KR20230083218A - Solid electrolyte and all-solid-state battery comprising same - Google Patents

Abstract

The present invention relates to a solid electrolyte and an all-solid-state battery including the same. Specifically, an oxide of a specific component is provided as a solid electrolyte (first solid electrolyte) and is provided as a solid electrolyte (second solid electrolyte) which includes the oxide of the specific component system as a first component and further includes an oxide or salt of another component at the same time.

Description

Solid electrolyte and all-solid-state battery including the same {SOLID ELECTROLYTE AND ALL-SOLID-STATE BATTERY COMPRISING SAME}

The present disclosure relates to a solid electrolyte and an all-solid-state battery including the same.

Lithium secondary batteries are widely used as a driving power source for small electronic devices such as mobile phones, laptops, and smartphones, and their application fields are expanding to driving power sources for battery vehicles and power storage power sources for energy storage devices. .

The most common type of lithium secondary battery is a lithium ion battery, which has problems (for example, potential hazards such as leakage, ignition, explosion, etc.) due to the use of a liquid electrolyte.

Recently, as a next-generation battery that solves the problems of a lithium ion battery, an all-solid-state battery in which the liquid electrolyte is replaced with a solid electrolyte has been in the spotlight. However, the solid electrolyte has a problem in that the ion conductivity is low compared to the liquid electrolyte, and ion movement resistance occurs at the interface between the electrode and the electrolyte. Therefore, for industrial mass production of all-solid-state batteries, it is necessary to increase the ionic conductivity of the solid electrolyte and reduce the ion migration resistance at the interface between the electrode and the electrolyte.

On the other hand, if an all-solid-state battery is manufactured in the form of a microchip, it can be used as an IT component such as an MLCC and a power inductor component based on its size and shape while basically having the characteristics of a battery. In such a microchip-type all-solid-state battery, it is advantageous to use an oxide-based solid electrolyte rather than a sulfide-based solid electrolyte or a polymer-based solid electrolyte from the viewpoints of eco-friendliness, product performance, and mass production. However, since a generally known oxide-based solid electrolyte has an amorphous glass structure, it may thermally expand or be easily broken during a co-firing process for manufacturing an ultra-small chip-type all-solid-state battery.

One embodiment is to provide an oxide of a specific component system as a solid electrolyte (first solid electrolyte) capable of increasing ionic conductivity, lowering interfacial resistance between an electrode and an electrolyte, suppressing thermal expansion, and enhancing strength.

Another embodiment provides a solid electrolyte (second solid electrolyte) having further improved ion conductivity by further including an oxide of the specific component system as a first component and an oxide or salt of another component system as a second component at the same time. It is to do.

Another embodiment is to provide an all-solid-state battery including any one of the solid electrolyte of the first type and the solid electrolyte of the second type.

One embodiment provides a first solid electrolyte.

The first solid electrolyte may be an oxide containing Li, Si, B, Zr, and P.

Of the total amount of 100 mol% of Li, Si, B, Zr, and P in the first solid electrolyte, Li is included in 40 mol% or more and 80 mol% or less, and Si is included in more than 0 mol% and 30 mol% or less. And, B is included in more than 0 mol% to 60 mol% or less, Zr is included in more than 0 mol% to 50 mol% or less, and P may be included in more than 0 mol% to 60 mol% or less.

The mole fraction of Li/(Si+B+Zr) in the first solid electrolyte may be 0.5 to 5.

The first solid electrolyte may be represented by Formula 1 below:

[Formula 1]

a(Li ₂ O)·b(SiO ₂ )·c(B ₂ O ₃ )·d(P ₂ O ₅ )·e(ZrO ₂ )

In Formula 1, a to e are real numbers representing mole fractions, and 40≤a≤60, 0<b≤30, 0<c≤60, 0<d≤60, and 0<e≤50.

The softening point of the first solid electrolyte may be 500 °C or higher and 550 °C or lower.

The first solid electrolyte may be glass or glass ceramic.

The first solid electrolyte is a glass ceramic, and upon X-ray diffraction (XRD) analysis using Cu-Kα, a crystalline phase may appear due to Li ₃ PO ₄ , specifically, a size of 1 nm or more to 10 nm or less in an amorphous structure A Li ₃ PO ₄ crystal phase having a may exist.

Ion conductivity of the first solid electrolyte may be 1.0 X 10 ^-8 S/cm or more.

Another embodiment provides a second solid electrolyte.

the second solid electrolyte includes an oxide containing Li, Si, B, Zr, and P; As the second component, Li, Al, Na, Mg, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Rb, S, Y, Nb, Mo, Ag , In, Sn, Sb, Cs, Ba, Hf, Ta, W, Pb, Bi, Au, La, Nd, Eu, I, Cl, Br, or oxides or salts containing at least one element of F; can include more.

The mole fraction of Li/(Si+B+Zr) in the second solid electrolyte may be 0.5 to 5.

The second solid electrolyte may be represented by Formula 2 below:

[Formula 2]

a(Li ₂ O)·b(SiO ₂ )·c(B ₂ O ₃ )·d(P ₂ O ₅ )·e(ZrO ₂ )·f(X _m Y _n )

In Formula 2, a to f are real numbers representing mole fractions, 40≤a≤60, 0<b≤30, 0<c≤60, 0<d≤60, 0<e≤50, 0≤f≤50; X is Li, Al, or a combination thereof; Y is Cl, O, or a combination thereof; 0<m≤5, and 0<n≤5.

The softening point of the second solid electrolyte may be 500 °C or higher and 550 °C or lower.

The second solid electrolyte may be glass or glass ceramic.

The second solid electrolyte may be a glass ceramic in which a peak due to Li ₃ PO ₄ appears during X-ray diffraction (XRD) analysis using Cu-Kα, and specifically has a size of 1 nm or more to 10 nm or less in an amorphous structure A Li ₃ PO ₄ crystalline phase may be present. Optionally, the second solid electrolyte may further show a peak due to Li ₄ B ₇ O ₁₂ Cl or Al ₂ O ₃ upon X-ray diffraction (XRD) analysis using Cu-Kα.

Ion conductivity of the second solid electrolyte may be 1.0 X 10 ^-7 S/cm or more.

Another embodiment is a body including a solid electrolyte layer and an anode layer and a cathode layer alternately stacked with the solid electrolyte layer interposed therebetween; Provides an all-solid-state battery including first external electrodes and second external electrodes respectively disposed on both side surfaces of the body, wherein the solid electrolyte layer includes any one of the first solid electrolyte and the second solid electrolyte can do.

The positive electrode layer and the negative electrode layer each independently include a current collecting layer and an electrode active material layer positioned on the current collecting layer; The current collecting layer and the electrode active material layer each independently include any one of the first solid electrolyte and the second solid electrolyte and a carbon-based conductive material; The electrode active material layer may further include an electrode active material.

The first solid electrolyte has high ionic conductivity, low interfacial resistance between the electrode and the electrolyte, suppressed thermal expansion and high strength, so that a multi-layered microchip all-solid-state battery can be manufactured through a co-firing process.

Furthermore, since the second solid electrolyte has higher ionic conductivity than the first solid electrolyte, the performance of the microchip-type all-solid-state battery can be further improved.

1 illustrates a connection relationship between elements constituting a solid electrolyte according to an embodiment of the present invention ((a): a first solid electrolyte, (b): a second solid electrolyte).
2 is a schematic cross-sectional view of an all-solid-state battery according to an embodiment of the present invention.
3 and 4 show the results of thermomechanical analysis (TMA) on the solid electrolytes according to Examples 1 and 8 of the present invention (FIG. 3: Example 1, FIG. 4: Example 8) ).
5 shows scanning electron microscope (SEM) images of solid electrolytes according to two Examples 1 and 8 of the present invention (left: Example 1, right: Example 8, scale All bars are 1 μm)
6 to 10 show the results of X-ray diffraction (XRD, Bruker AXS D4-Endeavor XRD) analysis using Cu-Kα on the solid electrolytes according to Examples 1 and 5 to 8 of the present invention (FIG. 6: Example 1, FIG. 7: Example 5, FIG. 8: Example 6, FIG. 9: Example 7, FIG. 10: Example 8).
FIG. 11 shows an image of a local area of the solid electrolyte according to Example 1 of the present invention taken using TEM equipment (right enlarged view).
12 shows an image of a local area of the solid electrolyte according to Example 8 of the present invention taken using a TEM device.
13 shows resistance measurement results for each of the solid electrolytes of Examples 1 and 8.
14 shows electrochemical evaluation results for an all-solid-state battery according to Example 1 of the present invention.

Hereinafter, with reference to the accompanying drawings, it will be described in detail so that those skilled in the art can easily carry out the present invention. In order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in this specification, the technical idea disclosed in this specification is not limited by the accompanying drawings, and all changes included in the spirit and technical scope of the present invention , it should be understood to include equivalents or substitutes. In addition, some components in the accompanying drawings are exaggerated, omitted, or schematically illustrated, and the size of each component does not entirely reflect the actual size.

Terms including ordinal numbers, such as first and second, may be used to describe various components, but the components are not limited by the terms. These terms are only used for the purpose of distinguishing one component from another.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle.

Throughout the specification, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but that one or more other features are present. It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded. Therefore, when a part "includes" a certain component, it means that it may further include other components, not excluding other components unless otherwise stated.

Throughout the specification, 'solid electrolyte' refers to a material capable of passing an electric current by the movement of ions in a solid state.

Throughout the specification, 'glass' generally refers to a material with high transparency that is formed when a mixture of silica sand, soda ash, carbonate lime, etc. is melted at a high temperature and then solidified without crystallization occurring in the process of cooling, and is distinguished from 'glass ceramic' described later. For this reason, it can be referred to as 'amorphous glass'.

Throughout the specification, 'glass ceramic' is a uniform aggregate of microcrystals obtained by heat-treating a glass molded body at a temperature above the transition temperature and below a melting temperature, and is also referred to as 'crystallized glass'. Since the 'glass ceramic' has an amorphous phase and at least one crystalline phase, it has both amorphous and crystalline characteristics. Specifically, the 'glass ceramic' has higher strength, high-temperature stability, chemical durability, and ionic conductivity than amorphous glass, and suppresses thermal expansion.

Throughout the specification, 'ionic conductivity' is a measure of the ionic conductivity of a material, and theoretically increases in proportion to the concentration of ions, the amount of charge, and the mobility of charges.

Hereinafter, various implementations will be described in detail with reference to the drawings.

(First solid electrolyte)

One embodiment provides a first solid electrolyte that is an oxide including Li, Si, B, Zr, and P.

The first solid electrolyte has high ionic conductivity, low interfacial resistance between the electrode and electrolyte, suppressed thermal expansion and strong strength, compared to an oxide solid electrolyte containing Li, Si, B, and P but not containing Zr. , it is advantageous to fabricate a multi-layered ultra-small chip-type all-solid-state battery through a co-firing process.

A description of the elements constituting the first solid electrolyte is as follows.

The Li, Si, and B are essential constituent elements of a generally known amorphous glass for a solid electrolyte, and also form an amorphous structure in the first solid electrolyte.

Specifically, among 100 mol% of the total amount of Li, Si, B, Zr, and P in the first solid electrolyte, Li is 40 mol% or more to 80 mol% or less, 40 mol% or more to 70 mol% or less, or 40 mol% % or more to 60 mol% or less. Si may be included in an amount of more than 0 mol% to 30 mol% or less, 3 mol% or more to 20 mol% or less, or 5 mol% or more to 15 mol% or less. B may be included in an amount of more than 0 mol% to 60 mol% or less, 5 mol% or more to 40 mol% or less, or 10 mol% or more to 20 mol% or less.

Meanwhile, Zr and P may form an amorphous structure having a specific structure together with Li, Si, and B. Specifically, (a) of FIG. 1 shows a connection relationship between elements constituting the first solid electrolyte. As shown in (a) of FIG. 1, in the first solid electrolyte, Li, Si, B, Zr, and P are -B-O-Si-O-P-O-Zr- network-based amorphous organization Non Bridged Oxide (NBO ) structure, it is possible to achieve properties such as high ionic conductivity, low thermal expansion, and high strength.

In contrast, an oxide solid electrolyte containing Li, Si, B, and P but not Zr can form an amorphous structure based on a -B-O-Si-O-P-O- network, which is -B-O-Si-O-P-O-Zr - Unlike the network-based amorphous organization, it forms an unstable organization with fewer holes in the Non Bridged Oxide (NBO) structure. Accordingly, characteristics such as ionic conductivity, thermal expansion, and strength may be inferior to those of the first solid electrolyte.

Specifically, Zr may be included in an amount of greater than 0 mol% to 50 mol% or less, 1 mol% to 20 mol% or less, or 1 mol% to 10 mol%. P may be included in an amount of more than 0 mol% to 60 mol% or less, 1 mol% or more to 20 mol% or less, or 5 mol% or more to 15 mol% or less.

For reference, the molar content of each element in 100 mol% of the total amount of Li, Si, B, Zr, and P in the first solid electrolyte can be confirmed through ICP analysis.

The mole fraction of Li/(Si+B+Zr) in the first solid electrolyte may be 0.5 to 5.

This represents the molar content of the main elements constituting the first solid electrolyte as a relational expression. As mentioned above, Li, Si, and B are generally known essential elements of amorphous glass, and Zr is an element that contributes to forming an amorphous structure of a specific network structure of the first solid electrolyte. When they satisfy the relational expression above, the -B-O-Si-O-P-O-Zr- network-based amorphous structure and the resulting holes of the Non Bridged Oxide (NBO) structure can be effectively formed.

For example, the mole fraction of Li/(Si+B+Zr) in the first solid electrolyte may be 0.5 or more, 1 or more, or 1.5 or more, and 5 or less, 4 or less, 3 or less, or 2 or less.

For reference, the mole fraction of Li/(Si+B+Zr) in the first solid electrolyte can be calculated from the molar content of each element out of 100 mol% of the total amount of Li, Si, B, Zr, and P in the first solid electrolyte. can

The first solid electrolyte may be represented by Formula 1 below:

[Formula 1]

a(Li ₂ O)·b(SiO ₂ )·c(B ₂ O ₃ )·d(P ₂ O ₅ )·e(ZrO ₂ )

In Formula 1, a to e are real numbers representing mole fractions, and may be 40≤a≤80, 40≤a≤0, or 40≤a≤60; 0<b≤30, 3≤b≤20, or 5≤b≤15; 0<c≤60, 5≤c≤40, or 10≤c≤20; 0<d≤60, 1≤d≤20, or 1≤d≤15; 0<e≤50, 1≤e≤20, or 1≤e≤10.

The explanation for this is the same as the description of the molar content of each element in 100 mol% of the total amount of Li, Si, B, Zr, and P in the first solid electrolyte.

The first solid electrolyte may be softened in a specific temperature range based on its amorphous nature.

Specifically, the softening point of the first solid electrolyte may be within a temperature range of 500 °C or more, 505 °C or more, or 510 °C or more, and 550 °C or less, 540 °C or less, or 530 °C or less.

For reference, the softening point of the first solid electrolyte can be confirmed through TMA thermal analysis.

The first solid electrolyte may be glass or glass ceramic.

As defined above, 'glass' is an amorphous material, and 'glass ceramic' is a material containing one or more crystalline phases in an amorphous structure.

In particular, when the first solid electrolyte is a glass ceramic, the ionic conductivity is high, the interface resistance between the electrode and the electrolyte is low, the thermal expansion is suppressed and the strength is strong, so that the co-firing process It is advantageous for manufacturing a multi-layered ultra-small chip-type all-solid-state battery.

Specifically, when the first solid electrolyte is a glass ceramic, during X-ray diffraction (XRD) analysis using Cu-Kα, a peak due to Li ₃ PO ₄ may appear in the range of 2θ of 22 to 25 °. Here, the amorphous structure is inferred to include a -BO-Si-OPO-Zr- network, and the amorphous structure based on the -BO-Si-OPO-Zr- network has holes of a Non Bridged Oxide (NBO) structure. can

In addition, when the first solid electrolyte is a glass ceramic, a crystal phase having a size of 1 nm or more or 3 nm or more and 10 nm or less or 5 nm or less in the amorphous structure can be identified through analysis such as FE-SEM, TEM, etc. there is.

In summary, when the first solid electrolyte is a glass ceramic, in an amorphous structure including a -BO-Si-OPO-Zr- network, a size of 1 nm or more or 3 nm or more and 10 nm or less or 5 nm or less A Li ₃ PO ₄ crystal phase may exist.

Ion conductivity of the first solid electrolyte may be 1.0 X 10 ^-8 S/cm or more. This is done by applying InGa paste, Ag paste, etc. on both sides of the solid electrolyte layer including the first solid electrolyte therebetween; After making an all-solid-state battery sample by sputtering Au, Pt, Ag, etc. to form a metal electrode, it may be mounted on a jig and measure the EIS voltage within the range of 10 ^-6 Hz at a reference frequency of 100 mV.

The manufacturing method of the first solid electrolyte is not particularly limited and may follow a generally known oxide-based solid electrolyte manufacturing method.

As a generally known method for producing an oxide-based solid electrolyte, various glass production methods such as a conventional melt-quenching method, a press melt-quenching method, and a twin-roller melt quenching method are possible. The crucible in the device uses alumina, high-density alumina, platinum-coated, and iridium-coated products.

The raw materials are blended according to the stoichiometric molar ratio of the target composition, heat-treated in the range of 450 to 700 ° C. to sufficiently volatilize ammonia in the blended raw materials, and continuously maintained at 1200 ° C. for about 2 hours, and then vitrification is performed. The molten metal after vitrification is cooled in the range of 500 to 700 ℃ and recovered as a cullet-shaped bulk material. These cullets are pulverized without secondary particles (aggregates) through a constant grinding process in absolute ethanol, and after drying, through a classification process, glass ceramics in the form of particles with an average particle diameter (D50) of 1.5 to 3.0 μm are obtained. can be obtained

(Second solid electrolyte)

Another embodiment includes an oxide comprising Li, Si, B, Zr, and P; As the second component, Li, Al, Na, Mg, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Rb, S, Y, Nb, Mo, Ag , In, Sn, Sb, Cs, Ba, Hf, Ta, W, Pb, Bi, Au, La, Nd, Eu, I, Cl, Br, or oxides or salts containing at least one element of F; It provides a second solid electrolyte further comprising.

As the second solid electrolyte further includes a specific element or atomic group compared to the first solid electrolyte, higher ionic conductivity can be achieved and performance of the microchip-type all-solid-state battery can be further improved.

1(b) shows a connection relationship between elements constituting the second solid electrolyte. Here, the case of including Li and Cl as the second component was exemplified.

According to (b) of FIG. 1, in the second solid electrolyte, as in the first solid electrolyte, an amorphous structure based on a -BO-Si-OPO-Zr- network forms holes of a Non Bridged Oxide (NBO) structure. However, since the second solid electrolyte further includes the second component compared to the first solid electrolyte, the hole size of the Non Bridged Oxide (NBO) structure is larger. In addition, among the second components, some of the anion component (Cl) bonds with oxygen by substitution or electrostatic bonding, thereby lowering the electronegativity of the second solid electrolyte. As a result, the second component can create an effective ion pathway so that Li ⁺ cations ejected from the active material electrode can easily pass through.

Of the total amount of 100 mol% of Li, Si, B, Zr and P in the second solid electrolyte, Li is included in 40 mol% or more and 80 mol% or less, and Si is included in more than 0 mol% and 30 mol% or less. And, B is included in more than 0 mol% to 60 mol% or less, Zr is included in more than 0 mol% to 50 mol% or less, and P may be included in more than 0 mol% to 60 mol% or less. A description thereof is the same as that of the first solid electrolyte.

In addition, the mole fraction of Li/(Si+B+Zr) in the second solid electrolyte may be 0.5 to 5. A description thereof is also the same as that of the first solid electrolyte.

For reference, the mole fraction of Li/(Si+B+Zr) may be partially higher in the second solid electrolyte than in the first solid electrolyte, but this is due to the presence of the second component (Si+B+Zr). Mole fraction means relatively reduced.

Specifically, the second solid electrolyte may be represented by Formula 2 below:

[Formula 2]

a(Li ₂ O)·b(SiO ₂ )·c(B ₂ O ₃ )·d(P ₂ O ₅ )·e(ZrO ₂ )·f(X _m Y _n )

In Formula 2, a to f are real numbers representing mole fractions, and may be 40≤a≤80, 40≤a≤0, or 40≤a≤60; 0<b≤30, 3≤b≤20, or 5≤b≤15; 0<c≤60, 5≤c≤40, or 10≤c≤20; 0<d≤60, 1≤d≤20, or 1≤d≤15; 0<e≤50, 1≤e≤20, or 1≤e≤10; 0≤f≤50, 1≤f≤10, or 1≤f≤5; X is Li, Al, or a combination thereof; Y is Cl, O, or a combination thereof; 0<m≤5 or 1≤m≤3; 0<n≤5 or 1≤n≤4.

The second solid electrolyte may also be softened in a specific temperature range based on amorphous characteristics.

Specifically, the softening point of the second solid electrolyte may be within a temperature range of 500 °C or higher and 550 °C or lower. A description thereof is also the same as that of the first solid electrolyte.

The second solid electrolyte may also be glass or glass ceramic, and the description thereof is the same as that of the first solid electrolyte.

In particular, when the second solid electrolyte is a glass ceramic, during X-ray diffraction (XRD) analysis using Cu-Kα, a peak due to Li ₃ PO ₄ may appear in the range of 2θ of 22 to 25 °, and 2θ of 42 A peak by Li ₄ B ₇ O ₁₂ Cl in the range of from 45 ° to 45 ° or a peak by Al ₂ O ₃ in the range of 2θ of 15 to 20 ° may further appear. The peak by Li ₃ PO ₄ appears in common with the case where the first solid electrolyte is a glass ceramic, and the peak by Li ₄ B ₇ O ₁₂ Cl and the peak by Al ₂ O ₃ are related to the second component. will appear by

In summary, when the second solid electrolyte is a glass ceramic, in an amorphous structure including a -BO-Si-OPO-Zr- network, a size of 1 nm or more or 3 nm or more and 10 nm or less or 5 nm or less A Li ₃ PO ₄ crystal phase is essentially present, and optionally a _{Li 4 B 7} O ₁₂ Cl crystal phase or an Al ₂ O ₃ crystal phase having the same/similar size as _the Li 3 PO 4 crystal phase may further exist.

As described above, the second solid electrolyte may exhibit higher ionic conductivity than the first solid electrolyte. Specifically, the ionic conductivity of the second solid electrolyte may be 1.0 X 10 ^-7 S/cm or more. Its measurement method is as described above.

The second solid electrolyte can be obtained by heat treatment while maintaining a temperature range of 525 to 530 ° C. for 8 to 10 hours in an air atmosphere after adding additives to the first solid electrolyte according to the stoichiometric molar ratio according to the target composition. there is.

(All-solid-state battery)

Another embodiment is a body including a solid electrolyte layer and an anode layer and a cathode layer alternately stacked with the solid electrolyte layer interposed therebetween; A first external electrode and a second external electrode are respectively disposed on both sides of the body, and the solid electrolyte layer includes a solid electrolyte of any one of the first solid electrolyte and the second solid electrolyte according to claim A solid-state battery can be provided.

The all-solid-state battery of one embodiment may be a microchip-type all-solid-state battery. As mentioned above, the microchip-type all-solid-state battery is treated as equivalent to IT components such as MLCC and power inductor components based on its size and shape, while fundamentally having battery characteristics.

In the microchip-type all-solid-state battery, the battery itself can be SMD mounted on a board like a chip, and it is possible to increase the degree of freedom in circuit design on a board like a passive device.

In the microchip-type all-solid-state battery, it is common to use an oxide-based solid electrolyte rather than a sulfide-based solid electrolyte or a polymer-based solid electrolyte. The oxide-based solid electrolyte has advantages in a wide electrochemical potential window, excellent secondary interfacial reaction suppression ability, low manufacturing cost, and applicability in a wide range of compositions, etc. It is also possible to implement

In particular, since the all-solid-state battery of one embodiment applies any one of the first solid electrolyte and the second solid electrolyte to the solid electrolyte layer, including Li, Si, B, and P but not including Zr Compared to the case where the oxide solid electrolyte is applied to the solid electrolyte layer, performance and durability may be excellent.

2 schematically illustrates a cross-sectional view of an all-solid-state battery according to an embodiment of the present invention.

Referring to FIG. 2 , the all-solid-state battery may include a body including the solid electrolyte layer 123 and the positive electrode layer and the negative electrode layer alternately stacked with the solid electrolyte layer 123 interposed therebetween. In addition, the all-solid-state battery may further include first external electrodes 131 and second external electrodes 132 respectively disposed on both side surfaces of the body.

Specifically, the all-solid-state battery includes an electrode layer and a solid electrolyte layer disposed adjacent to the electrode layer in a stacking direction. The electrode layer may basically include a current collector 125 and electrode active material layers 121 and 122 coated on one side or both sides of the current collector 125 .

For example, the uppermost electrode layer in the stacking direction is formed by coating the negative electrode active material layer 122 on one surface of the negative electrode current collector 125, and the lowermost electrode layer is formed by applying the negative electrode active material layer 122 to one surface of the positive electrode current collector 125. The active material layer 121 may be coated and formed. In addition, the electrode layers positioned between the uppermost and lowermost ends are formed by coating the positive electrode active material layer 121 on both sides of the positive electrode current collector 125, or by applying the negative electrode active material layer 122 on both sides of the negative electrode current collector 125. can

The solid electrolyte layer 123 may be interposed and stacked between the anode layer and the cathode layer. Accordingly, the solid electrolyte layer 123 may be disposed adjacent to each other in the stacking direction between the positive active material layer 121 of the positive electrode layer and the negative active material layer 123 of the negative electrode layer. Accordingly, in the all-solid-state battery, a plurality of anode layers and a plurality of cathode layers may be alternately disposed, and stacked with a plurality of solid electrolyte layers 123 interposed therebetween.

An insulating layer 124 may be disposed along edges of the anode layer and the cathode layer. The insulating layer 124 is positioned on the solid electrolyte layer 130 and may be formed laterally adjacent to an edge of the anode layer or the cathode layer. Accordingly, the insulating layer 150 may be positioned on the same layer as the anode layer and the cathode layer. The insulating layer 150 may be formed using the same material as the solid electrolyte layer 123 . Therefore, in an all-solid-state battery, the insulating layer and the solid electrolyte layer do not have a boundary and may be composed of the solid electrolyte layer 123 integrally formed.

The positive electrode layer, the solid electrolyte layer 123, the negative electrode layer, and the insulating layer may be stacked as described above to form a cell stack of an all-solid-state battery. A protective layer made of an insulating material may be formed on the upper and lower ends of the cell stack of the all-solid-state battery. In addition, terminals of the positive current collector 125 and terminals of the negative current collector 125 are exposed on both sides of the cell stack of the all-solid-state battery, and external electrodes 131 and 132 are connected to the exposed terminals, can be combined That is, the external electrodes 131 and 132 may be configured to be connected to terminals of the positive current collector 125 to have positive poles and connected to terminals of the negative current collector 125 to have negative poles. When the terminals of the positive current collector 125 and the terminals of the negative current collector 125 are configured to face in opposite directions, the external electrodes 131 and 132 may also be positioned on both sides, respectively.

The positive electrode layer, the solid electrolyte layer 123, and the negative electrode layer may be stacked to form a cell stack of an all-solid-state battery. A protective layer 140 may be formed of an insulating material at the top and bottom of the cell stack of the all-solid-state battery, and the insulating material may also be made of the same material as the solid electrolyte layer 123 .

As the positive electrode active material included in the positive electrode layer, a compound capable of reversible intercalation and deintercalation of lithium (lithiated intercalation compound) may be used. Specifically, one or more of cobalt, manganese, nickel, or a combination of metals and lithium composite oxides may be used, and as specific examples thereof, a compound represented by any one of the following formulas may be used. Li _a A _1-b R _b D ₂ (wherein 0.90 ≤ a ≤ 1.8 and 0 ≤ b ≤ 0.5); Li _a E _1-b R _b O _2-c D _c (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); LiE _2-b R _b O _4-c D _c (wherein 0 ≤ b ≤ 0.5 and 0 ≤ c ≤ 0.05); Li _a Ni _1-bc Co _b R _c D _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α ≤ 2); Li _a Ni _1-bc Co _b R _c O _2-α Z _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α <2); Li _a Ni _1-bc Co _b R _c O _2-α Z ₂ (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α <2); Li _a Ni _1-bc Mn _b R _c D _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α ≤ 2); Li _a Ni _1-bc Mn _b R _c O _2-α Z _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α <2); Li _a Ni _1-bc Mn _b R _c O _2-α Z ₂ (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α <2); Li _a Ni _b E _c G _d O ₂ (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5 and 0.001 ≤ d ≤ 0.1); Li _a Ni _b Co _c Mn _d G _e O ₂ (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5 and 0.001 ≤ e ≤ 0.1); Li _a NiG _b O ₂ (wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li _a CoG _b O ₂ (wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li _a MnG _b O ₂ (wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li _a Mn ₂ G _b O ₄ (wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); QO ₂ ; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₅ ; LiTO ₂ ; LiNiVO ₄ ; Li _(3-f) J ₂ (PO ₄ ) ₃ (0 ≤ f ≤ 2); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0 ≤ f ≤ 2); and LiFePO ₄ .

In the above formula, A is Ni, Co, Mn or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P or a combination thereof; E is Co, Mn or a combination thereof; Z is F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or combinations thereof; Q is Ti, Mo, Mn or a combination thereof; T is Cr, V, Fe, Sc, Y or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu or combinations thereof.

Of course, one having a coating layer on the surface of this compound may be used, or a mixture of the compound and a compound having a coating layer may be used. The coating layer may include an oxide, hydroxide, oxyhydroxide of a coating element, oxycarbonate of a coating element, or hydroxycarbonate of a coating element as a compound of a coating element. Compounds constituting these coating layers may be amorphous or crystalline. As the coating element included in the coating layer, Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof may be used. In the coating layer forming process, any coating method may be used as long as the compound can be coated with a method that does not adversely affect the physical properties of the positive electrode active material by using these elements (eg, spray coating, dipping method, etc.). Since it is a content that can be well understood by those working in the field, detailed explanations will be omitted.

Examples of the negative electrode active material included in the negative electrode layer include a material capable of reversibly intercalating/deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and undoping lithium, or transition Metal oxides may be used.

A material capable of reversibly intercalating/deintercalating the lithium ion is a carbon material, and any carbon-based negative electrode active material commonly used in a lithium ion secondary battery may be used, and a representative example thereof is crystalline carbon , amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate, flake, spherical or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbide, calcined coke, and the like.

The alloy of lithium metal is a combination of lithium and a metal of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al or Sn. alloys may be used.

Materials capable of doping and undoping the lithium include Si, SiO _x (0 < x < 2), Si-C complex, Si-Q alloy (Q is an alkali metal, an alkaline earth metal, a Group 13 to Group 16 element) , a transition metal, a rare earth element, or a combination thereof, but not Si), Sn, SnO ₂ , Sn—C complex, Sn—R (wherein R is an alkali metal, an alkaline earth metal, a Group 13 to Group 16 element, a transition metal, a rare earth element or a combination thereof, but not Sn), and the like. Specific elements of Q and R include Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po or combinations thereof.

Examples of the transition metal oxide include vanadium oxide, lithium vanadium oxide, lithium vanadium oxide, and lithium vanadium phosphate (Li ₃ V ₂ (PO ₄ ) ₃ , LVP).

Examples and comparative examples of the present invention are described below. The examples described below are only examples of the present invention, but the present invention is not limited to the examples described below.

Example 1

For producing glass ceramics, Li ₂ CO ₃ (purity 99%); SiO ₂ (purity 99.8%); B ₂ O ₃ (purity 95%); ZrO ₂ (purity 98%); And P ₂ O ₅ (purity 98%) or (NH ₄ ) ₂ HPO ₄ (98%) is used as a raw material.

A twin-roller melt quenching method was used as a method of manufacturing glass ceramics, and the crucible in the apparatus using the twin-roller melt quenching method was a platinum product.

57 (Li ₂ O) 10 (SiO ₂ ) 18 (B ₂ O ₃ ) 12 (P ₂ O ₅ ) 3 (ZrO ₂ ) With [mol%] as the target composition, the raw materials are blended according to the stoichiometric molar ratio, heat-treated in the range of 450 to 700 ° C. to sufficiently volatilize the ammonia in the blended raw materials, and continuously maintained at 1200 ° C. for about 2 hours After that, the vitrification process is carried out. The molten metal after vitrification is cooled in the range of 500 to 700 ℃ and recovered as a cullet-shaped bulk material. These cullets are pulverized without secondary particles (aggregates) through a constant grinding process in absolute ethanol, and after drying, through a classification process, glass ceramics in the form of particles with an average particle diameter (D50) of 1.5 to 3.0 μm are obtained. Acquire The glass ceramic was used as the solid electrolyte of Example 1.

Example 2

The target composition is 57 (Li ₂ O) 10 (SiO ₂ ) 18 (B ₂ O ₃ ) 14 (P ₂ O ₅ ) 1 (ZrO ₂ ) The solid electrolyte of Example 2 was prepared using the same method as Example 1, except for changing [mol%].

Example 3

The target composition is 57 (Li ₂ O) 10 (SiO ₂ ) 18 (B ₂ O ₃ ) 10 (P ₂ O ₅ ) 5 (ZrO ₂ ) The solid electrolyte of Example 3 was prepared using the same method as Example 1, except for changing [mol%].

Example 4

The target composition is 57 (Li ₂ O) 10 (SiO ₂ ) 18 (B ₂ O ₃ ) 5 (P ₂ O ₅ ) 10 (ZrO ₂ ) The solid electrolyte of Example 4 was prepared using the same method as Example 1, except for changing [mol%].

Example 5

A mixed powder was prepared by post-adding LiCl to the glass ceramic prepared in Example 1. Of 100% by weight of the mixed powder, the content of the post-added LiCl is 5% by weight.

Thereafter, the mixed powder is heat-treated while maintaining a temperature range of 525 to 530° C. for 8 to 10 hours in an air atmosphere.

Accordingly, the solid electrolyte of Example 5 is obtained, and the target (expected) composition of the solid electrolyte is 56 (Li ₂ O) 10 (SiO ₂ ) 16 (B ₂ O ₃ ) 10 (P ₂ O ₅ )·3(ZrO ₂ )·5(LiCl) is [mol%].

Example 6

The solid electrolyte of Example 6 was obtained in the same manner as in Example 5, except that Li ₃ PO ₄ was added instead of LiCl, and the target (expected) composition of the solid electrolyte was 57 (Li ₂ O) 10 (SiO ₂ ) 16 (B ₂ O ₃ ) 14 (P ₂ O ₅ ) 3 (ZrO ₂ ) is [mol%].

Example 7

The solid electrolyte of Example 7 was obtained in the same manner as in Example 5, except that Li ₂ CO ₃ was added instead of LiCl, and the target (expected) composition of the solid electrolyte was 61 (Li ₂ O) 10 (SiO ₂ ) 16 (B ₂ O ₃ ) 10 (P ₂ O ₅ ) 3 (ZrO ₂ ) is [mol%].

Example 8

The solid electrolyte of Example 8 was obtained in the same manner as in Example 5, except that α-Al ₂ O ₃ was added instead of LiCl, and the target (expected) composition of the solid electrolyte was 56 (Li ₂ O) 10(SiO ₂ ) 16(B ₂ O ₃ ) 10(P ₂ O ₅ ) 3(ZrO ₂ ) 5(Al ₂ O ₃ ) is [mol%].

Example 9

The target composition is 56 (Li ₂ O) 10 (SiO ₂ ) 16 (B ₂ O ₃ ) 10 (P ₂ O ₅ ) 7 (ZrO ₂ ) 1 (Al ₂ O ₃ ) The solid electrolyte of Example 9 was prepared in the same manner as in Example 8, except that [mol%] was changed.

Example 10

The target composition is 56 (Li ₂ O) 10 (SiO ₂ ) 16 (B ₂ O ₃ ) 10 (P ₂ O ₅ ) 5 (ZrO ₂ ) 3 (Al ₂ O ₃ ) The solid electrolyte of Example 10 was prepared using the same method as in Example 8, except for changing [mol%].

Comparative Example 1

Using the same method as in Example 1 except that the target composition was changed to 57 (Li ₂ O) 10 (SiO ₂ ) 18 (B ₂ O ₃ ) 15 (P ₂ O ₅ ) [mol%] , preparing the solid electrolyte of Comparative Example 1.

Comparative Example 2

While using GeO ₂ instead of ZrO ₂ as a raw material, the target composition was 57 (Li ₂ O) 10 (SiO ₂ ) 18 (B ₂ O ₃ ) 12 (P ₂ O ₅ ) 3 (GeO ₂ ) A solid electrolyte of Comparative Example 2 was prepared in the same manner as in Example 1, except for changing [mol%].

For reference, the target composition used to prepare each of the solid electrolytes of Examples 1 to 10 and Comparative Examples 1 and 2 is shown in Table 1 below.

(unit: mol%) Li ₂ O SiO ₂ B ₂ O ₃ P ₂ O ₅ ZrO ₂ X _m Y _n Total note Example 1 57 10 18 12 3 - 100 - Example 2 57 10 18 14 One - 100 - Example 3 57 10 18 10 5 - 100 - Example 4 57 10 18 5 10 - 100 - Example 5 56 10 16 10 3 5 100 X _m Y _n = LiCl Example 6 57 10 16 14 3 - 100 - Example 7 61 10 16 10 3 - 100 - Example 8 56 10 16 10 3 5 100 X _m Y _n = α-Al ₂ O ₃ Example 9 56 10 16 10 7 One 100 X _m Y _n = α-Al ₂ O ₃ Example 10 56 10 16 10 5 3 100 X _m Y _n = α-Al ₂ O ₃ Comparative Example 1 57 10 18 15 - - 100 - Comparative Example 2 57 10 18 12 - 3 100 X _m Y _n = GeO ₂

Evaluation Example 1: Evaluation of solid electrolyte

(1) ICP analysis

For each of the solid electrolytes of Examples 1 and 8, the mole fraction of the main elements was measured through ICP analysis.

The ICP analysis method was measured using an inductively coupled plasma emission spectrometer (ICP-OES, device name: Optima 7300DV, manufacturer: PerkinElmer). Specifically, about 0.7 g of a solid electrolyte sample was put in a platinum crucible, and about 1 mL of concentrated sulfuric acid (98% by weight, electronic grade) was added, heated at 300 ° C. for 3 hours, and the sample was heated in an electric furnace (Thermo Scientific, Lindberg Blue M), the conversation was conducted with the program of steps 1 to 3 below.

1) step 1: initial temp 0℃, rate (temp/hr) 180 ℃/hr, temp(holdtime) 180℃ (1hr)

2) step 2: initial temp 180℃, rate (temp/hr) 85 ℃/hr, temp(holdtime) 370℃ (2hr)

3) step 3: initial temp 370℃, rate (temp/hr) 47 ℃/hr, temp(holdtime) 510℃ (3hr)

Thereafter, 1 mL of concentrated nitric acid (48% by weight) and 20 μl of concentrated hydrofluoric acid (50% by weight) were added to the residue, and the platinum crucible was sealed and shaken for 30 minutes or more, and then 1 mL of boric acid was added to the sample. After storing at 0 ° C. for 2 hours or more, it was diluted in 30 mL of ultrapure water and measured by incineration.

Accordingly, the mole fraction of the main elements included in each of the solid electrolytes of Examples 1 and 8 was measured, and the measured values are shown in Table 2 below. In addition, the target composition used to prepare each of the solid electrolytes of Examples 1 and 5 is also shown in Table 2 below.

(unit: mol%) Li ₂ O SiO ₂ B ₂ O ₃ P ₂ O ₅ ZrO ₂ Al ₂ O ₃ Total Example 1 goal creation
(chemical formula) 57 10 18 12 3 - 100 Measures
(ICP-OES) 57.6 9 18.7 11.6 3.1 - 100 Example 8 goal creation
(chemical formula) 56 10 16 10 3 5 100 Measures
(ICP-OES) 56.2 9.2 16.3 10.8 2.8 4.7 100

According to Table 2, it can be seen that although some elements were lost during the process of preparing each of the solid electrolytes of Examples 1 and 8, the target composition and the actual measured value were almost the same.

Further, each of the solid electrolytes of Examples 1 and 8 had a mole fraction of Li/(Si+B+Zr) within a range of 0.5 to 5. Specifically, based on the measured values, the mole fraction of Li/(Si+B+Zr) of the solid electrolyte of Example 1 was 1.87, and the mole fraction of Li/(Si+B+Zr) of the solid electrolyte of Example 8 was It is about 1.99. The reason why the mole fraction of Li/(Si+B+Zr) is partially higher in the solid electrolyte of Example 8 than in the solid electrolyte of Example 1 is that the mole fraction of (Si+B+Zr) decreases with the presence of the second component. caused by

Here, the solid electrolytes of Examples 1 and 8 were evaluated representatively, but each solid electrolyte of Examples 2 to 4, 9 and 10 and Comparative Examples 1 and 2 would also have the same target composition and actual measured values.

(2) TMA thermal analysis

For each of the solid electrolytes of Examples 1 and 8, thermomechanical analysis (TMA) was performed, and the analysis results are shown in FIGS. 3 and 4.

Specifically, under an air and nitrogen atmosphere, a 10 mm length sample is placed in a TMA instrument (TA Instrument, Q400) and exposed to increasing temperature conditions (5 ° C / min starting at 30 ° C) with a tension of 19.6 mN applied. . As the temperature rises, the length of the sample is accompanied by a change, and the temperature at which the length is rapidly increased and the sample breaks is measured. Measure the MD and TD respectively and define the higher temperature as the meltdown temperature of that sample.

According to FIGS. 3 and 4, it was confirmed that each of the solid electrolytes of Examples 1 and 8 softened at 500 to 550 °C. Specifically, the solid electrolyte of Example 1 is a softening start step at 516 to 526 ° C, and the solid electrolyte of Example 8 is determined to be a softening start step at 527 ° C.

On the other hand, for each of the solid electrolytes of Examples 1 and 8, the temperature was raised at a heating rate of 3 ° C / min in an electric furnace in which a mixed atmosphere of nitrogen (N ₂ ) and air was maintained, maintained at 530 ° C for 8 hours, and then cooled naturally, SEM images were obtained and shown in FIG. 6 . According to FIG. 5 , it can be seen that each of the solid electrolytes of Examples 1 and 5 softened after heat treatment based on amorphous characteristics.

Here, each solid electrolyte of Examples 1 and 8 was evaluated representatively, but it is inferred that each solid electrolyte of Examples 2 to 4, 9 and 10 also has a softening point of 500 ° C. or more and 550 ° C. or less.

(3) XRD analysis

For each of the solid electrolytes of Examples 1 and 5 to 8, X-ray diffraction (XRD, Bruker AXS D4-Endeavor XRD) analysis was performed using Cu-Kα, and the analysis results are shown in FIGS. 6 to 10.

In each of the solid electrolytes of Examples 1 and 5 to 8, peaks due to Li ₃ PO ₄ are commonly observed in the range of 2θ of 22 to 25 ° (FIGS. 6 to 10). Furthermore, in the solid electrolyte of Example 5, the peak due to Li ₄ B ₇ O ₁₂ Cl in the range of 2θ of 42 to 45 ° Further observed (Fig. 7), which is attributed to the preparation by adding LiCl. In addition, in the solid electrolyte of Example 8, a peak due to α-Al ₂ O ₃ was additionally observed in the range of 2θ from 15 to 20 ° (FIG. 10), which was obtained by adding α-Al ₂ O ₃ caused by

Here, each solid electrolyte of Examples 1 and 5 to 8 was evaluated representatively, but each solid electrolyte of Examples 2 to 4, 6 and 7 was similar to the solid electrolyte of Example 1, and each solid electrolyte of Examples 9 and 10 The electrolyte is inferred to yield similar results to the solid electrolyte of Example 8.

(4) FE-SEM and TEM analysis

For the solid electrolytes of Examples 1 and 8, local areas were observed using TEM equipment, and the results are shown in FIGS. 11 and 12, respectively.

11 and 12, it can be seen that a crystal phase having a size of 3 to 5 nm is present in the amorphous structure in common to each of the solid electrolytes of Examples 1 and 8.

Here, each solid electrolyte of Examples 1 and 8 was evaluated representatively, but each solid electrolyte of Examples 2 to 4 was similar to the solid electrolyte of Example 1, and each solid electrolyte of Examples 5 to 7, 9 and 10 was It is inferred that similar results to the solid electrolyte of Example 8 will be obtained.

(5) Evaluation of ionic conductivity

For each of the solid electrolytes of Examples 1 to 8 and Comparative Examples 1 and 2, all-solid-state battery samples were prepared according to the following method, and ionic conductivity was measured.

First, 0.5 g of the solid electrolyte is pelletized by applying a pressure of 1.5 ton using a circular die having a diameter of 14 pi to obtain a solid electrolyte sample in the form of a green sheet.

After heat-treating the solid electrolyte sample at 500 to 600° C., metal electrodes are formed on both sides to obtain an all-solid-state battery sample. Here, the metal electrode is formed by sputtering using InGa paste, Ag paste, etc.

These all-solid-state battery samples are measured by mounting them on a jig, regardless of the direction of + or - polarity. The EIS voltage is measured within the range of 10 ^-6 Hz with a reference frequency of 100 mV. Resistance values of each solid electrolyte of Examples 1 to 8 and Comparative Examples 1 and 2 were measured, and values obtained by converting ionic conductivity therefrom are shown in Table 3 below. In addition, resistance measurement results for each of the solid electrolytes of Examples 1 and 8 are shown in FIG. 13 .

Ionic Conductivity (S/cm) Example 1 ^2.32X10-8 Example 2 ^5.32X10-9 Example 3 ^4.23X10-9 Example 4 ^2.32X10-9 Example 5 1.50X10 ^-7 Example 6 2.40X10 ^-7 Example 7 ^2.87X10-7 Example 8 1.24X10 ^-7 Comparative Example 1 ^8.74X10-9 Comparative Example 2 7.69X10 ^-9

According to Table 3, the solid electrolyte of Example 1 is an oxide-only solid electrolyte (first type solid electrolyte) containing Li, Si, B, Zr, and P, and has an ion conductivity of 1X10 ^-8 S/cm. It has a securing effect.

In addition, according to Table 3 and FIG. 13, the solid electrolytes of Examples 5 to 8 include the glass ceramic as a main component and at the same time include a specific subcomponent (solid electrolyte of the second type), 1X10 ^-7 S / cm has the effect of securing the ionic conductivity.

(6) synthesis

Each of the solid electrolytes of Examples 1 to 5 corresponds to the above-described first solid electrolyte (an oxide containing Li, Si, B, Zr, and P). These are glass ceramics having both amorphous and crystalline characteristics, and Li ₃ PO ₄ crystalline phases of 3 to 5 nm in size exist in the amorphous structure based on the -BO-Si-OPO-Zr- network, and 1X10 ^-8 S/cm of Ionic conductivity can be secured.

In addition, each of the solid electrolytes of Examples 5 to 10 contains the above-described second solid electrolyte (an oxide containing Li, Si, B, Zr, and P as a first component; and Li, Al, or Cl as a second component). Including oxides or salts containing These are also glass ceramics having both amorphous and crystalline characteristics, and Li ₃ PO ₄ crystal phases of 3 to 5 nm in size exist in the amorphous structure based on the -BO-Si-OPO-Zr- network, depending on the second component It may have an additional crystalline phase (Li ₄ B ₇ O ₁₂ Cl, or Al ₂ O ₃ ), and ionic conductivity of 1X10 ^-7 S/cm may be secured.

All of the solid electrolytes of Examples 1 to 10 had high ionic conductivity compared to the solid electrolytes of Comparative Examples 1 and 2, which is inferred to be an effect due to Zr in particular.

Evaluation Example 2: Evaluation of all-solid-state battery

All-solid-state batteries containing the respective solid electrolytes of Examples 1 and 8 were fabricated, and their charge/discharge performance was measured.

First, 0.5 g of the solid electrolyte is pelletized by applying a pressure of 1.5 ton using a circular die having a diameter of 14 pi to obtain a solid electrolyte sample in the form of a green sheet.

Independently, 0.24 g of solid electrolyte, 0.24 g of Li ₃ V ₂ (PO ₄ ) ₃ , and 0.02 g of carbon black were mixed and pelletized by applying a pressure of 1.5 ton using a circular die. (pelletizing), and an electrode active material layer sample in the form of a green sheet is obtained. Two samples of such an electrode active material layer were prepared.

Independently of this, 0.1 g of solid electrolyte and 0.4 g of carbon black are mixed, pelletized by applying a pressure of 1.5 ton using a circular die, and a green sheet form is formed. Obtain a full-layer sample. Two such current collector layer samples were also prepared.

Current collector layer sample/electrode active material layer sample/electrolyte layer sample/electrode active material layer sample/current collector layer sample were stacked in this order and heat-treated at 500 to 600° C. to obtain all-solid-state batteries of Examples 1 and 8 respectively.

Each all-solid-state battery of Examples 1 and 8 was charged once and discharged once, and a charge/discharge graph thereof is shown in FIG. 14 . Specifically, in a state where each of the all-solid-state batteries of Examples 1 and 8 were mounted on a jig regardless of the + and - pole directions, charging was applied at a current density of 0.025 C-rate to a voltage of 2.4 V, and discharging was performed up to 0.001 V at the same current density.

According to FIG. 14, it can be seen that the all-solid-state battery of Example 1 exhibits an initial discharge capacity of 48 μAh (32.13 mAh/g) and a saturation discharge voltage of 1.5 to 1.6 V. In addition, it can be seen that the all-solid-state battery of Example 8 exhibited an initial discharge capacity of 63 µAh (40.51 mAh/g) and a saturation discharge voltage of 1.5 to 1.6 V.

Here, each all-solid-state battery of Examples 1 and 8 was evaluated representatively, but each all-solid-state battery of Examples 2 to 4 was similar to the all-solid-state battery of Example 1, and each of Examples 5 to 7, 9 and 10 It is inferred that the all-solid-state battery will obtain similar results to the all-solid-state battery of Example 8.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and it is possible to make various modifications and practice within the scope of the claims and the detailed description of the invention and the accompanying drawings, and this is also the present invention. It goes without saying that it falls within the scope of the invention.

121: positive electrode active material layer
122: negative electrode active material layer
123: solid electrolyte layer
124: insulating layer
125: entire collector
131, 132: external electrode layer
140: protective layer

Claims (20)

A solid electrolyte that is an oxide containing Li, Si, B, Zr, and P. According to claim 1,
Of 100 mol% of the total amount of Li, Si, B, Zr, and P in the solid electrolyte, Li is included in 40 mol% or more and 80 mol% or less, and Si is included in more than 0 mol% and 30 mol% or less, B is contained in more than 0 mol% to 60 mol% or less, Zr is contained in more than 0 mol% to 50 mol% or less, and P is contained in more than 0 mol% to 60 mol% or less. According to claim 1,
The solid electrolyte wherein the mole fraction of Li/(Si+B+Zr) in the solid electrolyte is 0.5 to 5. According to claim 1,
The solid electrolyte is a solid electrolyte represented by Formula 1 below:
[Formula 1]
a(Li ₂ O)·b(SiO ₂ )·c(B ₂ O ₃ )·d(P ₂ O ₅ )·e(ZrO ₂ )
In Formula 1,
a to e are real numbers representing mole fractions, 40≤a≤60, 0<b≤30, 0<c≤60, 0<d≤60, and 0<e≤50. According to claim 1,
The solid electrolyte has a softening point of 500 ° C. or more and 550 ° C. or less. According to claim 1,
The solid electrolyte is a solid electrolyte of glass or glass ceramic. According to claim 6,
The solid electrolyte is a glass ceramic solid electrolyte in which a crystal phase by Li ₃ PO ₄ appears during X-ray diffraction (XRD) analysis using Cu-Kα. According to claim 7,
The solid electrolyte is a solid electrolyte of a glass ceramic in which a Li ₃ PO ₄ crystal phase having a size of 1 nm or more to 10 nm or less in an amorphous structure is present. According to claim 1,
The solid electrolyte has an ionic conductivity of 1.0 X 10 ^-8 S/cm or more. As the first component, an oxide containing Li, Si, B, Zr, and P; and
As the second component, Li, Al, Na, Mg, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Rb, S, Y, Nb, Mo, Ag , In, Sn, Sb, Cs, Ba, Hf, Ta, W, Pb, Bi, Au, La, Nd, Eu, I, Cl, Br, or oxides or salts containing at least one element of F; A solid electrolyte containing According to claim 10,
The solid electrolyte wherein the mole fraction of Li/(Si+B+Zr) in the solid electrolyte is 0.5 to 5. According to claim 10,
The solid electrolyte is a solid electrolyte represented by Formula 2 below:
[Formula 2]
a(Li ₂ O)·b(SiO ₂ )·c(B ₂ O ₃ )·d(P ₂ O ₅ )·e(ZrO ₂ )·f(X _m Y _n )
In Formula 2,
a to f are real numbers representing mole fractions, 40≤a≤60, 0<b≤30, 0<c≤60, 0<d≤60, 0<e≤50, 0≤f≤50 ego;
X is Li, Al, or a combination thereof;
Y is Cl, O, or a combination thereof;
0<m≤5, and 0<n≤5. According to claim 10,
The solid electrolyte has a softening point of 500 ° C. or more and 550 ° C. or less. According to claim 10,
The solid electrolyte is a solid electrolyte of glass or glass ceramic. According to claim 14,
The solid electrolyte is a glass ceramic solid electrolyte in which a peak due to Li ₃ PO ₄ appears during X-ray diffraction (XRD) analysis using Cu-Kα. According to claim 15,
The solid electrolyte is a solid electrolyte of a glass ceramic in which a Li ₃ PO ₄ crystal phase having a size of 1 nm or more to 10 nm or less in an amorphous structure is present. According to claim 15,
The solid electrolyte is a glass ceramic solid electrolyte in which peaks due to Li ₄ B ₇ O ₁₂ Cl or Al ₂ O ₃ appear more during X-ray diffraction (XRD) analysis using Cu-Kα. According to claim 10,
The solid electrolyte has an ionic conductivity of 1.0 X 10 ^-7 S/cm or more. A body including a solid electrolyte layer and an anode layer and a cathode layer alternately stacked with the solid electrolyte layer interposed therebetween;
A first external electrode and a second external electrode are respectively disposed on both side surfaces of the body,
The solid electrolyte layer is an all-solid-state battery comprising the solid electrolyte of any one of claims 1 to 18. According to claim 19,
the positive electrode layer and the negative electrode layer each independently include an electrode active material layer positioned on a current collecting layer and an electrode active layer;
The current collecting layer and the electrode active material layer each independently include a solid electrolyte according to any one of claims 1 to 18 and a carbon-based conductive material;
The electrode active material layer further comprises an electrode active material all-solid-state battery.

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