Solid ion conductor, solid electrolyte and electrochemical device including the same, and method of preparing the solid ion conductor

Abstract

A solid ion conductor, a solid electrolyte and an electrochemical device comprising the same, and a method for manufacturing the solid ion conductor are disclosed. The solid ion conductor may include a compound represented by the following chemical formula 1, having an orthorhombic crystal structure and belonging to the Pnma space group or the Pnma-like space group: Li3-xAxLuCl6-yBy In the above chemical formula 1, A, B, x, and y are each as described in the specification.

Description

Technology Field

[0001] The invention relates to a solid ion conductor, a solid electrolyte and an electrochemical device including the same, and a method for manufacturing the solid ion conductor. Background Technology

[0002] Electrochemical devices, such as all-solid-state secondary batteries, employ materials with high energy density, such as lithium metal, for the negative electrode to achieve high energy density, and use solid-state ion conductors as the electrolyte for safe operation.

[0003] Oxide-based and sulfide-based solid ion conductors are widely studied as solid ion conductors depending on the type of anion. However, oxide-based solid ion conductors require additional processes to ensure good interfacial adhesion with the cathode and / or anode. During this process, side reactions with the cathode and / or anode materials at the interface may occur, which can inhibit lithium ion migration. Sulfide-based solid ion conductors may react with the cathode and / or anode materials, leading to interfacial decomposition.

[0004] Therefore, there is a need for a solid ion conductor having improved ion conductivity and low interfacial resistance, a solid electrolyte and electrochemical device containing the same, and a method for manufacturing the solid ion conductor. The problem to be solved

[0005] One aspect is to provide a solid ion conductor having enhanced ion conductivity and low interfacial resistance.

[0006] Another aspect is to provide a solid electrolyte comprising the above-mentioned solid ion conductor.

[0007] Another aspect is to provide an electrochemical device comprising the above-mentioned solid ion conductor.

[0008] Another aspect is to provide a method for manufacturing the above-mentioned solid ion conductor. means of solving the problem

[0009] Depending on one aspect,

[0010] A solid ion conductor is provided, comprising a compound represented by the following chemical formula 1, having an orthorhombic crystal structure, and belonging to the Pnma space group or the Pnma-like space group:

[0011] <Chemical Formula 1>

[0012] Li 3-x A x LuCl 6-y B y

[0013] In the above formula,

[0014] A can be a monovalent cation having an ionic radius of 76 pm or more, and

[0015] B can be a monovalent anion, and

[0016] 0 ≤ x ≤ 0.1, 0 ≤ y ≤ 1, and x + y > 0.

[0017] The above A is Na + , K + , Rb + , Cs + , Ag + , Au + , Cu + , Hg + , Tl + , Or it could be a combination of these.

[0018] The above B is Br - , I - , or a combination of these.

[0019] The above compound is Li 2.95 Na 0.05 LuCl6, Li 2.95 K 0.05 LuCl6, Li 2.95 Rb 0.05 LuCl6, Li 2.95 Cs 0.05 LuCl6, Li 2.95 Ag 0.05 LuCl6, Li 2.95 Au 0.05 LuCl6, Li 2.95 Cu0.05 LuCl6, Li 2.95 Hg 0.05 LuCl6, Li 2.95 Soil 0.05 LuCl6, Li3LuCl5Br, Li3LuCl5I, Li 2.95 On 0.05 LuCl5Br, Li 2.95 K 0.05 LuCl5Br, Li 2.95 Number 0.05 LuCl5Br, Li 2.95 Cs 0.05 LuCl5Br, Li 2.95 Ag 0.05 LuCl5Br, Li 2.95 Oh! 0.05 LuCl5Br, Li 2.95 I will 0.05 LuCl5Br, Li 2.95 Hg 0.05 LuCl5Br, Li 2.95 Soil 0.05 LuCl5Br, Li 2.95 On 0.05 LuCl5I, Li 2.95 K 0.05 LuCl5I, Li 2.95 Number 0.05 LuCl5I, Li 2.95 Cs 0.05 LuCl5I, Li 2.95 Ag 0.05 LuCl5I, Li 2.95 Oh! 0.05 LuCl5I, Li 2.95 I will 0.05 LuCl5I, Li 2.95 Hg 0.05 LuCl5I, Li 2.95 Soil 0.05 LuCl5I, or a combination of these.

[0020] The Pnma space group refers to a space group having an n-glide plane perpendicular to the x-axis, a mirror plane perpendicular to the y-axis, and an a-glide plane perpendicular to the z-axis. The definition of the crystal structure of the compound having the Pnma space group is as follows.

[0021] The above compound may have a centrosymmetric structure having different lengths in the x-axis, y-axis, and z-axis directions, each axis being perpendicular to the others, and having 8 inversion points per unit cell.

[0022] The above compound has 4 screw axes per unit cell along each unit cell direction and may have 2 planes per unit cell in a direction perpendicular to each unit cell axis.

[0023] In the above compound, LuCl6 or LiX6 (X = Cl, Br) octahedra are positioned in an edge-sharing manner in an orthorhombic crystal structure, and A cation can be located at the Li site.

[0024] The above compound may have three-dimensionally connected lithium ion transport channels within an orthorhombic crystal structure.

[0025] The above compound may have lithium ion transport channels extended in the x-axis, y-axis, and z-axis directions by spatial distribution according to the ionic radius of the A cation or the B anion within an orthorhombic crystal structure.

[0026] One or more peaks may appear in the region of 29° to 32°, the region of 33° to 35°, or the region of 34° to 37°, which is the diffraction angle 2θ obtained by the XRD spectrum using CuKα-rays of the above compound.

[0027] The above compound can be shifted to the left relative to the Li3LuCl6 compound in the diffraction angle 2θ region where the above peak appears.

[0028] The above solid ion conductor is 1 x 10⁻⁶ at 25℃ -1 mS·cm -1 It can have an ionic conductivity greater than that.

[0029] The above solid ion conductor is a lithium symmetric cell disposed between lithium metals at 25°C, 1 Hz to 10 6 The interfacial resistance between the solid ion conductor and the lithium metal, measured in the impedance spectrum in the frequency range of Hz, is 500 Ω·cm 2 It may be less than.

[0030] Depending on other aspects of work,

[0031] A solid electrolyte comprising the aforementioned solid ion conductor is provided:

[0032] Depending on another aspect of work,

[0033] It includes an anode layer, a cathode layer, and a solid electrolyte layer,

[0034] An electrochemical device comprising the aforementioned solid electrolyte is provided.

[0035] The above solid electrolyte may be included in the solid electrolyte layer, the anode layer, the cathode layer, the anode layer protective film, the cathode layer protective film, or a combination thereof.

[0036] The above solid electrolyte may have a thickness of 10 micrometers (μm) to 1 millimeter (mm) and may be a single layer or multilayer structure.

[0037] The above electrochemical device may be an all-solid-state secondary battery or a metal-air battery.

[0038] Depending on another aspect of work,

[0039] A step of providing a precursor mixture for forming a solid ion conductor; and

[0040] A method for manufacturing a solid ion conductor is provided, comprising the step of performing mechanical milling on the above mixture to manufacture a solid ion conductor comprising a compound represented by the following chemical formula 1 and having a crystal structure of a Pnma space group or a Pnma-like space group:

[0041] <Chemical Formula 1>

[0042] Li 3-x A x LuCl 6-y B y

[0043] In the above formula,

[0044] A can be a monovalent cation having an ionic radius of 76 pm or more, and

[0045] B can be a monovalent anion, and

[0046] 0 ≤ x ≤ 0.1, 0 ≤ y ≤ 1, and x + y > 0. Effects of the invention

[0047] A solid ion conductor according to one aspect comprises a compound having an orthorhombic crystal structure, belonging to a Pnma space group or a Pnma-like space group, and having a monovalent cation or / and monovalent anion substituted at a Li site or / and a Cl site. The solid ion conductor may have enhanced ion conductivity and reduced interfacial resistance.

[0048] The above solid ion conductor may be included in the solid electrolyte layer, anode layer, cathode layer, anode layer protective film, or cathode layer protective film of an electrochemical device, for example, an all-solid-state secondary battery or a metal-air battery. Brief explanation of the drawing

[0049] FIG. 1 is a schematic diagram showing the crystal structure of a solid ion conductor compound according to one embodiment. FIG. 2 is a schematic diagram showing that lithium ion transport channels are connected in three dimensions within the crystal structure of a solid ion conductor compound according to one embodiment. FIG. 3a is the result of measuring the XRD spectrum using CuKα rays for solid ion conductors prepared according to Example 4 and Comparative Examples 1 to 3; FIG. 3b is the result of measuring the XRD spectrum using CuKα rays for solid ion conductors prepared according to Example 1 and Comparative Example 1. FIGS. 4 to 6 are cross-sectional views of an all-solid-state secondary battery according to one embodiment. Specific details for implementing the invention

[0050] Hereinafter, a solid ion conductor according to one embodiment of the present invention, a solid electrolyte and an electrochemical device including the same, and a method for manufacturing the solid ion conductor will be described in detail with reference to the attached drawings. The following is presented as an example and is not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0051] In this specification, expressions such as "at least one," "one or more," or "one or more" preceding components are to supplement the list of all components and do not mean that they are to supplement the individual components described above. In this specification, the term "combination" includes mixtures, alloys, reaction products, etc., unless specifically stated otherwise.

[0052] In this specification, the term "includes" means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0053] In this specification, terms such as “first,” “second,” etc., are used to distinguish one element from another without indicating order, quantity, or importance. Unless otherwise indicated in this specification or clearly contradicted by the context, they should be interpreted to include both singular and plural forms. “Or” means “and / or” unless otherwise specified.

[0054] Throughout this specification, terms such as “one embodiment,” “an embodiment,” etc., mean that specific elements described in relation to an embodiment are included in at least one embodiment described herein and may or may not be present in other embodiments. Furthermore, it should be understood that the described elements may be combined in any appropriate manner in various embodiments.

[0055] Unless otherwise defined, technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which this application pertains. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, in the event that terms in this specification contradict or conflict with terms in the incorporated reference, the terms from this specification shall prevail over the conflicting terms in the incorporated reference.

[0056] Although specific embodiments and implementations 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 and amendments are intended to include all such alternatives, variations, improvements, and substantial equivalents.

[0057] Oxide-based and sulfide-based solid ion conductors are being widely studied as solid ion conductors.

[0058] Although the above oxide-based solid ion conductor exhibits excellent chemical stability, interfacial adhesion with the electrode is difficult when used as a solid electrolyte due to its brittle and rigid characteristics. Additional processes, such as sintering or pressurization, are required to achieve good interfacial adhesion between the oxide-based solid ion conductor and the electrode. During these processes, the oxide-based solid ion conductor may deform or react with the electrode material, which may reduce ion mobility at the interface.

[0059] The above-mentioned sulfide-based solid ion conductor exhibits excellent ion conductivity but suffers from reduced chemical and electrochemical stability. Since the sulfide-based solid ion conductor can react with electrode materials and decompose at the interface, a protective film is required at the interface with the electrode.

[0060] Based on these points, the inventors of the present invention propose a solid ion conductor that facilitates ion movement, a solid electrolyte and an electrochemical device comprising the same, and a method for manufacturing the solid ion conductor.

[0061] Hereinafter, a solid ion conductor, a solid electrolyte and an electrochemical device including the same, and a method for manufacturing the solid ion conductor are described in detail.

[0062] Solid ion conductors

[0063] A solid ion conductor according to one embodiment may include a compound represented by the following chemical formula 1, having an orthorhombic crystal structure, and belonging to the Pnma space group or the Pnma-like space group:

[0064] <Chemical Formula 1>

[0065] Li 3-x A x LuCl 6-y B y

[0066] In the above formula,

[0067] A can be a monovalent cation having an ionic radius of 76 pm or more, and

[0068] B can be a monovalent anion, and

[0069] 0 ≤ x ≤ 0.1, 0 ≤ y ≤ 1, and x + y > 0.

[0070] The above solid ion conductor comprises a halide compound having a structure in which a cation A is substituted at a lithium site or / and a chlorine site is substituted with a chlorine anion B. Within the range of types and content of the cation A or / and the chlorine anion B, the structure of the halide compound can be maintained and can be easily substituted with the cation A or / and the chlorine anion B within the structure.

[0071] A solid ion conductor comprising a compound having an orthorhombic crystal structure and belonging to the Pnma space group or a Pnma-like space group maintains structural stability during charging and discharging, thereby reducing the likelihood of decomposition at the interface even when reacting with the electrode. The solid ion conductor may possess excellent lithium ion conductivity and improved electrochemical stability with respect to the electrode, e.g., lithium metal. For example, a solid ion conductor comprising a compound having an orthorhombic crystal structure and a Pnma space group or a Pnma-like space group crystal structure may have improved thermodynamic reduction stability with respect to lithium metal by approximately 1.7 V or more compared to a solid ion conductor comprising a Li3InCl6 compound. The interfacial resistance with respect to the electrode may be reduced in the solid ion conductor during charging and discharging.

[0072] The above A is Na + , K + , Rb + , Cs + , Ag + , Au + , Cu + , Hg + , Tl + , or a combination thereof. For example, the above A is Na + , Au + , Cu + , or a combination thereof. The above B is Br - , I - , or a combination of these.

[0073] For example, the above compound may include a compound represented by the following chemical formula 2 or chemical formula 3:

[0074] <Chemical Formula 2>

[0075] Li 3-x A x LuCl6

[0076] In the above formula,

[0077] A is Na + , K + , Rb + , Cs + , Ag + , Au + , Cu + , Hg + , Tl + , or a combination of these,

[0078] 0 < x ≤ 0.1 may be possible.

[0079] <Chemical Formula 3>

[0080] Li3LuCl 6-y B y

[0081] In the above formula,

[0082] B is Br - , I - , or a combination of these,

[0083] 0 < y ≤ 1 can be true.

[0084] For example, in the above chemical formula 1, A is Na + , K + , Rb + , Cs + , Ag + , Au + , Cu + , Hg + , Tl + , or a combination thereof, and B is Br - , I - It may include compounds that are , or a combination thereof, and in which 0 < x ≤ 0.1 and 0 < y ≤ 1.

[0085] the above compound is Li 2.95 On 0.05 LuCl6, Li 2.95 K 0.05 LuCl6, Li 2.95 Number 0.05 LuCl6, Li 2.95 Cs 0.05 LuCl6, Li 2.95 Ag 0.05 LuCl6, Li 2.95 Oh! 0.05 LuCl6, Li 2.95 I will 0.05 LuCl6, Li 2.95 Hg 0.05 LuCl6, Li 2.95 Soil 0.05 LuCl6, Li3LuCl5Br, Li3LuCl5I, Li 2.95 On 0.05 LuCl5Br, Li 2.95 K 0.05 LuCl5Br, Li 2.95 Number 0.05 LuCl5Br, Li 2.95 Cs 0.05 LuCl5Br, Li 2.95 Ag 0.05 LuCl5Br, Li 2.95 Oh! 0.05 LuCl5Br, Li 2.95 I will 0.05 LuCl5Br, Li 2.95 Hg 0.05 LuCl5Br, Li 2.95 Soil 0.05 LuCl5Br, Li 2.95 On 0.05 LuCl5I, Li 2.95 K 0.05 LuCl5I, Li 2.95 Number 0.05 LuCl5I, Li 2.95 Cs 0.05 LuCl5I, Li 2.95 Ag 0.05 LuCl5I, Li 2.95 Oh! 0.05 LuCl5I, Li 2.95 I will 0.05 LuCl5I, Li 2.95 Hg0.05 LuCl5I, Li 2.95 Tl 0.05 It may be LuCl5I, or a combination thereof. For example, the compound is Li 2.95 Na 0.05 LuCl6, Li 2.95 K 0.05 LuCl6, Li 2.95 Rb 0.05 LuCl6, Li 2.95 Cs 0.05 LuCl6, Li 2.95 Ag 0.05 LuCl6, Li 2.95 Au 0.05 LuCl6, Li 2.95 Cu 0.05 LuCl6, Li3LuCl5Br, Li 2.95 Na 0.05 LuCl5Br, Li 2.95 K 0.05 LuCl5Br, Li 2.95 Rb 0.05 LuCl5Br, Li 2.95 Cs 0.05 LuCl5Br, Li 2.95 Ag0 .05 LuCl5Br, Li 2.95 Au 0.05 LuCl5Br, Li 2.95 Cu 0.05 It may be LuCl5Br, or a combination thereof. For example, the above compound is Li 2.95 Na 0.05 LuCl6, Li2 .95 Ag 0.05 LuCl6, Li 2.95 Au 0.05 LuCl6, Li 2.95 Cu 0.05 LuCl6, Li3LuCl5Br, Li2 .95 Na 0.05 LuCl5Br, Li 2.95 Ag 0.05 LuCl5Br, Li 2.95Au0.05 LuCl5Br, Li 2.95 Cu 0.05It may be LuCl5Br, or a combination thereof. For example, the above compound is Li 2.95 Na 0.05 LuCl6, Li 2.95 Ag 0.05 LuCl6, Li 2.95 Cu 0.05 LuCl6, Li3LuCl5Br, Li 2.95 Na 0.05 LuCl5Br, Li 2.95 Ag 0.05 LuCl5Br, Li 2.95 Cu 0.05 It may be LuCl5Br, or a combination thereof. For example, the above compound is Li 2.95 Na 0.05 LuCl6, Li 2.95 Ag 0.05 LuCl6, Li 2.95 Cu 0.05 It may be LuCl6, Li3LuCl5Br, or a combination thereof.

[0086] FIG. 1 is a schematic diagram showing the crystal structure of a compound of a solid ion conductor according to one embodiment.

[0087] As shown in FIG. 1, the compound of the solid ion conductor according to one embodiment has a structure in which the x-axis, y-axis, and z-axis directions have different lengths and each axis is perpendicular to the others. In the crystal structure of the compound, Li cations or A cations may be located around LuCl6 octahedra. Although not shown in the drawing, Li cations (or A cations) may form LiCl6 octahedra with Cl anions. LuCl6 or LiX6 (X = Cl, Br) octahedra may be located in an edge-sharing manner, and A cations may be located at Li sites. Alternatively, LuCl6 octahedra may be located in a manner where they do not share edges with each other, and LiX6 (X = Cl, Br) octahedra may be located in a manner where they share edges with each other.

[0088] A solid ion conductor according to one embodiment may have a Pnma space group structure which is a centrosymmetric structure having 8 inversion points per unit cell. The compound may have 4 screw axes per unit cell along each unit cell direction and 2 planes per unit cell in a direction perpendicular to each unit cell axis.

[0089] Alternatively, the solid ion conductor may have a Pnma-like space group structure. In this specification, a "Pnma-like space group" structure refers to a structure synthesized by substituting a small amount of elements into a Pnma space group structure, and is a space group structure having a peak pattern similar to the peak pattern of the XRD spectrum using CuKα lines of the Pnma space group structure in the XRD spectrum. For example, the peak pattern of the Pnma-like space group structure appearing in regions where the diffraction angle 2θ obtained by the XRD spectrum using CuKα lines is 29° to 32°, 33° to 35°, 34° to 37°, etc., may be similar to the peak pattern of the Pnma space group structure. A solid ion conductor containing such a Pnma space group or a compound having a Pnma-like space group structure maintains structural stability during charging and discharging, so the possibility of decomposition at the interface is reduced even if it reacts with the electrode. The above solid ion conductor can have excellent lithium ion conductivity and improved electrochemical stability with an electrode, for example, lithium metal.

[0090] FIG. 2 is a schematic diagram showing that lithium ion transport channels are connected in three dimensions within the crystal structure of a solid ion conductor compound according to one embodiment.

[0091] As shown in FIG. 2, the compound of the solid ion conductor according to one embodiment indicates that lithium ion transport channels are connected in a three-dimensional direction between LuCl6 octahedrons within an orthorhombic crystal structure. The compound may have lithium ion transport channels that are evenly extended in the x-axis, y-axis, and z-axis directions according to the spatial distribution of the ionic radii of the A cation or the B anion between the LuCl6 octahedrons within the orthorhombic crystal structure. The compound may have enhanced ion conductivity because lithium ions can move freely within the orthorhombic crystal structure during charging and discharging.

[0092] One or more peaks may appear in the region of 29° to 32°, the region of 33° to 35°, or the region of 34° to 37° for the diffraction angle 2θ obtained by the XRD spectrum using CuKα rays of the above compound. For example, one or more peaks may appear in the region of 29.5° to 32°, the region of 33° to 34.5°, and the region of 34.5° to 36.3° for the diffraction angle 2θ obtained by the XRD spectrum using CuKα rays of the above compound.

[0093] The above compound may be shifted to the left relative to the Li3LuCl6 compound in the diffraction angle 2θ region where the peak appears. The volume of the above compound may be increased by 0.1% to 5% relative to the Li3LuCl6 compound.

[0094] The above solid ion conductor is 1 x 10⁻⁶ at 25℃ -1 mS·cm -1 It can have an ionic conductivity greater than or equal to 1.1 x 10⁻⁶ at 25°C. For example, the solid ionic conductor has 1.1 x 10⁻⁶ at 25°C. -1 mS·cm -1 or more than 1.2 x 10 -1 mS·cm -1 or more than 1.3 x 10 -1 mS·cm -1 or more than 1.4 x 10 -1mS·cm -1 or more than 1.5 x 10 -1 mS·cm -1 It can have an ionic conductivity greater than that.

[0095] The above solid ion conductor is a lithium symmetric cell disposed between lithium metals at 25°C, 1 Hz to 10 6 The interfacial resistance between the solid ion conductor and the lithium metal, measured in the impedance spectrum in the frequency range of Hz, is 500 Ω·cm 2 It may be less than or equal to. For example, the solid ion conductor is 25°C, 1 Hz to 10 of a lithium symmetric cell disposed between lithium metals. 6 The interfacial resistance between the solid ion conductor and the lithium metal, measured in the impedance spectrum in the frequency range of Hz, is 490 Ω·cm 2 Less than or equal to 480 Ω·cm 2 Less than or equal to 470 Ω·cm 2 or less than or equal to 460 Ω·cm 2 Less than or equal to 450 Ω·cm 2 Less than or equal to 440 Ω·cm 2 It may be less than.

[0096] Solid Electrolytes and Electrochemical Devices

[0097] A solid electrolyte according to another embodiment may include the aforementioned solid ion conductor. The solid electrolyte may be the aforementioned solid ion conductor or, in addition to the aforementioned solid ion conductor, may further include an oxide-based solid ion conductor or / and a sulfide-based solid ion conductor.

[0098] The above-described solid electrolyte may include the aforementioned solid ion conductor to form a stable interface that does not have side reactions with the electrode during charging and discharging. The above-described solid ion conductor may include a compound having lithium ion transport channels extended in a three-dimensional direction, and the lithium ion conductivity may be increased at room temperature.

[0099] The above oxide-based solid ion conductor is Garnet-based ceramics Li 3+x La3M2O 12 (M = Te, Nb, or Zr, x is an integer from 1 to 10), lithium phosphorus oxynitride (Li x PO y N z )(0< x <1, 0< y <1, 0< z <1)(LiPON: Lithium Phosphorus Oxynitride), Li x P y O z N k (2.7≤ x ≤3.3, 0.8≤ y ≤1.2, 3.5≤ z ≤3.9, 0.1≤ k ≤0.5), Li w PO x N y S z (0< w <1, 0< x <1, 0< y <1, 0< z <1), 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, SiC, Lithium Phosphate (Li3PO4), Lithium Titanium Phosphate (Li x Ti y (PO4)3, 0< x <2, 0< y <3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO4)3, 0< x <2, 0< y <1, 0< z <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), lithium germanium thiophosphate (Li x Ge y P z S w , 0< x <4, 0< y <1, 0< z <1, 0< w <5), lithium nitride glass (Li x N y , 0< x <4, 0< y <2), SiS2(Li x Si y S z , 0< x <3, 0< y <2, 0< z <4), P2S5 series glass (Li x P y S z , 0< x <3, 0< y <3, 0< z <7), Li2O, LiF, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2-based ceramics, Garnet-based ceramics Li 3+x La3M2O 12 (M = Te, Nb, or Zr, where x is an integer from 1 to 10), or a combination thereof may be used. For example, the oxide-based solid ion conductor may use a garnet-based oxide-based solid electrolyte that exhibits excellent reduction stability when in contact with a lithium anode. Garnet-based ceramics Li 3+x La3M2O 12 (M = Te, Nb, or Zr), for example LLZO(Li 6.5 La3Zr 1.5 Ta 0.5 O 12 ) can be used.

[0100] The above sulfide-based solid ion conductors are 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, n are positive numbers, Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, In), Li 7-x PS 6-x Cl x (0< x <2), Li 7-x PS 6-x Br x (0< x <2), Li 7-x PS 6-x I x (0 < x < 2), or a combination thereof may be used. For example, the sulfide-based solid ion conductor may include at least sulfur (S), phosphorus (P), and lithium (Li) elements. For example, the sulfide-based solid ion conductor may include Li2S-P2S5. If the sulfide-based solid ion conductor is Li2S-P2S5, the molar ratio of Li2S and P2S5 may be in the range of, for example, Li2S:P2S5 = 50:50 to 90:10.

[0101] For example, sulfide-based solid ion conductors may include argyrodite-type solid ion conductors represented by the following chemical formula 4:

[0102] <Chemical Formula 4>

[0103] Li 12-n-x A'X 6-x Y x

[0104] In the above formula,

[0105] A' is P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb or Ta, and

[0106] X is S, Se, or Te, and

[0107] Y is Cl, Br, I, F, CN, OCN, SCN, or N3, and

[0108] 1 < n < 5, 0 < x < 2.

[0109] The oxidation number of A' is +n, the oxidation number of X is -2, and the oxidation number of Y is -1.

[0110] The above sulfide-based solid ion conductor is Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be an azirodite-type compound comprising one or more selected from (0≤x≤2). For example, the sulfide-based solid ion conductor may be an azirodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0111] The above solid electrolyte may further include a binder. For example, the binder included in the above solid electrolyte may be styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, or a combination thereof. However, it is not limited thereto, and any binder used in the relevant technical field is acceptable.

[0112] If necessary, the solid electrolyte may further comprise an organic solid electrolyte. Examples of the organic solid electrolyte may include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, poly-adhesion lysines, polyester sulfides, polyvinyl alcohols, polyvinylidene fluoride, or polymers containing ionic dissociators. If necessary, the solid electrolyte may further comprise an amorphous solid electrolyte. The solid electrolyte may comprise a mixed solid electrolyte comprising a mixture of a crystalline solid electrolyte and an amorphous solid electrolyte. If necessary, the solid electrolyte may further comprise a lithium salt or / and an ionic liquid.

[0113] The above-mentioned solid electrolyte may be in the form of a powder or a molded article. The solid electrolyte in the form of a molded article may be, for example, in the form of pellets, sheets, thin films, etc., but is not necessarily limited to these and may have various forms depending on the application.

[0114] An electrochemical device according to another embodiment includes an anode layer, a cathode layer, and a solid electrolyte layer, and may include the aforementioned solid electrolyte.

[0115] The above solid electrolyte may be included in the solid electrolyte layer, the anode layer, the cathode layer, the anode layer protective film, the cathode layer protective film, or a combination thereof.

[0116] The above solid electrolyte may have a thickness of 10 micrometers (μm) to 1 millimeter (mm) and may be a single layer or multilayer structure.

[0117] For example, the solid electrolyte may comprise, in the solid electrolyte layer alone, a solid ion conductor comprising a compound represented by Chemical Formula 1 and having a crystal structure of a Pnma space group or a Pnma-like space group. Alternatively, the solid electrolyte layer may comprise an oxide-based solid ion conductor or a sulfide-based solid ion conductor as a separate layer in addition to the solid ion conductor.

[0118] For example, the solid electrolyte may comprise, alone, a solid ion conductor comprising a compound represented by Formula 1 and having a Pnma space group or Pnma-like space group crystal structure in the anode layer or / and cathode layer. Alternatively, in addition to the solid ion conductor, an oxide-based solid ion conductor solid electrolyte or / and an ionic liquid-containing electrolyte may be included in the anode layer or / and cathode layer as separate single-layer or multi-layer structures. For example, the electrochemical device may comprise, in the order of an anode layer, an ionic liquid-containing electrolyte, an oxide-based solid ion conductor solid electrolyte, a solid ion conductor solid electrolyte containing a compound represented by Formula 1 and having a Pnma space group or Pnma-like space group crystal structure, an oxide-based solid ion conductor solid electrolyte, and a cathode layer.

[0119] The above electrochemical device may be an all-solid-state secondary battery or a metal-air battery. However, it is not limited thereto, and any electrochemical device usable in the relevant technical field is acceptable.

[0120] For example, the above electrochemical device may be an all-solid-state secondary battery.

[0121] FIGS. 4 to 6 are cross-sectional views of an all-solid-state secondary battery according to one embodiment.

[0122] Referring to FIGS. 4 to 6, the all-solid-state secondary battery (1) comprises a positive electrode layer (10) including a positive current collector (11) and a positive active material layer (12); a negative electrode layer (20); and a solid electrolyte layer (30) disposed between the positive electrode layer (10) and the negative electrode layer (20). The negative electrode layer (20) comprises a negative electrode current collector (21) and a negative electrode active material layer (22) disposed on the negative electrode current collector (21), wherein the negative electrode active material layer (22) comprises a negative electrode active material that forms an alloy or compound with lithium metal, lithium. One or more of the positive electrode layer (10); the negative electrode layer (20); and the solid electrolyte layer (30) of the all-solid-state secondary battery (1) comprise a solid ion conductor comprising a compound represented by the above chemical formula 1 and having a Pnma space group or a Pnma-like space group crystal structure.

[0123] For the positive current collector (11), for example, a plate or foil made of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof may be used. The positive current collector (11) may be omitted.

[0124] The positive active material layer (12) may include a positive active material or / and a solid electrolyte. The solid electrolyte included in the positive layer (10) may be the same as or different from the solid electrolyte included in the solid electrolyte layer (30).

[0125] The cathode active material may be a cathode active material capable of reversibly absorbing and releasing lithium ions. For example, the cathode active material may be formed using lithium cobalt oxide (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (hereinafter referred to as NCA), lithium nickel cobalt manganese oxide (hereinafter referred to as NCM), lithium manganese oxide, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide. Each of these cathode active materials may be used individually or in combination of two or more types.

[0126] For example, the cathode active material is LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn z Examples include lithium salts of ternary transition metal oxides such as O2(NCM) (where 0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1).

[0127] A coating layer may be formed on the cathode active material. Any coating layer that is used as a coating layer for the cathode active material of an all-solid-state secondary battery may be used. Examples of coating layers include, for instance, Li2O-ZrO2.

[0128] In addition, if the positive active material is formed from a lithium salt of a ternary transition metal oxide such as NCA or NCM and includes nickel (Ni) as the positive active material, the capacity density of the all-solid-state secondary battery (1) can be increased, thereby reducing the metal leaching of the positive active material in the charged state. The all-solid-state secondary battery (1) can improve long-term reliability and cycle characteristics in the charged state.

[0129] Examples of the shapes of the above positive active material include particle shapes such as oval and spherical. In addition, the particle size of the positive active material is not limited and can be used as long as it is within a range applicable to the positive active material of an all-solid-state secondary battery. The content of the positive active material of the positive layer (10) is also not limited and can be used as long as it is within a range applicable to the positive of an all-solid-state secondary battery.

[0130] The anode layer (10) may appropriately incorporate additives such as, for example, a conductive agent, a binder, a filler, a dispersant, and an ion-conducting aid, in addition to the anode active material or / and solid electrolyte described above.

[0131] Examples of conductive agents that can be incorporated into the anode layer (10) include graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or metal powder. Examples of binders that can be incorporated into the anode layer (10) include styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. Known materials generally used in electrodes of all-solid-state secondary batteries can be used as coating agents, dispersants, and ion-conducting aids that can be incorporated into the anode layer (10).

[0132] The negative electrode layer (20) may include a negative electrode current collector (21) and a negative electrode active material layer (22).

[0133] Materials constituting the negative electrode current collector (21) may include copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), or nickel (Ni). The negative electrode current collector (21) may be composed of one type of metal, or may be composed of an alloy of two or more types of metals or a coating material. The negative electrode current collector (21) may be formed, for example, in a plate shape or a thin shape.

[0134] The negative electrode active material layer (22) may use lithium or an alloy comprising one or more selected from lithium and indium (In), silicon (Si), gallium (Ga), tin (Sn), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), gold (Au), platinum (Pt), palladium (Pd), magnesium (Mg), palladium (Pd), silver (Ag), and zinc (Zn). However, it is not limited thereto, and any metal or metalloid capable of forming an alloy with lithium available in the art may be used.

[0135] If necessary, the negative electrode active material layer (22) may further include a carbon-based negative electrode active material. The carbon-based negative electrode active material may be graphite, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, carbon nanotube, or carbon nanofiber.

[0136] The negative electrode active material layer (22) may also appropriately incorporate additives such as a conductive agent, binder, filler, dispersant, and ion conductivity aid.

[0137] If necessary, the cathode active material layer (22) may be a non-cathode coating layer. For example, the non-cathode coating layer may have a structure containing a metal such as silicon and carbon, and a conductive binder disposed around the metal and carbon. The thickness of the non-cathode coating layer may be 1 μm to 20 μm.

[0138] The solid electrolyte layer (30) can be manufactured by depositing using known film deposition methods, such as aerosol deposition, cold spray, or sputtering. Alternatively, the solid electrolyte layer (30) can be manufactured by pressurizing a single solid electrolyte particle. Alternatively, the solid electrolyte layer (30) can be manufactured by mixing the solid electrolyte, solvent, and binder, applying the mixture, drying, and pressurizing.

[0139] As shown in FIG. 5, a thin film (24) may be formed on the surface of the negative current collector (21). The thin film (24) may contain elements capable of forming an alloy with lithium. Elements capable of forming an alloy with lithium may include, for example, gold, silver, zinc, tin, indium, silicon, aluminum, and bismuth. The thin film (24) may be composed of one of these metals or may be composed of several types of alloys. By having the thin film (24), the precipitation pattern of the metal layer (23) shown in FIG. 6 may be further flattened, and the characteristics of the solid secondary battery (1) may be further improved.

[0140] The thickness of the thin film (24) may be 1 nm to 500 nm, but is not limited thereto. When the thickness of the thin film (24) is within the above range, the function of the thin film (24) is sufficiently performed, and the amount of lithium precipitated in the negative electrode layer is appropriate, so the characteristics of the all-solid-state secondary battery (1) are excellent. The thin film (24) can be formed on the negative electrode current collector (21) by, for example, vacuum deposition, sputtering, plating, etc.

[0141] Method for manufacturing a solid ion conductor

[0142] A method for manufacturing a solid ion conductor according to one embodiment may include: a step of providing a precursor mixture for forming a solid ion conductor; and a step of performing mechanical milling on the mixture to manufacture a solid ion conductor comprising a compound represented by the following chemical formula 1, having an orthorhombic crystal structure, and belonging to a Pnma space group or a Pnma-like space group:

[0143] <Chemical Formula 1>

[0144] Li 3-x A x LuCl 6-y B y

[0145] In the above formula,

[0146] A can be a monovalent cation having an ionic radius of 76 pm or more, and

[0147] B can be a monovalent anion, and

[0148] 0 ≤ x ≤ 0.1, 0 ≤ y ≤ 1, and x + y > 0.

[0149] The above method for manufacturing a solid ion conductor can easily manufacture a solid ion conductor having improved ion conductivity and low interfacial resistance.

[0150] When preparing the above-mentioned precursor mixture for forming a solid ion conductor, a lithium precursor, a precursor A, a lutetium precursor, and a precursor B may be mixed. In the above-mentioned Chemical Formula 1, when x=0, precursor A may be omitted, and when y=0, precursor B may be omitted.

[0151] The lithium precursor and precursor B may include lithium chlorides, halides, oxides, nitrides, oxynitrides, nitrates, hydroxides, and carbonates. For example, the lithium precursor may be lithium chloride. For example, precursor B may be a lithium halide.

[0152] A precursor may include chlorides, oxides, nitrides, oxynitrides, nitrates, hydroxides, and carbonates of one element selected from sodium, potassium, rubidium, cesium, silver, gold, copper, mercury, and thallium. For example, A precursor may be a chloride of one element selected from sodium, potassium, rubidium, cesium, silver, gold, copper, mercury, and thallium.

[0153] Lutetium precursors may include chlorides, oxides, nitrides, oxynitrides, nitrates, hydroxides, and carbonates of lutetium. For example, the lutetium precursor may be lutetium chloride.

[0154] The above compound can be used to prepare a mixture by contacting the starting material in an appropriate amount, for example, a stoichiometric amount. Mechanical milling is performed on the mixture.

[0155] The above mechanical milling may use a ball mill, airjet mill, bead mill, roll mill, planetary mill, hand milling, high energy ball mill, planetary ball mill, stirred ball mill, vibrating mill, mechanofusion milling, shaker milling, planetary milling and atritor milling, disk milling, shape milling, nauta milling, nobilta milling, high speed mix, or a combination thereof. For example, the above mechanical milling may be planetary milling and may be performed at room temperature.

[0156] 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.

[0157] Example 1: Li 2.95 Na 0.05 LuCl 6 Manufacturing of solid ion conductors

[0158] A precursor mixture for forming a solid ion conductor was prepared by introducing and mixing a lithium precursor LiCl, a sodium precursor NaCl, and a lutetium precursor LuCl3 in stoichiometric ratios into a reactor. The above precursor mixture for forming a solid ion conductor was ball-milled for a total of 24 hours at 700 rpm using a planetary mill (Pulverisette 7 premium line) equipped with 10 mm diameter zirconia (YSZ) balls to Li 2.95 Na 0.05 A LuCl6 solid ion conductor was prepared. Li 2.95 Na 0.05 LuCl6 solid ion conductors have an orthorhombic crystal structure and belong to the Pnma-like space group.

[0159] Example 2: Li 2.95 Cu 0.05 LuCl 6 Manufacturing of solid ion conductors

[0160] Except for using the copper precursor CuCl instead of the sodium precursor NaCl in the reactor, Li was produced in the same manner as in Example 1. 2.95 Cu 0.05 A LuCl6 solid ion conductor was prepared. Li 2.95 Cu 0.05 LuCl6 solid ion conductors have an orthorhombic crystal structure and belong to the Pnma-like space group.

[0161] Example 3: Li 2.95 Ag 0.05 LuCl 6 Manufacturing of solid ion conductors

[0162] Except for using the silver precursor AgCl instead of the sodium precursor NaCl in the reactor, Li was used in the same manner as in Example 1. 2.95 Ag 0.05 A LuCl6 solid ion conductor was prepared. Li 2.95 Ag 0.05 LuCl6 solid ion conductors have an orthorhombic crystal structure and belong to the Pnma-like space group.

[0163] Example 4: Li 3 LuCl 5 Br Manufacturing of solid ion conductors

[0164] A Li3LuCl5Br solid ion conductor was prepared in the same manner as in Example 1, except that a bromine precursor, LiBr, was used in the reactor instead of a sodium precursor, NaCl. The Li3LuCl5Br solid ion conductor has an orthorhombic crystal structure and belongs to the Pnma-like space group.

[0165] Comparative Example 1: Li 3 LuCl 6 Manufacturing of solid ion conductors

[0166] A Li3LuCl6 solid ion conductor was prepared in the same manner as in Example 1, except that a lithium precursor LiCl and a lutetium precursor LuCl3 were introduced into the reactor in stoichiometric ratios. The Li3LuCl6 solid ion conductor has an orthorhombic crystal structure and belongs to the Pnma space group.

[0167] Comparative Example 2: Li 3 LuCl 3 Br 3 Manufacturing of solid ion conductors

[0168] A Li3LuCl3Br3 solid ion conductor was prepared in the same manner as in Example 1, except that a lithium precursor LiCl, a lutetium precursor LuCl3, and a bromine precursor LiBr were introduced into the reactor in stoichiometric ratios. The Li3LuCl3Br3 solid ion conductor has an orthorhombic crystal structure and belongs to the C2 / m-like space group.

[0169] Comparative Example 3: Li 3 LuBr 6 Manufacturing of solid ion conductors

[0170] A Li3LuBr6 solid ion conductor was prepared in the same manner as in Example 1, except that a lithium precursor LiBr and a lutetium precursor LuBr3 were introduced into the reactor in stoichiometric ratios. The Li3LuBr6 solid ion conductor has a monoclinic crystal structure and a C2 / m space group crystal structure.

[0171] Comparative Example 4: Li 3 InCl 6 Manufacturing of solid ion conductors

[0172] A Li3InCl6 solid ion conductor was prepared in the same manner as in Example 1, except that an indium precursor, InCl3, was introduced into the reactor in stoichiometric proportions instead of a sodium precursor, NaCl. The Li3InCl6 solid ion conductor has a monoclinic crystal structure and a C2 / m space group crystal structure.

[0173] Comparative Example 5: Li 3 ErCl 6 Manufacturing of solid ion conductors

[0174] A Li3ErCl6 solid ionic conductor was prepared in the same manner as in Example 1, except that ErCl3, an erbium precursor, was introduced into the reactor in stoichiometric proportions instead of NaCl, a sodium precursor. The Li3ErCl6 solid ionic conductor has a trigonal crystal structure and a P-3m1 space group crystal structure.

[0175] Comparative Example 6: Li 3 DyCl 6 Manufacturing of solid ion conductors

[0176] A Li3DyCl6 solid ionic conductor was prepared in the same manner as in Example 1, except that the dysprosium precursor DyCl3 was introduced into the reactor in stoichiometric proportions instead of the sodium precursor NaCl. The Li3DyCl6 solid ionic conductor has a trigonal crystal structure and a P-3m1 space group crystal structure.

[0177] Analysis Example 1: XRD Experiment

[0178] XRD spectra using CuKα rays were measured for the solid ion conductors prepared according to Example 1, Example 4, and Comparative Examples 1 to 3. The results are shown in Figures 3a and 3b.

[0179] Referring to FIGS. 3a and 3b, peaks were observed in the solid ion conductor compounds prepared according to Example 1 and Example 4 in the region where the diffraction angle 2θ is 29.5° to 32°, the region where it is 33° to 34.5°, and the region where it is 34.5° to 36.3°. This was similar to the diffraction angle 2θ region where peaks were observed in the Li3LuCl6 solid ion conductor prepared according to Comparative Example 1, which has an orthorhombic crystal structure and a Pnma space group. From this, it can be confirmed that the solid ion conductor compounds prepared according to Example 1 and Example 4 have an orthorhombic crystal structure and a Pnma-like space group crystal structure.

[0180] The diffraction angle 2θ region where the peak of the compound of the solid ion conductor prepared according to Example 4 was observed was shifted to the left compared to the diffraction angle 2θ region where the peak of the Li3LuCl6 solid ion conductor prepared according to Comparative Example 1 appeared. According to Bragg's law (2dsinθ = nλ), from the relationship between the diffraction angle (2θ) and the interplanar distance (d), the compound of the solid ion conductor prepared according to Example 4 appears to have increased in volume by about 4% compared to the Li3LuCl6 solid ion conductor prepared according to Comparative Example 1.

[0181] Evaluation Example 1: Measurement of ion conductivity

[0182] The solid ion conductors prepared according to Examples 1–4 and Comparative Examples 1–6 were each prepared as specimens in the form of pellets with a thickness of approximately 500 μm. Electrodes were formed by depositing gold (Au) paste onto the top and bottom surfaces of the solid ion conductor pellets by sputtering, and then heat-treated in air at 700°C for 1 hour. The impedance of the specimens with the formed electrodes was measured using the 2-probe method with an impedance analyzer (Biologic VMP3). The frequency range was 1 Hz to 1 MHz, and the amplitude voltage was 200 mV. Measurements were taken at 25°C in an air atmosphere. The resistance value was determined from the arc of the Nyquist plot of the impedance measurement results, and the ion conductivity was calculated considering the area and thickness of the specimens. The results are shown in Table 1 below.

[0183] Ionic conductivity (S / cm, @ 25℃) Example 1 0.26 Example 2 0.15 Example 3 0.25 Example 4 0.21 Comparative Example 1 0.05 Comparative Example 2 0.28 Comparative Example 3 0.03 Comparative Example 4 0.34 Comparative Example 5 < 0.01 Comparative Example 6 0.04

[0184] Referring to Table 1, the ionic conductivity of the solid ion conductors prepared according to Examples 1 to 4 is 1 x 10⁻⁶ at 25°C. -1 mS·cm -1The above was the result. The solid ion conductors prepared according to Examples 1 to 4 showed improved ion conductivity compared to Comparative Example 1, Comparative Example 3, Comparative Example 5, and Comparative Example 6.

[0185] Evaluation Example 2: Interfacial Resistance Measurement

[0186] A lithium foil with a thickness of 8 mm was placed on one side of a solid ion conductor pellet prepared according to Examples 1 to 4 and Comparative Examples 1 to 6, and a lithium electrode was attached by applying 250 MPa at 25°C using the Cold Isotactic Pressing (CIP) method.

[0187] A lithium / solid electrolyte / lithium symmetry cell was prepared by attaching a lithium electrode to the opposite side of the pellet using the same method. Current collectors were placed on the lithium electrodes positioned on both sides of the pellet, and while sealing the symmetry cell, a portion of the current collector was allowed to protrude outside the sealed cell to serve as an electrode terminal. The interfacial resistance of the pellet was measured using the prepared symmetry cell.

[0188] The impedance of the symmetric cell was measured using the 2-probe method with a Biologic VMP3 as an impedance analyzer. The impedance measurements were performed in a dryroom atmosphere with an amplitude of 200 mV, a frequency range of 1 Hz to 1 MHz, and a dew point of -60 degrees or lower at 25°C.

[0189] The interfacial resistance was measured from the size of the arc of the Nyquist plot of the impedance measurement results. The results are shown in Table 2 below.

[0190] Interfacial resistance (Ω·cm) 2 ) Example 1 53 Example 2 440 Example 3 225 Example 4 103 Comparative Example 1 508 Comparative Example 2 4008 Comparative Example 3 3880 Comparative Example 4 3280 Comparative Example 5 〉 10000 Comparative Example 6 6140

[0191] Referring to Table 2, the interfacial resistance of the solid ion conductors prepared according to Examples 1 to 4 is 440 Ω·cm 2The interfacial resistance of the solid ion conductors prepared according to Examples 1 to 4 was significantly reduced compared to Comparative Examples 1 to 6.

[0192] From this, it can be confirmed that a solid ion conductor according to one embodiment has an orthorhombic crystal structure and includes a compound substituted with a monovalent cation or / and a monovalent anion at a Li site or / and Cl site that can increase volume in three dimensions, and has improved ion conductivity and low interfacial resistance. Explanation of the symbols

[0193] 1, 1a: All-solid-state secondary battery 10: Cathode layer 11: Positive current collector 12: Positive active material layer 20: Cathode layer 21: Cathode current collector 22: Cathode active material layer 23: Metal layer 24: Thin film 30: Solid electrolyte layer

Claims

Claim 1 A solid ionic conductor represented by the following chemical formula 1, comprising a compound having an orthorhombic crystal structure and belonging to the Pnma space group or the Pnma-like space group: <Chemical Formula 1>Li 3-x A x LuCl 6-y B y In the above formula, A is Na + , K + , Rb + , Cs + , Ag + , Au + , Cu + , Hg + , Tl + , or a combination thereof, and B is Br - , I - , or a combination thereof, and 0 ≤ x ≤ 0.1, 0 ≤ y ≤ 1, and x + y > 0. Claim 2 delete Claim 3 delete Claim 4 The solid ion conductor of claim 1, wherein the following compound comprises a compound represented by the following chemical formula 2 or chemical formula 3: <Chemical Formula 2>Li 3-x A x In the above formula for LuCl6, A is Na + , K + , Rb + , Cs + , Ag + , Au + , Cu + , Hg + , Tl + , or a combination thereof, and 0 < x ≤ 0.

1. <Chemical Formula 3> Li3LuCl 6-y B y In the above formula, B is Br - , I - , or a combination thereof, and 0 < y ≤ 1. Claim 5 In claim 1, in the above chemical formula 1, A is Na + , K + , Rb + , Cs + , Ag + , Au + , Cu + , Hg + , Tl + , or a combination thereof, and B is Br - , I - A solid ion conductor comprising a compound that is , or a combination thereof, wherein 0 < x ≤ 0.1 and 0 < y ≤ 1. Claim 6 1 2.95 On 0.05 LuCl6, Li 2.95 K 0.05 LuCl6, Li 2.95 Number 0.05 LuCl6, Li 2.95 Cs 0.05 LuCl6, Li 2.95 Ag 0.05 LuCl6, Li 2.95 Oh! 0.05 LuCl6, Li 2.95 I will 0.05 LuCl6, Li 2.95 Hg 0.05 LuCl6, Li 2.95 Soil 0.05 LuCl6, Li3LuCl5Br, Li3LuCl5I, Li 2.95 On 0.05 LuCl5Br, Li 2.95 K 0.05 LuCl5Br, Li 2.95 Number 0.05 LuCl5Br, Li 2.95 Cs 0.05 LuCl5Br, Li 2.95 Ag 0.05 LuCl5Br, Li 2.95 Oh! 0.05 LuCl5Br, Li 2.95 I will 0.05 LuCl5Br, Li 2.95 Hg 0.05 LuCl5Br, Li 2.95 Soil 0.05 LuCl5Br, Li 2.95 On 0.05 LuCl5I, Li 2.95 K 0.05 LuCl5I, Li 2.95 Number 0.05 LuCl5I, Li 2.95 Cs 0.05 LuCl5I, Li 2.95 Ag 0.05 LuCl5I, Li 2.95 Oh! 0.05 LuCl5I, Li 2.95 I will 0.05 LuCl5I, Li 2.95 Hg 0.05 LuCl5I, Li 2.95 Tl 0.05 A solid ion conductor, LuCl5I, or a combination thereof. Claim 7 A solid ion conductor according to claim 1, wherein the compound has different lengths in the x-axis, y-axis, and z-axis directions, each axis is perpendicular to the others, and has a centrosymmetric structure with 8 inversion points per unit cell. Claim 8 A solid ion conductor according to claim 7, wherein the compound has four screw axes per unit cell along each unit cell direction and two planes per unit cell in a direction perpendicular to each unit cell axis. Claim 9 In claim 1, the compound is a solid ion conductor in which LuCl6 or LiX6 (X = Cl, Br) octahedra are positioned in an edge-sharing manner in an orthorhombic crystal structure, and A cation is located at the Li site. Claim 10 A solid ion conductor according to claim 1, wherein the compound has lithium ion transport channels connected in three dimensions within an orthorhombic crystal structure. Claim 11 A solid ion conductor according to claim 1, wherein the compound has lithium ion transport channels extended in the x-axis, y-axis, and z-axis directions in a spatial distribution according to the ionic radius of the A cation or the B anion within an orthorhombic crystal structure. Claim 12 A solid ion conductor according to claim 1, wherein one or more peaks appear in the region where the diffraction angle 2θ obtained by the XRD spectrum using CuKα-rays of the compound is 29° to 32°, 33° to 35°, or 34° to 37°. Claim 13 In claim 12, the compound is a solid ion conductor that is shifted to the left relative to the Li3LuCl6 compound in the diffraction angle 2θ region where the peak appears. Claim 14 In claim 1, the solid ion conductor is 1 x 10 at 25°C -1 mS·cm -1 A solid ion conductor having an ion conductivity greater than or equal to the above. Claim 15 In claim 1, the solid ion conductor is disposed between lithium metals at 25°C, 1 Hz to 10 of a lithium symmetric cell. 6 The interfacial resistance between the solid ion conductor and the lithium metal, measured in the impedance spectrum in the frequency range of Hz, is 500 Ω·cm 2 Lee Ha-in, solid ion conductor. Claim 16 A solid electrolyte comprising a solid ion conductor according to any one of claims 1, 4 to 15. Claim 17 An electrochemical device comprising an anode layer, a cathode layer, and a solid electrolyte layer, and a solid electrolyte according to claim 16. Claim 18 In claim 17, the electrochemical device wherein the solid electrolyte comprises the solid electrolyte layer, the anode layer, the cathode layer, the anode layer protective film, the cathode layer protective film, or a combination thereof. Claim 19 In claim 17, the electrochemical device wherein the solid electrolyte has a thickness of 10 micrometers (μm) to 1 millimeter (mm) and has a single-layer or multi-layer structure. Claim 20 In paragraph 17, the electrochemical element is an all-solid-state secondary battery or a metal-air battery. Claim 21 A method for manufacturing a solid ion conductor, comprising: a step of providing a precursor mixture for forming a solid ion conductor; and a step of performing mechanical milling on the mixture to manufacture a solid ion conductor comprising a compound represented by the following chemical formula 1, having an orthorhombic crystal structure, and belonging to the Pnma space group or a Pnma-like space group: <Chemical Formula 1>Li 3-x A x LuCl 6-y B y In the above formula, A is Na + , K + , Rb + , Cs + , Ag + , Au + , Cu + , Hg + , Tl + , or a combination thereof, and B is Br - , I - , or a combination thereof, and 0 ≤ x ≤ 0.1, 0 ≤ y ≤ 1, and x + y > 0. Claim 22 A method for manufacturing a solid ion conductor according to claim 21, wherein the mechanical milling is a ball mill, airjet mill, bead mill, roll mill, planetary mill, hand milling, high energy ball mill, planetary mill ball mill, stirred ball mill, vibrating mill, mechanofusion milling, shaker milling, planetary milling and atritor milling, disk milling, shape milling, nauta milling, nobilta milling, high speed mix, or a combination thereof. Claim 23 A method for manufacturing a solid ion conductor according to claim 21, wherein the mechanical milling is planetary milling and is performed at room temperature.

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