Lithium ion conductor, lithium battery including the same, and method of preparing lithium ion conductor

Abstract

Lithium ion conductors, lithium batteries including the same, and methods of making lithium ion conductors. The lithium ion conductors include: a first compound represented by Formula 1; and a second compound represented by Formula 2, wherein the lithium ion conductor has a first peak at a diffraction angle (2θ) of 23.8° to 24.5° in an X-ray diffraction spectrum, wherein Formula 1 and Formula 2 are as described herein.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2024-0178987 filed on December 4, 2024 and Korean Patent Application No. 10-2025-0186140 filed on November 28, 2025, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to lithium-ion conductors, lithium batteries including said lithium-ion conductors, and methods for preparing said lithium-ion conductors. Background Technology

[0004] Recent industrial demands require batteries with high energy density. Lithium-ion batteries possess such high energy density and are used in wireless headphones, mobile devices, and electric vehicles. Conventional lithium-ion batteries use liquid electrolytes that include flammable organic solvents, posing a risk of overheating and fire in the event of a short circuit. Considering this risk, all-solid-state lithium-ion batteries, which use solid electrolytes instead of liquid electrolytes, are gaining attention and are under development.

[0005] Compared to sulfide-based solid electrolytes, which require isolation from air, oxide-based solid electrolytes are relatively stable in air. Summary of the Invention

[0006] One aspect of this disclosure provides a novel lithium-ion conductor with excellent ionic conductivity and moisture (water) stability.

[0007] Another aspect of this disclosure provides a solid-state battery including the lithium-ion conductor.

[0008] Other aspects will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the embodiments presented in this disclosure.

[0009] According to one aspect,

[0010] Lithium-ion conductors include: a first compound represented by Formula 1; and a second compound represented by Formula 2.

[0011] The lithium-ion conductor described herein exhibits a first peak in the XRD spectrum at a diffraction angle (2θ) of approximately 23.8° to approximately 24.5°.

[0012] Formula 1

[0013] Li x B 4-y M1 3+y O12 X1 z

[0014] In Equation 1,

[0015] 3.8 ≤ x ≤ 4.2, 0 ≤ y < 4, and 0.5 ≤ z ≤ 1.2.

[0016] M1 is at least one element belonging to groups 13 to 15 of the periodic table, and

[0017] X1 is at least one halogen element.

[0018] Formula 2

[0019] Li x B7O 12 X2 z

[0020] In Equation 2,

[0021] 3.8 ≤ x ≤ 4.2 and 0.5 ≤ z ≤ 1.2, and

[0022] X2 is at least one halogen element.

[0023] According to another perspective, a lithium battery includes: a positive electrode; a negative electrode; and...

[0024] A solid electrolyte layer is disposed between the positive electrode and the negative electrode.

[0025] At least one of the positive electrode, the negative electrode, and the solid electrolyte layer includes the lithium-ion conductor.

[0026] According to another method, the preparation of lithium-ion conductors includes:

[0027] Precursor glasses containing lithium, boron, M1 elements and halogen elements were prepared.

[0028] The precursor glass is annealed to prepare an intermediate; and

[0029] The intermediate is subjected to pressure and heat treatment to prepare a lithium-ion conductor comprising a crystalline phase.

[0030] The lithium-ion conductor comprises: a first compound represented by Formula 1; and a second compound represented by Formula 2.

[0031] The lithium-ion conductor described herein exhibits a first peak in the XRD spectrum at a diffraction angle (2θ) of approximately 23.8° to approximately 24.5°.

[0032] Formula 1

[0033] Li x B 4-y M1 3+yO 12 X1 z

[0034] In Equation 1,

[0035] 3.8 ≤ x ≤ 4.2, 0 ≤ y < 4, and 0.5 ≤ z ≤ 1.2.

[0036] M1 is at least one element belonging to groups 13 to 15 of the periodic table, and

[0037] X1 is at least one halogen element.

[0038] Formula 2

[0039] Li x B7O 12 X2 z

[0040] In Equation 2,

[0041] 3.8 ≤ x ≤ 4.2 and 0.5 ≤ z ≤ 1.2, and

[0042] X2 is at least one halogen element. Attached Figure Description

[0043] The above and other aspects, features, and advantages of some embodiments of this disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, wherein:

[0044] Figure 1 These are a series of X-ray diffraction patterns of the lithium-ion conductors prepared in Example 1 and Comparative Examples 1 and 2;

[0045] Figure 2 yes Figure 1 Partial unfolded XRD pattern;

[0046] Figure 3 This is a diagram showing the lattice parameters of the lithium-ion conductors prepared in Examples 1 to 5 and Comparative Examples 1 to 2;

[0047] Figure 4 This is a graph showing the results of measuring the phase fraction of the lithium-ion conductors prepared in Examples 1 to 5 and Comparative Examples 1 to 2;

[0048] Figure 5 This is a schematic cross-sectional view illustrating the structure of a solid-state battery according to an embodiment;

[0049] Figure 6 This is a schematic cross-sectional view illustrating the structure of a solid-state battery according to an embodiment; and

[0050] Figure 7 This is a schematic cross-sectional view illustrating the structure of a solid-state battery according to an embodiment.

[0051] Figure 8 This is a schematic cross-sectional view illustrating the structure of a stacked ceramic battery according to one embodiment;

[0052] Figure 9 This is a schematic cross-sectional view illustrating the structure of a stacked ceramic battery according to another embodiment; and

[0053] Figure 10 This is a schematic cross-sectional view illustrating the structure of a stacked ceramic battery according to another embodiment. Detailed Implementation

[0054] Embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings, wherein the same reference numerals always denote the same elements. In this respect, embodiments may take different forms and should not be construed as limited to the description set forth herein. Rather, these embodiments are provided so that this disclosure is thorough and complete, and are provided to fully convey the scope of the inventive concept to those skilled in the art. The same reference numerals denote the same components. Therefore, embodiments are described below only by reference to the accompanying drawings to explain aspects.

[0055] When a component is described as being "on" or "above" another component, it can be understood that it can be located directly on the other component, or that another component can be inserted between them. Conversely, when a component is described as being "directly" on another component, no component is inserted between them.

[0056] While the terms “first,” “second,” “third,” etc., may be used herein to describe various components, ingredients, regions, layers, and / or areas, these components, ingredients, regions, layers, and / or areas should not be limited by these terms. These terms are used only to distinguish one component, ingredient, region, layer, or area from another. Therefore, without departing from the scope of this disclosure, the first component, ingredient, region, layer, or area described below may be referred to as the second component, ingredient, region, layer, or area.

[0057] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to limit the inventive concept. As used herein, the singular form is intended to include the plural form, including "at least one," unless the context clearly specifies otherwise. "At least one" should not be construed as limited to the singular. The terms "comprising" and / or "including" as used in the detailed description specify the presence of the stated features, regions, integrals, steps, operations, components, and / or ingredients, but do not exclude the presence or addition of one or more other features, regions, integrals, steps, operations, components, ingredients, and / or collections thereof.

[0058] Unless otherwise defined, all terms used in this disclosure (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Furthermore, terms defined in commonly used dictionaries shall be interpreted as having the meaning consistent with their meaning in the context of this disclosure and the relevant field, and shall not be interpreted in an idealized or overly formal sense.

[0059] Exemplary embodiments are described in this disclosure with reference to cross-sectional views that serve as schematic representations of idealized embodiments. Similarly, variations in the shape shown must be expected, for example, as a result of manufacturing techniques and / or tolerances. Therefore, the embodiments described in this disclosure should not be construed as limited to the specific shapes of the regions shown in this disclosure, and should include, for example, deviations in shape due to manufacturing processes. For example, regions shown or described as flat may typically have rough and / or non-linear characteristics. Furthermore, sharply shown corners may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to represent the precise shapes of the regions and are not intended to limit the scope of the claims.

[0060] "Group" refers to the group in the periodic table of elements according to the classification system of Groups 1 to 18 of the International Union of Pure and Applied Chemistry (IUPAC).

[0061] As used herein, “particle diameter” refers to the average diameter when the particle is spherical, and the average major axis length when the particle is non-spherical. Particle diameter can be measured using a particle size analyzer (PSA). “Particle diameter” is, for example, the average particle diameter. “Average particle diameter” is, for example, the median particle diameter D50.

[0062] D50 is the size of the particles corresponding to 50% of the cumulative volume, calculated from the side of the particles with the smallest particle size in the particle size distribution measured by laser diffraction.

[0063] D90 is the size of the particles corresponding to 90% of the cumulative volume, calculated from the side of the particles with the smallest particle size in the particle size distribution measured by laser diffraction.

[0064] D10 is the size of 10% of the cumulative volume of particles, calculated from the side of particles with smaller particle sizes in the particle size distribution measured by laser diffraction.

[0065] As used in this article, "lithium-ion conductor" refers to a conductor with a conductivity of 1 × 10⁻⁶ ppm at room temperature and normal pressure. -7 Materials with lithium-ion conductivity of Siemens / cm (S / cm) or greater.

[0066] As used herein, “metal” includes both in the elemental (elemental) state and in the ionic state: metals and metalloids such as silicon and germanium.

[0067] As used herein, “alloy” means a metallic material comprising two or more elements, at least one of which is a metal as defined herein.

[0068] As used in this article, “electrode active material” refers to an electrode material that can undergo lithiation and delithiation.

[0069] In this article, "positive electrode active material" refers to a positive electrode material that can undergo lithiation and delithiation.

[0070] In this article, "negative electrode active material" refers to a negative electrode material that can undergo lithiation and delithiation.

[0071] As used in this article, "lithiation" refers to the process of adding lithium to the electrode active material.

[0072] As used in this article, “delithiation” refers to the process of removing lithium from the electrode active material.

[0073] As used in this article, “charging” refers to the process of providing electrochemical energy to a battery.

[0074] As used in this article, “discharging” refers to the process of removing electrochemical energy from a battery.

[0075] As used in this article, "positive electrode" and "positive electrode" refer to the electrode that undergoes electrochemical reduction and lithiation during the discharge process.

[0076] As used in this article, "negative electrode" and "negative electrode" refer to the electrode that undergoes electrochemical oxidation and delithiation during the discharge process.

[0077] Although specific embodiments have been described, the applicant or those skilled in the art will recognize alternatives, modifications, variations, improvements, and substantial equivalents that are not currently foreseen or unforeseen. Therefore, the appended claims, as filed and as amended, are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0078] Solid-state batteries are manufactured using oxide-based solid electrolytes as lithium-ion conductors through sintering. Sintering at relatively low temperatures is necessary to prevent or minimize side reactions between the oxide-based solid electrolyte and the electrode active materials during the sintering process. While glass solid electrolytes may be more suitable for solid-state battery manufacturing due to their relatively low sintering temperature, they also present technical drawbacks. For example, glass solid electrolytes exhibit relatively low ionic conductivity and relatively low moisture stability compared to crystalline solid electrolytes. Therefore, a lithium-ion conductor with excellent ionic conductivity and moisture stability is required while sintering at low temperatures.

[0079] The lithium-ion conductor and the all-solid-state battery including the thereof will be described in more detail below according to embodiments.

[0080] Lithium-ion conductors

[0081] According to an embodiment, the lithium-ion conductor comprises a first compound represented by Formula 1; and a second compound represented by Formula 2, wherein the lithium-ion conductor has a first peak in an X-ray diffraction (XRD) spectrum at a diffraction angle (2θ) of 23.8° to 24.5°.

[0082] Formula 1

[0083] Li x B 4-y M1 3+y O 12 X1 z

[0084] In Equation 1,

[0085] 3.8 ≤ x ≤ 4.2, 0 ≤ y < 4, and 0.5 ≤ z ≤ 1.2.

[0086] M1 is at least one element belonging to groups 13 to 15 of the periodic table, and

[0087] X1 is at least one halogen element.

[0088] Formula 2

[0089] Li x B7O 12 X2 z

[0090] In Equation 2,

[0091] 3.8 ≤ x ≤ 4.2 and 0.5 ≤ z ≤ 1.2, and

[0092] X2 is at least one halogen element.

[0093] In Equation 1, for example, 3.9 ≤ x ≤ 4.1, 0 ≤ y ≤ 3, and 0.5 ≤ z ≤ 1.2. In Equation 1, for example, 3.9 ≤ x ≤ 4.1, 0 ≤ y ≤ 2, and 0.5 ≤ z ≤ 1.2. In Equation 1, for example, 3.9 ≤ x ≤ 4.1, 0 ≤ y ≤ 1, and 0.6 ≤ z ≤ 1.1. In Equation 1, for example, 3.9 ≤ x ≤ 4.1, 0 ≤ y ≤ 1, and 0.7 ≤ z ≤ 1.1. In Equation 1, for example, 3.9 ≤ x ≤ 4.1, 0 ≤ y ≤ 1, and 0.8 ≤ z ≤ 1.1. In Equation 1, for example, 3.9 ≤ x ≤ 4.1, 0 ≤ y ≤ 1, and 0.9 ≤ z ≤ 1.1. In Equation 1, for example, 3.95 ≤ x ≤ 4.05, 0 ≤ y ≤ 0.5, and 0.95 ≤ z ≤ 1.05.

[0094] In Equation 2, for example, 3.9 ≤ x ≤ 4.1 and 0.5 ≤ z ≤ 1.2. In Equation 2, for example, 3.9 ≤ x ≤ 4.1 and 0.6 ≤ z ≤ 1.2. In Equation 2, for example, 3.9 ≤ x ≤ 4.1 and 0.6 ≤ z ≤ 1.1. In Equation 2, for example, 3.9 ≤ x ≤ 4.1 and 0.7 ≤ z ≤ 1.1. In Equation 2, for example, 3.9 ≤ x ≤ 4.1 and 0.8 ≤ z ≤ 1.1. In Equation 2, for example, 3.9 ≤ x ≤ 4.1 and 0.9 ≤ z ≤ 1.1. In Equation 2, for example, 3.95 ≤ x ≤ 4.05 and 0.95 ≤ z ≤ 1.05.

[0095] In the XRD spectrum of a lithium-ion conductor, the position of the first peak can be, for example, a diffraction angle (2θ) of about 23.80° to about 24.30°, a diffraction angle (2θ) of about 23.80° to about 24.10°, or a diffraction angle (2θ) of about 23.83° to about 24.00°. The lithium-ion conductor may also have a second peak in the XRD spectrum, the second peak having a diffraction angle smaller than that of the first peak.

[0096] The lithium-ion conductor may include a first compound and a second compound, and may also include an additional (third compound) compound exhibiting a peak different from that of the first and second compounds (i.e., a first peak), thereby providing improved ionic conductivity to the lithium-ion conductor. The lattice of the additional compound exhibiting the first peak may have a reduced lattice parameter compared to the lattice of the first compound, thereby providing a buffering effect between the lattices of the first compound. Due to this buffering effect, the energy barrier for lithium-ion conduction within the crystal structure of the lithium-ion conductor can be reduced. As a result, the lithium-ion conductor may have improved ionic conductivity. Furthermore, the internal resistance of an all-solid-state battery including such a lithium-ion conductor can be reduced, thereby improving the charge / discharge characteristics of the all-solid-state battery.

[0097] Because the lithium-ion conductor includes additional compounds exhibiting a first peak and structural stability, the content of amorphous phases, which are relatively highly reactive with moisture, can be significantly reduced, or these phases can be absent altogether. As a result, the lithium-ion conductor can exhibit improved moisture stability. Moisture-induced degradation in all-solid-state batteries including such lithium-ion conductors can be suppressed.

[0098] Reference Figure 1 and 2 The lithium-ion conductor may have a first peak at a diffraction angle (2θ) of 23.8° to 24.5° and a second peak at a diffraction angle (2θ) of 23.8 ± 0.3° in the XRD spectrum, originating from the first compound. The ratio (Ic / Ia) of the intensity of the first peak to the intensity Ia of the second peak (i.e., the first peak intensity ratio (Ic / Ia)) may be, for example, 0.05 or greater, 0.07 or greater, or 0.1 or greater. The first peak intensity ratio (Ic / Ia) may be, for example, about 0.05 to about 0.5, about 0.07 to about 0.4, or about 0.1 to about 0.3. Without further limiting the lithium-ion conductor, it is believed that because the lithium-ion conductor has a first peak intensity ratio (Ic / Ia) in this range, it can provide further improved ionic conductivity and moisture stability.

[0099] Reference Figure 1 and 2The lithium-ion conductor may exhibit a first peak at a diffraction angle (2θ) of 23.8° to 24.5° and a third peak at a diffraction angle (2θ) of 25.3 ± 0.5° in the XRD spectrum, originating from the second compound. The ratio of the intensity Ic of the first peak to the intensity Ib of the third peak (Ic / Ib) (i.e., the second peak intensity ratio (Ic / Ib)) may be, for example, 0.1 or greater, 0.3 or greater, 0.5 or greater, 0.8 or greater, 1 or greater, 2 or greater, or 3 or greater. The second peak intensity ratio (Ic / Ib) may be, for example, about 0.1 to about 100, about 0.3 to about 100, about 0.5 to about 100, about 0.8 to about 100, about 1 to about 100, about 2 to about 20, or about 3 to about 10. Because the lithium-ion conductor has a second peak intensity ratio (Ic / Ib) within this range, further improved ionic conductivity and moisture stability can be provided.

[0100] The lithium-ion conductor exhibits a first peak in its XRD spectrum at a diffraction angle (2θ) between 23.8° and 24.5°. This first peak may originate from a third compound. The third compound may possess, for example, different physical properties and / or chemical composition from, the first and second compounds. The third compound may also have, for example, different lattice parameters from, the first and second compounds.

[0101] The lithium-ion conductor includes a first compound and a third compound, and both compounds may have a cubic structure. Because the first and third compounds have a cubic structure, their a-axis, b-axis, and c-axis may have the same lattice parameters. The a-axis lattice parameter of the third compound may be, for example, about 12.580 Å to about 12.940 Å, about 12.580 Å to about 12.900 Å, about 12.580 Å to about 12.870 Å, or about 12.580 Å to about 12.850 Å. Because the third compound has an a-axis lattice parameter within this range, the ionic conductivity and moisture stability of the lithium-ion conductor including the third compound can be improved.

[0102] The a-axis lattice parameter of the third compound can be smaller than that of the first compound. The a-axis lattice parameter of the first compound can be, for example, 12.910 Å or greater, or 12.945 Å or greater. Because the a-axis lattice parameter of the third compound is smaller than that of the first compound, a buffering effect can be provided between the a-axis lattice parameters. For example, since the positions of the atoms arranged in the cubic crystal structure in the lithium-ion conductor comprising the first and third compounds are partially altered, the energy barrier for lithium-ion conduction in the lithium-ion conductor can be reduced. As a result, the lithium-ion conductivity of the lithium-ion conductor can be improved.

[0103] The lithium-ion conductor includes, for example, a first phase comprising a first compound, a second phase comprising a second compound, and a third phase comprising a third compound, wherein the phase fraction of the third phase relative to the total weight of the first, second, and third phases may be 3 wt% or more, 7 wt% or more, 9 wt% or more, 12 wt% or more, or 15 wt% or more. The phase fraction of the third phase in the lithium-ion conductor relative to the total weight of the first, second, and third phases may be, for example, about 3 wt% to about 40 wt%, about 7 wt% to about 40 wt%, about 9 wt% to about 35 wt%, about 12 wt% to about 30 wt%, or about 15 wt% to about 30 wt%. Without further limiting the lithium-ion conductor, it is believed that because the lithium-ion conductor has a third phase fraction within this range, it can have improved ionic conductivity and moisture stability.

[0104] Lithium-ion conductors may include, for example, a first phase and a third phase, wherein the first phase includes a first compound represented by Formula 1, and the third phase may include a third compound comprising boron (B), at least one element belonging to groups 13 to 15 of the periodic table (M1), and oxygen (O). The third compound is distinct from the first compound. The third phase may include a third compound comprising, for example, lithium (Li), boron (B), at least one element belonging to groups 13 to 15 of the periodic table (M1), oxygen (O), and a halogen. At least one element belonging to groups 13 to 15 of the periodic table (M1) may be, for example, Al, Si, P, Ga, Ge, As, In, Sn, Sb, Tl, Pb, Bi, or combinations thereof. Halogens may be, for example, F, Cl, Br, I, or combinations thereof. Lattice parameters and phase fractions may be calculated using Rietveld refinement with information about, for example, all peaks obtained from XRD spectra.

[0105] Lithium-ion conductors include, for example, a first compound and a third compound, wherein the third compound may have a boron content (CB) greater than that of the first compound relative to the content (CM1) of at least one element belonging to groups 13 to 15 of the periodic table. For example, the boron content (C3) in the third compound... B The content of at least one element belonging to groups 13 to 15 of the periodic table (C3) M1 The content of (C3) is higher than that of (C3). B / C3 M1 The boron content can be greater than that in the first compound (C1). B The abundance (C1) of at least one element belonging to groups 13 to 15 of the periodic table. M1 The ratio of (C1) B / C1 M1 That is, the B / M1 ratio in the third phase can be greater than the B / M1 ratio in the first phase. The content ratio can be a molar ratio. For example, the ratio in the third phase (C3) B / C3M1 ) The ratio (C1 B / C1 M1 )(i.e., (C3 B / C3 M1 ):(C1 B / C1 M1 )) may be, for example, 1.01:1.00 or greater, 1.05:1.00 or greater, 1.10:1.00 or greater, 1.20:1.00 or greater, or 1.50:1.00 or greater.

[0106] The lithium ion conductor may include, for example, a first phase and a third phase, wherein the third phase may include a third compound. With respect to 1 mole of the third compound, the third compound may include, for example, 3 to 5 moles of lithium; greater than 4 moles to less than 7 moles of boron; greater than 0 to less than 3 moles of at least one element belonging to Groups 13 to 15 of the periodic table; 11 to 13 moles of oxygen; and 0.5 to 1.2 moles of a halogen element. With respect to 1 mole of the third compound, the third compound may include, for example, 3.5 to 4.5 moles of lithium; greater than 4 moles to less than 6 moles of boron; greater than 1 mole to less than 3 moles of at least one element belonging to Groups 13 to 15 of the periodic table; 11.5 to 12.5 moles of oxygen; and 0.7 to 1.1 moles of a halogen element. With respect to 1 mole of the third compound, the third compound may include, for example, 3.7 to 4.3 moles of lithium; greater than 4 moles to less than 5 moles of boron; greater than 2 moles to less than 3 moles of at least one element belonging to Groups 13 to 15 of the periodic table; 11.7 to 12.3 moles of oxygen; and 0.8 to 1.05 moles of a halogen element. With respect to 1 mole of the third compound, the third compound may include, for example, 3.9 to 4.1 moles of lithium; greater than 4 moles to less than 4.5 moles of boron; 2.5 moles to less than 3 moles of at least one element belonging to Groups 13 to 15 of the periodic table; 11.9 to 12.1 moles of oxygen; and 0.9 to 1.01 moles of a halogen element.

[0107] The third compound may be, for example, a compound represented by Formula 3:

[0108] Formula 3

[0109] Li p B q M1 r O s X3 t

[0110] wherein, in Formula 3,

[0111] 3 ≤ p ≤ 5, 4 < q < 7, 0 < r < 3, 11 ≤ s ≤ 13, and 0.5 ≤ t ≤ 1.2,

[0112] M1 is at least one element belonging to Groups 13 to 15 of the periodic table, and

[0113] X3 is at least one halogen element.

[0114] In Formula 3, for example, 3.5 ≤ p ≤ 4.5, 4 < q ≤ 6, 1 ≤ r < 3, 11.5 ≤ s ≤ 12.5, and 0.7 ≤ t ≤ 1.1. In Formula 3, for example, 3.7 ≤ p ≤ 4.3, 4 < q ≤ 5, 2 ≤ r < 3, 11.7 ≤ s ≤ 12.3, and 0.8 ≤ t ≤ 1.05. In Formula 3, for example, 3.9 ≤ p ≤ 4.1, 4 < q ≤ 4.5, 2.5 ≤ r < 3, 11.9 ≤ s ≤ 12.1, and 0.9 ≤ t ≤ 1.01. In Formula 3, at least one element (M1) belonging to Groups 13 to 15 of the periodic table can be, for example, Al, Si, P, Ga, Ge, As, In, Sn, Sb, Tl, Pb, Bi, or a combination thereof. In Formula 3, the halogen can be, for example, F, Cl, Br, I, or a combination thereof.

[0115] The third compound can include, for example, compounds represented by Formulas 3a to 3e:

[0116] Formula 3a; Li p B q Al r O s Cl t

[0117] Formula 3b; Li p B q Ga r O s Cl t

[0118] Formula 3c; Li p B q Si r O s Cl t

[0119] Formula 3d; Li p B q Ge r O s Cl t

[0120] Formula 3e; Li p B q P r O s Cl t

[0121] In Formulas 3a to 3e; 3 ≤ p ≤ 5, 4 < q < 7, 0 < r < 3, 11 ≤ s ≤ 13, and 0.6 ≤ t ≤ 1.2. In Formulas 3a to 3e, for example, 3.5 ≤ p ≤ 4.5, 4 < q ≤ 6, 1 ≤ r < 3, 11.5 ≤ s ≤ 12.5, and 0.7 ≤ t ≤ 1.1. In Formulas 3a to 3e, for example, 3.7 ≤ p ≤ 4.3, 4 < q ≤ 5, 2 ≤ r < 3, 11.7 ≤ s ≤ 12.3, and 0.8 ≤ t ≤ 1.05. In Formulas 3a to 3e, for example, 3.9 ≤ p ≤ 4.1, 4 < q ≤ 4.5, 2.5 ≤ r < 3, 11.9 ≤ s ≤ 12.1, and 0.9 ≤ t ≤ 1.01.

[0122] The third compound may include, for example, compounds represented by Formulas 3f to 3j:

[0123] Formula 3f; Li4B q Al r O 12 Cl

[0124] Formula 3g; Li4B q Ga r O 12 Cl

[0125] Formula 3h; Li4B q Si r O 12 Cl

[0126] Formula 3i; Li4B q Ge r O 12 Cl

[0127] Formula 3j; Li4B q P r O 12 Cl

[0128] In Formulas 3f to 3j, 4 < q < 7 and 0 < r < 3. In Formulas 3f to 3j, for example, 4 < q ≤ 6 and 1 ≤ r < 3. In Formulas 3f to 3j, for example, 4 < q ≤ 5 and 2 ≤ r < 3. In Formulas 3f to 3j, for example, 4 < q ≤ 4.5 and 2.5 ≤ r < 3.

[0129] The lithium ion conductor includes a first phase, a second phase, and a third phase, where the first phase includes a first compound, the second phase includes a second compound, and the third phase includes a third compound.

[0130] The first compound may be represented, for example, by Formula 4, and the second compound may be represented, for example, by Formula 5:

[0131] Formula 4

[0132] Li x B 4-y M23+y O 12 X4 z

[0133] In Equation 4,

[0134] 3.9≤x≤4.1, 0≤y<3 and 0.9≤z≤1.1,

[0135] M2 is Al, Ga, Si, Ge, P, or a combination thereof, and

[0136] X4 is F, Cl, Br, I, or a combination thereof.

[0137] Formula 5

[0138] Li x B7O 12 X5 z

[0139] In Equation 5,

[0140] 3.9≤x≤4.1 and 0.9≤z≤1.1, and

[0141] X5 is F, Cl, Br, I, or a combination thereof.

[0142] The first compound can be represented, for example, by formula 6, and the second compound can be represented, for example, by formula 7:

[0143] Formula 6

[0144] Li x B4M33O 12 Cl z

[0145] In Equation 6,

[0146] 3.9 ≤ x ≤ 4.1 and 0.7 ≤ z ≤ 1.1, and

[0147] M3 is Al, Ga, Si, Ge, P, or a combination thereof.

[0148] Formula 7

[0149] Li x B7O 12 Cl z

[0150] In Equation 7,

[0151] 3.9≤x≤4.1 and 0.7≤z≤1.1.

[0152] The first compound may include, for example, Li4B4Al3O 12 Cl, Li4B4Ga3O 12 Cl, Li4B4Si3O 12Cl、Li4B4G e3 O 12 Cl, Li4B4P3O 12 Cl or combinations thereof. The second compound may include, for example, Li₄B₇O₂. 12 Cl.

[0153] In addition to the first, second, and third phases, lithium-ion conductors may further include, for example, an amorphous phase, a glassy phase, or a combination thereof. Lithium-ion conductors are not further limited, as it is believed that because they further include an amorphous phase, a glassy phase, or a combination thereof, for example, the sintering temperature of lithium-ion conductors can be more easily reduced.

[0154] Relative to the total weight of the first, second, and third phases and the amorphous phases included in the lithium-ion conductor, the phase fraction of the amorphous phase included in the lithium-ion conductor can be 2% by weight or less, 1% by weight or less, or 0.1% by weight or less. Without further limiting the lithium-ion conductor, it is assumed that because the lithium-ion conductor has a low amorphous phase fraction, the ionic conductivity and / or moisture stability of the lithium-ion conductor can be further improved.

[0155] Relative to the total weight of the first, second, third, and glass phases included in the lithium-ion conductor, the phase fraction of the glass phase included in the lithium-ion conductor can be 2% by weight or less, 1% by weight or less, or 0.1% by weight or less. Without further limiting the lithium-ion conductor, it is believed that because the lithium-ion conductor has a low glass phase fraction, the ionic conductivity and / or moisture stability of the lithium-ion conductor can be further improved.

[0156] Relative to the total weight of the first, second, third, amorphous, and glassy phases included in a lithium-ion conductor, the phase fraction of the amorphous and glassy phases in the lithium-ion conductor can be 2% by weight or less, 1% by weight or less, or 0.1% by weight or less. Without further limiting the lithium-ion conductor, it is assumed that because of the low phase fraction of the amorphous and glassy phases, the ionic conductivity and / or moisture stability of the lithium-ion conductor can be further improved.

[0157] Alternatively, lithium-ion conductors may substantially exclude, for example, amorphous phases, glassy phases, or combinations thereof. For instance, one or more amorphous or glassy phases may not be detected in the XRD spectrum of a lithium-ion conductor.

[0158] Lithium-ion conductors can exhibit 3.7 × 10⁻⁶ Ω·cm at 20 °C and 1 atm. -6 Siemens / cm (S / cm) or larger, 4.0 × 10 -6 S / cm or greater, 5.0 × 10 -6 S / cm or greater, or 5.5 × 10 -6An ionic conductivity of S / cm or greater is not considered a further limitation on lithium-ion conductors, as it is believed that such ionic conductivity can improve the charge / discharge characteristics of all-solid-state batteries incorporating lithium-ion conductors. The ionic conductivity of lithium-ion conductors can be measured, for example, through impedance analysis.

[0159] Lithium-ion conductors can have a moisture absorption rate (moisture absorption rate) of 30% or less, or 25% or less, corresponding to the rate of mass increase due to moisture absorption after being placed at 70% relative humidity for 7 days. Without further limiting the lithium-ion conductor, it is believed that because of this low moisture absorption rate, improved moisture stability can be provided. Therefore, moisture-induced degradation in all-solid-state batteries including lithium-ion conductors can be more effectively suppressed. Furthermore, since the need for moisture barrier during the manufacture of lithium-ion conductors is reduced, manufacturing costs can be lowered, and lithium-ion conductors can be manufactured more easily under various conditions.

[0160] According to an embodiment, in the XRD spectrum, the lithium-ion conductor may have a first peak and a second peak at a diffraction angle (2θ) of 23.5° to 24.5°, and may have a third peak at a diffraction angle (2θ) of 25.3 ± 0.5°. Specifically, the lithium-ion conductor may have a first peak at a diffraction angle (2θ) of 23.8° to 24.5°, a second peak at a diffraction angle (2θ) smaller than the first peak, and a third peak at a diffraction angle (2θ) of 25.3 ± 0.5°. The second peak may appear at a diffraction angle (2θ) of 23.8 ± 0.3°.

[0161] Methods for preparing lithium-ion conductors

[0162] According to another embodiment, a method for preparing a lithium-ion conductor includes the following steps: preparing a precursor glass comprising lithium, boron, M1 elements and halogen elements; annealing the precursor glass to prepare an intermediate; and pressurizing and heat-treating the intermediate to prepare a lithium-ion conductor comprising a crystalline phase. The lithium-ion conductor prepared by this method comprises a first compound represented by Formula 1; and a second compound represented by Formula 2, and has a first peak in its XRD spectrum at a diffraction angle (2θ) of 23.8° to 24.5°.

[0163] Formula 1

[0164] Li x B 4-y M1 3+y O 12 X1 z

[0165] In Equation 1,

[0166] 3.8 ≤ x ≤ 4.2, 0 ≤ y < 4, and 0.5 ≤ z ≤ 1.2.

[0167] M1 is at least one element belonging to groups 13 to 15 of the periodic table, and

[0168] X1 is at least one halogen element.

[0169] Formula 2

[0170] Li x B7O 12 X2 z

[0171] In Equation 2,

[0172] 3.8 ≤ x ≤ 4.2 and 0.5 ≤ z ≤ 1.2, and

[0173] X2 is at least one halogen element.

[0174] Without further limiting the lithium-ion conductor, it is assumed that because the precursor glass crystallizes through annealing, followed by pressure and heat treatment, a lithium-ion conductor with peaks at diffraction angles (2θ) of 23.8° to 24.5° can be formed in the XRD spectrum. Therefore, the lithium-ion conductor manufactured by this method can provide excellent ionic conductivity and improved moisture stability.

[0175] First, a precursor glass comprising lithium, boron, M1 elements, and halogen elements is prepared. The process for preparing a precursor glass comprising lithium, boron, M1 elements, and halogen elements may include: preparing a mixture comprising lithium precursor, boron precursor, M1 precursor, and halogen precursor; heat-treating the mixture to prepare a molten product; and cooling the molten product to prepare the precursor glass.

[0176] In this embodiment, a mixture comprising a lithium precursor, a boron precursor, an M1 precursor, and a halogen precursor is prepared. The lithium precursor may include, for example, lithium-containing oxides, lithium-containing hydroxides, lithium-containing carbonates, lithium-containing halide salts, or combinations thereof. The lithium precursor may be, for example, Li₂O, LiOH, Li₂CO₃, etc.

[0177] Boron precursors may include, for example, boron-containing oxides. Boron precursors may be, for example, B₂O₃.

[0178] M1 precursors may include, for example, oxides containing M1, hydroxides containing M1, carbonates containing M1, or combinations thereof. M1 precursors may be, for example, Al2O3, P2O5, SiO2, GeO2, Ga2O3, or combinations thereof.

[0179] Halogen precursors can be, for example, lithium-containing halides. Examples of halogen precursors include LiCl, LiBr, LiF, and LiI.

[0180] Oxygen precursors may be added separately, optionally. Among the lithium precursors, boron precursors, M1 precursors, and halogen precursors mentioned above, oxygen-containing precursors may be used as oxygen precursors.

[0181] The contents of lithium precursors, boron precursors, M1 precursors and halogen precursors included in the mixture can be adjusted depending on the desired composition of the lithium-ion conductor.

[0182] The mixture may include, for example, 2 to 4 molar equivalents of a lithium precursor, 3 to 5 molar equivalents of a boron precursor, and 2 to 4 molar equivalents of an M1 precursor, based on a halogen precursor of 1 molar equivalent.

[0183] The mixture may include, for example, 2 to 4 molar equivalents of lithium precursor, 2.5 to 3.5 molar equivalents of lithium precursor, or 2.7 to 3.2 molar equivalents of lithium precursor, based on 1 molar equivalent of halogen precursor.

[0184] The mixture may include, for example, 3 to 5 molar equivalents of boron precursor, 3.5 to 4.5 molar equivalents of boron precursor, or 3.7 to 4.3 molar equivalents of boron precursor, based on 1 molar equivalent of halogen precursor.

[0185] The mixture may include, for example, 2 to 4 molar equivalents of M1 precursor, 2.5 to 3.5 molar equivalents of M1 precursor, or 2.7 to 3.2 molar equivalents of M1 precursor, based on 1 molar equivalent of the halogen precursor.

[0186] The prepared mixture is heat-treated to prepare a molten product.

[0187] The heat treatment for preparing the molten product may be carried out, for example, at about 700°C to about 1300°C for about 1 minute to about 10 hours. The heat treatment may be carried out in an air atmosphere or in an inert atmosphere.

[0188] The prepared molten product is cooled to prepare a precursor glass.

[0189] The precursor glass can be prepared by, for example, pouring or spreading a molten product onto a room temperature metal substrate (substrate), and then placing the room temperature metal substrate on the molten product to cool the molten product.

[0190] The cooling rate and cooling temperature can be controlled to conditions for forming precursor glasses that include amorphous or glassy phases.

[0191] The precursor glass can be formed into various shapes for subsequent annealing processes.

[0192] Following the preparation of the precursor glass, the method may further include: grinding the precursor glass to prepare precursor glass powder; and molding the precursor glass powder to prepare a molded body, such as a pellet.

[0193] The process of grinding precursor glass to prepare precursor glass powder can be carried out by mechanical grinding. Mechanical grinding includes, but is not limited to, ball milling, jet milling, etc., and any method capable of mechanical grinding in the related technical field is possible. Mechanical grinding can be carried out dry in an inert atmosphere for about 10 minutes to about 100 hours. Mechanical grinding can be carried out in an air atmosphere or in an inert atmosphere. The inert atmosphere can be an atmosphere that is substantially free of oxygen (oxygen). The inert atmosphere can be an atmosphere including nitrogen, argon, neon, or combinations thereof.

[0194] The process of molding precursor glass powder to prepare a molded body can be carried out as follows: the precursor glass powder is added to a mold of a certain shape, and then pressure is applied to the mold. The shape of the molded body can be, for example, a sheet, a film, etc.

[0195] Next, the molded precursor glass is annealed to prepare an intermediate. The precursor glass may be in sheet shape. Annealing can be performed by heat treatment at a temperature of about 200°C to about 650°C for about 10 minutes to about 10 hours. Annealing can be performed in an air atmosphere or an inert atmosphere. An intermediate can be prepared by annealing. The intermediate may have different crystallinity, composition, etc., than the precursor glass. Annealing can be performed at atmospheric pressure.

[0196] Next, the intermediate is subjected to pressure and heat treatment to prepare a lithium-ion conductor. The pressure and heat treatment can be performed at pressures ranging from about 50 MPa to about 500 MPa. The pressure and heat treatment can be performed in an air atmosphere or an inert atmosphere. A lithium-ion conductor can be prepared by pressure and heat treatment. The pressure and heat treatment can be performed by heat treatment at a temperature of about 200°C to about 700°C under pressure for about 10 minutes to about 10 hours. The above-mentioned lithium-ion conductor is prepared by pressure and heat treatment of the intermediate.

[0197] The method may further include an additional annealing process. This additional annealing can be performed by heat treatment at a temperature of approximately 200°C to approximately 650°C for approximately 10 minutes to approximately 10 hours. The additional annealing can be carried out in an air atmosphere or an inert atmosphere. This additional annealing can further improve the crystallinity of the lithium-ion conductor. The additional annealing can be performed at atmospheric pressure. This additional annealing may be omitted.

[0198] lithium batteries

[0199] According to another embodiment, a lithium battery includes: a positive electrode; a negative electrode; and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein at least one of the positive electrode, the negative electrode, and the solid electrolyte layer includes the aforementioned lithium-ion conductor. Without further limiting the lithium-ion conductor, it is believed that because the lithium battery includes the aforementioned lithium-ion conductor, the internal resistance of the lithium battery can be reduced, and the cycle characteristics and moisture stability of the all-solid-state battery can be improved.

[0200] Lithium batteries can be used in electronic devices, vehicles, and other applications. There are no particular limitations on lithium batteries, and they can be, for example, lithium-ion batteries or lithium-air batteries.

[0201] Lithium batteries can be, for example, solid-state batteries. Solid-state batteries are not particularly limited and can be, for example, multilayer ceramic (MLC) batteries. Such batteries will be described in detail below.

[0202] solid-state batteries

[0203] Figures 5 to 7 This is a schematic diagram of solid-state batteries 40 and 40a according to an embodiment.

[0204] Reference Figures 5 to 7 The positive electrode 10 can be manufactured by forming a positive electrode active material layer 12 comprising positive electrode active material on the positive electrode current collector 11. The positive electrode active material layer 12 can be formed by a vapor phase method or a solid phase method. The vapor phase method can be, but is not limited to, pulsed laser deposition (PLD), sputtering deposition, chemical vapor deposition (CVD), etc., and any method applicable to the relevant technical field can be used. The solid phase method can be, but is not limited to, sintering, powder pressing, etc., and any method applicable to the relevant technical field can be used. The liquid phase method can be, but is not limited to, sol-gel method, doctor blade method, screen printing method, slurry casting method, etc., and any method applicable to the relevant technical field can be used.

[0205] The positive electrode active material layer 12 can be prepared as follows: a positive electrode active material composition is prepared by mixing a positive electrode active material, a conductive material, a binder, and a solvent. The positive electrode 10 is manufactured by directly coating the positive electrode current collector 11 thereon with the positive electrode active material composition, or by casting the positive electrode active material composition on a carrier, peeling the composition off the carrier to obtain a film, and then laminating the obtained film onto the positive electrode current collector 11 to manufacture the positive electrode 10. Alternatively, the positive electrode 10 can be manufactured by preparing the positive electrode active material composition into an electrode ink comprising an excess solvent, and printing the electrode ink onto the positive electrode current collector 11 by an inkjet printing method or a gravure printing method. The printing method is not limited to the above methods, and any method applicable to conventional coating and printing can be used.

[0206] The positive electrode active material layer 12 includes a positive electrode active material.

[0207] Any positive electrode active material commonly used in lithium batteries can be used without restriction. Positive electrode active materials can be, for example, lithium transition metal oxides, transition metal sulfides, etc. Lithium transition metal oxides can be, for example, a composite oxide of lithium and at least one metal selected from cobalt, manganese, nickel, and combinations thereof. Positive electrode active materials are, for example, compounds represented by one of the following formulas: Li a A 1-b B' b D2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5); Li a E 1-b B' b O 2-c D c (Where, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2-b B' b O 4-c D c (Where, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B' c D α (Where, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Co b B' c O 2-α F' α (where, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0< α < 2); Li a Ni 1-b-c Mn b B' c D α (where, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0< α ≤ 2); Li a Ni 1-b-c Mn b B' c O 2-α' F' α (where, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤0.05, 0 < α < 2); Li a Ni b E c G dO2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d G e O2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2 (where 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (where 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (where 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (where 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI'O2; LiNiVO4; Li (3-f) J2(PO4)3 (0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3 (0 ≤ f ≤ 2); and LiFePO4. In the formula, A is Ni, Co, Mn or a combination thereof; B' is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof; D is O, F, S, P or a combination thereof; E is Co, Mn or a combination thereof; F' is F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; Q is Ti, Mo, Mn or a combination thereof; I' is Cr, V, Fe, Sc, Y or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu or a combination thereof. Positive electrode active materials include, for example, LiCoO2 and LiMn. x O 2x (x=1, 2), LiNi 1-x Mn x O2 (0 < x < 1), LiNi 1-x-y CO x Mn y O2 (0≤x≤0.5, 0≤y≤0.5), LiFePO4, TiS2, FeS2, TiS3, FeS3, etc.

[0208] The positive electrode active material can be covered by a coating layer. The coating layer can be any layer known as a coating layer for positive electrode active materials used in multilayer ceramic batteries. The coating layer is, for example, made of Li2O-ZrO2 (LZO).

[0209] The size of the positive electrode active material can be, for example, from about 0.1 micrometers (μm) to about 20 μm, from about 0.5 μm to about 10 μm, or from about 1 μm to about 5 μm. The positive electrode active material can be, for example, a single crystal particle or a polycrystalline particle.

[0210] The positive electrode active material may be in the form of particles, such as spheres, ellipses, or balls. The particle size of the positive electrode active material is not particularly limited and is within the range suitable for positive electrode active materials in conventional all-solid-state batteries. The content of the positive electrode active material in the positive electrode active material layer 12 is not particularly limited and is within the range suitable for positive electrode active material layers 12 in conventional all-solid-state batteries. The content of the positive electrode active material included in the positive electrode active material layer 12 may be approximately 80% to approximately 99% by weight, approximately 80% to approximately 95% by weight, or approximately 80% to approximately 90% by weight of the total weight of the positive electrode active material layer 12.

[0211] The positive electrode active material layer 12 may further comprise a solid electrolyte. The solid electrolyte may include the lithium-ion conductor described above. The content of the solid electrolyte included in the positive electrode active material layer 12 may be from about 0.1% to about 20% by weight, from about 1% to about 20% by weight, or from about 10% to about 20% by weight of the total weight of the positive electrode active material layer 12.

[0212] The positive electrode active material layer 12 may further include a conductive material, an adhesive, or a combination thereof.

[0213] The conductive material may include, for example, a carbon-based conductive material. Carbon-based conductive materials may include, for example, carbon black, carbon fibers, graphite, fluorocarbons, or combinations thereof. Carbon black may be, for example, acetylene black, Ketjen black, Super P carbon, channel black, furnace black, lamp black, thermal black (pyrolytic carbon black), or combinations thereof. Graphite may be natural graphite or artificial graphite. In addition to carbon-based conductive materials, the positive electrode active material layer 12 may further include a metal-based conductive material, a metal oxide-based conductive material, or a polymer-based conductive material. The metal-based conductive material, the metal oxide-based conductive material, or the polymer-based conductive material may be, for example, metal fibers; metal powders such as aluminum powder or nickel powder; conductive metal oxides such as zinc oxide or potassium titanate; or polyethylene derivatives. The content of the conductive material relative to 100 parts by weight of the positive electrode active material may be from about 1 part by weight to about 10 parts by weight or from about 2 parts by weight to about 7 parts by weight.

[0214] The adhesive improves the adhesion between the components of the positive electrode active material layer 12 and the adhesion of the positive electrode active material layer 12 to the positive electrode current collector 11. Examples of adhesives may include polyacrylic acid (PAA), polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluorinated rubber, copolymers thereof, or combinations thereof. The adhesive content relative to 100 parts by weight of the positive electrode active material may be from about 1 part by weight to about 10 parts by weight or from about 2 parts by weight to about 7 parts by weight. The adhesive may be partially or completely removed during the sintering process of the positive electrode active material layer 12 by evaporation and / or carbonization. The adhesive may be omitted.

[0215] The positive electrode current collector 11 may include, for example, a metal-based substrate or a carbon-based substrate. As a metal-based substrate, for example, a porous body, mesh, plate, or foil made of stainless steel, nickel (Ni), aluminum (Al), indium (In), copper (Cu), magnesium (Mg), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), germanium (Ge), lithium (Li), or alloys thereof may be used. The positive electrode current collector 11 may be, for example, a sintered product of metal powder used in the aforementioned metal-based substrate. The carbon-based substrate may include, for example, one-dimensional carbon-based materials such as carbon fibers or carbon nanotubes; two-dimensional carbon-based materials such as graphite or graphene; or combinations thereof. The positive electrode current collector 11 may further include a binder. The binder may be selected from the binder used in the positive electrode active material layer 12. The positive electrode current collector 11 may be omitted.

[0216] The negative electrode 20 can be manufactured in the same manner as the positive electrode 10, except that a negative electrode active material is used instead of a positive electrode active material. The negative electrode 20 can be manufactured by forming a negative electrode active material layer 22 comprising the negative electrode active material on the negative electrode current collector 21.

[0217] The negative electrode 20 can be prepared as follows: a negative electrode active material composition is prepared by mixing a negative electrode active material, a conductive material, a binder, and a solvent. The negative electrode 20 can be manufactured by directly coating the negative electrode current collector 21 with the negative electrode active material composition, or by casting the negative electrode active material composition on a carrier, peeling the composition off the carrier to obtain a film, and then laminating the obtained film onto the negative electrode current collector 21 to manufacture the negative electrode 20. Alternatively, the negative electrode can be manufactured by preparing an electrode ink comprising an excess solvent from the negative electrode active material composition, and printing the electrode ink onto the negative electrode current collector 21 by inkjet printing or gravure printing. The printing method is not limited to the methods described above, and any method suitable for general coating and printing can be used.

[0218] The negative electrode active material layer 22 includes a negative electrode active material.

[0219] The negative electrode active material may include, for example, one or more selected from lithium metal, lithium metal alloys, metals capable of alloying with lithium, transition metal oxides, non-transition metal oxides, and carbon-based materials. A lithium metal alloy is an alloy of lithium and another metal such as indium. The metal capable of alloying with lithium may be, for example, Si, Sn, Al, Ge, Pb, Bi, Sb, a Si-Y' alloy (where Y' is an alkali metal, alkaline earth metal, group 13 element, group 14 element, group 15 element, group 16 element, transition metal, rare earth element, or a combination thereof, but not Si), a Sn-Y' alloy (where Y' is an alkali metal, alkaline earth metal, group 13 element, group 14 element, group 15 element, group 16 element, transition metal, rare earth element, or a combination thereof, but not Sn), etc. The 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. The transition metal oxide may be, for example, lithium titanium oxide, vanadium oxide, lithium vanadium oxide, etc. The non-transition metal oxide may be, for example, SnO2, SiO x (0 < x < 2), etc.

[0220] The carbon-based material may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon may be graphite such as natural graphite or artificial graphite, which has a non-shaped, plate-like, flaky, spherical, or fibrous shape, and the amorphous carbon may be soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbide, calcined coke, etc. The negative electrode active material may include, for example, 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.

[0221] The negative electrode active material layer 22 may further include a solid electrolyte. The solid electrolyte may include the above-mentioned lithium ion conductor. The content of the solid electrolyte in the negative electrode active material layer 22 may be about 0.1 wt% to about 50 wt%, about 1 wt% to about 40 wt%, or about 10 wt% to about 30 wt% of the total weight of the negative electrode active material layer 22.

[0222] The negative electrode active material layer 22 may further include a conductive material, a binder, or a combination thereof. The conductive material and binder may be selected from the conductive material and binder used in the positive electrode active material layer 12, respectively. The content of the conductive material and binder used in the negative electrode active material layer 22 may be selected from the content of the conductive material and binder used in the positive electrode active material layer 12. The binder may be partially or completely removed during the sintering process of the negative electrode active material layer 22 by evaporation and / or carbonization. The binder may be omitted.

[0223] The negative electrode current collector 21 can be selected from the metal-based substrate or the carbon-based substrate used in the positive electrode current collector 11 described above.

[0224] The solid electrolyte layer 30 may include an oxide-based solid electrolyte. The solid electrolyte layer 30 may include the lithium-ion conductor described above.

[0225] The solid electrolyte layer 30 can be formed by mixing and drying a solid electrolyte including the lithium-ion conductor described above, and a binder, or by pressing solid electrolyte powder including the lithium-ion conductor described above into a certain shape. The solid electrolyte layer 30 can also be formed by mixing and drying a solid electrolyte including the lithium-ion conductor described above, a sulfide-based and / or oxide-based solid electrolyte, and a binder, or by pressing solid electrolyte powder including the lithium-ion conductor described above with sulfide-based and / or oxide-based solid electrolyte powder into a certain shape. Alternatively, the solid electrolyte layer 30 can be formed by mixing and drying a sulfide-based and / or oxide-based solid electrolyte and a binder, or by pressing sulfide-based and / or oxide-based solid electrolyte powder into a certain shape.

[0226] Sulfide-based solid electrolytes may include, for example, lithium sulfide, silicon sulfide, phosphorus sulfide, boron sulfide, or combinations thereof.

[0227] The solid electrolyte layer 30 may further include a binder. The binder may be selected from the binder used in the positive electrode active material layer 12. The amount of binder used in the solid electrolyte layer 30 may be selected from the amount of binder used in the positive electrode active material layer 12. The binder may be partially or completely removed during the sintering process of the solid electrolyte layer 30 by evaporation and / or carbonization. The binder may be omitted.

[0228] A boundary layer (not shown) may be disposed along the side surfaces of the positive electrode 10 and the negative electrode 20 to surround at least a portion of the positive electrode 10 and the negative electrode 20. The boundary layer (not shown) is disposed on the solid electrolyte layer 30 and may be disposed adjacent to the side surfaces of the positive electrode active material layer 12 and / or the negative electrode active material layer 22 to surround at least a portion of the positive electrode active material layer 12 and / or the negative electrode active material layer 22. The boundary layer (not shown) may be disposed in the same layer as the positive electrode active material layer 12 and / or the negative electrode active material layer 22.

[0229] The boundary layer (not shown) may include, for example, an insulating or conductive material. The boundary layer (not shown) may include, for example, an insulator having an ionic conductivity of 1 / 100 or less or 1 / 1000 or less compared to the ionic conductivity of the solid electrolyte layer 30. The boundary layer (not shown) may include, for example, an insulating polymer. Examples of insulating polymers may include, but are not limited to, polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate (PET); polyurethane; and polyimide.

[0230] Unplated negative electrode

[0231] Figure 5 This is a schematic diagram of an all-solid-state battery 40 including an unplated negative electrode according to an embodiment. In the all-solid-state battery 40 including an unplated negative electrode, the initial charge capacity of the negative electrode active material layer 22 during initial charging is, for example, more than 50%, 60% or greater, 70% or greater, 80% or greater, 90% or greater, or 100% or greater of the initial charge capacity of the positive electrode active material layer 12.

[0232] Uncoated negative electrodes can be manufactured using the methods described above for manufacturing negative electrodes for solid-state batteries.

[0233] Reference Figure 5The all-solid-state battery 40, including an unplated negative electrode, comprises a solid electrolyte layer 30, a positive electrode 10 disposed on one side of the solid electrolyte layer 30, and a negative electrode 20 disposed on the other side of the solid electrolyte layer 30. The positive electrode 10 includes a positive active material layer 12 in contact with the solid electrolyte layer 30 and a positive current collector 11 in contact with the positive active material layer 12. The negative electrode 20 includes a negative active material layer 22 in contact with the solid electrolyte layer 30 and a negative current collector 21 in contact with the negative active material layer 22. In the all-solid-state battery 40, for example, the positive active material layer 12 and the negative active material layer 22 are formed on both sides of the solid electrolyte layer 30, and the positive current collector 11 and the negative current collector 21 are formed on the positive active material layer 12 and the negative active material layer 22, respectively, thereby completing the all-solid-state secondary battery 40. Alternatively, a negative electrode active material layer 22, a solid electrolyte layer 30, a positive electrode active material layer 12, and a positive electrode current collector 11 can be sequentially stacked on the negative electrode current collector 21 to complete the all-solid-state secondary battery 40.

[0234] Plated negative electrode

[0235] Figure 6 This is a schematic diagram of an all-solid-state battery including a plated negative electrode according to an embodiment. In the all-solid-state battery 40 including a plated negative electrode, the initial charge capacity of the negative electrode active material layer during initial charging is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, or 1% or less of the initial charge capacity of the positive electrode active material layer. The all-solid-state battery 40 includes, for example, a positive electrode 10 including a positive electrode active material layer 12 disposed on a positive electrode current collector 11; a negative electrode 20 including a negative electrode active material layer 22 disposed on a negative electrode current collector 21; and an electrolyte layer 30 disposed between the positive electrode 10 and the negative electrode 20, wherein the positive electrode active material layer 12 and / or the electrolyte layer 30 include a solid electrolyte.

[0236] Reference Figures 6 to 7 The negative electrode 20 includes a negative electrode current collector 21 and a negative electrode active material layer 22 disposed on the negative electrode current collector 21, and the negative electrode active material layer 22 includes, for example, a negative electrode active material and an adhesive.

[0237] The negative electrode active material included in the negative electrode active material layer 22 has, for example, a particulate shape. The average particle diameter of the negative electrode active material with a particulate shape is, for example, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or 900 nm or less. The average particle diameter of the negative electrode active material with a particulate shape is, for example, 10 nm to 4 μm, 10 nm to 3 μm, 10 nm to 2 μm, 10 nm to 1 μm, or 10 nm to 900 nm. Because the negative electrode active material has an average particle size within this range, reversible absorption and / or desorption of lithium can be promoted during charging and discharging. The average particle diameter of the negative electrode active material is, for example, the median diameter (D50) measured using a laser particle size analyzer.

[0238] The negative electrode active material included in the negative electrode active material layer 22 includes, for example, at least one selected from carbon-based negative electrode active materials and metallic or quasi-metallic negative electrode active materials.

[0239] Carbon-based anode materials are specifically amorphous carbon. Examples of amorphous carbon include, but are not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), Ketjen black (KB), graphene, and any material classified as amorphous carbon in the relevant technical field can be used. Amorphous carbon is carbon that is non-crystalline or has very low crystallinity, and is distinct from crystalline carbon or graphitic carbon.

[0240] Metallic or quasi-metallic anode active materials include, but are not limited to, at least one selected from gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Any metallic or quasi-metallic anode active material that forms an alloy or compound with lithium in the relevant art can be used. For example, nickel (Ni) is not a metallic anode active material because it does not form an alloy with lithium.

[0241] The mixing ratio of the mixture of amorphous carbon and gold, etc., is, for example, about 10:1 to about 1:2, about 5:1 to about 1:1, or about 4:1 to about 2:1 by weight, but is not limited to this range, and is selected according to the desired characteristics of the all-solid-state battery 40. Because the negative electrode active material has such a composition, the cycle characteristics of the all-solid-state battery 40 are further improved.

[0242] Examples of adhesives included in the negative electrode active material layer 22 may include, but are not limited to, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate. Any adhesive used in the relevant technical field may be used. The adhesive may consist of a single adhesive or a combination of different adhesives.

[0243] The negative electrode active material layer 22 may further include additives such as fillers, coatings, dispersants and ion conduction aids used in conventional all-solid-state batteries 40.

[0244] The thickness of the negative electrode active material layer 22 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer 12. The thickness of the negative electrode active material layer 22 is, for example, about 1 μm to about 20 μm, about 2 μm to about 10 μm, or about 3 μm to about 7 μm. When the thickness of the negative electrode active material layer 22 is too thin, lithium dendrites formed between the negative electrode active material layer 22 and the negative electrode current collector 21 cause the negative electrode active material layer 22 to collapse, thereby making it difficult to improve the cycle characteristics of the all-solid-state battery 40. When the thickness of the negative electrode active material layer 22 is excessively increased, the energy density of the all-solid-state battery 40 decreases, and the internal resistance of the all-solid-state battery 40 increases due to the negative electrode active material layer 22, thereby making it difficult to improve the cycle characteristics of the all-solid-state battery 40.

[0245] Reference Figure 7 The all-solid-state battery 40a may further include a metal layer 23 disposed between the negative electrode current collector 21 and the negative electrode active material layer 22. The metal layer 23 may be a metal foil or a plated metal layer. The metal layer 23 comprises lithium or a lithium alloy. Therefore, the metal layer 23 serves as a lithium reservoir. Examples of lithium alloys may include, but are not limited to, Li-Al alloys, Li-Sn alloys, Li-In alloys, Li-Ag alloys, Li-Au alloys, Li-Zn alloys, Li-Ge alloys, and Li-Si alloys, and any lithium alloy used in the relevant technical field may be used. The metal layer 23 may be made of one of these alloys, may be made of lithium, or may be made of several types of alloys.

[0246] The thickness of the metal layer 23 is not particularly limited, but may be, for example, about 1 μm to about 200 μm, about 1 μm to about 100 μm, about 1 μm to about 70 μm, about 1 μm to about 50 μm, about 1 μm to about 30 μm, or about 1 μm to about 20 μm. When the thickness of the metal layer 23 is too thin, it is difficult for the metal layer 23 to function as a lithium reservoir. When the thickness of the metal layer 23 is too thick, the mass and volume of the all-solid-state battery 40a may increase, and the cycle characteristics of the all-solid-state battery 40a may deteriorate. The metal layer 23 may, for example, be a metal foil with a thickness within this range.

[0247] The negative electrode current collector 21 is, for example, made of a material that does not react with lithium (i.e., a material that does not form either an alloy or a compound). Examples of materials constituting the negative electrode current collector 21 include, but are not limited to, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), and any material that can be used as an electrode current collector in the relevant art can be used. The negative electrode current collector 21 may be composed of one of the aforementioned metals, or may be composed of an alloy or coating material of two or more metals. The negative electrode current collector 21 is, for example, in the form of a plate or foil.

[0248] Multilayer ceramic (MLC) battery

[0249] A multilayer ceramic battery includes, for example, a plurality of positive electrodes; a plurality of negative electrodes alternately arranged between the plurality of positive electrodes; and a solid electrolyte layer alternately arranged between the plurality of positive electrodes and the plurality of negative electrodes. The solid electrolyte layer includes the aforementioned lithium-ion conductor.

[0250] Multilayer ceramic batteries can be, for example, sintered bodies of laminates in which a positive electrode active material composition, a negative electrode active material composition, and a precursor for a solid electrolyte are sequentially stacked. The precursor for the solid electrolyte may include the aforementioned precursor glass. Multilayer ceramic batteries can be laminates in which a positive electrode active material, a negative electrode active material, and a solid electrolyte are sequentially stacked, or sintered bodies of such laminates.

[0251] The positive electrode active material composition may include a positive electrode active material and a binder. The positive electrode active material composition may further include a conductive material. As the binder and conductive material, the binders and conductive materials mentioned in the positive electrode of an all-solid-state secondary battery can be used.

[0252] The positive electrode active material composition may include a precursor (precursor glass) for forming the aforementioned lithium-ion conductor. This precursor for forming the lithium-ion conductor may be converted into a solid lithium-ion conductor during the co-sintering process of the laminate described later.

[0253] Multilayer ceramic batteries have a stacked structure in which multiple cell units (each cell including a positive electrode comprising a positive electrode active material layer; a solid electrolyte layer; and a negative electrode comprising a negative electrode active material layer arranged sequentially and continuously) are stacked such that the positive electrode active material layers and the negative electrode active material layers face each other. Multilayer ceramic batteries may further include, for example, positive electrode current collectors and / or negative electrode current collectors. When a multilayer ceramic battery includes a positive electrode current collector, the positive electrode active material layer may be disposed on both sides of the positive electrode current collector. When a multilayer ceramic battery includes a negative electrode current collector, the negative electrode active material layer may be disposed on both sides of the negative electrode current collector. Because multilayer ceramic batteries further include positive electrode current collectors and / or negative electrode current collectors, the high-rate characteristics of the battery can be further improved. In multilayer ceramic batteries, cell units are stacked by providing a current collector layer on one or both of the uppermost and lowermost layers of the stack, or by inserting a metal layer into the stack. Multilayer ceramic batteries or thin-film batteries are small or ultra-small batteries that can be used as power sources for applications such as the Internet of Things (IoT) and for wearable devices. Multilayer ceramic batteries or thin-film batteries can also be used in medium and large batteries, such as electric vehicles (EVs) and energy storage systems (ESS).

[0254] The negative electrode included in a multilayer ceramic battery includes at least one negative electrode active material selected from lithium metal phosphate, lithium metal oxide, metal oxide and carbon-based negative electrode active materials.

[0255] Examples of carbon-based anode active materials include amorphous carbon, crystalline carbon, porous carbon, and combinations thereof. Examples of crystalline carbon may include graphite, such as natural or synthetic graphite, which can be amorphous, tabular, flake-like, spherical, or fibrous.

[0256] Examples of amorphous carbon include carbon black (CB), acetylene black (AB), furnace black (FB), Ketjen black (KB), graphene, soft or hard carbon, mesophase pitch carbides, and calcined coke. Amorphous carbon, as carbon that is non-crystalline or has very low crystallinity, is distinguished from crystalline carbon.

[0257] Carbon-based anode materials can be, for example, porous carbon. The volume of the pores in porous carbon is, for example, about 0.1 cubic centimeters per gram (cm³). 3 / g) to approximately 10.0 cm 3 / g, approximately 0.5 cm 3 / g to approximately 5 cm 3 / g, or approximately 0.1 cm 3 / g to approximately 1 cm 3 / g. The average diameter of the pores in the porous carbon is, for example, about 1 nm to about 50 nm, about 1 nm to about 30 nm, or about 1 nm to about 10 nm. The BET specific surface area of ​​the porous carbon is, for example, about 100 m² / g.2 / g) to about 3000 m 2 / g.

[0258] The negative electrode active material is selected from Li 4 / 3 Ti 5 / 3 O4, LiTiO2, LiM1 s M2 t O u (where M1 and M2 are transition metals, and s, t, u are any positive numbers), TiO x (0 < x ≤ 3), and Li x V2(PO4)3 (0 < x ≤ 5). The negative electrode active material according to an embodiment may be Li 4 / 3 Ti 5 / 3 O4, LiTiO2 or a combination thereof.

[0259] The positive electrode included in the multilayer ceramic battery includes a positive electrode active material. The positive electrode active material may be selected from positive electrode active materials used in all-solid-state secondary batteries. The positive electrode active material includes at least one selected from lithium metal phosphates and lithium metal oxides, and for example, includes lithium cobalt oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide or a combination thereof.

[0260] The current collector layer can be used as a positive electrode current collector and / or a negative electrode current collector. The current collector layer can be made of any metal of Ni, Cu, Ag, Pd, Au, and Pt. The current collector layer can be made of an alloy including any one of Ni, Cu, Ag, Pd, Au, and Pt. The alloy can be, for example, an alloy of two or more selected from Ni, Cu, Ag, Pd, Au, and Pt. The alloy is, for example, an Ag / Pd alloy. These metals and alloys can be single metals and alloys, or can be mixtures of two or more. The current collector layer as the positive electrode current collector and the current collector layer as the negative electrode current collector can use the same material, or can be different from each other. Since the alloy or mixed powder including Ag and Pd can continuously and arbitrarily change the melting point from the melting point of silver (962 °C) to the melting point of palladium (1550 °C), the melting point can be adjusted to match the batch sintering temperature, and since the alloy or mixed powder has a high electron conductivity, an increase in the internal resistance of the battery can be suppressed.

[0261] Figure 8 is a schematic cross-sectional view of a multilayer ceramic (MLC) battery according to an embodiment. Refer to Figure 8A positive electrode active material layer 112 is disposed on both sides of the positive electrode current collector 111 to form a positive electrode 110. A negative electrode active material layer 122 is disposed on both sides of the negative electrode current collector 121 to form a negative electrode 120. A composite solid electrolyte 130 according to the embodiment is disposed between the positive electrode 110 and the negative electrode 120. External electrodes 140 are formed at both ends of the battery body 150. The external electrodes 140 are connected to the positive electrode 110 and the negative electrode 120, the ends of which are exposed to the outside of the battery body 150, and serve as external terminals for electrically connecting the positive electrode 110 and the negative electrode 120 to an external device. One of the pair of external electrodes 140 connects one end to the positive electrode 110 exposed to the outside of the battery body 150, and the other connects the other end to the negative electrode 120 exposed to the outside of the battery body 150. The multilayer ceramic (MLC) battery 150 can be manufactured by sequentially stacking a positive electrode, a solid electrolyte, and a negative electrode to form a stack, then stacking multiple such stacks and simultaneously heat-treating these stacks.

[0262] The method for manufacturing a multilayer ceramic battery according to the embodiments is described below.

[0263] First, a composition for a solid electrolyte is placed on a substrate.

[0264] According to embodiments, the composition for forming a solid electrolyte may include a lithium-ion conductor and may further include a sintering agent, a solvent, etc. The composition for forming a solid electrolyte may include a lithium-ion conductor in particulate or powder form.

[0265] According to an embodiment, the composition for forming a solid electrolyte may be a composition for forming a lithium-ion conductor comprising lithium, boron, M1 elements and halogen elements.

[0266] For example, the composition used to form a lithium-ion conductor may include a mixture or molten product comprising lithium, boron, M1 elements, and halogen elements. In particular, the composition used to form a lithium-ion conductor may be a mixture or molten product comprising Li2O, B2O3, Al2O3, and LiCl.

[0267] Compositions for forming lithium-ion conductors may include precursor glasses or their crystalline phases. Compositions for forming lithium-ion conductors may include amorphous or glassy precursor glasses comprising lithium, boron, M1 elements, and halogen elements. Amorphous or glassy precursor glasses can be prepared by melting a mixture comprising Li2O, B2O3, Al2O3, and LiCl and then cooling the mixture. Compositions for forming lithium-ion conductors may include precursor glasses in granular or powder form. Alternatively, compositions for forming lithium-ion conductors may include materials in which the precursor glass is partially crystalline. Partially crystalline precursor glasses can be prepared by annealing the precursor glass at a temperature of about 200°C to about 650°C. Compositions for forming lithium-ion conductors may include partially crystalline precursor glasses in granular or powder form.

[0268] In cases where the membrane of the composition used to form a solid electrolyte has a self-standing state, the substrate can be omitted.

[0269] The positive electrode is formed by printing the composition for forming the positive electrode onto a substrate and a film of the composition for forming a solid electrolyte disposed on the substrate.

[0270] The composition used to form the positive electrode may include a positive electrode active material and a binder. The positive electrode active material and binder may be the same as those used in all-solid-state secondary batteries. Additionally, the composition used to form the positive electrode may include a solid ion conductor according to embodiments.

[0271] Subsequently, a positive current collector and a positive electrode are formed on the other side of the positive electrode on which the film for forming the solid electrolyte composition is formed, thereby forming a laminate of substrate / film for forming the solid electrolyte composition / positive electrode / positive current collector / positive electrode. The positive current collector can be formed, for example, by printing the positive current collector composition.

[0272] The negative electrode is formed by printing a composition for forming the negative electrode onto a substrate and a film of the composition for forming a solid electrolyte disposed on the substrate.

[0273] The composition used to form the negative electrode may include a negative electrode active material and a binder. Here, the binder may be applied in the same manner as the binder used in all-solid-state secondary batteries.

[0274] The compositions described above for forming the positive electrode and for forming the negative electrode may include solvents.

[0275] A negative electrode current collector and a negative electrode are formed on the other side of the negative electrode of the membrane on which the composition for forming a solid electrolyte is formed, thereby forming a laminate of substrate / membrane for forming a solid electrolyte / negative electrode / negative electrode current collector / negative electrode. The negative electrode current collector can be formed, for example, by printing the negative electrode current collector composition.

[0276] The substrate is separated and removed from the laminate of substrate / film for forming solid electrolyte / positive electrode / positive electrode current collector / positive electrode. The film for forming solid electrolyte formed by removing the substrate in this manner and the film for forming solid electrolyte formed by removing the substrate from the laminate of substrate / film for forming solid electrolyte / negative electrode / negative electrode current collector / negative electrode are laminated and pressed to form a battery structure.

[0277] The positive electrode current collector composition and the negative electrode current collector composition each comprise carbon such as graphite, a metal selected from copper, aluminum, nickel, silver, gold, and their alloys, a conductive oxide, or a combination thereof. As a specific example, aluminum can be used in the positive electrode current collector, and copper can be used in the negative electrode current collector.

[0278] The process of forming the positive electrode current collector and / or the negative electrode current collector can be omitted. In other words, the battery structure according to the embodiment may not include a positive electrode current collector, a negative electrode current collector, or both.

[0279] Next, the pressed battery structure is cut. Here, the cutting size of the battery structure varies depending on the capacity of the multilayer ceramic battery, and the battery structure is cut into dimensions of approximately 5 mm to approximately 15 mm, for example, 10 mm in width and approximately 5 mm to approximately 15 mm, for example, 10 mm in length. This cutting process can be omitted.

[0280] The battery structure obtained through the above process is co-sintered to manufacture a unit cell serving as a positive electrode / current collector / positive electrode / solid electrolyte / negative electrode / current collector / negative electrode.

[0281] Co-sintering can be carried out at pressures of approximately 50 MPa to approximately 500 MPa.

[0282] Co-sintering is performed, for example, at 200°C or higher and 700°C or lower, 650°C or lower, 600°C or lower, or 550°C or lower. During this co-sintering process, the film of the composition used to form the solid electrolyte is transformed into a solid ionic conductor. In particular, the density (compactness) of the film of the composition used to form the solid electrolyte can be improved. The composition used to form the lithium-ion conductor can be transformed into a lithium-ion conductor according to the embodiments. The precursor glass in the composition used to form the lithium-ion conductor can be transformed into a lithium-ion conductor according to the embodiments.

[0283] Multiple cell units obtained through the above process can be stacked and can form external electrodes, thereby manufacturing a multilayer ceramic battery according to the embodiment.

[0284] Figure 9 and 10 The cross-sectional structure of a multilayer ceramic battery according to another embodiment is schematically shown.

[0285] like Figure 9 As shown, in the multilayer ceramic battery 710, cell 1 and cell 2 are stacked together by an internal current collector layer 74. Cell 1 and cell 2 are each sequentially stacked with a positive electrode 71, a solid electrolyte layer 73, and a negative electrode 72. Cell 1, cell 2, and the internal current collector layer 74 are stacked such that the negative electrode 72 of cell 2 is adjacent to one side surface of the internal current collector layer 74. Figure 9 The upper surface of the cell 1 is adjacent to the negative electrode 72 of the cell 1 and the other side surface of the internal current collector layer 74. Figure 9 The lower surface of the middle is adjacent. Figure 9 In this multilayer ceramic battery 710, the internal current collector layer 74 is configured to contact the negative electrode 72 of each of the cell 1 and cell 2, but it can also be configured to contact the positive electrode 71 of each of the cell 1 and cell 2. The internal current collector layer 74 includes a conductive material. The internal current collector layer 74 may further include an ion-conducting material. When the internal current collector layer 74 further includes an ion-conducting material, the voltage stabilization characteristics are improved. Since the same electrodes are arranged on both sides of the internal current collector layer 74 in the multilayer ceramic battery 710, a unipolar multilayer ceramic battery 710 in which multiple cell cells are connected in parallel through the internal current collector layer 74 can be obtained. In this way, a high-capacity multilayer ceramic battery 710 can be obtained. In the multilayer ceramic battery 710, the internal current collector layer 74 disposed between cell 1 and cell 2 includes a conductive material, so that two adjacent cell cells can be electrically connected in parallel, and at the same time, the positive electrode 71 or negative electrode 72 in the two adjacent cell cells can be ion-connected. Therefore, the potential of adjacent positive electrodes 71 or negative electrodes 72 can be averaged through the internal current collector layer 74, resulting in a stable output voltage. Furthermore, external current collectors, such as tabs, can be eliminated, and the cell units constituting the multilayer ceramic battery 710 can be connected in parallel. Thus, a multilayer ceramic battery 710 with excellent space utilization and economic efficiency can be obtained. (Refer to...) Figure 10 The laminate includes a positive electrode 81, a negative electrode 82, a solid electrolyte layer 83, and an internal current collector layer 84. These laminates are stacked and hot-pressed to obtain a multilayer ceramic battery 810. The positive electrode 81 is composed of a single positive electrode sheet, and the negative electrode 82 is composed of two negative electrode sheets.

[0286] The present disclosure will be described in detail below with reference to embodiments and comparative examples, but is not limited thereto.

[0287] Preparation of lithium-ion conductors

[0288] Example 1

[0289] A mixture was prepared by mixing Li₂O, B₂O₃, Al₂O₃, and LiCl in a molar ratio of 1.5:2.0:1.5:1.0. The mixture was added to a platinum crucible covered with an alumina crucible and heated and melted at 1000°C for 30 minutes to obtain a molten product. The molten product was spread on a first stainless steel substrate, pressed from above with a second stainless steel substrate, and rapidly cooled to prepare a precursor glass. The precursor glass was pulverized to obtain precursor glass powder. The precursor glass powder was formed into sheets and then annealed at 450°C in air for 1 hour.

[0290] The annealed sheet was then hot-pressed in air at 500°C for 0.5 hours under a pressure of 250 MPa to prepare a lithium-ion conductor in sheet form.

[0291] Example 2

[0292] The lithium-ion conductor was prepared in the same manner as in Example 1, except that the precursor glass powder sheet was annealed at 500°C for 1 hour.

[0293] Example 3

[0294] The lithium-ion conductor was prepared in the same manner as in Example 1, except that the precursor glass powder sheet was annealed at 400°C for 1 hour.

[0295] Example 4

[0296] The lithium-ion conductor was prepared in the same manner as in Example 1, except that the precursor glass powder sheet was annealed at 300°C for 1 hour.

[0297] Example 5

[0298] The lithium-ion conductor was prepared in the same manner as in Example 1, except that the precursor glass powder sheet was annealed at 350°C for 1 hour.

[0299] Comparative Example 1

[0300] The lithium-ion conductor was prepared in the same manner as in Example 1, except that annealing was omitted.

[0301] Comparative Example 2

[0302] The lithium-ion conductor was prepared in the same manner as in Example 1, except that the annealing temperature was 700°C for 1 hour.

[0303] Evaluation Example 1: XRD Analysis (I)

[0304] XRD spectra were obtained for the lithium-ion conductors prepared in Examples 1 to 5 and Comparative Examples 1 to 2, and the spectra of Examples 1 and Comparative Examples 1 to 2 are shown in Figure 1. Figure 1 and 2 in Figure 2 is Figure 1 a partial expansion view. The XRD spectrum was measured using Cu Kα radiation (1.54056 Å).

[0305] As Figure 1 and 2 shown in, the lithium-ion conductor of Example 1 exhibits a second peak at a diffraction angle (2θ) of 23.8°, a second-a peak at a diffraction angle (2θ) of 27.5°, both originating from the first phase, a third peak at a diffraction angle (2θ) of 25.3° originating from the second phase, and a first peak at a diffraction angle (2θ) of 23.9° originating from the third phase.

[0306] The lithium-ion conductor of Comparative Example 1 exhibits a second peak originating from the first phase, a second-a peak at a diffraction angle (2θ) of 27.7° originating from the first phase, and a third peak originating from the second phase, but does not exhibit the first peak originating from the third phase. For the lithium-ion conductor of Comparative Example 1, it was confirmed by Rietveld refinement that the first phase includes a first compound having a composition of Li4B4Al3O 12 Cl, and the second phase includes a second compound having a composition of Li4B7O 12 Cl.

[0307] The lithium-ion conductor of Comparative Example 2 exhibits a second peak and a second-a peak originating from the first phase, but does not exhibit the third peak originating from the second phase and the first peak originating from the third phase. For the lithium-ion conductor of Comparative Example 2, it was confirmed by Rietveld refinement that the first phase includes a first compound having a composition of Li4B4Al3O 12 Cl.

[0308] It can be confirmed that, different from the lithium-ion conductors of Comparative Examples 1 and 2, the lithium-ion conductor of Example 1 further includes a first peak at a diffraction angle (2θ) of 23.9° originating from the third phase.

[0309] For the lithium-ion conductor of Example 1, it was confirmed by Rietveld refinement that the first phase includes a first compound having a composition of Li4B4Al3O 12 Cl, the second phase includes a second compound having a composition of Li4B7O 12 Cl, and the third phase includes a third compound having a composition of Li4B q Al r O 12 Cl (4 < q < 7, 0 < r < 3).

[0310] Evaluation Example 2: XRD Analysis (II)

[0311] The peak intensity ratios, lattice parameters, and phase fractions of the lithium-ion conductors prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were calculated from the XRD spectra measured in Evaluation Example 1. The calculated peak intensity ratios, lattice parameters, and phase fractions are shown in Table 1 and... Figure 3 and 4 middle.

[0312] The first peak intensity ratio is the ratio (Ic / Ia) of the intensity Ic of the first peak originating from the third phase at a diffraction angle (2θ) of 23.9° to the intensity Ia of the second peak originating from the first phase at a diffraction angle (2θ) of 23.8°.

[0313] The second peak intensity ratio is the ratio (Ic / Ib) of the intensity Ic of the first peak originating from the third phase at a diffraction angle (2θ) of 23.9° to the intensity Ib of the third peak originating from the second phase at a diffraction angle (2θ) of 25.3°.

[0314] The a-axis lattice parameters and phase fractions were calculated by Rietveld refinement from the peaks originating from the first phase, the second phase, and the third phase, respectively. The cubic structure of the first, second, and third phases was confirmed.

[0315] Table 1

[0316]

[0317] As shown in Table 1, the first peak intensity ratio (Ic / Ia) of the lithium-ion conductors in Examples 1 to 5 is 0.05 or greater.

[0318] The second peak intensity ratio (Ic / Ib) of the lithium-ion conductors in Examples 1 to 5 is greater than 0.1.

[0319] As shown in Table 1 and Figure 3 As shown, the first phase a-axis lattice parameter of the lithium-ion conductors in Examples 1 to 5 is 12.9 Å or greater, and the third phase a-axis lattice parameter is 12.80 Å to 12.84 Å.

[0320] As shown in Table 1 and Figure 4 As shown, the lithium-ion conductors of Examples 1 to 5 have a third phase fraction of 3% by weight or more, and the lithium-ion conductors of Comparative Examples 1 to 2 do not include a third phase.

[0321] Evaluation Example 3: Measurement of Ionic Conductivity

[0322] Barrier electrodes were deposited by sputtering gold (Au) electrodes with a thickness of 20 nm onto both sides of the lithium-ion conductor sheets prepared in Examples 1 to 5 and Comparative Examples 1 to 2. Impedance was measured using a dual-probe method with barrier electrodes formed on both sides of the samples. The frequency range was 7 MHz to 1 Hz, and the amplitude voltage was 100 mV. Measurements were performed in air at 20°C. Resistance values ​​were obtained from the arcs in the Nyquist plot of the impedance measurements, and ionic conductivity was calculated by correcting for electrode area and sheet thickness. The results are shown in Table 2.

[0323] Table 2

[0324]

[0325] As shown in Table 2, the lithium-ion conductors of Examples 1 to 5 exhibited improved ionic conductivity compared to the lithium-ion conductor of Comparative Example 1. The lithium-ion conductor of Comparative Example 2 had a lithium-ion conductivity of 0 and was a lithium-ion non-conductor.

[0326] Evaluation Example 4: Measurement of Moisture Absorption Rate

[0327] The lithium-ion conductor sheets prepared in Example 1 and Comparative Examples 1 and 2 were placed in an oven at 70% relative humidity for 7 days, and then the moisture absorption rate, as the rate of increase in mass, was measured. The respective rates of increase in mass are shown in Table 3 below.

[0328] The moisture absorption rate is calculated using Equation 1 below.

[0329] Equation 1

[0330] Moisture absorption rate (%) = [(Wf-Wi) / Wi] × 100

[0331] Where Wf is the final film weight after 7 days of storage in the oven, and Wi is the initial film weight.

[0332] Table 3

[0333]

[0334] As shown in Table 3, compared with the lithium-ion conductor of Comparative Example 1, the lithium-ion conductor of Example 1 exhibits a reduced moisture absorption rate, i.e., improved moisture stability.

[0335] According to one aspect, a novel lithium-ion conductor with improved ionic conductivity and reduced water absorption is provided.

[0336] According to another approach, lithium batteries with reduced internal resistance and improved moisture stability are provided by including novel lithium-ion conductors.

[0337] On the other hand, a method for preparing novel lithium-ion conductors is provided.

[0338] The novel lithium-ion conductor can be prepared by low-temperature sintering and can be easily mass-produced under various conditions, such as air, due to its reduced moisture absorption. This novel lithium-ion conductor is suitable as a solid electrolyte for lithium batteries manufactured by sintering due to its excellent ionic conductivity.

[0339] It should be understood that the embodiments described herein are to be considered in a descriptive sense only and are not intended for limiting purposes. The descriptions of features or aspects within each embodiment should typically be considered applicable to other similar features or aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope defined by the appended claims.

Claims

1. Lithium-ion conductors, including: The first compound represented by Formula 1; and The second compound represented by formula 2, The lithium-ion conductor described herein exhibits a first peak in the X-ray diffraction pattern at a diffraction angle (2θ) of 23.8° to 24.5°. Formula 1 Yes x B 4-y M1 3+y Oh 12 X1 z In Equation 1, 3.8 ≤ x ≤ 4.2, 0 ≤ y < 4, and 0.5 ≤ z ≤ 1.

2. M1 is at least one element belonging to groups 13 to 15 of the periodic table, and X1 is at least one halogen element. Formula 2 Li x B7O 12 X2 z In Equation 2, 3.8 ≤ x ≤ 4.2 and 0.5 ≤ z ≤ 1.2, and X2 is at least one halogen element.

2. The lithium-ion conductor according to claim 1, The lithium-ion conductor has a second peak with a diffraction angle smaller than that of the first peak.

3. The lithium-ion conductor according to claim 2, Wherein the ratio of the peak intensity Ic of the first peak to the peak intensity Ia of the second peak, Ic / Ia, is 0.05 or greater.

4. The lithium-ion conductor according to claim 3, The ratio Ic / Ia is 0.1 or greater.

5. The lithium-ion conductor according to claim 1, The lithium-ion conductor described herein exhibits a third peak in its XRD spectrum at a diffraction angle (2θ) of 25.3 ± 0.5°. The ratio of the peak intensity Ic of the first peak to the peak intensity Ib of the third peak, Ic / Ib, is greater than 0.

1.

6. The lithium-ion conductor according to claim 1, The first compound has an a-axis lattice parameter of 12.945 Å or greater.

7. The lithium-ion conductor according to claim 1, further comprising: The third compound, The third compound has a cubic structure. The third compound has a different a-axis lattice parameter than the first compound, and The a-axis lattice parameter of the third compound is 12.580 Å to 12.940 Å.

8. The lithium-ion conductor according to claim 7, The third compound is different from the first compound, and The third compound includes lithium, boron, at least one element M1 belonging to groups 13 to 15 of the periodic table, oxygen, and halogens.

9. The lithium-ion conductor according to claim 7, In the third compound, the boron content is C3 B The content of elements belonging to groups 13 to 15 of the periodic table, C3 M1 The content of C3 is higher than that of C3 B / C3 M1 The boron content C1 is greater than that of the first compound. B The abundance C1 of elements belonging to groups 13 to 15 of the periodic table M1 The content of C1 B / C1 M1 .

10. The lithium-ion conductor according to claim 1, The first compound is represented by Equation 4: Formula 4 The x B 4-y M2 3+y O 12 X4 z in, In equation 4, 3.9 ≤ x ≤ 4.1, 0 ≤ y < 3, and 0.7 ≤ z ≤ 1.

1. M2 is Al, Ga, Si, Ge, P, or a combination thereof, and X4 is F, Cl, Br, I, or a combination thereof.

11. The lithium-ion conductor according to claim 1, The second compound is represented by formula 5: Formula 5 Li x B7O 12 X5 z in, In Equation 5, 3.9 ≤ x ≤ 4.1 and 0.7 ≤ z ≤ 1.1, and X5 is F, Cl, Br, I, or a combination thereof.

12. The lithium-ion conductor according to claim 1, The lithium-ion conductor further comprises an amorphous phase, a glassy phase, or a combination thereof.

13. The lithium-ion conductor according to claim 1, The lithium-ion conductor described herein has a strength of 3.7 × 10⁻⁶ at 20°C and 1 atm. -6 S / cm or greater ionic conductivity.

14. The lithium-ion conductor according to claim 1, The lithium-ion conductor has a moisture absorption rate of 30% or less, which corresponds to the rate of increase in mass due to the absorption of moisture after the lithium-ion conductor is placed at 70% relative humidity for 7 days.

15. Lithium-ion batteries, including: Positive electrode; negative electrode; and a solid electrolyte layer disposed between the positive electrode and the negative electrode. At least one of the positive electrode, the negative electrode, and the solid electrolyte layer comprises a lithium-ion conductor according to any one of claims 1 to 14.

16. A method for preparing a lithium-ion conductor according to any one of claims 1 to 14, the method comprising: Precursor glasses containing lithium, boron, M1 elements and halogen elements were prepared. The precursor glass is annealed to prepare an intermediate. and The intermediate is subjected to pressure and heat treatment to prepare the lithium-ion conductor comprising a crystalline phase.

17. The method according to claim 16, The annealing of the precursor glass is carried out at a temperature of 200°C to 650°C.

18. The method according to claim 16, The pressurization and heat treatment of the intermediate are carried out at a temperature of 200°C to 700°C and a pressure of 50 MPa to 500 MPa.

19. The method according to claim 16, The preparation of the precursor glass includes: Melting a mixture comprising Li₂O, B₂O₃, Al₂O₃, and LiCl to obtain a melt product; and The molten product is cooled to form a precursor glass comprising an amorphous phase or a glassy phase.

20. The method according to claim 19, The mixture comprises, in 1 molar equivalent of a halogen precursor, 2 to 4 molar equivalents of a lithium precursor, 3 to 5 molar equivalents of a boron precursor, and 2 to 4 molar equivalents of an M1 element precursor.

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