Manufacturing method of positive electrode, positive electrode and all-solid-state rechargeable battery

Abstract

A manufacturing method of a positive electrode of an all-solid-state rechargeable battery is provided. The manufacturing method of a positive electrode comprises the steps of: adding a first positive electrode active material and a first solid electrolyte to a solvent and mixing same so as to prepare a pre-dispersion; adding a second positive electrode active material and a second solid electrolyte to the pre-dispersion so as to prepare a positive electrode slurry; and applying the positive electrode slurry onto a current collector.

Description

Method for manufacturing anode, anode and all-solid-state secondary battery

[0001] The present disclosure relates to a method for manufacturing an anode, an anode, and an all-solid-state secondary battery.

[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] Currently commercially available lithium-ion batteries use electrolytes containing flammable organic solvents, so there is a possibility of overheating and fire in the event of a short circuit. In response to this, all-solid-state secondary batteries using solid electrolytes instead of liquid electrolytes are being proposed.

[0004] All-solid-state secondary batteries can significantly reduce the likelihood of fire or explosion in the event of a short circuit by not using flammable organic solvents. Therefore, these all-solid-state batteries can offer significantly higher safety compared to lithium-ion batteries that use liquid electrolytes.

[0005] The information described above, disclosed in the background technology of this invention, is intended only to enhance understanding of the background of this disclosure and may therefore include information that does not constitute prior art.

[0006] One embodiment provides a method for manufacturing a positive electrode that minimizes the aggregation of the solid electrolyte and uniformly forms an interface between the positive electrode active material and the solid electrolyte.

[0007] In one embodiment, a method for manufacturing a positive electrode is provided, comprising the steps of: introducing a first positive electrode active material and a first solid electrolyte into a solvent and mixing them to produce a pre-dispersed solution; introducing a second positive electrode active material and a second solid electrolyte into the pre-dispersed solution to produce a positive electrode slurry; and applying the positive electrode slurry onto a current collector to produce a positive electrode.

[0008] According to one embodiment, the positive active material and the solid electrolyte of the all-solid-state secondary battery can be uniformly dispersed and mixed to form a good interface, and accordingly, the positive and all-solid-state secondary battery according to one embodiment can achieve high ionic conductivity and electrical conductivity.

[0009] FIGS. 1 and FIGS. 2 are cross-sectional views schematically illustrating an all-solid-state secondary battery according to one embodiment.

[0010] Specific embodiments are described below in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0011] The terms used herein are for describing exemplary embodiments only and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0012] Here, "combinations of these" refers to mixtures of components, laminates, composites, copolymers, alloys, blends, reaction products, etc.

[0013] The terms "include," "equip," or "have" used herein are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0014] In the drawings, thicknesses have been enlarged to clearly represent various layers and regions, and the same reference numerals have been used for similar parts throughout the specification. When a part such as a layer, film, region, or plate is described as being "on" or "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between. Conversely, when a part is described as being "immediately on" another part, it means that there is no other part in between.

[0015] In addition, the term “layer” here includes not only shapes formed on the entire surface when viewed in a plan view, but also shapes formed on some surfaces.

[0016] The average particle size can be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by using transmission electron microscope or scanning electron microscope images. Alternatively, the average particle size value can be obtained by measuring using dynamic light scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this. Unless otherwise defined, the average particle size is the diameter (D) of the particle at which the cumulative volume in the particle size distribution is 50 volume percent. 50 It may mean ). In addition, unless otherwise defined, the average particle size is obtained by measuring the size (diameter or length of the major axis) of approximately 20 randomly selected particles from scanning electron microscope images to obtain a particle size distribution, and the diameter (D) of the particle with a cumulative volume of 50% in the said particle size distribution. 50 It may be that ) was taken as the average particle size.

[0017] Here, “or” is not interpreted in an exclusive sense; for example, “A or B” is interpreted to include A, B, A+B, etc.

[0018] The term “metal” is interpreted as a concept that includes ordinary metals, transition metals, and metalloids (semimetals).

[0019] anode

[0020] The positive electrode comprises a positive current collector and a positive active material layer located on the positive current collector, wherein the positive active material layer comprises a positive active material and a solid electrolyte, and may optionally include a binder and / or a conductive material. However, not limited thereto, the positive electrode for the all-solid-state secondary battery may include more or fewer components than the components described above.

[0021] A positive electrode according to one embodiment comprises a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector, the layer comprising a positive electrode active material, a solid electrolyte, a conductive material, and a binder. The electrical conductivity of the positive electrode is 0.1 to 1 mS / cm, and the ionic conductivity is 0.05 to 0.1 mS / cm. Specifically, the electrical conductivity of the positive electrode may be 0.1 to 1 mS / cm, 0.4 to 1 mS / cm, or 0.6 to 1 mS / cm. When satisfying the above electrical conductivity range, excellent capacity characteristics and lifespan characteristics can be realized while exhibiting low resistance. The ionic conductivity of the positive electrode may be 0.05 to 0.1 mS / cm, 0.05 to 0.09 mS / cm, or 0.06 to 0.09 mS / cm. When satisfying the above range, the movement of lithium ions in the positive electrode is smooth, thereby enabling excellent capacity characteristics, output characteristics, and lifespan characteristics.

[0022] According to one embodiment, the anode may comprise, with respect to 100 weight% of the anode active material layer, 55 weight% to 99.3 weight% of the anode active material, 0.5 weight% to 35 weight% of the solid electrolyte, 0.1 weight% to 5 weight% of the binder, and 0.1 weight% to 5 weight% of the conductive material.

[0023] Specifically, with respect to 100 wt% of the positive active material layer, the positive active material may be 55 wt% to 99.3 wt%, 60 wt% to 90 wt%, or 80 wt% to 90 wt%, and the solid electrolyte may be 0.5 wt% to 35 wt%, 5 wt% to 30 wt%, or 10 wt% to 20 wt%. The binder may be included in an amount of 0.1 wt% to 5 wt% or 0.1 wt% to 3 wt%, and the conductive material may be included in an amount of 0.1 wt% to 5 wt% or 0.1 wt% to 3 wt%. When the above ranges are satisfied, the positive active material and the solid electrolyte can be uniformly dispersed, and electrical conductivity and ionic conductivity can be maximized.

[0024] Method for manufacturing an anode

[0025] In one embodiment, the positive electrode for the all-solid-state secondary battery is manufactured as follows.

[0026] The above method for manufacturing the anode

[0027] (i) a step of preparing a pre-dispersed solution by introducing a first positive active material and a first solid electrolyte into a solvent and mixing them;

[0028] (ii) a step of preparing an anode slurry by adding a second anode active material and a second solid electrolyte to the above pre-dispersed liquid; and

[0029] (iii) The step of manufacturing an anode by applying the anode slurry above onto a current collector.

[0030] A method for manufacturing a positive electrode according to one embodiment can be described as a method for manufacturing a positive electrode for a lithium secondary battery, and, for example, as a method for manufacturing an all-solid-state secondary battery.

[0031] A method for manufacturing a positive electrode according to one embodiment involves preparing a pre-dispersed solution by wet-mixing a positive electrode active material and a solid electrolyte, and then adding additional positive electrode active material and a solid electrolyte to prepare a solid (or near-solid) positive electrode composition, which is then coated onto a current collector. It is a method combining wet and dry processes, and can be described as a complex method in which a wet slurry is prepared first, followed by a dry process.

[0032] Generally, since solid electrolytes have lower ionic conductivity compared to liquid electrolytes, a composite electrode is manufactured by mixing a positive electrode active material and a solid electrolyte when manufacturing a positive electrode for an all-solid-state secondary battery. However, the solid electrolyte is difficult to disperse evenly within the positive electrode and tends to clump together. Consequently, localized areas with significantly reduced ionic or electrical conductivity occur, which becomes a factor that degrades the capacity and lifespan characteristics of the battery. However, according to the positive electrode manufacturing method of one embodiment, the clumping of the solid electrolyte within the positive electrode is minimized, thereby suppressing the formation of inactive regions where ionic or electrical conductivity is significantly reduced, and improving the ionic and electrical conductivity of the positive electrode. Accordingly, the initial charge / discharge capacity, initial charge / discharge efficiency, and lifespan characteristics of the all-solid-state secondary battery can be improved.

[0033] The anode manufactured according to the method of one embodiment can exhibit higher ionic conductivity and electrical conductivity compared to an anode manufactured only by the dry method without the preparation of a pre-dispersion solution. Furthermore, compared to the case where an anode is manufactured by a method in which, contrary to one embodiment, a mixed powder is prepared by mixing an anode active material and a solid electrolyte by the dry method, a dispersion solution in which the anode active material and the solid electrolyte are mixed in a solvent is added to prepare an anode composition, and then coated onto a current collector, the anode of one embodiment can achieve even superior ionic conductivity and electrical conductivity. Conventionally, an anode for an all-solid-state battery was manufactured by preparing an anode slurry only by the wet method, coating it onto a current collector, and then drying and rolling it; however, according to this method, degradation of the solid electrolyte occurs during the solvent drying step, which leads to a problem where the ionic conductivity and electrical conductivity of the anode decrease. According to the manufacturing method of one embodiment, an anode can be manufactured that achieves improved ionic conductivity and electrical conductivity compared to an anode manufactured by the conventional wet method.

[0034] In step (i) above, a pre-dispersed solution can be prepared by adding the first positive active material and the first solid electrolyte to a solvent and mixing them. This step can be described as a type of wet process. Through step (i), the first positive active material and the first solid electrolyte can be evenly mixed to form a good interface. For example, through step (i), the first solid electrolyte particles can be coated or attached to the surface of the first positive active material particles, and accordingly, the first solid electrolyte can be evenly dispersed within the positive electrode without clumping together.

[0035] In the above pre-dispersed solution, with respect to a total of 100 weight% of the first positive active material and the first solid electrolyte, the first positive active material may be included in an amount of 65 weight% to 99 weight%, for example, 85 weight% to 99 weight%, and the first solid electrolyte may be included in an amount of 1 weight% to 35 weight%, for example, 1 weight% to 15 weight%.

[0036] The solid content in the pre-dispersion may be 40% to 70% by weight with respect to the total weight of the pre-dispersion, for example, 45% to 65% by weight, or 50% to 60% by weight. When the solid content of the pre-dispersion satisfies the above range, the first positive active material and the first solid electrolyte can be evenly mixed and a good interface can be formed between the first positive active material and the first solid electrolyte, and, for example, the first solid electrolyte particles can be well coated on the surface of the first positive active material particles.

[0037] At this time, the first positive electrode active material may be included in an amount of 1% to 99% by weight, for example, 10% to 90% by weight, 20% to 70% by weight, or 30% to 50% by weight, based on a total of 100% by weight of the first positive electrode active material and the second positive electrode active material to be described later. Additionally, the first solid electrolyte may be included in an amount of 1% to 99% by weight, for example, 10% to 90% by weight, 20% to 70% by weight, or 30% to 50% by weight, based on a total of 100% by weight of the first solid electrolyte and the second solid electrolyte to be described later. When the above ranges are satisfied, the positive electrode active material and the solid electrolyte can be well mixed and evenly dispersed within the positive electrode, and the ionic conductivity and electrical conductivity of the positive electrode can be maximized.

[0038] In the pre-dispersion, the solvent may include oxaloacetate, isobutyryl isobutyrate, xylene, toluene, benzene, hexane, alkyl acetate, alkyl propionate, or a combination thereof, and any other solvent that does not react with the solid electrolyte may be used without limitation. Here, the alkyl may be an alkyl having 1 to 10 carbon atoms.

[0039] At this time, a binder may be added to the pre-dispersion liquid. (i) The content of the binder added in step may be 0% to 50% by weight relative to 100% by weight of the total binder in the final anode slurry, and may be included in an amount of, for example, 20% to 40% by weight.

[0040] In addition, a dispersant may be added to the pre-dispersion solution to increase the dispersion power of the solid electrolyte. Hydrogenated nitrile butadiene rubber (HNBR) may be used as the dispersant.

[0041] When mixing in the preparation of pre-dispersion, a shaker, paint shaker, Thinky mixer, Planetary Dispersion Mixer (PD), High Dispersion Mixer (HD), etc., can be used.

[0042] In step (ii) above, a second positive active material and a second solid electrolyte are additionally added to the pre-dispersed liquid. The second positive active material and the second solid electrolyte are added in powder form. Therefore, through this step, a positive slurry in a solid or near-solid state can be produced. From this step onwards, it can be considered a dry process or a quasi-dry process.

[0043] At this time, the second positive active material may be included in an amount of 1% to 99% by weight, for example, 10% to 90% by weight, 30% to 80% by weight, or 50% to 70% by weight, based on 100% by weight of the total of the first positive active material and the second positive active material. Additionally, the second solid electrolyte may be included in an amount of 1% to 99% by weight, for example, 10% to 90% by weight, 30% to 80% by weight, or 50% to 70% by weight, based on 100% by weight of the total of the first solid electrolyte and the second solid electrolyte. When the above ratios are satisfied, the positive active material and the solid electrolyte within the positive electrode can be uniformly mixed, and the ionic conductivity and electrical conductivity of the positive electrode can be improved. At this time, the content of the solids included in the anode slurry may be 90% to 98% by weight with respect to 100% by weight of the total anode slurry, for example, 91% to 95% by weight. When the above range is satisfied, the solid electrolyte and the anode active material can be evenly dispersed within the anode slurry.

[0044] After step (ii) above, the method may further include a step of adding a binder and / or a conductive material to the anode slurry. In this case, the binder may be the remaining amount excluding the binder added in step (i), and may be included in an amount of 50% to 100% by weight, or 60% to 80% by weight, relative to 100% by weight of the total binder in the final anode slurry. In this case, after adding the binder, the solid content relative to the total weight of the anode slurry may be 90% to 95% by weight. Additionally, the conductive material may refer to a pre-dispersed conductive material liquid. The pre-dispersed conductive material liquid may be formed by adding and dispersing a conductive material, which is a carbon-based inorganic material described below, into a solvent. The solvent may be water or an organic solvent, specifically water, N-methylpyrrolidone (NMP), alcohol and isopropanol, oxaloacetate, isobutyryl isobutyrate, xylene, toluene, benzene, hexane, alkyl acetate, alkyl propionate, or a mixture of two or more of these. At this time, the content of solids relative to the total weight of the anode slurry after adding the conductive material pre-dispersion solution may be, for example, 75% to 80% by weight. When the anode slurry in this state is applied to a current collector to form an anode, processability is improved and the anode active material and solid electrolyte within the anode can be uniformly mixed, thereby improving both the ionic conductivity and electrical conductivity of the anode.

[0045] The process of applying the anode slurry to the current collector in step (iii) above may be a vapor phase method or a solid phase method. The vapor phase method may be pulse laser deposition (PLD), sputtering deposition, chemical vapor deposition (CVD), etc., but is not limited to these; any method that can be used in the relevant technical field is possible. The solid phase method may be sintering, sol-gel method, doctor blade method, screen printing method, slurry casting method, powder compression method, etc., but is not necessarily limited to these; any method that can be used in the relevant technical field is possible.

[0046] positive electrode active material

[0047] The above positive active material includes a first positive active material and a second positive active material. The first positive active material and the second positive active material may be identical or different from each other.

[0048] At this time, the positive electrode active material may be applied without limitation as long as it is a material commonly used in all-solid-state secondary batteries. For example, the positive electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium, and may include a compound represented by any one of the following chemical formulas.

[0049] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5);

[0050] Li a A 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0051] Li a E 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0052] Li a HAVE BEEN 2-b X b O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0053] Li a Ni 1-b-c Co b X c D α (0.90 ≤ a ≤1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 <α ≤ 2);

[0054] Li a Ni 1-b-c Co b X c O 2-α T α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0055] Li a Ni 1-b-c Co b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0056] Li a Ni 1-b-c Mr b X c D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2);

[0057] Li a Ni 1-b-c Mr b X c O 2-α T α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0058] Li a Ni 1-b-c Mr bX c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α < 2);

[0059] The a Nor b E c G d O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1);

[0060] The a Nor b Co c Mn d G e O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤0.5, 0.001 ≤ e ≤ 0.1);

[0061] The a NiG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0062] The a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0063] The a Mn 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0064] The a Mn2G b O4(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0065] The a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5);

[0066] QO2; QS2; LiQS2;

[0067] V2O5; LiV2O5;

[0068] LiZO2;

[0069] LiNiVO4;

[0070] Li (3-f) J2(PO4)3(0 ≤ f ≤ 2);

[0071] Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2);

[0072] Li a FePO4(0.90 ≤ a ≤ 1.8).

[0073] In the above chemical formulas, A is selected from the group consisting of Ni, Co, Mn, and combinations thereof; X is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is selected from the group consisting of O, F, S, P, and combinations thereof; E is selected from the group consisting of Co, Mn, and combinations thereof; T is selected from the group consisting of F, S, P, and combinations thereof; G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; Q is selected from the group consisting of Ti, Mo, Mn, and combinations thereof; Z is selected from the group consisting of Cr, V, Fe, Sc, Y, and combinations thereof; and J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof.

[0074] The above-mentioned positive electrode active material may be, for example, a lithium cobalt-based composite oxide, a lithium nickel-based composite oxide, a lithium nickel-cobalt-aluminum-based composite oxide, a lithium nickel-cobalt-manganese-based composite oxide, a lithium nickel-manganese-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based compound, or a combination thereof.

[0075] The above-mentioned positive active material may include, for example, a lithium nickel-based composite oxide represented by the following chemical formula 11, a lithium cobalt-based composite oxide represented by the following chemical formula 12, a lithium iron phosphate-based compound represented by the following chemical formula 13, a cobalt-free lithium nickel-manganese-based composite oxide represented by the following chemical formula 14, or a combination thereof.

[0076] [Chemical Formula 11]

[0077] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0078] In the above chemical formula 11, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, 0≤z1≤0.7, 0.9≤x1+y1+z1≤1.1, and 0≤b1≤0.1, and M 1 and M 2 is different from each other and is independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from the group consisting of F, P and S.

[0079] In the above chemical formula 1, 0.6≤x1≤1, 0≤y1≤0.4, and 0≤z1≤0.4, or 0.8≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.2.

[0080] [Chemical Formula 12]

[0081] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0082] In the above chemical formula 12, 0.9≤a2≤1.8, 0.7≤x2≤1, 0≤y2≤0.3, 0.9≤x2+y2≤1.1, and 0≤b2≤0.1, and M 3 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

[0083] [Chemical Formula 13]

[0084] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0085] In the above chemical formula 13, 0.9≤a3≤1.8, 0.6≤x3≤1, 0≤y3≤0.4, and 0≤b3≤0.1, and M 4 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

[0086] [Chemical Formula 14]

[0087] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0088] In the above chemical formula 14, 0.9≤a2≤1.8, 0.8≤x4<1, 0 <y4≤0.2, 0≤z4≤0.2, 0.9≤x4+y4+z4≤1.1, 및 0≤b4≤0.1이고 M 5is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from the group consisting of F, P and S.

[0089] The above positive active material is in the form of particles and has an average particle size (D 50 ) may be 0.05 μm to 25 μm, and for example, may be 3 μm to 25 μm, 1 μm to 20 μm, 1 μm to 18 μm, 3 μm to 15 μm, or 5 μm to 15 μm. As an example, the anode active material has an average particle size (D 50 Fine particles with a diameter of 1 μm to 8 μm and an average particle size (D 50 ) may include alleles ranging from 9 μm to 25 μm.

[0090] The above positive active material comprises allotropic particles and microparticles, and with respect to the total sum of allotropic particles and microparticles of 100 weight%, the allotropic particles may be included in an amount of 20 weight% to 95 weight% and the microparticles may be included in an amount of 5 weight% to 80 weight%.

[0091] Anode active materials having such a particle size range can be harmoniously mixed with other components within the anode active material layer and can realize high capacity and high energy density. Here, the average particle size is determined by selecting approximately 20 arbitrary particles from scanning electron microscope images of the anode active material, measuring their particle sizes (diameter, major axis, or length of the major axis) to obtain a particle size distribution, and then determining the diameter (D) of the particle with a cumulative volume of 50 volume% in the particle size distribution. 50 It may be that ) was taken as the average particle size.

[0092] The above positive active material may be in the form of secondary particles formed by the aggregation of a plurality of primary particles, or in the form of single particles. In addition, the above positive active material may be spherical or have a shape close to spherical, or may be polyhedral or irregular in shape.

[0093] The cathode active material included in the cathode for an all-solid-state secondary battery may further include a buffer layer on the surface of particles containing a lithium transition metal complex oxide. The buffer layer may be described as a coating layer or a protective layer. The buffer layer can enhance the structural stability of the cathode active material, suppress side reactions between the cathode active material and the sulfide-based solid electrolyte, lower resistance, and prevent the degradation of the sulfide-based solid electrolyte caused by the cathode active material. The buffer layer may include, for example, lithium-metal oxide, lithium-metal phosphate, etc., wherein the metal may be one or more elements selected from the group consisting of Al, B, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ta, V, W, and Zr.

[0094] The content of the buffer layer may be 0.01 wt% to 10 wt% with respect to 100 wt% of the positive active material, and, for example, 0.1 wt% to 2 wt%, or 0.5 wt% to 1.5 wt%.

[0095] As an example, the buffer layer of the positive electrode active material may include lithium-boron oxide, e.g., LiBO-2, Li3B7O 12 , Li6B4O9, Li3B 11 O 18 It may include Li2B4O7, Li3BO3, or a combination thereof. Since lithium-boron oxide has high thermal stability, it can improve the thermal stability of the all-solid-state secondary battery. As another example, the buffer layer of the positive electrode active material may include lithium-zirconium oxide, in which case the output characteristics and lifespan characteristics of the all-solid-state secondary battery can be improved.

[0096] solid electrolyte

[0097] The above solid electrolyte includes a first solid electrolyte and a second solid electrolyte. The first solid electrolyte and the second solid electrolyte may be the same or different from each other.

[0098] The above solid electrolyte may be an inorganic solid electrolyte, such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte, or a solid polymer electrolyte.

[0099] Sulfide-based solid electrolytes are, for example, Li2S-P2S5, Li2S-P2S5--LiX (where X is a halogen element, e.g., I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are integers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are integers, and M is P, Si, Ge, B, Al, Ga or In), or may include a combination thereof.

[0100] Such sulfide-based solid electrolytes can be obtained, for example, by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10 or 50:50 to 80:20 and optionally heat-treating. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be manufactured. Additionally, ionic conductivity may be further improved by including other components such as SiS2, GeS2, B2S3, etc.

[0101] Mechanical milling or the solution method can be applied as mixing methods for sulfur-containing raw materials to manufacture sulfide-based solid electrolytes. Mechanical milling is a method in which starting materials are placed in a reactor and vigorously stirred with a ball mill or similar device to finely pulverize and mix the starting materials. When using the solution method, starting materials are mixed in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, if heat treatment is performed after mixing, the crystals of the solid electrolyte can become more robust and the ionic conductivity can be improved. For example, a sulfide-based solid electrolyte can be manufactured by mixing sulfur-containing raw materials and heat-treating them two or more times; in this case, a robust sulfide-based solid electrolyte with high ionic conductivity can be produced.

[0102] For example, the sulfide-based solid electrolyte may include an argyrodite-type sulfide. The argyrodite-type sulfide is, for example, Li a M b P c S d A e It can be expressed by the chemical formula (where a, b, c, d, and e are all between 0 and 12, M is Ge, Sn, Si, or a combination thereof, and A is F, Cl, Br, or I), and as a specific example, Li 7-x PS 6-x A x It can be expressed by the chemical formula (where x is 0.2 or greater and 1.8 or less, and A is F, Cl, Br, or I). Specifically, the azirodite-type sulfide is Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0103] Sulfide-based solid electrolyte particles containing such azirodite-type sulfides have an ionic conductivity of 10 at room temperature, which is the ionic conductivity of a typical liquid electrolyte.-4 to 10 -2 It has high ionic conductivity close to the S / cm range and can form a tight bond between the positive active material and the solid electrolyte without causing a decrease in ionic conductivity, and furthermore, can form a tight interface between the electrode layer and the solid electrolyte layer. An all-solid-state battery including this can improve battery performance such as rate characteristics, Coulomb efficiency, and lifespan characteristics.

[0104] An azirodite-type sulfide-based solid electrolyte can be prepared by mixing, for example, lithium sulfide and phosphorus sulfide, and optionally lithium halide. After mixing these, heat treatment may be performed. The heat treatment may include, for example, two or more heat treatment steps.

[0105] Average particle size (D of sulfide-based solid electrolyte particles according to one embodiment) 50 ) may be 5.0 μm or less, for example, 0.1 μm to 5.0 μm, 0.1 μm to 4.0 μm, 0.1 μm to 3.0 μm, 0.5 μm to 2.0 μm, or 0.1 μm to 1.5 μm. Alternatively, depending on the location or purpose of use, the sulfide-based solid electrolyte particles may have an average particle size (D) of 0.1 μm to 1.0 μm. 50 It may be a small particle having ), or an average particle size (D) of 1.5 μm to 5.0 μm. 50 It may also be a large particle having ). Sulfide-based solid electrolyte particles within this particle size range can effectively penetrate between solid particles within the battery, and exhibit excellent contact with the electrode active material and connectivity between solid electrolyte particles. The average particle size of the sulfide-based solid electrolyte particles may be measured using microscopic images; for example, a particle size distribution is obtained by measuring the size of approximately 20 particles from a scanning electron microscope image, where D 50 It could be that it was calculated.

[0106] The above oxide-based inorganic solid electrolyte is, for example, Li1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Lithium Phosphate (Li3PO4), Lithium Titanium Phosphate (Li x Ti y (PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate(Li x La y TiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O · 11Al2O3, Na2O · 11Al2O3, (Na,Li) 1+x Ti 2-x Al x (PO4)3(0.1≤x≤0.9), Li 1+x Hf 2-x Al x (PO4)3(0.1≤x≤0.9), Na3Zr2Si2PO 12 , Li3Zr2Si2PO 12 , Na5ZrP3O 12 , Na5TiP3O 12 , Na3Fe2P3O 12 , Na4NbP3O 12, Na-silicate, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2-based ceramics, Garnet-based ceramics Li 3+x La3M2O 12 (M= Te, Nb, or Zr; x is an integer from 1 to 10), Li 0.3 La 0.5 TiO3, Na5MSi4O 12 (M is a rare earth element such as Nd, Gd, or Dy) Li5ZrP3O 12 , Li5TiP3O 12 , Li3Fe2P3O 12 , Li4NbP3O 12 , Li 1+x (M,Al,Ga) x (Ge 1-y Ti y ) 2-x (PO4)3(x≤0.8, 0≤y≤1.0, M is Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), Li 1+x+y Q x Ti 2-x Si y P 3-y O 12 (0 <x≤0.4, 0<y≤0.6, Q는 Al 또는 Ga), Li6BaLa2Ta2O 12 , Li7La3Zr2O 12 , Li5La3Nb2O 12 , Li5La3M2O 12 (M is Nb, Ta) and Li 7+x A x La 3-x Zr2O 12 (0 <x<3, A는 Zn) 또는 이들의 조합을 포함할 수 있다.

[0107] The above halide-based solid electrolyte may include a Li element, an M element (M is a metal other than Li), and an X element (X is a halogen). Examples of X include F, Cl, Br, and I. In particular, for the halide-based solid electrolyte, at least one of Br and Cl is suitable as X. Additionally, examples of M include metal elements such as Sc, Y, B, Al, Ga, and In.

[0108] The composition of the above halide-based solid electrolyte is not particularly limited, but Li 6-3a M a Br b Cl c (In the formula, M is a metal other than Li, and 0 <a<2, 0≤b≤6, 0≤c≤6, b+c=6)로 표현될 수 있다. 이때, 상기 a는 0.75 이상일 수 있고, 1 이상일 수 있고, a는, 1.5 이하일 수 있다. 상기 b는 1 이상일 수 있고, 2 이상일 수 있다. 또한, 상기 c는, 3 이상일 수 있고, 4 이상일 수도 있다. 상기 할라이드계 고체 전해질의 구체적인 예로는 Li3YBr6, Li3YCl6또는 Li3YBr2Cl4를 들 수 있다.

[0109] The composition of the above halide-based solid electrolyte is not particularly limited, but Li 6-3a M a Br b Cl c (In the formula, M is a metal other than Li, and 0 <a<2, 0≤b≤6, 0≤c≤6, b+c=6)로 표현될 수 있다. 이때, 상기 a는 0.75 이상일 수 있고, 1 이상일 수 있고, a는, 1.5 이하일 수 있다. 상기 b는 1 이상일 수 있고, 2 이상일 수 있다. 또한, 상기 c는, 3 이상일 수 있고, 4 이상일 수도 있다. 상기 할라이드계 고체 전해질의 구체적인 예로는 Li3YBr6, Li3YCl6또는 Li3YBr2Cl4를 들 수 있다.

[0110] The above solid polymer electrolyte may be, for example, polyethylene oxide, poly(diallyldimethylammonium)trifluoromethanesulfonylimide (poly(diallyldimethylammonium)TFSI), polyethylene, polypropylene, or a combination thereof.

[0111] The above-mentioned inorganic solid electrolytes are Cu3N, Li3N, LiPON, and Li3PO. 4· Li2S · SiS2, Li2S · It may include one or more selected from GeS2 and Ga2S3.

[0112] bookbinder

[0113] The binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Representative examples include polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc., but are not limited thereto.

[0114] Challenge

[0115] The above positive active material layer may further include a conductive material. The conductive material is used to impart conductivity to the electrode and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or a combination thereof.

[0116] The conductive material may be included in an amount of 0.1% to 5% by weight, or 0.1% to 3% by weight, relative to the total weight of each component of the anode for the all-solid-state battery, or relative to the total weight of the anode active material layer. Within the above content range, the conductive material can improve electrical conductivity without degrading battery performance.

[0117] The whole house

[0118] The positive current collector may include, for example, aluminum, stainless steel, nickel, or a combination thereof, and may be in the form of a foil, foam, or porous metal plate. The positive current collector may be, for example, a polymer-metal composite film comprising a polymer film and a metal layer located on one or both sides of the polymer film. The positive current collector may, for example, include a substrate containing metal and a primer layer located on the surface of the substrate and containing a carbon material.

[0119] All-solid-state secondary battery

[0120] In one embodiment, an all-solid-state secondary battery is provided, comprising a positive electrode and a negative electrode manufactured by the method described above, and a solid electrolyte layer located between the positive electrode and the negative electrode. The all-solid-state secondary battery may also be referred to as an all-solid-state battery or an all-solid-state lithium secondary battery.

[0121] FIG. 1 is a cross-sectional view of an all-solid-state secondary battery according to one embodiment. Referring to FIG. 1, the all-solid-state secondary battery (100) may have a structure in which an electrode assembly is stored in a case such as a pouch, wherein the electrode assembly comprises a negative electrode (400) including a negative electrode current collector (401) and a negative electrode active material layer (403), a solid electrolyte layer (300), and a positive electrode (200) including a positive electrode active material layer (203) and a positive electrode current collector (201). The all-solid-state secondary battery (100) may further include an elastic layer (500) on the outer side of at least one of the positive electrode (200) and the negative electrode (400). FIG. 1 shows a single electrode assembly including a negative electrode (400), a solid electrolyte layer (300), and a positive electrode (200), but an all-solid-state battery may be manufactured by stacking two or more electrode assemblies.

[0122] cathode

[0123] A negative electrode for an all-solid-state battery may, for example, include a current collector and a negative electrode active material layer located on the current collector. The negative electrode active material layer may include a negative electrode active material and may further include a binder, a conductive material, and / or a solid electrolyte.

[0124] The above negative electrode active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0125] A material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0126] As the above lithium metal alloy, an alloy of lithium with one or more metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn may be used.

[0127] As a material capable of doping and undoping the above lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used, and the Si-based negative electrode active material may include silicon, a silicon-carbon composite, or SiO₂. x (0 <x≤2), Si-Q 합금(상기 Q는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Si은 아님), 상기 Sn계 음극 활물질로는 Sn, SnO2, Sn-R 합금(상기 R은 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 상기 원소 Q 및 R로는 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, 및 이들의 조합으로 이루어진 군에서 선택되는 것을 사용할 수 있다.

[0128] The silicon-carbon composite may be, for example, a silicon-carbon composite comprising a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof. The amorphous carbon may be pitch carbon, soft carbon, hard carbon, mesophase pitch carbide, calcined coke, carbon fiber, or a combination thereof. In this case, the silicon content may be 10% to 50% by weight of the total weight of the silicon-carbon composite. Additionally, the content of the crystalline carbon may be 10% to 70% by weight of the total weight of the silicon-carbon composite, and the content of the amorphous carbon may be 20% to 40% by weight of the total weight of the silicon-carbon composite. Additionally, the thickness of the amorphous carbon coating layer may be 5nm to 100nm.

[0129] Average particle size (D) of the above silicon particles 50 ) can be 10 nm to 20 µm, for example, 10 nm to 500 nm. The silicon particles may exist in an oxidized form, wherein the atomic content ratio of Si:O within the silicon particles indicating the degree of oxidation may be 99:1 to 33:67. The silicon particles are SiO x It can be a particle, and in this case, SiO x In this case, the range of x can be greater than 0 and less than 2. Here, the average particle size (D 50 ) is measured by a particle size analyzer using laser diffraction and refers to the diameter of a particle with a cumulative volume of 50 volume% in the particle size distribution.

[0130] The above Si-based negative electrode active material or Sn-based negative electrode active material may be used in combination with a carbon-based negative electrode active material. The mixing ratio of the Si-based negative electrode active material or Sn-based negative electrode active material and the carbon-based negative electrode active material may be 1:99 to 90:10 by weight.

[0131] The content of the negative electrode active material in the above negative electrode active material layer may be 95% to 99% by weight with respect to the total weight of the negative electrode active material layer.

[0132] In one embodiment, the negative electrode active material layer further comprises a binder and optionally further comprises a conductive material. The content of the binder in the negative electrode active material layer may be 1% to 5% by weight based on the total weight of the negative electrode active material layer. Additionally, when further comprising a conductive material, the negative electrode active material layer may comprise 90% to 98% by weight of the negative electrode active material, 1% to 5% by weight of the binder, and 1% to 5% by weight of the conductive material.

[0133] The above binder serves to effectively bond the negative electrode active material particles to each other and also to effectively bond the negative electrode active material to the current collector. The above binder may include a water-insoluble binder, a water-soluble binder, or a combination thereof.

[0134] The above-mentioned water-insoluble binder may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer comprising ethylene oxide, an ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0135] Examples of the above water-soluble binders include rubber-based binders or polymer resin binders. The rubber-based binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, and combinations thereof. The polymer resin binder may be selected from polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0136] When a water-soluble binder is used as the above-mentioned cathode binder, a thickener capable of imparting viscosity may be used together, and the thickener may include, for example, a cellulose-based compound. The cellulose-based compound may include carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, alkali metal salts thereof, or combinations thereof. Na, K, or Li may be used as the alkali metal. The content of such a thickener may be 0.1 to 3 parts by weight per 100 parts by weight of the cathode active material.

[0137] The above conductive material is used to impart conductivity to an electrode and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes; metal-based materials in the form of metal powder or metal fibers including copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0138] As the above-mentioned cathode current collector, a material selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof may be used.

[0139] As another example, the negative electrode for the all-solid-state battery may be a precipitation type negative electrode. The precipitation type negative electrode refers to a negative electrode that does not contain a negative electrode active material when assembling the battery, but where lithium metal, etc., is precipitated during charging of the battery and acts as the negative electrode active material.

[0140] FIG. 2 is a schematic cross-sectional view of an all-solid-state secondary battery including a precipitation type negative electrode according to one embodiment. Referring to FIG. 2, the precipitation type negative electrode (400') may include a current collector (401) and a negative electrode coating layer (405) located on the current collector. An all-solid-state battery having such a precipitation type negative electrode (400') is initially charged in a state where no negative electrode active material is present, and during charging, a high-density lithium metal, etc. is precipitated between the current collector (401) and the negative electrode coating layer (405) to form a lithium metal layer (404), which can act as a negative electrode active material. Accordingly, in an all-solid-state battery that has undergone one or more charges, the precipitation type negative electrode (400') may include a current collector (401), a lithium metal layer (404) located on the current collector, and a negative electrode coating layer (405) located on the metal layer. The above lithium metal layer (404) refers to a layer in which lithium metal, etc. is precipitated during the charging process of the battery, and can be referred to as a metal layer or a negative electrode active material layer.

[0141] The above cathode coating layer (405) may include a metal, a carbon material, or a combination thereof that acts as a catalyst.

[0142] The above metal may include, for example, Ag, Al, Au, Bi, Cu, Ge, In, Mg, Ni, Pt, Pd, Si, Sn, Zn, or combinations thereof, and may be composed of one of these or may be composed of several types of alloys. When the above metal exists in the form of particles, its average particle size (D 50 ) can be about 4 μm or less, and for example, 10 nm to 4 μm.

[0143] The carbon material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof. The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon microbeads, or a combination thereof. The amorphous carbon may be, for example, pitch carbon, soft carbon, hard carbon, mesophase pitch carbide, calcined coke, carbon fiber, or a combination thereof.

[0144] When the above-mentioned cathode coating layer (405) includes both the metal and the carbon material, the mixing ratio of the metal and the carbon material may be, for example, a weight ratio of 1:10 to 2:1. In this case, the precipitation of lithium metal can be effectively promoted and the characteristics of the all-solid-state battery can be improved. The above-mentioned cathode coating layer (405) may include, for example, a carbon material supported with a catalyst metal, or may include a mixture of metal particles and carbon material particles.

[0145] The above cathode coating layer (405) may, for example, include the metal and amorphous carbon, and in this case, can effectively promote the precipitation of lithium metal.

[0146] The above cathode coating layer (405) may further include a binder. The binder may be a non-aqueous binder, and as an example, may be an ion-conducting binder.

[0147] The above-mentioned non-aqueous binder may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene oxide, ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, polyacrylate, or a combination thereof.

[0148] The binder may be 1% to 15% by weight with respect to 100% by weight of the entire cathode coating layer. For example, the binder may be 1% to 14% by weight, 1% to 12% by weight, 1% to 10% by weight, 2% to 8%, or 2% to 7% by weight with respect to 100% by weight of the entire cathode coating layer.

[0149] When the above binder is included in the negative electrode coating layer of an all-solid-state battery within the above content range, electrical resistance and adhesion are improved, and the characteristics of the all-solid-state battery (battery capacity and output characteristics) can be improved.

[0150] In addition, the above cathode coating layer (405) may further include common additives such as fillers, dispersants, and ion conductive materials.

[0151] The thickness of the above cathode coating layer (405) may be, for example, 100 nm to 20 μm, or 500 nm to 10 μm, or 1 μm to 5 μm.

[0152] The above-mentioned solid electrolyte may be an inorganic solid electrolyte, such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte, or a solid polymer electrolyte. The specific details of the above-mentioned solid electrolyte are as described above.

[0153] The above-mentioned precipitation type cathode (400') may, for example, further include a thin film on the surface of the current collector, that is, between the current collector and the cathode coating layer. The thin film may include an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and may be composed of one of these or composed of several types of alloys. The thin film can further flatten the precipitation shape of the lithium metal layer (404) and further improve the characteristics of the all-solid-state battery. The thin film may be formed by, for example, vacuum deposition, sputtering, plating, etc. The thickness of the thin film may be, for example, 1 nm to 500 nm.

[0154] solid electrolyte layer

[0155] The solid electrolyte layer (300) may be an inorganic solid electrolyte such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte, or may include a solid polymer electrolyte. The specific details of the solid electrolyte are as described above.

[0156] In one example, the solid electrolyte included in the positive electrode (200) or the negative electrode and the solid electrolyte included in the solid electrolyte layer (300) may include the same compound or different compounds. For example, if both the positive electrode (200) and the solid electrolyte layer (300) include an azirodite-type sulfide-based solid electrolyte, the overall performance of the all-solid-state secondary battery may be improved. In addition, for example, if both the positive electrode (200) and the solid electrolyte layer (300) include the aforementioned coated solid electrolyte, the all-solid-state secondary battery may achieve high capacity and high energy density while achieving excellent initial efficiency and lifespan characteristics.

[0157] Meanwhile, the average particle size (D) of the solid electrolyte included in the anode (200) 50 ) is the average particle size (D) of the solid electrolyte included in the solid electrolyte layer (300).50 It may be smaller than ). In this case, overall performance can be improved by increasing the mobility of lithium ions while maximizing the energy density of the all-solid-state battery. For example, the average particle size (D) of the solid electrolyte included in the cathode (200) 50 ) may be 0.1 μm to 1.0 μm, or 0.1 μm to 0.8 μm, and the average particle size (D) of the solid electrolyte included in the solid electrolyte layer (300) 50 The particle size ) can be 1.5 μm to 5.0 μm, or 2.0 μm to 4.0 μm, or 2.5 μm to 3.5 μm. When such a particle size range is satisfied, the energy density of the all-solid-state secondary battery is maximized, while lithium ion transport is facilitated to suppress resistance, thereby improving the overall performance of the all-solid-state secondary battery. Here, the average particle size (D) of the solid electrolyte 50 ) may be measured using a particle size analyzer utilizing laser diffraction. Alternatively, approximately 20 random particles may be selected from microscopic images such as those of a scanning electron microscope, their particle sizes measured, and their particle size distribution obtained, where D 50 You can also calculate the value.

[0158] The above solid electrolyte layer may further include a binder in addition to the solid electrolyte. In this case, styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, acrylate-based polymers, or combinations thereof may be used as the binder, but are not limited thereto, and any material used as a binder in the relevant technical field may be used. The above acrylate-based polymer may be, for example, butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0159] The above solid electrolyte layer can be formed by adding a solid electrolyte to a binder solution, coating it onto a substrate film, and drying it. The solvent of the binder solution may be isobutyryl isobutylate, xylene, toluene, benzene, hexane, or a combination thereof. Since the process for forming the above solid electrolyte layer is widely known in the field, a detailed description will be omitted.

[0160] The thickness of the solid electrolyte layer may be, for example, 10 μm to 150 μm.

[0161] The above solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0162] The above alkali metal salt may be, for example, a lithium salt. The content of the lithium salt in the above solid electrolyte layer may be 1 M or more, for example, 1 M to 4 M. In this case, the lithium salt can improve ion conductivity by improving the lithium ion mobility of the solid electrolyte layer.

[0163] The above lithium salts are, for example, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI), It may include LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4, or a mixture thereof.

[0164] In addition, the lithium salt may be imide-based, for example, the imide-based lithium salt may include lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2) and lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). The lithium salt can maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with the ionic liquid.

[0165] The above ionic liquid refers to a salt or room temperature molten salt that has a melting point below room temperature, is in a liquid state at room temperature, and consists only of ions.

[0166] The above ionic liquid comprises a) one or more cations selected from ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phosphonium-based, sulfonium-based, triazolium-based, and mixtures thereof, and b) BF4 - , PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - It may be a compound containing one or more anions selected from among.

[0167] The above ionic liquid may be one or more selected from the group consisting of, for example, N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazoliium bis(trifluoromethylsulfonyl)amide, and 1-ethyl-3-methylimidazoliium bis(trifluoromethylsulfonyl)amide.

[0168] The weight ratio of the solid electrolyte to the ionic liquid in the above solid electrolyte layer may be 0.1:99.9 to 90:10, and for example, 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. A solid electrolyte layer satisfying the above range can maintain or improve ionic conductivity by increasing the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate characteristics, etc. of the all-solid-state battery can be improved.

[0169] The above all-solid-state battery may be a unit cell having a structure of a positive electrode / solid electrolyte layer / negative electrode, a bicell having a structure of a negative electrode / solid electrolyte layer / positive electrode / solid electrolyte layer / negative electrode, or a stacked battery in which the structure of the unit cell is repeated.

[0170] The shape of the above-described solid-state battery is not particularly limited and may be, for example, coin-type, button-type, sheet-type, stacked-type, cylindrical-type, flat-type, etc. In addition, the above-described solid-state battery can be applied to large batteries used in electric vehicles, etc. For example, the above-described solid-state battery can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in fields requiring a large amount of power storage, and for example, it can be used in electric bicycles or power tools.

[0171] Examples and comparative examples of the present invention are described below. The following examples are merely illustrative of the present invention, and the present invention is not limited to the following examples.

[0172] Example 1

[0173] 1. Preparation of anode slurry

[0174] Jo Seong-i LiNi 0.945 Co 0.04 Al 0.015 It is O2 and is in the form of secondary particles, with an average particle size (D 50) an allele having a thickness of approximately 13 μm, and a composition of LiNi 0.94 Co 0.04 Al 0.01 Mn 0.01 It is O2 and in single-particle form, with an average particle size (D 50 A first positive active material is prepared by mixing fine particles with a diameter of approximately 4 μm in a weight ratio of 7:3. 2.55 g of the first positive active material, average particle size (D 50 0.4032 g of a azirodite-type first solid electrolyte Li6PS5Cl, with a thickness of approximately 0.85 μm, is added to 6 g of oxaloacetate solvent to prepare a pre-dispersion solution with a solid content of 55 wt%.

[0175] A cathode slurry having a solid content of about 95% by weight was prepared by adding 22.95g of a second cathode active material having the same composition as the first cathode active material and 3.6288g of a second solid electrolyte having the same composition as the first solid electrolyte to the above pre-dispersed liquid.

[0176] With respect to the total of the first positive active material and the second positive active material, the first positive active material is 10% by weight and the second positive active material is 90% by weight. With respect to the total of the first solid electrolyte and the second solid electrolyte, the first solid electrolyte is 10% by weight and the second solid electrolyte is 90% by weight.

[0177] Next, a PVdF binder was added and mixed to prepare an anode slurry with a solid content of about 90 wt%.

[0178] Subsequently, a conductive material pre-dispersion solution containing oxalo acetate solvent and carbon nanotubes was added and mixed to prepare a final anode slurry with a solid content of about 80%.

[0179] With respect to 100 wt% of the solid content in the final anode slurry, the sum of the first anode active material and the second anode active material is about 85 wt%, the sum of the first solid electrolyte and the second solid electrolyte is about 13.44 wt%, the binder is 1 wt%, and the carbon nanotube conductive material is about 0.56 wt%.

[0180] 2. Manufacture of the anode

[0181] The final anode slurry prepared was applied to an aluminum foil current collector and dried, and then an anode was prepared by hydrostatic pressing at a high temperature of 85°C at 500 MPa for 30 minutes.

[0182] 3. Manufacturing of all-solid-state secondary batteries

[0183] A cathode coating layer composition was prepared by mixing an Ag-C composite compound, styrene-butadiene rubber, and sodium carboxymethyl cellulose in a water solvent at a weight ratio of 100:6:3. The prepared cathode coating layer composition was coated onto a stainless steel foil current collector with a thickness of 10 μm, and then vacuum dried at 80°C to produce a precipitation-type cathode with a cathode coating layer 12 μm thick formed on the surface of the current collector.

[0184] D 50 An azirodite-type solid electrolyte of Li6PS5Cl with a thickness of about 3.0 μm was added to an IBIB solvent containing an acrylic binder and mixed to prepare a composition for forming a solid electrolyte layer. The composition was cast onto a release film and dried at room temperature to prepare a solid electrolyte layer.

[0185] The prepared positive electrode, negative electrode, and solid electrolyte layer were cut, and the solid electrolyte layer was laminated onto the positive electrode, and then the negative electrode was laminated on top of it. This was sealed in a pouch form and subjected to hydrostatic pressing at a high temperature of 80°C at 500 MPa for 30 minutes to manufacture an all-solid-state secondary battery.

[0186] Example 2

[0187] A cathode was prepared in substantially the same manner as in Example 1, except that the content of the first cathode active material was changed to 7.65g, the first solid electrolyte to 1.2096g, the content of the second cathode active material to 17.85g, and the content of the second solid electrolyte to 2.8224g.

[0188] Example 3

[0189] A cathode was prepared in substantially the same manner as in Example 1, except that the content of the first cathode active material was changed to 12.75g, the first solid electrolyte to 2.016g, the content of the second cathode active material to 12.75g, and the content of the second solid electrolyte to 2.016g.

[0190] Example 4

[0191] A cathode was prepared in substantially the same manner as in Example 1, except that the content of the first cathode active material was changed to 22.95g, the first solid electrolyte to 3.6288g, the content of the second cathode active material to 2.55g, and the content of the second solid electrolyte to 0.4032g.

[0192] Comparative Example 1

[0193] A positive electrode and an all-solid-state secondary battery were prepared in the same manner as in Example 1, except that 25.5 g of the first positive electrode active material and 2.016 g of the first solid electrolyte, identical to those used in Example 1, were mixed in a dry state, and then a pre-dispersion solution was prepared by mixing 2.016 g of the second solid electrolyte, having the same composition as the first solid electrolyte, and 0.3 g of PVdF binder in an oxalo acetate solvent to prepare a final positive electrode slurry.

[0194] Comparative Example 2

[0195] A mixture with 100% solid content was prepared by dry mixing the same first positive active material and first solid electrolyte used in Example 1, and then a PVdF binder was added and mixed to prepare a composition with approximately 95% solid content, and subsequently, a carbon nanotube conductive material pre-dispersion liquid was added and mixed to prepare a final positive slurry with approximately 80% solid content. The weight ratio of the first positive active material, the first solid electrolyte, the binder, and the conductive material is 85:13.44:1:0.56.

[0196] Evaluation Example 1: Battery performance evaluation according to manufacturing method

[0197] The ionic conductivity of the anodes in Example 1, Comparative Example 1, and Comparative Example 2 was evaluated. Specifically, two anode plates coated with each anode active material were placed in contact and subjected to a Warm Isostatic Press (WIP), after which they were punched into a circular shape with a diameter of 13 mm to form a torque cell. At this time, the bonding pressure was approximately 300 MPa, and the measurement pressure was approximately 30 MPa. Electrochemical Impedance Spectroscopy (EIS) was performed on the manufactured cells. The resistance value was determined from the arc of the Nyquist plot of the impedance measurement results, and the ionic conductivity was calculated considering the area and thickness of the specimen and is indicated in Table 1.

[0198] Ionic Conductivity (S / cm) Example 15.11E-05 Comparative Example 14.48E-05 Comparative Example 24.76E-05

[0199] Referring to Table 1, it can be seen that Comparative Example 1 and Comparative Example 2 have lower ionic conductivity compared to Example 1 because the solid electrolyte is unevenly dispersed.

[0200] Evaluation Example 2: Battery Performance Evaluation According to Content

[0201] The electrical conductivity and ionic conductivity of the cathode active materials of Examples 1 to 4 were evaluated by adjusting the content ratios of the first cathode active material, the second cathode active material, the first solid electrolyte, and the second solid electrolyte. The evaluation method was the same as that described in Evaluation Example 1, and the results are shown in Table 2.

[0202] First active material: Second active material First solid electrolyte: Second solid electrolyte Electrical conductivity (S / cm) Ionic conductivity (S / cm) Example 1 10:90 10:90 7.85 E-045.11 E-05 Example 2 30:70 30:70 6.21 E-046.34 E-05 Example 3 50:50 50:50 6.08 E-046.08 E-05 Example 4 90:10 90:109.27 E-044.96 E-05

[0203] Referring to Table 2, it can be seen that Examples 1 to 4 all exhibit excellent electrical and ionic conductivity. It can be seen that Examples 2 and 3 show higher ionic conductivity because the solid electrolyte is evenly dispersed.

[0204] [Explanation of the symbol]

[0205] 100: All-solid-state battery 200: Cathode

[0206] 201: Positive current collector 203: Positive active material layer

[0207] 300: Solid electrolyte layer 400: Cathode

[0208] 401: Cathode current collector 403: Cathode active material layer

[0209] 400': Precipitation type cathode 404: Lithium metal layer

[0210] 405: Cathode coating layer 500: Elastic layer

Claims

1. (i) A step of preparing a pre-dispersed solution by introducing a first positive active material and a first solid electrolyte into a solvent and mixing them; (ii) a step of preparing an anode slurry by adding a second anode active material and a second solid electrolyte to the above pre-dispersed liquid; and (iii) a step of manufacturing an anode by applying the anode slurry above onto a current collector; A method for manufacturing an anode including 2. In Paragraph 1, In step (i) above, the solid content of the pre-dispersion is 40% to 70% by weight with respect to the total weight of the pre-dispersion, and A method for manufacturing an anode in which, in step (ii) above, the solid content of the anode slurry is 90% to 98% by weight relative to the total weight of the anode slurry.

3. In Paragraph 1, In the above pre-dispersion, A method for manufacturing a cathode in which, with respect to a total of 100 weight% of the first cathode active material and the first solid electrolyte, the first cathode active material is included in an amount of 65 weight% to 99 weight% and the first solid electrolyte is included in an amount of 1 weight% to 35 weight%.

4. In Paragraph 1, In the above pre-dispersion, A method for manufacturing a cathode in which, with respect to a total of 100 weight% of the first cathode active material and the first solid electrolyte, the first cathode active material is included in an amount of 85 weight% to 99 weight% and the first solid electrolyte is included in an amount of 1 weight% to 15 weight%.

5. In Paragraph 1, The first positive active material and the second positive active material are identical or different from each other, and A method for manufacturing an anode comprising, respectively independently, a lithium cobalt-based composite oxide, a lithium nickel-based composite oxide, a lithium nickel-cobalt-based composite oxide, a lithium nickel-cobalt-aluminum-based composite oxide, a lithium nickel-cobalt-manganese-based composite oxide, a lithium nickel-manganese-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based oxide, or a combination thereof.

6. In Paragraph 1, A method for manufacturing a positive electrode in which the first positive electrode active material and the second positive electrode active material are identical or different from each other, and each independently comprises a lithium nickel-based composite oxide represented by the following chemical formula 11: [Chemical Formula 11] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1 In the above chemical formula 11, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, 0≤z1≤0.7, 0.9≤x1+y1+z1≤1.1, and 0≤b1≤0.1, and 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7 and 0≤z≤0.1, and M 1 and M 2 are distinct from each other and are each independently Al, B, Ba, Ca, Ce, Co, Cr, Fe, Mg, Mn, Mo, Nb, Si, Sr, Ti, V, W, Y, Zn, Zr or a combination thereof, and X is F, P, S or a combination thereof.

7. In Paragraph 1, The first positive active material and the second positive active material are each in the form of particles, and the average particle size (D) of the particles 50 ) is a method for manufacturing an anode having a length of 0.05 μm to 25 μm.

8. In Paragraph 1, The first positive active material and the second positive active material are identical or different from each other, and are each independently particles containing a lithium nickel-based composite oxide, with an average particle size (D 50 Large particles with a diameter of 9 µm to 25 µm, average particle size (D 50 A method for manufacturing an anode comprising ) small particles having a size of 1 μm to 8 μm, or a combination thereof.

9. In Paragraph 8, The first positive active material and the second positive active material each independently comprise the allele and the subatomic particle, and With respect to a total of 100 weight% of alloles and subatomic particles, alloles are included in an amount of 60 to 95 weight% and subatomic particles are included in an amount of 5 to 40 weight%, and The above-mentioned opposite is in the form of a secondary particle composed of multiple primary particles, and A method for manufacturing an anode in which the above-mentioned elementary particles are in the form of secondary particles composed of a plurality of primary particles or in the form of single particles.

10. In Paragraph 1, A method for manufacturing an anode in which the first solid electrolyte and the second solid electrolyte are identical or different from each other and each is independently a sulfide-based solid electrolyte.

11. In Paragraph 10, A method for manufacturing an anode in which the first solid electrolyte and the second solid electrolyte are identical or different from each other and each independently comprises an azirodite-type sulfide.

12. In Paragraph 1, The first solid electrolyte and the second solid electrolyte are in the form of particles, and the average particle size (D) of the particles 50 A method for manufacturing an anode, each having a diameter of 0.1 μm to 5 μm independently.

13. In Paragraph 1, A method for manufacturing an anode in step (i) above, wherein the pre-dispersion liquid further comprises a binder.

14. In Paragraph 1, The above method for manufacturing the anode follows step (ii), A method for manufacturing an anode, further comprising the step of adding a binder and / or a conductive material to the anode slurry.

15. In Paragraph 14, The above conductive material is a method for manufacturing an anode, which is a conductive material pre-dispersion liquid prepared by pre-dispersing a carbon-based inorganic material in a solvent.

16. In Paragraph 1, A method for manufacturing an anode, further comprising the steps of: adding a binder to the anode slurry after step (ii) above to produce an anode slurry having a solid content of 90% to 95% by weight relative to the total weight of the anode slurry; and adding a conductive material pre-dispersion liquid to produce an anode slurry having a solid content of 75% to 80% by weight relative to the total weight of the anode slurry.

17. Positive current collector, and A positive electrode comprising a positive active material layer located on the above positive current collector and comprising a positive active material, a solid electrolyte, a conductive material, and a binder, An anode having an electrical conductivity of 0.1 to 1 mS / cm and an ionic conductivity of 0.050 to 0.1 mS / cm.

18. In Paragraph 17, The above-mentioned positive electrode active material comprises a lithium cobalt-based composite oxide, a lithium nickel-based composite oxide, a lithium nickel-cobalt-aluminum-based composite oxide, a lithium nickel-cobalt-manganese-based composite oxide, a lithium nickel-manganese-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based compound, or a combination thereof. The above solid electrolyte is an anode containing an azirodite-type sulfide.

19. In Paragraph 17, With respect to 100 weight% of the above positive active material layer, The above positive active material is 55% by weight to 99.3% by weight. The above solid electrolyte is included in an amount of 0.5 weight% to 35 weight%, and The above binder is included in an amount of 0.1 weight% to 5 weight%, and The above conductive material is included in an amount of 0.1 weight% to 5 weight%.

20. An anode manufactured by the method of any one of claims 1 to 16 or an anode according to any one of claims 17 to 19; cathode; and An all-solid-state secondary battery comprising a solid electrolyte layer located between the anode and the cathode.

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