Cr, V, Fe, Sc, Y, and combinations thereof; "J" can be or include at least one of V, Cr, Mn, Co, Ni, Cu, and combinations thereof.

[0036] The positive electrode active material can 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" can refer to 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, and in this structure, each atom layer forms a two-dimensional plane. The term "cubic rock salt-type structure" can refer to the sodium chloride (NaCl)-type structure, which is a type of crystal structure. For example, it has a face-centered cubic lattice (FCC) formed by cations and anions that are offset by 1 / 2 (half) of the unit lattice ridge from each other. The lithium transition metal oxide having a layered rock salt-type structure can 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 can have an increased energy density and improved thermal stability.

[0037] The compound included in the positive electrode active material may be covered by a coating layer (not shown). The positive electrode active material may be used as a mixture of the compound and the compound to which the coating layer is added. The coating layer added to the surface of the positive electrode active material may include at least one of oxides, hydroxides, hydroxyoxides, oxycarbonates, and bicarbonates 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, and mixtures thereof. The coating layer may include, for example, Li₂O-ZrO₂ (LZO). The method for forming the coating layer may be determined in any way 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.

[0038] 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.

[0039] 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.

[0040] 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 (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, Li₂S-P₂S₅-ZmS n (Where m and n are both positive integers, and "Z" is one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Lip MO q (Where p and q are both positive integers, and "M" is 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).

[0041] Sulfide solid electrolytes may be or include argentite-germanium sulfide compounds, such as 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.

[0042] 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 and 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), and combinations thereof. Sulfide-based solid electrolytes can include, for example, Li 7-x PS 6-x Clx (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), Li 7-x PS 6-x I x (0≤x≤2), Li 7-y M1 y PS 6-z M2 z (0≤y≤2, 0≤z≤2) and at least one of the combinations thereof, wherein M1 is or includes at least one element from groups 3 to 15 of the periodic table, and wherein M2 is or includes at least one element from group 17 of the periodic table.

[0043] 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 reduce 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.

[0044] The solid electrolyte in the positive electrode active material layer 120 can be derived from the following reference. Figure 4 The solid electrolyte complex described.

[0045] 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, for example, using a laser particle size analyzer.

[0046] The positive electrode active material layer 120 may include a conductive material. The conductive material can provide conductivity 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.

[0047] The positive electrode active material layer 120 may further include a binder. The binder allows the positive electrode active material, solid electrolyte, and conductive material to bond together within 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.

[0048] 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 80 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.

[0049] Based on 100 parts by weight of solid electrolyte, conductive material can 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 decreases, 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 increases significantly, resulting in incomplete formation of the coating layer covering the surface of the solid electrolyte.

[0050] 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, coatings, dispersants and ionic conductive agents.

[0051] negative electrode layer 200 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.

[0052] 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.

[0053] Coating layer 220 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.

[0054] 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), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Coating layer 220 may include at least one carbon, such as at least one selected from carbon black, 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).

[0055] 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.

[0056] 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 a very small thickness, lithium dendrites formed between the coating layer 220 and the negative electrode current collector 210 may cause the coating layer 220 to collapse, thereby reducing the cycle characteristics of the cell CEL. When the coating layer 220 has a very large thickness, the cell CEL may have a reduced energy density, and the internal resistance of the cell CEL may increase due to the coating layer 220, thereby reducing the cycle characteristics of the cell CEL. 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.

[0057] Solid electrolyte layer 300 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 desired or improved lithium-ion conductivity. The solid electrolyte in the solid electrolyte layer 300 may be derived from [the following references] Figure 4 The solid electrolyte complex described. 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.

[0058] 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.

[0059] Reference Figure 2A The first solid electrolyte layer 310 may include a first solid electrolyte. The first solid electrolyte may have a generally spherical or generally 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 one of the constituent elements of the aforementioned sulfide-based solid electrolytes: sulfur (S), phosphorus (P), and lithium (Li). For example, the solid electrolyte may be or include a material comprising Li₂S-P₂S₅. When the sulfide-based solid electrolyte material includes Li₂S-P₂S₅ as the solid electrolyte, the molar ratio of Li₂S to P₂S₅ may be in the range of about 50:50 to about 90:10.

[0060] 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.

[0061] Optionally, the sulfide-based solid electrolyte may be or may include Li 7-a-c M a PS 6-c X cA 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 and 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), and combinations thereof. Sulfide-based solid electrolytes can include, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), Li 7-x PS 6-x I x (0≤x≤2), Li 7-y M1 y PS 6-z M2 z (0≤y≤2, 0≤z≤2) and at least one of the combinations thereof, wherein M1 is or includes at least one element from groups 3 to 15 of the periodic table, and wherein M2 is or includes at least one element from group 17 of the periodic table.

[0062] 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 reduce 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.

[0063] 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, and 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.

[0064] The second solid electrolyte layer 320 may include a second solid electrolyte. The second solid electrolyte may have a generally spherical particle shape or an elliptical particle shape.

[0065] 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 a composition substantially the same as that of the first solid electrolyte. Optionally, the second solid electrolyte may have a composition similar to that of the first solid electrolyte.

[0066] 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 battery performance.

[0067] 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.

[0068] 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.

[0069] 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, for example, be completely stacked inward with the negative electrode hybrid layer ASH.

[0070] In an exemplary embodiment of this disclosure, the first solid electrolyte layer 310 may have an area substantially the same as that of the positive electrode layer 100. The second solid electrolyte layer 320 may have an area substantially the same as that of the negative electrode layer 200.

[0071] 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.

[0072] According to an example of this 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.

[0073] The example cell CEL according to this embodiment may further include a gasket GSK. The gasket GSK may be configured to 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 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 disposed at a height (or horizontal) higher than the height of the gasket GSK.

[0074] The positive electrode current collector 110 may include a positive electrode terminal block CTB. The positive electrode terminal block CTB may be a protruding region of the positive electrode current collector 110. In an example embodiment, the positive electrode terminal block CTB may protrude in the second direction D2.

[0075] The negative electrode current collector 210 may include a negative electrode terminal block ATB. The negative electrode terminal block ATB may be a protruding area 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.

[0076] 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.

[0077] 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 3The 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.

[0078] 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 types of alloys.

[0079] In another exemplary embodiment of this disclosure, the lithium metal layer 400 in the negative electrode 200 may be disposed between the negative electrode current collector 210 and the coating layer 220, for example, before assembling the cell cell CEL. When the lithium metal layer 400 is disposed between the negative electrode current collector 210 and the coating layer 220 before assembling the cell cell CEL, the lithium metal layer 400 may be a metal layer comprising lithium, and thus may constitute a lithium storage device. For example, a lithium foil may be placed between the negative electrode current collector 210 and the coating layer 220 before assembling the cell cell CEL.

[0080] When a lithium metal layer 400 is deposited by charging after assembling the cell cell (CEL), the energy density of the cell cell (CEL) can be increased because the cell cell (CEL) does not include a lithium metal layer during assembly. When the cell cell (CEL) is charged, the charging capacity of the coating layer 220 can be exceeded. That is, the coating layer 220 is overcharged. In the initial stage of charging, lithium may be adsorbed in the coating layer 220. When charging beyond the capacity of the coating layer 220 is performed, for example, lithium can be deposited between the negative electrode coating layer 220 and the negative electrode current collector 210. The metal layer 400 can be formed from the deposited lithium.

[0081] The lithium metal layer 400 may be primarily composed of lithium (i.e., metallic lithium) or may include lithium (i.e., metallic lithium). During discharge, the lithium in the lithium metal layer 400 can be ionized and migrate to the positive electrode 100. In other words, lithium can be used as the negative electrode active material in the cell cell CEL. Furthermore, because the coating layer 220 covers the lithium metal layer 400, the coating layer 220 can protect the lithium metal layer 400 and reduce or inhibit the precipitation and growth of lithium dendrites. Therefore, the coating layer 220 can reduce or inhibit short circuits and capacity reduction in the cell cell CEL, and can improve the cycle characteristics of the cell cell.

[0082] When a lithium metal layer 400 is formed by charging after assembling a cell cell CEL, the negative electrode 200 (including the negative electrode current collector 210, the coating layer 220 and the area therebetween) may be or may include a Li-free region that does not contain lithium (Li) in the initial state or in the state after the cell cell CEL is fully discharged.

[0083] 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.

[0084] The negative electrode 200 may also include a thin layer disposed between the negative electrode current collector 210 and the coating layer 220. The thin layer may be disposed on one side of the negative electrode current collector 210 to form an alloy with lithium.

[0085] The thin layer may include, for example, elements capable of forming alloys with lithium. Elements capable of forming alloys with lithium may include, for example, at least one of gold, silver, zinc, tin, indium, silicon, aluminum, and bismuth, but this disclosure is not limited thereto, and any suitable element in the art capable of forming alloys with lithium may be used. The thin layer may be formed from or include alloys of one or more of the metals discussed above.

[0086] Since the thin layer is disposed on one side of the negative electrode current collector 210, the plating shape of the lithium metal layer 400 deposited between the thin layer and the coating layer 220 can be made more flat, and the cycle characteristics of the all-solid-state battery can be improved.

[0087] The thickness of the thin layer can range, for example, from about 1 nm to about 800 nm, from about 10 nm to about 700 nm, from about 50 nm to about 600 nm, or from about 100 nm to about 500 nm. When the thickness of the thin layer is less than about 1 nm, it may be difficult to achieve the performance benefits caused by the thin layer. When the thickness of the thin layer is very large, the thin layer may absorb lithium to reduce the amount of lithium deposited in the negative electrode 200, thereby reducing the energy density and cycle characteristics of the all-solid-state battery. For example, vapor deposition, sputtering, or plating can be used to form the thin layer on the negative electrode current collector 210, but this disclosure is not limited thereto, and any suitable method in the art capable of forming the thin layer can be used.

[0088] Figure 4 A cross-sectional view of a solid electrolyte complex according to a disclosed example embodiment is shown. In the following, reference is made to... Figure 4The document provides a detailed description of solid electrolyte complexes, positive electrode active material slurries comprising solid electrolyte complexes, and solid electrolyte slurries comprising solid electrolyte complexes.

[0089] solid electrolyte complex Reference Figure 4 The solid electrolyte complex according to an example embodiment of the present disclosure may include a sulfide solid electrolyte (SSE) and a surface modifier (SMF) on the surface of the sulfide solid electrolyte (SSE).

[0090] Sulfide solid electrolytes (SSEs) can include those referenced above. Figures 1 to 2B The solid electrolyte included in the positive electrode active material layer 120 described herein may be made of the same or different materials. Sulfide-based solid electrolytes (SSEs) may have a generally spherical or elliptical particle shape.

[0091] Sulfide solid electrolytes (SSEs) can include, for example, Li₂S-P₂S₅, Li₂S-P₂S₅-LiX (where 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, and Li₂S-P₂S₅-Z. m S 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 At least one of the following (where 0 ≤ x ≤ 2).

[0092] Sulfide solid electrolytes (SSEs) can be or include sulfide-germanium ore-type compounds, such as Li 7-x PS 6-xCl 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.

[0093] 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 and 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), and combinations thereof.

[0094] The average particle size (D50) of sulfide solid electrolytes (SSEs) can range, for example, from about 0.5 μm to about 20 μm, from about 1 μm to about 15 μm, from about 2 μm to about 10 μm, or from about 2 μm to about 5 μm. The average particle size (D50) can be the median particle size measured using, for example, a laser-type particle size distribution analyzer.

[0095] Surface modifiers (SMFs) can include chain hydrocarbon chains (HCCs) and polar functional groups (FGs) bonded to the HCCs. The polar functional group FG can attach the SMF to the surface of the sulfide-based solid electrolyte (SSE) through interactions with it. For example, forces such as electrostatic attraction, ion-dipole interactions, coordination bonding, or dispersion forces can act between the sulfide-based SSE and the polar functional group FG.

[0096] For example, anions present in sulfide solid electrolytes (SSE) (e.g., S...2- Cl - ,Br - I - ) or lithium cation (Li + Lithium ions can form electrostatic attraction with a portion of the charge of the polar functional group FG. For example, lithium ions in sulfide solid electrolytes (SSEs) can attract a portion of the negative charge of the polar functional group FG, or lithium anions in sulfide solid electrolytes (SSEs) can attract a portion of the positive charge of the polar functional group FG. Optionally, lithium ions (Li...) present in sulfide solid electrolytes (SSEs) can... + It can form an ionic dipole interaction with the dipole of the polar functional group FG. Optionally, the polar functional group FG can form a direct coordination bond with lithium ions, or van der Waals attraction can act between the polar functional group FG and the solid electrolyte SSE.

[0097] The polar functional group FG can directly adhere to the surface of the sulfide-based solid electrolyte (SSE) through the aforementioned attractive force. In other words, the surface of the sulfide-based solid electrolyte (SSE) can be in direct contact with the polar functional group FG.

[0098] There are no particular limitations on the polar functional group FG, as long as the polar functional group FG exhibits polarity and low reactivity. For example, the polar functional group FG may include at least one of thiol, hydroxyl, amino, aldehyde, acetic acid, ester, and combinations thereof. In an example embodiment, the polar functional group FG may include a thiol group.

[0099] Chain-like hydrocarbon-based hydrocarbon-based electrolytes (HCCs) can limit the contact between sulfide-based solid electrolytes (SSEs) and solvents. Solid electrolyte particles may come into contact with solvents during the manufacturing process of the positive electrode 100 or the solid electrolyte layer 300. As the contact area between the sulfide-based SSE and the solvent increases, the solid electrolyte particles may degrade due to chemical reactions between the particles and the solvent. Chain-like hydrocarbon-based hydrocarbon-based hydrocarbon-based HCCs can limit the contact between the solvent and the sulfide-based SSE particles, thereby reducing or preventing degradation of the sulfide-based SSE and improving its lifespan.

[0100] Chain-like hydrocarbon-based HCCs can have at least 3 carbon atoms. For example, chain-like hydrocarbon-based HCCs can have about 3 to about 30, about 4 to about 20, or about 5 to about 15 carbon atoms. When the number of carbon atoms in the chain-like hydrocarbon-based HCC is too small, the surface modifier SMF may not be able to effectively limit the contact between the solvent and the solid electrolyte SSE particles. When the number of carbon atoms in the chain-like hydrocarbon-based HCC is too large, the dispersibility of the solid electrolyte SSE may decrease, and the viscosity of the slurry may become very high. When the number of carbon atoms in the chain-like hydrocarbon chain meets the above ranges, sulfide-based solid electrolyte SSEs can exhibit desired or improved dispersibility and desired or improved lifetime characteristics.

[0101] For example, surface modifiers SMF can include CH3(CH2). n R (where 4 ≤ n ≤ 14, and R is or includes at least one of SH, OH, NH2, COOH, COO, COH, and combinations thereof). In an example embodiment, the surface modifier SMF may include CH3(CH2). n SH (where 4≤n≤14 or 5≤n≤8).

[0102] In some exemplary embodiments of this disclosure, the surface modifier SMF may have a boiling point in the range of about 250°C or lower. For example, the boiling point of the surface modifier SMF may be in the range of about 120°C to about 250°C, about 130°C to about 220°C, or about 150°C to about 200°C. When the surface modifier SMF has a low boiling point as described above, the surface modifier SMF may be vaporized and removed during the manufacturing process of the positive electrode 100 or the solid electrolyte layer 300 for use in an all-solid-state battery.

[0103] In other words, the surface modifier SMF can protect the sulfide-based solid electrolyte from the solvent during the manufacturing process of the positive electrode 100 or the solid electrolyte layer 300, and can then be vaporized and removed along with the solvent.

[0104] As a result, the positive electrode 100 or solid electrolyte layer 300 manufactured using the solid electrolyte composite according to this disclosure may not include the surface modifier SMF. The absence of the surface modifier SMF in the positive electrode 100 or solid electrolyte layer 300 may mean that the surface modifier SMF is completely absent, or is present in a very small amount or a very small amount (e.g., 0.01 wt% or less).

[0105] Figure 5 It shows Figure 2A The “M” region in the diagram shows an enlarged cross-sectional view of the positive electrode active material layer 120 according to a comparative example of this disclosure. (Refer to...) Figure 5 According to the comparative example, the positive electrode active material layer 120 may include a positive electrode active material CAM and a sulfide-based solid electrolyte SSE, wherein the sulfide-based solid electrolyte SSE includes a coating layer CTL. The coating layer CTL is included to protect the sulfide-based solid electrolyte SSE from the effects of solvents, and the coating layer CTL may be or include a polymeric or oligomeric coating layer or an inorganic coating layer.

[0106] Unlike the surface modifiers of the examples in this disclosure, the polymeric or inorganic coating CTL remains stable even at temperatures of 200°C or higher. Therefore, the polymeric or inorganic coating CTL remains in the manufactured positive electrode 100 without decomposing or vaporizing during the manufacturing process of the positive electrode 100 for use in an all-solid-state battery. The coating CTL remaining in the positive electrode 100 constitutes resistance and reduces the ionic conductivity of the positive electrode 100.

[0107] Similarly, when the solid electrolyte layer 300 is manufactured using a solid electrolyte including a polymer coating or an inorganic coating CTL, the coating CTL will remain in the solid electrolyte layer 300 and reduce the ionic conductivity of the solid electrolyte layer.

[0108] Figure 6 It shows Figure 2A The “M” region in the diagram shows an enlarged cross-sectional view of the positive electrode active material layer 120 according to an exemplary embodiment of this disclosure. (Refer to...) Figure 6 The positive electrode active material layer 120 manufactured using the solid electrolyte composite of this disclosure may include the positive electrode active material CAM and the sulfide-based solid electrolyte SSE, and may no longer include a surface modifier. The surface modifier, having a low boiling point, can vaporize during the coating and drying process of the positive electrode active material slurry. Therefore, the surface modifier may no longer remain in the positive electrode active material layer 120. Since the positive electrode active material layer 120 according to the exemplary embodiment of this disclosure does not include the surface modifier constituting the resistor, the positive electrode active material layer 120 according to the exemplary embodiment of this disclosure may exhibit the desired or improved ionic conductivity.

[0109] Similarly, when the solid electrolyte layer 300 is fabricated using a solid electrolyte composite according to embodiments of the present disclosure, the solid electrolyte layer 300 may not include a surface modifier, and thus may exhibit the desired or improved ionic conductivity.

[0110] Methods for preparing solid electrolyte complexes The solid electrolyte complex according to an example embodiment of this disclosure can be prepared by a process of mixing a sulfide-based solid electrolyte (SSE) and a surface modifier (SMF). The mixing can be carried out by a solvent-free dry process or by a wet process in the presence of a solvent.

[0111] When mixing is performed via a wet process, the solvent may be or include an organic solvent that is nonpolar or weakly polar. For example, the solvent may include at least one of xylene, benzene, toluene, pentane, hexane, cyclohexane, octyl acetate, isobutyl isobutyrate, and combinations thereof. In one example embodiment, the solvent may include octyl acetate.

[0112] The above-described mixing process can be performed simultaneously or concurrently with the preparation of the positive electrode active material slurry, or it can be performed before the preparation of the positive electrode active material slurry. For example, after preparing a solid electrolyte composite by mixing a sulfide-based solid electrolyte (SSE) and a surface modifier (SMF), the positive electrode active material slurry can be prepared by mixing the solid electrolyte composite and the positive electrode active material in the presence of a solvent. Optionally, the sulfide-based solid electrolyte (SSE), the surface modifier (SMF), and the positive electrode active material can be added to a solvent simultaneously or concurrently and mixed to prepare the solid electrolyte composite and the positive electrode active material slurry at the same time.

[0113] Similarly, the process of mixing the sulfide-based solid electrolyte (SSE) and the surface modifier (SMF) can be performed simultaneously or concurrently with the preparation of the solid electrolyte slurry, or it can be performed before the preparation of the solid electrolyte slurry. For example, after preparing a solid electrolyte composite by mixing the sulfide-based solid electrolyte (SSE) and the surface modifier (SMF), a solid electrolyte slurry can be prepared by mixing the solid electrolyte composite and a binder in the presence of a solvent. Alternatively, the sulfide-based solid electrolyte (SSE), the surface modifier (SMF), and the binder can be added to a solvent simultaneously or concurrently and mixed to prepare both the solid electrolyte composite and the solid electrolyte slurry at the same time.

[0114] In the following, examples of positive electrode active material slurries and solid electrolyte slurries for all-solid-state batteries, including solid electrolyte complexes, are described in more detail according to the present disclosure.

[0115] Positive electrode active material slurry The positive electrode active material slurry according to an example embodiment of the present disclosure may include a positive electrode active material, a solid electrolyte complex, and a solvent.

[0116] The positive electrode active material in the positive electrode active material slurry may be the same as or similar to the positive electrode active material included in the positive electrode active material layer 120 described above. For example, the positive electrode active material 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 lithium transition metal oxides (e.g., at least one of 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, or vanadium oxide, but this disclosure is not limited thereto. The positive electrode active material may be used alone or in a mixture of two or more compounds.

[0117] The solid electrolyte complex of the positive electrode active material slurry may be or includes the above-mentioned references. Figure 4The solid electrolyte complex described. For example, the solid electrolyte complex may include a sulfide-based solid electrolyte and a surface modifier on the surface of the sulfide-based solid electrolyte.

[0118] Sulfide solid electrolytes may be or include argentite-germanium sulfide compounds, such as 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.

[0119] 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 and 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), and combinations thereof.

[0120] Sulfide-based solid electrolytes can have a smaller average particle size (D50) than the positive electrode active material. When the average particle size of the sulfide-based solid electrolyte is smaller than that of the positive electrode active material, the solid electrolyte particles can be more uniformly distributed among the positive electrode active material particles, thereby improving the ionic conductivity and structural stability of the positive electrode. The average particle size can be the median particle size measured using a laser particle size analyzer.

[0121] Surface modifiers may include chain-like hydrocarbon chains and polar functional groups bonded to the chain-like hydrocarbon chains. In one example embodiment, the polar functional group may be bonded to one end of the chain-like hydrocarbon chain. The polar functional group may include at least one of, for example, a thiol group, a hydroxyl group, an amino group, an aldehyde group, an acetic acid group, an ester group, and combinations thereof. The chain-like hydrocarbon chain may be, for example, a chain having about 3 to about 30, about 4 to about 20, or about 5 to about 15 carbon atoms. The boiling point of the surface modifier may be in the range of about 250°C or lower.

[0122] The solvent may be or include organic solvents that are nonpolar or weakly polar. For example, the solvent may include at least one of xylene, benzene, toluene, pentane, hexane, cyclohexane, octyl acetate, isobutyl isobutyrate, and combinations thereof. In one example embodiment, the solvent may include octyl acetate.

[0123] Even when nonpolar or weakly polar solvents are used as solvents in the positive electrode active material slurry, the increased contact area between the sulfide-based solid electrolyte and the solvent may accelerate the decomposition or degradation of the sulfide component. Furthermore, sulfide-based solid electrolytes may undergo physical changes such as shrinkage or expansion upon contact with organic solvents. The surface modifiers according to exemplary embodiments of this disclosure can limit the contact between the solvent and the sulfide-based solid electrolyte, and reduce or prevent the degradation of the sulfide-based solid electrolyte.

[0124] The positive electrode active material slurry may also include a conductive material. The conductive material may include at least one of, for example, graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0125] The positive electrode active material layer 120 may further include an adhesive. The adhesive can bond the positive electrode active material, solid electrolyte, and conductive material together within the positive electrode active material layer 120. The adhesive 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 adhesive may include at least one of polyvinylidene fluoride, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, butyl acrylate, polyacrylonitrile, and polymethyl methacrylate.

[0126] A slurry of positive electrode active material can be applied to a positive electrode current collector and then dried to form a positive electrode active material layer 120. The drying temperature of the positive electrode active material slurry can be in the range of, for example, about 50°C to about 150°C or about 150°C to about 250°C. At the drying temperature, the solvent and surface modifier in the positive electrode active material slurry can be vaporized and removed. That is, the positive electrode active material layer 120 made using the positive electrode active material slurry may not contain solvents and surface modifiers.

[0127] solid electrolyte slurry The solid electrolyte slurry according to the disclosed example embodiments may include a solid electrolyte complex and a solvent.

[0128] Solid electrolyte complexes can be referenced above. Figure 4 The solid electrolyte complex described. For example, the solid electrolyte complex may include a sulfide-based solid electrolyte and a surface modifier on the surface of the sulfide-based solid electrolyte.

[0129] Sulfide solid electrolytes may be or include argentite-germanium sulfide compounds, such as 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) at least one of the following. Optionally, the sulfide solid electrolyte may be or 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 and 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), and combinations thereof.

[0130] The sulfide-based solid electrolyte contained in the solid electrolyte slurry can have a larger average particle size (D50) than the sulfide-based solid electrolyte contained in the positive electrode active material slurry. For example, the average particle size of the solid electrolyte in the solid electrolyte slurry can be in the range of about 110% or greater, about 120% or greater, about 150% or greater, or about 200% or greater than the average particle size of the solid electrolyte in the positive electrode active material slurry. The average particle size can be the median particle size measured using, for example, a laser-type particle size distribution analyzer.

[0131] Surface modifiers may include chain-like hydrocarbon chains and polar functional groups bonded to the chain-like hydrocarbon chains. Polar functional groups may include, for example, at least one selected from thiol groups, hydroxyl groups, amino groups, aldehyde groups, acetic acid groups, ester groups, and combinations thereof. The chain-like hydrocarbon chains may be, for example, chains having about 3 to about 30, about 4 to about 20, or about 5 to about 15 carbon atoms. The boiling point of the surface modifier may be in the range of about 250°C or lower.

[0132] The solvent may be or include organic solvents that are nonpolar or weakly polar. For example, the solvent may include at least one of xylene, benzene, toluene, pentane, hexane, cyclohexane, octyl acetate, isobutyl isobutyrate, and combinations thereof. In one example embodiment, the solvent may include octyl acetate.

[0133] As described above, surface modifiers can limit the contact between the solvent and sulfide solid electrolytes to reduce or prevent the degradation of sulfide solid electrolytes.

[0134] Solid electrolyte slurries may also include binders. Examples of binders included in solid electrolyte slurries include, but are not limited to, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, butyl acrylate, and polyethylene. The binder in the solid electrolyte slurry may be the same as or different from the binder included in the positive electrode active material slurry.

[0135] A solid electrolyte slurry can be applied to a substrate, a positive electrode active material layer 120, or a coating layer 220, and then dried to form a solid electrolyte layer 300. The drying temperature of the solid electrolyte slurry can be in the range of, for example, about 50°C to about 150°C or about 150°C to about 250°C. At the above drying temperatures, the solvent and surface modifier in the solid electrolyte slurry can be vaporized and removed. That is, the solid electrolyte layer 300 manufactured using the solid electrolyte slurry may not contain solvents and surface modifiers.

[0136] Figure 8 This is a flowchart illustrating a method for preparing a solid electrolyte complex according to an example embodiment. Figure 8 In method 800, steps 810, 820, and 830 are included. Step 810 includes preparing a sulfide-based solid electrolyte. For example, the sulfide-based solid electrolyte includes Li... 7-x PS 6-x Cl x (where 0≤x≤2), Li 7-x PS 6-x Br x (where 0≤x≤2), Li 7- x PS 6-x Ix (where 0≤x≤2), Li 7-y M1 y PS 6-z M2 z (where 0 ≤ y ≤ 2 and 0 ≤ z ≤ 2) and at least one combination thereof, wherein M1 includes at least one element from groups 3 to 15 of the periodic table, and M2 includes at least one element from group 17 of the periodic table.

[0137] Operation 820 includes preparing a surface modifier. For example, the surface modifier comprises a chain of hydrocarbons and a polar functional group bonded to the chain of hydrocarbons. In an example, the polar functional group comprises at least one of a thiol group, a hydroxyl group, an amino group, an aldehyde group, an acetic acid group, an ester group, and combinations thereof. In another example, the chain of hydrocarbons has about 5 to about 15 carbon atoms.

[0138] Operation 830 includes mixing a sulfide-based solid electrolyte with a surface modifier. For example, the surface modifier is attached to the surface of the sulfide-based solid electrolyte via polar functional groups.

[0139] Examples of this disclosure are discussed in detail below through embodiments. However, these exemplary embodiments are provided to illustrate this disclosure, and the scope of this disclosure is not limited to these embodiments.

[0140] Example 1 Preparation of positive electrode active material slurry: LiNi prepared as the active material for the positive electrode 0.8 Co 0.1 Al 0.1 O2 (NCA) powder, sulfide-based solid electrolyte (Li6PS5Cl) powder, and CH3(CH2)7SH (1-octyl mercaptan) as a surface modifier were used. Polyvinylidene fluoride / hexafluoropropylene copolymer (PVdF / HFP) was prepared as a binder, and carbon nanofibers (CNF) were prepared as a conductive material. A slurry for the positive electrode active material was prepared by mixing these materials in an octyl acetate solvent at a weight ratio of positive electrode active material: solid electrolyte: surface modifier: conductive material: binder = 80:16:0.15:1.5:2.5.

[0141] Manufacturing of the positive electrode: A slurry of positive electrode active material is coated onto an aluminum positive electrode current collector and dried at 90°C for 5 hours to manufacture the positive electrode.

[0142] Fabrication of the solid electrolyte layer: A solid electrolyte slurry was prepared by adding a sulfogermanium ore-type solid electrolyte (Li6PS5Cl) to an isobutyl isobutyrate binder solution containing butyl acrylate polymers. The mixing ratio of the solid electrolyte to the binder was 98.7:1.3 by weight. The prepared solid electrolyte slurry was applied to a release polytetrafluoroethylene membrane and dried at 60°C for 2 hours to form a solid electrolyte layer.

[0143] Manufacturing of all-solid-state batteries: A coin cell is manufactured using the positive electrode, counter electrode (lithium metal), and solid electrolyte layer manufactured above.

[0144] Comparative Example 1 A positive electrode active material slurry excluding surface modifiers was prepared by mixing the positive electrode active material, solid electrolyte, conductive material, and binder in a weight ratio of 80:16:1.5:2.5. Except for this difference, the positive electrode active material slurry, positive electrode, solid electrolyte layer, and all-solid-state battery were manufactured in the same manner as in Example 1.

[0145] Comparative Example 2 Preparation of positive electrode active material slurry: The polymer coating solution was sprayed onto the silver sulfide germanium ore type solid electrolyte (Li6PS5Cl) powder, and then dried at 60°C for 2 hours to prepare a solid electrolyte with a polymer coating layer formed on it.

[0146] By using the positive electrode active material LiNi 0.8 Co 0.1 Al 0.1 O2 (NCA), the solid electrolyte prepared above, CNF conductive material, and polyvinylidene fluoride / hexafluoropropylene copolymer (PVdF / HFP) binder are mixed in a weight ratio of positive electrode active material: solid electrolyte: conductive material: binder = 80:16:1.5:2.5 to prepare a positive electrode slurry.

[0147] Manufacturing of all-solid-state batteries: The positive electrode, solid electrolyte layer, and all-solid-state battery were manufactured in the same manner as in Example 1.

[0148] Evaluation Example 1: Evaluation of Solid Electrolytes The positive electrode pastes according to Example 1, Comparative Example 1, and Comparative Example 2 were coated onto a substrate and cross-sectionalized. X-ray photoelectron spectroscopy (XPS) analysis was performed to evaluate the degree of degradation of the solid electrolyte. The results are shown in... Figure 7 middle.

[0149] Reference Figure 7 In Example 1 and Comparative Example 2, where the surface of the sulfide-based solid electrolyte was coated, the structure of the sulfide-based solid electrolyte was clearly observed, while in Comparative Example 1, where no surface treatment was performed, chemical changes due to degradation were observed.

[0150] Evaluation Example 2: Evaluation of the ionic conductivity of the positive electrode The positive electrode pastes prepared in each of Examples 1, 1 Comparative Example, and 2 were coated onto a substrate and dried at 90°C for 5 hours to form a positive electrode active material layer (coated product). The coated product was stamped into a circle with a diameter of 10 mm, and a sample was prepared by attaching a substrate to both sides. The sample was then placed in a measuring fixture and pressed under a pressure of 10 Nm. The impedance of the prepared sample was measured at 25°C with an amplitude of 10 mV and a frequency range of 0.01 Hz to 1 MHz. The resistance value was determined from the arcs of the Nyquist plot of the impedance measurement results, and the ionic conductivity was calculated considering the area and thickness of the sample. The measurement results are shown in Table 1 below.

[0151] Table 1:

[0152] Referring to Table 1, it can be seen that the positive electrode prepared according to Example 1 exhibits superior or improved ionic conductivity compared to the positive electrodes prepared according to Comparative Example 1 and Comparative Example 2. This may be because a chemical change occurred due to the deterioration of the solid electrolyte in the case of Comparative Example 1, while the residual coating layer in the case of Comparative Example 2 acts as a resistor.

[0153] Evaluation Example 3: Evaluation of the Lifetime Characteristics of All-Solid-State Batteries The lifetime characteristics of the all-solid-state batteries manufactured according to Example 1, Comparative Example 1, and Comparative Example 2 were evaluated using the following methods. The results are shown in Table 2 below.

[0154] The all-solid-state batteries manufactured in Example 1, Comparative Examples 1 and 2 were charged at 45°C with a constant current at a rate of 0.1C until the voltage reached 4.25V (relative to Li). Subsequently, charging continued in constant voltage mode, maintaining 4.25V, while a cutoff was applied at a current rate of 0.05C. Next, the batteries were discharged at a constant current rate of 0.1C until the voltage reached 2.8V (relative to Li) (formation cycle). After the formation cycle, the lithium batteries were charged at 45°C with a constant current rate of 0.5C until the voltage reached 4.25V (relative to Li). Then, the lithium batteries were discharged at a constant current rate of 0.5C until the voltage reached 2.8V (relative to Li). This cycle was repeated under the same conditions until the 100th cycle (100 repetitions). A 10-minute rest period was applied after each charge / discharge cycle. The results of the charge / discharge experiments are shown in Table 2 below.

[0155] Table 2:

[0156] Referring to Table 2, it can be seen that, in Comparative Example 1 without surface treatment, the lowest discharge capacity was observed during 1 to 100 cycles due to solid electrolyte degradation caused by the solvent. Comparative Example 2, where the solid electrolyte particles were coated with a polymer, showed better lifetime characteristics than Comparative Example 1. On the other hand, the surface modifier used in this disclosure effectively protects the solid electrolyte in the slurry state and is easily removed during electrode drying, thereby producing the highest ionic conductivity and the desired or improved lifetime characteristics.

[0157] The solid electrolyte composite according to this disclosure can have desired or improved solvent stability. Positive electrodes and solid electrolyte layers fabricated using this solid electrolyte composite can have desired or improved lifetime characteristics and desired or improved ionic conductivity.

[0158] 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 solid electrolyte complex, the solid electrolyte complex comprising: Sulfide solid electrolytes; and Surface modifiers are applied to the surface of the sulfide-based solid electrolyte. The surface modifier comprises a chain-like hydrocarbon chain and polar functional groups bonded to the chain-like hydrocarbon chain, and The surface modifier is attached to the surface of the sulfide-based solid electrolyte via the polar functional groups.

2. The solid electrolyte complex according to claim 1, in, The surface modifier adheres to the surface of the sulfide-based solid electrolyte via electrostatic attraction between the polar functional groups and the sulfide-based solid electrolyte.

3. The solid electrolyte complex according to claim 1, in, The polar functional group is in contact with the surface of the sulfide-based solid electrolyte.

4. The solid electrolyte complex according to claim 1, in, The polar functional groups include at least one of thiol, hydroxyl, amino, aldehyde, acetic acid, ester, and combinations thereof.

5. The solid electrolyte complex according to claim 1, in, The chain-like hydrocarbon chain has 5 to 15 carbon atoms.

6. The solid electrolyte complex according to claim 1, in, The surface modifier includes CH3(CH2). n SH, where 4≤n≤14.

7. The solid electrolyte complex according to claim 1, in, The surface modifier has a boiling point in the range of 120°C to 250°C.

8. The solid electrolyte complex according to claim 1, in, The sulfide-based solid electrolyte includes at least one of the following: Li 7-x PS 6-x Cl x Where 0 ≤ x ≤ 2; Li 7-x PS 6-x Br x Where 0 ≤ x ≤ 2; Li 7-x PS 6-x I x Where 0 ≤ x ≤ 2; Li 7-y M1 y PS 6-z M2 z Where 0 ≤ y ≤ 2 and 0 ≤ z ≤ 2; and combinations thereof, M1 includes at least one element from groups 3 to 15 of the periodic table, and M2 includes at least one element from Group 17 of the periodic table.

9. The solid electrolyte complex according to claim 1, in, The average particle size D50 of the sulfide-based solid electrolyte is in the range of 2 μm to 10 μm.

10. A positive electrode active material slurry, the positive electrode active material slurry comprising: Positive electrode active material and solid electrolyte complex, The solid electrolyte complex comprises: a sulfide-based solid electrolyte; and a surface modifier, on the surface of the sulfide-based solid electrolyte. The surface modifier comprises a chain-like hydrocarbon chain and polar functional groups bonded to the chain-like hydrocarbon chain, and The surface modifier is attached to the surface of the sulfide-based solid electrolyte via the polar functional groups.

11. The positive electrode active material slurry according to claim 10, in, The polar functional groups include at least one of thiol, hydroxyl, amino, aldehyde, acetic acid, ester, and combinations thereof.

12. The positive electrode active material slurry according to claim 10, in, The chain-like hydrocarbon chain has 5 to 15 carbon atoms.

13. The positive electrode active material slurry according to claim 10, in, The surface modifier includes CH3(CH2). n SH, where 4≤n≤14.

14. The positive electrode active material slurry according to claim 10, in, The surface modifier has a boiling point in the range of 120°C to 250°C.

15. The positive electrode active material slurry according to claim 10, in, The sulfide-based solid electrolyte includes at least one of the following: Li 7-x PS 6-x Cl x Where 0 ≤ x ≤ 2; Li 7-x PS 6-x Br x Where 0 ≤ x ≤ 2; Li 7-x PS 6-x I x Where 0 ≤ x ≤ 2; Li 7-y M1 y PS 6-z M2 z Where 0 ≤ y ≤ 2 and 0 ≤ z ≤ 2; and combinations thereof, M1 includes at least one element from groups 3 to 15 of the periodic table, and M2 includes at least one element from Group 17 of the periodic table.

16. The positive electrode active material slurry according to claim 10, in, The average particle size of the positive electrode active material is greater than the average particle size of the sulfide solid electrolyte.

17. The positive electrode active material slurry according to claim 10, wherein the positive electrode active material slurry further comprises: Conductive materials and adhesives.

18. A method for preparing a solid electrolyte complex, the method comprising the following steps: Prepare sulfide solid electrolytes; Prepare the surface modifier; as well as The sulfide-based solid electrolyte is mixed with the surface modifier; The surface modifier comprises a chain-like hydrocarbon chain and polar functional groups bonded to the chain-like hydrocarbon chain, and The surface modifier is attached to the surface of the sulfide-based solid electrolyte via the polar functional groups.

19. The method according to claim 18, in, The polar functional groups include at least one of thiol, hydroxyl, amino, aldehyde, acetic acid, ester, and combinations thereof, and The chain-like hydrocarbon chain has 5 to 15 carbon atoms.

20. The method according to claim 18, in, The sulfide-based solid electrolyte includes at least one of the following: Li 7-x PS 6-x Cl x Where 0 ≤ x ≤ 2; Li 7-x PS 6-x Br x Where 0 ≤ x ≤ 2; Li 7-x PS 6-x I x Where 0 ≤ x ≤ 2; Li 7-y M1 y PS 6-z M2 z Where 0 ≤ y ≤ 2 and 0 ≤ z ≤ 2; and combinations thereof, M1 includes at least one element from groups 3 to 15 of the periodic table, and M2 includes at least one element from Group 17 of the periodic table.

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