Method for recycling all-solid-state rechargeable battery materials

Abstract

The present invention relates to a method for recycling all-solid-state rechargeable battery materials, the method comprising: heat-treating all-solid-state rechargeable battery materials, including lithium-containing materials and sulfide-based solid electrolytes, to convert same into lithium-recovery materials including lithium sulfate; and mixing the product of the heat treatment with an aqueous solvent to extract the lithium-recovery materials.

Description

Recycling method for all-solid-state secondary battery materials

[0001] This relates to a method for recycling all-solid-state secondary battery materials.

[0002] Lithium-ion batteries, which offer high energy density and portability, are primarily used as the power source for mobile information terminals such as mobile phones, laptops, and smartphones. Recently, active research is being conducted to utilize high-energy-density lithium-ion batteries as power sources for driving or energy storage in hybrid and electric vehicles.

[0003] Since commercially available lithium-ion batteries use electrolytes containing flammable organic solvents, there are safety issues where the battery may explode or catch fire in the event of collisions or penetrations.

[0004] Accordingly, all-solid-state secondary batteries utilizing solid electrolytes instead of liquid electrolytes are being proposed. All-solid-state secondary batteries are composed entirely of solid materials; they offer the advantages of safety by eliminating risks such as explosions caused by electrolyte leakage, and facilitate the fabrication of thin batteries. Furthermore, the reduction in negative electrode thickness enables improved high-speed charging and discharging performance, as well as the realization of high-voltage operation and high energy density.

[0005] One embodiment aims to provide an eco-friendly recycling method for all-solid-state secondary battery materials that can suppress or reduce the generation of toxic substances while improving the lithium recovery rate.

[0006] One embodiment provides a method for recycling an all-solid-state secondary battery material comprising heat-treating an all-solid-state secondary battery material containing a lithium-containing material and a sulfide-based solid electrolyte to convert it into a lithium recovery material containing lithium sulfate, and mixing the result of the heat treatment with an aqueous solvent to extract the lithium recovery material.

[0007] According to one embodiment, a method for recycling all-solid-state secondary battery materials can be provided that can suppress or reduce the generation of toxic substances while improving the lithium recovery rate and is environmentally friendly.

[0008] FIGS. 1 to 3 are cross-sectional views schematically illustrating an all-solid-state secondary battery according to one embodiment.

[0009] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0010] Unless otherwise specifically stated in this specification, when a part such as a layer, film, region, plate, etc. is described as being "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between.

[0011] Unless otherwise specified in this specification, a singular form may also include a plural form. Additionally, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B."

[0012] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0013] Unless otherwise defined in this specification, particle size may be the average particle size. Additionally, particle size refers to the average particle size (D) which means the diameter of the particle whose cumulative volume in the particle size distribution is 50 volume%. 50 It means ). Average particle size (D 50The measurement can be performed using methods widely known to those skilled in the art, for example, by using a particle size analyzer, or by using transmission electron microscope (TEM) or scanning electron microscope (SEM) images. Alternatively, the measurement may be performed using a measuring device utilizing dynamic light scattering, and after analyzing the data to count the number of particles for each particle size range, the average particle size (D) is calculated from this. 50 ) values ​​can be obtained. Alternatively, it can be measured using the laser diffraction method. When measuring by the laser diffraction method, for example, after dispersing the particles to be measured in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), and ultrasound at approximately 28 kHz is irradiated at an output of 60 W. Then, the average particle size (D) at the 50% reference of the particle size distribution in the measuring device is 50 ) can be produced.

[0014] The terms "include," "equip," or "have" used herein are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0015] In addition, the term “layer” here includes not only shapes formed on the entire surface when viewed in a plan view, but also shapes formed on some surfaces.

[0016] The term “metal” is interpreted as a concept that includes ordinary metals, transition metals, and metalloids (semimetals).

[0017] Recycling method for all-solid-state secondary battery materials

[0018] One embodiment provides a method for recycling an all-solid-state secondary battery material comprising heat-treating an all-solid-state secondary battery material containing a lithium-containing material and a sulfide-based solid electrolyte to convert it into a lithium recovery material containing lithium sulfate, and mixing the result of the heat treatment with an aqueous solvent to extract the lithium recovery material.

[0019] All-solid-state secondary batteries contain a large amount of useful resources and require recycling through various methods. In particular, all-solid-state secondary batteries containing sulfide-based solid electrolytes contain a large amount of sulfur (S) elements, so technologies for removing and treating them are being considered. However, these technologies can also emit toxic substances such as secondary waste or hydrogen sulfide (H2S), making it difficult to view them as environmentally friendly methods.

[0020] Sulfide-based solid electrolytes included in all-solid-state secondary battery materials generate toxic substances such as hydrogen sulfide (H2S) when exposed to environments containing water or moisture. Consequently, all-solid-state secondary batteries containing sulfide-based solid electrolytes face the problem of being difficult to apply to general recycling processes, and require a dry room with minimal reaction and extreme moisture control during handling.

[0021] In other words, there is a limitation in that recycling all-solid-state secondary battery materials containing sulfide-based solid electrolytes requires a process to remove hydrogen sulfide (H2S) in advance, or a dry room to prevent exposure to air or moisture-containing atmospheres during handling.

[0022] However, since it is inevitable that all-solid-state secondary battery materials containing sulfide-based solid electrolytes will be exposed to an environment containing air or moisture during handling when recycling, one embodiment proposes a method for recycling all-solid-state secondary battery materials that can solve the aforementioned problems.

[0023] One embodiment proposes a recycling method that actively utilizes sulfur (S) contained in an all-solid-state secondary battery material containing a sulfide-based solid electrolyte, wherein the lithium contained in the cathode active material or the sulfide-based solid electrolyte is converted into lithium sulfate (Li2SO4) having high solubility using a dry method, and then the lithium can be pre-extracted at a high concentration through water leaching.

[0024] A recycling method for all-solid-state cell materials according to one embodiment improves upon the problems of the existing lithium pre-extraction method and develops an eco-friendly recycling method capable of converting the sulfur (S) itself, which can generate secondary waste, into lithium sulfate (Li2SO4) by consuming it, and selectively extracting the lithium contained in the cell by leaching it into an aqueous solvent.

[0025] A method for recycling all-solid-state secondary battery materials according to one embodiment includes the following process.

[0026] First, an all-solid-state secondary battery material containing a lithium-containing material and a sulfide-based solid electrolyte is heat-treated to convert it into a lithium recovery material containing lithium sulfate.

[0027] In one embodiment, the lithium-containing material may be a positive electrode active material containing lithium. In this case, the following description regarding all-solid-state secondary batteries can be applied equally to the positive electrode active material, and the following description regarding all-solid-state secondary batteries can be applied equally to the sulfide-based solid electrolyte; therefore, a detailed description is omitted here.

[0028] For example, the all-solid-state secondary battery material may include an all-solid-state secondary battery cell, an all-solid-state secondary battery module, an all-solid-state secondary battery pack, all-solid-state secondary battery process scrap, an all-solid-state secondary battery decomposition product, or a combination thereof. According to one embodiment, the cell, pack, module, process scrap, or combination thereof of the all-solid-state secondary battery may be fed in whole to carry out the recycling process, or the decomposition product obtained by decomposing the electrode plate of the all-solid-state secondary battery may be fed in to carry out the recycling process. Therefore, according to one embodiment, since it is not necessary to preemptively subject the all-solid-state secondary battery material to various process treatments or to separately require an additional toxic substance treatment process, the cost required for recycling the all-solid-state secondary battery material can be effectively reduced.

[0029] A recycling method for an all-solid-state secondary battery material according to one embodiment is based on the discovery that by heat-treating an all-solid-state secondary battery material containing a lithium-containing positive active material and a sulfide-based solid electrolyte, the lithium-containing positive active material and the sulfide-based solid electrolyte can react and be converted into lithium sulfate, thereby providing a new lithium pre-extraction method capable of selectively extracting lithium. Through the heat treatment, the lithium-containing positive active material and the sulfide-based solid electrolyte can react and be converted into lithium sulfate with high solubility. Since lithium sulfate has a solubility more than 20 times higher than that of materials such as lithium carbonate (Li2CO3), lithium hydrogen bicarbonate (LiHCO3), and lithium hydroxide (LiOH) that can be recovered through conventional lithium pre-extraction methods, not only can the amount of water used be drastically reduced, but the lithium recovery rate can also be improved compared to conventional lithium pre-extraction methods.

[0030] According to the aforementioned recycling method, by including the lithium-containing cathode active material and sulfide-based solid electrolyte during the heat treatment, the lithium contained in the lithium-containing cathode active material and sulfide-based solid electrolyte within the battery can be converted into lithium sulfate (Li2SO4) or lithium recovery materials including lithium sulfate and lithium chloride (LiCl) without separately removing hydrogen sulfide, which is difficult to handle. Through this, the release of hydrogen sulfide (H2S) that may occur during the recycling process of all-solid-state secondary battery materials can be suppressed or reduced. At the same time, by using the hydrogen sulfide (H2S) itself that may occur during the recycling process as a raw material for the reaction, the problem of existing technologies requiring a separate hydrogen sulfide removal process can be resolved. Furthermore, the lithium sulfate obtained from the heat treatment has a higher solubility compared to conventional lithium pre-extraction methods, allowing for the application of the water leaching process described later using less water, thereby enabling the recycling of all-solid-state secondary battery materials in an environmentally friendly manner.

[0031] In one embodiment, the heat treatment may be performed as a dry process. Since toxic substances such as hydrogen sulfide (H2S) are generated when a sulfide-based solid electrolyte included in an all-solid-state secondary battery material is exposed to an environment containing water or moisture, the recycling method for the all-solid-state battery material according to one embodiment can suppress or reduce the generation of hydrogen sulfide by performing the heat treatment as a dry process without using a separate solvent, thereby enabling the application of an environmentally friendly recycling method.

[0032] In one embodiment, the heat treatment may be performed in a temperature range of 150°C to 750°C, 200°C to 700°C, 300°C to 600°C, or 300°C to 500°C, and / or under conditions satisfying the aforementioned temperatures, it may be performed for 10 minutes to 10 hours, 30 minutes to 5 hours, or 1 hour to 3 hours. When this is satisfied, the bonds within the positive electrode active material, which is a lithium-containing material, are effectively broken to effectively convert not only the lithium contained in the sulfide-based solid electrolyte but also the lithium contained in the positive electrode active material into lithium sulfate, thereby increasing the conversion rate of lithium and, accordingly, improving the lithium recovery rate.

[0033] For example, the heat treatment may be performed under an atmosphere containing oxygen, nitrogen, carbon dioxide, hydrogen, or a combination thereof, or in an oxygen atmosphere, for example, in an atmosphere containing 0 to 30 volume% or 10 to 30 volume% of oxygen, or in an atmospheric atmosphere. If these conditions are met, the lithium-containing positive electrode active material and the sulfide-based solid electrolyte can be effectively converted into lithium sulfate through a reaction during the heat treatment.

[0034] For example, in order to maximize the lithium recovery rate by recovering not only the lithium of the sulfide-based solid electrolyte but also the lithium of the cathode active material which is the lithium-containing material, the method may further include adding a sulfur-containing material and a chlorine-containing material during the heat treatment. For example, hydrogen sulfide (H2S) gas may be used as the sulfur-containing material, and chlorine (Cl2) gas may be used as the chlorine-containing material.

[0035] In one embodiment, prior to the heat treatment, the all-solid-state secondary battery material may be fed into a crushing and grinding device to perform crushing and grinding. By further including the aforementioned crushing and grinding process, the reaction surface area between the lithium-containing positive electrode active material and the sulfide-based solid electrolyte within the all-solid-state secondary battery material is increased, which may be advantageous for securing a high lithium recovery rate.

[0036] For example, the crushing and grinding can be performed such that the maximum length of the all-solid-state secondary battery material fed into the crushing and grinding device satisfies 0.1 cm to 10 cm, and, for example, such that the all-solid-state secondary battery material fed into the device satisfies a square shape with a side length of 0.1 cm to 10 cm. Within this range, the reaction area between the positive electrode active material, which is a lithium-containing material, and the sulfide-based solid electrolyte within the all-solid-state secondary battery material can be effectively increased to promote the reaction, further improve the conversion rate to lithium sulfate, and increase the lithium recovery rate.

[0037] Next, the product of the heat treatment is mixed with an aqueous solvent to extract the lithium recovery material.

[0038] For example, the above-mentioned aqueous solvent may include water, sodium hydroxide, lithium hydroxide, or a combination thereof. If this is satisfied, the water leaching of the lithium recovery material containing the lithium sulfate can be effectively performed, and the recovery rate of the lithium recovery material can be increased.

[0039] In one embodiment, the extraction can be performed by solid-liquid separation. Through the extraction process, lithium sulfate with easy handling and high solubility can be obtained in the form of a solution.

[0040] For example, among the results of the solid-liquid separation, a solid powder from which lithium has been removed in the solid phase can be recovered, and among the results of the solid-liquid separation, a solution containing a lithium recovery material in the liquid phase can be recovered, and the solution may contain lithium sulfate as the lithium recovery material. In this case, the solid powder from which lithium has been removed may refer to the solid powder remaining after lithium has been removed by recovering lithium into the liquid phase through the solid-liquid separation.

[0041] For example, in addition to the aforementioned lithium sulfate (Li2SO4), the lithium recovery material recoverable from the above solution may further include lithium chloride (LiCl), lithium carbonate (Li2CO3), lithium hydrogen bicarbonate (LiHCO3), lithium hydroxide (LiOH), lithium phosphate (Li3PO4), or a combination thereof. While one embodiment is meaningful in that it recovers lithium sulfate, which is easy to handle and has high solubility, the overall lithium recovery rate can be further improved by additionally recovering the aforementioned examples as lithium recovery materials in addition to lithium sulfate.

[0042] In one embodiment, the lithium recovery rate recovered from the lithium recovery material may be 70% or more, 80% or more, or 85% or more, and the lithium recovery rate may be defined by the following Equation 1. At this time, the lithium recovery rate may be measured based on weight, and since the units of the amount of recovered lithium R1 and the amount of lithium contained in the all-solid-state secondary battery material R2 in the following Equation 1 only need to match each other, the units of R1 and R2 are not specifically limited.

[0043] [Equation 1]

[0044] Lithium recovery rate = (R1 / R2)×100

[0045] In the above Equation 1, R1 represents the amount of recovered lithium, and R2 represents the amount of lithium contained in the all-solid-state secondary battery material.

[0046] All-solid-state secondary battery

[0047] In a method for recycling an all-solid-state secondary battery material according to one embodiment, the all-solid-state secondary battery of the all-solid-state secondary battery material may include the aforementioned positive electrode; a negative electrode; and a solid electrolyte membrane located between the positive electrode and the negative electrode.

[0048] FIG. 1 is a cross-sectional view of an all-solid-state secondary battery according to one embodiment. Referring to FIG. 1, the all-solid-state secondary battery (100) may have a structure in which an electrode assembly is housed in a battery case, wherein the electrode assembly is stacked and includes a negative electrode (400) comprising a negative electrode current collector (401) and a negative electrode active material layer (403); a solid electrolyte membrane (300); and a positive electrode (200) comprising a positive electrode active material layer (203) and a positive electrode current collector (201). The all-solid-state secondary battery (100) may further include an elastic sheet (500) on the outer side of at least one of the positive electrode (200) and the negative electrode (400). FIG. 1 illustrates a unit cell comprising a cathode (400), a solid electrolyte membrane (300), and a positive electrode (200). However, as illustrated in FIG. 3, a solid-state secondary battery may be manufactured by stacking two unit cells, or by stacking two or more unit cells, for example, 2 to 100, 3 to 50, 4 to 20, etc. Additionally, the unit cell may include one or more cathodes, and likewise may include one or more solid electrolyte membranes and one or more positive electrodes. For example, the unit cell may be a monocell with a positive electrode / solid electrolyte membrane / cathode structure, or a bicell with a negative electrode / solid electrolyte membrane / positive electrode / solid electrolyte membrane / cathode structure.

[0049] anode

[0050] In one embodiment, it includes an anode current collector and an anode active material layer formed on the anode current collector. The anode active material layer includes the aforementioned anode active material and may further include a solid electrolyte, and may further include a binder and a conductive material.

[0051] positive electrode active material

[0052] The above-mentioned positive electrode active material may be applied without limitation as long as it is commonly used in all-solid-state secondary batteries, for example, a compound capable of reversible intercalation and deintercalation of lithium may be used, may include a lithium transition metal complex oxide, and may include a compound represented by any one of the following chemical formulas. a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Lia Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).

[0053] The above-mentioned positive electrode active material may include, for example, lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt oxide (NC), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium nickel manganese oxide (NM), lithium manganese oxide (LMO), lithium iron phosphate oxide (LFP), or a combination thereof.

[0054] The above positive active material may include, for example, a lithium nickel-based oxide represented by the following chemical formula 1, a lithium cobalt-based oxide represented by the following chemical formula 2, a lithium iron phosphate-based compound represented by the following chemical formula 3, a cobalt-free lithium nickel-manganese-based oxide represented by the following chemical formula 4, or a combination thereof.

[0055] [Chemical Formula 1]

[0056] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0057] In the above chemical formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, 0≤z1≤0.7, 0.9≤x1+y1+z1≤1.1, and 0≤b1≤0.1, and M 1 and M 2Each is independently Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zr, or a combination thereof, and X is F, P, S, or a combination thereof.

[0058] In the above chemical formula 1, 0.6≤x1≤1, 0≤y1≤0.4, and 0≤z1≤0.4, or 0.8≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.2.

[0059] [Chemical Formula 2]

[0060] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0061] In the above chemical formula 2, 0.9≤a2≤1.8, 0.7≤x2≤1, 0≤y2≤0.3, 0.9≤x2+y2≤1.1, and 0≤b2≤0.1, and M 3 is Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, Zr, or a combination thereof, and X is F, P, S, or a combination thereof.

[0062] [Chemical Formula 3]

[0063] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0064] In the above chemical formula 3, 0.9≤a3≤1.8, 0.6≤x3≤1, 0≤y3≤0.4, and 0≤b3≤0.1, and M 4 is Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, Zr, or a combination thereof, and X is F, P, S, or a combination thereof.

[0065] [Chemical Formula 4]

[0066] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0067] In the above chemical formula 4, 0.9≤a2≤1.8, 0.8≤x4<1, 0 <y4≤0.2, 0≤z4≤0.2, 0.9≤x4+y4+z4≤1.1, 및 0≤b4≤0.1이고 M 5 is Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zr, or a combination thereof, and X is F, P, S, or a combination thereof.

[0068] The above positive active material may be in the form of particles, and the average particle size (D) of the above positive active material 50 ) may be 1 μm to 25 μm, for example, 3 μm to 25 μm, 1 μm to 20 μm, 1 μm to 18 μm, 3 μm to 15 μm, or 5 μm to 15 μm. As an example, the anode active material has an average particle size (D 50 Fine particles with a diameter of 1 μm to 9 μm and an average particle size (D 50 It may include atoms having a particle size range of 10 μm to 25 μm. A positive electrode active material having this particle size range can be harmoniously mixed with other components within the positive electrode active material layer and can achieve high capacity and high energy density. Here, the average particle size is determined by selecting approximately 20 arbitrary particles from a scanning electron microscope image of the positive electrode active material, measuring their particle sizes (diameter, major axis, or length of the major axis), obtaining a particle size distribution, and determining the diameter (D) of the particle whose cumulative volume is 50 volume% in the particle size distribution. 50 It may be that ) was taken as the average particle size.

[0069] The above positive active material may be in the form of secondary particles formed by the aggregation of a plurality of primary particles, or in the form of single particles. In addition, the above positive active material may be spherical or have a shape close to spherical, or may be polyhedral or irregular in shape.

[0070] Meanwhile, the above-mentioned positive electrode active material may include a buffer layer on the particle surface. The buffer layer may be described as a coating layer, a protective layer, etc., and may serve to lower the interfacial resistance between the positive electrode active material and the solid electrolyte particles. As an example, the buffer layer may include a lithium metal oxide, wherein the metal may be, for instance, Al, B, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ta, V, W, Zr, or a combination thereof. The lithium metal oxide is excellent at lowering the interfacial resistance between the positive electrode active material and the solid electrolyte particles while improving the performance of the positive electrode active material by facilitating the movement of lithium ions and electron conduction.

[0071] The above positive active material may be included in an amount of 55% to 99% by weight with respect to 100% by weight of the above positive active material layer, for example, 65% to 95% by weight, or 75% to 95% by weight.

[0072] solid electrolyte

[0073] The solid electrolyte included in the above-mentioned positive electrode active material layer may include a sulfide-based solid electrolyte, and in addition to the sulfide-based solid electrolyte, it may further include an oxide-based solid electrolyte, a halide-based solid electrolyte, or a combination thereof. The same description as described below with respect to the solid electrolyte membrane may be applied to the solid electrolyte included in such a positive electrode active material layer.

[0074] With respect to 100 weight% of the above positive active material layer, the solid electrolyte may be included in an amount of 0.1 weight% to 35 weight%, for example, 1 weight% to 35 weight%, 5 weight% to 30 weight%, 8 weight% to 25 weight%, or 10 weight% to 20 weight%.

[0075] In addition, regarding the total weight of the positive active material and the solid electrolyte in the positive active material layer, 65% to 99% by weight of the positive active material and 1% to 35% by weight of the solid electrolyte may be included, for example, 80% to 90% by weight of the positive active material and 10% to 20% by weight of the solid electrolyte may be included. When the solid electrolyte is included in the positive electrode in such a content, the efficiency and lifespan characteristics of the all-solid-state battery can be improved without reducing the capacity.

[0076] bookbinder

[0077] The above binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Representative examples include polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc., but are not limited thereto.

[0078] The content of the binder in the above positive active material layer may be approximately 0.1% to 5% by weight with respect to 100% by weight of the positive active material layer.

[0079] Challenge

[0080] The above positive active material layer may further include a conductive material. The conductive material is used to impart conductivity to the electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.; metal-based materials in the form of metal powder or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or conductive materials including mixtures thereof.

[0081] The content of the conductive material in the above positive active material layer may be 0% to 3% by weight, 0.01% to 2% by weight, or 0.1% to 1% by weight with respect to 100% by weight of the positive active material layer.

[0082] Aluminum foil may be used as the anode current collector, but is not limited thereto.

[0083] cathode

[0084] A negative electrode for an all-solid-state secondary battery according to one embodiment comprises a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector. The negative electrode active material layer comprises a negative electrode active material and may further comprise a binder and / or a conductive material. Alternatively, the negative electrode active material layer may optionally further comprise the aforementioned solid electrolyte.

[0085] The above-mentioned negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0086] A material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0087] As the above lithium metal alloy, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, Sn, or a combination thereof may be used.

[0088] As a material capable of doping and undoping the above lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used, and the Si-based negative electrode active material may include silicon, a silicon-carbon composite, or SiO₂. x(0 <x≤2), Si-Q 합금(상기 Q는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 또는 이들의 조합에서 선택되는 원소이며, Si은 아님), 상기 Sn계 음극 활물질로는 Sn, SnO2, Sn-R 합금(상기 R은 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 또는 이들의 조합에서 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 상기 원소 Q 및 R로는 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, 또는 이들의 조합에서 선택되는 것을 사용할 수 있다.

[0089] For example, the negative electrode active material may include silicon-carbon composite particles. The average particle size (D) of the silicon-carbon composite particles 50 ) can be, for example, 0.5 μm to 20 μm. The average particle size (D 50 ) refers to the diameter of a particle whose cumulative volume in the particle size distribution is 50 volume%, as measured by a particle size analyzer. With respect to 100 weight% of the silicon-carbon composite particles, silicon may be included in an amount of 10 weight% to 60 weight% and carbon may be included in an amount of 40 weight% to 90 weight%. The silicon-carbon composite particles may, for example, comprise a core containing silicon particles and a carbon coating layer located on the surface of the core. The average particle diameter (D) of the silicon particles in the core 50) may be 10 nm to 1 µm, or 10 nm to 200 nm. The silicon particles may exist as silicon alone, in the form of a silicon alloy, or in an oxidized form. The oxidized form of silicon is SiO x (0 <x≤2)로 표시될 수 있다. 또한, 상기 탄소 코팅층의 두께는 약 5 ㎚ 내지 100 ㎚일 수 있다.

[0090] For example, the silicon-carbon composite particles may comprise a core containing silicon particles and crystalline carbon, and a carbon coating layer located on the surface of the core containing amorphous carbon. For example, in the silicon-carbon composite particles, the amorphous carbon may not be present in the core but only in the carbon coating layer. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof, and the amorphous carbon may be formed from coal-based pitch, mesophase pitch, petroleum-based pitch, coal-based oil, petroleum-based heavy oil, or a polymer resin (phenol resin, furan resin, polyimide resin, etc.). In this case, the content of the crystalline carbon may be 10% to 70% by weight and the content of the amorphous carbon may be 20% to 40% by weight with respect to 100% by weight of the silicon-carbon composite particles.

[0091] The core of the silicon-carbon composite particle may include a void in the central portion. The radius of the void may be 30% to 50% of the radius of the silicon-carbon composite particle.

[0092] The aforementioned silicon-carbon composite particles effectively suppress problems such as volume expansion, structural collapse, or particle fragmentation due to charging and discharging, thereby preventing the interruption of conductive paths, enabling high capacity and high efficiency, and making them advantageous for use under high voltage or high-speed charging conditions.

[0093] The above Si-based negative electrode active material or Sn-based negative electrode active material may be used in combination with a carbon-based negative electrode active material. When the Si-based negative electrode active material or Sn-based negative electrode active material and the carbon-based negative electrode active material are mixed and used, the mixing ratio may be 1:99 to 90:10 by weight.

[0094] The content of the negative electrode active material in the above negative electrode active material layer may be 95% to 99% by weight with respect to the total weight of the negative electrode active material layer.

[0095] In one embodiment, the negative active material layer further comprises a binder and optionally further comprises a conductive material. The content of the binder in the negative active material layer may be 1% to 5% by weight with respect to the total weight of the negative active material layer. Additionally, when further comprising a conductive material, the negative active material layer may comprise 90% to 98% by weight of the negative active material, 1% to 5% by weight of the binder, and 1% to 5% by weight of the conductive material.

[0096] The above binder serves to effectively bond the negative electrode active material particles to each other and also to effectively bond the negative electrode active material to the current collector. As the binder, a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof may be used.

[0097] Examples of the above-mentioned non-aqueous binders include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide imide, polyimide, or combinations thereof.

[0098] The above-mentioned water-based binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0099] When a water-based binder is used as the above-mentioned cathode binder, a cellulose-based compound capable of imparting viscosity may be further included. As this cellulose-based compound, one or more types such as carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or alkali metal salts thereof may be mixed and used. Na, K, or Li may be used as the alkali metal.

[0100] The above conductive material is used to impart conductivity to the electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Examples of the above conductive material include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube; metal-based materials in the form of metal powder or metal fibers including copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or conductive materials including mixtures thereof.

[0101] As the above-mentioned cathode current collector, a material selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, or a combination thereof may be used.

[0102] Precipitation type cathode

[0103] As another example, the negative electrode for an all-solid-state secondary battery may be a precipitation type negative electrode. The precipitation type negative electrode may refer to a negative electrode that does not contain a negative electrode active material during battery assembly, but where lithium metal, etc., is precipitated or electrodeposited on the negative electrode during battery charging, and which acts as the negative electrode active material.

[0104] FIG. 2 is a schematic cross-sectional view of an all-solid-state secondary battery including a precipitation type negative electrode. Referring to FIG. 2, the precipitation type negative electrode (400') may include a negative electrode current collector (401) and a negative electrode coating layer (405) located on the negative electrode current collector. An all-solid-state secondary battery having such a precipitation type negative electrode (400') starts initial charging in a state where no negative electrode active material is present. Subsequently, during charging, a high-density lithium metal is precipitated or electrodeposited between the negative electrode current collector (401) and the negative electrode coating layer (405), or on the negative electrode coating layer (405), to form a lithium metal layer (404), which can serve as a negative electrode active material. Accordingly, in a solid-state secondary battery that has undergone one or more charges, the precipitation type negative electrode (400') may include, for example, a negative electrode current collector (401), a lithium metal layer (404) located on the negative electrode current collector, and a negative electrode coating layer (405) located on the lithium metal layer. The lithium metal layer (404) refers to a layer in which lithium metal, etc. is precipitated during the charging process of the battery, and may be referred to as a metal layer, a lithium layer, a lithium electrodeposition layer, or a negative electrode active material layer.

[0105] The above-mentioned cathode coating layer (405) may be a lithium electrodeposition inducing layer or a cathode catalyst layer, and may include a lithium-friendly metal, a carbon material, or a combination thereof.

[0106] The above-mentioned lithium-friendly metal may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or a combination thereof, and may be composed of one of these or may be composed of several types of alloys. When the metal exists in the form of particles, its average particle size (D50 ) can be about 4 μm or less, and for example, 10 nm to 4 μm.

[0107] The carbon material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof. The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon micro beads, or a combination thereof. The amorphous carbon may be, for example, carbon black, activated carbon, acetylene black, Denka black, Ketjen black, or a combination thereof.

[0108] When the above-mentioned cathode coating layer (405) includes both the metal and the carbon material, the mixing ratio of the metal and the carbon material may be, for example, a weight ratio of 1:10 to 2:1. In this case, the precipitation of lithium metal can be effectively promoted and the characteristics of the all-solid-state secondary battery can be improved. The cathode coating layer (405) may, for example, include a carbon material supported with a catalyst metal, or may include a mixture of metal particles and carbon material particles.

[0109] The above cathode coating layer (405) may, for example, include the lithium-friendly metal and amorphous carbon, in which case the precipitation of lithium metal can be effectively promoted. As a specific example, the cathode coating layer (405) may include a composite in which a lithium-friendly metal is supported on amorphous carbon.

[0110] The above cathode coating layer (405) may further include a binder, and the binder may be, for example, a conductive binder. In addition, the above cathode coating layer (405) may further include general additives such as fillers, dispersants, ion conductive agents, etc.

[0111] The thickness of the above cathode coating layer (405) may be, for example, 100 nm to 20 μm, or 500 nm to 10 μm, or 1 μm to 5 μm.

[0112] The above-described precipitation type cathode (400') may, for example, further include a thin film on the surface of the cathode current collector, that is, between the cathode current collector and the cathode coating layer. The thin film may include an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and may be composed of one of these or composed of several types of alloys. The thin film can further flatten the precipitation shape of the lithium metal layer (404) and further improve the characteristics of the all-solid-state secondary battery. The thin film may be formed by, for example, a vacuum deposition method, a sputtering method, a plating method, etc. The thickness of the thin film may be, for example, 1 nm to 500 nm.

[0113] The lithium metal layer (404) may include lithium metal or a lithium alloy. The lithium alloy may be, for example, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, or a Li-Si alloy.

[0114] The thickness of the lithium metal layer (404) may be 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 100 μm, or 1 μm to 50 μm. Within the above range, it can sufficiently perform the role of a lithium storage tank and prevent performance degradation due to an increase in battery volume.

[0115] When such a precipitation-type cathode is applied, the cathode coating layer (405) can protect the lithium metal layer (404) and suppress the precipitation growth of lithium deadlite. Accordingly, short circuits and capacity degradation of the all-solid-state battery are suppressed, and lifespan characteristics can be improved.

[0116] solid electrolyte membrane

[0117] In a solid-state secondary battery according to one embodiment, the solid electrolyte membrane (300) comprises a solid electrolyte, and the solid electrolyte may include a sulfide-based solid electrolyte, and may further include a solid electrolyte selected from an oxide-based solid electrolyte, a halide-based solid electrolyte, or a combination thereof.

[0118] Sulfide-based solid electrolytes

[0119] For example, the solid electrolyte membrane (300) may include a sulfide-based solid electrolyte with excellent ion conductivity. The sulfide-based solid electrolyte is, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element, for example, I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are integers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are integers, and M is P, Si, Ge, B, Al, Ga or In), or may include a combination thereof.

[0120] Such sulfide-based solid electrolytes can be obtained, for example, by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10 or 50:50 to 80:20 and optionally heat-treating. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be manufactured. Additionally, ionic conductivity may be further improved by including other components such as SiS2, GeS2, B2S3, etc.

[0121] Mechanical milling or the solution method can be applied as mixing methods for sulfur-containing raw materials to manufacture sulfide-based solid electrolytes. Mechanical milling is a method in which starting materials are placed in a ball mill reactor and vigorously stirred to finely atomize and mix them. When using the solution method, starting materials are mixed in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, if heat treatment is performed after mixing, the crystals of the solid electrolyte can become more robust and the ionic conductivity can be improved. For example, a sulfide-based solid electrolyte can be manufactured by mixing sulfur-containing raw materials and heat-treating them two or more times; in this case, a robust sulfide-based solid electrolyte with high ionic conductivity can be produced.

[0122] A sulfide-based solid electrolyte according to one embodiment can be manufactured, for example, by mixing sulfur-containing raw materials and calcining at 120°C to 350°C for a first heat treatment, and by mixing the results of the first heat treatment and calcining at 350°C to 800°C for a second heat treatment. The first heat treatment and the second heat treatment can each be carried out in an inert gas or nitrogen atmosphere. The first heat treatment can be performed for 1 to 10 hours, and the second heat treatment can be performed for 5 to 20 hours. Through the first heat treatment, the effect of milling small raw materials can be obtained, and through the second heat treatment, the final solid electrolyte can be synthesized. Through two or more such heat treatments, a high-performance sulfide-based solid electrolyte with high ion conductivity and robustness can be obtained, and such a solid electrolyte can be considered suitable for mass production. The temperature of the first heat treatment may be, for example, 150°C to 330°C or 200°C to 300°C, and the temperature of the second heat treatment may be, for example, 380°C to 700°C or 400°C to 600°C.

[0123] For example, the sulfide-based solid electrolyte may be in the form of particles and may contain argyrodite-type sulfides. These argyrodite-type sulfide-based solid electrolyte particles have an ionic conductivity of 10 at room temperature, which is the ionic conductivity of a typical liquid electrolyte. -4 to 10 -2 It has high ionic conductivity approaching the S / cm range. Furthermore, it can form a tight bond between the positive electrode active material and the solid electrolyte without causing a decrease in ionic conductivity, and can form a tight interface between the electrode and the solid electrolyte film. An all-solid-state secondary battery containing this can improve battery performance such as rate characteristics, Coulomb efficiency, and lifespan characteristics.

[0124] The above sulfide-based solid electrolyte may include, for example, an azirodite-type sulfide represented by Chemical Formula 11 below.

[0125] [Chemical Formula 11]

[0126] (Li a M 1 b M 2 c )(P d M 3 e )(S f M 4 g )X h

[0127] In the above chemical formula 11, 4≤a≤8, and M 1 is Mg, Cu, Ag, or a combination thereof, 0≤b<0.5, and M 2 is Na, K, or a combination thereof, 0≤c<0.5, and M 3 is Sn, Zn, Si, Sb, Ge, or a combination thereof, and 0 <d<4, 0≤e<1 이고, M 4 is O, SO n , or a combination thereof, 1.5≤n≤5, 3≤f≤12, 0≤g<2, X is F, Cl, Br, I, or a combination thereof, and 0≤h≤2.

[0128] For example, in Chemical Formula 11, a halogen element (X) may be necessarily included, in which case 0 <h≤2로 표시될 수 있다. 일 예로 화학식 11에 M 1 An element may be required, in which case 0 <b<0.5로 표시될 수 있다. 화학식 11에서 M 3 can be understood as the element substituted at the P position, and 0 <e<1일 수 있다. 화학식 11에서 M 4 is substituted into the S position, for example, 0 <g<2일 수 있으며, S의 비율인 f는 예를 들어 3≤f≤7일 수 있다. M 4 ga SO n In the case of SO n It can be, for example, S4O6, S3O6, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, SO4, or SO5, and as an example, it can be SO4.

[0129] For example, in Chemical Formula 11, a+b+c+h=7, d+e=1, and f+g+h=6.

[0130] As a specific example, azirodite-type sulfide-based solid electrolyte particles include Li3PS4 and Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 , Li 5.75 PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )PS 4.75 Cl 1.25 , (Li 5.72 Cu 0.03 )PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.70 (SO4) 0.05 )Cl 1.25 , (Li 5.69 Cu0.06 )P(S 4.60 (SO4) 0.15 )Cl 1.25 , (Li 5.72 Cu 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , (Li 5.72 Na 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , Li 5.75 P(S 4.725 (SO4) 0.025 )Cl 1.25 , or a combination thereof may be included, but is not limited thereto.

[0131] An azirodite-type sulfide-based solid electrolyte can be prepared by mixing, for example, lithium sulfide and phosphorus sulfide, and optionally lithium halide. After mixing these, heat treatment may be performed. The heat treatment may include, for example, two or more heat treatment steps. Here, preparing an azirodite-type sulfide-based solid electrolyte may include, for example, a first heat treatment in which raw materials are mixed and calcined at 120°C to 350°C, and a second heat treatment in which the result of the first heat treatment is mixed again and calcined at 350°C to 800°C.

[0132] Average particle size of sulfide-based solid electrolyte particles (D 50 ) may, for example, be 0.1 μm to 5.0 μm or 0.1 μm to 3.0 μm, and may be fine particles of 0.1 μm to 1.9 μm or coarse particles of 2.0 μm to 5.0 μm. The sulfide-based solid electrolyte particles may be a mixture of fine particles with an average particle size of 0.1 μm to 1.9 μm and coarse particles with an average particle size of 2.0 μm to 5.0 μm. The average particle size of the sulfide-based solid electrolyte particles may be measured using electron microscope images, for example, by measuring the size (diameter or length of the major axis) of about 20 particles from scanning electron microscope images to obtain a particle size distribution, where D50 It could be that it was calculated.

[0133] For example, the sulfide-based solid electrolyte may be included in an amount of 80% to 97% by weight with respect to 100% by weight of the solid electrolyte membrane, and may be included in an amount of, for example, 85% to 97% by weight, 90% to 97% by weight, 93% to 97% by weight, or 94% to 96% by weight. Within this range, excellent ionic conductivity can be secured while ensuring the durability of the battery.

[0134] oxide-based solid electrolytes

[0135] The solid electrolyte membrane (300) may include an oxide-based solid electrolyte. The oxide-based solid electrolyte is, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Lithium Phosphate (Li3PO4), Lithium Titanium Phosphate (Li x Ti y (PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate(Li x Lay TiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2계 세라믹스, 가넷(Garnet)계 세라믹스 Li 3+x La3M2O 12 (M= Te, Nb, or Zr; x is an integer from 1 to 10), or may include a mixture thereof.

[0136] Halide-based solid electrolytes

[0137] The solid electrolyte membrane (300) may include, for example, a halide-based solid electrolyte. The halide-based solid electrolyte contains a halogen element as a main component, and the ratio of the halogen element to all elements constituting the solid electrolyte may be 50 mol% or more, 70 mol% or more, 90 mol% or more, or 100 mol%. For example, the halide-based solid electrolyte may not contain a sulfur element.

[0138] The halide-based solid electrolyte may contain a lithium element, a metal element other than lithium, and a halogen element. The metal element other than lithium may be Al, As, B, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hf, In, Mg, Mn, Ni, Sb, Sc, Sn, Ta, Ti, Y, Zn, Zr, or a combination thereof. The halogen element may be F, Cl, Br, I, or a combination thereof, and for example, may be Cl, Br, or a combination thereof. The halide-based solid electrolyte is, for example, Li a It can be represented as M1X6 (M is Al, As, B, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hf, In, Mg, Mn, Ni, Sb, Sc, Sn, Ta, Ti, Y, Zn, Zr, or a combination thereof, X is F, Cl, Br, I, or a combination thereof, and 2≤a≤3). The above halide-based solid electrolyte is, for example, Li2ZrCl6, Li 2.7 Y0.7 Zr 0.3 Cl6, Li 2.5 Y 0.5 Zr 0.5 Cl6, Li 2.5 In 0.5 Zr 0.5 Cl6, Li2In 0.5 Zr 0.5 Cl6, Li3YBr6, Li3YCl6, Li3YBr2Cl4, Li3YbCl6, Li 2.6 Hf 0.4 Yb 0.6 It may include Cl6, or a combination thereof, but is not limited thereto.

[0139] bookbinder

[0140] A solid electrolyte membrane according to one embodiment may further include a binder. The binder is, for example, nitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, natural rubber, polydimethylsiloxane, polyethylene oxide, polyvinylpyrrolidone, polyvinylpyridine, chlorosulfonated polyethylene, polyvinyl alcohol, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, polyamideimide, polyimide, poly(meth)acrylate, polyacrylonitrile, polystyrene, polyurethane, copolymers thereof, Or it may include a combination of these.

[0141] The binder may be included in an amount of 0.1% to 3% by weight relative to 100% by weight of the solid electrolyte membrane, for example, 0.5% to 2% by weight or 0.5% to 1.5% by weight. When the binder is included within the above range, the components within the solid electrolyte membrane can be well bonded without lowering the ionic conductivity of the solid electrolyte, thereby improving the durability and reliability of the battery.

[0142] Other ingredients

[0143] The solid electrolyte membrane may optionally further include other components such as alkali metal salts, and / or ionic liquids, and / or conductive polymers.

[0144] The above alkali metal salt may be, for example, a lithium salt. The content of the lithium salt in the above solid electrolyte membrane may be 1 M or more, for example, 1 M to 4 M. In this case, the lithium salt can improve ion conductivity by improving the lithium ion mobility of the solid electrolyte membrane.

[0145] Lithium salts may be applied without limitation of type and may include, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiSCN, LiN(CN)2, lithium bis(oxalateto)borate (LiBOB), lithium difluoro(oxalateto)borate (LiDFOB), lithium difluorobis(oxalateto)phosphate (LiDFBP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, or combinations thereof.

[0146] For example, the above lithium salt may be an imide-based lithium salt such as LiTFSI, LiFSI, LiBETI, or a combination thereof. The imide-based lithium salt can maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with the ionic liquid.

[0147] Ionic liquids are salts or room temperature molten salts that have a melting point below room temperature, are in a liquid state at room temperature, and consist only of ions.

[0148] The ionic liquid comprises a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, and mixtures thereof, and b) BF4 - , PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - It may be a compound containing one or more anions selected from among.

[0149] The above ionic liquid may include, for example, N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolinium bis(trifluoromethylsulfonyl)amide, 1-ethyl-3-methylimidazolinium bis(trifluoromethylsulfonyl)amide, or a combination thereof.

[0150] The weight ratio of the solid electrolyte to the ionic liquid in the above solid electrolyte membrane may be 0.1:99.9 to 90:10, and for example, 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. A solid electrolyte membrane satisfying the above range can maintain or improve ionic conductivity by increasing the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate characteristics, etc. of the all-solid-state secondary battery can be improved.

[0151] The shape of the above-described all-solid-state secondary battery is not particularly limited and may be, for example, coin-type, button-type, sheet-type, stacked-type, cylindrical-type, flat-type, etc. Furthermore, the above-described all-solid-state secondary battery can be applied to large batteries used in electric vehicles, etc. For example, the above-described all-solid-state secondary battery can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in fields requiring a large amount of power storage, for example, in electric bicycles or power tools. Furthermore, the above-described all-solid-state secondary battery can be used in various fields such as portable electronic devices.

[0152] Examples and comparative examples of the present invention are described below. The following examples are merely illustrative of the present invention, and the present invention is not limited to the following examples.

[0153] Example 1

[0154] Waste solid-state secondary battery modules and packs, which are used solid-state secondary battery materials requiring recycling, with LiNi as the positive electrode active material 0.8 Co 0.15 Mn 0.05 A product was prepared using O2 and Li6PS5Cl, an azirodite-type sulfide, as the sulfide-based solid electrolyte.

[0155] After preparing a crushing and grinding device, the all-solid-state secondary battery material was fed into the crushing and grinding device, and crushing and grinding were performed so that the maximum length of the fed all-solid-state secondary battery material satisfies the range of 5 cm (here, to satisfy the square shape with a side length of 5 cm).

[0156] The above-mentioned crushed and ground all-solid-state secondary battery material was subjected to heat treatment at 300°C for 3 hours under an atmospheric environment, and the heat treatment was performed dry. Subsequently, the product of the heat treatment was mixed with water and subjected to water leaching, after which the solid and liquid phases were separated to recover a solid powder from which lithium had been removed in the solid phase, and a lithium sulfate (Li2SO4) and lithium chloride (LiCl) solution was recovered in the liquid phase.

[0157] Example 2

[0158] Except for changing the temperature of the heat treatment above to 400 ℃, the lithium-removed solid powder and lithium recovery materials, lithium sulfate (Li2SO4) and lithium chloride (LiCl) solutions, were recovered in substantially the same manner as in Example 1.

[0159] Example 3

[0160] Except for changing the temperature of the heat treatment above to 500 ℃, the lithium-removed solid powder and lithium recovery materials, lithium sulfate (Li2SO4) and lithium chloride (LiCl) solutions, were recovered in substantially the same manner as in Example 1.

[0161] Comparative Example 1

[0162] A lithium hydroxide (LiOH) solution was recovered as a lithium recovery material in substantially the same manner as in Example 1, except that the crushed and ground all-solid-state secondary battery material was mixed with water and leached without the above heat treatment.

[0163] Evaluation Example 1: Evaluation of Hydrogen Sulfide Gas Leakage Amount

[0164] During the recycling process of the all-solid-state secondary battery modules and packs of Examples 1 to 3 and Comparative Examples 1 and 2, the amount of hydrogen sulfide (H2S) gas leakage under atmospheric conditions was measured in ppm units using a hydrogen sulfide meter (Manufacturer: Honeywell, Model: MINIMAX-XP-H2S) and is shown in Table 1 below.

[0165] H2S gas outflow amount Example 120 ppm Example 210 ppm Example 325 ppm Comparative Example 1350 ppm

[0166] Referring to Table 1 above, it can be confirmed that the amount of hydrogen sulfide (H2S) gas leakage is low in the case of Examples 1 to 3. Therefore, it can be seen that not only is it safe because there is no problem with H2S gas leakage during the operation process, but there is also no problem with environmental pollution.

[0167] In contrast, in the case of Comparative Example 1, it can be seen that the amount of hydrogen sulfide (H2S) gas leakage is relatively higher compared to Examples 1 and 2. Therefore, it can be seen that a risk issue may arise due to the hydrogen sulfide (H2S) gas generated during the work process, and that an environmental pollution problem may occur.

[0168] Evaluation Example 2: Evaluation of the composition of lithium recovery material

[0169] A lithium recovery material was prepared by recycling the all-solid-state secondary battery module and pack of Examples 1 to 3 and Comparative Example 1 from the liquid phase during solid-liquid separation, and the components were analyzed using an ICP component measuring device and are shown in Table 2 below.

[0170] Composition of lithium recovery material Example 1: Li2SO4, LiCl solution Example 2: Li2SO4, LiCl solution Example 3: Li2SO4, LiCl solution Comparative Example 1: LiOH solution

[0171] Referring to Table 2 above, it can be confirmed that in Examples 1 to 3, lithium sulfate (Li2SO4) and lithium chloride (LiCl) can be recovered as lithium recovery materials.

[0172] On the other hand, in the case of Comparative Example 1, heat treatment was not performed during the recycling process, so it can be confirmed that lithium sulfate (Li2SO4) and lithium chloride (LiCl) are not recovered as lithium recovery materials, and LiOH is recovered as lithium recovery materials.

[0173] Evaluation Example 3: Evaluation of Lithium Recovery Rate

[0174] The final amount of lithium recovered (ppm) in the lithium recovery material through the recycling process of Examples 1 to 3 and Comparative Example 1 was measured under atmospheric conditions using an Agilent 7850 ICP and is shown in Table 3 below.

[0175] In addition, the lithium recovery rate was calculated from Equation 1 below and shown in Table 3 below, and measured based on weight.

[0176] [Equation 1]

[0177] Lithium recovery rate = (R1 / R2)×100

[0178] In the above Equation 1, R1 represents the amount of recovered lithium, and R2 represents the amount of lithium contained in the all-solid-state secondary battery material.

[0179] Amount of Recovered Lithium (ppm) Lithium Recovery Rate (%) Example 1 140,000 85 Example 2 165,000 90 Example 3 165,000 90 Comparative Example 1 18,000 10

[0180] Referring to Table 3 above, it can be seen that in Examples 1 to 3, the amount of recovered lithium is very high at the level of 140,000 to 165,000 ppm, and the lithium recovery rate is also very high at 85% or higher.

[0181] On the other hand, in the case of Comparative Example 1, heat treatment was not performed during the recycling process, so it can be confirmed that the amount of lithium recovered is very low and the lithium recovery rate is also very low at the level of 10%.

[0182] Evaluation Example 4: Water Usage Evaluation

[0183] The amount of water required to achieve the lithium recovery rate of Evaluation Example 3 described above during the recycling process of the all-solid-state secondary battery modules and packs of Examples 1 to 3 and Comparative Example 1 was measured and is shown in Table 4 below. At this time, the amount of water used in Example 1 was measured in weight units and set as the standard 100%, and the relative amount of water used in Examples 2 and 3 and Comparative Example 1 compared to Example 1 was measured.

[0184] Water Usage Example 1 100% Example 2 100% Example 3 100% Comparative Example 1 400%

[0185] Referring to Table 4 above, it can be seen that in the case of Examples 1 to 3, the amount of water used in the recycling process is significantly lower compared to Comparative Example 1. Accordingly, according to the recycling method of one embodiment, the amount of water used can be drastically reduced to 1 / 10 to 1 / 2 of the level of the conventional method, Comparative Example 1, so it can be seen that not only is it environmentally friendly, but the cost required for recycling can also be reduced.

[0186] Although preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concepts defined in the following claims are also included within the scope of the present invention.

[0187] [Explanation of the symbol]

[0188] 100: All-solid-state battery 200: Cathode

[0189] 201: Positive current collector 203: Positive active material layer

[0190] 300: Solid electrolyte membrane 400: Cathode

[0191] 401: Cathode current collector 403: Cathode active material layer

[0192] 400': Precipitation type cathode 404: Lithium metal layer

[0193] 405: Cathode coating layer 500: Elastic sheet

Claims

1. An all-solid-state secondary battery material comprising a lithium-containing material and a sulfide-based solid electrolyte is heat-treated to convert it into a lithium recovery material containing lithium sulfate, and A method for recycling all-solid-state secondary battery materials comprising mixing the product of the heat treatment with an aqueous solvent to extract the lithium recovery material.

2. In Paragraph 1, The above lithium-containing material is a method for recycling all-solid-state secondary battery materials that are lithium-containing positive electrode active materials.

3. In Paragraph 1, The above lithium-containing material is a method for recycling an all-solid-state secondary battery material comprising a lithium transition metal composite oxide.

4. In Paragraph 1, A method for recycling an all-solid-state secondary battery material comprising the above lithium-containing material being a lithium nickel-based oxide represented by the following chemical formula 1, a lithium cobalt-based oxide represented by the following chemical formula 2, a lithium iron phosphate-based compound represented by the following chemical formula 3, a cobalt-free lithium nickel-manganese-based oxide represented by the following chemical formula 4, or a combination thereof. [Chemical Formula 1] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1 In the above chemical formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, 0≤z1≤0.7, 0.9≤x1+y1+z1≤1.1, and 0≤b1≤0.1, and M 1 and M 2 Each is independently Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zr, or a combination thereof, and X is F, P, S, or a combination thereof. [Chemical Formula 2] Li a2 Co x2 M 3 y2 O 2-b2 X b2 In the above chemical formula 2, 0.9≤a2≤1.8, 0.7≤x2≤1, 0≤y2≤0.3, 0.9≤x2+y2≤1.1, and 0≤b2≤0.1, and M 3 is Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, Zr, or a combination thereof, and X is F, P, S, or a combination thereof. [Chemical Formula 3] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3 In the above chemical formula 3, 0.9≤a3≤1.8, 0.6≤x3≤1, 0≤y3≤0.4, and 0≤b3≤0.1, and M 4 is Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, Zr, or a combination thereof, and X is F, P, S, or a combination thereof. [Chemical Formula 4] Li a4 Ni x4 Mr y4 M 5 z4 O 2-b4 X b4 In the above chemical formula 4, 0.9≤a2≤1.8, 0.8≤x4<1, 0 <y4≤0.2, 0≤z4≤0.2, 0.9≤x4+y4+z4≤1.1, 및 0≤b4≤0.1이고 M 5 is Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zr, or a combination thereof, and X is F, P, S, or a combination thereof.

5. In Paragraph 1, The above sulfide-based solid electrolyte is a method for recycling all-solid-state secondary battery materials containing azirodite-type sulfide.

6. In Paragraph 1, A method for recycling all-solid-state secondary battery materials, wherein the above-mentioned sulfide-based solid electrolyte comprises an azirodite-type sulfide represented by the following chemical formula 11. [Chemical Formula 11] (Li a M 1 b M 2 c (P) d M 3 e )(S f M 4 g )X h In the above chemical formula 11, 4≤a≤8, and M 1 is Mg, Cu, Ag, or a combination thereof, 0≤b<0.5, and M 2 is Na, K, or a combination thereof, 0≤c<0.5, and M 3 is Sn, Zn, Si, Sb, Ge, or a combination thereof, and 0 <d<4, 0≤e<1 이고, M 4 is O, SO n , or a combination thereof, 1.5≤n≤5, 3≤f≤12, 0≤g<2, X is F, Cl, Br, I, or a combination thereof, and 0≤h≤2.

7. In Paragraph 1, A method for recycling solid-state secondary battery materials, comprising solid-state secondary battery cells, solid-state secondary battery modules, solid-state secondary battery packs, solid-state secondary battery process scraps, solid-state secondary battery decomposition products, or a combination thereof.

8. In Paragraph 1, A method for recycling all-solid-state secondary battery materials, further comprising, prior to the heat treatment, feeding the all-solid-state secondary battery material into a crushing and grinding device to perform crushing and grinding.

9. In Paragraph 8, A method for recycling all-solid-state secondary battery materials in which the crushing and grinding are performed such that the maximum length of the all-solid-state secondary battery material fed into the crushing and grinding device satisfies 0.1 cm to 10 cm.

10. In Paragraph 1, The above heat treatment is a method for recycling all-solid-state secondary battery materials performed as a dry process.

11. In Paragraph 1, A method for recycling all-solid-state secondary battery materials in which the above heat treatment is performed in a temperature range of 150 ℃ to 750 ℃.

12. In Paragraph 1, The above heat treatment is a method for recycling all-solid-state secondary battery materials performed under an atmospheric environment.

13. In Paragraph 1, A method for recycling all-solid-state secondary battery materials in which the above heat treatment is performed for 10 minutes to 10 hours.

14. In Paragraph 1, A method for recycling all-solid-state secondary battery materials, wherein the above-mentioned lithium recovery material further comprises lithium chloride, lithium carbonate, lithium hydrogen bicarbonate, lithium hydroxide, lithium phosphate, or a combination thereof.

15. In Paragraph 1, A method for recycling all-solid-state secondary battery materials, wherein the above-mentioned aqueous solvent comprises water, sodium hydroxide, lithium hydroxide, or a combination thereof.

16. In Paragraph 1, The above extraction is a method for recycling all-solid-state secondary battery materials performed by solid-liquid separation.

17. In Paragraph 16, Among the results of the above solid-liquid separation, the solid powder from which lithium has been removed in the solid phase is recovered, and A method for recycling all-solid-state secondary battery materials by recovering a solution containing a lithium recovery material in the liquid phase among the results of the above-mentioned solid-liquid separation.

18. In Paragraph 1, Recycling method for all-solid-state secondary battery materials having a lithium recovery rate of 70% or more as defined by the following Equation 1: [Equation 1] Lithium recovery rate = (R1 / R2)×100 In the above Equation 1, R1 represents the amount of recovered lithium, and R2 represents the amount of lithium contained in the all-solid-state secondary battery material.

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