Lithium ion conductor and all-solid-state battery using the same

Abstract

The lithium ion conductor according to the present disclosure contains Li, B, O, M, and X, and in an X-ray diffraction analysis spectrum using CuKα radiation, it has peaks attributable to a main crystalline phase at diffraction angles (2θ) of 24.5° to 26°, 32° to 34°, 35.5° to 36.2°, 37.5° to 38.5°, 43.5° to 45.5°, or a combination thereof. The M element is Al, Si, Ge, P, or a combination thereof, and the X element is a halogen element such as F, Cl, I, Br, or a combination thereof.

Description

[Technical Field]

[0001] The present disclosure relates to a lithium ion conductor and an all-solid-state battery including the same. [Background technology]

[0002] In recent years, the demand for smaller portable electronic devices and longer battery life has led to a demand for higher-capacity batteries. Furthermore, the widespread use of wearable electronic devices has led to a demand for battery safety. In response to these demands, active development of all-solid-state batteries using solid electrolytes instead of liquid electrolytes has been underway.

[0003] Because all-solid-state batteries do not use flammable organic solvents, it may be possible to simplify additional safety circuits, and so all-solid-state batteries are expected to be a technology that can produce safe batteries with high capacity per unit volume.

[0004] In addition, the ionic conductivity of the sulfide electrolyte (10 -2 S / cm) than the oxide electrolyte (10 -4 S / cm~10 -6 Although oxide all-solid-state batteries using sulfide electrolytes (S / cm) require a high-temperature firing process, they exhibit superior stability compared to sulfide all-solid-state batteries that use sulfide electrolytes, which react with oxygen and moisture in the air.

[0005] An oxide all-solid-state battery may be fired at a high temperature to increase ionic conductivity. However, in order to integrally stack and simultaneously co-fire the solid electrolyte and electrode layers (positive electrode layer and negative electrode layer), firing must be performed at a temperature lower than or equal to the electrode synthesis temperature in order to control the reaction between the solid electrolyte and the electrode layers and to prevent the electrode active material and solid electrolyte of the electrode layers from reacting with oxygen in the air.

[0006] [Disclosure] [Beneficial Effects] The lithium ion conductor according to the present embodiment enables a low-temperature co-firing method, which results in almost no deterioration of the electrode layer, low interfacial resistance with the electrode layer, high ionic conductivity, and improved power performance of the all-solid-state battery.

[0007] However, the various advantageous benefits and effects of the present invention are not limited to the above description, but will be more easily understood in the course of describing specific embodiments of the present invention. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing the process of transformation of a lithium ion conductor from (a) a glassy state, (b) crystal nucleation, (c) crystal growth at the center of the crystal nuclei, and (d) into a crystallized glass-ceramic through heat treatment steps.

[0009] [Figure 2] 1 is a graph showing XRD analysis results measured during the heat treatment stages of a lithium ion conductor, from (a) a glassy state, (b) crystal nucleation, (c) crystal growth at the center of the crystal nuclei, and (d) transformation into a crystallized glass-ceramic.

[0010] [Figure 3] 10A and 10B are transmission electron microscope (TEM) and ion milling cross-sectional scanning electron microscope (SEM) photographs of the crystalline state of a lithium ion conductor after a heat treatment step.

[0011] [Figure 4] FIG. 1 is a perspective view schematically illustrating an all-solid-state battery according to an embodiment.

[0012] [Figure 5] FIG. 5 is a cross-sectional view of the all-solid-state battery according to the embodiment shown in FIG.

[0013] [Figure 6] FIG. 5 is an exploded perspective view schematically illustrating a unit cell stack structure of the all-solid-state battery according to the embodiment shown in FIG. 4.

[0014] [Figure 7] 1 is a scanning electron microscope (SEM) photograph of an ion-milled cross section of a crystalline phase contained in a lithium ion conductor.

[0015] [Figure 8] 1 is a graph showing the results of XRD analysis of Example 1 before heat treatment.

[0016] [Figure 9] 1 is a graph showing the results of XRD analysis of Example 2 before heat treatment.

[0017] [Figure 10] 1 is a graph showing the results of XRD analysis of Example 3 before heat treatment.

[0018] [Figure 11] 1 is a graph showing the results of XRD analysis of Example 4 before heat treatment.

[0019] [Figure 12] 1 is a graph showing the results of XRD analysis of Example 5 before heat treatment.

[0020] [Figure 13] 1 is a graph showing the results of XRD analysis of Example 6 before heat treatment.

[0021] [Figure 14] 1 is a graph showing the results of XRD analysis of Example 7 before heat treatment.

[0022] [Figure 15] 1 is a graph showing the results of XRD analysis of Example 8 before heat treatment.

[0023] [Figure 16] 1 is a graph showing the results of XRD analysis of Example 9 before heat treatment.

[0024] [Figure 17] 1 is a graph showing the results of XRD analysis of Comparative Example 1 before heat treatment.

[0025] [Figure 18] 1 is a graph showing the results of XRD analysis of Comparative Example 2 before heat treatment.

[0026] [Figure 19] 1 is a graph showing the results of XRD analysis of Comparative Example 3 before heat treatment.

[0027] [Figure 20] 1 is a graph showing the results of XRD analysis of Comparative Example 4 before heat treatment.

[0028] [Figure 21] 1 is a graph showing the results of XRD analysis of Example 1 after heat treatment.

[0029] [Figure 22] 1 is a graph showing the results of XRD analysis of Example 2 after heat treatment.

[0030] [Figure 23] 1 is a graph showing the results of XRD analysis of Example 3 after heat treatment.

[0031] [Figure 24] 1 is a graph showing the results of XRD analysis of Example 4 after heat treatment.

[0032] [Figure 25] 1 is a graph showing the results of XRD analysis of Example 5 after heat treatment.

[0033] [Figure 26] 1 is a graph showing the results of XRD analysis of Example 6 after heat treatment.

[0034] [Figure 27]1 is a graph showing the results of XRD analysis of Example 7 after heat treatment.

[0035] [Figure 28] 1 is a graph showing the results of XRD analysis of Example 8 after heat treatment.

[0036] [Figure 29] 1 is a graph showing the results of XRD analysis of Example 9 after heat treatment.

[0037] [Figure 30] 1 is a graph showing the results of XRD analysis of Comparative Example 1 after heat treatment.

[0038] [Figure 31] 1 is a graph showing the results of XRD analysis of Comparative Example 2 after heat treatment.

[0039] [Figure 32] 1 is a graph showing the results of XRD analysis of Comparative Example 3 after heat treatment.

[0040] [Figure 33] 1 is a graph showing the results of XRD analysis of Comparative Example 4 after heat treatment.

[0041] [Figure 34] 1A shows a cross-sectional structure of an entire solid-state battery cell according to one embodiment, (B) shows a cross-sectional structure of a positive electrode, and (C) shows a cross-sectional structure of a negative electrode.

[0042] [Figure 35] 1 is a graph showing the 5-cycle charge / discharge performance of an all-solid-state battery cell fabricated using the lithium ion conductor of Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0043] In one aspect of this embodiment, a low-temperature co-firing method is possible, thereby providing an electrode layer that is almost free from deterioration, a lithium ion conductor that has low interfacial resistance with the electrode layer, and high ionic conductivity.

[0044] Another aspect of the present embodiment provides a method for preparing a lithium ion conductor.

[0045] Another aspect of the present embodiments provides an all-solid-state battery with improved power performance due to the lithium ion conductor.

[0046] However, the object to be achieved by this embodiment is not limited to the above-mentioned object, but can be expanded in various ways without departing from the technical concept of the embodiment.

[0047] A lithium ion conductor according to one embodiment contains Li, B, O, M, and X, and has peaks attributable to a main crystalline phase at diffraction angles (2θ) of 24.5° to 26°, 32° to 34°, 35.5° to 36.2°, 37.5° to 38.5°, 43.5° to 45.5°, or a combination thereof in an X-ray diffraction analysis spectrum using CuKα radiation. The M element is Al, Si, Ge, P, or a combination thereof, and the X element is a halogen element such as F, Cl, I, Br, or a combination thereof.

[0048] The predominant crystalline phase of the lithium ion conductor may comprise a compound represented by Formula 1.

[0049] [Chemical formula 1] Li4B (7-x) M x O 12 X In Chemical Formula 1, M is Al, Si, Ge, P or a combination thereof, and X is a halogen element such as F, Cl, I, Br or a combination thereof, where 0≦x<7.

[0050] The main crystalline phase is Li4B4Al3O 12 Cl, Li4B7O 12 It may include Cl, LiAlO2, LiAl5O8, or a combination thereof.

[0051] The lithium ion conductor may further include a minor crystalline phase, which may include Li2SiO3, LiBO2, LiBO3, Li3PO4, or a combination thereof.

[0052] The lithium ion conductor may include glass and crystalline phases, and the glass may include lithium oxide (LiO), silicon oxide (SiO), boron oxide (BO), phosphorus oxide (PO), germanium oxide (GeO), aluminum oxide (AlO), and lithium halides (Li-X), where X is a halogen element such as F, Cl, I, Br, or a combination thereof.

[0053] Based on 100 mol % of the entire glass, the glass may contain 35 to 55 mol % of lithium oxide (Li2O), 5 to 15 mol % of silicon oxide (SiO2), 30 to 50 mol % of boron oxide (B2O3), 0.1 to 5.0 mol % of phosphorus oxide (P2O5), 0.1 to 5.0 mol % of germanium oxide (GeO2), 0.1 to 10 mol % of aluminum oxide (Al2O3), and 0.5 to 10 mol % of lithium halide (Li-X).

[0054] The glass transition temperature (Tg) of the glass may be 380 to 450°C.

[0055] Glass crystallization temperature (T c ) may be 460 to 540°C.

[0056] The average particle size of the crystalline phase of the lithium ion conductor may be 0.5 μm to 2.0 μm.

[0057] The lithium ion conductor may further include a peak at a diffraction angle (2θ) of 21° to 23° in an X-ray diffraction analysis spectrum using CuKα radiation.

[0058] The lithium ion conductor may have a crystallinity greater than or equal to 70% as calculated by Equation 1.

[0059] [Formula 1] Crystallinity (%)=[Ic / (Ic+Ia)]×100 In Equation 1, Ic is the sum of the integral values ​​of the scattering intensity of the crystalline peaks in the X-ray diffraction analysis spectrum of the lithium ion conductor, and Ia is the sum of the integral values ​​of the scattering intensity of the amorphous halo in the X-ray diffraction analysis spectrum of the lithium ion conductor.

[0060] The apparent density of lithium ion conductors is 2.0 to 2.4 g / cm 3 It may be.

[0061] The lithium ion conductor is 1.0 × 10 -5 The polymer may have a room temperature (20° C.) ionic conductivity of greater than or equal to [Siemens / cm].

[0062] In another embodiment, a method for preparing a lithium ion conductor includes heat-treating a glass containing lithium oxide (LiO), boron oxide (BO), silicon oxide (SiO), phosphorus oxide (PO), germanium oxide (GeO), aluminum oxide (AlO), and lithium halide (Li-X) to prepare a glass-ceramic containing Li, B, M, O, and X, and having peaks attributable to a primary crystalline phase at diffraction angles (2θ) of 24.5° to 26°, 32° to 34°, 35.5° to 36.2°, 37.5° to 38.5°, 43.5° to 45.5°, or a combination thereof in an X-ray diffraction spectrum using CuKα radiation. The M element is Al, Si, Ge, P, or a combination thereof, and the X element is a halogen element such as F, Cl, I, Br, or a combination thereof.

[0063] The glass may contain, based on 100 mol % of the total glass, 35 to 55 mol % lithium oxide (Li2O), 5 to 15 mol % silicon oxide (SiO2), 30 to 50 mol % boron oxide (B2O3), 0.1 to 5.0 mol % phosphorus oxide (P2O5), 0.1 to 5.0 mol % germanium oxide (GeO2), 0.1 to 10 mol % aluminum oxide (Al2O3), and 0.5 to 10 mol % lithium halide (Li-X).

[0064] Glass particle size (D 50 ) may be 1 μm to 5 μm.

[0065] The glass transition temperature (Tg) of the glass may be 380°C to 450°C.

[0066] Glass crystallization temperature (T c ) may be 460°C to 540°C.

[0067] In another embodiment, an all-solid-state battery includes a solid electrolyte layer and a positive electrode and a negative electrode sandwiching the solid electrolyte layer, wherein one of the solid electrolyte layer, the positive electrode, the negative electrode, and combinations thereof includes a lithium ion conductor.

[0068] The lithium ion conductor is 1.0 × 10 -5 The polymer may have a room temperature (20° C.) ionic conductivity of greater than or equal to [Siemens / cm].

[0069] In another embodiment, the lithium ion conductor is Li4B (7-x) M x O 12 X, where M is Al, Si, Ge, P, or a combination thereof; X is F, Cl, I, Br, or a combination thereof; and 0≦x<7; and the minor crystalline phase comprises Li2SiO3, LiBO2, LiBO3, Li3PO4, or a combination thereof.

[0070] The main crystalline phase is Li4B4Al3O 12 Cl, Li4B7O 12 The sol-gel composition may include one or more of Cl, LiAlO2, LiAl5O8, or combinations thereof.

[0071] Another embodiment of a method for preparing a lithium ion conductor includes heat-treating a glass containing, based on 100 mol % of the total glass, 5 to 55 mol % lithium oxide (LiO), 5 to 15 mol % silicon oxide (SiO), 30 to 50 mol % boron oxide (BO), 0.1 to 5.0 mol % phosphorus oxide (PO), 0.1 to 5.0 mol % germanium oxide (GeO), 0.1 to 10 mol % aluminum oxide (AlO), and 0.5 to 10 mol % lithium halide (Li-X) at a temperature of 450°C to 500°C to form a glass-ceramic containing an amorphous phase and a crystalline phase, where X is a halogen element selected from F, Cl, I, Br, and combinations thereof.

[0072] [Mode of Invention] Various embodiments of the present invention will now be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. The drawings and descriptions are to be regarded as illustrative in nature and not restrictive. Like reference numerals refer to like elements throughout the specification. Furthermore, the accompanying drawings are provided solely to facilitate understanding of the embodiments disclosed herein and should not be construed as limiting the spirit disclosed herein. It should be understood that the present invention encompasses all modifications, equivalents, and alternatives without departing from the scope and spirit of the present invention. In addition, some components in the accompanying drawings are exaggerated, omitted, or illustrated schematically, and the size of each component does not entirely reflect the actual size.

[0073] Additionally, unless expressly stated to the contrary, the word "comprise" and variations such as "comprises" or "comprising" are understood to mean the inclusion of the stated elements, but not the exclusion of other elements.

[0074] Throughout this specification, the term "stacking direction" refers to the direction in which components are stacked in order, or the "thickness direction" perpendicular to the large surface (main surface) of a sheet-like component, which corresponds to the T-axis direction in the drawings. Additionally, the term "lateral direction" refers to a direction extending parallel to the large surface (principal surface) from the end of the sheet-like component, or a "planar direction," which corresponds to the L-axis direction in the drawings.

[0075] Various embodiments and modifications will be described in detail below with reference to the drawings.

[0076] A lithium ion conductor according to one embodiment can be used as a battery material for all-solid-state batteries and the like, for example, as a solid electrolyte, an electrode binder, or a coating agent, and includes Li, B, O, M, and X. The M element is Al, Si, Ge, P, or a combination thereof, and the X element is a halogen element, such as F, Cl, I, Br, or a combination thereof.

[0077] The lithium ion conductor according to one embodiment may include a glass (amorphous phase) and a crystalline phase. The crystalline phase may include a predominant crystalline phase or a minor crystalline phase.

[0078] The glasses correspond to precursor materials for lithium ion conductors and include lithium oxide (LiO), silicon oxide (SiO), boron oxide (BO), phosphorus oxide (PO), germanium oxide (GeO), aluminum oxide (AlO), and lithium halides (Li-X), where X is a halogen element and may be F, Cl, I, Br, or a combination thereof.

[0079] Based on 100 mol % of the entire glass, the glass may contain 35 to 55 mol % of lithium oxide (Li2O), 5 to 15 mol % of silicon oxide (SiO2), 30 to 50 mol % of boron oxide (B2O3), 0.1 to 5.0 mol % of phosphorus oxide (P2O5), 0.1 to 5.0 mol % of germanium oxide (GeO2), 0.1 to 10 mol % of aluminum oxide (Al2O3), and 0.5 to 10 mol % of lithium halide (Li-X).

[0080] When the content of phosphorus oxide (P2O5) exceeds 5 mol% based on 100 mol% of the entire glass, the -9 Excessive Li3PO4 crystals with a very low ionic conductivity of 100 s / cm are produced, reducing the ionic conductivity of the lithium ion conductor. If the phosphorus oxide (P2O5) content is less than 1 mol% based on the entire 100 mol% glass, the apparent density may decrease after heat treatment.

[0081] When the content of lithium halide (Li-X) exceeds 10 mol % based on the entire 100 mol % glass, the deliquescence and hygroscopicity of lithium halide become strong, and the ion conduction performance or heat shrinkage density characteristics of the lithium ion conductor deteriorates. When the content of lithium halide (Li-X) is less than 0.5 mol % based on the entire 100 mol % glass, the main crystalline phase (Li4B7O 12 Cl) is hardly produced, and the performance of the lithium ion conductor is significantly deteriorated.

[0082] The glass transition temperature (Tg) of the glass may be 380 to 450°C, or for example 380 to 440°C. c ) may be 460 to 540°C, or for example 460 to 500°C.

[0083] The average particle size of the crystalline phase of the lithium ion conductor can be 0.5 μm to 2.0 μm, or for example, 0.5 μm to 1.5 μm. For example, the average particle size of the crystalline phase can be obtained by taking a scanning electron microscope (SEM) image of the cross section obtained by cutting the lithium ion conductor, measuring the maximum principal axes of at least 100 crystalline phases from the image, creating a size distribution curve, and calculating the D50.

[0084] As described below, the lithium ion conductor according to one embodiment is manufactured by a method of generating crystal nuclei, growing crystals centered on the crystal nuclei, and then crystallizing them, so that a second phase may be generated in addition to the first phase, which is the main crystal. By the heat treatment, a part of the glass (amorphous phase) changes to a crystalline phase, resulting in a lithium ion conductor that is a glass ceramic containing both the glass (amorphous phase) and the crystalline phase.

[0085] The primary crystalline phase of the lithium ion conductor according to one embodiment may include a compound represented by Chemical Formula 1.

[0086] [Chemical formula 1] Li4B (7-x) M x O 12 In the formula 1, M is Al, Si, Ge, P or a combination thereof, and X is a halogen element such as F, Cl, I, Br or a combination thereof, where 0≦x<7.

[0087] In one embodiment, the predominant crystalline phase is Li4B4Al3O 12 Cl, Li4B7O 12 It may include Cl, LiAlO2, LiAl5O8, or a combination thereof.

[0088] In one embodiment, the lithium ion conductor may further include a secondary crystalline phase, which may include Li2SiO3, LiBO2, LiBO3, Li3PO4, or a combination thereof.

[0089] In an X-ray diffraction spectrum using CuKα radiation, the lithium ion conductor according to one embodiment may have peaks attributable to the main crystalline phase at diffraction angles (2θ) of 24.5° to 26°, 32° to 34°, 35.5° to 36.2°, 37.5° to 38.5°, 43.5° to 45.5°, or a combination thereof. For example, in an X-ray diffraction spectrum using CuKα radiation, the lithium ion conductor may have peaks attributable to the main crystalline phase at positions selected from a combination of four or more of the diffraction angles (2θ) of 24.5° to 26°, 32° to 34°, 35.5° to 36.2°, 37.5° to 38.5°, and 43.5° to 45.5°.

[0090] For example, in an X-ray diffraction analysis spectrum using CuKα radiation, the lithium ion conductor may have peaks attributable to the main crystalline phase at diffraction angles (2θ) of 24.5° to 26°, 32° to 34°, 35.5° to 36.2°, and 43.5° to 45.5°.

[0091] Specifically, in an X-ray diffraction analysis spectrum using CuKα radiation, the lithium ion conductor may have peaks attributable to the main crystalline phase at diffraction angles (2θ) of 24.5° to 26°, 32° to 34°, 35.5° to 36.2°, 37.5° to 38.5°, and 43.5° to 45.5°.

[0092] The lithium ion conductor according to one embodiment may further include a peak at a diffraction angle (2θ) of 21° to 23° in an X-ray diffraction analysis spectrum using CuKα radiation. Referring to Tables 1 and 3, as the SiO2 content in the glass decreases, the Al2O3 content increases relatively, and the results can be interpreted as a signal that the excess Al2O3 additionally generates a main crystalline phase containing a mixture of LiAlO2 and LiAl5O8.

[0093] The lithium ion conductor according to one embodiment may have a crystallinity greater than or equal to 70% as calculated by Equation 1.

[0094] [Formula 1] Crystallinity (%) = [Ic / (Ic+Ia)] × 100 In Equation 1, Ic is the sum of the integral values ​​of the scattering intensity of the crystalline peaks in the X-ray diffraction analysis spectrum of the lithium ion conductor, and Ia is the sum of the integral values ​​of the scattering intensity of the amorphous halo in the X-ray diffraction analysis spectrum of the lithium ion conductor.

[0095] For example, the crystallinity of lithium ion conductors can be calculated based on graphs obtained by X-ray diffraction spectroscopy. In X-ray diffraction analysis spectra, the X-ray wavelength λ with incident angle θ and lattice spacing d has the relationship 2d·sinθ=nλ, which is called the Bragg equation. Accordingly, once the incident angle is determined, the lattice spacing d can be obtained.

[0096] However, amorphous materials exhibit random atomic arrangements rather than regular ones, so they do not exhibit multiple X-ray diffraction peaks at specific wavelengths, but instead exhibit a broad halo pattern in the diffraction angle range of 15° to 35°. In the diffraction angle range of 10° to 60°, no peaks appear at specific angles, but a diffuse halo pattern appears, indicating an amorphous material with 0% crystallinity. However, the surface of lithium-ion conductors exposed to X-rays should not contain any contaminants other than organic matter. Reliable results can only be obtained when measurements are performed under conditions free of factors that affect the diffraction pattern.

[0097] In addition, if some of the precursor materials are in excess, deficient, or omitted, crystalline peaks may be observed due to unstable networks between amorphous phases, which corresponds to a defect phenomenon.

[0098] When crystals are present in a lithium ion conductor, one or more crystalline peaks are present in the corresponding measured diffraction angle range. The presence of a peak means that, in an X-ray diffraction diagram, a peak having a maximum intensity in the diffraction angle range of (2θ)=5° or higher and 50° or lower across the entire vertical axis of the XRD pattern graph can be recognized at least with the naked eye, or can be clearly distinguished from background noise and recognized using a waveform processor. In particular, the main crystalline phase peak has 80% of the peak intensity of the lowest peak.

[0099] Here, the higher the crystallinity, the smaller the halo region, and no halo region exists when the crystallinity is 100%. When crystalline and amorphous phases are mixed, the crystallinity is determined by calculating the relative area of ​​the halo region to the area of ​​the crystalline peak region in a graph of intensity and diffraction angle range.

[0100] The apparent density of the lithium ion conductor is measured after heat treatment in a specific temperature range (at or above the crystallization temperature of the glass) and is between 2.0 and 2.4 g / cm. 3 may be in the range of

[0101] The lithium ion conductor according to one embodiment has a temperature of 1.0×10 -5 Alternatively, the lithium ion conductor may have a room temperature ionic conductivity of greater than or equal to 2.0×10 [Siemens / cm]. -5 The ionic conductivity may be greater than or equal to 0.25 S / cm, but the upper limit is not particularly limited. When a lithium ion conductor satisfying this range is used, the all-solid-state battery can have excellent charge / discharge cycle characteristics and exhibit high power.

[0102] According to one embodiment of a method for preparing a lithium ion conductor, a glass containing lithium oxide (LiO), boron oxide (BO), silicon oxide (SiO), phosphorus oxide (PO), germanium oxide (GeO), aluminum oxide (AlO), and lithium halide (Li-X) is heat-treated to produce a glass-ceramic containing Li, B, M, O, and X elements. The glass-ceramic has peaks attributable to a primary crystalline phase at diffraction angles (2θ) of 24.5° to 26°, 32° to 34°, 35.5° to 36.2°, 37.5° to 38.5°, 43.5° to 45.5°, or combinations thereof in an X-ray diffraction spectrum using CuKα radiation. The M element is Al, Si, Ge, P, or a combination thereof, and the X element is a halogen element such as F, Cl, I, Br, or a combination thereof. The glass may correspond to a precursor material for a lithium ion conductor.

[0103] Before heat treatment of the glass, 35 to 55 mol % of lithium oxide (Li2O), 5 to 15 mol % of silicon oxide (SiO2), 30 to 50 mol % of boron oxide (B2O3), 0.1 to 5.0 mol % of phosphorus oxide (P2O5), 0.1 to 5.0 mol % of germanium oxide (GeO2), 0.1 to 10 mol % of aluminum oxide (Al2O3), and 0.5 to 10 mol % of lithium halide (Li-X) may be mixed with the glass, based on 100 mol % of the entire glass.

[0104] The glass has a particle size (D 50 In addition, the glass may have a particle size (D) of 0.5 to 2 μm, for example, 1 to 1.5 μm. 10 Furthermore, the glass may have a particle size (D) of 3 to 6 μm, for example 3.5 to 5 μm. 90 In addition, the glass may have a particle size (D) of 5 to 10 μm, for example 6 to 8 μm. 99 ) may be included.

[0105] The glass has a particle size of less than 1 μm (D 50 ), the characteristics of the lithium ion conductor may change due to the elution of glass components, and the glass may have a particle size (D50 ), a problem may occur in that the thickness of the solid electrolyte layer laminated between the positive electrode layer and the negative electrode layer of the final product is not properly formed.

[0106] The heat treatment of the glass may include the following steps 1 to 3 with reference to FIGS.

[0107] (Step 1: Crystal nucleation) Amorphous glass is formed at the glass transition temperature (T g When the glass is heat-treated at a temperature equal to or higher than 1000 K, the glass becomes liquid, and at the same time, lithium oxide (Li2O) and phosphorus oxide (P2O5) in the liquid phase reach the following equilibrium state to form crystal nuclei:

[0108] [Balanced formula] 4LiX + 2LiPO3 + GeO2 = 2Li3PO4 + GeX4X is a halogen element that can be F, Cl, I, Br, or a combination thereof.

[0109] The glass transition temperature (Tg) of the glass may be from 380 to 450°C, or such as from 380 to 440°C.

[0110] (Step 2: Crystal growth at the center of the crystal nucleus) By continuous heat treatment, the crystal grows while placing a small crystal nucleus at the center. For example, Li2B4O7 crystal grows to Li4B7O 12 Sequential crystallization can occur up to Cl crystal. If a large amount of aluminum oxide (Al2O3) is used, Li4B7O 12 Along with Cl crystals and LiAlO2 / LiAl5O8 composite crystals, Li4B7O 12 A polycrystalline complex of Cl / LiAlO2 / LiAl5O8 can be formed.

[0111] (Step 3: Crystallization) Glass crystallization temperature (T c ) or higher, Li4B7O 12 Cl crystal or Li4B4Al3O 12The main crystal phase, such as Cl crystal, can be completely formed. Here, in the heat treatment of the glass, the maximum temperature may be maintained for 30 to 180 minutes. If the maximum temperature is maintained within this range, the main crystal phase can be formed without deteriorating the properties of the lithium ion conductor.

[0112] Glass crystallization temperature (T c ) may be 460 to 540°C, or for example 460 to 500°C.

[0113] In one embodiment, a lithium-ion conductor can be fabricated into a glass-ceramic containing both glass and crystalline phases by heat-treating the glass within a specific temperature range. The lithium-ion conductor made from such a glass-ceramic has a specific degree of crystallinity and a room-temperature ionic conductivity that is significantly superior to that before heat-treating within the specific temperature range. Accordingly, high room-temperature ionic conductivity can be achieved even when the lithium-ion conductor is fired at a low temperature of about 500°C or lower.

[0114] An all-solid-state battery 100 according to another embodiment includes a solid electrolyte layer, and a positive electrode and a negative electrode sandwiching the solid electrolyte layer, wherein any one selected from the solid electrolyte layer, the positive electrode, the negative electrode, and combinations thereof includes a lithium ion conductor.

[0115] The lithium ion conductor contained in the all-solid-state battery according to one embodiment has a concentration of 1.0×10 -5 The polymer may have a room temperature (20° C.) ionic conductivity of greater than or equal to [Siemens / cm].

[0116] The room temperature (20°C) ionic conductivity of the lithium ion conductor contained in the all-solid-state battery can be measured by the AC impedance method. For example, the all-solid-state battery can be ion milled or polished to cut out a part of the solid electrolyte layer containing the lithium ion conductor into a flat rectangular piece. Then, electrodes made of gold (Au) are formed on both ends of the obtained piece to prepare a sample. Next, the sample is subjected to room temperature (25°C) AC impedance (frequency: 10) measurement using the impedance measurement used to calculate the ionic conductivity. +6 Hz~10 -1 Measured in terms of frequency (Hz, voltage: 100mV, 1000mV).

[0117] Fig. 4 is a perspective view schematically showing an all-solid-state battery according to another embodiment, Fig. 5 is a cross-sectional view of the all-solid-state battery according to the embodiment shown in Fig. 4, and Fig. 6 is an exploded perspective view schematically showing a unit cell stack structure of the all-solid-state battery according to the embodiment shown in Fig. 4. Hereinafter, the all-solid-state battery will be described in detail with reference to Figs. 4 to 6.

[0118] The all-solid-state battery 100 may have, for example, a substantially hexahedral shape.

[0119] In this exemplary embodiment, for convenience of explanation, in the all-solid-state battery 100, both surfaces opposing each other in the thickness direction (T-axis direction) are defined as a first surface and a second surface, and both surfaces connected to the first surface and the second surface and opposing each other in the length direction (L-axis direction) are defined as a third surface and a fourth surface. For example, the first surface and the second surface of the all-solid-state battery 100 may be the third surface and the fourth surface.

[0120] The all-solid-state battery 100 according to this embodiment includes electrode layers 120 and 140 in the stacking direction, and a solid electrolyte layer 130 adjacent to the electrode layers 120 and 140. The electrode layers 120 and 140 may include a positive electrode layer 120 and a negative electrode layer 140, and may basically include current collectors 123 and 143, and active material layers 121, 122, 141, and 142 coated on at least one surface of the current collectors 123 and 143.

[0121] The positive electrode layer 120 can be formed by coating at least one surface of a positive electrode current collector 123 with positive electrode active material layers 121 and 122, and the negative electrode layer 140 can be formed by coating at least one surface of a negative electrode current collector 143 with negative electrode active material layers 141 and 142. For example, the topmost electrode layer in the stacking direction can be formed by coating one surface of a positive electrode current collector 123 with the positive electrode active material layer 122, and the bottommost electrode layer can be formed by coating one surface of a negative electrode current collector 143 with the negative electrode active material layer 141. In addition, the electrode layers between the topmost and bottommost electrodes are formed by coating both surfaces of the positive electrode current collector 123 with the positive electrode active material layers 121 and 122, or by coating both surfaces of the negative electrode current collector 143 with the negative electrode active material layers 141 and 142.

[0122] The positive electrode active material layers 121 and 122 may contain a positive electrode active material and, if necessary, a solid electrolyte, and may further contain additives such as a binder or a conductive agent, if necessary.

[0123] For example, the positive electrode active material is not particularly limited as long as it can ensure sufficient capacity of the all-solid-state battery 100. For example, the positive electrode active material may include lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese oxide, or a combination thereof.

[0124] For example, the positive electrode active material may be a compound represented by the following chemical formula: Li a A l-b M b D2 (in the formula, 0.90≦a≦1.8, 0≦b≦0.5);Li a E l-b M b O 2-c D c (In the formula, 0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05);LiE 2-b M b O 4-c D c (In the formula, 0≦b≦0.5, 0≦c≦0.05);Lia Ni 1-b-c Co b M c D α (In the formula, 0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, 0<α≦2); Li a Ni 1-b-c Co b M c O 2-α X α (In the formula, 0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, 0<α<2); Li a Ni 1-b-c CO b M c O 2-α X2 (where 0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, 0<α<2);Li a Ni 1-b-c Mn b M c D α (In the formula, 0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, 0<α≦2); Li a Ni 1-b-c Mn b M c O 2-α X α (In the formula, 0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, 0<α<2); Li a Ni 1-b-c Mn b M c O 2-α X2 (where 0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, 0<α<2);Li a Ni b E c G d O2 (where 0.90≦a≦1.8, 0≦b≦0.9, 0≦c≦0.5, 0.001≦d≦0.1); Li a Ni b Co c Mn d GeO2 (where 0.90≦a≦1.8, 0≦b≦0.9, 0≦c≦0.5, 0≦d≦0.5, 0.001≦e≦0.1); Li a NiGbO2 (where 0.90≦a≦1.8, 0.001≦b≦0.1); Li aCoGbO2 (in the formula, 0.90≦a≦1.8, 0.001≦b≦0.1);Li a MnGbO2 (in the formula, 0.90≦a≦1.8, 0.001≦b≦0.1);Li a Mn2GbO4 (in the formula, 0.90≦a≦1.8, 0.001≦b≦0.1);QO2;QS2;LiQS2;V2O5;LiV2O2;LiRO2;LiNiVO4;Li (3-f) J2(PO4)3(0≦f≦2);Li (3-f) Fe2(PO4)3 (where 0≦f≦2); and LiFePO4, where in the above chemical formula, A is Ni, Co, or Mn, M is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, or a rare earth element, D is O, F, S, or P, E is Co or Mn, X is F, S, or P, G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, or V, Q is Ti, Mo, or Mn, R is Cr, V, Fe, Sc, or Y, and J is V, Cr, Mn, Co, Ni, or Cu.

[0125] The positive electrode active material is LiCoO2, LiMn x O 2x (wherein x=1 or 2), LiNi 1-x Mn x O 2x (0 <x<1)、LiNi 1-x-y Co x Mn y O2 (where 0≦x≦0.5 and 0≦y≦0.5), LiFePO4, TiS2, FeS2, TiS3, or FeS3.

[0126] The solid electrolyte may include a lithium ion conductor according to one embodiment. The content of the solid electrolyte may be greater than or equal to 0.1 parts by weight, greater than or equal to 1 part by weight, or greater than or equal to 10 parts by weight, and less than or equal to 80 parts by weight, less than or equal to 60 parts by weight, or less than or equal to 50 parts by weight, based on 100 parts by weight of the total amount of the positive electrode active material.

[0127] The conductive agent is not particularly limited as long as it has conductivity without causing a chemical change in the all-solid-state battery 100. For example, examples of the conductive agent include: graphite, such as natural graphite and artificial graphite; carbon-based substances, such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers, such as carbon fibers and metal fibers; fluorinated carbon; metal powders, such as aluminum and nickel powder; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; or conductive materials, such as polyphenylene derivatives.

[0128] The content of the conductive agent may be 1 to 10 parts by weight, for example, 2 to 5 parts by weight, based on 100 parts by weight of the positive electrode active material. If the content of the conductive agent is within the above range, the finally obtained electrode can have excellent conductivity properties.

[0129] A binder can be used to improve the bonding strength between the active material and the conductive agent, and can include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, or various copolymers, and the like.

[0130] The content of the binder may be 1 to 50 parts by weight, for example, 2 to 5 parts by weight, based on 100 parts by weight of the total positive electrode active material. When the content of the binder satisfies the above range, the active material layer can have high bonding strength.

[0131] As the positive electrode current collector 123, a porous material such as a mesh or a mesh-like material can be used, and a porous metal plate such as stainless steel, nickel, or aluminum, or a two-dimensional carbon-based material (for example, graphite) can be used. In addition, the positive electrode current collector 123 may be coated with an oxidation-resistant metal or alloy film to prevent oxidation.

[0132] The negative electrode active material layers 141 and 142 may contain a negative electrode active material and, if necessary, a solid electrolyte. In addition, the negative electrode active material layers 141 and 142 may further contain additives such as a binder or a conductive agent, if necessary.

[0133] The negative electrode active material can be a carbon-based material, silicon, silicon oxide, a silicon-based alloy, a silicon-carbon-based material composite, tin, a tin-based alloy, a tin-carbon composite, a metal oxide, or a combination thereof, and may contain lithium metal and / or a lithium metal alloy. The carbon-based material may include a two-dimensional carbon-based material, and as a specific example, the carbon-based material may include graphite.

[0134] The lithium metal alloy may contain lithium and a metal / semimetal that can be alloyed with lithium. For example, the metal / semimetal that can be alloyed with lithium is Si, Sn, Al, Ge, Pb, Bi, Sb, a Si-Y alloy (where Y 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, and Si is not included), a Sn-Y alloy (where Y is an alkali metal, an alkaline earth metal, a Group 13 to Group 16 element, a transition metal, or a transition metal oxide, such as lithium titanate (Li4Ti5O 12 ), a rare earth element, or a combination thereof, and Sn is not included), or M n O x (0 < x ≤ 2) may be included.

[0135] Element Y may be 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, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof.

[0136] In addition, oxides of metals / semimetals that can be alloyed with lithium may be lithium titanate, vanadium oxide, lithium vanadate, SnO2, SiO x (0 < x < 2), and the like. For example, the negative electrode active material may contain one or more elements selected from the elements of Groups 13 to 16 of the periodic table. For example, the negative electrode active material may contain one or more elements selected from the group consisting of Si, Ge, and Sn.

[0137] The carbon-based material may be crystalline carbon, amorphous carbon, or a mixture thereof. Crystalline carbon may include graphite such as irregular, plate-like, flaky, spherical, or fibrous natural graphite or artificial graphite. In addition, amorphous carbon may include soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbonization products, calcined coke, graphene, carbon black, fullerene soot, carbon nanotubes, carbon fibers, and the like.

[0138] Silicon may be Si, SiO x (0 < x < 2, for example 0.5 to 1.5), Sn, SnO2, a silicon-containing metal alloy, or a mixture thereof. The silicon-containing metal alloy may include, for example, silicon and one or more of Al, Sn, Ag, Fe, Bi, Mg, Zn, In, Ge, Pb, and Ti.

[0139] The solid electrolyte may include a lithium ion conductor according to one embodiment. The content of the solid electrolyte may be greater than or equal to 0.1 parts by weight, greater than or equal to 1 part by weight, or less than or equal to 10 parts by weight, less than or equal to 80 parts by weight, less than or equal to 60 parts by weight, or less than or equal to 50 parts by weight, based on 100 parts by weight of the total amount of the negative electrode active material.

[0140] The negative electrode active material layer may also contain the conductive agent and binder described in the positive electrode active material layer, if necessary.

[0141] The negative electrode current collector 143 may be a mesh or a mesh-like porous body, or may be a porous metal plate made of stainless steel, nickel, aluminum, etc. In addition, the negative electrode current collector 143 may be coated with an oxidation-resistant metal or alloy film to prevent oxidation.

[0142] The solid electrolyte layer 130 may be stacked and interposed between the positive electrode layer 120 and the negative electrode layer 140. Thus, the solid electrolyte layer 130 may be disposed adjacent to the positive electrode active material layers 121 and 122 of the positive electrode layer 120 and the negative electrode active material layers 141 and 142 of the negative electrode layer 140 in the stacking direction. Thus, in the all-solid-state battery 100, a plurality of positive electrode layers 120 and a plurality of negative electrode layers 140 may be alternately arranged, with a plurality of solid electrolyte layers 130 interposed and stacked therebetween. The all-solid-state battery 100 is a stacked-type all-solid-state battery 100 manufactured by alternately stacking a plurality of positive electrode layers 120 and anode layers 140 and interposing a plurality of solid electrolyte layers 130 therebetween to provide a cell stack, and then co-firing the stacked layers together.

[0143] The solid electrolyte layer 130 may include an oxide-based solid electrolyte. For example, the solid electrolyte layer 130 may include a lithium ion conductor according to one embodiment.

[0144] The oxide-based solid electrolyte may be a garnet-type, NASICON-type, LISICON-type, perovskite-type, LiPON-type, or amorphous (glass) electrolyte.

[0145] Garnet-based solid electrolytes may include lithium-lanthanum zirconium oxide (LLZO) represented by, for example, Li7La3Zr2O a La b Zr c O 12 , and NASICON-based solid electrolytes may contain Li introduced into a TiLi 12 Al 1+x Al x M 2-x (PO4)3 (LAMP) (0 < x < 2, M is Zr, Ti, or Ge) type compound, Li 1+x Al x Ti 2-x (PO4)3 (0 < x < 1) lithium-aluminum-titanium-phosphate salt (LATP), Li into which excess lithium has been introduced 1+x Al x Ge 2-x (PO4)3 (0 < x < 1), for example, lithium-aluminum-germanium-phosphate (LAGP) represented by Li 1.3 Al 0.3 Ti 1.7 (PO4)3 and / or lithium-zirconium-phosphate (LZP) of LiZr2(PO4)3.

[0146] In addition, LISICON-based solid electrolytes are xLi3AO4-(1-x)Li4BO4 (where A is P, As, or V, and B is Si, Ge, or Ti), for example, Li4Zn(GeO4)4, Li 10 GeP2O 12 (LGPO), Li 3.5 Si 0.5 P 0.5 O4, or Li 10.42 Si(Ge) 1.5 P 1.5 Cl 0.08 O 11.92A solid-solution oxide represented by, or Li 4-x M 1-y M' y S4 (where M is Si or Ge, and M' is P, Al, Zn, or Ga), for example, may include a solid-solution sulfide represented by Li2S-P2S5, Li2S-SiS2, Li2S-SiS2-P2S5, or Li2S-GeS2.

[0147] Perovskite-type solid electrolytes may include Li 3x La 2 / 3-x □ 1 / 3-2x TiO3, for example, may include lithium lanthanum titanate (LLTO) represented by Li 1 / 8 La 5 / 8 TiO3 (0 < x < 0.16, □: vacancy). LiPON-based solid electrolytes may include lithium oxy-nitride phosphate, for example, Li 2.8 PO 3.3 N 0.46 and may include.

[0148] Examples of amorphous electrolytes include Li2O-B2O3-SiO2, Li2O-B2O3-P2O5, Li3BO3-Li2SO4, and Li3BO3-Li2CO3.

[0149] The margin layer 150 may be disposed along the ends of the positive electrode layer 120 and the negative electrode layer 140. The margin layer 150 may be disposed on the solid electrolyte layer 130 and may be formed adjacent to the ends of the positive electrode active material layers 121 and 122 or the negative electrode active material layers 141 and 1,42 in the lateral direction. Accordingly, the margin layer 150 may be disposed on the same layer as the positive electrode layer 120 and the negative electrode layer 140.

[0150] The margin layer 150 may include an insulating material having an ionic conductivity of less than or equal to 1.0×10 -6 S / cm, and for example, insulating materials such as the aforementioned solid electrolyte materials or resins may be included.

[0151] For example, the insulating material may be a polyolefin, such as polyethylene or polypropylene, a polyester, such as polyethylene terephthalate (PET), a polyurethane, or a polyimide.

[0152] Additionally, margin layer 150 may include an inorganic solid electrolyte, including an oxide-based solid electrolyte, a sulfide-based solid electrolyte, or a combination thereof, as used in solid electrolyte layer 130. However, the material included in margin layer 150 is not limited thereto and may include a variety of materials.

[0153] The positive electrode layer 120, the solid electrolyte layer 130, the negative electrode layer 140, and the margin layer 150 can be stacked as described above to form a cell stack of the all-solid-state battery 100. Protective layers made of an insulating material may be formed on the upper and lower ends of the cell stack of the all-solid-state battery 100.

[0154] In addition, terminals of the positive electrode current collector 123 and the negative electrode current collector 143 are exposed on both sides of the cell stack of the all-solid-state battery 100, and the external electrodes 112 and 114 are connected to the exposed terminals and combined together. In other words, the external electrodes 112 and 114 are connected to the terminal of the positive electrode current collector 123 to form a positive electrode, and are connected to the terminal of the negative electrode current collector 143 to form a negative electrode. When the terminals of the positive electrode current collector 123 and the negative electrode current collector 143 are configured to face in opposite directions, the external electrodes 112 and 114 may also be positioned on both sides, respectively.

[0155] The outer electrodes 112 and 114 may include conductive metals and glasses.

[0156] The conductive metal may include, for example, copper (Cu), nickel (Ni), tin (Sn), palladium (Pd), platinum (Pt), gold (Au), silver (Ag), tungsten (W), titanium (Ti), lead (Pb), or alloys thereof.

[0157] The glass component included in the first and second external electrodes 112 and 114 may have a mixed oxide composition. The glass component may include, for example, silicon oxide, boron oxide, aluminum oxide, transition metal oxide, alkali metal oxide, alkaline earth metal oxide, or a combination thereof. Here, the transition metal may be selected from zinc (Zn), titanium (Ti), copper (Cu), vanadium (V), manganese (Mn), iron (Fe), or nickel (Ni), the alkali metal may be selected from lithium (Li), sodium (Na), or potassium (K), and the alkaline earth metal may be selected from magnesium (Mg), calcium (Ca), strontium (Sr), or barium (Ba).

[0158] The method for forming the first and second external electrodes 112 and 114 is not particularly limited. For example, the method may include immersing the cell stack in a conductive paste containing a conductive metal and glass, or screen printing or gravure printing the conductive paste onto the surface of the cell stack. In addition, various methods can be used for applying the conductive paste to the surface of the cell stack or for drying the conductive paste and transferring the resulting dry film to the cell stack.

[0159] According to one embodiment, even when a positive electrode, a solid electrolyte layer, and a negative electrode are stacked and simultaneously fired at a low temperature of about 500°C or lower, an all-solid-state battery can be produced in which the electrode layer is hardly deteriorated, the interfacial resistance with the electrode layer is small, the ionic conductivity of the solid electrolyte layer is high, and thus the battery has excellent power performance, for example, charge / discharge performance.

[0160] Specific examples of the present invention are presented below. However, the following examples are intended only to specifically illustrate or explain the present invention, and the scope of the present invention should not be limited thereto.

[0161] [Example] Example 1 A glass powder was prepared by mixing 43 mol% Li2O, 11 mol% SiO2, 37 mol% B2O3, 1 mol% P2O5, 3 mol% GeO2, 1 mol% Al2O3, and 4 mol% LiCl, which is a precursor material for a lithium ion conductor. Here, the glass powder had a particle size (D 50 ), glass transition temperature (T g ), and a crystallization temperature (T c )

[0162] (Examples 2 to 9 and Comparative Examples 1 to 4) The powder particle sizes (D 50 ), glass transition temperature (T g ), and crystallization temperature (T c A glass powder having the following structure was prepared.

[0163] [Table 1] [Table 1] [Table 2] [Table 2] [Experimental Example]

[0164] The glass powders of Examples 1 to 9 and Comparative Examples 1 to 4 were heat-treated at the temperatures shown in Table 4 (450°C / 475°C / 500°C) to prepare lithium ion conductors of glass ceramics containing a mixture of crystalline and amorphous phases.

[0165] FIG. 7 shows an ion-milled cross-sectional scanning electron microscope (SEM) image of a crystalline phase contained in a lithium ion conductor.

[0166] The main and sub-crystalline phases formed after the heat treatment are shown in Table 3.

[0167] Referring to Table 3, in Examples 1 to 9, Li4B7O was used as the main crystalline phase. 12Cl, LiAlO2, LiAl5O8, or a combination thereof is produced, but in Comparative Examples 1 to 4, Li4B7O is produced as the main crystalline phase. 12 No Cl, LiAlO2, LiAl5O8, or combinations thereof are produced.

[0168] [Table 3] [Table 3] The following experiments are carried out using heat-treated lithium ion conductors.

[0169] (Experimental Example 1: XRD evaluation of lithium ion conductor before and after heat treatment) The lithium ion conductor before and after the heat treatment is measured for the diffraction angle (2θ) in the X-ray diffraction analysis spectrum using CuKα radiation (XRD). The measurement is performed under the following conditions.

[0170] Energy: 100 keV Wavelength: 1.5418Å Detector: PANalytical X'Pert Pro multipurpose diffractometer with CuKα radiation Exposure time: 30 minutes Temperature conditions: Room temperature 25℃ Scattering angle: 10°~60° Regarding the lithium ion conductors of Examples 1 to 9 and Comparative Examples 1 to 4, the lithium ion conductor precursors in the glass powder state before heat treatment were measured for diffraction angle (2θ) in the X-ray diffraction analysis spectrum using CuKα radiation (XRD), and the results are shown in Figures 8 to 20.

[0171] 8 to 20, the glass powder before heat treatment is amorphous, and therefore a broad halo pattern appears within a diffraction angle range of 10° to 60°. However, in Examples 7 and 9 and Comparative Example 3, crystalline peaks may appear due to an unstable network between amorphous phases, which corresponds to a defect phenomenon.

[0172] In addition, the lithium ion conductors of Examples 1 to 9 and Comparative Examples 1 to 4 after the heat treatment were measured for diffraction angle (2θ) in X-ray diffraction analysis spectra using CuKα radiation (XRD), and the results are shown in Figures 21 to 33. Referring to Figures 21 to 33, Examples 1 to 9 have peaks attributable to the main crystalline phase at 24.5° to 26°, 32° to 34°, 35.5° to 36.2°, 37.5° to 38.5°, and 43.5° to 45.5°.

[0173] In Examples 2 to 4 (FIGS. 22 to 24), the Al2O3 content is relatively increased due to the low SiO2 content, and the excess Al2O3 additionally generates a main crystalline phase containing a mixture of LiAlO2 and LiAl5O8, which further includes a peak at a diffraction angle (2θ) of 21° to 23°.

[0174] In contrast, Comparative Examples 1 to 4 have peaks only at one or two combinations of 24.5° to 26°, 32° to 34°, 35.5° to 36.2°, 37.5° to 38.5°, and 43.5° to 45.5°.

[0175] (Experimental Example 2: Measurement of room temperature ionic conductivity and apparent density of lithium ion conductor) The glass powder is compressed into a circular pellet under a pressure of 2 tons in a 14π die, and then heat-treated at a specific temperature (450°C / 475°C / 500°C). The top and bottom surfaces of the sample are polished. The sample is then coated with electrodes and measured for room temperature ionic conductivity [S / cm]. The room temperature ionic conductivity is measured in the voltage range of 20-200 mV and 10 -6 Measured using an impedance resistor within the frequency range of Hz.

[0176] After heat treating the sample to a specific temperature (450°C / 475°C / 500°C), the lithium ion conductor is measured for apparent density, which is obtained by weighing the sample and dividing it by the volume obtained by multiplying it by the diameter and thickness.

[0177] The results are shown in Table 4.

[0178] [Table 4] [Table 4] Referring to Table 4, the lithium ion conductors of Examples 1 to 9 had a melting point of 1.0 × 10 after heat treatment up to 500 °C. -5 The lithium ion conductors of Comparative Examples 1, 2, and 4 exhibit room temperature ionic conductivity exceeding or equal to 1000 kJ / cm, and thus exhibit excellent apparent density characteristics after heat treatment. The lithium ion conductors of Comparative Examples 1, 2, and 4 have a low content of the lithium halide LiCl, and therefore exhibit Li4B7O as the main crystalline phase. 12 Since almost no Cl is produced, the lithium ion conductor of Comparative Example 3 exhibits very low room-temperature ionic conductivity. The lithium ion conductor of Comparative Example 3 exhibits extremely poor room-temperature ionic conductivity or apparent density characteristics due to the excessive content of lithium halide LiCl, which causes strong deliquescence and hygroscopicity. Additionally, the apparent density and room-temperature ionic conductivity of Examples 1 and 2 were measured after heat treatment at temperatures relatively higher than 500°C, such as 600°C and 1000°C, and the results are shown in Table 5. Referring to Table 5, the lithium ion conductors of Examples 1 and 2 exhibit insufficient apparent density characteristics and unmeasurably low room-temperature ionic conductivity when sintered at 600°C or higher instead of at low temperatures.

[0179] [Table 5] [Table 5] (Experimental Example 3: Evaluation of charge / discharge performance of all-solid-state battery cells) A 30 μm thick solid electrolyte layer is prepared containing the lithium ion conductor of Example 1. A 12 μm thick positive electrode layer is formed from a positive electrode active material containing 70 wt % LiCoO2 (LCO) and 30 wt % of the lithium ion conductor of Example 1. A 7 μm thick negative electrode layer is formed from a negative electrode active material containing 70 wt % graphite and 30 wt % of the lithium ion conductor of Example 1.

[0180] The positive electrode layer, the solid electrolyte layer, and the negative electrode layer are stacked and simultaneously co-fired at 500°C for 30 minutes under a pressure of 65.8 MPa using a hot spot to produce an all-solid-state battery cell.

[0181] Here, the cross-sectional structure of the manufactured all-solid-state battery cell (A), the cross-sectional structure of the positive electrode (B), and the cross-sectional structure of the negative electrode (C) are shown in FIG.

[0182] The all-solid-state battery cell was charged at a constant current of 0.05c up to a maximum voltage of 4.3V, and then discharged at 0.05c down to a cutoff voltage of 3.5V. This was considered as one charge-discharge cycle, and this cycle was repeated five times. The results of the characteristic experiment are shown in Figure 35.

[0183] Referring to FIG. 35, the all-solid-state battery cell exhibits a large ratio of the discharge capacity at the fifth cycle to the initial discharge capacity at the first cycle, i.e., a large capacity retention rate, and thus excellent battery cycling characteristics and excellent power performance.

[0184] While the present invention has been described in connection with what are presently considered to be working exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but rather is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0185] [Industrial Applicability] The present disclosure relates to a lithium ion conductor having not only high ionic conductivity but also low interfacial resistance with an electrode layer, and an all-solid-state battery including the same, which in turn has excellent power performance and can be used in devices and electronic devices. [Explanation of symbols]

[0186] 100: All-solid-state battery 112,114: External electrode 120: Positive electrode layer 121,122: Positive electrode active material layer 123: Positive electrode current collector 130: Solid electrolyte layer 140: Negative electrode layer 141,142:Negative electrode active material layer 143:Negative electrode current collector 150: Margin layer

Claims

1. Li element, B element, O element, M element, and X element A lithium ion conductor comprising: In an X-ray diffraction analysis spectrum using CuKα radiation, the lithium ion conductor has a peak attributable to a main crystalline phase at a diffraction angle (2θ) of 24.5° to 26°, 32° to 34°, 35.5° to 36.2°, 37.5° to 38.5°, 43.5° to 45.5°, or a combination thereof; the M element is Al, Si, Ge, P, or a combination thereof; The X element is a halogen element selected from F, Cl, I, Br, and combinations thereof. Lithium ion conductor.

2. The predominant crystalline phase of the lithium ion conductor is Chemical formula 1: [Chemical formula 1] Li ４ b （７－ｘ） M ｘ O １２ X The compound includes a compound represented by In Chemical Formula 1, M is Al, Si, Ge, P, or a combination thereof; X is a halogen element such as F, Cl, I, or Br, or a combination thereof, and 0≦x<7. The lithium ion conductor according to claim 1 .

3. The main crystalline phase is Li ４ B ４ Al ３ O １２ Cl, Li ４ B ７ O １２ Cl, LiAlO ２ , LiAl ５ O ８ , or a combination thereof The lithium ion conductor according to claim 1 .

4. Further comprising a secondary crystalline phase, The secondary crystalline phase is Li ２ SiO ３ , LiBO ２ , LiBO ３ , Li ３ P.O. ４ , or a combination thereof The lithium ion conductor according to claim 1 .

5. further comprising glass and crystalline phases; The glass contains lithium oxide (Li ２ O), silicon oxide (SiO ２ ), boron oxide (B ２ O ３ ), phosphorus oxide (P ２ O ５ ), germanium oxide (GeO ２ ), aluminum oxide (Al ２ O ３ ), and lithium halides (Li-X) The lithium ion conductor according to claim 1 .

6. Based on 100 mol% of the entire glass, 35 to 55 mol% of the lithium oxide (Li ２ O), 5 to 15 mol % of said silicon oxide (SiO ２ ), 30 to 50 mol % of the boron oxide (B ２ O ３ ), 0.1 to 5.0 mol % of the phosphorus oxide (P ２ O ５ ), 0.1 to 5.0 mol % of the germanium oxide (GeO ２ ), 0.1 to 10 mol % of said aluminum oxide (Al ２ O ３ ), and 0.5 to 10 mol % of the lithium halide (Li—X). The lithium ion conductor according to claim 5.

7. The glass transition temperature (Tg) of the glass is 380 to 450°C. The lithium ion conductor according to claim 5.

8. The crystallization temperature (T ｃ ) is 460 to 540°C The lithium ion conductor according to claim 5.

9. The average particle size of the crystalline phase of the lithium ion conductor is 0.5 μm to 2.0 μm. The lithium ion conductor according to claim 5.

10. The lithium ion conductor further includes a peak at a diffraction angle (2θ) of 21° to 23° in an X-ray diffraction analysis spectrum using CuKα radiation. The lithium ion conductor according to claim 1 .

11. The lithium ion conductor is Formula 1: [Formula 1] Crystallinity (%) = [Ic / (Ic+Ia)] x 100 having a crystallinity of greater than or equal to 70% calculated by In Formula 1, Ic is the sum of integral values ​​of scattering intensity of crystalline peaks in the X-ray diffraction analysis spectrum of the lithium ion conductor, Ia is the sum of the integral values ​​of the scattering intensity of the amorphous halo in the X-ray diffraction analysis spectrum of the lithium ion conductor. The lithium ion conductor according to claim 1 .

12. The lithium ion conductor has a density of 2.0 to 2.4 g / cm ３ has an apparent density of The lithium ion conductor according to claim 1 .

13. The lithium ion conductor is 1.0×10 －５ have a room temperature (20°C) ionic conductivity greater than or equal to [Siemens / cm] The lithium ion conductor according to claim 1 .

14. Lithium oxide (Li ２ O), boron oxide (B ２ O ３ ), silicon oxide (SiO ２ ), phosphorus oxide (P ２ O ５ ), germanium oxide (GeO ２ ), aluminum oxide (Al ２ O ３ and a lithium halide (Li-X) to prepare a glass ceramic, wherein the glass ceramic comprises Li, B, M, O, and X elements; In an X-ray diffraction analysis spectrum using CuKα radiation, the glass ceramic has a peak attributable to a main crystalline phase at a diffraction angle (2θ) of 24.5° to 26°, 32° to 34°, 35.5° to 36.2°, 37.5° to 38.5°, 43.5° to 45.5°, or a combination thereof; the M element is Al, Si, Ge, P, or a combination thereof; The X element is a halogen element, such as F, Cl, I, Br, or a combination thereof. Method for preparing lithium ion conductors.

15. The glass contains 35 to 55 mol % of the lithium oxide (Li ２ O), 5 to 15 mol % of said silicon oxide (SiO ２ ), 30 to 50 mol % of the boron oxide (B ２ O ３ ), 0.1 to 5.0 mol % of the phosphorus oxide (P ２ O ５ ), 0.1 to 5.0 mol % of the germanium oxide (GeO ２ ), 0.1 to 10 mol % of said aluminum oxide (Al ２ O ３ ), and 0.5 to 10 mol % of lithium halide (Li—X), 15. The method of claim 14.

16. The particle size of the glass (D ５０ 16. The method according to claim 14, wherein the particle size is 1 μm to 5 μm.

17. 16. The method according to claim 14 or 15, wherein the glass transition temperature (Tg) of the glass is 380 to 450°C.

18. The crystallization temperature (T ｃ 16. The method according to claim 14, wherein the heating temperature is 460 to 540°C.

19. a solid electrolyte layer, and a positive electrode and a negative electrode disposed with the solid electrolyte layer sandwiched therebetween; One of the solid electrolyte layer, the positive electrode, the negative electrode, and combinations thereof comprises the lithium ion conductor according to any one of claims 1 to 13. All-solid-state battery.

20. The lithium ion conductor is 1.0×10 －５ having a room temperature (20°C) ionic conductivity of greater than or equal to [Siemens / cm]; The all-solid-state battery according to claim 19.

21. Li ４ B （７－ｘ） M ｘ O １２ a predominant crystalline phase comprising a compound represented by X, where M is Al, Si, Ge, P, or a combination thereof, and X is F, Cl, I, Br, or a combination thereof, and 0≦x<7; and Li ２ SiO ３ , LiBO ２ , LiBO ３ , Li ３ P.O. ４ or a secondary crystalline phase containing a combination thereof A lithium ion conductor having:

22. The main crystalline phase is Li ４ B ４ Al ３ O １２ Cl, Li ４ B ７ O １２ Cl, LiAlO ２ , LiAl ５ O ８ or a combination thereof.

22. The lithium ion conductor of claim 21.

23. further comprising glass and crystalline phases; The glass contains lithium oxide (Li ２ O), silicon oxide (SiO ２ ), boron oxide (B ２ O ３ ), phosphorus oxide (P ２ O ５ ), germanium oxide (GeO ２ ), aluminum oxide (Al ２ O ３ ), and lithium halides (Li-X) 22. The lithium ion conductor of claim 21.

24. Based on 100 mol% of the entire glass, 35 to 55 mol% of the lithium oxide (Li ２ O), 5 to 15 mol % of said silicon oxide (SiO ２ ), 30 to 50 mol % of the boron oxide (B ２ O ３ ), 0.1 to 5.0 mol % of the phosphorus oxide (P ２ O ５ ), 0.1 to 5.0 mol % of the germanium oxide (GeO ２ ), 0.1 to 10 mol % of said aluminum oxide (Al ２ O ３ ), and 0.5 to 10 mol % of the lithium halide (Li—X).

24. The lithium ion conductor of claim 23.

25. The average particle size of the crystalline phase of the lithium ion conductor is 0.5 μm to 2.0 μm.

25. The lithium ion conductor of claim 24.

26. The lithium ion conductor is Formula 1: [Formula 1] Crystallinity (%) = [Ic / (Ic+Ia)] x 100 having a crystallinity of greater than or equal to 70% calculated by In Formula 1, Ic is the sum of integral values ​​of scattering intensity of crystalline peaks in the X-ray diffraction analysis spectrum of the lithium ion conductor, Ia is the sum of the integral values ​​of the scattering intensity of the amorphous halo in the X-ray diffraction analysis spectrum of the lithium ion conductor.

26. The lithium ion conductor according to any one of claims 21 to 25.

27. The lithium ion conductor is 1.0×10 －５ have a room temperature (20°C) ionic conductivity greater than or equal to [Siemens / cm] 26. The lithium ion conductor according to any one of claims 21 to 25.

28. Based on 100 mol% of the entire glass, 5 to 55 mol% of lithium oxide (Li ２ O), 5 to 15 mol % silicon oxide (SiO ２ ), 30 to 50 mol % of boron oxide (B ２ O ３ ), 0.1 to 5.0 mol % of phosphorus oxide (P ２ O ５ ), 0.1 to 5.0 mol % germanium oxide (GeO ２ ), 0.1 to 10 mol % aluminum oxide (Al ２ O ３ ), and 0.5 to 10 mol % lithium halide (Li—X), at a temperature of 450° C. to 500° C. to form a glass-ceramic comprising an amorphous phase and a crystalline phase; The element X is a halogen element such as F, Cl, I, Br, or a combination thereof. Method for preparing lithium ion conductors.

29. The particle size of the glass (D ５０ 29. The method of claim 28, wherein the thickness of the first and second electrodes is 1 μm to 5 μm.

30. 29. The method of claim 28, wherein the glass has a glass transition temperature (Tg) of 380 to 450°C.

31. The crystallization temperature (T ｃ 29. The method of claim 28, wherein the temperature is 460 to 540°C.

32. The crystalline phase is Li ４ B ４ Al ３ O １２ Cl, Li ４ B ７ O １２ Cl, LiAlO ２ , LiAl ５ O ８ or a combination thereof, 32. The method of any one of claims 28 to 31.

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