Solid electrolyte and all-solid-state battery comprising same

Abstract

The present invention relates to a solid electrolyte and an all-solid-state battery comprising same and, more specifically, to a solid electrolyte comprising: a first solid electrolyte layer; a second solid electrolyte layer; and an intermediate layer therebetween, wherein the intermediate layer comprises a composite derived from a mixture of a lithium salt and a cyclic polymer represented by structural formula 1.

Description

Solid electrolyte and all-solid-state battery including the same

[0001] The present invention relates to a solid electrolyte and an all-solid-state battery containing the same.

[0002] Recently, driven by industrial demands, the development of batteries with high energy density and safety is actively underway. For example, lithium-ion batteries are being commercialized not only in the fields of information and communication devices but also in the automotive sector. In the automotive sector, safety is considered particularly important because it is directly related to human life.

[0003] Recently, all-solid-state batteries in which liquid electrolytes are replaced with solid electrolytes have been proposed. By not using flammable organic dispersion media, all-solid-state batteries can significantly reduce the likelihood of fire or explosion in the event of a short circuit. Therefore, these all-solid-state batteries can offer significantly higher safety compared to lithium-ion batteries that use liquid electrolytes.

[0004] The problem that the present invention aims to solve is to provide a solid electrolyte with low resistance and excellent ionic conductivity.

[0005] Another problem that the present invention aims to solve is to provide an all-solid-state battery with low resistance and excellent ion conductivity.

[0006] A solid electrolyte according to one embodiment of the present invention comprises: a first solid electrolyte layer; a second solid electrolyte layer; and an intermediate layer between the first solid electrolyte layer and the second solid electrolyte layer, wherein the intermediate layer may comprise a composite derived from a mixture of a cyclic polymer represented by the following structural formula 1 and a lithium salt:

[0007] [Structural Formula 1]

[0008]

[0009] In the above structural formula 1, n can be 1 to 1000.

[0010] A solid-state battery according to one embodiment of the present invention comprises: a positive electrode layer including a positive current collector and a positive active material layer; a negative electrode layer including a negative current collector and a coating layer; and a solid electrolyte layer between the positive electrode layer and the negative electrode layer, wherein the solid electrolyte layer may include the solid electrolyte described above.

[0011] An all-solid-state battery according to one embodiment of the present invention comprises: a positive electrode layer comprising a positive current collector and a positive active material layer; a negative electrode layer comprising a negative current collector and a coating layer; and a solid electrolyte layer between the positive electrode layer and the negative electrode layer, wherein at least one of the positive active material layer or the coating layer may comprise a composite derived from a mixture of a cyclic polymer represented by the following structural formula 1 and a lithium salt:

[0012] [Structural Formula 1]

[0013]

[0014] In the above structural formula 1, n can be 1 to 1000.

[0015] A solid electrolyte according to one embodiment of the present invention may have low resistance and excellent ionic conductivity.

[0016] An all-solid-state battery according to one embodiment of the present invention may have low resistance and excellent ion conductivity.

[0017] FIG. 1 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0018] FIG. 2 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0019] FIG. 3 is a cross-sectional view of a solid electrolyte layer according to one embodiment of the present invention.

[0020] In order to fully understand the structure and effects of the present invention, preferred embodiments of the present invention are described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and various modifications can be made. The description of these embodiments is provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention.

[0021] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Additionally, in the drawings, the thicknesses of the components are exaggerated for the effective description of the technical content. Throughout the specification, parts indicated by the same reference numeral represent the same components.

[0022] The embodiments described herein will be described with reference to cross-sectional and / or plan views, which are exemplary illustrations of the invention. In the drawings, the thicknesses of films and regions are exaggerated for effective description of the technical content. Accordingly, the regions illustrated in the drawings are schematic in nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific forms of regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, third, etc., have been used to describe various components in the various embodiments of this specification, these components should not be limited by such terms. These terms are used merely to distinguish one component from another. The embodiments described and illustrated herein also include their complementary embodiments.

[0023] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, 'comprises' and / or 'comprising' do not exclude the presence or addition of one or more other components to the mentioned components.

[0024] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0025] Unless otherwise defined in this specification, the particle size may be the average particle size. Additionally, the particle size refers to the average particle size (D50), which means the diameter of the particle whose cumulative volume in the particle size distribution is 50% by volume. The average particle size (D50) may be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) image or a scanning electron microscope (SEM) image. Alternatively, the average particle size (D50) value may be obtained by measuring using a measuring device utilizing dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this. Alternatively, it may be measured using a laser diffraction method. When measuring by laser diffraction, more specifically, after dispersing the particles to be measured in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasound of about 28 kHz at an output of 60 W, and then the average particle size (D50) at 50% of the particle size distribution in the measuring device can be calculated.

[0026] In this specification, each of the phrases such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0027]

[0028] FIG. 1 is a cross-sectional view of an all-solid-state battery (10) according to one embodiment of the present invention.

[0029] Referring to FIG. 1, an all-solid-state battery (10) according to one embodiment includes 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 all-solid-state battery (10) may further include an additional functional layer, such as an adhesion-enhancing 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] An anode layer (100) of one embodiment includes an anode current collector (110) and an anode active material layer (120) disposed on the anode current collector (110). The anode active material layer (120) may include an anode active material, a solid electrolyte, a conductive material, and a binder.

[0031] The positive current collector (110) can provide a reference surface on which the positive active material layer (120) is placed. The positive current collector (110) may include, for example, a plate or foil comprising indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0032] Meanwhile, unlike as illustrated in FIG. 1, the positive current collector (110) may be omitted in one embodiment of the present invention. Although not illustrated, a carbon layer with a thickness of 0.1 μm to 4 μm may be further disposed between the positive current collector (110) and the positive active material layer (120) to increase the bonding strength between the positive current collector (110) and the positive active material layer (120).

[0033] The cathode active material is a material capable of reversibly absorbing and desorbing lithium ions. The cathode active material may include, for example, 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 manganate, and lithium iron phosphate, as well as nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but is not necessarily limited to these. Each cathode active material may be a single material or a mixture of two or more materials.

[0034] Lithium transition metal oxides are, for example, Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Li a E 1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2-b B b O 4-c D c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Co b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Mn b B c D α(0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2), Li a Nor 1-b-c Mn b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Nor b E c G d O2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1), Li a Nor b Co c Mn d GeO2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1), Li a NiG b O2(0.9≤a≤1, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a MnG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a Mn2GbO4(0.90≤a≤1, 0.001≤b≤0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li 3-f J2(PO4)3(0≤f≤2), Li 3-fIt is a compound represented by any one of Fe2(PO4)3 (0≤f≤2) or LiFePO4. In such compounds, the uppercase “A” is Ni, Co, Mn, or a combination thereof; the uppercase “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; the uppercase “D” is O, F, S, P, or a combination thereof; the uppercase “E” is Co, Mn, or a combination thereof; the uppercase “F” is F, S, P, or a combination thereof; the uppercase “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; the uppercase “Q” is Ti, Mo, Mn, or a combination thereof; the uppercase “I” is Cr, V, Fe, Sc, Y, or a combination thereof; and the uppercase “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0035] The cathode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen and metal atomic layers are alternately and regularly arranged in a specific direction, thereby forming a two-dimensional plane for each atomic layer. The "cubic rock salt type structure" represents a sodium chloride (NaCl) type structure, which is a type of crystal structure; specifically, it exhibits a structure in which face-centered cubic lattices (fcc) formed by cations and anions, respectively, are offset from each other by half the ridge of the unit lattice. Lithium transition metal oxides having such a layered rock salt type structure are, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn zO2(NCM) (0 <x<1,0<y<1, 0<z<1, x+y+z=1) 등의 삼원계 리튬전이금속산화물일 수 있다. 양극활물질이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 전고체 전지(10)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0036] The aforementioned compound contained in the cathode active material may be covered by a coating layer (not shown). The cathode active material may also be a mixture of the aforementioned compound and the compound to which the coating layer is added. Meanwhile, the coating layer added to the surface of the cathode active material may include, for example, oxides, hydroxides, oxyhydroxides, oxycarbonates, or hydroxycarbonates of the following coating elements. The compounds forming this coating layer are amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer may include, for example, Li2O-ZrO2 (LZO). The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the cathode active material. The method for forming the coating layer is, for example, spray coating or immersion.

[0037] When the positive electrode active material is a ternary lithium transition metal oxide such as NCA or NCM and contains nickel (Ni), the capacity density of the all-solid-state battery (10) is increased, and the metal leaching of the positive electrode active material in the charged state can be reduced. As a result, the cycle characteristics of the all-solid-state battery (10) in the charged state are improved. Meanwhile, “cycle characteristics” is a characteristic that indicates the degree of deterioration of the all-solid-state battery (10) due to charging and discharging of the all-solid-state battery (10). An all-solid-state battery (10) with high cycle characteristics has a small degree of deterioration due to charging and discharging, while an all-solid-state battery (10) with low cycle characteristics may have a large degree of deterioration due to charging and discharging.

[0038] The shape of the cathode active material may include particle shapes such as spheres or ellipsoids. The particle size and content of the cathode active material are not particularly limited.

[0039] The solid electrolyte may include a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. Sulfide-based solid electrolytes 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, n are positive numbers, uppercase “Z” is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, uppercase “M” is one of P, Si, Ge, B, Al, Ga, 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 It may include at least one selected from (0≤x≤2).

[0040] Sulfide-based solid electrolytes are, for example, 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 xIt may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0041] Alternatively, sulfide-based solid electrolytes are Li 7-a M a PS 6-c X c It may be an argyrodite-type compound containing (0≤a≤2, 0≤c≤2). Here, X may be F, Br, Cl, or a combination thereof. M can be scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. there is.

[0042] The density of the azyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. By having a density of 1.5 g / cc or higher for the azyrodite-type solid electrolyte, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0043] The solid electrolyte included in the positive electrode active material layer (120) may have a smaller average particle size (D50) compared to the solid electrolyte included in the solid electrolyte layer (300). For example, the average particle size (D50) of the solid electrolyte included in the positive electrode active material layer (120) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the average particle size (D50) of the solid electrolyte included in the solid electrolyte layer (300). Meanwhile, the average particle size (D50) may be a median diameter measured using a laser particle size distribution meter.

[0044] The positive electrode active material layer (120) may include a conductive material. The conductive material may have conductivity without causing chemical changes in the all-solid-state battery (10), thereby increasing the conductivity of the positive electrode active material and the solid electrolyte. The conductive material may include a carbon-based material. The conductive material may include, for example, one or more selected from graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0045] The positive active material layer (120) may further include a binder. The binder may include a material for bonding the positive active material, solid electrolyte, and conductive material included in the positive active material layer (120), and for improving the bonding strength with the positive current collector (110). The binder may include, for example, polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0046] Based on 100 parts by weight of the total positive active material, solid electrolyte, conductive material, and binder, the positive active material layer (120) may contain 85 parts by weight or more and 92 parts by weight or less of the positive active material. Based on 100 parts by weight of the total positive active material, solid electrolyte, conductive material, and binder, the positive active material layer (120) may contain 0.5 parts by weight or more and 1.5 parts by weight or less of the binder.

[0047] Based on 100 parts by weight of solid electrolyte, the positive active material layer (120) may contain 1 part by weight or more and 50 parts by weight or less of a conductive material. If the conductive material is included in the positive active material layer (120) in an amount less than 1 part by weight based on 100 parts by weight of solid electrolyte, the proportion of the conductive material decreases, and the electrical conductivity of the positive active material layer (120) may decrease. If the conductive material is included in the positive active material layer (120) in an amount exceeding 50 parts by weight based on 100 parts by weight of solid electrolyte, the proportion of the conductive material is excessively high, and a coating layer covering the surface of the solid electrolyte may not be properly formed.

[0048] The positive active material layer (120) may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids in addition to the positive active material, solid electrolyte, conductive material, and binder described above.

[0049] The solid electrolyte layer (300) is disposed between the positive electrode layer (100) and the negative electrode layer (200) and includes a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. The solid electrolyte included in the solid electrolyte layer (300) may be the same as or different from any one of the materials that can be included in the solid electrolyte included in the aforementioned positive electrode active material layer (120).

[0050] The solid electrolyte layer (300) of one embodiment may include a sulfide-based solid electrolyte. The sulfide-based solid electrolyte may be manufactured by processing starting materials, such as Li2S or P2S5, by a melt quenching method or a mechanical milling method. Additionally, heat treatment may be performed after such processing. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. Furthermore, the solid electrolyte may include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the sulfide-based solid electrolyte materials described above, for example. For example, the solid electrolyte may be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material containing Li2S-P2S5 to form the solid electrolyte, the molar ratio of Li2S and P2S5 is, for example, in the range of Li2S : P2S5 = 50 : 50 to 90 : 10.

[0051] Sulfide-based solid electrolytes are, for example, 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 It may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0052] Alternatively, sulfide-based solid electrolytes are Li 7-a M a PS 6-c X cIt may be an argyrodite-type compound containing (0≤a≤2, (0≤c≤2)). Here, X may be F, Br, Cl, or a combination thereof. M can be scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. there is.

[0053] The density of the azyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. By having a density of 1.5 g / cc or higher for the azyrodite-type solid electrolyte, 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 prevented. The elastic modulus of the solid electrolyte is, for example, 15 GPa to 35 GPa.

[0054] The solid electrolyte layer (300) may further include a binder. The binder included in the solid electrolyte layer (300) is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these. The binder of the solid electrolyte layer (300) may be the same as or different from the binder included in the positive electrode active material layer (120) or the binder included in the coating layer (220).

[0055] 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 placed. The negative electrode current collector (210) may include, for example, a material that does not react with lithium, that is, does not form any alloys or compounds with lithium. For example, the negative electrode current collector (210) may include at least one metal selected from the group consisting of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative electrode current collector (210) may be about 10 μm. The thickness of the negative electrode current collector (210) may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0056] The negative current collector (210) may be composed of one of the metals described above, or may include an alloy of two or more metals or a coating material. The negative current collector (210) may, for example, have a plate-like or foil-like shape. Meanwhile, in one embodiment, the negative current collector (210) may be omitted.

[0057] The negative electrode layer (200) may further include a second electrode tab extending from one side of the negative electrode current collector (210). The second electrode tab may be welded to an electrode lead and connected to an external terminal. The electrode lead welded to the second electrode tab may be different from the electrode lead welded to the first electrode tab.

[0058] The coating layer (220) can cause lithium metal to grow between the all-solid-state battery (10) and the negative current collector (210) during charging. Alternatively, the coating layer (220) can cause lithium metal to grow or form an alloy with lithium inside the all-solid-state battery (10) during charging. The coating layer (220) can serve as a protective layer for lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0059] The coating layer (220) may include metal and carbon. For example, the coating layer (220) may include at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The coating layer (220) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In one embodiment, the coating layer (220) may include a mixture of carbon black and silver (Ag).

[0060] The coating layer (220) may further include other additives in addition to metal and carbon. The coating layer (220) may further include at least one additive selected from the group consisting of, for example, binders, fillers, coating agents, dispersants, and ion-conducting aids.

[0061] For example, the loading amount of the coating layer (220) is 0.1 mg / cm² 2 Up to 5 mg / cm² 2 It could be.

[0062] The coating layer (220) may have a smaller thickness compared to the positive active material layer (120). The thickness of the coating layer (220) may be, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive active material layer (120). The thickness of the coating layer (220) may be, for example, 1 µm to 20 µm, 2 µm to 10 µm, or 3 µm to 7 µm. The thickness of the coating layer (220) may be about 10 µm. If the thickness of the coating layer (220) is excessively thin, lithium dendrites formed between the coating layer (220) and the negative current collector (210) may cause the coating layer (220) to collapse, thereby degrading the cycle characteristics of the all-solid-state battery (10). If the thickness of the coating layer (220) increases excessively, the energy density of the all-solid-state battery (10) decreases and the internal resistance of the all-solid-state battery (10) due to the coating layer (220) increases, which may degrade the cycle characteristics of the all-solid-state battery (10).

[0063] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the coating layer (220) and the solid electrolyte layer (300).

[0064] Referring again to FIG. 1, the positive active material layer (120) may have a first width (WI1) in a first direction (D1). The coating layer (220) may have a second width (WI2) in a first direction (D1).

[0065] For example, the first width (WI1) of the positive active material layer (120) may be substantially the same as the second width (WI2) of the coating layer (220). In this specification, substantially the same width may be defined as the difference between the two widths being within 10%.

[0066] As another example, the first width (WI1) of the positive active material layer (120) may be smaller than the second width (WI2) of the coating layer (220).

[0067] At least one of the positive active material layer (120) or the coating layer (220) may include a composite to be described later. By including the composite, the resistance of the positive active material layer (120) and / or the coating layer (220) can be lowered and the ion conductivity improved.

[0068]

[0069] FIG. 2 is a cross-sectional view of an all-solid-state battery (10) according to another embodiment of the present invention. FIG. 3 is a cross-sectional view for explaining the solid electrolyte layer (300) of FIG. 2. Hereinafter, for convenience of explanation, the description of matters identical to those described with reference to FIG. 1 is omitted, and the differences are described in detail.

[0070] Referring to FIGS. 2 and 3, the solid electrolyte layer (300) is disposed between the anode layer (100) and the cathode layer (200) and may include a first solid electrolyte layer (SEL1), an intermediate layer (MDL), and a second solid electrolyte layer (SEL2).

[0071] The first solid electrolyte layer (SEL1) can be placed on the coating layer (220).

[0072] The first solid electrolyte layer (SEL1) may include first electrolyte particles. The first electrolyte particles may include a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. The description of the sulfide-based solid electrolyte is as described above. The solid electrolyte included in the first solid electrolyte layer (SEL1) may be the same as or different from any one of the materials that may be included in the solid electrolyte included in the aforementioned positive electrode active material layer (120).

[0073] The first solid electrolyte layer (SEL1) may further include a binder. The description of the binder is as described above. The binder of the first solid electrolyte layer (SEL1) may be the same as or different from the binder included in the positive active material layer (120) or the binder included in the coating layer (220).

[0074] The thickness (TKL1) of the first solid electrolyte layer (SEL1) may be 15㎛ to 100㎛. For example, the thickness (TKL1) of the first solid electrolyte layer (SEL1) may be 15㎛ to 90㎛, 15㎛ to 80㎛, 15㎛ to 70㎛, 15㎛ to 60㎛, 15㎛ to 50㎛, 20㎛ to 50㎛, or 30㎛ to 40㎛.

[0075] The first solid electrolyte layer (SEL1) may have a fourth width (WI4) in the first direction (D1). For example, the fourth width (WI4) of the first solid electrolyte layer (SEL1) may be substantially the same as the second width (WI2) of the coating layer (220).

[0076] The second solid electrolyte layer (SEL2) can be placed on the lower surface of the positive active material layer (120).

[0077] The second solid electrolyte layer (SEL2) may include second electrolyte particles. The second electrolyte particles may include a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. The description of the sulfide-based solid electrolyte is as described above. The solid electrolyte included in the second solid electrolyte layer (SEL2) may be the same as or different from any one of the materials that may be included in the solid electrolyte included in the aforementioned positive electrode active material layer (120).

[0078] The second solid electrolyte layer (SEL2) may further include a binder. The description of the binder is as described above. The binder of the second solid electrolyte layer (SEL2) may be the same as or different from the binder included in the positive active material layer (120) or the binder included in the coating layer (220).

[0079] The thickness (TKL2) of the second solid electrolyte layer (SEL2) may be 15㎛ to 100㎛. For example, the thickness (TKL1) of the first solid electrolyte layer (SEL1) may be 15㎛ to 90㎛, 15㎛ to 80㎛, 15㎛ to 70㎛, 15㎛ to 60㎛, 15㎛ to 50㎛, 20㎛ to 50㎛, or 30㎛ to 40㎛.

[0080] The second solid electrolyte layer (SEL2) may have a third width (WI3) in the first direction (D1). For example, the third width (WI3) of the second solid electrolyte layer (SEL2) may be substantially the same as the first width (WI1) of the positive active material layer (120).

[0081] An intermediate layer (MDL) may be disposed on the upper surface of the first solid electrolyte layer (SEL1). An intermediate layer (MDL) may be disposed on the lower surface of the second solid electrolyte layer (SEL2). An intermediate layer (MDL) may be disposed between the first solid electrolyte layer (SEL1) and the second solid electrolyte layer (SEL2). The intermediate layer (MDL) may have adhesive properties. The intermediate layer (MDL) may bond the first solid electrolyte layer (SEL1) and the second solid electrolyte layer (SEL2) together.

[0082] The thickness (TKM) of the intermediate layer (MDL) may be 0.01 μm to 20 μm. For example, the thickness (TKM) of the intermediate layer (MDL) may be 0.01 μm to 15 μm, or 0.01 μm to 10 μm. For example, the thickness (TKM) of the intermediate layer (MDL) may be about 0.01 μm, or about 0.1 μm, or about 1 μm, or about 10 μm.

[0083] The intermediate layer (MDL) may have a fifth width (WIM) in the first direction (D1). For example, the fifth width (WIM) of the intermediate layer (MDL) may be substantially the same as the fourth width (WI4) of the first solid electrolyte layer (SEL1). For example, the fifth width (WIM) of the intermediate layer (MDL) may be substantially the same as the third width (WI3) of the second solid electrolyte layer (SEL2). For example, the fifth width (WIM) of the intermediate layer (MDL), the fourth width (WI4) of the first solid electrolyte layer (SEL1), and the third width (WI3) of the second solid electrolyte layer (SEL2) may be substantially the same as each other.

[0084] The intermediate layer (MDL) may include a composite to be described later. By including the composite, the resistance of the solid electrolyte layer (300) can be lowered and the ion conductivity improved.

[0085] The complex is explained in detail below.

[0086]

[0087] complex

[0088] The composite according to the embodiments of the present invention may be derived from a mixture of a cyclic polymer represented by the following structural formula 1 and a lithium salt.

[0089] [Structural Formula 1]

[0090]

[0091] In the above structural formula 1, n can be 1 to 1000.

[0092] The viscosity of the complex at 25°C may be 550 cP or higher. For example, the viscosity of the complex at 25°C may be 550 cP to 700 cP, or 550 cP to 650 cP. As an example, the viscosity of the complex may be measured in the form of a composition containing the complex. As an example, the composition may contain 1% to 5% by weight of the complex. As an example, the composition may include dichloromethane, acetonitrile, tetrahydrofuran, etc. as a solvent.

[0093] The composite can be derived by mixing a cyclic polymer and a lithium salt in a molar ratio of 3:1 to 12:1. The composite can be prepared by introducing a lithium salt into the cyclic polymer and mixing the cyclic polymer and the lithium salt so that the solid lithium salt disappears. For example, the composite can be derived by mixing a cyclic polymer and a lithium salt in a molar ratio of 3:1 to 12:1, 3:1 to 8:1, or 3:1 to 5:1. When the cyclic polymer and the lithium salt are mixed within the ranges described above, the composite is a lithium cation (Li + It can provide ) and lithium cations (Li +It can facilitate the movement of ). The composite can be applied to all-solid-state batteries to increase ion conductivity and lower resistance.

[0094] Cyclic polymers may contain not only oxygen atoms (O) but also sulfur atoms (S) within the chain. Oxygen atoms (O) and sulfur atoms (S) may contain lone pairs of electrons. The oxygen atoms (O) and sulfur atoms (S) of the cyclic polymer are each lithium cations (Li) of a lithium salt. + ) can combine with. For example, the oxygen atoms (O) and sulfur atoms (S) of a cyclic polymer can each combine with the lithium cations (Li) of a lithium salt. + It can form a coordinate bond with )

[0095] The cyclic polymer may contain a plurality of oxygen atoms (O). In the composite, at least one of the plurality of oxygen atoms (O) is a lithium cation (Li) of a lithium salt. + It can combine with ). For example, the bond can be a coordinate bond.

[0096] The cyclic polymer may contain a plurality of sulfur atoms (S). In the complex, at least one of the plurality of sulfur atoms (S) is a lithium cation (Li) of a lithium salt. + It can combine with ). For example, the bond can be a coordinate bond.

[0097] In the complex, the cyclic polymer contains lithium cations (Li of the lithium salt) + It can be configured to chelate ) . The cyclic polymer chelates the lithium cations (Li) of the lithium salt through oxygen atoms (O) and sulfur atoms (S). + It can be configured to chelate ).

[0098] The number average molecular weight (Mn) of the cyclic polymer may be 2,000 to 60,000. The weight average molecular weight (Mw) of the cyclic polymer may be 5,000 to 300,000.

[0099] The viscosity of the cyclic polymer at 25°C may be less than 550 cP. For example, the viscosity of the cyclic polymer at 25°C may be 400 cP or more and less than 550 cP, or 450 cP to 500 cP. As an example, the viscosity of the cyclic polymer may be measured in the form of a composition containing the cyclic polymer. As an example, the composition may contain 1% to 5% by weight of the composite. As an example, the composition may include dichloromethane, acetonitrile, tetrahydrofuran, etc. as a solvent.

[0100] If the number average molecular weight (Mn), weight average molecular weight (Mw), and viscosity of the cyclic polymer satisfy the ranges described above, the cyclic polymer can be mixed with a lithium salt such that the solid lithium salt disappears within the mixture, and a composite can be manufactured.

[0101] Cyclic polymers can be prepared to have the viscosity described above. For example, they can be prepared by mixing a dithiol containing two thiol groups with triethylamine. However, they are not limited to the examples described.

[0102] Lithium salts are lithium cations (Li + It may include ) and anions. In lithium salts, lithium cations (Li + ) and anions can form ionic bonds with each other (hereinafter, first ionic bond). For example, the lithium salt is LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiN(C x F2x+1 SO2)(C y F 2y+1 It may include at least one of SO2)(x and y are integers from 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBOP), lithium bis(oxalate)borate (LiBOB), or a combination thereof.

[0103] For example, within a complex, the lithium cations (Li of a cyclic polymer and a lithium salt) of the lithium salt + ) can be combined in the form of the following structural formula 2.

[0104] [Structural Formula 2]

[0105]

[0106] Referring to Structural Formula 2, within the complex, the lithium cation (Li of the lithium salt + ) can form bonds with oxygen atoms (O) or sulfur atoms (S) of cyclic polymers. For example, lithium cations (Li) of lithium salts + ) can form a coordinate bond with the oxygen atom (O) or sulfur atom (S) of the cyclic polymer. Within the complex, the lithium cation (Li) of the lithium salt + ) can be attracted by oxygen atoms (O) or sulfur atoms (S) of the cyclic polymer. Within the complex, lithium cations (Li of the lithium salt) + The ionic bond between ) and the anion (hereinafter, the second ionic bond) may be relatively weak. The lithium cation (Li) in the complex + The ionic bond (second ionic bond) between ) and the anion is a lithium cation (Li) in a lithium salt that does not form a complex. + It can be weaker than the ionic bond (first ionic bond) between ) and anion. The complex consists of lithium cations (Li) in the lithium salt. + It can weaken the ionic bond (first ionic bond) between the ) and the anion.

[0107] For example, the complex may include both a first lithium cation bonded to a cyclic polymer and a second lithium cation not bonded to a cyclic polymer. The ionic bond between the anion of the lithium salt and the first lithium cation (second ionic bond) may be weaker than the ionic bond between the anion of the lithium salt and the second lithium cation (first ionic bond).

[0108] Referring to Structural Formula 2, the complex consists of an oxygen atom (O) and a lithium cation (Li) of a lithium salt. + Bonding with ) (hereinafter, first coordinate bond) and a sulfur atom (S) and a lithium cation (Li of a lithium salt) + It may include all combinations with ) (hereinafter, second coordinate combinations).

[0109] The electronegativity of the oxygen atom (O) can be approximately 3.5. The electronegativity of the sulfur atom (S) can be lower than that of the oxygen atom (O). For example, the electronegativity of the sulfur atom (S) can be approximately 2.5. The size of the oxygen atom (O) can be smaller than that of the sulfur atom (S). Thus, the oxygen atom (O) is smaller than the lithium cation (Li + Sulfur atoms (S) can form relatively strong bonds with lithium cations (Li) compared to oxygen atoms (O). + It can form a relatively weak bond with ) and within the complex, sulfur atoms (S) and lithium cations (Li + The bond with ) (second coordinate bond) is formed between an oxygen atom (O) and a lithium cation (Li + It may be weaker than the bond with (first coordinate bond).

[0110] Sulfur atoms (S) and lithium cations (Li + The bonding with ) (second coordination bond) is a lithium cation (Li) within the complex. + It is possible to prevent ) from bonding too strongly. Sulfur atom (S) and lithium cation (Li + Through bonding with ) (second coordinate bond), the complex forms a lithium cation (Li +It can combine with ) with appropriate force. Sulfur atoms (S) and lithium cations (Li + Through bonding with ) (second coordinate bond), the complex forms a lithium cation (Li + This can prevent the phenomenon of ) being trapped within the complex.

[0111] For example, bonds within a complex can be identified through infrared spectroscopic analysis. For instance, in the infrared spectroscopic spectrum of a complex, oxygen atoms (O) and lithium cations (Li + The first peak corresponding to the bonding (first coordinate bond) with ) and the sulfur atom (S) and lithium cation (Li + A second peak corresponding to the bond (second coordination bond) may be newly observed, or the maximum peak intensities of the first and second peaks may increase due to the formation of the complex. For example, in the infrared spectroscopic spectrum of the complex, the positions of the peaks corresponding to the CO bond, CS bond, or CC bond of the cyclic polymer may change or the maximum peak intensities may increase.

[0112] For example, bonds within the complex can be identified through nuclear magnetic resonance spectra. For instance, the position of the peaks appearing in the lithium element nuclear magnetic resonance spectrum for the complex and the lithium element nuclear magnetic resonance spectrum for the lithium salt may change. This allows us to confirm that the ionic bond (secondary ionic bond) between the anion of the lithium salt and the first lithium cation within the complex is weaker than the ionic bond (first ionic bond) between the anion of the lithium salt and the second lithium cation that is not bonded to the cyclic polymer.

[0113] In another example of the present invention, the composite may further include a glyme. For example, the glyme may include a monoglyme, a diglyme, a triglyme, etc. For example, the composite may be derived by mixing a cyclic polymer and a lithium salt in a molar ratio of 3:1 to 12:1, and mixing the lithium salt and a glyme in a molar ratio of 1:1 to 1:0.1.

[0114]

[0115] The composite according to the embodiments of the present invention may have the following characteristics.

[0116] The composite according to the embodiments of the present invention is a lithium cation (Li) of a lithium salt. + While weakening the ionic bond between ) and the anion, the lithium cation (Li + ) can be prevented from being bound too strongly within the complex. The complex according to the embodiments of the present invention is a lithium cation (Li + It can provide ) and lithium cations (Li + It can facilitate the movement of ). The complex is lithium cations (Li + It can increase the concentration of ). The complex is lithium cations (Li + It can allow ) to move freely. The composite can be applied to all-solid-state batteries to increase ion conductivity and lower resistance.

[0117] The composite may be an additive. The composite may be added to a slurry during the manufacture of the electrode plate. A slurry containing the composite may be applied and dried on a current collector to form an electrode plate. For example, a positive active material layer slurry containing the composite may be applied and dried on a positive current collector (110) to form a positive layer (100). For example, a coating layer slurry containing the composite may be applied and dried on a negative current collector (210) to form a negative layer (200). Thus, the composite can provide an electrode plate (positive layer (100) or negative layer (200)) and an all-solid-state battery (10) having low resistance and high ion conductivity.

[0118] When the composite is formed into a film, it may have adhesive properties. An intermediate layer (MDL) containing the composite can bond the first solid electrolyte layer (SEL1) and the second solid electrolyte layer (SEL2) to each other and reduce voids within the interface between the first solid electrolyte layer (SEL1) and the second solid electrolyte layer (SEL2). By doing so, the composite can provide a solid electrolyte layer (300) with low resistance and high ionic conductivity and an all-solid-state battery (10). For example, the resistance of the solid electrolyte layer (300) may be 50Ω or less, 40Ω or less, 30Ω or less, or 20Ω or less. For example, the ionic conductivity of the solid electrolyte layer (300) may be 0.1 mS / cm to 10 mS / cm, or 0.1 mS / cm to 1 mS / cm.

[0119] The present invention will be explained in more detail below through examples. However, these examples are intended to illustrate the invention and the scope of the invention is not limited to these examples.

[0120]

[0121] Example 1

[0122] Preparation Example 1: Preparation of a coating composition containing a composite

[0123] A solution was prepared containing a cyclic polymer represented by the following structural formula 1 and a solvent (dichloromethane). The content of the cyclic polymer in the solution was 3 wt%, it was a transparent solution, and its viscosity at 25°C was 497 cP. The solution was mixed with lithium bis(trifluoromethanesulfoyl)imide (LiFSI) as a lithium salt. The cyclic polymer and the lithium salt were mixed in a molar ratio of 4:1. After mixing, the solid lithium salt disappeared, and a transparent solution with a viscosity slightly higher than that of the cyclic polymer was obtained. Thus, a coating composition containing a composite of the cyclic polymer and the lithium salt was prepared. The content of the composite in the coating composition was approximately 3 wt%, and its viscosity at 25°C was 600 cP.

[0124] [Structural Formula 1]

[0125]

[0126]

[0127] Preparation Example 2: Preparation of the cathode layer

[0128] A SUS foil with a thickness of 10 μm was prepared as a cathode current collector. Additionally, carbon black (CB) with a primary particle size of 30 nm and silver (Ag) particles with an average particle size (D50) of 60 nm were prepared as coating layer materials. 4 g of a mixed powder, prepared by mixing carbon black (CB) and silver (Ag) particles in a weight ratio of 3:1, was placed in a container, and 4 g of an NMP solution containing 7 wt% of a PVDF binder (Kureha # 9300) was added to prepare a mixed solution. Subsequently, a slurry was prepared by stirring the mixed solution while gradually adding NMP to it. The prepared slurry was applied to a Ni sheet using a bar coater and dried in air at 80°C for 10 minutes. The resulting laminate was vacuum dried at 40°C for 10 hours. The dried laminate was then cold-roll-pressed to flatten the surface of the coating layer of the laminate. A cathode layer was fabricated by the above process. The thickness of the coating layer included in the cathode layer was 7 μm. The area of ​​the coating layer and the cathode current collector were the same.

[0129]

[0130] Preparation Example 3: Preparation of a solid electrolyte layer

[0131] A mixture was prepared by adding 1 part by weight of a polytetrafluoroethylene (PTFE) first binder and 1 part by weight of a polyvinylidene fluoride (PVDF) second binder to 98 parts by weight of an argyrodite-type crystal Li6PS5Cl sulfide-based solid electrolyte (D50 = 3㎛, crystalline) in a grind mixer and mixing them. A dough was prepared by adding the prepared mixture to a mortar heated to 80°C and stirring it. The prepared dough was passed through a roller and formed into a sheet shape to prepare a solid electrolyte film of a uniform thickness. A solid electrolyte layer was manufactured by the above process. The above solid electrolyte layer prepared a second solid electrolyte layer (SEL2) having substantially the same area as the anode layer and a first solid electrolyte layer (SEL1) having substantially the same area as the cathode layer. The elastic modulus of the sulfide-based solid electrolyte was about 15 GPa to 30 GPa.

[0132]

[0133] Preparation Example 4: Preparation of a symmetrical cell

[0134] A cathode layer and a first solid electrolyte layer (SEL1) were laminated and pressed using a roll press method. A cathode composite layer was prepared by applying a linear pressure of 2.0 ton / cm at 120°C.

[0135] The coating composition of Preparation Example 1 was spray-coated onto the coating layer of the cathode composite layer. The cathode composite layer was placed on a temperature-controlled support plate, and the coating composition was sprayed under a hydrogen atmosphere. After spray coating, the intermediate layer (MDL) was formed by drying at a temperature of 60°C.

[0136] Another cathode composite layer was placed on the intermediate layer (MDL), and a symmetric cell was manufactured by applying pressure using a roll press method. The pressure was applied at a temperature of 160°C and a linear pressure of 0.5 ton / cm. Thus, the symmetric cell contained two different cathode composites and an intermediate layer (MDL) between them. The solid electrolyte layer within the symmetric cell contained two first solid electrolyte layers (SEL1) and an intermediate layer (MDL) between them. The thickness of each of the first solid electrolyte layers (SEL1) was 60 μm. The intermediate layer (MDL) bonded the first solid electrolyte layers (SEL1) together.

[0137]

[0138] Preparation Example 5: Preparation of the anode layer

[0139] LiNi coated with Li2O-ZrO2 (LZO) as a cathode active material 0.8 Co 0.15 Mn 0.05O2 (NCM) was prepared. The LZO-coated cathode active material was prepared according to the method disclosed in Korean Patent Publication No. 10-2016-0064942. As a solid electrolyte, Li6PS5Cl, an argyrodite-type crystal (D50 = 0.5 μm, crystalline), was prepared. As a binder, a polytetrafluoroethylene (PTFE) binder was prepared. As a conductive agent, carbon nanofiber (CNF) was prepared. A slurry was formed by mixing these materials with a xylene solvent in a weight ratio of cathode active material : solid electrolyte : conductive agent : binder = 84 : 11.5 : 3 : 1.5, and then vacuum-dried at 40°C for 8 hours to produce a cathode sheet. Anode sheets manufactured were placed on the cross-section of an anode current collector made of carbon-coated aluminum foil on one side, and an anode layer was manufactured by a heated roll press at 85°C. The total thickness of the anode layer was 120 μm. The thickness of the anode active material layer was 107 μm, and the thickness of the carbon-coated (thickness 1 mm) aluminum foil was 13 μm. The area of ​​the anode active material layer and the anode current collector were the same.

[0140]

[0141] Preparation Example 6: Preparation of an all-solid-state battery

[0142] The anode layer and the second solid electrolyte layer (SEL2) were laminated and pressed using a roll press method. An anode composite layer was prepared by applying a linear pressure of 2.5 ton / cm at 120 ℃.

[0143] A cathode layer and a first solid electrolyte layer (SEL1) were laminated and pressed using a roll press method. A cathode composite layer was prepared by applying a linear pressure of 2.0 ton / cm at 120°C.

[0144] The coating composition of Preparation Example 1 was spray-coated onto the coating layer of the cathode composite layer. The cathode composite layer was placed on a temperature-controlled support plate, and the coating composition was sprayed under a hydrogen atmosphere. After spray coating, the intermediate layer (MDL) was formed by drying at a temperature of 60°C.

[0145] A composite was formed by applying pressure to the cathode composite layer and the anode composite layer, on which an intermediate layer (MDL) was formed, using a roll press method. The pressure was applied at a temperature of 160°C and a linear pressure of 0.5 ton / cm. Thus, the all-solid-state battery included an anode composite layer, a cathode composite layer, and an intermediate layer (MDL) between them. The solid electrolyte layer within the all-solid-state battery included first and second solid electrolyte layers (SEL1, SEL2) and an intermediate layer (MDL) between them. The thickness of the first and second solid electrolyte layers (SEL1, SEL2) was 60 μm each. The intermediate layer (MDL) bonded the first solid electrolyte layer (SEL1) and the second solid electrolyte layer (SEL2) together.

[0146]

[0147] Example 2

[0148] It was prepared in the same manner as in Example 1, except that lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was used instead of lithium bis(trifluoromethanesulfonyl)imide (LiFSI) as the lithium salt.

[0149]

[0150] Example 3

[0151] The coating composition of Preparation Example 1 was prepared in the same manner as Example 1, except that a monoglyme represented by the following structural formula 3 was mixed together with the cyclic polymer and lithium salt.

[0152] [Structural Formula 3]

[0153]

[0154]

[0155] Comparative Example 1

[0156] A symmetric cell that does not include an intermediate layer (MDL) was prepared.

[0157] A symmetric cell and an all-solid-state battery were manufactured in the same manner as in Example 1, except that the coating composition was not coated.

[0158]

[0159] Comparative Example 2

[0160] A symmetric cell and an all-solid-state battery were prepared in the same manner as in Example 1, except that a solution containing a cyclic polymer represented by Structural Formula 1 and a solvent (dichloromethane) was used as the coating composition.

[0161]

[0162] Comparative Example 3

[0163] A symmetric cell and an all-solid-state battery were prepared in the same manner as in Example 1, except that a mixture of lithium bis(trifluoromethanesulfoyl)imide (LiFSI) and a solvent (dichloromethane) was used as the coating composition.

[0164]

[0165] Comparative Example 4

[0166] When preparing the coating composition of Preparation Example 1, a mixture was prepared in which the cyclic polymer represented by Structural Formula 1 and lithium bis(trifluoromethanesulfoyl)imide (LiFSI) were simply mixed, with the mixture being mixed only to the extent that the solid lithium salt (LiFSI) did not disappear. A symmetric cell and an all-solid-state battery were prepared in the same manner as in Example 1, except that the above mixture was used as the coating composition.

[0167]

[0168] Comparative Example 5

[0169] A symmetric cell and an all-solid-state battery were prepared in the same manner as in Example 1, except that a monoglyme represented by structural formula 3 was used instead of a cyclic polymer when preparing the coating composition of Preparation Example 1.

[0170]

[0171] Experimental Example 1: Analysis of the Intermediate Layer (MDL)

[0172] The intermediate layer (MDL) in the all-solid-state battery according to Example 1 was a soft, off-white film. The intermediate layer (MDL) had adhesive properties and bonded the first solid electrolyte layer and the second solid electrolyte layer together.

[0173] A cyclic polymer, lithium bis(trifluoromethanesulfoyl)imide (LiFSI), the composite of Preparation Example 1, and a simple mixture of a cyclic polymer and lithium bis(trifluoromethanesulfoyl)imide (LiFSI) according to Comparative Example 4 were analyzed by infrared (IR) spectral analysis and nuclear magnetic resonance (NMR) spectral analysis. The composite showed different results from the cyclic polymer and lithium salt, and also different results from the simple mixture according to Comparative Example 4.

[0174] Specifically, in the infrared spectrum of the complex, 568 cm⁻¹, which did not appear in the infrared spectrum of the cyclic polymer. -1 A maximum peak was observed at 558 cm⁻¹, which appears in the infrared spectrum for the complex and the infrared spectrum for the lithium salt. -1 The maximum peak at is 568 cm -1 It moved to. Thus, it was confirmed that the oxygen atom (O) and sulfur atom (S) of the cyclic polymer within the complex each formed a coordination bond with a lithium cation.

[0175] In the nuclear magnetic resonance spectrum of the complex, the maximum peak at 1.68 ppm, which appears in the lithium element nuclear magnetic resonance spectrum for the lithium salt (LiFSI), shifted to 1.70 ppm. This confirmed that the oxygen atoms (O) and sulfur atoms (S) of the cyclic polymer within the complex formed coordination bonds with lithium cations, respectively. Consequently, the lithium cations (Li of the lithium salt (LiFSI) within the complex + ) and anion ((FSO2)2N - The ionic bonding between ) is the lithium cation (Li of the lithium salt (LiFSI) not bonded to the cyclic polymer. + ) and anion ((FSO2)2N - It was confirmed that it is weaker than the ionic bond between ).

[0176] Thus, it was confirmed that the composite of Preparation Example 1 is in a form in which a cyclic polymer chelates the lithium cation of a lithium salt (LiFSI) through oxygen atoms (O) and sulfur atoms (S).

[0177]

[0178] Experimental Example 2: Performance Analysis of All-Solid State Batteries

[0179] The resistance of a symmetric cell containing an intermediate layer (MDL) according to the examples and comparative examples was measured using an impedance analyzer (Solartron 1260A Impedance / Gain-Phase Analyzer) according to the 2-probe method. The resistance was measured under conditions of a temperature of 25°C, a frequency range of 0.1 Hz to 1 MHz, and a voltage bias of 10 mV.

[0180] The ionic conductivity of the all-solid-state battery according to the examples and comparative examples was evaluated at 25°C. The ionic conductivity was measured using a symmetric cell according to the examples and comparative examples. The ionic conductivity was calculated by substituting the resistance value obtained from the arc of the Nyquist plot according to the impedance analysis into the following equation.

[0181] [ceremony]

[0182] Ionic conductivity (σ) = I / (R A) (I: thickness of solid electrolyte layer, R: resistance, A: electrode area)

[0183] The results are shown in Table 1.

[0184]

[0185] Distinction Resistance (Ω) Ionic Conductivity (mS / cm) Example 1 16.40.364 Example 2 21.40.279 Example 3 39.60.151 Comparative Example 1 50.50.009 Comparative Example 2 86.30.069 Comparative Example 5 49.80.011

[0186]

[0187] Referring to Table 1, the symmetric cells according to Examples 1 to 3 had lower resistance and higher ion conductivity than the symmetric cells according to Comparative Examples 1, 2, and 5.

[0188] Specifically, the symmetric cells according to Examples 1 to 3 had higher ionic conductivity and lower resistance than Comparative Example 2, which did not contain any lithium salt. In Comparative Examples 3 and 4, the lithium salt was hardly soluble in the solvent, so it could not be coated on the cathode composite layer, and resistance and ionic conductivity could not be measured. Thus, the symmetric cells according to Examples 1 to 3 include a composite, and the cyclic polymer within the composite chelates the lithium cations of the lithium salt, thereby [relating] the lithium cations (Li FSI) of the lithium salt + ) and anion ((FSO2)2N - It was confirmed that by weakening the ionic bond between ) it is possible to provide lithium cations from lithium salts and facilitate the movement of lithium cations.

[0189] The symmetric cells according to Examples 1 to 3 had higher ionic conductivity and lower resistance than Comparative Example 5. The composites within the symmetric cells according to Examples 1 to 3 include not only coordination bonds between oxygen atoms (O) and lithium cations, but also coordination bonds between sulfur atoms (S) and lithium cations, thereby including the lithium cations (Li) of the lithium salt (LiFSI). +) and anion ((FSO2)2N - While weakening the ionic bond between ), lithium cations (Li + By preventing ) from binding too strongly within the complex, lithium cations (Li) from the lithium salt (LiFSI) + It was confirmed that it can provide ) and that lithium cations can move easily.

[0190] That is, in the symmetric cell according to Examples 1 to 3, the complex is a lithium cation (Li + It can provide ) and lithium cations (Li + It was confirmed that by facilitating the movement of ), it is possible to provide an all-solid-state battery with low resistance and high ion conductivity.

[0191] In addition, it was confirmed that in the symmetric cell according to Examples 1 to 3, the intermediate layer (MDL) can reduce the interfacial resistance in the solid electrolyte layer and the all-solid-state battery and increase the ion conductivity by bonding the first solid electrolyte layer and the second solid electrolyte layer together and reducing the voids within the interface.

[0192]

[0193] Although embodiments of the present invention have been described above with reference to the attached drawings, the present invention may be implemented in other specific forms without altering its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

First solid electrolyte layer; A second solid electrolyte layer; and It includes an intermediate layer between the first solid electrolyte layer and the second solid electrolyte layer, The above intermediate layer comprises a composite derived from a mixture of a cyclic polymer represented by the following structural formula 1 and a lithium salt, Solid electrolyte: [Structural Formula 1] In the above structural formula 1, n is 1 to 1000. In paragraph 1, The above cyclic polymer is configured to chelate the lithium cations of the above lithium salt, Solid electrolyte. In paragraph 1, In the above complex, the oxygen atom (O) and sulfur atom (S) in the cyclic polymer each form a coordinate bond with the lithium cation of the lithium salt. Solid electrolyte. In paragraph 1, The above composite comprises a first lithium cation bonded to the cyclic polymer and a second lithium cation not bonded to the cyclic polymer, and The ionic bond between the anion of the lithium salt and the first lithium cation is weaker than the ionic bond between the anion of the lithium salt and the second lithium cation. Solid electrolyte. In paragraph 3, In the above complex, the coordination bond between the sulfur atom (S) and the lithium cation is weaker than the coordination bond between the oxygen atom (O) and the lithium cation. Solid electrolyte. In paragraph 1, The above composite is derived by mixing the above cyclic polymer and the above lithium salt in a molar ratio of 3:1 to 12:1, Solid electrolyte. In paragraph 1, The viscosity of the above composite at 25°C is 550 cP or higher, Solid electrolyte. In paragraph 1, The above intermediate layer combines the first solid electrolyte layer and the second solid electrolyte layer with each other. Solid electrolyte. In paragraph 1, The thickness of the above intermediate layer is 0.01㎛ to 20㎛, Solid electrolyte. In paragraph 1, The number average molecular weight of the above cyclic polymer is 2,000 to 60,000, Solid electrolyte. In paragraph 1, The viscosity of the above cyclic polymer at 25°C is less than 550 cP, Solid electrolyte. In paragraph 1, The above lithium salts are LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2)(x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBOP), lithium bis(oxalate)borate (LiBOB), or at least one combination thereof, comprising Solid electrolyte. Anode layer comprising an anode current collector and an anode active material layer; A cathode layer comprising a cathode current collector and a coating layer; and It includes a solid electrolyte layer between the anode layer and the cathode layer, wherein The above solid electrolyte layer comprises the solid electrolyte described in claim 1, All-solid-state battery. In Paragraph 13, In the above complex, the cyclic polymer is configured to chelate the lithium cation of the lithium salt, All-solid-state battery. In Paragraph 13, The composite in the solid electrolyte is derived by mixing the cyclic polymer and the lithium salt in a molar ratio of 3:1 to 12:1, All-solid-state battery. In Paragraph 13, The viscosity of the above composite at 25°C is 550 cP or higher, All-solid-state battery. Anode layer comprising an anode current collector and an anode active material layer; A cathode layer comprising a cathode current collector and a coating layer; and It includes a solid electrolyte layer between the anode layer and the cathode layer, wherein At least one of the above positive active material layer or the above coating layer comprises a composite derived from a mixture of a cyclic polymer represented by the following structural formula 1 and a lithium salt, All-solid-state battery: [Structural Formula 1] In the above structural formula 1, n is 1 to 1000. In Paragraph 17, In the above complex, the cyclic polymer is configured to chelate the lithium cation of the lithium salt, All-solid-state battery. In Paragraph 17, The above composite is derived by mixing the above cyclic polymer and the above lithium salt in a molar ratio of 3:1 to 12:1, All-solid-state battery. In Paragraph 17, The viscosity of the above composite at 25°C is 550 cP or higher, All-solid-state battery.

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