KR20220072176A - Halogen element introduced glassy sulfide solid electrolyte for lithium secondary battery - Google Patents

Abstract

The present invention relates to a sulfide-based solid electrolyte for a lithium secondary battery in a glassy state having a new composition by introducing a halogen element. Specifically, the sulfide-based solid electrolyte may be represented by the following formula (1).
[Formula 1]
{[Li ₂ S] _x [(LiX1) _1-a (LiX2) _a ] _1-x } _1-y {P ₂ S ₅ } _y
Formula 1 satisfies 0.55≤x≤0.80, 0≤a≤0.5, 0.10≤y≤0.21, and X1 and X2 are different halogen elements and are F, Cl, Br, or I, respectively.

Description

HALOGEN ELEMENT INTRODUCED GLASSY SULFIDE SOLID ELECTROLYTE FOR LITHIUM SECONDARY BATTERY

The present invention relates to a sulfide-based solid electrolyte for a lithium secondary battery in a glassy state having a new composition by introducing a halogen element.

Liquid electrolyte-based lithium secondary batteries are widely used because they are easy to make and light, but there is a risk of explosion when exposed to shocks or high temperatures.

All-solid-state batteries, in which all components, including solid electrolytes, are made of solids, have superior durability and stability compared to lithium secondary batteries based on liquid electrolytes. In addition, since direct stacking is possible, it is easy to implement a high voltage cell and is advantageous for high energy density. Accordingly, many attempts are currently being made to utilize all-solid-state batteries as medium to large-sized batteries for electric vehicles or energy storage systems (ESS).

The solid electrolyte can be largely divided into a glassy solid electrolyte and a crystalline solid electrolyte. Glassy solid electrolytes have a low modulus of elasticity, making them suitable for use in batteries, but their lithium ion conductivity is rather low. On the other hand, the crystalline solid electrolyte has excellent lithium ion conductivity but high elastic modulus.

Currently, materials that complement mechanical properties and lithium ion conductivity are being developed in glassy solid electrolytes and crystalline solid electrolytes, respectively.

An object of the present invention is to provide a glassy solid electrolyte having excellent lithium ion conductivity.

Specifically, an object of the present invention is to provide a sulfide-based solid electrolyte having a novel composition having high lithium ion conductivity while maintaining the low elastic modulus of the glassy solid electrolyte.

The object of the present invention is not limited to the object mentioned above. The objects of the present invention will become more apparent from the following description and will be realized by means of the means and combinations thereof recited in the claims.

The sulfide glassy solid electrolyte for a lithium secondary battery according to an embodiment of the present invention is represented by the following Chemical Formula 1, and may be in a glassy state.

[Formula 1]

{[Li ₂ S] _x [(LiX1) _1-a (LiX2) _a ] _1-x } _1-y {P ₂ S ₅ } _y

Formula 1 satisfies 0.55≤x≤0.80, 0<a≤0.5, 0.10≤y≤0.21, and X1 and X2 are different halogen elements and may be F, Cl, Br, or I, respectively.

In the sulfide glassy solid electrolyte, in Formula 1, x may satisfy 0.65≤x≤0.80.

In the sulfide glassy solid electrolyte, x and y in Formula 1 may satisfy Formula 1 below.

[Equation 1]

The sulfide glassy solid electrolyte may have a degree of crystallization measured by X-ray diffraction (XRD) of less than 5%.

The sulfide glassy solid electrolyte may have a peak at a chemical shift of -9.20 ppm to -8.72 ppm in a ⁷ Li-NMR spectrum.

The sulfide glassy solid electrolyte may have a full width at half maximum (FWHM) of less than 0.7 ppm of a peak found at -10 ppm to -8 ppm in the ⁷ Li-NMR spectrum.

A method for preparing a sulfide glassy solid electrolyte for a lithium secondary battery according to an embodiment of the present invention comprises the steps of preparing a starting material including lithium sulfide, diphosphorus pentasulfide and lithium halide according to a composition according to the following Chemical Formula 1; and pulverizing the starting material.

The sulfide-based solid electrolyte according to the present invention is a glass-based solid electrolyte, which has a low modulus of elasticity and at the same time has excellent lithium ion conductivity, so it can be usefully used in an all-solid-state battery.

The effects of the present invention are not limited to the above-mentioned effects. It should be understood that the effects of the present invention include all effects that can be inferred from the following description.

1 is a reference diagram for explaining a method of obtaining the full width at half maximum in the present invention.
2 is an X-ray diffraction analysis result of sulfide-based solid electrolytes according to Examples 1, 2, Comparative Examples 1 and 2 of the present invention.
3 is a ⁷ Li-NMR spectrum result of the sulfide-based solid electrolytes according to Examples 1, 2, Comparative Examples 1 and 2 of the present invention.
4 is an ionic conductivity contour map result through the molar ratio of three raw materials (Li ₂ S, P ₂ S ₅ , LiI) according to Examples and Comparative Examples of the present invention.

The above objects, other objects, features and advantages of the present invention will be easily understood through the following preferred embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art.

In describing each figure, like reference numerals have been used for like elements. In the accompanying drawings, the dimensions of the structures are enlarged than the actual size for clarity of the present invention. Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present specification, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It is to be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof. Also, when a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the case where it is "on" another part, but also the case where there is another part in between. Conversely, when a part of a layer, film, region, plate, etc. is said to be “under” another part, this includes not only cases where it is “directly under” another part, but also a case where another part is in the middle.

Unless otherwise specified, all numbers, values, and/or expressions expressing quantities of ingredients, reaction conditions, polymer compositions and formulations used herein, contain all numbers, values and/or expressions in which such numbers essentially occur in obtaining such values, among others. Since they are approximations reflecting various uncertainties in the measurement, it should be understood as being modified by the term "about" in all cases. Also, where the present disclosure discloses numerical ranges, such ranges are continuous and inclusive of all values from the minimum to the maximum inclusive of the range, unless otherwise indicated. Furthermore, when such ranges refer to integers, all integers inclusive from the minimum to the maximum inclusive are included, unless otherwise indicated.

The sulfide-based solid electrolyte for a lithium secondary battery in a glassy state according to the present invention may be represented by the following formula (1).

[Formula 1]

{[Li ₂ S] _x [(LiX1) _1-a (LiX2) _a ] _1-x } _1-y {P ₂ S ₅ } _y

In Formula 1, 0.55≤x≤0.80, 0<a≤0.5, 0.10≤y≤0.21 may be satisfied.

In addition, in Formula 1, X1 and X2 are different halogen elements, and may be F, Cl, Br, or I, respectively.

x≤0.80를 만족할 수 있다. 또한, 상기 화학식1에서 x 및 y는 하기 식 1을 만족하는 것일 수 있다.Specifically, in Formula 1, x is 0.65

x≤0.80 may be satisfied. In addition, in Formula 1, x and y may satisfy Formula 1 below.

[Equation 1]

When the sulfide-based solid electrolyte satisfies the ranges of x, a, and y and Equation 1, high lithium ion conductivity may be exhibited.

The sulfide-based solid electrolyte is in a glassy state, and the degree of crystallization (DOC) measured by X-ray diffraction (XRD) is less than 5%, or less than 3%, or less than 1%. can The crystallinity measured by X-ray diffraction can be calculated by integrating the graph of the data obtained after XRD measurement to obtain the area of the crystalline area (Crystalline Area) and the area of the amorphous area (Amorphous Area), and then using the following Equation 2 .

[Equation 2]

The sulfide-based solid electrolyte according to the present invention can be specified by a parameter of the peak of the ⁷ Li-NMR spectrum.

The sulfide-based solid electrolyte may have a peak in a chemical shift of -9.20 ppm to -8.72 ppm, specifically -9.20 ppm to -9.00 ppm in the ⁷ Li-NMR spectrum.

In addition, the full width at half maximum of the sulfide-based solid electrolyte is found at -8ppm to -10ppm, specifically -9.20ppm to -8.72ppm, and more specifically -9.20ppm to -9.00ppm in the ⁷ Li-NMR spectrum. (Full width at half maximum, FWHM) may be less than 0.7ppm. The full width at half maximum (FWHM) means the width of the peak at half (H/2) of the height (H) of the peak with respect to the baseline (A) of the peak as shown in FIG. 1 .

When the ⁷ Li-NMR spectrum of the sulfide-based solid electrolyte satisfies the above parameters, it exhibits high lithium ion conductivity.

Hereinafter, the present invention will be described in more detail through specific examples and experimental examples. However, these Examples and Experimental Examples are intended to illustrate the present invention, and the scope of the present invention is not limited thereto.

Example 1 - {[ Li ₂ S ] _0.658 [( LiI )] _0.342 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; a=0.000; x=0.658; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), and lithium iodide (LiI) in a molar ratio of 0.543:0.175:0.282, respectively, was prepared.

The mixture was charged into a gas-tight milling vessel, and beads made of zirconium oxide having a diameter of 5 mm were put together. At this time, the input amount of the beads was about 30 times the weight of the raw material. As described above, the mixture was pulverized by a planetary ball mill method generating a high inertia force. Specifically, the vessel was rotated so that a force of about 37 G was applied to the mixture, and the duration was 12 hours.

After the pulverization was completed, the powdery sulfide-based solid electrolyte was recovered through appropriate sieving and mortar grinding.

Example 2 - {[ Li ₂ S ] _0.658 [( LiI ) _0.900 ( LiBr ) _0.100 ] _0.342 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.100; x=0.658; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI) and lithium bromide (LiBr) in a molar ratio of 0.543:0.175:0.254:0.028, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 3 - {[ Li ₂ S ] _0.600 [( LiI )] _0.400 } _0.870 { P ₂ S ₅ } _0.130 Synthesis (X1=I; a=0.000; x=0.600; y=0.130)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), and lithium iodide (LiI) in a molar ratio of 0.522:0.130:0.348, respectively, was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 4 - {[ Li ₂ S ] _0.650 [( LiI )] _0.350 } _0.870 { P ₂ S ₅ } _0.130 Synthesis (X1=I; a=0.000; x=0.650; y=0.130)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ) and lithium iodide (LiI) in a molar ratio of 0.566:0.130:0.305, respectively, was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 5 - {[ Li ₂ S ] _0.700 [( LiI )] _0.300 } _0.850 { P ₂ S ₅ } _0.150 Synthesis (X1=I; a=0.000; x=0.700; y=0.150)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), and lithium iodide (LiI) in a molar ratio of 0.595: 0.150: 0.255, respectively, was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 6 - {[ Li ₂ S ] _0.620 [( LiI )] _0.380 } _0.850 { P ₂ S ₅ } _0.150 Synthesis (X1=I; a=0.000; x=0.620; y=0.150)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ) and lithium iodide (LiI) in a molar ratio of 0.527:0.150:0.323, respectively, was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 7 - {[ Li ₂ S ] _0.730 [( LiI )] _0.270 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; a=0.000; x=0.730; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), and lithium iodide (LiI) in a molar ratio of 0.602:0.175:0.223, respectively, was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 8 - {[ Li ₂ S ] _0.700 [( LiI )] _0.300 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; a=0.000; x=0.700; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), and lithium iodide (LiI) in a molar ratio of 0.578:0.175:0.248, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 9 - {[ Li ₂ S ] _0.700 [( LiI )] _0.300 } _0.800 { P ₂ S ₅ } _0.200 Synthesis (X1=I; a=0.000; x=0.700; y=0.200)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ) and lithium iodide (LiI) in a molar ratio of 0.560: 0.200: 0.240, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 10 - {[ Li ₂ S ] _0.700 [( LiI )] _0.300 } _0.825 { P ₂ S ₅ } _0.250 Synthesis (X1=I; a=0.000; x=0.700; y=0.250)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ) and lithium iodide (LiI) in a molar ratio of 0.525:0.250:0.225, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 11 - {[ Li ₂ S ] _0.670 [( LiI )] _0.330 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; a=0.000; x=0.670; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ) and lithium iodide (LiI) in a molar ratio of 0.553: 0.175: 0.272, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 12 - {[ Li ₂ S ] _0.787 [( LiI )] _0.213 } _0.800 { P ₂ S ₅ } _0.200 Synthesis (X1=I; a=0.000; x=0.787; y=0.200)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), and lithium iodide (LiI) in a molar ratio of 0.630: 0.200: 0.170, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 13 - {[ Li ₂ S ] _0.658 [( LiI ) _0.950 ( LiBr ) _0.050 ] _0.342 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.050; x=0.658; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI), and lithium bromide (LiBr) in a molar ratio of 0.543: 0.175: 0.268: 0.014 was prepared, respectively.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 14 - {[ Li ₂ S ] _0.658 [( LiI ) _0.925 ( LiBr ) _0.075 ] _0.342 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.075; x=0.658; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI), and lithium bromide (LiBr) in a molar ratio of 0.543 : 0.175 : 0.261 : 0.021 was prepared, respectively.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 15 - {[ Li ₂ S ] _0.658 [( LiI ) _0.875 ( LiBr ) _0.125 ] _0.342 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.125; x=0.658; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI) and lithium bromide (LiBr) in a molar ratio of 0.543: 0.175: 0.247: 0.035, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 16 - {[ Li ₂ S ] _0.658 [( LiI ) _0.850 ( LiBr ) _0.150 ] _0.342 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.150; x=0.658; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI), and lithium bromide (LiBr) in a molar ratio of 0.543:0.175:0.240:0.042, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 17 - {[ Li ₂ S ] _0.658 [( LiI ) _0.800 ( LiBr ) _0.200 ] _0.342 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.200; x=0.658; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI), and lithium bromide (LiBr) in a molar ratio of 0.543 : 0.175 : 0.226 : 0.056 was prepared, respectively.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 18 - {[ Li ₂ S ] _0.658 [( LiI ) _0.700 ( LiBr ) _0.300 ] _0.342 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.300; x=0.658; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI), and lithium bromide (LiBr) in a molar ratio of 0.543:0.175:0.197:0.085, respectively, was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 19 - {[ Li ₂ S ] _0.670 [( LiI )] _0.330 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; a=0.000; x=0.670; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), and lithium iodide (LiI) in a molar ratio of 0.553: 0.175: 0.272, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 20 - {[ Li ₂ S ] _0.670 [( LiI ) _0.950 ( LiBr ) _0.050 ] _0.330 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.050; x=0.670; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI), and lithium bromide (LiBr) in a molar ratio of 0.553 : 0.175 : 0.259 : 0.014 was prepared, respectively.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 21 - {[ Li ₂ S ] _0.670 [( LiI ) _0.900 ( LiBr ) _0.100 ] _0.330 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.100; x=0.670; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI) and lithium bromide (LiBr) in a molar ratio of 0.553: 0.175: 0.245: 0.027 was prepared, respectively.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 22 - {[ Li ₂ S ] _0.670 [( LiI ) _0.875 ( LiBr ) _0.125 ] _0.330 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.125; x=0.670; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI) and lithium bromide (LiBr) in a molar ratio of 0.553: 0.175: 0.238: 0.034, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 23 - {[ Li ₂ S ] _0.670 [( LiI ) _0.850 ( LiBr ) _0.150 ] _0.330 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.150; x=0.670; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI) and lithium bromide (LiBr) in a molar ratio of 0.553: 0.175: 0.231: 0.041, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 24 - {[ Li ₂ S ] _0.670 [( LiI ) _0.825 ( LiBr ) _0.175 ] _0.330 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.175; x=0.670; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI) and lithium bromide (LiBr) in a molar ratio of 0.553: 0.175: 0.225: 0.048, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 25 - {[ Li ₂ S ] _0.670 [( LiI ) _0.800 ( LiBr ) _0.200 ] _0.330 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.200; x=0.670; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI) and lithium bromide (LiBr) in a molar ratio of 0.553: 0.175: 0.218: 0.054, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Example 26 - {[ Li ₂ S ] _0.670 [( LiI ) _0.700 ( LiBr ) _0.300 ] _0.330 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; X2=Br; a=0.300; x=0.670; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), lithium iodide (LiI) and lithium bromide (LiBr) in a molar ratio of 0.553: 0.175: 0.190: 0.082, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Comparative Example 1 - ( Li ₂ S ) _0.75 ( P ₂ S ₅ ) _0.25 Synthesis (a=0.000; x=0.000; y=0.250)

A mixture containing lithium sulfide (Li ₂ S) and diphosphorus pentasulfide (P ₂ S ₅ ) in a molar ratio of 0.75: 0.25, respectively, was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

Comparative Example 2 - {[ Li ₂ S ] _0.636 [( LiI )] _0.364 } _0.825 { P ₂ S ₅ } _0.175 Synthesis (X1=I; a=0.000; x=0.636; y=0.175)

A mixture containing lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ) and lithium iodide (LiI) in a molar ratio of 0.525: 0.175: 0.300, respectively was prepared.

The pulverization and synthesis steps were performed in the same manner as in Example 1 above to obtain a solid electrolyte in a powder state.

The composition and ion conductivity results of Examples 1 to 26, Comparative Examples 1 and 2 are summarized in Table 1 below.

X-ray diffraction analysis was performed on Examples 1, 2, and Comparative Examples 1 and 2. The result is shown in FIG. 2 . As shown in FIG. 2 , it can be seen that the sulfide-based solid electrolytes according to the above examples are in a glassy state.

⁷ Li-NMR analysis was performed on the sulfide-based solid electrolytes according to Examples 1 and 2, Comparative Examples 1 and 2 above. The result is shown in FIG. 3 . 3, the chemical shift and full width at half maximum of each sulfide-based solid electrolyte were obtained. This is shown in Table 2 below.

In addition, the lithium ion conductivity of the sulfide-based solid electrolytes according to Examples 1 and 2, Comparative Examples 1 and 2 was measured. These are shown together in Table 2 below.

division chemical shift [ppm] Full width at half maximum [ppm] Lithium ion conductivity [mS·cm ^-1 ] Example 1 -9.08112 0.616 1.97 Example 2 -9.08112 0.604 2.27 Comparative Example 1 -8.71297 0.784 0.24 Comparative Example 2 -9.20384 0.613 1.50

Referring to Table 2, Examples 1 and 2 have a peak at a chemical shift of -8.72 ppm to -9.20 ppm in the ⁷ Li-NMR spectrum, and the full width at half maximum of the peak is less than 0.7 ppm Able to know. Accordingly, the lithium ion conductivity was measured to be significantly higher than that of Comparative Examples 1 and 2.

Based on the Examples and Comparative Examples, the ionic conductivity results according to the composition molar ratios of the three raw materials (Li ₂ S, P ₂ S ₅ , and LiI) are shown in FIG. 4 as a contour map. Based on FIG. 4 , we confirmed the molar ratio of P ₂ S ₅ , which is a network former exhibiting high ionic conductivity, and derived the ratio of Li ₂ S and LiI accordingly. In the present invention, the molar ratio of the lithium halide composition added in addition to LiI was tested by additionally introducing an appropriate ratio compared to LiI, and an optimal molar ratio value was derived.

As the experimental examples and examples of the present invention have been described in detail above, the scope of the present invention is not limited to the above-described experimental examples and examples, and the basic concept of the present invention defined in the following claims. Various modifications and improved forms used by those skilled in the art are also included in the scope of the present invention.

Claims (12)

A sulfide glassy solid electrolyte for a lithium secondary battery in a glassy state, represented by the following formula (1).
[Formula 1]
{[Li ₂ S] _x [(LiX1) _1-a (LiX2) _a ] _1-x } _1-y {P ₂ S ₅ } _y
Formula 1 satisfies 0.55≤x≤0.80, 0<a≤0.5, 0.10≤y≤0.21,
X1 and X2 are different halogen elements and are respectively F, Cl, Br or I. According to claim 1,
Wherein x is a sulfide glassy solid electrolyte for a lithium secondary battery that satisfies 0.65≤x≤0.80. According to claim 1,
A sulfide glass-based solid electrolyte for a lithium secondary battery, characterized in that x and y in Formula 1 satisfy the following Formula 1.
[Equation 1]

According to claim 1,
A sulfide glassy solid electrolyte for a lithium secondary battery having a degree of crystallization measured by X-ray diffraction (XRD) of less than 5%. According to claim 1,
⁷ In the Li-NMR spectrum, the sulfide glassy solid electrolyte for a lithium secondary battery that has a peak at a chemical shift of -9.20 ppm to -8.72 ppm. According to claim 1,
⁷ The full width at half maximum (FWHM) of the peak found at -10ppm to -8ppm in the Li-NMR spectrum is less than 0.7ppm, a sulfide glass-based solid electrolyte for a lithium secondary battery. Preparing a starting material including lithium sulfide, diphosphorus pentasulfide and lithium halide by weighing it according to a composition according to Formula 1 below; and
A method for producing a sulfide glassy solid electrolyte for a lithium secondary battery, comprising the step of pulverizing the starting material.
[Formula 1]
{[Li ₂ S] _x [(LiX1) _1-a (LiX2) _a ] _1-x } _1-y {P ₂ S ₅ } _y
Formula 1 satisfies 0.55≤x≤0.80, 0<a≤0.5, 0.10≤y≤0.21,
X1 and X2 are different halogen elements and are respectively F, Cl, Br or I. 8. The method of claim 7,
Wherein x is a method of manufacturing a sulfide glassy solid electrolyte for a lithium secondary battery that satisfies 0.65≤x≤0.80. 8. The method of claim 7,
A method of manufacturing a sulfide glassy solid electrolyte for a lithium secondary battery, characterized in that x and y in Formula 1 satisfy the following Formula 1.
[Equation 1]

8. The method of claim 7,
A method of manufacturing a sulfide glassy solid electrolyte for a lithium secondary battery having a degree of crystallization measured by X-ray diffraction (XRD) of less than 5%. 8. The method of claim 7,
⁷ A method for producing a sulfide glassy solid electrolyte for a lithium secondary battery having a peak at a chemical shift of -9.20 ppm to -8.72 ppm in the Li-NMR spectrum. 8. The method of claim 7,
⁷ A method of manufacturing a sulfide glassy solid electrolyte for a lithium secondary battery in which the full width at half maximum (FWHM) of the peak found at -10 ppm to -8 ppm in the Li-NMR spectrum is less than 0.7 ppm.

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