All-solid-state batteries

Abstract

This invention further maximizes energy density by eliminating amorphous carbon between the negative electrode current collector and the solid electrolyte layer. Even without amorphous carbon, it prevents lithium dendrites from growing through the gaps in the solid electrolyte layer as the charge-discharge process is repeated, thereby solving problems such as short circuits or capacity degradation. Furthermore, it provides an all-solid-state battery with excellent capacity retention rate over cycles.

Description

[Technical Field]

[0001] This application claims priority under Republic of Korea Patent Application No. 2023-0162269 dated November 21, 2023, and all content disclosed in the documents of the said Republic of Korea Patent Application is incorporated herein by reference. The present invention relates to an all-solid-state battery in which a separate negative electrode active material layer is not formed on the negative electrode current collector during the battery manufacturing process, and a lithium layer is formed during the charging process. [Background technology]

[0002] In recent years, industrial demands have led to the proposal of all-solid-state batteries with high energy density and stability, and efforts are continuing to further improve these characteristics. For example, research is being conducted on using lithium as the negative electrode active material to increase the energy density of all-solid-state batteries.

[0003] Methods for using lithium as a negative electrode active material include using lithium or a lithium alloy as a negative electrode active material layer during the battery manufacturing process, or not forming a separate negative electrode active material layer on the negative electrode current collector during the battery manufacturing process, but instead forming a lithium layer during the charging process.

[0004] However, when lithium is used as the negative electrode active material, lithium (metallic lithium) is deposited on the negative electrode side during charging. As the charge-discharge process is repeated, lithium dendrites grow through the gaps in the solid electrolyte layer, which can cause battery short circuits or a decrease in capacity, thus posing a problem.

[0005] Therefore, in order to put into practical use a method that uses lithium as a negative electrode active material, it is necessary to improve the aforementioned problems. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention aims to solve the aforementioned problems by providing an all-solid-state battery in which a separate negative electrode active material layer is not formed on the negative electrode current collector during the battery manufacturing process, and a lithium layer is formed during the charging process. By not including amorphous carbon between the negative electrode current collector and the solid electrolyte layer, the energy density can be further maximized. Even without including amorphous carbon, the growth of lithium dendrites through the gaps in the solid electrolyte layer can be prevented by repeated charge and discharge processes, thereby solving the problems of short circuits or capacity degradation. Furthermore, the invention aims to provide an all-solid-state battery with excellent capacity retention rate over cycles. [Means for solving the problem]

[0007] One aspect of the present invention relates to an all-solid-state battery using lithium or a lithium alloy as the negative electrode active material, wherein the all-solid-state battery comprises a negative electrode current collector and a solid electrolyte layer, and either includes a silver (Ag) nanolayer between the negative electrode current collector and the solid electrolyte layer, or silver (Ag) nanoparticles are distributed between the negative electrode current collector and the solid electrolyte layer, and does not contain amorphous carbon between the negative electrode current collector and the solid electrolyte layer.

[0008] In one embodiment, before charging after battery manufacturing, a silver (Ag) nanolayer is included between the negative electrode current collector and the solid electrolyte layer, and after charging, silver (Ag) nanoparticles are distributed between the negative electrode current collector and the solid electrolyte layer.

[0009] In one embodiment, the silver (Ag) nanolayer may be characterized as a silver vapor-deposited layer.

[0010] In one embodiment, the thickness of the silver (Ag) nanolayer may be 1000 nm or less.

[0011] In one embodiment, the average particle size of the silver (Ag) nanoparticles may be 1000 nm or less.

[0012] In one embodiment, before charging after battery manufacturing, the ratio d2 / d1 of the distance d2 between the surface of the negative electrode current collector and the solid electrolyte layer to the thickness d1 of the negative electrode current collector may be 0.001 to 0.1.

[0013] In one embodiment, at full charge, the ratio d3 / d1 of the distance d3 between the surface of the negative electrode current collector and the solid electrolyte layer to the thickness d1 of the negative electrode current collector may be 0.5 to 10.

[0014] In one embodiment, at full discharge, the ratio d4 / d1 of the distance d4 between the surface of the negative electrode current collector and the solid electrolyte layer to the thickness d1 of the negative electrode current collector may be 0.01 or less.

[0015] In one embodiment, the solid electrolyte layer may contain a sulfide-based solid electrolyte.

[0016] In one embodiment, the sulfide-based solid electrolyte is Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-LiBr-LiI-P2S5, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li 7-x , 6-x , , n , 6-x , q , <000001​​​​​​​​​​​​​​​​​​​​​​​​It can be characterized by being one or more selected from the group that includes (0 ≤ x ≤ 2).

[0017] In one embodiment, the all-solid-state battery of the present invention may be characterized by further including a positive electrode.

[0018] In one embodiment, the all-solid-state battery of the present invention may be characterized in that, when fully discharged, the thickness of a monocell containing one negative electrode and one positive electrode is 120 to 180 μm.

[0019] In one embodiment, the all-solid-state battery of the present invention may be characterized by having a thickness of 150 to 210 μm based on a monocell containing one negative electrode and one positive electrode when fully charged.

[0020] In one embodiment, the all-solid-state battery of the present invention may be characterized by having an initial discharge capacity of 185 mAh / g or more, as a result of life characteristic evaluation.

[0021] In one embodiment, the all-solid-state battery of the present invention may be characterized by a capacity retention rate of 80% or more after 50 cycles. [Effects of the Invention]

[0022] In particular, the present invention provides an all-solid-state battery in which a separate negative electrode active material layer is not formed on the negative electrode current collector during the battery manufacturing process, and a lithium layer is formed during the charging process. By not including amorphous carbon between the negative electrode current collector and the solid electrolyte layer, the energy density can be further maximized. Even without amorphous carbon, the growth of lithium dendrites through the gaps in the solid electrolyte layer can be prevented by repeated charge-discharge processes, thereby solving the problems of short circuits or capacity degradation. Furthermore, an all-solid-state battery with excellent capacity retention rate over cycles can be provided. [Brief explanation of the drawing]

[0023] [Figure 1]This is an image of the surface of a silver nanolayer taken with a scanning electron microscope (magnification: 1K). [Figure 2] This is an image of the surface of a silver nanolayer taken with a scanning electron microscope (magnification: 5K). [Figure 3] This image shows the results of EDS analysis on the negative electrode of the example. [Figure 4] This graph shows the cycle capacity of the monocells in the examples and comparative examples. [Figure 5] This graph shows the capacity retention rate over the cycle of monocells in the examples and comparative examples. [Modes for carrying out the invention]

[0024] The terms and words used in this specification and in the claims should not be construed to be limited to their ordinary or dictionary meanings, but rather should be construed in a sense and concept consistent with the technical idea of ​​the present invention, based on the principle that inventors can appropriately define the concepts of terms in order to best describe their invention.

[0025] Therefore, the configurations of the embodiments described herein represent only one of the most preferred embodiments of the present invention and do not represent the entire technical concept of the invention. It should be understood that, at the time of filing, there may be a variety of equivalents and modifications that can be substituted for these.

[0026] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0027] In this specification, when a part is said to "contain" a component, this means, unless otherwise stated, that it may contain other components rather than excluding them. For example, a composition containing compound A may contain other compounds other than A. However, the term "contains" also encompasses, in its particular embodiment, the more restrictive meanings of "essentially / essentially composed of" and "composed of," for example, a "composition containing compound A" may also be (essentially / essentially) composed of compound A.

[0028] In this regard, as described herein, terms such as “to provide” or “to have” are intended to specify the existence of implemented features, figures, stages, components, or combinations thereof, and should be understood not to preemptively exclude the possibility of the existence or addition of one or more different features, figures, stages, components, or combinations thereof.

[0029] In this specification, when any layer is said to be located "on top of" or "between" any other layer, this includes not only cases where any layer is in contact with any other layer, but also cases where there are other layers or materials between the two layers.

[0030] Where, in this specification, a quantity, concentration, or other value or parameter is given by listing a range, preferred range, preferred upper limit, and preferred lower limit, it should be understood that this specifically discloses all ranges that can be formed by any pair of any upper range limits or preferred values ​​and any lower range limits or preferred values, regardless of whether the range is disclosed separately. Where, in this specification, a range of numerical values ​​is referred to, unless otherwise stated, and unless there are limiting terms such as greater than or less than, the range is intended to include its endpoint and all integers and fractions within that range. The scope of the present invention is intended not to be limited to specific values ​​referred to when defining a range.

[0031] In this specification, if the measurement temperature affects the physical properties mentioned, those properties are measured at room temperature unless otherwise specified. The term "room temperature" refers to the natural temperature without heating or deheating, and may mean, for example, any temperature within the range of approximately 10°C to 30°C, or approximately 23°C or 25°C. Furthermore, unless otherwise specified, the unit of temperature in this specification is °C.

[0032] Furthermore, in the case of any physical properties mentioned herein where the measurement pressure affects the property in question, unless otherwise specified, the physical properties are measured at normal pressure, i.e., atmospheric pressure (approximately 1 atmosphere).

[0033] A first aspect of the present invention relates to an all-solid-state battery using lithium or a lithium alloy as the negative electrode active material.

[0034] The all-solid-state battery may, for example, include a negative electrode current collector and a solid electrolyte layer, and may be characterized by including a silver (Ag) nanolayer between the negative electrode current collector and the solid electrolyte layer, or by having silver (Ag) nanoparticles distributed between the negative electrode current collector and the solid electrolyte layer, and not containing amorphous carbon between the negative electrode current collector and the solid electrolyte layer.

[0035] The present invention may relate to an all-solid-state battery that uses lithium or a lithium alloy as the negative electrode active material, and more particularly to an all-solid-state battery in which a separate negative electrode active material layer is not formed on the negative electrode current collector during the battery manufacturing process, and a lithium layer is formed during the charging process.

[0036] The lithium layer may include, for example, lithium or a lithium alloy.

[0037] In all-solid-state batteries, in which a separate negative electrode active material layer is not formed on the negative electrode current collector during the battery manufacturing process, and a lithium layer is formed during the charging process, a method has been proposed to introduce a non-negative electrode coating layer containing amorphous carbon (e.g., one or more selected from the group consisting of carbon black, acetylene black, furnace black, Ketjen black, and graphene) as an essential component between the negative electrode current collector and the solid electrolyte layer in order to solve problems such as the growth of lithium dendrites formed during the charge-discharge process and the resulting short circuits or capacity degradation. Although the clear mechanism has not been elucidated, it is expected that the amorphous carbon can control the growth of lithium dendrites by ensuring that lithium ions are uniformly deposited between the non-negative electrode coating layer and the negative electrode current collector during the charging process, and in addition, the non-negative electrode coating layer containing amorphous carbon can act as a protective layer to control short circuits and the like. Therefore, conventionally, amorphous carbon and / or a non-negative electrode coating layer containing it have been introduced between the solid electrolyte layer and the negative electrode current collector. In this specification, "negative electrode coating layer" refers to a coating layer formed between the negative electrode current collector and the solid electrolyte layer in an all-solid-state battery in which lithium is absorbed into the negative electrode coating layer during charging, lithium is deposited between the negative electrode current collector and the negative electrode coating layer after the charging capacity of the negative electrode coating layer is exceeded to form a lithium layer, and the lithium in the negative electrode coating layer and the lithium layer is ionized and moves to the positive electrode side during discharge.

[0038] However, since the non-negative electrode coating layer also has a thickness of approximately 1 to 20 μm, in order to further maximize energy density and further improve cycle characteristics, it was necessary to either further reduce the thickness of the non-negative electrode coating layer or to provide a new solution that could achieve the above-mentioned objectives without introducing the non-negative electrode coating layer.

[0039] In contrast, the present invention includes a silver (Ag) nanolayer between the negative electrode current collector and the solid electrolyte layer, or distributes silver (Ag) nanoparticles between the negative electrode current collector and the solid electrolyte layer. This eliminates the need to include amorphous carbon between the negative electrode current collector and the solid electrolyte layer, thereby further maximizing energy density. Furthermore, even without amorphous carbon, it is possible to prevent the growth of lithium dendrites through the gaps in the solid electrolyte layer as the charge-discharge process is repeated, thereby solving the problems of short circuits or capacity degradation. Moreover, it has been confirmed that this provides an all-solid-state battery with excellent capacity retention rate over cycles.

[0040] The present invention may, for example, include a silver (Ag) nanolayer between the negative electrode current collector and the solid electrolyte layer.

[0041] The silver (Ag) nanolayer may be characterized by being, for example, a silver vapor-deposited layer. The silver vapor-deposited layer may be formed, for example, using an electron beam vacuum deposition (E-beam evaporator) method. The silver nanolayer may be characterized by not containing any substances other than silver (Ag). The silver nanolayer may not contain a binder, for example, thereby controlling the increase in battery resistance.

[0042] The thickness of the silver (Ag) nanolayer may be, for example, 1000 nm or less. The thickness of the silver (Ag) nanolayer may be measured, for example, by SEM, and may represent the average thickness, minimum thickness, and / or maximum thickness. The thickness of the silver (Ag) nanolayer may be 950 nm or less, 900 nm or less, 850 nm or less, 800 nm or less, 750 nm or less, 700 nm or less, 650 nm or less, 600 nm or less, 550 nm or less, 500 nm or less, 450 nm or less, 400 nm or less, 350 nm or less, or 300 nm or less, or 10 nm or more, 20 nm or more, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, 70 nm or more, 80 nm or more, 90 nm or more, 100 nm or more, 110 nm or more, 120 nm or more, 130 nm or more, 140 nm or more, 150 nm or more, 160 nm or more, 170 nm or more, 180 nm or more, 190 nm or more, 200 nm or more, 210 nm or more, 220 nm or more, 230 nm or more, or 240 nm or more. The all-solid-state battery of the present invention can further improve energy density and capacity by including a silver nanolayer within the aforementioned thickness range, and can form a uniform lithium layer during the charging process.

[0043] The all-solid-state battery of the present invention may have a configuration in which, for example, a silver nanolayer contained between the negative electrode current collector and the solid electrolyte layer is rearranged into silver nanoparticles during the battery charging process, resulting in a distribution of silver nanoparticles between the negative electrode current collector and the solid electrolyte layer. The rearrangement of the silver nanolayer into silver nanoparticles is irreversible, and after one battery charge, the configuration in which silver nanoparticles are distributed between the negative electrode current collector and the solid electrolyte layer can be maintained. However, this does not mean that the presence of a nanolayer in part between the negative electrode current collector and the solid electrolyte layer after charging is completely eliminated.

[0044] In other words, the all-solid-state battery of the present invention may include a silver (Ag) nanolayer between the negative electrode current collector and the solid electrolyte layer before charging after battery manufacturing, and may have a configuration in which silver (Ag) nanoparticles are distributed between the negative electrode current collector and the solid electrolyte layer after charging.

[0045] In this specification, "silver nanoparticles are distributed between the negative electrode current collector and the solid electrolyte layer" means that the silver nanoparticles are present in the region between the negative electrode current collector and the solid electrolyte layer in the form of primary and / or secondary particles, or, more preferably, from the viewpoint of controlling the growth of lithium dendrites, at least some or all of the silver nanoparticles are present embedded on one surface of the solid electrolyte layer (for example, the surface of the solid electrolyte layer facing the negative electrode current collector). The silver nanoparticles may be distributed uniformly or non-uniformly between the negative electrode current collector and the solid electrolyte layer, and from the viewpoint of forming a uniform lithium layer during the charging process, it may be preferable that the silver nanoparticles be distributed uniformly between the negative electrode current collector and the solid electrolyte layer.

[0046] The average particle size of the silver (Ag) nanoparticles may be characterized by being, for example, 1000 nm or less. The average particle size of the silver nanoparticles may be measured by SEM. The average particle size of the silver nanoparticles may refer to the average particle size of primary particles and / or secondary particles. In other examples, the average particle size of the silver nanoparticles may be 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, or 200 nm or less. The lower limit of the average particle size of the silver nanoparticles is not particularly limited, but may be, for example, 1 nm or more, 5 nm or more, 10 nm or more, 20 nm or more, or 30 nm or more. The all-solid-state battery of the present invention can further suppress the formation of lithium dendrites by distributing silver nanoparticles having the above-mentioned average particle size between the negative electrode current collector and the solid electrolyte layer after battery charging.

[0047] The all-solid-state battery of the present invention may be characterized, for example, by the formation of a lithium layer between the negative electrode current collector and the solid electrolyte layer during the charging process. Through the combination of the above configurations, the all-solid-state battery of the present invention is thought to be able to suppress the growth of lithium dendrites by causing the silver nanolayer and / or silver nanoparticles present between the negative electrode current collector and the solid electrolyte layer to react with lithium during the process in which lithium is deposited between the negative electrode current collector and the solid electrolyte layer during charging, thereby forming a lithium alloy, and thus preventing short circuits in the battery. On the other hand, in the initial state of the all-solid-state battery (pre-charging state after battery manufacturing) or the state after discharge, the area between the negative electrode current collector and the solid electrolyte layer may be a lithium-free (Li-Free) region that does not contain lithium.

[0048] The all-solid-state battery of the present invention may be characterized, for example, before charging after battery manufacturing, by having a ratio d2 / d1 of 0.001 to 0.1 of the distance d2 between the surface of the negative electrode current collector and the solid electrolyte layer compared to the thickness d1 of the negative electrode current collector. In this specification, "distance between the surface of the negative electrode current collector and the solid electrolyte layer" may mean, for example, the distance from the surface of the negative electrode current collector that is closer to the solid electrolyte layer to the surface of the solid electrolyte layer that is closer to the negative electrode current collector. In other examples, the all-solid-state battery of the present invention may be characterized, for example, before charging after battery manufacturing, by having a ratio d2 / d1 of 0.005 or more, 0.01 or more, 0.015 or more, or 0.02 or more compared to the thickness d1 of the negative electrode current collector, or by 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, 0.05 or less, 0.04 or less, or 0.03 or less.

[0049] The all-solid-state battery of the present invention may be characterized, for example, by having a ratio d3 / d1 of the distance d3 between the surface of the negative electrode current collector and the solid electrolyte layer to the thickness d1 of the negative electrode current collector, which is 0.5 to 10, when fully charged. The all-solid-state battery of the present invention does not contain amorphous carbon, and instead distributes silver nanoparticles between the negative electrode current collector and the solid electrolyte layer when fully charged, thereby further improving energy density while suppressing lithium dendrite growth and the occurrence of short circuits. In other examples, the all-solid-state battery of the present invention may be characterized by having a ratio d3 / d1 of the distance d3 between the surface of the negative electrode current collector and the solid electrolyte layer to the thickness d1 of the negative electrode current collector, which is 1 or more, 1.5 or more, 2 or more, or 2.5 or more, or 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, or 4 or less, when fully charged.

[0050] During the complete discharge of an all-solid-state battery, the lithium layer formed between the negative electrode current collector and the solid electrolyte layer during the charging process can ionize into lithium ions and move towards the positive electrode side, as described later. As a result, the area between the negative electrode current collector and the solid electrolyte layer of the all-solid-state battery becomes a lithium-free region during complete discharge. Therefore, during the complete discharge of an all-solid-state battery, the distance between the surface of the negative electrode current collector and the solid electrolyte layer can decrease even further compared to when fully charged.

[0051] The all-solid-state battery of the present invention may be characterized, for example, by having a ratio d4 / d1 of the distance d4 between the surface of the negative electrode current collector and the solid electrolyte layer to the thickness d1 of the negative electrode current collector, which is 0.01 or less, when fully discharged. In other examples, the all-solid-state battery of the present invention may have a ratio d4 / d1 of 0.005 or less or 0.001 or less of the distance d4 between the surface of the negative electrode current collector and the solid electrolyte layer to the thickness d1 of the negative electrode current collector, when fully discharged, and since the space between the solid electrolyte layer and the negative electrode current collector is a lithium-free region while the silver nanoparticles are distributed in a form embedded in the solid electrolyte layer, the ratio d4 / d1 may be substantially 0.

[0052] The negative electrode current collector can be any known metal usable as a current collector for all-solid-state batteries. The negative electrode current collector can be any material that does not form alloys or compounds with lithium, for example. The negative electrode current collector can be any material selected from the group consisting of, for example, copper (Cu), nickel (Ni), aluminum (Al), vanadium (V), gold (Au), platinum (Pt), magnesium (Mg), iron (Fe), titanium (Ti), cobalt (Co), chromium (Cr), zinc (Zn), germanium (Ge), indium (in), and stainless steel, but is not limited thereto. Any material used as an electrode current collector in the relevant art can be used, as long as it does not hinder the purpose of the present invention. The negative electrode current collector may be composed of one of the aforementioned metals or of an alloy or coating material of two or more metals. The negative electrode current collector may be in the form of, for example, a plate, mesh, or foil, but is not limited thereto.

[0053] The solid electrolyte layer may contain, for example, one or more sulfide-based solid electrolytes, oxide-based solid electrolytes, or halide-based solid electrolytes. From the viewpoint of realizing excellent ionic conductivity and high energy density, the solid electrolyte layer may, but is not limited to, a sulfide-based solid electrolyte.

[0054] The aforementioned sulfide-based solid electrolytes are, for example, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-LiBr-LiI-P2S5, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-Li3PO4, and Li2S-SiS2-Li p MO q (p and q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, and In), Li2S-SiS2-P2S5-LiI, Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element), Li2S-B2S3, Li2S-P2S5-Z m S n(m and n are positive numbers, Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li 7-x PS 6-x Cl x (0≦x≦2), Li 7-x PS 6-x Br x (0≦x≦2), and Li 7-x PS 6-x I x It can be characterized by being one or more selected from the group that includes (0 ≤ x ≤ 2).

[0055] Sulfide-based solid electrolytes can be manufactured by processing starting materials such as Li2S and P2S5 using methods such as melt-quenching or mechanical milling. Furthermore, heat treatment can be performed after such processing. Solid electrolytes can be amorphous, crystalline, or a mixture thereof. In the present invention, a sulfide-based solid electrolyte may be, for example, a sulfide-based solid electrolyte material containing at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements.

[0056] The aforementioned sulfide-based solid electrolyte is, for example, Li 7-x PS 6-x Cl x (0≦x≦2), Li 7-x PS 6-x Br x (0≦x≦2), and Li 7-x PS 6-x I x The compound may be an argyrodite-type compound containing one or more values ​​selected from (0 ≤ x ≤ 2). In particular, sulfide-based solid electrolytes may be argyrodite-type compounds containing one or more values ​​selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0057] The density of the argyrodite-type solid electrolyte can be, for example, 1.5 to 2.0 g / cc. When the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state secondary battery decreases, and penetration of the solid electrolyte by Li can be effectively suppressed.

[0058] The elastic modulus of the sulfide-based solid electrolyte can be, for example, 15 to 45 GPa.

[0059] The oxide-based solid electrolyte can be, for example, any one or more of a garnet-type solid electrolyte, a NASICON-type solid electrolyte, a LISICON-type solid electrolyte, or a perovskite-type solid electrolyte. Specifically, the oxide-based solid electrolyte includes Li7La3Zr2O 12 , those obtained by doping elements such as Al, Y, Ga, Ta, Nb, etc. instead of Li in the Li7La3Zr2O 12 , or those obtained by multi-doping Ga 12 -Sc +3 etc. at the positions of Li and La, Zr elements in the Li7La3Zr2O +3 ; or those obtained by coating substances such as Al2CO3, Ge, ZnO, etc. on their surfaces; or Na 1+x Zr2Si2P 3-x O 12 (0≦x≦3), LiM2(PO4)3 (M = Zr, Ti, Ge), Li 1+x Al x M 2-x ((PO4)3 (0 < x < 2, M = Zr, Ti, Ge), or those obtained by doping atoms with an oxidation number of +3 such as Y, La, Sc, etc. instead of Al, or those obtained by doping atoms with an oxidation number of +2 such as Sr, Mg, Ca, etc.; xLi3AO4-(1-x)Li4BO4 (A: P, As, V, etc., B: Si, Ge, Ti, etc.) or those obtained by adding Li3BO3, etc. thereto; or Li 3x La 2 / 3-x □ 1 / 3-2xTiO3 (LLTO, 0 < x < 0.16, □ represents vacancy), La 0.57-2x / 3 Sr x Li 0.3 TiO3 and the like can be used, but are not limited thereto.

[0060] Examples of the halide-based solid electrolyte include Li2ZrCl6, Li 2+x Zr 1-x M x Cl6 (M = Fe, Cr, V), and Na2ZrCl6 and the like can be used, but are not limited thereto.

[0061] The solid electrolyte layer can further include, for example, a binder. Examples of the binder include an aqueous binder, an organic binder, or a combination thereof. The binder can be, for example, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinylidene fluoride, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylate styrene-butadiene rubber, epoxy resin, nylon, or a combination thereof. Examples of the aqueous binder include styrene butadiene rubber, carboxymethyl cellulose, or a combination thereof. Examples of the organic binder include polytetrafluoroethylene, polyvinylidene fluoride, or a combination thereof.

[0062] The solid electrolyte layer may be characterized, for example, by having a thickness of 1 to 100 μm. In other examples, the solid electrolyte layer may have a thickness of 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, 10 μm or more, 11 μm or more, 12 μm or more, 13 μm or more, 14 μm or more, 15 μm or more, 16 μm or more, 17 μm or more, 18 μm or more, 19 μm or more, or 20 μm or more, or 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, or 30 μm or less, but is not limited thereto.

[0063] The all-solid-state battery of the present invention may be characterized by further including, for example, a positive electrode.

[0064] The positive electrode may include, for example, a positive electrode active material layer. The positive electrode active material layer may be characterized by containing one or more positive electrode active materials selected from the group consisting of lithium transition metal oxides, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, and vanadium oxide. The lithium transition metal oxide may be lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganese oxide, or lithium iron phosphate, or a combination thereof. The positive electrode active material is not limited thereto, and any material used as a positive electrode active material in the art may be used. The positive electrode active materials may be used individually or in combination of two or more.

[0065] The lithium transition metal oxide is, for example, Li a A 1-b B b D2 (In the above formula, 0.90 ≤ a ≤ 1 and 0 ≤ b ≤ 0.5); Li a Ni1-b-c Co b B c O 2-α F2 (In the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c D α (In the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 ≤ α ≤ 2); Li a Ni 1-b-c Co b B c D α (In the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a E 1-b B b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2-b B b O 4-c D c (In the above formula, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​(In the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni 1-b-c Mn b B c O 2-α F2(In the above equation, 0.90≦a≦1, 0≦b≦0.5, 0≦c≦0.05, and 0<α<2);Li a Ni b E c G d O2(In the above formula, 0.90≦a≦1, 0≦b≦0.9, 0≦c≦0.5, 0.001≦d≦0.1); Li a Ni b Co c Mn d G e O2(In the above formula, 0.90≦a≦1, 0≦b≦0.9, 0≦c≦0.5, 0≦d≦0.5, 0.001≦e≦0.1);Li a NiG b O2 (In the above formula, 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3(0≦f≦2);Li (3-f)The compound may be represented by one of the following chemical formulas: Fe2(PO4)3 (0≦f≦2);LiFePO4. In such a compound, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F 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 is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. As the positive electrode active material, a compound with a coating layer attached to its surface may be used, or a mixture of the aforementioned compound and the compound with the coating layer attached may be used. The coating layer added to the surface of such a compound may contain, for example, a lithium-ion conductive oxide. The lithium-ion conductive oxide may be, for example, LiNbO3, Li4Ti5O 12 Examples include, but are not limited to, Li3PO4. The compound forming such a coating layer may be amorphous or crystalline. Methods for forming the coating layer may include, for example, spray coating or immersion, but can be selected without limitation as long as they do not adversely affect the physical properties of the positive electrode active material.

[0066] If the positive electrode active material includes nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, it may be possible to increase the capacity density of the all-solid-state battery and reduce the metal leaching of the positive electrode active material in the charged state. This may improve the cycle characteristics of the all-solid-state battery in the charged state.

[0067] The shape of the positive electrode active material may be, for example, a perfect sphere, an ellipsoid, or some other particle shape. The particle size of the positive electrode active material is not particularly limited and should be within a range applicable to the positive electrode active material of conventional all-solid-state secondary batteries. The content of the positive electrode active material in the positive electrode is also not particularly limited and should be within a range applicable to the positive electrode of conventional all-solid-state secondary batteries.

[0068] The positive electrode active material layer may further include, for example, a solid electrolyte, a binder, and / or a conductive material.

[0069] The solid electrolyte contained in the positive electrode active material layer may be, for example, one or more selected from the examples of solid electrolytes contained in the solid electrolyte layer, and may be the same as or different from the solid electrolyte contained in the solid electrolyte layer.

[0070] The solid electrolyte contained in the positive electrode active material layer may have a smaller average particle size than, for example, the solid electrolyte contained in the solid electrolyte layer. For example, the average particle size of the solid electrolyte contained in the positive electrode active material layer may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the average particle size of the solid electrolyte contained in the solid electrolyte layer.

[0071] The binder contained in the positive electrode active material layer may be, for example, one or more selected from the examples of binders contained in the solid electrolyte layer, and may be the same as or different from the binder contained in the solid electrolyte layer.

[0072] The conductive material contained in the positive electrode active material layer may be characterized by being one or more selected from the group consisting of, for example, graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; or carbon fiber.

[0073] The positive electrode active material layer may further contain additives such as fillers, coating agents, dispersants, and ion conductivity enhancers, and these additives can be used without limitation as long as they are known materials commonly used in electrodes for all-solid-state batteries.

[0074] The positive electrode may further include, for example, a positive electrode current collector. The positive electrode current collector can be made of a known metal that can be used as a current collector for all-solid-state batteries. The positive electrode current collector can be made of, for example, copper (Cu), nickel (Ni), aluminum (Al), vanadium (V), gold (Au), platinum (Pt), chromium (Cr), iron (Fe), zinc (Zn), indium (In), germanium (Ge), lithium (Li), magnesium (Mg), stainless steel, titanium (Ti), cobalt (Co), or an alloy thereof, in the form of a plate, mesh, or foil. The positive electrode current collector may be omitted in some cases.

[0075] In addition to the configuration described above, the positive electrode may further include known configurations that can be included in a positive electrode within an all-solid-state battery.

[0076] The all-solid-state battery of the present invention may be characterized by having a thickness of 120 to 180 μm, for example, based on a monocell containing one negative electrode and one positive electrode when fully discharged. In this specification, a monocell, as the smallest unit of a battery consisting of a positive electrode and a negative electrode in a single layer, may have a structure including a negative electrode, a solid electrolyte layer, and a positive electrode, as in the examples described later. In other examples, the all-solid-state battery of the present invention may have a thickness of 130 μm or more, or 140 μm or more, or 170 μm or less, or 160 μm or less, based on a monocell containing one negative electrode and one positive electrode when fully discharged.

[0077] The all-solid-state battery of the present invention may be characterized by having a thickness of 150 to 210 μm, for example, based on a monocell containing one negative electrode and one positive electrode when fully charged. In other examples, the all-solid-state battery of the present invention may be characterized by having a thickness of 160 μm or more, 170 μm or more, 200 μm or less, or 190 μm or less, based on a monocell containing one negative electrode and one positive electrode when fully charged.

[0078] The all-solid-state battery of the present invention may be characterized, for example, by having an initial discharge capacity of 185 mAh / g or more as a result of life characteristic evaluation. The initial discharge capacity may be measured, for example, by the method described in the evaluation example below. In other examples, the all-solid-state battery of the present invention may have an initial discharge capacity of 186 mAh / g or more, 187 mAh / g or more, 188 mAh / g or more, 189 mAh / g or more, 190 mAh / g or more, 191 mAh / g or more, 192 mAh / g or more, 193 mAh / g or more, or 194 mAh / g or more.

[0079] The all-solid-state battery of the present invention may have a capacity retention rate of 80% or more after 50 cycles. The capacity retention rate may be measured, for example, by the method described in the evaluation example later. In other examples, the all-solid-state battery of the present invention may have a capacity retention rate of 85% or more, 90% or more, 95% or more, 96% or more, 97% or more, or 98% or more after 50 cycles.

[0080] In the following, the present invention will be described in detail with reference to examples in order to specifically illustrate the disclosures of the present invention as described above and the intended functions and effects of the present invention. However, the examples may be modified into several different forms, and the scope of this specification should not be construed as being limited to these examples alone. It should be emphasized that the examples are provided to specifically illustrate the present invention to those skilled in the art.

[0081] Examples

[0082] (Negative electrode)

[0083] Silver (Ag) was deposited onto a SUS foil (10 μm thick) using an E-Beam Evaporator. As a result, a negative electrode was obtained in which a 250 nm thick silver (Ag) nanolayer was formed on the SUS foil.

[0084] (positive electrode)

[0085] LiNi 0.8 Co 0.15 Mn 0.05O2(NCM), Li6PS5Cl (an argyrodite-type crystalline material) as the solid electrolyte, polytetrafluoroethylene (Teflon® binder, DuPont) as the binder, and carbon nanofibers (CNF) as the conductive material were prepared. These materials were then mixed in a weight ratio of positive electrode active material:solid electrolyte:conductive material:binder = 83.8:14.8:0.2:1.2, and the mixture was formed into a large sheet to produce a positive electrode sheet. Subsequently, this positive electrode sheet was pressed onto a 10 μm thick aluminum foil positive electrode current collector to produce the positive electrode. The initial charge capacity of the positive electrode (charge capacity in the first cycle) was approximately 20 mAh at a charge of 4.25 V. The weight of the positive electrode was approximately 110 mg (approximately 203 mAh / g per active material weight).

[0086] (solid electrolyte layer)

[0087] The solid electrolyte layer used contained a solid electrolyte of Li6PS5Cl.

[0088] (All-solid-state battery)

[0089] A solid-state battery was fabricated by stacking a positive electrode, a solid electrolyte layer, and a negative electrode, and sealing them in a pouch under vacuum. The positive electrode current collector and the negative electrode current collector were made to protrude from the pouch to maintain the battery's vacuum. These protruding parts served as the positive and negative electrode terminals. Furthermore, this solid-state battery was subjected to hydrostatic pressure treatment at 500 MPa for 30 minutes. This hydrostatic pressure treatment significantly improved the battery's performance.

[0090] Comparative Example 1.

[0091] An all-solid-state battery was obtained using the same method as in the examples, except that during the negative electrode manufacturing process, aluminum (Al) was deposited onto the SUS foil instead of silver (Ag) to obtain a negative electrode in which a 250 nm thick aluminum (Al) nanolayer was formed on the SUS foil.

[0092] Comparative Example 2.

[0093] An all-solid-state battery was obtained using the same method as in the examples, except that during the negative electrode manufacturing process, Si3N4 was deposited onto the SUS foil instead of silver (Ag) to obtain a negative electrode in which a 250 nm thick silicon nitride (Si3N4) nanolayer was formed on the SUS foil.

[0094] Comparative Example 3.

[0095] An all-solid-state battery was obtained using the same method as in the examples, except that the negative electrode was manufactured as described below.

[0096] (Negative electrode)

[0097] 6 g of carbon black (average particle size 41 nm), 9.33 g of PVdF solution (6% solids), and 7.19 g of NMP solution were placed in a Thinky Mixer container and mixed 12 times for 3 minutes at 2000 rpm. Then, 5 g of NMP solution was added, and the mixture was mixed 5 times for 3 minutes at 2000 rpm to produce a slurry for the non-negative electrode coating layer. Subsequently, the slurry was coated onto a 10 μm thick SUS foil using a bar coater, dried in air at 80°C for 20 minutes, and then vacuum dried at 100°C for 12 hours. Through this process, a negative electrode was obtained in which a non-negative electrode coating layer with a thickness of 10.0 μm and a porosity of 67.1% was formed on the SUS foil.

[0098] Comparative Example 4.

[0099] An all-solid-state battery was obtained using the same method as in the example, except that an untreated SUS foil (10 μm thick) was used for the negative electrode.

[0100] Evaluation Example 1: SEM-EDS Analysis

[0101] After preparing a sample by cutting an arbitrary region of the negative electrode of the example into a 10mm*10mm size section, the silver (Ag) nanolayer surface of the sample was observed using a scanning electron microscope (SEM), and images like those in Figures 1 and 2 were obtained. Figure 1 is an image observed at a magnification of 1K, and Figure 2 is an image observed at a magnification of 5K.

[0102] On the other hand, the above sample was subjected to component analysis by energy-dispersive spectroscopy (EDS) under the following conditions, and the results were confirmed as shown in Figure 3.

[0103] (EDS analysis conditions)

[0104] -Acceleration voltage: 15kV

[0105] -Time: 1.5 minutes

[0106] Evaluation Example 2. Monocell Performance Evaluation

[0107] All-solid-state batteries (pouch-type monocells) in the examples and comparative examples were driven under the following charge / discharge conditions within an operating voltage range of 4.25V-3.0V and a driving temperature of 60°C. The cycle capacity and capacity retention rate were evaluated, and the results are shown in Table 1, Figure 4, and Figure 5 below.

[0108] Charging conditions: 0.33C, 4.25V CC / CV, 0.1C cut-off

[0109] Discharge conditions: 0.33C, 3.0V, CC

[0110] [Table 1]

Claims

1. A solid-state battery using lithium or a lithium alloy as the negative electrode active material, The all-solid-state battery includes a negative electrode current collector and a solid electrolyte layer. The negative electrode current collector and the solid electrolyte layer contain a silver (Ag) nanolayer, or Silver (Ag) nanoparticles are distributed between the negative electrode current collector and the solid electrolyte layer. An all-solid-state battery characterized in that amorphous carbon is not present between the negative electrode current collector and the solid electrolyte layer.

2. The all-solid-state battery according to claim 1, characterized in that, before charging after battery manufacturing, a silver (Ag) nanolayer is included between the negative electrode current collector and the solid electrolyte layer, and after charging, silver (Ag) nanoparticles are distributed between the negative electrode current collector and the solid electrolyte layer.

3. The all-solid-state battery according to claim 1, characterized in that the silver (Ag) nanolayer is a silver vapor-deposited layer.

4. The all-solid-state battery according to claim 1, characterized in that the thickness of the silver (Ag) nanolayer is 1000 nm or less.

5. The all-solid-state battery according to claim 1, characterized in that the average particle size of the silver (Ag) nanoparticles is 1000 nm or less.

6. Before charging after battery manufacturing, the thickness d of the negative electrode current collector １ Compared to the distance d between the surface of the negative electrode current collector and the solid electrolyte layer ２ ratio d ２ / d １ The all-solid-state battery according to claim 1, characterized in that the ratio is 0.001 to 0.

1.

7. When fully charged, the thickness d of the negative electrode current collector １ Compared to the distance d between the surface of the negative electrode current collector and the solid electrolyte layer ３ ratio d ３ / d １ The all-solid-state battery according to claim 1, characterized in that the ratio is 0.5 to 10.

8. When fully discharged, the thickness d of the negative electrode current collector １ compared to the distance d between the surface of the negative electrode current collector and the solid electrolyte layer ４ of the ratio d ４ / d １ is 0.01 or less, and the all-solid-state battery according to claim 1 is characterized thereby.

9. The all-solid-state battery according to claim 1, characterized in that the solid electrolyte layer contains a sulfide-based solid electrolyte.

10. The sulfide-based solid electrolyte is Li ２ S-P ２ S ５ -Li ２ O, Li ２ S-P ２ S ５ -Li ２ O-LiI, Li ２ S-LiBr-LiI-P ２ S ５ Li ２ S-SiS ２ Li ２ S-SiS ２ -LiI, Li ２ S-SiS ２ - LiBr, Li ２ S-SiS ２ -LiCl, Li ２ S-SiS ２ -B ２ S ３ -LiI, Li ２ S-SiS ２ -Li ３ PO ４ Li ２ S-SiS ２ -Li ｐ MO ｑ (p and q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, and In), Li ２ S-SiS ２ -P ２ S ５ -LiI, Li ２ S-P ２ S ５ Li ２ S-P ２ S ５ -LiX (X is a halogen element), Li ２ S-B ２ S ３ Li ２ S-P ２ S ５ -Z ｍ S ｎ (m and n are positive numbers, Z is one of Ge, Zn, or Ga), Li ２ S-GeS ２ Li ７－ｘ PS ６－ｘ Cl ｘ (0≦x≦2), Li ７－ｘ PS ６－ｘ Br ｘ (0 ≤ x ≤ 2), and Li ７－ｘ PS ６－ｘ I ｘ The all-solid-state battery according to claim 9, characterized by being one or more selected from the group including (0 ≤ x ≤ 2).

11. The all-solid-state battery according to claim 1, further comprising a positive electrode.

12. The all-solid-state battery according to claim 11, characterized in that, when fully discharged, the thickness of a monocell containing one negative electrode and one positive electrode is 120 to 180 μm.

13. The all-solid-state battery according to claim 11, characterized in that, when fully charged, the thickness is 150 to 210 μm based on a monocell containing one negative electrode and one positive electrode.

14. The all-solid-state battery according to claim 1, characterized in that, as a result of life characteristic evaluation, the initial discharge capacity is 185 mAh / g or more.

15. The all-solid-state battery according to claim 1, characterized in that the capacity retention rate after 50 cycles is 80% or more.

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