Solid electrolyte, preparation method thereof, lithium-air battery and electrochemical device

Abstract

The present invention relates to a solid electrolyte, a method for preparing the same, a lithium-air battery including the same, and an electrochemical device including the same. The solid electrolyte includes: a compound represented by Formula 1, wherein, in Formula 1, M1 is a tetravalent element, M2 is a monovalent element, a divalent element, a trivalent element, a tetravalent element, a pentavalent element, a hexavalent element, or a combination thereof, X is a halogen atom, a pseudohalogen, or a combination thereof, 0 < x < 8, 0 ≤ y < 1, and 0 < z < 4. Formula 1 Li x M1 2‑y M2 y (PO 4‑z X z )3.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefits of U.S. Provisional Patent Application No. 62 / 906,297 filed in the U.S. Patent and Trademark Office on September 26, 2019, and Korean Patent Application No. 10-2020-0023004 filed in the Korean Intellectual Property Office on February 25, 2020, and all rights arising therefrom, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates to a solid electrolyte, a method of preparing the solid electrolyte, and a lithium-air battery and an electrochemical device each including the solid electrolyte. Background Art

[0004] In lithium-air batteries, lithium metal is used as a negative electrode active material, and there is no need to store air as a positive electrode active material in the battery, so the lithium-air battery can be implemented as a high-capacity battery. In addition, the lithium-air battery has a high theoretical specific energy of 3,500 watt-hours / kilogram (Wh / kg) or more.

[0005] The stability of solid electrolytes of lithium-air batteries to lithium hydroxide, which is a discharge product of lithium-air batteries, is unsatisfactory, and, for example, the ion conductivity under strong alkaline conditions (such as in lithium hydroxide) is reduced relative to that in acid. Therefore, improved battery materials are needed. Summary of the invention

[0006] Provided are a solid electrolyte that is stable to strong alkali and moisture, and a method for preparing the solid electrolyte.

[0007] A lithium-air battery including the solid electrolyte is provided.

[0008] An electrochemical device including the solid electrolyte is provided.

[0009] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments of the disclosure.

[0010] According to one aspect, a solid electrolyte is provided, which includes: a compound represented by Formula 1

[0011] Formula 1

[0012] Li x M1 2-y M2 y (PO 4-z X z ) 3

[0013] Among them, in Formula 1, M1 is a tetravalent element, M2 is a monovalent element, divalent element, trivalent element, tetravalent element, pentavalent element, hexavalent element, or a combination thereof, X is a halogen atom, pseudohalogen, or a combination thereof, 0 < x < 8, 0 ≤ y < 1, and 0 < z < 4.

[0014] According to another aspect, a lithium-air battery is provided, which includes: a positive electrode; a negative electrode; and an electrolyte disposed between the positive electrode and the negative electrode, the electrolyte including the solid electrolyte.

[0015] In an embodiment, at least one of the positive electrode and the negative electrode may include the solid electrolyte including the compound of Formula 1.

[0016] According to another aspect, an electrochemical device including the solid electrolyte is provided.

[0017] In an embodiment, the electrochemical device may include a battery, a storage battery, a supercapacitor, a fuel cell, a sensor, an electrochromic device, or a combination thereof.

[0018] According to another aspect, a method for preparing a solid electrolyte is provided, the method including: providing a lithium precursor, an M1 precursor, an X precursor, and a phosphorus precursor to prepare a precursor mixture; and performing a heat treatment on the precursor mixture to prepare a solid electrolyte including the compound represented by Formula 1

[0019] Formula 1

[0020] Li x M1 2-y M2 y (PO 4-z X z ) 3

[0021] Among them, in Formula 1, M1 is a tetravalent element, M2 is a monovalent element, divalent element, trivalent element, tetravalent element, pentavalent element, hexavalent element, or a combination thereof, X is a halogen atom, pseudohalogen, or a combination thereof, 0 < x < 8, 0 ≤ y < 1, and 0 < z < 4.

[0022] In an embodiment, in the preparation of the precursor mixture, an M2 precursor may be further added.

[0023] A solid electrolyte is also disclosed, which includes: the compound represented by Formula 1

[0024] Formula 1

[0025] Li x M1 2-y M2 y (PO 4-z X z )3

[0026] Among them, in Formula 1, M1 is a tetravalent element, M2 is a trivalent element, X is a halogen atom, 0 < x < 8, 0 ≤ y < 0.1, and 0 < z < 0.2. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or other aspects, features, and advantages of some embodiments of the disclosure will become clearer from the following description considered in conjunction with the accompanying drawings, wherein:

[0028] Figure 1 is a graph of intensity (in arbitrary units, a.u.) versus diffraction angle (in degrees, 2θ), which shows the results of X-ray diffraction analysis of the solid electrolytes of Examples 1, 2, and 4 and Comparative Example 1.

[0029] Figure 2 is Figure 1 an enlarged view of a part of the graph shown in

[0030] Figure 3 is a graph of the ionic conductivity (in Siemens / cm, S / cm) of the solid electrolytes of Examples 1-4 and Comparative Example 1 before and after impregnation with lithium hydroxide.

[0031] Figure 4 is a graph of the conductivity retention rate (in percentage after impregnation with lithium hydroxide) versus the ionic conductivity (log(S / cm)), which illustrates the change in ionic conductivity in the solid electrolytes of Example 3 and Comparative Example 1.

[0032] Figure 5 is a schematic diagram of an embodiment of a lithium-air battery. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings, wherein like reference numerals always refer to like elements. In this regard, the present embodiments may have different forms and should not be construed as limited to the description set forth herein. Therefore, the embodiments are described below only by referring to the drawings to illustrate aspects. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one (kind) of..." when before or after a list of elements modify the entire list of elements and not individual elements of the list.

[0034] It will be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings herein, the "first element", "component", "region", "layer" or "part" discussed below may be referred to as a second element, component, region, layer or part.

[0035] The terms used herein are only for the purpose of describing specific embodiments and are not intended to be restrictive. As used herein, "a (individual) (indefinite article) (a, an)", "said (the)" and "at least one (individual)" do not represent the limitation of quantity, and are intended to include both the singular and the plural, unless the context clearly states otherwise. For example, "(an) element" has the same meaning as "at least one element", unless the context clearly states otherwise. "At least one (individual)" will not be interpreted as limiting "a (individual)". "Or" means "and / or". As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items. It will be further understood that the term "comprising" or "including" when used in this specification, means that there are stated features, regions, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components, and / or their sets.

[0036] As used herein, "about" includes the stated value and means within an acceptable range of deviation for a particular value as determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations, or within ±30%, 20%, 10%, or 5% relative to the stated value.

[0037] Unless otherwise defined, the meaning of all terms (including technical and scientific terms) used herein is the same as that of ordinary technicians in the field to which the present disclosure belongs. It will be further understood that terms, such as those defined in common dictionaries, should be interpreted as their meanings consistent with their meanings in the context of the present disclosure and the relevant field, and will not be interpreted in the sense of idealization or excessive form, unless clearly defined in this article. For ease of description, spatial relative terms such as "under ... ", "under ... ", "lower part", "above ... ", "upper part" etc. can be used in this article to describe the relationship between an element or feature and another element or feature as shown in the figure. It will be understood that, in addition to the orientation shown in the figure, spatial relative terms are also intended to include different orientations of the device in use or operation. For example, if the device in the figure is turned over, the element described as "under" or "under" other elements or features will be oriented "above" the other elements or features. Therefore, the exemplary term "under ... " can include two orientations above ... and below .... The device can be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptors used in this article are explained accordingly.

[0038] Exemplary embodiments are described herein with reference to cross-sectional views as schematic diagrams of idealized embodiments. Thus, deviations from the shapes of the figures as a result of, for example, manufacturing techniques and / or tolerances are to be expected. Therefore, the embodiments described herein should not be construed as being limited to the specific shapes of the regions as illustrated herein, but rather include deviations in shape caused by, for example, manufacturing. For example, a region illustrated or described as flat may typically have rough and / or nonlinear features. Moreover, the illustrated sharp corners may be rounded. Therefore, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shapes of the regions and are not intended to limit the scope of the claims.

[0039] Hereinafter, embodiments of a solid electrolyte, a method of preparing the solid electrolyte, a lithium-air battery including the solid electrolyte, and an electrochemical device including the solid electrolyte will be described in detail.

[0040] According to one aspect, a solid electrolyte including a compound represented by Formula 1 is provided.

[0041] Formula 1

[0042] Li x M1 2-y M2 y (PO 4-z X z ) 3

[0043] In Formula 1, M1 can be a tetravalent element, M2 is a monovalent, divalent, trivalent, tetravalent, pentavalent, hexavalent element, or a combination thereof, and X is a halogen atom, pseudohalogen, or a combination thereof.

[0044] 0 < x < 8, 0 ≤ y < 1, and 0 < z < 4.

[0045] In Formula 1, the elements are cationic elements.

[0046] In Formula 1, for example, when M2 is a trivalent element, x can be equal to 1 + y - 3z. When this condition is satisfied, the solid electrolyte including the compound of Formula 1 can satisfy charge balance and be in a neutral state.

[0047] Desirably, the solid electrolyte pair of the lithium-air battery is reversibly stable to any changes that can occur under humid conditions or in air. For this purpose, stability against lithium hydroxide (LiOH) and moisture as discharge products is required. However, existing solid electrolyte pairs have low stability against moisture and strong bases such as lithium hydroxide, and thus have very low conductivity. Therefore, there is an increasing need for solid electrolytes with improved properties.

[0048] There is disclosed such a solid electrolyte that maintains good ionic conductivity even after exposure to strong bases such as lithium hydroxide and maintains good ionic conductivity after exposure to moisture. The solid electrolyte can be obtained by introducing anions from a halogen atom, pseudohalogen, or a combination thereof into a phosphate-based electrolyte.

[0049] Since the solid electrolyte contains the compound of Formula 1 into which anions are introduced, the solid electrolyte can have improved phase stability. In particular, the solid electrolyte can have good stability under strongly basic conditions, for example, at a pH of about 12 to about 13, and thus can maintain good ionic conductivity.

[0050] In Formula 1, M1 can be a tetravalent cationic element, such as hafnium (Hf), titanium (Ti), zirconium (Zr), or a combination thereof.

[0051] At some sites of M1 in the crystal structure of the compound, M2 can substitute for M1. M2 can be, for example, a divalent, trivalent, or tetravalent cationic element, such as aluminum (Al), lanthanum (La), scandium (Sc), cerium (Ce), praseodymium (Pr), gadolinium (Gd), europium (Eu), or a combination thereof. Aluminum (Al), lanthanum (La), scandium (Sc), and gadolinium (Gd) are all trivalent cationic elements, and cerium (Ce) and praseodymium (Pr) can be trivalent or tetravalent elements, and europium (Eu) can be divalent or trivalent elements.

[0052] Although not wishing to be bound by theory, it is understood that the disclosed M2 element has a large lattice volume, and the lithium ion conductivity of the solid electrolyte may be further improved by including M2, compared to a solid electrolyte into which M2 is not introduced.

[0053] As described above, X may be a halogen atom, a pseudohalogen, or a combination thereof.

[0054] As used herein, the term "pseudohalogen" is a molecule that includes two or more electronegative atoms (e.g., consists of two or more electronegative atoms) like a halogen, which in a free state (free state) produces an anion similar to a halide ion. Examples of pseudohalogens are cyanide (CN), cyanate (OCN), thiocyanate (SCN), azide (N 3 ), or a combination thereof.

[0055] X may be, for example, at least one halogen atom, for example, two halogen atoms, and may replace oxygen and may remain at an oxygen site in the crystal structure of the compound of Formula 1.

[0056] For example, X can be chlorine (Cl), bromine (Br), fluorine (F), cyanide, cyanate, thiocyanate, azide, or a combination thereof.

[0057] For example, X 3z Can be F n Br n , Cl n 、(F a Cl 1-a ) n 、(F a Br 1-a ) n , or (Cl a Br 1-a ) n , wherein n may be 1 or less, for example, from about 0.1 to about 0.9, for example, from about 0.1 to about 0.5, for example, from about 0.1 to about 0.3, for example, from about 0.1 to about 0.2. Moreover, a may be from about 0.01 to about 0.99, for example, from about 0.2 to about 0.8, from about 0.3 to about 0.7, for example, about 0.5.

[0058] In Formula 1, x may be from about 0.5 to about 1.5, such as from about 0.7 to about 1.3, such as from about 0.8 to about 1.2. In Formula 1, y may be from 0 to about 0.8, such as from 0 to about 0.5, such as from about 0.05 to about 0.5, such as from about 0.1 to about 0.3. In Formula 1, when y is 0 or greater and M2 is present, and although not wishing to be bound by theory, it is understood that because the lattice volume of M2 may be greater than the lattice volume of M1, when a compound containing M1 and M2 is used, a solid electrolyte having further improved ion conductivity may be prepared compared to when M2 is not present in the compound (e.g., when a compound containing only M1 is used).

[0059] In Formula 1, z may be greater than 0 to about 1, such as about 0.01 to about 0.8, such as about 0.02 to about 0.7, such as about 0.03 to about 0.5, such as about 0.05 to about 0.2.

[0060] In an embodiment, the solid electrolyte may have a phase having a NASICON structure, that is, a crystal structure isostructural with NASICON. NASICON or a structure isostructural with NASICON has a general formula A 1 Q 2 (PO 4 ) 3 Compounds wherein A is a monovalent cation and Q is a single trivalent, tetravalent or pentavalent ion or a combination of trivalent, tetravalent or pentavalent ions. The characteristics of these structures can be identified by X-ray diffraction (XRD) analysis. In an embodiment, in an XRD spectrum, for example, when analyzed by X-ray diffraction spectrometry using CuKα radiation, a solid electrolyte comprising a compound of Formula 1 may exhibit a peak at a diffraction angle (2θ) of 14.1°±0.5°, 19.9°±0.5°, 20.2°±0.5°, 23.5°±0.5°, 28.5°±0.5°, 31.7°±0.5°, or 35.2°±0.5°.

[0061] Compared with the X-ray diffraction peak characteristics of the solid electrolyte including the compound of Formula 1 (wherein z = 0), the solid electrolyte including the compound of Formula 1 may exhibit a shifted X-ray diffraction peak characteristic. From such a shifted X-ray diffraction peak characteristic, it can be understood that X replaces some of the oxygen in the compound. For example, X can replace oxygen and remain at the oxygen crystallographic site.

[0062] In an embodiment, the compound of Formula 1 may exhibit two diffraction peaks at a diffraction angle (2θ) of about 19.8°2θ to about 20.4°2θ in its XRD spectrum. The two diffraction peaks may include a first diffraction peak and a second diffraction peak. The first diffraction peak may have a maximum point at a diffraction angle (2θ) of about 19.93°2θ to about 19.99°2θ, and the second diffraction peak may have a maximum point at a diffraction angle (2θ) of about 20.17°2θ to about 20.25°2θ. For example, the first diffraction peak may have a maximum point at a diffraction angle (2θ) of about 19.95°2θ to about 19.97°2θ, and the second diffraction peak may have a maximum point at a diffraction angle (2θ) of about 20.19°2θ to about 20.23°2θ or about 20.20°2θ to about 20.22°2θ.

[0063] Although not wishing to be bound by theory, it is understood that the first diffraction peak is associated with, for example, the (104) crystal plane of the solid electrolyte including the compound of Formula 1, and the second diffraction peak is associated with, for example, its (110) crystal plane. The height of the second diffraction peak may be in the range of about 72% to about 99%, for example, about 75% to about 82%, for example, about 77% to about 81% of the height of the first diffraction peak. The ratio of the intensity of the second diffraction peak (P2) to the intensity of the first diffraction peak (P1) may be less than about 1, about 0.1 to less than about 1, about 0.6 to less than about 1, or about 0.77 to about 0.81.

[0064] The first diffraction peak may have a half width of about 0.7° 2θ to about 1.3° 2θ, and the second diffraction peak may have a half width of about 0.7° 2θ to about 1.3° 2θ.

[0065] In an embodiment, a solid electrolyte including a compound of Formula 1 may exhibit two peaks at a diffraction angle (2θ) of about 19.8°2θ to about 20.4°2θ in its XRD spectrum. The two diffraction peaks may include a first diffraction peak and a second diffraction peak. The first diffraction peak may have a maximum value at a diffraction angle (2θ) of about 19.93°2θ to about 19.99°2θ, and the second diffraction peak may have a double peak shape.

[0066] The second diffraction peak having a double peak shape may include a second diffraction peak P2 having a first maximum point at a diffraction angle (2θ) of about 20.15°2θ to about 20.25°2θ, and a second diffraction peak P3 having a second maximum point at a diffraction angle (2θ) of about 20.26°2θ to about 20.32°2θ, for example, a second diffraction peak P2 having a first maximum point at a diffraction angle (2θ) of about 20.16°2θ to about 20.24°2θ, about 20.17°2θ to about 20.20°2θ, or about 20.17°2θ to about 20.18°2θ, and a second diffraction peak P3 having a second maximum point at a diffraction angle (2θ) of about 20.28°2θ to about 20.31°2θ, or about 20.29°2θ to about 20.30°2θ. The first diffraction peak may have a half width of about 0.7° 2θ to about 1.3° 2θ, and the second diffraction peak may have a half width of about 0.7° 2θ to about 1.3° 2θ.

[0067] In an embodiment, in the X-ray diffraction spectrum of the solid electrolyte, an intensity ratio of the second diffraction peak P2 to the first diffraction peak may be greater than 1, and an intensity ratio of the second diffraction peak P3 to the first diffraction peak may be greater than 1. X-ray diffraction may be performed using CuKα radiation.

[0068] like Figure 2 As shown in , the second diffraction peak may have a double peak shape including a second diffraction peak A1 having a first maximum point and a second diffraction peak A2 having a second maximum point.

[0069] Although not wishing to be bound by theory, it is understood that the first diffraction peak is associated with, for example, the (104) crystal plane of the solid electrolyte of the compound of Formula 1, and the second diffraction peak having the first maximum point is associated with, for example, its (110) crystal plane. The second diffraction peak having the second maximum point is associated with, for example, the (210) crystal plane of the solid electrolyte of the compound of Formula 1. The height of the second diffraction peak P2 having a first maximum point at 2θ of about 20.15°2θ to about 20.25°2θ, and the height of the second diffraction peak P3 having a second maximum point at 2θ of about 20.26°2θ to about 20.32°2θ may both exceed 100% of the height of the first diffraction peak. The intensity ratio (P2 / P1) of the second diffraction peak P2 to the first diffraction peak P1, and the intensity ratio (P3 / P1) of the second diffraction peak P3 to the first diffraction peak P1 may both be greater than 1, for example, each independently greater than 1 to about 2, greater than 1 to about 1.5, or greater than 1 to about 1.26.

[0070] The first diffraction peak may have a half width of about 0.7°2θ to about 1.3°2θ, the second diffraction peak P2 having the first maximum point may have a half width of about 0.7°2θ to about 1.3°2θ, and the second diffraction peak P3 having the second maximum point may have a half width of about 0.7°2θ to about 1.3°2θ.

[0071] The compound represented by Formula 1 may be a compound represented by Formula 2, a compound represented by Formula 3, or a compound represented by Formula 4.

[0072] Formula 2

[0073] Li 1+y-3z Hf 2-y M2 y (PO 4-z X z ) 3

[0074] In formula 2,

[0075] M2 can be a monovalent element, a divalent element, a trivalent element, a tetravalent element, a pentavalent element, a hexavalent element, or a combination thereof.

[0076] X can be a halogen atom, a pseudohalogen, or a combination thereof,

[0077] 0≤y<1, and 0 <z<4。

[0078] Formula 3

[0079] Li 1+y-3z Ti 2-y M2 y (PO 4-z X z ) 3

[0080] In formula 3,

[0081] M2 can be a monovalent element, a divalent element, a trivalent element, a tetravalent element, a pentavalent element, a hexavalent element, or a combination thereof.

[0082] X can be a halogen atom, a pseudohalogen, or a combination thereof,

[0083] 0≤y<1, and 0 <z<4。

[0084] Formula 4

[0085] Li 1+y-3z Zr 2-y M2 y (PO 4-z X z ) 3

[0086] In formula 4,

[0087] M2 can be a monovalent element, a divalent element, a trivalent element, a tetravalent element, a pentavalent element, a hexavalent element, or a combination thereof.

[0088] X can be a halogen atom, a pseudohalogen, or a combination thereof,

[0089] 0≤y<1, and 0 <z<4。

[0090] In Formulae 2 to 4, 1+y-3z may be from about 0.5 to about 1.5, y may be from 0 or more than 0 to about 0.8, and z may be from more than 0 to about 1.

[0091] In the solid electrolyte, the compound represented by Formula 1 may be, for example, Li 0.8 Hf 2 P 3 O 11.8 F 0.2 , Li 0.8 Hf 2 P 3 O 11.8 Cl 0.2 、LiHf 1.9 Y 0.1 P 3 O 11.9 F 0.1 、LiHf 1.9 Y 0.1 P 3 O 11.9 Cl 0.1 , Li 0.8 Hf 2 P 3 O 11.8 Br 0.2 , Li 0.8 Hf 2 P 3 O 11.8 Br 0.1 F 0.1 , Li 0.8 Hf 2 P 3 O 11.8 Br 0.1 Cl 0.1 、LiHf 1.9 Y 0.1 P 3 O 11.9 Br 0.1 、LiHf 1.9 Y 0.1 P 3 O 11.9 Br 0.05 F 0.05 、LiHf 1.9 Y0.1 P 3 Oh 11.9 Br 0.05 Cl 0.05 、Li 0.8 You 2 P 3 Oh 11.8 F 0.2 、Li 0.8 You 2 P 3 Oh 11.8 Cl 0.2 、LiTi 1.9 Y 0.1 P 3 Oh 11.9 F 0.1 、LiTi 1.9 Y 0.1 P 3 Oh 11.9 Cl 0.1 、Li 0.8 You 2 P 3 Oh 11.8 Br 0.2 、Li 0.8 You 2 P 3 Oh 11.8 Cl 0.2 、LiTi 1.9 Y 0.1 P 3 Oh 11.9 F 0.1 、LiTi 1.9 Y 0.1 P 3 Oh 11.9 Cl 0.1 、Li 0.8 You 2 P 3 Oh 11.8 Br 0.1 F 0.1 、Li 0.8 You 2 P 3 Oh 11.8 Br 0.1 Cl 0.1 、LiTi 1.9 Y 0.1 P 3 Oh 11.9 Br 0.1 、LiTi 1.9 Y 0.1 P 3 Oh 11.9 Br 0.05 F 0.05、LiTi 1.9 Y 0.1 P 3 O 11.9 Br 0.05 Cl 0.05 、Li 0.8 Zr 2 P 3 O 11.8 F 0.2 、Li 0.8 Zr 2 P 3 O 11.8 Cl 0.2 、LiZr 1.9 Y 0.1 P 3 O 11.9 F 0.1 、LiZr 1.9 Y 0.1 P 3 O 11.9 Cl 0.1 、Li 0.8 Zr 2 P 3 O 11.8 Br 0.2 、Li 0.8 Zr 2 P 3 O 11.8 Cl 0.2 、LiZr 1.9 Y 0.1 P 3 O 11.9 F 0.1 、LiZr 1.9 Y 0.1 P 3 O 11.9 Cl 0.1 、Li 0.8 Zr 2 P 3 O 11.8 Br 0.1 F 0.1 、Li 0.8 Zr 2 P 3 O 11.8 Br 0.1 Cl 0.1 、LiZr 1.9 Y 0.1 P 3 O 11.9 Br 0.1 、LiZr 1.9 Y 0.1 P 3 O 11.9 Br0.05 F 0.05 、LiZr 1.9 Y 0.1 P 3 A 11.9 Br 0.05 Cl 0.05 、LiHf 1.9 the 0.1 P 3 A 11.9 F 0.1 、LiHf 1.9 the 0.1 P 3 A 11.9 Br 0.1 、LiHf 1.9 the 0.1 P 3 A 11.9 F 0.05 Br 0.05 、LiHf 1.9 the 0.1 P 3 A 11.9 Cl 0.1 、LiHf 1.9 the 0.1 P 3 A 11.9 Cl 0.05 Br 0.05 、LiHf 1.9 to 0.1 P 3 A 11.9 F 0.1 、LiHf 1.9 to 0.1 P 3 A 11.9 Br 0.1 、LiHf 1.9 to 0.1 P 3 A 11.9 F 0.05 Br 0.05 、LiHf 1.9 to 0.1 P 3 A 11.9 Cl 0.05 Br 0.05 、LiHf 1.9 to 0.1 P 3 A 11.9 Cl 0.1 、LiHf 1.9 Gd 0.1 P 3 A 11.9 F0.1 、LiHf 1.9 Gd 0.1 P 3 A 11.9 F 0.05 Br 0.05 、LiHf 1.9 Gd 0.1 P 3 A 11.9 Cl 0.05 Br 0.05 、LiHf 1.9 Gd 0.1 P 3 A 11.9 Cl 0.1 、LiZr 1.9 the 0.1 P 3 A 11.9 F 0.1 、LiHf 1.9 the 0.1 P 3 A 11.9 F 0.05 Br 0.05 、LiHf 1.9 the 0.1 P 3 A 11.9 Cl 0.05 Br 0.05 、LiZr 1.9 the 0.1 P 3 A 11.9 Cl 0.1 、LiZr 1.9 to 0.1 P 3 A 11.9 F 0.1 、LiZr 1.9 to 0.1 P 3 A 11.9 Br 0.1 、LiZr 1.9 to 0.1 P 3 A 11.9 Br 0.05 F 0.05 、LiZr 1.9 to 0.1 P 3 A 11.9 Br 0.05 Cl 0.05 、LiZr 1.9 to 0.1 P 3 A 11.9 Cl0.1 、LiZr 1.9 Mr. 0.1 P 3 About 11.9 F 0.1 、LiZr 1.9 Mr. 0.1 P 3 About 11.9 No 0.1 、LiZr 1.9 Mr. 0.1 P 3 About 11.9 No 0.05 F 0.05 、LiZr 1.9 Mr. 0.1 P 3 About 11.9 No 0.05 Cl 0.05 、LiZr 1.9 Mr. 0.1 P 3 About 11.9 Cl 0.1 、LiTi 1.9 Al 0.1 P 3 About 11.9 F 0.1 、LiTi 1.9 Mr. 0.1 P 3 About 11.9 No 0.1 、LiTi 1.9 Mr. 0.1 P 3 About 11.9 No 0.05 F 0.05 、LiTi 1.9 Mr. 0.1 P 3 About 11.9 No 0.05 Cl 0.05 、LiTi 1.9 Al 0.1 P 3 About 11.9 Cl 0.1 、LiTi 1.9 The 0.1 P 3 About 11.9 F 0.1 、LiTi 1.9 The 0.1 P 3 About 11.9 Cl 0.1 、LiTi 1.9 Mr.0.1 P 3 O 11.9 F 0.1 、LiTi 1.9 G 0.1 P 3 O 11.9 Br 0.1 、LiTi 1.9 G 0.1 P 3 O 11.9 Br 0.05 F 0.05 、LiTi 1.9 G 0.1 P 3 O 11.9 Br 0.05 Cl 0.05 、LiTi 1.9 G 0.1 P 3 O 11.9 Cl 0.1 , Li 0.8 Hf 2 P 3 O 11.8 F 0.1 Cl 0.1 、LiHf 1.9 Y 0.1 P 3 O 11.9 F 0.05 Cl 0.05 , Li 0.8 Ti 2 P 3 O 11.8 F 0.1 Cl 0.1 、LiTi 1.9 Y 0.1 P 3 O 11.9 F 0.05 Cl 0.05 , Li 0.8 Zr 2 P 3 O 11.8 F 0.1 Cl 0.1 、LiZr 1.9 Y 0.1 P 3 O 11.9 F 0.05 Cl 0.05 , or a combination thereof.

[0092] In an embodiment, the solid electrolyte may have a thickness of, for example, about 1×10-6 Siemens / cm (S / cm) or greater, for example, about 1.4x10 -5 S / cm or larger, about 2x10 -5 S / cm or larger, about 3x10 -5 S / cm or greater, or about 5X10 -5 S / cm or more, for example, about 1x10 -5 S / cm is about 1x10 -3 S / cm, about 5x10 -5 S / cm is about 5x10 -4 S / cm, about 1x10 -5 S / cm is about 1x10 -4 S / cm, and thus the ion conductivity can be maintained even after exposure to a strong base. From this, it is understood that the solid electrolyte according to the embodiment can have excellent stability to a strong base.

[0093] As used herein, the term "ionic conductivity after impregnation with a saturated lithium hydroxide (LiOH) solution" means the ionic conductivity of a solid electrolyte after the solid electrolyte is impregnated with a saturated lithium hydroxide solution and then maintained at 40°C for 6 or 7 days.

[0094] In an embodiment, the solid electrolyte may have an ionic conductivity retention in a saturated lithium hydroxide (LiOH) solution (e.g., after 6 or 7 days at 40° C.) of about 50% or greater, e.g., about 56% or greater, e.g., about 95% or greater, e.g., about 100% or greater, e.g., about 150% or greater, e.g., about 220% or greater, e.g., about 50% to about 400%, about 100% to about 350%, or about 100% to about 300%.

[0095] Throughout the specification, “ion conductivity maintenance rate for a saturated lithium hydroxide (LiOH) solution” can be calculated using Equation 1.

[0096] Equation 1

[0097] Ion conductivity retention rate (%) = (ion conductivity after electrolyte is impregnated with saturated lithium hydroxide solution) / (ion conductivity before electrolyte is impregnated with saturated lithium hydroxide solution) × 100%

[0098] In an embodiment, the solid electrolyte may have a thickness of, for example, about 1×10 -6 Siemens / cm (S / cm) or greater, for example, about 1×10 -5 S / cm or more, for example, about 3x10 -5 S / cm or more, for example, about 1x10 -6S / cm is about 1x10 -3 S / cm, about 5x10 -6 S / cm is about 5x10 -4 S / cm, about 1x10 -5 S / cm is about 1x10 -4 S / cm at 25° C. Since the solid electrolyte according to the embodiment has such a high ionic conductivity, a lithium-air battery including such a solid electrolyte may have further reduced internal resistance.

[0099] The solid electrolyte according to the embodiment may be in the form of particles. For example, the solid electrolyte may have an average particle size of about 5 nanometers (nm) to about 500 micrometers (μm), for example, about 100 nm to about 15 μm, for example, about 300 nm to about 10 μm, and a particle size of about 0.01 square meters / gram (m 2 / g) to about 1000m 2 / g, for example, about 0.1m 2 / g to about 500m 2 / g, or about 0.5m 2 / g to about 100m 2 / g specific surface area. The specific surface area can be determined using a nitrogen isotherm. See, for example, EP Barrett, LG Joyner, PP Halenda, The determination of pore volume and area distributions in porous substances. I. Computations from nitrogen isotherms, J. Am. Chem. Soc. (1951), 73, 373-380, the contents of which are incorporated herein by reference in their entirety.

[0100] Hereinafter, a method of preparing a solid electrolyte according to an embodiment will be further described.

[0101] A lithium precursor, an M1 precursor, an X precursor, a phosphorus precursor and optionally an M2 precursor may be contacted, for example, mixed together, to obtain a precursor mixture. In the preparation of the precursor mixture, an M2 precursor may be further added. M1 of the M1 precursor, X of the X precursor and M2 of the M2 precursor may be defined as described in Formula 1.

[0102] As required, a solvent may be added to the precursor mixture. The solvent may be any suitable solvent, such as a solvent capable of dissolving or dispersing the lithium precursor, the M1 precursor, the X precursor, the phosphorus precursor, and optionally the M2 precursor. The solvent may be, for example, ethanol, water, ethylene glycol, isopropanol, or a combination thereof. Furthermore, a variety of precursors including M1, X, phosphorus, and optionally M2 may be used.

[0103] The mixing can be performed using methods known in the art, such as grinding, blending or sputtering. Grinding can be performed using a ball mill, jet mill, bead mill or roller mill.

[0104] Subsequently, the precursor mixture may be subjected to a first thermal treatment.

[0105] In the first heat treatment of the precursor mixture, the heating rate may be about 1 degree Celsius / minute (°C / minute) to about 10°C / minute, and the first heat treatment temperature may be in the range of about 400°C to about 950°C, for example, in the range of about 700°C to about 900°C. When the heating rate in the first heat treatment is within this range, the first heat treatment may be sufficient to obtain a solid electrolyte according to an embodiment. A second heat treatment may be used, which will be further described later.

[0106] The first heat treatment may be carried out under an oxidizing gas atmosphere. The oxidizing gas atmosphere may be produced using, for example, air or oxygen. The first heat treatment time may vary depending on the first heat treatment temperature, etc. The first heat treatment time may be, for example, in the range of about 1 hour to about 20 hours, for example, in the range of about 2 hours to about 12 hours, or for example, in the range of about 5 hours to about 12 hours.

[0107] The M1 precursor and the M2 precursor may each independently be a compound containing M1 or M2, such as an oxide containing M1 or M2, a carbonate containing M1 or M2, a chloride containing M1 or M2, a phosphate containing M1 or M2, a hydroxide containing M1 or M2, a nitrate containing M1 or M2, or a combination thereof. For example, the M1 precursor and the M2 precursor may each independently be hafnium oxide, zirconium oxide, titanium oxide, yttrium oxide, hafnium nitrate, hafnium sulfate, zirconium nitrate, zirconium sulfate, or a combination thereof.

[0108] The X precursor may be, for example, lithium chloride, lithium fluoride, lithium bromide, or a combination thereof. The lithium precursor may be, for example, lithium oxide, lithium carbonate, lithium chloride, lithium sulfide, lithium nitrate, lithium phosphate, lithium hydroxide, or a combination thereof.

[0109] The phosphorus precursor may be, for example, (NH 4 ) 2 HPO 4 NH 4 )H 2 PO4 、Na 2 HPO 4 、Na 3 PO 4 , or a combination thereof.

[0110] The amounts of the lithium precursor, the M1 precursor, the M2 precursor, the X precursor, and the phosphorus precursor may be stoichiometrically controlled to obtain the compound represented by Formula 1.

[0111] Then, the product from the first heat treatment can be pulverized to obtain a pulverized product. The pulverized product can be in the form of a powder, for example, including a plurality of particles. The pulverized product (particles) obtained by pulverizing can have a size of about 10 μm or less. When the pulverized particles have a size within this range, the particles can be small enough to be fully pulverized and mixed, and can also promote the formation of NASICON structure, for example, compounds with a structure isostructural with NASICON. As used herein, the term "size" can refer to an average particle size when the particles are spherical, or can refer to the length of the major axis when the particles are non-spherical. The size of the particles can be measured, for example, by light scattering, using an electron scanning microscope or a particle size analyzer.

[0112] Next, the pulverized product may be subjected to a second heat treatment. In the second heat treatment of the pulverized product, the heating rate may be about 1°C / min to about 10°C / min. The second heat treatment temperature may be in the range of about 500°C to about 1300°C, for example, in the range of about 800°C to about 1200°C.

[0113] In an embodiment, the second heat treatment temperature may be higher than the first heat treatment temperature. Before the pulverized product is subjected to the second heat treatment, the pulverized product may be pressed into a sheet (pellet). When the second heat treatment is performed on the pulverized product in sheet form, it is easier to obtain the target solid electrolyte due to the reduced diffusion distance in the material to be heat treated. When the second heat treatment is performed on the pulverized product in particle form, a longer heat treatment time and a higher heat treatment temperature can be used, for example to accommodate a longer diffusion distance, compared to when the second heat treatment is performed on the pulverized product in sheet form.

[0114] The conditions of the second heat treatment can be determined according to the valence or oxidation number of M1 and M2. For example, the second heat treatment can be carried out in an oxidizing gas atmosphere, a reducing gas atmosphere or an inert gas atmosphere. The oxidizing gas atmosphere can be generated by, for example, air or oxygen. The reducing gas atmosphere can be generated by a reducing gas such as hydrogen. The inert gas atmosphere can be generated by an inert gas such as nitrogen, argon or helium.

[0115] The second heat treatment time may vary depending on the second heat treatment temperature. The second heat treatment time may be, for example, in the range of about 1 hour to about 50 hours, or, for example, in the range of about 4 hours to 48 hours.

[0116] Through the second heat treatment, a compound of Formula 1 may be obtained. When the temperature increase rates in the first heat treatment and the second heat treatment are within the disclosed ranges, the heat treatment may be sufficient to form a desired crystal structure and may also be economical due to reduced synthesis time.

[0117] In an embodiment, the solid electrolyte can be used as, for example, an electrolyte for a metal-air battery such as a lithium-air battery. The solid electrolyte can be used as an electrolyte for an all-solid-state battery or an electrolyte for a lithium battery. The solid electrolyte can be used to prepare the positive and negative electrodes of the battery. The solid electrolyte can be used to coat the surface of the positive and negative electrodes.

[0118] According to another aspect of the disclosure, an electrochemical device including the solid electrolyte is provided. By including the solid electrolyte that can be chemically stable and can conduct ions and electrons at the same time, stability to moisture and strong alkali can be improved, and thus degradation of the electrochemical device can be effectively suppressed.

[0119] In an embodiment, the electrochemical device may be, for example, a battery, an accumulator, a supercapacitor, a fuel cell, a sensor, an electrochromic device, or a combination thereof. However, the disclosed embodiments are not limited thereto. Any suitable device that can be used as an electrochemical device in the art can be used.

[0120] The battery may be, for example, a primary battery or a secondary battery. The battery may be, for example, a lithium battery, a sodium battery, etc. However, the disclosed embodiments are not limited thereto. The lithium battery may be, for example, a lithium ion battery or a lithium-air battery. However, the disclosed embodiments are not limited thereto. The electrochromic device may be an electrochemical mirror, a window, or a screen. However, the disclosed embodiments are not limited thereto.

[0121] The electrochemical device may be, for example, a lithium metal battery or a lithium-air battery. The battery includes a positive electrode, a negative electrode, and an electrolyte therebetween.

[0122] The positive electrode may be porous. Since the positive electrode is porous, diffusion of air or oxygen into the positive electrode may be facilitated.

[0123] According to another aspect of the disclosure, a lithium-air battery may include a positive electrode according to the disclosed embodiment, a negative electrode, and a solid electrolyte according to the disclosed embodiment, the solid electrolyte being interposed between the positive electrode and the negative electrode.

[0124] At least one of the negative electrode and the positive electrode may include the solid electrolyte according to an embodiment. The negative electrode may include lithium.

[0125] Since the lithium-air battery uses the solid electrolyte as described above, the lithium-air battery can have improved stability to moisture and strong alkali, and its reversibility is ensured under humid or air conditions, allowing the battery to operate smoothly. The lithium-air battery can have improved structural stability and its degradation can be suppressed.

[0126] In an embodiment, the lithium-air battery may include the positive electrode according to the embodiment. The positive electrode may be disposed on, for example, a positive electrode current collector.

[0127] In an embodiment, the positive electrode may include a solid electrolyte according to the disclosed embodiment. The amount of the solid electrolyte may be in the range of about 2 parts by weight to about 70 parts by weight, such as 3 parts by weight to 70 parts by weight, such as 3 parts by weight to about 60 parts by weight, such as about 10 parts by weight to about 60 parts by weight, each relative to 100 parts by weight of the positive electrode.

[0128] In manufacturing the positive electrode, a pore-forming agent may be used to introduce pores into the positive electrode. The positive electrode may be in the form of a porous disc, a porous sheet, etc. However, the positive electrode is not limited thereto. Depending on the shape of the battery, the positive electrode may have any suitable form.

[0129] For example, the positive electrode may be permeable to gases such as oxygen or air. Thus, the positive electrode is distinguished from a positive electrode that is substantially impermeable to gases such as oxygen or air, such as a positive electrode that conducts only ions. The positive electrode may be porous and / or permeable to gas, and thus oxygen or air may easily diffuse into the positive electrode. In addition, lithium ions and / or electrons may also easily migrate through the solid electrolyte included in the positive electrode. Thus, electrochemical reactions involving oxygen, lithium ions, and electrons may be promoted in the positive electrode.

[0130] In an embodiment, in the manufacture of the positive electrode, in addition to the solid electrolyte, a conductive (conductive) material may be further added to further improve the electronic conductivity and ionic conductivity. For example, the conductive material may be porous. Due to the porosity of the conductive material, air permeation can be promoted. The conductive material may be any material with porosity and / or conductivity available in the art. For example, the conductive material may be a carbonaceous material with porosity. The carbonaceous material may be, for example, carbon black, graphite, graphene, activated carbon, carbon fiber, or a combination thereof. However, embodiments are not limited thereto. Any suitable carbonaceous material available in the art may be used. The conductive material may be, for example, a metallic material. For example, the metallic material may be a metallic fiber, a metallic mesh, a metallic powder, or a combination thereof. The metallic powder may include, for example, copper, silver, nickel, or aluminum in powder form. The conductive material may be, for example, an organic conductive material. The organic conductive material may be, for example, a polyphenylene derivative, a polythiophene derivative, or a combination thereof. For example, the conductive material may be used alone or in combination. The positive electrode may include a composite conductor as the conductive material. In addition to the composite conductor, the positive electrode may further include any suitable conductive material.

[0131] In an embodiment, the positive electrode may further include a catalyst for oxidation / reduction of oxygen. Examples of the catalyst may include: a metal-based catalyst such as a catalyst including platinum, gold, silver, palladium, ruthenium, rhodium, osmium, or a combination thereof; an oxide-based catalyst such as manganese oxide, iron oxide, cobalt oxide, nickel oxide, or a combination thereof; an organometallic catalyst such as cobalt phthalocyanine. A combination including at least two of the foregoing may be used. However, embodiments are not limited thereto. Any suitable catalyst for oxidation / reduction of oxygen used in the art may be used.

[0132] In an embodiment, the catalyst may be disposed on a catalyst support. The catalyst support may be an oxide support, a zeolite support, a clay-based mineral support, a carbon support, or a combination thereof. The oxide support may be a metal oxide support including the following: aluminum (Al), zirconium (Zr), titanium (Ti), cerium (Ce), praseodymium (Pr), samarium (Sm), europium (Eu), terbium (Tb), thulium (Tm), ytterbium (Yb), antimony (Sb), bismuth (Bi), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), niobium (Nb), molybdenum (Mo), tungsten (W), or a combination thereof. Examples of the oxide support may include aluminum oxide, silicon dioxide, zirconium oxide, titanium dioxide, or a combination thereof. The oxide support may be a semi-metal oxide support including silicon (Si). Examples of the carbon carrier may include: carbon black such as Ketjen black, acetylene black, channel black, lamp black, or a combination thereof; graphite such as natural graphite, artificial graphite, expandable graphite, or a combination thereof; activated carbon; or carbon fiber. A combination including at least two of the foregoing may be used. However, embodiments are not limited thereto. Any suitable catalyst carrier available in the art may be used.

[0133] In an embodiment, the positive electrode may further include a binder. For example, the binder may include a thermoplastic resin or a heat curable resin. For example, the binder may include polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), styrene-butadiene rubber, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene copolymer or ethylene-acrylic acid copolymer, which may be used alone or in combination. However, embodiments are not limited thereto. Any suitable binder available in the art may be used.

[0134] In an embodiment, the positive electrode can be manufactured by mixing a conductive material, a catalyst for oxidation / reduction of oxygen, and a binder and adding a suitable solvent thereto to prepare a positive electrode slurry, and coating the positive electrode slurry on the surface of a substrate and drying the coated resultant, and optionally compression molding the dried product to improve the electrode density. For example, the substrate may be a positive electrode collector, a separator, or a solid electrolyte membrane. For example, the positive electrode collector may be a gas diffusion layer. The conductive material may be, for example, a composite conductor.

[0135] For example, depending on the type of the positive electrode, the catalyst for oxidation / reduction of oxygen and the binder may be omitted.

[0136] In an embodiment, the lithium-air battery may include a negative electrode. The negative electrode may include the solid electrolyte.

[0137] The negative electrode may include lithium.

[0138] The negative electrode may be, for example, a lithium metal film or a lithium-based alloy film. For example, the lithium-based alloy may be a lithium alloy including, for example, aluminum, tin, magnesium, indium, calcium, titanium, vanadium, or a combination thereof.

[0139] The lithium-air battery according to an embodiment may include an electrolyte between the positive electrode and the negative electrode, as described above.

[0140] For example, the electrolyte may be a solid electrolyte including a compound represented by Formula 1.

[0141] For example, in addition to the solid electrolyte, the electrolyte may further include a second solid electrolyte, a gel electrolyte, a liquid electrolyte, or a combination thereof. The second solid electrolyte, the gel electrolyte, and the liquid electrolyte are not particularly limited. Any suitable electrolyte available in the art may be used.

[0142] In an embodiment, the second solid electrolyte may include: a solid electrolyte including an ion conductive inorganic material, a solid electrolyte including a polymer ionic liquid (PIL) and a lithium salt, a solid electrolyte including an ion conductive polymer and a lithium salt, a solid electrolyte including an electron conductive polymer, or a combination thereof. However, the disclosed embodiments are not limited thereto. Any suitable solid electrolyte available in the art may be used.

[0143] For example, the ion conductive inorganic material may include a glass or amorphous metal ion conductor, a ceramic active metal ion conductor, a glass ceramic active metal ion conductor, or a combination thereof. However, the embodiment is not limited thereto. Any ion conductive inorganic material available in the art may be used. For example, the ion conductive inorganic material may be ion conductive inorganic particles or a pulverized product thereof, such as in the form of flakes.

[0144] For example, the ion conductive inorganic material may be BaTiO 3 , where 0≤a≤1Pb(Zr 1-a Ti a ) 3 (PZT), where 0≤x<1 and 0≤y<1 Pb 1-x La x Zr 1-y Ti y O 3 (PLZT), Pb(Mg 1 / 3 Nb 2 / 3 ) 3-PbTiO 3 (PMN-PT), HfO 2 , SrTiO 3 , SnO 2 , CeO 2 , Na 2 O, MgO, NiO, CaO, BaO, ZnO, ZrO 2 , Y 2 O 3 , Al 2 O 3 , TiO 2 , SiO 2 , SiC, lithium phosphate (Li 3 PO 4 ), lithium titanium phosphate (Li x Ti y (PO 4 ) 3 , where 0 < x < 2 and 0 < y < 3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO 4 ) 3 , where 0 < x < 2, 0 < y < 1, and 0 < z < 3), where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ a ≤ 1, and 0 ≤ b ≤ 1 of Li 1+x+y (Al a Ga 1-a ) x (Ti b Ge 1-b ) 2-x Si y P 3-y O 12 , lithium lanthanum titanate (Li x La y TiO 3 , where 0 < x < 2, and 0 < y < 3), lithium germanium thiophosphate (Li x Ge y P z S w , where 0 < x < 4, 0 < y < 1, 0 < z < 1, and 0 < w < 5), lithium nitride (Li x N y , where 0 < x < 4, and 0 < y < 2), based on SiS 2 glass (Li x Si y S z , where 0 < x < 3, 0 < y < 2, and 0 < z < 4), based on P 2 S 5 glass (Li x Py S z , where 0 < x < 3, 0 < y < 3, and 0 < z < 7), based on Li 2 O, LiF-based, LiOH-based, based on Li 2 CO 3 -based, based on LiAlO 2 -based, or based on Li 2 O - Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 -GeO 2 -based ceramics, garnet-based ceramics (Li 3+x La 3 M 2 O 12 , where 0 ≤ x ≤ 5, M = Te, Nb, or Zr), or combinations thereof.

[0145] For example, the polymer ionic liquid (PIL) may include: i) cations such as ammonium-based cations, pyrrolidine -based cations, pyridine -based cations, pyrimidine -based cations, imidazole -based cations, piperidine -based cations, pyrazole -based cations, azole -based cations, pyridazine -based cations, -based cations, sulfonium-based cations, triazole -based cations, or combinations thereof; and ii) anions selected from: BF 4 - 、PF 6 - 、AsF 6 - 、SbF 6 - 、AlCl 4 - 、HSO 4 - 、ClO 4 - 、CH 3 SO 3 - 、CF 3 CO 2 - 、(CF 3SO 2 ) 2 N - 、Cl - 、Br - 、I - 、SO 4 2- 、CF 3 SO 3 - 、(C 2 F 5 SO 2 )(CF 3 SO 2 )N - 、NO 3 - 、Al 2 Cl 7 - 、CH 3 COO - 、(CF 3 SO 2 ) 3 C - 、(CF 3 CF 2 SO 2 ) 2 N - 、(CF 3 ) 2 PF 4 - 、(CF 3 ) 3 PF 3 - 、(CF 3 ) 4 PF 2 - 、(CF 3 ) 5 PF - 、(CF 3 ) 6 P - 、SF 5 CF 2 SO 3 - 、SF 5 CHFCF 2 SO 3 - 、CF 3 CF 2 (CF 3 ) 2 CO - 、(CF 3 SO 2 )2 CH - , (SF 5 ) 3 C - ,(O(CF 3 ) 2 C 2 (CF 3 ) 2 O) 2 PO - , or a combination thereof. For example, the polymer ionic liquid (PIL) may be poly(trifluoromethanesulfonyl)imide (TFSI) (diallyldimethylammonium), poly(bis(trifluoromethanesulfonyl)imide 1-allyl-3-methylimidazole ), poly(bis(trifluoromethanesulfonyl)imide-N-methyl-N-propylpiperidinium ), or a combination thereof.

[0146] The ion-conducting polymer may include at least one ion-conducting repeating unit. Examples are derived from ether-based monomers, acryl-based monomers, methacryl-based monomers, siloxane-based monomers, or combinations thereof.

[0147] The ion-conducting polymer may include, for example, polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), polyvinyl sulfone, polypropylene oxide (PPO), polymethyl methacrylate, polyethyl methacrylate, polydimethylsiloxane, polyacrylic acid, polymethacrylic acid, poly(methyl acrylate), poly(ethyl acrylate), poly(2-ethylhexyl acrylate), poly(butyl methacrylate), poly(2-ethylhexyl methacrylate), poly(decyl acrylate), polyethylene vinyl acetate, phosphate polymer, polyester sulfide, polyvinylidene fluoride (PVdF), Li-substituted Nafion, or a combination thereof. However, the disclosed embodiments are not limited thereto. Any suitable ion-conducting polymer available in the art may be used.

[0148] The electron conductive polymer may be, for example, a polyphenylene derivative or a polythiophene derivative. However, the disclosed embodiments are not limited thereto. Any suitable electron conductive polymer available in the art may be used.

[0149] In an embodiment, the gel electrolyte may be obtained, for example, by adding a low molecular weight solvent to a solid electrolyte between the positive electrode and the negative electrode. The gel electrolyte may be a gel electrolyte obtained by further adding a low molecular weight organic compound such as a solvent or an oligomer to a polymer. The gel electrolyte may be a gel electrolyte obtained by further adding a low molecular weight organic compound such as a solvent or an oligomer to any suitable polymer electrolyte.

[0150] In an embodiment, the liquid electrolyte may include a solvent and a lithium salt.

[0151] The solvent may include an organic solvent, an ionic liquid (IL), an oligomer, or a combination thereof. However, the disclosed embodiments are not limited thereto. Any suitable solvent available in the art that is in a liquid form at room temperature (25° C.) may be used.

[0152] The organic solvent may include, for example, an ether-based solvent, a carbonate-based solvent, an ester-based solvent, a ketone-based solvent, or a combination thereof. For example, the organic solvent may include propylene carbonate, ethylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, dimethylacetamide, dimethyl sulfoxide, dimethyl sulfoxide, dimethyl ether ... The organic solvent may be any suitable organic solvent available in the art that is in liquid form at room temperature.

[0153] The ionic liquid (IL) may include, for example: i) ammonium-based cations, pyrrolidine-based Cations based on pyridine Cationic, pyrimidine-based Cation, imidazole-based Cation, based on piperidine Cations based on pyrazole Cations, based on Azoles Cationic, pyridazine-based Cations, based on cations based on sulfonium, cations based on triazole cations, or combinations thereof, and ii) anions such as BF 4 - PF 6 - , AsF 6 - , SbF 6 - 、AlCl 4 - , HSO4 - 、ClO 4 - 、CH 3 SO 3 - 、CF 3 CO 2 - 、(CF 3 SO 2 ) 2 N - 、Cl - 、Br - 、I - 、SO 4 2- 、CF 3 SO 3 - 、(C 2 F 5 SO 2 )(CF 3 SO 2 )N - 、NO 3 - 、Al 2 Cl 7 - 、CH 3 COO - 、(CF 3 SO 2 ) 3 C - 、(CF 3 CF 2 SO 2 ) 2 N - 、(CF 3 ) 2 PF 4 - 、(CF 3 ) 3 PF 3 - 、(CF 3 ) 4 PF 2 - 、(CF 3 ) 5 PF - 、(CF 3 ) 6 P - 、SF 5 CF 2 SO 3 - 、SF 5CHF 2 SO 3 - CF 3 CF 2 (CF 3 ) 2 CO - ,(CF 3 SO 2 ) 2 CH - , (SF 5 ) 3 C - ,(O(CF 3 ) 2 C 2 (CF 3 ) 2 O) 2 PO - , or a combination thereof.

[0154] The lithium salt may include lithium bis(trifluoromethanesulfonyl)imide (LiN(SO 2 CF 3 ) 2 , LiTFSI), LiPF 6 , LiBF 4 、LiAsF 6 、LiClO 4 、LiNO 3 , lithium bis(oxalate)borate (LiBOB), LiCF 3 SO 3 、LiN(SO 2 C 2 F 5 ) 2 、LiN(SO 2 F) 2 、LiC(SO 2 CF 3 ) 3 、LiN(SO 3 CF 3 ) 2 ,LiC 4 F 9 SO 3 、LiAlCl 4 , or a combination thereof. However, the disclosed embodiments are not limited thereto. Any suitable material that can be used as a lithium salt in the art can be used. The concentration of the lithium salt can be, for example, about 0.01 M to about 5.0 M.

[0155] In an embodiment, the lithium-air battery may further include a separator between the positive electrode and the negative electrode. Any suitable separator may be used, such as a separator having suitable durability under the operating conditions of the lithium-air battery. For example, the separator may include a polymer nonwoven fabric such as a nonwoven fabric of a polypropylene material or a nonwoven fabric of polyphenylene sulfide; a porous film of an olefin resin such as polyethylene or polypropylene; or glass fiber. The separator may be used in combination of at least two thereof.

[0156] For example, the electrolyte may have a structure in which a solid polymer electrolyte is impregnated in a separator, or a structure in which a liquid electrolyte is impregnated in a separator. For example, an electrolyte in which a solid polymer electrolyte is impregnated in a separator may be prepared by arranging a solid polymer electrolyte membrane on opposite surfaces of a separator and rolling them simultaneously. For example, when the electrolyte includes a liquid electrolyte impregnated in a separator, it may be prepared by injecting a liquid electrolyte including a lithium salt into the separator.

[0157] In an embodiment, the lithium-air battery may be manufactured by mounting the negative electrode on the inner side of the housing, sequentially arranging the electrolyte on the negative electrode, arranging the positive electrode on the electrolyte, and arranging a porous positive electrode collector on the positive electrode, and then arranging a pressing member on the porous positive electrode collector to press the resulting unit cell structure with the pressing member, thereby allowing air to be transmitted to the air electrode (i.e., the positive electrode). The housing may be divided into an upper portion and a lower portion that contact the negative electrode and the air electrode, respectively. An insulating resin may be provided between the upper portion and the lower portion of the housing to electrically insulate the positive electrode and the negative electrode from each other.

[0158] The lithium-air battery can be used as a lithium primary battery or a lithium secondary battery. The lithium-air battery can have any suitable shape, such as a coin, a button, a sheet, a stack, a cylinder, a plane, or an angular shape. However, the disclosed embodiments are not limited thereto. The lithium-air battery can be used in large batteries for electric vehicles.

[0159] Figure 5 2 is a schematic diagram illustrating the structure of a lithium-air battery 500 according to an embodiment.

[0160] Reference Figure 5 , a lithium-air battery 500 according to an embodiment may include a positive electrode 200 adjacent to a first current collector 210 and using oxygen as an active material, a negative electrode 300 adjacent to a second current collector 310 and including lithium, and a first electrolyte 400 interposed between the positive electrode 200 and the negative electrode 300. The first electrolyte 400 may be a separator impregnated with a liquid electrolyte.

[0161] The second electrolyte 450 may be disposed between the positive electrode 200 and the first electrolyte 400. The second electrolyte 450, which is a lithium ion conductive solid electrolyte membrane, may be a solid electrolyte according to the disclosed embodiment. The first current collector 210 may be porous and function as a gas diffusion layer that allows diffusion of air. A pressing member 220 for transmitting air to the positive electrode 200 may be disposed on the first current collector 210.

[0162] The housing 320 made of insulating resin may be Figure 5 Air may be supplied into the lithium-air battery 500 through the air inlet 230a and may be exhausted through the air outlet 230b. The lithium-air battery 500 may be housed in a stainless steel container.

[0163] The term "air" used herein is not limited to atmospheric air, and for convenience, may refer to a combination of gases including oxygen, or pure oxygen. This broad definition of the term "air" also applies to any other terms used herein including "air battery" and "air electrode".

[0164] The embodiments of the disclosure will now be described in further detail with reference to the following examples. However, these examples are for illustrative purposes only and are not intended to limit the scope of the disclosed embodiments.

[0165] Example

[0166] Formation of solid electrolyte

[0167] Comparative Example 1: LiHf 2 P 3 O 12

[0168] According to LiHf 2 P 3 O 12 The composition ratio of Li 2 CO 3 , HfO as a precursor of M1 2 , and (NH 4 ) 2 HPO 4 The precursor mixture was mixed in a stoichiometric ratio, and then ethanol was added thereto and mixed to obtain a precursor mixture. The precursor mixture was placed in a ball mill, and then pulverized and mixed for about 4 hours. The resulting mixture was dried, heated to about 900° C. at a rate of about 5° C. / min, and then subjected to a first heat treatment for about 12 hours in an air atmosphere.

[0169] The powder obtained by the first heat treatment was crushed and then pressed to form a sheet having a diameter of about 1.3 cm and a height of about 0.5 cm. The sheet was subjected to a second heat treatment at about 1200° C. for about 4 hours in an air atmosphere to obtain a target product. For the second heat treatment, the temperature was raised to 1200° C. at a heating rate of about 5° C. / min.

[0170] Example 1: Li 0.8 Hf 2 P 3 O 11.8 F 0.2

[0171] The solid electrolyte was prepared in the same manner as in Comparative Example 1, except that lithium fluoride (LiF) was further added in the preparation of the precursor mixture, and the amount of lithium fluoride was stoichiometrically controlled to obtain Li 0.8 Hf 2 P 3 O 11.8 F 0.2 , the first heat treatment is performed at about 800°C, and the second heat treatment is performed at about 1200°C.

[0172] Example 2: Li 0.8 Hf 2 P 3 O 11.8 Cl 0.2

[0173] The solid electrolyte was prepared in the same manner as in Comparative Example 1, except that lithium chloride (LiCl) was further added in the preparation of the precursor mixture, and the amount of lithium chloride was stoichiometrically controlled to obtain Li 0.8 Hf 2 P 3 O 11.8 Cl 0.2 , the first heat treatment is performed at about 800°C, and the second heat treatment is performed at about 1250°C.

[0174] Example 3: LiHf 1.9 Y 0.1 P 3 O 11.9 F 0.1

[0175] A solid electrolyte was prepared in the same manner as in Comparative Example 1, except that lithium fluoride (LiF) and yttrium oxide (Y 2 O 3 ), stoichiometrically controlling the amounts of lithium fluoride and yttrium oxide to obtain LiHf 1.9 Y 0.1 P 3 O11.9 F 0.1 , the first heat treatment is performed at about 850°C, and the second heat treatment is performed at about 1300°C.

[0176] Example 4: LiHf 1.9 Y 0.1 P 3 O 11.9 Cl 0.1

[0177] A solid electrolyte was prepared in the same manner as in Comparative Example 1, except that lithium chloride (LiCl) and yttrium oxide (Y 2 O 3 ), the amount of lithium chloride and yttrium oxide is stoichiometrically controlled to obtain LiHf 1.9 Y 0.1 P 3 O 11.9 Cl 0.1 , the first heat treatment is performed at about 850°C, and the second heat treatment is performed at about 1250°C.

[0178] Examples 5 and 6

[0179] A solid electrolyte having the composition in Table 1 was prepared in the same manner as in Example 1, except that zirconium oxide and titanium oxide were used instead of hafnium oxide (HfO 2 ) as M1 precursor, and the amount of each precursor is stoichiometrically controlled to obtain the target product. In Example 5, the first heat treatment and the second heat treatment are performed at about 900°C and about 1300°C, respectively. In Example 6, the first heat treatment and the second heat treatment are performed at about 900°C and about 1250°C, respectively.

[0180] Example 7

[0181] A solid electrolyte was prepared in the same manner as in Comparative Example 1, except that lithium chloride (LiCl) and lithium fluoride (LiF) were further added in preparing the precursor mixture, the amounts of lithium chloride and lithium fluoride were stoichiometrically controlled to obtain a solid electrolyte having a composition in Table 1, the first heat treatment was performed at about 900°C, and the second heat treatment was performed at about 1300°C.

[0182] Table 1

[0183] Example composition Example 5 <![CDATA[Li 0.8 Zr 2 P 3 O 11.8 F 0.2 ]]> Example 6 <![CDATA[Li 0.8 You 2 P 3 ON 11.8 F 0.2 ]]> Example 7 <![CDATA[Li 0.8 Hf 2 P 3 O 11.8 F 0.1 Cl 0.1 ]]>

[0184] Manufacturing Example 1:

[0185] After 40 parts by weight of carbon (Super-P), 10 parts by weight of polytetrafluoroethylene (PTFE) and 50 parts by weight of N-methylpyrrolidone (NMP) were mixed together to prepare a positive electrode slurry, the slurry was coated and roll-pressed to obtain a positive electrode mixed sheet. The positive electrode mixed sheet was pressed on a stainless steel mesh and then vacuum dried in an oven at 100°C for about 120 minutes to obtain a positive electrode.

[0186] A polypropylene-coated aluminum film (200 μm) having a size of about 5 cm×5 cm was perforated to form a hole of about 1 cm×1 cm at its center. The hole was blocked with the solid electrolyte of Example 1 having a size of about 1.4 cm×1.4 cm to thereby form a first aluminum film including the solid electrolyte of Example 1 as a part thereof. Next, a second aluminum film having a size of about 5 cm×5 cm, a copper current collector (having a thickness of about 20 μm), a lithium foil (having a size of about 1.4 cm×1.4 cm and a thickness of about 100 μm), a Celgard-3501 polypropylene separator (having a thickness of about 25 μm, available from Celgard) impregnated with an electrolyte solution of a mixture of 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and propylene carbonate (PC), and the first aluminum film prepared as above were stacked on top of each other and then vacuum heated to adhere together, thereby obtaining an aluminum bag type protected lithium negative electrode.

[0187] The protected lithium negative electrode was installed in a stainless steel case, and a positive electrode having a Celgard-3501 polypropylene separator (available from Celgard) with a thickness of about 25 μm was placed on the opposite side of the negative electrode. Subsequently, after a porous gas diffusion layer formed of carbon fibers was arranged on the positive electrode, a foamed nickel plate was arranged thereon, and then pressed with a pressing member to thereby manufacture a lithium-air battery.

[0188] Manufacturing Example 2-4: Manufacturing of Lithium-Air Battery

[0189] A lithium-air battery was manufactured in the same manner as in Manufacturing Example 1, except that the solid electrolytes of Examples 2 to 4 were used instead of the solid electrolyte of Example 1, respectively.

[0190] Comparative Manufacturing Example 1: Manufacturing of Lithium-Air Battery

[0191] A lithium-air battery was manufactured in the same manner as in Manufacturing Example 1, except that the solid electrolyte of Comparative Example 1 was used instead of the solid electrolyte of Example 1.

[0192] Evaluation Example 1: Evaluation by X-ray Diffraction

[0193] The X-ray diffraction (XRD) spectra of the solid electrolytes of Example 1, Example 2, Example 4 and Comparative Example 1 were evaluated. The results are shown in Figure 1 and 2 The XRD spectra were obtained using a Bruker D8 Advance diffractometer with Cu Kα radiation.

[0194] The XRD spectrum analysis results are shown in Figure 1 and 2 middle. Figure 2 illustrate Figure 1 An enlarged view of a portion at a diffraction angle (2θ) of about 20° 2θ in the XRD spectrum of FIG.

[0195] like Figure 1 As shown in Comparative Example 1 (LiHf 2 P 3 O 12 )、Example 1 (Li 0.8 Hf 2 P 3 O 11.8 F 0.2 )、Example 2 (Li 0.8 Hf 2 P 3 O 11.8 Cl 0.2 ), and Example 4 (LiHf 1.9 Y 0.1 P 3 O 11.9 Cl 0.1 ) all present very similar XRD patterns macroscopically and can be indexed as materials with a crystal structure isostructural to that of NASICON.

[0196] Reference Figure 2 , it is found that the solid electrolytes of Examples 1 and 2 have first and second diffraction peaks all shifted to the right by about 0.1°2θ compared to the solid electrolyte of Comparative Example 1. It is found that the solid electrolyte of Example 4 has first and second diffraction peaks A1 all shifted to the right by about 0.05°2θ compared to the solid electrolyte of Comparative Example 1. In particular, the solid electrolyte of Example 4 exhibits a second diffraction peak A2 at about 20.3°2θ.

[0197] In terms of peak intensity, when the intensity ratio (P2 / P1) of the second diffraction peak (2θ=20.16°) to the first diffraction peak (2θ=19.92°) in the solid electrolyte of Comparative Example 1 is 0.58, the intensity ratio (P2 / P1) of the second diffraction peak (2θ=20.16°) to the first diffraction peak (2θ=19.92°) in the solid electrolyte of Example 1 is 0.77, the intensity ratio (P2 / P1) of the second diffraction peak (2θ=20.16°) to the first diffraction peak (2θ=19.92°) in the solid electrolyte of Example 2 is 0.81, and the intensity ratio (P2 / P1) of the second diffraction peak (2θ=20.16°) to the first diffraction peak (2θ=19.92°) in the solid electrolyte of Example 4 is 1.26. In the solid electrolyte of Example 4, the second diffraction peak has a higher intensity than the intensity of the first diffraction peak.

[0198] Evaluation Example 2: Evaluation of ion conductivity

[0199] An electron-blocking cell was manufactured by arranging a separator film impregnated with a liquid electrolyte (1M LiTFSI in propylene carbonate (PC)) on opposite surfaces of the sheet prepared in Examples 1-4 (hereinafter, "sheet A") and the sheet prepared in Comparative Example 1 ("sheet B"), and then arranging a lithium foil thereon. Then, the ion conductivity of the electron-blocking cell was measured using a DC polarization method.

[0200] While applying a constant voltage of about 100 mV to each of the completed symmetrical unit cells for about 30 minutes, the time-dependent current of the unit cells was measured. The ionic resistance was calculated from the measured current, and the ionic conductivity was calculated from the ionic resistance.

[0201] After the sheet A or sheet B was immersed in a saturated lithium hydroxide aqueous solution at about 40° C. for about 6 days, the ion conductivity of the sheet A and the sheet B was evaluated in the same manner as that of the sheet A and the sheet B before the immersion. The results are shown in Tables 2 and Figure 3 middle.

[0202] Table 2

[0203]

[0204] Refer to Table 2 and Figure 3 It was found that the solid electrolytes of Examples 1-4 exhibited a greater ion conductivity retention after impregnation with a lithium hydroxide solution than the solid electrolyte of Comparative Example 1. From these results, it was found that the solid electrolytes of Examples 1-4 had significantly improved stability to moisture and strong alkali due to the introduction of anions such as fluoride ions and chloride ions and yttrium.

[0205] The ion conductivity retention of the solid electrolytes of Example 3 and Comparative Example 1 was evaluated. The results are shown in Figure 4 middle.

[0206] from Figure 4 The results in FIG. 2 show that the solid electrolyte of Example 3 has a greatly improved ion conductivity retention rate compared to the ion conductivity retention rate of the solid electrolyte of Comparative Example 1.

[0207] Evaluation Example 3: Evaluation of electrochemical stability

[0208] After the solid electrolyte of Example 1 is crushed into a size of about 1 μm to obtain a crushed compound, about 85 weight percent (wt%) of the crushed compound based on the total weight of the solid electrolyte, carbon black, and binder, about 10 weight % of carbon black as a conductive agent, and about 5 weight % of polyvinylidene fluoride (PVDF) as a binder are mixed with N-methyl-2-pyrrolidone to prepare a slurry. The prepared slurry is coated on an aluminum foil and then dried to thereby manufacture a working electrode. A separator impregnated with a liquid electrolyte (1M LiTFSI in propylene carbonate (PC)) is arranged between the working electrode and the lithium metal foil used as the counter electrode to thereby complete the manufacture of a half-cell battery.

[0209] Each half cell was analyzed by cyclic voltammetry (CV) over a voltage range of about 2 volts (V) to about 4 V (vs. Li) at a scan rate of about 0.1 millivolt / second (mV / sec) to evaluate the electrochemical stability of the solid electrolyte.

[0210] As a result, it was found that the solid electrolyte of Example 1 was electrochemically stable during 1 scan, 80 scans, or 100 scans without overcurrent caused by side reactions.

[0211] Evaluation Example 5: Evaluation of Charge-Discharge Characteristics of Lithium-Air Batteries

[0212] The lithium-air battery manufactured in Manufacturing Example 1 was subjected to the following charge-discharge cycle: at about 60° C. in an oxygen atmosphere of about 1 atm and at a current of about 0.01 mA / cm 2 The battery was discharged at a constant current of 1.5 V until the voltage reached 2.0 V (vs. Li), and then charged at the same constant current until the voltage reached 4.25 V. The results of the charge-discharge test at the first cycle of each lithium-air battery were evaluated.

[0213] As a result of the charge-discharge test, it was found that the lithium-air battery of Manufacturing Example 1 using the solid electrolyte of Example 1 operated stably. It was found that the lithium-air batteries of Manufacturing Examples 2-4 manufactured using the solid electrolytes of Examples 2-4, respectively, also operated stably like the lithium-air battery of Manufacturing Example 1.

[0214] The charge and discharge characteristics of the lithium-air batteries of Production Examples 2 to 4 were evaluated in the same manner as applied to the lithium-air battery of Production Example 1.

[0215] As a result of the charge and discharge characteristics analysis, it was found that the charge and discharge characteristics of the lithium-air batteries of Production Examples 2 to 4 were similar to those of the lithium-air battery of Production Example 1.

[0216] As described above, according to the disclosed embodiments, the solid electrolyte can be stable to strong alkali and moisture, and can have excellent ion conductivity even when in contact with a strong alkali. By using such a solid electrolyte, an electrochemical device in which degradation is suppressed can be manufactured.

[0217] It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for limiting purposes. The description of features, aspects, or advantages within each embodiment should be considered applicable to other similar features, aspects, or advantages in other embodiments. Although the embodiments have been described with reference to the accompanying drawings, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope as defined by the appended claims.

Claims

1. A solid electrolyte, comprising: a compound represented by Formula 1, Formula 1 Yes x M1 2-y M2 y (PO 4-z X z )3 wherein, in Formula 1, M1 is hafnium, titanium, or a combination thereof, M2 is aluminum, lanthanum, scandium, cerium, praseodymium, gadolinium, europium, yttrium, or a combination thereof, X is a halogen atom, pseudohalogen, or a combination thereof, 0 < x < 8, 0 ≤ y < 1, and 0 < z < 4.

2. The solid electrolyte according to claim 1, wherein X is chlorine, bromine, fluorine, cyanide, cyanate, thiocyanate, azide, or a combination thereof.

3. The solid electrolyte according to claim 1, wherein In Formula 1, X 3z is F n , Br n , Cl n , (F a Cl 1-a ) n , (F a Br 1-a ) n , or (Cl a Br 1-a ) n , n is 1 or less, and a is from 0.01 to 0.

99.

4. The solid electrolyte according to claim 1, wherein the solid electrolyte has a crystal structure isomorphic to NASICON.

5. The solid electrolyte according to claim 1, wherein In Formula 1, x is from 0.5 to 1.5, y is from 0 to 0.8, and z is greater than 0 and less than or equal to 1.

6. The solid electrolyte according to claim 1, wherein the compound represented by Formula 1 is a compound represented by Formula 2 or a compound represented by Formula 3: Formula 2 <h2 style=";text-align:left;direction:ltr">Li<h2 style=";text-align:left;direction:ltr"> 1+y-3z <h2 style=";text-align:left;direction:ltr"> Hf<h2 style=";text-align:left;direction:ltr"> 2-y <h2 style=";text-align:left;direction:ltr"> M2<h2 style=";text-align:left;direction:ltr"> y <h2 style=";text-align:left;direction:ltr"> (PO<h2 style=";text-align:left;direction:ltr"> 4-z <h2 style=";text-align:left;direction:ltr"> X<h2 style=";text-align:left;direction:ltr"> z <h2 style=";text-align:left;direction:ltr"> 3) in, wherein, in Formula 2, M2 is aluminum, lanthanum, scandium, cerium, praseodymium, gadolinium, europium, yttrium, or a combination thereof, X is a halogen atom, pseudohalogen, or a combination thereof, 0 ≤ y < 1, and 0 < z < 4, or Formula 3 The 1+y-3z Ti 2-y M2 y (MONTH 4-z X z )3 wherein, in Formula 3, M2 is aluminum, lanthanum, scandium, cerium, praseodymium, gadolinium, europium, yttrium, or a combination thereof, X is a halogen atom, pseudohalogen, or a combination thereof, 0 ≤ y < 1, and 0 < z < 4.

7. The solid electrolyte according to claim 6, wherein In Formulas 2 to 3, 1 + y - 3z is from 0.5 to 1.5, y is from 0 to 0.8, and z is greater than 0 and less than or equal to 1.

8. The solid electrolyte according to claim 1, wherein the compound represented by Formula 1 is Li 0.8 Hf2P3O 11.8 F 0.2 , Li 0.8 Hf2P3O 11.8 Cl 0.2 、LiHf 1.9 Y 0.1 P3O 11.9 F 0.1 、LiHf 1.9 Y 0.1 P3O 11.9 Cl 0.1 , Li 0.8 Hf2P3O 11.8 Br 0.2 , Li 0.8 Hf2P3O 11.8 Br 0.1 F 0.1 , Li 0.8 Hf2P3O 11.8 Br 0.1 Cl 0.1 、LiHf 1.9 Y 0.1 P3O 11.9 Br 0.1 、LiHf 1.9 Y 0.1 P3O 11.9 Br 0.05 F 0.05 、LiHf 1.9 Y 0.1 P3O 11.9 Br 0.05 Cl 0.05 , Li 0.8 Ti2P3O 11.8 F 0.2 , Li 0.8 Ti2P3O 11.8 Cl 0.2 、LiTi 1.9 Y 0.1 P3O 11.9 F 0.1 、LiTi 1.9 Y 0.1 P3O 11.9 Cl 0.1 , Li 0.8 Ti2P3O 11.8 Br 0.2 , Li 0.8 Ti2P3O 11.8 Cl 0.2 、LiTi 1.9 Y<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> F<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiTi<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Y<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> Li<h2 style=";text-align:left;direction:ltr"> 0.8 <h2 style=";text-align:left;direction:ltr"> Ti2P3O<h2 style=";text-align:left;direction:ltr"> 11.8 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> F<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> Li<h2 style=";text-align:left;direction:ltr"> 0.8 <h2 style=";text-align:left;direction:ltr"> Ti2P3O<h2 style=";text-align:left;direction:ltr"> 11.8 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiTi<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Y<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiTi<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Y<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> F<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> LiTi<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Y<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Al<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> F<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Al<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Al<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> F<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Al<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Al<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> No<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> F<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> No<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> No<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> F<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> No<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> No<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Gd<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> F<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Gd<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> F<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Gd<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Gd<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Al<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> F<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> LiHf<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Al<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> LiTi<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Al<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> F<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiTi<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Gd<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiTi<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Gd<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> F<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> LiTi<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Gd<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Br<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> 0.05 <h2 style=";text-align:left;direction:ltr"> LiTi<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> Al<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> LiTi<h2 style=";text-align:left;direction:ltr"> 1.9 <h2 style=";text-align:left;direction:ltr"> No<h2 style=";text-align:left;direction:ltr"> 0.1 <h2 style=";text-align:left;direction:ltr"> P3O<h2 style=";text-align:left;direction:ltr"> 11.9 <h2 style=";text-align:left;direction:ltr"> F 0.1 , LiTi 1.9 La 0.1 P3O 11.9 Cl 0.1 , LiTi 1.9 Gd 0.1 P3O 11.9 F 0.1 , LiTi 1.9 Gd 0.1 P3O 11.9 Br 0.1 , LiTi 1.9 Gd 0.1 P3O 11.9 Br 0.05 F 0.05 , LiTi 1.9 Gd 0.1 P3O 11.9 Br 0.05 Cl 0.05 , LiTi 1.9 Gd 0.1 P3O 11.9 Cl 0.1 , Li 0.8 Hf2P3O 11.8 F 0.1 Cl 0.1 , LiHf 1.9 Y 0.1 P3O 11.9 F 0.05 Cl 0.05 , Li 0.8 Ti2P3O 11.8 F 0.1 Cl 0.1 , LiTi 1.9 Y 0.1 P3O 11.9 F 0.05 Cl 0.05 , or a combination thereof.

9. The solid electrolyte according to claim 1, wherein the solid electrolyte has a thickness of 1×10 -5 Ionic conductivity of Siemens / cm or greater.

10. The solid electrolyte according to claim 1, wherein the retention rate of the ionic conductivity of the solid electrolyte in a saturated lithium hydroxide solution is 50% or greater.

11. The solid electrolyte according to claim 1, wherein when analyzed by X-ray diffraction using CuKα radiation, the solid electrolyte exhibits a first diffraction peak having a maximum point at a diffraction angle of 19.93° 2θ to 19.99° 2θ, and a second diffraction peak having a maximum point at a diffraction angle of 20.17° 2θ to 20.25° 2θ.

12. The solid electrolyte according to claim 11, wherein the intensity ratio of the second diffraction peak to the first diffraction peak is less than 1.

13. The solid electrolyte according to claim 1, wherein when analyzed by X-ray diffraction using CuKα radiation, the solid electrolyte exhibits a first diffraction peak having a maximum point at a diffraction angle of 19.93° 2θ to 19.99° 2θ, and a second diffraction peak having a double-peak shape, and wherein the second diffraction peak includes a peak having a first maximum point at 20.15° 2θ to 20.25° 2θ and a peak having a maximum point at 20.26° 2θ to 20.32° 2θ.

14. The solid electrolyte according to claim 13, wherein the intensity ratio of the peak having the first maximum point at 20.15° 2θ to 20.25° 2θ to the first diffraction peak is greater than 1.

15. The solid electrolyte according to claim 13, wherein the intensity ratio of the peak having a maximum point at 20.26° 2θ to 20.32° 2θ to the first diffraction peak is greater than 1.

16. The solid electrolyte according to claim 1, wherein the solid electrolyte has a -6 Ionic conductivity at 25°C of Siemens / cm or more.

17. The solid electrolyte according to claim 1, wherein M2 is a trivalent element, X is a halogen atom, 0 ≤ y < 0.1, and 0 < z < 0.

2.

18. A lithium-air battery, comprising: a positive electrode; a negative electrode; and an electrolyte disposed between the positive electrode and the negative electrode, wherein the electrolyte comprises the solid electrolyte according to any one of claims 1-17.

19. The lithium-air battery according to claim 18, wherein at least one of the positive electrode and the negative electrode comprises a solid electrolyte including a compound of Formula 1: Formula 1 Yes x M1 2-y M2 y (PO 4-z X z )3 in, In Formula 1, M1 is a tetravalent element, M2 is a monovalent element, divalent element, trivalent element, tetravalent element, pentavalent element, hexavalent element, or a combination thereof, X is a halogen atom, pseudohalogen, or a combination thereof, 0 < x < 8, 0 ≤ y < 1, and 0 < z < 4.

20. An electrochemical device, comprising the solid electrolyte according to any one of claims 1-17.

21. The electrochemical device according to claim 20, comprising a battery, a supercapacitor, a sensor, an electrochromic device, or a combination thereof.

22. The electrochemical device according to claim 20, comprising a storage battery, a fuel cell, or a combination thereof.

23. A method for preparing the solid electrolyte according to any one of claims 1-17, the method comprising: providing a lithium precursor, an M1 precursor, an X precursor, a phosphorus precursor, and optionally an M2 precursor to prepare a precursor mixture; and performing a heat treatment on the precursor mixture to prepare a solid electrolyte including a compound represented by Formula 1 Formula 1 Yes x M1 2-y M2 y (PO 4-z X z )3 wherein, in Formula 1, M1 is hafnium, titanium, or a combination thereof, M2 is aluminum, lanthanum, scandium, cerium, praseodymium, gadolinium, europium, yttrium, or a combination thereof, X is a halogen atom, pseudohalogen, or a combination thereof, 0 < x < 8, 0 ≤ y < 1, and 0 < z < 4.

24. The method according to claim 23, wherein the precursor mixture comprises an M2 precursor.

25. The method according to claim 23, wherein the heat treatment comprises a first heat treatment at 400 °C to 950 °C.

26. The method according to claim 25, further comprising crushing the product from the first heat treatment to obtain a crushed product; and performing a second heat treatment on the crushed product.

27. The method according to claim 26, wherein the second heat treatment is performed at 500 °C to 1300 °C.

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