KR20200135210A - Solid conductor, Preparation method thereof, solid electrolyte including the solid conductor, and electrochemical device including the same - Google Patents

Abstract

A solid conductor including a compound represented by the following Formula 1: Li_(1+x+y-z)Ta_(2-x)M_XP_(1-y)N_yO_(8-z)X_z, a compound represented by the following Formula 2: Li_(1+x+y-z)Ta_(2-x)M_xP_(1-y)N_yO_8·zLiX, or a combination thereof, a method for preparing the same, a solid electrolyte and an electrochemical device including the same are provided. In Formulas 1 and 2, M, N, x, y, z, and X are as defined in the detailed description. The solid conductor has improved ion conductivity and excellent lithium stability.

Description

Solid conductor, preparation method thereof, solid electrolyte including the solid conductor, and electrochemical device including the same}

It relates to a solid conductor, a method of manufacturing the same, a solid electrolyte and an electrochemical device including the same.

Lithium secondary batteries have a large electrochemical capacity, high operating potential, and excellent charge/discharge cycle characteristics, so they are in demand for applications such as portable information terminals, portable electronic devices, small household power storage devices, motorcycles, electric vehicles, and hybrid electric vehicles. Is increasing. With the proliferation of such uses, there is a demand for improved safety and high performance of lithium secondary batteries.

As lithium secondary batteries use liquid electrolytes, they are easily ignited when exposed to water in the air, and stability problems have always been raised. This stability problem is becoming more and more an issue as electric vehicles become visible. Accordingly, in recent years, for the purpose of improving safety, research on an all-solid-state secondary battery using a solid electrolyte made of an inorganic material has been actively conducted. The all-solid secondary battery is attracting attention as a next-generation secondary battery from the viewpoint of stability, high energy density, high output, long life, simplification of manufacturing processes, large-sized, compact, and low-cost batteries.

An all-solid secondary battery consists of a positive electrode, a solid electrolyte, and a negative electrode, and the double solid electrolyte requires high ionic conductivity and low electronic conductivity. Solid electrolytes for all-solid secondary batteries include sulfide-based solid electrolytes and oxide-based solid electrolytes. Among them, the oxide-based solid electrolyte does not generate toxic substances during the manufacturing process and has excellent stability of the material itself, but has a limitation in low room temperature ion conductivity compared to the sulfide-based oxide. Accordingly, a lot of research is being focused on developing solid conductors with high ionic conductivity and excellent stability at room temperature.

One aspect is to provide a solid conductor having improved ionic conductivity and improved lithium stability, and a method of manufacturing the same.

Another aspect is to provide a solid electrolyte including the solid conductor.

Another aspect is to provide an electrochemical device including the above-described solid conductor.

According to one aspect,

A solid conductor including a compound represented by the following formula (1), a compound represented by formula (2), or a combination thereof is provided.

<Formula 1>

Li _1+x+yz Ta _2-x M _x P _1-y N _y O _8-z X _z

In Formula 1, M is an element having an oxidation number 4+,

N is an element with oxidation number +4,

X is a halogen atom, pseudohalogen, or a combination thereof,

0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z Except for =2,

<Formula 2>

Li _1+x+yz Ta _2-x M _x P _1-y N _y O ₈ zLiX

In Formula 2, M is an element having oxidation number +4,

N is an element with oxidation number +4,

X is a halogen atom, pseudohalogen, or a combination thereof,

0≤x≤2, 0≤y<1, 0≤z≤2, i) When x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O, z If =1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z=2 Except for

According to the other side

Obtaining a precursor mixture by mixing the precursor for forming a solid conductor according to another aspect;

There is provided a method for producing the above-described solid conductor for obtaining a solid conductor represented by Formula 1, a solid conductor represented by Formula 2, or a combination thereof, including the step of heat-treating the precursor mixture in an oxidizing gas atmosphere.

<Formula 1>

Li _1+x+yz Ta _2-x M _x P _1-y N _y O _8-z X _z

In Formula 1, M is an element having an oxidation number 4+,

N is an element with oxidation number +4,

X is a halogen atom, pseudohalogen, or a combination thereof,

0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z Except for =2,

<Formula 2>

Li _1+x+yz Ta _2-x M _x P _1-y N _y O ₈ zLiX

In Formula 2, M is an element having oxidation number +4,

N is an element with oxidation number +4,

X is a halogen atom, pseudohalogen, or a combination thereof,

0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z The case of =2 is excluded.

The heat treatment may be performed at 500 to 1200°C.

The heat treatment includes a first heat treatment and a second heat treatment performed at a temperature higher than the first heat treatment, the first heat treatment is performed at 500 to 1000°C, and the second heat treatment may be performed at 600 to 1200°C. have.

According to another aspect, a solid electrolyte including the above-described solid conductor is provided.

According to another aspect, an electrochemical device including the above-described solid conductor is provided.

The electrochemical device is provided with an electrochemical cell including a positive electrode, a negative electrode, and a solid electrolyte containing the above-described solid conductor interposed therebetween.

The solid conductor according to an embodiment can be used as an excellent lithium ion conductor by showing improved ionic conductivity at room temperature. Such a lithium ion conductor can be used as an electrolyte for a positive electrode due to improved lithium stability and high oxidation potential. By using such a lithium ion conductor, it is possible to manufacture an electrochemical device with improved performance.

1A shows X-ray diffraction spectra of solid conductors according to Examples 2-6, 11, and 1-2.
FIG. 1B is an enlarged view of a partial area of FIG. 1A.
1C is an XRD spectrum of LiTa ₂ PO ₈ and hafnium-doped solid conductors.
2A to 2D show, in the solid conductors of Example 4, Example 8, Comparative Example 1, and Comparative Example 4, respectively, before and after introduction of a dopant, the diffusion coefficient (diffusivity) by Li ion diffusion (D (unit : cm ² /S).
3A and 3B are graphs showing mean-square displacements (MSDs) of Li ions before and after introduction of a dopant in the solid conductors of Example 4 and Comparative Example 1, respectively, by diffusion of Li ions.
Figure 4a shows the ionic conductivity of the solid conductors of Examples 1, 2, 5, 6 and Comparative Example 1.
4B is a graph showing the activation energy of the solid conductors of Examples 1, 2, 5, and 6 and Comparative Example 1.
4C shows the impedance characteristics of a solid conductor doped with fluorine and hafnium.
4D shows the conductivity of a solid conductor doped with fluorine and hafnium.
5 shows the results of cyclovoltametry analysis of structures using solid conductors of Example 5 and Comparative Example 1.
6A and 6B show lithium stability evaluation results of lithium symmetric cells containing solid conductors of Example 9 and Comparative Example 1, respectively.
7A is a ³¹ P-NMR spectrum of solid conductors of Examples 1-3, 8 and Comparative Example 1. FIG.
7B is an enlarged view of a partial area of FIG. 7A.
7C shows ³¹ P-NMR spectra of the solid conductor of Example 2 and the solid conductor of Example 5. FIG.
8A shows an impedance spectrum for LiTa ₂ PO ₈ .
Figure 8b is for LiTa ₂ PO ₈ It shows the results of evaluating the activation energy of bulk ion conductivity and total ion conductivity.
8C shows an impedance spectrum of a solid conductor in which tantalum is partially substituted with hafnium.
Figure 8d shows the activation energy of LiTa ₂ PO ₈ and hafnium-doped solid conductor.
9 to 11 are cross-sectional views showing a schematic configuration of an all-solid-state battery according to an embodiment.

Hereinafter, a solid conductor according to exemplary embodiments, a method of manufacturing the same, a solid electrolyte including the solid conductor, and an electrochemical device will be described in more detail.

A solid conductor including a compound represented by the following formula (1), a compound represented by formula (2), or a combination thereof is provided.

<Formula 1>

Li _1+x+yz Ta _2-x M _x P _1-y N _y O _8-z X _z

In Formula 1, M is an element having an oxidation number 4+,

N is an element with oxidation number +4,

X is a halogen atom, pseudohalogen, or a combination thereof,

0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z Except for =2,

<Formula 2>

Li _1+x+yz Ta _2-x M _x P _1-y N _y O ₈ zLiX

In Formula 2, M is an element having oxidation number +4,

N is an element with oxidation number +4,

X is a halogen atom, pseudohalogen, or a combination thereof,

0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z The case of =2 is excluded.

In Formulas 1 and 2, 0≦x<0.6 and 0≦z<1.

In the compound of Formula 1, LiHfTaPO ₇ F (when M is Hf, X is F, x=1, y=O, z=1), LiHf ₂ PO ₆ Cl ₂ M is Hf, X is Cl, x=2 , y=O, z=2, and LiHf ₂ PO ₆ F ₂ (where M is Hf, X is F, x=2, y=O, z=2) is excluded.

In Formulas 1 and 2, M is an element that replaces tantalum having an oxidation number of 4+, and the coordination number of M is 6.

In Formulas 1 and 2, N may have a coordination number of 4, for example.

The compound of Formula 1 has a type in which X in Formula 1 replaces some sites of oxygen, and in the compound of Formula 2, LiX (eg LiCl or LiF) is Li _1+x+y Ta _2-x M _x P _{1 -y} N _y O ₈ has the form of a complex added as an additive.

In the present specification, "a compound represented by Formula 1, a compound represented by Formula 2, or a combination thereof" refers to a compound represented by Formula 1 alone, a compound represented by Formula 2 alone, a compound represented by Formula 1 and a compound represented by Formula 2 A mixture of a compound represented by Formula 1 and a compound represented by Formula 2 are represented.

In the present specification, "pseudohalogen" is a molecule composed of two or more electronegative atoms resembling halogens in a free state, and halide ions and It generates similar anions. Examples of pseudohalogens are cyanide (CN), cyanate (OCN), thiocyanate (SCN), azide (N ₃ ), or combinations thereof.

In Formulas 1 and 2, M is, for example, hafnium (Hf), zirconium (Zr), titanium (Ti), germanium (Ge), tin (Sn), iridium (Ir), rhodium (Rh), manganese ( Mn), osmium (Os), ruthenium (Ru), platinum (Pt), or combinations thereof.

And in Formulas 1 and 2, x is, for example, greater than 0 and less than 0.5, for example greater than 0 and less than 0.5, such as greater than or equal to 0.025, less than 0.1, such as from 0.05 to 0.1.

In Formula 1, N is an element that replaces phosphorus (P) having an oxidation number of 4+, for example, silicon (Si), tin (Sn), titanium (Ti), germanium (Ge), selenium (Se), palladium ( Pd), rhodium (Rh), cobalt (Co), molybdenum (Mo), chromium (Cr), ruthenium (Ru), nickel (Ni), manganese (Mn), vanadium (V), niobium (Nb), or a combination thereof It's water. Here, silicon (Si), tin (Sn), titanium (Ti), germanium (Ge), and niobium (Nb) may have an oxide number of 5+, and selenium (Se) may have an oxide number of 6+. And in Formula 1, y may be 0 or greater than 0 and 0.5 or less, for example 0.1 to 0.5, for example 0.1 to 0.2.

In Formulas 1 and 2, X partially replaces the position of oxygen. For example, chlorine (Cl), bromine (Br), fluorine (F), cyanide (CN), cyanate (OCN) ), thiocyanate (SCN), azide (N ₃ ), or a combination thereof. In Formulas 1 and 2, z is 0 or greater than 0 and 0.9 or less, for example 0.01 to 0.5, for example 0.01 to 0.25, for example 0.05 to 0.15.

In the present specification, "oxidation number" may mean an average oxidation number.

LiTa ₂ PO ₈ has been proposed as a lithium phosphate-based lithium ion conductor. However, such lithium ion conductors do not have satisfactory levels of room temperature ionic conductivity and lithium stability, and thus a compound having improved ionic conductivity and lithium stability is required.

Accordingly, the present inventors introduced an element (M) having an oxidation number of +4 to the tantalum (Ta) octahedral site of LiTa ₂ PO ₈ or have a 4+ oxidation number to the tetrahedral site of phosphorus (P) and the coordination number Provides a solid conductor with improved lithium stability with improved ionic conductivity at room temperature by introducing an element of 4 or an element (M) having an oxidation number of +4 and an element having an oxidation number of 4+ and a coordination number of 4 at the same time. do.

The solid conductor may be a lithium ion conductor.

In addition, a halogen atom such as chlorine or fluorine or a pseudohalogen may be introduced into the oxygen (0) site of the solid conductor. In this way, when a solid conductor into which a halogen atom or pseudohalogen is introduced is used in the manufacture of a solid electrolyte, a passive layer containing fluorine, etc., between the lithium metal electrode and the solid electrolyte containing the solid conductor according to an embodiment As a result, lithium stability of the solid electrolyte is improved, and LiF or LiCl is present in the grain boundary region of the solid electrolyte, thereby increasing the Li ion conductivity at the grain boundary.

The solid conductor according to an embodiment is a lithium ion conductor, and has a monoclinic or monoclinic-like structure having a space group of c2/c as LiTa ₂ PO ₈ system, and has two [MO6] octahedrons (octahedral) and one [PO4] tetrahedral have a structure in which corner sharing is performed.

The solid conductor according to an embodiment has improved bulk ionic conductivity and total ionic conductivity characteristics compared to LiTa ₂ PO ₈ .

The solid conductor may be electrically neutral. To match the electrical neutrality of a solid conductor, Li ⁺ vacancy is Can be introduced. At this time, the introduced vacancy becomes a site in which Li ⁺ is capable of hopping, so that activation energy required for Li migration can be reduced. The compound represented by Formula 1 may be, for example, a compound represented by Formula 3 or 4 below.

<Formula 3>

Li _1+x+yz Ta _2-x Hf _x P _1-y Si _y O _8-z X _z

In Formula 3, X is a halogen atom or a pseudohalogen,

0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z Except for =2,

<Formula 4>

Li _1+x+yz Ta _2-x Zr _x P _1-y Si _y O _8-z X _z

In Formula 4, X is a halogen atom or a pseudohalogen,

0≤x≤2, 0≤y<1,0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z The case of =2 is excluded.

In Chemical Formulas 3 and 4, 0≦x<0.6 and 0≦y<1,0≦z<1.

In Formulas 3 and 4, x is, for example, greater than 0 and less than 0.5, for example greater than 0 and less than 0.5, such as 0.1 or more, less than 0.5, such as 0.1 to 0.2.

y may be 0 or greater than 0 and less than or equal to 0.5, such as 0.1 to 0.5, such as 0.1 to 0.2. And z is greater than 0 and not more than 0.9, for example 0.01 to 0.8, for example 0.01 to 0.7, for example 0.01 to 0.6, for example 0.01 to 0.5, for example 0.01 to 0.2, for example 0.05 to 0.15. to be.

In formulas 3 and 4, z is 0 or greater than 0 and 0.9 or less, for example 0.01 to 0.8, for example 0.01 to 0.7, for example 0.01 to 0.6, for example 0.01 to 0.5, for example 0.01 to 0.2 , For example 0.05 to 0.15.

In Formulas 3 and 4, hafnium or zirconium replaces some positions of tantalum. In addition, [PO4] When the oxidation number in a tetrahedron (tetrahedral) introducing a 4 ⁺ a Si in place of 5 ⁺ P-excess (Excess) Li ⁺ to match the electrical neutral view of the compound is introduced, the amount of movable Li ⁺ By increasing the lithium ion conductivity may increase.

When anion X replaces some sites of oxygen, a passive layer containing F, etc., can be formed to improve lithium stability, and LiF or LiCl is present in the grain boundary region, resulting in grain boundary It is possible to increase the Li ion conductivity in

The compound represented by Formula 2 is, for example, a compound represented by Formula 5 or 6.

<Formula 5>

Li _1+x+yz Ta _2-x Hf _x P _1-y Si _y O ₈ zLiX

In Formula 5, X is a halogen atom,

0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z Except for =2,

<Formula 6>

Li _1+x+yz Ta _2-x Zr _x P _1-y Si _y O ₈ zLiX

In Formula 5, X is a halogen atom,

0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z The case of =2 is excluded.

In Formulas 5 and 6, 0≦x<0.6 and 0≦z<1.

In Chemical Formulas 5 and 6, x is, for example, greater than 0 and less than or equal to 0.5, such as greater than or equal to 0.1 and less than 0.5, for example, 0.1 to 0.2.

y may be 0 or greater than 0 and less than or equal to 0.5, such as 0.1 to 0.5, such as 0.1 to 0.2. And z is greater than 0 and not more than 0.9, for example 0.01 to 0.8, for example 0.01 to 0.7, for example 0.01 to 0.6, for example 0.01 to 0.5, for example 0.01 to 0.2, for example 0.05 to 0.15. to be.

In formulas 5 and 6, z is 0 or greater than 0 and 0.9 or less, for example 0.01 to 0.8, for example 0.01 to 0.7, for example 0.01 to 0.6, for example 0.01 to 0.5, for example 0.01 to 0.2 , For example 0.05 to 0.15.

The solid conductor according to an embodiment may be, for example, a compound represented by Formula 5, a compound represented by Formula 6, or a combination thereof.

The solid conductor according to an embodiment is, for example, Li _0.9 Ta ₂ PO _7.9 F _0.1 , Li _0.9 Ta ₂ PO _7.9 Cl _0.1 , Li _0.85 Ta ₂ PO _7.85 Cl _0.15 , Li _0.85 Ta ₂ PO _7.85 F _0.15 , Li _0.8 Ta ₂ PO _7.85 F _0.2 , Li _0.8 Ta ₂ PO _7.8 Cl _0.2 , Li _1.025 Hf _0.025 Ta _1.975 PO ₈ , Li _1.05 Hf _0.05 Ta _1.95 PO ₈ , Li _1.1 Hf _0.1 Ta _1.9 PO ₈ , Li _1.25 Hf _0.25 Ta _1.75 PO ₈ , Li _1.125 Hf _0.125 Ta _1.875 PO ₈ , Li _1.375 Hf _0.375 Ta _1.625 PO ₈ , Li _1.125 Zr _0.125 Ta _1.875 PO ₈ , Li _1.25 Zr _0.25 Ta _1.75 PO ₈ , Li _1.375 Zr _0.375 Ta _1.625 PO ₈ , Li _1.025 Zr _0.025 Ta _1.975 PO ₈ , Li _1.05 Zr _0.05 Ta _1.95 PO ₈ , Li _1.1 Zr _0.1 Ta _1.9 PO ₈ , Li _0.9 Hf _0.05 Ta _1.95 PO _7.85 F _0.15 , Li _0.9 Hf _0.05 Ta _1.95 PO _7.85 Cl _0.15 , Li _0.8 Hf _0.05 Ta _1.95 PO _7.75 F _0.25, Li _0.8 Hf _0.05 Ta _1.95 PO _7.75 Cl _0.25 , Li _0.875 Hf _0.025 Ta _1.975 PO _7.85 F _0.15 , Li _0.875 Hf _0.025 Ta _1.975 PO _7.85 Cl _0.15 , Li _0.775 Hf _0.025 Ta _1.975 PO _7.75 F _{0.25 ,,} Li _0.775 Hf _0.025 Ta _1.975 PO _7.75 Cl _0.25 , Li _0.95 Hf _0.1 Ta _1.9 PO _7.85 Cl _0.15 , Li _0.85 Hf _0.1 Ta _1.9 PO _7.75 F _0.25 , Li _0.85 Hf _0.1 Ta _1.9 PO _7.75 Cl _0.25 , Li _1.1 Hf _0.25 Ta _1.75 PO _7.85 Cl _0.15 , Li ₁ Hf _0.25 Ta _1.75 PO _7.75 F _0.25 , Li ₁ Hf _0.25 Ta _1.75 PO _7.75 Cl _0.25 , Li _0.975 Hf _0.125 Ta _1.875 PO _7.85 Cl _0.15 , Li _0.875 Hf _0.125 Ta _1.875 PO _7.75 F _0.25 , Li _0.875 Hf _0.125 Ta _1.875 PO _7.75 Cl _0.25 , Li _1.225 Hf _0.375 Ta _1.625 PO _7.85 Cl _0.15 , Li _1.125 Hf _0.375 Ta _1.625 PO _7.75 F _0.25, Li _1.125 Hf _0.375 Ta _1.625 PO _7.75 Cl _0.25 , Li _0.975 Zr _0.125 Ta _1.875 PO _7.85 Cl _0.15 , Li _0.875 Zr _0.125 Ta _1.875 PO _7.75 F _0.25 , Li _0.875 Zr _0.125 Ta _1.875 PO _7.75 Cl _0.25 , Li _1.1 Zr _0.25 Ta _1.75 PO _7.85 Cl _0.15 , Li ₁ Zr _0.25 Ta _1.75 PO _7.75 F _0.25 , Li ₁ Zr _0.25 Ta _1.75 PO _7.75 Cl _0.25 , Li _1.225 Zr _0.375 Ta _1.625 PO _7.85 Cl _0.15 , Li _1.125 Zr _0.375 Ta _1.625 PO _7.75 F _0.25 , Li _1.125 Zr _0.375 Ta _1.625 PO _7.75 Cl _0.25 , Li _0.875 Zr _0.025 Ta _1.975 PO _7.85 Cl _0.15 , Li _0.775 Zr _0.025 Ta _1.975 PO _7.75 F _0.25 , Li _0.775 Zr _0.025 Ta _1.975 PO _7.75 Cl _0.25 , Li _1.05 Zr _0.05 Ta _1.95 PO ₈ , Li _1.05 Zr _0.05 Ta _1.95 PO _7.85 Cl _0.15 , Li _1.05 Zr _0.05 Ta _1.95 PO _7.75 F _0.25 , Li _1.05 Zr _0.05 Ta _1.95 PO _7.75 Cl _0.25 , Li _1.1 Zr _0.1 Ta _1.9 PO ₈ , Li _1.1 Zr _0.1 Ta _1.9 PO _7.85 Cl _0.15 , Li _1.1 Zr _0.1 Ta _1.9 PO _7.75 F _0.25 , Li _1.1 Zr _0.1 Ta _1.9 PO _7.75 Cl _0.25 ; Li _0.975 Ta ₂ PO _7.975 F _0.025 , Li _0.95 Ta ₂ PO _7.95 Cl _0.05 , Li _0.975 Ta ₂ PO _7.975 Cl _0.025 , Li _0.95 Ta ₂ PO _7.95 Cl _0.05 , Li _1.05 Ta _1.975 Hf _0.025 P _0.975 Si _0.025 O ₈ , Li _1.2 Ta _1.9 Hf _0.1 P _0.9 Si _0.1 O ₈ , Li _1.5 Hf _0.5 Ta _1.5 PO ₈ , Li _0.875 Ta ₂ PO _7.875 F _0.125 , Li _0.75 Ta ₂ PO _7.75 F _0.25 , Li _0.625 Ta ₂ PO _7.625 F _0.375 , Li _0.5 Ta ₂ PO _7.5 F _0.5 , Li _0.375 Ta ₂ PO _7.375 F _0.625 , Li _0.25 Ta ₂ PO _7.25 F _0.75 , or a combination thereof.

The solid conductor according to an embodiment improves the isotropy of ionic conductivity.

In general lithium ion conductors, ion conduction occurs very quickly in the z-axis direction compared to the x-axis and y-axis directions (c (z-axis) >> b (y-axis) & a (x-axis)).

However, in the solid conductor according to an embodiment, the ion conduction path and ion conductivity that was fast only in c (z-axis) in general lithium ion conductors are anisotropic at the level of c (z-axis)> b (y-axis)> a (x-axis). This is alleviated, that is, the anisotropy is reduced or alleviated, so that the isotropy of the ion conductivity can be improved.

In the present specification, "isotropy of ion conductivity" means that the diffusion path of lithium ions is reduced in the order of c (z-axis), b (y-axis), and a (x-axis), so that these differences are reduced, so that the anisotropy of ionic conductivity is reduced. Is reduced. That is, it means that the isotropy of ionic conductivity is improved.

The isotropy of the ionic conductivity of the solid conductor according to an embodiment is improved before and after the introduction of the dopant into the solid conductor, the diffusion coefficient (D, unit: cm ² /S) and the mean square displacement MSD ( Mean-square displacements) can be supported from the results of each calculation by means of a Nudged Elastic Band (NEB) calculating method. According to this calculation result, the solid conductor according to an embodiment shows the result that the anisotropy of the diffusion path decreases (the lithium mobility increases in the a and b axis) and the ionic conductivity value increases as a whole. It can be seen that the solid conductor according to an embodiment exhibits isotropic ionic conductivity characteristics.

The solid conductor according to an embodiment has a monoclinic or monoclinic-like structure having a space group of c2/c as described above. According to X-ray diffraction spectroscopy, the solid conductor according to an embodiment has a diffraction angle 2θ of 17.5°±0.5°, 24.8°±0.5°, 24.9°±0.5°, 25.4°±0.5°, and Peaks appear at 27.8°±0.5°, for example 17.5°±0.2°, 24.8°±0.2°, 24.9°±0.2°, 25.4°±0.2°, and/or 27.8°±0.2°.

In Formula 2, a solid conductor containing LiX such as LiCl may exhibit a shifted X-ray diffraction peak characteristic compared to the X-ray diffraction peak of a solid conductor (z=0 in Formula 1) that does not contain LiX such as LiCl. have. From the shift in the X-ray diffraction peak characteristic as described above, it can be seen that X in LiX replaces some sites of oxygen.

From the following ³¹ P-nuclear magnetic resonance (NMR) spectrum, it can be confirmed that an oxide number +4 element such as hafnium was introduced into the crystal structure.

In the ³¹ P-nuclear magnetic resonance (NMR) spectrum of the solid conductor of Formula 1 according to an embodiment, the chemical shift of the main peak appears in the range of -6 to -14 ppm, and the half value of the main peak The width (Full Width at Half-Maximum; FWHM) is 2 to 6 ppm, or 2 to 3 ppm. Here, the main peak means a peak having the largest intensity, and the half width is a numerical value of the peak width at a position of 1/2 of the maximum peak intensity of the main peak.

In the ³¹ P-nuclear magnetic resonance (NMR) spectrum for the solid conductor, the bulk chemical shift appears at -15 to -22 ppm. Bulk refers to a peak having a smaller intensity than the main peak.

A solid conductor according to the embodiment is, for ionic conductivity (ionic conductivity) is 1ⅹ10 ^-2 mS / cm or more, for example, 1.8 × 10 ^-1 S / cm or more, for example at room temperature (25 ℃) 2.8 × 10 ^{- It is 1} S/cm or more, for example, 5.4×10 ^-1 S/cm or more, for example, 6.6×10 ^-1 S/cm or more, or more. Since the solid conductor has such a high ionic conductivity at room temperature, the internal resistance of the electrochemical cell including the solid conductor is further reduced.

The electron conductivity of the solid conductor is 1x10 ^-5 mS/cm or less, for example, 1x10 ^-6 mS/cm or less.

The solid conductor according to an embodiment is very useful as a solid electrolyte because it has high ionic conductivity and low electronic conductivity at room temperature as described above.

When the solid conductor according to an embodiment is used as an electrode additive, the electronic conductivity may have a value higher than 1×10 ^-5 mS/cm compared to the case where the solid electrolyte is used. The electrode may be a high voltage anode. In this way, a battery having a high power density in which a solid conductor is used as an electrode additive can be manufactured.

The solid conductor according to an embodiment is electrochemically stable at 2.0 to 4.6 V for lithium metal, for example.

The activation energy of the solid conductor is less than 0.42 eV/atom, for example less than 0.37 eV/atom, for example 0.29 to 0.35 eV/atom.

The grain size of the solid conductor is in the range of 5 nm to 500 μm. When the solid conductor contains X in Chemical Formula 1, the grain size may be reduced, the grain-grain stability is improved, and the adhesion between grains is improved.

The solid conductor according to an embodiment may exist in a particle state. The average particle diameter of the particles is 5 nm to 500 μm, for example 100 nm to 100 μm, for example 1 μm to 50 μm, and the specific surface area is 0.01 to 1000 m ² /g, for example 0.5 to 100 m ² /g.

A method of manufacturing a solid conductor according to an embodiment will be described as follows.

A precursor mixture is obtained by mixing the precursor for forming a solid conductor according to an embodiment, and heat treatment is performed on the precursor mixture. The solid conductor is a compound represented by Formula 1, a compound represented by Formula 2, or a combination thereof.

<Formula 1>

Li _1+x+yz Ta _2-x M _x P _1-y N _y O _8-z X _z

In Formula 1, M is an element having an oxidation number 4+,

N is an element with oxidation number +4,

X is a halogen atom, pseudohalogen, or a combination thereof,

0≤x≤2, 0≤y<1,0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z Except for =2,

<Formula 2>

Li _1+x+yz Ta _2-x M _x P _1-y N _y O ₈ zLiX

In Formula 2, M is an element having oxidation number +4,

N is an element with oxidation number +4,

X is a halogen atom pseudohalogen or a combination thereof,

0≤x≤2, 0≤y<1,0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z The case of =2 is excluded.

When both x and y in Formulas 1 and 2 are 0, the precursor for forming a solid conductor is a mixture of a lithium precursor, a phosphorus precursor, and a lithium precursor containing X.

When both x and y in Formula 1 and Formula 2 are not 0, the precursor for forming a solid conductor is a lithium precursor, a tantalum precursor, an M precursor, an N precursor, a phosphorus precursor, and/or a lithium precursor containing X. It is a mixture.

In Formulas 1 and 2, when x is 0, the M precursor is not used in the precursor, when y is 0, the N precursor is not used, and when z is 0, the lithium precursor containing X is not used. Does not.

A solvent may be added to the precursor mixture. Any solvent that can dissolve or disperse the lithium precursor, tantalum precursor, M precursor, N precursor, P precursor, and lithium precursor containing X may be used. Examples of the solvent include acetone, ethanol, water, ethylene glycol, isopropanol, or a combination thereof. The content of the solvent is in the range of 50 to 1,000 parts by weight, for example 100 to 300 parts by weight, based on 100 parts by weight of the total weight of the precursor compound.

The mixing may be carried out according to methods known in the art, such as milling, blending and stirring. For milling, for example, a ball mill, air jet mill, bead mill, roll mill, planetary mill, or the like can be used.

During heat treatment for the mixture, the heating rate is 1°C/min to 10°C/min, and the heat treatment temperature (T ₁ ) is in the range of 500°C to 1200°C, for example 600°C to 1000°C. When the heating rate in the heat treatment step is within the above range, the heat treatment may be sufficiently performed.

The heat treatment may be performed in an oxidizing gas atmosphere. An oxidizing gas atmosphere is created using, for example, air or oxygen. And the heat treatment time varies depending on the heat treatment temperature and the like, and ranges from 1 to 20 hours, for example 1 to 10 hours, for example 2 to 8 hours.

The heat treatment may be performed in two stages including a first stage heat treatment and a second stage heat treatment performed at a higher temperature than the first heat treatment. The first heat treatment is performed at 500 to 1000°C, or 600 to 1000°C, and the second heat treatment is performed at 600 to 1200°C or 1100°C. If the heat treatment is carried out in two steps as described above, a high-density solid conductor can be obtained.

A process of milling the heat treatment product may be further performed after performing the first heat treatment and before performing the second heat treatment. Here, the milling may be carried out, for example, planetary milling or hand milling. In this way, further milling may be performed to control the particle size of the heat-treated product. The particle size of the heat-treated product by milling may be controlled to be 1 μm or less, for example. By controlling the particle size in this way, it is possible to obtain a solid conductor with improved density finally obtained.

In the present specification, “particle size” indicates the average particle diameter when the particles are spherical, and when the particles are not spherical, the particle size may indicate the major axis length.

The lithium precursor may be at least one selected from lithium oxide, lithium carbonate, lithium chloride, lithium sulfide, lithium nitrate, lithium phosphate, and lithium hydroxide.

The tantalum precursor is, for example, at least one selected from tantalum hydroxide, tantalum carbonate, tantalum chloride, tantalum sulfate, tantalum nitrate and tantalum oxide.

The phosphorus precursor is, for example, (NH ₄ ) ₂ HPO ₄ , (NH ₄ ) H ₂ PO ₄ , Na ₂ HPO ₄ , Na ₃ PO _4, and the like.

The M precursor is, for example, an M-containing oxide, M-containing carbonate, M-containing chloride, M-containing phosphate, M-containing hydroxide, M-containing nitrate, M-containing hydroxide or a combination thereof, for example, hafnium oxide, hafnium chloride. , Hafnium sulfate, zirconium oxide, zirconium chloride, and zirconium sulfate.

N precursors are, for example, N-containing oxides, N-containing carbonates, N-containing chlorides, N-containing phosphates, N-containing hydroxides, N-containing nitrates or combinations thereof, for example, silicon oxide, tin oxide, tin chloride, etc. have.

Examples of the X-containing precursor include LiCl, LiF, and LiBr.

The content of each precursor described above is stoichiometrically controlled so that a solid conductor containing a compound represented by Formula 1, a compound represented by Formula 2, or a combination thereof can be obtained.

Subsequently, the heat-treated product is pulverized to obtain a molded body. The shaped body is, for example, powder particles. The size of the molded article (powder particles) obtained by grinding is 10 μm or less. When the pulverized particle size is within the above range, the pulverization and mixing can be sufficiently performed because the particle size is small. In the present specification, "size" may mean the average particle diameter when the particles are spherical, and may mean the long axis length when the particles are non-spherical. The size can be measured using a scanning electron microscope or particle size analyzer.

Subsequently, heat treatment is performed on the molded body. During heat treatment, the rate of temperature rise is 1°C/min to 10°C/min. The heat treatment may be performed at 600°C to 1100°C, 600 to 1000°C, or 1000°C to 1100°C. The heat treatment temperature (T ₂ ) for the molded body is performed at a higher temperature than the heat treatment temperature (T ₁ ) before obtaining the molded body.

According to an embodiment, prior to the heat treatment of the molded body, the molded body may be pressed to form a pellet as described above. As described above, when heat treatment is performed in the form of pellets, the diffusion distance of the material to be heat treated is shortened, so that the desired solid conductor can be easily manufactured.

The heat treatment of the molded body can be carried out, for example, in an oxidizing gas atmosphere, a reducing gas atmosphere, or an inert gas atmosphere. The oxidizing gas atmosphere can be made using, for example, air or oxygen, and the reducing gas atmosphere can be made using a reducing gas such as hydrogen and an inert gas atmosphere such as nitrogen, argon, and helium.

The heat treatment time for the molded body varies depending on the heat treatment temperature (T ₂ ) for the molded body, and the like, and ranges from 1 to 50 hours, for example, 6 to 48 hours.

In addition, according to another aspect, an electrochemical device including a solid conductor according to an embodiment is provided. The electrochemical device is, for example, one selected from an electrochemical cell, a storage battery, a supercapacitor, a fuel cell, a sensor, and a color change device.

In accordance with another aspect, there is provided an electrochemical cell containing a solid electrolyte including a positive electrode, a negative electrode, and a solid conductor according to an embodiment interposed therebetween. The electrochemical cell is a positive electrode; A negative electrode containing lithium; And a solid electrolyte disposed between the positive electrode and the negative electrode and containing a solid conductor according to an embodiment.

The electrochemical battery is a lithium secondary battery, a lithium air battery, a solid battery, and the like. In addition, an electrochemical cell can be used for both a primary cell and a secondary cell, and the shape of the electrochemical cell is not particularly limited, and is, for example, a coin type, a button type, a sheet type, a stacked type, a cylinder type, a flat type, and a horn type. The electrochemical cell according to an embodiment can also be applied to medium and large-sized batteries for electric vehicles.

The electrochemical cell may be, for example, an all-solid cell using a precipitation-type negative electrode. The precipitation-type negative electrode refers to a negative electrode in which a negative electrode material such as lithium metal is deposited after charging of an electrochemical cell, although it has a non-anode coating layer without a negative electrode active material when assembling an electrochemical cell.

The solid electrolyte may be an electrolyte protective film, a positive electrode protective film, a negative electrode protective film, or a combination thereof.

The solid electrolyte according to an embodiment may be used as a positive electrode protective film in a battery to which a sulfide-based solid electrolyte is applied, so that a reaction between the sulfide-based solid electrolyte and the positive electrode can be effectively reduced. In addition, the solid electrolyte according to an embodiment may be used as a positive electrode coating material and used as a positive electrode protective film. And the solid electrolyte according to an embodiment has an oxidation stability potential of 3.5 V vs. Li/Li+ or more, e.g. 4.6 to 5.0 V _{vs. It} is high in _Li/Li+ and can be used as a cathode electrolyte, for example, as a cathode electrolyte for all-solid-state batteries.

According to one embodiment, the electrochemical cell may be an all-solid cell.

Referring to Fig. 9, a configuration of an all-solid secondary battery 1 according to the first embodiment will be described. The all-solid-state battery 1 may include a positive electrode 10, a negative electrode 20, and a solid electrolyte 30 containing a solid conductor according to an embodiment, as shown in FIG. 9.

The positive electrode 10 may include a positive electrode current collector 11 and a positive electrode active material layer 12. As the positive electrode current collector 11, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), A plate upper body or a foil upper body made of zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof may be used. The positive electrode current collector 11 may be omitted.

The positive active material layer 12 may include a positive active material and a solid electrolyte. In addition, the solid electrolyte included in the positive electrode 10 may be similar to or different from the solid electrolyte included in the solid electrolyte 30.

The positive electrode active material may be any positive electrode active material capable of reversibly occluding and releasing lithium ions.

For example, the positive electrode active material is lithium cobalt oxide (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobalt oxide, and lithium nickel cobalt aluminum oxide (hereinafter referred to as NCA). , Lithium nickel cobalt manganese oxide (hereinafter referred to as NCM), lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide. It can be formed by using. Each of these positive electrode active materials may be used alone, or two or more types may be used in combination.

In addition, the positive electrode active material is, for example, LiNi _x Co _y Al _z O ₂ (NCA) (however, 0 <x <1, 0 <y <1, 0 <z <1, while x + y + z = 1) or LiNi _x Co _y Mn _z O ₂ (NCM) (however, 0 <x <1, 0 <y <1, 0 <z <1, on the other hand x + y + z = 1) lithium of a ternary transition metal oxide such as Salt is mentioned.

The positive electrode active material may be covered by a coating layer. Here, the coating layer of the present embodiment may be used as long as it is known as a coating layer of the positive electrode active material of an all-solid secondary battery. Examples of the coating layer include, for example, a lithium ion conductor such as Li ₂ O-ZrO ₂ .

In addition, if the positive electrode active material is a compound containing nickel (Ni) such as NCA or NCM, the capacity density of the all-solid secondary battery 1 can be increased. Accordingly, long-term reliability and cycle characteristics in a charged state of the all-solid secondary battery 1 according to the present embodiment can be improved.

Here, as the shape of the positive electrode active material, for example, a particle shape such as an ellipse or a sphere may be mentioned. In addition, the particle diameter of the positive electrode active material is not particularly limited, and may be within a range applicable to the positive electrode active material of a conventional solid secondary battery. In addition, the content of the positive electrode active material of the positive electrode 10 is not particularly limited, and may be within a range applicable to the positive electrode of a conventional solid secondary battery.

In addition, the positive electrode 10 may be appropriately mixed with additives such as a conductive agent, a binder, a filler, a dispersant, and an ion conductive auxiliary agent, as well as the above-described positive electrode active material and solid electrolyte.

Examples of the conductive agent that can be blended in the positive electrode 10 include graphite, carbon black, acetylene black, Ketjen black, carbon fiber, and metal powder. Further, examples of the binder that can be blended into the positive electrode 10 include styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. In addition, as a coating agent, a dispersant, an ion conductive auxiliary agent, etc. that can be blended into the positive electrode 10, a known material generally used for an electrode of a solid secondary battery may be used.

The negative electrode 20 may include a negative electrode current collector 21 and a non-cathode coating layer 22. 9 shows the non-cathode coating layer 22, but may be a general negative electrode active material layer.

The non-cathode coating layer 22 may contain, for example, a metal such as silicon and carbon, and may have a structure in which a conductive binder is disposed around the metal and carbon.

The thickness of the non-cathode coating layer 22 is 1 μm to 20 μm. The negative electrode current collector 21 may be made of a material that does not react with lithium, that is, does not form both an alloy and a compound. As a material constituting the negative electrode current collector 21, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni) are exemplified. The negative electrode current collector 21 may be composed of one type of metal, or may be composed of an alloy or coating material of two or more types of metals. The negative electrode current collector 21 can be formed in a plate shape or a thin shape, for example.

Here, as shown in FIG. 10, a thin film 24 may be formed on the surface of the negative electrode current collector 21. The thin film 24 may include an element capable of forming an alloy with lithium. An element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, and bismuth. The thin film 24 may be composed of one of these metals or may be composed of various types of alloys. By the presence of the thin film 24, the deposition pattern of the metal layer 23 shown in FIG. 11 can be further flattened, and the characteristics of the all-solid secondary battery 1 can be further improved.

Here, the thickness of the thin film 24 is not particularly limited, but may be 1 nm to 500 nm. When the thickness of the thin film 24 is within the above range, the function of the thin film 24 is sufficiently exhibited and the amount of lithium precipitated from the negative electrode is appropriate, so that the characteristics of the all-solid secondary battery 1 are excellent. The thin film 24 may be formed on the negative electrode current collector 21 by, for example, a vacuum evaporation method, a sputtering method, a plating method, or the like.

The non-cathode coating layer 22 may include a negative active material forming an alloy or compound with lithium.

As the negative active material, for example, amorphous carbon, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi) , Tin (Sn), zinc (Zn), and the like. Here, as amorphous carbon, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB) , Graphene, and the like.

The non-cathode coating layer 22 may include only one of these negative active materials or two or more negative active materials. For example, the non-cathode coating layer 22 contains only amorphous carbon as a negative electrode active material, or contains at least one selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, and zinc. You may. In addition, the non-cathode coating layer 22 may include a mixture of amorphous carbon and at least one selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, and zinc. Amorphous carbon and gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin in any one or more mixtures selected from the group consisting of amorphous carbon and gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin and zinc And the mixing weight ratio of any one or more selected from the group consisting of zinc may be, for example, 10: 1 to 1: 2. By constituting the negative active material of such a material, the characteristics of the all-solid secondary battery 1 may be further improved.

Here, when at least one of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, and zinc is used as the negative active material, the particle size (eg, average particle diameter) of the negative active material may be about 4 μm or less. . In this case, the characteristics of the all-solid secondary battery 1 may be further improved. Here, as the particle diameter of the negative electrode active material, for example, a median diameter (so-called D50) measured using a laser particle distribution analyzer can be used. In the following examples and comparative examples, the particle diameter was measured by this method. The lower limit of the particle diameter is not particularly limited, but may be, for example, about 10 nm.

In addition, the negative active material may include a mixture of first particles formed of amorphous carbon and second particles formed of metal or semiconductor. The metal or semiconductor may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, and the like. Here, the content of the second particles is about 8 to 60% by weight, for example, about 10 to 50% by weight based on the total weight of the mixture. In this case, the characteristics of the all-solid secondary battery 1 may be further improved.

The thickness of the non-cathode coating layer 22 is not particularly limited, but may be about 1 μm to 20 μm. When the thickness of the non-cathode coating layer 22 is within the above range, the characteristics of the all-solid secondary battery 1 are sufficiently improved. When the aforementioned binder is used, the thickness of the non-cathode coating layer 22 can be easily secured to an appropriate level.

In the non-cathode coating layer 22, additives used in general solid batteries, for example, fillers, dispersants, ion conductive agents, and the like may be appropriately blended.

As the solid electrolyte 30, a general solid electrolyte is used.

The solid electrolyte may be composed of, for example, a sulfide-based solid electrolyte material. As a sulfide-based solid electrolyte material, for example, Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -LiX (X is a halogen element, for example I, or Cl), 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 SP ₂ S ₅ -Z _m S _n (m, n Is a positive number, Z is one of Ge, Zn or Ga), Li ₂ S-GeS ₂ , Li ₂ S-SiS ₂ -Li ₃ PO ₄ , Li ₂ S-SiS ₂ -Li _p MO _q (p, q Is a positive number, M is one of P, Si, Ge, B, Al, and Ga In), and the like. Here, the sulfide-based solid electrolyte material is produced by treating a starting material (eg, Li ₂ S, P ₂ S _5, etc.) by a melt quenching method or a mechanical milling method. In addition, after such treatment, heat treatment may be performed. The solid electrolyte may be amorphous, crystalline, or a mixture of both.

In addition, the sulfide-based solid electrolyte may be one containing sulfur (S), phosphorus (P), and lithium (Li). For example, a material containing Li ₂ SP ₂ S ₅ can be used. Here, in the case of using a material containing Li ₂ SP ₂ S ₅ as a sulfide-based solid electrolyte material forming the solid electrolyte, the mixing molar ratio of Li ₂ S and P ₂ S ₅ is, for example, Li ₂ S: P ₂ S It may be selected in the range of ₅ = 50:50 to 90:10. In addition, the solid electrolyte 30 may further include a binder. The binder included in the solid electrolyte 30 may include, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, and the like. The binder of the solid electrolyte 30 may be the same as or different from the binders of the positive electrode active material layer 12 and the non-cathode coating layer 22.

It will be described in more detail through the following Examples and Comparative Examples. However, examples are for illustrative purposes only, and the scope of the present invention is not limited thereto.

Example 1

LiOH as a lithium precursor, Ta ₂ O _{5 as a} tantalum precursor, HfO _{2 as a} hafnium precursor, and (NH ₄ ) ₂ HPO ₄ as a phosphorus precursor are mixed in a stoichiometric ratio according to the composition ratio in Table 1, and acetone and zirconia balls are included. The precursor mixture was obtained by grinding and mixing for 2 hours using a planetary mill. The content of acetone is about 100 parts by weight based on 100 parts by weight of the total weight of the precursor mixture, and LiOH was used in an excess of about 10% by weight when preparing the precursor mixture to compensate for the loss of lithium in the subsequent heat treatment process of the precursor mixture.

The precursor mixture was heated to 600° C. at a heating rate of about 5° C./min, and a first heat treatment was performed at this temperature in an air atmosphere for 8 hours.

Planetary milling was performed on the resultant first heat treated according to the above process for 10 minutes.

The resultant product was heated to 1000° C. at a heating rate of about 5° C./min, and secondary heat treatment was performed at this temperature in an air atmosphere for 8 hours to obtain a solid conductor powder having the composition shown in Table 1 below.

Examples 2-4 and 8

A solid conductor powder was prepared in the same manner as in Example 1, except that the content of the hafnium precursor HfO ₂ was controlled at a stoichiometric ratio so as to obtain a solid conductor powder having the composition of Table 1.

Examples 5 and 7

A solid conductor powder having the composition shown in Table 1 was prepared in the same manner as in Example 2, except that lithium fluoride (LiF) was further added when preparing the precursor mixture. In Examples 5 and 7, the content of lithium fluoride was controlled in a stoichiometric ratio according to the composition ratio in Table 1.

Example 6

A solid conductor powder having the composition shown in Table 1 was prepared in the same manner as in Example 2, except that lithium chloride (LiCl) was further added when preparing the precursor mixture. In Example 6, the content of lithium chloride was controlled in a stoichiometric ratio according to the composition ratio in Table 1.

Examples 9, 11, 12

When preparing the precursor mixture, it was carried out in the same manner as in Example 7, except that the content of each precursor was controlled in a stoichiometric ratio to obtain a solid conductor powder having the composition shown in Table 1 below without using a hafnium precursor.

Examples 10, 13-16

When preparing the precursor mixture, it was carried out in the same manner as in Example 6, except that the content of each precursor was controlled in a stoichiometric ratio so as to obtain a solid conductor powder having the composition shown in Table 1 below without using a hafnium precursor.

Example 17-18

Example 1, except that SiO ₂ as a silicon precursor was further used when preparing the precursor mixture, and each precursor was used so that a solid conductor powder having the composition shown in Table 1 was obtained, and the content was controlled in a stoichiometric ratio. It was carried out in the same way as.

Examples 8, 19-29

Each precursor was used to obtain a solid conductor powder having a composition shown in Table 2 below, and the content was controlled in a stoichiometric ratio, and the following process was followed.

As a precursor, LiOH (Sigma Aldrich), Ta ₂ O ₅ (Alfa-Aesar, purity 98% or more), HfO ₂ (Sigma Aldrich) or ZrO ₂ (Sigma Aldrich), (NH ₄ )H ₂ PO ₄ (Sigma Aldrich) and LiF (Alfa-Aesar) was used.

The precursor powder was mixed in a stoichiometric ratio in a 45 ml zirconia container, and then high-energy mechanical milling was performed using SPEX8000 with anhydrous acetone. The ball milled powder was preheated at 600° C. and 1000° C. for 8 hours, and then compressed to obtain pellets having a diameter of 12 mm. The pellet was covered with mother powder to prevent lithium loss, and then heat-treated at 1100° C. for 12 hours.

Comparative Example 1

A solid conductor having the composition of Table 1 was prepared by following the same method as in Example 1, except that HfO ₂ as a hafnium precursor was not used when preparing the precursor mixture.

Comparative Examples 2 and 4

LiOH as a lithium precursor, Ta ₂ O _{5 as a} tantalum precursor, (HfO ₂ ) as a hafnium precursor, and ((NH ₄ ) ₂ HPO _{4 as a} phosphorus precursor) were mixed in a stoichiometric ratio according to the composition ratio in Table 1, and a precursor mixture was prepared. Except for further use of lithium fluoride, a solid conductor having the composition shown in Table 1 was prepared in the same manner as in Example 1. The content of lithium fluoride was controlled in a stoichiometric ratio according to the composition ratio in Table 1.

Comparative Example 3

LiOH as a lithium precursor, HfO _{2 as a} hafnium precursor, and (NH ₄ ) ₂ HPO ₄ as a phosphorus precursor were mixed in a stoichiometric ratio according to the composition ratio in Table 1, except that lithium chloride was further used when preparing the precursor mixture. A solid conductor having the composition shown in Table 1 was manufactured according to the same method as in Example 1. The content of lithium chloride was controlled in a stoichiometric ratio according to the composition ratio in Table 1.

Evaluation Example 1: X-ray diffraction analysis (X-ray diffraction: XRD)

XRD spectra were measured for the solid conductors according to Examples 2-6, 11, and 1-2, and the results are shown in FIGS. 1A and 1B. FIG. 1B is an enlarged view of a partial area in FIG. 1A. Cu Kα radiation (λ=1.5406Å) was used for XRD spectrum measurement. X-ray diffraction analysis was performed using Bruker's D8 Advance.

Referring to FIGS. 1A and 1B, it was found that the solid conductors of Examples 2 to 6 and 11 exhibit the same XRD peak characteristics as the solid conductor of Comparative Example 1 (LiTa ₂ PO ₈ ). From this, it was found that the solid conductors of Examples 2 to 6 and 11 had substantially the same crystal structure compared to the solid conductor of Comparative Example 1.

In addition, as shown in FIG. 1B, in the solid conductor of Comparative Example 1, a peak (peak A) was observed at a diffraction angle of about 25.4°. And in the case of the hafnium-substituted solid conductor (the solid conductor of Example 2-4), the peak A was shifted compared to the solid conductor of Comparative Example 1, and Example 5-6, in which fluorine or chlorine and hafnium were substituted, And the solid conductor of 11 showed the result of shifting the peak A.

In more detail, as shown in FIG. 1B, in the solid conductor of Example 11, the peak A appears at 25.43°, compared to the peak A of the solid conductor of Comparative Example 1 (diffraction angle 2Θ: about 25.4°). Shifted to the right. In addition, in the solid conductor of Example 5, peak A appeared at 25.42° and was shifted to the right by 0.02° compared to the peak A of the solid conductor of Comparative Example 1 (diffraction angle 2Θ: about 25.4°). In addition, in the solid conductor of Example 6, peak A appeared at 25.45°, and compared to the peak A of the solid conductor of Comparative Example 1 (diffraction angle 2Θ: about 25.4°), it was shifted to the right by 0.05°. As described above, the solid conductor substituted with hafnium and fluorine or chlorine showed a result in which peak A was shifted by 0.02 to 0.05° compared to the solid conductor of Comparative Example 1.

In addition, the (221) interplanar distance of the solid conductor of Example 2 was reduced by about 0.007 Å compared to the solid conductor of Comparative Example 1. The (221) interplanar distance of the solid conductor can be determined from the peak at 2theta of 25.4°.

The results of XRD analysis on the solid conductors of Examples 1 to 18 and Comparative Examples 1-2 are shown in Table 3 below.

As shown in Table 3, it was found that the solid conductors of Examples 1 to 16 had substantially the same crystal structure compared to the solid conductors of Comparative Example 1. In addition, the solid conductors of Examples 4, 17, and 18 have a perovskite phase of LiTaO ₃ in addition to LiTa ₂ PO ₈ . In this way, having a parovskite phase can further improve the lithium stability of the solid conductor.

In addition, XRD analysis of the solid conductors of Examples 2, 3, 8, and 1 was performed. The analysis results are as shown in FIG. 1C.

Referring to this, when the amount of hafnium increased by 0.1 or more, impurities were observed in the range of 21 to 25°.

Evaluation Example 2: Measurement of ion conductivity and activation energy

The solid conductor powders of Examples 1 to 18 and Comparative Examples 1 and 2 were pelletized by pressing for 5 minutes at a pressure of 6 tons to make each solid conductor pellet (thickness: about 500 μm). The surface of the solid conductor pellets obtained by the above process was completely covered with mother powder having the same composition as the solid conductor pellets to minimize the change in composition due to lithium volatilized during heat treatment. During the heat treatment was performed. Subsequently, after polishing both sides of the heat-treated pellet with SiC sand paper, sputtering the Au electrode as a blocking electrode on both sides of the pellet using an MTI sputtering coater. By depositing by the Au / solid conductor pellet / Au structure was prepared.

The Au/solid conductor pellet/Au structure was analyzed using electrochemical impedance spectroscopy (EIS). EIS analysis was performed at about 10mV for amplitude and 0.1 Hz for frequency. The total resistance (R _total ) value is calculated from the impedance result, and the electrode area and pellet thickness are corrected from this value to calculate the conductivity value. In addition, during the EIS measurement, an activation energy (Ea) value for Li ion conduction was calculated from the measurement result by changing the temperature of the chamber in which each solid conductor sample was loaded. Ea can be calculated from the slope value by converting the measured conductivity value for each temperature in the range of 298~378K to the Arrhenius plot (Ln (σT) vs. 1/T) of Equation 1 below.

[Equation 1]

σT = A exp(Ea/RT)

In Equation 1, Ea is the activation energy, T is the absolute temperature, A is the pre-exponential factor, σ is the conductivity, and R is the gas constant.

Some of the activation energy analysis results obtained according to the above process are shown in FIGS. 4A and 4B and Table 4 below.

In Table 4, Li ⁺ , bulk represents the lithium ion bulk conductivity, and Li ⁺ , tot represents the total lithium ion conductivity.

As shown in Table 4, it was found that the ionic conductivity of the solid conductors of Examples 1 to 18 was improved at room temperature (25° C.) compared to the cases of Comparative Examples 1 to 3. In addition, the solid conductors of Examples 4 and 15 have slightly lower Li ⁺ ,tot than the case of Comparative Example 1, but the solid electrolytes containing the solid conductors of Examples 4 and 15 have improved lithium stability.

In addition, the solid conductors of Examples 1 to 6 and 8 to 18 exhibited a small value, that is, 0.42 eV/atom compared to the activation energy of the solid conductors of Comparative Examples 1 to 3. When the activation energy of the solid conductor is reduced in this way, the ionic conductivity is improved at low temperatures. In addition, the solid conductors of Examples 8 to 10 exhibited ionic conductivity properties similar to those of the solid conductors of Example 7.

In addition, the conductivity of the solid conductors of Examples 1 to 3, Examples 5 to 8, and Comparative Example 1 was evaluated. The evaluation results are shown in Table 5 below.

Conductivity is measured at 21°C using Ac Electrochemical Impedance Spectroscopy (EIS) in the frequency range of 50 mV, 5 MHz to 1 Hz.

division The composition of solid conductors Bulk conductivity
(Bulk conductivity) mS/cm Total conductivity
(Total conductivity)(mS/cm) density
(%) Comparative Example 1 LiTa ₂ PO ₈ 1.99 0.013 97.3 Example 8 Li _1.125 Hf _0.125 Ta _1.875 PO ₈ 1.09 0.25 92.3 Example 7 Li _0.8 Hf _0.05 Ta _1.95 PO _7.75 F _0.25 - 0.21 - Example 5 Li _0.9 Hf _0.05 Ta _1.95 PO _7.85 F _0.15 - 0.79 - Example 3 Li _1.1 Hf _0.1 Ta _1.9 PO ₈ 1.32 0.30 94.6 Example 2 Li _1.05 Hf _0.05 Ta _1.95 PO ₈ 1.72 0.43 91.4 Example 1 Li _1.025 Hf _0.025 Ta _1.975 PO ₈ 1.54 0.658 92.6

Referring to Table 5, it was found that the total conductivity was improved by hafnium doping. The highest total conductivity is x = 0.025 and the total conductivity value is 0.658mS/cm. Hafnium doping also reduces the activation energy from 0.45 eV (x=0) to 0.29 eV (x=0.05). In addition, impedance characteristics and conductivity characteristics of the solid conductor doped with fluorine and hafnium were evaluated, and the evaluation results are shown in FIGS. 4C and 4D, respectively.

In the solid conductor doped with fluorine, one semicircle was observed as shown in FIG. 4C, and the total conductivity was calculated from this.

Evaluation Example 3: Activation energy and mean-square displacements MSD (calculated value)

In the solid conductors of Example 8, Example 4, Comparative Example 1, and Comparative Example 4, the diffusion coefficient (diffusivity) (D (unit: cm ² /s) by Li ion diffusion before and after the introduction of the dopant was determined) Each calculated by quantum calculation (Nudged Elastic Band (NEB) calculating) is shown in Figs. 2a to 2d.

As shown in FIGS. 2A and 2B, the solid conductors of Examples 4 and 8 exhibited very increased ionic conductivity compared to the solid conductor of Comparative Example 1 of FIG. 2C and the solid conductor of Comparative Example 4 of FIG. 2D, respectively. . From these results, it can be seen that the solid conductors of Examples 4 and 8 have increased isotropy of the ion conduction path, unlike the cases of Comparative Examples 1 and 2.

In addition, in the solid conductors of Example 4 and Comparative Example 1, before and after the introduction of the dopant, the mean-square displacements MSD (mean-square displacements) due to Li ion diffusion were calculated by quantum calculation (Nudged Elastic Band (NEB)). ) Calculated by the method and shown in Figs. 3A and 3B, respectively. In FIGS. 3A to 3C, a represents MSD along the x-axis, b represents MSD along the y-axis, c represents MSD along the z-axis, and overall represents the net value of MSD.

Compared to the case of Comparative Example 1, the anisotropy of the diffusion path of the solid conductor of Example 4 decreased (mobility increased in the a and b axes), resulting in an overall increase in the ionic conductivity value. From these results, it was found that the solid conductor of Example 4 increased the isotropy of the ion conduction path.

3B and 3A show the crystal lattice direction (a [100]), b ([010]), c ([001]) in undoped LiTa ₂ PO ₈ and Hf doped Li _1.25 Hf _0.25 Ta _1.75 PO ₈ The calculated mean-square displacements for Li-ion diffusion along the crystal lattice direction are shown, respectively. With reference to this, it is determined that the Li-ion diffusion is mainly limited along the c-lattice, and the Hf dopant can enhance lithium diffusion along the b-axis.

Evaluation Example 4: Cyclovoltammetry

The solid conductor powders of Example 5 and Comparative Example 1 were pelletized by pressing for 5 minutes at a pressure of 6 tons to prepare respective solid conductor pellets (thickness: about 500 μm). The top of the solid conductor pellet obtained by the above process was completely covered with mother powder having the same composition as the solid conductor pellet to minimize the change in composition due to lithium volatilized during heat treatment, and this was done at about 1100°C for 12 hours. During the heat treatment was performed. Subsequently, both sides of the heat-treated pellet were polished using SiC sand paper, and Au electrodes were deposited on both sides of the pellet by sputtering to prepare an Au/solid conductor pellet/Au structure. The structure was scanned for 3 cycles at a scan rate of 1 mV/s to perform cyclovoltametry analysis. The current density was measured in a voltage range of 2.0 to 4.6V and shown in FIG. 5.

5, it was found that the solid conductor of Example 5 was stable up to 4.6V _Li/Li+ .

Evaluation Example 5: Lithium stability

The solid conductor powders of Example 9 and Comparative Example 1 were pelletized by pressing at a pressure of 6 tons for 5 minutes to prepare respective solid conductor pellets (thickness: about 500 μm). The top of the pellet obtained by the above process was completely covered with mother powder having the same composition as the solid conductor pellet to minimize the composition change due to lithium volatilized during heat treatment, and this resulted in air at about 1100°C for 12 hours. Heat treatment was performed in an atmosphere. Subsequently, after polishing both sides of the heat-treated pellets using SiC sand paper, lithium metal is placed on both sides of the pellet, and cold isostatic press (CIP) is performed on the resultant product. A symmetric cell was prepared.

The state changes after the lithium symmetric cell using the solid conductor of Example 9 and the lithium symmetric cell using the solid conductor of Comparative Example 1 were left for 3 days are shown in FIGS. 6A and 6B. 6A is a lithium symmetric cell using the solid conductor of Example 9, and FIG. 6B is a lithium symmetric cell using the solid conductor of Comparative Example 1.

As shown in FIGS. 6A and 6B, it was found that the degree of discoloration of lithium was reduced in the lithium symmetric cell using the solid conductor of Example 9 compared to the lithium symmetric cell using the solid conductor of Comparative Example 1. From this, it was found that the solid conductor of Example 9 has improved lithium stability compared to the case of Comparative Example 1.

Evaluation Example 6: ³¹ P-Nuclear Magnetic Resonance (NMR) analysis

³¹ P-NMR analysis was performed on the solid conductors obtained according to Examples 1, 2, 3 and 8 and Comparative Example 1. ³¹ P-NMR analysis was performed using a Bruker Avance-III 500 spectrometer at a Larmor frequency of 202.4 MHz. ^{The 31} P NMR spectrum is calibrated to 85% H ₃ PO ₄ at 0 ppm.

³¹ P-NMR analysis results are shown in Figs. 7a, 7b and Table 6.

division Presence of bulk (P2, P3) Example 1 ○ Example 2 ○ Example 3 ○ Example 8 ○ Comparative Example 1 X

In FIG. 7B, P1 denotes a pristine sample PO4 having tantalum in a second coordination shell of phosphorus. And P2 may be caused by hafnium at the second coordination site of phosphorus.

P3 is hafnium phosphate, which is also found in XRD. When the hafnium doping was 0.1 or more, additional impurities were observed at about -30 ppm, and lithium phosphate was observed to be present at about 10 ppm.

Referring to this, when Ta was doped with hafnium, bulk P2 and P3 were observed in a chemical shift of -15 to -22 ppm in ³¹ P-NMR.

As described above, as the content of hafnium doped to tantalum in the solid conductor increased, the half width of the main peak increased. From this, it was confirmed from the above-described XRD analysis results that hafnium was doped into the crystal structure from the ³¹ P-NMR results while maintaining the crystal structure of the solid conductor. In addition, the solid conductors of Examples 1 to 8 were observed to be bulky (P2 and P3) unlike the solid conductor of Comparative Example 1.

In addition, ³¹ P-NMR analysis was performed on the solid conductor of Example 2 and the solid conductor of Example 5, and the analysis results are shown in FIG. 7C. The half width of the P1 peak from FIG. 7C is shown in Table 7 below.

The Li ₃ PO ₄ phase was removed by fluorine doping. In the second coordination environment of phosphorus (P), it was observed that P2 related to hafnium exhibited a broader peak shape in the fluorine-doped sample.

division Half width of main peak (P1) (ppm) Example 2 4 Example 5 3

Evaluation Example 7: Phase stability

The energy above hull for the solid conductor shown in Table 8 below is determined. The Hull energy was calculated through a phase diagram analysis. The evaluation results are shown in Table 8 below. Hull energy is a measure of the phase stability of a certain composition expressed by a given chemical formula.

division Dopant
(Dopant) Furtherance Hull energy
(Energy above hull)(meV/atom) Possible impurity phases during synthesis Comparative Example 1 without dopant LiTa ₂ PO ₈ 19.5 Ta ₉ PO ₂₅ Li ₃ PO ₄ TaPO ₅ Example 8 Hf dopant Li _1.125 Hf _0.125 Ta _1.875 PO ₈ 22.7 Ta ₉ PO ₂₅ TaPO ₅ Li ₃ PO ₄ HfO ₂ Example 4 Li _1.25 Hf _0.25 Ta _1.75 PO ₈ 27.0 Ta ₉ PO ₂₅ TaPO ₅ Li ₃ PO ₄ HfO ₂ Example 19 Li _1.375 Hf _0.375 Ta _1.625 PO ₈ 31.7 Ta ₉ PO ₂₅ TaPO ₅ Li ₃ PO ₄ HfO ₂ Example 20 Li _1.5 Hf _0.5 Ta _1.5 PO ₈ 38.6 Ta ₉ PO ₂₅ TaPO ₅ Li ₃ PO ₄ HfO ₂ Example 21 Zr dopant Li _1.125 Zr _0.125 Ta _1.875 PO ₈ 24.5 Ta ₉ PO ₂₅ TaPO ₅ LiZr ₂ (PO ₄ ) ₃ Li ₃ PO ₄ Example 22 Li _1.25 Zr _0.25 Ta _1.75 PO ₈ 30.6 Ta ₉ PO ₂₅ TaPO ₅ LiZr ₂ (PO ₄ ) ₃ Li ₃ PO ₄ Example 23 Li _1.375 Zr _0.375 Ta _1.625 PO ₈ 36.7 Ta ₉ PO ₂₅
LiZr ₂ (PO ₄ ) ₃ Li ₃ PO ₄ ZrO ₂ Example 24 F dopant Li _0.875 Ta ₂ PO _7.875 F _0.125 19.5 Ta ₉ PO ₂₅ TaPO ₅ Li ₃ PO ₄ LiF Example 25 Li _0.75 Ta ₂ PO _7.75 F _0.25 21.5 Ta ₉ PO ₂₅ TaPO ₅ Li ₃ PO ₄ LiF Example 26 Li _0.625 Ta ₂ PO _7.625 F _0.375 22.1 Ta ₉ PO ₂₅ TaPO ₅ Li ₃ PO ₄ LiF Example 27 Li _0.5 Ta ₂ PO _7.5 F _0.5 22.0 Ta ₉ PO ₂₅ TaPO ₅ LiF Example 28 Li _0.375 Ta ₂ PO _7.375 F _0.625 18.5 Ta ₉ PO ₂₅ TaPO ₅ Li ₂ Ta ₂ O ₃ F ₆ LiF Example 29 Li _0.25 Ta ₂ PO _7.25 F _0.75 17.8 Ta ₉ PO ₂₅ TaPO ₅ Li ₂ Ta ₂ O ₃ F ₆ Comparative Example 2 Hf, F co-doped LiHfTaPO ₇ F 43.8 TaPO ₅ LiF HfO ₂ Comparative Example 4 LiHf ₂ PO ₆ F ₂ 44.7 Hf ₂ P ₂ O ₉ HfF ₄ LiF HfO ₂

Evaluation Example 8: Impedance and activation energy of bulk and total ionic conductivity

Ionic conductivity is measured at 21° C. using Ac electrochemical impedance spectroscopy (EIS) in the frequency range of 50 mV, 5 MHz to 1 Hz. The activation energy is determined using a variable temperature impedance measurement from room temperature to 120 oC in the CSZ microclimate chamber. The synthesized pellets are sputtered with gold as a blocking electrode (MTI sputtering coater) and sealed with a home-built cylindrical cell for all measurements.

1)LiTa ₂ PO ₈

The impedance spectrum is shown in FIG. 8A, and the results of evaluating the activation energy of the bulk and total ion conductivity are shown in FIG. 8B.

Referring to FIG. 8A, the region of 3 MHz reflects the bulk impedance and the region of 158 MHz reflects the grain boundary. Also, as shown in FIG. 8B, since the bulk impedance is clearly not seen at a temperature greater than 60°C, only the total impedance is considered.

2) Solid conductor partially substituted with hafnium for tantalum

Fig. 8c shows the impedance spectrum of a solid conductor in which tantalum is partially substituted with hafnium. Referring to FIG. 8C, the bulk and grain boundary conductivity of the solid conductor can be seen.

The activation energy of the solid conductor LiTa ₂ PO ₈ and the hafnium-doped LiTa ₂ PO ₈ is shown in FIG. 8D. The hafnium-doped solid conductor showed a reduced activation energy compared to LiTa ₂ PO ₈ .

In the above, one embodiment has been described with reference to the drawings and embodiments, but this is only illustrative, and those of ordinary skill in the art can understand that various modifications and other equivalent embodiments are possible therefrom. will be. Therefore, the scope of protection of the present application should be determined by the appended claims.

1, 1a: all-solid secondary battery 10: positive electrode
11: positive current collector 12: positive active material layer
20: negative electrode 21: negative electrode current collector
22: non-cathode coating layer 23: metal layer
30: solid electrolyte

Claims (26)

A solid conductor comprising a compound represented by the following Formula 1, a compound represented by Formula 2, or a combination thereof:
<Formula 1>
Li _1+x+yz Ta _2-x M _x P _1-y N _y O _8-z X _z
In Formula 1, M is an element having an oxidation number 4+,
N is an element with oxidation number +4,
X is a halogen atom, pseudohalogen, or a combination thereof,
0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z Except for =2,
<Formula 2>
Li _1+x+yz Ta _2-x M _x P _1-y N _y O ₈ zLiX
In Formula 2, M is an element having oxidation number +4,
N is an element with oxidation number +4,
X is a halogen atom, pseudohalogen, or a combination thereof,
0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z The case of =2 is excluded. The method of claim 1,
The M is a solid conductor having a coordination number of 6. The method of claim 1,
In Formulas 1 and 2, M is hafnium (Hf), zirconium (Zr), titanium (Ti),
Solid conductors of germanium (Ge), tin (Sn), iridium (Ir), rhodium (Rh), manganese (Mn), osmium (Os), ruthenium (Ru), platinum (Pt), or a combination thereof. The method of claim 1,
In Formulas 1 and 2, N has a coordination number of 4,
The N is silicon (Si), tin (Sn), titanium (Ti), germanium (Ge), selenium (Se), palladium (Pd), rhodium (Rh), cobalt (Co), molybdenum (Mo), chromium ( Solid conductors of Cr), ruthenium (Ru), nickel (Ni), manganese (Mn), vanadium (V), niobium (Nb), or combinations thereof. The method of claim 1,
In Formulas 1 and 2, X is chlorine (Cl), bromine (Br), fluorine (F), cyanide, cyanate, thiocyanate, azide, or Solid conductor as a combination. The method of claim 1,
In Chemical Formulas 1 and 2, 0≦x<0.6, 0≦z<1. The method of claim 1,
In Formulas 1 and 2, x is greater than 0 and less than 0.5, y is 0 or greater than 0 and less than 0.5, and z is 0 or greater than or equal to 0 and less than or equal to 0.3. The method of claim 1,
The solid conductor is a solid conductor having a monoclinic or monoclinic-like structure having a space group of c2/c. The method of claim 1,
The diffraction angle 2θ determined in the X-ray diffraction analysis for the solid conductor is 17.5°±0.5°, 24.8°±0.5°, 24.9°±0.5°, 25.4°±0.5°, and 27.8°±0.5°. Solid conductor. The method of claim 1,
In the ³¹ P-nuclear magnetic resonance (NMR) spectrum for the solid conductor, a chemical shift of the main peak appears in the range of -6 to -14 ppm, and the full width at half-width of the main peak. A solid conductor with a maximum; FWHM) of 2 to 6 ppm. The method of claim 1,
In the ³¹ P-nuclear magnetic resonance (NMR) spectrum of the solid conductor, a bulk bulk chemical shift appears at -15 to -22 ppm. The method of claim 1,
The solid conductor has a lithium ion conductivity of 1×10 ^-2 mS/cm or more at room temperature (25° C.) of the solid conductor. The method of claim 1,
The solid conductor has an electron conductivity of 1×10 ^-5 mS/cm or less. The method of claim 1,
The compound represented by Formula 1 is a solid conductor that is a compound represented by Formula 3 or a compound represented by Formula 4:
<Formula 3>
Li _1+x+yz Ta _2-x Hf _x P _1-y Si _y O _8-z X _z
In Formula 3, X is a halogen atom or pseudohalogen,
0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z Except for =2,
<Formula 4>
Li _1+x+yz Ta _2-x Zr _x P _1-y Si _y O _8-z X _z
In Formula 4, X is a halogen atom or pseudohalogen,
0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z The case of =2 is excluded. The method of claim 1,
The compound represented by Formula 2 is a solid conductor which is a compound represented by Formula 5 or a compound represented by Formula 6:
<Formula 5>
Li _1+x+yz Ta _2-x Hf _x P _1-y Si _y O ₈ zLiX
In Formula 5, X is a halogen atom,
0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z Except for =2,
<Formula 6>
Li _1+x+yz Ta _2-x Zr _x P _1-y Si _y O ₈ zLiX
In Formula 5, X is a halogen atom,
0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z The case of =2 is excluded. The method of claim 1,
The solid conductor is Li _0.9 Ta ₂ PO _7.9 F _0.1 , Li _0.9 Ta ₂ PO _7.9 Cl _0.1 , Li _0.85 Ta ₂ PO _7.85 Cl _0.15 , Li _0.85 Ta ₂ PO _7.85 F _0.15 , Li _0.8 Ta ₂ PO _7.85 F _0.2 , Li _0.8 Ta ₂ PO _7.8 Cl _0.2 , Li _1.025 Hf _0.025 Ta _1.975 PO ₈ , Li _1.05 Hf _0.05 Ta _1.95 PO ₈ , Li _1.1 Hf _0.1 Ta _1.9 PO ₈ , Li _1.25 Hf _0.25 Ta _1.75 PO ₈ , Li _1.125 Hf _0.125 Ta _1.875 PO ₈ , Li _1.375 Hf _0.375 Ta _1.625 PO ₈ , Li _1.125 Zr _0.125 Ta _1.875 PO ₈ , Li _1.25 Zr _0.25 Ta _1.75 PO ₈ , Li _1.375 Zr _0.375 Ta _1.625 PO ₈ , Li _1.025 Zr _0.025 Ta _1.975 PO ₈ , Li _1.05 Zr _0.05 Ta _1.95 PO ₈ , Li _1.1 Zr _0.1 Ta _1.9 PO ₈ , Li _0.9 Hf _0.05 Ta _1.95 PO _7.85 F _0.15 , Li _0.9 Hf _0.05 Ta _1.95 PO _7.85 Cl _0.15 , Li _0.8 Hf _0.05 Ta _1.95 PO _7.75 F _0.25, Li _0.8 Hf _0.05 Ta _1.95 PO _7.75 Cl _0.25 , Li _0.875 Hf _0.025 Ta _1.975 PO _7.85 F _0.15 , Li _0.875 Hf _0.025 Ta _1.975 PO _7.85 Cl _0.15 , Li _0.775 Hf _0.025 Ta _1.975 PO _7.75 F _{0.25 ,,} Li _0.775 Hf _0.025 Ta _1.975 PO _7.75 Cl _0.25 , Li _0.95 Hf _0.1 Ta _1.9 PO _7.85 Cl _0.15 , Li _0.85 Hf _0.1 Ta _1.9 PO _7.75 F _0.25 , Li _0.85 Hf _0.1 Ta _1.9 PO _7.75 Cl _0.25 , Li _1.1 Hf _0.25 Ta _1.75 PO _7.85 Cl _0.15 , Li ₁ Hf _0.25 Ta _1.75 PO _7.75 F _0.25 , Li ₁ Hf _0.25 Ta _1.75 PO _7.75 Cl _0.25 , Li _0.975 Hf _0.125 Ta _1.875 PO _7.85 Cl _0.15 , Li _0.875 Hf _0.125 Ta _1.875 PO _7.75 F _0.25 , Li _0.875 Hf _0.125 Ta _1.875 PO _7.75 Cl _0.25 , Li _1.225 Hf _0.375 Ta _1.625 PO _7.85 Cl _0.15 , Li _1.125 Hf _0.375 Ta _1.625 PO _7.75 F _0.25, Li _1.125 Hf _0.375 Ta _1.625 PO _7.75 Cl _0.25 , Li _0.975 Zr _0.125 Ta _1.875 PO _7.85 Cl _0.15 , Li _0.875 Zr _0.125 Ta _1.875 PO _7.75 F _0.25 , Li _0.875 Zr _0.125 Ta _1.875 PO _7.75 Cl _0.25 , Li _1.1 Zr _0.25 Ta _1.75 PO _7.85 Cl _0.15 , Li ₁ Zr _0.25 Ta _1.75 PO _7.75 F _0.25 , Li ₁ Zr _0.25 Ta _1.75 PO _7.75 Cl _0.25 , Li _1.225 Zr _0.375 Ta _1.625 PO _7.85 Cl _0.15 , Li _1.125 Zr _0.375 Ta _1.625 PO _7.75 F _0.25 , Li _1.125 Zr _0.375 Ta _1.625 PO _7.75 Cl _0.25 , Li _0.875 Zr _0.025 Ta _1.975 PO _7.85 Cl _0.15 , Li _0.775 Zr _0.025 Ta _1.975 PO _7.75 F _0.25 , Li _0.775 Zr _0.025 Ta _1.975 PO _7.75 Cl _0.25 , Li _1.05 Zr _0.05 Ta _1.95 PO ₈ , Li _1.05 Zr _0.05 Ta _1.95 PO _7.85 Cl _0.15 , Li _1.05 Zr _0.05 Ta _1.95 PO _7.75 F _0.25 , Li _1.05 Zr _0.05 Ta _1.95 PO _7.75 Cl _0.25 , Li _1.1 Zr _0.1 Ta _1.9 PO ₈ , Li _1.1 Zr _0.1 Ta _1.9 PO _7.85 Cl _0.15 , Li _1.1 Zr _0.1 Ta _1.9 PO _7.75 F _0.25 , Li _1.1 Zr _0.1 Ta _1.9 PO _7.75 Cl _0.25 ; Li _0.975 Ta ₂ PO _7.975 F _0.025 , Li _0.95 Ta ₂ PO _7.95 Cl _0.05 , Li _0.975 Ta ₂ PO _7.975 Cl _0.025 , Li _0.95 Ta ₂ PO _7.95 Cl _0.05 , Li _1.05 Ta _1.975 Hf _0.025 P _0.975 Si _0.025 O ₈ , Li _1.2 Ta _1.9 Hf _0.1 P _0.9 Si _0.1 O ₈ , Li _1.5 Hf _0.5 Ta _1.5 PO ₈ , Li _0.875 Ta ₂ PO _7.875 F _0.125 , Li _0.75 Ta ₂ PO _7.75 F _0.25 , Li _0.625 Ta ₂ PO _7.625 F _0.375 , Li _0.5 Solid conductors of Ta ₂ PO _7.5 F _0.5 , Li _0.375 Ta ₂ PO _7.375 F _0.625 , Li _0.25 Ta ₂ PO _7.25 F _0.75 , or a combination thereof. The method of claim 1,
The solid conductor has an isotropic ionic conductivity and an activation energy of the solid conductor is less than 0.42 eV/atom. Mixing a precursor for forming a solid conductor to obtain a precursor mixture; And
A method for producing a solid conductor to obtain a solid conductor represented by Formula 1, a solid conductor represented by Formula 2, or a combination thereof, including the step of heat-treating the precursor mixture in an oxidizing gas atmosphere.
<Formula 1>
Li _1+x+yz Ta _2-x M _x P _1-y N _y O _8-z X _z
In Formula 1, M is an element having an oxidation number 4+,
N is an element with oxidation number +4,
X is a halogen atom, pseudohalogen, or a combination thereof,
0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z Except for =2,
<Formula 2>
Li _1+x+yz Ta _2-x M _x P _1-y N _y O ₈ zLiX
In Formula 2, M is an element having oxidation number +4,
N is an element with oxidation number +4,
X is a halogen atom or pseudohalogen,
0≤x≤2, 0≤y<1, 0≤z≤2, provided that if i)x and y and z are 0 at the same time, ii)M is Hf, X is F, x=1, y=O , if z=1, iii) M is Hf, X is Cl, x=2, y=O, z=2 and iv) M is Hf, X is F, x=2, y=O, z The case of =2 is excluded. The method of claim 18,
The method of manufacturing a solid conductor in which the heat treatment is performed at 500 to 1200°C. The method of claim 18,
The heat treatment includes a first heat treatment and a second heat treatment performed at a temperature higher than the first heat treatment,
The first heat treatment is carried out at 500 to 1000°C,
The second heat treatment is a method of manufacturing a solid conductor carried out at 600 to 1200 ℃. The method of claim 18,
A method for producing a solid conductor in which a lithium precursor containing X is further added when preparing a precursor mixture.
The lithium precursor containing X is a method for producing a solid conductor further comprising at least one selected from lithium chloride and lithium fluoride. A solid electrolyte comprising the solid conductor of any one of claims 1 to 17. An electrochemical device comprising the solid conductor of any one of claims 1 to 17. The method of claim 23,
The electrochemical device comprises a positive electrode, a negative electrode, and a solid electrolyte interposed therebetween.
An electrochemical device that is an electrochemical cell containing. The method of claim 24,
An electrochemical device in which the solid electrolyte is an electrolyte protective film, a positive electrode protective film, a negative electrode protective film, or a combination thereof. The method of claim 23,
An electrochemical device in which the electrochemical device is an all-solid battery.

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