All-solid-state battery including lithium storage layer having multi-layer structure and method of manufacturing the same

Abstract

A full solid battery includes: an anode current collector; a lithium storage layer including a first layer on an electrolyte layer side and a second layer on an anode current collector side, the second layer having higher porosity than the first layer and including an interface portion and a core portion that is a remaining portion other than the interface portion; an electrolyte layer; and a cathode layer, wherein the anode current collector, the lithium storage layer, the electrolyte layer, and the cathode layer are sequentially laminated, and the interface portion is in contact with the first layer and has higher binder content per unit volume than the core portion.

Description

Technical Field

[0001] This disclosure relates to all-solid-state batteries and methods for manufacturing them. Background Technology

[0002] The statements in this section are provided only as background information in connection with this disclosure and do not constitute prior art.

[0003] The all-solid-state battery is configured as a three-layer laminate, including a cathode composite layer bonded to the cathode current collector, an anode composite layer bonded to the anode current collector, and a solid electrolyte between the cathode composite layer and the anode composite layer.

[0004] Typically, the anode composite layer of an all-solid-state battery is formed by mixing active materials and a solid electrolyte to provide ionic conductivity. Because solid electrolytes have a higher specific gravity than liquid electrolytes, these conventional all-solid-state batteries have lower energy density compared to lithium-ion batteries.

[0005] To increase the energy density of all-solid-state batteries, the application of lithium metal as an anode has been studied. However, challenges exist, such as interface bonding, dendrite growth, cost, and difficulty in achieving large-area applications.

[0006] Recently, research on anode-free storage batteries has also been underway, in which the anode of the all-solid-state battery is removed, and lithium is allowed to deposit directly on the anode current collector side. However, the drawback of the above-mentioned batteries is that irreversible reactions gradually increase due to the uneven deposition of lithium, resulting in very poor durability. Summary of the Invention

[0007] This disclosure provides an anode-free all-solid-state battery capable of uniformly depositing lithium.

[0008] This disclosure provides an all-solid-state battery capable of suppressing volume expansion caused by lithium deposition.

[0009] This disclosure also provides an all-solid-state battery with improved durability and charge / discharge efficiency by increasing the adhesion between the layers of the lithium storage layer.

[0010] One form of this disclosure provides an all-solid-state battery comprising: an anode current collector; a lithium storage layer including a first layer on the side of an electrolyte layer and a second layer on the side of the anode current collector, the second layer having a higher porosity than the first layer and including an interface portion and a core portion as the remainder excluding the interface portion; an electrolyte layer; and a cathode layer, wherein the anode current collector, the lithium storage layer, the electrolyte layer and the cathode layer are sequentially laminated, and the interface portion has a higher binder content per unit volume than the core portion.

[0011] Lithium storage layers may include carbon materials and metal powders.

[0012] Carbon materials may include at least one of the following: particulate carbon materials, fibrous carbon materials, and combinations thereof.

[0013] Particulate carbon materials may include at least one selected from the following: carbon black, graphitizable carbon, non-graphitizable carbon, and combinations thereof.

[0014] Fibrous carbon materials may include at least one of the following: carbon nanofibers, carbon nanotubes, vapor-grown carbon fibers, and combinations thereof.

[0015] The metal powder may include at least one of the following: aluminum (Al), zinc (Zn), indium (In), silver (Ag), gold (Au), magnesium (Mg), silicon (Si), bismuth (Bi), germanium (Ge), platinum (Pt), antimony (Sb), and combinations thereof.

[0016] In all-solid-state batteries, the thickness ratio of the first layer to the second layer can be 1:0.5-2.

[0017] The first layer may have a porosity of 5% or lower.

[0018] The second layer can have a porosity of 5% to 50%.

[0019] The first layer may include a polyvinylidene fluoride (PVDF) adhesive.

[0020] The second layer may include a polyvinylidene fluoride (PVDF) adhesive and a nitrile rubber (NBR) adhesive.

[0021] The interface portion can have a higher nitrile rubber adhesive content per unit volume than the core portion.

[0022] The thickness of the interface portion can be 0.1% to 10% of the thickness of the second layer.

[0023] Furthermore, this disclosure provides a method for manufacturing an all-solid-state battery, comprising: preparing a first adhesive solution comprising a polyvinylidene fluoride (PVDF) binder and a first solvent; preparing a second adhesive solution comprising a nitrile rubber (NBR) binder and a second solvent different from the first solvent; preparing a first slurry comprising a carbon material, metal powder, and the first adhesive solution; preparing a second slurry by adding the second adhesive solution to the first slurry; forming a second layer by applying the second slurry onto a substrate; forming a first layer by applying the first slurry onto the second layer, and obtaining a lithium storage layer comprising the first layer and the second layer; and forming an all-solid-state battery by sequentially laminating an anode current collector, a lithium storage layer, an electrolyte layer, and a cathode layer, wherein the first layer is located on the electrolyte layer side, and a second layer having a higher porosity than the first layer is located on the anode current collector side, the second layer comprising an interface portion in contact with the first layer and a core portion as the remaining portion excluding the interface portion, and the interface portion having a higher binder content per unit volume than the core portion.

[0024] The second solvent may have a lower density than the first solvent, may have a higher solubility for nitrile butadiene rubber (NBR) adhesives than for polyvinylidene fluoride (PVDF) adhesives, or may have a higher vapor pressure than the first solvent.

[0025] The first solvent may include N-methyl-2-pyrrolidone (NMP), and the second solvent may include hexyl butyrate.

[0026] The second slurry may have a lower solids content than the first slurry.

[0027] The solids content of the first slurry can be from 4 wt% to 10 wt%.

[0028] The solids content of the second slurry can be 3 wt% or less.

[0029] Here, after the second slurry is applied to the substrate, the second layer can be dried or left to stand, allowing the second adhesive solution to rise to the surface of the second layer.

[0030] According to this disclosure, an anode-free all-solid-state battery capable of uniformly depositing lithium can be obtained.

[0031] Furthermore, according to this disclosure, an all-solid-state battery capable of suppressing volume expansion caused by lithium deposition can be obtained.

[0032] Furthermore, according to this disclosure, an all-solid-state battery with improved durability and charge / discharge efficiency can be obtained by increasing the adhesion between the layers of the lithium storage layer.

[0033] The effects of this disclosure are not limited to the foregoing and should be understood to include all effects that can be reasonably expected from the following description.

[0034] Further applications will become apparent from the description provided herein. It should be understood that the descriptions and specific examples are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0035] To better understand this disclosure, various forms thereof will now be described with reference to the accompanying drawings, which are given by way of example, in which:

[0036] Figure 1 To illustrate a cross-sectional view of an all-solid-state battery according to this disclosure;

[0037] Figure 2 A cross-sectional view of a lithium storage layer in an all-solid-state battery according to the present disclosure is shown.

[0038] Figure 3 A flowchart illustrating a process for manufacturing an all-solid-state battery according to one form of the present disclosure;

[0039] Figure 4 A scanning electron microscope (SEM) image of the cross-section of the all-solid-state battery of the embodiment during charging;

[0040] Figure 5 SEM images of the cross-section of the all-solid-state battery of Comparative Example 1 during charging are shown;

[0041] Figure 6A The measurement results of the capacity retention of the all-solid-state batteries of Example 1 and Comparative Example 1 are shown; and

[0042] Figure 6B The measurement results of the coulombic efficiency of the all-solid-state batteries of Example 1 and Comparative Example 1 are shown.

[0043] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way. Detailed Implementation

[0044] The following description is merely exemplary in nature and is not intended to limit this disclosure, its application, or its use. It should be understood that in all the drawings, corresponding reference numerals indicate similar or corresponding parts and features.

[0045] For clarity of this disclosure, the dimensions of the structures are described as larger than their actual size. It should be understood that although terms such as “first,” “second,” etc., may be used herein to describe various elements, these elements are not limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this disclosure, a “first” element discussed below may be referred to as a “second” element. Similarly, a “second” element may also be referred to as a “first” element. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise.

[0046] The terms “comprising,” “including,” “having,” etc., as used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof. Furthermore, it should be understood that when an element such as a layer, film, region, or sheet is referred to as being “on” another element, it may be directly on the other element, or an intermediate element may exist between them. Similarly, when an element such as a layer, film, region, or sheet is referred to as being “under” another element, it may be directly under the other element, or an intermediate element may exist between them.

[0047] Unless otherwise stated, all figures, values, and / or representations used herein to indicate the amounts of components, reaction conditions, polymer compositions, and mixtures should be considered approximate, including various uncertainties in measurement that are inherent in obtaining these values, and are therefore to be understood to be modified in all cases by the term "about". Furthermore, when numerical ranges are disclosed in this specification, the ranges are continuous and include all values ​​from the minimum to the maximum of the range, unless otherwise indicated. Additionally, when such ranges are integer values, all integers from the minimum to the maximum are included, unless otherwise indicated.

[0048] Figure 1 A cross-sectional view of an all-solid-state battery according to the present disclosure is shown. Referring here, the all-solid-state battery includes an anode current collector 10, a lithium storage layer 20, an electrolyte layer 30, a cathode layer 40, and a cathode current collector 50.

[0049] The anode current collector 10 may be a sheet-like substrate. The anode current collector layer 10 may be a metal thin film, including at least one metal selected from copper (Cu), nickel (Ni), and combinations thereof. Specifically, the anode current collector layer 10 may be a high-density metal thin film with a porosity of less than about 1%.

[0050] The anode current collector layer 10 may have a thickness of 1 μm to 20 μm, particularly 5 μm to 15 μm.

[0051] The lithium storage layer 20 provides lithium ions (Li) that move from the cathode layer 40 through the electrolyte layer 30 during all-solid-state battery charging. + The space in which lithium metal or lithium compounds are stored.

[0052] The lithium storage layer 20 may include carbon materials and metal powder.

[0053] Carbon materials may include at least one of the following: particulate carbon materials, fibrous carbon materials, and combinations thereof.

[0054] Specifically, particulate carbon materials may include at least one selected from the following: carbon black, graphitizable carbon, non-graphitizable carbon, and combinations thereof.

[0055] In addition, fibrous carbon materials may include at least one of the following: carbon nanofibers, carbon nanotubes, vapor-grown carbon fibers, and combinations thereof.

[0056] Metal powder can be used as a seed for lithium ions in the lithium storage layer 20. Specifically, when the all-solid-state battery is charged, the lithium ions (Li+) that have moved to the lithium storage layer 20... + Lithium mainly grows around metal powder.

[0057] The metal powder may include at least one of the following: aluminum (Al), zinc (Zn), indium (In), silver (Ag), gold (Au), magnesium (Mg), silicon (Si), bismuth (Bi), germanium (Ge), platinum (Pt), antimony (Sb), and combinations thereof.

[0058] Particle size of metal powder (D) 50 There are no particular restrictions, but it can be, for example, 0.01 μm to 5 μm, or 0.1 μm to 1 μm.

[0059] The lithium storage layer 20 may include a first layer 21 located on the side of the electrolyte layer 30 and a second layer 22 located on the side of the anode current collector 10.

[0060] The thickness of each of the first layer 21 and the second layer 22 is not particularly limited and can be, for example, from 2 μm to 10 μm, and the thickness ratio of the first layer 21 to the second layer 22 can be 1:0.5-2.

[0061] The present disclosure is characterized in that the second layer 22 is designed to have a higher porosity than the first layer 21. By increasing the porosity of the second layer 22 on the anode current collector 10 side, lithium ions (Li...) +Lithium metal and / or lithium compounds are allowed to deposit within the second layer 22 and / or between the second layer 22 and the anode current collector 10. Therefore, lithium metal and / or lithium compounds can be deposited uniformly, and lithium volume expansion can be effectively suppressed. Furthermore, since the deposited lithium metal and / or lithium compounds can be located near the anode current collector 10, which is the pathway for electrons, dead lithium is not generated during battery discharge.

[0062] There are no particular limitations on the porosity of the first layer 21 and the second layer 22, but for example, the porosity of the first layer 21 may be 5% or lower. On the other hand, the porosity of the second layer 22 may be 5% to 50%, or 20% to 30%.

[0063] Figure 2 This is a cross-sectional view of the lithium storage layer 20. Referring to this figure, the second layer 22 may include an interface portion 22a in contact with the first layer 21 and a core portion 22b that is the remaining portion excluding the interface portion 22a.

[0064] The thickness of the interface portion 22a is not particularly limited, but may be, for example, 0.1% to 10% or 0.1% to 5% of the thickness of the second layer 22.

[0065] The lithium storage layer 20 may be provided in the form of a multilayer structure of a first layer 21 and a second layer 22, and undergoes volume expansion due to lithium precipitation and / or deposition, so that the layers can be easily separated from each other when the adhesion between the layers is weak.

[0066] The present disclosure is characterized in that the interface portion 22a of the second layer 22 is designed to have a high adhesive content per unit volume, thereby increasing the adhesion between the first layer 21 and the second layer 22.

[0067] In addition to the aforementioned carbon materials and metal powder, the first layer 21 also includes a polyvinylidene fluoride (PVDF) adhesive.

[0068] In addition to carbon materials and metal powder, the second layer 22 also includes polyvinylidene fluoride (PVDF) adhesive and nitrile rubber (NBR) adhesive.

[0069] Interface portion 22a may include a higher content of nitrile butadiene rubber (NBR) adhesive per unit volume than core portion 22b. Therefore, as described above, the total adhesive content per unit volume of interface portion 22a can be adjusted to be higher than the total adhesive content of core portion 22b. A method for manufacturing a lithium storage layer 20 having a multilayer structure designed as described above will be described later.

[0070] Furthermore, there is no particular limitation on the adhesive content per unit volume of the interface portion 22a and the core portion 22b, and as long as they are set to satisfy the above relationship, they should be considered to fall within the scope of the embodiments and modifications of this disclosure.

[0071] The electrolyte layer 30 is located between the lithium storage layer 20 and the cathode layer 40, allowing lithium ions to move between the two components.

[0072] The electrolyte layer 30 may comprise an oxide-based solid electrolyte or a sulfide-based solid electrolyte. Here, a sulfide-based solid electrolyte with high lithium-ion conductivity is preferred. The sulfide-based solid electrolyte is not particularly limited and may be 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, or Li₂S-P₂S₅-Z. m S n (where m and n are positive numbers and z is any one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (where x and y are positive numbers and M is any one of P, Si, Ge, B, Al, Ga, and In), Li 10 GeP2S 12 wait.

[0073] The cathode layer 40 may include cathode active materials, solid electrolytes, conductive materials, adhesives, etc.

[0074] The cathode active material can be an oxide active material or a sulfide active material.

[0075] Oxide active materials can be rock salt layer type active materials, such as LiCoO2, LiMnO2, LiNiO2, LiVO2, Li 1+ x Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2, spinel-type active materials, such as LiMn2O4, Li(Ni) 0.5 Mn 1.5 Examples of active materials include: O4, anti-spinel type active materials such as LiNiVO4 and LiCoVO4; olivine type active materials such as LiFePO4, LiMnPO4, LiCoPO4, and LiNiPO4; silicon-containing active materials such as Li2FeSiO4 and Li2MnSiO4; and rock salt layer type active materials, in which some transition metals are replaced by different metals, such as LiNi...0.8 Co (0.2-x) Al x O2(0 < x < 0.2), a spinel-type active material, in which a part of the transition metal is replaced by a different metal, such as Li 1+x Mn 2-x-y M y O4 (M is at least one of Al, Mg, Co, Fe, Ni, and Zn, 0 < x + y < 2), or lithium titanate, such as Li4Ti5O 12 etc.

[0076] The sulfide active material can be Chevrel copper, iron sulfide, cobalt sulfide, nickel sulfide, etc.

[0077] The solid-state electrolyte can be an oxide solid-state electrolyte or a sulfide solid-state electrolyte. Here, a sulfide-based solid-state electrolyte with high lithium-ion conductivity is preferably used. The sulfide-based solid-state electrolyte is not particularly limited and can be 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 any one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (where x and y are positive numbers and M is any one of P, Si, Ge, B, Al, Ga, and In), Li 10 GeP2S 12 etc. The solid-state electrolyte can be the same as or different from the solid-state electrolyte included in the electrolyte layer 30.

[0078] The conductive material can be carbon black, conductive graphite, ethylene black, graphene, etc.

[0079] The binder can be BR (butadiene rubber), NBR (nitrile rubber), HNBR (hydrogenated nitrile rubber), PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), CMC (carboxymethyl cellulose), etc., and can be the same as or different from the binder included in the lithium storage layer 20.

[0080] The cathode current collector layer 50 can be made of aluminum foil, etc.

[0081] Figure 3 A flowchart illustrating the process of manufacturing an all-solid-state battery according to the present disclosure is provided. Referring to the figure, the manufacturing method includes: preparing a first adhesive solution comprising a polyvinylidene fluoride (PVDF) binder and a first solvent; preparing a second adhesive solution comprising a nitrile rubber (NBR) binder and a second solvent; preparing a first slurry comprising a carbon material, metal powder, and the first adhesive solution; preparing a second slurry by adding the second adhesive solution to the first slurry; forming a second layer by applying the second slurry onto a substrate; forming a first layer by applying the first slurry onto the second layer; obtaining a lithium storage layer comprising the first and second layers; and forming an all-solid-state battery, wherein an anode current collector, a lithium storage layer, an electrolyte layer, and a cathode layer are sequentially laminated.

[0082] The all-solid-state battery according to this disclosure is characterized in that the porosity of the second layer 22 is higher than that of the first layer 21. Therefore, the solid content of the second slurry can be adjusted to be lower than that of the first slurry. Specifically, the solid content of the first slurry can be from 4 wt% to 10 wt%, and the solid content of the second slurry can be 3 wt% or less.

[0083] Furthermore, the all-solid-state battery according to this disclosure is characterized in that the binder content per unit volume of the interface portion 22a in the second layer 22 is higher than the binder content per unit volume of the core portion 22b. Therefore, after the second slurry is applied to the substrate, the second layer can be dried or left to stand, allowing the second binder solution to rise to the surface of the second layer 22.

[0084] Here, in order to adjust the fluidity of the second adhesive solution, the first solvent and the second solvent can be appropriately selected.

[0085] The second solvent may have a lower density than the first solvent.

[0086] The first solvent selected is one in which the solubility of polyvinylidene fluoride (PVDF) adhesive is higher than that of nitrile rubber (NBR) adhesive, and the second solvent selected is one in which the solubility of nitrile rubber (NBR) adhesive is higher than that of polyvinylidene fluoride (PVDF) adhesive.

[0087] Furthermore, the second solvent may have a higher vapor pressure than the first solvent.

[0088] When the second solvent contained in the second adhesive solution has a lower density than the first solvent, different solubilities of polyvinylidene fluoride (PVDF) adhesive and nitrile rubber (NBR) adhesive, or a higher vapor pressure than the first solvent, the fluidity of the second adhesive solution increases compared to the fluidity of the first adhesive solution, and thus allows the second layer 22 to stand for a predetermined period of time after its formation, thereby allowing the second adhesive solution to rise to the vicinity of the surface of the second layer to form the interface portion 22a.

[0089] The first solvent may include N-methyl-2-pyrrolidone (NMP).

[0090] The second solvent may include hexyl butyrate.

[0091] The second adhesive solution can rise more easily because polar solvents and non-polar solvents with different polarities are used as the first and second solvents.

[0092] There are no particular limitations on the method of laminating the anode current collector, lithium storage layer, electrolyte layer and cathode layer, and each configuration can be manufactured and then laminated, or each configuration can be laminated directly on the underlying configuration in sequence.

[0093] A better understanding of this disclosure can be obtained through the following embodiments. However, these embodiments are merely illustrative and should not be construed as limiting the scope of this disclosure.

[0094] Example

[0095] The first adhesive solution is prepared by mixing polyvinylidene fluoride (PVDF) adhesive and N-methyl-2-pyrrolidone (NMP) as the first solvent.

[0096] A second adhesive solution is prepared by mixing nitrile rubber (NBR) adhesive and hexyl butyrate as a second solvent.

[0097] The first slurry is prepared by mixing super C65 as a carbon material, silver (Ag) powder, and a first binder solution. A small amount of dispersant is added to this slurry.

[0098] Take out a portion of the first slurry and add a second adhesive solution to it to prepare a second slurry.

[0099] The solids content of the first slurry is adjusted to approximately 6%, and the solids content of the second slurry is adjusted to approximately 3%.

[0100] A second layer is formed by applying a second slurry to the anode current collector to a thickness of approximately 4 μm. The second layer is then dried to obtain a second layer comprising an interface portion and a core portion.

[0101] The first layer is formed by applying a first slurry to the second layer to a thickness of about 4 μm, and finally a lithium storage layer is obtained.

[0102] All-solid-state batteries are formed by laminating an electrolyte layer, a cathode layer, and a cathode current collector onto a lithium storage layer.

[0103] Comparative Example 1

[0104] The all-solid-state battery was formed in the same manner as in the example, except that the lithium storage layer was formed by applying the first slurry of the example to the anode current collector to a thickness of about 8 μm.

[0105] Comparative Example 2

[0106] The solids content of the first slurry in the embodiment was adjusted to about 3%, and then the first slurry was applied to the anode current collector to a thickness of about 4 μm to form a second layer.

[0107] The first layer is formed by applying the first slurry (with a solid content of about 6%) of the embodiment onto the second layer. The same procedure as in the embodiment is performed to form an all-solid-state battery.

[0108] Test Example 1 - Measurement of Adhesion and Porosity

[0109] The adhesion and porosity of the lithium storage layers in Examples 1, 2, and 3 were measured. The results are shown in Table 1 below.

[0110] Table 1

[0111]

[0112] As is evident from Table 1, in the embodiments, the adhesion force between the first and second layers is approximately 1.6 gf / mm, but in Comparative Example 2, separation occurs immediately, and therefore it is impossible to assess the adhesion force. Therefore, as in this disclosure, when the lithium storage layer is configured such that the second layer includes an interface portion and a core portion having a high binder content per unit volume, separation of the two layers due to volume expansion of the second layer can be suppressed.

[0113] Test Example 2 - Analysis using Scanning Electron Microscopy (SEM)

[0114] Scanning electron microscopy was performed on the all-solid-state batteries of Examples 1 and Comparative Example 1.

[0115] Figure 4 The figure shows a cross-section of the all-solid-state battery of the embodiment during charging. Referring to the figure, it can be seen that lithium is uniformly deposited between the lithium storage layer 20 and the anode current collector.

[0116] at the same time, Figure 5The figure shows a cross-section of the all-solid-state battery of the comparative embodiment during charging. Referring to the figure, it can be seen that lithium is irregularly deposited and dead lithium is formed in the lithium storage layer.

[0117] Test Example 3 - Evaluation of Charge / Discharge Characteristics

[0118] The capacity retention and coulombic efficiency of the all-solid-state batteries of Example 1 and Comparative Example 1 were measured and evaluated.

[0119] Figure 6A The measurement results of capacity retention are shown, and Figure 6B The measurement results of coulombic efficiency are shown. Referring to the figure, it can be seen that the capacity retention and coulombic efficiency of the all-solid-state battery of the embodiment are better than those of the all-solid-state battery of the comparative embodiment.

[0120] The test examples and embodiments of this disclosure have been described in detail above, but the scope of this disclosure is not limited to the test examples and embodiments described above. Those skilled in the art can use the basic concepts of this disclosure to design various modifications and improvements.

Claims

1. An anode-free all-solid-state battery, comprising: Anode current collector; A lithium storage layer comprising: The first layer, which is located on the electrolyte layer side, and The second layer, located on the anode current collector side, has a higher porosity than the first layer and includes an interface portion and a core portion that is the remaining portion excluding the interface portion. Electrolyte layer; and cathode layer, The anode current collector, lithium storage layer, electrolyte layer, and cathode layer are sequentially laminated, and The interface portion contacts the first layer and has a higher adhesive content per unit volume than the core portion.

2. The all-solid-state battery according to claim 1, wherein the lithium storage layer comprises carbon material and metal powder.

3. The all-solid-state battery according to claim 2, wherein the carbon material comprises at least one selected from the group consisting of particulate carbon material, fibrous carbon material, and combinations thereof.

4. The all-solid-state battery according to claim 3, wherein the particulate carbon material comprises at least one selected from the group consisting of graphitizable carbon, non-graphitizable carbon, and combinations thereof.

5. The all-solid-state battery according to claim 3, wherein the particulate carbon material is carbon black.

6. The all-solid-state battery according to claim 3, wherein the fibrous carbon material comprises at least one selected from the group consisting of carbon nanofibers, carbon nanotubes, vapor-grown carbon fibers, and combinations thereof.

7. The all-solid-state battery according to claim 2, wherein the metal powder comprises at least one selected from the group consisting of aluminum (Al), zinc (Zn), indium (In), silver (Ag), gold (Au), magnesium (Mg), bismuth (Bi), germanium (Ge), platinum (Pt), antimony (Sb), and combinations thereof.

8. The all-solid-state battery according to claim 1, wherein the thickness ratio of the first layer to the second layer is 1:0.5-2.

9. The all-solid-state battery according to claim 1, wherein the first layer has a porosity of 5% or less.

10. The all-solid-state battery of claim 1, wherein the second layer has a porosity of 5% to 50%.

11. The all-solid-state battery of claim 1, wherein the first layer comprises polyvinylidene fluoride (PVDF) adhesive.

12. The all-solid-state battery according to claim 1, wherein the second layer comprises polyvinylidene fluoride (PVDF) adhesive and nitrile rubber (NBR) adhesive.

13. The all-solid-state battery of claim 1, wherein the interface portion has a higher content of nitrile rubber binder per unit volume than the core portion.

14. The all-solid-state battery according to claim 1, wherein the thickness of the interface portion is 0.1% to 10% of the thickness of the second layer.

15. A method for manufacturing an anode-free all-solid-state battery, the method comprising the following steps: Prepare a first adhesive solution comprising polyvinylidene fluoride (PVDF) adhesive and a first solvent; A second adhesive solution comprising nitrile rubber (NBR) adhesive and a second solvent different from the first solvent is prepared; Prepare a first slurry comprising carbon material, metal powder, and the first binder solution; A second slurry is prepared by adding the second adhesive solution to the first slurry; A second layer is formed by applying the second slurry onto the substrate; A first layer is formed by applying the first slurry onto the second layer, and a lithium storage layer comprising the first layer and the second layer is obtained; and All-solid-state batteries are formed by sequentially laminating an anode current collector, a lithium storage layer, an electrolyte layer, and a cathode layer. Wherein: the first layer of the lithium storage layer is located on the electrolyte layer side, and the second layer, which has a higher porosity than the first layer, is located on the anode current collector side. The second layer includes an interface portion that contacts the first layer and a core portion that is the remaining portion excluding the interface portion. The interface portion has a higher adhesive content per unit volume than the core portion.

16. The method of claim 15, wherein the second solvent has a lower density than the first solvent, the solubility of the nitrile butadiene rubber (NBR) adhesive in the second solvent is higher than the solubility of the polyvinylidene fluoride (PVDF) adhesive in the second solvent, or the second solvent has a higher vapor pressure than the first solvent.

17. The method of claim 15, wherein the first solvent comprises N-methyl-2-pyrrolidone (NMP) and the second solvent comprises hexyl butyrate.

18. The method of claim 15, wherein the second slurry has a lower solids content than the first slurry.

19. The method of claim 15, wherein the solids content of the first slurry is from 4 wt% to 10 wt%.

20. The method of claim 15, wherein the solids content of the second slurry is 3 wt% or less.

21. The method of claim 15, further comprising the step of: After the second slurry is applied to the substrate, the second layer is dried.

22. The method of claim 15, further comprising the step of: After the second slurry is applied to the substrate, the second layer is left to stand, allowing the second adhesive solution to rise to the surface of the second layer.

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