All-solid state battery containing the same

Abstract

The present invention aims to solve the above problem by providing an all-solid-state battery in which the non-cathode coating layer contains anisotropic silver nanoparticles, thereby providing excellent reactivity between silver nanoparticles and lithium ions and lithium ion conductivity, and excellent distribution characteristics of silver nanoparticles even after charging and discharging, which enables uniformity of resistance distribution within the battery and effective control of lithium dendrite growth. Accordingly, the all-solid-state battery of the present invention can have excellent capacity retention rate, particularly at high rates, and excellent lifespan characteristics.

Description

Technology Field

[0001] The present invention relates to an all-solid-state battery using lithium or a lithium alloy as a negative electrode active material. Background Technology

[0002] Recently, methods using lithium as a negative electrode active material are being studied to increase the energy density of all-solid-state batteries. Methods for using lithium as a negative electrode active material include using lithium or a lithium alloy as the negative electrode active material layer during the battery manufacturing process, or forming a lithium layer during the charging process without forming a separate negative electrode active material layer on the negative electrode current collector during manufacturing.

[0003] However, when lithium is used as the negative electrode active material, lithium (metallic lithium) is deposited on the negative electrode side during charging. As the charging and discharging process is repeated, lithium dendrites grow through the gaps in the solid electrolyte layer, which causes problems such as short circuits in the battery or reduced capacity.

[0004] Therefore, in order to commercialize the method of using lithium as a negative electrode active material, it is necessary to improve the above-mentioned problems. The problem to be solved

[0005] The present invention aims to solve the above problem by providing an all-solid-state battery in which the non-cathode coating layer contains anisotropic silver nanoparticles, thereby providing excellent reactivity between silver nanoparticles and lithium ions and lithium ion conductivity, and excellent distribution characteristics of silver nanoparticles even after charging and discharging, which enables uniformity of resistance distribution within the battery and effective control of lithium dendrite growth. Accordingly, the all-solid-state battery of the present invention can have excellent capacity retention rate, particularly at high rates, and excellent lifespan characteristics. means of solving the problem

[0006] The present invention relates to an all-solid-state battery using lithium or a lithium alloy as a negative electrode active material, comprising a positive electrode, a solid electrolyte layer, a negative electrode coating layer, and a negative electrode current collector, wherein the negative electrode coating layer comprises amorphous carbon and silver nanoparticles, and when the negative electrode coating layer is divided into two equal parts in the thickness direction, sequentially referred to as a first section and a second section starting from the section closest to the negative electrode current collector, the ratio (C2 / C1) of the content of silver nanoparticles (C1) contained in the first section to the content of silver nanoparticles (C2) contained in the second section after charging and discharging is within the 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-negative electrode coating layer is divided into three equal parts in the thickness direction and sequentially referred to as the first' section, the second' section, and the third' section starting from the section closest to the negative electrode current collector, the ratio of the sum of the contents of silver nanoparticles (C2'+C3') contained in the second' section and the third' section ((C2'+C3') / C1') to the content of silver nanoparticles contained in the first' section after charging and discharging (C1') is within the range of 0.4 to 5.

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

[0009] In one embodiment, the maximum difference between the (200) plane grain size, (220) plane grain size and (311) plane grain size of the silver nanoparticles may be 1.5 nm or more.

[0010] In one embodiment, the BET specific surface area of ​​the silver nanoparticles is 6 m² 2 It can be characterized as being less than / g.

[0011] In one embodiment, the average pore size of the silver nanoparticles may be 40 nm or larger.

[0012] In one embodiment, the total pore volume of the silver nanoparticles is 0.065 cm³ 3 It can be characterized as being greater than / g.

[0013] In one embodiment, the amorphous carbon may be characterized as being one or more selected from the group consisting of carbon black, acetylene black, furnace black, Ketjen black, and graphene.

[0014] In one embodiment, the silver nanoparticles may be included in a range of 10 to 50 parts by weight relative to 100 parts by weight of amorphous carbon.

[0015] In one embodiment, the non-cathode coating layer may be characterized by further including a binder.

[0016] In one embodiment, the solid electrolyte layer may be characterized by comprising a sulfide-based solid electrolyte.

[0017] 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 as being one or more types selected from (0≤x≤2).

[0018] In one embodiment, the all-solid-state battery of the present invention may be characterized by having a 1.0C capacity retention rate of 88% or more relative to the 0.1C capacity. Effects of the invention

[0019] The present invention aims to solve the above problem and provides an all-solid-state battery that includes anisotropic silver nanoparticles, thereby exhibiting excellent reactivity between silver nanoparticles and lithium ions and lithium ion conductivity, and having excellent distribution characteristics of silver nanoparticles even after charging and discharging, enabling uniformity of resistance distribution within the battery and effective control of lithium dendrite growth. Accordingly, the all-solid-state battery of the present invention can have excellent capacity retention rate, particularly at high rates, and excellent lifespan characteristics. Brief explanation of the drawing

[0020] Figure 1 shows an example of a schematic diagram of a non-cathode coating layer of an example and a comparative example. Figure 2 is an SEM image of the silver nanoparticles of the example. Figure 3 is an SEM image of a comparative example silver nanoparticle. Figure 4 is an image showing the distribution of amorphous carbon and silver nanoparticles in the anode-free coating layer through SEM / EDS measurements on samples that were charged and discharged once under certain conditions for each of the all-solid-state batteries (pouch-type monocells) of the examples and comparative examples. Figure 5 is an image showing the distribution of amorphous carbon and silver nanoparticles in the anode-free coating layer through backscattered electron (BSE) measurements for samples that were charged and discharged once under certain conditions for each of the all-solid-state batteries (pouch-type monocells) of the examples and comparative examples. Figures 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 certain conditions, in which the non-cathode coating layer located between the negative electrode current collector (top) and the solid electrolyte (bottom) was divided into two equal parts (Figure 6) or three equal parts (Figure 7) in the thickness direction, respectively, and then the silver nanoparticles in each section and the remaining area were distinguished. Figures 8 and 9 are SEM images taken of a sample of a comparative example all-solid-state battery (pouch-type monocell) that was charged and discharged 147 times under certain conditions, in which the non-cathode coating layer located between the negative electrode current collector (top) and the solid electrolyte (bottom) was divided into two equal parts (Figure 8) or three equal parts (Figure 9) in the thickness direction, respectively, and then the silver nanoparticles in each section and the remaining area were distinguished. Figure 10 is a graph showing the XRD analysis results of silver nanoparticles for the examples and comparative examples. Figure 11 is a graph showing the results of the capacity retention rate evaluation according to the C-rate for the examples and comparative examples. Figure 12 is a graph showing the results of evaluating the capacity retention rate according to the cycle for the examples and comparative examples. Specific details for implementing the invention

[0021] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0022] Therefore, it should be understood that the configuration of the embodiments described in this specification is merely one of the most preferred embodiments of the present invention and does not represent all of the technical ideas of the present invention, and that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0023] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0024] In this specification, when a part is described as “comprising” a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Thus, for example, a composition comprising compound A may include compounds other than A. However, the term “comprising” also encompasses, in a more restrictive sense as a specific embodiment thereof, “essentially / essentially composed of” and “composed of,” so, for example, a “composition comprising compound A” may also be (essentially / essentially) composed of compound A.

[0025] In connection with this, terms such as “comprising” or “having,” as described in this specification, are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should not be understood as precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0026] In this specification, when any layer is described as being located “on” or “between” another arbitrary layer, this includes not only cases where any layer is in contact with another arbitrary layer, but also cases where another layer or material, etc., exists between the two layers.

[0027] Where in this specification a quantity, concentration, or other value or parameter is given as an enumeration of a range, a preferred range, a preferred upper limit, and a preferred lower limit, it should be understood that any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the range is disclosed separately, specifically discloses all ranges that may be formed. Where a range of numerical values ​​is mentioned in this specification, unless otherwise stated, for example, without limiting terms such as greater than or less than, the range is intended to include its endpoint value and all integers and fractions within that range. The scope of the invention is not intended to be limited to the specific value mentioned when defining the range.

[0028] Among the physical properties mentioned in this specification, if the measured temperature affects the property, the property is measured at room temperature unless specifically otherwise specified. The term "room temperature" refers to a natural temperature that has not been heated or cooled, and may mean, for example, any temperature within the range of about 10°C to 30°C, about 23°C, or about 25°C. Furthermore, unless specifically otherwise specified, the unit of temperature in this specification is °C.

[0029] In addition, among the physical properties mentioned in this specification, if the measured pressure affects the physical property, unless specifically otherwise specified, the physical property is measured at normal pressure, that is, atmospheric pressure (about 1 atmosphere).

[0030] In this specification, "all-solid-state battery" may mean an all-solid-state secondary battery and may be referred to as a cell, secondary battery, or battery, etc.

[0031] In this specification, the term "non-cathode coating layer" refers to a coating layer formed between a negative electrode current collector and a solid electrolyte layer in an all-solid-state battery in which lithium is adsorbed in the non-cathode coating layer during charging and, after the charging capacity of the non-cathode coating layer is exceeded, lithium is precipitated between the negative electrode current collector and the solid electrolyte layer to form a metal layer, and during discharge, lithium in the non-cathode coating layer and the lithium metal layer is ionized and moves toward the positive electrode. The composition and operating mechanism may differ from that of a conventional negative electrode active material layer. The non-cathode coating layer can cover the lithium metal layer formed on the negative electrode current collector during the charging process to serve as a protective layer for the lithium metal layer and can suppress the precipitation growth of lithium dendrites. Through this, short circuits and capacity degradation of the all-solid-state battery can be suppressed and performance can be improved.

[0032] The present invention may relate to an all-solid-state battery that uses, for example, lithium or a lithium alloy as a negative electrode active material, and may include a positive electrode, a solid electrolyte layer, a negative electrode coating layer, and a negative electrode current collector, wherein the negative electrode coating layer may include amorphous carbon and silver nanoparticles, and when the negative electrode coating layer is divided into two equal parts in the thickness direction and sequentially referred to as a first section and a second section starting from the section closest to the negative electrode current collector, the ratio (C2 / C1) of the content of silver nanoparticles (C1) contained in the first section to the content of silver nanoparticles (C2) contained in the second section after charging and discharging is, for example, within the range of 0.4 to 2.

[0033] During the charging process, lithium ions react with silver nanoparticles within the anode coating layer to form a lithium-silver (Li-Ag) alloy. The lithium-silver alloy moves within the anode coating layer toward the surface near the negative electrode current collector, and after the lithium ion charging capacity of the anode coating layer is exceeded, lithium is precipitated between the negative electrode current collector and the anode coating layer to form a lithium metal layer. Meanwhile, during the discharge process, lithium ions move from the lithium metal layer and / or the lithium-silver alloy toward the positive electrode. In this case, when conventional spherical silver nanoparticles are introduced, it appears that during repeated charging and discharging, the silver nanoparticles remain concentrated in the region near the negative electrode current collector even after discharge, and do not spread uniformly throughout the anode coating layer. However, in the case of the present invention, although the exact reason is not clearly known, it has been confirmed that by including silver nanoparticles having characteristics different from conventional silver nanoparticles, the silver nanoparticles can be distributed uniformly throughout the anode coating layer even after charging and discharging. Accordingly, the present invention can provide an all-solid-state battery in which the reactivity between silver nanoparticles and lithium ions and the lithium ion conductivity can be maintained excellently, and in particular, the capacity retention rate and lifespan characteristics at high rates are excellent.

[0034] 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 charging and discharging may, in other examples, be 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 of the silver nanoparticle content (C2 / C1) is defined by a relative ratio, it is not necessary to measure the absolute values ​​of C1 and C2, and it may be possible to calculate it through the measurement of other indicators. In this specification, the content of silver nanoparticles (C) included in the n-th 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 a vertical cross-sectional photograph (A n It can be proportional to ). When the above content is calculated based on area, it can be measured using an Image Analysis System as in the evaluation example described below, provided that the brightness criterion distinguishing between silver nanoparticles and other regions is not limited to an absolute value, but can be distinguished when there is a brightness difference that can distinguish between different materials.

[0035] In the present invention, when a non-cathode coating layer is divided into three equal parts in the thickness direction and sequentially referred to as the 1' section, the 2' section, and the 3' section starting from the section closest to the cathode current collector, the ratio of the sum of the contents of silver nanoparticles in the 2' section and the 3' section (C2'+C3') to the contents of silver nanoparticles in the 1' section after charging and discharging (C1') ((C2'+C3') / C1') may be characterized as being within the range of, for example, 0.4 to 5. The ratio ((C2'+C3') / C1') of the sum of the contents of silver nanoparticles included in the 2' and 3' sections to the content of silver nanoparticles included in the 1' section (C1') may, in other examples, be 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 this specification, the content of silver nanoparticles included in the n' section (C n')(n' is an integer greater than or equal to 1) is, for example, the weight (W) of silver nanoparticles included in the n' interval. n' ), volume(V n' ) or the area occupied by silver nanoparticles in a vertical cross-sectional photograph (A n' It can be proportional to ).

[0036] In the present invention, the silver nanoparticles may be characterized as being, for example, anisotropic. In this specification, the term "anisotropic silver nanoparticles" may mean shapes other than spherical shapes having a constant diameter regardless of direction.

[0037] More specifically, in this specification, the statement that silver nanoparticles are anisotropic may mean that the variation in grain size of representative planes according to X-ray diffraction analysis (XRD) is large, and for example, may mean that the maximum value of the difference between the grain size of the (200) plane, the grain size of the (220) plane, and the grain size of the (311) plane of silver nanoparticles is 1.5 nm or more. In this specification, the maximum value of the difference between the grain size of the (200) plane, the grain size of the (220) plane, and the grain size of the (311) plane may mean the largest value when all differences between the grain sizes of the said planes are derived. The X-ray diffraction analysis may be performed in the manner according to the evaluation example described below. The maximum value of the difference between the (200) plane grain size, (220) plane grain size and (311) plane grain size of the silver nanoparticles above may be 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. As such, the present invention can infer that the particles grew anisotropically from the large grain size variation of the (200) plane, (220) plane, and (311) plane of the nanoparticles.

[0038] In the present invention, the silver nanoparticles have, for example, a BET specific surface area of ​​6 m² 2It may be characterized as being / g or less. The BET specific surface area of ​​the silver nanoparticles may be measured in the manner according to the evaluation example described below. In the present invention, in another example, the silver nanoparticles have a BET specific surface area of ​​5.5 m² 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 It may be greater than / g. The larger the BET specific surface area of ​​the particle, the higher the likelihood of increased reactivity with other surrounding substances; therefore, conventionally, silver nanoparticles were introduced in a spherical shape known to have a large BET specific surface area to increase 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 compared to conventional spherical silver nanoparticles. Although the exact reason has not been revealed, 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 a high surface energy, which contributes to increased reactivity with lithium ions. In this specification, the term "neck" may refer to a recessed portion relative to adjacent portions in anisotropic silver nanoparticles.

[0039] In the present invention, the silver nanoparticles may be characterized by having an average pore size of, for example, 40 nm or more. In this specification, the average pore size of the silver nanoparticles does not refer to the average pore size of the pores contained within the silver nanoparticles themselves, but may refer to the average size of the pores formed between the particles when the silver nanoparticle(s) are packed in the manner according to the evaluation example described below. In this 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 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.

[0040] In the present invention, the silver nanoparticles, for example, have a total pore volume of 0.065 cm³ 3 It may be characterized as being greater than / g. In this specification, the total pore volume of the silver nanoparticles does not refer to the total volume of pores contained within the silver nanoparticles themselves, but may refer to the total volume of pores formed between the particles when the silver nanoparticle(s) are packed in the manner according to the evaluation example described below. In another example, the total pore volume of the silver nanoparticles of the present invention is 0.067 cm² 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 It may be less than / g.

[0041] In accordance with the present invention, the non-cathode coating layer comprises silver nanoparticles having the characteristics described above, so the reactivity between the silver nanoparticles and lithium ions and the lithium ion conductivity are excellent, and the distribution characteristics of the silver nanoparticles are excellent even after charging and discharging, thereby enabling the uniformization of the resistance distribution within the battery and effectively controlling the growth of lithium dendrites. Accordingly, the all-solid-state battery of the present invention can have excellent capacity retention rate, particularly at high rates, and excellent lifespan characteristics.

[0042] In the present invention, the amorphous carbon may be one or more selected from the group consisting of, for example, carbon black, acetylene black, furnace black, Ketjen black, and graphene.

[0043] In the present invention, the average particle size of the primary particles of the amorphous carbon may be characterized as, for example, less than 100 nm. The average particle size of the primary particles is the volume-based average particle size (D 50It may mean ). The average particle size of the primary particle may be measured, for example, by TEM, but is not limited thereto and may be measured by a known method commonly used in the industry. In other examples, the average particle size of the primary particle of the amorphous carbon may be 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 controls the average particle size of primary particles of amorphous carbon to the range described above, thereby reducing the occurrence of cracks during charging of an all-solid-state battery and improving the battery's lifespan, and further improves performance by providing a pathway through which lithium ions can move efficiently.

[0044] The all-solid-state battery of the present invention, by including amorphous carbon having the above-mentioned characteristics in the anode coating layer, can transfer lithium ions supplied from the positive electrode direction during battery charging to the negative electrode current collector where negative charges are supplied, thereby enabling a lithium metal layer to be uniformly formed between the anode coating layer and the negative electrode current collector.

[0045] The above amorphous carbon may be included in an amount of 40 parts by weight or more based on 100 parts by weight (dry weight) of the anode coating layer, for example. In other examples, the above 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 based on 100 parts by weight (dry weight) of the anode coating layer, or in an amount of 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.

[0046] The above-described anode-free coating layer may be characterized by containing the silver nanoparticles in an amount ranging from 10 to 50 parts by weight relative to 100 parts by weight of amorphous carbon, for example. In other examples, the all-solid-state battery of the present invention may contain the silver nanoparticles in an amount of 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 relative to 100 parts by weight of amorphous carbon, or in an amount of 45 parts by weight or less, 40 parts by weight or less, or 35 parts by weight or less. By introducing the amorphous carbon together with the silver nanoparticles as described above, the all-solid-state battery of the present invention can provide an all-solid-state battery having excellent cycle characteristics.

[0047] The above-mentioned non-cathode 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).

[0048] The particle size of the above lithium-affinity element may be, for example, within a range of 10 to 1000 nm. The above 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 above lithium-affinity element may be 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, but is not limited thereto.

[0049] The non-cathode coating layer of the present invention may further include, for example, a binder. For example, a water-based binder, an organic binder, or a combination thereof may be used as the binder. For example, the binder may be polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinylidene fluoride, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer comprising ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene, fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylate styrene-butadiene rubber, epoxy resin, nylon, or a combination thereof. For example, the water-based binder may be styrene-butadiene rubber, carboxymethylcellulose, or a combination thereof. For example, polytetrafluoroethylene, polyvinylidene fluoride, or a combination thereof may be used as the above organic binder.

[0050] The binder may be characterized by being included in a range of 1 to 20 parts by weight relative to 100 parts by weight of amorphous carbon, for example. The weight ratio of the binder to the amorphous carbon may refer to 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 relative to 100 parts by weight of amorphous carbon, 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.

[0051] In the present invention, by controlling the weight ratio between the compositions included in the anode-free coating layer as described above, an all-solid-state battery having excellent performance and lifespan characteristics can be provided.

[0052] In the present invention, the non-cathode coating layer may further comprise, for example, a solvent. In this specification, the meaning of the non-cathode coating layer further comprising a solvent may mean that a solvent is used during the manufacturing process of the non-cathode coating layer, and may not mean that the non-cathode coating layer finally manufactured through drying, etc., contains a solvent. Water, N-methylpyrrolidone (NMP), etc., may be used as the solvent.

[0053] In the present invention, the non-cathode coating layer may further include, for example, other additives. As long as it does not impede the purpose of the present invention, fillers, coating agents, dispersants, ion conductivity aids, etc. used in conventional all-solid-state batteries may be used without limitation as other additives.

[0054] In the present invention, the non-cathode coating layer can be manufactured, for example, by applying and drying a slurry in which the material constituting the non-cathode coating layer is dispersed onto a cathode current collector.

[0055] In the present invention, the thickness of the non-cathode 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 active material layer described later. The thickness of the non-cathode coating layer may be, for example, within a range of 1 to 20 μm, 5 to 18 μm, or 9 to 15 μm. By controlling the thickness of the non-cathode coating layer as described above, the breakdown of the non-cathode coating layer by lithium dendrites formed between the non-cathode coating layer and the negative current collector described later can be controlled, thereby improving cycle characteristics, improving energy density, and reducing the internal resistance of the all-solid-state battery.

[0056] The cathode-free coating layer of the present invention may, for example, have a porosity in the range of 50 to 80%. The porosity of the cathode-free coating layer may be measured in a known manner. In other examples, the porosity of the cathode-free coating layer may be 55% or more, 60% or more, or 65% or more, or 75% or less, or 70% or less, but is not limited thereto.

[0057] The above anode may include, for example, an anode current collector and / or an anode active material layer.

[0058] The above positive current collector may be a known metal that can be used as a current collector for an all-solid-state battery. The above positive 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 current collector may be omitted depending on the case.

[0059] The above positive active material layer may include, for example, a positive active material, a solid electrolyte, a binder and / or a conductive material.

[0060] The above-mentioned positive electrode active material reversibly absorbs and desorbs lithium ions. The positive electrode active material may be, for example, 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, and lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but is not limited thereto; any material used as a positive electrode active material in the relevant technical field may be used. The positive electrode active materials may be used individually or in a mixture of two or more types.

[0061] The above lithium transition metal oxide is, for example, Li a A 1-b B b D2 (wherein 0.90≤a≤1, and 0≤b≤0.5); Li a Ni 1-b-c Co b B c O 2-α F2(wherein 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(wherein the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a MnG b O2(wherein the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a Mn2G b O4(wherein 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(wherein 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni b E c G d O2(wherein 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(wherein the above equation, 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 (wherein the above equation, 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 such a 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; and J may be V, Cr, Mn, Co, Ni, Cu, or a combination thereof. As a positive electrode active material, a compound having a coating layer added to the surface of such a compound may be used, or a mixture of the compound described above and the compound having a coating layer added may be used. A coating layer added to the surface of such compounds may contain, for example, a lithium ion conductive oxide. The lithium ion conductive oxide is, for example, LiNbO3, Li4Ti5O 12 Examples include Li3PO4, but are not limited thereto. The compounds forming this coating layer may be amorphous or crystalline. Methods for forming the coating layer may include, for example, spray coating or immersion methods, but can be selected without limitation as long as they do not adversely affect the physical properties of the cathode active material.

[0062] 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 the metal leaching of the cathode active material in the charged state. Accordingly, the cycle characteristics of the all-solid-state battery in the charged state may be improved.

[0063] The shape of the above-mentioned positive electrode active material may be a particle shape, for example, a sphere, an elliptical sphere, etc. The particle size of the positive electrode active material is not particularly limited and must be within a range applicable to the positive electrode active material of a conventional all-solid-state secondary battery. The content of the positive electrode active material is also not particularly limited and must be within a range applicable to the positive electrode of a conventional all-solid-state secondary battery.

[0064] The solid electrolyte included in the above-mentioned 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-mentioned positive electrode active material layer may be a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a phosphoric acid-based solid electrolyte, or a halide-based solid electrolyte, but is not limited thereto and may be any that is commonly used in all-solid-state batteries.

[0065] The solid electrolyte included in the above positive active material layer may, for example, have a smaller average particle size compared to the solid electrolyte included in the solid electrolyte layer. For example, the average particle size of the solid electrolyte included in the positive 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.

[0066] The binder included in the above positive active material layer may be, for example, acrylonitrile butadiene rubber (ABR), butadiene rubber (BR), styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc.

[0067] The conductive material included in the above positive active material layer may be, for example, graphite, carbon black, acetylene black, kezen black, carbon fiber, or metal powder.

[0068] In addition to the above, the positive active material layer may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids, and these additives may be used without limitation as long as they are known materials generally used in electrodes of all-solid-state batteries.

[0069] The above solid electrolyte layer may include, for example, a sulfide-based solid electrolyte. The above sulfide-based solid electrolyte is, 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 It may be one or more selected from (0≤x≤2). Sulfide-based solid electrolytes can be manufactured by processing starting materials, such as Li2S or P2S5, by methods such as melt quenching or mechanical milling. Additionally, heat treatment may be performed after such processing. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. In the present invention, the sulfide-based solid electrolyte may, for example, include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the above-mentioned sulfide-based solid electrolyte materials.

[0070] 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 comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0071] The density of the above-mentioned azyrodite-type solid electrolyte may be, for example, 1.5 to 2.0 g / cc. Since the above-mentioned azyrodite-type solid electrolyte has a density of 1.5 g / cc or higher, the internal resistance of the all-solid-state secondary battery is reduced, and penetration of the solid electrolyte by Li can be effectively suppressed.

[0072] The elastic modulus of the above solid electrolyte may be, for example, 15 to 45 GPa.

[0073] The above-mentioned 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 above-mentioned positive active material layer and / or negative electrode coating layer, but is not limited thereto and any binder used in the relevant technical field may be possible. The binder included in the solid electrolyte layer may be the same as or different from the binder included in the aforementioned positive active material layer and / or negative electrode coating layer.

[0074] For the above-mentioned negative electrode current collector, known metals that can be used as current collectors for all-solid-state batteries may be used. For example, the above-mentioned negative electrode current collector may be a material that does not form alloys or compounds with lithium. For example, the above-mentioned negative electrode current collector may be 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; any material used as an electrode current collector in the relevant technical field may be used as long as it does not impede the purpose of the present invention. The above-mentioned negative electrode current collector may be composed of one of the metals described above, or may be composed of an alloy of two or more metals or a coating material. The above-mentioned negative electrode current collector may be in the form of a plate, mesh, or foil, for example, but is not limited thereto.

[0075] The all-solid-state battery of the present invention may further include, by charging, a metal comprising lithium or a lithium alloy and / or a metal (layer) thereof between, for example, the negative electrode current collector and the non-negative electrode coating layer and / or within the non-negative electrode coating layer. The lithium alloy may, for example, be a lithium-silver alloy, and in other examples, may be 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 alloy used as a lithium alloy in the art is possible. The metal or metal layer included between, and / or within, the negative electrode current collector and the non-negative electrode coating layer may be composed of one of these alloys or lithium, or may be composed of various types of alloys.

[0076] The thickness of the metal layer containing the lithium or lithium alloy may be, for example, within the 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. It is necessary to control the thickness as above so that the metal layer can perform its role as a lithium reservoir effectively and improve cycle characteristics.

[0077] The above metal layer may be formed, for example, by precipitation between the negative current collector and the non-negative coating layer and / or within the non-negative coating layer through charging after assembly of the all-solid-state battery. When a metal layer is formed between the negative current collector and the non-negative coating layer and / or within the non-negative coating layer through charging after assembly of the all-solid-state battery, these regions may be, for example, lithium-free regions that do not contain lithium in the initial state or after discharge state of the all-solid-state battery.

[0078] The all-solid-state battery of the present invention may be characterized, for example, having a 1.0C capacity retention rate relative to a 0.1C capacity of 88% or more. The 1.0C capacity retention rate relative to a 0.1C capacity may be measured in the manner according to the 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 a 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 may be 99.9% or less, 99% or less, 98% or less, or 97% or less, although the upper limit is not particularly limited.

[0079] The all-solid-state battery of the present invention may be characterized, for example, having a 0.33C capacity retention rate relative to a 0.1C capacity of 98% or more. The 0.33C capacity retention rate relative to a 0.1C capacity may be measured in the manner according to the 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 a 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 may be 99.9% or less or 99.5% or less, although the upper limit is not specifically limited.

[0080] The all-solid-state battery of the present invention may be characterized, for example, having a 0.5C capacity retention rate relative to a 0.1C capacity of 96% or more. The 0.5C capacity retention rate relative to a 0.1C capacity may be measured in the manner according to the 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 a 0.1C capacity of 96.5% or more, 97% or more, 97.5% or more, or 98% or more, and the upper limit may be 99.9% or less, 99% or less, or 98% or less, although the upper limit is not particularly limited.

[0081] In the following, the present invention is described in detail with reference to examples to specifically explain the disclosure of the present invention as described above and the intended functions and effects of the present invention. However, the examples may be modified in various different forms, and the scope of this specification is not to be interpreted as being limited only to these examples. It is emphasized that the examples are provided to represent the present invention and to explain it more specifically to those skilled in the art.

[0082] Example.

[0083] (cathode)

[0084] 6 g of carbon black (average particle size 41 nm), 2 g of anisotropic silver (Ag) nanoparticles, 9.33 g of PVdF solution (solid content 6%), and 7.19 g of NMP solution were placed in a Thinky mixer container and mixed multiple times at 2000 rpm for 3 minutes. Subsequently, 5 g of NMP solution was added, and mixing was performed 5 times at 2000 rpm for 3 minutes to prepare a cathode-free coating layer slurry. Next, the slurry was coated onto a SUS foil with 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. Through this process, a cathode was obtained in which a cathode-free coating layer with a thickness of 14.0 μm and a porosity of 67.1% was formed on the SUS foil.

[0085] (anode)

[0086] LiNi as the positive active material 0.8 Co 0.15 Mn 0.05O2 (NCM), Li6PS5Cl (an argyrodite-type crystal) as the solid electrolyte, polytetrafluoroethylene (Teflon binder, DuPont) as the binder, and carbon nanofiber (CNF) as the conductive material were prepared. Subsequently, these materials were mixed in a weight ratio of positive active material : solid electrolyte : conductive material : binder = 84 : 15 : 0.2 : 1.2, and the mixture was formed into a large sheet to fabricate a positive electrode sheet. Furthermore, the positive electrode was fabricated by pressing this positive electrode sheet onto an 18 µm thick aluminum foil positive current collector. The initial charge capacity of the positive electrode (charge capacity at the first cycle) was approximately 20 mAh at a 4.25 V charge. The weight of the positive electrode was approximately 110 mg (approx. 203 mAh / g per weight of active material).

[0087] (Solid electrolyte layer)

[0088] The solid electrolyte layer used contained Li6PS5Cl solid electrolyte.

[0089] (Solid-state battery)

[0090] An all-solid-state battery was fabricated by stacking a positive electrode, a solid electrolyte, and a negative electrode and sealing them in a pouch under vacuum. Here, parts of the positive current collector and the negative current collector were protruded outward from the pouch to maintain the vacuum of the battery. These protrusions served as the positive and negative terminals. Additionally, this all-solid-state battery was subjected to hydrostatic pressure treatment at 500 MPa for 30 minutes. By performing this hydrostatic pressure treatment, the characteristics as a battery are significantly improved.

[0091] Comparative example.

[0092] An all-solid-state battery was obtained by forming a cathode on a SUS foil having a non-cathode coating layer with a thickness of 16 μm and a porosity of 67.1% in the same manner as in the example, except that spherical silver nanoparticles (DF-SLN-002, Dowa) (average particle size 60 nm) were used instead of anisotropic silver nanoparticles when manufacturing the cathode.

[0093] Evaluation Example 1. Silver nanoparticle shape

[0094] The silver nanoparticles used in each of the examples and comparative examples were mixed with an ethanol solution to perform sonication and dispersed for more than 1 hour, after which the dispersion was applied to a silicon wafer (Si wafer), dried, and SEM images were observed. As a result, it was confirmed that, unlike the spherical silver nanoparticles of the comparative example, the silver nanoparticles of the example were anisotropic (Figs. 2 and 3).

[0095] Evaluation Example 2. Distribution characteristics of silver nanoparticles and amorphous carbon

[0096] Samples were prepared by activating the all-solid-state batteries (pouch-type monocells) of the examples and comparative examples twice at an operating voltage range of 4.3V-3.0V and an operating temperature of 60℃, and then performing charge-discharge cycles once each at rate limits of 0.33C, 0.5C, 1.0C, and 0.1C, followed by one charge-discharge cycle each at a current density of 0.33C. For the samples, cross-sections of the all-solid-state batteries excluding the pouch were fabricated by Cooling Cross-section Polishing (ion milling) under an Ar atmosphere and 120 μA conditions, and the distribution of the anode / electrolyte / cathode and changes in the interface were confirmed using SEM / EDS (Fig. 4). In addition, the distribution of amorphous carbon and silver nanoparticles within the anode-free coating layer was confirmed in more detail through backscattered electron (BSE) measurements. As the higher the atomic number, the more backscattered electrons are generated, so silver (atomic number: 47) appears as a brighter point than carbon (atomic number: 6), and carbon becomes a dark point (Fig. 5). As a result, in both the example and the comparative example, lithium-alloy precipitation and restoration to the anode occurred during a single charge-discharge cycle, and it was confirmed that the interface between the anode / solid electrolyte layer / anode-free coating layer was well maintained. However, in the case of the example, the distribution was similar to the initial anode-free coating layer even after a single charge-discharge cycle, whereas in the comparative example, the silver nanoparticles appearing as bright points failed to maintain the initial distribution of the anode-free coating layer and were distributed skewed toward the first section in the direction of the cathode current collector (Figs. 4 and 5).

[0097] Meanwhile, the all-solid-state batteries (pouch-type monocells) of the examples and comparative examples were activated twice at an operating voltage range of 4.3V-3.0V and an operating temperature of 60℃, and charged and discharged once each at rate limits of 0.33C, 0.5C, 1.0C, and 0.1C, respectively, and then charged and discharged 166 times and 147 times, respectively, at a current density of 0.33C to prepare samples. For the samples, a cross-section of the all-solid-state battery excluding the pouch was fabricated by Cooling Cross-section Polishing (ion milling) under conditions of 120 μA in an Ar atmosphere, and after taking SEM images and converting them into black and white images, the area ratio was calculated by distinguishing the silver nanoparticle region and the remaining region for each section of the non-anode 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 (top) and the solid electrolyte (bottom) in the black-and-white converted SEM image 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 at level 255 was designated as the silver nanoparticle region (indicated in red), and the region at levels 96 to 105 was designated as the remaining region (indicated in green). As a result, in the example, when divided into two, 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% and the area ratio of silver nanoparticles in the second section (A2) was 4%, so A2 / A1 was 1.33 (Fig. 6); and when divided into three, the area ratio of silver nanoparticles in the first section (A1') was 3% and the area ratio of silver nanoparticles in the second section (A2') and the area ratio of silver nanoparticles in the third section (A3') was 6%, so (A2'+A3') / A1' was 2 (Fig. 7). On the other hand, in the comparative example, when divided into two, the area ratio of silver nanoparticles in the first section (A1) was 9% and the area ratio of silver nanoparticles in the second section (A2) was 3%, so A2 / A1 was 0.It was 33 (Fig. 8), and when divided into three parts, the area ratio of silver nanoparticles in the first section (A1') was 10%, and the area ratio of silver nanoparticles in the second section (A2') and the area ratio of silver nanoparticles in the third section (A3') was 3%, so (A2'+A3') / A1' was 0.3 (Fig. 9). As such, even after performing more cycles in the all-solid-state battery of the example compared to the comparative example, the distribution of silver nanoparticles after discharge was more uniform compared to the comparative example.

[0098] Through this, it can be seen that when anisotropic silver nanoparticles such as those in the example are included in the non-cathode coating layer, alloying between lithium ions and silver can be achieved more efficiently, and the resistance distribution within the battery can also be homogenized, thereby enabling excellent reversibility (efficiency, rate capability, and lifespan).

[0099] Evaluation Example 3. XRD (X-ray Diffraction) Analysis of Silver Nanoparticles

[0100] 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 with a voltage / current of 40 kV / 30 mA. The results are shown in Fig. 10 and Table 1 below.

[0101] As a result of checking the half-width of each face peak of the silver nanoparticles, it was found that the example and the comparative example had a difference of 0.01 or more in half-width of all (111), (200), (220) and (311) faces.

[0102] In addition, as a result of checking the grain size of each of the above planes, the silver nanoparticles of the example had grain sizes of 15 to 18.8 nm in 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 grain sizes of 14.7 to 15.7 nm in the (200) plane, (220) plane, and (311) plane, with a difference of about 1 nm between the maximum and minimum values. Through this, it can be seen that the silver nanoparticles of the example grew anisotropically.

[0103]

[0104] Evaluation Example 4. BET Analysis

[0105] The specific surface area and pore characteristics of the silver nanoparticles in the examples and comparative examples were measured according to the commonly used BET method (Brunauer, Emmett, and Teller method). Specifically, the specific surface area of ​​amorphous carbon was, at 298K, when the residual pressure of each sample was 10 -3 After out-gassing for about 2 hours until torr is reached, the amount of N2 gas adsorbed at 77K was measured using a Micromeritics, ASAP 2460 instrument to determine the surface adsorption properties of the silver nanoparticles S BET Micropore development and S BJH As a result, the medium-term growth was analyzed and derived.

[0106]

[0107] (In Table 2, Vm represents the total pore volume per unit weight of the sample)

[0108] Evaluation Example 5. Dose Retention Rate

[0109] The all-solid-state batteries (pouch-type monocells) of the examples and comparative examples were charged at an operating voltage range of 4.3V-3.0V and an operating temperature of 60℃ under conditions of 0.1C, 4.3V CC / CV, and 0.05C cut-off, and discharged under conditions of 0.1C, 3.0V, CC. After two activation cycles, the capacity retention rate was measured during rate capability evaluation once each at current densities of 0.33C, 0.5C, 1.0C, 0.1C, and 0.33C.

[0110] As a result, the capacity retention rates of the examples and comparative examples were confirmed as shown in Table 3 and Figure 11 below. As such, it can be seen that the capacity retention rate of the examples was generally superior to that of the comparative examples, and in particular, the capacity retention rate at high rates (1.0C) was significantly superior.

[0111]

[0112] (In Table 3, the 0.1C capacity refers to the capacity after the above 2 activations.)

[0113] Evaluation Example 6. Life characteristics

[0114] The all-solid-state batteries (pouch-type monocells) of the examples and comparative examples were activated twice at an operating voltage range of 4.3V-3.0V and an operating temperature of 60℃, and charged and discharged once each at rate limits of 0.33C, 0.5C, 1.0C, and 0.1C, and then the capacity retention rate according to the cycle was measured at a current density of 0.33C.

[0115] As a result, the embodiment showed an overall superior capacity retention rate for each cycle compared to the comparative example. In addition, while the comparative example showed a sharp drop in capacity retention rate after about 75 cycles and then short-circuited after about 130 cycles, the embodiment maintained a gradual decrease in capacity retention rate over the cycle and operated without short-circuiting for 300 cycles (Fig. 12).

Claims

Claim 1 An all-solid-state battery using lithium or a lithium alloy as a negative electrode active material, comprising a positive electrode, a solid electrolyte layer, a negative electrode coating layer, and a negative electrode current collector, wherein the negative electrode coating layer comprises amorphous carbon and silver nanoparticles, and the silver nanoparticles are anisotropic particles including a neck, and wherein, when the negative electrode coating layer is divided into two equal parts in the thickness direction and sequentially referred to as a first section and a second section starting from the section closest to the negative electrode current collector, the ratio (C2 / C1) of the content of silver nanoparticles (C1) contained in the first section to the content of silver nanoparticles (C2) contained in the second section after charging and discharging is within the range of 0.4 to 2. Claim 2 An all-solid-state battery according to claim 1, wherein the non-cathode coating layer is divided into three equal parts in the thickness direction, sequentially referred to as the 1' section, the 2' section, and the 3' section starting from the section closest to the negative current collector, and the ratio of the sum of the contents of silver nanoparticles (C2'+C3') contained in the 2' section and the 3' section ((C2'+C3') / C1') to the content of silver nanoparticles contained in the 1' section after charging and discharging is within the range of 0.4 to 5. Claim 3 delete Claim 4 A solid-state battery according to claim 1, characterized in that the maximum difference between the (200) plane grain size, (220) plane grain size, and (311) plane grain size of the silver nanoparticles is 1.5 nm or more. Claim 5 In claim 1, the BET specific surface area of ​​the silver nanoparticles is 6 m² 2 All-solid-state battery characterized by having a value of / g or less. Claim 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. Claim 7 In claim 1, the total pore volume of the silver nanoparticles is 0.065 cm³ 3 All-solid-state battery characterized by having a value of / g or more. Claim 8 A solid-state battery according to claim 1, characterized in that the amorphous carbon is one or more selected from the group consisting of carbon black, acetylene black, furnace black, Ketjen black, and graphene. Claim 9 An all-solid-state battery according to claim 1, characterized in that the silver nanoparticles are included in a range of 10 to 50 parts by weight per 100 parts by weight of amorphous carbon. Claim 10 A solid-state battery according to claim 1, characterized in that the non-cathode coating layer further comprises a binder. Claim 11 An all-solid-state battery according to claim 1, characterized in that the solid electrolyte layer comprises a sulfide-based solid electrolyte. Claim 12 In claim 11, 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 being one or more selected from (0≤x≤2). Claim 13 An all-solid-state battery according to claim 1, characterized in that the 1.0C capacity retention rate relative to the 0.1C capacity is 88% or higher.

Images