Lithium bismuth oxyhalide-based lithium-ion conductor, manufacturing method therefor, and lithium battery comprising same

Abstract

Provided are a lithium bismuth oxyhalide-based lithium-ion conductor, a manufacturing method therefor, and a lithium battery comprising same. The lithium bismuth oxyhalide-based lithium-ion conductor has a tetragonal crystal system and, through the unique crystal structure, can exhibit excellent lithium-ion conductivity.

Description

Lithium bismuth oxyhalide-based lithium ion conductor, method for manufacturing the same, and lithium battery including the same

[0001] The present invention relates to a lithium battery, and more specifically, to a lithium bismuth oxyhalide-based lithium ion conductor, a method for manufacturing the same, and a lithium battery comprising the same.

[0002] As industry advances, the development of batteries with high energy density and safety is also steadily progressing. Among these, lithium batteries are actively utilized in the fields of information devices, communication devices, and automobiles; as this directly impacts the lives of users, their safety is considered to be of even greater importance. Lithium battery electrolytes can be classified into liquid electrolytes composed of liquids such as EC, DMC, or EMC; gel electrolytes in which the liquid electrolyte exists in a gel-like form; and solid electrolytes composed of inorganic materials or polymers. Currently, commercially available lithium (Li) batteries primarily use liquid electrolytes with high ionic conductivity to enable lithium ions to move smoothly across the electrodes.

[0003] However, these liquid electrolytes contain flammable organic solvents, posing a risk of overheating or fire. Additionally, lithium batteries containing liquid electrolytes necessarily require a separator to prevent direct contact between the positive and negative electrodes, which limits the ability to increase battery density.

[0004] Accordingly, solid electrolytes are being developed to replace the liquid electrolyte in lithium batteries with a solid powder. Since solid electrolytes do not require separators or safety devices, they are expected to enable a reduction in battery volume and an increase in energy density, as well as improve physical and chemical stability.

[0005] Solid electrolytes can be broadly classified into sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes. Sulfide solid electrolytes have high lithium ion conductivity, but they have the disadvantage of generating toxic hydrogen sulfide when exposed to air due to low material stability. Additionally, oxide solid electrolytes and halide solid electrolytes have superior stability in air compared to the aforementioned sulfide solid electrolytes, but they have the problem of low lithium ion conductivity.

[0006] The present invention, aimed at solving the aforementioned problems, provides a lithium bismuth oxyhalide-based lithium ion conductor having excellent lithium ion conductivity characteristics, a method for manufacturing the same, and a lithium battery including the same.

[0007] The technical problems of the present invention are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description below.

[0008] To achieve the above objective, one aspect of the present invention provides a lithium bismuth oxyhalide-based lithium ion conductor having a tetragonal crystal system composed of a layered crystal structure with a space group of 14 / mmm and represented by the following chemical formula 1.

[0009] [Chemical Formula 1]

[0010] Li 1±δ Bi3O4X2

[0011] In the above formula, δ is 0 to 0.1, and X is Br, Cl, or I.

[0012] The above layered crystal structure is [M2O2], in which sites of lithium (Li) and bismuth (Bi) mixed in a 1:3 ratio are located at the top, and pyramids bonded to four oxygen (O) atoms located at the four vertices of the bottom are arranged sharing corners. +Layer and X - The layers may be alternately stacked.

[0013] The above M is Li 0.25 Bi 0.75 It could be.

[0014] The lithium ion conductivity of the above lithium ion conductor is 1.0 x 10⁻⁶ -3 It may be greater than S / cm.

[0015] The above lithium-ion conductor may have peaks exhibiting an intensity of 30 or more at 2θ values ​​of 31.2±0.2, 32.5±0.2, and 57.3±0.2 in the X-ray diffraction pattern obtained by powder X-ray diffraction using Cu-Ka lines.

[0016] Another aspect of the present invention provides a method for manufacturing a lithium bismuth oxyhalide-based lithium ion conductor represented by the following chemical formula 1, comprising the steps of mixing LiX, Bi2O3 and BiX3 to form an amorphous powder and heat-treating the amorphous powder to form a lithium ion conductor, wherein the lithium ion conductor has a tetragonal crystal system composed of a layered crystal structure having a space group of I4 / mmm.

[0017] [Chemical Formula 1]

[0018] Li 1±δ Bi3O4X2

[0019] In the above formula, δ is 0 to 0.1, and X is Br, Cl, or I.

[0020] The step of forming the above amorphous powder can be performed by solid-state mixing.

[0021] The above heat treatment can be performed at 400 to 600°C.

[0022] Another aspect of the present invention provides a lithium battery comprising a lithium bismuth oxyhalide-based lithium ion conductor represented by the following chemical formula 1, having a tetragonal crystal system composed of a layered crystal structure with a space group of I4 / mmm.

[0023] [Chemical Formula 1]

[0024] Li 1±δ Bi3O4X2

[0025] In the above formula, δ is 0 to 0.1, and X is Br, Cl, or I.

[0026] The lithium battery further comprises a positive electrode layer, a negative electrode layer, and a solid-liquid hybrid electrolyte layer provided between the positive electrode layer and the negative electrode layer, and the lithium bismuth oxyhalide-based lithium ion conductor may be provided in the solid-liquid hybrid electrolyte layer.

[0027] The lithium battery further comprises a positive electrode layer, a negative electrode layer, and a solid electrolyte layer provided between the positive electrode layer and the negative electrode layer, and the lithium bismuth oxyhalide-based lithium ion conductor may be provided in any one or more layers selected from the positive electrode layer, the negative electrode layer, and the solid electrolyte layer.

[0028] According to the present invention described above, a lithium bismuth oxyhalide-based lithium ion conductor, a method for manufacturing the same, and a lithium battery including the same can exhibit excellent lithium ion conductivity through the inherent crystal structure of the lithium ion conductor.

[0029] The technical effects of the present invention are not limited to those mentioned above, and other unmentioned technical effects will be clearly understood by those skilled in the art from the description below.

[0030] FIG. 1 is a schematic diagram showing the crystal structure of a lithium bismuth oxyhalide-based lithium ion conductor according to one embodiment of the present invention.

[0031] Figure 2 is an X-ray diffraction (XRD) spectrum of the lithium bismuth oxyhalide-based lithium ion conductor of Preparation Example 1 of the present invention.

[0032] Figure 3 is an image showing the results of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis of the lithium bismuth oxyhalide-based lithium ion conductor of Preparation Example 1 of the present invention.

[0033] Figure 4 is an image showing the results of structural analysis of the lithium bismuth oxyhalide-based lithium ion conductor of Preparation Example 1 of the present invention using transmission electron microscopy (TEM).

[0034] Figure 5 is a graph showing the results of analyzing the lithium bismuth oxyhalide-based lithium ion conductor of Preparation Example 1 of the present invention using electrochemical impedance spectroscopy (EIS).

[0035] FIG. 6 is a voltage-capacity graph of an initial charge-discharge cycle at 0.1C and a voltage of 2.5 to 4.3V for a lithium battery equipped with a solid-liquid hybrid electrolyte layer mixed with LBOB of Preparation Example 2 of the present invention.

[0036] Figure 7 is a graph evaluating the rate capability characteristics of a lithium battery equipped with a hybrid electrolyte mixed with LBOB of Manufacturing Example 2 of the present invention during 70 charge-discharge cycles.

[0037] Hereinafter, embodiments according to the present invention will be described in detail with reference to the attached drawings.

[0038] While the present invention allows for various modifications and variations, specific embodiments are illustrated in the drawings and will be described in detail below. However, it is not intended to limit the invention to the particular forms disclosed, but rather the invention includes all modifications, equivalents, and substitutions consistent with the spirit of the invention as defined by the claims.

[0039] When an element such as a layer, region, or substrate is referred to as existing "on" another component, it can be understood that this exists directly on the other element, or that an intermediate element may exist between them.

[0040] Although terms such as first, second, etc., may be used to describe various elements, components, regions, layers, and / or regions, it will be understood that these elements, components, regions, layers, and / or regions should not be limited by these terms.

[0041]

[0042] Lithium bismuth oxyhalide-based lithium ion conductors

[0043] One aspect of the present invention provides a lithium bismuth oxyhalide-based lithium ion conductor. The lithium bismuth oxyhalide-based lithium ion conductor may be represented by the following chemical formula 1.

[0044] [Chemical Formula 1]

[0045] Li 1±δ Bi3O4X2

[0046] In the above formula, δ is 0 to 0.1, and X is Br, Cl, or I.

[0047] Specifically, the lithium bismuth oxyhalide-based lithium ion conductor may be a lithium bismuth oxybromide-based lithium ion conductor in which X is Br. Specifically, for example, the lithium bismuth oxybromide-based lithium ion conductor may be represented by the following chemical formula 2.

[0048] [Chemical Formula 2]

[0049] Li1Bi3O4Br2

[0050] A lithium-ion conductor having the structure of Chemical Formula 1 above may have a tetragonal crystal system composed of a layered crystal structure with a space group of I4 / mmmm. The lithium-bismuth oxyhalide-based lithium-ion conductor may be a body-centered tetragonal crystal system in which the lattice is elongated in one direction.

[0051] FIG. 1 is a schematic diagram showing the crystal structure of a lithium bismuth oxyhalide-based lithium ion conductor according to one embodiment of the present invention.

[0052] Referring to FIG. 1, the lithium bismuth oxyhalide-based lithium ion conductor [M2O2] has a site where lithium (Li) and bismuth (Bi) are mixed in a 1:3 ratio located at the apex, and pyramids combined with four oxygen (O) atoms located at the four vertices of the base are arranged sharing corners. + Layer and X - The layers may be alternately stacked. In this case, the above M is Li 0.25 Bi 0.75 It can have the composition of. The above X - The layer may be Br, Cl, or I. That is, the lithium bismuth oxyhalide-based lithium ion conductor may be configured such that the lithium (Li), the bismuth (Bi), and the oxygen (O) form a pyramidal layered crystal structure, and a bromine (Br) ion layer is interposed between the layers composed of lithium-bismuth-oxygen (Li-Bi-O).

[0053] In addition, the lithium bismuth oxyhalide-based lithium ion conductor may be polycrystalline. Polycrystalline means that single crystals having different crystal orientations are interconnected at grain boundaries. As the lithium bismuth oxyhalide-based lithium ion conductor is formed as a polycrystalline structure, the capacity of the battery to which it is applied can be increased and the initial resistance can be lowered.

[0054] The above lithium bismuth oxyhalide-based lithium ion conductor may have peaks exhibiting an intensity of 5 or greater at 2θ values ​​of 14.1±0.2, 23.9±0.2, 31.2±0.2, 32.5±0.2, 43.2±0.2, 46.7±0.2, 55.1±0.2, 57.3±0.2, 65.5±0.2, 71.9±0.2, and 77.0±0.2 in the X-ray diffraction pattern obtained by powder X-ray diffraction using Cu-Ka lines. In addition to these, there may be a number of peaks exhibiting an intensity of less than 5.

[0055] Specifically, the lithium-ion conductor may have peaks with an intensity of 30 or more at 2θ values ​​of 31.2±0.2, 32.5±0.2, and 57.3±0.2 in the X-ray diffraction pattern obtained by powder X-ray diffraction using Cu-Ka lines, and more specifically, may have peaks with an intensity of 100 or more at 2θ values ​​of 31.2±0.2.

[0056] The lithium ion conductivity of the above lithium bismuth oxyhalide-based lithium ion conductor is 1.0 x 10⁻⁶ -3 It may be greater than S / cm. Specifically, the lithium ion conductivity of the above lithium ion conductor is 2.18 x 10⁻⁶ -3 It can be S / cm. Accordingly, the above lithium bismuth oxyhalide-based lithium ion conductor can be used as an ion conductor.

[0057] That is, the above-described lithium bismuth oxyhalide-based lithium-ion conductor can be actively utilized as an electrolyte material in various electrochemical devices such as secondary batteries, capacitors, solar cells, and gas sensors due to its inherently excellent ionic conductivity. Specifically, the present invention can provide a solid electrolyte comprising the above-described lithium-ion conductor, and can also provide a lithium battery comprising a solid electrolyte equipped with the above-described lithium-ion conductor.

[0058]

[0059] Method for manufacturing a lithium bismuth oxyhalide-based lithium ion conductor

[0060] Another aspect of the present invention may provide a method for manufacturing a lithium bismuth oxyhalide-based lithium ion conductor. The method for manufacturing the lithium bismuth oxyhalide-based lithium ion conductor may be to manufacture the lithium bismuth oxyhalide-based lithium ion conductor described above.

[0061] The above method for manufacturing a lithium bismuth oxyhalide-based lithium ion conductor may include the steps of mixing lithium halide (LiX), bismuth trioxide (Bi2O3), and bismuth halide (BiX3) to form an amorphous powder, and heat-treating the amorphous powder to form a lithium ion conductor. At this time, the lithium ion conductor has a tetragonal crystal system composed of a layered crystal structure with a space group of I4 / mmmm and can be represented by the following chemical formula 1.

[0062] [Chemical Formula 1]

[0063] Li 1±δ Bi3O4X2

[0064] In the above formula, δ is 0 to 0.1, and X is Br, Cl, or I.

[0065] First, the step of forming an amorphous powder by mixing the lithium halide (LiX), bismuth trioxide (Bi2O3), and bismuth halide (BiX3) can be performed by solid-state mixing. The lithium halide (LiX), bismuth trioxide (Bi2O3), and bismuth halide (BiX3) can be provided in powder form. The powders can be added to a reactor and ground together while mixed.

[0066] Specifically, for example, in the lithium halide (LiX) and bismuth halide (BiX3), X can be bromine (Br). That is, the step of forming the amorphous powder can be performed by mixing lithium bromide (LiBr), bismuth trioxide (Bi2O3), and bismuth bromide (BiBr3).

[0067] When mixing the above lithium halide (LiX), bismuth trioxide (Bi2O3) and bismuth halide (BiX3) powders, the powders can be mixed to satisfy the stoichiometric equivalent ratio. Specifically, for example, when X is bromine (Br), the lithium bromide (LiBr), bismuth trioxide (Bi2O3) and bismuth bromide (BiBr3) can be mixed in a ratio of 6:8:2 to form an amorphous powder.

[0068] The above solid-state mixing can be performed, for example, by manual grinding using a mortar and pestles or by mechanical milling. The mechanical milling is a method of grinding a sample while applying mechanical energy. Examples of such mechanical milling methods include ball mills, vibrating mills, turbo mills, mechanofusion mills, and disc mills, among which a ball mill may be preferred. Various conditions of the mechanical milling can be set to obtain the desired solid electrolyte.

[0069] In this embodiment, the lithium halide (LiX), bismuth trioxide (Bi2O3) and bismuth halide (BiX3) powders may be ground for 5 to 20 minutes in an inert gas atmosphere using a mortar and pestle. The inert gas may be, for example, argon (Ar) or nitrogen (N2), but is not limited thereto.

[0070] Afterward, the amorphous powder may be heat-treated. The heat treatment may be for crystallization of the amorphous powder. Specifically, for example, when X in the lithium halide (LiX) and bismuth halide (BiX3) is bromine (Br), the reaction following the heat treatment is as shown in Reaction Scheme 1 below.

[0071] [Reaction Equation 1]

[0072] 6LiBr + 8Bi2O3+ 2BiBr3→ 6LiBi3O4Br2

[0073] Through the above heat treatment, the amorphous powder can be formed into a lithium bismuth oxyhalide-based lithium ion conductor having a tetragonal crystal system composed of a layered crystal structure with a space group of 14 / mm.

[0074] The above heat treatment can be performed in a temperature range of 400 to 600°C, specifically 450 to 550°C, and more specifically 450 to 500°C. When the heat treatment is performed within the above-described range, the sintering reaction of lithium halide (LiX), bismuth trioxide (Bi2O3), and bismuth halide (BiX3) constituting the amorphous powder can be sufficiently completed, thereby minimizing the residue of unreacted raw materials and preventing a decrease in yield.

[0075] The above heat treatment may be carried out in an argon (Ar) atmosphere, as an example of an inert gas atmosphere. In addition, the heat treatment may be carried out for 5 to 20 hours, specifically 8 to 17 hours, and more specifically 12 to 14 hours. When the heat treatment is performed within the above-mentioned time range, the loss of the lithium-ion conductor due to the vaporization of elements constituting the solid electrolyte can be prevented.

[0076]

[0077] Lithium battery containing a lithium bismuth oxyhalide-based lithium ion conductor

[0078] Another aspect of the present invention may provide a lithium battery comprising the lithium bismuth oxyhalide-based lithium ion conductor described above. That is, the lithium battery may be a battery in which the lithium bismuth oxyhalide-based lithium ion conductor described above is applied. The lithium battery may refer to any type of battery in which a chemical reaction in which lithium ions move from the negative electrode to the positive electrode is performed. Specifically, the lithium battery may be a battery comprising a negative electrode layer and a positive electrode layer, and having a solid-liquid hybrid electrolyte layer or a solid electrolyte layer between the negative electrode layer and the positive electrode layer.

[0079] In one embodiment, the lithium battery further comprises a positive electrode layer, a negative electrode layer, and a solid-liquid hybrid electrolyte layer provided between the positive electrode layer and the negative electrode layer, and the lithium bismuth oxyhalide-based lithium ion conductor may be provided in the solid-liquid hybrid electrolyte layer.

[0080] The above-mentioned anode layer may use any anode material used in lithium batteries. Specifically, for example, the above-mentioned anode layer is provided with an anode active material, and may further provide at least one of a conductive material and a binder as needed.

[0081] The above-mentioned positive electrode active material may be a metal oxide containing lithium capable of electrochemically inserting or extracting lithium through a redox reaction. For example, the above-mentioned positive electrode active material may utilize a lithium iron phosphate-based composite oxide with an olivin structure such as LiFePO4, a lithium-cobalt-based composite oxide such as LiCoO2, a lithium-nickel-based composite oxide such as LiNiO2, a lithium-manganese-based composite oxide such as LiMn2O4, a lithium-vanadium-based composite oxide such as LiV2O5, or a lithium-iron-based composite oxide such as LiFeO2. Additionally, a nickel-cobalt-manganese (NCM) material may be used as the above-mentioned positive electrode active material.

[0082] Specifically, the above positive active material is LiFe 1-x M x PO4 (0≤x<1), where M may include one or more elements selected from the group consisting of Ni, Co, Mn, Al, Mg, Y, Zn, In, Ru, Sn, Sb, Ti, Te, Nb, Mo, Cr, Zr, W, Ir, and V, specifically, for example, LiFePO4, Li(Fe,Mn)PO4, Li(Fe,Co)PO4, or Li(Fe,Ni)PO4, but is not limited thereto. Alternatively, the cathode active material may include one or more elements selected from the group consisting of Ni, Co, and Mn, LiNi x Co y Mn z O2(x+y+z=1), LiNi x Co y Mn zMaO2(x+y+z+a=1) can be used, where M can be B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, or W, but is not limited thereto. In this embodiment, LiFePO4 (LFP) was used as the positive electrode active material.

[0083] The above conductive material may be any conductive material used in batteries. Specifically, for example, the above conductive material may be graphene, carbon nanotubes, activated carbon, super p conductive carbon, or carbon fiber, but is not limited thereto.

[0084] The above binder may include, but is not limited to, polymer compounds of fluorine-based, diene-based, acrylic-based, or silicone-based polymers. Specifically, for example, the binder may be nitrile butadiene rubber (NBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), or polyimide (PI).

[0085] The above-described anode layer can be formed through a method for forming an anode layer of a lithium battery. Specifically, for example, it can be formed by applying (coating) a slurry mixed with the above-described anode active material, conductive material, binder, and solvent onto a substrate (or current collector), and then drying and / or rolling it, but is not particularly limited. The thickness of the above-described anode layer may preferably be formed in a range of, for example, 0.1 to 1,000 μm.

[0086] The above-mentioned negative electrode layer may utilize any negative electrode material used in lithium batteries. Specifically, for example, the above-mentioned negative electrode layer is provided with a negative electrode active material and may contain at least one of a conductive material and a binder as needed. The above-mentioned negative electrode layer may be formed using the same composition or manufacturing method as the anode layer described above, except for the negative electrode active material. Accordingly, the above-mentioned details may be referenced.

[0087] As the above-mentioned negative electrode active material, a material capable of electrochemically inserting or extracting lithium through a redox reaction may be used. Specifically, for example, the above-mentioned negative electrode active material may be metallic lithium or LiAl-based, LiAg-based, LiPb-based, LiSi-based, or LiIn-based alloys that alloy with lithium. In addition, as the above-mentioned negative electrode active material, non-graphitizable carbon materials obtained by calcining graphite or resin, soft carbon obtained by heat-treating coke, and carbon materials such as fullerene may be used. Furthermore, as the above-mentioned negative electrode active material, metal oxides such as TiO2 and SnO2 having a potential with respect to lithium of less than 2V may be used, but are not limited thereto.

[0088] The thickness of the above cathode layer may preferably be formed in a range of, for example, 0.1 to 1,000 μm, but is not limited thereto.

[0089] The solid-liquid hybrid electrolyte layer may be provided between the anode layer and the cathode layer and may include the lithium bismuth oxyhalide-based lithium ion conductor of the present invention. The solid-liquid hybrid electrolyte layer may have a solid or gel form.

[0090] The solid-liquid hybrid electrolyte layer described above can be prepared by mixing a crosslinking agent, a lithium salt, a thermal curing initiator, and a solvent together with the lithium bismuth oxyhalide-based lithium ion conductor to prepare a precursor solution, and then thermally curing the solution. The thermal curing may be performed at 80 to 1220°C for 1 to 5 hours under an inert gas atmosphere, but any condition under which the precursor solution is cured into a solid-liquid hybrid electrolyte may be possible. The solid-liquid hybrid electrolyte layer containing the lithium bismuth oxyhalide-based lithium ion conductor may have a structure in which a polymer matrix with a network structure is generated as the crosslinking agent forms crosslinks through thermal curing, and the lithium bismuth oxyhalide-based lithium ion conductor, the lithium salt, and the solvent are impregnated within the porous structure of the polymer matrix.

[0091] The crosslinking agent may have a functional group capable of crosslinking, specifically an acrylate group or a methacrylate group. Specifically, for example, the crosslinking agent may include one or more selected from bisphenol A ethoxylate dimethacrylate, polyethyleneglycol diacrylate, triethyleneglycol diacrylate, and trimethylolpropaneethoxylate triacrylate. In this embodiment, bisphenol A ethoxylate diacrylate (Bis-A) was used as the crosslinking agent.

[0092] The above-mentioned thermosetting initiator is t-butyl peroxypivalate (tert-butyl peroxypivalate), benzoyl peroxide, di-tert-butyl peroxide, di-tert-amyl peroxide, α-cumil peroxineodecanoate, α-cumil peroxineopeptanoate, t-butyl peroxyneodecanoate, t-amyl peroxyneodecanoate, di-(2-ethylhexyl) peroxydicarbonate, and t-amyl peroxypivalate (t-amyl peroxypivalate), 2,5-dimethyl-2,5-bis(2-ethyl-hexanoylperoxy)hexane, dibenzoyl peroxide, t-amyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, 1,1-di-(t-amylperoxy)cyclohexane, 1,1-di-(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di-(t-butylperoxy)cyclohexane), t-butyl peroxyacetate, t-butyl peroxybenzoate, t-amyl peroxybenzoate, ethyl 3,It may include one or more selected from 3-bis(t-amylperoxy) butyrate, ethyl 3,3-di-(t-butylperoxy) butyrate, dicumyl peroxide, 1,1'-azobis(cyclohexanecarbonitrile), 2,2'-azobis(2-methylpropionamidine) dihydrochloride, and 4,4'-azobis(4-cyanovaleric acid). In this embodiment, t-butyl peroxyneodecanoate was used as the thermosetting initiator.

[0093] The above lithium salt may be included as a liquid electrolyte in the solid-liquid hybrid electrolyte layer. The above lithium salt may act as a source of lithium ions within the solid-liquid hybrid electrolyte layer. That is, the above lithium salt may promote the movement of lithium ions between the anode and the cathode in a lithium battery. Specifically, for example, the above lithium salt may be LiPF6, LiBF4, LiSbF6, LiAsF6, LiN(SO2C2F5)2, LiN(SO2F2)2, Li(CF3SO2)2N (hereinafter LiTFSI), LiC4F9SO3, LiClO4, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1It may be one or more selected from the group consisting of SO2)(where x and y are natural numbers), LiF, LiBr, LiCl, LiI, and LiB(C2O4)2 (lithium bis(oxalato) borate), but is not limited thereto. The solid-liquid hybrid electrolyte layer may be composed of a plurality of polymer particles composed of the lithium ion conductor and a small amount of liquid electrolyte (including lithium salt), such that the polymer particles composed of the lithium ion conductor are surrounded by the liquid electrolyte. In this case, the liquid electrolyte may not dissolve the lithium ion conductor.

[0094] The above solvent may include, but is not limited to, glycylate-based compounds or carbonate-based compounds. Specifically, for example, the above glycylate-based solvent may include one or more selected from poly(ethylene glycol) dimethyl ether (PEGDME), tetra(ethylene glycol) dimethyl ether (TEGDME, tetraglyme), tri(ethylene glycol) dimethyl ether (triglyme), poly(ethylene glycol) dilaurate (PEGDL), poly(ethylene glycol) monoacrylate (PEGMA), and poly(ethylene glycol) diacrylate (PEGDA). In addition, the carbonate-based solvent may include one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, fluoroethylene carbonate, diethyl carbonate, and ethylmethyl carbonate. In this embodiment, poly(ethylene glycol) dimethyl ether (PEGDME) was used as the solvent.

[0095] The proportion of the lithium bismuth oxyhalide-based lithium ion conductor included in the solid-liquid hybrid electrolyte layer may be in the range of 10 to 100 volume%, and more specifically, in the range of 50 to 100 volume%, but is not limited thereto. The thickness of the solid-liquid hybrid electrolyte layer may be, for example, in the range of 0.1 to 1,000 μm, and more specifically, in the range of 0.1 to 300 μm. The solid-liquid hybrid electrolyte layer may be formed by a method of mixing the solid-liquid hybrid electrolyte with a binder and a solvent and applying it, but is not limited thereto.

[0096]

[0097] In another embodiment, the lithium battery further comprises a positive electrode layer, a negative electrode layer, and a solid electrolyte layer provided between the positive electrode layer and the negative electrode layer, and the lithium bismuth oxyhalide-based lithium ion conductor may be provided in any one or more layers selected from the positive electrode layer, the negative electrode layer, and the solid electrolyte layer. That is, the lithium battery may be a solid-state battery.

[0098] The above-mentioned anode layer may use any anode material used in a lithium battery having a solid electrolyte layer. Specifically, for example, the above-mentioned anode layer is provided with an anode active material, and may additionally provide at least one of a conductive material and a binder as needed. At this time, the above-mentioned anode layer may include a lithium ion conductor, and such a lithium ion conductor may be a lithium bismuth oxyhalide-based lithium ion conductor according to the present invention. The proportion of the lithium bismuth oxyhalide-based solid electrolyte included in the above-mentioned anode layer may vary depending on the type of battery, but for example, it may be in the range of 0.1 to 80 volume%, and more specifically, in the range of 1 to 60 volume%. The materials used for the anode active material, conductive material, and binder used in the above-mentioned anode layer may be described above.

[0099] The above-mentioned negative electrode layer may use any negative electrode material used in a lithium battery having a solid electrolyte layer. Specifically, for example, the above-mentioned negative electrode layer is provided with a negative electrode active material and may contain at least one of a conductive material and a binder as needed. At this time, the above-mentioned negative electrode layer may include a lithium ion conductor, and such a lithium ion conductor may be a lithium bismuth oxyhalide-based lithium ion conductor according to the present invention. The proportion of the lithium bismuth oxyhalide-based solid electrolyte included in the above-mentioned negative electrode layer may vary depending on the type of battery, but for example, it may be in the range of 0.1 to 80 volume%, and more specifically, in the range of 1 to 60 volume%. The materials used for the negative electrode active material, conductive material, and binder used in the above-mentioned negative electrode layer may be referenced from the previously described contents.

[0100] The solid electrolyte layer may be provided between the anode layer and the cathode layer and may include the lithium bismuth oxyhalide-based lithium ion conductor of the present invention. Specifically, for example, the proportion of the lithium bismuth oxyhalide-based lithium ion conductor included in the solid electrolyte layer may be in the range of 10 to 100 volume%, and more specifically, in the range of 50 to 100 volume%. Alternatively, the solid electrolyte layer may be composed solely of the lithium bismuth oxyhalide-based solid electrolyte.

[0101] The thickness of the solid electrolyte layer may be, for example, in the range of 0.1 to 1,000 μm, more specifically in the range of 0.1 to 300 μm. The solid electrolyte layer may be formed by a method of mixing the solid electrolyte with a binder and a solvent and applying it, but is not limited thereto.

[0102] The lithium battery of the present invention may further include a positive current collector for collecting current from the positive layer and a negative current collector for collecting current from the negative layer. The positive current collector may be formed of, for example, SUS, aluminum, nickel, iron, titanium, and carbon, and the material of the negative current collector may be formed of, for example, stainless steel (SUS), copper (Cu), nickel (Ni), and carbon, but is not limited thereto. The thickness or shape of the positive current collector and the negative current collector may be appropriately selected and used according to the application of the battery.

[0103] Hereinafter, preferred experimental examples are presented to aid in understanding the present invention. However, the following experimental examples are intended only to aid in understanding the present invention, and the present invention is not limited by the following experimental examples.

[0104]

[0105] Preparation Example 1: Preparation of a lithium bismuth oxyhalide-based lithium ion conductor

[0106] The raw materials, lithium bromide (LiBr) powder, bismuth(III) oxide (Bi2O3) powder, and bismuth bromide (BiBr3) powder, were weighed and mixed according to stoichiometric equivalent ratios. The mixed powder was mixed and ground for 10 minutes in a glove box filled with an argon (Ar) atmosphere using a mortar and pestle and an agate pestle.

[0107] Afterwards, the crushed powder was filled into an alumina crucible. The alumina crucible filled with powder was placed in an alumina tube electric furnace and heated to 450°C under an argon (Ar) atmosphere, and then calcined for 12 hours. Then, it was naturally cooled, and the naturally cooled material was crushed to obtain LiBi3O4Br2 powder.

[0108] Experimental Example 1: X-ray Diffraction Analysis

[0109] After analyzing the LiBi3O4Br2 powder obtained in Preparation Example 1 by X-ray diffraction, the Rietveld refinement method was performed for analysis. Generally, the Rietveld refinement method refers to a crystal structure analysis method that obtains information about the crystal by refining the given variables using the least squares method until optimal agreement is achieved with the calculated values ​​in a selected model using various functions from the diffraction data obtained from X-ray diffraction.

[0110] Figure 2 is the X-ray diffraction (XRD) spectrum of the lithium bismuth oxyhalide-based lithium ion conductor of Preparation Example 1 of the present invention, and Table 1 below shows the diffraction peak values ​​for various crystal planes as a result of X-ray diffraction analysis. In Table 1, h, k, and l are the plane indices of the X-ray diffraction data peaks.

[0111] hkl2 theta(degrees)intensity(counts)00214.122366.1527210123.9577210.0031900428.465112.0008710331.4166810011032.5627838.527311235.651310.0673810542.903050.07 71200643.281687.5962711443.787627.3124520046.7168418.7509920249.051430.929421153.16952.4550411655.1943719.4469820455.617711.5004710756.552823.58 13721357.3841732.087600858.90690.2397621565.284610.0267320665.569048.131822068.209815.2308711868.946940.1145322270.063060.2715610971.977945.9376 30173.437910.4534522475.503760.62878001075.852310.5875821776.303882.7786330377.020176.048831077.642485.3628420878.344040.3278131279.409520.05186

[0112] Referring to Figure 2 and Table 1, the structural characteristics analysis of the LiBi3O4Br2 powder obtained in Preparation Example 1 confirmed that LiBi3O4Br2 was synthesized as a single phase without impurities.

[0113] Experimental Example 2: Surface analysis using scanning electron microscopy and energy dispersive spectroscopy

[0114] Figure 3 is an image showing the results of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis of the lithium bismuth oxyhalide-based lithium ion conductor of Preparation Example 1 of the present invention.

[0115] As shown in Fig. 3, the particle surface image of the LiBi3O4Br2 powder of Preparation Example 1 was captured using a scanning electron microscope and analyzed using energy dispersive spectroscopy. As a result, it was confirmed that LiBi3O4Br2 (LBOB) is a polycrystalline particle and that bismuth (Bi), oxygen (O), and bromine (Br) are evenly distributed on the particle surface.

[0116]

[0117] Experimental Example 3: Structural analysis using transmission electron microscopy

[0118] Figure 4 is an image showing the results of structural analysis of the lithium bismuth oxyhalide-based lithium ion conductor of Preparation Example 1 of the present invention using transmission electron microscopy (TEM). Specifically, the left image of Figure 4 is a selected area electron diffraction (SAED) pattern image showing the crystal planes of the polycrystalline phase of LBOB, which is a lithium bismuth oxyhalide-based lithium ion conductor, and the right image of Figure 4 is a high resolution transmission electron microscope (HRTEM) image showing the lattice plane spacing of the aforementioned planes.

[0119] Looking at Fig. 4, the interplanar distance of the (200) plane was found to be 0.1936, and the interplanar distance of the (110) plane was found to be 0.2722. That is, by calculating the distance between the crystal planes shown as dots in the SAED pattern image on the left and the lattices shown as dots in the HRTEM image on the right, it was confirmed that this matches the interplanar distance of the crystal structure of the lithium bismuth oxyhalide-based lithium ion conductor of Preparation Example 1 confirmed in Experimental Example 1 described above. Through this, it can be seen that the lithium ion conductor of Preparation Example 1 was synthesized as a single phase. In addition, from Fig. 4, it can be seen that the lithium ion conductor of Preparation Example 1 shows the arrangement of lattices measured in the

[0001] direction among the tetragonal crystal structures of I4 / mmm.

[0120]

[0121] Experimental Example 4: Analysis of electrical characteristics using electrochemical impedance spectroscopy

[0122] Figure 5 is a graph showing the results of analyzing the lithium bismuth oxyhalide-based lithium ion conductor of Preparation Example 1 of the present invention using electrochemical impedance spectroscopy (EIS).

[0123] Referring to FIG. 5, the lithium ion conductivity of the lithium bismuth oxyhalide-based lithium ion conductor of Preparation Example 1 is 2.18 x 10⁻⁶ at 25°C. -3 It can be confirmed that it was expressed as S / cm. As described above, it can be seen that the lithium bismuth oxyhalide-based lithium ion conductor of Preparation Example 1 of the present invention exhibits excellent lithium ion conductivity characteristics.

[0124]

[0125] Preparation Example 2: Preparation of a lithium battery having a lithium bismuth oxyhalide-based lithium ion conductor (LBOB) in a solid-liquid hybrid electrolyte layer

[0126] (1) positive electrode

[0127] : A slurry made by mixing lithium iron phosphate (LiFePO4, LFP), conductive acetylene black, polyvinylidene fluoride (PVDF), and methylpyrrolidone (NMP) was coated onto a Cu foil to produce an anode with a diameter of 14 mm.

[0128] (2) Cathode

[0129] High-quality lithium metal was used as the cathode.

[0130] (3) Solid-liquid hybrid electrolyte containing LBOB

[0131] A solution was prepared by dissolving lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and poly(ethylene glycol)dimethyl ether (PEGDME) in bisphenol A ethoxylate diacrylate (Bis-A).

[0132] A solid-liquid hybrid electrolyte with a diameter of 16 mm was prepared by mixing 10 wt% of the LBOB lithium ion conductor of Preparation Example 1 into the above solution and using a tert-butyl peroxyneodecanoate solution as an initiator to solidify it on a hot plate at 100°C for 3 hours.

[0133] (4) Lithium battery manufacturing

[0134] A lithium battery was manufactured by configuring the above anode, electrolyte, and cathode in the form of a standard coin cell (CR2032).

[0135]

[0136] Experimental Example 5: Analysis of charge / discharge characteristics of the lithium battery of Preparation Example 2

[0137] Using a battery cycler, Li + Charge and discharge cycles were performed at 0.1C in a voltage range of 2.5 to 4.3V relative to / Li. During this time, the voltage, current, and capacity were monitored to obtain graphs such as those in Figures 6 and 7.

[0138] FIG. 6 is a voltage-capacity graph of an initial charge-discharge cycle of a lithium battery equipped with a solid-liquid hybrid electrolyte layer mixed with LBOB of Preparation Example 2 of the present invention at 0.1C and a voltage of 2.5 to 4.3V, and FIG. 7 is a graph evaluating the rate capability characteristics of a lithium battery equipped with a hybrid electrolyte mixed with LBOB of Preparation Example 2 of the present invention during 70 charge-discharge cycles.

[0139] Referring to Fig. 6, the initial coulombic efficiency was found to be 76.6%. Additionally, as shown in Fig. 7, the lithium battery equipped with a solid-liquid hybrid electrolyte layer mixed with LBOB of Preparation Example 2 had a maximum capacity of 95.5 mAh / g over 70 cycles and a coulombic efficiency of 94.6% or higher. Through this, it was confirmed that the lithium battery of Preparation Example 2, utilizing the LBOB lithium-ion conductor of Preparation Example 1, is capable of operation. As described above, the battery comprising the lithium bismuth oxyhalide-based lithium-ion conductor of the present invention can exhibit excellent rate capability characteristics that maintain high capacity even as the number of charge-discharge cycles increases.

[0140] Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments, and various modifications and changes are possible by those skilled in the art within the technical spirit and scope of the present invention.

Claims

1. A lithium bismuth oxyhalide-based lithium ion conductor having a tetragonal crystal system composed of a layered crystal structure with a space group of I4 / mmm and represented by the following chemical formula 1. [Chemical Formula 1] Li 1±δ Bi3O4X2 In the above formula, δ is 0 to 0.1, and X is Br, Cl, or I.

2. In paragraph 1, the layered crystal structure is, [M2O2], in which a site with lithium (Li) and bismuth (Bi) mixed in a 1:3 ratio is located at the top, and pyramids combined with four oxygen (O) atoms located at the four vertices of the bottom are arranged sharing corners. + Layer and X - Lithium bismuth oxyhalide-based lithium ion conductor with alternating layers.

3. In Paragraph 2, The above M is Li 0.25 Bi 0.75 Phosphorus, lithium bismuth oxyhalide-based lithium ion conductor.

4. In Paragraph 1, The lithium ion conductivity of the above lithium ion conductor is 1.0 x 10⁻⁶ -3 Lithium bismuth oxyhalide-based lithium ion conductor with a S / cm or greater.

5. In paragraph 1, the lithium-ion conductor is, A lithium bismuth oxyhalide-based lithium ion conductor having peaks with an intensity of 30 or more at 2θ values ​​of 31.2±0.2, 32.5±0.2, and 57.3±0.2 in the X-ray diffraction pattern obtained by powder X-ray diffraction using Cu-Ka rays.

6. A step of mixing LiX, Bi2O3 and BiX3 to form an amorphous powder; and The method includes the step of heat-treating the above amorphous powder to form a lithium-ion conductor; A method for manufacturing a lithium bismuth oxyhalide-based lithium ion conductor, wherein the above lithium ion conductor has a tetragonal crystal system composed of a layered crystal structure with a space group of I4 / mmm and is represented by the following chemical formula 1. [Chemical Formula 1] Li 1±δ Bi3O4X2 In the above formula, δ is 0 to 0.1, and X is Br, Cl, or I.

7. In Paragraph 6, A method for manufacturing a lithium bismuth oxyhalide-based lithium ion conductor, wherein X is Br.

8. In Paragraph 7, The step of forming the above amorphous powder is, A method for manufacturing a lithium bismuth oxyhalide-based lithium ion conductor by solid-state mixing.

9. In Paragraph 7, A method for manufacturing a lithium bismuth oxyhalide-based lithium ion conductor in which the above heat treatment is performed at 400 to 600°C.

10. A solid electrolyte comprising a lithium-ion conductor according to any one of claims 1 to 9.

11. A lithium battery comprising a solid electrolyte according to paragraph 10.

12. A lithium battery comprising a lithium bismuth oxyhalide-based lithium ion conductor having a tetragonal crystal system composed of a layered crystal structure with a space group of I4 / mmm and represented by the following chemical formula 1. [Chemical Formula 1] Li 1±δ Bi3O4X2 In the above formula, δ is 0 to 0.1, and X is Br, Cl, or I.

13. In Clause 12, the lithium battery is, It further comprises an anode layer, a cathode layer, and a solid-liquid hybrid electrolyte layer provided between the anode layer and the cathode layer, and The above lithium bismuth oxyhalide-based lithium ion conductor is a lithium battery provided in the above solid-liquid hybrid electrolyte layer.

14. In Clause 12, the lithium battery is, It further includes an anode layer, a cathode layer, and a solid gel layer provided between the anode layer and the cathode layer, The above lithium bismuth oxyhalide-based lithium ion conductor is a lithium battery provided in one or more layers selected from the anode layer, the cathode layer, and the solid electrolyte layer.

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