Solid electrolyte and all-solid-state battery containing the same

Abstract

The present invention relates to a sulfide-based solid electrolyte particle and a buffer layer containing Li2CO3 formed on the sulfide-based solid electrolyte particle, and -1 ~4725cm -1 The present invention relates to a solid electrolyte having a Li2CO3 band integral value in a region of 2.0 to 8.0, and an all-solid-state battery including the solid electrolyte.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0042176, filed March 30, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a solid electrolyte and an all-solid-state battery including the same. [Background technology]

[0003] All-solid-state batteries replace the liquid electrolyte currently used between the positive and negative electrodes of lithium secondary batteries with a solid electrolyte. These batteries are safe and explosion-free, and have a higher energy density than conventional batteries, drawing attention as a next-generation battery. The solid electrolyte used in all-solid-state batteries is a solid-state material that allows lithium ions to be conducted within the battery, and has high ionic conductivity comparable to that of the liquid electrolytes currently used in lithium secondary batteries. Key materials for solid electrolytes include polymers, sulfides, and oxides. Among these, sulfide-based solid electrolytes, which are highly flexible and have high ionic conductivity, are considered suitable for the production of large-capacity batteries.

[0004] However, sulfide-based solid electrolytes have the problem of decomposing by reacting with moisture in the air and generating hydrogen sulfide gas, and the decomposition products generated by interfacial side reactions with electrode materials can cause deterioration of battery performance during long-term operation.

[0005] Therefore, there is a need to develop a sulfide-based solid electrolyte that can suppress reactions with moisture in the atmosphere and interfacial side reactions with electrode materials. Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a solid electrolyte that has improved water stability and can suppress interfacial side reactions with electrode materials, and an all-solid-state battery including the same.

[0007] However, the problems that the present invention aims to solve are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a solid electrolyte and an all-solid-state battery including the same.

[0009] (1) The present invention provides a sulfide-based solid electrolyte particle and a buffer layer containing Li2CO3 formed on the sulfide-based solid electrolyte particle, wherein the buffer layer has a peak at 5200 cm in the NIR spectrum. -1 ~4725cm -1 The present invention provides a solid electrolyte having a Li2CO3 band integral value in a region of 2.0 or more and 8.0 or less.

[0010] (2) The present invention provides, in the above (1), a solid electrolyte in which the sulfide-based solid electrolyte has an argyrodite-type crystal structure.

[0011] (3) The present invention provides the sulfide-based solid electrolyte according to the above (1) or (2), wherein the sulfide-based solid electrolyte has a composition represented by the following chemical formula 1: [Chemical formula 1] Li a (P 1-b M b )S 6-c X d In the above Chemical Formula 1, M is one or more selected from Sb, Sn, Ge, Si, Nb, Ni, Ga, and Al; X is one or more selected from F, Cl, Br and I; 5.0 <a<7.5、0≦b≦0.7、0<c≦2.0である。

[0012] (4) The present invention provides a solid electrolyte according to any one of the above (1) to (3), which has an ionic conductivity of 3 mS / cm to 12 mS / cm.

[0013] (5) In any one of the above (1) to (4), the present invention is characterized in that the NIR spectrum has a wavelength of 7200 cm -1 ~7140cm -1 The present invention provides a solid electrolyte having a LiOH band integral of less than 0.1 in a region.

[0014] (6) In any one of the above (1) to (5), the present invention provides a method for producing a 2p spectrum of phosphorus (P) obtained by XPS analysis, which shows that PS4 3- Peak area A1 and PO x S 4-x 3- PO relative to the sum of peak areas A2 x S 4-x 3- A solid electrolyte is provided in which the ratio of peak areas A2 / (A1+A2) is less than 0.1.

[0015] (7) The present invention provides an all-solid-state battery including the solid electrolyte according to any one of (1) to (6) above. [Effects of the Invention]

[0016] The solid electrolyte according to the present invention includes a buffer layer containing Li2CO3 formed on sulfide-based solid electrolyte particles, and has a peak at 5200 cm in the NIR spectrum. -1 ~4725cm -1 The Li2CO3 band integral value in this region is between 2.0 and 8.0, which means that a stable phase is maintained when exposed to water during the battery manufacturing process, and side reactions at the interface between the solid electrolyte and electrode materials can be suppressed, resulting in improved battery performance. [Brief explanation of the drawings]

[0017] [Figure 1] 1 shows XRD peaks of the solid electrolyte of Example 5. [Figure 2]1 shows XPS data of the solid electrolytes of Examples 1 to 3 and Comparative Examples 3 and 6. [Figure 3] 1 shows evaluation data of the rate-limiting characteristics of all-solid-state batteries containing the solid electrolytes of Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will now be described in more detail to facilitate understanding of the present invention.

[0019] The terms and words used in this specification should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as having meanings and concepts that are consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0020] The terms used in this specification are merely used to describe exemplary embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly indicates otherwise.

[0021] In this specification, the terms "comprises," "includes," "has," and the like are intended to specify the presence of embodied features, numbers, steps, components, or combinations thereof, but are not intended to preclude the possible presence or addition of one or more different features, numbers, steps, components, or combinations thereof.

[0022] In this specification, normal temperature means 20°C to 25°C.

[0023] solid electrolyte The solid electrolyte according to the present invention includes sulfide-based solid electrolyte particles and a buffer layer containing Li2CO3 formed on the sulfide-based solid electrolyte particles, and has a peak at 5200 cm in the NIR spectrum. -1 ~4725cm -1The Li2CO3 band integral value present in the region is between 2.0 and 8.0.

[0024] The present inventors have discovered a solid electrolyte comprising sulfide-based solid electrolyte particles and a buffer layer containing Li2CO3 formed on the sulfide-based solid electrolyte particles, and have discovered a material with a peak at 5200 cm in the NIR spectrum. -1 ~4725cm -1 The inventors discovered that when the Li2CO3 band integral value in the region is between 2.0 and 8.0, the water stability of the solid electrolyte is improved and a stable phase of the solid electrolyte is maintained during the battery manufacturing process, resulting in improved battery life and rate characteristics, and thus completed the present invention.

[0025] According to the present invention, the sulfide-based solid electrolyte may have an argyrodite-type crystal structure in terms of high ionic conductivity and low reactivity with a lithium negative electrode.

[0026] The sulfide-based solid electrolyte may be a sulfide-based solid electrolyte containing Li, P, and S.

[0027] According to the present invention, the sulfide-based solid electrolyte may have a composition represented by the following Chemical Formula 1. In this case, it may have excellent ionic conductivity even after forming a buffer layer.

[0028] [Chemical formula 1] Li a (P 1-b M b )S 6-c X d

[0029] In the above Chemical Formula 1, M is one or more selected from Sb, Sn, Ge, Si, Nb, Ni, Ga, and Al; X is one or more selected from F, Cl, Br and I; 5.0 <a<7.5、0≦b≦0.7、0<c≦2.0である。

[0030] The M is a cation to be doped at the P site, and specifically, may be one or more selected from Sb, Sn, Ge, and Si. In this case, since M has a similar oxidation number to P, it can be easily doped (substituted) at the P site.

[0031] Specifically, X may be Cl, Br, or a combination thereof, in which case the degree of disorder in the anion arrangement increases, the lithium ion conduction pathway changes, and consequently the ionic conductivity can be further increased.

[0032] The a may be greater than 5.0, 5.1, 5.2, 5.3, or 5.4 or greater, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, or 7.4 or less, or less than 7.5. More specifically, the a may be 5.4 or greater and 6.6 or less. In this case, an argyrodite phase having an appropriate lithium concentration can be formed, resulting in higher ionic conductivity.

[0033] The b can be 0 or more and 0.3, 0.4, 0.5, 0.6, or 0.7 or less. More specifically, the b can be 0 or more and 0.3 or less. In this case, the amount of cation doping (substitution amount) is appropriate, and the amount of impurities can be reduced.

[0034] The c may be greater than 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 or greater, or 1.6, 1.7, 1.8, 1.9, or 2.0 or less, in which case an argyrodite phase may be formed, the degree of disorder in anion arrangement may increase, and ionic conductivity may be higher.

[0035] The buffer layer may have a mixture of Li2CO3 and argyrodite-type crystal structures.

[0036] According to the present invention, the solid electrolyte has a wavelength of 5200 cm in the NIR spectrum. -1 ~4725cm -1The Li2CO3 band integral value present in the region may be 2.0 or more and 8.0 or less. Specifically, in the NIR spectrum, -1 ~4725cm -1 The Li2CO3 band integral value in the region may be 2.0 or more, 2.1 or more, 2.2 or more, 2.3 or more, 2.4 or more, 2.5 or more, 2.6 or more, 2.7 or more, 2.8 or more, 2.9 or more, 3.0 or more, 3.1 or more, 3.2 or more, or 3.3 or more, 6.6 or less, 6.7 or less, 6.8 or less, 6.9 or less, 7.0 or less, 7.1 or less, 7.2 or less, 7.3 or less, 7.4 or less, 7.5 or less, 7.6 or less, 7.7 or less, 7.8 or less, 7.9 or less, or 8.0 or less. In this case, an appropriate amount of buffer layer is formed, which is effective in blocking side reactions and has the advantage of higher ionic conductivity performance.

[0037] On the other hand, in the NIR spectrum of the solid electrolyte, -1 ~4725cm -1 If the Li2CO3 band integral value in the region is less than 2.0, the buffer layer is not sufficiently formed and there is no blocking effect on side reactions. If it exceeds 8.0, an excessive amount of impurity phases other than the argyrodite-type crystal structure is formed, resulting in low ionic conductivity.

[0038] According to the present invention, the solid electrolyte can have an ionic conductivity of 3 mS / cm to 12 mS / cm.

[0039] According to the present invention, the solid electrolyte has a wavelength of 7200 cm in the NIR spectrum. -1 ~7140cm -1 The LiOH band integral value present in the region may be less than 0.1. That is, the buffer layer of the solid electrolyte exposes the electrolyte particles at a sufficiently low dew point and can contain almost no lithium hydroxide. In this case, there are advantages in that the amount of secondary phase generated is small and the ionic conductivity is high. Specifically, the solid electrolyte has a LiOH band integral value present in the region of 7200 cm in the NIR spectrum. -1 ~7140cm -1 The LiOH band integral present in the region can be zero.

[0040] According to the present invention, in the 2p spectrum of phosphorus (P) obtained by XPS analysis of the solid electrolyte, PS4 3- peak area A1 and PO x S 4-x 3- the ratio A2 / (A1 + A2) of the peak area A2 of PO x S 4-x 3- can be less than 0.1, specifically 0.09 or less, and more specifically 0.085 or less (in PO x S 4-x 3- , x is 0 < x < 4). That is, the buffer layer of the solid electrolyte has the bonds within the PS4 3- unit not decomposed, and there may be no PO x S 4-x 3- bond. In this case, there is an advantage that the amount of the secondary phase generated is small and the ion conductivity performance is high.

[0041] The solid electrolyte according to the present invention can be produced, for example, by exposing sulfide-based solid electrolyte particles in an atmosphere with a dew point temperature exceeding -40°C and not exceeding -20°C so that a trace amount of moisture and carbon dioxide react with the sulfide-based solid electrolyte particles, forming a buffer layer containing Li2CO3 on the sulfide-based solid electrolyte particles, and then drying the sulfide-based solid electrolyte particles on which the buffer layer containing Li2CO3 is formed, but is not limited thereto.

[0042] Here, the exposure can be performed at room temperature in order to control the violent reaction with moisture. In the present invention, room temperature can mean 20°C to 25°C. Further, the exposure can be performed for 1 hour to 10 hours. Specifically, the exposure can be performed between 1 hour, 2 hours, 3 hours or more, 4 hours, 5 hours, and 10 hours or less. In this case, there is an advantage that a buffer layer having appropriate ion conductivity is generated.

[0043] Meanwhile, the drying may be vacuum drying, which is carried out under vacuum conditions, to rapidly remove residual moisture adsorbed on the surface. The drying may be carried out at a temperature of 50°C to 150°C to sufficiently remove moisture and prevent particle agglomeration. Specifically, the drying may be carried out at a temperature of 50°C, 55°C, or higher, or 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, or lower than 150°C. The drying may be carried out for 5 to 24 hours to sufficiently remove moisture. Specifically, the drying may be carried out for 5, 7, or 9 hours or more, or 10, 12, or 24 hours or less.

[0044] All solid state battery The present invention provides an all-solid-state battery containing the solid electrolyte.

[0045] Specifically, the all-solid-state battery includes a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, and a solid electrolyte layer containing the solid electrolyte according to the present invention disposed between the positive electrode and the negative electrode.

[0046] The all-solid-state battery according to the present invention has little decrease in ionic conductivity due to moisture, and can have excellent initial efficiency, life characteristics, and output characteristics.

[0047] The all-solid-state battery of the present invention can be manufactured by a conventional method known in the art, for example, by stacking a positive electrode and a negative electrode so that a solid electrolyte layer is present between them and applying pressure.

[0048] (1) Positive electrode The positive electrode may be prepared by coating a positive electrode current collector with a positive electrode slurry containing a positive electrode active material, a binder, a conductive material, and a solvent.

[0049] The positive electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has conductivity. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or those obtained by surface treatment of the surface of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. can be used. Also, fine irregularities can be formed on the surface to strengthen the binding force of the positive electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven fabrics, etc.

[0050] The positive electrode active material can include a compound capable of reversible intercalation and deintercalation of lithium, specifically, a lithium metal oxide containing one or more metals such as cobalt, manganese, nickel, or aluminum and lithium. More specifically, the lithium metal oxide can be a lithium-manganese-based oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt-based oxide (e.g., LiCoO2, etc.), a lithium-nickel-based oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese-based oxide (e.g., LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2-z Ni z O4 (where 0 < Z < 2), etc.), a lithium-nickel-cobalt-based oxide (e.g., LiNi 1-Y1 Co<o Y1 [[ID=k16]]O2 (where 0 < Y1 < 1), etc.), a lithium-manganese-cobalt-based oxide (e.g., LiCo 1-Y2 Mn Y2 O2 (where 0 < Y2 < 1), LiMn 2-z1 Co z1 O4 (where 0 < Z1 < 2), etc.), a lithium-nickel-manganese-cobalt-based oxide (e.g., Li(Ni p Co q Mn r1 )O2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) or Li(Ni p1 Co q1 Mn r2 It should be noted that there seems to be a typo in the original text where "<o Y1 " appears. It should probably be " Y1 ". The translation has been done based on the best understanding of the text with this in mind.)O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2), etc.), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r3 M S2 )O2 (where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r3, and s2 are the atomic fractions of the respective independent elements, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1), etc.), and any one or two or more of these compounds can be included.

[0051] Among them, in terms of being able to enhance the capacity characteristics and stability of the battery, the lithium metal oxide is LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxide (e.g., Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2, and Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc.), or lithium nickel cobalt aluminum oxide (e.g., Li(Ni 0.8 Co 0.15 Al 0.05 )O2, etc.), and considering the remarkable improvement effect by controlling the types and content ratios of the constituent elements forming the lithium composite metal oxide, the lithium composite metal oxide is Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15Co 0.15 )O2, and Li(Ni 0.8 Mn 0.1 Co 0.1 ) O2, etc., and any one or a mixture of two or more of these can be used.

[0052] The positive electrode active material may be contained in an amount of 60% by weight to 99% by weight, preferably 70% by weight to 99% by weight, and more preferably 80% by weight to 98% by weight, based on the total weight of solids other than the solvent in the positive electrode slurry.

[0053] The binder is a component that helps bind the conductive material, active material, and current collector together. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof.

[0054] Typically, the binder can be contained in an amount of 1 wt % to 20 wt %, preferably 1 wt % to 15 wt %, and more preferably 1 wt % to 10 wt %, based on the total weight of solids other than the solvent in the positive electrode slurry.

[0055] The conductive material is a component for further improving the conductivity of the positive electrode active material.

[0056] The conductive material is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity. For example, carbon-based materials such as graphite; carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives may be used.

[0057] Typically, the conductive material can be contained in an amount of 1 wt % to 20 wt %, preferably 1 wt % to 15 wt %, and more preferably 1 wt % to 10 wt %, based on the total weight of solids other than the solvent in the positive electrode slurry.

[0058] The solvent may include an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a desired viscosity when the positive electrode active material and, optionally, a binder and a conductive material are included. For example, the solvent may be included so that the concentration of the solids including the positive electrode active material and, optionally, a binder and a conductive material is 50 wt % to 95 wt %, preferably 70 wt % to 95 wt %, and more preferably 70 wt % to 90 wt %.

[0059] (2) Negative electrode The negative electrode can be prepared by, for example, coating a negative electrode current collector with a negative electrode slurry containing a negative electrode active material, a binder, a conductive material, and a solvent, or a graphite electrode made of carbon (C) or a metal itself can be used as the negative electrode.

[0060] For example, when the negative electrode is manufactured by coating the negative electrode slurry onto the negative electrode current collector, the negative electrode current collector typically has a thickness of 3 to 500 μm. Such a negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surfaces treated with carbon, nickel, titanium, silver, or the like, aluminum-cadmium alloys, etc., can be used. Furthermore, similar to the positive electrode current collector, the surface can be formed with fine irregularities to strengthen the binding strength of the negative electrode active material, and the negative electrode current collector can be used in various forms such as a film, sheet, foil, mesh, porous material, foam, nonwoven fabric, etc.

[0061] Examples of the negative electrode active material include natural graphite, artificial graphite, carbonaceous materials, lithium-containing titanium composite oxide (LTO), Si, SiO x , Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe; alloys composed of the metals (Me); oxides of the metals (Me) (MeO x and composites of the metals (Me) with carbon. Specific examples of the negative electrode active material include silicon (Si), silicon oxide (SiO x Silicon-based negative electrode active materials, such as silicon dioxide, silicon nitride, silicon carbide ...

[0062] The negative electrode active material may be contained in an amount of 60% by weight to 99% by weight, preferably 70% by weight to 99% by weight, and more preferably 80% by weight to 98% by weight, based on the total weight of solids other than the solvent in the negative electrode slurry.

[0063] The binder is a component that helps bind the conductive material, active material, and current collector together. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof.

[0064] Typically, the binder can be contained in an amount of 1 wt % to 20 wt %, preferably 1 wt % to 15 wt %, and more preferably 1 wt % to 10 wt %, based on the total weight of solids other than the solvent in the negative electrode slurry.

[0065] The conductive material is a component for further improving the conductivity of the negative electrode active material. The conductive material is not particularly limited as long as it does not cause chemical changes in the battery and has conductivity, and examples thereof include graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0066] The conductive material may be contained in an amount of 1 wt % to 20 wt %, preferably 1 wt % to 15 wt %, and more preferably 1 wt % to 10 wt %, based on the total weight of solids other than the solvent in the negative electrode slurry.

[0067] The solvent may include water or an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a desired viscosity when the negative electrode active material and, optionally, a binder and a conductive material are included. For example, the solvent may be included so that the concentration of the solids, including the negative electrode active material and, optionally, a binder and a conductive material, is 50 wt % to 95 wt %, preferably 70 wt % to 90 wt %.

[0068] When a metal is used as the anode, the anode can be fabricated by physically bonding, rolling, or depositing a metal thin film on the anode current collector or the metal thin film itself. The deposition method can be electrolytic deposition or chemical vapor deposition.

[0069] For example, the metal thin film itself or the metal bonded / rolled / deposited on the negative electrode current collector may include one metal or an alloy of two metals selected from the group consisting of lithium (Li), nickel (Ni), tin (Sn), copper (Cu), and indium (In).

[0070] (3) Solid electrolyte layer The solid electrolyte layer may further contain a binder in addition to the solid electrolyte according to the present invention.

[0071] The binder is a component that helps bind the conductive material, active material, and current collector together. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof.

[0072] Generally, the binder can be contained in an amount of 1 to 20% by weight, preferably 1 to 15% by weight, and more preferably 1 to 10% by weight, based on the total weight of the solid electrolyte layer.

[0073] The present invention provides a battery module including the all-solid-state battery as a unit cell, and a battery pack including the same. The battery module and battery pack include the secondary battery having high capacity, excellent rate-limiting characteristics, and excellent cycle characteristics, and can be used as a power source for medium- to large-sized devices selected from the group consisting of electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems.

[0074] In the following, preferred embodiments will be presented to facilitate understanding of the present invention. However, the above embodiments are merely illustrative of the present description, and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope of the scope and technical ideas of the present description. It goes without saying that such changes and modifications fall within the scope of the appended claims.

[0075] Manufacturing example Manufacturing Example 1 Four precursors, Li2S, P2S5, LiCl, and LiBr, were dry mixed (ball milled) in a molar ratio of 1.9:0.5:0.6:1.0. During the dry mixing, a planetary ball mill equipped with zirconia balls was used, and the rotation speed was 300 rpm or more to ensure uniform mixing. The obtained mixed precursor was then heat-treated at 400-550°C for 12 hours to crystallize it, and then pulverized again by ball milling to obtain Li with an argyrodite-type crystal structure. 5.4 P 4.4 Cl 0.6 Br 1.0 The particles were prepared. All of the above steps were carried out under an inert Ar atmosphere.

[0076] Manufacturing Example 2 Four precursors, Li2S, P2S5, LiCl, and LiBr, were dry mixed (ball milled) in a molar ratio of 2.0:0.5:0.5:1.0. During the dry mixing, a planetary ball mill equipped with zirconia balls was used, and the rotation speed was 300 rpm or more to ensure uniform mixing. The obtained mixed precursor was then heat-treated at 400-550°C for 12 hours to crystallize it, and then pulverized again by ball milling to obtain Li with an argyrodite-type crystal structure. 5.5 PS 4.5 Cl 0.5 Br 1.0 The particles were prepared. All of the above steps were carried out under an inert Ar atmosphere.

[0077] Manufacturing Example 3 Four precursors, Li2S, P2S5, LiCl, and LiBr, were dry mixed (ball milled) in a molar ratio of 1.9:0.5:1.0:0.6. During the dry mixing, a planetary ball mill containing zirconia balls was used, and the rotation speed was 300 rpm or higher to ensure uniform mixing. The obtained mixed precursor was then heat-treated at 400-550°C for 12 hours to crystallize it, and then pulverized again by ball milling to obtain Li with an argyrodite-type crystal structure. 5.4 PS 4.4 Cl 1.0 Br 0.6 The particles were prepared. All of the above steps were carried out under an inert Ar atmosphere.

[0078] Manufacturing Example 4 Three precursors, Li2S, P2S5, and LiCl, were dry mixed (ball milled) in a molar ratio of 2:0.5:1.5. During the dry mixing, a planetary ball mill containing zirconia balls was used, and the rotation speed was 300 rpm or more to ensure uniform mixing. The mixed precursor was then heat-treated at 400-550°C for 12 hours to crystallize it, and then pulverized again by ball milling to obtain Li2S with an argyrodite-type crystal structure. 5.5 PS 4.5 Cl 1.5 The particles were prepared. All of the above steps were carried out under an inert Ar atmosphere.

[0079] Production Example 5 Three precursors, Li2S, P2S5, and LiBr, were dry mixed (ball milled) in a molar ratio of 2.5:0.5:1.0. A planetary ball mill equipped with zirconia balls was used for dry mixing, rotating at a speed of 300 rpm or higher to ensure uniform mixing. The resulting precursor mixture was then heat-treated at 400-550°C for 12 hours to crystallize it, and then ball-milled again to produce Li6PS5Br particles with an argyrodite-type crystal structure. All of the above processes were carried out in an inert Ar atmosphere.

[0080] Manufacturing Example 6 Three precursors, Li2S, P2S5, and LiCl, were dry mixed (ball milled) in a molar ratio of 2.5:0.5:1.0. A planetary ball mill equipped with zirconia balls was used for dry mixing, rotating at a speed of 300 rpm or higher to ensure uniform mixing. The resulting mixed precursor was then heat-treated at 400-550°C for 12 hours to crystallize it, and then ball-milled again to produce Li6PS5Cl particles with an argyrodite-type crystal structure. All of the above processes were carried out in an inert Ar atmosphere.

[0081] Examples and Comparative Examples Example 1 Li having an argyrodite-type crystal structure produced in Production Example 1 5.4 PS 4.4 Cl 0.6 Br 1.0 The particles were exposed to the atmosphere at room temperature with a dew point of −30° C. for 5 hours, and then vacuum dried at 80° C. for 12 hours to prepare solid electrolyte A.

[0082] Example 2 Li having an argyrodite-type crystal structure produced in Production Example 1 5.4 PS 4.4 Cl 0.6 Br 1.0 The particles were exposed to the atmosphere at room temperature with a dew point of −35° C. for 5 hours, and then vacuum dried at 80° C. for 12 hours to prepare solid electrolyte B.

[0083] Example 3 Li having an argyrodite-type crystal structure produced in Production Example 1 5.4 PS 4.4 Cl 0.6 Br 1.0 The particles were exposed to the atmosphere at room temperature with a dew point of −25° C. for 5 hours, and then vacuum dried at 80° C. for 12 hours to prepare solid electrolyte C.

[0084] Example 4 Li having an argyrodite-type crystal structure produced in Production Example 2 5.5 PS 4.5 Cl 0.5 Br 1.0 The particles were exposed to the atmosphere at room temperature with a dew point of −30° C. for 5 hours, and then vacuum dried at 80° C. for 12 hours to prepare solid electrolyte D.

[0085] Example 5 Li having an argyrodite-type crystal structure produced in Production Example 3 5.4 PS 4.4 Cl 1.0 Br 0.6 The particles were exposed to the atmosphere at room temperature with a dew point of −30° C. for 5 hours, and then vacuum dried at 80° C. for 12 hours to prepare solid electrolyte E.

[0086] Example 6 Li having an argyrodite-type crystal structure produced in Production Example 4 5.5 PS 4.5 Cl 1.5 The particles were exposed to the atmosphere at room temperature with a dew point of −30° C. for 5 hours, and then vacuum dried at 80° C. for 12 hours to prepare solid electrolyte F.

[0087] Comparative Example 1 Li having an argyrodite-type crystal structure produced in Production Example 1 5.4 PS 4.4 Cl 0.6 Br 1.0 was used as solid electrolyte G in Comparative Example 1.

[0088] Comparative Example 2 Li having an argyrodite-type crystal structure produced in Production Example 3 5.4 PS4.4 Cl 1.0 Br 0.6 was used as the solid electrolyte H in Comparative Example 1.

[0089] Comparative Example 3 Li having an argyrodite-type crystal structure produced in Production Example 1 5.4 PS 4.4 Cl 0.6 Br 1.0 The particles were exposed to the atmosphere at room temperature with a dew point of −40° C. for 5 hours, and then vacuum dried at 80° C. for 12 hours to prepare solid electrolyte I.

[0090] Comparative Example 4 Li having an argyrodite-type crystal structure produced in Production Example 1 5.4 PS 4.4 Cl 0.6 Br 1.0 The particles were exposed to the atmosphere at room temperature with a dew point of 10° C. for 3 hours, and then vacuum dried at 80° C. for 12 hours to prepare solid electrolyte J.

[0091] Comparative Example 5 Li having an argyrodite-type crystal structure produced in Production Example 4 5.5 PS 4.5 Cl 1.5 was used as the solid electrolyte K in Comparative Example 10.

[0092] Comparative Example 6 The Li6PS5Br particles having an argyrodite-type crystal structure prepared in Preparation Example 5 were exposed to the atmosphere at a dew point of −30° C. for 5 hours at room temperature, and then left for 7 weeks without drying to prepare solid electrolyte L.

[0093] Comparative Example 7 The Li6PS5Cl particles having an argyrodite-type crystal structure prepared in Preparation Example 6 were exposed to the atmosphere at a dew point of 10°C for 3 hours at room temperature, and then vacuum dried at 80°C for 12 hours to prepare a solid electrolyte M.

[0094] Experimental Example Experimental Example 1: Crystal structure analysis The crystalline morphology of the solid electrolyte prepared in Example 5 was observed by X-ray diffraction (XRD). Figure 1 shows the XRD peaks of the solid electrolyte of Example 5.

[0095] Referring to FIG. 1, it can be seen that the solid electrolyte of Example 5 has an argyrodite-type crystal structure.

[0096] Experimental Example 2: Solid Electrolyte Surface Analysis (1)NIR analysis Measuring device: ABB MB3600

[0097] Spec: -Covering Range:3,700to 14,885cm -1 range -Interferometer Mechanism:High-throughput doble pivot Michelson -NIR Source:Quartz-halogen(Elec.Controlled) -Lase Source:Solid-state Laser(Long lifetime) -Optics materials:Completely non-Hygroscopic optics(ZnSe) -TE cooled InGaAs detector

[0098] The solid electrolyte powders prepared in the Examples and Comparative Examples were taken and placed in glass vials, and then an FT-NIR diffuse reflectance accessory was attached to measure the NIR reflectance spectrum of the solid electrolyte in the glass vial (8 cm -1 resolution, 32 scans). 5300cm -1 , 4685cm -1 After baseline correction, the NIR spectrum of each of the solid electrolytes A to M showed a peak at 5200 cm -1~4725cm -1 The Li2CO3 band integral value in the region was confirmed. -1 , 7120cm -1 After baseline correction, 7200 cm -1 ~7140cm -1 The LiOH band integrals present in the region were determined and are shown in Table 1 below.

[0099] (2)XPS analysis Measurement equipment: K-Alpha+ manufactured by ThermoFisher Scientific Inc.

[0100] Spec: -X-ray source: monochromatic Al Kα (1486.6eV) -Operation mode: CAE (Constant Analyzer Energy) mode -Software: Avantage software (version 5.992) -X-ray spot size: 400μm -Charge compensation:default FG03 mode(100μA, 0.5V) -Pass energy: 50 eV

[0101] A pellet-shaped sample was attached to a sample holder in an argon-filled glove box. To prevent exposure to the atmosphere, the sample was capped using a VTM (Vacuum Transfer Module) holder and then placed in the device chamber. The binding energy range of 120 eV to 140 eV was scanned at an energy step of 0.1 eV.

[0102] After peak fitting of the 2p spectrum of phosphorus (P) obtained by XPS analysis of each of the solid electrolytes A to M, PS4 corresponding to the binding energy of 131.63 eV was obtained. 3- PO corresponding to the peak area A1 and the 132.85 eV position x S 4-x 3- The peak area A2 was obtained, and the A2 / (A1+A2) value was calculated and shown in Table 1 below. The peak fitting conditions applied were an L / G ratio of 0.3, FWHM of 0.9 to 1.2 eV, and an energy difference of 1.3±0.1 eV.

[0103] FIG. 2 shows XPS data of the solid electrolytes of Examples 1 to 3 and Comparative Examples 3 and 6.

[0104] [Table 1]

[0105] Experimental Example 3: Evaluation of ionic conductivity of solid electrolytes 150 mg of each of the solid electrolyte powders from Examples 1 to 6 and Comparative Examples 1 to 7 was placed in a 13 mm diameter SUS mold. The mold, along with the insulating PEEK, was attached to a press, and a potentiostat was connected to the SUS mold. After applying a pressure of 370 MPa to sufficiently densify the electrolyte structure, the pressure was gradually reduced to maintain 100 MPa, and AC impedance measurements were performed at frequencies from 1 Hz to 7 MHz. The ionic conductivity (initial ionic conductivity) was calculated from the measured resistance values ​​using a Nyquist plot, and is shown in Table 2 below. All measurements were performed in a dry room at a temperature of 22°C and a relative humidity of 0.7%.

[0106] Immediately after 5 hours of exposure to the atmosphere at a relative humidity of 1.91% for each of the solid electrolyte powders prepared in Examples 1 to 6 and Comparative Examples 1 to 3 and 5, 150 mg of each powder was taken and placed in a 13 mm diameter SUS mold. The mold, along with the insulating PEEK, was attached to a press, and a potentiostat was connected to the SUS mold. After applying a pressure of 370 MPa to sufficiently densify the electrolyte structure, the pressure was gradually reduced to maintain 100 MPa while AC impedance measurements were performed at frequencies from 1 Hz to 7 MHz. The ionic conductivity after moisture exposure was calculated from the measured resistance values ​​using a Nyquist plot, and the ionic conductivity retention rate was calculated using Equation 1 below, as shown in Table 2. All measurements were performed in a dry room at a temperature of 22°C and a relative humidity of 0.7%. On the other hand, the initial ionic conductivity of the solid electrolyte powders of Comparative Examples 4, 6, and 7 was too low to evaluate the ionic conductivity retention rate.

[0107]

number

[0108] [Table 2]

[0109] Referring to Table 1, the solid electrolytes of Examples 1 to 6 not only included a buffer layer containing Li2CO3 formed on the particles, but also showed a peak at 5200 cm in the NIR spectrum. -1 ~4725cm -1 It can be confirmed that the Li2CO3 band integral value present in the region is between 2.0 and 8.0.

[0110] On the other hand, in the case of Comparative Examples 1, 2, and 5, which were not surface-treated, the NIR spectrum detected a Li2CO3 band integral value at the same level as an impurity, confirming that no buffer layer was present on the solid electrolyte particles. Similarly, in the case of Comparative Example 3, the NIR spectrum detected a Li2CO3 band integral value at the same level as an impurity, confirming that almost no buffer layer was present on the solid electrolyte particles. This indicates that the solid electrolytes of Comparative Examples 1, 2, 3, and 5 do not maintain a stable phase during the battery manufacturing process, which can lead to degradation of battery performance.

[0111] In addition, in the case of Comparative Example 6, which was left without drying treatment after the surface treatment (no removal of moisture adsorbed on the surface), phase decomposition occurred over time, and the NIR spectrum showed a peak at 5200 cm -1 ~4725cm -1 The Li2CO3 band integral value present in the region exceeds 8.0, and the PO measured by XPS x S 4-x 3- It can be seen that the binding peak increases, which leads to the problem of low ionic conductivity.

[0112] In the cases of Comparative Examples 4 and 7, a buffer layer was formed, but not only was it formed excessively, but an excessive amount of argyrodite decomposition phase was also generated, and in the NIR spectrum, -1 ~4725cm -1 The Li2CO3 band integral in the region is much larger than 8.0, which is a problem of low ionic conductivity.

[0113] Experimental Example 4: Rate-limiting evaluation of all-solid-state batteries LiNi as the positive electrode active material 0.8 Co 0.1 Mn 0.1O2 was used as a solid electrolyte in Example 1 and Comparative Example 1, and carbon nanofiber (CNF) was used as a conductive material. The solid electrolytes were then mixed in a weight ratio of 60:35:5 to prepare a positive electrode composition. The positive electrode composition was applied to a solid electrolyte filled in a 13 mm diameter load cell, and a current of 3 mAh / cm was applied. 2 The positive electrode was manufactured by uniformly distributing the loading amount. Then, a flat press was used to apply pressure to the load cell, and the screws were tightened. The measured pressure of the load cell was 35 MPa. A 100 μm thick lithium metal was used as the negative electrode, and a load cell (all-solid-state battery) with a negative electrode / solid electrolyte / positive electrode structure was manufactured.

[0114] The fabricated all-solid-state battery was maintained at a temperature of 60°C and charged in constant current / constant voltage (CC / CV) mode at a 0.05C rate limiting state up to an upper voltage of 4.25V, and then discharged in CC mode at 0.05C to an end voltage of 3V, performing the initial two charge / discharge cycles. After that, the battery was charged at a rate of 0.1C, and the discharge rate was gradually changed to 0.1C, 0.2C, 0.33C, 0.5C, 1.0C, and 0.1C to evaluate the rate-limiting characteristics, and the results are shown in Figure 3.

[0115] FIG. 3 shows evaluation data of the rate-limiting characteristics of all-solid-state batteries containing the solid electrolytes of Example 1 and Comparative Example 1.

[0116] Referring to FIG. 3, in the case of the all-solid-state battery including the solid electrolyte of Example 1 according to the present invention, the NIR spectrum shows a peak at 5200 cm -1 ~4725cm -1 It can be confirmed that the rate-determining characteristics are superior to those of the all-solid-state battery including the solid electrolyte of Comparative Example 1, in which the Li2CO3 band integral value present in the region is less than 0.2.

[0117] That is, the solid electrolyte according to the present invention not only includes a buffer layer containing Li2CO3 formed on the particles, but also has a peak at 5200 cm in the NIR spectrum. -1 ~4725cm -1The Li2CO3 band integral value in this region is between 2.0 and 8.0, and it can be seen that a stable phase is maintained when exposed to water during the battery manufacturing process, which can suppress interfacial side reactions between the solid electrolyte and electrode materials and improve battery performance.

Claims

1. sulfide-based solid electrolyte particles; The Li formed on the sulfide-based solid electrolyte particles ２ CO ３ and a buffer layer comprising In the NIR spectrum, 5200 cm －１ ~4725cm －１ Li present in the region ２ CO ３ A solid electrolyte having a band integral value of 2.0 or more and 8.0 or less.

2. The solid electrolyte according to claim 1 , wherein the sulfide-based solid electrolyte has an argyrodite-type crystal structure.

3. The solid electrolyte according to claim 1 , wherein the sulfide-based solid electrolyte has a composition represented by the following chemical formula 1: [Chemical formula 1] Li ａ (P) １－ｂ M ｂ S ６－ｃ X ｄ In the above Chemical Formula 1, M is one or more selected from Sb, Sn, Ge, Si, Nb, Ni, Ga, and Al; X is one or more selected from F, Cl, Br and I; 5.0<a<7.5, 0≦b≦0.7, 0<c≦2.

0.

4. 2. The solid electrolyte according to claim 1, having an ionic conductivity of 3 mS / cm to 12 mS / cm.

5. In the NIR spectrum, 7200 cm －１ ~7140cm －１ 2. The solid electrolyte of claim 1, wherein the LiOH band integral present in the region is less than 0.

1.

6. The 2p spectrum of phosphorus (P) obtained by XPS analysis shows that PS ４ ３－ Peak area A １ and P.O. ｘ S ４－ｘ ３－ Peak area A ２ PO for the sum of ｘ S ４－ｘ ３－ Peak area A ２ Ratio A ２ / (A １ +A ２ 2. The solid electrolyte of claim 1, wherein σ is less than 0.

1.

7. An all-solid-state battery comprising the solid electrolyte according to any one of claims 1 to 6.

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