Anode for all-solid-state battery and all-solid-state battery including the same

Abstract

The present invention relates to an anode for an all-solid-state battery and an all-solid-state battery including the same, the anode for the all-solid-state battery including the same, the anode including a current collector, an ion transport layer, and an anode coating layer positioned between the current collector and the ion transport layer and including first amorphous carbon, a metal, and a first binder, wherein the thickness ratio of the anode coating layer to the ion transport layer is 1:0.1 to 1:0.5.

Description

[Technical Field]

[0001] The present invention relates to a negative electrode for an all-solid-state battery and an all-solid-state battery including the same. [Background technology]

[0002] Recently, with the rapid spread of battery-powered electronic devices such as mobile phones, laptops, and electric vehicles, the demand for small, lightweight, and relatively high-capacity secondary batteries has been growing rapidly. In particular, lithium secondary batteries have attracted attention as a power source for portable devices due to their light weight and high energy density. As a result, research and development efforts to improve the performance of lithium secondary batteries have been actively pursued.

[0003] Among lithium secondary batteries, all-solid-state batteries are batteries that are composed entirely of solid materials, particularly those that use a solid electrolyte. One way to increase the energy density of such all-solid-state batteries is to use lithium metal as the anode. However, this method poses problems due to the volume expansion of lithium and irreversible dendrite growth during charging and discharging.

[0004] To solve these problems, a method of constructing an anode without using lithium metal itself, but by forming a layer on the anode current collector during charging and discharging, is being studied. However, this method is not suitable because it results in low output characteristics and excessive short circuiting. Summary of the Invention [Problem to be solved by the invention]

[0005] One embodiment provides an anode for an all-solid-state battery that exhibits excellent battery chemistry properties.

[0006] Another embodiment provides an all-solid-state battery including the negative electrode. [Means for solving the problem]

[0007] One embodiment provides an anode for an all-solid-state battery, comprising: a current collector; an ion transport layer; and an anode coating layer positioned between the current collector and the ion transport layer, the anode coating layer comprising first amorphous carbon, a metal, and a first binder, wherein the thickness ratio of the anode coating layer to the ion transport layer is 1:0.1 to 1:0.5.

[0008] The thickness ratio of the negative electrode coating layer to the ion transport layer may be 1:0.15 to 1:0.5.

[0009] The ion conduction layer may have a thickness of 0.5 μm to 5 μm.

[0010] The thickness of the negative electrode coating layer may be 5 μm to 50 μm.

[0011] The ion transport layer can include a second amorphous carbon and a second binder.

[0012] The second amorphous carbon is 10 m 2 / g over 100m 2 / g.

[0013] The first amorphous carbon is 50 m 2 / g over 1500m 2 / g.

[0014] The second amorphous carbon may have a specific surface area smaller than the specific surface area of ​​the first amorphous carbon.

[0015] The content of the first binder may be 1 to 15 wt % based on 100 wt % of the total weight of the negative electrode coating layer.

[0016] The content of the second binder may be 5 to 50% by weight based on 100% by weight of the ion transport layer.

[0017] The ion transport layer may have a porosity of between 5% and 50%.

[0018] The negative electrode coating layer may have a porosity of 10% to 30%.

[0019] The metal can be Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd, or a combination thereof.

[0020] The second amorphous carbon may be carbon black, acetylene black, denka black, ketjen black, furnace black, activated carbon, carbon nanofibers, or a combination thereof.

[0021] The second amorphous carbon may be an aggregate having the form of secondary particles formed by aggregation of primary particles.

[0022] Another embodiment provides an all-solid-state battery comprising: the anode; a cathode; and a solid electrolyte layer located between the anode and the cathode.

[0023] The solid electrolyte may be a sulfide-based solid electrolyte. [Effects of the Invention]

[0024] The negative electrode for an all-solid-state battery according to one embodiment can exhibit excellent electrochemical properties. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a schematic diagram illustrating a charge / discharge state of an all-solid-state battery according to an embodiment. FIG. [Figure 2] FIG. 1 is a schematic diagram illustrating a structure of an all-solid-state battery according to an embodiment. [Figure 3] 1 is a 3D optical microscope photograph of a cross section of a negative electrode for an all-solid-state battery prepared according to Example 1. [Figure 4] 1 is a photograph of the all-solid-state battery manufactured in Example 1 after disassembly. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the present invention is given by way of example only and is not intended to limit the scope of the present invention, which is defined solely by the claims.

[0027] The terms used herein are merely used to describe exemplary embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless otherwise clearly indicated in the context.

[0028] As used herein, "combinations thereof" means mixtures, laminates, composites, copolymers, alloys, blends, reaction products, and the like of compositions.

[0029] As used herein, the terms "comprise," "comprise," or "have" are intended to specify the presence of embodied features, numbers, steps, components, or combinations thereof, and should be understood as not precluding the possible presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0030] In the drawings, thicknesses of multiple layers and regions are exaggerated to clearly show them, and similar parts are designated by the same reference numerals throughout the specification. When a layer, film, region, plate, or other part is said to be "on" or "above" another part, this includes not only the case where it is "directly on" the other part, but also the case where there is another part between them. Conversely, when a part is said to be "directly on" another part, it means that there is no other part between them.

[0031] Furthermore, the term "layer" as used herein includes not only shapes formed on the entire surface when observed in a plan view, but also shapes formed on a portion of the surface.

[0032] Herein, "or" is not to be construed in an exclusive sense; for example, "A or B" is to be construed as including A, B, A+B, and so on.

[0033] Unless otherwise defined herein, particle size or size may refer to the average particle size. This average particle size refers to the average particle size (D50), which is the diameter of particles with a cumulative volume of 50% in the particle size distribution. The average particle size (D50) can be measured by methods well known to those skilled in the art, such as using a particle size analyzer, a transmission electron microscope (TEM), or a scanning electron microscope (SEM). Alternatively, measurements can be performed using a dynamic light-scattering measuring device, and data analysis can be performed to count the number of particles in each particle size range, followed by calculation to obtain the average particle size (D50).

[0034] An anode for an all-solid-state battery according to one embodiment includes a current collector; an ion transport layer; and an anode coating layer positioned between the current collector and the ion transport layer.

[0035] In one embodiment, the anode coating layer refers to a layer that facilitates the migration of lithium ions released from the cathode active material to the anode during charge and discharge of an all-solid-state battery and facilitates their deposition on the current collector surface. That is, a lithium deposition layer is formed between the current collector and the anode coating layer due to the deposition of lithium ions, and this lithium deposition layer functions as the anode active material. Such anodes are generally referred to as deposition-type anodes. Such deposition-type anodes refer to anodes that do not contain anode active material during battery assembly, but in which the lithium deposition layer functions as the anode active material.

[0036] In one embodiment, the ion transport layer is located on the surface of the negative electrode and is in contact with the solid electrolyte when the all-solid-state battery is constructed, thereby facilitating the transport of lithium ions to the negative electrode coating layer.

[0037] In one embodiment, the thickness ratio of the anode coating layer to the ion transport layer may be 1:0.1 to 1:0.5, or 1:0.15 to 1:0.5. When the ion transport layer is included in the anode with a thickness thinner than the anode coating layer, and the thickness ratio of the anode coating layer to the ion transport layer is within this range, it is possible to suppress overvoltage, which is an excessive increase in voltage during charge and discharge, and to prevent excessive formation of lithium dendrites on the anode surface. Furthermore, when these dendrites penetrate the electrolyte and contact the cathode, it is possible to prevent problems with reduced lifespan due to short circuits. Furthermore, when the thickness ratio is within this range, it is possible to improve charge and discharge efficiency.

[0038] The thickness of the negative electrode coating layer may be 5 μm to 50 μm, 5 μm to 40 μm, or 5 μm to 30 μm, and the thickness of the ion transport layer may be 0.5 μm to 5 μm, or 1 μm to 5 μm.

[0039] When the thicknesses of the anode coating layer and the ion transport layer are within the above ranges, the effects of including the ion transport layer can be more appropriately achieved.

[0040] The anode coating layer includes a first amorphous carbon, a metal, and a first binder. The ion transport layer includes a second amorphous carbon and a second binder. The ion transport layer does not include a metal. If the ion transport layer includes a metal, volume expansion of the metal may occur, which may damage the anode and electrolyte, resulting in a short circuit.

[0041] The first amorphous carbon may be carbon black, acetylene black, denka black, ketjen black, furnace black, activated carbon, carbon nanofiber, or a combination thereof. An example of the carbon black is Super P (Timcal).

[0042] The second amorphous carbon may be carbon black, acetylene black, denka black, ketjen black, furnace black, activated carbon, carbon nanofiber, or a combination thereof.

[0043] The first amorphous carbon and the second amorphous carbon may be the same or different.

[0044] The first amorphous carbon or the second amorphous carbon may be a single particle or an aggregate of primary particles. When the first amorphous carbon or the second amorphous carbon is a single particle, the first amorphous carbon or the second amorphous carbon may be an amorphous carbon particle having an average particle size of 100 nm or less, for example, a nano-size of 10 nm to 100 nm.

[0045] When the first amorphous carbon is an aggregate, the particle size of the primary particles may be 30 nm to 300 nm, or 35 nm to 100 nm, and the particle size of the secondary particles may be 50 nm to 1000 nm, or 100 nm to 500 nm.

[0046] When the second amorphous carbon is an aggregate, the particle size of the primary particles may be 20 nm to 50 nm, or 20 nm to 35 nm, and the particle size of the secondary particles may be 50 nm to 800 nm, or 80 nm to 300 nm.

[0047] When the particle sizes of the primary particles and secondary particles are within the above ranges, the first and second amorphous carbons do not excessively increase the length of the lithium transport path, and the lithium transport path is not interrupted, so that the lithium transport path can be properly maintained, enabling smooth conduction of lithium ions, and therefore lithium deposition can occur uniformly.

[0048] When the first amorphous carbon and the second amorphous carbon are aggregates, the shape of the primary particles may be spherical, elliptical, plate-like, or a combination thereof, and in one embodiment, the shape of the primary particles may be spherical, elliptical, or a combination thereof.

[0049] In one embodiment, the first amorphous carbon is 50 m 2 / g or more, 1500m 2 / g or less, and 2 / g~500m 2 When the BET specific surface area of ​​the first amorphous carbon is within this range, the negative electrode may have higher interparticle cohesion during fabrication, preventing detachment and providing high stability, and lithium ions may be able to migrate efficiently, thereby reducing overvoltage.

[0050] The second amorphous carbon is 10 m 2 / g or more, 100m 2 / g or less, and 2 / g~60m 2 The second amorphous carbon may have a BET specific surface area of ​​1 / g. When the BET specific surface area of ​​the second amorphous carbon is within this range, the negative electrode may have higher interparticle cohesion during fabrication, preventing detachment and providing high stability, and may be advantageous in that lithium ions can migrate efficiently, thereby reducing overvoltage. In particular, it is preferable that the specific surface area of ​​the second amorphous carbon is smaller than that of the first amorphous carbon. This is because the ion transport layer plays a role in rapidly transporting lithium ions, and the second amorphous carbon's low specific surface area effectively suppresses overvoltage generation.

[0051] In one embodiment, the first binder contained in the negative electrode coating layer and the second binder contained in the ion transport layer may be the same or different. Examples of the first binder and the second binder include styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, or a combination thereof. The carboxymethyl cellulose may be an alkali metal salt thereof, and the alkali metal may be Na or Li. The first and second binders are not limited to these, and any binders commonly used in the art may be used.

[0052] In one embodiment, the metal contained in the negative electrode coating layer may be Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd, or a combination thereof. According to one embodiment, the metal may be Ag. The inclusion of such a metal in the negative electrode coating layer can further improve the conductivity of the negative electrode.

[0053] The metal may be nanoparticles, and the average size of the metal nanoparticles may be, for example, 5 nm to 80 nm. However, nanometer-sized nanoparticles are suitable. The use of nanometer-sized metal nanoparticles can further improve the battery characteristics (e.g., life characteristics) of all-solid-state batteries. Increasing the metal particle size to the micrometer level is not suitable because it can reduce the uniformity of the metal particles in the anode coating layer, increase the current density in a specific region, and reduce cycle life characteristics.

[0054] According to one embodiment, the content of the first binder in the negative electrode coating layer may be 1 wt % to 15 wt %, 3 wt % to 10 wt %, or 5 wt % to 9 wt %, based on 100 wt % of the total weight of the negative electrode coating layer. When the content of the first binder is within this range, it may be advantageous in improving adhesion between active materials without increasing the sound plate resistance.

[0055] The content of the second binder in the ion transport layer may be 5 to 50 wt %, 8 to 30 wt %, or 10 to 20 wt %, based on 100 wt % of the total weight of the ion transport layer. When the content of the second binder is within this range, it may be advantageous in improving adhesion between active materials without increasing the negative electrode resistance.

[0056] In one embodiment, the content of the first binder in the negative electrode coating layer may be equal to or less than the content of the second binder in the ion transport layer. The first and second binder contents may be compared in terms of weight percent (wt%) of each layer. For example, the first binder content is expressed as a percentage of 100 wt% of the negative electrode coating layer, and the second binder content is expressed as a percentage of 100 wt% of the ion transport layer.

[0057] When the content of the first binder is equal to or less than the content of the second binder, it can be advantageous to uniformly deposit lithium in the anode coating layer containing the first binder and to effectively perform the role of lithium ion transport in the ion transport layer containing the second binder. If the content of the first binder is higher than the content of the second binder, the electrical resistance of the anode coating layer containing the first binder is relatively higher than that of the ion transport layer, which can lead to lithium deposition between the anode coating layer and the ion transport layer or to non-uniform lithium deposition, which is not appropriate.

[0058] In one embodiment, the content of the first amorphous carbon in the negative electrode coating layer may be 60 wt % to 95 wt %, 70 wt % to 95 wt %, 75 wt % to 95 wt %, 80 wt % to 95 wt %, or 85 wt % to 95 wt %, based on 100 wt % of the total weight of the negative electrode coating layer. When the content of the first amorphous carbon is within this range, it may be able to more effectively buffer the volume change that occurs when lithium is deposited, and may be advantageous in facilitating reversible charge and discharge.

[0059] According to an embodiment, the content of the metal in the negative electrode coating layer may be 3 wt % to 39 wt %, 3 wt % to 30 wt %, 4 wt % to 25 wt %, 5 wt % to 20 wt %, or 5 wt % to 15 wt %, based on 100 wt % of the weight of the negative electrode coating layer. When the content of the metal is within this range, the metal may more effectively form an alloy with lithium, and the alloy may grow well in the planar direction, resulting in uniform deposition of lithium.

[0060] The content of the second amorphous carbon in the ion transport layer may be 50 to 95 wt%, 70 to 95 wt%, 75 to 95 wt%, 80 to 95 wt%, or 85 to 95 wt%, based on 100 wt% of the total weight of the ion transport layer. When the content of the second amorphous carbon is within this range, lithium ions may be able to move more quickly and without resistance through the second amorphous carbon.

[0061] In one embodiment, the ion transport layer may have a porosity of 5% to 50%, or 20% to 40%. When the porosity of the ion transport layer is in this range, lithium ions can efficiently move through the pores.

[0062] In addition, the negative electrode coating layer may have a porosity of 10% to 30%, or may have a porosity of 15% to 20%. When the porosity of the negative electrode coating layer is within this range, the problem of lithium growth between pores can be more effectively suppressed, lithium can be easily transported through the pores, resistance can be further reduced, and lithium electrodeposition can be effectively induced, which is preferable.

[0063] The negative electrode coating layer may further include additives such as a filler, a dispersant, an ion conductive material, etc. The filler, dispersant, ion conductive material, etc. that can be included in the negative electrode coating layer may be any known material that is generally used in all-solid-state batteries.

[0064] According to an embodiment, the negative electrode may further include a lithium-containing layer between the current collector and the negative electrode coating layer.

[0065] The lithium-containing layer is a metal layer containing lithium, and therefore can act as, for example, a lithium reservoir and can be referred to as a lithium deposition layer.

[0066] The thickness of the lithium-containing layer may be 1 μm to 1000 μm, 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 150 μm, 1 μm to 100 μm, or 1 μm to 50 μm. When the thickness of the lithium-containing layer is within this range, it may be possible to appropriately function as a lithium reservoir and further improve the lifespan.

[0067] Such a lithium-containing layer can be formed by, after the manufacture of an all-solid-state battery, releasing lithium ions from the positive electrode active material during charging, passing through the solid electrolyte and migrating to the negative electrode side, resulting in the deposition and vapor deposition of lithium on the negative electrode current collector, as shown in Figure 1. In Figure 1, the lithium-containing layer is shown as a lithium deposition layer.

[0068] The charging process may be a chemical conversion process carried out once to three times at about 25° C. to 50° C. and 0.05 C to 1 C. During discharge, lithium contained in the lithium-containing layer is ionized and migrates toward the positive electrode, and this lithium can be used as a negative electrode active material.

[0069] In one embodiment, since the lithium-containing layer is located between the current collector and the negative electrode coating layer, the negative electrode coating layer can serve as a protective layer for the lithium-containing layer and can suppress the precipitation and growth of lithium dendrites, thereby suppressing short circuits and capacity degradation in the all-solid-state battery and ultimately improving the cycle life of the all-solid-state battery.

[0070] The current collector may be, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof, and may be in the form of a foil or sheet. The thickness of the negative electrode current collector may be 1 μm to 20 μm, 5 μm to 15 μm, or 7 μm to 10 μm.

[0071] The current collector may be based on the metal and further include a thin film formed on the substrate. The thin film may include an element capable of forming an alloy with lithium, such as, but not limited to, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, or a combination thereof, and may include any element known in the art that can form an alloy with lithium. When the current collector further includes a thin film, the lithium-containing layer may be more planarized when deposited during charging, thereby further improving the cycle life of the all-solid-state battery.

[0072] The thickness of the thin film may be 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. When the thickness of the thin film is within this range, the cycle life characteristics can be further improved.

[0073] Another embodiment provides an all-solid-state battery comprising the anode, a cathode, and a solid electrolyte layer located between the anode and the cathode.

[0074] The solid electrolyte layer may include a solid electrolyte. The 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 solid electrolyte may be a sulfide-based solid electrolyte.

[0075] The sulfide-based solid electrolyte and the oxide-based solid electrolyte are as described above, and may be the same as or different from the solid electrolyte contained in the positive electrode or the negative electrode.

[0076] The solid polymer electrolyte may be, for example, polyethylene oxide, poly(diallyldimethylammonium)trifluoromethanesulfonylimide (poly(diallyldimethylammonium)TFSI), CuN, LiN, LiPON, or LiPO 4. Li2S·SiS2, Li2S·GeS2·Ga2S3, 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 , NaTiP0 12 , Na3Fe2P3O 12 , Na4NbP3O 12 , Na-Silicates, Li 0.3 La0.5 TiO3, Na5MSi4O 12 (M is a rare earth element such as Nd, Gd, 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, Q is Al or 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, A is Zn) can include one or more selected from the above.

[0077] The halide-based solid electrolyte can contain 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 the X. Examples of the M include metal elements such as Sc, Y, B, Al, Ga, and In.

[0078] The composition of the halide-based solid electrolyte is not particularly limited, but Li 6-3a M a Br bClc (where M in the formula is a metal other than Li, 0 < a < 2, 0 ≤ b ≤ 6, 0 ≤ c ≤ 6, and b + c = 6). At this time, a can be 0.75 or more, a can be 1 or more, and a can be 1.5 or less. b can be 1 or more, and b can be 2 or more. Also, c can be 3 or more, and c can be 4 or more. Specific examples of the halide-based solid electrolyte include Li3YBr6, Li3YCl 6、 or Li3YBr2Cl4.

[0079] The electrolyte layer can further contain a binder. At this time, the binder can be styrene-butadiene rubber, nitrile-butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, an acrylate-based polymer, or a combination thereof, but is not limited thereto, and any binder used in the technical field can be used. The acrylate-based polymer can be butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0080] The thickness of the electrolyte layer can be, for example, 1 μm to 150 μm.

[0081] The solid electrolyte layer can further contain an alkali metal salt, an ionic liquid, or a combination thereof.

[0082] The alkali metal salt can be, for example, a lithium salt. The content of the lithium salt in the solid electrolyte layer can be 1 M or more, and can be, for example, 1 M to 4 M. In this case, the lithium salt can improve the ionic conductivity by improving the lithium ion mobility of the solid electrolyte layer.

[0083] Examples of the lithium salt include 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), and lithium bis(trifluoromethanesulfonyl)imide (lithium The compound may include lithium bis(trifluoromethanesulfonyl)imide, LiTFSI, LiN(SOCF), lithium bis(fluorosulfonyl)imide, LiFSI, LiN(SOF), LiCFSO, LiAsF, LiSbF, LiClO, or a mixture thereof.

[0084] The lithium salt may be an imide-based lithium salt, for example, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SOCF)), or lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SOF)). The lithium salt may maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with the ionic liquid.

[0085] The ionic liquid has a melting point below room temperature and is a salt that is in a liquid state at room temperature and is composed only of ions, or a room-temperature molten salt.

[0086] The ionic liquid comprises: a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, 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 - The compound may contain one or more anions selected from the following:

[0087] The ionic liquid may be, for example, one or more selected from the group consisting of N-methyl-N-propylpyrrolidine bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide.

[0088] The weight ratio of the solid electrolyte to the ionic liquid in the solid electrolyte layer may be 0.1:99.9 to 90:10, 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.

[0089] The solid electrolyte layer can be formed by adding a solid electrolyte to a binder solution, coating the resulting solution on a substrate film, and drying. The solvent for the binder solution can be isobutylyl isobutyrate, isolene, toluene, benzene, hexane, or a combination thereof. The process for forming the solid electrolyte layer is widely known in the art, and therefore, a detailed description thereof will be omitted herein.

[0090] The positive electrode includes a current collector and a positive electrode layer located on one surface of the current collector.

[0091] The positive electrode layer may include a positive electrode active material. The positive electrode active material may be a positive electrode active material capable of reversibly absorbing and releasing lithium ions. For example, the positive electrode active material may be one or more of composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. Specific examples of the positive electrode active material include Li a A 1-b B 1 b D 1 2(0.90≦a≦1.8, 0≦b≦0.5);Li a E 1-b B 1 b O 2-c D 1 c (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.5);Li a E 2-b B 1 b O 4-c D 1 c (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.5);Li a Ni 1-b-c Co b B 1 c D 1 α (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.5, 0<α≦2);Li a Ni 1-b-c Co b B1 c O 2-α F 1 α (0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.5、0<α<2);Li a Ni 1-b-c Co b B 1 c O 2-α F 1 2(0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.5、0<α<2);Li a Ni 1-b-c Mr b B 1 c D 1 α (0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.5、0<α≦2);Li a Ni 1-b-c Mr b B 1 c O 2-α F 1 α (0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.5、0<α<2);Li a Ni 1-b-c Mr b B 1 c O 2-α F 1 2(0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.5、0<α<2);Li a Ni b HAVE BEEN c G d O2(0.90≦a≦1.8、0≦b≦0.9、0≦c≦0.5、0.001≦d≦0.1);Li a Ni b Co c L 1 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);Li a NiG b O2(0.90≦a≦1.8、0.001≦b≦0.1);Li a CoG bO2 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI 1 O2; LiNiVO4; Li (3-f) J2(PO4)3 (0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3 (0 ≤ f ≤ 2); or LiFePO4 may be mentioned.

[0092] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; B 1 is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D 1 is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F 1 is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I 1 is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0093] According to one embodiment, as the positive electrode active material, LiNi x Co y Al z O2 (NCA), LiNi x Co y Mn z O2 (NCM) (where 0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1), such as ternary lithium transition metal oxides, may be mentioned.

[0094] Of course, the compound may have a coating layer on its surface, or the compound may be mixed with a compound having a coating layer. The coating layer may include at least one coating element compound selected from the group consisting of oxides of the coating element, hydroxides of the coating element, oxyhydroxides of the coating element, oxycarbonates of the coating element, and hydroxycarbonates of the coating element. The compounds constituting these coating layers may be amorphous or crystalline. The coating elements contained in the coating layer may be Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer formation process may be performed using any coating method (e.g., spray coating, dipping, etc.) that does not adversely affect the physical properties of the positive electrode active material. This method is readily understood by those skilled in the art, so a detailed description will be omitted.

[0095] In addition, any other coating layer known as a coating layer for a positive electrode active material of an all-solid-state battery can be used as the coating layer, and examples thereof include Li2O-ZrO2 (LZO).

[0096] Furthermore, when the positive electrode active material contains nickel, cobalt, and manganese, or nickel, cobalt, and aluminum, the capacity density of the all-solid-state battery can be further improved and metal elution from the positive electrode active material in a charged state can be further reduced, thereby further improving the long-term reliability and cycle characteristics of the all-solid-state battery in a charged state.

[0097] Here, examples of the shape of the positive electrode active material include particle shapes such as spherical and oval spheres. The average particle size of the positive electrode active material is not particularly limited, and may be within a range applicable to positive electrode active materials of existing all-solid-state secondary batteries. The content of the positive electrode active material in the positive electrode layer is also not particularly limited, and may be within a range applicable to positive electrode layers of existing all-solid-state secondary batteries.

[0098] The content of the positive electrode active material in the positive electrode layer may be 69.8 wt % to 89.8 wt % based on the total weight of the positive electrode layer.

[0099] The positive electrode layer may further include a solid electrolyte. The solid electrolyte included in the positive electrode layer may be the same as or different from the solid electrolyte included in the solid electrolyte layer. The solid electrolyte may be included in an amount of 10 wt % to 30 wt % based on the total weight of the positive electrode layer.

[0100] The current collector may comprise, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof, and may be in the form of a foil or sheet.

[0101] The positive electrode layer may further include a binder and a conductive material.

[0102] Examples of the binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylate styrene-butadiene rubber, epoxy resin, and nylon.

[0103] The binder may be included in an amount of 0.1 to 5 wt %, or 0.1 to 3 wt %, based on the total weight of each component of the positive electrode for the all-solid-state battery or the total weight of the positive electrode active material layer. A binder in this content range can sufficiently exhibit adhesive properties without deteriorating battery performance.

[0104] The conductive material is used to impart conductivity to the electrodes, and any electron-conductive material that does not cause a chemical change in the constructed battery can be used. Examples of such conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, and carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, or the like in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; and conductive materials containing mixtures of these.

[0105] The conductive material may be contained in an amount of 0.1 to 5 wt %, or 0.1 to 3 wt %, based on the total weight of each component of the positive electrode for the all-solid-state battery or the total weight of the positive electrode active material layer. The conductive material in this content range can improve conductivity without deteriorating battery performance.

[0106] The thickness of the positive electrode layer may be 90 μm to 200 μm. For example, the thickness of the positive electrode layer may be 90 μm or more, 100 μm or more, 110 μm or more, 120 μm or more, 130 μm or more, 140 μm or more, 150 μm or more, 160 μm or more, 170 μm or more, 180 μm or more, or 190 μm or more, and may be 200 μm or less, 190 μm or less, 180 μm or less, 170 μm or less, 160 μm or less, 150 μm or less, 140 μm or less, 130 μm or less, 120 μm or less, or 110 μm or less. As described above, the thickness of the positive electrode layer is thicker than the total thickness of the negative electrode coating layer and the ion transport layer, so the capacity of the positive electrode is greater than the capacity of the negative electrode.

[0107] The positive electrode may be prepared by forming a positive electrode layer on a positive electrode current collector by dry or wet coating.

[0108] In one embodiment, a buffer material may be further included to buffer thickness changes that occur during charge and discharge of the all-solid-state battery. The buffer material may be located between the negative electrode and the case, and in the case of a battery in which one or more electrode assemblies are stacked, the buffer material may be located between different electrode assemblies.

[0109] The buffer material may be a material having an elastic recovery rate of 50% or more and having an insulating function, such as silicone rubber, acrylic rubber, fluorine-based rubber, nylon, synthetic rubber, or a combination thereof. The buffer material may be in the form of a polymer sheet.

[0110] 2 is a schematic diagram of an all-solid-state battery according to one embodiment. The all-solid-state secondary battery 1 includes a cathode / anode current collector 2 including a cathode current collector 7 and a cathode layer 6, an anode including an anode coating layer 3 and an ion transport layer 4, and a solid electrolyte layer 5 disposed between the cathode layer 6 and the ion transport layer 4. While FIG. 2 illustrates a configuration in which the anode 20 does not include a lithium-containing layer, as described above, the anode may include a lithium-containing layer formed between the anode current collector 2 and the anode coating layer 3 during charge and discharge.

[0111] An all-solid-state battery according to an embodiment may be manufactured by preparing a stack by positioning an anode, a cathode, and a solid electrolyte layer between the anode and the cathode, and pressing the stack.

[0112] The pressurization step can be carried out within the range of 25°C to 90°C. Further, the pressurization step can be carried out by pressurizing at a pressure within the range of 550 MPa or less, for example, 500 MPa or less, for example, 1 MPa to 500 MPa. The pressurization time may vary depending on temperature, pressure, etc., and can be, for example, less than 30 minutes. The pressurization step can be, for example, isostatic press, roll press, plate press, warm isostatic press.

Examples

[0113] Examples and comparative examples of the present invention are described below. Such examples below are an example of the present invention, and the present invention is not necessarily limited to the examples below.

[0114] <BET Evaluation> The BET specific surface area of the carbon black used in the experiment below was measured by the following method.

[0115] A mixed gas of nitrogen and helium (volume ratio of 1:1) was injected onto the carbon black surface and injected into a U-shaped sample cell. At that time, using the adsorption of nitrogen gas, it was detected by a thermal conductivity detector and measured by the specific surface area with the amount of adsorbed gas.

[0116] (Example 1) (1) Production of negative electrode 86% by weight of secondary particle carbon black (BET specific surface area: 150 m 2 / g, average particle size (D50): 400 nm) in which a plurality of primary particles with an average particle size (D50) of 35 nm are aggregated, 5% by weight of Ag with an average size of 60 nm, 3% by weight of carboxymethyl cellulose, and 6% by weight of styrene-butadiene rubber were mixed in water to produce a negative electrode coating layer slurry.

[0117] Secondary particle carbon black (BET specific surface area: 55 m) consisting of an aggregate of multiple primary particles with an average particle size (D50) of 35 nm. 2 75% by weight of cellulose acetate (C10 / g, average particle size (D50): 200 nm), 8% by weight of carboxymethyl cellulose, and 17% by weight of styrene-butadiene rubber were mixed in water to prepare a slurry for the ion conduction layer.

[0118] The negative electrode coating layer slurry was coated on a 10 μm-thick stainless steel foil current collector and dried to form a dry layer, and the ion transport layer slurry was coated on this dry layer and then vacuum dried at 80° C. to fabricate a negative electrode having a 15 μm-thick negative electrode coating layer and a 3 μm-thick ion transport layer. The porosity of the fabricated negative electrode coating layer was 20%, and the porosity of the ion transport layer was 30%.

[0119] (2) Manufacturing of solid electrolyte layer The ajirodite-type solid electrolyte Li6PS5Cl was mixed with an isobutylyl isobutylate binder solution (solid content: 50 wt%) containing butyl acrylate, an acrylate polymer. The mixing ratio of the solid electrolyte to the binder was 98.7:1.3 by weight.

[0120] The mixing process was carried out using a Thinky mixer. 2 mm zirconia balls were added to the resulting mixture and stirred again using the Thinky mixer to prepare a slurry. The slurry was cast onto a release polytetrafluoroethylene film and dried at room temperature to prepare a solid electrolyte layer with a thickness of 100 μm.

[0121] (3) Fabrication of all-solid-state half-cells The prepared negative electrode, solid electrolyte, and lithium metal counter electrode were sequentially stacked, and a pressure of 8 MPa was applied to fabricate an all-solid-state half-cell.

[0122] (4) Manufacturing of all-solid-state batteries (full-cell) LiNi 0.8 Co 0.1 Al 0.1 A positive electrode layer slurry was prepared by mixing 85.0 wt% of O2 positive electrode active material, 13.0 wt% of azirodite-type solid electrolyte Li6PS5Cl, 0.5 wt% of carbon nanotube conductive material, and 1.5 wt% of polyvinylidene fluoride binder in N-methylpyrrolidone solvent.

[0123] The positive electrode layer slurry was coated on an aluminum current collector, and then dried and rolled at 60° C. to prepare a positive electrode for an all-solid-state battery.

[0124] The prepared negative electrode, solid electrolyte, and positive electrode were sequentially applied, and warm isostatic pressing (WIP) at 8 MPa was performed to fabricate an all-solid-state battery.

[0125] Example 2 A negative electrode, an all-solid-state semi-cell, and an all-solid-state battery were fabricated in the same manner as in Example 1, except that a negative electrode having a 20 μm-thick negative electrode coating layer and a 2 μm-thick ion transport layer was fabricated using the negative electrode coating layer slurry and the ion transport layer slurry fabricated in Example 1. The porosity of the negative electrode coating layer in the fabricated negative electrode was 23%, and the porosity of the ion transport layer was 28%.

[0126] Example 3 A negative electrode, an all-solid-state semi-cell, and an all-solid-state battery were fabricated in the same manner as in Example 1, except that a negative electrode having a negative electrode coating layer with a thickness of 11 μm and an ion transport layer with a thickness of 4 μm was fabricated using the negative electrode coating layer slurry and ion transport layer slurry fabricated in Example 1. The porosity of the negative electrode coating layer in the fabricated negative electrode was 16%, and the porosity of the ion transport layer was 35%.

[0127] Example 4 A negative electrode, an all-solid-state semi-cell, and an all-solid-state battery were fabricated in the same manner as in Example 1, except that a negative electrode having a 7 μm-thick negative electrode coating layer and a 3 μm-thick ion transport layer was fabricated using the negative electrode coating layer slurry and the ion transport layer slurry fabricated in Example 1. The porosity of the negative electrode coating layer in the fabricated negative electrode was 14%, and the porosity of the ion transport layer was 30%.

[0128] Example 5 A negative electrode, an all-solid-state semi-cell, and an all-solid-state battery were fabricated in the same manner as in Example 1, except that a negative electrode having a 6 μm-thick negative electrode coating layer and a 3 μm-thick ion transport layer was fabricated using the negative electrode coating layer slurry and the ion transport layer slurry fabricated in Example 1. The porosity of the negative electrode coating layer in the fabricated negative electrode was 13%, and the porosity of the ion transport layer was 30%.

[0129] (Comparative Example 1) A negative electrode, an all-solid-state semi-cell, and an all-solid-state battery were fabricated in the same manner as in Example 1, except that a negative electrode having a 30 μm-thick negative electrode coating layer and a 2.5 μm-thick ion transport layer was fabricated using the negative electrode coating layer slurry and the ion transport layer slurry fabricated in Example 1. The porosity of the negative electrode coating layer in the fabricated negative electrode was 35%, and the porosity of the ion transport layer was 29%.

[0130] (Comparative Example 2) A negative electrode, an all-solid-state semi-cell, and an all-solid-state battery were fabricated in the same manner as in Example 1, except that a negative electrode having a 15 μm-thick negative electrode coating layer and a 9 μm-thick ion transport layer was fabricated using the negative electrode coating layer slurry and the ion transport layer slurry fabricated in Example 1. The porosity of the negative electrode coating layer in the fabricated negative electrode was 20%, and the porosity of the ion transport layer was 43%.

[0131] (Comparative Example 3) A negative electrode, an all-solid-state semi-cell, and an all-solid-state battery were fabricated in the same manner as in Example 1, except that a negative electrode having a 9 μm-thick negative electrode coating layer and a 5 μm-thick ion transport layer was fabricated using the negative electrode coating layer slurry and the ion transport layer slurry fabricated in Example 1. The porosity of the negative electrode coating layer in the fabricated negative electrode was 15%, and the porosity of the ion transport layer was 36%.

[0132] Comparative Example 4 A negative electrode, an all-solid-state semi-cell, and an all-solid-state battery were fabricated in the same manner as in Example 1, except that a negative electrode having an 8 μm-thick negative electrode coating layer and a 10 μm-thick ion transport layer was fabricated using the negative electrode coating layer slurry and the ion transport layer slurry fabricated in Example 1. The porosity of the negative electrode coating layer in the fabricated negative electrode was 15%, and the porosity of the ion transport layer was 40%.

[0133] Experimental Example 1) 3D Optical Photography (3D Optical Microscope (OM) measurements The cross section of the negative electrode prepared in Example 1 was polished (CP, cross polisher) and then photographed at 2000x magnification using a 3D OM (Keyence Corporation), the results of which are shown in Figure 3. As shown in Figure 3, the negative electrode prepared in Example 1 has a negative electrode coating layer (referred to as a deposition-type negative electrode layer in Figure 3) and an ion transport layer formed in that order on the current collector.

[0134] Experimental example 2) Evaluation of overvoltage The all-solid-state half-cells of Examples 1 to 5 and Comparative Examples 1 to 4 were charged once at 0.05 C. The voltage drop started at OCV (open circuit voltage, approximately 2.5 V), and the voltage was measured from approximately 0 mV to the point where an inflection point occurred. The measured results are shown in Table 1 below as initial overvoltage.

[0135] Experimental example 3) Evaluation of charge / discharge efficiency The all-solid-state half-cells of Examples 1 to 5 and Comparative Examples 1 to 4 were charged and discharged once at 0.05 C. The ratio of the discharge capacity to the charge capacity was calculated (single discharge capacity / single charge capacity), and the results are shown in Table 1 below as initial efficiency.

[0136] Experimental example 4) Evaluation of cycle life The all-solid-state batteries (full-cells) of Examples 1 to 5 and Comparative Examples 1 to 4 were charged and discharged 100 times at 0.33 C. The ratio of the 100th discharge capacity to the 1st discharge capacity was calculated. Based on this value, the batteries were classified according to the following criteria, and the results are shown in Table 1 below.

[0137] X:<90%[(100 times discharge capacity / 1 time discharge capacity)*100] ○:90%[(100 times discharge capacity / 1 time discharge capacity)*100]

[0138] [Table 1]

[0139] As shown in Table 1 above, in Examples 1 to 5, in which the thickness ratio of the anode coating layer to the ion transport layer was 1:0.1 to 1:0.5, the overvoltage was low, the charge / discharge efficiency was excellent, and the cycle life characteristics were excellent.

[0140] On the other hand, in Comparative Examples 1 to 8, where the thickness ratio of the negative electrode coating layer to the ion transport layer was outside the range of 1:0.1 to 1:0.5, the overvoltage was too high, the charge / discharge efficiency was very low, and the cycle life characteristics were also deteriorated.

[0141] Although the preferred embodiment of the present invention has been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the claims, the detailed description of the invention, and the accompanying drawings, and it is natural that these also fall within the scope of the present invention.

Claims

1. A negative electrode for an all-solid-state battery, current collector; an ion transport layer; and a negative electrode coating layer positioned between the current collector and the ion transport layer, the negative electrode coating layer including first amorphous carbon, a metal, and a first binder; Including, The thickness ratio of the anode coating layer to the ion transport layer is 1:0.1 to 1:0.

5.

2. 2. The anode for an all-solid-state battery according to claim 1, wherein a thickness ratio of the anode coating layer to the ion transport layer is 1:0.15 to 1:0.

5.

3. 2. The negative electrode for an all-solid-state battery according to claim 1, wherein the ion conduction layer has a thickness of 0.5 μm to 5 μm.

4. The anode for an all-solid-state battery according to claim 1 , wherein the thickness of the anode coating layer is 5 μm to 50 μm.

5. 2. The negative electrode for an all-solid-state battery according to claim 1, wherein the ion transport layer comprises a second amorphous carbon and a second binder.

6. The second amorphous carbon is 10 m 2 / g over 100m 2 The negative electrode for an all-solid-state battery according to claim 5 , having a BET specific surface area of ​​less than 1 / g.

7. The first amorphous carbon is 50 m 2 / g, 1500m 2 The negative electrode for an all-solid-state battery according to claim 1 , having a BET specific surface area of ​​less than 1 / g.

8. the ion transport layer comprises a second amorphous carbon and a second binder; 2. The negative electrode for an all-solid-state battery according to claim 1, wherein the specific surface area of ​​the second amorphous carbon is smaller than the specific surface area of ​​the first amorphous carbon.

9. 2. The anode of claim 1, wherein the content of the first binder is 1 to 15 wt % based on 100 wt % of the total weight of the anode coating layer.

10. 6. The negative electrode for an all-solid-state battery according to claim 5, wherein the content of the second binder is 5 to 50 wt% with respect to 100 wt% of the total weight of the ion transport layer.

11. 2. The negative electrode for an all-solid-state battery according to claim 1, wherein the ion transport layer has a porosity of 5% to 50%.

12. The negative electrode for an all-solid-state battery according to claim 1 , wherein the negative electrode coating layer has a porosity of 10% to 30%.

13. 2. The negative electrode for an all-solid-state battery according to claim 1, wherein the metal is Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd, or a combination thereof.

14. 6. The negative electrode for an all-solid-state battery according to claim 5, wherein the second amorphous carbon is carbon black, acetylene black, denka black, ketjen black, furnace black, activated carbon, carbon nanofiber, or a combination thereof.

15. The negative electrode for an all-solid-state battery according to claim 5 , wherein the second amorphous carbon is an aggregate having a form of secondary particles formed by aggregation of primary particles.

16. The negative electrode according to any one of claims 1 to 15; a positive electrode; and a solid electrolyte layer located between the negative electrode and the positive electrode; Including solid-state batteries.

17. 17. The all-solid-state battery according to claim 16, wherein the solid electrolyte is a sulfide-based solid electrolyte.

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