All-solid-state secondary battery and method for detecting coating of adhesive layer of all-solid-state secondary battery

Abstract

An all-solid-state secondary battery according to one embodiment of the present invention comprises: a positive electrode; a negative electrode; solid electrolyte layers between the positive electrode and the negative electrode; and an adhesive layer disposed between the positive electrode and the solid electrolyte layers, between the negative electrode and the solid electrolyte layers, between the solid electrolyte layers, or a combination thereof, wherein the adhesive layer includes an adhesive and a fluorescein-based dye. A method for detecting the coating of an adhesive layer of an all-solid secondary battery according to one embodiment of the present invention comprises: a step for preparing an electrode-solid electrolyte layer stack by laminating a solid electrolyte layer on an electrode; a step for forming an adhesive layer by coating a surface of the solid electrolyte layer of the electrode-solid electrolyte layer stack with an adhesive composition including an adhesive, a fluorescein-based dye, and a solvent; and a step for irradiating the adhesive layer with UV rays and confirming whether the surface of the solid electrolyte layer is coated with the adhesive layer on the basis of fluorescence emitted from the adhesive layer.

Description

All-solid-state secondary battery and method for detecting coating of the adhesive layer of the all-solid-state secondary battery

[0001] This relates to an all-solid-state secondary battery and a method for detecting the coating of the adhesive layer of an all-solid-state secondary battery.

[0002] Recently, driven by industrial demands, the development of batteries with high energy density and safety is actively underway. For example, lithium-ion batteries are being commercialized not only in the fields of information and communication devices but also in the automotive sector. In the automotive sector, safety is considered particularly important because it is directly related to human life.

[0003] Since commercially available lithium-ion batteries use electrolytes containing flammable organic solvents, there is a possibility of overheating and fire in the event of a short circuit. In response to this, all-solid-state secondary batteries using solid electrolytes instead of liquid electrolytes are being proposed.

[0004] All-solid-state secondary batteries can significantly reduce the likelihood of fire or explosion in the event of a short circuit by not using flammable organic solvents. Therefore, these all-solid-state batteries can offer significantly higher safety compared to lithium-ion batteries that use liquid electrolytes.

[0005] The information described above, disclosed in the background technology of this invention, is intended only to enhance understanding of the background of this disclosure and may therefore include information that does not constitute prior art.

[0006] One embodiment provides an all-solid-state secondary battery having excellent interfacial adhesion between components and excellent lithium ion conductivity.

[0007] Another embodiment provides a method for detecting the coating of an adhesive layer of an all-solid-state secondary battery, which can easily verify whether the adhesive layer is uniformly coated.

[0008] One embodiment provides an all-solid-state secondary battery comprising: a positive electrode; a negative electrode; a solid electrolyte layer located between the positive electrode and the negative electrode; and an adhesive layer disposed at a location between the positive electrode and the solid electrolyte layer, between the negative electrode and the solid electrolyte layer, between the solid electrolyte layers, or a combination thereof, wherein the adhesive layer comprises an adhesive and a fluorescein-based dye.

[0009] Another embodiment provides a method for detecting the coating of an adhesive layer in an all-solid-state secondary battery, comprising: manufacturing an electrode-solid electrolyte layer laminate by laminating a solid electrolyte layer on an electrode; forming an adhesive layer by applying an adhesive composition comprising an adhesive and a fluorescein-based dye to the surface of the solid electrolyte layer of the electrode-solid electrolyte layer laminate; and irradiating UV light onto the adhesive layer and confirming whether the adhesive layer has been applied by the fluorescence emitted from the adhesive layer.

[0010] An all-solid-state secondary battery according to one embodiment has excellent interfacial adhesion between components and excellent lithium ion conductivity, and a method for detecting the coating of an all-solid-state secondary battery adhesive layer according to another embodiment can easily confirm whether the adhesive layer is uniformly coated.

[0011] FIGS. 1 to 7 are cross-sectional views schematically illustrating an all-solid-state secondary battery according to one embodiment.

[0012] Figure 8 is an image showing a case where the application uniformity of the adhesive layer is excellent.

[0013] Figure 9 is an image showing the case where the uniformity of the adhesive layer application is normal.

[0014] Figure 10 is an image showing a case where the uniformity of the adhesive layer application is insufficient.

[0015] Figure 11 is a graph evaluating the resistance of a symmetric cell according to the degree of uniformity of the adhesive layer application.

[0016] FIG. 12 is a graph evaluating the lithium ion conductivity of symmetric cells prepared in Example 1, Comparative Example 1, and Comparative Example 2.

[0017] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0018] Unless otherwise specifically stated in this specification, when a part such as a layer, film, region, plate, etc. is described as being "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between.

[0019] Unless otherwise specified in this specification, a singular form may also include a plural form. Additionally, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B."

[0020] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0021] Unless otherwise defined in this specification, particle size may be the average particle size. Additionally, particle size refers to the average particle size (D) which means the diameter of the particle whose cumulative volume in the particle size distribution is 50 volume%. 50 It means ). Average particle size (D 50The measurement can be performed using methods widely known to those skilled in the art, for example, by using a particle size analyzer, or by using transmission electron microscope (TEM) or scanning electron microscope (SEM) images. Alternatively, the measurement may be performed using a measuring device utilizing dynamic light scattering, and after analyzing the data to count the number of particles for each particle size range, the average particle size (D) is calculated from this. 50 ) values ​​can be obtained. Alternatively, it can be measured using the laser diffraction method. When measuring by the laser diffraction method, more specifically, after dispersing the particles to be measured in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), and ultrasound at approximately 28 kHz is irradiated at an output of 60 W. Then, the average particle size (D) at the 50% reference of the particle size distribution in the measuring device 50 ) can be produced.

[0022] The term "metal" is interpreted as a concept that includes ordinary metals, transition metals, and metalloids (semimetals).

[0023] "Substitution" means that at least one hydrogen atom is a halogen atom (F, Cl, Br, I), a hydroxyl group, a C1 to C20 alkoxy group, a nitro group, a cyano group, an amine group, an imino group, an azido group, an amidino group, a hydrazino group, a hydrazono group, a carbonyl group, a carbamyl group, a thiol group, an ester group, an ether group, a carboxyl group or its salt, a sulfonic acid group or its salt, a phosphoric acid or its salt, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C6 to C20 aryl group, a C3 to C20 cycloalkyl group, a C3 to C20 cycloalkenyl group, a C3 to C20 cycloalkynyl group, a C2 to C20 heterocycloalkyl group, a C2 to C20 heterocycloalkenyl group, a C2 to C20 It means substituted with a heterocycloalkynyl group, a C3 to C20 heteroaryl group, or a combination thereof.

[0024] Here, for example, C1 to C20 means having 1 to 20 carbon atoms.

[0025]

[0026] Method for detecting coating of an adhesive layer in a solid-state secondary battery

[0027] A method for detecting the coating of an adhesive layer of an all-solid-state secondary battery according to one embodiment comprises: a first step of manufacturing an electrode-solid electrolyte layer laminate by laminating a solid electrolyte layer on an electrode; a second step of forming an adhesive layer by applying an adhesive composition comprising an adhesive, a fluorescein-based dye, and a solvent to the surface of the solid electrolyte layer of the electrode-solid electrolyte layer laminate; and a third step of irradiating UV light onto the adhesive layer and confirming whether the adhesive layer has been applied by the fluorescence emitted from the adhesive layer.

[0028]

[0029] In the first step, the electrode may mean an anode, a cathode, or both, and the first step may be a step of laminating the electrode and a solid electrolyte layer to manufacture an anode-solid electrolyte layer laminate, a cathode-solid electrolyte layer laminate, or both.

[0030] The above lamination method may use a commonly used pressure method, and as an example, a roll press method may be used.

[0031] The above-mentioned manufactured laminate can be understood as a semi-finished product for manufacturing an all-solid-state secondary battery.

[0032] For example, an all-solid-state secondary battery can be manufactured by stacking an opposite electrode on the solid electrolyte layer surface of a semi-finished electrode-solid electrolyte layer laminate, and as a specific example, an all-solid-state secondary battery can be manufactured by stacking a positive electrode on the solid electrolyte layer surface of a negative electrode-solid electrolyte layer laminate. At this time, there was a problem that the interfacial adhesion between the solid electrolyte layer surface and the positive electrode was poor.

[0033] As another example, an all-solid-state secondary battery can be manufactured by separately producing an anode-solid electrolyte layer laminate and a cathode-solid electrolyte layer laminate, and stacking them so that the solid electrolyte layer surfaces of the laminates are in contact. However, there was a problem in that the interfacial adhesion between the contacting solid electrolyte layer surfaces was poor.

[0034] To solve such interfacial bonding problems, a method was used to form an adhesive layer by applying an adhesive composition to the interface; however, when the adhesive composition was colorless, there was a problem in that it was difficult to verify whether the adhesive layer was applied evenly.

[0035] If the adhesive layer is not applied evenly, the interfacial resistance increases only in specific parts of the adhesive layer, and there is a possibility that degradation will occur only in these parts during battery operation; therefore, it was very important to verify whether the adhesive composition was applied uniformly during the application process.

[0036] To this end, a method for detecting the application of an adhesive layer of an all-solid secondary battery according to one embodiment comprises: a second step of forming an adhesive layer by applying an adhesive composition comprising an adhesive, a fluorescein-based dye, and a solvent to the surface of a solid electrolyte layer of an electrode-solid electrolyte layer laminate; and a third step of irradiating UV light onto the adhesive layer and confirming whether the adhesive layer has been applied by the fluorescence emitted from the adhesive layer, thereby having the advantage of easily confirming whether the adhesive layer has been uniformly applied.

[0037] Adhesive composition

[0038] The above adhesive composition is applied between the electrode and the solid electrolyte layer, or between the solid electrolyte layer and the solid electrolyte layer, to form an adhesive layer.

[0039] In one embodiment, the adhesive composition comprises an adhesive, a fluorescein-based dye, and a solvent, and may optionally further comprise a lithium salt.

[0040] The adhesive may include a first adhesive, a second adhesive, or a combination thereof.

[0041] First adhesive

[0042] The first adhesive comprises a cyclic polymer, wherein the cyclic polymer comprises a first structural unit represented by the following structural formula 1A and a second structural unit represented by the following structural formula 1B, and

[0043] The first structural unit and the second structural unit can be joined to each other by a disulfide bond.

[0044] [Structural Formula 1A]

[0045]

[0046] In the above structural formula 1A, L1, L2, and L3 may each independently be a single bond, a C1 to C10 alkylene group, a C2 to C10 alkenylene group, or a C2 to C10 alkynylene group. For example, L1, L2, and L3 may each independently be a C1 to C3 alkylene group.

[0047] The above Y1 and the above Y2 may each independently be oxygen or sulfur. For example, the above Y1 and the above Y2 may each be oxygen.

[0048] The first structural unit can improve ion conductivity while providing adhesion to the adhesive layer.

[0049] [Structural Formula 1B]

[0050]

[0051] In the above structural formula 1B, L4 may be a single bond, a C1 to C20 alkylene group, a C2 to C20 alkenylene group, or a C2 to C20 alkynylene group. For example, L4 may be a C1 to C10 alkylene group.

[0052] The second structural unit can impart adhesiveness to the adhesive layer.

[0053] The first structural unit and the second structural unit may be bonded to each other by disulfide bonds (SS). Any one of the sulfur (S) atoms of the first structural unit may be covalently bonded to any one of the sulfur (S) atoms of the second structural unit. The remaining one of the sulfur (S) atoms of the first structural unit may be covalently bonded to the remaining one of the sulfur (S) atoms of the second structural unit.

[0054] The molar ratio of the first structural unit and the second structural unit in the first adhesive may be 2:1 to 1:2. For example, the molar ratio of the first structural unit and the second structural unit in the first adhesive may be 1.5:1 to 1:1.5, 1.5:1 to 1:1, 1:1 to 1:1.5, or 1:1.

[0055] The first structural unit may include a plurality of first structural units. The second structural unit may include a plurality of second structural units. The first structural unit and the second structural unit may be randomly arranged within the first adhesive.

[0056] For example, the first adhesive can be represented by the following structural formula 2-1.

[0057] [Structural Formula 2-1]

[0058]

[0059] In the above structural formula 2-1, n can be 1 to 1000 and m can be 1 to 1000. For example, n can be 1 to 500 and m can be 1 to 500. Or, for example, n can be 1 to 300 and m can be 1 to 300. Or, for example, n can be 1 to 200 and m can be 1 to 200.

[0060] For example, the first adhesive can be represented by the following structural formula 2-2.

[0061] [Structural Formula 2-2]

[0062]

[0063] In the above structural formula 2-2, the sum of p and r may be 2 to 1000, and the sum of q and s may be 2 to 1000. For example, p may be 1 to 999 and r may be 1 to 999. q may be 1 to 999 and s may be 1 to 999.

[0064] For example, the sum of p and r may be 2 to 500, and the sum of q and s may be 2 to 500. For example, p may be 1 to 499, and r may be 1 to 499. q may be 1 to 499, and s may be 1 to 499.

[0065] Or, for example, the sum of p and r may be 2 to 300, and the sum of q and s may be 2 to 300. For example, p may be 1 to 299, and r may be 1 to 299. q may be 1 to 299, and s may be 1 to 299.

[0066] Or, for example, the sum of p and r may be 2 to 200, and the sum of q and s may be 2 to 200. For example, p may be 1 to 199, and r may be 1 to 199. q may be 1 to 199, and s may be 1 to 199.

[0067] As another example, the first adhesive above can be represented by the following structural formula 2-3.

[0068] [Structural Formula 2-3]

[0069]

[0070] In the above structural formula 2-3, the sum of u, w, and y may be 3 to 1000, and the sum of v, x, and z may be 3 to 1000. For example, e may be u to 998, w may be 1 to 998, and y may be 1 to 998. For example, v may be 1 to 998, x may be 1 to 998, and z may be 1 to 998.

[0071] For example, the sum of the above u, the above w, and the above y may be 3 to 500, and the sum of the above v, the above x, and the above z may be 3 to 500. For example, the above e may be u to 498, the above w may be 1 to 498, and the above y may be 1 to 498. For example, the above v may be 1 to 498, the above x may be 1 to 498, and the above z may be 1 to 498.

[0072] Alternatively, for example, the sum of the above u, the above w, and the above y may be 3 to 300, and the sum of the above v, the above x, and the above z may be 3 to 300. For example, the above e may be u to 298, the above w may be 1 to 298, and the above y may be 1 to 298. For example, the above v may be 1 to 298, the above x may be 1 to 298, and the above z may be 1 to 298.

[0073] Alternatively, for example, the sum of the above u, the above w, and the above y may be 3 to 200, and the sum of the above v, the above x, and the above z may be 3 to 200. For example, the above e may be u to 198, the above w may be 1 to 198, and the above y may be 1 to 198. For example, the above v may be 1 to 198, the above x may be 1 to 198, and the above z may be 1 to 198.

[0074] However, the structure of the cyclic polymer is not limited to the examples described above and may further include various structures in which the first structural unit and the second structural unit are randomly arranged.

[0075] The weight-average molecular weight (Mw) of the first adhesive may be 1,000 to 300,000. For example, the weight-average molecular weight (Mw) of the first adhesive may be 1,000 or more, 3,000 or more, 5,000 or more, or 10,000 or more. For example, the weight-average molecular weight (Mw) of the first adhesive may be 300,000 or less, 100,000 or less, 80,000 or less, or 50,000 or less.

[0076] For example, the number average molecular weight (Mn) of the first adhesive may be 1,000 to 300,000. For example, the number average molecular weight (Mn) of the first adhesive may be 1,000 or more, 3,000 or more, 5,000 or more, or 10,000 or more. For example, the number average molecular weight (Mn) of the first adhesive may be 300,000 or less, 100,000 or less, 80,000 or less, or 50,000 or less.

[0077]

[0078] Second adhesive

[0079] The second adhesive may include a first linear polymer and a second linear polymer, and as an example, the second adhesive may include a network structure of the first linear polymer and the second linear polymer.

[0080] For example, the weight ratio of the first linear polymer and the second linear polymer may be 2:1 to 1:2. For example, the weight ratio of the first linear polymer and the second linear polymer may be 1:1.

[0081] For example, the first linear polymer may include a first main chain and a first side chain.

[0082] The first main chain may include a carbon skeleton. The carbon skeleton may refer to a skeletal structure composed of carbon (C) atoms. For example, the carbon skeleton may include 1 to 50, 1 to 40, 1 to 30, 1 to 20, or 1 to 10 carbon (C) atoms. For example, the carbon skeleton may mainly include carbon (C) atoms and may additionally include other types of atoms. For example, other types of atoms may include hydrogen (H), oxygen (O), etc., but are not limited to the examples described. For example, the first main chain may include a carbon skeleton composed of carbon (C), oxygen (O), and hydrogen (H) atoms.

[0083] The carbon skeleton can be a straight chain or a branched chain.

[0084] A straight chain or branched chain may not contain a ring. A straight chain may have carbon (C) atoms or the aforementioned atoms bonded to each other to form a continuous chain. A branched chain may include a continuous chain and a side chain bonded to the continuous chain. A straight chain or branched chain may be an aliphatic hydrocarbon. For example, a straight chain or branched chain may include at least one of a saturated hydrocarbon or an unsaturated hydrocarbon. That is, a straight chain or branched chain may include at least one of a single bond, a double bond, and a triple bond.

[0085] For example, the first main chain may comprise a form in which at least one hydrogen on the carbon skeleton is substituted. For example, the first main chain may comprise a form in which at least one hydrogen on the carbon skeleton is substituted with one or more substituents selected from the group consisting of deuterium atoms, halogen atoms, cyano groups, nitro groups, amino groups, silyl groups, oxy groups, thio groups, sulfinyl groups, sulfonyl groups, carbonyl groups, boron groups, phosphine oxide groups, phosphine sulfide groups, alkyl groups, alkenyl groups, alkynyl groups, hydrocarbon ring groups, aryl groups, and heterocyclic groups. Each of the exemplified substituents may be substituted or unsubstituted. For example, a biphenyl group may be interpreted as an aryl group or as a phenyl group substituted with a phenyl group.

[0086] For example, the first main chain may include a form in which two hydrogens on the carbon skeleton are substituted with a cyano group and an alkyl group.

[0087] The first side chain may include a plurality of first side chains. That is, the first linear polymer may include at least one first side chain.

[0088] The first side chain can be represented by the following structural formula 3A.

[0089] [Structural Formula 3A]

[0090]

[0091] In the above structural formula 3A, R1 and R2 may each independently be hydrogen, a cyano group, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group. For example, R1 and R2 may each be a substituted or unsubstituted C1 to C5 alkyl group.

[0092] The above L5 may be a single bond, a substituted or unsubstituted C1 to C5 alkylene group, a substituted or unsubstituted C2 to C5 alkenylene group, a substituted or unsubstituted C2 to C5 alkynylene group, or a substituted or unsubstituted C6 to C20 arylene group. For example, the above L5 may be a substituted or unsubstituted C1 to C5 alkylene group.

[0093] The first side chain may have the property of attracting electrons. For example, a nitrogen (N) atom in the first side chain may contribute to the first side chain having the said property. As an example, the first side chain may have a positive charge. The first linear polymer may be a cationic polymer.

[0094] For example, the weight-average molecular weight (Mw) of the first linear polymer may be 1,500 to 2,500. For example, the weight-average molecular weight (Mw) of the first linear polymer may be 2,000 to 2,500.

[0095] For example, the first linear polymer can be represented by the following structural formula 3.

[0096] [Structural Formula 3]

[0097]

[0098] In the above structural formula 3, n can be 1 to 100 and m can be 1 to 100. For example, n can be 1 to 50 and m can be 1 to 50. Or, for example, n can be 1 to 20 and m can be 1 to 20. Or, for example, n can be 1 to 10 and m can be 1 to 10.

[0099] In the above structural formula 3, L6 may include a carbon skeleton. The carbon skeleton may be a straight chain or a branched chain. For example, L6 may include a hydrocarbon skeleton composed of carbon (C) and hydrogen (H) atoms, and may include a form in which at least one hydrogen on the hydrocarbon skeleton is substituted with one or more substituents selected from the group consisting of deuterium atoms, halogen atoms, cyano groups, nitro groups, amino groups, silyl groups, oxy groups, thio groups, sulfinyl groups, sulfonyl groups, carbonyl groups, boron groups, phosphine oxide groups, phosphine sulfide groups, alkyl groups, alkenyl groups, alkynyl groups, hydrocarbon ring groups, aryl groups, and heterocyclic groups. For example, L6 may include a hydrocarbon skeleton composed of carbon (C) and hydrogen (H) atoms, and may include a form in which at least one hydrogen on the hydrocarbon skeleton is substituted with a cyano group and an alkyl group.

[0100]

[0101] For example, the second linear polymer may include a second main chain and a second side chain.

[0102] The description of the second main chain is identical to the first main chain described above, so the description is omitted here.

[0103] The second side chain may include a plurality of second side chains. That is, the second linear polymer may include at least one second side chain.

[0104] The second side chain can be represented by the following structural formula 4A.

[0105] [Structural Formula 4A]

[0106]

[0107] In the above structural formula 4A, R3 may be hydrogen, a cyano group, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group. For example, R3 may be a substituted or unsubstituted C1 to C5 alkyl group.

[0108] The second side chain can provide electrons. For example, sulfur (S) atoms and / or oxygen (O) atoms of the second side chain can contribute to the second side chain having the above properties. As an example, the second side chain can have a negative charge. The second linear polymer may be an anionic polymer.

[0109] The first side chain and the second side chain may be ionically bonded. The first linear polymer and the second linear polymer may be ionically bonded. Thus, the first linear polymer and the second linear polymer may form a network structure. For example, a network structure including ionic bonding can be confirmed via NMR.

[0110] For example, the weight-average molecular weight (Mw) of the second linear polymer may be 1,500 to 2,500. For example, the weight-average molecular weight (Mw) of the second linear polymer may be 2,000 to 2,500.

[0111] For example, the second linear polymer can be represented by the following structural formula 4.

[0112] [Structural Formula 4]

[0113]

[0114] In the above structural formula 4, n can be 1 to 100 and m can be 1 to 100. For example, n can be 1 to 50 and m can be 1 to 50. Or, for example, n can be 1 to 20 and m can be 1 to 20. Or, for example, n can be 1 to 10 and m can be 1 to 10.

[0115] In the above structural formula 4, L6 may include a carbon skeleton. The carbon skeleton may be a straight chain or a branched chain. For example, L6 may include a hydrocarbon skeleton composed of carbon (C) and hydrogen (H) atoms, and may include a form in which at least one hydrogen on the hydrocarbon skeleton is substituted with one or more substituents selected from the group consisting of deuterium atoms, halogen atoms, cyano groups, nitro groups, amino groups, silyl groups, oxy groups, thio groups, sulfinyl groups, sulfonyl groups, carbonyl groups, boron groups, phosphine oxide groups, phosphine sulfide groups, alkyl groups, alkenyl groups, alkynyl groups, hydrocarbon ring groups, aryl groups, and heterocyclic groups. For example, L6 may include a hydrocarbon skeleton composed of carbon (C) and hydrogen (H) atoms, and may include a form in which at least one hydrogen on the hydrocarbon skeleton is substituted with a cyano group and an alkyl group.

[0116] For example, the weight-average molecular weight (Mw) of the second adhesive may be 5,000 to 10,000. For example, the weight-average molecular weight (Mw) of the second adhesive may be 5,000 or more, 5,500 or more, 6,000 or more, or 7,000 or more. For example, the weight-average molecular weight (Mw) of the second adhesive may be 10,000 or less, 9,500 or less, or 9,000 or less.

[0117] For example, the number average molecular weight (Mn) of the second adhesive may be 5,000 to 10,000. For example, the number average molecular weight (Mn) of the second adhesive may be 5,000 or more, 5,500 or more, or 6,000 or more. The number average molecular weight (Mn) of the second adhesive may be 10,000 or less, 9,500 or less, 9,000 or less, 8,000 or less, or 7,000 or less.

[0118]

[0119] Since the first adhesive above has disulfide bonds, even if the disulfide bonds are broken during the operation of the all-solid-state secondary battery, they are easy to re-bond, so the adhesive strength of each layer within the battery is strongly maintained, and thus the lifespan characteristics of the battery can be greatly improved.

[0120] In addition, since the second adhesive has a network structure, it is easy to reconnect even if a part of the network structure breaks during the operation of the all-solid-state secondary battery, so the adhesive strength of each layer within the battery is strongly maintained, and thus the lifespan characteristics of the battery can be greatly improved.

[0121] Since the aforementioned adhesive has lithium ion conductivity, the adhesive composition and adhesive layer containing it can function as a lithium ion transport pathway within an all-solid-state secondary battery, thus having the advantage of excellent lithium ion conductivity of the battery.

[0122] In contrast, acrylic adhesives or fluorine-based adhesives (such as PVdF) that lack lithium ion conductivity are difficult to use as adhesives in all-solid-state batteries because their inclusion in the adhesive layer of the battery reduces the battery's lithium ion conductivity.

[0123] For example, with respect to 100 weight% of the adhesive composition, the adhesive may be included in an amount of 0.1 weight% to 10 weight%, and for example, 0.1 weight% to 9 weight%, 0.1 weight% to 5 weight%, 0.1 weight% to 2.5 weight%, 0.5 weight% to 2.5 weight%, 0.5 weight% to 1.5 weight%, 0.5 weight% to 1 weight%, or 1 weight% to 1.5 weight%.

[0124] If the above numerical range is satisfied, an adhesive layer with excellent lithium ion conductivity and excellent adhesion can be formed.

[0125]

[0126] Fluorescein-based dyes

[0127] Fluorescein-based dyes are fluorescent materials having a xanthene tricyclic ring structure. By including a fluorescein-based dye in the adhesive composition, the uniformity of the application during adhesive application can be easily verified, which has the advantage of enabling the production of an all-solid-state secondary battery containing a uniformly applied adhesive layer.

[0128] In addition, the above fluorescein-based dye is suitable for inclusion in the adhesive layer of an all-solid-state secondary battery because, even when used with the adhesive, it does not reduce the adhesion of the adhesive material and does not reduce the lithium ion conductivity.

[0129] For example, the fluorescein-based dye may include fluorescein or a derivative thereof, and the fluorescein-based dye may include fluorescein, rhodamine-based dyes, eosin-based dyes, erythrosine-based dyes, and combinations thereof.

[0130] For example, the rhodamine-based dye may include rhodamine B, rhodamine 6G, rhodamine 123, sulforhodamine B, rhodamine 110, or a combination thereof.

[0131] For example, the above eosin-based dye may include eosin B, eosin Y, ethyl eosin, phloxine B, rose Bengal, or a combination thereof.

[0132] For example, the above erythrosine-based dye may include erythrosine B, erythrosine Y, diethyl erythrosine, or a combination thereof.

[0133] For example, with respect to 100 weight% of the adhesive composition, the fluorescein-based dye may be included in an amount of 0.001 weight% to 1 weight%, for example, 0.001 weight% to 0.1 weight%, 0.005 weight% to 0.1 weight%, 0.001 weight% to 0.05 weight%, 0.005 weight% to 0.05 weight%, 0.01 weight% to 0.05 weight%, or 0.005 weight% to 0.01 weight%.

[0134] When the above numerical range is satisfied, the uniformity of the adhesive layer can be easily verified, and the lithium ion conductivity of the all-solid-state secondary battery is not reduced, so the battery characteristics can be excellent.

[0135] The above solvent is configured to facilitate the application of the adhesive composition and to allow the thickness of the adhesive layer to be easily controlled by adjusting the concentration of the composition, and 1,2-dichloroethane (DCE) can be used as the solvent.

[0136] With respect to 100 weight% of the adhesive composition, the solvent may be included in an amount of 50 weight% to 99 weight%, for example, 80 weight% to 99 weight%, 90 weight% to 99 weight%, 95 weight% to 99 weight%, or 98 weight% to 99 weight%.

[0137] For example, the adhesive composition may further include a lithium salt to improve the lithium ion conductivity of the adhesive layer.

[0138] The above lithium salts are LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 It may include one or more selected from SO2)(x and y are integers from 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0139] With respect to 100 weight% of the adhesive composition, the lithium salt may be included in an amount greater than 0 weight% and less than or equal to 10 weight%, for example, 0.01 weight% to 9 weight%, 0.1 weight% to 9 weight%, or 0.1 weight% to 7.5 weight%.

[0140] For example, a wet coating method may be used to apply the adhesive composition, and examples include spray coating, dip coating, screen coating, spin coating, roll coating, blade coating, or gravure coating, and a specific example may be spray coating.

[0141] For example, the conditions of the spray coating can be appropriately selected according to the concentration of the adhesive composition, and, for instance, can be carried out for 1 to 5 minutes at a pressure of 1 to 2 bar.

[0142]

[0143] Since the adhesive layer contains the aforementioned fluorescein-based dye, when UV is irradiated, the dye absorbs UV light and emits light (fluorescence), making it easy to check whether the adhesive layer is uniformly applied. For example, the uniformity of the application can be checked by irradiating UV immediately after forming the adhesive layer on the electrode-solid electrolyte layer laminate.

[0144] For example, the wavelength of the UV irradiated above can be appropriately selected depending on the type of fluorescein-based dye, and as a specific example, it may be 465 nm to 490 nm. When UV is irradiated in the above wavelength range, the fluorescein-based dye emits sufficient light and can function as a fluorescent material, so it can be easy to detect the coating of the adhesive layer.

[0145] For example, when an adhesive layer is formed by applying the above adhesive composition, if the adhesive layer is applied uniformly, it can emit light of a uniform intensity overall. In addition, if the adhesive layer is not applied uniformly, the fluorescence intensity may be relatively strong in areas where a relatively large amount of adhesive is applied, and relatively weak in areas where a relatively small amount of adhesive is applied.

[0146] For example, the fluorescence intensity emitted from the adhesive layer can be confirmed as a spectrum through a UV imaging device.

[0147] As another example, the presence of the adhesive layer can be confirmed by visually observing the fluorescence emitted from the adhesive layer.

[0148] Specifically, when the coating uniformity is excellent, the fluorescein-based dye is evenly distributed so that color differences in the adhesive layer are hardly visible to the naked eye, and there may be no stains or uneven areas.

[0149] In addition, when the coating uniformity is average, the fluorescein dye is mostly evenly distributed in the adhesive layer, but fine color differences may be observed visually in some areas and some stains may exist.

[0150] If the uniformity of application is insufficient, the fluorescein-based dye is not evenly distributed, so a distinct difference in color is observed, many stains or clumps are observed, and there may be areas where the adhesive is not applied.

[0151] For example, an adhesive composition is applied to the surface of the solid electrolyte layer of the electrode-solid electrolyte layer laminate to form an adhesive layer, and then UV light is irradiated onto the adhesive layer to visually check whether the adhesive layer has been applied and the uniformity of the application. Only when it is determined that the uniformity of the application is excellent can the solid electrolyte layer surface of the opposite electrode-solid electrolyte layer laminate be laminated so as to come into contact with the adhesive layer to manufacture an all-solid-state secondary battery.

[0152] The all-solid-state secondary battery manufactured after confirming coating uniformity in this way has excellent adhesion of each layer and very excellent lithium ion conductivity.

[0153]

[0154] Optionally, the first step may further include the step of forming an adhesive layer by applying the adhesive composition onto the electrode prior to lamination. Accordingly, an electrode-solid electrolyte layer laminate can be manufactured that further includes an adhesive layer between the electrode and the solid electrolyte layer. In this case, the description of the adhesive composition and the adhesive layer is the same as described above.

[0155] At this stage as well, to confirm whether the adhesive layer has been uniformly applied, a further step may be performed of irradiating UV light onto the formed adhesive layer and confirming whether the adhesive layer has been applied by the fluorescence emitted from the adhesive layer.

[0156] By the above-described additional step, an electrode-solid electrolyte layer laminate can be manufactured with superior adhesion without a decrease in lithium ion conductivity, while also having the advantage of easily verifying whether the adhesive layer has been applied.

[0157]

[0158] All-solid-state secondary battery

[0159] FIGS. 1 to 7 are schematic cross-sectional views of an all-solid-state secondary battery (100, 100') according to one embodiment.

[0160] Referring to FIGS. 1 to 7, an all-solid-state secondary battery (100, 100') according to one embodiment includes an electrode (200, 400), a solid electrolyte layer (300) located on the electrode (200, 400), and an adhesive layer (500) located between the electrode (200, 400) and the solid electrolyte layer (300) or between the solid electrolyte layers (300).

[0161] In other words, a solid-state secondary battery according to one embodiment comprises a positive electrode (200), a negative electrode (400), a solid electrolyte layer (300) located between the positive electrode (200) and the negative electrode (400), and an adhesive layer (500), wherein the adhesive layer (500) is positioned between the positive electrode (200) and the solid electrolyte layer (300), between the negative electrode (400) and the solid electrolyte layer (300), between the solid electrolyte layers (310, 320), or a combination thereof.

[0162] In one embodiment, referring to FIG. 1, when the adhesive layer (500) is located between the anode (200) and the solid electrolyte layer (300), the adhesive layer (500) may include a first adhesive layer (510). Referring to FIG. 2, the adhesive layer (500) may further include a second adhesive layer (520) located between the cathode (400) and the solid electrolyte layer (300).

[0163] The method for manufacturing the all-solid-state secondary battery (100) illustrated in FIGS. 1 and FIGS. 2 is as follows.

[0164] First, a cathode-solid electrolyte layer laminate (430) is manufactured by laminating a cathode (400) and a solid electrolyte layer (300) using a roll press method. Next, the adhesive composition described above is applied to the solid electrolyte layer surface of the laminate (430) to form a first adhesive layer (510). At this time, it can be confirmed whether the first adhesive layer is uniformly coated using the adhesive layer coating detection method described above. Next, an anode (200) is laminated on the first adhesive layer (510) to manufacture an all-solid-state secondary battery (100).

[0165] Optionally, when manufacturing the cathode-solid electrolyte layer laminate (430), a second adhesive layer (520) may be further formed by applying the adhesive described above onto the cathode (400). In this case, it may also be confirmed whether the second adhesive layer is uniformly coated using the adhesive layer coating detection method described above. Then, a solid electrolyte layer (300) may be laminated onto the second adhesive layer (520) to manufacture a cathode-solid electrolyte layer laminate (430) further comprising the second adhesive layer (520).

[0166] In another embodiment, referring to FIG. 3, when the adhesive layer (500) is located between the cathode (400) and the solid electrolyte layer (300), the adhesive layer (500) may include a second adhesive layer (520).

[0167] The method for manufacturing the all-solid-state secondary battery (100) disclosed in FIG. 3 is as follows.

[0168] First, an anode (200) and a solid electrolyte layer (300) are laminated using a roll press method to manufacture an anode-solid electrolyte layer laminate (230). Next, the adhesive composition described above is applied to the solid electrolyte layer surface of the laminate (230) to form a second adhesive layer (520). At this time, the coating detection method of the adhesive layer described above can be used to confirm whether the second adhesive layer is uniformly coated. Next, a negative electrode (400) is laminated on the second adhesive layer (520) to manufacture an all-solid-state secondary battery (100).

[0169] Optionally, when manufacturing the anode-solid electrolyte layer laminate (230), the adhesive described above may be applied as a coating on the anode (200) to further form a first adhesive layer (510). In this case, the coating detection method of the adhesive layer described above can be used to verify whether the first adhesive layer is uniformly coated. Then, a solid electrolyte layer (300) may be laminated onto the first adhesive layer (510) to further manufacture an anode-solid electrolyte layer laminate (230) including the first adhesive layer (520). In this case, an all-solid secondary battery (100) having a structure as illustrated in FIG. 2 may be manufactured.

[0170] In a solid-state secondary battery (100') according to another embodiment, with reference to FIG. 4, the solid electrolyte layer (300) includes a first solid electrolyte layer (310) located in contact with the negative electrode (400) and a second solid electrolyte layer (320) located in contact with the positive electrode (200), and the adhesive layer may include a third adhesive layer (530) located between the first solid electrolyte layer (310) and the second solid electrolyte layer (320).

[0171] Also, referring to FIGS. 5 to 7, the adhesive layer in the all-solid-state secondary battery (100') may further include a first adhesive layer (510) located between the positive electrode (200) and the second solid electrolyte layer (320), a second adhesive layer (520) located between the negative electrode (400) and the first solid electrolyte layer (310), or a combination thereof.

[0172] The method for manufacturing the all-solid-state secondary battery (100') disclosed in FIGS. 4 to 7 is as follows.

[0173] First, a cathode-first solid electrolyte layer laminate (430') manufactured by laminating a cathode (400) and a first solid electrolyte layer (310) using a roll press method, and an anode-second solid electrolyte layer laminate (230') manufactured by laminating an anode (200) and a second solid electrolyte layer (320) using a roll press method are prepared.

[0174] Next, the adhesive composition described above is applied to the surface of the first solid electrolyte layer (310) of the laminate (430') to form a third adhesive layer (530). At this time, the coating detection method of the adhesive layer described above can be used to confirm whether the third adhesive layer is uniformly coated. Next, the laminate (230') is stacked so that the surface of the second solid electrolyte layer (320) is positioned on the third adhesive layer (530) to manufacture an all-solid-state secondary battery (100').

[0175] Optionally, when manufacturing the laminate (230', 430'), a first adhesive layer (510) may be further formed by applying the adhesive described above onto the anode (200), and a second adhesive layer (520) may be further formed by applying the adhesive described above onto the cathode (400). Even in this case, it can be confirmed whether the first and second adhesive layers are uniformly coated using the adhesive layer coating detection method described above.

[0176] Next, a solid electrolyte layer (300) is laminated on the first adhesive layer (510) to further include an anode-second solid electrolyte layer laminate (230') and a cathode-first solid electrolyte layer laminate (430') is laminated on the second adhesive layer (520) to further include a second adhesive layer (520).

[0177] adhesive layer

[0178] As described above, the adhesive layer (500) can be understood to be divided into a first adhesive layer (510), a second adhesive layer (520), and a third adhesive layer (530) depending on the position in which they are placed. Since the first to third adhesive layers are layers formed from the adhesive composition described above, the type, content (weight%), and weight ratio of the compounds included in each adhesive layer may be the same.

[0179] A solid-state secondary battery (100, 100') according to one embodiment includes an adhesive layer disposed at the above location, thereby having the advantage of excellent interfacial adhesion between components and excellent lithium ion conductivity.

[0180] The adhesive layer comprises an adhesive and a fluorescein-based dye. Since the description of the adhesive and the fluorescein-based dye is the same as described above, a detailed description is omitted here.

[0181] For example, with respect to a total amount of 100% by weight of the adhesive and the fluorescein-based dye, the adhesive may be included in an amount of 90% to 99.9% by weight, for instance, 92.5% to 99.9% by weight, 95% to 99.9% by weight, 98% to 99.9% by weight, or 90% to 99% by weight. When the above numerical range is satisfied, an adhesive layer with excellent lithium ion conductivity and excellent adhesive strength can be formed.

[0182] For example, with respect to a total amount of 100% by weight of the adhesive and the fluorescein-based dye, the fluorescein-based dye may be included in an amount of 0.01% to 10% by weight, for instance, 0.01% to 5% by weight, 0.01% to 2.5% by weight, 0.5% to 2.5% by weight, 0.9% to 2.5% by weight, or 0.9% to 1% by weight. When the above numerical range is satisfied, the coating uniformity of the adhesive layer can be easily verified, and the lithium ion conductivity of the all-solid-state secondary battery is not reduced, so the characteristics of the battery can be excellent.

[0183] For example, the adhesive and the fluorescein-based dye are included in a weight ratio of 90:10 to 99.9:0.1, and may be included in a weight ratio of, for example, 92.5:7.5 to 99.9:0.1, 95:5 to 99.9:0.1, or 98:2 to 99.9:0.1. When the above numerical range is satisfied, the coating uniformity of the adhesive layer can be easily verified, and the lithium ion conductivity of the all-solid-state secondary battery is not reduced, so the characteristics of the battery can be excellent.

[0184] For example, the thickness of the adhesive layer (510, 520, 530) can be appropriately selected depending on the position of the adhesive layer, and for example, it can be 1 μm to 50 μm.

[0185] For example, the resistance (Ω) measured at room temperature according to the impedance method of the adhesive layer may be 300 Ω to 640 Ω, and for example, 300 Ω to 600 Ω, 300 Ω to 500 Ω, 300 Ω to 480 Ω, or 400 Ω to 480 Ω. When the above numerical range is satisfied, the lithium ion conductivity of the adhesive layer is excellent, and an all-solid-state secondary battery with excellent battery characteristics can be realized.

[0186]

[0187] The following describes the composition of an all-solid-state secondary battery other than the adhesive layer.

[0188] anode

[0189] A positive electrode for an all-solid-state secondary battery comprises a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector, wherein the positive electrode active material layer may comprise at least one of a positive electrode active material, a solid electrolyte, a binder, and a conductive material. However, the positive electrode for an all-solid-state secondary battery may comprise more or fewer components than those described above, provided that it is not limited thereto.

[0190] For example, the positive electrode for the all-solid-state secondary battery is manufactured by applying a positive electrode composition comprising at least one of a positive electrode active material, a sulfide-based solid electrolyte, a binder, and a conductive material to a current collector, and then drying and rolling.

[0191] positive electrode active material

[0192] The above-mentioned positive active material may be applied without limitation as long as it is commonly used in all-solid-state secondary batteries. For example, the above-mentioned positive active material may be a compound capable of reversible intercalation and deintercalation of lithium, and may include a compound represented by any one of the following chemical formulas.

[0193] Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).

[0194] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 is Mn, Al, or a combination thereof.

[0195] The above-mentioned positive electrode active material may be, for example, lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt oxide (NC), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium nickel manganese oxide (NM), lithium manganese oxide (LMO), or lithium iron phosphate oxide (LFP).

[0196] The above positive active material may include a lithium nickel-based oxide represented by the following chemical formula 1, a lithium cobalt-based oxide represented by the following chemical formula 2, a lithium iron phosphate-based compound represented by the following chemical formula 3, or a combination thereof.

[0197] [Chemical Formula 1]

[0198] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2

[0199] In the above Chemical Formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, and M 1 and M 2 is each independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr. 1 and M 2 can be different elements.

[0200] [Chemical Formula 2]

[0201] Li a2 Co x2 M 3 1-x2 O2

[0202] In the above chemical formula 2, 0.9≤a2≤1.8, 0.6≤x2≤1, and M 3It is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0203] [Chemical Formula 3]

[0204] Li a3 Fe x3 M 4 (1-x3) PO4

[0205] In the above chemical formula 3, 0.9≤a3≤1.8, 0.6≤x3≤1, and M 4 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0206] Average particle size (D) of the above positive active material 50 The particle size can be 1 μm to 25 μm, for example, 3 μm to 25 μm, 5 μm to 25 μm, 5 μm to 20 μm, 8 μm to 20 μm, or 10 μm to 18 μm. A positive electrode active material having such a particle size range can be harmoniously mixed with other components within the positive electrode active material layer and can achieve high capacity and high energy density.

[0207] The above positive active material may be in the form of secondary particles formed by the aggregation of a plurality of primary particles, or in the form of a single particle. In addition, the above positive active material may be spherical or have a shape close to spherical, or may be polyhedral or amorphous.

[0208] solid electrolyte

[0209] The above solid electrolyte may be an inorganic solid electrolyte, such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte, or a solid polymer electrolyte.

[0210] Sulfide-based solid electrolytes include, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element, e.g., I or Cl), 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, and Li2S-P2S5-Z m S n (m and n are integers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are integers, and M is P, Si, Ge, B, Al, Ga or In), or may include a combination thereof.

[0211] Such sulfide-based solid electrolytes can be obtained, for example, by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10 or 50:50 to 80:20 and optionally heat-treating. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be manufactured. The ionic conductivity may be further improved by including SiS2, GeS2, B2S3, etc., as other components.

[0212] Mechanical milling or the solution method can be applied as mixing methods for sulfur-containing raw materials to manufacture sulfide-based solid electrolytes. Mechanical milling is a method in which starting materials are placed in a reactor and strongly stirred with a ball mill or similar device to finely pulverize and mix the starting materials. When using the solution method, starting materials are mixed in a solvent to obtain a solid electrolyte as a precipitate. Additionally, if heat treatment is performed after mixing, the crystals of the solid electrolyte can become more robust and the ionic conductivity can be improved. For example, a sulfide-based solid electrolyte can be manufactured by mixing sulfur-containing raw materials and heat-treating them two or more times; in this case, a robust sulfide-based solid electrolyte with high ionic conductivity can be produced.

[0213] For example, the sulfide-based solid electrolyte particles may include an argyrodite-type sulfide. The argyrodite-type sulfide is, for example, Li a M b P c S d A e It can be expressed by the chemical formula (where a, b, c, d, and e are all between 0 and 12, M is a metal excluding Li or a combination of multiple metals excluding Li, and A is F, Cl, Br, or I), and as a specific example, Li 7-x PS 6-x A x It can be expressed by the chemical formula (where x is 0.2 or greater and 1.8 or less, and A is F, Cl, Br, or I). Specifically, the azirodite-type sulfide is Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0214] Sulfide-based solid electrolyte particles containing such azirodite-type sulfides have an ionic conductivity of 10 at room temperature, which is the same as that of a typical liquid electrolyte. -4 to 10 -2 It has high ionic conductivity close to the S / cm range and can form a tight bond between the positive active material and the solid electrolyte without causing a decrease in ionic conductivity, and furthermore, can form a tight interface between the electrode layer and the solid electrolyte layer. An all-solid-state battery including this can improve battery performance such as rate characteristics, Coulomb efficiency, and lifespan characteristics.

[0215] An azirodite-type sulfide-based solid electrolyte can be prepared by mixing, for example, lithium sulfide and phosphorus sulfide, and optionally lithium halide. After mixing these, heat treatment may be performed. The heat treatment may include, for example, two or more heat treatment steps.

[0216] According to one embodiment, the average particle size (D50) of the sulfide-based solid electrolyte particles may be 5.0 μm or less, for example, 0.1 μm to 5.0 μm, 0.1 μm to 4.0 μm, 0.1 μm to 3.0 μm, 0.5 μm to 2.0 μm, or 0.1 μm to 1.5 μm. Alternatively, depending on the location or purpose of use, the sulfide-based solid electrolyte particles may be small particles having an average particle size (D50) of 0.1 μm to 1.0 μm, or large particles having an average particle size (D50) of 1.5 μm to 5.0 μm. Sulfide-based solid electrolyte particles within this particle size range can effectively penetrate between solid particles within the battery, and have excellent contact with the electrode active material and connectivity between solid electrolyte particles. The average particle size of the sulfide-based solid electrolyte particles may be measured using a microscopic image, for example, by measuring the size of about 20 particles in a scanning electron microscope image to obtain the particle size distribution and calculating D50 from it.

[0217] The above oxide-based inorganic solid electrolyte is, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Lithium Phosphate (Li3PO4), Lithium Titanium Phosphate (Li x Ti y (PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate(Li x La y TiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2계 세라믹스, 가넷(Garnet)계 세라믹스 Li 3+x La3M2O 12 (M= Te, Nb, or Zr; x is an integer from 1 to 10), or may include a combination thereof.

[0218] The above halide-based solid electrolyte may include a Li element, an M element (M is a metal other than Li), and an X element (X is a halogen). Examples of X include F, Cl, Br, and I. In particular, for the halide-based solid electrolyte, at least one of Br and Cl is suitable as X. Additionally, examples of M include metal elements such as Sc, Y, B, Al, Ga, and In.

[0219] The composition of the above halide-based solid electrolyte is not particularly limited, but Li 6-3a M a Br b Cl c (In the formula, M is a metal other than Li, and 0 <a<2, 0≤b≤6, 0≤c≤6, b+c=6)로 표현될 수 있다. 이때, 상기 a는 0.75 이상일 수 있고, 1 이상일 수 있고, a는, 1.5 이하일 수 있다. 상기 b는 1 이상일 수 있고, 2 이상일 수 있다. 또한, 상기 c는, 3 이상일 수 있고, 4 이상일 수도 있다. 상기 할라이드계 고체 전해질의 구체적인 예로는 Li3YBr6, Li3YCl6또는 Li3YBr2Cl4를 들 수 있다.

[0220] The above solid polymer electrolyte is, for example, polyethylene oxide, poly(diallyldimethylammonium)trifluoromethanesulfonylimide (poly(diallyldimethylammonium)TFSI), Cu3N, Li3N, LiPON, Li3PO 4· Li2S · SiS2, Li2S · GeS2.Ga2S3, Li2O · 11Al2O3, Na2O · 11Al2O3, (Na,Li) 1+x Ti 2-x Al x (PO4)3(0.1≤x≤0.9), Li 1+x Hf 2-x Al x (PO4)3(0.1≤x≤0.9), Na3Zr2Si2PO12 , Li3Zr2Si2PO 12 , Na5ZrP3O 12 , Na5TiP3O 12 , Na3Fe2P3O 12 , Na4NbP3O 12 , Na-silicate, Li 0.3 La 0.5 TiO3, Na5MSi4O 12 (M is a rare earth element such as Nd, Gd, or Dy) Li5ZrP3O 12 , Li5TiP3O 12 , Li3Fe2P3O 12 , Li4NbP3O 12 , Li 1+x (M,Al,Ga) x (Ge 1-y Ti y ) 2-x (PO4)3(x≤0.8, 0≤y≤1.0, M is Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), Li 1+x+y Q x Ti 2-x Si y P 3-y O 12 (0 <x≤0.4, 0<y≤0.6, Q는 Al 또는 Ga), Li6BaLa2Ta2O 12 , Li7La3Zr2O 12 , Li5La3Nb2O 12 , Li5La3M2O 12 (M is Nb, Ta) and Li 7+x A x La 3-x Zr2O 12 (0 <x<3, A는 Zn) 중에서 선택된 하나 이상을 포함할 수 있다.

[0221] The content of the solid electrolyte in the anode for the all-solid-state battery may be 0.5 wt% to 35 wt%, for example, 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%. This is the content relative to the total weight of the components in the anode, and specifically, it can be said to be the content relative to the total weight of the anode active material layer.

[0222] In one embodiment, the positive active material layer may comprise, with respect to 100 weight% of the positive active material layer, 50 weight% to 99.35 weight% of a positive active material, 0.5 weight% to 35 weight% of a sulfide-based solid electrolyte, 0.1 weight% to 10 weight% of a fluorine-based resin binder, and 0.05 weight% to 5 weight% of vanadium oxide. When such content ranges are satisfied, the positive electrode for an all-solid-state secondary battery can achieve high capacity and high ionic conductivity while maintaining high adhesion, and the viscosity of the positive electrode composition can be maintained at an appropriate level, thereby improving processability.

[0223] bookbinder

[0224] The binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Representative examples include polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc., but are not limited thereto.

[0225] Challenge

[0226] The above positive active material layer may further include a conductive material. The conductive material is used to impart conductivity to the electrode and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or a combination thereof.

[0227] The conductive material may be included in an amount of 0.1% to 5% by weight, or 0.1% to 3% by weight, relative to the total weight of each component of the anode for the all-solid-state battery, or relative to the total weight of the anode active material layer. Within the above content range, the conductive material can improve electrical conductivity without degrading battery performance.

[0228] When the above positive active material layer further includes a conductive material, the positive active material layer may comprise, with respect to 100 weight% of the positive active material layer, 45 weight% to 99.25 weight% of a positive active material, 0.5 weight% to 35 weight% of a sulfide-based solid electrolyte, 0.1 weight% to 10 weight% of a fluorine-based resin binder, 0.05 weight% to 5 weight% of vanadium oxide, and 0.1 weight% to 5 weight% of a conductive material.

[0229] The positive current collector may include, for example, aluminum, stainless steel, nickel, or a combination thereof, and may be in the form of a foil, foam, or porous metal plate. The positive current collector may be, for example, a polymer-metal composite film comprising a polymer film and a metal layer located on one or both sides of the polymer film. The positive current collector may, for example, include a substrate containing metal and a primer layer located on the surface of the substrate and containing a carbon material.

[0230] cathode

[0231] A negative electrode for an all-solid-state battery may, for example, include a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector. The negative electrode active material layer may include a negative electrode active material and may further include a binder, a conductive material, and / or a solid electrolyte.

[0232] The above negative electrode active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0233] A material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0234] As the above lithium metal alloy, an alloy of lithium with one or more metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn may be used.

[0235] As a material capable of doping and undoping the above lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used, and the Si-based negative electrode active material may include silicon, a silicon-carbon composite, or SiO₂. x(0<x≤2), Si-Q 합금(상기 Q는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Si은 아님), 상기 Sn계 음극 활물질로는 Sn, SnO2, Sn-R 합금(상기 R은 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 상기 원소 Q 및 R로는 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, 및 이들의 조합으로 이루어진 군에서 선택되는 것을 사용할 수 있다.

[0236] The silicon-carbon composite may be, for example, a silicon-carbon composite comprising a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof. The amorphous carbon may be pitch carbon, soft carbon, hard carbon, mesophase pitch carbide, calcined coke, carbon fiber, or a combination thereof. In this case, the silicon content may be 10% to 50% by weight of the total weight of the silicon-carbon composite. Additionally, the content of the crystalline carbon may be 10% to 70% by weight of the total weight of the silicon-carbon composite, and the content of the amorphous carbon may be 20% to 40% by weight of the total weight of the silicon-carbon composite. Additionally, the thickness of the amorphous carbon coating layer may be 5nm to 100nm.

[0237] The average particle size (D50) of the silicon particles may be 10 nm to 20 µm, for example, 10 nm to 500 nm. The silicon particles may exist in an oxidized form, wherein the atomic content ratio of Si:O within the silicon particles indicating the degree of oxidation may be 99:1 to 33:67. The silicon particles are SiO x It can be a particle, and in this case, SiO x In this case, the range of x may be greater than 0 and less than 2. Here, the average particle size (D50) is measured by a particle size analyzer using laser diffraction and refers to the diameter of a particle with a cumulative volume of 50% in the particle size distribution.

[0238] The above Si-based negative electrode active material or Sn-based negative electrode active material may be used in combination with a carbon-based negative electrode active material. The mixing ratio of the Si-based negative electrode active material or Sn-based negative electrode active material and the carbon-based negative electrode active material may be 1:99 to 90:10 by weight.

[0239] The content of the negative electrode active material in the above negative electrode active material layer may be 95% to 99% by weight with respect to the total weight of the negative electrode active material layer.

[0240] In one embodiment, the negative active material layer further comprises a binder and optionally further comprises a conductive material. The content of the binder in the negative active material layer may be 1% to 5% by weight with respect to the total weight of the negative active material layer. Additionally, when further comprising a conductive material, the negative active material layer may comprise 90% to 98% by weight of the negative active material, 1% to 5% by weight of the binder, and 1% to 5% by weight of the conductive material.

[0241] The above binder serves to effectively bond the negative electrode active material particles to each other and also to effectively bond the negative electrode active material to the current collector. The above binder may include a water-insoluble binder, a water-soluble binder, or a combination thereof.

[0242] The above-mentioned water-insoluble binder may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer comprising ethylene oxide, an ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0243] Examples of the above water-soluble binders include rubber-based binders or polymer resin binders. The rubber-based binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, and combinations thereof. The polymer resin binder may be selected from polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0244] When a water-soluble binder is used as the above-mentioned cathode binder, a thickener capable of imparting viscosity may be used together, and the thickener may include, for example, a cellulose-based compound. The cellulose-based compound may include carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, alkali metal salts thereof, or combinations thereof. Na, K, or Li may be used as the alkali metal. The content of such a thickener may be 0.1 to 3 parts by weight per 100 parts by weight of the cathode active material.

[0245] The above conductive material is used to impart conductivity to an electrode and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes; metal-based materials in the form of metal powder or metal fibers including copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0246] As the above-mentioned cathode current collector, a material selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof may be used.

[0247] As another example, the negative electrode for the all-solid-state battery may be a precipitation type negative electrode. The precipitation type negative electrode refers to a negative electrode that does not contain a negative electrode active material when assembling the battery, but where lithium metal, etc., is precipitated during charging of the battery and acts as the negative electrode active material.

[0248] In an all-solid-state battery having such a precipitation-type negative electrode, initial charging begins in the absence of a negative electrode active material, and during charging, a high-density lithium metal, etc. is precipitated between the current collector and the negative electrode coating layer to form a lithium metal layer, which can serve as the negative electrode active material. Accordingly, in an all-solid-state battery that has undergone one or more charging cycles, the precipitation-type negative electrode may include a current collector, a lithium metal layer located on the current collector, and a negative electrode coating layer located on the metal layer. The lithium metal layer refers to a layer in which lithium metal, etc. is precipitated during the charging process of the battery, and may be referred to as a metal layer or a negative electrode active material layer.

[0249] The above cathode coating layer may include a metal, a carbon material, or a combination thereof that acts as a catalyst.

[0250] The above metal may include, for example, Ag, Al, Au, Bi, Cu, Ge, In, Mg, Ni, Pt, Pd, Si, Sn, Zn, or a combination thereof, and may be composed of one of these or may be composed of several types of alloys. When the above metal exists in the form of particles, the average particle size (D50) may be about 4 μm or less, and for example, 10 nm to 4 μm.

[0251] The carbon material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof. The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon microbeads, or a combination thereof. The amorphous carbon may be, for example, pitch carbon, soft carbon, hard carbon, mesophase pitch carbide, calcined coke, carbon fiber, or a combination thereof.

[0252] When the above-described cathode coating layer includes both the metal and the carbon material, the mixing ratio of the metal and the carbon material may be, for example, a weight ratio of 1:10 to 2:1. In this case, the precipitation of lithium metal can be effectively promoted and the characteristics of the all-solid-state battery can be improved. The above-described cathode coating layer may include, for example, a carbon material supported with a catalyst metal, or may include a mixture of metal particles and carbon material particles.

[0253] The above cathode coating layer may, for example, include the metal and amorphous carbon, and in this case, can effectively promote the precipitation of lithium metal.

[0254] The above cathode coating layer may further include a binder. The binder may be a non-aqueous binder, and as an example, may be an ion-conducting binder.

[0255] The above-mentioned non-aqueous binder may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene oxide, ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, polyacrylate, or a combination thereof.

[0256] The binder may be 1% to 15% by weight with respect to 100% by weight of the entire cathode coating layer. For example, the binder may be 1% to 14% by weight, 1% to 12% by weight, 1% to 10% by weight, 2% to 8%, or 2% to 7% by weight with respect to 100% by weight of the entire cathode coating layer.

[0257] When the above binder is included in the negative electrode coating layer of an all-solid-state battery within the above content range, electrical resistance and adhesion are improved, and the characteristics of the all-solid-state battery (battery capacity and output characteristics) can be improved.

[0258] In addition, the above cathode coating layer (405) may further include common additives such as fillers, dispersants, and ion conductive materials.

[0259] The thickness of the above cathode coating layer may be, for example, 100 nm to 20 µm, or 500 nm to 10 µm, or 1 µm to 5 µm.

[0260] The above-mentioned solid electrolyte may be an inorganic solid electrolyte, such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte, or a solid polymer electrolyte. The specific details of the above-mentioned solid electrolyte are as described above.

[0261] The above-described precipitation type cathode may, for example, further include a thin film on the surface of the current collector, that is, between the current collector and the cathode coating layer. The thin film may include an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and may be composed of one of these or composed of several types of alloys. The thin film can further flatten the precipitation pattern of the lithium metal layer and further improve the characteristics of the all-solid-state battery. The thin film may be formed by, for example, vacuum deposition, sputtering, plating, etc. The thickness of the thin film may be, for example, 1 nm to 500 nm.

[0262] solid electrolyte layer

[0263] The solid electrolyte layer may be an inorganic solid electrolyte, such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte, or may include a solid polymer electrolyte. The specific details of the solid electrolyte are as described above.

[0264] In one example, the solid electrolyte included in the anode or cathode and the solid electrolyte included in the solid electrolyte layer may contain the same compound or different compounds. For example, if both the anode and the solid electrolyte layer contain an azirodite-type sulfide-based solid electrolyte, the overall performance of the all-solid-state secondary battery may be improved. Additionally, for example, if both the anode and the solid electrolyte layer contain the aforementioned coated solid electrolyte, the all-solid-state secondary battery can achieve high capacity and high energy density while realizing excellent initial efficiency and lifespan characteristics.

[0265] Meanwhile, the average particle size (D) of the solid electrolyte contained in the anode 50 ) is the average particle size (D) of the solid electrolyte contained in the solid electrolyte layer. 50It may be smaller than ). In this case, overall performance can be improved by increasing lithium ion mobility while maximizing the energy density of the all-solid-state battery. For example, the average particle size (D) of the solid electrolyte contained in the cathode. 50 ) may be 0.1 μm to 1.0 μm, or 0.1 μm to 0.8 μm, and the average particle size (D) of the solid electrolyte included in the solid electrolyte layer 50 The particle size ) can be 1.5 μm to 5.0 μm, or 2.0 μm to 4.0 μm, or 2.5 μm to 3.5 μm. When such a particle size range is satisfied, the energy density of the all-solid-state secondary battery is maximized, while lithium ion transport is facilitated to suppress resistance, thereby improving the overall performance of the all-solid-state secondary battery. Here, the average particle size (D) of the solid electrolyte 50 ) may be measured using a particle size analyzer utilizing laser diffraction. Alternatively, approximately 20 random particles may be selected from microscopic images such as those of a scanning electron microscope, their particle sizes measured, and their particle size distribution obtained, where D 50 You can also calculate the value.

[0266] The above solid electrolyte layer may further include a binder in addition to the solid electrolyte. In this case, styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, acrylate-based polymers, or combinations thereof may be used as the binder, but are not limited thereto, and any material used as a binder in the relevant technical field may be used. The above acrylate-based polymer may be, for example, butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0267] The above solid electrolyte layer can be formed by adding a solid electrolyte to a binder solution, coating it onto a substrate film, and drying it. The solvent of the binder solution may be isobutyryl isobutylate, xylene, toluene, benzene, hexane, or a combination thereof. Since the process for forming the above solid electrolyte layer is widely known in the field, a detailed description will be omitted.

[0268] The thickness of the solid electrolyte layer may be, for example, 10 μm to 150 μm.

[0269] The above solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0270] The above alkali metal salt may be, for example, a lithium salt. The content of the lithium salt in the above solid electrolyte layer may be 1 M or more, for example, 1 M to 4 M. In this case, the lithium salt can improve ion conductivity by improving the lithium ion mobility of the solid electrolyte layer.

[0271] The above lithium salts are, for example, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI), It may include LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4, or a mixture thereof.

[0272] In addition, the lithium salt may be imide-based, for example, the imide-based lithium salt may include lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2) and lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). The lithium salt can maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with the ionic liquid.

[0273] The above ionic liquid refers to a salt or room temperature molten salt that has a melting point below room temperature, is in a liquid state at room temperature, and consists only of ions.

[0274] The above ionic liquid comprises a) one or more cations selected from ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phosphonium-based, sulfonium-based, triazolium-based, and mixtures thereof, and b) BF4 - , PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - It may be a compound containing one or more anions selected from among.

[0275] The above ionic liquid may be one or more selected from the group consisting of, for example, N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazoliium bis(trifluoromethylsulfonyl)amide, and 1-ethyl-3-methylimidazoliium bis(trifluoromethylsulfonyl)amide.

[0276] The weight ratio of the solid electrolyte to the ionic liquid in the above solid electrolyte layer may be 0.1:99.9 to 90:10, and for example, 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. A solid electrolyte layer satisfying the above range can maintain or improve ionic conductivity by increasing the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate characteristics, etc. of the all-solid-state battery can be improved.

[0277] The above all-solid-state battery may be a unit cell having a structure of a positive electrode / solid electrolyte layer / negative electrode, a bicell having a structure of a negative electrode / solid electrolyte layer / positive electrode / solid electrolyte layer / negative electrode, or a stacked battery in which the structure of the unit cell is repeated.

[0278] The shape of the above-described solid-state battery is not particularly limited and may be, for example, coin-type, button-type, sheet-type, stacked-type, cylindrical-type, flat-type, etc. In addition, the above-described solid-state battery can be applied to large batteries used in electric vehicles, etc. For example, the above-described solid-state battery can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in fields requiring a large amount of power storage, and for example, it can be used in electric bicycles or power tools.

[0279] Examples and comparative examples of the present invention are described below. However, the following examples are merely one example of the present invention, and the present invention is not limited to the following examples.

[0280] (Example)

[0281] Example 1

[0282] (1) Preparation of an adhesive layer composition

[0283] First, a cyclic polymer adhesive comprising a first structural unit represented by the following structural formula 1A-1 and a second structural unit represented by the following structural formula 1B-1 was prepared.

[0284] [Structural Formula 1A-1]

[0285]

[0286] [Structural Formula 1B-1]

[0287]

[0288] The cyclic polymer was prepared by the following method.

[0289] A first mixture was formed by mixing a first reactant represented by the structural formula 1A-1' below, a second reactant represented by the structural formula 1B-1' below, and triethylamine (TEA) in a molar ratio of 1:1:4. Under air bubbling conditions, 30 wt% hydrogen peroxide was added dropwise to the first mixture over 45 minutes, followed by stirring for 2 hours to form a second mixture. The supernatant of the second mixture was removed to obtain a precipitate. The precipitate was washed with distilled water and acetone and dried to produce a cyclic polymer.

[0290] [Structural Formula 1A-1']

[0291]

[0292] [Structural Formula 1B-1']

[0293]

[0294] An adhesive composition was prepared by mixing 1 wt% of the above-prepared cyclic polymer adhesive, 0.01 wt% of Rhodamine B dye, and 98.99 wt% of 1,2-dichloroethane (DCE) solvent.

[0295] (2) Preparation of a solid electrolyte layer

[0296] 98.5 wt% of an azirodite-type solid electrolyte of Li6PS5Cl and 1.5 wt% of a binder were added to an IBIB solvent and mixed to prepare a composition for forming a solid electrolyte layer. The composition for forming a solid electrolyte layer was applied onto a release PET film using a bar coater and dried at room temperature to prepare a solid electrolyte layer.

[0297] (3) Preparation of the cathode

[0298] Primary particle size (D 50 Carbon black with a diameter of approximately 30 nm and an average particle size (D 50 An Ag / C composite was prepared by mixing silver (Ag) with a thickness of approximately 60 nm in a weight ratio of 3:1, and 0.25 g of the composite was added to 2 g of an NMP solution containing 7 wt% of a polyvinylidene fluoride binder and mixed to prepare a cathode coating layer composition. This was applied to a nickel foil current collector using a bar coater and vacuum dried to prepare a precipitation type cathode with a cathode coating layer formed on the current collector.

[0299] (4) Check whether the adhesive layer has been applied

[0300] A cathode-solid electrolyte layer laminate (thickness: 110 μm) was manufactured by laminating the cathode and the solid electrolyte layer and applying pressure (120°C, 2.0 ton / cm) using a roll press method. An adhesive layer was formed by applying the adhesive composition to the surface of the solid electrolyte layer of the cathode-solid electrolyte layer laminate using a spray method.

[0301] UV light was irradiated onto the adhesive layer formed at this time, and the application status and uniformity of the adhesive layer were confirmed by the fluorescence emitted from the adhesive layer.

[0302] (5) Manufacturing of a symmetric cell

[0303] After confirming that the adhesive layer was applied excellently, the solid electrolyte layer surface of the same cathode-solid electrolyte layer laminate was laminated onto the adhesive layer so as to be in contact, and then a symmetric cell including the adhesive layer was manufactured by applying pressure using a roll press method. The pressure was applied at 120°C.

[0304]

[0305] Comparative Example 1

[0306] A symmetric cell according to Comparative Example 1 was prepared in the same manner as in Example 1, except that an adhesive composition was prepared by mixing 0.01 wt% of Rhodamine B dye and 99.99 wt% of 1,2-Dichloroethane (DCE) solvent.

[0307]

[0308] Comparative Example 2

[0309] A symmetric cell according to Comparative Example 2 was prepared in the same manner as Example 1, except that the adhesive composition was not applied to the symmetric cell prepared in Example 1 (meaning it does not contain an adhesive layer).

[0310]

[0311] Evaluation example

[0312] Evaluation Example 1: Evaluation of Adhesive Layer Application Uniformity

[0313] (1) Checking the uniformity of the adhesive layer coating

[0314] The application of the adhesive layer of Example 1 and the uniformity of the application were visually checked, and the degree of uniformity of the application was evaluated by dividing it into ○ (excellent), △ (average), and X (poor).

[0315] Figure 8 is an image showing a case with excellent coating uniformity, Figure 9 is an image showing a case with average coating uniformity, and Figure 10 is an image showing a case with poor coating uniformity.

[0316] Referring to Figure 8, it can be seen that Rhodamine B, a red dye, is evenly distributed so that color differences are hardly visible to the naked eye, and there are no stains or uneven areas.

[0317] Referring to Fig. 9, although the dye is mostly uniformly distributed in the adhesive layer, fine color differences are visible to the naked eye in some areas, and it can be seen that some stains exist.

[0318] Referring to Fig. 10, it can be seen that the dye is not evenly distributed, so a distinct color difference is observed, many stains or clumps are observed, and there are areas where the adhesive is not applied.

[0319] (2) Evaluation of lithium ion conductivity of the adhesive layer according to the degree of uniformity of the adhesive layer coating

[0320] After evaluating the degree of uniformity of the coating of the above adhesive layer as ○ (excellent), △ (average), and X (poor), a symmetric cell for each coating was prepared in the same manner as in Example 1 above, and the resistance according to the impedance method was evaluated for each symmetric cell, and the results are shown in Table 1 and Figure 11 below.

[0321] Referring to Table 1 and Figure 11, it can be seen that when the coating uniformity of the adhesive layer is excellent, the resistance of the adhesive layer is very low and the lithium ion conductivity is excellent compared to cases of average and poor uniformity. Accordingly, it can be seen that when a battery is manufactured by adopting the case of excellent coating uniformity after evaluating the coating uniformity of the adhesive layer, excellent adhesion and excellent lithium ion conductivity can be secured.

[0322] Resistance (Ω) ○ 408.34 △ 645.443 X 1368.73

[0323] Evaluation Example 2: Evaluation of Lithium Ion Conductivity

[0324] The resistance according to the impedance method was measured for the symmetric cells prepared in Example 1, Comparative Example 1, and Comparative Example 2, and is shown in Table 2 and Figure 12.

[0325] Resistance (Ω) Comparative Example 2792.913 Comparative Example 1767.191 Example 1465.197

[0326] Referring to Table 2 and Figure 12, since the resistance of Comparative Example 1 sample, which includes an adhesive layer containing only Rhodamine B dye, is equivalent to that of Comparative Example 2, which does not include an adhesive layer, it can be confirmed that Rhodamine B included in the adhesive layer does not significantly affect the lithium ion conductivity of the solid electrolyte layer.

[0327] In addition, in the case of Example 1, the battery has an adhesive layer containing both an adhesive having disulfide bonds and a Rhodamine B dye, and since the battery can be manufactured while checking the degree of coating of the adhesive layer, it can be confirmed that the lithium ion conductivity is excellent with a lower resistance value compared to Comparative Example 1 and Comparative Example 2.

[0328]

[0329] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

[0330]

[0331] [Explanation of Symbols]

[0332] 100, 100': All-solid-state secondary battery 200: Cathode

[0333] 400: Cathode 300: Solid electrolyte layer

[0334] 310: First solid electrolyte layer 320: Second solid electrolyte layer

[0335] 430: Cathode-solid electrolyte layer laminate

[0336] 430': Cathode-first solid electrolyte layer laminate

[0337] 230: Anode-solid electrolyte layer laminate

[0338] 230': Anode-second solid electrolyte layer laminate

[0339] 500: Adhesive layer 510: First adhesive layer

[0340] 520: Second adhesive layer 530: Third adhesive layer

Claims

1. Anode; cathode; a solid electrolyte layer located between the anode and the cathode; and It includes an adhesive layer disposed at a position between the anode and the solid electrolyte layer, between the cathode and the solid electrolyte layer, between the solid electrolyte layers, or a combination thereof, and The above adhesive layer comprises an adhesive and a fluorescein-based dye, for an all-solid-state secondary battery.

2. In Paragraph 1, The all-solid-state secondary battery, wherein the adhesive layer comprises a first adhesive layer located between the anode and the solid electrolyte layer.

3. In Paragraph 2, The all-solid-state secondary battery, wherein the adhesive layer further comprises a second adhesive layer located between the cathode and the solid electrolyte layer.

4. In Paragraph 1, The all-solid-state secondary battery, wherein the adhesive layer comprises a second adhesive layer located between the cathode and the solid electrolyte layer.

5. In Paragraph 1, The above solid electrolyte layer includes a first solid electrolyte layer located in contact with the cathode and a second solid electrolyte layer located in contact with the anode, and The all-solid-state secondary battery, wherein the adhesive layer comprises a third adhesive layer located between the first solid electrolyte layer and the second solid electrolyte layer.

6. In Paragraph 5, The all-solid-state secondary battery further comprises an adhesive layer located between the anode and the second solid electrolyte layer, a first adhesive layer located between the cathode and the first solid electrolyte layer, or a combination thereof.

7. In Paragraph 1, The above adhesive includes a first adhesive, and The first adhesive above includes a cyclic polymer, and The above-mentioned cyclic polymer comprises a first structural unit represented by the following structural formula 1A and a second structural unit represented by the following structural formula 1B, and All-solid-state secondary battery in which the first structural unit and the second structural unit are bonded to each other by disulfide bonds: [Structural Formula 1A] In the above structural formula 1A, L1, L2, and L3 are each independently a single bond, a C1 to C10 alkylene group, a C2 to C10 alkenylene group, or a C2 to C10 alkynylene group, and The above Y1 and the above Y2 are each independently oxygen or sulfur, and [Structural Formula 1B] In the above structural formula 1B, L4 is a single bond, a C1 to C20 alkylene group, a C2 to C20 alkenylene group, or a C2 to C20 alkylene group.

8. In Paragraph 1, The above adhesive includes a second adhesive, and The second adhesive above comprises a network structure of a first linear polymer and a second linear polymer, and The first linear polymer comprises a first main chain and at least one first side chain represented by the following structural formula 3A, and The second linear polymer comprises a second main chain and at least one second side chain represented by the following structural formula 4A, and The above first side chain and the above second side chain are ionically bonded, all-solid-state secondary battery: [Structural Formula 3A] In the above structural formula 3A, R1 and R2 are each independently hydrogen, a cyano group, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group, and The above L5 is a single bond, a substituted or unsubstituted C1 to C5 alkylene group, a substituted or unsubstituted C2 to C5 alkenylene group, a substituted or unsubstituted C2 to C5 alkynylene group, or a substituted or unsubstituted C6 to C20 arylene group, and [Structural Formula 4A] In the above structural formula 4A, R3 is hydrogen, a cyano group, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group.

9. In any one of paragraphs 1 through 8, A solid-state secondary battery comprising, with respect to a total amount of 100% by weight of the adhesive and the fluorescein-based dye, 90% by weight to 99.9% by weight of the adhesive.

10. In any one of paragraphs 1 through 8, The above fluorescein-based dye comprises fluorescein, rhodamine-based dye, eosin-based dye, erythrosine-based dye, and combinations thereof, for an all-solid-state secondary battery.

11. In any one of paragraphs 1 through 8, A solid-state secondary battery comprising, with respect to a total amount of 100% by weight of the adhesive and the fluorescein-based dye, the fluorescein-based dye in an amount of 0.01% to 10% by weight.

12. In any one of paragraphs 1 through 8, An all-solid-state secondary battery comprising the adhesive and the fluorescein-based dye in a weight ratio of 90:10 to 99.9:0.

1.

13. In any one of paragraphs 1 through 8, An all-solid-state secondary battery having a resistance of 300 Ω to 640 Ω for the adhesive layer.

14. A step of manufacturing an electrode-solid electrolyte layer laminate by laminating a solid electrolyte layer onto an electrode; A step of forming an adhesive layer by applying an adhesive composition comprising an adhesive, a fluorescein-based dye, and a solvent to the surface of the solid electrolyte layer of the electrode-solid electrolyte layer laminate; and A method for detecting the coating of an adhesive layer of a solid-state secondary battery, comprising the step of irradiating the adhesive layer with UV light and confirming whether the adhesive layer is coated by the fluorescence emitted from the adhesive layer.

15. In Paragraph 14, The above adhesive includes a first adhesive, and The first adhesive above includes a cyclic polymer, and The above-mentioned cyclic polymer comprises a first structural unit represented by the following structural formula 1A and a second structural unit represented by the following structural formula 1B, and A method for detecting a coating of an all-solid-state secondary battery adhesive layer, wherein the first structural unit and the second structural unit are bonded to each other by disulfide bonds: [Structural Formula 1A] In the above structural formula 1A, L1, L2, and L3 are each independently a single bond, a C1 to C10 alkylene group, a C2 to C10 alkenylene group, or a C2 to C10 alkynylene group, and The above Y1 and the above Y2 are each independently oxygen or sulfur, and [Structural Formula 1B] In the above structural formula 1B, L4 is a single bond, a C1 to C20 alkylene group, a C2 to C20 alkenylene group, or a C2 to C20 alkylene group.

16. In Paragraph 14, The above adhesive includes a second adhesive, and The second adhesive above comprises a network structure of a first linear polymer and a second linear polymer, and The first linear polymer comprises a first main chain and at least one first side chain represented by the following structural formula 3A, and The second linear polymer comprises a second main chain and at least one second side chain represented by the following structural formula 4A, and A method for detecting a coating of an all-solid-state secondary battery adhesive layer, wherein the first side chain and the second side chain are ionically bonded: [Structural Formula 3A] In the above structural formula 3A, R1 and R2 are each independently hydrogen, a cyano group, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group, and The above L5 is a single bond, a substituted or unsubstituted C1 to C5 alkylene group, a substituted or unsubstituted C2 to C5 alkenylene group, a substituted or unsubstituted C2 to C5 alkynylene group, or a substituted or unsubstituted C6 to C20 arylene group, and [Structural Formula 4A] In the above structural formula 4A, R3 is hydrogen, a cyano group, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group.

17. In Paragraph 14, A method for detecting the coating of an all-solid-state secondary battery adhesive layer, wherein the adhesive is included in an amount of 0.1% to 10% by weight with respect to 100% by weight of the adhesive composition.

18. In Paragraph 14, A method for detecting a coating of an all-solid-state secondary battery adhesive layer, wherein the above-mentioned fluorescein-based dye comprises fluorescein, rhodamine-based dye, eosin-based dye, erythrosine-based dye, and combinations thereof.

19. In Paragraph 14, A method for detecting a coating of an all-solid-state secondary battery adhesive layer, wherein the fluorescein-based dye is included in an amount of 0.001% to 1% by weight relative to 100% by weight of the adhesive composition.

20. In Paragraph 14, A method for detecting the coating of an all-solid-state secondary battery adhesive layer, wherein the adhesive composition is applied by spray coating.

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