Composition for forming oxide-based solid electrolyte sheet, oxide-based solid electrolyte sheet, and all-solid-state lithium secondary battery

Abstract

A composition for forming an oxide-based solid electrolyte sheet, according to an embodiment disclosed herein, comprises lithium conductive oxide-based particles and a dye material, wherein the dye material includes at least one of an organic dye or an organometallic dye, and the dye material has a maximum absorption wavelength (λmax) in a wavelength region of 500-800 nm. According to an embodiment disclosed herein, an oxide-based solid electrolyte sheet having excellent sintering uniformity can be manufactured.

Description

Composition for forming an oxide-based solid electrolyte sheet, oxide-based solid electrolyte sheet, and all-solid-state lithium secondary battery

[0001] The present disclosure relates to a composition for forming an oxide-based solid electrolyte sheet, an oxide-based solid electrolyte sheet, and an all-solid-state lithium secondary battery.

[0002] With the recent increase in interest in environmental issues, research is actively underway on electric vehicles (EVs) that can replace fossil fuel-based vehicles and energy storage systems (ESS) that utilize renewable energy. Lithium-ion batteries, which have high discharge voltage and output stability, are mainly used as power sources for such electric vehicles (EVs).

[0003] Meanwhile, conventional lithium secondary batteries utilizing liquid electrolytes such as organic solvents pose a risk of ignition due to electrolyte leakage, and problems such as battery expansion caused by the decomposition of the electrolyte during electrode reactions also exist. Furthermore, the separators included in conventional lithium secondary batteries to prevent these issues limit the ability to achieve high energy density. Accordingly, research and development on all-solid-state lithium secondary batteries using solid-state electrolytes are actively underway to address these problems.

[0004] According to one aspect of the present disclosure, a composition capable of producing a uniformly sintered oxide-based solid electrolyte sheet is provided.

[0005] According to another aspect of the present disclosure, the ionic conductivity of an oxide-based solid electrolyte sheet can be improved.

[0006] According to another aspect of the present disclosure, the operating conditions of the photo-sintering process can be relaxed when manufacturing an oxide-based solid electrolyte sheet by photo-sintering.

[0007] According to another aspect of the present disclosure, the uniformity of an oxide-based solid electrolyte sheet produced by large-area photo-sintering can be easily controlled.

[0008] According to another aspect of the present disclosure, damage to the substrate can be mitigated when manufacturing an oxide-based solid electrolyte sheet by photo-sintering.

[0009] A composition for forming an oxide-based solid electrolyte sheet according to one embodiment comprises lithium-conducting oxide-based particles and a dye material, wherein the dye material comprises at least one of an organic dye and an organometallic dye, and the dye material has a maximum absorption wavelength (λ) in the wavelength region of 500 nm to 800 nm. max has ).

[0010] In some embodiments, the dye material has a maximum absorption wavelength (λ) in the wavelength range of 600 nm to 780 nm. max Can have ).

[0011] In some embodiments, the total content of the dye material may be greater than 0.1 weight% and less than 10 weight% based on the total weight of the lithium conductive oxide-based particles.

[0012] In some embodiments, the lithium conductive oxide-based particles may comprise at least one selected from a garnet compound, a NASICON compound, and a perovskite compound.

[0013] In some embodiments, the average particle size (D50) of the lithium conductive oxide-based particles may be 100 nm to 10 μm.

[0014] In some embodiments, the oxide-based solid electrolyte sheet forming composition may further include a binder.

[0015] In some embodiments, the binder may comprise at least one selected from the group consisting of polyacrylic resin, ethyl cellulose, methyl cellulose and polyvinyl butyral resin, polyvinylidene fluoride, alkyl carboxylic acid monomers and ethylenically unsaturated carboxylic acid monomers.

[0016] A method for manufacturing an oxide-based solid electrolyte sheet according to one embodiment comprises the steps of: applying and drying a composition for forming an oxide-based solid electrolyte sheet onto a substrate surface to form an oxide-based solid electrolyte green sheet; and photosintering the green sheet. An oxide-based solid electrolyte green sheet according to one embodiment comprises lithium-conducting oxide-based particles and a dye material, wherein the dye material comprises at least one of an organic dye and an organometallic dye, and the dye material has a maximum absorption wavelength (λ) in the wavelength range of 500 nm to 800 nm. max has ).

[0017] In some embodiments, the oxide-based solid electrolyte green sheet may further include a binder.

[0018] An oxide-based solid electrolyte sheet according to one embodiment is manufactured using a composition for forming an oxide-based solid electrolyte sheet according to any one of the embodiments described above.

[0019] In some embodiments, the oxide-based solid electrolyte sheet is 1.0 x 10 -5 S / cm to 10 -2 It can have an ionic conductivity of S / cm.

[0020] In some embodiments, the oxide-based solid electrolyte sheet may have a thickness of 10 μm to 300 μm.

[0021] In some embodiments, the oxide-based solid electrolyte sheet may include lithium-conducting oxide-based particles in surface contact with each other.

[0022] An all-solid-state lithium secondary battery according to one embodiment includes an oxide-based solid electrolyte sheet according to any one of the embodiments described above.

[0023] According to one embodiment of the present disclosure, an oxide-based solid electrolyte sheet with excellent sintering uniformity can be manufactured.

[0024] According to another embodiment of the present disclosure, an oxide-based solid electrolyte sheet with excellent ion conductivity can be manufactured.

[0025] According to another embodiment of the present disclosure, an oxide-based solid electrolyte sheet of excellent quality can be manufactured while relaxing the operating conditions of the photo-sintering process.

[0026] According to another embodiment of the present disclosure, a large-area oxide-based solid electrolyte sheet with excellent uniformity can be manufactured.

[0027] According to another embodiment of the present disclosure, an oxide-based solid electrolyte sheet can be manufactured while mitigating substrate damage caused by photo-sintering.

[0028] FIGS. 1a to 1d are conceptual diagrams showing, respectively, the inter-particle connection structure and particle shape changing in stages as sintering progresses.

[0029] Figure 2 is a diagram showing the oxide-based solid electrolyte compositions of Comparative Example 1 and Examples 1 to 3 after being cast onto one side of a stainless steel substrate and then dried.

[0030] FIG. 3 is a diagram showing the shape of the oxide-based solid electrolyte sheets of Comparative Example 1 and Examples 1 to 3.

[0031] Figure 4 is a diagram showing the shape of the substrate surface of the oxide-based solid electrolyte sheets of Comparative Example 1 and Examples 1 to 3.

[0032] Figure 5 is a graph showing the results of electrochemical impedance analysis for oxide-based solid electrolyte sheets of Comparative Example 1 and Examples 1 to 3.

[0033] Figure 6 is a diagram showing an image of the surface of the oxide-based solid electrolyte sheet of Comparative Example 1 observed using a differential interference microscope.

[0034] Figure 7 is a diagram showing an image of the surface of the oxide-based solid electrolyte sheet of Example 1 observed using a differential interference microscope.

[0035] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings. However, the embodiments may be modified in various different forms, and their scope is not limited to the embodiments described below. Furthermore, the embodiments may not only be applied in a limited manner with the configurations of each embodiment described below, but may also be configured by selectively combining all or part of each embodiment to allow for various modifications.

[0036] In this specification, 'sintering' refers to a phenomenon in which powder-form particles are tightly bonded together by external energy. For example, the sintering phenomenon may refer to a process in which powder-form particles are bonded together through a thermal activation process to form a single mass.

[0037] In this specification, 'Light-Sintering' means sintering by inducing a thermal activation reaction within a material through light, 1) heat generation due to a resonance phenomenon between the intrinsic wavelength range of the material and the wavelength range of the light, and / or 2) heat transfer due to photothermal conversion in which absorbed light is converted into heat.

[0038] An oxide-based solid electrolyte can be applied as one of the solid electrolytes of the above-described all-solid-state lithium secondary battery. The oxide-based solid electrolyte has excellent mechanical strength and electrochemical stability, making it suitable for application as a next-generation solid electrolyte. However, the oxide-based solid electrolyte may have relatively insufficient ionic conductivity due to high interfacial resistance. According to one embodiment, the ionic conductivity of the oxide-based solid electrolyte can be improved through a sintering process that reduces interfacial resistance by connecting oxide particles contained in the oxide-based solid electrolyte to each other.

[0039] In this regard, the high-temperature sintering process of sintering an oxide molded body at a temperature of 1,000°C or higher for a long period of time, from 1 hour to 24 hours or more, is not only unsuitable in terms of time / cost, but also presents problems with lithium volatilization due to high-temperature sintering and difficulties in density control depending on the sintering conditions.

[0040] In addition, the high-temperature sintered oxide body has brittleness and lacks processability, making it difficult to produce in large areas, and it may also be virtually impossible to undergo subsequent processes such as rolling. Furthermore, it is difficult to form a homogeneous surface on the high-temperature sintered oxide body, so additional processing steps may be required.

[0041] Meanwhile, in the case of Rapid Thermal Annealing (RTA) or microwave-based processes, the temperature can be raised rapidly, allowing for a shorter duration compared to general high-temperature sintering processes; however, problems such as deformation or destruction of the substrate may occur during these processes. Additionally, in the case of laser-based processes, the reaction proceeds locally near the area where the laser is incident, resulting in a narrow application area during the sintering process and potentially requiring a long time for the sintering process.

[0042] According to one embodiment, the aforementioned problems can be effectively solved through a photo-sintering process in which light energy in the wavelength range of 10 nm to 1,000 nm is irradiated repeatedly several times. By using the photo-sintering process, it is possible to proceed with sintering in a short period of time, and accordingly, the degree of sintering of the sheet can be easily controlled. This will be explained in detail with reference to FIGS. 1a to 1d. FIGS. 1a to 1d are conceptual diagrams showing, respectively, stepwise changes in the inter-particle connection structure and particle shape as sintering progresses.

[0043] During the sintering process, the grain boundaries (boundaries where particles are in contact with each other; GB) between particles (5) expand from a point contact form during the initial stage of sintering as shown in FIG. 1a to a surface contact form as shown in FIG. 1b and FIG. 1c. In FIG. 1d, the distinct boundaries between particles disappear due to sintering, making it impossible to distinguish the particles. In the case of a point contact form where each particle maintains its initial shape as shown in FIG. 1a, the ions experience significant resistance during movement as simple contact is formed. On the other hand, when the contact area increases through sintering to become a surface contact form, the resistance of the ion movement path is lowered, enabling rapid ion conduction, and durability increases with densification, allowing the sheet shape to be well maintained.

[0044] Meanwhile, as the contact area between particles expands, the pores—the empty spaces between particles—reduce, and volume shrinkage occurs. At this time, the volume shrinkage rate may vary depending on the contact type between particles and the degree of coarsening. Specifically, in the stage where grain boundaries (GBs) are formed as sintering progresses, the volume shrinkage rate is within 3% (see Fig. 1b), whereas in the stage where the contact area between particles increases and coarsening progresses as sintering continues, the volume shrinkage rate increases to approximately 10% to 20% (see Figs. 1c to 1d). When excessive coarsening of particles within the thin film and an increase in volume shrinkage rate occur, problems such as delamination from the substrate and / or cracking of the thin film occur, leading to a degradation of function.

[0045] Accordingly, it is necessary to have a structure in which ion conduction occurs by appropriately adjusting the contact form to prevent delamination due to excessive coarsening and volume shrinkage after sintering, while maintaining a surface contact state to secure a dense structure and ion transport pathways (see Fig. 1b). If a photo-sintering process is applied, not only is high-speed sintering possible, but it is also possible to form particle shapes such as Fig. 1b by controlling the particle shape according to the degree of sintering. In addition, the particles may be appropriately coarsened as needed, taking into account the flexibility and shape of the substrate.

[0046] The oxide-based solid electrolyte sheet forming composition for the aforementioned photo-sintering process may include a light absorber for photo-sintering. In one embodiment, the oxide-based solid electrolyte sheet forming composition may include a colored oxide such as Fe2O3, which corresponds to a coloring agent, as the light absorber.

[0047] However, colored oxides such as the aforementioned Fe2O3 correspond to inorganic pigments that are insoluble in solvents, and thus their dispersion and light absorption rates may vary depending on the particle size. If the inorganic pigment is not evenly dispersed in the solvent, heat transfer by photo-sintering does not proceed uniformly, making it difficult to manufacture high-quality solid electrolyte sheets and potentially causing damage to the substrate.

[0048] In addition, transition metal-based inorganic pigments such as Fe2O3 can have electronic conductivity after the photothermal sintering process, making it difficult to add them in excess as battery materials, and they can cause side reactions with lithium conductive oxide particles such as lithium lanthanum zirconium oxide (LLZO) compounds.

[0049] According to one embodiment of the present disclosure, the problems described above can be effectively solved by using a dye material comprising at least one of an organic dye and an organometallic dye as a light absorber. Specific embodiments are disclosed below with reference to FIGS. 2 to 7.

[0050] Figure 2 is a diagram showing the oxide-based solid electrolyte compositions of Comparative Example 1 and Examples 1 to 3 after being cast onto one side of a stainless steel substrate and then dried.

[0051] FIG. 3 is a diagram showing the shape of the oxide-based solid electrolyte sheets of Comparative Example 1 and Examples 1 to 3.

[0052] Figure 4 is a diagram showing the shape of the substrate surface of the oxide-based solid electrolyte sheets of Comparative Example 1 and Examples 1 to 3.

[0053] Figure 5 is a graph showing the results of electrochemical impedance analysis for oxide-based solid electrolyte sheets of Comparative Example 1 and Examples 1 to 3.

[0054] Figure 6 is a diagram showing an image of the surface of the oxide-based solid electrolyte sheet of Comparative Example 1 observed using a differential interference microscope.

[0055] Figure 7 is a diagram showing an image of the surface of the oxide-based solid electrolyte sheet of Example 1 observed using a differential interference microscope.

[0056] Composition for forming oxide-based solid electrolyte sheets

[0057] A composition for forming an oxide-based solid electrolyte sheet according to one embodiment comprises lithium-conducting oxide-based particles and a dye material, wherein the dye material comprises at least one of an organic dye and an organometallic dye, and the dye material has a maximum absorption wavelength (λ) in the wavelength region of 500 nm to 800 nm. max The dye material comprises at least one of an organic dye and an organometallic dye that can be dissolved in a solvent, thereby mitigating problems such as dispersibility, sintering quality, and difficulty of excessive addition that occur with the inorganic pigment described above.

[0058] Maximum absorption wavelength (λ) in the above 500 nm to 800 nm wavelength range max A dye material having ) may be a red-based dye. Specifically, the dye material has a maximum absorption wavelength (λ) in the wavelength region of 600 nm to 780 nm. max It may have ). If the oxide-based solid electrolyte sheet forming composition includes a red dye, the light energy absorption rate in the visible light spectrum within the wavelength range of 380 nm to 800 nm is excellent, which can improve the photo-sintering quality. The maximum absorption wavelength (λ max ) may be the wavelength at which the absorbance value measured by a UV-Vis spectrometer is maximum within the wavelength range of 380 nm to 800 nm.

[0059] The above organic dye has a maximum absorption wavelength (λ) in the wavelength region described above. maxThe dye is not particularly limited as long as it has ) and can be dissolved in a solvent. The organic dye may be, for example, at least one selected from Disperse Red 1, 5, 7, 13, 17, 19, 43, 50, 54, 58, 65, 72, 73, 88, 117, 137, 143, 199, and 210.

[0060] The above-mentioned organometallic dye is a compound utilizing an organometallic compound as a dye, wherein ligands are coordinately bonded around a central metal ion, and the maximum absorption wavelength (λ) in the aforementioned wavelength region max It is not particularly limited to dyes that have ) and can be dissolved in a solvent.

[0061] For example, the organometallic dye may comprise at least one selected from the group consisting of ruthenium (Ru) dyes such as tris(bipyridine)ruthenium(II) chloride; iron (Fe) dyes such as ferrocene and acetylferrocene; rhodium (Rh) dyes such as pentamethylcyclopentadienyl rhodium dichloride; and titanium (Ti) dyes such as pentamethylcyclopentadienyltris(dimethylamino)titanium(IV).

[0062] In some embodiments, the total content of the dye material may be 0.1 wt% to 10 wt% based on the total weight of the lithium conductive oxide-based particles. For example, the total content of the dye material may be greater than 0.1 wt%, 0.3 wt% or more, 0.6 wt% or more, or 0.8 wt% or more based on the total weight of the lithium conductive oxide-based particles, and less than 10 wt% and 5 wt% or less. When the total content of the dye material satisfies the above-described range, it absorbs light energy sufficiently to allow photo-sintering to proceed without excessive photo-sintering, thereby further reducing damage to the substrate.

[0063] The above lithium conductive oxide-based particles may be powdered particles of a compound containing oxygen and metal elements and having conductivity toward lithium ions. The above lithium conductive oxide-based particles may be oxide-based solid electrolyte particles.

[0064] In some embodiments, the lithium conductive oxide-based particles may comprise at least one selected from a garnet compound, a NASICON compound, and a perovskite compound.

[0065] The above garnet compound is a compound having a garnet crystal structure or a garnet-like crystal structure, Li7La3Zr2O 12 It may be a lithium lanthanum zirconium oxide (LLZO)-based compound represented by the chemical formulas such as the above.

[0066] The above NASICON compound is a compound having a NASICON crystal structure or a NASICON-like crystal structure, wherein Li 1.3 Al 0.3 Ti 1.7 It may be a lithium aluminum titanium phosphate (LATP)-based compound represented by the chemical formula (PO4)3, etc.

[0067] The above perovskite compound is a compound having a perovskite crystal structure or a perovskite-like crystal structure, wherein Li 0.31 La 0.56 It may be a lithium lanthanum titanate oxide (LLTO)-based compound represented by the chemical formula TiO3, etc.

[0068] In some embodiments, the lithium conductive oxide-based particles may comprise one or more selected from zirconium (Zr), phosphate (PO4), and titanium (Ti). For example, the lithium conductive oxide-based particles (21) may comprise at least one selected from lithium lanthanum zirconium oxide (LLZO)-based compounds, lithium lanthanum zirconium oxide (LLZTO)-based compounds doped with tantalum (Ta), lithium lanthanum titanate oxide (LLTO)-based compounds, lithium aluminum germanium phosphate (LAGP)-based compounds, and lithium aluminum titanium phosphate (LATP)-based compounds.

[0069] When the above-described type of compound is included in the lithium conductive oxide-based particles, an oxide-based solid electrolyte sheet having characteristics such as excellent ionic conductivity, stability with lithium metal, and a wide potential window range can be manufactured.

[0070] In some embodiments, the average particle size (D50) of the lithium conductive oxide-based particles may be 100 nm to 10 μm. For example, the average particle size (D50) of the lithium conductive oxide-based particles may be 150 nm or more, 1,000 nm or less, 500 nm or less, or 250 nm or less. When the average particle size (D50) of the lithium conductive oxide-based particles satisfies the above-described range, the uniformity and ion conductivity of the photosintering may be excellent.

[0071] The method for measuring the average particle size (D50) of the lithium conductive oxide-based particles is not particularly limited. For example, the average particle size (D50) of the lithium conductive oxide-based particles may be the particle diameter value at the 50% volume fraction when accumulating from the smallest particle in the particle size distribution of particles measured using a particle size analysis device (such as Microtrac’s MT 3000) according to the laser diffraction method.

[0072] In some embodiments, the total content of the lithium-conducting oxide-based particles may be 25% to 95% by weight based on the total weight of the composition for forming an oxide-based solid electrolyte sheet. Specifically, the total content of the lithium-conducting oxide-based particles may be 35% or more or 45% or more by weight, and 80% or less or 70% or less by weight based on the total weight of the composition for forming an oxide-based solid electrolyte sheet.

[0073] In some embodiments, the composition for forming an oxide-based solid electrolyte sheet may further include a binder. The binder is not particularly limited as long as it is a component capable of binding the lithium-conductive oxide-based particles described above and contributing to improving the adhesion of the composition to a substrate. According to one embodiment, the binder may be an organic binder comprising at least one selected from the group consisting of a polyvinyl compound-based binder, a cellulose-based binder, an acrylic polymer-based binder, and a copolymer resin binder.

[0074] For example, the organic binder is polyvinyl alcohol (PVA), polyvinyl butyral (PB), polyvinylpyrrolidone (PVP), carboxymethylcellulose (CMC), vinylpyrrolidone / vinylacetate (VP / VA) copolymer resin, polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), acrylonitrile-butadiene rubber (NBR), and polybutadiene It may include at least one selected from the group consisting of polybutadiene rubber (BR), styrene-butadiene rubber (SBR), polyacrylic acid-based binders and poly(3,4-dioxythiophene) (poly(3,4-ethylenedioxythiophene), PEDOT).

[0075] In some embodiments, the organic binder may be an organic polymer having a glass transition temperature (Tg) of 100°C to 600°C, 100°C to 500°C, or 100°C to 300°C. For example, the organic binder may include a PVDF-based binder. When using an organic binder having the above glass transition temperature (Tg) range, the organic binder can stabilize the electrolyte by uniformly distributing and fixing lithium conductive oxide-based particles, etc., without the need for separate heat treatment at high temperatures during electrolyte preparation.

[0076] The above-described composition for forming an oxide-based solid electrolyte sheet may further include a solvent. Specifically, in some embodiments, the solvent may be a solvent capable of dissolving the lithium-conducting oxide-based particles and the binder together. In one embodiment, the solvent may include an organic solvent.

[0077] The above organic solvent may include a solvent comprising at least one functional group selected from the group consisting of alcohol, ketone, amide, ester, ether, aromatic hydrocarbon, etc. For example, the above organic solvent may include 2-propanol, isopropyl alcohol (IPA), toluene, terpineol, N-methyl-2-pyrrolidone (NMP), etc. The above solvent (or organic solvent) may be used alone or in combination of two or more.

[0078] In one embodiment, the solvent may be a combination of two types of organic solvents. For example, the solvent may be a mixture of a first solvent and a second solvent that are mixable among the solvents described above. The first solvent and the second solvent can each dissolve at least one of the lithium conductive oxide-based particles and the binder. Accordingly, even if either of the inorganic lithium conductive oxide-based particles or the binder is not dissolved in the first solvent, it can be dissolved and mixed in the second solvent.

[0079] Oxide-based solid electrolyte sheet

[0080] An oxide-based solid electrolyte sheet according to one embodiment is manufactured using a composition for forming an oxide-based solid electrolyte sheet according to any one of the embodiments described above. For example, the oxide-based solid electrolyte sheet may be manufactured by photosintering a green sheet formed by applying the aforementioned oxide-based solid electrolyte sheet-forming composition onto a substrate surface and drying it. The green sheet may refer to a sheet in an unsintered state in which sintering has not taken place. Specifically, the green sheet may be one in which the oxide-based lithium conductive oxide particles are not in surface contact.

[0081] The above substrate is not particularly limited. For example, the substrate may be a current collector in the form of copper (Cu), aluminum (Al), or stainless steel (SUS) foil, or may be a negative or positive electrode for an all-solid-state lithium secondary battery. The flexibility, shape, type, thickness, etc. of the substrate can be appropriately adjusted considering the characteristics of the photothermal sintering process and the composition to be performed later.

[0082] The method of applying the oxide-based solid electrolyte sheet-forming composition on the surface of the substrate is not particularly limited. For example, the oxide-based solid electrolyte sheet-forming composition may be applied to the surface of the substrate by methods such as bar coating, casting, or spraying.

[0083] The method of drying the oxide-based solid electrolyte sheet-forming composition applied on the surface of the substrate is not particularly limited. For example, the oxide-based solid electrolyte sheet-forming composition applied on the surface of the substrate may be dried by placing it in a convection oven. The drying temperature may, for example, be 50°C to 200°C, or 80°C to 120°C. In addition, the drying time may be 0.5 hours to 24 hours (overnight).

[0084] The above green sheet (specifically, an oxide-based solid electrolyte green sheet) may include the lithium-conducting oxide-based particles and dye material described above. In addition, the above green sheet may further include the binder and / or solvent described above.

[0085] When light is irradiated onto a green sheet formed on the surface of the substrate, heat is generated due to absorbed light, excluding reflected and transmitted light, which can cause the temperature of the material within the green sheet to rise. If this process is repeated, the temperature of the material within the green sheet, which has risen due to heat generation, is maintained instantaneously, and a sintering effect (hereinafter also referred to as "photosintering") may occur. An oxide-based solid electrolyte sheet can be manufactured using a composition for forming an oxide-based solid electrolyte sheet by utilizing this photosintering process.

[0086] In some embodiments, the photothermal sintering process may be performed in a pulsed manner. The pulsed manner refers to a method of applying a strong voltage in pulses to a device, such as a light-generating lamp, to irradiate a strong light that is instantaneously generated, and the light energy supplied through irradiation can generate heat to induce photothermal sintering. At this time, the photothermal sintering device that generates light in a pulsed manner is not particularly limited as long as it is a device capable of operating under pulse conditions set as follows.

[0087] The light irradiation time per pulse (On-time), operating voltage (V), duty cycle (%), number of cycles, the heating frequency (Firing frequency, Hz) constituting the total pulse, and the number of repetitions during the above-mentioned light sintering process can be appropriately varied (adjusted) by controlling the controller, power supply, etc. of the light sintering device.

[0088] In some embodiments, the light irradiation time per pulse (On-time) during the light sintering may be 1,000 μs to 4,500 μs. Specifically, the light irradiation time per pulse (On-time) may be 2,000 μs or more or 2,500 μs or more, and 4,400 μs or less, 4,000 μs or less, or 3,500 μs or less.

[0089] In some embodiments, the operating voltage (V) during photo-sintering may be 100 to 450 V. Specifically, the operating voltage (V) may be 200 V or more, or 250 V or more, and 440 V or less, 400 V or less, or 350 V or less.

[0090] In some embodiments, the duty cycle (%) during photo-sintering may be 10% to 100%. Specifically, the duty cycle (%) may be 30% or more or 50% or more, and 90% or less or 70% or less. The duty cycle may be calculated as the value of the ratio (%) of the light irradiation time per pulse (On-time) to the pulse period.

[0091] In some embodiments, the number of cycles during photo-sintering may be 1 to 20 times. Specifically, the number of cycles during photo-sintering may be 5 to 15 times.

[0092] When the light irradiation time (On-time), operating voltage (V), duty cycle (%), and number of cycles during the above-mentioned light sintering are controlled within the ranges described above, the light sintering process time calculated by Equation 1 below can be shortened, allowing the sintering process to be carried out in a short period of time.

[0093] [Equation 1]

[0094] T s = C / T r

[0095] In the above Equation 1, T s is the photothermal sintering process time (s), and T r is the firing frequency (Hz), and C is the number of repetitions.

[0096] In some embodiments, the firing frequency (Hz) constituting the total pulse during the photo-sintering may be 1 Hz to 50 Hz. Specifically, the firing frequency (Hz) constituting the total pulse during the photo-sintering may be 35 Hz or higher and 45 Hz or lower.

[0097] In some embodiments, the number of repetitions during photothermal sintering may be 50 to 1000 times. Specifically, the number of repetitions during photothermal sintering may be 100 times or more and 400 times or less.

[0098] In some embodiments, the temperature of the substrate during photo-sintering may be maintained at 300°C or lower. Specifically, the temperature of the substrate during photo-sintering may be maintained at 5 to 100°C, 10 to 50°C, or 15 to 30°C. More specifically, the temperature of the substrate during photo-sintering may be maintained at a room temperature (RT) of substantially 20 to 25°C. When the temperature of the substrate is maintained within the above-described range during photo-sintering, residual thermal stress on the substrate can be prevented, thereby substantially mitigating problems such as substrate failure or reduced durability, and various types of substrates can be selected and applied to the photo-sintering process without restriction.

[0099] In some embodiments, the light energy irradiated per pulse during photo-sintering is 0.1 to 1.0 J / cm 2 It may be. Specifically, the light energy irradiated per pulse during the above photothermal sintering is 0.2 J / cm 2 Above or 0.3 J / cm 2 It may be more than 0.7 J / cm 2 The following is 0.5 J / cm 2 It may be less than.

[0100] In some embodiments, the light energy irradiated during the photo-sintering is 10 to 150 J / cm 2 It may be. Specifically, the light energy irradiated during the above photothermal sintering is 30 J / cm² 2- Above, 50 J / cm 2 or 70 J / cm 2 It may be more than 100 J / cm 2 Less than or equal to 90 J / cm² 2 It may be less than.

[0101] In some embodiments, the oxide-based solid electrolyte sheet may include the lithium-conducting oxide-based particles described above. Additionally, the oxide-based solid electrolyte sheet, as a sheet after sintering, may not further include the organic dye, binder, and / or solvent described above.

[0102] In some embodiments, the oxide-based solid electrolyte sheet may have the aforementioned lithium-conducting oxide-based particles in direct contact with each other, specifically, the lithium-conducting oxide-based particles may be in surface contact with each other. Accordingly, the resistance of the ion transport path is lowered, enabling rapid ion conduction, and durability is increased due to densification, allowing the sheet shape to be well maintained.

[0103] In some embodiments, the oxide-based solid electrolyte sheet is 1.0 x 10 -5 S / cm to 10 -2 It can have an ionic conductivity of S / cm. For example, the ionic conductivity of the oxide-based solid electrolyte sheet is 1.5 x 10⁻⁶ -4 S / cm or greater, 1.7 X 10 -4 S / cm or higher, 3.0 X 10 -4 S / cm or more or 5.0 X 10 -4 It may be greater than S / cm, and 10 -3 It may be less than S / cm. In this case, the above ionic conductivity value may be a value measured at room temperature (25 ℃).

[0104] In some embodiments, the oxide-based solid electrolyte sheet may have a thickness of 10 μm to 300 μm. For example, the thickness of the oxide-based solid electrolyte sheet may be 15 μm or more or 20 μm or more, and 200 μm or less or 100 μm or less. When the thickness of the oxide-based solid electrolyte sheet is within the range described above, the oxide-based solid electrolyte sheet is a thin film having a thin thickness and has excellent ion conductivity, and can improve the energy density of an all-solid-state lithium secondary battery containing it.

[0105] All-solid-state lithium secondary battery

[0106] An all-solid-state lithium secondary battery according to one embodiment includes an oxide-based solid electrolyte sheet according to any one of the embodiments described above. Specifically, the all-solid-state lithium secondary battery may include the oxide-based solid electrolyte sheet described above between the positive electrode and the negative electrode.

[0107] The above anode is not particularly limited. For example, the anode may include an anode current collector; and an anode composite layer on at least one surface of the anode current collector.

[0108] The composition of the anode current collector is not particularly limited. For example, the anode current collector may be a plate or foil composed of one or more of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), and alloys thereof. In some embodiments, the anode current collector may be aluminum foil (Al-foil).

[0109] The thickness of the anode current collector is not particularly limited. For example, the thickness of the anode current collector may be 0.1 μm to 50 μm.

[0110] In some embodiments, the anode composite layer may include an anode active material. The anode active material is not particularly limited to an active material produced from the active material precursor described above, and may include a compound capable of reversibly intercalating and deintercalating lithium ions. For example, the anode active material may include a lithium-nickel metal oxide. The lithium-nickel metal oxide may further include at least one of cobalt (Co), manganese (Mn), and aluminum (Al).

[0111] In some embodiments, the positive electrode active material or the lithium-nickel metal oxide may comprise a layered structure or a crystal structure represented by the following chemical formula 1.

[0112] [Chemical Formula 1]

[0113] Li x Ni a M b O 2+z

[0114] In the above chemical formula 1, 0.9≤x≤1.2, 0.6≤a≤0.99, 0.01≤b≤0.4, and -0.5≤z≤0.1 may be used. As described above, M may include Co, Mn, and / or Al.

[0115] The chemical structure represented by Chemical Formula 1 above represents the bonding relationships included within the layered or crystal structure of the positive electrode active material and does not exclude other additional elements. For example, M includes Co and / or Mn, and Co and / or Mn may be provided as the main active element of the positive electrode active material together with Ni. Chemical Formula 1 above is provided to express the bonding relationships of the main active elements and should be understood as encompassing the introduction and substitution of additional elements.

[0116] In some embodiments, auxiliary elements may be further included in addition to the main active element to enhance the chemical stability of the anode active material or the layered structure / crystalline structure. The auxiliary elements may be incorporated together within the layered structure / crystalline structure to form bonds, and in this case, it should be understood that they are also included within the range of the chemical structure represented by Chemical Formula 1.

[0117] The above auxiliary element may, for example, include at least one of Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Al, Ga, C, Si, Sn, Sr, Ba, Ra, P, or Zr. The above auxiliary element may also act as an auxiliary active element that contributes to the capacity / output activity of the cathode active material together with Co or Mn, such as Al.

[0118] For example, the positive electrode active material or the lithium-nickel metal oxide may include a layered structure or a crystal structure represented by the following chemical formula 1-1.

[0119] [Chemical Formula 1-1]

[0120] Li x Ni a M1 b1 M2 b2 O 2+z

[0121] In Chemical Formula 1-1, M1 may include Co, Mn and / or Al. M2 may include the auxiliary element described above. In Chemical Formula 1-1, 0.9≤x≤1.2, 0.6≤a≤0.99, 0.01≤b1+b2≤0.4, and -0.5≤z≤0.1.

[0122] The above-described positive active material may further include a coating element or a doping element. For example, elements substantially identical or similar to the auxiliary elements described above may be used as coating elements or doping elements. For example, any of the elements described above may be used alone or in combination of two or more as coating elements or doping elements.

[0123] The coating element or doping element may be present on the surface of the lithium-nickel metal oxide particles or penetrate through the surface of the lithium-nickel metal composite oxide particles and be included within the bonding structure represented by Formula 1 or Formula 1-1.

[0124] The above-mentioned positive electrode active material may include a nickel-cobalt-manganese (NCM)-based lithium oxide. In this case, an NCM-based lithium oxide with an increased nickel content may be used.

[0125] The content of Ni in the above NCM-based lithium oxide (e.g., the mole fraction of nickel in the total moles of nickel, cobalt, and manganese) may be 0.6 or more, 0.7 or more, or 0.8 or more. In some embodiments, the content of Ni may be 0.8 to 0.95, 0.82 to 0.95, 0.83 to 0.95, 0.84 to 0.95, 0.85 to 0.95, or 0.88 to 0.95.

[0126] In some embodiments, the positive electrode active material may include a lithium cobalt oxide-based active material, a lithium manganese oxide-based active material, a lithium nickel oxide-based active material, or a lithium iron phosphate (LFP)-based active material (e.g., LiFePO4).

[0127] In some embodiments, the positive electrode active material may include a Mn-rich active material, an LLO (Li-rich layered oxide) / OLO (Over-Lithiated Oxide) active material, or a Co-less active material having a chemical structure or crystal structure represented by Chemical Formula 2.

[0128] [Chemical Formula 2]

[0129] p[Li2MnO3]·(1-p)[Li q JO2]

[0130] Of chemical formula 2, 0 <p<1이고, 0.9≤q≤1.2이며, J는 Mn, Ni, Co, Fe, Cr, V, Cu, Zn, Ti, Al, Mg 및 B 중 적어도 하나의 원소를 포함할 수 있다.

[0131] In some embodiments, the anode composite layer may further include a binder. The binder is not particularly limited. For example, the binder may include one or more of polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate. According to one embodiment, the binder may include polyvinylidene fluoride (PVDF).

[0132] The content of the binder included in the anode composite layer is not particularly limited. For example, the content of the binder included in the anode composite layer may be 0.1 weight% to 10 weight%.

[0133] In some embodiments, the anode composite layer may further include a conductive material. The conductive material is not particularly limited. For example, the conductive material may include one or more types of: graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, carbon nanotube (CNT); metal powder or metal fiber such as copper, nickel, aluminum, or silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives.

[0134] The content of the conductive material included in the anode composite layer is not particularly limited. For example, the content of the conductive material included in the anode composite layer may be 0.1 weight% to 10 weight%.

[0135] The above cathode is not particularly limited. For example, the cathode may include a cathode current collector; and a cathode composite layer on at least one surface of the cathode current collector.

[0136] The composition of the above-mentioned negative current collector is not particularly limited. For example, the above-mentioned negative current collector may be a plate or foil composed of one or more of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), and alloys thereof. In some embodiments, the above-mentioned negative current collector may be a copper foil (Cu-foil).

[0137] The thickness of the above-mentioned cathode current collector is not particularly limited. For example, the thickness of the above-mentioned cathode current collector may be 0.1 μm to 50 μm.

[0138] The above-mentioned cathode composite layer may include a cathode active material. The above-mentioned cathode active material is not particularly limited. For example, the above-mentioned cathode active material may be one or more selected from the group consisting of carbon-based materials such as crystalline carbon, amorphous carbon, carbon composites, and carbon fibers; lithium metal; lithium alloy; silicon-containing materials and tin-containing materials.

[0139] The crystalline carbon mentioned above may be, for example, graphitic carbon such as natural graphite, artificial graphite, graphitized coke, graphitized mesocarbon microbeads (MCMB), or graphitized mesophase pitch-based carbon fiber (MPCF).

[0140] Exemplarily, the above amorphous carbon may be hard carbon, soft carbon, coke, mesocarbon microbeads (MCMB), or mesophase pitch-based carbon fiber (MPCF).

[0141] When the above-mentioned negative electrode active material is lithium metal or a lithium alloy, the negative electrode may be a lithium metal negative electrode or a non-negative electrode. In the above-mentioned lithium metal negative electrode or non-negative electrode, lithium metal or lithium alloy particles may be used as active materials. For example, during charging and discharging, the electrodeposition and desorption reactions of lithium metal, rather than the oxidation and reduction reactions of the electrode active material, may be the main reversible reactions of the lithium secondary battery. The above-mentioned lithium metal negative electrode may include a lithium metal-containing layer. The above-mentioned lithium metal-containing layer may include lithium metal or a lithium metal alloy. The above-mentioned lithium metal-containing layer may be a pure lithium metal or lithium metal alloy layer, or the lithium metal or lithium metal alloy may be contained within a porous storage layer.

[0142] The lithium metal negative electrode may further include a protective layer for inhibiting dendrite growth on the lithium metal-containing layer, or a coating layer between the current collector and the lithium metal-containing layer described later so that lithium metal can be uniformly electrodeposited.

[0143] The elements included in the above lithium alloy may be, for example, aluminum, zinc, bismuth, cadmium, antimony, silicon, lead, tin, gallium, or indium.

[0144] The above silicon-containing material is not particularly limited as long as it contains silicon, and may be an active material capable of alloying with lithium (Li). For example, the above silicon-containing material may be silicon (Si), silicon oxide (SiOx; 0 <x<2), 금속 도핑된 실리콘 산화물(SiOx; 0<x<2), 탄소 코팅된 실리콘 산화물(SiOx; 0<x<2), 실리콘-탄소 복합체(Si-C) 및 실리콘 합금으로 이루어진 군으로부터 선택된 1종 이상일 수 있다.

[0145] The above cathode composite layer may further include a binder. The binder is not particularly limited. For example, the binder may be any one of a rubber-based binder such as styrene-butadiene rubber (SBR), fluororubber, ethylene propylene rubber, butadiene rubber, isoprene rubber, silane rubber; a cellulose-based binder such as carboxymethylcellulose (CMC), hydroxypropylmethylcellulose, methylcellulose, or an alkali metal salt thereof; and a combination thereof.

[0146] The above cathode composite layer may further include a conductive material. The conductive material is not particularly limited. For example, the conductive material may be one or more selected from particulate carbon materials and fibrous carbon materials. The particulate carbon material may be carbon black such as Super-P or Super-C, acetylene black, Ketjen black, etc., and the fibrous carbon material may be carbon fiber, carbon nanotube (CNT), vapor-grown carbon fiber (VGCF), etc.

[0147] Examples

[0148] 1. Preparation of a composition for forming oxide-based solid electrolyte sheets

[0149] 1) Examples 1 to 6

[0150] (1) Example 1

[0151] Tantalum (Ta)-doped lithium lanthanum zirconium oxide (LLZTO) particles (D50: approx. 200 nm) were prepared as lithium conductive oxide-based particles by the sol-gel method. The LLZTO has a maximum absorption wavelength (λ) in the wavelength range of 600 nm to 780 nm, specifically at approx. 700 nm. max An organic dye (Sigma-Aldrich; Disperse Red 19) and a binder (polyvinyl butyral (PVB)) having LLZTO were mixed with a solvent (toluene and isopropyl alcohol (IPA)) to prepare an oxide-based solid electrolyte sheet-forming composition of Example 1, wherein the content of LLZTO was 48 wt% and the total content of the organic dye was 1 wt% based on the total weight of the oxide-based particles.

[0152] (2) Example 2

[0153] In the same manner as in Example 1, a composition for forming an oxide-based solid electrolyte sheet of Example 2 was prepared, wherein the content of LLZTO was 48 wt% and the total content of organic dye was 0.5 wt% based on the total weight of the oxide-based particles.

[0154] (3) Example 3

[0155] In the same manner as in Example 1, a composition for forming an oxide-based solid electrolyte sheet of Example 3 was prepared, wherein the content of LLZTO was 48 wt% and the total content of organic dye was 0.25 wt% based on the total weight of the oxide-based particles.

[0156] (4) Example 4

[0157] The oxide-based solid electrolyte sheet forming composition of Example 4 was prepared in the same manner as Example 1, except that the total content of the organic dye was adjusted to 0.1% by weight based on the total weight of the oxide-based particles.

[0158] (5) Example 5

[0159] A composition for forming an oxide-based solid electrolyte sheet of Example 5 was prepared in the same manner as in Example 1, except that the total content of the organic dye was adjusted to 10% by weight based on the total weight of the oxide-based particles.

[0160] (6) Example 6

[0161] Li as lithium conductive oxide-based particles 1.3 Al 0.3 Ti 1.7 The oxide-based solid electrolyte sheet forming composition of Example 6 was prepared in the same manner as in Example 1, except that a lithium aluminum titanium phosphate (LATP)-based compound (D50: about 300 nm) represented by the chemical formula (PO4)3 was used.

[0162] 2) Comparative Example

[0163] (1) Comparative Example 1

[0164] A composition for forming an oxide-based solid electrolyte sheet of Comparative Example 1 was prepared in the same manner as in Example 1, except that an inorganic pigment (Fe2O3) was added instead of an organic dye.

[0165] (2) Comparative Example 2

[0166] Wavelength region below 500 nm, specifically the maximum absorption wavelength (λ) at 350 nm max A composition for forming an oxide-based solid electrolyte sheet of Comparative Example 2 was prepared in the same manner as in Example 1, except that an organic dye (Pigment Yellow 138) having ) was used.

[0167] (3) Comparative Example 3

[0168] Wavelength region exceeding 800 nm, specifically the maximum absorption wavelength (λ) at 810 nm max A composition for forming an oxide-based solid electrolyte sheet of Comparative Example 3 was prepared in the same manner as in Example 1, except that an organic dye (Pigment Violet PV23) having ) was used.

[0169] 2. Manufacturing of oxide-based solid electrolyte sheets

[0170] Green sheets were prepared by casting the compositions of the examples and comparative examples prepared according to the above onto one side of a stainless steel substrate (SUS foil) and drying them (see Fig. 2). Subsequently, the sheets were sintered using a photothermal sintering device (NovaCentrix, PulseForge®1300) at a pulse of 0.4 J / cm² for 5 seconds. 2 The photothermal sintering process, which irradiates light energy, was repeated 200 times for a total of 80 J / cm² 2 Light energy was irradiated. The specific photo-sintering process conditions are as shown in Table 1 below. Through this photo-sintering process, an oxide-based solid electrolyte sheet with a thickness of approximately 27 μm (excluding the thickness of the SUS foil) was manufactured (see Fig. 3).

[0171] Photo-sintering Conditions Conditions constituting a pulse Voltage: 300 V On-time: 3000 μs Duty Cycle: 60% Number of cycles: 10 Operating Conditions Firing Frequency: 40 Hz Number of repetitions: 200 Light energy irradiated per pulse: 0.4 J / cm² 2 Total irradiated light energy 80 J / cm 2

[0172] 3. Evaluation of Oxide-based Solid Electrolyte Sheets

[0173] 1. Degree of PCB damage

[0174] The results of evaluating the degree of damage to the substrate by visually observing the surface of the manufactured oxide-based solid electrolyte sheet (see Fig. 4) are shown in Table 2 below. Specifically, the degree of damage was evaluated as 'large' when the surface of the substrate opposite to the side where the oxide-based solid electrolyte sheet is formed was oxidized to brown and severely discolored, the degree of damage was evaluated as 'medium' when the color change of the substrate was not significant, and the degree of damage was evaluated as 'small' when there was no color change of the substrate.

[0175] 2. Ion Conductivity Analysis

[0176] Electrochemical impedance analysis was performed on the manufactured oxide-based solid electrolyte sheet using a potentiostat (VMP-300) in an atmospheric environment at room temperature (25℃) (see Fig. 5), and the resistance components of the example and comparative example were measured. The ionic conductivity was calculated and compared according to Equation 2 below, and the results are shown in Table 2 below.

[0177] [Equation 2]

[0178] σ = D / (RXS)

[0179] In Equation 2 above, σ is the ionic conductivity value (S / cm), D is the thickness (cm) of the oxide-based solid electrolyte sheet, R is the measured impedance resistance value (1 / S), and S is the area (cm²) of the oxide-based solid electrolyte sheet. 2 )am.

[0180] 3. Sheet Surface Analysis

[0181] Images of the surface of the prepared oxide-based solid electrolyte sheets observed using a Differential Interference Contrast Microscopy (DIC) are shown in FIG. 6 (Comparative Example 1) and FIG. 7 (Example 1), respectively. Surface cracks caused by photo-sintering were observed in the sheet of Comparative Example 1 and were marked with ○ in Table 1 below, while almost no cracks were observed in the sheet of Example 1 and were marked with X in Table 2 below. Cases where localized cracks were observed on the surface were marked with △.

[0182] Degree of Substrate Damage Ion Conductivity (S / cm) Presence of Sheet Surface Cracks Comparison Example 1 vs 1.68 X 10 -4 ○ Comparative Example 2 Small 2.50 X 10 -6 ×Comparative Example 3 Small 3.76 X 10 -6 ×6.05 X 10 in Example 1 -4 ×Example 2 Small 1.73 X 10 -4 ×Example 3 Small 1.58 X 10 -4 ×Example 4 Small 9.76 X 10-5 × 5.45 X 10 in Example 5 -5 △Example 6 Small 2.47 X 10 -4 ×

[0183] Referring to Table 2 above, it can be seen that the sheet of Comparative Example 1 containing an inorganic pigment has a relatively greater degree of damage to the substrate compared to the sheets of Examples 1 to 6 containing an organic dye. In addition, unlike the sheet of Comparative Example 1, it was found that no cracks occurred on the surface of the sheet of Example 1.

[0184] Meanwhile, in the case of Comparative Examples 2 and 3, effective sintering did not occur because the amount of energy absorbed by the organic dye used was less than that of the composition of Example 1, which absorbs energy in the 500 nm to 800 nm range, and accordingly, significantly low ionic conductivity was exhibited.

[0185] Meanwhile, it can be confirmed that the sheet of Example 1 containing an organic dye has an ionic conductivity at least three times higher than that of the sheet of Comparative Example 1 containing the same amount of inorganic pigment. In addition, it can be confirmed that the sheets of Examples 2 and 3, which have a relatively low content of organic dye, have an ionic conductivity similar to that of the Comparative Example despite having a low degree of substrate damage. These results are attributed to the fact that, unlike inorganic pigments, the organic dye dissolved in the composition colors the lithium-conductive oxide-based particles themselves and induces uniform heat transfer between particles during photo-sintering, thereby improving the sintering uniformity of the sheet.

[0186] In addition, in the case of Example 4, which contained 0.1 wt% of organic dye based on the total weight of oxide particles, the photothermal sintering was insufficient, resulting in lower ionic conductivity compared to Example 1, and in the case of Example 5, which contained 10 wt% of organic dye based on the total weight of oxide particles, photothermal sintering proceeded more than in Example 1, and localized cracking was observed on the sheet surface. Furthermore, in the case of Example 6, which used LATP as the oxide-based particle, lower ionic conductivity was observed compared to Example 1.

[0187] The present disclosure may also relate to the following aspects.

[0188] Aspect 1) A composition for forming an oxide-based solid electrolyte sheet comprises lithium-conducting oxide-based particles and a dye material, wherein the dye material comprises at least one of an organic dye and an organometallic dye, and the dye material has a maximum absorption wavelength (λ) in the wavelength region of 500 nm to 800 nm. max It may have ).

[0189] Aspect 2) In Aspect 1, the dye material has a maximum absorption wavelength (λ) in the wavelength range of 600 nm to 780 nm. max Can have ).

[0190] Aspect 3) In aspect 1 or 2, the total content of the dye material may be greater than 0.1 weight% and less than 10 weight% based on the total weight of the lithium conductive oxide-based particles.

[0191] Side 4) In any one of sides 1 to 3, the lithium conductive oxide-based particles may include at least one selected from a garnet compound, a NASICON compound, and a perovskite compound.

[0192] Side 5) In any one of sides 1 to 4, the average particle size (D50) of the lithium conductive oxide-based particles may be 100 nm to 10 μm.

[0193] Side 6) In any one of Sides 1 to 5, the oxide-based solid electrolyte sheet forming composition may further include a binder.

[0194] Side 7) In Side 6, the binder may comprise at least one selected from the group consisting of polyacrylic resin, ethyl cellulose, methyl cellulose and polyvinyl butyral resin, polyvinylidene fluoride, alkyl carboxylic acid monomers and ethylenically unsaturated carboxylic acid monomers.

[0195] Side 8) A method for manufacturing an oxide-based solid electrolyte sheet may include the step of forming an oxide-based solid electrolyte green sheet by applying and drying a composition for forming an oxide-based solid electrolyte sheet according to any one of Sides 1 to 7 onto a substrate surface; and the step of photo-sintering the green sheet.

[0196] Side 9) The oxide-based solid electrolyte green sheet comprises lithium-conductive oxide-based particles and dye material, and

[0197] The above dye material comprises at least one of an organic dye and an organometallic dye, and

[0198] The above dye material has a maximum absorption wavelength (λ) in the wavelength range of 500 nm to 800 nm. max It may have ).

[0199] Side 10) In Side 9, the oxide-based solid electrolyte green sheet may further include a binder.

[0200] Side 11) An oxide-based solid electrolyte sheet can be manufactured using a composition for forming an oxide-based solid electrolyte sheet according to any one of Sides 1 to 7.

[0201] Side 12) In Side 11, the oxide-based solid electrolyte sheet is 1.0 x 10 -5 S / cm to 10 -2 It can have an ionic conductivity of S / cm.

[0202] Side 13) In side 11 or 12, the oxide-based solid electrolyte sheet may have a thickness of 10 μm to 300 μm.

[0203] Side 14) In any one of sides 11 to 13, the oxide-based solid electrolyte sheet may include lithium-conducting oxide-based particles in surface contact with each other.

[0204] Side 15) An all-solid-state lithium secondary battery may include an oxide-based solid electrolyte sheet according to any one of Sides 11 to 14.

Claims

1. As a composition for forming an oxide-based solid electrolyte sheet, The above-mentioned oxide-based solid electrolyte sheet forming composition comprises lithium-conductive oxide-based particles and a dye material, and The above dye material comprises at least one of an organic dye and an organometallic dye, and The above dye material has a maximum absorption wavelength (λ) in the wavelength range of 500 nm to 800 nm. max having, Composition for forming oxide-based solid electrolyte sheets.

2. In Paragraph 1, The above dye material has a maximum absorption wavelength (λ) in the wavelength range of 600 nm to 780 nm. max having, Composition for forming oxide-based solid electrolyte sheets.

3. In Paragraph 1, The total content of the dye material is greater than 0.1 weight% and less than 10 weight% based on the total weight of the lithium conductive oxide-based particles. Composition for forming oxide-based solid electrolyte sheets.

4. In Paragraph 1, The above lithium conductive oxide-based particles comprise at least one selected from garnet compounds, NASICON compounds, and perovskite compounds, Composition for forming oxide-based solid electrolyte sheets.

5. In Paragraph 1, The average particle size (D50) of the above lithium conductive oxide-based particles is 100 nm to 10 μm, Composition for forming oxide-based solid electrolyte sheets.

6. In Paragraph 1, including additional binder, Composition for forming oxide-based solid electrolyte sheets.

7. In Paragraph 6, The above binder comprises at least one selected from the group consisting of polyacrylic resin, ethyl cellulose, methyl cellulose and polyvinyl butyral resin, polyvinylidene fluoride, alkyl carboxylic acid monomers and ethylenically unsaturated carboxylic acid monomers. Composition for forming oxide-based solid electrolyte sheets.

8. A step of forming an oxide-based solid electrolyte green sheet by applying and drying an oxide-based solid electrolyte sheet forming composition according to any one of claims 1 to 7 onto a substrate surface; and A step comprising the photo-sintering step of the above green sheet, Method for manufacturing oxide-based solid electrolyte sheets.

9. Includes lithium conductive oxide-based particles and dye materials, The above dye material comprises at least one of an organic dye and an organometallic dye, and The above dye material has a maximum absorption wavelength (λ) in the wavelength range of 500 nm to 800 nm. max Oxide-based solid electrolyte green sheet having ).

10. In Paragraph 9, Oxide-based solid electrolyte green sheet containing a binder.

11. An oxide-based solid electrolyte sheet manufactured from a composition for forming an oxide-based solid electrolyte according to any one of claims 1 to 7.

12. In Paragraph 11, 1.0 x 10 -5 S / cm to 10 -2 having an ionic conductivity of S / cm, Oxide-based solid electrolyte sheet.

13. In Paragraph 11, Having a thickness of 10 μm to 300 μm, Oxide-based solid electrolyte sheet.

14. In Paragraph 11, Comprising lithium conductive oxide-based particles in surface contact with each other, Oxide-based solid electrolyte sheet.

15. A sheet of oxide-based solid electrolyte according to paragraph 11, All-solid-state lithium secondary battery.

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