All-solid-state battery

Abstract

According to the present invention, an all-solid-state battery in which a lithium layer is formed during a charging process without the formation of a separate anode active material layer on an anode current collector in a battery manufacturing process is provided, the all-solid-state battery being capable of: further maximizing energy density without the inclusion of amorphous carbon between the anode current collector and a solid electrolyte layer, and preventing lithium dendrite from growing through gaps in the solid electrolyte layer according to the repetition of charging and discharging without the inclusion of amorphous carbon, thereby enabling the problem of shorting or capacity degradation to be solved and, furthermore, having excellent capacity retention during cycling.

Description

All-solid-state batteries

[0001] This application claims the benefit of priority from Republic of Korea Patent Application No. 2023-0162269, filed November 21, 2023, the entire disclosure of which is incorporated herein by reference. The present invention relates to an all-solid-state battery in which a lithium layer is formed during the charging process without forming a separate negative electrode active material layer on the negative electrode current collector during the battery manufacturing process.

[0002] Recent industrial demands have led to the development of all-solid-state batteries with high energy density and stability, and ongoing efforts are underway to further improve these properties. For example, research is underway into using lithium as an anode material to increase the energy density of all-solid-state batteries.

[0003] As a method of using lithium as an anode active material, a method of using lithium or a lithium alloy as an anode active material layer during the battery manufacturing process, or a method of forming a lithium layer during the charging process without forming a separate anode active material layer on the anode current collector during the battery manufacturing process have been proposed.

[0004] However, when lithium is used as an anode active material, lithium (metallic lithium) is deposited on the anode side during charging, and as the charging and discharging process is repeated, lithium dendrites grow through the gaps in the solid electrolyte layer, which causes a battery short circuit or a decrease in capacity, which is a problem.

[0005] Therefore, in order to commercialize the method of using lithium as an anode active material, it is necessary to improve the above problems.

[0006] The present invention is intended to solve the above problem, and in particular, in an all-solid-state battery in which a lithium layer is formed during a charging process without forming a separate negative electrode active material layer on a negative electrode collector during a battery manufacturing process, the energy density can be further maximized by not including amorphous carbon between the negative electrode collector and the solid electrolyte layer, and even without including amorphous carbon, the growth of lithium dendrites through gaps in the solid electrolyte layer can be prevented as the charge and discharge process is repeated, thereby solving the problem of short circuits or capacity reduction due to this, and further providing an all-solid-state battery with excellent capacity retention according to cycles.

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

[0008] In one embodiment, the battery may be characterized in that, before charging after manufacturing the battery, 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 being a silver deposition layer.

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

[0011] In one embodiment, the silver (Ag) nanoparticles may be characterized by having an average particle diameter of 1000 nm or less.

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

[0013] In one embodiment, the ratio (d3 / d1) of the distance (d3) between the surface of the negative electrode collector and the solid electrolyte layer to the thickness (d1) of the negative electrode collector when fully charged may be 0.5 to 10.

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

[0015] In one embodiment, the solid electrolyte layer may be characterized by including 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 p MO q (p, 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, n are positive numbers), Z is one of Ge, Zn or Ga, L i2 S-GeS2, Li 7-x PS 6-x Clx (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 at least one selected from the group including (0≤x≤2).

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

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

[0019] In one embodiment, the all-solid-state battery of the present invention may be characterized by a thickness of 150 to 210 μm based on a monocell comprising 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 an initial discharge capacity of 185 mAh / g or more as a result of a 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.

[0022] According to the present invention, in an all-solid-state battery in which a lithium layer is formed during a charging process without forming a separate negative electrode active material layer on a negative electrode collector during a battery manufacturing process, the energy density can be further maximized by not including amorphous carbon between the negative electrode collector and the solid electrolyte layer, and even without including amorphous carbon, the growth of lithium dendrites through gaps in the solid electrolyte layer can be prevented as the charge and discharge process is repeated, thereby solving the problem of short circuits or capacity reduction due to this, and furthermore, an all-solid-state battery having excellent capacity retention according to cycles can be provided.

[0023] Figure 1 is an image of the surface of a silver nanolayer taken using a scanning electron microscope (magnification: 1K).

[0024] Figure 2 is an image of the surface of a silver nanolayer taken using a scanning electron microscope (magnification: 5K).

[0025] Figure 3 is an image of the results of EDS analysis on the example cathode.

[0026] Figure 4 is a graph showing the capacity according to the cycle of the monocells of the examples and comparative examples.

[0027] Figure 5 is a graph showing the capacity retention rate according to the cycle of the monocells of the examples and comparative examples.

[0028] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0029] Accordingly, the configuration of the embodiments described in this specification is only one of the most preferred embodiments of the present invention and does not represent all of the technical ideas of the present invention, so it should be understood that various equivalents and modified examples that can replace them may exist at the time of filing this application.

[0030] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0031] When a part in this specification is said to “comprise” a certain component, this does not exclude other components unless specifically stated to the contrary, but rather means that other components may be included. Thus, for example, a composition comprising compound A may include compounds other than A. However, the term “comprise” also encompasses, as a specific embodiment thereof, the more restrictive meanings of “consisting essentially / essentially of” and “consisting of,” so that, for example, “a composition comprising compound A” may also consist (essentially / essentially) of compound A.

[0032] In this connection, it should be understood that terms such as “have” or “have” as used herein are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0033] When it is said in this specification that any layer is located “on” or “between” any other layer, this includes not only cases where any layer is in contact with any other layer, but also cases where another layer or material, etc., exists between the two layers.

[0034] Where an amount, concentration, or other value or parameter is given herein as a range, a preferred range, or an enumeration of an upper preferred value and a lower preferred value, this should be understood to specifically disclose any range that can be formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the range is separately disclosed. Where a range of numerical values ​​is recited herein, unless otherwise stated, e.g., there is no limiting term such as greater than, less than, etc., the range is intended to include the endpoint values ​​and all integers and fractions within the range. The scope of the present invention is not intended to be limited to the specific values ​​recited when defining a range.

[0035] Among the properties mentioned in this specification, if the measurement temperature affects the property, the property is measured at room temperature unless otherwise specified. The term "room temperature" refers to the natural temperature without heating or cooling, and may mean, for example, any temperature within the range of about 10°C to 30°C, or about 23°C or about 25°C. In addition, unless otherwise specified, the unit of temperature in this specification is ℃.

[0036] In addition, among the properties mentioned in this specification, if the measurement pressure affects the property, the property is measured at normal pressure, i.e., atmospheric pressure (approximately 1 atm), unless otherwise specified.

[0037] A first aspect of the present invention relates to an all-solid-state battery using lithium or a lithium alloy as a negative electrode active material.

[0038] The above-mentioned all-solid-state battery may be characterized by including, for example, a negative electrode current collector and a solid electrolyte layer, and 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 including amorphous carbon between the negative electrode current collector and the solid electrolyte layer.

[0039] The present invention may relate to an all-solid-state battery that uses lithium or a lithium alloy as an anode active material, and in particular, to an all-solid-state battery that forms a lithium layer during a charging process without forming a separate anode active material layer on a cathode current collector during the battery manufacturing process.

[0040] The lithium layer may include, for example, lithium or a lithium alloy.

[0041] In an all-solid-state battery that forms a lithium layer during the charging process without forming a separate negative active material layer on the negative electrode collector during the battery manufacturing process, a method has been proposed to introduce a non-anode coating layer containing amorphous carbon (e.g., at least one selected from the group consisting of carbon black, acetylene black, furnace black, Ketjen black, and graphene) as an essential component between the negative electrode collector and the solid electrolyte layer in order to solve problems such as the growth of lithium dendrites formed during the charge and discharge process and the occurrence of short circuits or capacity reduction due to these dendrites. Although the clear mechanism has not been identified, it is expected that the amorphous carbon can control the growth of lithium dendrites by allowing lithium ions to be uniformly deposited between the non-anode coating layer and the negative electrode collector during the charging process, and in addition, the non-anode coating layer containing the amorphous carbon can serve as a protective layer to control short circuits, etc. Therefore, amorphous carbon and / or a non-anode coating layer containing the same has been conventionally introduced between the solid electrolyte layer and the negative electrode collector. In this specification, the “non-cathode coating layer” means a coating layer formed between the negative current collector and the solid electrolyte layer in an all-solid-state battery in which lithium is absorbed into the non-cathode coating layer during charging, lithium is deposited between the negative current collector and the non-cathode coating layer after the charge capacity of the non-cathode coating layer is exceeded, and a lithium layer is formed, and lithium in the non-cathode coating layer and the lithium layer is ionized and moves toward the positive electrode during discharge.

[0042] However, since the cathode-free coating layer also has a thickness of approximately 1 to 20 ㎛, in order to further maximize energy density and improve cycle characteristics, etc., it was necessary to further reduce the thickness of the cathode-free coating layer or to provide a new solution that can achieve the above-mentioned purpose without introducing the cathode-free coating layer.

[0043] The present invention has confirmed that by including a silver (Ag) nano-layer between a negative electrode current collector and a solid electrolyte layer; or by distributing silver (Ag) nano-particles between the negative electrode current collector and the solid electrolyte layer, amorphous carbon can be omitted between the negative electrode current collector and the solid electrolyte layer, thereby further maximizing energy density, and that lithium dendrites can be prevented from growing through gaps in the solid electrolyte layer as charge and discharge processes are repeated without including amorphous carbon, thereby solving the problem of short circuits or capacity reduction due to this, and further providing an all-solid-state battery with excellent capacity retention according to cycles.

[0044] The present invention may include, for example, a silver (Ag) nanolayer between the negative electrode current collector and the solid electrolyte layer.

[0045] The above silver (Ag) nanolayer may be characterized as, for example, a silver deposition layer. The silver deposition layer may be formed, for example, using a vacuum deposition method using an electron beam (E-beam evaporator). The silver nanolayer may be characterized as not containing any other material other than silver (Ag). The silver nanolayer may not contain, for example, a binder, and thus, an increase in battery resistance may be controlled.

[0046] The thickness of the above silver (Ag) nanolayer may be characterized as being, for example, 1000 nm or less. The thickness of the above silver (Ag) nanolayer may be measured, for example, by SEM, and may mean an average thickness, a minimum thickness, and / or a maximum thickness. The thickness of the above silver (Ag) nanolayer is, in other examples, 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 The thickness may be 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 having a thickness range as described above, and can form a uniform lithium layer during the charging process.

[0047] The all-solid-state battery of the present invention may have a form in which, for example, the silver nano-layer included between the negative electrode collector and the solid electrolyte layer is rearranged into silver nano-particles during the battery charging process, and the silver nano-particles are distributed between the negative electrode collector and the solid electrolyte layer. The rearrangement of the silver nano-layer into silver nano-particles is irreversible, and the form in which the silver nano-particles are distributed between the negative electrode collector and the solid electrolyte layer can be maintained after a single battery charge. However, this does not mean that the presence of the silver nano-layer in some portion between the negative electrode collector and the solid electrolyte layer is completely ruled out even after charging.

[0048] That is, the all-solid-state battery of the present invention may include a silver (Ag) nano-layer between the negative electrode current collector and the solid electrolyte layer before charging after manufacturing the battery, and may have a form in which silver (Ag) nano-particles are distributed between the negative electrode current collector and the solid electrolyte layer after charging.

[0049] In the present 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 particles and / or secondary particles, or more preferably, from the viewpoint of controlling the growth of lithium dendrites, at least a part or all of the silver nanoparticles are present in a state of being embedded on one surface of the solid electrolyte layer (for example, it may mean a surface facing the negative electrode current collector among both surfaces of the solid electrolyte layer). The silver nanoparticles may be uniformly or non-uniformly distributed 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 are uniformly distributed between the negative electrode current collector and the solid electrolyte layer.

[0050] The average particle diameter of the above silver (Ag) nanoparticles may be, for example, 1000 nm or less. The average particle diameter of the silver nanoparticles may be measured by SEM. The average particle diameter of the silver nanoparticles may refer to the average particle diameter of primary particles and / or the average particle diameter of secondary particles. In other examples, the average particle diameter 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 diameter 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 lithium dendrite formation by distributing silver nanoparticles having the above-described average particle diameter between the negative electrode current collector and the solid electrolyte layer after battery charging.

[0051] The all-solid-state battery of the present invention may be characterized, for example, by forming a lithium layer between the negative electrode current collector and the solid electrolyte layer during the charging process. It is thought that the all-solid-state battery of the present invention, through the combination of the above configurations, can suppress the growth of lithium dendrites and thereby prevent a short circuit of the battery by allowing lithium to react with the silver nano-layer and / or silver nanoparticles present between the negative electrode current collector and the solid electrolyte layer to form a lithium alloy during the process of lithium precipitation between the negative electrode current collector and the solid electrolyte layer during charging. Meanwhile, in the initial state of the all-solid-state battery (the state before charging after battery manufacturing) or the state after discharge, the region between the negative electrode current collector and the solid electrolyte layer may be a lithium-free region that does not contain lithium.

[0052] The all-solid-state battery of the present invention may be characterized in that, for example, before charging after manufacturing the battery, the ratio (d2 / d1) of the distance (d2) between the surface of the negative current collector and the solid electrolyte layer to the thickness (d1) of the negative current collector is 0.001 to 0.1. In the present specification, the “distance between the surface of the negative current collector and the solid electrolyte layer” may mean, for example, the distance from the surface of the negative current collector closer to the solid electrolyte layer to the surface of the solid electrolyte layer closer to the negative current collector among both surfaces of the negative current collector. In another example, the all-solid-state battery of the present invention may be characterized in that, before charging after manufacturing the battery, 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 is 0.005 or more, 0.01 or more, 0.015 or more, or 0.02 or more, or 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.

[0053] The all-solid-state battery of the present invention may be characterized, for example, by a ratio (d3 / d1) of the distance (d3) between the surface of the negative current collector and the solid electrolyte layer to the thickness (d1) of the negative current collector when fully charged being 0.5 to 10. The all-solid-state battery of the present invention does not include amorphous carbon, but instead distributes silver nanoparticles between the negative current collector and the solid electrolyte layer when fully charged, thereby further improving energy density while suppressing the growth of lithium dendrites or occurrence of short circuits. In another example, the all-solid-state battery of the present invention may be characterized by a ratio (d3 / d1) of the distance (d3) between the surface of the negative current collector and the solid electrolyte layer to the thickness (d1) of the negative current collector when fully charged being 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.

[0054] When an all-solid-state battery is completely discharged, the lithium layer formed between the negative electrode collector and the solid electrolyte layer during the charging process can be ionized into lithium ions and move toward the positive electrode side, which will be described later. When completely discharged, the area between the negative electrode collector and the solid electrolyte layer of the all-solid-state battery becomes a lithium-free region. Therefore, when an all-solid-state battery is completely discharged, the distance between the surface of the negative electrode collector and the solid electrolyte layer can be further reduced compared to when fully charged.

[0055] The all-solid-state battery of the present invention may be characterized in that, for example, a ratio (d4 / d1) of the distance (d4) between the surface of the negative current collector and the solid electrolyte layer to the thickness (d1) of the negative current collector when completely discharged is 0.01 or less. In another example, the all-solid-state battery of the present invention may have a ratio (d4 / d1) of the distance (d4) between the surface of the negative current collector and the solid electrolyte layer to the thickness (d1) of the negative current collector when completely discharged is 0.005 or less or 0.001 or less, and since the area between the solid electrolyte layer and the negative current collector is a lithium-free region when completely discharged, and the silver nanoparticles are distributed in a form in which they are embedded in the solid electrolyte layer, the d4 / d1 may be substantially 0.

[0056] As the negative electrode current collector, a known metal that can be used as a current collector of an all-solid-state battery can be used. The negative electrode current collector can be, for example, a material that does not form an alloy or compound with lithium. The negative electrode current collector can be, for example, selected from the group consisting of 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, and any material used as an electrode current collector in the relevant technical field can be used as long as it does not impede the purpose of the present invention. The negative electrode current collector can be composed of one type of the above-described metal, or can be composed of an alloy or a coating material of two or more types of metals. The negative electrode current collector can be, for example, in the form of a plate, mesh, or foil, but is not limited thereto.

[0057] The solid electrolyte layer may include, for example, one or more of a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte. From the perspective of achieving excellent ionic conductivity and high energy density, the solid electrolyte layer may include, but is not limited to, a sulfide-based solid electrolyte.

[0058] The above sulfide-based solid electrolytes include, 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, Li2S-SiS2- Li p MO q(p, 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, n are positive numbers), Z is one of Ge, Zn or Ga, L i2 S-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 at least one selected from the group including (0≤x≤2).

[0059] A sulfide-based solid electrolyte can be manufactured by treating starting materials such as Li2S and P2S5 by a melting rapid cooling method or a mechanical milling method. In addition, a heat treatment can be performed after such treatment. The solid electrolyte can be in an amorphous, crystalline, or mixed state. In the present invention, the sulfide-based solid electrolyte can be, for example, one that includes sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the above-mentioned sulfide-based solid electrolyte materials.

[0060] The above 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 xIt may be an argyrodite-type compound including at least one selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0061] The density of the above-mentioned argyrodite-type solid electrolyte may be, for example, 1.5 to 2.0 g / cc. Since the above-mentioned argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state secondary battery is reduced, and penetration of the solid electrolyte by Li can be effectively suppressed.

[0062] The elastic modulus of the above sulfide-based solid electrolyte may be, for example, 15 to 45 GPa.

[0063] The above oxide-based solid electrolyte may be, for example, at least one 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 may be Li7La3Zr2O 12 , the above Li7La3Zr2O 12 Doped with elements such as Al, Y, Ga, Ta, Nb, etc. instead of Li, or the above Li7La3Zr2O 12 Ga in the place of Li, La, and Zr elements +3 -Sc +3 Multi-doped ones, etc. are used; those coated with materials such as Al2CO3, Ge, ZnO, etc. on the surface are used; Na 1+x Zr2Si2P 3-X O 12 (0≤x≤3), LiM2(PO4)3(M = Zr, Ti, Ge), Li 1+x Al x M2-x (PO4)3(0 <x<2, M=Zr, Ti, Ge) 또는 상기 Al 대신 Y, La, Sc 등의 산화수가 +3인 원자를 도핑하거나 Sr, Mg, Ca 등의 산화수가 +2인 원자를 도핑한 것 등이 사용되거나; xLi3AO4-(1-x) Li4BO4(A: P, As, V 등, B: Si, Ge, Ti 등) 또는 이에 대해 Li3BO3등을 첨가한 것 등; 또는 Li 3x La 2 / 3-x □ 1 / 3- 2x TiO3(LLTO, 0 <x<0.16, □는 공공(vacancy)), La 0.57-2x / 3 Sr x Li 0.3 TiO3, etc. can be used, but are not limited thereto.

[0064] The above halide-based solid electrolytes include Li2ZrCl6, Li 2+x Zr 1-x M x Cl6(M= Fe, Cr, V) and Na2ZrCl6 can be used, but are not limited thereto.

[0065] The solid electrolyte layer may further include, for example, a binder. The binder may be, for example, an aqueous binder, an organic binder, or a combination thereof. The binder may be, for example, a polymer including polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinylidene fluoride, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene, fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylate styrene-butadiene rubber, epoxy resin, nylon, or a combination thereof. The aqueous binder may be, for example, styrene butadiene rubber, carboxymethyl cellulose, or a combination thereof. As the organic binder, for example, polytetrafluoroethylene, polyvinylidene fluoride, or a combination thereof can be used.

[0066] The solid electrolyte layer may be characterized by, for example, a thickness of 1 to 100 μm. In other examples, the solid electrolyte layer may have a thickness of, but is not limited to, 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.

[0067] The all-solid-state battery of the present invention may be characterized, for example, by further including a positive electrode.

[0068] The positive electrode may include, for example, a positive electrode active material layer. The positive electrode active material layer may be characterized by including, for example, at least one positive electrode active material selected from the group consisting of lithium transition metal oxide, 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 manganate, or lithium iron phosphate, or a combination thereof. The positive electrode active material is not limited thereto, and any positive electrode active material used in the art may be used. The positive electrode active materials may be used alone or in combination of two or more.

[0069] The above 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 Ni 1-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 Bb 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 B c O 2-α F α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a CoG b O2 (in the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a MnG b O2 (in the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a Mn2G b O4 (in the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a Ni 1-b-c Mn b B c O 2-α F 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 Mn 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 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 eO2 (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, 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3- f) J2(PO4)3(0≤f≤2); Li (3-f) Fe2(PO4)3(0≤f≤2); It may be a compound represented by any one of the chemical formulas of LiFePO4. In this compound, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, 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 may be V, Cr, Mn, Co, Ni, Cu, or a combination thereof. A compound having a coating layer added to the surface of this compound may be used as the positive electrode active material, or a mixture of the above-mentioned compound and the compound having a coating layer added may be used. The coating layer added to the surface of such compounds may contain, for example, a lithium ion conductive oxide. The lithium ion conductive oxide may be, for example, LiNbO3, Li4Ti5O. 12 , Li3PO4, etc., but are not limited thereto. The compound forming the coating layer may be amorphous or crystalline. The method for forming the coating layer may include, for example, spray coating, dipping, etc., but may be selected without limitation within a range that does not adversely affect the properties of the positive electrode active material.

[0070] When the above-mentioned cathode active material is a ternary lithium transition metal oxide such as NCA or NCM and contains nickel (Ni), it may be possible to increase the capacity density of the all-solid-state battery and reduce metal dissolution of the cathode active material in a charged state. Accordingly, the cycle characteristics of the all-solid-state battery in a charged state may be improved.

[0071] The shape of the above-mentioned positive electrode active material may be, for example, a spherical particle shape, such as an elliptical sphere. The particle size of the positive electrode active material is not particularly limited and may be within the range applicable to positive electrode active materials of conventional all-solid-state secondary batteries. The content of the positive electrode active material is also not particularly limited and may be within the range applicable to positive electrodes of conventional all-solid-state secondary batteries.

[0072] The above positive electrode active material layer may further include, for example, a solid electrolyte, a binder, and / or a conductive material.

[0073] The solid electrolyte included in the above positive electrode active material layer may be, for example, one or more types selected from examples of solid electrolytes included in the solid electrolyte layer, and may be the same as or different from the solid electrolyte included in the solid electrolyte layer.

[0074] The solid electrolyte included in the positive electrode active material layer may have, for example, a smaller average particle size than the solid electrolyte included in the solid electrolyte layer. For example, the average particle size of the solid electrolyte included 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 included in the solid electrolyte layer.

[0075] The binder included in the above positive electrode active material layer may be, for example, one or more types selected from examples of binders included in the solid electrolyte layer, and may be the same as or different from the binder included in the solid electrolyte layer.

[0076] The conductive material included in the above-described positive electrode active material layer may be characterized by being at least one 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.

[0077] In addition to the above-mentioned positive electrode active material layer, the positive electrode active material layer may further include additives such as fillers, coating agents, dispersants, and ion conductive assistants, and these additives may be used without limitation as long as they are known materials generally used in electrodes of all-solid-state batteries.

[0078] The above-described positive electrode may further include, for example, a positive electrode current collector. The positive electrode current collector may be a known metal usable as a current collector of an all-solid-state battery. The positive electrode current collector may be, for example, a plate, mesh, or foil made of 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. The positive electrode current collector may be omitted in some cases.

[0079] In addition to the aforementioned configuration, the above-mentioned positive electrode may further include known configurations that can be included in the positive electrode in an all-solid-state battery.

[0080] The all-solid-state battery of the present invention may be characterized by a thickness of 120 to 180 μm, for example, based on a monocell including one negative electrode and one positive electrode when fully discharged. The term "monocell" refers to the smallest unit of a battery in which the positive electrode and the negative electrode are formed as a single layer, and in the present specification, the monocell may have a structure including a negative electrode, a solid electrolyte layer, and a positive electrode as in the examples described below. In another example, the all-solid-state battery of the present invention may have a thickness of 130 μm or more, 140 μm or more, or 170 μm or less, or 160 μm or less, based on a monocell including one negative electrode and one positive electrode when fully discharged.

[0081] The all-solid-state battery of the present invention may be characterized by, for example, a thickness of 150 to 210 μm based on a monocell comprising one negative electrode and one positive electrode when fully charged. In another example, the all-solid-state battery of the present invention may be characterized by a thickness of 160 μm or more, 170 μm or more, or 200 μm or less, or 190 μm or less based on a monocell comprising one negative electrode and one positive electrode when fully charged.

[0082] The all-solid-state battery of the present invention may be characterized, for example, by an initial discharge capacity of 185 mAh / g or more as a result of a life characteristic evaluation. The initial discharge capacity may be measured, for example, in a method according to an evaluation example described 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.

[0083] The all-solid-state battery of the present invention may have, for example, a capacity retention rate of 80% or more after 50 cycles. The capacity retention rate may be measured, for example, according to a method according to the evaluation example described below. 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.

[0084] Hereinafter, the present invention will be described in detail by way of examples to specifically illustrate the disclosure of the present invention and its intended functions and effects, as described above. However, these examples may be modified in various ways, and the scope of this specification is not construed as being limited to these examples. It is emphasized that these examples are provided to represent the present invention and to provide a more concrete explanation to those skilled in the art.

[0085] Example.

[0086] (cathode)

[0087] Silver (Ag) was deposited on a SUS foil (thickness 10 μm) using an E-Beam Evaporator. As a result, a cathode with a silver (Ag) nanolayer having a thickness of 250 nm was obtained on the SUS foil.

[0088] (anode)

[0089] LiNi as positive electrode active material 0.8 Co 0.15 Mn 0.05O2(NCM), Li6PS5Cl as a solid electrolyte, an argyrodite-type crystal, polytetrafluoroethylene (Teflon binder, DuPont) as a binder, and carbon nanofibers (CNF) as a conductive material were prepared. Then, these materials were 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 shape to produce a positive electrode sheet. Then, this positive electrode sheet was pressed onto a 10-μm-thick aluminum foil positive electrode collector to produce a positive electrode. The initial charge capacity (charge capacity at the first cycle) of the positive electrode was approximately 20 mAh at 4.25 V charge. The positive electrode weight was approximately 110 mg (approximately 203 mAh / g per active material weight).

[0090] (solid electrolyte layer)

[0091] The solid electrolyte layer used was one containing Li6PS5Cl solid electrolyte.

[0092] (all-solid-state battery)

[0093] An all-solid-state battery was fabricated by stacking a positive electrode, a solid electrolyte layer, and a negative electrode and sealing them in a vacuum pouch. Each portion of the positive and negative current collectors were allowed to protrude from the pouch to maintain the battery's vacuum. These protrusions served as the positive and negative terminals. Furthermore, the all-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.

[0094] Comparative Example 1.

[0095] An all-solid-state battery was obtained in the same manner as in the example, except that aluminum (Al) was deposited on the SUS foil instead of silver (Ag) during the manufacture of the cathode, thereby obtaining a cathode in which an aluminum (Al) nanolayer with a thickness of 250 nm was formed on the SUS foil.

[0096] Comparative Example 2.

[0097] An all-solid-state battery was obtained in the same manner as in the example, except that when manufacturing the cathode, Si3N4 was deposited on the SUS foil instead of silver (Ag), thereby obtaining a cathode in which a silicon nitride (Si3N4) nanolayer with a thickness of 250 nm was formed on the SUS foil.

[0098] Comparative Example 3.

[0099] An all-solid-state battery was obtained in the same manner as in the example, except that the negative electrode was manufactured as follows.

[0100] (cathode)

[0101] 6 g of carbon black (average particle size: 41 nm), 9.33 g of PVdF solution (6% solid content), 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 additionally added, and mixing was performed 5 times for 3 minutes at 2000 rpm to prepare a cathode-free coating layer slurry. Next, the slurry was coated on a SUS foil having a thickness of 10 μm using a bar coater, dried in air at 80°C for 20 minutes, and then vacuum-dried at 100°C for 12 hours. As a result, a cathode having a cathode-free coating layer having a thickness of 10.0 μm and a porosity of 67.1% was obtained on the SUS foil.

[0102] Comparative Example 4.

[0103] An all-solid-state battery was obtained in the same manner as in the example, except that an untreated SUS foil (thickness 10 μm) was used as the cathode.

[0104] Evaluation Example 1. SEM-EDS Analysis

[0105] After preparing a sample by cutting an arbitrary area of ​​the cathode of the example into a size of 10 mm x 10 mm, the silver (Ag) nanolayer surface of the sample was observed using a scanning electron microscope (SEM) to obtain images as shown in Figs. 1 and 2. Fig. 1 is an image observed at 1K magnification, and Fig. 2 is an image observed at 5K magnification.

[0106] Meanwhile, the component analysis of the above sample was performed using energy dispersive spectroscopy (EDS) under the following conditions, and the results were confirmed as shown in Fig. 3.

[0107] (EDS analysis conditions)

[0108] -Acceleration voltage: 15 kV

[0109] -Time: 1.5 minutes

[0110] Evaluation Example 2. Monocell Performance Evaluation

[0111] The all-solid-state batteries (pouch-type monocells) of the examples and comparative examples were operated under the following charge and discharge conditions at an operating voltage range of 4.25 V to 3.0 V and an operating temperature of 60°C to evaluate the capacity and capacity retention rate according to the cycle, and the results are shown in Table 1, Figures 4 and 5 below.

[0112] Charging conditions: 0.33C, 4.25V CC / CV, 0.1C cut-off

[0113] Discharge conditions: 0.33C, 3.0V, CC

[0114]

Claims

1. In an all-solid-state battery using lithium or a lithium alloy as an anode active material, The above all-solid-state battery includes a negative electrode collector and a solid electrolyte layer, A silver (Ag) nanolayer is included 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, An all-solid-state battery, characterized in that it does not contain amorphous carbon between the negative electrode collector and the solid electrolyte layer.

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

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

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

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

6. In the first paragraph, before charging after manufacturing the battery, the thickness (d) of the negative electrode current collector 1 ) the distance (d) between the surface of the negative electrode collector and the solid electrolyte layer 2 ) of the ratio(d) 2 / d 1 ) is 0.001 to 0.

1.

7. In the first paragraph, the thickness (d) of the negative electrode current collector when fully charged 1 ) the distance (d) between the surface of the negative electrode collector and the solid electrolyte layer 3 ) of the ratio(d) 3 / d 1 ) is 0.5 to 10.

8. In the first paragraph, the thickness (d) of the negative electrode current collector when completely discharged 1 ) the distance (d) between the surface of the negative electrode collector and the solid electrolyte layer 4 ) of the ratio(d) 4 / d 1 ) is 0.01 or less.

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

10. In the 9th paragraph, the sulfide-based solid electrolyte is Li 2 SP 2 S 5 -Li 2 O, Li 2 SP 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, 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 SP 2 S 5 , Li 2 SP 2 S 5 -LiX (X is a halogen element), Li 2 SB 2 S 3 , Li 2 SP 2 S 5 -Z m S n (m, n are positive numbers), Z is one of Ge, Zn or Ga, L i2 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 An all-solid-state battery, characterized in that it comprises at least one selected from the group comprising (0≤x≤2).

11. An all-solid-state battery according to claim 1, characterized in that it further comprises a positive electrode.

12. An all-solid-state battery according to claim 11, characterized in that the thickness is 120 to 180 ㎛ based on a monocell including one negative electrode and one positive electrode when completely discharged.

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

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

15. An all-solid-state battery, characterized in that the capacity retention rate after 50 cycles is 80% or more in the first paragraph.

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