Solid electrolyte, method for preparing the same, protective layer for lithium battery, metal-air battery and electrochemical device

Abstract

The present invention relates to a solid electrolyte, a method for preparing the same, a protective layer for a lithium battery, a metal-air battery, and an electrochemical device. The solid electrolyte includes: an oxide represented by Formula 1, Formula 2, Formula 3, or a combination thereof, wherein, in Formula 1, M1 is hafnium, titanium, zirconium, or a combination thereof, and 0 < x < 1; wherein, in Formula 2, M1 is hafnium, titanium, zirconium, or a combination thereof, M2 is at least one element having an oxidation value of a, and wherein a is an integer from 1 to 6, and 0 < y < 1; or wherein, in Formula 3, M1 is hafnium, titanium, zirconium, or a combination thereof, X is a halogen, a pseudohalogen, or a combination thereof, and 0 < z < 2. Formula 1 Li 2+4x M1 1‑x O3 Formula 2 Li 2‑y(a‑4) M1 1‑ y M2 a y O3 Formula 3 Li 2‑z M1O 3‑z X z

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority and benefit of U.S. Provisional Application No. 62 / 942,498, filed on December 2, 2019, and Korean Patent Application No. 10 - 2019 - 0160968, filed on December 5, 2019, with the Korean Intellectual Property Office, and all benefits arising therefrom, the contents of which are hereby incorporated by reference in their entirety. Technical field

[0003] The present disclosure relates to a solid electrolyte, a method for preparing the same, a metal - air battery including the solid electrolyte, and an electrochemical device including the solid electrolyte. Background art

[0004] A lithium - air battery uses lithium metal as a negative electrode active material, and since air is used as a positive electrode active material, there is no need to store air, and thus the lithium - air battery can function as a high - capacity battery. The theoretical specific energy of a lithium - air battery is 3500 watt - hours per kilogram (Wh / kg) or greater, which is very high.

[0005] However, there is still a need for an improved solid electrolyte for lithium - air batteries. Summary of the invention

[0006] Provided are a solid electrolyte that is stable in the presence of moisture and lithium metal and a method for preparing the same.

[0007] Provided is a lithium - air battery including the solid electrolyte.

[0008] Provided is an electrochemical device including the solid electrolyte.

[0009] Additional aspects will be set forth in part in the description that follows and in part will be apparent from the description.

[0010] According to one aspect, the solid electrolyte includes an oxide represented by Formula 1, Formula 2, Formula 3, or a combination thereof,

[0011] Formula 1

[0012] Li 2+4x M1 1-x O 3

[0013] Wherein, in Formula 1, M1 is hafnium (Hf), titanium (Ti), zirconium (Zr), or a combination thereof, and 0 < x < 1;

[0014] Formula 2

[0015] Li 2-y(a-4) M11-y M2 a y O 3

[0016] Wherein, in Formula 2,

[0017] M1 is hafnium (Hf), titanium (Ti), zirconium (Zr), or a combination thereof,

[0018] M2 is at least one element having an oxidation value of a, where a is an integer from 1 to 6, and 0 < y < 1; or

[0019] Formula 3

[0020] Li 2-z M1O 3-z X z

[0021] Wherein, in Formula 3,

[0022] M1 is hafnium (Hf), titanium (Ti), zirconium (Zr), or a combination thereof,

[0023] X is a halogen, a pseudohalogen, or a combination thereof, and 0 < z < 2.

[0024] According to one aspect, a metal-air battery includes: a positive electrode, a negative electrode, and an electrolyte between the positive electrode and the negative electrode, wherein the positive electrode, the negative electrode, the electrolyte, or a combination thereof includes the solid electrolyte.

[0025] According to one aspect, an electrochemical device includes a negative electrode, a positive electrode, and the solid electrolyte between the negative electrode and the positive electrode.

[0026] The electrochemical device may include a battery, a storage battery, a supercapacitor, a fuel cell, a sensor, or an electrochromic device.

[0027] According to one aspect, a method for preparing a solid electrolyte includes: mixing a lithium precursor and an M1 precursor to prepare a precursor mixture; and heat-treating the precursor mixture to prepare the solid electrolyte, and optionally adding an M2 precursor and an X precursor to the precursor mixture.

[0028] A protective layer for a lithium battery is also disclosed, the protective layer including the solid electrolyte, wherein the solid electrolyte is disposed on the positive electrode or the negative electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other aspects, features, and advantages of some embodiments of the present disclosure will become more apparent from the following description when considered in conjunction with the accompanying drawings, wherein:

[0030] Figure 1A graph of intensity (in arbitrary units (a.u.)) versus diffraction angle (°, 2θ), showing the results of X-ray diffraction (XRD) analysis of the solid electrolytes of Examples 3 to 5, 7, 9, 12, 13, 20, and Comparative Example 1 when analyzed by X-ray diffraction (XRD) using CuKα radiation;

[0031] Figure 2 A graph of pellet (disk) density (grams per cubic centimeter (g / cc)), showing the pellet density of the solid electrolytes of Examples 1 to 12 and Comparative Example 1;

[0032] Figure 3 A graph of ionic conductivity (log Siemens per centimeter (log(S / cm))), showing the ionic conductivity of the solid electrolytes of Examples 1 to 12 and Comparative Example 1;

[0033] Figure 4 A graph of ionic conductivity (log Siemens per centimeter (log(S / cm))), showing the ionic conductivity of the solid electrolytes of Examples 13 to 23 and Comparative Example 2;

[0034] Figure 5 A schematic cross-sectional view of an embodiment illustrating the structure of a lithium-air battery; and

[0035] Figure 6 A schematic cross-sectional view of an embodiment illustrating the structure of a lithium-air battery. Detailed Description of the Embodiments

[0036] The embodiments will now be described in detail. Examples thereof 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. Accordingly, the embodiments are described below only by way of example with reference to the accompanying 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 the individual elements of the list.

[0037] The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which various embodiments are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art.

[0038] It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, no intervening element is present.

[0039] 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 sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another. Thus, a “first element,” “component,” “region,” “layer,” or “section” discussed below may be referred to as a second element, component, region, layer, or section without departing from the teachings herein.

[0040] The terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting. As used herein, “a,” “an,” “the,” and “at least one” do not denote a limitation of quantity and are intended to cover both the singular and the plural, unless the context clearly dictates otherwise. For example, “an element” has the same meaning as “at least one element” unless the context clearly dictates otherwise. “At least one” will not be construed as limiting “a” or “an.” “Or” means “and / or.” It will be further understood that the terms “comprises” or “comprising,” when used in this specification, specify the presence of the stated features, regions, wholes, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components, and / or groups thereof.

[0041] In addition, relative terms such as “lower” or “bottom” and “upper” or “top” may be used herein to describe the relationship of one element to another as shown in the figures. It will be understood that relative terms are intended to include different orientations of the device in addition to the orientation shown in the figures. For example, if the device in one of the figures is turned over, an element described as on the “lower” side of another element will then be oriented on the “upper” side of the other element. Thus, depending on the particular orientation of the figure, the exemplary term “lower” can include both the “lower” and the “upper” orientations. Similarly, if the device in one of the figures is turned over, an element described as “under” or “beneath” another element will then be oriented “above” the other element. Thus, the exemplary terms “under” or “beneath” can include both above and under orientations.

[0042] As used herein, "about" or "approximately" includes the stated value and means within an acceptable deviation range for a particular value as determined by one of ordinary skill in the art in view of the measurements discussed and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or within ±30%, 20%, 10%, or 5%.

[0043] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted in an idealized or overly formal sense unless clearly so defined herein.

[0044] Exemplary embodiments are described herein with reference to cross-sectional views that are schematic illustrations of idealized embodiments. Accordingly, deviations from the shapes of the figures as a result of, for example, manufacturing techniques and / or tolerances are to be expected. Thus, the embodiments described herein should not be construed as limited to the particular shapes of regions illustrated herein, but include deviations in shapes resulting from, for example, manufacturing. For example, regions illustrated or described as flat may typically have rough and / or non-linear features. Also, sharp corners illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the exact shape of a region and are not intended to limit the scope of the claims.

[0045] The solid electrolyte of a lithium-air battery may be unstable in the presence of LiOH, which is a discharge product of the lithium-air battery. The ionic conductivity of the solid electrolyte decreases under strongly basic conditions including the presence of lithium hydroxide. Accordingly, there is a need for an improved solid electrolyte with improved stability.

[0046] Hereinafter, the solid electrolyte, its preparation method, a metal-air battery including the solid electrolyte, and an electrochemical device including the solid electrolyte will be described in more detail.

[0047] Provided is a solid electrolyte comprising an oxide represented by Formula 1, Formula 2, Formula 3, or a combination thereof.

[0048] Formula 1

[0049] Li 2+4x M1 1-x O 3

[0050] In Formula 1, M1 is hafnium (Hf), titanium (Ti), zirconium (Zr), or a combination thereof, and 0 < x < 1.

[0051] Formula 2

[0052] Li 2-y(a-4) M1 1-y M2 a y O 3

[0053] In Formula 2, M1 is hafnium (Hf), titanium (Ti), zirconium (Zr), or a combination thereof,

[0054] M2 is at least one element having an oxidation value of a,

[0055] where a is an integer from 1 to 6, and 0 < y < 1.

[0056] Formula 3

[0057] Li 2-z M1O 3-z X z

[0058] In Formula 3, M1 is hafnium (Hf), titanium (Ti), zirconium (Zr), or a combination thereof, X is a halogen, pseudohalogen, or a combination thereof, and 0 < z < 2.

[0059] In Formulas 1 to 3, each M1 is independently hafnium (Hf), titanium (Ti), zirconium (Zr), or a combination thereof.

[0060] In Formula 2, M2 is aluminum (Al), gallium (Ga), indium (In), niobium (Nb), tantalum (Ta), vanadium (V), yttrium (Y), lanthanum (La), scandium (Sc), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), tungsten (W), molybdenum (Mo), or a combination thereof.

[0061] In Formula 2, a is the oxidation value of M2 and is, for example, 2, 3, 5, or 6.

[0062] In Formula 3, the halogen can be Cl, Br, F, I, or a combination thereof.

[0063] The solid electrolyte satisfies charge balance to have a neutral state.

[0064] The solid electrolyte is suitable for a lithium-air battery and has excellent stability in the presence of lithium metal, and the reversibility of the lithium-air battery is improved in humid or atmospheric conditions. Although not wishing to be bound by theory, it is understood that the improved stability and reversibility are because the solid electrolyte is an excellent ionic conductor and is stable to moisture and strong bases. Thus, the stability of the solid electrolyte is improved in the presence of moisture and lithium hydroxide (LiOH) as a discharge product.

[0065] However, solid electrolytes in the prior art do not have sufficient stability towards lithium and have low stability towards strong bases such as lithium hydroxide and moisture, thereby reducing the ionic conductivity. Therefore, there is an increasing need for new solid electrolytes that can solve such problems.

[0066] Solid electrolytes comprising oxides represented by Formulas 1 to 3 containing elements such as hafnium, titanium, or zirconium provide improved stability in the presence of both moisture and lithium.

[0067] The oxides are ionic conductors with a thermodynamically stable composition. Although not wishing to be bound by theory, it is understood that the oxide of Formula 1 provides improved ionic conductivity by introducing Li vacancies for lithium migration and having an excess of lithium, or by doping the oxide with other transition metals. When Formula 3 includes anions such as halogens, pseudohalogens, or combinations thereof, the solid electrolyte comprising the oxide of Formula 3 has excellent ionic conductivity.

[0068] The solid electrolyte contains the oxides of Formulas 1 to 3 and provides improved phase stability. In particular, the solid electrolyte has excellent stability towards moisture under strongly basic conditions, such as when the pH is 12 to 13, and maintains excellent ionic conductivity.

[0069] The oxides of Formulas 1 to 3 each contain elements such as hafnium, titanium, or zirconium that are not reduced by lithium and have very high stability in the presence of lithium metal. Although not wishing to be bound by theory, it is understood that hafnium, titanium, or zirconium results in an interface between the solid electrolyte and the negative electrode with improved stability. In addition, when the solid electrolyte includes the oxides of Formulas 1 to 3, the solid electrolyte has improved stability in the presence of moisture and strong bases. Therefore, the interface between the solid electrolyte and the positive electrode is also stabilized.

[0070] The solid electrolyte according to an embodiment has excellent ionic conductivity at room temperature and has excellent stability in the presence of lithium metal and moisture. Therefore, a metal-air battery with improved reversibility under humid or air conditions can be manufactured.

[0071] The metal-air battery can be a lithium-air battery configured to use oxygen from air or any other suitable gas as the positive electrode active material and lithium as the negative electrode.

[0072] In Formulas 1 to 3, M1 can be a tetravalent cationic element such as hafnium (Hf), titanium (Ti), zirconium (Zr), or a combination thereof.

[0073] In Formula 2, M2 can replace part of the crystallographic position of M1 in the crystal structure of the oxide. M2 is an element with an oxidation value of a, and can be a monovalent element to a hexavalent element, or a combination thereof. In Formula 2, M2 can be a divalent element, a trivalent element, a pentavalent element, a hexavalent element, or a combination thereof.

[0074] M2 can be aluminum (Al), gallium (Ga), indium (In), niobium (Nb), tantalum (Ta), vanadium (V), yttrium (Y), lanthanum (La), scandium (Sc), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), tungsten (W), molybdenum (Mo), or a combination thereof.

[0075] In Formula 3, X can be a halogen, a pseudohalogen, or a combination thereof.

[0076] As used herein, "pseudohalogen" refers to a group or molecule including two or more electronegative atoms that is similar to a free halogen and provides an anion similar to a halide ion. Pseudohalogens can be, for example, cyanide, cyanate, thiocyanate, azide, or a combination thereof.

[0077] X can be two or more halogens. The halogens can replace part of the crystallographic position of oxygen in the crystal structure of Formula 3.

[0078] X can be chlorine (Cl), bromine (Br), fluorine (F), cyanide, cyanate, thiocyanate, azide, or a combination thereof.

[0079] In Formula 1, x can be from about 0.01 to about 0.99, from about 0.01 to about 0.97, from about 0.01 to about 0.95, or from about 0.01 to about 0.9.

[0080] In Formula 2, y is greater than 0 to less than about 1, from about 0.01 to about 0.9, from about 0.03 to about 0.85, or from about 0.05 to about 0.8.

[0081] In Formula 2, M2 can be Y, Al, Ta, Mg, Zn, or a combination thereof.

[0082] In Formula 1, x is greater than 0 to less than about 1, from about 0.01 to about 0.9, from about 0.05 to about 0.8, from about 0.1 to about 0.6, or from about 0.2 to about 0.5. Further, 2 + 4x is greater than about 2 to less than about 6, from about 2.05 to about 5.5, from about 2.05 to about 5, from about 2.1 to about 4, from about 2.1 to about 3, or from about 2.1 to about 2.5. In Formula 2, y is greater than 0 to less than about 1, from about 0.01 to about 0.9, from about 0.05 to about 0.8, from about 0.07 to about 0.5, from about 0.09 to about 0.3, or from about 0.1 to about 0.2. In Formula 2, a is an oxidation value of 1 to 6, such as 2, 3, 5, or 6.

[0083] In Formula 3, z is greater than 0 to about 1, about 0.05 to about 1, about 0.07 to about 0.9, about 0.09 to about 0.8, or about 0.1 to about 0.5.

[0084] The oxide of Formula 1 can be the oxide represented by Formula 4, the oxide represented by Formula 5, or a combination thereof.

[0085] Formula 4

[0086] Li 2+4x Hf 1-x O 3

[0087] In Formula 4, 0.01 ≤ x ≤ 0.9.

[0088] Formula 5

[0089] Li 2+4x Zr 1-x O 3

[0090] In Formula 5, 0.01 ≤ x ≤ 0.9.

[0091] The oxide of Formula 2 can be the oxide represented by Formula 6, the oxide represented by Formula 7, or a combination thereof.

[0092] Formula 6

[0093] Li 2-y(a-4) Hf 1-y M2 a y O 3

[0094] In Formula 6, M2 is aluminum (Al), gallium (Ga), indium (In), niobium (Nb), tantalum (Ta), vanadium (V), yttrium (Y), lanthanum (La), scandium (Sc), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), tungsten (W), molybdenum (Mo), or a combination thereof. In Formula 6, a is the oxidation value of M2, and a can be an integer from 1 to 6, and 0.05 ≤ y ≤ 0.9.

[0095] Formula 7

[0096] Li 2-y(a-4) Zr 1-y M2 a y O 3

[0097] In Formula 7, M2 is aluminum (Al), gallium (Ga), indium (In), niobium (Nb), tantalum (Ta), vanadium (V), yttrium (Y), lanthanum (La), scandium (Sc), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), tungsten (W), molybdenum (Mo), or a combination thereof. In Formula 7, a is the oxidation value of M2 and is an integer from 1 to 6 such as 2, 3, 5, or 6, and 0.05 ≤ y ≤ 0.9.

[0098] The oxide of Formula 3 can be the oxide represented by Formula 8, the oxide represented by Formula 9, or a combination thereof.

[0099] Formula 8

[0100] Li 2-z HfO 3-z X z

[0101] In Formula 8, X is a halogen, pseudohalogen, or a combination thereof, and 0.05 ≤ z ≤ 1.

[0102] Formula 9

[0103] Li 2-z ZrO 3-z X z

[0104] In Formula 9, X is a halogen, pseudohalogen, or a combination thereof, and 0.05 ≤ z ≤ 1.

[0105] In Formulas 4 and 5, each x is independently from about 0.1 to about 0.8, from about 0.1 to about 0.6, or from about 0.1 to about 0.5.

[0106] In Formulas 6 and 7, each y is independently from about 0.1 to about 0.8, from about 0.1 to about 0.5, from about 0.1 to about 0.3, or from about 0.1 to about 0.2. In Formulas 6 and 7, a is the oxidation value of M2, and a is from 1 to 6 such as 2, 3, 5, or 6.

[0107] In Formulas 8 and 9, each z is independently from about 0.1 to about 0.9, from about 0.1 to about 0.8, or from about 0.1 to about 0.5.

[0108] The solid electrolyte may have a phase having a rock salt crystal structure. The solid electrolyte may have a layered rock salt crystal structure and may have a C2 / c space group (space group 15). Such characteristics can be confirmed by X-ray diffraction (XRD) analysis.

[0109] In the solid electrolyte according to the embodiment, when analyzed by X-ray diffraction using Cu Kα radiation, the spectrum has from crystal planes, crystal planes and / or crystal plane or related to crystal plane, crystal plane or diffraction peaks related to the crystal plane.

[0110] According to the embodiment, when analyzed by X-ray diffraction using Cu Kα radiation, the oxide has diffraction peaks at diffraction angles of 26.7 ± 0.5° 2θ, 35 ± 0.5° 2θ, and / or 39 ± 0.5° 2θ that are different from those of the oxide based on Li 2 HfO 3 Among the diffraction peaks, the first peak with a diffraction angle 2θ of 26.7 ± 0.5° 2θ is related to the

[0111] crystal plane of the oxide of Formula 1, and the second peak with a diffraction angle 2θ of 35 ± 0.5° 2θ is related to the crystal plane of the oxide of Formula 1. The third peak with a diffraction angle of 39 ± 0.5° 2θ is related to the crystal plane of the oxide of Formula 1. crystal plane of the oxide of Formula 1.

[0112] The oxide represented by Formula 1 may be Li 2.2 Hf 0.95 O 3 、Li 1.9 HfF 0.1 O 2.9 、Li 1.8 HfF 0.2 O 2.8 、Li 1.5 HfF 0.5 O 2.5 、Li 1.9 HfCl 0.1 O 2.9 、Li 1.8 HfCl 0.2 O 2.8 、Li 1.5 HfCl 0.5 O 2.5 、Li 1.9 HfF 0.05 Cl 0.05 O 2.9 、Li 1.8 HfF 0.1 Cl 0.1 O 2.8 、Li 1.8 HfBr 0.1 Cl 0.1 O 2.8 、Li 1.5 HfF 0.25 Cl 0.25 O 2.5 、Li1.5 HfBr 0.25 Cl 0.25 O 2.5 、Li 2.2 Hf 0.8 Y 0.2 O 3 、Li 2.2 Hf 0.8 La 0.2 O 3 、Li 2.2 Hf 0.8 Sc 0.2 O 3 、Li 2.2 Hf 0.8 Al 0.2 O 3 、Li 1.8 Hf 0.8 Ta 0.2 O 3 、Li 1.8 Hf 0.8 Nb 0.2 O 3 、Li 1.8 Hf 0.8 V 0.2 O 3 、Li 2.2 Hf 0.9 Mg 0.1 O 3 、Li 2.2 Hf 0.9 Ca 0.1 O 3 、Li 2.2 Hf 0.9 Sr 0.1 O 3 、Li 2.2 Hf 0.9 Ba 0.1 O 3 、Li 2.2 Hf 0.9 Zn 0.1 O 3 、Li 2.2 Hf 0.9 Cd 0.1 O 3 、Li 2.2 Zr 0.95 O 3 、Li 1.9 ZrF 0.1 O 2.9 、Li 1.8 ZrF 0.2 O 2.8 、Li 1.5 ZrF0.5 O 2.5 、Li 1.9 ZrCl 0.1 O 2.9 、Li 1.8 ZrCl 0.2 O 2.8 、Li 1.5 ZrCl 0.5 O 2.5 、Li 1.9 ZrF 0.05 Cl 0.05 O 2.9 、Li 1.9 ZrBr 0.05 Cl 0.05 O 2.9 、Li 1.8 ZrF 0.1 Cl 0.1 O 2.8 、Li 1.8 ZrBr 0.1 Cl 0.1 O 2.8 、Li 1.5 ZrF 0.25 Cl 0.25 O 2.5 、Li 1.5 ZrBr 0.25 Cl 0.25 O 2.5 、Li 2.2 Zr 0.8 Y 0.2 O 3 、Li 2.2 Zr 0.8 La 0.2 O 3 、Li 2.2 Zr 0.8 Sc 0.2 O 3 、Li 2.2 Zr 0.8 Al 0.2 O 3 、Li 1.8 Zr 0.8 Ta 0.2 O 3 、Li 1.8 Zr 0.8 Nb 0.2 O 3 、Li 1.8 Zr 0.8 V 0.2 O 3 、Li 2.2 Zr 0.9 Mg 0.1 O3 , Li 2.2 , Zr 0.9 , Ca 0.1 , O 3 , Li 2.2 , Zr 0.9 , Sr 0.1 , O 3 , Li 2.2 , Zr 0.9 , Ba 0.1 , O 3 , Li 2.2 , Zr 0.9 , Zn 0.1 , O 3 , Li 2.2 , Zr 0.9 , Cd 0.1 , O 3 , Li 2.2 , Hf 0.8 , Ta 0.2 , O 3 , Li 2.2 , Hf 0.8 , Nb 0.2 , O 3 , Li 2.2 , Hf 0.8 , V 0.2 , O 3 , Li 2.2 , Zr 0.8 , Ta 0.2 , O 3 , Li 2.2 , Zr 0.8 , Nb 0.2 , O 3 , Li 2.2 , Zr 0.8 , V 0.2 , O 3 , or a combination thereof.

[0113] The solid electrolyte according to the embodiment has an ionic conductivity of about 1 × 10 -10 Siemens / cm (S / cm) or greater, about 3.0 × 10 -5 S / cm or greater, or about 3.0 × 10 -5 S / cm to about 1 × 10 -2 S / cm at room temperature (25 °C). For example, the ionic conductivity of the solid electrolyte can be about 1 × 10 -5 S / cm to about 1 × 10 -2 S / cm, about 2 × 10 -5 S / cm to about 1 × 10 -2 S / cm, about 2 × 10 -5 S / cm to about 9 × 10 -3S / cm, about 4×10 -5 S / cm to about 9×10 -3 S / cm, about 4×10 -5 S / cm to about 5×10 -3 S / cm, about 5×10 -5 S / cm to about 2×10 -3 S / cm, about 6×10 -5 S / cm to about 1×10 -3 S / cm, about 7×10 -5 S / cm to about 9×10 -4 S / cm, about 8×10 -5 S / cm to about 8×10 -4 S / cm, about 9×10 -5 S / cm to about 7×10 -4 S / cm, about 1×10 -4 S / cm to about 7×10 -4 S / cm, about 5×10 -4 S / cm to about 8×10 -4 S / cm, or about 1×10 -4 S / cm to about 5×10 -4 S / cm. Without wishing to be bound by theory, it is understood that since the solid electrolyte has such a high ionic conductivity, the internal resistance of the lithium-air battery containing the solid electrolyte is reduced.

[0114] The solid electrolyte may be present in the form of particles. The solid electrolyte particles have an average particle diameter of about 5 nanometers (nm) to about 500 micrometers (μm), about 100 nm to about 15 μm, or about 300 nm to about 10 μm. The particle diameter can be measured by microscopy methods such as SEM or by light scattering.

[0115] The solid electrolyte has about 0.01 square meters per gram (m 2 / g) to about 1000 m 2 / g, about 0.05 m 2 / g to about 500 m 2 / g, about 0.1 m 2 / g to about 250 m 2 / g, or about 0.5 m 2 / g to about 100 m 2The specific surface area per g. The specific surface area can be determined as described in E.P. Barrett, L.G. Joyner, P.P. 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 entire content of which is incorporated herein by reference.

[0116] The solid electrolyte according to the embodiment has a pellet (disk) density of about 2.6 g / cc to about 5.1 g / cc, about 2.8 g / cc to about 5.05 g / cc, about 3 g / cc to about 5.0 g / cc, about 4 g / cc to about 4.95 g / cc, about 4.3 g / cc to about 4.9 g / cc, about 4.4 g / cc to about 4.85 g / cc, or about 4.5 g / cc to about 4.80 g / cc. When using a solid electrolyte having a pellet density within this range, the resulting product obtained after the pressing process for preparing the solid electrolyte is dense, e.g., sufficiently dense to be impermeable to gases such as air, water vapor, or liquids such as water. Thus, when using the resulting product to prepare a solid electrolyte in the form of a membrane, water or air does not pass through the membrane-shaped solid electrolyte, and thus the physical properties of the solid electrolyte are improved.

[0117] The pressing process is carried out at about 1 megapascal (MPa) to about 200 MPa, about 5 MPa to about 150 MPa, or about 10 MPa to about 120 MPa.

[0118] A method for preparing a solid electrolyte according to the embodiment is further described.

[0119] A lithium precursor and an M1 precursor are mixed to prepare a precursor mixture. Here, an M2 precursor and an X precursor are optionally added to the precursor mixture.

[0120] Subsequently, the precursor mixture is heat-treated to prepare a solid electrolyte comprising oxides represented by Formulas 1 to 3, or a combination thereof. M1 is as defined in Formulas 1 to 3, M2 is as defined in Formula 2, and X is as defined in Formula 3.

[0121] A solvent can be added to the mixture.

[0122] Any suitable solvent can be used as long as it can dissolve or disperse the lithium precursor, M1 precursor, M2 precursor, and X precursor. The solvent can be, for example, ethanol, water, ethylene glycol, isopropyl alcohol, or a combination thereof.

[0123] Mixing can be carried out using suitable methods such as grinding, blending, or stirring. Grinding can be carried out using a ball mill, jet mill, bead mill, or roll mill.

[0124] Subsequently, the precursor mixture is heat-treated.

[0125] The heat treatment can include a primary heat treatment. In the primary heat treatment of the mixture, the temperature is increased at a rate of about 1 °C / min to about 10 °C / min, and the primary heat treatment temperature is about 400 °C to about 950 °C or about 600 °C to about 900 °C. When the temperature is increased at a rate within this range during the primary heat treatment, the heat treatment can be carried out sufficiently to obtain a solid electrolyte having a desired crystal structure. The temperature of the primary heat treatment can be about 450 °C to about 900 °C, about 500 °C to about 850 °C, about 550 °C to about 800 °C, or about 600 °C to about 750 °C.

[0126] The primary heat treatment can be carried out in an oxygen or oxidizing gas atmosphere. Air can be used. The inert gas atmosphere can be argon, helium, nitrogen, or a combination thereof. The primary heat treatment time varies depending on the primary heat treatment temperature and is, for example, about 1 hour to about 20 hours, about 4 hours to about 15 hours, or about 9 hours to about 13 hours.

[0127] Each of the M1 precursor and the M2 precursor can contain an oxide, carbonate, chloride, phosphate, hydroxide, nitrate, or a combination thereof, and can be, for example, hafnium oxide, zirconium oxide, yttrium oxide, hafnium nitrate, hafnium sulfate, zirconium nitrate, zirconium sulfate, aluminum oxide, tantalum oxide, magnesium oxide, zinc oxide, gallium oxide, indium oxide, niobium oxide, vanadium oxide, lanthanum oxide, scandium oxide, calcium oxide, strontium oxide, barium oxide, cadmium oxide, or a combination thereof.

[0128] The X precursor can be, for example, lithium chloride, lithium fluoride, lithium bromide, or a combination thereof. The lithium precursor can be, for example, lithium oxide, lithium carbonate, lithium chloride, lithium sulfide, lithium nitrate, lithium phosphate, lithium hydroxide, or a combination thereof.

[0129] The contents of the lithium precursor, M1 precursor, M2 precursor, and X precursor are selected stoichiometrically to obtain a desired oxide, such as the oxides represented by Formulas 1 to 3.

[0130] Subsequently, the heat-treated precursor mixture is pulverized to obtain a pulverized product. The pulverized product is, for example, a powder. The pulverized product, such as powder particles, is obtained by pulverization and may have a particle size of 10 μm or less, for example, about 0.1 μm to about 10 μm. When the size of the powder particles is within this range, pulverization and mixing are carried out sufficiently because their size is small, making it easy to form the crystal phase. As used herein, "size" refers to the average diameter when the particles are spherical and the major axis length when the particles are non-spherical. For example, the size can be measured using a scanning electron microscope (SEM) or a particle size analyzer using light scattering.

[0131] Subsequently, a secondary heat treatment of the pulverized product is carried out. In the secondary heat treatment of the pulverized product, the temperature is increased at a rate of about 1 °C / min to about 10 °C / min. The secondary heat treatment can be carried out at 500 °C to about 1300 °C, about 700 °C to about 1200 °C, about 800 °C to about 1100 °C, or about 900 °C to about 1000 °C. The heat treatment can be carried out for a predetermined amount of time, for example, about 1 hour to about 24 hours, about 2 hours to about 20 hours, about 4 hours to about 16 hours, or about 6 hours to about 12 hours.

[0132] According to an embodiment, the secondary heat treatment can be carried out at a temperature higher than the primary heat treatment temperature. During the secondary heat treatment of the pulverized product, the pulverized product can be pressed to form a sheet. The pressing process is carried out at about 1 MPa to about 200 MPa, about 5 MPa to about 150 MPa, or about 10 MPa to about 120 MPa. According to an embodiment, when the solid electrolyte has a sheet density in the range of about 2 g / cc to about 6 g / cc or about 2.6 g / cc to about 5.1 g / cc, a film-shaped solid electrolyte can be formed from the sheet, which has improved impermeability to air or water.

[0133] As described above, when the secondary heat treatment of the pulverized product is carried out on the sheet, the diffusion distance of the material to be heat-treated is shortened, making it easy to prepare the desired solid electrolyte. When the secondary heat treatment is carried out in the form of powder particles (i.e., not in the form of a sheet), the oxides of Formulas 1 to 3 can be manufactured, but longer heat treatment times and higher temperatures can be used because the diffusion distance increases in powder particles compared to the diffusion distance in the sheet form.

[0134] The secondary heat treatment can be determined by the desired valence or oxidation value of M1 and M2 and can be carried out in an oxidizing gas atmosphere, a reducing gas atmosphere, or an inert gas atmosphere. The oxidizing gas atmosphere can be formed using air or oxygen, the reducing gas atmosphere can be formed using a reducing gas such as hydrogen, and the inert gas atmosphere can be formed using an inert gas such as nitrogen, argon, or helium.

[0135] The secondary heat treatment time can be adjusted depending on the secondary heat treatment temperature, and is, for example, about 1 hour to about 50 hours or about 6 hours to about 48 hours.

[0136] After the secondary heat treatment, oxides of Formulas 1 to 3 are formed. When the temperature increase during the primary heat treatment and the secondary heat treatment is within the above ranges, each heat treatment is sufficiently carried out such that not only the desired crystal structure is formed, but also the synthesis time is short and thus economical.

[0137] The solid electrolyte according to the embodiment can be used in a metal-air battery, such as a lithium-air battery. In addition, the solid electrolyte can be used as an electrolyte of a lithium battery, such as an all-solid-state battery. The solid electrolyte can be used in the manufacture of the positive electrode and the negative electrode of a battery, and can also be used in the surface coating of the positive electrode and the negative electrode.

[0138] The surface coating can be a protective layer. Refer to Figure 6 , the lithium-air battery 500 can include a protective layer 520, the protective layer 520 can include the solid electrolyte and can be disposed on the positive electrode 200. The lithium-air battery 500 can include a protective layer 510, the protective layer 510 includes the solid electrolyte and can be disposed on the negative electrode. According to another aspect, there is provided an electrochemical device including the solid electrolyte. The solid electrolyte can be chemically stable, excellent in ionic conductivity, and improved in stability against moisture and strong bases, thereby obtaining an electrochemical device in which deterioration is effectively suppressed.

[0139] The electrochemical device is, but not limited to, a battery, a storage battery, a supercapacitor, a fuel cell, a sensor, or an electrochromic device. Any suitable electrochemical device can be used.

[0140] The battery is, for example, a primary battery or a secondary battery. Examples of the battery can include, but are not limited to, a lithium battery or a sodium battery. Any suitable battery can be used. Examples of the lithium battery can include, but are not limited to, a lithium-ion battery or a lithium-air battery. Any suitable lithium battery can be used. Examples of the electrochromic device can include, but are not limited to, an electrochromic mirror, an electrochromic window, or an electrochromic screen. Any suitable electrochromic device can be used.

[0141] The electrochemical device is, for example, a lithium metal battery using a metal such as lithium or zinc as the negative electrode, or a lithium-air battery using lithium as the negative electrode. The lifespan of such a lithium-air battery is improved.

[0142] According to the embodiment, the positive electrode is porous. When the positive electrode is porous, air, oxygen, etc. can easily diffuse into the positive electrode.

[0143] The metal-air battery according to an embodiment includes a positive electrode, a negative electrode, and an electrolyte between the positive electrode and the negative electrode, wherein at least one of the positive electrode, the negative electrode, or the electrolyte includes the solid electrolyte.

[0144] According to an embodiment, the electrolyte may include the solid electrolyte.

[0145] According to an embodiment, the positive electrode or the negative electrode may include the solid electrolyte. The negative electrode may include lithium.

[0146] Since the lithium-air battery includes the solid electrolyte, the stability against moisture and strong bases is improved, and the reversibility under humid or air conditions is improved, thereby enabling the lithium-air battery to operate more effectively. In addition, the structural stability of the lithium-air battery is improved, and its deterioration is suppressed.

[0147] The lithium-air battery may include a positive electrode, and the positive electrode may be disposed on a positive electrode current collector.

[0148] The positive electrode may contain the solid electrolyte. The content of the solid electrolyte is about 2 parts by weight to about 70 parts by weight, about 3 parts by weight to about 70 parts by weight, about 3 parts by weight to about 60 parts by weight, about 10 parts by weight to about 60 parts by weight, based on 100 parts by weight of the positive electrode.

[0149] Holes may also be introduced into the positive electrode by introducing a pore-forming agent during the manufacture of the positive electrode. The positive electrode may be in the form of a porous sheet (disc), a porous sheet material, etc., but its form is not limited thereto, and it may be formed according to the desired battery form.

[0150] The positive electrode is permeable to gases such as oxygen or air. Therefore, the positive electrode may be different from a positive electrode that is substantially impermeable to gases such as oxygen or air and conducts only ions. Since the positive electrode is porous and / or permeable to gases, oxygen, air, etc. easily diffuse into the positive electrode, and lithium ions and / or electrons easily move through the solid electrolyte included in the positive electrode, such that an electrochemical reaction of oxygen, lithium ions, and electrons easily occurs in the positive electrode.

[0151] In the manufacture of the positive electrode, in addition to the solid electrolyte, a conductive material may be further added to further increase the electron conductivity and ion conductivity. The conductive material may be porous. The conductive material has a suitable porosity, thereby promoting the penetration of air. The conductive material may be any suitable material that is porous and / or conductive, and is, for example, a carbon-based material having porosity. Examples of the carbon-based material may include, but are not limited to, carbon black, graphite, graphene, activated carbon, or carbon fiber. Any suitable carbon-based material may be used. The conductive material is, for example, a metal material. Examples of the metal material may include metal fibers, metal meshes, or metal powders. Examples of the metal powder may include copper powder, silver powder, and aluminum powder. The conductive material is, for example, an organic conductive material. Examples of the organic conductive material may include polyphenylene derivatives or polythiophene derivatives. The conductive materials are used alone or in combination. The positive electrode may include a composite conductor as the conductive material, and in addition to the composite conductor, the positive electrode may further include the conductive material.

[0152] The positive electrode may further include a catalyst for the oxidation / reduction of oxygen. Examples of the catalyst may include, but are not limited to, noble metal catalysts such as platinum, gold, silver, palladium, ruthenium, rhodium, or osmium; oxide catalysts such as manganese oxide, iron oxide, cobalt oxide, or nickel oxide; organometallic catalysts such as cobalt phthalocyanine, or combinations thereof. Any suitable catalyst may be used.

[0153] The catalyst is supported on a carrier. Examples of the carrier may include an oxide carrier, a zeolite carrier, a clay-based mineral carrier, or a carbon carrier. The oxide carrier is an oxide carrier including Al, Si, Zr, Ti, Ce, Pr, Sm, Eu, Tb, Tm, Yb, Sb, Bi, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, W, or combinations thereof. Examples of the oxide carrier may include alumina, silica, zirconia, titania, or combinations thereof. Examples of the carbon carrier may include, but are not limited to, carbon black such as Ketjen black, acetylene black, channel black, or lamp black; graphite such as natural graphite, artificial graphite, or expanded graphite; activated carbon; or carbon fiber. Any suitable carbon carrier may be used.

[0154] The positive electrode may further include a binder. The binder may include a thermoplastic resin or a thermosetting resin. Examples of the binder may include, but are not limited to, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene-butadiene rubber, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluorochloroethylene copolymer, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-trifluorochloroethylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene copolymer, ethylene-acrylic acid copolymer, or a combination thereof. Any suitable binder may be used.

[0155] The positive electrode is manufactured as follows: A conductive material, an oxidation / reduction catalyst for oxygen, and a binder are mixed to obtain a mixture, an appropriate solvent is added to the mixture to prepare a positive electrode paste, and then the positive electrode paste is applied to the surface of a substrate and the applied positive electrode paste is dried or the positive electrode paste is pressed onto the substrate to improve the electrode density. The substrate is, for example, a positive electrode current collector, a separator, or a solid electrolyte membrane. The positive electrode current collector is, for example, a gas diffusion layer. The conductive material may include a solid electrolyte according to an embodiment, and depending on the type of the desired positive electrode, the oxidation / reduction catalyst for oxygen and the binder in the positive electrode may be omitted.

[0156] The lithium-air battery may include a negative electrode. According to an embodiment, the negative electrode may include the solid electrolyte.

[0157] The negative electrode may contain lithium.

[0158] The negative electrode may be, for example, a lithium metal thin film or a lithium-based alloy thin film. The lithium-based alloy is, for example, an alloy of lithium and aluminum, tin, magnesium, indium, calcium, titanium, vanadium, or a combination thereof.

[0159] The lithium-air battery may include an electrolyte disposed between the positive electrode and the negative electrode.

[0160] The electrolyte may be, for example, the solid electrolyte including the oxides represented by Formulas 1 to 3.

[0161] According to an embodiment, in addition to the solid electrolyte, the electrolyte may further include another solid electrolyte, a gel electrolyte, or a liquid electrolyte. The other solid electrolyte, the gel electrolyte, and the liquid electrolyte are not particularly limited. Any suitable electrolyte may be used.

[0162] Additional solid electrolytes may include, but are not limited to, solid electrolytes including ion-conducting inorganic materials, solid electrolytes including polymer ionic liquids (PILs) and lithium salts, solid electrolytes including ion-conducting polymers and lithium salts, or solid electrolytes including electron-conducting polymers. Any suitable additional solid electrolyte may be used.

[0163] The ion-conducting inorganic materials may include, but are not limited to, glass or amorphous metal ion conductors, ceramic active metal ion conductors, or glass-ceramic active metal ion conductors. Any suitable ion-conducting inorganic material may be used. The ion-conducting inorganic material may be in the form of, for example, particles or sheets.

[0164] Examples of ion-conducting inorganic materials may include BaTiO 3 、Pb(Zr a Ti 1-a )O 3 (0≤a≤1)(PZT), Pb 1- x La x Zr 1-y Ti y O 3 (PLZT)(0≤x<1, 0≤y<1), Pb(Mg 1 / 3 Nb 2 / 3 )O 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 ,0<x<2, 0<y<3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO 4 ) 3 、0<x<2, 0<y<1, 0<z<3), Li 1+x+y (Al aGa 1-a ) x (Ti b Ge 1-b ) 2-x Si y P 3-y O 12 (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ a ≤ 1, and 0 ≤ b ≤ 1), lithium lanthanum titanate (Li x La y TiO 3 , 0 < x < 2, 0 < y < 3), lithium germanium thiophosphate (Li x Ge y P z S w , 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride (Li x N y , 0 < x < 4, 0 < y < 2), SiS 2 -based glass (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4), P 2 S 5 -based glass (Li x P y S z , 0 < x < 3, 0 < y < 3, 0 < z < 7), Li 2 O, LiF, LiOH, Li 2 CO 3 、LiAlO 2 、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 (M = Te, Nb, Zr, 0 ≤ x ≤ 5)), or a combination thereof.

[0165] The polymer ionic liquid (PIL) may include: i) a cation, which may be an ammonium-based ion, a pyrrolidine -based ion, a pyridine -based ion, a pyrimidine -based ion, an imidazole -based ion, a piperidine -based ion, a pyrazole ions, based on azole ions, based on pyridazine ions, based on ions, sulfonium-based ions, triazole-based ions, or combinations thereof, and ii) anions, which may be BF 4 - , PF 6 - , AsF 6 - , SbF 6 - , AlCl 4 - , HSO 4 - , 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 ) 2 N - , (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 ) 2 PF 4 - , (CF3 ) 3 PF 3 - ,(CF 3 ) 4 PF 2 - ,(CF 3 ) 5 PF - ,(CF 3 ) 6 P - , SF 5 CF 2 SO 3 - , SF 5 CHF 2 SO 3 - CF 3 CF 2 (CF 3 ) 2 CO - ,(CF 3 SO 2 ) 2 CH - , (SF 5 ) 3 C - , and (O(CF 3 ) 2 C 2 (CF 3 ) 2 O) 2 PO - Examples of polymer ionic liquids (PILs) may include poly TFSI (diallyldimethylammonium), poly (bis(trifluoromethanesulfonyl)imide 1-allyl-3-methylimidazole ), poly(bis(trifluoromethanesulfonyl)imide N-methyl-N-propylpiperidinium ), or a combination thereof.

[0166] The ion-conducting polymer may include conductive repeating units derived from ether-based monomers, acrylic monomers, methacrylic monomers, siloxane-based monomers, or combinations thereof.

[0167] Examples of ion-conductive polymers can include, but are not limited to, polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinylpyrrolidone (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), poly(ethylene vinyl acetate), phosphate polymers, polyester sulfides, poly(vinylidene fluoride) (PVdF), Li-substituted Nafion, or combinations thereof. Any suitable ion-conductive polymer can be used.

[0168] Examples of electron-conductive polymers can include, but are not limited to, polyphenylene derivatives or polythiophene derivatives. Any suitable electron-conductive polymer can be used.

[0169] A gel electrolyte is obtained by adding a low-molecular-weight solvent to a solid electrolyte disposed between a positive electrode and a negative electrode. A gel electrolyte is obtained by adding a solvent, an oligomer, or a combination thereof, which is a low-molecular-weight compound, to a polymer.

[0170] The liquid electrolyte can include a solvent and a lithium salt.

[0171] The solvent can include, but is not limited to, an organic solvent, an ionic liquid, an oligomer, or a combination thereof. Any suitable solvent can be used as long as it is liquid at room temperature (25 °C).

[0172] The organic solvent can be an ether-based solvent, a carbonate-based solvent, an ester-based solvent, a ketone-based solvent, or a combination thereof. The organic solvent can include, but is not limited to, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, vinylene 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, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, succinonitrile, diethylene glycol dimethyl ether (DEGDME), tetraethylene glycol dimethyl ether (TEGDME), polyethylene glycol dimethyl ether (PEGDME, MW ~ 500), dimethyl ether, diethyl ether, dibutyl ether, dimethoxyethane, or combinations thereof. Any suitable organic solvent that is liquid at room temperature can be used.

[0173] The ionic liquid (IL) can include: i) a cation, which can be an ammonium-based ion, a pyrrolidine- -based ion, a pyridine- -based ion, a pyrimidine- ions, imidazole-based ions, piperidine-based ions, pyrazole-based ions, based on azole ions, pyridazine-based ions, based on ions, sulfonium-based ions, triazole-based ions, or a combination thereof, and ii) an anion, which may be BF 4 - 、PF 6 - 、AsF 6 - 、SbF 6 - 、AlCl 4 - 、HSO 4 - 、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 ) 2 N - 、(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 ) 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 ) 2 PO - , or a combination thereof.

[0174] The lithium salt may include, but is not limited to, LiTFSI (LiN(SO 2 CF 3 ) 2 ), LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiNO 3 , lithium bis(oxalato)borate (LiBOB), LiCF 3 SO 3 , LiN(SO 2 C 2 F 5 ) 2 , LiN(SO 2F) 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. Any suitable lithium salt can be used. The concentration of the lithium salt is, for example, from about 0.01 molar concentration (M) to about 5.0 M, from about 0.05 M to about 4 M, from about 0.1 M to about 4.5 M, from about 0.5 M to about 4 M, or from about 1 M to about 3.5 M.

[0175] The lithium - air battery may further include a separator between the positive electrode and the negative electrode.

[0176] There is no limitation on the separator as long as it has a composition that can withstand the usage range of the lithium - air battery. Examples of the separator may include: polymer non - woven fabrics such as polypropylene non - woven fabric or polyphenylene sulfide non - woven fabric; porous membranes of olefin resins such as polyethylene or polypropylene; glass fibers; or a combination thereof.

[0177] The electrolyte may have a structure in which the separator is impregnated with a solid polymer electrolyte or a structure in which the separator is impregnated with a liquid electrolyte. The electrolyte having a structure in which the separator is impregnated with a solid polymer electrolyte is prepared by placing a solid polymer electrolyte membrane on one or both surfaces of the separator and rolling the solid polymer electrolyte membrane. The electrolyte having a structure in which the separator is impregnated with a liquid electrolyte is prepared by injecting a liquid electrolyte containing a lithium salt into the separator.

[0178] The lithium - air battery can be completed by: placing the negative electrode on one surface of the case, placing the electrolyte layer on the negative electrode, placing the positive electrode on the electrolyte layer, placing the porous positive - electrode current collector on the positive electrode, placing a pushing member on the porous positive - electrode current collector to transfer air to the air electrode, and pushing the pushing member to fix the unit cell. The case can be divided into an upper part that contacts the negative electrode and a lower part that contacts the air electrode, and an insulating resin can be provided between the upper part and the lower part to electrically isolate the positive electrode and the negative electrode from each other.

[0179] The lithium - air battery can be used in both primary and secondary batteries. The shape of the lithium - air battery is not particularly limited and is, for example, coin - shaped, button - shaped, sheet - shaped, laminate - shaped, cylindrical - shaped, flat - shaped, or angular - shaped. The lithium - air battery can be a medium - sized or large - sized battery for electric vehicles.

[0180] Figure 5Schematic cross-sectional view for explaining the structure of a lithium-air battery according to an embodiment.

[0181] Reference Figure 5 , the lithium-air battery 500 has the following structure: A first electrolyte 400 is interposed between a positive electrode 200 containing oxygen as an active material adjacent to a first current collector 210 and a negative electrode 300 containing lithium adjacent to a second current collector 310. The first electrolyte 400 is a separator impregnated with a liquid electrolyte.

[0182] A second electrolyte 450 may be provided between the positive electrode 200 and the first electrolyte 400. According to an embodiment, the second electrolyte 450 is a lithium-ion conducting solid electrolyte membrane, and a solid electrolyte according to an embodiment may be used. The first current collector 210 is porous and may also serve as a gas diffusion layer capable of diffusing air due to the porosity. A pushing member 220 capable of transporting air to the positive electrode 200 is provided on the first current collector 210.

[0183] Air is supplied to an air inlet 230a and discharged to an air outlet 230b. The lithium-air battery 500 may be accommodated in a stainless steel container. Reference numeral 320 denotes an insulating resin case.

[0184] The "air" of the lithium-air battery is not limited to the atmosphere and may include a combination of gases containing oxygen, or pure oxygen. This broad definition of the term "air" applies to all applications such as air unit cells, air positive electrodes, etc.

[0185] Hereinafter, the present disclosure will be described in detail with reference to examples and comparative examples. However, these examples are provided for illustrative purposes only, and the scope of the present disclosure is not limited thereto.

[0186] Examples

[0187] Preparation of a solid electrolyte including an oxide

[0188] Comparative Example 1: Li 2 HfO 3

[0189] Li as a lithium precursor 2 CO 3 and HfO as an M1 precursor 2 According to Li 2 HfO 3 Mix according to the composition ratio, add ethanol thereto and mix to obtain a precursor mixture. Put the precursor mixture into a ball milling device, and pulverize and mix for 4 hours. Dry the obtained mixture, heat it to 650 °C at a temperature increasing rate of about 5 °C / minute, and perform a primary heat treatment in an air atmosphere for 12 hours to obtain a powder.

[0190] The powder obtained by the primary heat treatment is ground and then pressed at about 100 MPa to prepare a pellet (disc) having a diameter of about 1 cm and a height of about 0.1 cm. The secondary heat treatment of the pellet is carried out at 700 °C for 12 hours in an air or oxygen atmosphere to obtain a solid electrolyte including an oxide. When heated to 700 °C during the secondary heat treatment, the temperature increase rate is about 5 °C / minute.

[0191] Example 1

[0192] A solid electrolyte including an oxide is obtained in the same manner as in Comparative Example 1, except that: when preparing the precursor mixture, lithium chloride is further added. Li is selected as the lithium precursor in stoichiometry 2 CO 3 、, HfO as the M1 precursor 2 、, and the content of lithium chloride to obtain Li 1.5 HfCl 0.5 O 2.5 。. The primary heat treatment is carried out at 650 °C for 12 hours, and the secondary heat treatment is carried out at 700 °C for 12 hours.

[0193] Examples 2 and 6

[0194] A solid electrolyte is obtained in the same manner as in Example 1, except that: Li is selected as the lithium precursor 2 CO 3 、, HfO as the M1 precursor 2 、, and the content of lithium chloride to obtain the target material given in Table 1.

[0195] Examples 3, 9 and 10

[0196] A solid electrolyte is obtained in the same manner as in Comparative Example 1, except that: when preparing the precursor mixture, lithium fluoride (LiF) is further added, and Li is selected as the lithium precursor in stoichiometry 2 CO 3 、, HfO as the M1 precursor 2 、, and the content of lithium fluoride to obtain the target material having the composition of Table 1.

[0197] Example 4

[0198] A solid electrolyte is obtained in the same manner as in Comparative Example 1, except that: when preparing the precursor mixture, Li is selected as the lithium precursor in stoichiometry 2 CO 3 and HfO as the M1 precursor 2 of the content to obtain the target material.

[0199] Example 5

[0200] A solid electrolyte was obtained in the same manner as in Comparative Example 1, except that: when preparing the precursor mixture, Al as an Al precursor was further added. 2 O 3 , and the content of Li as a lithium precursor was stoichiometrically controlled. 2 CO 3 , HfO as an M1 precursor. 2 , and Al 2 O 3 to obtain a target material having the composition shown in Table 1.

[0201] Example 7

[0202] A solid electrolyte was obtained in the same manner as in Comparative Example 1, except that: when preparing the precursor mixture, magnesium oxide (MgO) as an Mg precursor was further added, and the content of Li as a lithium precursor, 2 CO 3 , HfO as an M1 precursor. 2 , and magnesium oxide (MgO) were stoichiometrically selected to obtain a target material having the composition shown in Table 1.

[0203] Example 8

[0204] A solid electrolyte was obtained in the same manner as in Comparative Example 1, except that: when preparing the precursor mixture, tantalum oxide (Ta 2 O 5 ) as a Ta precursor was further added, and the content of Li as a lithium precursor, 2 CO 3 , HfO as an M1 precursor. 2 , and tantalum oxide (Ta 2 O 5 ) were stoichiometrically selected to obtain a target material having the composition shown in Table 1.

[0205] Example 11

[0206] A solid electrolyte was obtained in the same manner as in Comparative Example 1, except that: when preparing the precursor mixture, yttrium oxide (Y 2 O 3 ) as a Y precursor was further added, and the content of Li as a lithium precursor, 2 CO 3 , HfO as an M1 precursor. 2 , and yttrium oxide (Y 2 O 3 ) were stoichiometrically selected to obtain a target material having the composition shown in Table 1.

[0207] Example 12

[0208] A solid electrolyte was obtained in the same manner as in Comparative Example 1, except that: when preparing the precursor mixture, zinc oxide (Zn 2 O 3 ) was further added as a Zn precursor, and the contents of Li 2 CO 3 as a lithium precursor, HfO 2 as an M1 precursor, and zinc oxide (Zn 2 O 3 ) were stoichiometrically selected to obtain a target material having the composition shown in Table 1.

[0209] Table 1

[0210] Example Composition Comparative Example 1 <![CDATA[Li 2 HfO 3 > Example 1 <![CDATA[Li 1.5 HfCl 0.5 O 2.5 <!-- 14 -->]]> Example 2 <![CDATA[Li 1.8 HfCl 0.2 O 2.8 > Example 3 <![CDATA[Li 1.5 HfF 0.5 O 2.5 > Example 4 <![CDATA[Li 2.2 Hf 0.95 O 3 > Example 5 <![CDATA[Li 2.2 Hf 0.8 Al 0.2 O 3 > Example 6 <![CDATA[Li 1.9 HfCl 0.1 O 2.9 > Example 7 <![CDATA[Li 2.2 Hf 0.9 Mg 0.1 O 3 > Example 8 <![CDATA[Li 1.8 Hf 0.8 Ta 0.2 O 3 > Example 9 <![CDATA[Li 1.9 HfF 0.1 O 2.9 > Example 10 <![CDATA[Li 1.8 HfF 0.2 O 2.8 > Example 11 <![CDATA[Li 2.2 Hf 0.8 Y 0.2 O 3 > Example 12 <![CDATA[Li 2.2 Hf 0.9 Zn 0.1 O 3 >

[0211] Comparative Example 2: Li 2 ZrO 3

[0212] Li 2 CO 3 as a lithium precursor and ZrO 2 as an M1 precursor were mixed according to the composition ratio of Li 2 ZrO 3 , ethanol was added thereto and mixed to obtain a precursor mixture. The precursor mixture was placed in a ball milling device and pulverized and mixed for 4 hours. The resulting mixture was dried, heated to 650 °C at a temperature increasing rate of about 5 °C / min, and then subjected to a primary heat treatment in an air atmosphere for 12 hours to obtain a powder.

[0213] The powder obtained by the primary heat treatment was ground and then pressed at about 100 MPa to prepare a pellet having a diameter of about 1 cm and a height of about 0.1 cm. The pellet was subjected to a secondary heat treatment at 700 °C in an air or oxygen atmosphere for 12 hours to obtain a solid electrolyte. When heated to 700 °C during the secondary heat treatment, the temperature increasing rate was about 5 °C / min.

[0214] Example 13

[0215] A solid electrolyte was obtained in the same manner as in Comparative Example 2, except that: when preparing the precursor mixture, aluminum oxide (Al 2 O 3 ) was further added as an Al precursor, and the contents of Li 2 CO 3 as a lithium precursor, ZrO 2 as an M1 precursor, and aluminum oxide (Al 2 O 3 ) were stoichiometrically selected to obtain a target material having the composition shown in Table 2.

[0216] Examples 14 and 16

[0217] A solid electrolyte was obtained in the same manner as in Comparative Example 2, except that: when preparing the precursor mixture, lithium chloride (LiCl) was further added, and Li was selected as the lithium precursor in stoichiometry 2 CO 3 , ZrO as the M1 precursor 2 , and the contents of lithium chloride (LiCl) to obtain a target material having the composition shown in Table 2.

[0218] Example 15

[0219] A solid electrolyte was obtained in the same manner as in Comparative Example 2, except that: when preparing the precursor mixture, yttrium oxide (Y 2 O 3 ) was further added as the Y precursor, and Li was selected as the lithium precursor in stoichiometry 2 CO 3 , ZrO as the M1 precursor 2 , and the contents of yttrium oxide (Y 2 O 3 ) to obtain a target material having the composition shown in Table 2.

[0220] Example 17

[0221] A solid electrolyte was obtained in the same manner as in Comparative Example 2, except that: when preparing the precursor mixture, magnesium oxide (MgO) was further added as the Mg precursor, and Li was selected as the lithium precursor in stoichiometry 2 CO 3 , ZrO as the M1 precursor 2 , and the contents of magnesium oxide (MgO) to obtain a target material having the composition shown in Table 2.

[0222] Example 18

[0223] A solid electrolyte was obtained in the same manner as in Comparative Example 2, except that: when preparing the precursor mixture, zinc oxide (ZnO) was further added as the Zn precursor, and Li was selected as the lithium precursor in stoichiometry 2 CO 3 , ZrO as the M1 precursor 2 , and the contents of zinc oxide (ZnO) to obtain a target material having the composition shown in Table 2.

[0224] Example 19

[0225] A solid electrolyte was obtained in the same manner as in Comparative Example 2, except that: when preparing the precursor mixture, tantalum oxide (Ta2 O 5 ), and Li is selected stoichiometrically as the lithium precursor 2 CO 3 , ZrO as the M1 precursor 2 , and tantalum oxide (Ta 2 O 5 ) in amounts to obtain a target material having the composition of Table 2.

[0226] Example 20

[0227] A solid electrolyte was obtained in the same manner as in Comparative Example 2, except that: Li was selected as the lithium precursor 2 CO 3 and the content of ZrO as the M1 precursor 2 to obtain a composition ratio of Li 2.2 Zr 0.95 O 3 .

[0228] Examples 21 to 23

[0229] A solid electrolyte was obtained in the same manner as in Comparative Example 2, except that: when preparing the precursor mixture, lithium fluoride (LiF) was further added, and Li was selected stoichiometrically as the lithium precursor 2 CO 3 , ZrO as the M1 precursor 2 , and the content of lithium fluoride (LiF) to obtain a target material having the composition of Table 2.

[0230] Table 2

[0231] Example Composition Comparative Example 2 <![CDATA[Li 2 ZrO 3 > Example 13 <![CDATA[Li 2.2 Zr 0.8 Al 0.2 O 3 > Example 14 <![CDATA[Li 1.8 ZrCl 0.2 O 2.8 > Example 15 <![CDATA[Li 2.2 Zr 0.8 Y 0.2 O 3 > Example 16 <![CDATA[Li 1.9 ZrCl 0.1 O 2.9 > Example 17 <![CDATA[Li 2.2 Zr 0.9 Mg 0.1 O 3 > Example 18 <![CDATA[Li 2.2 Zr 0.9 Zn 0.1 O 3 > Example 19 <![CDATA[Li 1.8 Zr 0.8 Ta 0.2 O 3 > Example 20 <![CDATA[Li 2.2 Zr 0.95 O 3 > Example 21 <![CDATA[Li 1.5 ZrF 0.5 O 2.5 > Example 22 <![CDATA[Li 1.8 ZrF 0.2 O 2.8 > Example 23 <![CDATA[Li 1.9 ZrF 0.1 O 2.9 >

[0232] The solid electrolyte of Example 4 contains an oxide having cation vacancies, and the solid electrolytes of Examples 3, 9, and 10 each contain an oxide doped with fluoride anions. The solid electrolytes of Examples 1, 2, and 6 each contain an oxide doped with chloride anions, and the solid electrolytes of Examples 5 and 11 contain an oxide doped with trivalent cations.

[0233] The solid electrolyte of Example 8 contains an oxide doped with pentavalent cations, and the solid electrolyte of Example 7 contains an oxide doped with divalent cations. The solid electrolyte of Example 12 contains an oxide doped with divalent cations.

[0234] Manufacturing Example 1: Manufacture of a lithium-air battery

[0235] 40 parts by weight of carbon (Super-P), 10 parts by weight of polytetrafluoroethylene (PTFE), and 50 parts by weight of NMP (N-methylpyrrolidone) were mixed to prepare a positive electrode paste, and then the positive electrode paste was applied and roll-pressed to obtain a positive electrode composite sheet. The positive electrode composite sheet was pressed onto a stainless steel mesh, and then vacuum-dried in an oven at 100 °C for 120 minutes to obtain a positive electrode.

[0236] The center of a 5 cm × 5 cm aluminum film (polypropylene-coated aluminum film, thickness 200 μm) was perforated to have holes, and the holes were blocked with the solid electrolyte of Example 1 using an adhesive to prepare a first aluminum film provided with the solid electrolyte of Example 1. Subsequently, a new second aluminum film having a size of 5 cm × 5 cm, a copper current collector (thickness 20 μm), a lithium foil (1.4 cm × 1.4 cm, thickness 100 μm), a separator (Celgard-3501, manufactured by Celgard Corporation) having a thickness of 25 μm and made of a polypropylene material and impregnated with an electrolyte solution (a mixture of 1 molar concentration (M) LiTFSI and PC), and the prepared first aluminum film were laminated, heated in a vacuum, and adhered to obtain a protected lithium negative electrode in the form of an aluminum pouch.

[0237] The protected lithium negative electrode was provided in a stainless steel case, and a positive electrode provided with a separator (Celgard-3501, manufactured by Celgard Corporation) having a thickness of 25 μm and made of a polypropylene material was arranged to face the negative electrode. Subsequently, a porous gas diffusion layer made of carbon fiber was placed on the positive electrode, a nickel foam plate was placed on the porous gas diffusion layer, and a pushing member for transporting air to the positive electrode was pressed onto the nickel foam plate to fabricate a lithium-air battery.

[0238] Production Examples 2 to 23: Fabrication of Lithium-Air Batteries

[0239] Lithium-air batteries were fabricated in the same manner as in Production Example 1, except that the solid electrolytes of Production Examples 2 to 23 were used instead of the solid electrolyte of Production Example 1, respectively.

[0240] Comparative Examples 1 and 2: Fabrication of Lithium-Air Batteries

[0241] Lithium-air batteries were fabricated in the same manner as in Production Example 1, except that the solid electrolytes of Comparative Examples 1 and 2 were used instead of the solid electrolyte of Production Example 1, respectively.

[0242] Evaluation Example 1: XRD Spectrum

[0243] XRD spectra of the solid electrolytes of Production Examples 3 to 5, 7, 9, 12, 13, and 20 and Comparative Example 1 were measured, and the results are shown inFigure 1 For this, X-ray diffraction analysis was carried out using a D8 Advance from Bruker Corporation, and Cu Kα radiation was used for XRD spectral measurement.

[0244] As Figure 1 shown, in the solid electrolytes of Examples 3 to 5, 7, 9, 12, 13, and 20, peaks appeared in the regions where the diffraction angle 2θ was 26.7 ± 0.5° 2θ, 35 ± 0.5° 2θ, and 39 ± 0.5° 2θ, but in the solid electrolyte of Comparative Example 1, these peaks were not observed.

[0245] Evaluation Example 2: Ionic Conductivity

[0246] The upper and lower surfaces of each of the ion conductor sheets prepared in Examples 1 to 12 and Comparative Example 1 were coated (deposited) with gold (Au) by sputtering, and the impedance of the samples was measured by the two-probe method using an impedance analyzer. The frequency range was from 1 Hz to 1 MHz, and the amplitude voltage was 100 mV. The impedance of the samples was measured at 30 °C in an air atmosphere. The resistance value was obtained from the arc of the Nyquist plot for the impedance measurement results, and the ionic conductivity was calculated from the resistance value.

[0247] As Figure 3 shown, the solid electrolytes of Examples 1 to 12 exhibited higher ionic conductivity than the solid electrolyte of Comparative Example 1. From these results, it was confirmed that the ionic conductivity of the solid electrolyte was improved by introducing anions such as fluorine and chlorine, and by introducing yttrium, aluminum, tantalum, magnesium, or zinc.

[0248] Except for hafnium, the solid electrolytes of Examples 11 and 12 each contained yttrium and zinc, and thus, compared with the weight of the electrolyte of Comparative Example 1, their weight was reduced, thereby enabling the fabrication of a lightweight lithium-air battery.

[0249] Evaluation Example 3: Ionic Conductivity

[0250] The upper and lower surfaces of the ion conductor sheets prepared in Examples 13 to 23 and Comparative Example 2 were coated (deposited) with gold (Au) by sputtering, and the impedance of the samples was measured by the two-probe method using an impedance analyzer. The frequency range was from about 1 Hz to about 1 MHz, and the amplitude voltage was 100 mV. The impedance of the samples was measured at 30 °C in an air atmosphere. The resistance value was obtained from the arc of the Nyquist plot for the impedance measurement results, and the ionic conductivity was calculated from the resistance value.

[0251] As Figure 4As shown, compared with the solid electrolyte of Comparative Example 2, the solid electrolytes of Examples 13 to 23 exhibit the same or improved ionic conductivity. From these results, it was confirmed that the ionic conductivity of the solid electrolyte was improved by introducing anions such as fluorine and chlorine, and by introducing yttrium, aluminum, tantalum, magnesium, or zinc. In particular, compared with the solid electrolyte of Comparative Example 2, the solid electrolytes of Examples 20 to 23 exhibit the same level of ionic conductivity, and the sheet density increases, as shown in Table 4 below. Thus, when using a solid electrolyte with an increased sheet density, the resulting product obtained after the pressing process for preparing the solid electrolyte is dense. Therefore, when using the dense product to prepare the solid electrolyte in the form of a film, the solid electrolyte has improved physical properties because water or air does not pass through the solid electrolyte.

[0252] Evaluation Example 4: Sheet Density

[0253] Examples 1 to 12 and Comparative Example 1

[0254] The sheet density of the ion conductor sheets obtained in Examples 1 to 12 and Comparative Example 1 was measured by measuring the diameter, height, and weight of the ion conductor sheets. The evaluation results of the sheet density are shown in Table 3 and Figure 2 in.

[0255] Table 3

[0256] Example Wafer density (g / cc) Example 1 4.42 Example 2 4.31 Example 3 4.60 Example 4 4.00 Example 5 4.99 Example 6 4.24 Example 7 5.10 Example 8 4.37 Example 9 4.42 Example 10 4.41 Example 11 4.96 Example 12 4.92 Comparative Example 1 3.97

[0257] As shown in Table 3 and Figure 2 in, it was found that the sheet density of the sheets of Examples 1 to 12 was improved compared with the sheet density of the sheets of Comparative Example 1.

[0258] Examples 13 to 23 and Comparative Example 2

[0259] The sheet density of the ion conductor sheets obtained in Examples 13 to 23 and Comparative Example 2 was measured by measuring the diameter, height, and weight of the ion conductor sheets.

[0260] The evaluation results of the sheet density are shown in Table 4.

[0261] Table 4

[0262] Example Wafer density (g / cc) Example 13 3.42 Example 14 2.60 Example 15 2.94 Example 16 2.79 Example 17 2.85 Example 18 3.33 Example 19 3.18 Example 20 3.04 Example 21 3.09 Example 22 2.99 Example 23 2.87 Comparative Example 2 2.62

[0263] As can be seen from Table 4, it was found that the sheet density of the ion conductor sheets of Examples 13 and 15 to 23 was improved compared with the sheet density of the sheets of Comparative Example 2. Although the sheet density of the ion conductor sheet of Example 14 was lower than that of Comparative Example 2, the conductivity increased significantly, as Figure 4 shown in.

[0264] Evaluation Example 5: Evaluation of Electrochemical Stability

[0265] After the solid electrolyte of Example 1 was pulverized to a size of about 1 μm, N-methyl-2-pyrrolidone was mixed with 85 weight percent (wt%) of the pulverized product, 10 wt% of carbon black as a conductive material, and 5 wt% of polyvinylidene fluoride (PVDF) as a binder to prepare a slurry. The slurry was applied onto an aluminum foil and then dried to prepare a working electrode. A lithium metal foil was used as a counter electrode, and a separator impregnated with a liquid electrolyte (1 M LiTFSI in propylene carbonate (PC)) was disposed between the working electrode and the counter electrode to prepare a half-cell battery.

[0266] The electrochemical stability of the layered compound on lithium metal was evaluated by cyclic voltammetry at a scan rate of 0.1 millivolt per second (mV / sec) in a voltage range from 2 volts (V) to 4 V (versus Li).

[0267] As a result of the evaluation, the solid electrolyte of Example 1 was electrochemically stable during 1, 80, or 100 scans without overcurrent due to side reactions.

[0268] Evaluation Example 6: Evaluation of Charge and Discharge Characteristics of a Lithium-Air Battery

[0269] The lithium-air battery fabricated in Fabrication Example 1 was discharged at a constant current of 0.01 milliamperes per square centimeter (mA / cm 2 ) in an oxygen atmosphere at 60 °C and 1 atmosphere (atm) until 2.0 volts (V) (versus Li), and then charged with the same current until 4.25 V. The charge and discharge cycle was repeated. The charge and discharge test results of each lithium-air battery in the first cycle were examined.

[0270] As a result of the charge and discharge tests, it was confirmed that the lithium-air battery of Fabrication Example 1 using the solid electrolyte of Example 1 was stably driven.

[0271] The charge and discharge characteristics of the lithium-air batteries of Fabrication Examples 2 to 23 were evaluated in the same manner as the lithium-air battery of Fabrication Example 1.

[0272] From the evaluation results, it was found that the lithium-air batteries of Fabrication Examples 2 to 23 operated as stably as the lithium-air battery of Fabrication Example 1.

[0273] According to the embodiment, the solid electrolyte has improved ionic conductivity at room temperature, is stable against moisture in humid or atmospheric conditions, has improved stability in the presence of lithium, maintains excellent ionic conductivity, and has a high sheet density. When such a solid electrolyte is used, an electrochemical device with suppressed deterioration can be fabricated.

[0274] It should be understood that the embodiments described herein are to be considered only in a descriptive sense and not for purposes of limitation. The description of features, aspects, or advantages in each embodiment should be considered applicable to other similar features, aspects, or advantages in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, those of ordinary skill in the art will understand 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. Solid electrolyte, comprising: an oxide represented by Formula 1, Formula 2, Formula 3, or a combination thereof, Formula 1 Li 2+4x M1 1-x O 3 wherein, in Formula 1, M1 is hafnium, titanium, zirconium, or a combination thereof, and x is from 0.01 to 0.9; Formula 2 Li 2-y(a-4) M1 1-y M2 a y O 3 wherein, in Formula 2, M1 is hafnium, titanium, zirconium, or a combination thereof, M2 is at least one element having an oxidation value of a and is aluminum, gallium, indium, niobium, tantalum, vanadium, yttrium, lanthanum, scandium, magnesium, calcium, strontium, barium, zinc, cadmium, tungsten, molybdenum, vacancy, or a combination thereof, and wherein a is an integer from 1 - 6, and y is from 0.05 to 0.9; or Formula 3 Li 2-z M1O 3-z X z wherein, in Formula 3, M1 is hafnium, titanium, zirconium, or a combination thereof, X is a halogen, pseudohalogen, or a combination thereof, and 0 < z < 2.

2. The solid electrolyte according to claim 1, wherein, in Formulas 1 to 3, each M1 is independently hafnium, zirconium, or a combination thereof.

3. The solid electrolyte according to claim 1, wherein, in Formula 3, X is fluorine, chlorine, bromine, cyanide, cyanate, thiocyanate, azide, or a combination thereof.

4. The solid electrolyte according to claim 1, wherein, in Formula 2, a is 2, 3, 5, or 6.

5. The solid electrolyte according to claim 1, wherein, in Formula 3, z is from 0.05 to 1.

6. The solid electrolyte according to claim 1, wherein the oxide of Formula 1 is an oxide represented by Formula 4, an oxide represented by Formula 5, or a combination thereof: Formula 4 Li 2+4x Hf 1-x O 3 wherein, in Formula 4, 0.01 ≤ x ≤ 0.9, or Formula 5 Li 2+4x Zr 1-x O 3 wherein, in Formula 5, 0.01 ≤ x ≤ 0.

9.

7. The solid electrolyte according to claim 1, wherein the oxide of Formula 2 is an oxide represented by Formula 6, an oxide represented by Formula 7, or a combination thereof: Formula 6 Li 2-y(a-4) Hf 1-y M2 a y O 3 wherein, in Formula 6, M2 is aluminum, gallium, indium, niobium, tantalum, vanadium, yttrium, lanthanum, scandium, magnesium, calcium, strontium, barium, zinc, cadmium, tungsten, molybdenum, or a combination thereof, a is an integer from 1 - 6, and 0.05 ≤ y ≤ 0.9, or Formula 7 Li 2-y(a-4) Zr 1-y M2 a y O 3 wherein, in Formula 7, M2 is aluminum, gallium, indium, niobium, tantalum, vanadium, yttrium, lanthanum, scandium, magnesium, calcium, strontium, barium, zinc, cadmium, tungsten, molybdenum, or a combination thereof, a is an integer from 1 - 6, and 0.05 ≤ y ≤ 0.

9.

8. The solid electrolyte according to claim 1, wherein the oxide of Formula 3 is an oxide represented by Formula 8, an oxide represented by Formula 9, or a combination thereof: Formula 8 Li 2-z HfO 3-z X z wherein, in Formula 8, X is a halogen, pseudohalogen, or a combination thereof, and 0.05 ≤ z ≤ 1, or Formula 9 Li 2-z ZrO 3-z X z wherein, in Formula 9, X is a halogen, pseudohalogen, or a combination thereof, and 0.05 ≤ z ≤ 1.

9. The solid electrolyte according to claim 1, wherein the oxide has a rock - salt crystal structure.

10. The solid electrolyte according to claim 1, wherein the oxide has a C2 / c space group.

11. The solid electrolyte according to claim 1, wherein the oxide is Li 2.2 Hf 0.95 O 3 、Li 1.9 HfF 0.1 O 2.9 、Li 1.8 HfF 0.2 O 2.8 、Li 1.5 HfF 0.5 O 2.5 、Li 1.9 HfCl 0.1 O 2.9 、Li 1.8 HfCl 0.2 O 2.8 、Li 1.5 HfCl 0.5 O 2.5 、Li 1.9 HfF 0.05 Cl 0.05 O 2.9 、Li 1.8 HfF 0.1 Cl 0.1 O 2.8 、Li 1.8 HfBr 0.1 Cl 0.1 O 2.8 、Li 1.5 HfF 0.25 Cl 0.25 O 2.5 、Li 1.5 HfBr 0.25 Cl 0.25 O 2.5 、Li 2.2 Hf 0.8 Y 0.2 O 3 、Li 2.2 Hf 0.8 La 0.2 O 3 、Li 2.2 Hf 0.8 Sc 0.2 O 3 、Li 2.2 Hf 0.8 Al 0.2 O 3 、Li 1.8 Hf 0.8 Ta 0.2 O 3 、Li 1.8 Hf 0.8 Nb 0.2 O 3 、Li 1.8 Hf 0.8 V 0.2 O 3 、Li 2.2 Hf 0.9 Mg 0.1 O 3 、Li 2.2 Hf 0.9 Ca 0.1 O 3 、Li 2.2 Hf 0.9 Sr 0.1 O 3 、Li 2.2 Hf 0.9 Ba 0.1 O 3 、Li 2.2 Hf 0.9 Zn 0.1 O 3 、Li 2.2 Hf 0.9 Cd 0.1 O 3 、Li 2.2 Zr 0.95 O 3 、Li 1.9 ZrF 0.1 O 2.9 、Li 1.8 ZrF 0.2 O 2.8 、Li 1.5 ZrF 0.5 O 2.5 、Li 1.9 ZrCl 0.1 O 2.9 、Li 1.8 ZrCl 0.2 O 2.8 、Li 1.5 ZrCl 0.5 O 2.5 、Li 1.9 ZrF 0.05 Cl 0.05 O 2.9 、Li 1.9 ZrBr 0.05 Cl 0.05 O 2.9 、Li 1.8 ZrF 0.1 Cl 0.1 O 2.8 、Li 1.8 ZrBr 0.1 Cl 0.1 O 2.8 , Li 1.5 ZrF 0.25 Cl 0.25 O 2.5 , Li 1.5 ZrBr 0.25 Cl 0.25 O 2.5 , Li 2.2 Zr 0.8 Y 0.2 O 3 , Li 2.2 Zr 0.8 La 0.2 O 3 , Li 2.2 Zr 0.8 Sc 0.2 O 3 , Li 2.2 Zr 0.8 Al 0.2 O 3 , Li 1.8 Zr 0.8 Ta 0.2 O 3 , Li 1.8 Zr 0.8 Nb 0.2 O 3 , Li 1.8 Zr 0.8 V 0.2 O 3 , Li 2.2 Zr 0.9 Mg 0.1 O 3 , Li 2.2 Zr 0.9 Ca 0.1 O 3 , Li 2.2 Zr 0.9 Sr 0.1 O 3 , Li 2.2 Zr 0.9 Ba 0.1 O 3 , Li 2.2 Zr 0.9 Zn 0.1 O 3 , Li 2.2 Zr 0.9 Cd 0.1 O 3 , Li 2.2 Hf 0.8 Ta 0.2 O 3 , Li 2.2 Hf 0.8 Nb 0.2 O 3 , Li 2.2 Hf 0.8 V 0.2 O 3 , Li 2.2 Zr 0.8 Ta 0.2 O 3 , Li 2.2 Zr 0.8 Nb 0.2 O 3 , Li 2.2 Zr 0.8 V 0.2 O 3 , or a combination thereof.

12. The solid electrolyte according to claim 1, wherein the solid electrolyte has an ionic conductivity of 1×10 -10 Siemens / cm or greater at 25°C.

13. The solid electrolyte according to claim 1, wherein when analyzed by X-ray diffraction using Cu Kα radiation, the oxide has diffraction peaks from crystal planes, crystal planes and crystal planes.

14. The solid electrolyte according to claim 1, wherein, when analyzed by X - ray diffraction using Cu Kα radiation, diffraction peaks exist at diffraction angles of 26.7 ± 0.5° 2θ, 35 ± 0.5° 2θ, 39 ± 0.5° 2θ, or a combination thereof.

15. The solid electrolyte according to claim 1, wherein the solid electrolyte has a sheet density of 2.6 g / cm³ to 5.1 g / cm³.

16. A metal-air battery, comprising: a positive electrode; a negative electrode; and an electrolyte between the positive electrode and the negative electrode, wherein the positive electrode, the negative electrode, the electrolyte, or a combination thereof comprises the solid electrolyte according to any one of claims 1-15.

17. The metal-air battery according to claim 16, wherein the negative electrode comprises lithium and the positive electrode is configured to use air as an active material.

18. An electrochemical device, comprising: the solid electrolyte according to any one of claims 1-15.

19. The electrochemical device according to claim 18, wherein the electrochemical device is a battery, a storage battery, a supercapacitor, a fuel cell, a sensor, or an electrochromic device.

20. A method for preparing a solid electrolyte, the method comprising: mixing a lithium precursor and an M1 precursor to prepare a precursor mixture; and thermally treating the precursor mixture to prepare the solid electrolyte according to any one of claims 1-15, and optionally adding an M2 precursor and an X precursor to the precursor mixture.

21. The method according to claim 20, wherein thermally treating the precursor mixture comprises thermally treating at 400 °C to 950 °C.

22. The method according to claim 20, further comprising pulverizing the thermally treated precursor mixture to form a pulverized product; and thermally treating the pulverized product.

23. The method according to claim 22, wherein thermally treating the pulverized product comprises thermally treating at 500 °C to 1300 °C.

24. The method according to claim 22, further comprising pressing the pulverized product to form a sheet before thermally treating the pulverized product.

25. A protective layer for a lithium battery, the protective layer comprising: the solid electrolyte according to any one of claims 1-15, wherein the solid electrolyte is disposed on a positive electrode or a negative electrode.

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