All-solid-state battery and method for manufacturing same

Abstract

The present disclosure relates to an all-solid-state battery and can provide an all-solid-state battery comprising a cathode, a solid electrolyte layer, an anodeless coating layer, and an anode current collector, and a manufacturing method therefor, wherein the anodeless coating layer includes amorphous carbon and silver nanoparticles, and when the anode-free coating layer is divided in the thickness direction into two equal parts, referred to as a first region and a second region in order from the side closer to the anode current collector, the ratio (C2 / C1) of the silver nanoparticle content (C2) in the second region to the silver nanoparticle content (C1) in the first region falls within the range of 0.4 to 2 after charging / discharging. This configuration ensures excellent reactivity between silver nanoparticles and lithium ions, and high lithium ion conductivity. Even after charge and discharge cycles, the distribution characteristics of silver nanoparticles remain excellent, contributing to the uniformity of internal resistance in the battery and effectively regulating lithium dendrite growth. Accordingly, the all-solid-state battery of the present invention has an excellent capacity retention rate, particularly, an excellent capacity retention rate at a high rate, and also exhibits excellent lifespan characteristics.

Description

All-solid-state battery and method for manufacturing the same

[0001] This application claims the benefit of priority to Republic of Korea Patent Application No. 2024-0025711, filed February 22, 2024, the entire disclosure of which is incorporated herein by reference. The present invention relates to an all-solid-state battery using lithium or a lithium alloy as an anode active material and a method for manufacturing the same.

[0002] Recently, research has been conducted on using lithium as an anode active material to increase the energy density of all-solid-state batteries. Proposed methods include using lithium or a lithium alloy as an anode active material layer during battery manufacturing, or forming a lithium layer during the charging process without forming a separate anode active material layer on the anode current collector during battery manufacturing.

[0003] 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.

[0004] Therefore, in order to commercialize the method of using lithium as an anode active material, it is necessary to improve the above problems.

[0005] The present invention is intended to solve the above problems, and provides an all-solid-state battery and a method for manufacturing the same, in which the non-cathode coating layer includes anisotropic silver nanoparticles, thereby exhibiting excellent reactivity between silver nanoparticles and lithium ions and excellent lithium ion conductivity, and the distribution characteristics of the silver nanoparticles are excellent even after charge and discharge, thereby enabling uniformity of resistance distribution within the battery and effectively controlling lithium dendrite growth. Accordingly, the all-solid-state battery of the present invention can exhibit excellent capacity retention, particularly excellent capacity retention at high rates, and excellent lifespan characteristics.

[0006] The present invention relates to an all-solid-state battery using lithium or a lithium alloy as an anode active material, comprising a cathode, a solid electrolyte layer, a non-anode coating layer, and a cathode current collector, wherein the non-anode coating layer comprises amorphous carbon and silver nanoparticles, and when the non-anode coating layer is divided into two parts in the thickness direction and sequentially referred to as a first section and a second section starting from a section closer to the anode current collector, the ratio (C2 / C1) of the content of silver nanoparticles (C1) included in the first section to the content of silver nanoparticles (C2) included in the second section after charge and discharge is within a range of 0.4 to 2.

[0007] In one embodiment, the all-solid-state battery of the present invention may be characterized in that, when the non-anode coating layer is divided into three parts in the thickness direction and sequentially divided into a first section, a second section, and a third section from a section close to the anode current collector, a ratio of the sum (C2'+C3') of the contents of silver nanoparticles included in the second section and the third section to the content (C1') of silver nanoparticles included in the first section after charge and discharge ((C2'+C3') / C1') is within a range of 0.4 to 5.

[0008] In one embodiment, the silver nanoparticles may be characterized as being anisotropic.

[0009] In one embodiment, the silver nanoparticles may be characterized in that the maximum difference between the (200) plane grain size, the (220) plane grain size, and the (311) plane grain size is 1.5 nm or more. In one embodiment, the silver nanoparticles may have a BET specific surface area of ​​6 m 2 / g or less.

[0010] In one embodiment, the silver nanoparticles may be characterized by having an average pore size of 40 nm or more.

[0011] In one embodiment, the total pore volume of the silver nanoparticles is 0.065 cm 3 / g or more can be characterized.

[0012] In one embodiment, the amorphous carbon may be characterized by being at least one selected from the group consisting of carbon black, acetylene black, furnace black, Ketjen black, and graphene.

[0013] In one embodiment, the silver nanoparticles may be included in an amount of 10 to 50 parts by weight relative to 100 parts by weight of amorphous carbon.

[0014] In one embodiment, the cathode-free coating layer may be characterized by further including a binder.

[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 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 at least one selected from (0≤x≤2).

[0017] In one embodiment, the all-solid-state battery of the present invention may be characterized by a 1.0C capacity retention rate of 88% or more compared to the 0.1C capacity.

[0018] The present invention also relates to a method for manufacturing an all-solid-state battery using lithium or a lithium alloy as an anode active material, wherein the method for manufacturing an all-solid-state battery includes a step of forming a non-anode coating layer on an anode current collector, and the step of forming a non-anode coating layer on the anode current collector includes a step of applying a composition for forming a non-anode coating layer comprising amorphous carbon and silver nanoparticles on the anode current collector; and a step of drying the applied composition for forming a non-anode coating layer to form a non-anode coating layer, wherein when the non-anode coating layer is divided into two parts in the thickness direction and sequentially referred to as a first section and a second section starting from a section closer to the anode current collector, the ratio (C2 / C1) of the content of silver nanoparticles (C1) included in the first section to the content of silver nanoparticles (C2) included in the second section after charge and discharge is within a range of 0.4 to 2.

[0019] In one embodiment, the silver nanoparticles may be characterized as being anisotropic.

[0020] The present invention is intended to solve the above problems, and provides an all-solid-state battery that includes anisotropic silver nanoparticles, thereby exhibiting excellent reactivity between silver nanoparticles and lithium ions and excellent lithium ion conductivity, and exhibits excellent distribution characteristics of silver nanoparticles even after charge and discharge, thereby enabling uniform distribution of resistance within the battery and effectively controlling lithium dendrite growth. Accordingly, the all-solid-state battery of the present invention can exhibit excellent capacity retention, particularly excellent capacity retention at high rates, and also excellent lifespan characteristics.

[0021] Figure 1 shows an example of a schematic diagram of a cathode-free coating layer of an embodiment and a comparative example.

[0022] Figure 2 is a SEM image of the silver nanoparticles of Example.

[0023] Figure 3 is an SEM image of comparative silver nanoparticles.

[0024] Figure 4 is an image showing the distribution of amorphous carbon and silver nanoparticles in the non-anode coating layer, as measured by SEM / EDS, for each of the all-solid-state batteries (pouch-type monocells) of the examples and comparative examples, which were each charged and discharged once under certain conditions.

[0025] Figure 5 is an image showing the distribution of amorphous carbon and silver nanoparticles in the non-cathode coating layer, confirmed through backscatter electron (BSE) measurement for each of the all-solid-state batteries (pouch-type monocells) of the examples and comparative examples, which were each charged and discharged once under certain conditions.

[0026] FIGS. 6 and 7 are SEM images taken of a sample of an example all-solid-state battery (pouch-type monocell) that was charged and discharged 166 times under constant conditions, in which the non-cathode coating layer located between the negative electrode current collector (upper part) and the solid electrolyte (lower part) was divided into two parts (FIG. 6) or three parts (FIG. 7) in the thickness direction, respectively, and then the silver nanoparticles in each section and the remaining area were distinguished.

[0027] FIG. 8 and FIG. 9 are SEM images taken of a sample of a comparative all-solid-state battery (pouch-type monocell) that was charged and discharged 147 times under constant conditions, in which the non-cathode coating layer located between the negative electrode current collector (upper part) and the solid electrolyte (lower part) was divided into two parts (FIG. 8) or three parts (FIG. 9) in the thickness direction, respectively, and then the silver nanoparticles in each section and the remaining area were distinguished.

[0028] Figure 10 is a graph showing the XRD analysis results of silver nanoparticles for examples and comparative examples.

[0029] Figure 11 is a graph showing the results of capacity retention rate evaluation according to C-rate for examples and comparative examples.

[0030] Figure 12 is a graph showing the results of capacity retention rate evaluation according to cycle for examples and comparative examples.

[0031] 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.

[0032] 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.

[0033] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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 ℃.

[0039] 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.

[0040] In this specification, “all-solid-state battery” may mean an all-solid-state secondary battery, and may also be referred to as a cell, secondary battery, or battery.

[0041] In this specification, the term "anode-free coating layer" refers to a coating layer formed between an anode current collector and a solid electrolyte layer in an all-solid-state battery in which lithium is absorbed into the anode current collector during charging, and when the charge capacity of the anode coating layer is exceeded, lithium is precipitated between the anode current collector and the solid electrolyte layer to form a metal layer, and when discharging, lithium in the anode current collector and the lithium metal layer is ionized and moves toward the anode, and may be different from a conventional anode active material layer in its composition and operating mechanism. The anode coating layer can act as a protective layer for the lithium metal layer by covering the lithium metal layer formed on the anode current collector during the charging process and can suppress the precipitation and growth of lithium dendrites, thereby suppressing short circuits and capacity reduction of the all-solid-state battery and improving performance, etc.

[0042] 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.

[0043] The all-solid-state battery of the present invention may include, for example, a positive electrode, a solid electrolyte layer, a non-anode coating layer, and a negative electrode current collector, and the non-anode coating layer may include amorphous carbon and silver nanoparticles, and when the non-anode coating layer is divided into two parts in the thickness direction and sequentially referred to as a first section and a second section starting from a section close to the negative electrode current collector, the ratio (C2 / C1) of the content of silver nanoparticles (C1) included in the first section after charge and discharge may be, for example, in the range of 0.4 to 2.

[0044] During the charging process, lithium ions react with silver nanoparticles in the non-anode coating layer to form a lithium-silver (Li-Ag) alloy, and the lithium-silver alloy moves toward the surface close to the negative electrode current collector within the non-anode coating layer, and after the lithium ion charging capacity of the non-anode coating layer is exceeded, lithium is precipitated between the negative electrode current collector and the non-anode coating layer to form a lithium metal layer. Meanwhile, during the discharging process, lithium ions move toward the positive electrode from the lithium metal layer and / or the lithium-silver alloy. At this time, when conventional spherical silver nanoparticles were introduced, it seems that the silver nanoparticles remain concentrated in the area close to the negative electrode current collector even after discharge during repeated charge and discharge processes, and are not uniformly distributed throughout the non-anode coating layer. However, in the case of the present invention, although the clear reason has not been identified, it was confirmed that the silver nanoparticles can be uniformly distributed throughout the non-anode coating layer even after charge and discharge by including silver nanoparticles having characteristics different from those of conventional silver nanoparticles. Accordingly, the present invention can provide an all-solid-state battery in which the reactivity between silver nanoparticles and lithium ions and lithium ion conductivity can be maintained excellently, and in particular, the capacity retention rate and lifespan characteristics at high rates are excellent.

[0045] In the present invention, the ratio (C2 / C1) of the content of silver nanoparticles (C2) included in the second section to the content (C1) of silver nanoparticles included in the first section after charge and discharge may be, in other examples, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more, or 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, or 1.4 or less. Since the ratio (C2 / C1) of the content of silver nanoparticles is defined by a relative ratio, the absolute values ​​of C1 and C2 do not necessarily need to be measured, and it may also be possible to calculate it through the measurement of other indicators. In the present specification, the content (C) of silver nanoparticles included in the nth section n)(n is an integer greater than or equal to 1) is, for example, the weight (W) of silver nanoparticles included in the nth interval. n ), volume (V n ) or the area occupied by silver nanoparticles in the vertical cross-section photograph (A n ) can be proportional to. If the above content is calculated based on the area, it can be measured using an Image Analysis System as in the evaluation example described below, but at this time, the brightness standard for distinguishing between silver nanoparticles and other areas is not limited to an absolute number, and can be distinguished if there is a difference in brightness that can distinguish between different substances.

[0046] In the present invention, when the non-cathode coating layer is divided into three parts in the thickness direction and sequentially called a 1' section, a 2' section, and a 3' section from a section close to the negative electrode current collector, the ratio of the sum (C2'+C3') of the contents of silver nanoparticles included in the 2' section and the 3' section to the content (C1') of silver nanoparticles included in the 1' section after charge and discharge ((C2'+C3') / C1') may be, for example, in the range of 0.4 to 5. The ratio of the sum (C2'+C3') of the contents of silver nanoparticles included in the 2' section and the 3' section to the content (C1') of silver nanoparticles included in the 1' section ((C2'+C3') / C1') may be, in other examples, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, 1.8 or more, or 1.9 or more, or 4.5 or less, 4 or less, 3.5 or less, 3 or less, 2.5 or less, 2.4 or less, 2.3 or less, 2.2 or less, or 2.1 or less. In the present specification, the content (C) of silver nanoparticles included in the n' section n')(n' is an integer greater than or equal to 1) is, for example, the weight (W) of silver nanoparticles included in the n'th interval. n' ), volume (V n' ) or the area occupied by silver nanoparticles in the vertical cross-section photograph (A n' ) can be proportional to.

[0047] In the present invention, the silver nanoparticles may be characterized by, for example, being anisotropic. In the present specification, the anisotropic shape of the silver nanoparticles may mean any shape other than a spherical shape in which the silver nanoparticles have a constant diameter, etc. regardless of direction.

[0048] More specifically, in this specification, the anisotropic shape of silver nanoparticles may mean that the deviation of the grain sizes of representative planes according to X-ray diffraction analysis (XRD) is large, and for example, it may mean that the maximum value of the difference between the (200) plane grain size, the (220) plane grain size, and the (311) plane grain size of silver nanoparticles is 1.5 nm or more. In this specification, the maximum value of the difference between the (200) plane grain size, the (220) plane grain size, and the (311) plane grain size may mean the largest value when all differences between the grain sizes of the planes are derived. The X-ray diffraction analysis may be performed in a manner according to an evaluation example described below. The maximum value of the difference between the (200) plane grain size, the (220) plane grain size and the (311) plane grain size of the above silver nanoparticles may be, in other examples, 1.6 nm or more, 1.7 nm or more, 1.8 nm or more, 1.9 nm or more, 2.0 nm or more, 2.1 nm or more, 2.2 nm or more, 2.3 nm or more, 2.4 nm or more, 2.5 nm or more, 2.6 nm or more, 2.7 nm or more, 2.8 nm or more, 2.9 nm or more, 3.0 nm or more, 3.1 nm or more, 3.2 nm or more, 3.3 nm or more, 3.4 nm or more, 3.5 nm or more, 3.6 nm or more or 3.7 nm or more, or 20 nm or less, 15 nm or less, 10 nm or less or 5 nm or less. In this way, it can be inferred that the particles grew anisotropically from the large deviation in the crystal size of the (200), (220) and (311) planes of the silver nanoparticles of the present invention.

[0049] In the present invention, the silver nanoparticles have, for example, a BET specific surface area of ​​6 m 2 / g or less. The BET specific surface area of ​​the silver nanoparticles may be measured in a manner according to the evaluation example described below. In the present invention, the silver nanoparticles, in another example, have a BET specific surface area of ​​5.5 m 2 / g or less, 5 m 2 / g or less, 4.5 m 2 / g or less or 4 m 2 / g or less, or 0.5 m 2 / g or more, 1 m 2 / g or more, 1.5 m 2 / g or more, 2 m 2 / g or more, 2.5 m 2 / g or more, 3 m 2 / g or more or 3.5 m 2 / g or more. The larger the BET specific surface area of ​​the particle, the more likely it is that the reactivity with other surrounding substances will increase. Therefore, in the past, silver nanoparticles in a spherical shape known to have a large BET specific surface area were introduced to increase the reactivity with lithium ions. However, the silver nanoparticles of the present invention can have excellent reactivity with lithium ions despite having a smaller BET specific surface area than conventional spherical silver nanoparticles. Although the clear reason has not been identified, the silver nanoparticles of the present invention may have a shape including a neck, for example, as shown in FIG. 1, and it is presumed that the neck theoretically has high surface energy and thus contributes to increasing the reactivity with lithium ions. In the present specification, the term "neck" may mean a recessed portion compared to adjacent portions in an anisotropic silver nanoparticle.

[0050] In the present invention, the silver nanoparticles may be characterized by having an average pore size of, for example, 40 nm or more. In the present specification, the average pore size of the silver nanoparticles does not mean the average pore size of the pores contained in the silver nanoparticles themselves, but may mean the average size of the pores formed between the particles when the silver nanoparticles are packed in a manner according to the evaluation example described below. In the present specification, the average pore size may have the same meaning as the average pore diameter. The silver nanoparticles of the present invention may have an average pore size of, for example, 45 nm or more, 50 nm or more, 55 nm or more, 60 nm or more, 65 nm or more, 70 nm or more, or 75 nm or more, or 100 nm or less, 95 nm or less, 90 nm or less, 85 nm or less, or 80 nm or less.

[0051] In the present invention, the silver nanoparticles have, for example, a total pore volume of 0.065 cm 3 / g or more. In the present specification, the total pore volume of silver nanoparticles does not mean the total volume of pores contained in the silver nanoparticles themselves, but may mean the total volume of pores formed between particles when silver nanoparticles are packed in a manner according to the evaluation example described below. The silver nanoparticles of the present invention have a total pore volume of, in another example, 0.067 cm 3 / g or more, 0.069 cm 3 / g or more, 0.071 cm 3 / g or more, 0.073 cm 3 / g or more or 0.075 cm 3 / g or more, or 1 cm 3 / g or less, 0.9 cm 3 / g or less, 0.8 cm 3 / g or less, 0.7 cm 3 / g or less, 0.6 cm 3 / g or less, 0.5 cm 3 / g or less, 0.4 cm3 / g or less, 0.3 cm 3 / g or less, 0.2 cm 3 / g or less, 0.1 cm 3 / g or less, 0.09 cm 3 / g or less or 0.08 cm 3 / g can be less.

[0052] The present invention has excellent reactivity between silver nanoparticles and lithium ions and excellent lithium ion conductivity since the non-cathode coating layer includes silver nanoparticles having the above-described characteristics, and the distribution characteristics of silver nanoparticles are excellent even after charge and discharge, enabling uniformity of resistance distribution within the battery and effectively controlling lithium dendrite growth, and accordingly, the all-solid-state battery of the present invention has excellent capacity retention rate, especially at high rates, and can also have excellent lifespan characteristics.

[0053] In the present invention, the amorphous carbon may be, for example, at least one selected from the group consisting of carbon black, acetylene black, furnace black, Ketjen black, and graphene.

[0054] In the present invention, the average particle diameter of the primary particles of the amorphous carbon may be, for example, less than 100 nm. The average particle diameter of the primary particles is the average particle diameter based on volume (D 50) may mean. The average particle diameter of the primary particles may be measured by, for example, TEM, but is not limited thereto, and may be measured by a method known in the industry. The average particle diameter of the primary particles of the amorphous carbon may be, in other examples, 95 nm or less, 90 nm or less, 85 nm or less, 80 nm or less, 75 nm or less, 70 nm or less, 65 nm or less, 60 nm or less, 55 nm or less, 50 nm or less, or 45 nm or less, or 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, 25 nm or more, 30 nm or more, 35 nm or more, or 40 nm or more. The present invention can improve the lifespan of a battery by reducing the occurrence of cracks during charging of an all-solid-state battery by controlling the average primary particle diameter of amorphous carbon within the above range, and can further improve performance by providing a path for lithium ions to move efficiently.

[0055] The all-solid-state battery of the present invention includes amorphous carbon having the above-described characteristics in the non-anode coating layer, so that when the battery is charged, lithium ions supplied from the positive electrode direction can be transferred toward the negative electrode current collector to which negative charges are supplied, thereby uniformly forming a lithium metal layer between the non-anode coating layer and the negative electrode current collector.

[0056] The amorphous carbon may be included in an amount of, for example, 40 parts by weight or more based on 100 parts by weight (dry weight) of the cathode-free coating layer. In other examples, the amorphous carbon may be included in an amount of 45 parts by weight or more, 50 parts by weight or more, 55 parts by weight or more, 60 parts by weight or more, or 65 parts by weight or more, or 95 parts by weight or less, 90 parts by weight or less, 85 parts by weight or less, 80 parts by weight or less, or 75 parts by weight or less based on 100 parts by weight (dry weight) of the cathode-free coating layer.

[0057] The above-described non-cathode coating layer may be characterized by containing the silver nanoparticles in an amount of, for example, 10 to 50 parts by weight relative to 100 parts by weight of the amorphous carbon. The all-solid-state battery of the present invention may contain the silver nanoparticles in an amount of, for example, 15 parts by weight or more, 20 parts by weight or more, 25 parts by weight or more, or 30 parts by weight or more, or 45 parts by weight or less, 40 parts by weight or less, or 35 parts by weight or less, relative to 100 parts by weight of the amorphous carbon. The all-solid-state battery of the present invention can provide an all-solid-state battery having excellent cycle characteristics by introducing amorphous carbon together with the above-described silver nanoparticles.

[0058] The above-described cathode-free coating layer may further include one or more lithium-affinity elements selected from the group consisting of, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn).

[0059] The particle size of the lithium-affinity element may be, for example, in the range of 10 to 1000 nm. The particle size may refer to a maximum particle size, a minimum particle size, or an average particle size. In other examples, the particle size of the lithium-affinity element may be, but is not limited to, 20 nm or more, 30 nm or more, 40 nm or more, or 50 nm or more, or 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, or 100 nm or less.

[0060] The cathode-free coating layer of the present invention 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.

[0061] The binder may be characterized in that it is included in an amount of, for example, 1 to 20 parts by weight relative to 100 parts by weight of the amorphous carbon. The weight ratio of the binder to the amorphous carbon may mean a value converted based on the solid content of the binder, i.e., the dry weight. In other examples, the binder may be included in an amount of 2 parts by weight or more, 3 parts by weight or more, 4 parts by weight or more, 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, or 8 parts by weight or more, or 19 parts by weight or less, 18 parts by weight or less, 17 parts by weight or less, 16 parts by weight or less, 15 parts by weight or less, 14 parts by weight or less, 13 parts by weight or less, 12 parts by weight or less, 11 parts by weight or less, or 10 parts by weight or less relative to 100 parts by weight of the amorphous carbon.

[0062] In the present invention, by controlling the weight ratio between the compositions included in the non-cathode coating layer as described above, an all-solid-state battery having excellent performance and lifespan characteristics can be provided.

[0063] In the present invention, the cathode-free coating layer may further include, for example, a solvent. In the present specification, the meaning of the cathode-free coating layer further including a solvent may mean that a solvent is used in the process of manufacturing the cathode-free coating layer, and may not mean that the cathode-free coating layer finally manufactured through drying or the like contains a solvent. The solvent may be water, N-methylpyrrolidone (NMP), or the like.

[0064] In the present invention, the non-cathode coating layer may further include, for example, other additives. As the other additives, fillers, coating agents, dispersants, ion conductivity aids, etc. used in conventional all-solid-state batteries may be used without limitation, as long as they do not impede the purpose of the present invention.

[0065] In the present invention, the cathode-free coating layer can be manufactured, for example, by applying a slurry in which a material constituting the cathode-free coating layer is dispersed onto a cathode current collector and drying the slurry.

[0066] In the present invention, the thickness of the non-anode coating layer may be 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer described later. The thickness of the non-anode coating layer may be, for example, in a range of 1 to 20 μm, 5 to 18 μm, or 9 to 15 μm. By controlling the thickness of the non-anode coating layer as described above, lithium dendrites formed between the non-anode coating layer and the negative electrode current collector described later can be controlled to prevent the non-anode coating layer from collapsing, thereby improving cycle characteristics, improving energy density, and reducing internal resistance of the all-solid-state battery.

[0067] The cathode-free coating layer of the present invention may have a porosity of, for example, 50 to 80%. The porosity of the cathode-free coating layer may be measured by a known method. In other examples, the porosity of the cathode-free coating layer may be, but is not limited to, 55% or more, 60% or more, or 65% or more, or 75% or less, or 70% or less.

[0068] The above positive electrode may include, for example, a positive electrode current collector and / or a positive electrode active material layer.

[0069] As the positive electrode current collector, any known metal that can be used as a current collector for an all-solid-state battery can be used. 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.

[0070] The above positive electrode active material layer may include, for example, a positive electrode active material, a solid electrolyte, a binder, and / or a conductive material.

[0071] The above-mentioned positive electrode active material reversibly absorbs and desorbs lithium ions. The positive electrode active material may be, but is not limited to, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, and any material used as a positive electrode active material in the art may be used. The positive electrode active materials may be used alone or in combination of two or more.

[0072] 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 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 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 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 NiGb 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.

[0073] 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.

[0074] 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.

[0075] The solid electrolyte included in the above-described positive electrode active material layer may be, for example, the same as or different from the solid electrolyte included in the solid electrolyte layer. The solid electrolyte included in the above-described positive electrode active material layer may be, but is not limited to, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a phosphate-based solid electrolyte, or a halide-based solid electrolyte, and may be any electrolyte commonly used in all-solid-state batteries.

[0076] 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.

[0077] The binder included in the above positive electrode active material layer may be, for example, acrylonitrile butadiene rubber (ABR), butadiene rubber (BR), styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc.

[0078] The conductive material included in the above positive electrode active material layer may be, for example, graphite, carbon black, acetylene black, Ketzen black, carbon fiber, or metal powder.

[0079] 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.

[0080] The above solid electrolyte layer may include, for example, a sulfide-based solid electrolyte. The above sulfide-based solid electrolyte may include, for example, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-LiBr-LiI-P2S5, 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), Li7-x PS 6-x Br x (0≤x≤2) and Li 7-x PS 6-x I x (0≤x≤2) may be at least one selected from. The 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, for example. In addition, a heat treatment may be performed after the treatment. The solid electrolyte may be in an amorphous, crystalline, or mixed state thereof. In the present invention, the sulfide-based solid electrolyte may be, for example, one including sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the above-mentioned sulfide-based solid electrolyte materials.

[0081] 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 x It 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.

[0082] 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.

[0083] The elastic modulus of the above solid electrolyte may be, for example, 15 to 45 GPa.

[0084] The above solid electrolyte layer may include, for example, a binder. The binder included in the solid electrolyte layer may be, for example, one of the types of binders included in the positive active material layer and / or the non-cathode coating layer, but is not limited thereto, and any binder used in the relevant technical field may be used. The binder included in the solid electrolyte layer may be the same as or different from the binder included in the above-described positive active material layer and / or the non-cathode coating layer.

[0085] 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.

[0086] The all-solid-state battery of the present invention may further include, for example, a metal including lithium or a lithium alloy and / or a metal (layer) thereof between the negative electrode current collector and the non-anode coating layer, and / or within the non-anode coating layer, by charging. The lithium alloy may be, for example, a lithium-silver alloy, and in other examples, a lithium-aluminum alloy, a lithium-tin alloy, a lithium-indium alloy, a lithium-gold alloy, a lithium-zinc alloy, a lithium-germanium alloy, or a lithium-silicon alloy, but is not limited thereto, and any lithium alloy used in the art may be used. The metal or metal layer included between the negative electrode current collector and the non-anode coating layer, and / or within the non-anode coating layer may be composed of one of these alloys, lithium, or may be composed of multiple types of alloys.

[0087] The thickness of the metal layer including the lithium or lithium alloy may be, for example, in a range of 1 to 1000 μm, 1 to 500 μm, 1 to 200 μm, 1 to 150 μm, 1 to 100 μm or 1 to 50 μm. The thickness needs to be controlled as described above so that the metal layer can perform its role as a lithium storage well and improve cycle characteristics.

[0088] The metal layer may be formed by precipitation between the negative current collector and the non-anode coating layer and / or within the non-anode coating layer, for example, by charging after assembling the all-solid-state battery. When the metal layer is formed between the negative current collector and the non-anode coating layer and / or within the non-anode coating layer by charging after assembling the all-solid-state battery, these regions may be, for example, lithium-free regions that do not contain lithium in the initial state or post-discharge state of the all-solid-state battery.

[0089] The all-solid-state battery of the present invention may be characterized by, for example, a 1.0C capacity retention rate of 88% or more relative to the 0.1C capacity. The 1.0C capacity retention rate relative to the 0.1C capacity may be measured in a manner according to an evaluation example described below. In another example, the all-solid-state battery of the present invention may have a 1.0C capacity retention rate relative to the 0.1C capacity of 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, or 96% or more, and the upper limit is not particularly limited, but may be 99.9% or less, 99% or less, 98% or less, or 97% or less.

[0090] The all-solid-state battery of the present invention may be characterized by, for example, a 0.33C capacity retention rate of 98% or more relative to the 0.1C capacity. The 0.33C capacity retention rate relative to the 0.1C capacity may be measured in a manner according to an evaluation example described below. In another example, the all-solid-state battery of the present invention may have a 0.33C capacity retention rate relative to the 0.1C capacity of 98.1% or more, 98.2% or more, 98.3% or more, 98.4% or more, 98.5% or more, 98.6% or more, 98.7% or more, 98.8% or more, 98.9% or more, 99% or more, 99.1% or more, or 99.2% or more, and the upper limit is not particularly limited, but may be 99.9% or less or 99.5% or less.

[0091] The all-solid-state battery of the present invention may be characterized by, for example, a 0.5C capacity retention rate of 96% or more relative to the 0.1C capacity. The 0.5C capacity retention rate relative to the 0.1C capacity may be measured in a manner according to an evaluation example described below. In another example, the all-solid-state battery of the present invention may have a 0.5C capacity retention rate relative to the 0.1C capacity of 96.5% or more, 97% or more, 97.5% or more, or 98% or more, and the upper limit is not particularly limited, but may be 99.9% or less, 99% or less, or 98% or less.

[0092] A second aspect of the present invention relates to a method for manufacturing an all-solid-state battery using lithium or a lithium alloy as a negative electrode active material.

[0093] Matters relating to the first aspect of the present invention may be equally applied to matters relating to the second aspect unless specifically stated otherwise.

[0094] The method for manufacturing an all-solid-state battery of the present invention may include, for example, a step of forming a non-anode coating layer on a negative electrode current collector.

[0095] The step of forming a non-cathode coating layer on the negative electrode current collector may include, for example, a step of applying a non-cathode coating layer forming composition including amorphous carbon and silver nanoparticles onto the negative electrode current collector; and / or a step of drying the applied non-cathode coating layer forming composition to form a non-cathode coating layer.

[0096] The step of applying the composition for forming a non-cathode coating layer including the above amorphous carbon and silver nanoparticles onto the negative electrode current collector may be performed by, but is not limited to, dip coating, T-die coating or gravure coating, and may be performed by a known coating method.

[0097] The composition for forming the above-described cathode coating layer may further include, for example, a binder and / or a solvent, and the contents regarding the above-described cathode coating layer may be equally applied.

[0098] The step of forming a cathode-free coating layer by drying the composition for forming the cathode-free coating layer applied above can be performed at a temperature of, for example, 50 to 200°C, and the pressure conditions are not particularly limited, but may be performed in a vacuum in some cases.

[0099] The all-solid-state battery according to the manufacturing method of the present invention may be characterized in that, for example, when the non-anode coating layer is divided into two parts in the thickness direction and sequentially referred to as a first section and a second section starting from the section close to the anode current collector, the ratio (C2 / C1) of the content of silver nanoparticles (C1) included in the first section after charge and discharge is within the range of 0.4 to 2.

[0100] The above silver nanoparticles may be characterized, for example, by being anisotropic.

[0101] The amorphous carbon and silver nanoparticles may be characterized, for example, as being simply mixed. The present invention can prevent migration of silver nanoparticles due to charge and discharge simply by mixing the amorphous carbon and silver nanoparticles included in the non-cathode coating layer without any separate treatment such as compounding. As a result, an all-solid-state battery can be provided in which the distribution characteristics of silver nanoparticles are excellent even after charge and discharge, enabling uniformity of resistance distribution within the battery and also effectively controlling lithium dendrite growth.

[0102] In the present invention, the manufacturing and laminating of a positive electrode, a solid electrolyte layer, etc. to manufacture an all-solid-state battery can be done according to a known method.

[0103] 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.

[0104] Example.

[0105] (cathode)

[0106] 6 g of carbon black (average particle size: 41 nm), 2 g of anisotropic silver (Ag) nanoparticles, 9.33 g of PVdF solution (6% solid content), and 7.19 g of NMP solution are placed in a thinky mixer container and mixed multiple times at 2000 rpm for 3 minutes. Then, 5 g of NMP solution is additionally added, and mixing is performed 5 times at 2000 rpm for 3 minutes each to prepare a cathode-free coating layer slurry. Next, the slurry is 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 14.0 μm and a porosity of 67.1% was obtained on the SUS foil.

[0107] (anode)

[0108] LiNi as positive electrode active material 0.8 Co 0.15 Mn 0.05 O2 (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 = 84:15:0.2:1.2, and the mixture was formed into a large sheet shape to produce a positive electrode sheet. In addition, this positive electrode sheet was pressed onto an 18-㎛-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).

[0109] (solid electrolyte layer)

[0110] The solid electrolyte layer used was one containing Li6PS5Cl solid electrolyte.

[0111] (all-solid-state battery)

[0112] An all-solid-state battery was fabricated by stacking a positive electrode, a solid electrolyte, 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 at 500 MPa for 30 minutes. This hydrostatic pressure treatment significantly improved the battery's performance.

[0113] Comparative example.

[0114] An all-solid-state battery including a cathode having a non-cathode coating layer having a thickness of 16 μm and a porosity of 67.1% formed on a SUS foil was obtained in the same manner as in the example except that spherical silver nanoparticles (DF-SLN-002, Dowa) (average particle diameter 60 nm) were used instead of anisotropic silver nanoparticles during the manufacture of the cathode.

[0115] Evaluation Example 1. Silver nanoparticle shape

[0116] The silver nanoparticles used in each of the examples and comparative examples were mixed with an ethanol solution, sonicated, and dispersed for more than 1 hour. The dispersion was then applied to a silicon wafer (Si wafer), dried, and SEM images were observed. As a result, it was confirmed that, unlike the silver nanoparticles of the comparative example, which were spherical, the silver nanoparticles of the examples were anisotropic (Figs. 2 and 3).

[0117] Evaluation Example 2. Distribution characteristics of silver nanoparticles and amorphous carbon

[0118] The all-solid-state batteries (pouch-type monocells) of the examples and comparative examples were activated twice and charged and discharged once each at rates of 0.33C, 0.5C, 1.0C, and 0.1C at an operating voltage range of 4.3 V to 3.0 V and an operating temperature of 60°C, and then charged and discharged once each at a current density of 0.33C to prepare samples. For the above samples, a cross-section of the all-solid-state battery excluding the pouch was manufactured through Cooling Cross-section Polishing (ion milling) under Ar atmosphere and 120 μA conditions, and the distribution of the positive electrode / electrolyte / cathode and the interface changes were confirmed using SEM / EDS (Fig. 4). In addition, the distribution of amorphous carbon and silver nanoparticles in the non-cathode coating layer was confirmed in more detail through backscatter electron (BSE) measurement. As the atomic number increases, more backscattered electrons are generated, so silver (atomic number: 47) appears as a brighter spot than carbon (atomic number: 6), and carbon appears as a dark spot (Fig. 5). As a result, in both the examples and comparative examples, lithium alloy precipitation and restoration to the positive electrode occurred during a single charge / discharge process, and it was confirmed that the positive electrode / solid electrolyte layer / cathode-free coating layer interface was well maintained. However, in the case of the examples, a distribution similar to the initial non-cathode coating layer was maintained even after a single charge / discharge, but in the case of the comparative example, the silver nanoparticles appearing as bright spots did not maintain the initial distribution of the non-cathode coating layer and were distributed biasedly in the first section in the direction of the negative electrode current collector (Figs. 4 and 5).

[0119] Meanwhile, the all-solid-state batteries (pouch-type monocells) of the examples and comparative examples were activated twice and charged and discharged once each at rates of 0.33C, 0.5C, 1.0C, and 0.1C in the operating voltage range of 4.3 V - 3.0 V and the operating temperature of 60 ℃, and then charged and discharged 166 and 147 times at a current density of 0.33C, respectively, to prepare samples. For the above samples, a cross-section of the all-solid-state battery excluding the pouch was manufactured through Cooling Cross-section Polishing (ion milling) under Ar atmosphere and 120 μA conditions, and an SEM image was taken, converted to a black and white image, and the area ratio was calculated by distinguishing the silver nanoparticle area and the remaining area for each section of the non-cathode coating layer using an Image Analysis System. Specifically, as shown in FIGS. 6 to 9, the non-cathode coating layer located between the cathode current collector (upper part) and the solid electrolyte (lower part) in the black-and-white converted SEM images was divided into two or three parts in the thickness direction, and then the silver nanoparticle region and the remaining region were distinguished based on the brightness intensity divided into 256 levels of [black, white] = [0, 255]. At this time, the region with a level of 255 was designated as the silver nanoparticle region (indicated in red), and the region with levels 96 to 105 was designated as the remaining region (indicated in green). As a result, in the example, when divided into two equal parts, the area ratio of silver nanoparticles in the first section (the ratio of the area of ​​silver nanoparticles to the total area of ​​the first section) (A1) was 3%, the area ratio of silver nanoparticles in the second section (A2) was 4%, and A2 / A1 was 1.33 (Fig. 6), and when divided into three equal parts, the area ratio of silver nanoparticles in the first section (A1') was 3%, the area ratio of silver nanoparticles in the second section (A2') and the area ratio of silver nanoparticles in the third section (A3') were 6%, and (A2'+A3') / A1' was 2 (Fig. 7). On the other hand, in the comparative example, when divided into two equal parts, the area ratio of silver nanoparticles in the first section (A1) was 9%, the area ratio of silver nanoparticles in the second section (A2) was 3%, and A2 / A1 was 0.33 (Fig. 8), and when divided into three parts, the area ratio of silver nanoparticles in the first section (A1') was 10%, the area ratio of silver nanoparticles in the second section (A2') and the area ratio of silver nanoparticles in the third section (A3') were 3%, so (A2'+A3') / A1' was 0.3 (Fig. 9). In this way, even after the all-solid-state battery of the example performed more cycles than the comparative example, the distribution of silver nanoparticles after discharge was more uniform than that of the comparative example.

[0120] Through this, it can be seen that when anisotropic silver nanoparticles such as those in the example are included in the cathode-free coating layer, alloying between lithium ions and silver can be achieved more efficiently, and uniformity of resistance distribution within the battery can also be achieved, thereby achieving excellent reversibility (efficiency, rate characteristics, and life characteristics).

[0121] Evaluation Example 3. XRD (X-ray Diffraction) Analysis of Silver Nanoparticles

[0122] XRD analysis was performed on the silver nanoparticles of the examples and comparative examples. Specifically, xXRD analysis was performed using a Bruker D8 Endeavor X-ray diffractometer (Cu target) in powder type 2-theta mode at a voltage / current of 40 kV / 30 mA. The results were as shown in Fig. 10 and Table 1 below.

[0123] As a result of checking the half-width of each facet of the silver nanoparticles, it was found that the examples and comparative examples had a difference of 0.01 or more in the half-width on all of the (111) facet, (200) facet, (220) facet, and (311) facet.

[0124] In addition, as a result of checking the crystal grain size of each plane above, the silver nanoparticles of the example had crystal grain sizes of 15 to 18.8 nm on the (200) plane, (220) plane, and (311) plane, with a difference of about 3.8 nm between the maximum and minimum values, whereas the silver nanoparticles of the comparative example had crystal grain sizes of 14.7 to 15.7 nm on the (200) plane, (220) plane, and (311) plane, with a difference of about 1 nm between the maximum and minimum values. This shows that the silver nanoparticles of the example grew anisotropically.

[0125]

[0126] Evaluation Example 4. BET Analysis

[0127] The specific surface area and pore characteristics of silver nanoparticles of examples and comparative examples were measured according to the commonly used BET method (Brunauer, Emmett, and Teller's method). Specifically, the specific surface area of ​​amorphous carbon was measured when the residual pressure of each sample was 10 at 298 K. -3 After outgassing for about 2 hours until the temperature reached torr, the surface adsorption properties of silver nanoparticles were measured by measuring the adsorption amount of N2 gas at 77 K using a Micromeritics, ASAP 2460 device. BET Development of micropores and S BJH As a result, the mid-term results were analyzed and derived.

[0128]

[0129] (In Table 2, Vm represents the total pore volume per weight of the sample)

[0130] Evaluation Example 5. Capacity Retention Rate

[0131] The all-solid-state batteries (pouch-type monocells) of the examples and comparative examples were charged under conditions of 0.1C, 4.3V CC / CV, 0.05C cut-off at an operating voltage range of 4.3V-3.0V and an operating temperature of 60℃, and discharged under conditions of 0.1C, 3.0V, CC. After activation twice, the capacity retention rate was measured when rate evaluation was performed once each at current densities of 0.33C, 0.5C, 1.0C, 0.1C, and 0.33C.

[0132] As a result, the capacity retention rates of each of the examples and comparative examples were confirmed as shown in Table 3 and Figure 11 below. As such, it can be confirmed that the examples had overall superior capacity retention rates compared to the comparative examples, and in particular, the capacity retention rate at high rates (1.0C) was remarkably superior.

[0133]

[0134] (In Table 3, 0.1C capacity refers to the capacity after two activations)

[0135] Evaluation Example 6. Life Characteristics

[0136] The all-solid-state batteries (pouch-type monocells) of the examples and comparative examples were activated twice and charged and discharged once each at rates of 0.33C, 0.5C, 1.0C, and 0.1C in an operating voltage range of 4.3V-3.0V and an operating temperature of 60℃, and then the capacity retention rate according to the cycle was measured at a current density of 0.33C.

[0137] As a result, the embodiment showed an overall superior capacity retention rate compared to the comparative example for each cycle. In addition, the capacity retention rate of the comparative example rapidly decreased after approximately 75 cycles and then short-circuited after approximately 130 cycles, whereas the embodiment maintained a gradual decrease in capacity retention rate according to cycles and operated without short-circuiting for 300 cycles (Fig. 12).

Claims

1. An all-solid-state battery using lithium or a lithium alloy as a negative electrode active material, Containing a cathode, a solid electrolyte layer, a non-cathode coating layer and a cathode current collector, The above-mentioned cathode-free coating layer comprises amorphous carbon and silver nanoparticles, An all-solid-state battery characterized in that, when the above-mentioned non-cathode coating layer is divided into two parts in the thickness direction and sequentially referred to as a first section and a second section starting from a section close to a negative electrode current collector, the ratio (C2 / C1) of the content of silver nanoparticles (C1) included in the first section to the content of silver nanoparticles (C2) included in the second section after charge and discharge is within a range of 0.4 to 2.

2. In the first paragraph, when the non-cathode coating layer is divided into three parts in the thickness direction and sequentially called a 1' section, a 2' section, and a 3' section from a section close to the negative electrode collector, an all-solid-state battery characterized in that the ratio of the sum (C2'+C3') of the contents of silver nanoparticles included in the 2' section and the 3' section to the content (C1') of silver nanoparticles included in the 1' section after charge and discharge ((C2'+C3') / C1') is within a range of 0.4 to 5.

3. An all-solid-state battery according to claim 1, characterized in that the silver nanoparticles are anisotropic.

4. An all-solid-state battery, characterized in that the maximum value of the difference between the (200) surface crystal grain size, the (220) surface crystal grain size, and the (311) surface crystal grain size of the silver nanoparticles is 1.5 nm or more.

5. In the first paragraph, the BET specific surface area of ​​the silver nanoparticles is 6 m 2 An all-solid-state battery characterized by having a mass of / g or less.

6. An all-solid-state battery according to claim 1, characterized in that the average pore size of the silver nanoparticles is 40 nm or more.

7. In the first paragraph, the total pore volume of the silver nanoparticles is 0.065 cm 3 An all-solid-state battery characterized by having a mass of / g or more.

8. An all-solid-state battery, characterized in that in paragraph 1, the amorphous carbon is at least one selected from the group consisting of carbon black, acetylene black, furnace black, Ketjen black, and graphene.

9. An all-solid-state battery, characterized in that the silver nanoparticles are included in an amount of 10 to 50 parts by weight relative to 100 parts by weight of amorphous carbon in the first paragraph.

10. An all-solid-state battery according to claim 1, characterized in that the non-cathode coating layer further comprises a binder.

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

12. In the 11th paragraph, 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 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 by having at least one selected from (0≤x≤2).

13. An all-solid-state battery characterized in that the 1.0C capacity retention rate is 88% or more compared to the 0.1C capacity in the first paragraph.

14. A method for manufacturing an all-solid-state battery using lithium or a lithium alloy as a negative electrode active material, The method for manufacturing the above all-solid-state battery includes a step of forming a non-anode coating layer on a negative electrode current collector, The step of forming a non-cathode coating layer on the negative electrode current collector includes the step of applying a non-cathode coating layer forming composition including amorphous carbon and silver nanoparticles to the negative electrode current collector; and the step of drying the applied non-cathode coating layer forming composition to form a non-cathode coating layer. A method for manufacturing an all-solid-state battery, characterized in that when the above-mentioned non-cathode coating layer is divided into two parts in the thickness direction and sequentially referred to as a first section and a second section starting from a section close to a negative electrode current collector, the ratio (C2 / C1) of the content of silver nanoparticles (C1) included in the first section to the content of silver nanoparticles (C2) included in the second section after charge and discharge is within a range of 0.4 to 2.

15. A method for manufacturing an all-solid-state battery, characterized in that the silver nanoparticles in the 14th paragraph are anisotropic.

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