KR20230082562A - Solid ion conductor compound, electrochemical cell comprising the same, and preparation method thereof - Google Patents

Abstract

It relates to a solid ion conductor compound represented by Formula 1, an electrochemical cell including the same, and a method for preparing the solid ion conductor compound.

Description

Solid ion conductor compound, electrochemical cell containing the same, and manufacturing method thereof {Solid ion conductor compound, electrochemical cell comprising the same, and preparation method thereof}

It relates to a solid ion conductor compound, an electrochemical cell including the same, and a manufacturing method thereof.

An electrochemical cell, for example, an all-solid-state battery includes a solid electrolyte as an electrolyte. All-solid-state batteries have excellent stability because they do not contain flammable organic solvents.

Conventional solid electrolyte materials are not sufficiently stable to lithium metal and have limitations in that lithium ion conductivity is low. In order to solve these problems, sulfide-based solid electrolytes, halogen-based solid electrolytes, and oxide-based solid electrolytes are being studied.

Among them, sulfide-based solid electrolytes and oxide-based solid electrolytes have the advantage of having high ionic conductivity, but sulfide-based solid electrolytes react with water to generate toxic gases, and oxide-based solid electrolytes have limitations in that they have poor moldability. exist.

In contrast, halogen-based solid electrolytes are attracting attention in that they do not react with water to generate toxic gases and have excellent moldability. However, halogen-based solid electrolytes developed to date have limitations in that ionic conductivity is not satisfactory or stability is insufficient.

Therefore, there is still a need for a halogen-based solid electrolyte having high ionic conductivity and improved stability.

It is to provide a novel solid ion conductor compound having excellent lithium ion conductivity, an electrochemical cell including the same, and a manufacturing method thereof.

According to one aspect, a solid ion conductor compound represented by Formula 1 is provided:

<Formula 1>

Li _a M _b Zr _c X _d T _e

In Formula 1,

1<a<3.5, 0<b<1.5, 0<c<1.5, 0<d<7, 0≤e<1, 0<b/d<0.03, 0.05<c/d<0.18,

Element M is one or more monovalent metal elements other than lithium,

element T is a metal element different from M, a transition metal element, a post-transition metal element, a metalloid, or a combination thereof;

The ionic radius (M _r ) of element M is 90 pm<M _r ≤180 pm,

X is one or more halogen elements.

Preparing a mixture of a zirconium precursor compound, a lithium precursor compound, and a metal M precursor compound according to another aspect, wherein the metal M element is one or more monovalent metal elements other than lithium, and the ionic radius of the metal M element (M _r ) is 90 pm<M _r ≤180 pm; and

A method for producing a solid ion conductor compound is provided, including the step of reacting the mixture in a solid phase to obtain a solid ion conductor compound.

According to another aspect, a positive electrode layer including a positive electrode active material layer;

A negative electrode layer including a negative electrode active material layer; and

A solid electrolyte layer interposed between the anode layer and the cathode layer,

An electrochemical cell is provided in which at least one of the positive electrode layer and the solid electrolyte layer includes the above-described solid ion conductor compound.

Here, the electrochemical cell may be, for example, an all-solid secondary battery, a secondary battery containing a liquid electrolyte, or a lithium-air battery, but is not necessarily limited thereto, and any electrochemical cell usable in the art is possible.

According to one aspect, an electrochemical cell having improved stability and cycle characteristics is provided by including a solid ion conductor compound having improved lithium ion conductivity and stability to lithium metal.

1 is a view showing XRD spectra of solid ion conductor compounds prepared in Example 1 and Comparative Examples 1 and 2;
FIG. 2 is a diagram showing the degree of peak shift of Example 1 and Comparative Example 2 based on the position of the 2θ=32.3° peak of Comparative Example 1 in the XRD spectrum of FIG. 1 .
3 is a view showing calculated crystal lattice constants of the solid ion conductor compounds prepared in Example 1 and Comparative Examples 1 and 2.
4 is a diagram showing initial charge and discharge curves of all-solid-state secondary batteries of Example 13 and Comparative Examples 8 and 9;
5 is a diagram showing cycle characteristics of all-solid-state secondary batteries of Example 13 and Comparative Examples 8 and 9;
6 is a diagram showing the evaluation of the initial impedance of the all-solid-state secondary batteries of Example 13 and Comparative Example 9.
7 is a schematic diagram of an all-solid-state secondary battery according to an embodiment.
8 is a schematic diagram of an all-solid-state secondary battery according to an embodiment.
<Description of symbols for main parts of drawings>
1, 1a: all-solid-state secondary battery 10: positive electrode
11: positive electrode current collector 12: positive electrode active material layer
20: negative electrode 21: negative electrode current collector
22: negative electrode active material layer 23: metal layer
30: solid electrolyte layer 40: all-solid secondary battery

Various implementations are shown in the accompanying drawings. However, this inventive idea may be embodied in many different forms and should not be construed as being limited to the implementations described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive idea to those skilled in the art. Like reference numerals designate like components.

It will be understood that when an element is referred to as being “on” another element, it may be directly on top of the other element, or another element may be interposed therebetween. In contrast, when an element is referred to as being “directly on” another element, there is no intervening element between them.

Although the terms “first,” “second,” “third,” and the like may be used herein to describe various components, components, regions, layers, and/or regions, these components, components, regions, A layer and/or zone should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or region from another element, component, region, layer or region. Thus, a first component, component, region, layer or region described below could be termed a second component, component, region, layer or region without departing from the teachings herein.

Terms used in this specification are for describing only specific implementations and are not intended to limit the present inventive idea. The singular forms as used herein are intended to include the plural forms including “at least one” unless the context clearly dictates otherwise. “At least one” should not be construed as limiting to the singular. As used herein, the term “and/or” includes any and all combinations of one or more of the listed items. The terms "comprises" and/or "comprising" as used in the Detailed Description specify the presence of specified features, regions, integers, steps, operations, components, and/or components, and one or more other features, regions, integers, or integers. However, it does not exclude the presence or addition of steps, operations, components, components and/or groups thereof.

Spatially relative terms such as "below", "below", "lower", "above", "above", "above", etc., are used to facilitate describing the relationship of one component or feature to another component or feature. can be used here for It will be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientations shown in the figures. For example, if the device in the figures is turned over, elements described as “beneath” or “beneath” other elements or features will be oriented “above” the other elements or features. Thus, the exemplary term "below" can encompass both directions of up and down. The device may be positioned in other orientations (rotated 90 degrees or rotated in other directions) and the spatially relative terms used herein interpreted accordingly.

Unless defined otherwise, 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 is also understood that terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with that within the context of the related art and the present disclosure, and not in an idealized or overly formal sense. It will be.

Exemplary implementations are described herein with reference to cross-sectional views that are schematic diagrams of idealized implementations. As such, variations from the illustrated shape should be expected as a result of, for example, manufacturing techniques and/or tolerances. Thus, the embodiments described herein should not be construed as being limited to the specific shapes of regions as shown herein, but should include deviations in shapes resulting, for example, from manufacturing. For example, regions shown or described as flat may typically be rough and/or have non-linear features. Moreover, the angles shown as sharp may be round. Accordingly, the regions depicted in the drawings are schematic in nature and the shapes are not intended to depict the exact shape of the region and are not intended to limit the scope of the claims.

"Group" means a group of the Periodic Table of Elements according to the International Union of Pure and Applied Chemistry ("IUPAC") Groups 1-18 grouping system.

While particular embodiments have been described, currently unforeseen or unforeseeable alternatives, modifications, variations, improvements, and substantial equivalents may occur to applicants or those skilled in the art. Accordingly, the appended claims as filed and as may be amended are intended to embrace all such alternatives, modifications, variations, improvements and substantial equivalents.

Hereinafter, a solid ion conductor compound according to one or more exemplary embodiments, an electrochemical cell including the same, and a method for preparing the solid ion conductor compound will be described in more detail.

[Solid ion conductor compound]

The solid ion conductor compound according to one aspect may be represented by Formula 1 below:

<Formula 1>

Li _a M _b Zr _c X _d T _e

In Formula 1, element M is one or more monovalent metal elements other than lithium, and the ionic radius (M _r ) of element M may be 90pm<M _r ≤180pm. Here, the ionic radius (M _r ) means the radius of a monoatomic ion in an ionic crystal structure.

According to one embodiment, the element M may include Na, K, Rb, Mo(I), Cu(I), Hg, Ag, Au, Tl, or a combination thereof. For example, the element M may include Na, K, Cu(I), Ag, or a combination thereof.

According to one embodiment, M _r of the M element is 90 pm<M _r ≤175 pm, 90 pm<M _r ≤170 pm, 90 pm<M _r ≤165 pm, 90 pm<M _r ≤160 pm, or 90 pm<M _r ≤155 pm, but is not limited thereto.

M _r of the M element has an ionic radius larger than the ionic radius of Li ions, and when the above range is satisfied, the lattice constant can be increased without collapse of the crystal structure inside the solid ion conductor compound, and as a result, Li The ion passage is sufficiently enlarged to have an effect of improving lithium ion conductivity.

According to one embodiment, the M element may be substituted at a Li site, substituted at a Zr site, and/or inserted at an empty lattice point in the crystal structure of the solid ion conductor compound.

Since the M element has a monovalent oxidation number, it does not cause severe distortion that causes crystal collapse due to charge imbalance even when inserted into the crystal, and does not cause crystal collapse due to excessive lattice expansion by satisfying a specific ionic radius range.

Accordingly, the lithium ion passage is expanded according to the volume expansion of the crystal, and as a result, a solid ion conductor compound having improved lithium ion conductivity compared to a compound in which M element is not substituted is obtained.

According to another embodiment, the M element may exist as a mixture without being substituted for the Zr site in the crystal.

Even when the M element is not substituted in the lattice in the crystal of the solid ion conductor compound and exists as a mixture, it has an effect of increasing the crystal lattice constant, thereby improving lithium ion conductivity according to the increase in crystal volume.

In Formula 1, X may be a halogen element, for example, one or more selected from F, Cl, Br, and I.

According to one embodiment, the X may include Cl, Br, or a combination thereof. For example, the X may be Cl. When X contains Cl, the activation energy is reduced and excellent lithium ion conductivity can be obtained.

According to another embodiment, the X may include Cl and Br. Since the solid ion conductor compound includes Cl and Br as halogen elements, activation energy is reduced, and lithium ion conductivity can be further improved as the proportion of the amorphous phase in the compound is increased.

In Formula 1, element T may be a metal element different from M, a transition metal element, a post-transition metal element, a metalloid element, or a combination thereof.

According to one embodiment, the T is B, Be, Mg, Ca, Sr, Se, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os , Co, Rh, Ir, Ni, Pd, Pt, Zn, Cd, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Po, or one or more combinations thereof.

For example, T may be B, Y, Mg, Ca, Sr, Hf, Al, Ga, Bi, Sc, Sb, Ta, Nb, or a combination of one or more thereof.

In Formula 1, 1<a<3.5, 0<b<1.5, 0<c<1.5, 0<d<7, 0≤e<1, 0<b/d<0.03, 0.05<c/d<0.18 can be

According to one embodiment, a may be 1.5≤a≤2.5. For example, the a may be 1.6≤a≤2.4, 1.7≤a≤2.3, 1.8≤a≤2.2, 1.9≤a≤2.1, or 1.9≤a≤2.0.

According to one embodiment, b may be 0<b<0.5. For example, b may be 0<b≤0.4, 0<b≤0.3, 0<b≤0.2, or 0<b≤0.1.

According to one embodiment, c may be 0.1≤c<1.5. For example, 0.2≤c≤1.4, 0.3≤c≤1.3, 0.4≤c≤1.2, or 0.5≤c≤1.1.

According to one embodiment, d may be 5<d<7. For example, 5.1≤d≤6.9, 5.2≤d≤6.8, 5.3≤d≤6.7, 5.4≤d≤6.6, 5.5≤d≤6.5, 5.6≤d≤6.4, 5.7≤d≤6.3, 5.8≤d≤ 6.2, 5.9≤d≤6.1.

According to one embodiment, e may be 0≤e<1. For example, 0≤e<0.9, 0≤e<0.8, 0≤e<0.7, 0≤e<0.6 0≤e≤0.5, 0<e<1, 0<e<0.9, 0<e<0.8 , 0<e<0.7, 0<e<0.6, or 0<e≤0.5.

According to one embodiment, a may satisfy 1.5≤a≤2.5, b may satisfy 0<b<0.5, c may satisfy 0.1≤c<1.5, and d may satisfy 5<d<7.

According to one embodiment, b/d may be 0.01≤b/d≤0.02.

According to one embodiment, c/d may be 0.06≤c/d≤0.17.

According to one embodiment, a/c may be 1<a/c<5. For example, 1<a/c≤4, 1<a/c≤3, 1<a/c≤2.9, 1<a/c≤2.8, 1<a/c≤2.7, 1<a/c≤ 2.6, 1<a/c≤2.5, 1<a/c≤2.4, 1<a/c≤2.3, 1<a/c≤2.2, 1<a/c≤2.1, or 1<a/c<2.1 can be

In Formula 1, when a, b, c, d, e, b/d, c/d, and a/c satisfy the above-mentioned range, improved lithium ion conductivity of the solid ion conductor compound and stable electricity using the same It is possible to manufacture a chemical cell.

According to one embodiment, the solid ion conductor compound may have at least one diffraction peak at diffraction angles 2θ = 15 ° to 17 °, 30 ° to 32 ° and 40 ° to 42 ° in the XRD spectrum using CuKα rays. .

For example, the solid ion conductor compound has diffraction angles 2θ=16.0°±2.0°, 30.4°±2.0°, 31.8°±2.0°, 34.1°±2.0°, 41.3°±2.0° in the XRD spectrum using CuKα rays. and a diffraction peak at 49.4±2.0°.

According to one embodiment, the a and c-axis lattice constants of the solid ion conductor compound may be increased compared to the compound containing no M metal element.

As will be described later, when the XRD graph of the solid ion conductor compound according to one embodiment of the present invention and the compound in which M is absent in Formula 1 of the solid ion conductor compound are compared, the solid ion conductor compound in which M is absent in Formula 1 is shown. It can be seen that the diffraction peak at the diffraction angle 2θ=32.5°±0.5° is shifted to the diffraction angle 2θ=31.5°±0.5°. In addition, the diffraction peak at the diffraction angle 2θ=31.5°±0.5° has an increased full width at half maximum (FWHM) compared to the diffraction peak at the diffraction angle 2θ=32.5°±0.5°. The shift of the peak and the increase in the full width at half maximum are due to the increase in the crystal volume due to the increase in the crystal lattice constant due to the introduction of the M element.

According to one embodiment, the solid ion conductor compound may include a crystalline phase, an amorphous phase, or a combination thereof.

According to one embodiment, the solid ion conductor compound includes a first crystalline phase and a second crystalline phase, the first crystalline phase and the second crystalline phase are the same or different, and an amorphous phase is formed between the first crystalline phase and the second crystalline phase. can include more.

When the solid ion conductor compound includes at least one crystalline phase and an amorphous phase, and the amorphous phase is included between the crystalline phases, the conductivity of lithium cations may be improved. In general, excellent lithium ion conductivity is obtained in an ordered crystal phase, but the lithium ion conductivity is further improved by including an amorphous phase in which lithium ions move easily between crystal phases.

According to one embodiment, the crystal phase, for example, at least one of the first crystal phase and the second crystal phase may include a layered rock salt crystal structure.

For example, the layered rock salt crystal structure may include a distorted layered rock salt crystal structure.

According to one embodiment, the solid ion conductor compound may include a crystal structure of a C2/m space group, a crystal structure of a P3m1 space group, or a combination thereof as a crystal phase.

According to one embodiment, the solid ion conductor compound may have an ionic conductivity of 2.4 x 10 ^-4 S/cm or more at room temperature, for example, 25°C. For example, the solid ion conductor compound has 2.5 x 10 ^-4 S/cm or more, 3.0 x 10 ^-4 S/cm or more, 3.5 x 10 ^-4 S/cm or more, 4.0 x 10 ^-4 S/cm or more at 25°C. cm or more, 4.1 x 10 ^-4 S/cm or more, 4.2 x 10 ^-4 S/cm or more, 4.3 x 10 ^-4 S/cm or more, or 4.4 x 10 ^-4 S/cm or more.

According to one embodiment, the solid ion conductor compound is Li _a Na _b Zr _c Cl _d T _e (1<a<3.5, 0<b<1.5, 0<c<1.5, 0<d<7, 0≤e <1), Li _a K _b Zr _c Cl _d T _e (1<a<3.5, 0<b<1.5, 0<c<1.5, 0<d<7, 0≤e<1), Li _a Rb _b Zr _c Cl _d T _e (1<a<3.5, 0<b<1.5, 0<c<1.5, 0<d<7, 0≤e<1), Li _a Mo _b Zr _c Cl _d T _e (1 <a<3.5, 0<b<1.5, 0<c<1.5, 0<d<7, 0≤e<1), Li _a Cu _b Zr _c Cl _d T _e (1<a<3.5, 0<b <1.5, 0<c<1.5, 0<d<7, 0≤e<1), Li _a Hg _b Zr _c Cl _d T _e (1<a<3.5, 0<b<1.5, 0<c<1.5 , 0<d<7, 0≤e<1), Li _a Ag _b Zr _c Cl _d T _e (1<a<3.5, 0<b<1.5, 0<c<1.5, 0<d<7, 0 ≤e<1), Li _a Au _b Zr _c Cl _d T _e (1<a<3.5, 0<b<1.5, 0<c<1.5, 0<d<7, 0≤e<1), or Li _a Tl _b Zr _c Cl _d T _e (1<a<3.5, 0<b<1.5, 0<c<1.5, 0<d<7, 0≤e<1), where T is Y can

For example, the solid ion conductor compound is Li _1.96 Na _0.03 ZrCl _{6 ,} Li _1.96 Na _0.04 ZrCl ₆ , Li _1.9 Na _0.1 ZrCl _{6 ,} Li ₂ Na _0.04 Zr _0.99 Cl ₆ , Li ₂ Na _0.1 Zr _0.98 Cl ₆ , Li _1.96 Cu _0.04 ZrCl ₆ , Li ₂ Cu _0.04 Zr _0.99 Cl ₆ , Li _1.96 Ag _0.04 ZrCl ₆ , Li _1.96 K _0.04 ZrCl ₆ , Li _1.96 Na _0.04 Y _0.5 Zr _0.5 Cl _{6 ,} Li _1.9 K _0.1 ZrCl ₆ , Li _{1.85K 0.15} ZrCl ₆ , Li _2.36 Na _0.04 Zr _0.9 Cl ₆ , or Li _2.45 Na _0.05 Zr _0.5 Cl ₆ Y _0.5 .

[Method of producing solid ion conductor compound]

A method for preparing a solid ion conductor compound according to an aspect includes preparing a mixture by mixing a zirconium precursor compound, a lithium precursor compound, and a metal M precursor compound; and obtaining a solid ion conductor compound by reacting the mixture in a solid phase. The solid ion conductor compound is the aforementioned solid ion conductor compound.

The lithium precursor compound may include a lithium halide. For example, the lithium halide may include LiF, LiCl, LiBr, LiI, or combinations thereof. For example, the lithium halide may include LiCl, LiBr, or a combination thereof.

The zirconium precursor compound may include a zirconium halide. For example, zirconium halides are ZrF ₄ , ZrCl ₄ . ZrBr ₄ , ZrI ₄ , or a combination thereof. For example, the zirconium halide may include ZrCl ₄ , ZrBr ₄ , or a combination thereof.

The M precursor compound may include a halide of at least one metal M selected from Na, K, Rb, Mo(I), Cu(I), Hg, Ag, Au, and Tl. For example, the M precursor compound may include NaCl, KCl, RbCl, CuCl, HgCl, AgCl, AuCl, TlCl, NaBr, KBr, RbBr, CuBr, HgBr, AgBr, AuBr, TlBr, or a combination thereof. . For example, the M precursor compound may include NaCl, KCl, CuCl, AgCl, or a combination thereof.

According to one embodiment, the lithium halide and the zirconium halide may be mixed in a stoichiometric ratio of 1:1 to 5:1. For example, the lithium halide and the zirconium halide have a stoichiometric ratio of 1:1 to 4.5:1, 1:1 to 4:1, 1:1 to 3.5:1, 1:1 to 3:1, 1.1:1 to 2.9:1, 1.2:1 to 2.8:1, 1.3:1 to 2.7:1, 1.4:1 to 2.6:1, 1.5:1 to 2.5:1, 1.6:1 to 2.4:1, 1.7:1 to 2.3 :1, 1.8:1 to 2.2:1, or 1.9:1 to 2.1:1, but is not limited thereto.

According to one embodiment, the M precursor compound and the zirconium halide may be mixed in a stoichiometric ratio of 0.01:1 to 1:1. For example, the M precursor compound and zirconium halide may be mixed at a stoichiometric ratio of 0.01:1 to 0.5:1 or 0.01:1 to 0.3:1, but is not limited thereto.

According to one embodiment, the mixture may further include a T precursor compound. In the T precursor compound, the T element may be a metal element different from M, a transition metal element, or a halide of a post-transition metal element. For example, the T precursor compound may be a halide of Y, Mg, Ca, Sr, Hf, Al, Ga, Bi, Sc, Sb, Ta, or Nb. Examples of T precursor compounds include YCl ₃ , YBr ₃ , MgCl ₂ , MgBr ₂ , CaCl ₂ , and CaBr ₂ .

According to one embodiment, the step of obtaining a solid ion conductor compound by reacting the mixture in a solid phase may include performing ball mill mixing of the mixture at 500 rpm for 48 hours in a dry and inert atmosphere.

According to one embodiment, the ball mill mixing may be performed for a first time and then have a rest period for a second time. Here, the first time and the second time may be the same as or different from each other. For example, the first time may be two or more times the second time, for example, three times the time. In this way, by having a rest period in the ball mill mixing process, the solid ion conductor compound can be obtained as a mixture of a crystalline phase and an amorphous phase.

According to one embodiment, the method for preparing the solid ion conductor compound is performed at room temperature and does not include a sintering step for crystallization. For example, the method for preparing the solid ion conductor compound may be performed at room temperature (25° C.).

A general method for producing a solid ion conductor compound includes a step of crystallizing by heat treatment after mixing raw materials, but the method for preparing a solid ion conductor compound of the present invention does not include a separate crystallization step after the solid phase mixing step, so that Zr And it is possible to obtain a solid ion conductor compound containing metal M, having a crystalline phase and an amorphous phase, and having an effect of improving lithium ion conductivity according to an increase in the volume of the crystalline phase.

The inert atmosphere is an atmosphere containing an inert gas. The inert gas is, for example, nitrogen, argon, etc., but is not necessarily limited thereto, and any one used as an inert gas in the art is possible.

[Electrochemical cell]

An electrochemical cell according to another embodiment includes a cathode layer including a cathode active material layer; A negative electrode layer including a negative electrode active material layer; and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, and at least one of the positive electrode layer and the solid electrolyte layer may include the above-described solid ion conductor compound. By including the solid ion conductor compound in the electrochemical cell, lithium ion conductivity and chemical stability of the electrochemical cell are improved.

The electrochemical cell may be, for example, an all-solid secondary battery, a secondary battery containing a liquid electrolyte, or a lithium-air battery, but is not necessarily limited thereto, and any electrochemical cell usable in the art is possible.

Hereinafter, an all-solid-state secondary battery will be described as an example.

[All-solid-state secondary battery: 1st type]

It may include the above solid ion conductor compound.

An all-solid-state secondary battery may include, for example, a cathode layer including a cathode active material layer; A negative electrode layer including a negative electrode active material layer; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and at least one of the positive electrode active material layer and the solid electrolyte layer may include the above-described solid ion conductor compound.

An all-solid-state secondary battery according to one embodiment may be prepared as follows.

(solid electrolyte layer)

First, a solid electrolyte layer is prepared.

The solid electrolyte layer may be prepared by mixing and drying the above-described solid ion conductor compound and a binder, or by rolling the powder of the solid ion conductor compound represented by Chemical Formula 1 in a constant shape at a pressure of 1 ton to 10 ton. The solid ion conductor compound described above is used as a solid electrolyte.

An average particle diameter of the solid electrolyte may be, for example, 0.5 um to 20 um. When the solid electrolyte has such an average particle diameter, the binding property is improved during the formation of the sintered body, and thus the ionic conductivity and lifespan characteristics of the solid electrolyte particles can be improved.

The thickness of the solid electrolyte layer may be 10um to 200um. By having such a thickness of the solid electrolyte layer, a sufficient movement rate of lithium ions is ensured, and as a result, high ionic conductivity can be obtained.

The solid electrolyte layer may further include a solid electrolyte such as a conventional sulfide-based solid electrolyte and/or an oxide-based solid electrolyte in addition to the above-described solid ion conductor compound.

A conventional sulfide-based solid electrolyte may include, for example, lithium sulfide, silicon sulfide, phosphorus sulfide, boron sulfide, or a combination thereof. Conventional sulfide-based solid electrolyte particles may include Li ₂ S, P ₂ S ₅ , SiS ₂ , GeS ₂ , B ₂ S ₃ or a combination thereof. Conventional sulfide-based solid electrolyte particles may be Li ₂ S or P ₂ S ₅ . Conventional sulfide-based solid electrolyte particles are known to have higher lithium ion conductivity than other inorganic compounds. For example, a conventional sulfide-based solid electrolyte includes Li ₂ S and P ₂ S ₅ . When the sulfide solid electrolyte material constituting the conventional sulfide-based solid electrolyte includes Li ₂ SP ₂ S ₅ , the mixing molar ratio of Li ₂ S to P ₂ S ₅ is, for example, about 50:50 to about 90:10. range can be In addition, Li ₃ PO ₄ , halogen, halogen compounds, Li _2+2x Zn _1-x GeO ₄ (“LISICON”), Li _3+y PO _4-x N _{x (} “LIPON”), Li _3.25 Ge _0.25 P _0.75 S ₄ ("ThioLISICON"), Li ₂ O—Al ₂ O ₃ -TiO ₂ -P ₂ O _{5 (} "LATP"), and the like as Li ₂ SP ₂ S ₅ , SiS ₂ , GeS ₂ , B ₂ S ₃ , or An inorganic solid electrolyte prepared by adding a combination thereof to an inorganic solid electrolyte can be used as a conventional sulfide solid electrolyte. Non-limiting examples of conventional sulfide solid electrolyte materials include Li ₂ SP ₂ S ₅ ; Li ₂ SP ₂ S ₅ -LiX (X is a halogen element); Li ₂ SP ₂ S ₅ -Li ₂ O; Li ₂ SP ₂ S ₅ -Li ₂ O-LiI; Li ₂ S-SiS ₂ ; Li ₂ S-SiS ₂ -LiI; Li ₂ S-SiS ₂ -LiBr; Li ₂ S-SiS ₂ -LiCl; Li ₂ S-SiS ₂ -B ₂ S ₃ -LiI; Li ₂ S-SiS ₂ -P ₂ S ₅ -LiI; Li ₂ SB ₂ S ₃ ; Li ₂ S -P ₂ S ₅ -Z _m S _n (m and n are positive numbers, Z is Ge, Zn or G); Li ₂ S-GeS ₂ ; Li ₂ S-SiS ₂ -Li ₃ PO ₄ ; and Li ₂ S-SiS ₂ -Li _p MO _q (wherein p and q are positive numbers and M is P, Si, Ge, B, Al, Ga or In). In this regard, a conventional sulfide-based solid electrolyte material is a raw material starting material (eg, Li ₂ S, P ₂ S ₅ , etc.) of a sulfide-based solid electrolyte material is melt quenched (melt quenching method), mechanical milling method etc. can be produced by processing. Also, calcinations may be performed after the treatment.

The binder included in the solid electrolyte layer, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyvinyl alcohol It is not limited to the like or these, and all are possible as long as they are used as binders in the art. The binder of the solid electrolyte layer may be the same as or different from the binders of the positive electrode layer and the negative electrode layer.

(anode layer)

Next, an anode layer is prepared.

The cathode layer may be prepared by forming a cathode active material layer containing a cathode active material on a current collector. The average particle diameter of the cathode active material may be, for example, 2 um to 10 um.

Any positive electrode active material may be used without limitation as long as it is commonly used in a secondary battery. For example, it may be a lithium transition metal oxide or a transition metal sulfide. For example, one or more types of complex oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used, and specific examples include, Li _a A _1-b B ¹ _b D ¹ ₂ (In the above formula, 0.90 ≤ a ≤ 1.8, and 0 ≤ b ≤ 0.5); Li _a E _1-b B ¹ _b O _2-c D ¹ _c (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE _2-b B ¹ _b O _4-c D ¹ _c (wherein 0 ≤ b ≤ 0.5 and 0 ≤ c ≤ 0.05); Li _a Ni _1-bc Co _b B ¹ _c D ¹ _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li _a Ni _1-bc Co _{b B} ¹ _c O _2-α F ¹ _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _1-bc Co _{b B} ¹ _c O _2-α F ¹ _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _1-bc Mn _b B ¹ _c D ¹ _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li _a Ni _1-bc Mn _b B ¹ _c O _2-α F ¹ _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _1-bc Mn _b B ¹ _c O _2-α F ¹ ₂ (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _b E _c G _d O ₂ (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li _a Ni _b Co _c Mn _d GeO ₂ (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li _a NiG _b O ₂ (wherein 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li _a CoG _b O ₂ (wherein 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li _a MnG _b O ₂ (wherein 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li _a Mn ₂ G _b O ₄ (wherein 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); QO ₂ ; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₂ ; LiIO ₂ ; LiNiVO ₄ ; Li _(3-f) J ₂ (PO ₄ ) ₃ (0 ≤ f ≤ 2); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0 ≤ f ≤ 2); A compound represented by any one of the chemical formulas of LiFePO ₄ may be used. In the above formula, A is Ni, Co, Mn, or a combination thereof; B ¹ Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D ¹ O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F ¹ F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or combinations thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or combinations thereof. For example, LiCoO ₂ , LiMn _x O _2x (x=1, 2), LiNi _1-x Mn _x O _2x (0<x<1), Ni _1-xy Co _x Mn _y O ₂ (0≤x≤ 0.5, 0≤y≤0.5), Ni _1-xy Co _x Al _y O ₂ (0≤x≤0.5, 0≤y≤0.5), LiFePO ₄ , TiS ₂ , FeS ₂ , TiS ₃ , FeS _{3 ,} and the like.

It is also possible to use a compound in which a coating layer is added to the surface of such a compound, and it is also possible to use a mixture of the above-mentioned compound and a compound in which a coating layer is added. The coating layer applied to the surface of such a compound includes, for example, a coating element compound of an oxide, a hydroxide, an oxyhydroxide of a coating element, an oxycarbonate of a coating element, or a hydroxycarbonate of a coating element. The compound constituting the coating layer is amorphous or crystalline. The coating elements included in the coating layer include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer formation method is selected within a range that does not adversely affect the physical properties of the cathode active material. The coating method is, for example, spray coating, dipping method or the like. Since a specific coating method can be well understood by those skilled in the art, a detailed description thereof will be omitted.

The cathode active material includes, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the above-described lithium transition metal oxides. "Layered rock salt structure" means, for example, that an oxygen atom layer and a metal atom layer are arranged alternately and regularly in the <111> direction of a cubic rock salt type structure, whereby each atomic layer is formed on a two-dimensional plane. It is a structure that forms "Cubic rock salt structure" refers to a NaCl type structure, which is a type of crystal structure, and specifically, face centered cubic lattice (fcc) formed by positive and negative ions, respectively, unit lattice ) shows a structure displaced by 1/2 of the ridge. A lithium transition metal oxide having such a layered rock salt structure is, for example, LiNi _x Co _y Al _z O ₂ (NCA) (0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1) or LiNi _x' Co _y' Mn _z' O ₂ (NCM) (0 <x'< 1, 0 <y'< 1, 0 <z'< 1, x' + y' + z' = 1) is a ternary lithium transition metal oxide such as the like. When the cathode active material includes a ternary lithium transition metal oxide having a layered rock salt structure, energy density and thermal stability of the all-solid-state secondary battery 1 are further improved.

According to one embodiment, the positive electrode layer includes a positive electrode active material represented by LiNi _x Co _y Al _z O ₂ or LiNi _x' Co _y' Mn _z' O ₂ , where 0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1, 0 <x'< 1, 0 <y'< 1, 0 <z'< 1, x' + y' + z' = 1, Part or all of the surface of the cathode active material may be coated with a lithium ion conductor compound. For example, the lithium ion conductor compound may be a Li ₂ ZrO ₃ compound.

The positive electrode active material may be coated with any material known as a material for the coating layer of the positive electrode active material. For example, the coating layer of the cathode active material may be Li ₂ O-ZrO ₂ (LZO).

When the cathode active material includes, for example, nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, it is possible to increase the capacity density of an all-solid-state secondary battery and reduce metal elution of the cathode active material in a charged state. . As a result, cycle characteristics of the all-solid-state secondary battery in a charged state are improved.

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

The positive electrode active material layer may additionally include the above-described solid ion conductor compound.

The cathode active material layer may include a binder. The binder is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, or the like.

The cathode active material layer may include a conductive material. The conductive material is, for example, graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powder or the like.

The cathode active material layer may further include additives such as a filler, a coating agent, a dispersant, and an ion conductive auxiliary agent in addition to the above-described cathode active material, solid electrolyte, binder, and conductive material.

As fillers, coating agents, dispersants, ion conductivity aids, etc. that may be included in the cathode active material layer, known materials generally used in electrodes of solid-state secondary batteries may be used.

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

The cathode current collector may further include a carbon layer disposed on one side or both sides of the metal substrate. By additionally disposing the carbon layer on the metal substrate, it is possible to prevent the metal of the metal substrate from being corroded by the solid electrolyte included in the positive electrode layer and to reduce interface resistance between the positive electrode active material layer and the positive electrode current collector. The thickness of the carbon layer may be, for example, 1 um to 5 um. If the thickness of the carbon layer is too thin, it may be difficult to completely block contact between the metal substrate and the solid electrolyte. If the thickness of the carbon layer is too thick, the energy density of the all-solid-state secondary battery may decrease. The carbon layer may include amorphous carbon, crystalline carbon, and the like.

(cathode layer)

Next, the cathode layer is prepared.

The negative electrode layer may be manufactured in the same manner as the positive electrode layer, except that the negative electrode active material is used instead of the positive electrode active material. The negative electrode layer may be prepared by forming a negative electrode active material layer containing the negative electrode active material on the negative electrode current collector.

The negative electrode active material layer may additionally include the above-described solid ion conductor compound.

The anode active material may be lithium metal, a lithium metal alloy, or a combination thereof.

The anode active material layer may further include a conventional anode active material in addition to lithium metal, a lithium metal alloy, or a combination thereof. Conventional anode active materials may include, for example, at least one selected from the group consisting of metals alloyable with lithium, transition metal oxides, non-transition metal oxides, and carbon-based materials. Metals alloyable with lithium are, for example, Ag, Si, Sn, Al, Ge, Pb, Bi, Sb Si-Y alloys (wherein Y is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a transition metal, a rare earth element or a combination thereof, but not Si), a Sn-Y alloy (wherein Y is an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, a rare earth element, or a combination thereof, but not Sn) ) and the like. The element Y is Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, It may be Se, Te, Po, or a combination thereof. The transition metal oxide may be, for example, lithium titanium oxide, vanadium oxide, lithium vanadium oxide, or the like. The non-transition metal oxide may be, for example, SnO ₂ , SiO _x (0<x<2), or the like. The carbon-based material may be, for example, crystalline carbon, amorphous carbon or mixtures thereof. Crystalline carbon may be graphite such as amorphous, plate-shaped, flake-shaped, spherical or fibrous natural graphite or artificial graphite, and the amorphous carbon may be soft carbon (low-temperature calcined carbon) or hard carbon ), mesophase pitch carbide, calcined coke, and the like.

Referring to FIG. 7 , an all-solid-state secondary battery 40 according to an embodiment includes a solid electrolyte layer 30, a positive electrode layer 10 disposed on one side of the solid electrolyte layer 30, and a solid electrolyte layer 30. and a cathode layer 20 disposed on the other side. The positive electrode layer 30 includes a positive electrode active material layer 12 in contact with the solid electrolyte layer 30 and a positive electrode current collector 11 in contact with the positive electrode active material layer 12, and the negative electrode layer 20 includes a solid electrolyte layer 30 ) and a negative electrode active material layer 22 in contact with the negative electrode current collector 21 in contact with the negative electrode active material layer 22 . In the all-solid-state secondary battery 40, for example, the positive active material layer 12 and the negative active material layer 22 are formed on both sides of the solid electrolyte layer 30, and the positive active material layer 12 and the negative active material layer 22 ) is completed by forming the positive electrode current collector 11 and the negative electrode current collector 21 on each. Alternatively, in the all-solid secondary battery 40, for example, the negative electrode active material layer 22, the solid electrolyte layer 30, the positive electrode active material layer 12, and the positive electrode current collector 11 are formed on the negative electrode current collector 21. It is completed by layering sequentially.

[All-solid-state secondary battery: 2nd type]

Referring to FIGS. 7 to 8 , the all-solid-state secondary batteries 1 and 1a include, for example, a positive electrode layer 10 including a positive electrode active material layer 12 disposed on a positive electrode current collector 11; a negative electrode layer 20 including a negative electrode active material layer 22 disposed on the negative electrode current collector 21; and an electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20, and the positive electrode active material layer 12 and/or the electrolyte layer 30 may include the above-described solid ion conductor compound. there is.

An all-solid-state secondary battery according to another embodiment may be prepared as follows.

The positive electrode layer and the solid electrolyte layer are manufactured in the same manner as in the above-described all-solid-state secondary battery.

(cathode layer)

Next, the cathode layer is prepared.

7 to 8, the negative electrode layer 20 includes a negative electrode current collector 21 and a negative electrode active material layer 22 disposed on the negative electrode current collector 21, and the negative electrode active material layer 22 is, for example, For example, a negative electrode active material and a binder are included.

The anode active material included in the anode active material layer 22 has a particle form, for example. The average particle diameter of the particle-shaped negative electrode active material is, for example, 4um or less, 3um or less, 2um or less, 1um or less, or 900nm or less. The average particle diameter of the particle-shaped negative electrode active material is, for example, 10 nm to 4 um or less, 10 nm to 3 um or less, 10 nm to 2 um or less, 10 nm to 1 um or less, or 10 nm to 900 nm or less. When the anode active material has an average particle diameter within this range, reversible absorbing and/or desorbing of lithium may be more easily performed during charging and discharging. The average particle diameter of the negative electrode active material is, for example, a median diameter (D50) measured using a laser type particle size distribution analyzer.

The anode active material included in the anode active material layer 22 includes, for example, at least one selected from a carbon-based anode active material and a metal or metalloid anode active material.

The carbon-based negative electrode active material is particularly amorphous carbon. Amorphous carbon is, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene ), etc., but are not necessarily limited to these, and all are possible as long as they are classified as amorphous carbon in the art. Amorphous carbon has no crystallinity or very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon.

Metal or metalloid cathode active materials include gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). ), but is not necessarily limited thereto, and can be used as a metal anode active material or a semi-metal anode active material forming an alloy or compound with lithium in the art. For example, nickel (Ni) is not a metal anode active material because it does not form an alloy with lithium.

The anode active material layer 22 includes one kind of anode active material among these anode active materials or a mixture of a plurality of different anode active materials. For example, the anode active material layer 22 includes only amorphous carbon, or may include gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), or bismuth (Bi). ), at least one selected from the group consisting of tin (Sn) and zinc (Zn). Alternatively, the anode active material layer 22 may include amorphous carbon, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin ( Sn) and a mixture with at least one selected from the group consisting of zinc (Zn). The mixing ratio of the mixture of amorphous carbon and gold is, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1 as a weight ratio, but is not necessarily limited to these ranges, and the required total It is selected according to the characteristics of the solid secondary battery (1). Cycle characteristics of the all-solid-state secondary battery 1 are further improved by having such a composition of the negative electrode active material.

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

The binder included in the negative active material layer 22 is, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride/ Hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but not necessarily limited thereto, are all possible as long as they are used as binders in the art. The binder may be single or composed of a plurality of different binders.

As the negative active material layer 22 includes a binder, the negative active material layer 22 is stabilized on the negative electrode current collector 21 . In addition, cracking of the anode active material layer 22 is suppressed despite a change in volume and/or relative position of the anode active material layer 22 during charging and discharging. For example, when the anode active material layer 22 does not contain a binder, the anode active material layer 22 can be easily separated from the anode current collector 21 . When the anode active material layer 22 is separated from the anode current collector 21, a short circuit occurs when the anode current collector 21 contacts the solid electrolyte layer 30 at the exposed portion of the anode current collector 21. Chances increase. The negative electrode active material layer 22 is manufactured, for example, by applying a slurry in which materials constituting the negative electrode active material layer 22 are dispersed onto the negative electrode current collector 21 and drying it. Stable dispersion of the negative active material in the slurry is possible by including the binder in the negative active material layer 22 . For example, when the slurry is applied on the negative electrode current collector 21 by screen printing, it is possible to suppress clogging of the screen (for example, clogging by aggregates of the negative electrode active material).

The negative electrode active material layer 22 may further include additives used in the conventional all-solid-state secondary battery 1, such as fillers, coating agents, dispersants, and ion conductivity auxiliary agents.

The thickness of the negative electrode active material layer 22 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer 12 . The thickness of the negative electrode active material layer 22 is, for example, 1 um to 20 um, 2 um to 10 um, or 3 um to 7 um. If the thickness of the negative electrode active material layer 22 is too thin, lithium dendrites formed between the negative electrode active material layer 22 and the negative electrode current collector 21 collapse the negative electrode active material layer 22 to form an all-solid-state secondary battery 1 It is difficult to improve the cycle characteristics of If the thickness of the negative electrode active material layer 22 is excessively increased, the energy density of the all-solid-state secondary battery 1 is lowered and the internal resistance of the all-solid-state secondary battery 1 by the negative electrode active material layer 22 increases, resulting in an all-solid-state secondary battery The cycle characteristics of (1) are difficult to improve.

When the thickness of the negative active material layer 22 decreases, for example, the charging capacity of the negative active material layer 22 also decreases. The charge capacity of the negative electrode active material layer 22 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, or 2% compared to the charge capacity of the positive electrode active material layer 12. below The charge capacity of the negative electrode active material layer 22 is, for example, 0.1% to 50%, 0.1% to 40%, 0.1% to 30%, 0.1% to 20%, 0.1% compared to the charge capacity of the positive electrode active material layer 12. to 10%, 0.1% to 5%, or 0.1% to 2%. If the charge capacity of the negative electrode active material layer 22 is too small, the thickness of the negative electrode active material layer 22 becomes very thin, so lithium formed between the negative electrode active material layer 22 and the negative electrode current collector 21 during repeated charging and discharging processes. Since dendrites collapse the anode active material layer 22 , it is difficult to improve cycle characteristics of the all-solid-state secondary battery 1 . If the charging capacity of the negative electrode active material layer 22 is excessively increased, the energy density of the all-solid secondary battery 1 is lowered and the internal resistance of the all-solid secondary battery 1 by the negative electrode active material layer 22 increases. The cycle characteristics of the battery 1 are difficult to improve.

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

Referring to FIG. 8 , the all-solid-state secondary battery 1a may further include, for example, a metal layer 23 disposed between the negative electrode current collector 21 and the negative electrode active material layer 22 . The metal layer 23 includes lithium or a lithium alloy. Thus, the metal layer 23 acts, for example, as a lithium reservoir. Lithium alloys include, for example, Li-Al alloy, Li-Sn alloy, Li-In alloy, Li-Ag alloy, Li-Au alloy, Li-Zn alloy, Li-Ge alloy, Li-Si alloy, etc. It is not limited to, and all are possible as long as they are used as lithium alloys in the art. The metal layer 23 may be made of one of these alloys or lithium, or made of several types of alloys.

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

In the all-solid-state secondary battery (1a), the metal layer 23 is disposed between the negative electrode current collector 21 and the negative electrode active material layer 22 before assembly of the all-solid-state secondary battery 1, for example, or the all-solid-state secondary battery 1 After assembling, it is deposited between the negative electrode current collector 21 (21, 21a, 21b) and the negative electrode active material layer 22 by charging. When the metal layer 23 is disposed between the negative electrode current collector 21 and the negative electrode active material layer 22 before assembling the all-solid-state secondary battery 1a, since the metal layer 23 is a metal layer containing lithium, a lithium reservoir works as For example, lithium foil is disposed between the anode current collector 21 and the anode active material layer 22 before assembling the all-solid-state secondary battery 1a. As a result, cycle characteristics of the all-solid-state secondary battery 1a including the metal layer 23 are further improved. If the metal layer 23 is deposited by charging after assembly of the all-solid-state secondary battery 1a, since the metal layer 23 is not included during assembly of the all-solid-state secondary battery 1a, the energy of the all-solid-state secondary battery 1a density increases. For example, when charging the all-solid-state secondary battery 1, the charge exceeds the charge capacity of the negative electrode active material layer 22. That is, the negative electrode active material layer 22 is overcharged. At the beginning of charging, lithium is occluded in the negative electrode active material layer 22 . The anode active material included in the anode active material layer 22 forms an alloy or compound with lithium ions transferred from the cathode layer 10 . When charging exceeds the capacity of the negative electrode active material layer 22, for example, lithium is deposited on the back side of the negative electrode active material layer 22, that is, between the negative electrode current collector 21 and the negative electrode active material layer 22, and the deposited A metal layer corresponding to the metal layer 23 is formed by lithium. The metal layer 23 is a metal layer mainly composed of lithium (ie, metal lithium). This result is obtained by, for example, the anode active material included in the anode active material layer 22 is composed of a material forming an alloy or compound with lithium. During discharge, the negative active material layer 22 and the metal layer 23, that is, lithium in the metal layer is ionized and moves toward the positive electrode layer 10. Therefore, it is possible to use lithium as an anode active material in the all-solid-state secondary battery 1a. In addition, since the negative electrode active material layer 22 covers the metal layer 23, it serves as a protective layer for the metal layer 23 and at the same time suppresses precipitation growth of lithium dendrite. Therefore, short circuit and capacity reduction of the all-solid-state secondary battery 1a are suppressed, and as a result, cycle characteristics of the all-solid-state secondary battery 1a are improved. In addition, when the metal layer 23 is disposed by charging after assembly of the all-solid-state secondary battery 1a, the negative electrode current collector 21 and the negative electrode active material layer 22 and the region between them are, for example, the all-solid-state secondary battery It is a Li-free region that does not contain lithium (Li) in the initial state of (1a) or the state after discharge.

The negative electrode current collector 21 is made of, for example, a material that does not react with lithium, that is, does not form any alloy or compound. The material constituting the negative electrode current collector 21 is, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not necessarily limited thereto. Anything that is used as an electrode current collector in the technical field is possible. The negative electrode current collector 21 may be made of one of the above-mentioned metals, or an alloy of two or more metals or a coating material. The negative electrode current collector 21 is, for example, in the form of a plate or foil.

The all-solid-state secondary battery 1 may further include, for example, a thin film including an element capable of forming an alloy with lithium on the negative electrode current collector 21 . The thin film is disposed between the anode current collector 21 and the anode active material layer 22 . The thin film contains an element capable of forming an alloy with, for example, lithium. Elements capable of forming an alloy with lithium include, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but are not necessarily limited to these, and those capable of forming an alloy with lithium in the art Any element is possible. The thin film is composed of one of these metals or an alloy of several metals. By placing the thin film on the negative electrode current collector 21, for example, the deposition form of the metal layer 23 deposited between the thin film 24 and the negative electrode active material layer 22 is further flattened, and the all-solid secondary battery 1 ) cycle characteristics can be further improved.

The thickness of the thin film is, for example, 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. When the thickness of the thin film is less than 1 nm, it may be difficult to exhibit the function of the thin film. If the thickness of the thin film is excessively thick, the thin film itself occludes lithium and the amount of lithium precipitated from the negative electrode decreases, thereby reducing the energy density of the all-solid-state battery and deteriorating cycle characteristics of the all-solid-state secondary battery 1 . The thin film may be disposed on the negative current collectors 21, 21a, and 21b by, for example, a vacuum deposition method, a sputtering method, a plating method, or the like, but is not necessarily limited to these methods, and any method capable of forming a thin film in the art can be used. possible.

Through the following Examples and Comparative Examples, this creative idea will be explained in more detail. However, the examples are for exemplifying the present creative idea, and the scope of the present creative idea is not limited only to them.

(Manufacture of solid ion conductor compound)

Example 1

In an Ar atmosphere glove box, zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor NaCl were added to a planetary ball mill at a stoichiometric ratio of 1: 1.96: 0.04, and zirconia After introducing (YSZ) balls, after grinding and mixing for 15 minutes at 500 rpm in an Ar atmosphere, a cycle having a rest period of 5 minutes was repeatedly performed for 48 hours to obtain a solid ion conductor compound having the composition shown in Table 1 below. got it Subsequently, the solid ion conductor compound obtained for XRD analysis was pressed at a uniaxial pressure of 300 MPa to prepare pellets having a thickness of about 1 mm and a diameter of about 13 mm.

Example 2

Except for changing the stoichiometric ratio of ZrCl ₄ as a zirconium precursor, LiCl as a lithium precursor, and NaCl as a metal M precursor to 1: 1.90: 0.1, using the same method as in Example 1 to obtain the composition shown in Table 1 below. A solid ion conductor compound was obtained, and pellets were prepared by molding it.

Example 3

Except for changing the stoichiometric ratio of zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor NaCl to 0.99: 2: 0.04, using the same method as in Example 1 to obtain the composition shown in Table 1 below. A solid ion conductor compound was obtained, and pellets were prepared by molding it.

Example 4

Except for changing the stoichiometric ratio of zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor NaCl to 0.98: 2: 0.1, using the same method as in Example 1 to obtain the composition shown in Table 1 below. A solid ion conductor compound was obtained, and pellets were prepared by molding it.

Example 5

Instead of zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor NaCl, the stoichiometric ratio of zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor CuCl was changed to 0.99:2:0.04. Except, using the same method as in Example 1 to obtain a solid ion conductor compound of the composition shown in Table 1, to prepare a pellet by molding it.

Example 6

Instead of zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor NaCl, the stoichiometric ratio of zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor CuCl was changed to 0.99:2:0.04. Except, using the same method as in Example 1 to obtain a solid ion conductor compound of the composition shown in Table 1, to prepare a pellet by molding it.

Example 7

Instead of ZrCl ₄ as a zirconium precursor, LiCl as a lithium precursor, and NaCl as a metal M precursor, the stoichiometric ratio of ZrCl ₄ as a zirconium precursor, LiCl as a lithium precursor, and AgCl as a metal M precursor was changed to 1:1.96:0.04. Except, using the same method as in Example 1 to obtain a solid ion conductor compound of the composition shown in Table 1, to prepare a pellet by molding it.

Example 8

Instead of zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor NaCl, the stoichiometric ratio of zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor KCl was changed to 1:1.96:0.04. Except, using the same method as in Example 1 to obtain a solid ion conductor compound of the composition shown in Table 1, to prepare a pellet by molding it.

Example 9

Instead of zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor NaCl, the stoichiometric ratio of zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor KCl was changed to 1:1.90:0.1 Except, using the same method as in Example 1 to obtain a solid ion conductor compound of the composition shown in Table 1, to prepare a pellet by molding it.

Example 10

Except for changing the stoichiometric ratio of ZrCl ₄ as a zirconium precursor, LiCl as a lithium precursor, and KCl as a metal M precursor to 1: 1.85: 0.15, using the same method as in Example 1 to obtain the composition shown in Table 1 below. A solid ion conductor compound was obtained, and pellets were prepared by molding it.

Example 11

Except for changing the stoichiometric ratio of zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor NaCl to 0.9: 2.36: 0.04, using the same method as in Example 1 to obtain the composition shown in Table 1 below. A solid ion conductor compound was obtained, and pellets were prepared by molding it.

Example 12

The same method as in Example 1 was used, except that the stoichiometric ratio of ZrCl ₄ as a zirconium precursor, LiCl as a lithium precursor, NaCl as a metal M precursor, and YCl ₃ as a metal T precursor was changed to 0.5:2.45:0.05:0.5. Thus, a solid ion conductor compound having the composition shown in Table 1 was obtained, and pellets were prepared by molding it.

Comparative Example 1

Instead of ZrCl ₄ as a zirconium precursor, LiCl as a lithium precursor, and NaCl as a metal M precursor, LiCl as a lithium precursor and ZrCl ₄ as a zirconium precursor were changed to the stoichiometric ratio at which the solid ion conductor compound of the composition shown in Table 1 was obtained. Then, using the same method as in Example 1, a solid ion conductor compound having the composition shown in Table 1 was obtained, and pellets were prepared by molding it.

Comparative Example 2

Instead of ZrCl ₄ as a zirconium precursor, LiCl as a lithium precursor, and NaCl as a metal M precursor, LiCl as a lithium precursor and HoCl ₃ as a holmium precursor were changed to the stoichiometric ratio at which the solid ion conductor compound of the composition shown in Table 1 was obtained. Then, using the same method as in Example 1, a solid ion conductor compound having the composition shown in Table 1 was obtained, and pellets were prepared by molding it.

Comparative Example 3

Instead of zirconium precursor ZrCl ₄ , lithium precursor LiCl, and metal M precursor NaCl, zirconium precursor ZrCl ₄ , lithium precursor LiCl, and CsCl were changed to a stoichiometric ratio at which the solid ion conductor compound having the composition shown in Table 1 was obtained. Except for one, solid ion conductor compounds having the composition shown in Table 1 were obtained using the same method as in Example 1, and pellets were prepared by molding them.

Comparative Example 4

ZrCl ₄ as a zirconium precursor, LiCl as a lithium precursor, and NaCl as a metal M precursor, ZrCl as a zirconium precursor ₄ , LiCl as a lithium precursor, and NaCl as a metal M precursor to obtain a solid ion conductor compound having the composition shown in Table 1 Except for changing the stoichiometric ratio for the solid ion conductor compound of the composition shown in Table 1 using the same method as in Example 1, to obtain a solid ion conductor compound, it was molded to prepare a pellet.

Comparative Example 5

ZrCl ₄ as a zirconium precursor, LiCl as a lithium precursor, and NaCl as a metal M precursor, ZrCl as a zirconium precursor ₄ , LiCl as a lithium precursor, and NaCl as a metal M precursor to obtain a solid ion conductor compound having the composition shown in Table 1 Except for changing the stoichiometric ratio for the solid ion conductor compound of the composition shown in Table 1 using the same method as in Example 1, to obtain a solid ion conductor compound, it was molded to prepare a pellet.

Comparative Example 6

ZrCl ₄ as a zirconium precursor, LiCl as a lithium precursor, and NaCl as a metal M precursor, ZrCl as a zirconium precursor ₄ , LiCl as a lithium precursor, and NaCl as a metal M precursor to obtain a solid ion conductor compound having the composition shown in Table 1 Except for changing the stoichiometric ratio for the solid ion conductor compound of the composition shown in Table 1 using the same method as in Example 1, to obtain a solid ion conductor compound, it was molded to prepare a pellet.

Comparative Example 7

Instead of ZrCl ₄ as a zirconium precursor, LiCl as a lithium precursor, and NaCl as a metal M precursor, ZrCl ₄ as a zirconium precursor and LiCl as a lithium precursor were changed to a stoichiometric ratio to obtain a solid ion conductor compound having the composition shown in Table 1 Except for that, using the same method as in Example 1, a solid ion conductor compound having the composition shown in Table 1 was obtained, and pellets were prepared by molding it.

(Manufacture of all-solid-state secondary battery)

Example 13

(Anode layer manufacturing)

As a cathode active material, LiNi _0.9 Co _0.05 Mn _0.05 O ₂ (NCM) was coated with Li ₂ ZrO ₃ (LZO) to prepare an LZO-NCM cathode active material. Powder was prepared by pulverizing the pellets of the solid ion conductor compound prepared in Example 1 as a solid electrolyte. Carbon nanofibers (CNF) were prepared as a conductive agent. A cathode mixture was prepared by mixing these materials in a weight ratio of LZO-NCM cathode active material:solid electrolyte:conductor = 60:52:5.

(Preparation of solid electrolyte powder)

Solid electrolyte powder was prepared by pulverizing the solid ion conductor compound prepared in Example 1 using an agate mortar.

In addition, a known solid electrolyte (Li ₆ PS ₅ Cl; purchased from Mitsui) was prepared.

(cathode layer manufacturing)

A metal lithium foil having a thickness of 20 um was prepared as an anode.

(Manufacture of all-solid-state secondary battery)

After sequentially stacking the negative electrode layer, the known solid electrolyte, the solid electrolyte powder prepared in Example 1, and the positive electrode mixture on the SUS lower electrode, press it for 3 minutes at a pressure of 300 MPa with one side press to prepare an all-solid secondary battery. did

Comparative Example 8

(Anode layer manufacturing)

As a cathode active material, LiNi _0.9 Co _0.05 Mn _0.05 O ₂ (NCM) was coated with Li ₂ ZrO ₃ (LZO) to prepare an LZO-NCM cathode active material. Powder was prepared by pulverizing the pellets of the solid ion conductor compound prepared in Comparative Example 1 as a solid electrolyte. Carbon nanofibers (CNF) were prepared as a conductive agent. A positive electrode mixture was prepared by mixing these materials in a weight ratio of positive electrode active material: solid electrolyte: conductive agent = 60:52:5.

(Preparation of solid electrolyte powder)

Solid electrolyte powder was prepared by pulverizing the solid ion conductor compound prepared in Comparative Example 1 using an agate mortar.

In addition, a known solid electrolyte (Li ₆ PS ₅ Cl; purchased from Mitsui) was prepared.

(cathode layer manufacturing)

A metal lithium foil having a thickness of 20 um was prepared as an anode.

(Manufacture of all-solid-state secondary battery)

A negative electrode layer, a known solid electrolyte, the solid electrolyte powder prepared in Comparative Example 1, and a positive electrode mixture were sequentially laminated on the SUS lower electrode, and then pressed for 3 minutes at a pressure of 300 MPa with a cold isostatic pressing device (CIP). An all-solid-state secondary battery was prepared.

Comparative Example 9

(Anode layer manufacturing)

As a cathode active material, LiNi _0.9 Co _0.05 Mn _0.05 O ₂ (NCM) was coated with Li ₂ ZrO ₃ (LZO) to prepare an LZO-NCM cathode active material. As a solid electrolyte, a known solid electrolyte (Li ₆ PS ₅ Cl; purchased from Mitsui) was prepared. Carbon nanofibers (CNF) were prepared as a conductive agent. A positive electrode mixture was prepared by mixing these materials in a weight ratio of positive electrode active material: solid electrolyte: conductive agent = 60:52:5.

(Preparation of solid electrolyte powder)

A known solid electrolyte (Li ₆ PS ₅ Cl; purchased from Mitsui) was prepared.

(cathode layer manufacturing)

A metal lithium foil having a thickness of 20 um was prepared as an anode.

(Manufacture of all-solid-state secondary battery)

An all-solid-state secondary battery was prepared by sequentially stacking a negative electrode layer, a known solid electrolyte, and a positive electrode mixture on the SUS lower electrode, and then pressing at a pressure of 300 MPa for 3 minutes using a cold isostatic pressing device (CIP).

Evaluation Example 1: X-ray diffraction experiment

After preparing powder by pulverizing the solid ion conductor compounds prepared in Example 1 and Comparative Examples 1 and 2 using an agate mortar, the powder XRD spectrum was measured and the results are shown in FIG. 1, Comparative Example 1, the position of the 2θ = 32.3 ° peak and the change in full width at half maximum (FWHM) are shown in FIG. 2, and the lattice constant of the crystal structure is calculated and shown in FIG.

Referring to FIGS. 1 to 3, it can be seen that both Example 1 and Comparative Example 1 have the same crystal structure of the P3m1 space group, and the lattice constant increases with Na doping, resulting in an increase in lattice volume by about 19%. was able to confirm

Evaluation Example 2: Measurement of ionic conductivity

After preparing powder by pulverizing the solid ion conductor compounds prepared in Examples 1 to 12 and Comparative Examples 1 to 7 using an agate mortar, the powder was pressed at a pressure of 4 ton/cm ² for 2 minutes to obtain a thickness A pellet specimen with a diameter of about 1 mm and a diameter of about 13 mm was prepared. A symmetry cell was prepared by sputtering platinum (Pt) on both sides of the prepared specimen and placing platinum (Pt) electrodes having a thickness of 10 μm and a diameter of 13 mm, respectively. The preparation of the symmetric cell was carried out in an Ar atmosphere glover box.

The impedance of the pellets was measured by a two-probe method using an impedance analyzer (VMP-3) for the specimens with platinum electrodes disposed on both sides. The frequency range was 1 Hz to 1 MHz, and the amplitude voltage was 20 mV. It was measured at 25°C in an Ar atmosphere. The resistance value was obtained from the arc of the Nyguist plot for the impedance measurement results, and the ionic conductivity was calculated considering the area and thickness of the specimen. The measurement results are shown in Table 1 below.

Referring to Table 1 below, compared to Comparative Example 2 not containing Zr and Comparative Example 1 containing Zr but not containing element M, the present invention showed up to 10 times improved ionic conductivity. In addition, it showed excellent ionic conductivity compared to Comparative Example 3 including an element having a larger ionic radius than the element M used in Examples.

In addition, in relation to the ratio (b / d) of the molar ratio (b) of the M element and the molar ratio (d) of the halogen element, and the ratio (c / d) of the molar ratio (c) of the Zr element and the molar ratio (d) of the halogen element , the compositions of examples in which the ranges of b / d and c / d satisfy 0 <b / d <0.03 and 0.05 <c / d <0.18, respectively, in Comparative Examples 1, 2, and 4 to 7 that do not satisfy these ranges In comparison, it showed excellent ionic conductivity.

These results suggest that together with the ionic radius of the M element, the ratio of the molar ratio of the M element and the halogen element and the ratio of the molar ratio of the Zr element and the halogen element affect the ionic conductivity.

Furtherance
(Li _a M _b Zr _c X _d T _e ) b/d CD ionic conductivity
(S cm ^-1 ) Example 1 Li _1.96 Na _0.04 ZrCl ₆ 0.01 0.17 1.1 x 10 ^-3 Example 2 Li _1.9 Na _0.1 ZrCl ₆ 0.02 0.17 5.5 x 10 ^-4 Example 3 Li ₂ Na _0.04 Zr _0.99 Cl ₆ 0.01 0.17 9.0 x 10 ^-4 Example 4 Li ₂ Na _0.1 Zr _0.98 Cl ₆ 0.02 0.17 5.6 x 10 ^-4 Example 5 Li _1.96 Cu _0.04 ZrCl ₆ 0.01 0.17 6.9 x 10 ^-4 Example 6 Li ₂ Cu _0.04 Zr _0.99 Cl ₆ 0.01 0.17 8.9 x 10 ^-4 Example 7 Li _1.96 Ag _0.04 ZrCl ₆ 0.01 0.17 5.4 x 10 ^-4 Example 8 Li _1.96 K _0.04 ZrCl ₆ 0.01 0.17 4.6 x 10 ^-4 Example 9 Li _1.9 K _0.1 ZrCl ₆ 0.02 0.17 4.4 x 10 ^-4 Example 10 Li _1.85 K _0.15 ZrCl ₆ 0.025 0.17 2.5 x 10 ^-4 Example 11 Li _2.36 Na _0.04 Zr _0.9 Cl ₆ 0.01 0.15 4.2 x 10 ^-4 Example 12 Li _2.45 Na _0.05 Zr _0.5 Cl ₆ Y _0.5 0.01 0.08 1.1 x 10 ^-3 Comparative Example 1 Li ₂ ZrCl ₆ - 0.17 4.0 x 10 ^-4 Comparative Example 2 Li ₃ HoCl ₆ - - 2.0 x 10 ^-4 Comparative Example 3 Li _1.96 Cs _0.04 ZrCl ₆ 0.01 0.17 2.3 x 10 ^-4 Comparative Example 4 Li _4.76 Na _0.04 Zr _0.3 Cl ₆ 0.01 0.05 3.5 x 10 ^-6 Comparative Example 5 Li _1.16 Na _0.04 Zr _1.2 Cl ₆ 0.01 0.2 1.7 x 10 ^-4 Comparative Example 6 Li _1.75 Na _0.25 ZrCl ₆ 0.04 0.17 9.1 x 10 ^-5 Comparative Example 7 Li _1.6 Zr _1.1 Cl ₆ - 0.18 2.3 x 10 ^-4

Evaluation Example 3: Cycle evaluation

The charge and discharge characteristics of the all-solid-state secondary batteries prepared in Example 13 and Comparative Examples 8 and 9 were evaluated by the following charge and discharge test.

In the first cycle of the charge/discharge test, the battery was charged with a constant current of 0.1C and a constant voltage of 4.2V until the battery voltage reached 4.2V until a current value of 0.1C was reached. Subsequently, discharging was performed at a constant current of 0.1 C until the battery voltage reached 2.5 V.

Initial efficiencies are shown in Table 2 below, and initial charge/discharge curves are shown in FIG. 4 .

Referring to Table 2 and FIG. 4, it can be seen that the initial efficiency of Example 13 is improved compared to Comparative Examples 8 and 9.

initial efficiency Example 13 96% Comparative Example 8 93% Comparative Example 9 88%

After the initial efficiency evaluation, the battery was charged with a constant current of 0.1C and a constant voltage of 4.2V until the battery voltage reached 4.2V until a current value of 0.1C was reached. Subsequently, discharging was performed at a constant current of 0.1 C until the battery voltage reached 2.5 V. Twenty such charge/discharge cycles were performed. The capacity in each cycle was measured and shown in FIG. 5 .

Referring to FIG. 5, Comparative Examples 8 and 9 show a trend in which the capacity gradually or significantly decreases, but the all-solid-state battery of Example 13 has a coulombic efficiency exceeding 99.7%, indicating that the capacity is maintained almost constant. Confirmed.

Evaluation Example 4: Interfacial Resistance Evaluation

For the all-solid-state batteries of Example 13 and Comparative Example 9, a voltage bias of 20 mV was applied at 25° C. in the frequency range of 10 ⁶ Hz to 0.1 MHz according to the 2-probe method using an impedance analyzer (VMP-3). The initial impedance was evaluated by measuring the resistance. These results, Nyquist plots, are shown in FIG. 6 .

Referring to FIG. 6, it was confirmed that the all-solid-state battery of Example 13 had a low anode interface resistance compared to the all-solid-state battery to which the existing sulfide-based solid electrolyte of Comparative Example 9 was applied, and that ion conduction was smooth.

Although the above has been described with reference to the embodiments shown in the drawings, this is only exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical scope of protection of the present invention should be determined by the technical spirit of the appended claims.

Claims (20)

A solid ion conductor compound represented by Formula 1:
<Formula 1>
Li _a M _b Zr _c X _d T _e
In Formula 1,
1<a<3.5, 0<b<1.5, 0<c<1.5, 0<d<7, 0≤e<1, 0<b/d<0.03, 0.05<c/d<0.18,
Element M is one or more monovalent metal elements other than lithium,
element T is a metal element different from M, a transition metal element, a post-transition metal element, a metalloid, or a combination thereof;
The ionic radius (M _r ) of element M is 90 pm<M _r ≤180 pm,
X is one or more halogen elements. According to claim 1,
Wherein M is Na, K, Rb, Mo(I), Cu(I), Hg, Ag, Au, Tl, or a solid ion conductor compound including a combination thereof. According to claim 1,
T is B, Be, Mg, Ca, Sr, Se, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir , Ni, Pd, Pt, Zn, Cd, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Po or a combination of one or more thereof, the solid ion conductor compound. According to claim 1,
The X is a solid ion conductor compound comprising Cl, Br or a combination thereof. According to claim 1,
The M _r is 90 pm<M _r ≤160 pm, the solid ionic conductor compound. According to claim 1,
a is 1.5≤a≤2.5, b is 0<b<0.5, c is 0.1≤c<1.5, and d is 5<d<7, a solid ionic conductor compound. According to claim 1,
e is 0<e<1, a solid ionic conductor compound. According to claim 1,
0.01≤b/d≤0.02, a solid ionic conductor compound. According to claim 1,
0.06≤c/d≤0.17, a solid ionic conductor compound. According to claim 1,
1<a/c<5, a solid ionic conductor compound. According to claim 1,
The solid ion conductor compound has at least one diffraction peak at diffraction angles 2θ = 15 ° to 17 °, 30 ° to 32 ° and 40 ° to 42 ° in the XRD spectrum using CuKα line, solid ion conductor compound. According to claim 1,
The solid ion conductor compound had diffraction angles of 2θ = 16.0 ° ± 2.0 °, 30.4 ° ± 2.0 °, 31.8 ° ± 2.0 °, 34.1 ° ± 2.0 °, 41.3 ° ± 2.0 ° and 49.4 ± 2.0 ° in the XRD spectrum using CuKα rays. A solid ionic conductor compound having a diffraction peak at °. According to claim 1,
The solid ion conductor compound is a solid ion conductor compound comprising a crystalline phase, an amorphous phase, or a combination thereof. According to claim 13,
The crystal phase is a solid ion conductor compound comprising a layered rock salt crystal structure. According to claim 13,
The crystalline phase comprises a crystal of the C2 / m space group, a crystal of the P3m1 space group, or a combination thereof, the solid ion conductor compound. According to claim 1,
The solid ion conductor compound has increased a and c axis lattice constants compared to the compound containing no M metal element. According to claim 1,
The solid ion conductor compound has an ion conductivity of 2.4 x 10 ^-4 S / cm or more at 25 ° C, a solid ion conductor compound. According to claim 1,
The solid ion conductor compounds are Li _1.96 Na _0.03 ZrCl ₆ , Li _1.96 Na _0.04 ZrCl ₆ , Li _1.9 Na _0.1 ZrCl _{6 ,} Li ₂ Na _0.04 Zr _0.99 Cl ₆ , Li ₂ Na _0.1 Zr _0.98 Cl ₆ , Li _1.96 Cu _0.04 ZrCl ₆ , Li ₂ Cu _0.04 Zr _0.99 Cl ₆ , Li _1.96 Ag _0.04 ZrCl ₆ , Li _1.96 K _0.04 ZrCl ₆ , Li _1.96 Na _0.04 Y _0.5 Zr _0.5 Cl ₆ , Li _1.9 K _0.1 ZrCl ₆ , Li _1.85 K _0.15 Zr Cl ₆ , Li _2.36 Na _0.04 Zr _0.9 Cl ₆ , or Li _2.45 Na _0.05 Zr _0.5 Cl ₆ Y _0.5 , a solid ionic conductor compound. A step of preparing a mixture of a zirconium precursor compound, a lithium precursor compound, and a metal M precursor compound, wherein the metal M element is one or more monovalent metal elements other than lithium, and the ionic radius (M _r ) of the metal M element is 90 pm<M _r ≤180 pm; and
A method for producing a solid ion conductor compound, comprising: reacting the mixture in a solid phase to obtain a solid ion conductor compound. According to claim 19,
The step of reacting the mixture in a solid phase to obtain a solid ion conductor compound,
Method for producing a solid ionic conductor compound comprising performing a ball mill mixing of the mixture in a dry and inert atmosphere.

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