Binder solution for all-solid-state battery and electrode paste including the solution

Abstract

The present disclosure relates to an adhesive solution having a lithium ion conductivity for all-solid-state batteries and an electrode paste including the adhesive solution. Specifically, the adhesive solution includes: a first adhesive having a high binding force; a second adhesive having a higher lithium ion conductivity than the first adhesive; a lithium salt; and an organic solvent for dissolving the lithium salt.

Description

Technical Field

[0001] The present disclosure relates to an adhesive solution having a lithium ion conductivity for an all-solid-state battery and an electrode paste including the solution. Background Art

[0002] Rechargeable and dischargeable batteries are used not only in small electronic devices such as mobile phones and laptop computers, but also in large vehicles such as hybrid vehicles and electric vehicles. Therefore, it is necessary to develop secondary batteries having higher stability and energy density.

[0003] Since most conventional secondary batteries use an organic solvent (organic liquid electrolyte) to form a cell, there are limitations in improving stability and energy density.

[0004] Meanwhile, since all-solid-state batteries using an inorganic solid electrolyte are based on a technology that excludes organic solvents, battery cells can be manufactured in a safer and simpler manner, and thus have recently received wide attention.

[0005] The electrodes of all-solid-state batteries include electrode active materials and solid electrolytes. That is, all components of the electrodes of all-solid-state batteries are solid. Therefore, in an all-solid-state battery using a solid electrolyte, a lithium ion transport path is formed when fine particles come into contact with each other. In addition, the electrodes of all-solid-state batteries are mainly formed by a wet process. For this purpose, an adhesive must be added. In particular, in order to apply a sulfide solid electrolyte having a high lithium ion conductivity, a non-polar polymer adhesive needs to be used to suppress chemical reactions. However, the lithium ion conductivity of such a polymer adhesive is low, which limits the capacity, life, and output characteristics of the battery. Summary of the Invention

[0006] Accordingly, an object of the present disclosure is to provide an adhesive solution for an all-solid-state battery that can provide a binding force between constituent materials of an electrode and form an effective lithium ion transport path in the electrode.

[0007] Another object of the present disclosure is to provide an adhesive solution suitable for manufacturing an all-solid-state battery having a large area.

[0008] Still another object of the present disclosure is to provide an adhesive solution suitable for manufacturing an all-solid-state battery that can operate even in a high-temperature environment.

[0009] The objects of the present disclosure are not limited to the foregoing objects, and will be clearly understood through the following description and can be achieved by the means described in the claims and their combinations.

[0010] Embodiments of the present disclosure provide an adhesive solution for all-solid-state batteries, the adhesive solution comprising: a first adhesive; a second adhesive having a higher lithium-ion conductivity than the first adhesive; a lithium salt; and an organic solvent that dissolves the lithium salt.

[0011] The first adhesive may be selected from the group consisting of nitrile rubber (NBR), butadiene rubber (BR), styrene-butadiene rubber (SBR), and combinations thereof.

[0012] The first adhesive may have a lithium-ion conductivity (σ -6 ) of 10 -7 S / cm to 10 1 S / cm.

[0013] The second adhesive may be selected from the group consisting of poly(propylene carbonate) (PPC), poly(vinyl acetate) (PVA), poly(1,4-butanediol adipate) diol (PBA), and combinations thereof.

[0014] The second adhesive may be at least partially miscible with the first adhesive.

[0015] The ratio of the lithium-ion conductivity of the second adhesive to that of the first adhesive (σ 2 / σ 1 ) may be from 100 to 4000.

[0016] The lithium salt may be selected from the group consisting of lithium hexafluorophosphate (LiPF 6 ), lithium bis(fluorosulfonyl)imide salt (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(pentafluoroethylsulfonyl)imide (LiBETI), and combinations thereof.

[0017] The organic solvent may be selected from the group consisting of benzyl acetate, ethyl 4-methylbenzoate, anisole, ethyl p-anisate, benzyl isobutyrate, and combinations thereof.

[0018] The organic solvent may have a boiling point of 150°C to 300°C.

[0019] The vapor pressure of the organic solvent at room temperature may be from 0.001 mmHg to 10 mmHg.

[0020] The adhesive solution may include 10 wt% or less and more than 0 wt% of the first adhesive, 10 wt% or less and more than 0 wt% of the lithium salt, and the balance of the organic solvent.

[0021] The weight ratio of the second adhesive to the first adhesive (m 2 / m 1 ) may be 3 or less and more than 0.

[0022] Another embodiment of the present disclosure provides an electrode paste for an all-solid-state battery, which includes the above-mentioned binder solution, an electrode active material, a conductive material, and a solid electrolyte.

[0023] The electrode paste may include 30 wt% or less and more than 0 wt% of the binder solution, 10 wt% or less and more than 0 wt% of the conductive material, 20 wt% or less and more than 0 wt% of the solid electrolyte, and the balance of the electrode active material.

[0024] According to the present disclosure, the binder solution can provide a binding force between the constituent materials of the electrode, and since the binder solution itself has lithium-ion conductivity, a lithium-ion transport path can be more effectively formed in the electrode. Therefore, an all-solid-state battery with significantly improved charge / discharge capacity and extended lifespan can be obtained.

[0025] According to the present disclosure, the binder solution uses a solvent with low volatility, thereby ensuring the stability of the paste, and thus an all-solid-state battery with a large area can be manufactured.

[0026] Using the binder solution according to the present invention, an all-solid-state battery that does not deteriorate during high-temperature evaluation or high-temperature operation can be manufactured.

[0027] The effects of the present disclosure are not limited to the foregoing, and should be understood to include all effects that can be reasonably anticipated according to the following description. Description of the Drawings

[0028] Figure 1 is a schematic cross-sectional view showing an all-solid-state battery according to an embodiment of the present disclosure;

[0029] Figure 2A is a photograph showing a cathode manufactured using an electrode paste including the binder solution according to Embodiments 1-4 of the present disclosure;

[0030] Figure 2B is a photograph showing a cathode manufactured using an electrode paste including the binder solution according to Embodiments 2-4 of the present disclosure;

[0031] Figure 2C is a photograph showing a cathode manufactured using an electrode paste including the binder solution according to Embodiments 3-4 of the present disclosure;

[0032] Figure 3A is a photograph showing a cathode manufactured using an electrode paste including only polypropylene carbonate (PPC) as the second binder and not including the first binder;

[0033] Figure 3B is a photograph showing a cathode manufactured using an electrode paste including only polyvinyl acetate (PVA) as the second binder and not including the first binder;

[0034] Figure 3C is a photograph showing a cathode manufactured using an electrode paste that includes only poly(butylene adipate) diol (PBA) as a second binder and does not include a first binder;

[0035] Figure 4A and Figure 4B shows the measurement results of the charge / discharge capacity and rate characteristics when a all-solid-state battery manufactured using the binder solutions of Comparative Example 1 and Examples 1-1 to 1-4 is charged and discharged at room temperature in Experimental Example 2 according to the present disclosure;

[0036] Figure 5A and Figure 5B shows the measurement results of the charge / discharge capacity and rate characteristics when a all-solid-state battery manufactured using the binder solutions of Comparative Example 1 and Examples 2-1 to 2-4 is charged and discharged at room temperature in Experimental Example 2 according to the present disclosure;

[0037] Figure 6A and Figure 6B shows the measurement results of the charge / discharge capacity and rate characteristics when a all-solid-state battery manufactured using the binder solutions of Comparative Example 1 and Examples 3-1 to 3-4 is charged and discharged at room temperature in Experimental Example 2 according to the present disclosure; and

[0038] Figure 7A and Figure 7B shows the measurement results of the charge / discharge capacity and rate characteristics when a all-solid-state battery manufactured using the binder solutions of Examples 4 and 5 is charged and discharged at about 70 °C in Experimental Example 3 according to the present disclosure. DETAILED DESCRIPTION

[0039] The above and other objects, features, and advantages of the present disclosure will be more clearly understood in conjunction with the accompanying drawings and according to the following preferred embodiments. However, the present disclosure is not limited to the embodiments disclosed herein and can be modified into different forms. These embodiments are intended to fully explain the present disclosure and convey the idea of the present disclosure to those skilled in the art.

[0040] Throughout the drawings, the same reference numerals will refer to the same or similar elements. For clarity of the present disclosure, the dimensions of the structures are depicted as larger than their actual dimensions. It will be understood that although terms such as "first", "second", etc. used herein may describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present disclosure, the "first" element discussed below may be referred to as the "second" element. Similarly, the "second" element may also be referred to as the "first" element. As used herein, unless the context clearly dictates otherwise, the singular forms are also intended to include the plural forms.

[0041] It will be further understood that the terms "comprising", "including", "having", etc. used in this specification specify the presence of the stated features, integers, steps, operations, elements, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof. Moreover, it will be understood that when an element such as a layer, film, region or sheet is referred to as being "on" another element, it can be directly on the other element, or intervening elements may be present therebetween. Similarly, when an element such as a layer, film, region or sheet is referred to as being "under" another element, it can be directly under the other element, or intervening elements may be present therebetween.

[0042] Unless otherwise specified in detail, all numbers, values and / or representations indicating the amounts of ingredients, reaction conditions, polymer compositions and mixtures used herein will be considered approximate values, and thus it should be understood that they can be modified by the term "about" in all cases. This approximation includes various uncertainties and other factors that substantially affect the measurement results when obtaining these values. In addition, when this specification discloses a numerical range, the range is continuous and includes all values from the minimum value to the maximum value of the stated range, unless otherwise stated. Moreover, when such a range pertains to integer values, it includes all integers from the minimum value to the maximum value, unless otherwise stated.

[0043] Figure 1 is a schematic cross-sectional view showing a all-solid-state battery according to an embodiment of the present disclosure. The all-solid-state battery 1 includes: a solid electrolyte layer 10; a cathode 20 formed on one surface of the solid electrolyte layer 10; and an anode 30 formed on the other surface of the solid electrolyte layer 10. Hereinafter, the term "electrode" generally refers to the cathode 20 or the anode 30.

[0044] At least one of the solid electrolyte layer 10, the cathode 20, and the anode 30 includes a binder. The binder is derived from a binder solution. Hereinafter, the binder solution according to the present disclosure will be described in detail.

[0045] Binder solution

[0046] The binder solution according to the present disclosure may include: a first binder; a second binder having a higher lithium ion conductivity than the first binder; a lithium salt; and an organic solvent that dissolves the lithium salt.

[0047] The first binder provides a binding force between the constituent materials of the solid electrolyte layer and the electrode.

[0048] The first binder may be selected from the group consisting of nitrile-butadiene rubber (NBR), butadiene rubber (BR), styrene butadiene rubber (SBR), and combinations thereof.

[0049] The first binder that provides the binding force has a low lithium ion conductivity and thus can interfere with the transport of lithium ions in the solid electrolyte layer and the electrode. Specifically, the lithium ion conductivity (σ 1 ) of the first binder may fall within the range of 10 -6 S / cm to 10 -7 S / cm.

[0050] Therefore, the present disclosure is characterized in that the above problems are solved by adding a second binder and a lithium salt.

[0051] The second binder increases the lithium ion conductivity in the solid electrolyte layer and the electrode.

[0052] The second binder is miscible with the first binder, the lithium salt, and the organic solvent. In particular, the second binder may be at least partially miscible with the first binder. As used herein, the term "miscible" means that two materials are stably mixed so that the product produced by mixing the two materials has the desired properties. Here, the two materials may have a physically and / or chemically bonded relationship.

[0053] The second binder may be selected from the group consisting of poly(propylene carbonate) (PPC), poly(vinyl acetate) (PVA), poly(1,4-butylene adipate) (PBA), and combinations thereof.

[0054] Since the second binder has a high lithium ion conductivity, the binder solution including the second binder itself can have a lithium ion conductivity. Specifically, the ratio of the lithium ion conductivity of the second binder to that of the first binder (σ 2 / σ 1 ) can be from 100 to 4000. For example, polypropylene carbonate (PPC) that can be used as the second binder has a maximum lithium ion conductivity of about 4x10 -4 S / cm, while polyvinyl acetate (PVA) and poly(butylene adipate) diol (PBA) have a maximum lithium ion conductivity of about 10 -5 S / cm.

[0055] In addition, the present disclosure is characterized in that the lithium ion conductivity is further improved by adding a lithium salt together with the second binder. The lithium salt can be miscible with the organic solvent, the first binder, and the second binder and is available. The term "available" herein means that when two materials are used together, there is no side reaction and each property of the two materials is manifested as it is.

[0056] The lithium salt can be selected from the group consisting of lithium hexafluorophosphate (LiPF 6 ), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), and combinations thereof.

[0057] The organic solvent can dissolve the first binder, the second binder, and the lithium salt.

[0058] The organic solvent can have a boiling point of 150 °C to 300 °C. During the manufacturing process of the all-solid-state battery, the drying temperature is generally 60 °C to 120 °C. Therefore, during the above drying process, the organic solvent will not disappear due to evaporation.

[0059] In addition, the vapor pressure of the organic solvent at room temperature can be from 0.001 mmHg to 10 mmHg. That is to say, the volatility of the organic solvent may be low. Therefore, the organic solvent will not evaporate during the manufacturing process of the all-solid-state battery.

[0060] Therefore, when the above-mentioned organic solvent is used, the stability of the binder solution and the electrode paste including the binder solution can be greatly improved, which is advantageous for manufacturing an all-solid-state battery with a large area.

[0061] There is no particular limitation on the organic solvent as long as it satisfies the above requirements, and it may be selected from the group consisting of benzyl acetate, ethyl 4-methylbenzoate, anisole, ethyl p-anisate, benzyl isobutyrate, and combinations thereof.

[0062] The binder solution may include 10 wt% or less and more than 0 wt% of a first binder and a second binder. When the sum of the amounts of the first binder and the second binder falls within the above range, the binding force and lithium ion conductivity of the binder solution can be balancedly obtained at a desired level.

[0063] Here, the weight ratio (m 2 / m l ) of the second binder to the first binder may be 3 or less and more than 0. If the weight ratio is greater than 3, the amount of the second binder is excessive, and thus the binding force of the binder solution may be insufficient.

[0064] The binder solution may include 10 wt% or less and more than 0 wt% of a lithium salt, preferably 3 wt% or less and more than 0 wt% of a lithium salt. Moreover, the amount of the lithium salt can be appropriately adjusted according to the type of the second binder.

[0065] Electrode of all-solid-state battery

[0066] The electrode of the all-solid-state battery according to the present disclosure can be manufactured by a wet process. Specifically, the electrode can be manufactured in the following manner: preparing an electrode paste including a binder solution, an electrode active material, a conductive material, and a solid electrolyte, then coating it on a substrate, and drying it.

[0067] The electrode paste may include 30 wt% or less and more than 0 wt% of a binder solution, 10 wt% or less and more than 0 wt% of a conductive material, 20 wt% or less and more than 0 wt% of a solid electrolyte, and the balance of an electrode active material.

[0068] Since the binder solution has been described above, a detailed description of the binder solution is omitted.

[0069] The electrode active material may be a cathode active material or an anode active material.

[0070] There is no particular limitation on the cathode active material, but it may be, for example, an oxide active material or a sulfide active material.

[0071] The oxide active material may be a rock salt layer type active material such as LiCoO 2 , LiMnO 2 , LiNiO 2 , LiVO 2 , Li 1+x Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 , a spinel type active material such as LiMn 2 O 4 , Li(Ni 0.5 Mn 1.5 )O 4 , an inverse spinel type active material such as LiNiVO 4 , LiCoVO 4 , an olivine type active material such as LiFePO 4 , LiMnPO 4 , LiCoPO 4 , LiNiPO 4 , a silicon-containing active material such as Li 2 FeSiO 4 , Li 2 MnSiO 4 , a rock salt layer type active material in which part of the transition metal is replaced by a foreign metal such as LiNi 0.8 Co (0.2-x) AlxO 2 (0 < x < 0.2), a spinel type active material in which part of the transition metal is replaced by a foreign metal such as Li 1+x Mn 2-x-y MyO 4 (M is at least one of Al, Mg, Co, Fe, Ni and Zn, 0 < x + y < 2), or lithium titanate such as Li 4 Ti 5 O 12 .

[0072] The sulfide active material may be copper chevrel, iron sulfide, cobalt sulfide, nickel sulfide, etc.

[0073] There is no particular limitation on the anode active material, but it may be, for example, a carbon active material or a metal active material.

[0074] The carbon active material can be graphite such as mesocarbon microbeads (MCMB), highly oriented pyrolytic graphite (HOPG), or amorphous carbon such as hard carbon and soft carbon.

[0075] The metal active material can be In, Al, Si, Sn, or an alloy including at least one element of In, Al, Si, and Sn.

[0076] The conductive material functions to form an electron conduction path in the electrode. The conductive material can be an sp 2 carbon material or graphene such as carbon black, conducting graphite, ethylene black, or carbon nanotubes.

[0077] The solid electrolyte can be an oxide solid electrolyte or a sulfide solid electrolyte. Here, a sulfide solid electrolyte with high lithium ion conductivity is preferably used.

[0078] The sulfide solid electrolyte can be Li 2 S-P 2 S 5 、Li 2 S-P 2 S 5 -LiI、Li 2 S-P 2 S 5 -LiC1、Li 2 S-P 2 S 5 -LiBr、Li 2 S-P 2 S 5 -Li 2 O、Li 2 S-P 2 S 5 -Li 2 O-LiI、Li 2 S-SiS 2 、Li 2 S-SiS 2 -LiI、Li 2 S-SiS 2 -LiBr、Li 2 S-SiS 2 -LiCl、Li 2 S-SiS 2 -B 2 S 3 -LiI、Li 2 S-SiS 2 -P 2 S 5 -LiI、Li2 S-B 2 S 3 、Li 2 S-P 2 S 5 -Z m S n (where m and n are positive numbers, and Z is any one of Ge, Zn, and Ga), Li 2 S-GeS 2 、Li 2 S-SiS 2 -Li3PO 4 、Li 2 S-SiS 2 -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 GeP 2 S 12 etc.

[0079] Solid electrolyte layer of all-solid-state battery

[0080] The solid electrolyte layer 10 is located between the cathode 20 and the anode 30, enabling lithium ions to move between the two electrodes.

[0081] The solid electrolyte layer 10 can be fabricated by a wet process. Specifically, the solid electrolyte layer can be fabricated in the following manner: Prepare a solid electrolyte layer slurry comprising a binder solution and a solid electrolyte, then coat it on a substrate or an electrode and dry it.

[0082] Since the binder solution has been described above, a detailed description of the binder solution is omitted.

[0083] The solid electrolyte layer 10 can include the same or different solid electrolytes as those included in the above electrodes. Here, it is preferably to include a sulfide solid electrolyte having a high lithium ion conductivity.

[0084] The present disclosure will be better understood through the following examples, which are only presented to illustrate the present disclosure and should not be construed as limiting the scope of the present disclosure.

[0085] Examples and Comparative Examples

[0086] A binder solution was obtained by dissolving the first binder and the second binder shown in Table 1 below together with lithium bis(fluorosulfonyl)imide (LiFSI) as a lithium salt in an organic solvent.

[0087] An electrode paste is prepared by mixing 26.1 wt% of a binder solution, 54.4 wt% of an electrode active material, 0.8 wt% of a conductive material, and 18.7 wt% of a solid electrolyte. Using a rock-salt-layer-type cathode active material Li 1+x Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 as the electrode active material, the conductive material is carbon black, and the solid electrolyte is Li 2 S-P 2 S 5 -LiC1.

[0088] The electrode paste is coated on the solid electrolyte layer and dried at about 60 °C for 2 hours to form a cathode.

[0089] A lithium-indium foil (Li-In foil) used as an anode is attached to the stack of the cathode and the solid electrolyte layer to complete the all-solid-state battery.

[0090] As a reference, this example aims to prove whether the above effects are obtained when manufacturing a cathode using an ion-conductive additive. It will be obvious to those skilled in the art that the above effects cannot be obtained only when using lithium metal as the anode, and even when completing the all-solid-state battery using an anode manufactured in the same or similar manner as the cathode, the same effects can be obtained.

[0091] Table 1

[0092]

[0093] Experimental Example 1

[0094] Figure 2A is a photograph showing a cathode manufactured using an electrode paste including the binder solution of Examples 1-4, Figure 2B is a photograph showing a cathode manufactured using an electrode paste including the binder solution of Examples 2-4, Figure 2C is a photograph showing a cathode manufactured using an electrode paste including the binder solution of Examples 3-4.

[0095] Figure 3A is a photograph showing a cathode manufactured using an electrode paste including only poly(propylene carbonate) (PPC) as the second binder and not including the first binder. Figure 3B is a photograph showing a cathode manufactured using an electrode paste including only poly(vinyl acetate) (PVA) as the second binder and not including the first binder. Figure 3C is a photograph showing a cathode manufactured using an electrode paste including only poly(butylene adipate) diol (PBA) as the second binder and not including the first binder.

[0096] When comparing Figure 2A with Figure 3A , Figure 2B with Figure 3B and Figure 2C with Figure 3C it can be seen that when using the adhesive solution containing only the second adhesive, the adhesion of the electrode is poor. And it can be confirmed that when the first adhesive and the second adhesive are used simultaneously, the electrode is formed uniformly due to the high adhesion of the electrode.

[0097] Experimental Example 2

[0098] When the all-solid-state batteries manufactured using the adhesive solutions of Comparative Example 1 and Examples 1-1 to 1-4 are charged and discharged at room temperature, the charge / discharge capacity and rate characteristics are measured. The measurement results are shown in Figure 4A and Figure 4B .

[0099] When the all-solid-state batteries manufactured using the adhesive solutions of Comparative Example 1 and Examples 2-1 to 2-4 are charged and discharged at room temperature, the charge / discharge capacity and rate characteristics are measured. The measurement results are shown in Figure 5A and Figure 5B .

[0100] When the all-solid-state batteries manufactured using the adhesive solutions of Comparative Example 1 and Examples 3-1 to 3-4 are charged and discharged at room temperature, the charge / discharge capacity and rate characteristics are measured. The measurement results are shown in Figure 6A and Figure 6B .

[0101] The measurement results of the initial coulombic efficiency of the all-solid-state batteries manufactured using the adhesive solutions according to the Examples and Comparative Examples are shown in Table 2 below.

[0102] Table 2

[0103] Number Initial coulombic efficiency [%] Comparative Example 1 78.1 Example 1-1 79.2 Example 1-2 78.4 Example 1-3 80.3 Example 1-4 79.2 Example 2-1 78.9 Example 2-2 80.5 Example 2-3 80.2 Example 2-4 81.5 Example 3-1 77.2 Example 3-2 80.4 Example 3-3 80.9 Example 3-4 81.9 Example 4 84.2 Example 5 91.8

[0104] Referring to Figure 4A and Figure 4B and Table 2, it can be seen that compared with Comparative Example 1, the all-solid-state batteries of Examples 1-1 to 1-4 exhibit high initial coulombic efficiency and improved discharge capacity and rate characteristics. This is because the adhesive solution according to the present disclosure includes a second adhesive having a high lithium ion conductivity, and thus exhibits a high lithium ion conductivity.

[0105] Referring to Figure 5A and Figure 5BAs can be seen from Table 2, compared with Comparative Example 1, the all-solid-state batteries of Examples 2-1 to 2-4 exhibit high initial Coulomb efficiency and improved discharge capacity and rate characteristics. Compared with Comparative Example 1, in the case of Example 2-2, the rate characteristics slightly decrease from 0.7C and 1.0C, but all other indicators are improved and are superior to Comparative Example 1.

[0106] Referring to Figure 6A and Figure 6B As can be seen from Table 2, the all-solid-state batteries of Examples 3-1 to 3-4 exhibit initial Coulomb efficiency, discharge capacity, and rate characteristics that are equal to or superior to those of Comparative Example 1. Compared with Comparative Example 1, in the case of Example 3-1, the rate characteristics slightly decrease, but can be fully compensated by adding a lithium salt.

[0107] Experimental Example 3

[0108] When the all-solid-state batteries manufactured using the binder solutions according to Examples 4 and 5 are charged and discharged at about 70°C, the charge / discharge capacity and rate characteristics are measured. The measurement results are shown in Figure 7A and Figure 7B . Referring to Figure 7A and Figure 7B , the all-solid-state batteries of Examples 4 and 5 exhibit stable performance at high temperatures. In addition, compared with the evaluation results at room temperature, the discharge capacity and rate characteristics are improved. In particular, in the case of Example 5 including a lithium salt, the degree of improvement in the discharge capacity and rate characteristics is greater.

[0109] Although specific embodiments of the present disclosure have been described with reference to the drawings, those skilled in the art will understand that the present disclosure can be implemented in other specific forms without changing the technical idea or basic characteristics of the present disclosure. Therefore, the above embodiments should be understood as being non-limiting and illustrative in all aspects.

Claims

1. An adhesive solution for all-solid-state batteries, comprising: a first adhesive having a lithium ion conductivity; a second adhesive having a higher lithium ion conductivity than the first adhesive; a lithium salt; and an organic solvent that dissolves the lithium salt, wherein the first adhesive comprises nitrile rubber (NBR), wherein the second adhesive is selected from the group consisting of poly(propylene carbonate) (PPC), poly(vinyl acetate) (PVA), poly(butylene adipate) (PBA), and combinations thereof, wherein the lithium ion conductivity σ of the first binder 1 is 10 -6 S / cm to 10 -7 S / cm, wherein the lithium ion conductivity σ of the second adhesive 2 is 4×10 -4 S / cm to 10 -5 S / cm, wherein the weight ratio m of the second adhesive to the first adhesive 2 / m 1 is 3 or less and more than 0 wherein the lithium salt is selected from the group consisting of lithium hexafluorophosphate (LiPF 6 ), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(pentafluoroethylsulfonyl)imide (LiBETI), and combinations thereof; wherein the second adhesive is miscible with the first adhesive, the lithium salt, and the organic solvent, the adhesive solution comprising: less than or equal to 10 wt% and more than 0 wt% of the first adhesive and the second adhesive; 0.5 wt% to 3 wt% of the lithium salt, and the balance of the organic solvent, wherein the organic solvent is the balance of the adhesive solution, whereby the weight percentages of the first adhesive, the second adhesive, the lithium salt, and the organic solvent total 100 wt%.

2. The adhesive solution according to claim 1, wherein the second adhesive is at least partially miscible with the first adhesive.

3. The adhesive solution according to claim 1, wherein the lithium ion conductivity ratio σ 2 / σ 1 of the second adhesive and the first adhesive is from 100 to 4000.

4. The adhesive solution according to claim 1, wherein the organic solvent is selected from the group consisting of benzyl acetate, ethyl 4-methylbenzoate, anisole, ethyl p-anisate, benzyl isobutyrate, and combinations thereof.

5. The adhesive solution according to claim 1, wherein the organic solvent has a boiling point of 150 °C to 300 °C.

6. The adhesive solution according to claim 1, wherein the organic solvent has a vapor pressure of 0.001 mmHg to 10 mmHg at room temperature.

7. An electrode paste for all-solid-state batteries, comprising: the adhesive solution according to claim 1; an electrode active material; a conductive material; and a solid electrolyte.

8. The electrode paste according to claim 7, comprising: 30 wt% or less and more than 0 wt% of the adhesive solution; 10 wt% or less and more than 0 wt% of the conductive material; 20 wt% or less and more than 0 wt% of the solid electrolyte; and the balance of the electrode active material, wherein the electrode active material is the balance of the electrode paste, whereby the weight percentages of the adhesive solution, the conductive material, the solid electrolyte, and the electrode active material total 100 wt%.

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