Solid ion conductor compound, solid electrolyte comprising the same, electrochemical cell comprising the same, and preparation method thereof

Abstract

The present invention relates to a solid ion conductor compound represented by the following chemical formula 1, a solid electrolyte comprising the same, a method for manufacturing the same, and an electrochemical cell comprising the solid electrolyte. LixM1aM2bClyBrz The definitions of x, a, b, y, z, M1, and M2 above follow the description in this specification.

Description

Technology Field

[0001] The invention relates to a solid ion-conducting compound, a solid electrolyte containing the same, a lithium battery containing the same, and a method for manufacturing the same. Background Technology

[0002] All-solid-state lithium batteries contain a solid electrolyte. Since all-solid-state lithium batteries do not contain flammable organic solvents, they offer excellent stability.

[0003] Conventional solid electrolyte materials are not sufficiently stable with respect to lithium metal. Furthermore, the lithium ion conductivity of conventional solid electrolytes is lower than that of liquid substitutes. The problem to be solved

[0004] One aspect is to provide a solid ion conductor compound having excellent lithium ion conductivity by having a new composition. means of solving the problem

[0005] According to one aspect, a solid ionic conductor compound represented by the following chemical formula 1 is provided:

[0006] <Chemical Formula 1>

[0007] Li x M1 a M2 b Cl y Br z

[0008] M1 comprises one or more metal elements selected from alkali metals, alkaline earth metals, and transition metals, and

[0009] M2 is one or more lanthanide elements selected from among the lanthanide elements, and

[0010] 0 <x<3.5, 0≤a<1.5, 0<b<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5이다.

[0011] According to another aspect, a solid electrolyte comprising the above-mentioned solid ion-conducting compound is provided.

[0012] According to another aspect, an electrochemical cell is provided comprising: an anode layer including an anode active material layer; a cathode layer including a cathode active material layer; and an electrolyte layer disposed between the anode layer and the cathode layer, wherein the anode active material layer, the electrolyte layer, or a combination thereof includes the solid ion-conducting compound.

[0013] According to another aspect, a method for manufacturing a solid ion conductor compound is provided, comprising the steps of: mixing a lithium precursor compound and a lanthanum halide precursor compound to prepare a mixture; and reacting the mixture in a solid phase. Effects of the invention

[0014] According to one aspect, an electrochemical cell having improved stability and cycle characteristics is provided by including a solid ion conductor compound with improved lithium ion conductivity and stability with respect to lithium metal. Brief explanation of the drawing

[0015] FIG. 1 shows the XRD spectra of Examples 1 to 5 and Comparative Examples 1 and 2. FIG. 2 shows the EIS evaluation curves for the solid ion conductor compounds obtained in Example 1 and Comparative Examples 1 and 2. FIG. 3 shows the initial charge-discharge curves of the all-solid-state lithium secondary batteries of Example 14 and Comparative Example 13. Figure 4 is a graph showing the limiting current density for the solid ion conductor compounds obtained in Example 1 and Comparative Example 1. Figure 5 is a graph showing the change in mole fraction of Br and the ionic conductivity and crystal phase before and after heat treatment. Figure 6 is a differential scanning calorimetry graph for solid ion conductor compounds obtained in Example 1, Comparative Examples 1 and 2. Figure 7 is a graph showing the change in voltage according to the charge-discharge cycle of the lithium symmetrical cells fabricated in Example 15 and Comparative Example 14. FIG. 8 is a schematic diagram of one embodiment of an all-solid-state secondary battery. FIG. 9 is a schematic diagram of another embodiment of an all-solid-state secondary battery. FIG. 10 is a schematic diagram of another embodiment of an all-solid-state secondary battery. <Explanation of symbols for major parts of the drawing> 1, 1a: All-solid-state secondary battery 10: Cathode 11: Positive current collector 12: Positive active material layer 20: Cathode 21: Cathode current collector 22: Cathode active material layer 23: Metal layer 30: Solid electrolyte layer 40: All-solid-state secondary battery Specific details for implementing the invention

[0016] Various embodiments are illustrated in the accompanying drawings. However, the present creative concept may be embodied in many different forms and should not be interpreted as being limited to the embodiments described herein. Rather, these embodiments are provided to ensure that the present disclosure is thorough and complete and will sufficiently convey the scope of the present creative concept to those skilled in the art. Identical reference numerals denote identical components.

[0017] When it is stated that one component is "on top" of another component, it can be understood that it may be directly on top of the other component or that another component may be interposed between them. In contrast, when it is stated that a component is "directly on top" of another component, no component is interposed between them.

[0018] Terms such as "first," "second," "third," etc., may be used in this specification to describe various components, components, regions, layers, and / or zones, but these components, components, regions, layers, and / or zones should not be limited by these terms. These terms are used solely to distinguish one component, component, region, layer, or zone from another. Accordingly, the first component, component, region, layer, or zone described below may be referred to as the second component, component, region, layer, or zone without departing from the teachings of this specification.

[0019] The terms used herein are intended to describe specific embodiments only and are not intended to limit the creative idea. The singular form used herein is intended to include the plural form including "at least one" unless the content clearly indicates otherwise. "At least one" should not be interpreted as limiting to the singular. As used herein, the term "and / or" includes any combination of one or more of the listed items. The terms "comprising" and / or "comprising" as used in the detailed description specify the presence of the specified features, regions, integers, steps, actions, components, and / or components, and do not exclude the presence or addition of one or more other features, regions, integers, steps, actions, components, components, and / or groups thereof.

[0020] Spatially relative terms such as "bottom," "lower," "subordinate," "top," "upper," and "upper" may be used herein to facilitate the description of the relationship of one component or feature to another component or feature. Spatially relative terms are to be understood as intended to include different orientations of the device during use or operation in addition to the orientations depicted in the drawings. For example, if the device in the drawings is inverted, a component described as "bottom" or "lower" of another component or feature will be oriented to the "top" of that other component or feature. Thus, the exemplary term "bottom" may encompass both the upper and lower directions. The device may be positioned in different directions (it may be rotated 90 degrees or rotated in other directions), and spatially relative terms used herein may be interpreted accordingly.

[0021] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art to which this disclosure pertains. Furthermore, it will also be understood that terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning within the context of the relevant technology and the content of this disclosure, and should not be interpreted in an idealized or overly formal sense.

[0022] Exemplary embodiments are described herein with reference to cross-sectional views, which are schematic diagrams of idealized embodiments. As such, variations from the depicted shapes should be expected as a result of, for example, manufacturing techniques and / or tolerances. Accordingly, the embodiments described herein should not be interpreted as being limited to the specific shapes of the regions as depicted herein, but should include variations in shapes resulting from, for example, manufacturing. For example, a region depicted or described as flat may typically have rough and / or non-linear features. Furthermore, an angle depicted as sharp may be rounded. Accordingly, the regions depicted in the drawings are essentially schematic, and the shapes are not intended to depict the exact shape of the region and are not intended to limit the scope of the claims.

[0023] "Group" refers to a group of elements in the periodic table according to the International Union of Pure and Applied Chemistry ("IUPAC") group classification system of groups 1-18.

[0024] Although specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently anticipated or cannot be anticipated may arise to the applicant or those skilled in the art. Accordingly, the appended claims, which may be filed and modified, are intended to include all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0025] A solid ion-conducting compound according to one or more exemplary embodiments, a solid electrolyte containing the same, an electrochemical cell containing the same, and a method for manufacturing the solid ion-conducting compound are described in more detail below.

[0026] [Solid Ion Conductor Compounds]

[0027] A solid ion conductor compound according to one aspect can be represented by the following chemical formula 1:

[0028] <Chemical Formula 1>

[0029] Li x M1a M2 b Cl y Br z

[0030] M1 comprises one or more metallic elements selected from alkali metals, alkaline earth metals, and transition metals, and M2 is one or more lanthanide elements selected from lanthanide elements, and 0 <x<3.5, 0≤a<1.5, 0<b<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5이다.

[0031] The solid ion conductor compound represented by the above chemical formula 1 contains Cl and Br among the halogen elements simultaneously, which expands the movement pathways of lithium due to the expansion of the lattice size caused by crystal lattice expansion, and as a result, the lithium ion conductivity is improved.

[0032] In addition, the crystallization temperature is reduced by mixing two types of halogen elements, making synthesis easier under mild conditions (i.e., at low temperatures) compared to cases containing a single halogen element.

[0033] In addition, the mole fractions (y / z) of Cl and Br are 0.166 <y / z≤5를 만족하는 것에 의하여, 이온전도체 화합물의 활성화 에너지가 감소하여 리튬 이온전도도가 향상된다.

[0034] Furthermore, as the mole fraction of Br gradually increases, the proportion of the amorphous phase in the compound increases, and as a result, the lithium ion conductivity is further improved.

[0035] In addition, the lithium ion conductivity of the solid ion conductor compound is improved by introducing a lanthanide element with an optimal size into the octahedral site space within the crystal, thereby reducing the activation energy compared to the case containing a transition metal. Furthermore, by including a lanthanide element with high reduction stability during cell operation, the reduction of the lanthanide element is suppressed, thereby suppressing the decomposition of the solid electrolyte, and the limiting current density increases due to increased durability, thereby improving high-rate characteristics.

[0036] According to one embodiment, the solid ion conductor compound may include a layered rock salt crystal structure.

[0037] For example, the layered rock salt crystal structure may include a twisted layered rock salt crystal structure.

[0038] According to one embodiment, the solid ion conductor compound may include a crystal structure belonging to the C2 / m space group. According to one embodiment, the solid ion conductor compound may include a crystal structure belonging to the C2 / m space group and a crystal structure belonging to the P3m1 space group. By having a crystal structure of the space group, excellent lithium ion conductivity can be achieved.

[0039] According to one embodiment, the solid ion conductor compound may not have a diffraction peak at a diffraction angle 2θ = 40° to 44° in an XRD spectrum using CuKα lines. By doing so, lithium ion conductivity may be improved.

[0040] According to one embodiment, in the above formula 1, M2 may be one or more lanthanide elements selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Here, M2 may be a lanthanide element with an oxidation state of 3.

[0041] For example, the above M2 may be one or more lanthanide elements selected from La, Ho, Tm, Yb, and Lu, but is not necessarily limited thereto.

[0042] According to one embodiment, in the above Chemical Formula 1, a is 0 <a<1.5이고, Li의 일부가 M1으로 치환될 수 있다. 예를 들어, 상기 화학식 1 중 M1은 결정 내 리튬 자리에 도핑되어 배치될 수 있다. M1의 도입에 의하여 결정 격자의 부피가 증가되어 리튬 이온의 이동 저항이 감소되어, 리튬 이온 전도도가 향상된다.

[0043] For example, in the above Chemical Formula 1, a is 0 <a≤1.4, 0<a≤1.3, 0<a≤1.2, 0<a≤1.1, 0<a≤1, 0<a≤0.9, 0<a≤0.8, 0<a≤0.7, 0<a≤0.6, 0<a≤0.5, 0<a≤0.4, 0<a≤0.3, 0<a≤0.2 또는 0<a≤0.1일 수 있으나, 이에 한정되는 것은 아니며, a의 범위는 고체이온전도체 화합물의 리튬 이온전도도를 해치지 않고, 화합물의 전하 균형을 고려하여 선택할 수 있으며, 예를 들어, 0<a<0.1일 수 있다.

[0044] According to one embodiment, M1 may include Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, Al, Ga, In, Ti, Ge, Sn, Pb, Sb, Bi, Po, or a combination thereof. When the metal element is included simultaneously with a lanthanide element, the resistance to movement of lithium ions within the crystal is reduced without crystal collapse, thereby further improving lithium ion conductivity.

[0045] According to one embodiment, in the above chemical formula 1, y and z can satisfy 1≤y≤5 and 1≤z≤5, respectively. By including a molar ratio of halogen elements satisfying the above ranges, the crystallization temperature is reduced, making synthesis at low temperatures easier, and the ionic conductivity increases due to the expansion of the lattice size.

[0046] According to one embodiment, 2.5 <x<3.5, 2<y<5이고, 5.4<x+y<6.6일 수 있다. 예를 들어, 2.7<x<3.3, 2.5<y<5이고, 5.7<x+y<6.3일 수 있다.

[0047] According to one implementation example, b can be 1.

[0048] According to one embodiment, in the above Chemical Formula 1, y=z. For example, y and z may be 3. When the mole fractions of Cl and Br are equal, the activation energy decreases due to the lattice expansion of the solid ion conductor compound, and the lithium ion conductivity can be significantly improved.

[0049] According to one embodiment, the chemical formula 1 is 0.166 <y / z<5을 만족할 수 있다. 예를 들어, 0.166<y / z≤3 또는 0.166<y / z≤2 일 수 있다.

[0050] According to one embodiment, the chemical formula 1 is 0.16 <z / (y+z)<0.85을 만족할 수 있다. 예를 들어, 0.16<z / (y+z)<0.84, 0.16<z / (y+z)<0.67, 0.16<z / (y+z)<0.55, 0.16<z / (y+z)≤0.5, 0.16<z / (y+z)<0.34일 수 있다.

[0051] According to one embodiment, 1 of the above chemical formula 1 <z<6이고, 상기 고체이온전도체 화합물은 P3m1 공간군 및 C2 / m 공간군에 속하는 결정구조를 포함할 수 있다. 이에 의하여 우수한 리튬 이온전도도를 가질 수 있다.

[0052] According to one embodiment, the above chemical formula 1 can be represented by the following chemical formula 2:

[0053] <Chemical Formula 2>

[0054] Li 3-a' M11 a' M2 b Cl y Br z

[0055] Among the above chemical formula 2,

[0056] M11 refers to the description of M1, and M2 refers to the aforementioned,

[0057] 0≤a'<1.5, 0 <b<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5이다.

[0058] According to one embodiment, the solid ion conductor compound is

[0059] Li x HoCl y Br z (0 <x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x CeCl y Br z (0 <x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x PrCl y Br z (0 <x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x NdCl y Br z (0 <x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x PmCl y Br z (0 <x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x SmCl y Br z (0 <x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x EuCl y Br z (0 <x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x GdCl y Br z (0 <x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x TbCl y Br z (0 <x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x DyCl y Br z (0 <x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x ErCl y Br z (0 <x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li xTmCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x YbCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), 및 Li x LuCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5); 및

[0060] Li x M1 a HoCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a CeCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a PrCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a NdCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a PmCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a SmCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a EuCl y Br z(0 <x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a GdCl y Br z (0 <x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a TbCl y Br z (0 <x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a DyCl y Br z (0 <x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a ErCl y Br z (0 <x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a TmCl y Br z (0 <x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a YbCl y Br z (0 <x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), 및 Li x M1 a LuCl y Br z (0 <x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5);

[0061] Selected from among,

[0062] M1 may include one or more metal elements selected from alkali metals, alkaline earth metals, and transition metals.

[0063] According to one embodiment, the solid ion conductor compound is 10 at room temperature, for example at 20°C. -4 It can have an ionic conductivity of S / cm or greater. For example, the solid ionic conductor compound has 1.8 x 10⁻⁶ at 20°C -4 S / cm or greater, 1.9 x 10 -4 S / cm or higher, 2.0 x 10 -4 S / cm or larger, 2.5 x 10 -4 S / cm or higher, 3.0 x 10 -4 S / cm or greater, 3.5 x 10 -4 S / cm or higher, 4.0 x 10 -4 S / cm or larger, 4.5 x 10 -4 S / cm or higher, 5.0 x 10 -4 S / cm or more, and 5.5 x 10 -4 It may be greater than S / cm.

[0064] [Solid Electrolyte]

[0065] A solid electrolyte according to another aspect comprises the aforementioned solid ion-conducting compound. By including such a solid ion-conducting compound, the solid electrolyte may have high ion conductivity and high chemical stability. The solid electrolyte comprising the solid ion-conducting compound may provide improved stability against air and electrochemical stability against lithium metal. Accordingly, the solid ion-conducting compound may be used, for example, as a solid electrolyte in an electrochemical cell.

[0066] The solid electrolyte may additionally include conventional general solid electrolytes in addition to the aforementioned solid ion conductor compounds. For example, it may additionally include conventional general sulfide-based solid electrolytes and / or oxide-based solid electrolytes. Conventional solid electrolyte compounds additionally included are, for example, Li2O-Al2O3-TiO2-P2O5 (LATP), LISICON (Lithium Super Ionic Conductor), LIPON (Li 3-y PO4-x N x , 0 <y<3, 0<x<4), Thio-LISICON(Li 3.25 Ge 0.25 P 0.75 S4), Li2S, Li2S-P2S5, Li2S-SiS2, Li2S-GeS2, Li2S-B2S5, and Li2S-Al2S5, etc., may be used, but are not necessarily limited to these, and any that can be used in the relevant technical field is acceptable.

[0067] Solid electrolytes may be in the form of powder or molded articles. Solid electrolytes in the form of molded articles may be, for example, pellets, sheets, or thin films, but are not necessarily limited to these and can take various forms depending on the application.

[0068] [Electrochemical Cell]

[0069] An electrochemical cell according to another embodiment comprises: an anode layer including an anode active material layer; a cathode layer including a cathode active material layer; and an electrolyte layer disposed between the anode layer and the cathode layer, wherein the anode active material layer and / or the electrolyte layer comprises the aforementioned solid ion conductor compound. By including the solid ion conductor compound, the lithium ion conductivity and chemical stability of the electrochemical cell are improved.

[0070] The electrochemical cell may be, for example, an all-solid-state secondary battery, a secondary battery containing a liquid electrolyte, or a lithium-air battery, but is not necessarily limited to these; any electrochemical cell usable in the relevant technical field is acceptable.

[0071] In the following, solid-state secondary batteries will be explained in more detail.

[0072] [All-solid-state secondary battery: Type 1]

[0073] The all-solid-state secondary battery may include the aforementioned solid-state ion-conducting compound.

[0074] A solid-state secondary battery comprises, for example, a positive electrode layer including a positive electrode active material layer; a negative electrode layer including a negative electrode active material layer; and an electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the positive electrode active material layer and / or the electrolyte layer may include the aforementioned solid ion-conducting compound.

[0075] An all-solid-state secondary battery according to one embodiment can be prepared as follows.

[0076] (Solid electrolyte layer)

[0077] First, a solid electrolyte layer is prepared.

[0078] The solid electrolyte layer can be manufactured by mixing and drying the aforementioned solid ion-conducting compound and a binder, or by rolling the powder of the solid ion-conducting compound represented by Chemical Formula 1 into a specific shape under a pressure of 1 ton to 10 ton. The aforementioned solid ion-conducting compound is used as a solid electrolyte.

[0079] The average particle size of the solid electrolyte may be, for example, 0.5 µm to 20 µm. Since the solid electrolyte has such an average particle size, the binding properties are improved during the sintering process, which can improve the ionic conductivity and lifespan characteristics of the solid electrolyte particles.

[0080] The thickness of the solid electrolyte layer can be 10 µm to 200 µm. By having such a thickness of the solid electrolyte layer, a sufficient mobility of lithium ions is ensured, and as a result, high ionic conductivity can be obtained.

[0081] The solid electrolyte layer may further include a solid electrolyte, such as a conventional sulfide-based solid electrolyte and / or an oxide-based solid electrolyte, in addition to the aforementioned solid ion-conducting compound.

[0082] Conventional sulfide-based solid electrolytes may comprise, for example, lithium sulfide, silicon sulfide, phosphorus sulfide, boron sulfide, or combinations thereof. Conventional sulfide-based solid electrolyte particles may comprise Li2S, P2S5, SiS2, GeS2, B2S3, or combinations thereof. Conventional sulfide-based solid electrolyte particles may be Li2S or P2S5. Conventional sulfide-based solid electrolyte particles are known to have high lithium ion conductivity compared to other inorganic compounds. For example, conventional sulfide-based solid electrolytes comprise Li2S and P2S5. When the sulfide solid electrolyte material constituting the conventional sulfide-based solid electrolyte comprises Li2S-P2S5, the mixed molar ratio of Li2S to P2S5 may be, for example, in the range of about 50:50 to about 90:10. In addition, Li3PO4, halogen, halogen compound, Li 2+2x Zn 1-x GeO4("LISICON"), Li 3+y PO 4-x N x( "LIPON"), Li 3.25 Ge 0.25 P 0.75 S4("ThioLISICON"), Li2O-Al2O3-TiO2-P2O 5( Inorganic solid electrolytes prepared by adding "LATP," etc., to inorganic solid electrolytes of Li2S-P2S5, SiS2, GeS2, B2S3, or combinations thereof can be used as conventional sulfide solid electrolytes. Non-limiting examples of conventional sulfide solid electrolyte materials include Li2S-P2S5; Li2S-P2S5-LiX (where X is a halogen element); Li2S-P2S5-Li2O; Li2S-P2S5-Li2O-LiI; Li2S-SiS2; Li2S-SiS2-LiI; Li2S-SiS2-LiBr; Li2S-SiS2-LiCl; Li2S-SiS2-B2S3-LiI; Li2S-SiS2-P2S5-LiI; Li2S-B2S3; Li2S-P2S5-Z m S n(m and n are positive numbers, and Z is Ge, Zn, or G); Li2S-GeS2; Li2S-SiS2-Li3PO4; and Li2S-SiS2-Li p MO q (In the above formula, p and q are positive numbers, and M is P, Si, Ge, B, Al, Ga, or In). In this regard, conventional sulfide-based solid electrolyte materials can be manufactured by processing raw material starting materials of sulfide-based solid electrolyte materials (e.g., Li2S, P2S5, etc.) by a melt quenching method, mechanical milling method, etc. Additionally, a calcination process may be performed after the above processing.

[0083] The binder included in the solid electrolyte layer is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, etc., but is not limited to these, and any binder used in the relevant technical field is acceptable. The binder of the solid electrolyte layer may be of the same type as or different from the binder of the anode layer and the cathode layer.

[0084] (Bipolar layer)

[0085] Next, the anode layer is prepared.

[0086] The positive layer can be manufactured by forming a positive active material layer containing a positive active material on a current collector. The average particle size of the positive active material may be, for example, 2 µm to 10 µm.

[0087] Any cathode active material commonly used in secondary batteries may be used without restriction. For example, it may be lithium transition metal oxides, transition metal sulfides, etc. For example, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used, and specific examples include Li a A 1-b B 1 b D 1 2 (wherein, 0.90 ≤ a ≤ 1.8, and 0 ≤ b ≤ 0.5); Li a E 1-b B 1 b O 2-c D 1 c (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2-b B 1 b O 4-c D 1 c (In the above equation, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B 1 c D 1 α (In the above equation, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Co b B 1 c O 2-α F 1 α (In the above equation, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Co b B 1 c O 2-α F 1α (In the above equation, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B 1 c D 1 α (In the above equation, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mn b B 1 c O 2-α F 1 α (In the above equation, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B 1 c O 2-α F 1 2(in the above equation, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c G d O2(wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d GeO2(wherein the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2(in the above equation, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a CoG bO2(in the above equation, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a MnG b O2(in the above equation, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4(wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O2; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f) A compound represented by any one of the chemical formulas of Fe2(PO4)3 (0 ≤ f ≤ 2); LiFePO4 may be used. In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; and B 1 Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or combinations thereof; D 1 O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F 1 F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. For example, LiCoO2, LiMn x O 2x (x=1, 2), LiNi 1-x Mn x O 2x (0 <x<1), Ni 1-x-y Co x Mn y O2(0≤x≤0.5, 0≤y≤0.5), Ni 1-x-y Co x Al yO2 (0≤x≤0.5, 0≤y≤0.5), LiFePO4, TiS2, FeS2, TiS3, FeS3, etc.

[0088] Compounds having a coating layer added to the surface of such compounds may be used, and mixtures of the aforementioned compounds and compounds having a coating layer added may also be used. The coating layer added to the surface of such compounds includes, for example, a coating element compound comprising an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxycarbonate of a coating element. The compounds forming this coating layer are amorphous or crystalline. The coating elements included in the coating layer are Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the cathode active material. The coating method is, for example, spray coating or immersion. Since specific coating methods are well understood by those skilled in the art, a detailed explanation will be omitted.

[0089] The cathode active material includes, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen and metal atomic layers are alternately and regularly arranged in a specific direction, thereby forming a two-dimensional plane for each layer. The "cubic rock salt type structure" represents a sodium chloride (NaCl type) structure, which is a type of crystal structure; specifically, it exhibits a structure in which the face-centered cubic lattices (fcc) formed by cations and anions, respectively, are offset from each other by half the ridge of the unit lattice. Lithium transition metal oxides having such a layered rock salt type structure are, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn z It is a ternary lithium transition metal oxide such as O2(NCM) (0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1). When the positive electrode active material includes a ternary lithium transition metal oxide having a layered rock salt structure, the energy density and thermal stability of the all-solid-state secondary battery (1) are further improved.

[0090] As described above, the positive electrode active material may be covered by a coating layer. The coating layer may be any material known as a coating layer for the positive electrode active material of an all-solid-state secondary battery. For example, the coating layer is Li2O-ZrO2 (LZO), etc.

[0091] When the cathode active material is a ternary lithium transition metal oxide, such as NCA or NCM, containing nickel (Ni), it is possible to increase the capacity density of the all-solid-state secondary battery and reduce metal leaching from the cathode active material during charging. Consequently, the cycle characteristics of the all-solid-state secondary battery during charging are improved.

[0092] The shape of the positive active material is, for example, a particle shape such as a sphere, an elliptical sphere, etc. The particle size of the positive active material is not particularly limited and is within a range applicable to the positive active material of a conventional all-solid-state secondary battery. The content of the positive active material in the positive layer is also not particularly limited and is within a range applicable to the positive layer of a conventional all-solid-state secondary battery. The content of the positive active material in the positive active material layer may be, for example, 50 to 95 weight%.

[0093] The positive electrode active material layer may additionally include the aforementioned solid ion conductor compound. For example, the positive electrode active material layer and the solid electrolyte layer may simultaneously include the aforementioned solid ion conductor compound. For example, when the positive electrode active material layer includes the aforementioned solid ion conductor compound, the solid electrolyte layer may not include the aforementioned solid ion conductor compound.

[0094] The positive active material layer may include a binder. Examples of binders include styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc.

[0095] The cathode active material layer may include a conductive material. The conductive material is, for example, graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powder, etc.

[0096] The positive electrode active material layer may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids in addition to the aforementioned positive electrode active material, solid electrolyte, binder, and conductive material.

[0097] As fillers, coating agents, dispersants, ion conductivity aids, etc. that may be included in the positive electrode active material layer, known materials generally used in electrodes of all-solid-state secondary batteries can be used.

[0098] The positive current collector uses, for example, a plate or foil made of aluminum (Al), indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), germanium (Ge), lithium (Li), or alloys thereof. The positive current collector may be omitted.

[0099] The positive current collector may further include a carbon layer disposed on one or both sides of a metal substrate. By additionally disposing of a carbon layer on the metal substrate, the metal of the metal substrate may be prevented from being corroded by the solid electrolyte contained in the positive layer, and the interfacial resistance between the positive active material layer and the positive current collector may be reduced. The thickness of the carbon layer may be, for example, 1 µm to 5 µm. If the thickness of the carbon layer is excessively thin, it may be difficult to completely block contact between the metal substrate and the solid electrolyte. If the thickness of the carbon layer is excessively thick, the energy density of the all-solid-state secondary battery may decrease. The carbon layer may include amorphous carbon, crystalline carbon, etc.

[0100] (Cathode layer)

[0101] Next, the cathode layer is prepared.

[0102] The cathode layer can be manufactured in the same manner as the anode layer, except that a cathode active material is used instead of an anode active material. The cathode layer can be manufactured by forming a cathode active material layer containing the cathode active material on a cathode current collector.

[0103] The cathode active material layer may additionally include the aforementioned solid ion conductor compound.

[0104] The negative electrode active material may be lithium metal, a lithium metal alloy, or a combination thereof.

[0105] The negative electrode active material layer may further include a conventional negative electrode active material in addition to lithium metal, a lithium metal alloy, or a combination thereof. The conventional negative electrode active material may include, for example, one or more selected from the group consisting of a metal alloyable with lithium, a transition metal oxide, a non-transition metal oxide, and a carbon-based material. The metal alloyable with lithium may be, for example, Ag, Si, Sn, Al, Ge, Pb, Bi, Sb Si-Y alloy (wherein Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, rare earth element, or a combination thereof, and is not Si), Sn-Y alloy (wherein Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, rare earth element, or a combination thereof, and is not Sn), etc. The above element Y may be 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, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof. The transition metal oxide may be, for example, lithium titanium oxide, vanadium oxide, lithium vanadium oxide, etc. The non-transition metal oxide may be, for example, SnO2, SiO2 x(0 <x<2) 등일 수 있다. 탄소계 재료는 예를 들어 결정질 탄소, 비정질 탄소 또는 이들의 혼합물일 수 있다. 결정질 탄소는 무정형, 판상, 린편상(flake), 구형 또는 섬유형의 천연 흑연 또는 인조 흑연과 같은 흑연일 수 있으며, 상기 비정질 탄소는 소프트 카본(soft carbon: 저온 소성 탄소) 또는 하드 카본(hard carbon), 메조페이스 피치(mesophase pitch) 탄화물, 소성된 코크스 등일 수 있다.

[0106] Referring to FIG. 8, an all-solid-state secondary battery (40) according to one embodiment includes a solid electrolyte layer (30), a positive electrode layer (10) disposed on one side of the solid electrolyte layer (30), and a negative electrode layer (20) disposed on the other side of the solid electrolyte layer (30). The positive electrode layer (30) includes a positive active material layer (12) in contact with the solid electrolyte layer (30) and a positive current collector (11) in contact with the positive active material layer (12), and the negative electrode layer (20) includes a negative active material layer (22) in contact with the solid electrolyte layer (30) and a negative current collector (21) in contact with the negative active material layer (22). The all-solid-state secondary battery (40) is completed, for example, by forming a positive active material layer (12) and a negative active material layer (22) on both sides of a solid electrolyte layer (30), and forming a positive current collector (11) and a negative current collector (21) respectively on the positive active material layer (12) and the negative active material layer (22). Alternatively, the all-solid-state secondary battery (40) is completed, for example, by sequentially stacking a negative active material layer (22), a solid electrolyte layer (30), a positive active material layer (12), and a positive current collector (11) on a negative current collector (21).

[0107] [All-solid-state secondary battery: Type 2]

[0108] Referring to FIGS. 9 and 10, the all-solid-state secondary battery (1) comprises, for example, a positive electrode layer (10) comprising a positive active material layer (12) disposed on a positive current collector (11); a negative electrode layer (20) comprising a negative active material layer (22) disposed on a negative current collector (21); and an electrolyte layer (30) disposed between the positive electrode layer (10) and the negative electrode layer (20), wherein the positive active material layer (12) and / or the electrolyte layer (30) may comprise the aforementioned solid ion-conducting compound.

[0109] An all-solid-state secondary battery according to another embodiment can be prepared as follows.

[0110] The anode layer and the solid electrolyte layer are manufactured in the same way as the all-solid-state secondary battery described above.

[0111] (Cathode layer)

[0112] Next, the cathode layer is prepared.

[0113] Referring to FIGS. 9 and 10, the cathode layer (20) comprises a cathode current collector (21) and a cathode active material layer (22) disposed on the cathode current collector (21), and the cathode active material layer (22) comprises, for example, a cathode active material and a binder.

[0114] The negative electrode active material included in the negative electrode active material layer (22) has, for example, a particle shape. The average particle size of the negative electrode active material having a particle shape is, for example, 4 µm or less, 3 µm or less, 2 µm or less, 1 µm or less, or 900 nm or less. The average particle size of the negative electrode active material having a particle shape is, for example, 10 nm to 4 µm or less, 10 nm to 3 µm or less, 10 nm to 2 µm or less, 10 nm to 1 µm or less, or 10 nm to 900 nm or less. By having the negative electrode active material with an average particle size within this range, the reversible absorption and / or desorption of lithium during charging and discharging may be more easily facilitated. The average particle size of the negative electrode active material is, for example, the median diameter (D50) measured using a laser particle size distribution meter.

[0115] The cathode active material included in the cathode active material layer (22) comprises, for example, one or more selected from carbon-based cathode active materials and metal or metalloid cathode active materials.

[0116] The carbon-based cathode active material is, in particular, amorphous carbon. Amorphous carbon is, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, etc., but is not necessarily limited to these, and any material classified as amorphous carbon in the relevant technical field is acceptable. Amorphous carbon is carbon that does not have crystallinity or has very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon.

[0117] The metal or metalloid cathode active material comprises one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), but is not necessarily limited to these; any metal cathode active material or metalloid cathode active material that forms an alloy or compound with lithium in the relevant technical field is acceptable. For example, nickel (Ni) is not a metal cathode active material because it does not form an alloy with lithium.

[0118] The negative electrode active material layer (22) may include a type of negative electrode active material among these negative electrode active materials, or may include a mixture of multiple different negative electrode active materials. For example, the negative electrode active material layer (22) may include only amorphous carbon, or one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Alternatively, the negative electrode active material layer (22) may include a mixture of amorphous carbon and one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio of a mixture of amorphous carbon and gold, etc., is, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1 by weight ratio, but is not necessarily limited to these ranges and is selected according to the required characteristics of the all-solid-state secondary battery (1). By having the negative electrode active material have this composition, the cycle characteristics of the all-solid-state secondary battery (1) are further improved.

[0119] The negative electrode active material included in the negative electrode active material layer (22) comprises a mixture of first particles made of, for example, amorphous carbon and second particles made of a metal or metalloid. The metal or metalloid includes, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Alternatively, the metalloid is a semiconductor. The content of the second particles is 8 to 60 weight%, 10 to 50 weight%, 15 to 40 weight%, or 20 to 30 weight% based on the total weight of the mixture. By having the second particles in this range, the cycle characteristics of, for example, the all-solid-state secondary battery (1) are further improved.

[0120] The binder included in the negative electrode active material layer (22) may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but is not necessarily limited to these and any binder used in the relevant technical field is possible. The binder may be composed of a single binder or a plurality of different binders.

[0121] The negative active material layer (22) is stabilized on the negative current collector (21) by including a binder. Additionally, cracking of the negative active material layer (22) is suppressed despite changes in volume and / or relative position of the negative active material layer (22) during the charging and discharging process. For example, if the negative active material layer (22) does not include a binder, it is possible for the negative active material layer (22) to be easily separated from the negative current collector (21). As the negative active material layer (22) is separated from the negative current collector (21), the possibility of a short circuit occurring increases as the negative current collector (21) comes into contact with the solid electrolyte layer (30) in the exposed portion of the negative current collector (21). The negative active material layer (22) is manufactured, for example, by applying a slurry in which the material constituting the negative active material layer (22) is dispersed onto the negative current collector (21) and drying it. By including a binder in the negative electrode active material layer (22), stable dispersion of the negative electrode active material in the slurry is possible. For example, when the slurry is applied onto the negative electrode current collector (21) by a screen printing method, it is possible to suppress clogging of the screen (e.g., clogging by aggregates of the negative electrode active material).

[0122] The negative electrode active material layer (22) may further include additives used in conventional all-solid-state secondary batteries (1), such as fillers, coating agents, dispersants, ion-conducting aids, etc.

[0123] The thickness of the negative electrode active material layer (22) is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer (12). The thickness of the negative electrode active material layer (22) is, for example, 1 µm to 20 µm, 2 µm to 10 µm, or 3 µm to 7 µm. If the thickness of the negative electrode active material layer (22) is excessively thin, lithium dendrites formed between the negative electrode active material layer (22) and the negative electrode current collector (21) cause the negative electrode active material layer (22) to collapse, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1). If the thickness of the negative electrode active material layer (22) increases excessively, the energy density of the all-solid-state secondary battery (1) decreases and the internal resistance of the all-solid-state secondary battery (1) due to the negative electrode active material layer (22) increases, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1).

[0124] If the thickness of the negative electrode active material layer (22) decreases, for example, the charging capacity of the negative electrode active material layer (22) also decreases. The charging capacity of the negative electrode active material layer (22) is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, or 2% or less compared to the charging capacity of the positive electrode active material layer (12). The charging capacity of the negative electrode active material layer (22) is, for example, 0.1% to 50%, 0.1% to 40%, 0.1% to 30%, 0.1% to 20%, 0.1% to 10%, 0.1% to 5%, or 0.1% to 2% compared to the charging capacity of the positive electrode active material layer (12). If the charge capacity of the negative electrode active material layer (22) is excessively small, the thickness of the negative electrode active material layer (22) becomes very thin, and thus, during repeated charge and discharge processes, lithium dendrites formed between the negative electrode active material layer (22) and the negative electrode current collector (21) cause the negative electrode active material layer (22) to collapse, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1). If the charge capacity of the negative electrode active material layer (22) increases excessively, the energy density of the all-solid-state secondary battery (1) decreases, and the internal resistance of the all-solid-state secondary battery (1) caused by the negative electrode active material layer (22) increases, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1).

[0125] The charge capacity of the positive active material layer (12) is obtained by multiplying the charge capacity density (mAh / g) of the positive active material by the mass of the positive active material in the positive active material layer (12). When multiple types of positive active materials are used, the charge capacity density × mass value is calculated for each positive active material, and the sum of these values ​​is the charge capacity of the positive active material layer (12). The charge capacity of the negative active material layer (22) is calculated in the same way. That is, the charge capacity of the negative active material layer (22) is obtained by multiplying the charge capacity density (mAh / g) of the negative active material by the mass of the negative active material in the negative active material layer (22). When multiple types of negative active materials are used, the charge capacity density × mass value is calculated for each negative active material, and the sum of these values ​​is the capacity of the negative active material layer (22). Here, the charge capacity densities of the positive active material and the negative active material are the capacity estimated using an all-solid-state half-cell using lithium metal as the counter electrode. The charge capacity of the positive active material layer (12) and the negative active material layer (22) is directly measured by measuring the charge capacity using an all-solid half-cell. By dividing the measured charge capacity by the mass of each active material, the charge capacity density is obtained. Alternatively, the charge capacity of the positive active material layer (12) and the negative active material layer (22) may be the initial charge capacity measured during the first cycle of charging.

[0126] Referring to FIG. 10, the all-solid-state secondary battery (1a) may further include a metal layer (23) disposed between, for example, a negative electrode current collector (21) and a negative electrode active material layer (22). The metal layer (23) comprises lithium or a lithium alloy. Thus, the metal layer (23) acts as, for example, a lithium reservoir. The lithium alloy is, for example, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, etc., but is not limited to these, and any alloy used as a lithium alloy in the relevant technical field is possible. The metal layer (23) may be made of one of these alloys or lithium, or may be made of various types of alloys.

[0127] The thickness of the metal layer (23) is not particularly limited, but is, for example, 1 µm to 1000 µm, 1 µm to 500 µm, 1 µm to 200 µm, 1 µm to 150 µm, 1 µm to 100 µm, or 1 µm to 50 µm. If the thickness of the metal layer (23) is excessively thin, it is difficult for the metal layer (23) to perform the role of a lithium reservoir. If the thickness of the metal layer (23) is excessively thick, the mass and volume of the all-solid-state secondary battery (1) may increase, and the cycle characteristics may actually deteriorate. The metal layer (23) may be, for example, a metal foil having a thickness within this range.

[0128] In the all-solid-state secondary battery (1a), the metal layer (23) is disposed between the negative electrode current collector (21) and the negative electrode active material layer (22) for example before assembly of the all-solid-state secondary battery (1), or is deposited between the negative electrode current collector (21) (21, 21a, 21b) and the negative electrode active material layer (22) by charging after assembly of the all-solid-state secondary battery (1). When the metal layer (23) is disposed between the negative electrode current collector (21) and the negative electrode active material layer (22) before assembly of the all-solid-state secondary battery (1a), the metal layer (23) acts as a lithium reservoir because it is a metal layer containing lithium. For example, a lithium foil is disposed between the negative electrode current collector (21) and the negative electrode active material layer (22) before assembly of the all-solid-state secondary battery (1a). Accordingly, the cycle characteristics of the all-solid-state secondary battery (1a) including the metal layer (23) are further improved. When the metal layer (23) is precipitated by charging after assembly of the all-solid-state secondary battery (1a), the energy density of the all-solid-state secondary battery (1a) increases because the metal layer (23) is not included during assembly of the all-solid-state secondary battery (1a). For example, when charging the all-solid-state secondary battery (1), it is charged beyond the charging capacity of the negative electrode active material layer (22). That is, the negative electrode active material layer (22) is overcharged. At the beginning of charging, lithium is absorbed in the negative electrode active material layer (22). The negative electrode active material included in the negative electrode active material layer (22) forms an alloy or compound with lithium ions that have moved from the positive electrode layer (10). When charging is performed beyond the capacity of the negative electrode active material layer (22), lithium is deposited, for example, on the back surface of the negative electrode active material layer (22), that is, between the negative electrode current collector (21) and the negative electrode active material layer (22), and a metal layer corresponding to the metal layer (23) is formed by the deposited lithium. The metal layer (23) is a metal layer composed mainly of lithium (i.e., metallic lithium). This result is obtained, for example, by the negative electrode active material included in the negative electrode active material layer (22) being composed of a material that forms an alloy or compound with lithium. During discharge, the lithium in the negative electrode active material layer (22) and the metal layer (23), that is, the metal layer, is ionized and moves toward the positive electrode layer (10).Therefore, it is possible to use lithium as a negative electrode active material in an all-solid-state secondary battery (1a). In addition, since the negative electrode active material layer (22) covers the metal layer (23), it acts as a protective layer for the metal layer (23) and simultaneously suppresses the precipitation growth of lithium dendrites. Thus, it suppresses short circuits and capacity degradation of the all-solid-state secondary battery (1a), and consequently improves the cycle characteristics of the all-solid-state secondary battery (1a). Furthermore, when the metal layer (23) is placed by charging after assembly of the all-solid-state secondary battery (1a), the negative electrode current collector (21), the negative electrode active material layer (22), and the region between them are, for example, Li-free regions that do not contain lithium (Li) in the initial state or after discharge state of the all-solid-state secondary battery (1a).

[0129] The negative electrode current collector (21) is composed of a material that does not react with, for example, lithium, that is, does not form any alloys or compounds. The material constituting the negative electrode current collector (21) may be, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not necessarily limited to these; any material used as an electrode current collector in the relevant technical field is acceptable. The negative electrode current collector (21) may be composed of one of the metals described above, or may be composed of an alloy or coating material of two or more metals. The negative electrode current collector (21) is, for example, in the form of a plate or foil.

[0130] The all-solid-state secondary battery (1) may further include a thin film containing an element capable of forming an alloy with lithium, for example, on a negative electrode current collector (21). The thin film is disposed between the negative electrode current collector (21) and the negative electrode active material layer (22). The thin film contains, for example, an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium is, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but is not necessarily limited to these, and any element capable of forming an alloy with lithium in the relevant technical field is possible. The thin film is composed of one of these metals or is composed of an alloy of various types of metals. By disposing of the thin film on the negative electrode current collector (21), the deposition pattern of the metal layer (23) deposited between, for example, the thin film (24) and the negative electrode active material layer (22) is further flattened, and the cycle characteristics of the all-solid-state secondary battery (1) can be further improved.

[0131] The thickness of the thin film is, for example, 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. If the thickness of the thin film is less than 1 nm, it may be difficult to perform the function provided by the thin film. If the thickness of the thin film is excessively thick, the thin film itself absorbs lithium, and the amount of lithium precipitated at the negative electrode decreases, which lowers the energy density of the all-solid-state battery and may degrade the cycle characteristics of the all-solid-state secondary battery (1). The thin film may be placed on the negative electrode current collector (21, 21a, 21b) by, for example, vacuum deposition, sputtering, plating, etc., but is not necessarily limited to these methods, and any method capable of forming a thin film in the relevant technical field is possible.

[0132] A method for manufacturing a solid ion-conducting compound according to an embodiment of another aspect comprises the steps of: preparing a mixture by mixing a lithium precursor compound and a precursor compound containing a lanthanum element (hereinafter referred to as a "lanthanum precursor compound"); and reacting the mixture in a solid phase. The solid ion-conducting compound is the solid ion-conducting compound described above.

[0133] The above lithium precursor compound may include a lithium halide. For example, the lithium halide may include LiCl, LiBr, or a combination thereof.

[0134] The above lanthanide precursor compound may include halides of lanthanide elements. For example, halides of lanthanide elements include LaCl3, CeCl3, PrCl3, NdCl3, PmCl3, SmCl3, EuCl3, GdCl3, TbCl3, DyCl3, HoCl3, ErCl3, TmCl3, YbCl3, and LuCl3. 3, It may include CeBr3, LaBr3, PrBr3, NdBr3, PmBr3, SmBr3, EuBr3, GdBr3, TbBr3, DyBr3, HoBr3, ErBr3, TmBr3, YbBr3, LuBr3, or combinations thereof. For example, the lanthanide precursor compound may include LaCl3, HoCl3, TmCl3, YbCl3, LuCl3 3, It may include HoBr3, TmBr3, YbBr3, LuBr3, or a combination thereof.

[0135] According to one embodiment, the mixture may include one lithium precursor compound and one lanthanum precursor compound, or two different lithium precursor compounds and one lanthanum precursor compound.

[0136] The mixing ratio of the lithium precursor compound and the lanthanide precursor compound included in the above mixture can be appropriately adjusted by considering the composition ratio of the desired solid ion conductor compound.

[0137] According to one embodiment, the step of reacting the mixture in a solid state may include performing ball mill mixing of the mixture at 700 rpm for 72 hours in a dry and inert atmosphere.

[0138] According to one embodiment, the ball mill mixing is performed with a first time interval, and a second rest period may be taken between the first time intervals. Here, the first time and the second time may be the same or different from each other. For example, the first time may be twice the time of the second time. In this way, by taking a rest period during the ball mill mixing process, a solid ion conductor compound can be obtained as a mixture of crystalline and amorphous phases.

[0139] According to one embodiment, the method for manufacturing the solid ion conductor compound is carried out at room temperature and does not include a calcination step for crystallization. For example, the method for manufacturing the solid ion conductor compound can be carried out at room temperature (25°C).

[0140] According to one embodiment, following the step of reacting the mixture in a solid phase, the method may further include a step of heat treating at 200°C to 300°C for 4 to 6 hours.

[0141] The above heat treatment step may be optionally performed to improve ion conductivity, for example, 0 in Chemical Formula 1 <y / z≤1을 만족하는 고체이온전도체 화합물에서 열처리를 가하는 경우 이온전도도가 향상될 수 있다.

[0142] In addition, 1 of the above Chemical Formula 1 <y / z<6을 만족하는 고체이온전도체는 열처리를 하는 경우 Br 원소의 몰분율이 낮아, 결정화가 진행되어 이온전도도가 저하될 수 있다.

[0143] To verify this, the crystal phase and ionic conductivity before and after heat treatment were measured for cases where the mole fraction of Br was 0 to 6, and are shown in Figure 5.

[0144] The above-mentioned inert atmosphere is an atmosphere containing an inert gas. The inert gas may be, for example, nitrogen, argon, etc., but is not necessarily limited to these; any gas used as an inert gas in the relevant technical field is acceptable.

[0145] The creative idea is explained in more detail through the following examples and comparative examples. However, the examples are intended to illustrate the creative idea and do not limit the scope of the creative idea to these examples alone.

[0146] (Preparation of solid ion-conducting compounds)

[0147] Example 1

[0148] HoCl3, a lanthanum precursor compound, and LiBr, a lithium precursor compound, were introduced into a planetary ball mill in a stoichiometric ratio of 1:3 inside a glove box under an Ar atmosphere. Zirconia (YSZ) balls were then introduced, and the mixture was ground and mixed at 700 rpm under an Ar atmosphere for 10 minutes, followed by a 5-minute rest period. This cycle was repeated for 72 hours to obtain a mixture. After grinding the obtained mixture, it was crystallized by heat treatment at 260°C for 5 hours to obtain a solid ion conductor compound with the composition listed in Table 1 below. Subsequently, for XRD analysis, the obtained solid ion conductor compound was pressed at a uniaxial pressure of 350 MPa to prepare a pellet with a thickness of approximately 800 mm and a diameter of approximately 13 mm.

[0149] Example 2

[0150] A solid ion conductor compound was obtained in the same manner as in Example 1, except that HoBr3 was mixed as a lanthanum precursor compound and LiCl and LiBr were mixed as lithium precursor compounds in a stoichiometric ratio of 1:2:1, and the compound was molded to prepare a pellet.

[0151] Example 3

[0152] A solid ion conductor compound was obtained in the same manner as in Example 1, except that HoBr3 was mixed as a lanthanum precursor compound and LiCl and LiBr were mixed as lithium precursor compounds in a stoichiometric ratio of 1:1:2, and the compound was molded to prepare a pellet.

[0153] Example 4

[0154] In a dry room with a dew point of -60 degrees, HoCl3, a lanthanum precursor compound, and LiCl and LiBr, lithium precursor compounds, were fed into a planetary ball mill in a stoichiometric ratio of 1:1:2, and zirconia (YSZ) balls were added. Then, the mixture was ground and mixed at 700 rpm for 10 minutes in an Ar atmosphere, followed by a 5-minute rest period. This cycle was repeated for 72 hours to obtain a solid ion conductor compound with the composition listed in Table 1 below. Subsequently, the obtained solid ion conductor compound was pressed at a uniaxial pressure of 350 MPa for XRD analysis to prepare a pellet with a thickness of approximately 800 mm and a diameter of approximately 13 mm.

[0155] Example 5

[0156] A solid ion conductor compound was obtained in the same manner as in Example 4, except that HoCl3, a lanthanum precursor compound, and LiCl and LiBr, lithium precursor compounds, were mixed in a stoichiometric ratio of 1:2:1, and the compound was molded to prepare a pellet.

[0157] Example 6

[0158] A solid ion conductor compound was obtained in the same manner as in Example 1, except that LuBr3 was mixed as a lanthanum precursor compound and LiCl and LiBr were mixed as lithium precursor compounds in a stoichiometric ratio of 1:2:1, and the compound was molded to prepare a pellet.

[0159] Example 7

[0160] A solid ion conductor compound was obtained in the same manner as in Example 4, except that LuCl3 was mixed as a lanthanum precursor compound and LiCl and LiBr were mixed as lithium precursor compounds in a stoichiometric ratio of 1:2:1, and the compound was molded to prepare a pellet.

[0161] Example 8

[0162] A solid ion conductor compound was obtained in the same manner as in Example 1, except that TmCl3, a lanthanum precursor compound, and LiBr, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0163] Example 9

[0164] A solid ion conductor compound was obtained in the same manner as in Example 1, except that TmBr3 was mixed as a lanthanum precursor compound and LiCl and LiBr were mixed as lithium precursor compounds in a stoichiometric ratio of 1:2:1, and the compound was molded to prepare a pellet.

[0165] Example 10

[0166] A solid ion conductor compound was obtained in the same manner as in Example 1, except that YbCl3, a lanthanum precursor compound, and LiBr, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0167] Example 11

[0168] A solid ion conductor compound was obtained in the same manner as in Example 1, except that HoBr3, a lanthanum precursor compound, and LiCl, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:2.75, and the compound was molded to prepare a pellet.

[0169] Example 12

[0170] HoBr3, a lanthanum precursor compound, and LiCl and NaCl, lithium precursor compounds, were fed into a planetary ball mill in a stoichiometric ratio of 1:2.95:0.05 in a dry room with a dew point of -60°C. Zirconia (YSZ) balls were then introduced, and the mixture was ground and mixed at 700 rpm for 10 minutes in an Ar atmosphere, followed by a 5-minute rest period. This cycle was repeated for 72 hours to obtain a mixture. After grinding the obtained mixture, it was crystallized by heat treatment at 260°C for 5 hours to obtain a solid ion conductor compound with the composition listed in Table 1 below. Subsequently, for XRD analysis, the obtained solid ion conductor compound was pressed at a uniaxial pressure of 350 MPa to prepare a pellet with a thickness of approximately 800 mm and a diameter of approximately 13 mm.

[0171] Example 13

[0172] A solid ion conductor compound was obtained in the same manner as in Example 1, except that LuCl3, a lanthanum precursor compound, and LiBr, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0173] Comparative Example 1

[0174] HoCl3, a lanthanum precursor compound, and LiCl, a lithium precursor compound, were introduced into a planetary ball mill in a stoichiometric ratio of 1:3 inside a glove box under an Ar atmosphere. Zirconia (YSZ) balls were then introduced, and the mixture was ground and mixed at 700 rpm under an Ar atmosphere for 10 minutes, followed by a 5-minute rest period. This cycle was repeated for 24 hours to obtain a mixture. The obtained mixture was placed in a furnace and calcined at a temperature of 260°C for 5 hours to obtain a crystallized solid ion conductor compound with the composition listed in Table 1 below. Subsequently, the obtained solid ion conductor compound was pressed at a uniaxial pressure of 200 MPa for XRD analysis to prepare a pellet with a thickness of approximately 10 mm and a diameter of approximately 13 mm.

[0175] Comparative Example 2

[0176] A solid ion conductor compound was obtained in the same manner as in Comparative Example 1, except that HoBr3, a lanthanum precursor compound, and LiBr, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0177] Comparative Example 3

[0178] A solid ion conductor compound was obtained in the same manner as in Comparative Example 1, except that LuCl3, a lanthanum precursor compound, and LiCl, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0179] Comparative Example 4

[0180] A solid ion conductor compound was obtained in the same manner as in Comparative Example 1, except that LuBr3, a lanthanum precursor compound, and LiBr, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0181] Comparative Example 5

[0182] A solid ion conductor compound was obtained in the same manner as in Comparative Example 1, except that TmCl3, a lanthanum precursor compound, and LiCl, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0183] Comparative Example 6

[0184] A solid ion conductor compound was obtained in the same manner as in Comparative Example 1, except that TmBr3, a lanthanum precursor compound, and LiBr, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0185] Comparative Example 7

[0186] A solid ion conductor compound was obtained in the same manner as in Comparative Example 1, except that YbCl3, a lanthanum precursor compound, and LiCl, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0187] Comparative Example 8

[0188] A solid ion conductor compound was obtained in the same manner as in Comparative Example 1, except that YbBr3, a lanthanum precursor compound, and LiBr, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0189] Comparative Example 9

[0190] A solid ion conductor compound was obtained in the same manner as in Comparative Example 1, except that TbCl3, a lanthanum precursor compound, and LiCl, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0191] Comparative Example 10

[0192] A solid ion conductor compound was obtained in the same manner as in Comparative Example 1, except that InCl3, a lanthanum precursor compound, and LiCl, a lithium precursor compound, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0193] Comparative Example 11

[0194] A solid ion conductor compound was obtained in the same manner as in Comparative Example 1, except that the yttrium precursor compound YCl3 and the lithium precursor compound LiCl were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0195] Comparative Example 12

[0196] A solid ion conductor compound was obtained in the same manner as in Comparative Example 1, except that an indium precursor compound, InCl3, and a lithium precursor compound, LiBr, were mixed in a stoichiometric ratio of 1:3, and the compound was molded to prepare a pellet.

[0197] (Manufacturing of all-solid-state secondary batteries)

[0198] Example 14

[0199] (Anode layer manufacturing)

[0200] LiNi as a positive electrode active material 0.8 Co 0.15 Mn 0.05 O2(NCM) was prepared. As a solid electrolyte, a powder was prepared by grinding the pellets of the solid ion conductor compound prepared in Example 1. Carbon nanofibers (CNF) were prepared as a conductive agent. These materials were mixed in a weight ratio of cathode active material : solid electrolyte : conductive agent = 65 : 35 : 5 to prepare a cathode composite powder.

[0201] (Preparation of solid electrolyte powder)

[0202] The pellets prepared in Example 1 were ground using an agate mortar to prepare solid electrolyte powder.

[0203] (Cathode layer manufacturing)

[0204] A metal lithium foil with a thickness of 30 μm was prepared as the cathode.

[0205] (Manufacturing of all-solid-state secondary batteries)

[0206] After stacking a cathode layer, solid electrolyte powder, and anode mixture powder in sequence on a SUS lower electrode, the solid electrolyte powder and anode mixture powder were pressed with a uniaxial pressure of 350 MPa (diameter 13 mm, 4 t) to prepare an all-solid-state secondary battery in the form of a pellet with a diameter of approximately 13 mm.

[0207] Comparative Example 13

[0208] An all-solid-state secondary battery was prepared in the same manner as in Example 14, except that the solid ion-conducting compound obtained in Comparative Example 10 was used as the solid electrolyte.

[0209] (Fabrication of lithium symmetric cells)

[0210] Example 15

[0211] A lithium substitute cell was fabricated by attaching a Cu foil coated with 20 m Li to both sides of the pellet obtained in Example 13 and compressing it at 250 MPa using CIP.

[0212] Comparative Example 14

[0213] A symmetric cell was fabricated in the same manner as in Example 15, except that the pellet obtained in Comparative Example 13 was used instead of the pellet obtained in Example 12.

[0214] Evaluation Example 1: X-ray Diffraction Experiment

[0215] The solid ion conductor compounds prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were ground using an agate mortar to prepare powder, and the powder XRD spectra were measured, and the results are shown in Table 1 and Figure 1 below.

[0216] When the mole fraction (z-value) of Br was 2, a diffraction peak was observed at a diffraction angle 2θ = 40° to 44°, but when it was 3 or greater, no diffraction peak was observed at the same diffraction angle 2θ = 40° to 44°. This suggests that when the mole fraction of Br is 3 or greater, that is, when the mole fraction of Br is equal to or greater than that of Cl, it contains an amorphous phase.

[0217] Evaluation Example 2: Ionic Conductivity Measurement

[0218] After preparing powders by grinding the solid ion conductor compounds prepared in Examples 1 to 13 and Comparative Examples 1 to 12 using an agate mortar, 300 mg of the powder was 4 ton / cm² 2 A pellet specimen with a thickness of approximately 700 μm and a diameter of approximately 13 mm was prepared by pressing under a pressure of 2 minutes. A symmetry cell was prepared by placing gold (Au) electrodes with a thickness of 10 nm and a diameter of 13 mm on each side of the prepared specimen. The preparation of the symmetry cell was carried out in a glover box under an Ar atmosphere.

[0219] For specimens with gold electrodes placed on both sides, the impedance of the pellet was measured using the 2-probe method with an impedance analyzer (Material Mates 7260 impedance analyzer). The frequency range was 1 Hz to 1 MHz, and the amplitude voltage was 10 mV. Measurements were taken at 20°C in an Ar atmosphere. The resistance value was determined from the arc of the Nyquist plot of the impedance measurement results, and the ionic conductivity was calculated by considering the area and thickness of the specimen. The measurement results are shown in Table 1 below, and the ionic conductivity according to temperature for Example 1 and Comparative Examples 1 and 2 was measured and is shown in Figure 2.

[0220] Referring to FIG. 2, from a low temperature (-20℃) to a high temperature (40℃) 10 -4 Scm -1It was confirmed that the ionic conductivity of was maintained.

[0221] furtherance Ionic conductivity (mScm) -1 ) furtherance Ionic conductivity (mScm) -1 ) Example 1 Li3HoCl3Br3 5.9E-04 Comparative Example 1 Li3HoCl6 1.7E-04 Example 2 Li3HoCl2Br4 5.9E-04 Comparative Example 2 Li3HoBr6 8.7E-05 Example 3 Li3HoCl1Br5 4.8E-04 Comparative Example 3 Li3LuCl6 5.2E-05 Example 4 Li3HoCl4Br2 5.1E-04 Comparative Example 4 Li3LuBr6 3.2E-05 Example 5 Li3HoCl5Br1 4.8E-04 Comparative Example 5 Li3TmCl6 8.3E-05 Example 6 Li3LuCl2Br4 5.0E-04 Comparative Example 6 Li3TmBr6 7.2E-05 Example 7 Li3LuCl5Br1 2.1E-04 Comparative Example 7 Li3YbCl6 4.6E-05 Example 8 Li3TmCl3Br3 3.2E-04 Comparative Example 8 Li3YbBr6 5.0E-05 Example 9 Li3TmCl2Br4 4.0E-04 Comparative Example 9 Li3TbCl6 6.9E-07 Example 10 Li3YbCl3Br3 2.0E-04 Comparative Example 10 Li3InCl6 5.8E-05 Example 11 Li 2.75 HoCl 2.75 Br3 5.3E-04 Comparative Example 11 Li3YCl6 1.2E-04 Example 12 Li 2.95 Na 0.05 HoCl3Br3 1.3E-03 Comparative Example 12 Li3InCl3Br3 1.4E-04 Example 13 Li3LuCl3Br3 2.8E-04

[0222] Evaluation Example 3: Initial Charge / Discharge Test

[0223] The charge and discharge characteristics of the all-solid-state secondary batteries prepared in Example 14 and Comparative Example 13 were evaluated by the following charge and discharge test.

[0224] The first cycle of the charge-discharge test was charged with a constant current of 0.05C and a constant voltage of 4.0V until the battery voltage reached 4.0V, and then discharged with a constant current of 0.05C until the battery voltage reached 2.0V.

[0225] The initial charge / discharge curve is shown in Fig. 3.

[0226] Referring to Fig. 3, it was confirmed that the charging and discharging cycles of Example 14 proceeded stably.

[0227] Evaluation Example 4: Evaluation of Limiting Current Density

[0228] After preparing a powder by grinding the solid ion conductor compounds prepared in Example 1 and Comparative Example 1 using an agate mortar, 300 mg of the powder was 4 ton / cm² 2 A pellet specimen with a thickness of approximately 700 μm and a diameter of approximately 13 mm was prepared by pressing for 2 minutes under a pressure of [a specific pressure]. A symmetry cell was prepared by placing lithium foil with a thickness of 20 μm and a diameter of 8 mm on each side of the prepared specimen using a cold isotactic press of 250 MPa. The preparation of the symmetry cell was carried out in a glover box under an Ar atmosphere.

[0229] For specimens with lithium foil electrodes placed on both sides, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 mAcm -2 Charge and discharge were performed at each current density, and the time-voltage curves at each current density are shown in Fig. 4.

[0230] Referring to Fig. 4, it was confirmed that the symmetric cell containing the solid ion-conducting compound of Comparative Example 1 was short-circuited at a current density of 0.3 mA cm⁻², whereas in contrast, the symmetric cell containing the solid ion-conducting compound of Example 1 was short-circuited at 0.5 mA -2 It was confirmed that charging and discharging proceeded smoothly at the current density.

[0231] Evaluation Example 5: DSC Analysis

[0232] 10 mg of each of the solid ion conductor compounds synthesized in Example 1, Comparative Example 1, and Comparative Example 2 were sampled, and their crystallization temperature and melting point were analyzed using differential scanning calorimetry, and the results are provided in Fig. 6.

[0233] Referring to Fig. 6, the solid ion conductor compound of Example 1 (Li3HoCl3Br3) had crystallization temperatures of 90°C and 135°C and a melting point of 168°C, the solid ion conductor compound of Comparative Example 1 (Li3HoCl6) had a crystallization temperature of 171°C and a melting point of 229°C, and the solid ion conductor compound of Comparative Example 2 (Li3HoBr6) had a crystallization temperature of 117°C and a melting point of 186°C. It can be seen that the solid ion conductor compound of Example 1 has a lower crystallization temperature compared to the solid ion conductor compounds of Comparative Examples 1 and 2, which contain one type of halogen element, because it contains two types of halogen elements. As a result, synthesis is possible at low temperatures, thereby improving processability.

[0234] Evaluation Example 6: Cycle Stability Evaluation

[0235] The stability of the lithium anode was confirmed by observing the change in voltage according to the charge-discharge cycle of the lithium symmetrical cell fabricated in Example 15 and Comparative Example 14, and the results are presented in FIG. 7.

[0236] Referring to Fig. 7, in the case of the cell of Comparative Example 14, a short circuit occurred during the initial operation of the cell, causing the operation of the cell to stop, while in the case of the cell of Example 15, it was confirmed that it operated stably even after more than 450 cycles of operation.

[0237] Although the above description refers to the embodiments illustrated in the drawings, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true technical scope of protection of the present invention should be determined by the technical spirit of the appended claims.

Claims

Claim 1 Solid ionic conductor compound represented by the following chemical formula 1: <Chemical Formula 1>Li x M1 a M2 b Cl y Br z M1 comprises one or more metal elements selected from alkali metals, alkaline earth metals, and transition metals, and M2 is one or more lanthanide elements selected from La, Ce, Pr, Nd, Pm, Eu, Tb, Ho, Er, Tm, Yb, and Lu, and the solid ion conductor compound comprises a crystal structure belonging to the C2 / m space group and the P3m1 space group, and 0 <x<3.5, 0≤a<1.5, 0<b<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5이다. Claim 2 In claim 1, the solid ion conductor compound comprises a layered rock salt crystal structure. Claim 3 delete Claim 4 delete Claim 5 In claim 1, the solid ion conductor compound is a solid ion conductor compound that does not have a diffraction peak at a diffraction angle 2θ = 40° to 44° in an XRD spectrum using CuKα lines. Claim 6 delete Claim 7 A solid ion-conducting compound according to claim 1, wherein M2 is one or more lanthanide elements selected from La, Ho, Tm, Yb, and Lu. Claim 8 A solid ion conductor compound according to claim 1, wherein a portion of Li in the above chemical formula 1 is substituted with M1. Claim 9 A solid ion-conducting compound according to claim 1, wherein M1 comprises Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, Al, Ga, In, Ti, Ge, Sn, Pb, Sb, Bi, Po, or a combination thereof. Claim 10 A solid ion conductor compound according to claim 1, wherein in the above chemical formula 1, 1≤y≤5 and 1≤z≤5. Claim 11 In claim 1, among the above chemical formula 1, 2.5 <x<3.5, 2<y<5이고, 5.4<x+y<6.6인, 고체이온전도체 화합물. Claim 12 In claim 1, a solid ion conductor compound having y=z in the above chemical formula 1. Claim 13 In claim 1, 1 of the above chemical formula 1 <z<6인, 고체이온전도체 화합물. Claim 14 In claim 1, the above chemical formula 1 is a solid ion conductor compound represented by the following chemical formula 2: <Chemical Formula 2>Li 3-a' M11 a' M12 b Cl y Br z In the above Chemical Formula 2, M11 refers to the description of M1 in Claim 1, M12 refers to the description of M2 in Claim 1, 0≤a'<1.5, 0 <b<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5이다. Claim 15 제1항에 있어서,Li x HoCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x CeCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x PrCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x NdCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x PmCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x EuCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x TbCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x ErCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x TmCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x YbCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5), 및 Li x LuCl y Br z (0<x<3.5, 0<y<6, 0<z<6, 0.166<y / z≤5); 및Li x M1 a HoCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a CeCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a PrCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a NdCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a PmCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a EuCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a TbCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a ErCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a TmCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), Li x M1 a YbCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5), 및 Li x M1 a LuCl y Br z (0<x<3.5, 0≤a<1.5, 0<y<6, 0<z<6, 0.166<y / z≤5);중에서 선택되고,M1은 알칼리금속, 알칼리토금속, 전이금속 중에서 선택되는 1종 이상의 금속 원소를 포함하는, 고체이온전도체 화합물. Claim 16 A solid electrolyte comprising a solid ion-conducting compound according to any one of claims 1, 2, 5 and 7 through 15. Claim 17 An electrochemical cell comprising: an anode layer including an anode active material layer; a cathode layer including a cathode active material layer; and an electrolyte layer disposed between the anode layer and the cathode layer, wherein the anode active material layer, the electrolyte layer, or a combination thereof comprises a solid ion conductor compound according to any one of claims 1, 2, 5 and 7 to 15. Claim 18 In claim 17, the electrochemical cell is an all-solid-state secondary battery. Claim 19 A method for preparing a solid ion conductor compound according to any one of claims 1, 2, 5 and 7 to 15, comprising: a step of preparing a mixture by mixing a lithium precursor and a precursor containing a lanthanide element; and a step of reacting said mixture in a solid phase. Claim 20 A method for preparing a solid ion conductor compound according to claim 19, wherein the step of reacting the mixture in a solid state comprises performing ball mill mixing of the mixture in a dry and inert atmosphere. Claim 21 A method for preparing a solid ion conductor compound according to claim 19, further comprising the step of heat treating at 200°C to 300°C for 4 to 6 hours following the step of reacting the above mixture in a solid state.

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