All-solid-state battery including negative electrode having suppressed volume expansion in vertical and horizontal directions and method of manufacturing same

Abstract

Disclosed are an all-solid-state battery including a negative electrode having suppressed volume expansion in a vertical direction and a horizontal direction, and a method of manufacturing the same, in which a buffer layer is interposed between a negative electrode current collector and a solid electrolyte layer to suppress volume expansion of the negative electrode in the vertical direction and the horizontal direction. This configuration prevents deterioration in battery characteristics caused by volume changes during charging and discharging, thereby improving efficiency, durability, and resistance characteristics of the all-solid-state battery.

Description

Technical Field

[0001] The present application relates to an all-solid-state battery including an anode with suppressed volume expansion in the vertical and horizontal directions and a method for manufacturing the same. A buffer layer can be inserted between the anode current collector and the solid electrolyte layer to suppress the volume expansion of the anode in the vertical and horizontal directions. This arrangement prevents the deterioration of battery characteristics caused by volume changes during the charging and discharging process of the all-solid-state battery, thereby improving the efficiency, durability, and resistance characteristics of the all-solid-state battery. Background Art

[0002] An all-solid-state battery that has attracted attention as a next-generation secondary battery includes a laminate in which an anode current collector, an anode layer, a solid electrolyte layer containing a solid electrolyte, a cathode layer, and a cathode current collector are stacked in this order.

[0003] Generally, all-solid-state batteries use a negative electrode layer in the form of a composite of an active material (graphite) and a solid electrolyte to ensure ionic conductivity in the negative electrode layer. However, since a solid electrolyte is added to the negative electrode layer, the proportion of the negative electrode active material is reduced. Therefore, the energy density of all-solid-state batteries may be reduced compared to lithium-ion batteries using electrolyte solutions.

[0004] To improve the energy density of these all-solid-state batteries, recent research has also focused on the application of metallic lithium. However, there are still many obstacles to overcome for commercialization, ranging from research technical issues such as interfacial bonding and dendrite growth to industrial technical issues such as cost and scalability.

[0005] Recently, research on lithium energy storage type anode-less batteries has also been conducted, in which the anode is omitted and lithium (Li) is directly deposited on the anode current collector.

[0006] Specifically, it has been reported that a negative electrode layer formed of an Ag-C composite material can be used to deposit (store) Li. In this negative electrode based on the Ag-C composite layer, during the charging process, Li from the positive electrode layer moves to the negative electrode layer and is deposited (stored) between the Ag-C composite layer and the negative electrode current collector, resulting in volume expansion of the negative electrode. During the discharge process, the stored Li returns to the positive electrode layer, resulting in volume shrinkage of the negative electrode. However, as the charging and discharging process is repeated, the volume expansion and contraction of each electrode is also repeated, and the pressure applied to each electrode and composite layer will produce differences. Therefore, interfacial contact defects will be generated between each electrode and the composite layer, the battery resistance will increase, or Li will be unevenly deposited, resulting in poor battery performance.

[0007] To reduce volume expansion or contraction of each electrode during charge and discharge, a thick gasket configured to compensate for volume expansion during battery operation is sometimes used, but when stacked batteries are implemented, it is difficult to compensate for volume expansion of each battery.

[0008] The above information disclosed in this Background section is only for enhancement of understanding of the background technology of this application and therefore it may contain information that does not constitute the prior art that is already known in this country to a person skilled in the art. Summary of the Invention

[0009] The present application aims to solve the above-mentioned problems associated with the prior art, and the purpose of the present application is to prevent the deterioration of electrochemical characteristics by minimizing the volume change of the negative electrode layer during the charging and discharging process of the all-solid-state battery.

[0010] In particular, due to the characteristics of an all-solid-state battery operating at a specified pressure, lithium may be deposited at the edge of the negative electrode layer when the battery is charged. When the battery continues to charge and discharge in a state where lithium is deposited at the edge of the negative electrode layer, the voltage may be concentrated at the edge, the deposition of lithium may be accelerated, and the deterioration of the electrochemical characteristics of the battery may be aggravated. Therefore, in one aspect, the present application aims to provide an all-solid-state battery that can control not only the volume expansion of the negative electrode layer in the vertical direction, but also the volume expansion of the negative electrode layer in the horizontal direction.

[0011] The purpose of this application is not limited to the above purpose. The purpose of this application will become clear from the following description and can be achieved by the methods and combinations thereof described in the embodiments.

[0012] In one aspect, the present application provides an all-solid-state battery, comprising a negative electrode collector, a buffer layer, a solid electrolyte layer, a positive electrode active material layer and a positive electrode collector, wherein the buffer layer is located on the negative electrode collector, the solid electrolyte layer comprises a solid electrolyte and is located on the buffer layer, the positive electrode active material layer comprises a positive electrode active material and is located on the solid electrolyte layer, and the positive electrode collector is located on the positive electrode active material layer, wherein the buffer layer comprises carbon flakes, the carbon flakes comprise oriented carbon materials, and the oriented carbon materials are aligned to form a predetermined angle with the negative electrode collector.

[0013] In various aspects, preferably, the lithiophilic metal material (eg, lithiophilic metal particles) is associated with (eg, attached to or incorporated into) the aligned carbon material.

[0014] In a preferred embodiment, the aligned carbon material may include vertically aligned carbon nanotubes (VA-CNTs).

[0015] In another preferred embodiment, the length of the aligned carbon material may be from about 4 μm to about 60 μm.

[0016] In another preferred embodiment, the predetermined angle may be 60° to 90°.

[0017] In another preferred embodiment, the lithiophilic metal material (e.g., lithiophilic metal particles) may include one selected from the group consisting of silver (Ag), gold (Au), magnesium (Mg), aluminum (Al), indium (In), silicon (Si), manganese (Mn), tin (Sn), bismuth (Bi), zinc (Zn), germanium (Ge), platinum (Pt), antimony (Sb), and combinations thereof.

[0018] In another preferred embodiment, the buffer layer may have a thickness of about 4 μm to about 50 μm.

[0019] In another preferred embodiment, the buffer layer may have a porous structure, and the porosity of the buffer layer may be about 50% or more.

[0020] In another preferred embodiment, the buffer layer may have a weight ratio of the lithiophilic metal particles to the carbon flakes of about 1:5 to about 1:15.

[0021] In another preferred embodiment, when the all-solid-state battery is in a fully charged state (SoC is 100), the thickness of the lithium layer including lithium deposited in the buffer layer may be equal to or less than the thickness of the buffer layer.

[0022] In another preferred embodiment, the thickness of the buffer layer when the all-solid-state battery is in a fully charged state (SoC is 100) and the thickness of the buffer layer when the all-solid-state battery is in a fully discharged state (SoC is 0) can be the same or substantially the same.

[0023] In another preferred embodiment, in various aspects, the lithiophilic metal material does not form a separate layer. For example, in these aspects, the lithiophilic metal material (e.g., lithiophilic metal particles) can be incorporated into the carbon material.

[0024] In another aspect, the present application provides a method for manufacturing an all-solid-state battery, which comprises immersing a carbon flake containing an oriented carbon material in a solution containing a salt of a lithium-philic metal material (e.g., lithium-philic metal particles) and a reducing agent, stirring the solution containing the carbon flake to attach the lithium-philic metal material to the surface of the oriented carbon material to form a buffer layer, and stacking a negative electrode collector, a buffer layer, a solid electrolyte layer containing a solid electrolyte, a positive electrode active material layer containing a positive electrode active material, and a positive electrode collector.

[0025] In a preferred embodiment, stirring the solution may be performed at a temperature of about 70°C to about 90°C.

[0026] In another preferred embodiment, the reducing agent may include trisodium citrate.

[0027] In another preferred embodiment, the aligned carbon material may include vertically aligned carbon nanotubes (VA-CNTs).

[0028] In another preferred embodiment, the length of the aligned carbon material may be from about 4 μm to about 60 μm.

[0029] In another preferred embodiment, the angle formed by the aligned carbon material and the negative electrode current collector may be about 60° to about 90°.

[0030] In another preferred embodiment, the lithiophilic metal material (e.g., lithiophilic metal particles) may include one selected from the group consisting of silver (Ag), gold (Au), magnesium (Mg), aluminum (Al), indium (In), silicon (Si), manganese (Mn), tin (Sn), bismuth (Bi), zinc (Zn), germanium (Ge), platinum (Pt), antimony (Sb), and combinations thereof.

[0031] In another preferred embodiment, the buffer layer may have a thickness of about 4 μm to about 50 μm.

[0032] In another preferred embodiment, the buffer layer may have a porous structure, and the porosity of the buffer layer may be about 50% or more.

[0033] In another preferred embodiment, the buffer layer may have a weight ratio of the lithiophilic metal particles to the carbon flakes of about 1:5 to about 1:15.

[0034] In another preferred embodiment, when the all-solid-state battery is in a fully charged state (SoC is 100), the thickness of the lithium layer including lithium deposited in the buffer layer may be equal to or less than the thickness of the buffer layer.

[0035] In another preferred embodiment, the thickness of the buffer layer when the all-solid-state battery is in a fully charged state (SoC is 100) and the thickness of the buffer layer when the all-solid-state battery is in a fully discharged state (SoC is 0) can be the same or substantially the same.

[0036] In another preferred embodiment, the lithiophilic metal material (eg, lithiophilic metal particles) may not form a separate layer.

[0037] In other aspects, a vehicle is provided, comprising a battery disclosed herein (including an all-solid-state battery disclosed herein).

[0038] Other aspects and preferred embodiments of the application are discussed below.

[0039] The above-mentioned features and other features of the present application are discussed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and other features of the present application will now be described in detail with reference to certain exemplary embodiments shown in the accompanying drawings, which are given below only by way of example and therefore do not limit the present application, in which:

[0041] Figure 1 A cross-sectional view showing an all-solid-state battery including a buffer layer according to the present application;

[0042] Figure 2 shows the discharge state of the buffer layer according to the present application;

[0043] Figure 3 shows the charge state of the buffer layer according to the present application;

[0044] Figure 4 shows a buffer layer according to another embodiment of the present application;

[0045] Figure 5 is a graph showing voltage curves of the all-solid-state batteries according to the embodiment and the comparative embodiment at the time of initial charge and discharge of the all-solid-state batteries; and

[0046] Figure 6 is a graph showing the results of durability analysis of all-solid-state batteries according to Examples and Comparative Examples.

[0047] It should be understood that the accompanying drawings are not drawn to scale, but rather are slightly simplified representations of various preferred features illustrating the basic principles of the present application. The specific design features of the present application disclosed herein (including, for example, specific dimensions, directions, positions, and shapes) will be determined in part by the specific intended application and use environment.

[0048] In the drawings, reference numbers refer to the same or equivalent parts of the present application throughout the several figures of the drawing. DETAILED DESCRIPTION

[0049] The above-mentioned purpose, other purposes, advantages and features of the present application will become apparent through the description of the embodiments given below with reference to the accompanying drawings. However, the application is not limited to the embodiments disclosed herein and can be implemented in various different forms. The embodiments are provided to make the description of the present invention thorough and to fully convey the scope of the application to those skilled in the art.

[0050] In the accompanying drawings, even if described in different drawings, the same or similar elements are represented by the same reference numerals. In the accompanying drawings, in order to describe more clearly, the size of the structure can be amplified compared to the actual size. In the following description of the embodiment, the terms such as "first" and "second" can be used to describe each element, but these elements are not limited. These terms are only used to distinguish an element from other elements. For example, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element, without departing from the scope and spirit of the present invention. Unless there is a significantly different contextual meaning, a singular expression can include a plural expression.

[0051] In the following description of the embodiments, terms such as "including," "comprising," and "having" will be interpreted as indicating the presence of the features, values, steps, operations, elements, or components described in the specification, or a combination thereof, and do not exclude the presence of one or more other features, values, steps, operations, elements, components, or a combination thereof, or the possibility of adding them. In addition, it will be understood that when a part (such as a layer, film, region, or sheet) is referred to as being "on" another part, the part may be "directly on" the other part, or one or more other parts may be interposed between the two parts. In the same manner, it will be understood that when a part (such as a layer, film, region, or sheet) is referred to as being "under" another part, the part may be "directly under" the other part, or one or more other parts may be interposed between the two parts.

[0052] Unless otherwise stated, all numbers, values and / or expressions used in this specification to represent the amounts of components, reaction conditions, polymer compositions and blends are approximate values, which reflect the various measurement uncertainties that arise when obtaining these values from essentially different things. Therefore, it will be understood that they are all modified by the term "about". Unless otherwise stated or obvious from the context, as used herein, the term "about" is understood to be within the normal tolerance range in the field, for example, within 2 standard deviations of the mean. "About" can be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05% or 0.01% of the specified value. In addition, it should be understood that if a numerical range is disclosed in the specification, unless otherwise stated, the range includes all consecutive values from the minimum value to the maximum value of the range. In addition, if the range involves integers, unless otherwise stated, the range includes all integers from the minimum integer to the maximum integer.

[0053] In the following description of the embodiments, it should be understood that when a range of a variable is described, the variable includes all values within the range (including the endpoints of the range). For example, it will be understood that the range of "5 to 10" includes not only the values of 5, 6, 7, 8, 9, and 10, but also any subranges (e.g., a subrange of 6 to 10, a subrange of 7 to 10, a subrange of 6 to 9, and a subrange of 7 to 9) and any value between the valid integers in the range (e.g., 5.5, 6.5, 7.5, 5.5 to 8.5, and 6.5 to 9). In addition, for example, it will be understood that the range of "10% to 30%" includes not only all integers (including values of 10%, 11%, 12%, 13%...30%), but also includes any sub-ranges (for example, a sub-range of 10% to 15%, a sub-range of 12% to 18% and a sub-range of 20% to 30%) and any value between the valid integers in the range (for example, 10.5%, 15.5% and 25.5%).

[0054] In addition, the terms "unit," "-device," "-component," and "module" described in this specification mean a unit for performing at least one function and operation and can be implemented by hardware components or software components and a combination thereof.

[0055] Although the exemplary embodiments are described as using multiple units to perform the exemplary processes, it should be understood that the exemplary processes can also be performed by one or more modules. Furthermore, it should be understood that the term controller / control unit refers to a hardware device that includes a memory and a processor and is specifically programmed to perform the processes described herein. The memory is configured to store the modules, and the processor is specifically configured to execute the modules, thereby performing one or more processes described further below.

[0056] Furthermore, the control logic of the present application may be embodied as non-transitory computer-readable media on a computer-readable medium, including executable program instructions executed by a processor, controller, or the like. Examples of computer-readable media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards, and optical data storage devices. The computer-readable medium may also be distributed among network-connected computer systems so that the computer-readable medium is stored and executed in a distributed manner, for example, by a telematics server or a controller area network (CAN).

[0057] As used herein, the term "substantially the same" means that the difference between two values does not exceed 10% of a base value (e.g., one of the two values), such as not more than 8% of the base value, not more than 6%, not more than 4%, not more than 2%, not more than 1%, not more than 0.5%, not more than 0.1%, not more than 0.05%, or not more than 0.01%.

[0058] All-solid-state batteries

[0059] In conventional all-solid-state batteries using a composite layer containing Ag-C as the negative electrode layer, the composite layer repeatedly expands and contracts in volume as the battery is charged and discharged. During discharge, the deposited lithium ionizes and migrates to the positive electrode layer, causing the pressure in the composite layer to decrease. This process can lead to contact defects at the interface between the composite layer and the solid electrolyte layer, or between the composite layer and the negative electrode current collector.

[0060] To solve this problem, a technology has been disclosed that involves inserting a carbon nanotube (CNT) sheet between a composite layer and a negative electrode current collector to absorb the volume expansion of the negative electrode layer or the composite layer.

[0061] However, the conventional technology of inserting a carbon nanotube sheet between the negative electrode collector and the composite layer can absorb the volume expansion of the negative electrode collector in the vertical direction to a certain extent, but may not be able to absorb the volume expansion in the horizontal direction. Specifically, when a conventional all-solid-state battery in which the negative electrode layer includes a composite layer and a carbon nanotube sheet is charged, lithium ions migrated from the positive electrode layer are deposited between the composite layer and the carbon nanotube sheet and inside the composite layer and the carbon nanotube sheet. At this time, since the carbon nanotube sheet may not be able to suppress the volume expansion in the horizontal direction, lithium may be irreversibly deposited at the edge of the negative electrode layer. As a result, lithium ions may be lost, the overall structure of the all-solid-state battery may collapse, and the durability of the battery may be reduced. When charging and discharging are continued in this state, lithium dendrites may grow at the interface between the layers and may reduce the durability of the battery, or in severe cases, may cause an internal short circuit of the battery.

[0062] Figure 1 1 is a cross-sectional view showing an all-solid-state battery according to the present application (specifically, an anode-free all-solid-state battery that solves the problems of conventional all-solid-state batteries). Figure 1 According to one embodiment of the present application, an all-solid-state battery may include a negative electrode collector 10, a buffer layer 20, a solid electrolyte layer 30, a positive electrode active material layer 40 and a positive electrode collector 50, wherein the buffer layer 20 is located on the negative electrode collector 10, the solid electrolyte layer 30 contains a solid electrolyte and is located on the buffer layer 20, the positive electrode active material layer 40 contains a positive electrode active material and is located on the solid electrolyte layer 30, and the positive electrode collector 50 is located on the positive electrode active material layer 40.

[0063] The negative electrode current collector 10 may be a conductive plate-shaped substrate. Specifically, the negative electrode current collector 10 may be in the form of a sheet, a film, or a foil.

[0064] The negative electrode current collector 10 may include a material that does not react with lithium. Specifically, the negative electrode current collector 10 may include at least one selected from nickel (Ni), copper (Cu), stainless steel, and a combination thereof.

[0065] The thickness of the negative electrode current collector 10 is not particularly limited and may be, for example, 1 μm to 500 μm.

[0066] Figure 2 is a diagram showing a discharge state of the buffer layer 20 according to the present application, and Figure 3 1 is a diagram showing a charge state of the buffer layer 20 according to the present application. The buffer layer 20 according to the present application comprises a carbon sheet containing an aligned carbon material 21 and lithium-philic metal particles 22 attached to the surface of the aligned carbon material 21, wherein the aligned carbon material 21 is aligned to form a predetermined angle θ with the negative electrode current collector 10.

[0067] In the all-solid-state battery according to the present application, lithium ions released from the positive electrode active material can move to the negative electrode layer (i.e., buffer layer 20) via the solid electrolyte layer 30. These ions can then be deposited in the form of lithium metal from the vicinity of the lithium-philic metal material 22 (e.g., lithium-philic metal particles) that is bound to (e.g., attached to or incorporated into) the oriented carbon material 21. In addition, the deposition of lithium metal can proceed from the lithium-philic metal particles 22 toward the negative electrode current collector 10.

[0068] Here, as will be described below, the oriented carbon material 21 is aligned to be nearly perpendicular to the negative electrode current collector 10 , and thus, the volume expansion of the buffer layer 20 can be suppressed not only in the vertical direction but also in the horizontal direction.

[0069] The aligned carbon material 21 has a specified area so that the lithiophilic metal particles 22 can be attached to the surface of the aligned carbon material 21, and the shape of the aligned carbon material 21 is not particularly limited, and as Figure 2 As shown, it can be cylindrical or fibrous in shape.

[0070] For example, the aligned carbon material 21 may include at least one selected from the group consisting of carbon nanofibers, carbon nanotubes, vapor-grown carbon fibers, and combinations thereof. Furthermore, the aligned carbon material 21 may have electrical conductivity.

[0071] Preferably, the aligned carbon material 21 may include vertically aligned carbon nanotubes (VA-CNTs). Vertically aligned carbon nanotubes (VA-CNTs) may refer to carbon nanotubes and bundles thereof that are aligned at an angle θ close to perpendicular to the negative electrode current collector 10. Here, the term "vertically aligned carbon nanotubes" not only refers to a case where the aligned carbon material 21 forms an angle θ of exactly 90° with the negative electrode current collector 10, but also includes a case where the aligned carbon material 21 is aligned at an angle θ of 60° to 90° to be close to perpendicular to the negative electrode current collector 10, such as Figure 4 shown.

[0072] When the angle θ between the aligned carbon material 21 and the negative electrode current collector 10 is less than 60°, lithium is unevenly deposited, and the volume expansion of the buffer layer 20 may not be effectively suppressed, which may easily deteriorate the performance of the all-solid-state battery.

[0073] In addition, the aligned carbon material 21 can be provided so that individual aligned carbon material units or bundles of aligned carbon material units are arranged at a specified distance within the carbon sheet. Since the aligned carbon material 21 is provided so that individual units or bundles of aligned carbon material are arranged at a specified distance, the carbon sheet and the buffer layer 20 (which includes the aligned carbon material) can have a porous structure.

[0074] Because the carbon sheet and the buffer layer 20 containing the carbon sheet have a porous structure, during the charging process of the all-solid-state battery according to the present invention, lithium ions can be deposited in the form of lithium metal in the space between adjacent aligned carbon material units. Therefore, even if lithium metal is deposited in the buffer layer 20 during the charging process of the all-solid-state battery, the volume change of the lithium metal can be absorbed by the porous structure.

[0075] Preferably, the porous structure of the buffer layer 20 can absorb all volume changes caused by the deposition of lithium. Therefore, when the all-solid-state battery is in a fully charged state (SoC is 100), the thickness T of the buffer layer 20 is b and the thickness T of the buffer layer 20 when the all-solid-state battery is in a fully discharged state (SoC is 0) b Can be the same or substantially the same.

[0076] In one embodiment, the porosity of buffer layer 20 may be 50% or higher. Buffer layer 20 should ensure at least 50% porosity to absorb all volume changes caused by lithium deposition without changing the thickness of buffer layer 20 and allowing uniform lithium deposition.

[0077] The porosity of the buffer layer 20 can be measured, for example, according to the Bruer-Emmett-Teller (BET) method, the mercury (Hg) intrusion method, or ASTM D-2873. Alternatively, the net density of the buffer layer 20 can be calculated from the density (apparent density) of the buffer layer 20, the composition ratio of the materials contained in the buffer layer 20, and the density of each component, and the porosity of the buffer layer 20 can be calculated from the difference between the apparent density and the net density of the buffer layer 20. For example, the porosity can be calculated using the following equation 1.

[0078] [Equation 1]

[0079] Porosity (volume %) = {1-(apparent density / net density)} × 100

[0080] In Equation 1, the apparent density can be calculated by the following Equation 2.

[0081] [Equation 2]

[0082] Apparent density (g / cm 3 ) = (weight of porous buffer layer (g)) / {(thickness of porous buffer layer (cm)) × (area of porous buffer layer (cm) 2 ))}

[0083] Figure 3 The buffer layer 20 is schematically shown when the all-solid-state battery according to the present application is fully charged. When the all-solid-state battery according to the present application is charged, lithium ions released from the positive electrode active material may be deposited in the form of metal near the lithium-philic metal particles 22 located on the negative electrode current collector 10, thereby forming a lithium layer 23.

[0084] Here, when the all-solid-state battery is in a fully charged state (SoC is 100), the thickness T of the lithium layer 23 including the lithium deposited in the buffer layer 20 is Li It can be equal to or less than the thickness T of the buffer layer 20 b Preferably, when the all-solid-state battery is in a fully charged state (SoC is 100), the thickness T of the lithium layer 23 is Li and the thickness T of the buffer layer 20 b Can be the same or substantially the same.

[0085] Due to the characteristic that the all-solid-state battery operates under a predetermined pressure applied in the stacking direction of the all-solid-state battery, when the thickness T of the lithium layer 23 is Li Exceeding the thickness T of the buffer layer 20 b When the all-solid-state battery is charged and discharged continuously in a state where lithium is deposited to the edge of the buffer layer 20, the voltage is concentrated at the edge of the buffer layer 20, the lithium deposition may be accelerated, and the electrochemical characteristics of the all-solid-state battery may be further deteriorated.

[0086] In the all-solid-state battery according to the present application, the thickness T of the lithium layer 23 including the lithium deposited in the buffer layer 20 is Li Equal to or less than the thickness T of the buffer layer 20 b , therefore, lithium can be prevented from being deposited on the edge of the buffer layer 20. In addition, when the thickness T of the lithium layer 23 is 100 under the fully charged state of the all-solid-state battery (SoC is 100), the lithium layer 23 is 100. Li and the thickness T of the buffer layer 20 b At the same time, excellent electrochemical performance in terms of energy density is exhibited, while the volume expansion of the buffer layer 20 in the vertical direction and the volume expansion of the buffer layer 20 in the horizontal direction can be suppressed.

[0087] In one embodiment, the thickness T of the buffer layer 20 is b The thickness T of the buffer layer 20 may be 4 μm to 50 μm. b It can be determined based on the capacity of the all-solid-state battery including the buffer layer 20. For example, when the capacity of a single-plated battery including the buffer layer 20 is 0 mAh / cm 2 Up to 1.0 mAh / cm 2 When the thickness T of the buffer layer 20 is b It can be 4μm to 10μm. When the capacity of a single-plated battery is 1.0mAh / cm 2 Up to 3.0mAh / cm 2 When the thickness T of the buffer layer 20 is b It can be 12μm to 30μm. When the capacity of a single-plated battery is 3.0mAh / cm 2 Up to 5.0 mAh / cm 2 When the thickness T of the buffer layer 20 is b It may be 20 μm to 50 μm.

[0088] When the thickness T of the buffer layer 20 b When the thickness T of the buffer layer 20 is less than 4 μm, the buffer layer 20 may not be sufficient to absorb the volume change caused by lithium deposition, and it may be difficult to suppress the volume expansion in the horizontal direction. b When the thickness exceeds 50 μm, the energy density of all-solid-state batteries may decrease.

[0089] When the angle θ formed by the aligned carbon material 21 and the negative electrode current collector 10 is 90°, the length L of the aligned carbon material 21 and the thickness T of the buffer layer 20 are b When the angle θ formed by the aligned carbon material 21 and the negative electrode current collector 10 is equal to or greater than 60° and less than 90°, the length L of the aligned carbon material 21 and the thickness T of the buffer layer 20 are equal to or greater than 60° and less than 90°. b It can be different.

[0090] In one embodiment, the length L of the aligned carbon material 21 may be 4 μm to 60 μm. When the length L of the aligned carbon material 21 is less than 4 μm, the buffer layer 20 may not be sufficient to absorb the volume change caused by lithium deposition, and it may be difficult to suppress the volume expansion of the buffer layer 20 in the horizontal direction. When the length L of the aligned carbon material 21 exceeds 60 μm, the energy density of the all-solid-state battery may be reduced.

[0091] Furthermore, in one embodiment, the lithiophilic metal particles 22 include one selected from the group consisting of silver (Ag), gold (Au), magnesium (Mg), aluminum (Al), indium (In), silicon (Si), manganese (Mn), tin (Sn), bismuth (Bi), zinc (Zn), germanium (Ge), platinum (Pt), antimony (Sb), and combinations thereof.

[0092] The lithiophilic metal particles 22 may represent a metal element in a particle form that can easily form an alloy with lithium to induce lithium ions. Preferably, the lithiophilic metal particles 22 may include silver (Ag).

[0093] As will be described below, the lithium-philic metal particles 22 may vary depending on the temperature and time required to stir the carbon sheet containing the aligned carbon material 21. However, preferably, the lithium-philic metal particles 22 may not form a separate layer on the surface of the aligned carbon material 21. When the lithium-philic metal particles 22 adhere to the surface of the aligned carbon material 21 to form a layer having a predetermined thickness, the porosity of the buffer layer 20 may decrease. Therefore, it may be difficult to provide a space sufficient to accommodate the lithium metal deposited in the buffer layer 20.

[0094] In one embodiment, the buffer layer 20 may have a weight ratio of the lithiophilic metal particles 22 to the carbon flakes of 1:5 to 1:15.

[0095] When the weight ratio of the lithiophilic metal particles 22 to the carbon flakes of the buffer layer 20 is greater than 1:5, the proportion of the lithiophilic metal particles 22 in the buffer layer 20 may be too high. Specifically, the lithiophilic metal particles 22 may form a separate layer having a predetermined thickness on the surface of the oriented carbon material 21, and thus, it may be difficult to provide a space sufficient to accommodate the lithium metal deposited in the buffer layer 20. In addition, the energy density of the all-solid-state battery may be reduced.

[0096] When the weight ratio of the lithiophilic metal particles 22 to the carbon flakes is less than 1:15, the proportion of the lithiophilic metal particles 22 in the buffer layer 20 may be too small. Specifically, since the lithiophilic metal particles 22 in the buffer layer 20 are insufficient to induce lithium ions, lithium metal may be deposited at the interface between the buffer layer 20 and the solid electrolyte layer 30. In this case, when the all-solid-state battery is repeatedly charged and discharged, the growth of lithium dendrites may be accelerated.

[0097] The solid electrolyte layer 30 may be located between the positive electrode active material layer 40 and the buffer layer 20 , and may include a solid electrolyte having lithium ion conductivity.

[0098] The solid electrolyte may include one selected from an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a polymer electrolyte, and a combination thereof. However, a sulfide-based solid electrolyte having high lithium ion conductivity may be preferably used as the solid electrolyte.

[0099] Sulfide solid electrolytes may include Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are positive numbers, and Z is one of Ge, Zn and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (x and y are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, and In), Li 10 GeP2S 12 etc., without particular limitation.

[0100] Oxide-based solid electrolytes may include perovskite-type LLTO (Li 3x La 2 / 3-x TiO3), phosphate NASICON type LATP (Li 1+x Al x Ti 2-x (PO4)3) etc.

[0101] The polymer electrolyte may include a gel polymer electrolyte, a solid polymer electrolyte, and the like.

[0102] The solid electrolyte layer 30 may further include a binder, which may include butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), and the like.

[0103] The positive electrode active material layer 40 reversibly intercalates and deintercalates lithium ions and may include a positive electrode active material, a conductive material, a binder, etc. In addition, a solid electrolyte may be mixed with the positive electrode active material layer 40.

[0104] The positive electrode active material may be an oxide active material or a sulfide active material.

[0105] The oxide active material may be a rock salt layer-type active material (e.g., LiCoO2, LiMnO2, LiNiO2, LiVO2 or Li 1+x Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2), a spinel-type active material (e.g., LiMn2O4 or Li(Ni 0.5 Mn 1.5 )O4), an inverse spinel-type active material (e.g., LiNiVO4 or LiCoVO4), an olivine-type active material (e.g., LiFePO4, LiMnPO4, LiCoPO4 or LiNiPO4), a silicon-containing active material (e.g., Li2FeSiO4 or Li2MnSiO4), a rock salt layer-type active material in which a part of transition metals are replaced by different types of metals (e.g., LiNi 0.8 Co (0.2-x) Al x O2(0 < x < 0.2)), a spinel-type active material in which a part of transition metals are replaced by different types of metals (e.g., Li 1+x Mn 2-x-y M y O4 (M is at least one of Al, Mg, Co, Fe, Ni or Zn, and 0 < x + y < 2)), or lithium titanate (e.g., Li4Ti5O 12 ).

[0106] The sulfide active material may be Chevrel copper, iron sulfide, cobalt sulfide, nickel sulfide, etc.

[0107] The solid electrolyte mixed with the positive electrode active material layer 40 may be substantially the same as the solid electrolyte included in the solid electrolyte layer 30.

[0108] The conductive material may be carbon black, conductive graphite, acetylene black, carbon fiber, graphene, etc.

[0109] The binder may include butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), etc.

[0110] The positive electrode current collector 50 may be a conductive plate-shaped substrate. Specifically, the positive electrode current collector 50 may be in the form of a sheet or film. The positive electrode current collector 50 may include at least one selected from indium (In), copper (Cu), magnesium (Mg), aluminum (Al), stainless steel, iron (Fe), and combinations thereof. Specifically, the positive electrode current collector 50 may include aluminum foil.

[0111] The thickness of the positive electrode current collector 50 is not particularly limited and may be, for example, 1 μm to 500 μm.

[0112] Hereinafter, a method for manufacturing an all-solid-state battery according to the present application will be described.

[0113] Manufacturing method of all-solid-state battery

[0114] The manufacturing method of the all-solid-state battery according to the present application may include immersing a carbon sheet containing an oriented carbon material 21 in a solution of a salt and a reducing agent containing lithium-philic metal particles 22, introducing the solution of the carbon sheet by stirring to attach the lithium-philic metal particles 22 to the surface of the oriented carbon material 21 to form a buffer layer 20, and stacking a negative electrode collector 10, a buffer layer 20, a solid electrolyte layer 30 containing a solid electrolyte, a positive electrode active material layer 40 containing a positive electrode active material, and a positive electrode collector 50 in sequence.

[0115] Each operation will be described in more detail below.

[0116] First, a carbon sheet comprising an aligned carbon material 21 may be introduced into a solution comprising a reducing agent and a salt of lithiophilic metal particles 22 .

[0117] A salt generally refers to a compound in which a cation and an anion are bonded by electrical attraction. In this specification, when the lithiophilic metal particles 22 are present in the solution in the form of cations, the salt of the lithiophilic metal particles 22 may refer to a compound containing anions that are bonded to the cations by electrical attraction. For example, when the lithiophilic metal particles 22 are silver (Ag) particles, the salt of silver (Ag) may be silver nitrate (AgNO 3 ).

[0118] In one embodiment, the reducing agent may be any compound for reducing the lithiophilic metal particles 22 in the solution in the form of cations without particular limitation. For example, the reducing agent may include trisodium citrate.

[0119] The carbon sheet includes the oriented carbon material 21 and is substantially the same as the carbon sheet of the above-mentioned “all-solid-state battery”, so a detailed description thereof will be omitted.

[0120] After the carbon sheet is immersed in the solution, the cationic lithiophilic metal particles 22 may be reduced by stirring the solution. The reduced lithiophilic metal particles 22 may be dispersed in the solution in a colloidal state (including nanoparticles).

[0121] The equation for the reduction reaction that occurs during stirring of the solution is as follows.

[0122] [Reduction reaction equation]

[0123] mMe n+ +nRed→mMe 0 +nO x

[0124] (Here, Me is the lithiophilic metal and Red is the reducing agent)

[0125] For example, when trisodium citrate is used as the reducing agent and silver (Ag) is used as the lithiophilic metal particles 22 , the following reaction may occur during stirring.

[0126] [Reduction formula]

[0127] 4Ag + +Na3C6H5O7+2H2O→4Ag 0 +C6H8O7+3Na + +H + +O2

[0128] Here, the solution may be stirred at a temperature of 70° C. to 90° C. When the temperature of the solution is stirred is lower than 70° C., the reaction may not occur, or the reduction of silver (Ag) may not be fully performed. When the temperature of the solution is stirred is higher than 90° C., as the reaction temperature increases, the leaching rate of silver (Ag) increases, and it may be difficult to obtain the size or amount of metal particles desired to be obtained in the present application.

[0129] Preferably, stirring the solution may be performed at a temperature of 75° C. to 80° C. When stirring the solution within the above temperature range, metal nanoparticles having a more appropriate amount and size may be reduced on the surface of the aligned carbon material 21 .

[0130] In addition, the solution can be stirred for 30 to 60 minutes. When the stirring time is less than 30 minutes, the reduction of the lithium metal particles may not occur sufficiently. Even when the stirring time exceeds 60 minutes, the leaching rate is similar, so the process efficiency may be reduced.

[0131] When stirring is continued after forming a colloid dispersed in the solution, the lithiophilic metal particles 22 may adhere to the surface of the aligned carbon material 21. Then, the buffer layer 20 can be formed by removing a carbon sheet from the solution, wherein the lithiophilic metal particles 22 adhere to the surface of the aligned carbon material 21.

[0132] In this case, the buffer layer 20 may be formed more efficiently by additionally performing a drying process. In the drying process, the solvent remaining on the surface of the carbon sheet or the buffer layer 20 evaporates, and the drying temperature or drying time is not particularly limited and may be adjusted to a level sufficient to evaporate the solvent.

[0133] After forming the buffer layer 20 through a stirring process and / or a drying process, an all-solid-state battery can be manufactured by sequentially stacking the negative electrode collector 10, the buffer layer 20, the solid electrolyte layer 30 containing a solid electrolyte, the positive electrode active material layer 40 containing a positive electrode active material, and the positive electrode collector 50. Here, the negative electrode collector 10, the solid electrolyte layer 30, the positive electrode active material layer 40, and the positive electrode collector 50 are substantially the same as those of the above-mentioned "all-solid-state battery", and the method of manufacturing the all-solid-state battery by stacking the respective elements can use a stacking method commonly used in the art.

[0134] The all-solid-state battery manufactured according to the manufacturing method of the present application can be substantially the same as the above-mentioned all-solid-state battery. For example, the lithium-philic metal particles 22 used in the manufacturing method according to the present application can include one selected from silver (Ag), gold (Au), magnesium (Mg), aluminum (Al), indium (In), silicon (Si), manganese (Mn), tin (Sn), bismuth (Bi), zinc (Zn), germanium (Ge), platinum (Pt), antimony (Sb), and combinations thereof.

[0135] The aligned carbon material 21 used in the manufacturing method according to the present application may include vertically aligned carbon nanotubes (VA-CNTs).

[0136] The length L of the aligned carbon material 21 used in the manufacturing method according to the present application may be 4 μm to 60 μm.

[0137] The angle θ formed by the aligned carbon material 21 and the negative electrode current collector 10 used in the manufacturing method according to the present application may be 60° to 90°.

[0138] The thickness T of the buffer layer 20 in the manufacturing method of the present application is b It can be 4 μm to 50 μm.

[0139] The buffer layer 20 in the manufacturing method according to the present application may have a porous structure, and the porosity of the buffer layer 20 may be 50% or higher.

[0140] The weight ratio of the lithiophilic metal particles 22 to the carbon flakes of the buffer layer 20 in the manufacturing method according to the present application may be 1:5 to 1:15.

[0141] When the all-solid-state battery manufactured by the manufacturing method according to the present application is in a fully charged state (SoC is 100), the thickness T of the lithium layer 23 including the lithium deposited in the buffer layer 20 is Li It can be equal to or less than the thickness T of the buffer layer 20 b .

[0142] When the all-solid-state battery manufactured by the manufacturing method according to the present application is in a fully charged state (SoC is 100), the thickness T of the buffer layer 20 is b and the thickness T of the buffer layer 20 when the all-solid-state battery is in a fully discharged state (SoC is 0) b Can be the same or substantially the same.

[0143] The lithiophilic metal particles 22 of the all-solid-state battery manufactured by the manufacturing method according to the present application may not form a separate layer.

[0144] Hereinafter, the present application will be described in more detail through the following examples and comparative examples. The following examples and comparative examples are only used to exemplify the present application and are not intended to limit the scope and spirit of the present application.

[0145] Example 1 -VA-CNT+Ag

[0146] (1) A solution was prepared by introducing trisodium citrate as a reducing agent and AgNO3 (which is a salt of lithiophilic metal particles) into DI water as a solvent. A carbon sheet containing vertically aligned carbon nanotubes (VA-CNT, NAWATECHNOLOGIES) was introduced into the solution.

[0147] (2) A carbon sheet in which silver (Ag) particles were attached to the surface of vertically aligned carbon nanotubes (VA-CNTs) was obtained by stirring a solution of vertically aligned carbon nanotubes (VA-CNTs) at a temperature of 80°C and about 300 rpm for 40 minutes. The buffer layer was produced by removing the carbon sheet from the solution and drying the carbon sheet to remove the residual solution.

[0148] (3) An all-solid-state battery was then assembled by sequentially stacking a nickel thin film, a buffer layer, a solid electrolyte layer, a cathode active material layer, and an aluminum thin film. The solid electrolyte layer comprised an argyrodite-type sulfide-based solid electrolyte in the form of a self-supporting thin film without a separate support, and the cathode active material layer comprised an NCM 811-based cathode active material. The all-solid-state battery was used as in Example 1.

[0149] Here, Table 1 lists the specific conditions of the carbon sheets and the lithiophilic metal particles used to form the buffer layer in the process of assembling the all-solid-state battery according to Example 1.

[0150] [Table 1]

[0151]

[0152] Comparative Example 1-AgC

[0153] A composite layer of silver (Ag) particles dispersed on graphite (C) was fabricated without separately synthesizing a buffer layer. An all-solid-state battery was then assembled by sequentially stacking a nickel thin film, a composite layer, a solid electrolyte layer comprising an argyrodite-type sulfide-based solid electrolyte in the form of a self-supporting thin film without a separate support, and an aluminum thin film. The positive electrode active material layer comprised an NCM 811-based positive electrode active material. This all-solid-state battery was designated Comparative Example 1.

[0154] Comparative Example 2-VA-CNT

[0155] An all-solid-state battery was assembled by the same method as in Example 1, except that a carbon sheet containing vertically aligned carbon nanotubes (VA-CNTs) without silver (Ag) attached to its surface (serving as a lithiophilic metal particle) was used as a buffer layer. This all-solid-state battery was designated as Comparative Example 2.

[0156] Comparative Example 3-CNT+Ag

[0157] An all-solid-state battery was assembled by the same method as in Example 1, except that a carbon sheet containing carbon nanotubes (CNTs) having a network structure was used instead of an aligned carbon material in which the carbon material is aligned in one direction. This all-solid-state battery was designated as Comparative Example 3.

[0158] Test Example 1 - Voltage Characteristics Analysis Based on Initial Charge and Discharge

[0159] In order to determine the electrochemical characteristics of the all-solid-state batteries according to the examples and comparative examples, initial charge and discharge were performed at a rate of 0.33 C and a cut-off voltage of 2 V to 4.25 V. The results of this test are shown in Figure 5 and Table 2 below.

[0160] [Table 2]

[0161] Charging (mAh / g) Discharge (mAh / g) efficiency(%) DC-IR(Ω) Example 1 220.3 199.3 90.4 1.74 Comparative Example 1 219.1 195.8 89.3 5.4 Comparative Example 2 173.9 150.9 86.8 11.4 Comparative Example 3 201.4 180.8 90.2 6.3

[0162] refer to Figure 5From Table 2, it can be confirmed that the all-solid-state battery according to Example 1 (wherein the buffer layer comprises a carbon sheet containing vertically aligned carbon nanotubes and silver (Ag) particles attached to the surface of the carbon sheet) exhibits the best charge capacity, discharge capacity, and efficiency, respectively. Furthermore, it can be confirmed that the all-solid-state battery according to Example 1 exhibits the lowest resistance in the internal resistance evaluation using direct current.

[0163] Test Example 2 - Durability Characterization by Repeated Charge / Discharge Cycles

[0164] In order to confirm the durability characteristics of the all-solid-state batteries according to the examples and comparative examples, about 57 cycles of charging and discharging were performed under the same charging and discharging conditions as in Test Example 1. The results of this test are shown in FIG. Figure 6 Table 3 below lists the capacity retention rate and coulombic efficiency of the all-solid-state battery when it is charged and discharged 10 times.

[0165] [Table 3]

[0166] Capacity retention rate (%) Coulombic efficiency (%) Example 1 97.99 99.8 Comparative Example 1 94.5 99.2 Comparative Example 2 91.99 99.6 Comparative Example 3 93.9 98.9

[0167] refer to Figure 6 , the all-solid-state batteries according to Example 1 and Comparative Example 1 had only partial degradation in battery performance during approximately 57 charge / discharge cycles, but were not unable to perform the charge-discharge test due to an internal short circuit, the all-solid-state battery according to Comparative Example 2 was unable to perform the charge-discharge test due to an internal short circuit at approximately 20 cycles, and the all-solid-state battery according to Comparative Example 3 was unable to perform the charge-discharge test at approximately 10 cycles. With reference to this situation, it can be confirmed that the durability of the all-solid-state batteries according to Example 1 and Comparative Example 1 is superior to that of the all-solid-state batteries according to Comparative Examples 2 and 3.

[0168] In addition, referring to Table 3 regarding the results when the charge / discharge cycle was repeated 10 times, the capacity retention rate and coulombic efficiency of the all-solid-state batteries according to Example 1 and Comparative Example 1 were better than the capacity retention rate and coulombic efficiency of the all-solid-state batteries according to Comparative Examples 2 and 3, and in particular, the all-solid-state battery according to Example 1 manufactured by the manufacturing method according to the present application exhibited better capacity retention rate and coulombic efficiency than the all-solid-state battery according to Comparative Example 1.

[0169] Summarizing the results of Test Example 1 and Test Example 2, the all-solid-state battery according to Example 1 (i.e., according to the present application) exhibited the best durability. This is expected to be because there is no volume expansion in the vertical and horizontal directions during charge / discharge behavior, and therefore, structural collapse does not occur even when the charge / discharge cycle is repeated.

[0170] Furthermore, in the case of the all-solid-state battery according to Comparative Example 2, since silver, which is a lithiophilic metal particle, does not exist, it is speculated that the battery performance deteriorates due to the imbalance of movement and deposition of lithium.

[0171] Furthermore, in the case of the all-solid-state battery using non-oriented carbon sheets according to Comparative Example 3, it is speculated that the durability of the battery is reduced because the volume expansion of the battery in the vertical direction may be alleviated but the volume expansion of the battery in the horizontal direction is not alleviated.

[0172] It is obvious from the above description that the buffer layer according to the present application comprises carbon flakes containing an oriented carbon material and lithium-philic metal particles attached to the surface of the oriented carbon material, wherein the oriented carbon material is aligned at a predetermined angle relative to the negative electrode collector, thereby allowing lithium to be deposited from near the lithium-philic metal particles during the charging process of the all-solid-state battery.

[0173] Therefore, during the charging process of the all-solid-state battery, both vertical and horizontal volume expansion can be suppressed. This prevents the deterioration of the electrochemical characteristics of the all-solid-state battery caused by the volume change of the negative electrode layer during repeated charging and discharging processes.

[0174] The effects of the present application are not limited to the above-mentioned effects, and should be understood to include all effects that can be inferred from the above description.

[0175] Although the embodiments of the present application have been described above, those skilled in the art will be able to modify or change the present application in various ways by adding, changing, or deleting components without departing from the spirit of the present application as described in the embodiments, and this will also be included in the scope of the present application.

Claims

1. An all-solid-state battery, comprising: negative electrode current collector; a buffer layer, the buffer layer being located on the negative electrode current collector; a solid electrolyte layer, the solid electrolyte layer comprising a solid electrolyte and being located on the buffer layer; a positive electrode active material layer comprising a positive electrode active material and located on the solid electrolyte layer; and a positive electrode current collector, the positive electrode current collector being located on the positive electrode active material layer, Wherein, the buffer layer comprises: a carbon sheet comprising an oriented carbon material aligned to form a predetermined angle with the negative electrode current collector; and A lithiophilic metal material is combined with an aligned carbon material.

2. The all-solid-state battery according to claim 1, wherein: The aligned carbon material includes vertically aligned carbon nanotubes.

3. The all-solid-state battery according to claim 1, wherein: The length of the aligned carbon material is 4 μm to 60 μm.

4. The all-solid-state battery according to claim 1, wherein: The predetermined angle is 60° to 90°.

5. The all-solid-state battery according to claim 1, wherein: The lithium-philic metal material includes one selected from silver, gold, magnesium, aluminum, indium, silicon, manganese, tin, bismuth, zinc, germanium, platinum, antimony and combinations thereof.

6. The all-solid-state battery according to claim 1, wherein: The buffer layer has a thickness of 4 μm to 50 μm.

7. The all-solid-state battery according to claim 1, wherein: The buffer layer has a porous structure, and a porosity of the buffer layer is 50% or more.

8. The all-solid-state battery according to claim 1, wherein: The weight ratio of the lithium-philic metal particles to the carbon flakes in the buffer layer is 1:5 to 1:

15.

9. The all-solid-state battery according to claim 1, wherein: When the all-solid-state battery is in a fully charged state, ie, when the SoC is 100, the thickness of the lithium layer including the lithium deposited in the buffer layer is equal to or less than the thickness of the buffer layer.

10. The all-solid-state battery according to claim 1, wherein: The thickness of the buffer layer when the all-solid-state battery is in a fully charged state, ie, when the SoC is 100, is the same or substantially the same as the thickness of the buffer layer when the all-solid-state battery is in a fully discharged state, ie, when the SoC is 0.

11. The all-solid-state battery according to claim 1, wherein: The lithiophilic metal material does not form a separate layer.

12. A method for manufacturing an all-solid-state battery, the method comprising: immersing a carbon sheet comprising an aligned carbon material in a solution comprising a salt of a lithiophilic metal material and a reducing agent; stirring a solution containing carbon flakes to attach a lithiophilic metal material to a surface of the aligned carbon material, thereby forming a buffer layer; as well as A negative electrode current collector, the buffer layer, a solid electrolyte layer including a solid electrolyte, a positive electrode active material layer including a positive electrode active material, and a positive electrode current collector are stacked.

13. The method for manufacturing an all-solid-state battery according to claim 12, wherein: The solution is stirred at a temperature of 70°C to 90°C.

14. The method for manufacturing an all-solid-state battery according to claim 12, wherein: The reducing agent includes trisodium citrate.

15. The method for manufacturing an all-solid-state battery according to claim 12, wherein: The aligned carbon material includes vertically aligned carbon nanotubes.

16. The method for manufacturing an all-solid-state battery according to claim 12, wherein: The length of the aligned carbon material is 4 μm to 60 μm.

17. The method for manufacturing an all-solid-state battery according to claim 12, wherein: The angle formed by the oriented carbon material and the negative electrode current collector is 60° to 90°.

18. The method for manufacturing an all-solid-state battery according to claim 12, wherein: The lithium-philic metal material includes one selected from silver, gold, magnesium, aluminum, indium, silicon, manganese, tin, bismuth, zinc, germanium, platinum, antimony and combinations thereof.

19. The method for manufacturing an all-solid-state battery according to claim 12, wherein: The buffer layer has a thickness of 4 μm to 50 μm.

20. A vehicle comprising the all-solid-state battery according to claim 1.

Images