Room-temperature operated all-solid-state battery and method for manufacturing the same

Abstract

To provide an all-solid-state battery that can be operated at room temperature and a method for manufacturing the same.SOLUTION: An all-solid-state battery includes a negative electrode current collector, an intermediate layer 20' located on the negative electrode current collector, a solid electrolyte layer located on the intermediate layer, a positive electrode active material layer located on the solid electrolyte layer and including a positive electrode active material that occludes and releases lithium ions, and a positive electrode current collector located on the positive electrode active material layer, and the intermediate layer may include a carbon material 21' and a lithium alloy 22'.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to an all-solid-state battery capable of operating at room temperature and a method for manufacturing the same. [Background technology]

[0002] All-solid-state batteries are three-layer stacked structures consisting of a positive electrode active material layer bonded to a positive electrode current collector, a negative electrode active material layer bonded to a negative electrode current collector, and a solid electrolyte layer positioned between the positive electrode active material layer and the negative electrode active material layer.

[0003] Generally, the negative electrode active material layer includes a solid electrolyte for lithium ion movement in addition to the negative electrode active material such as graphite. Because the solid electrolyte has a higher specific gravity than the liquid electrolyte, the energy density of an all-solid-state battery is lower than that of a lithium-ion battery using a liquid electrolyte.

[0004] To overcome the aforementioned problems and increase the energy density of all-solid-state batteries, research is underway to apply lithium metal to the negative electrode. However, there are many obstacles to overcome before commercialization, ranging from research and technical issues such as interfacial bonding and lithium dendrite growth to industrial technical issues such as cost and scaling up.

[0005] In recent years, the negative electrode has been removed, and lithium ions (Li + Research is also underway on a storage-type all-solid-state battery without a negative electrode, in which lithium ions are directly deposited onto lithium metal or other materials on the negative electrode current collector. However, all-solid-state batteries without a negative electrode have problems such as the formation of inert lithium (dead lithium) because lithium ions are not uniformly deposited on the negative electrode current collector. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Korean Published Patent No. 10-2020-0052707 [Overview of the Initiative]

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a non-aqueous electrode all-solid-state battery capable of normal charge and discharge even at room temperature and a method for manufacturing the same.

[0008] The object of the present invention is not limited to the above object. The object of the present invention will become more apparent from the following description and can be realized by the means described in the claims and combinations thereof.

Means for Solving the Problems

[0009] The all-solid-state battery according to an embodiment of the present invention includes a negative electrode current collector, an intermediate layer located on the negative electrode current collector, a solid electrolyte layer located on the intermediate layer, and a positive electrode active material layer located on the solid electrolyte layer and containing a positive electrode active material that occludes and releases lithium ions, and a positive electrode current collector located on the positive electrode active material layer. The intermediate layer may include a carbon material and a lithium alloy.

[0010] The lithium alloy may include an alloy of lithium and at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), and combinations thereof.

[0011] The particle size (D50) of the lithium alloy may be 50 nm or less.

[0012] The intermediate layer may contain the lithium alloy in a discharged state.

[0013] The intermediate layer may contain 30% to 85% by weight of the carbon material and 15% to 70% by weight of the lithium alloy.

[0014] The intermediate layer may be composed of a plurality of layers each containing the carbon material and the lithium alloy.

[0015] Each layer of the intermediate layer is separated from each other at the layer interface, and the layer interface may allow lithium ions to pass through but not allow the lithium alloy to pass through.

[0016] The thickness of the intermediate layer may be 3 μm to 30 μm.

[0017] The all-solid-state battery may have a driving temperature of 40°C or less.

[0018] A method for manufacturing an all-solid-state battery according to an embodiment of the present invention includes a step of preparing a laminate including a negative electrode current collector, a precursor layer located on the negative electrode current collector and including a carbon material and a metal capable of forming an alloy with lithium, a solid electrolyte layer located on the precursor layer, a positive electrode active material layer located on the solid electrolyte layer and including a positive electrode active material that stores and releases lithium ions, and a positive electrode current collector located on the positive electrode active material layer, and a step of charging the laminate to cause an alloy reaction between the metal and lithium to form an intermediate layer including the carbon material and the lithium alloy.

[0019] The metal may include at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), and combinations thereof.

[0020] The manufacturing method may charge the laminate at 45°C to 60°C.

[0021] The manufacturing method may charge the laminate in a voltage range of 2.5 V to 4.25 V at a charging rate of 0.1 C to 1 C and at a state of charge (SoC) of 10% or less to cause an alloy reaction between the metal and lithium.

[0022] The manufacturing method may form the precursor layer from a plurality of layers each including the carbon material and the metal, and form the intermediate layer from a plurality of layers each including the carbon material and the lithium alloy. [Effects of the Invention]

[0023] According to the present invention, a negative electrode-free all-solid-state battery that can be charged and discharged normally even at room temperature can be obtained. The effects of the present invention are not limited to those described above. The effects of the present invention should be understood to include all effects that can be inferred from the following description. [Brief explanation of the drawing]

[0024] [Figure 1] Figure 1 shows an all-solid-state battery according to the present invention. [Figure 2] Figure 2 shows a first embodiment of the intermediate layer according to the present invention. [Figure 3] Figure 3 shows a second embodiment of the intermediate layer according to the present invention. [Figure 4] Figure 4 is a reference diagram illustrating the manufacturing method of the all-solid-state battery according to the present invention. [Figure 5] Figure 5 shows the results of analyzing a cross-section of the all-solid-state battery according to Example 1 using a scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS). [Figure 6] Figure 6 shows the results of analyzing the cross-section of the all-solid-state battery according to Example 2 using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). [Figure 7a] Figure 7a shows the results of analyzing the cross-section of an all-solid-state battery according to a comparative example after charging, using an ion beam section polisher-scanning electron microscope (CP-SEM). [Figure 7b] Figure 7b shows the results of analyzing the cross-section of the all-solid-state battery according to Example 1 after charging, using an ion beam sectioning machine-scanning electron microscope (CP-SEM). [Figure 7c]Figure 7c shows the results of analyzing the cross-section of the all-solid-state battery according to Example 2 after charging, using an ion beam sectioning machine-scanning electron microscope (CP-SEM). [Figure 8] Figure 8 shows the results of measuring the capacity of all-solid-state batteries according to Example 1, Example 2, and the Comparative Example. [Figure 9] Figure 9 shows the results of evaluating the durability of all-solid-state batteries according to Example 1, Example 2, and the Comparative Example. [Modes for carrying out the invention]

[0025] The above-described objects, other objects, features, and advantages of the present invention can be readily understood through the following preferred embodiments relating to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments presented herein are provided to ensure that the disclosed content is thorough and complete, and that the idea of ​​the present invention is fully conveyed to a person of the ordinary skill.

[0026] In describing each drawing, similar reference numerals were used for similar components. In the accompanying drawings, the dimensions of structures are shown enlarged for clarity of the invention. Terms such as "first," "second," etc., can be used to describe various components, but such components should not be limited by such terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without exceeding the scope of the invention, the first component may be named as the second component, and similarly, the second component may be named as the first component. A singular expression includes plural expressions unless the context clearly indicates otherwise.

[0027] In this specification, terms such as “includes” or “have” are intended to specify the presence of features, numbers, steps, actions, components, parts, or combinations thereof described herein, without prejudice to the existence or possibility of adding one or more other features, numbers, steps, actions, components, parts, or combinations thereof. Furthermore, when a part such as a layer, membrane, region, or plate is said to be “on” another part, this includes not only when it is “directly on” the other part, but also when there is another part in between. Conversely, when a part such as a layer, membrane, region, or plate is said to be “below” another part, this includes not only when it is “directly below” the other part, but also when there is another part in between.

[0028] Unless otherwise explicitly stated, all numbers, values ​​and / or expressions used herein to express quantities of components, reaction conditions, polymer compositions and formulations should be understood to be modified in all cases by the term “approximately,” since such numbers are approximations that reflect various uncertainties in measurement that arise in obtaining such values, among other things. Furthermore, where numerical ranges are disclosed herein, such ranges are continuous and, unless otherwise noted, include all values ​​from the minimum to the maximum value of such range. Furthermore, where such ranges refer to integers, unless otherwise noted,

[0029] This includes all integers from the minimum value up to the maximum value. Figure 1 shows an all-solid-state battery according to the present invention. Referring to this, the all-solid-state battery may include a negative electrode current collector 10, an intermediate layer located on the negative electrode current collector 10, a solid electrolyte layer 30 located on the intermediate layer 20, a positive electrode active material layer 40 located on the solid electrolyte layer 30, and a positive electrode current collector 50 located on the positive electrode active material layer 40.

[0030] Figure 1 shows the discharge state of the all-solid-state battery. When the all-solid-state battery is charged, lithium ions (Li) are released from the positive electrode active material layer 40. +The lithium ions move to the intermediate layer 20 via the solid electrolyte layer 30. Subsequently, the lithium ions can be deposited and stored between the negative electrode current collector 10 and the intermediate layer 20 and / or inside the intermediate layer 20 to form a lithium metal layer (not shown).

[0031] The negative electrode current collector 10 may be a plate-shaped substrate with electrical conductivity. Specifically, the negative electrode current collector 10 may be in the form of a sheet, a thin film, or a foil.

[0032] The negative electrode current collector 10 may contain a material that does not react with lithium. Specifically, the negative electrode current collector 10 may contain at least one selected from the group consisting of Ni, Cu, SUS (stainless steel), and combinations thereof.

[0033] Conventional technology has reported that forming a coating layer containing carbon material, metal, etc., on the negative electrode current collector allows for the uniform deposition of lithium metal on the negative electrode current collector. Specifically, a lithiation reaction between lithium ions and metal occurs in the initial stages of charging and discharging, forming an alloy, which then induces smooth conduction and uniform deposition of lithium ions. However, since such a lithiation reaction only occurs at high temperatures of approximately 45°C or higher, such a negative electrode-less all-solid-state battery will not function properly at room temperature of approximately 25°C.

[0034] Figure 2 shows a first embodiment of the intermediate layer 20 according to the present invention. The present invention is characterized by applying an intermediate layer 20 containing a carbon material 21 and a lithium alloy 22 on the negative electrode current collector 10 in order to solve the problems of the prior art.

[0035] The lithium alloy 22 can provide a path for lithium ions to move within the intermediate layer 20. In particular, the intermediate layer 20 may contain the lithium alloy 22 in the discharge state. That is, unlike conventional all-solid-state batteries without negative electrodes, the present invention does not require a lithiation reaction between lithium ions and metal to form the lithium alloy 22 in the initial stages of charging. Therefore, when the all-solid-state battery according to the present invention is charged at room temperature, lithium ions can move smoothly through the lithium alloy 22 within the intermediate layer 20. Here, "discharge state" means a state in which the remaining capacity of the all-solid-state battery is 15% or less, or 10% or less, or 5% or less, or zero.

[0036] The lithium alloy 22 may include an alloy of lithium with a metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), and combinations thereof. The ratio of lithium to metal is not particularly limited. For example, the lithium alloy may be alloyed in a weight ratio of lithium to metal of 0.1 to 99.9:0.1 to 99.9.

[0037] The particle size D50 of the lithium alloy 22 may be 50 nm or less. The lower limit of the particle size D50 is not particularly limited and may be, for example, 5 nm or more, 10 nm or more, or 20 nm or more.

[0038] The carbon material 21 may contain amorphous carbon. The amorphous carbon is not particularly limited, but may include, for example, furnace black, acetylene black, or ketjen black.

[0039] The intermediate layer 20 may contain 30% to 85% by weight of carbon material 21 and 15% to 70% by weight of lithium alloy 22. If the lithium alloy 22 content is less than 15% by weight, the movement of lithium ions within the intermediate layer 20 may not be smooth, and if the content exceeds 70% by weight, the dispersibility may decrease.

[0040] On the other hand, although the specific mechanism has not been elucidated, the lithium alloy 22 does not distribute uniformly within the intermediate layer 20 during its formation process, but rather moves towards the negative electrode current collector 10, as shown in Figure 2. Therefore, the intermediate layer 20 is divided in the thickness direction into parts with a high content of the lithium alloy 22 and parts with a low content. As a result, the movement of lithium ions may not be smooth in the parts of the intermediate layer 20 with a low content of the lithium alloy 22.

[0041] Figure 3 shows a second embodiment of the intermediate layer 20' according to the present invention. Referring to this, the intermediate layer 20' may be composed of multiple layers, each containing the carbon material 21' and the lithium alloy 22'. Although Figure 3 shows the intermediate layer 20' as two layers, the present invention is not limited thereto, and the number of layers can be appropriately adjusted according to the specifications of the all-solid-state battery and the desired characteristics.

[0042] The multiple layers of the intermediate layer 20' may be separated from each other by an interlayer interface A. The interlayer interface A is not an abstract or conceptual structure, but rather an interface that physically separates each layer. Therefore, even if the lithium alloy 22' contained in each layer exhibits behavior of moving toward the negative electrode current collector 10 side during the manufacturing process of the intermediate layer 20', it cannot pass through the interlayer interface A. As a result, in the intermediate layer 20' according to the second embodiment, there is no significant difference in the distribution of lithium alloy 22' content in the thickness direction, so lithium ions can move smoothly. Furthermore, even if lithium alloy 22' moves toward the negative electrode current collector 10 side and a portion with a low lithium alloy 22' content is created within each layer, the distance is short, so it does not significantly affect the overall lithium ion conductivity.

[0043] On the other hand, the lithium alloy 22' is distributed around the interlayer interface A, but it cannot pass through the interlayer interface A, so lithium ions can pass through the interlayer interface A.

[0044] The thickness of the intermediate layer 20 may be 3 μm to 30 μm. If the thickness is less than 3 μm, uniform deposition and storage of lithium ions becomes difficult, and if it exceeds 30 μm, lithium ion movement may not be smooth, which may result in a lower energy density of the all-solid-state battery.

[0045] As described above, the all-solid-state battery according to the present invention does not require high-temperature charging and discharging because the intermediate layer 20 contains a lithium alloy 22 that can conduct lithium ions in the discharge state. That is, the operating temperature of the all-solid-state battery may be 40°C or lower. The lower limit of the operating temperature is not particularly limited and may be the same as or similar to the lower limit of the operating temperature of batteries that are normally considered in the art to which the present invention belongs.

[0046] The solid electrolyte layer 30 may be configured to conduct lithium ions from the positive electrode active material layer 40 to the intermediate layer 20.

[0047] The solid electrolyte layer 30 may contain a solid electrolyte that is conductive to lithium ions.

[0048] The solid electrolyte may include at least one selected from the group consisting of oxide-based solid electrolytes, sulfide-based solid electrolytes, polymer electrolytes, and combinations thereof. However, it is preferable to use a sulfide-based solid electrolyte having a high lithium ion conductivity. The sulfide-based solid electrolyte is not particularly limited, but 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 (where m, n are positive numbers, and Z is one of Ge, Zn, Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (where x, y are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, In), Li 10 GeP2S 12 and the like may be included.

[0049] The oxide-based solid electrolyte may include perovskite-type (perovskite) LLTO (Li 3x La 2 / 3-x TiO3), phosphate-based NASICON-type LATP (Li 1+x Al x Ti 2-x (PO)3) and the like. The polymer electrolyte may include a gel polymer electrolyte, a solid polymer electrolyte, and the like.

[0050] The positive electrode active material layer 40 may include a positive electrode active material, a solid electrolyte, a conductive material, a binder, and the like.

[0051] The positive electrode active material is configured to reversibly occlude and release lithium ions. The positive electrode active material may include an oxide active material or a sulfide active material.

[0052] The oxide active material is LiCoO2, LiMnO2, LiNiO2, LiVO2, Li 1+x Ni 1 / 3 Co 1 / 3 Mn 1 / 3 rock salt layer type active materials such as O2, spinel type active materials such as LiMn2O4, Li(Ni 0.5 Mn 1.5 )O4, inverse spinel type active materials such as LiNiVO4, LiCoVO4, olivine type active materials such as LiFePO4, LiMnPO4, LiCoPO4, LiNiPO4, silicon-containing active materials such as Li2FeSiO4, Li2MnSiO4, LiNi 0.8 Co (0.2-x) Al x O2 (0 < x < 0.2) and other rock salt layer type active materials in which part of the transition metal is replaced with a different metal, Li 1+x Mn 2-x-y M y O4 (M is at least one of Al, Mg, Co, Fe, Ni, Zn, and 0 < x + y < 2) and other spinel type active materials in which part of the transition metal is replaced with a different metal, Li4Ti5O 12 etc. may contain lithium titanate. The sulfide active material may include copper chalcogenide, iron sulfide, cobalt sulfide, nickel sulfide, etc.

[0053] The solid electrolyte may include an oxide solid electrolyte or a sulfide solid electrolyte. However, it is preferable to use a sulfide-based solid electrolyte with high lithium ion conductivity. The sulfide-based solid electrolyte is not particularly limited, but 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(where m and n are positive numbers, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (where x and y are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, or In), Li 10 GeP2S 12 You can also use these.

[0054] The conductive material may be carbon black, conductive graphite, ethylene black, graphene, or the like. The binder may be BR (butadiene rubber), NBR (nitrile butadiene rubber), HNBR (hydrogenated nitrile butadiene rubber), PVDF (polyvinylidene difluoride), PTFE (polytetrafluoroethylene), or CMC (carboxymethylcellulose).

[0055] The positive electrode current collector 50 may be a plate-shaped substrate that is electrically conductive. The positive electrode current collector 50 may also include an aluminum foil.

[0056] Figure 4 is a reference diagram illustrating a method for manufacturing an all-solid-state battery according to the present invention. Referring to Figures 1 and 4, the manufacturing method may include the steps of: preparing a laminate including a negative electrode current collector 10, a precursor layer 60 located on the negative electrode current collector 10 and containing a carbon material and a metal capable of forming an alloy with lithium, a solid electrolyte layer 30 located on the precursor layer 60, a positive electrode active material layer 40 located on the solid electrolyte layer 30, and a positive electrode current collector 50 located on the positive electrode active material layer 40; and charging the laminate to cause an alloy reaction between the metal and lithium to form an intermediate layer 20 containing the carbon material and lithium alloy.

[0057] The method for manufacturing each layer of the laminate is not particularly limited and may be dry or wet. For example, the materials for each layer may be mixed in powder form, then pressurized under a constant pressure, or made into a slurry, which may then be applied to a substrate and dried.

[0058] The aforementioned metal may include at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), and combinations thereof.

[0059] If the precursor layer 60 is composed of multiple layers, each containing the carbon material and the metal, then an intermediate layer 20' composed of multiple layers can be formed as shown in Figure 3.

[0060] Referring to Figure 4, when the laminate is charged, lithium ions released from the positive electrode active material layer 40 move to the precursor layer 60 via the solid electrolyte layer 30. These lithium ions undergo a lithiation reaction with the metal in the precursor layer 60 to form a lithium alloy.

[0061] To induce the lithiumization reaction, the laminate may be charged at a temperature of 45°C to 60°C. If the laminate is charged at a temperature below 45°C, a lithium alloy may not be formed.

[0062] Furthermore, the charging of the laminate may be carried out under the conditions of a voltage range of 2.5V to 4.25V, a charge level of 0.1C to 1C, and an SoC (State of Charge) of 10% or less. Here, "SoC" means the charge state and may be expressed as a percentage obtained by dividing the currently usable battery capacity by the total capacity. The SoC can be measured by a voltage measurement method or a current integration method. The voltage measurement method may involve measuring the battery voltage and calculating it in comparison with the discharge curve. The current integration method can be calculated by measuring the battery current and then integrating it over time.

[0063] The lithium ions forming the lithium alloy do not revert to the positive electrode active material during room-temperature operation of the all-solid-state battery, but remain as part of the lithium alloy. Therefore, if the laminate is charged under conditions exceeding 10% SoC, the amount of lithium ions remaining in the positive electrode active material decreases, which can reduce the battery capacity. To solve the above problems, it is also possible to overfill the lithium alloy or increase the loading amount of the positive electrode active material. In particular, by increasing the loading amount of the positive electrode active material, the capacity of the positive electrode becomes larger than that of the negative electrode, and even when the full capacity of the positive electrode is realized, the potential of the negative electrode does not rise to the potential at which the lithium alloy decomposes, thus effectively preventing the above problems from occurring.

[0064] Other embodiments of the present invention will be described in more detail below through examples. The following examples are merely illustrative for understanding the present invention, and the scope of the present invention is not limited thereto.

[0065] Example 1 A laminate as shown in Figure 4 was prepared. Specifically, a precursor layer containing carbon material and silver (Ag) was formed on the negative electrode current collector. A solid electrolyte layer containing a sulfide-based solid electrolyte was formed on the precursor layer. A positive electrode active material layer containing nickel-cobalt-manganese positive electrode active material was formed on the solid electrolyte layer. The positive electrode current collector was attached to the positive electrode active material layer to create the laminate.

[0066] The laminate was charged at approximately 50°C with a voltage range of 2.5V to 4.25V and a charge level of 0.33C to form a single-layer intermediate layer containing a lithium-silver alloy, with a thickness of approximately 5μm to 10μm. The all-solid-state battery including the intermediate layer was designated as Example 1.

[0067] Example 2 The laminate was manufactured in the same manner as in Example 1, except that the precursor layer was formed from two layers. The laminate was charged under the same conditions as in Example 1 to form an intermediate layer containing a lithium-silver alloy, with a thickness of approximately 5 μm to 10 μm and consisting of two layers. The thickness of each layer of the intermediate layer was adjusted to be the same as that of the others. The all-solid-state battery including the intermediate layer was designated as Example 2.

[0068] Comparative Example The laminate of Example 1 was set as a comparative example. Figure 5 shows the results of analyzing a cross-section of the all-solid-state battery according to Example 1 using a scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS).

[0069] Figure 6 shows the results of analyzing the cross-section of the all-solid-state battery according to Example 2 using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS).

[0070] Referring to the EDS results in Figure 5, it can be seen that in Example 1, there is a higher concentration of silver (Ag) on ​​the negative electrode current collector side in the thickness direction of the intermediate layer. In other words, it can be seen that in Example 1, the lithium-silver alloy migrated towards the negative electrode current collector side during the manufacturing process, resulting in a gradient in the content of the intermediate layer.

[0071] In contrast, referring to the EDS results in Figure 6, it can be seen that in Example 2, the silver (Ag) element is uniformly distributed in the thickness direction of the intermediate layer. That is, in Example 2, the movement of the lithium-silver alloy is suppressed by the interlayer interface, and the lithium-silver alloy is uniformly present in the thickness direction of the intermediate layer.

[0072] The all-solid-state batteries according to Example 1, Example 2, and the Comparative Example were charged at approximately 25°C until the SoC reached 100%.

[0073] Figure 7a shows the results of analyzing the cross-section of an all-solid-state battery related to the comparative example after charging, using a cross-section polisher-scanning electron microscope (CP-SEM). Referring to this, it can be seen that in the comparative example, lithium ions were unable to pass through the precursor layer and instead electrodeposited between the solid electrolyte layer and the intermediate layer. This is because, due to room-temperature charging, the lithium ions could not undergo a lithiation reaction with the silver (Ag) contained in the precursor layer of the comparative example. When lithium ions electrodeposit between the solid electrolyte layer and the intermediate layer, resinous lithium can grow, potentially causing a short circuit in the battery.

[0074] Figure 7b shows the results of analyzing the cross-section of the all-solid-state battery according to Example 1 after charging, using an ion beam sectioning machine-scanning electron microscope (CP-SEM). Referring to this, it can be seen that in Example 1, lithium ions migrated to the intermediate layer and were electrodeposited inside it. Therefore, it can be confirmed that the all-solid-state battery according to Example 1 is capable of reversible charging and discharging while suppressing the growth of resinous lithium even at room temperature.

[0075] Figure 7c shows the results of analyzing the cross-section of the all-solid-state battery according to Example 2 after charging, using an ion beam sectioning machine-scanning electron microscope (CP-SEM). Referring to this, it can be seen that in Example 2, lithium ions were electrodeposited at high density between the intermediate layer and the negative electrode current collector. This is because the lithium alloy is uniformly distributed in the intermediate layer of Example 2, allowing lithium ions to move smoothly within the intermediate layer.

[0076] Figure 8 shows the results of measuring the capacity of all-solid-state batteries according to Example 1, Example 2, and the Comparative Example. The capacity was measured by charging and discharging each all-solid-state battery at approximately 25°C within a voltage range of 2.5V to 4.25V. Referring to this, it can be seen that Example 1 and Example 2 have higher charging capacity and lower resistance compared to the Comparative Example. This is because Example 1 and Example 2 have higher lithium-ion conductivity and improved electrodeposition characteristics compared to the Comparative Example.

[0077] Figure 9 shows the results of evaluating the durability of all-solid-state batteries according to Example 1, Example 2, and the Comparative Example. Each all-solid-state battery was charged and discharged at approximately 25°C in a voltage range of 2.5V to 4.25V, and the capacity retention rate in each cycle was measured. Referring to this, it can be seen that Example 1 and Example 2 have higher capacity retention rates than the Comparative Example. This is because lithium is uniformly electrodeposited in Example 1 and Example 2. In particular, Example 2 shows a capacity retention rate of approximately 95% based on 30 charge-discharge cycles. This is because, as can be seen from Figure 7c, in Example 2, lithium is electrodeposited at a high density between the intermediate layer and the negative electrode current collector, resulting in high reversibility.

[0078] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to the embodiments described above. Various modifications and improvements made by those skilled in the art using the basic concepts of the present invention as defined in the following claims are also included within the scope of the present invention. [Explanation of symbols]

[0079] 10: Negative electrode current collector 20: Middle Class 30: Solid electrolyte layer 40: Positive electrode active material layer 50: Anode current collector 60: Precursor layer

Claims

1. Negative electrode current collector and An intermediate layer located on the negative electrode current collector, A solid electrolyte layer located on the aforementioned intermediate layer, A positive electrode active material layer located on the solid electrolyte layer and containing a positive electrode active material that intercepts and releases lithium ions, The positive electrode current collector is located on the positive electrode active material layer, The aforementioned intermediate layer comprises a carbon material and a lithium alloy. The aforementioned intermediate layer is composed of multiple layers, each containing the carbon material and the lithium alloy. The all-solid-state battery wherein the particle size (D50) of the lithium alloy is 50 nm or less.

2. The aforementioned lithium alloy is Lithium and, The all-solid-state battery according to claim 1, comprising an alloy with a metal including at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), and combinations thereof.

3. The all-solid-state battery according to claim 1, wherein the intermediate layer contains the lithium alloy in the discharged state.

4. The aforementioned intermediate layer is The carbon material is 30% to 85% by weight and, The all-solid-state battery according to claim 1, comprising 15% to 70% by weight of the lithium alloy.

5. The aforementioned multiple layers are separated from each other at the interlayer interface. The all-solid-state battery according to claim 1, wherein the interlayer interface allows lithium ions to pass through but does not allow the lithium alloy to pass through.

6. The all-solid-state battery according to claim 1, wherein the thickness of the intermediate layer is 3 μm to 30 μm.

7. The all-solid-state battery according to claim 1, wherein the operating temperature is 40°C or lower.

8. The steps include preparing a laminate comprising a negative electrode current collector, a precursor layer located on the negative electrode current collector and containing a carbon material and a metal capable of forming an alloy with lithium, a solid electrolyte layer located on the precursor layer, a positive electrode active material layer located on the solid electrolyte layer and containing a positive electrode active material that intercepts and releases lithium ions, and a positive electrode current collector located on the positive electrode active material layer, The step of charging the laminate to cause an alloy reaction between the metal and lithium, thereby forming an intermediate layer containing the carbon material and the lithium alloy, A method for manufacturing an all-solid-state battery, wherein the laminate is charged at a voltage range of 2.5V to 4.25V, a charge level of 0.1C to 1C, and a State of Charge (SoC) of 10% or less to cause an alloy reaction between the metal and lithium.

9. The method for manufacturing an all-solid-state battery according to claim 8, wherein the metal comprises at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), and combinations thereof.

10. A method for manufacturing an all-solid-state battery according to claim 8, wherein the laminate is charged at 45°C to 60°C.

11. The method for manufacturing an all-solid-state battery according to claim 8, wherein the particle size (D50) of the lithium alloy is 50 nm or less.

12. The method for manufacturing an all-solid-state battery according to claim 8, wherein the intermediate layer contains the lithium alloy in the discharged state.

13. The aforementioned intermediate layer is The carbon material is 30% to 85% by weight and, A method for manufacturing an all-solid-state battery according to claim 8, comprising 15% to 70% by weight of the lithium alloy.

14. The method for manufacturing an all-solid-state battery according to claim 8, wherein the precursor layer is composed of a plurality of layers each containing the carbon material and a metal, and the intermediate layer is formed from a plurality of layers each containing the carbon material and a lithium alloy.

15. The multiple layers of the aforementioned intermediate layer are separated from each other at the interlayer interface. The method for manufacturing an all-solid-state battery according to claim 14, wherein the interlayer interface allows lithium ions to pass through but does not allow the lithium alloy to pass through.

16. The method for manufacturing an all-solid-state battery according to claim 8, wherein the thickness of the intermediate layer is 3 μm to 30 μm.

17. A method for manufacturing an all-solid-state battery according to claim 8, wherein the operating temperature is 40°C or lower.

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