Solid electrolyte, electrochemical cell comprising solid electrolyte, and Method for preparing solid electrolyte

Abstract

A solid electrolyte comprising a compound having an azirodite crystal structure represented by the following chemical formula 1, an electrochemical cell comprising the same, and a method for manufacturing the same are presented. (Li1-aMa)7-d+xPS6-d-x+k(N)x(X)d In Chemical Formula 1, M is sodium (Na), potassium (K), calcium (Ca), iron (Fe), magnesium (Mg), silver (Ag), copper (Cu), zirconium (Zr), zinc (Zn), or a combination thereof, and X is chlorine (Cl), bromine (Br), fluorine (F), iodine (I), pseudohalogen, or a combination thereof, and 0

Description

Technology Field

[0001] The present invention relates to a solid electrolyte, an electrochemical cell containing the same, and a method for manufacturing the solid electrolyte. Background Technology

[0002] Recently, driven by industrial demands, the development of batteries with high energy density and safety is actively underway. For example, lithium-ion batteries are being commercialized not only in the fields of information and communication devices but also in the automotive sector. In the automotive sector, safety is considered particularly important because it is directly related to human life.

[0003] Currently commercially available lithium-ion batteries use electrolytes containing flammable organic solvents, so there is a possibility of overheating and fire in the event of a short circuit. In response to this, all-solid-state batteries using solid electrolytes instead of liquid electrolytes are being proposed.

[0004] By not using flammable organic solvents, all-solid-state batteries can significantly reduce the likelihood of fire or explosion in the event of a short circuit. Therefore, these all-solid-state batteries can offer significantly higher safety compared to lithium-ion batteries that use liquid electrolytes.

[0005] Sulfide-based solid electrolytes with excellent ionic conductivity are used as solid electrolytes for all-solid-state batteries. However, sulfide-based solid electrolytes have poor oxidation stability at high potentials, so improvement in this regard is required. The problem to be solved

[0006] One aspect is providing a solid electrolyte containing nitrogen.

[0007] Another aspect is to provide an electrochemical cell with improved high rate and lifespan characteristics by containing the aforementioned solid electrolyte.

[0008] Another aspect is to provide a method for manufacturing the above-mentioned solid electrolyte. means of solving the problem

[0009] According to one aspect, a solid electrolyte is provided comprising a compound represented by the following chemical formula 1 and having an argyrodite crystal structure.

[0010] <Chemical Formula 1>

[0011] (Li 1-a M a ) 7-d+x PS 6-d-x+k (N) x (X) d

[0012] In Chemical Formula 1, M is sodium (Na), potassium (K), calcium (Ca), iron (Fe), magnesium (Mg), silver (Ag), copper (Cu), zirconium (Zr), zinc (Zn), or a combination thereof, and

[0013] X is chlorine (Cl), bromine (Br), fluorine (F), iodine (I), pseudohalogen, or a combination thereof, and

[0014] 0 <x<1, 0≤a<1, 0<d≤1.8, 0≤k<1이다.

[0015] According to another aspect, it comprises an anode layer; a cathode layer; and a solid electrolyte layer disposed between the anode layer and the cathode layer, and

[0016] An electrochemical cell is provided that includes at least one selected from the solid electrolyte layer and the anode layer described above, and the solid electrolyte described above.

[0017] According to another aspect, a step of providing a precursor mixture by mixing a sulfur (S) precursor, a phosphorus (P) precursor, an X precursor, and a nitrogen (N) precursor; and

[0018] A method for manufacturing a solid electrolyte is provided, comprising the step of reacting the above mixture to obtain a solid electrolyte precursor and heat-treating at 300°C or higher, wherein X of the X precursor is chlorine (Cl), bromine (Br), fluorine (F), iodine (I), pseudohalogen, or a combination thereof.

[0019] M precursor is further added to the above precursor mixture, and M of the M precursor is sodium (Na), potassium (K), calcium (Ca), iron (Fe), magnesium (Mg), silver (Ag), copper (Cu), zirconium (Zr), zinc (Zn), or a combination thereof. Effects of the invention

[0020] In one aspect, a solid electrolyte with excellent ionic conductivity and improved rate characteristics and cycle characteristics can be provided. Using such a solid electrolyte, an electrochemical cell with improved capacity retention and cycle characteristics can be manufactured. Brief explanation of the drawing

[0021] Figure 1 shows the XRD spectra for the solid electrolytes prepared in Examples 1-2 and Comparative Example 1. Figure 2 is a graph showing the change in capacity characteristics of the all-solid-state secondary batteries of Examples 6 and 7 and the all-solid-state secondary battery of Comparative Example 4. Figure 3 is a graph showing the characteristics by rate of the all-solid-state secondary batteries of Examples 6 and 7 and the all-solid-state secondary battery of Comparative Example 4. Figure 4 is a graph showing the change in discharge capacity according to the number of cycles of the all-solid-state secondary batteries prepared in Examples 6-7 and Comparative Example 4. Figure 5 is a graph showing the capacity retention rate of the all-solid-state secondary batteries prepared in Examples 6-7 and Comparative Example 4. FIGS. 6 to 8 are cross-sectional views of an all-solid-state secondary battery according to an exemplary embodiment. Specific details for implementing the invention

[0022] A solid electrolyte according to one embodiment, an electrochemical cell containing the solid electrolyte, and a method for manufacturing the same will be described in more detail.

[0023] A solid electrolyte is provided comprising a compound represented by the following chemical formula 1 and having an azirodite crystal structure.

[0024] <Chemical Formula 1>

[0025] (Li 1-a M a ) 7-d+x PS 6-d-x+k (N) x (X) d

[0026] In Chemical Formula 1, M is sodium (Na), potassium (K), calcium (Ca), iron (Fe), magnesium (Mg), silver (Ag), copper (Cu), zirconium (Zr), zinc (Zn), or a combination thereof, and X is chlorine (Cl), bromine (Br), fluorine (F), iodine (I), pseudohalogen, or a combination thereof, and 0 <x<1, 0≤a<1, 0<d≤1.8, 0≤k<1이다.

[0027] In Chemical Formula 1, if M is a monovalent element such as sodium (Na), potassium (K), or silver (Ag), k=0, and if M is a divalent, trivalent, or tetravalent element such as calcium (Ca), iron (Fe), magnesium (Mg), copper (Cu), zirconium (Zr), or zinc (Zn), k=0. <k<1이다. 여기에서 k의 수치는 화학식 1의 화합물이 전기적으로 중성이 되도록 정해진다.

[0028] The compound of Chemical Formula 1 above may be a compound represented by the following Chemical Formula 1-1.

[0029] <Chemical Formula 1-1>

[0030] (Li 1-a M a ) 7-d+x PS 6-d-x (N) x (X) d

[0031] In Chemical Formula 1-1, M is sodium (Na), potassium (K), calcium (Ca), iron (Fe), magnesium (Mg), silver (Ag), copper (Cu), zirconium (Zr), zinc (Zn), or a combination thereof, and

[0032] X is chlorine (Cl), bromine (Br), fluorine (F), iodine (I), pseudohalogen, or a combination thereof, and 0 <x<1, 0≤a<1, 0<d≤1.8이다.

[0033] In this specification, "pseudohalogen" refers to a molecule composed of two or more electronegative atoms that resemble halogens in the free state and generate anions similar to halide ions. Examples of pseudohalogens are cyanide (CN), cyanate (OCN), thiocyanate (SCN), azide (N3), or combinations thereof.

[0034] In the solid electrolyte according to one embodiment, the nitrogen content is greater than 0 and less than 10 mol% based on the total content of sulfur and nitrogen, for example, greater than 0 and less than 5 mol%, for example, 1 to 5 mol%.

[0035] 0 in the above chemical formulas 1 and 1-1 <x≤0.5이다.

[0036] According to one embodiment, in chemical formulas 1 and 1-1, 0 <d≤1이다.

[0037] According to one embodiment, X of Chemical Formula 1 is Cl. According to another embodiment, X is Cl and at least one of F, Br, or I.

[0038] (X) in the above chemical formulas 1 and 1-1 d is (Cl) d , (Br) d , or (Br 1-x2 (Cl) x2 ) d and 0 <x2<1, 0<d≤1이다.

[0039] To increase the ionic conductivity of sulfide-based solid electrolytes having an agitite crystal structure, it is common practice to introduce large atomic elements into sulfur (S) to enhance the mobility of lithium. However, these sulfide-based solid electrolytes exhibit poor oxidation stability at high potentials during charging, leading to the formation of a resistive layer due to reactions at the interface between the solid electrolyte and the anode layer, thus requiring improvement.

[0040] Research on this topic has not been practically conducted because the addition of nitrogen to solid electrolytes with an agitite crystal structure is expected to result in a low improvement in ion conductivity due to the reduction in lithium vacancies and lattice volume.

[0041] However, the inventors have completed the present invention regarding a solid electrolyte containing nitrogen (N), which exhibits an interface stabilization effect by reducing the formation of a resistance layer caused by the reaction between the anode layer and the electrolyte interface through the inclusion of nitrogen, while maintaining an ionic conductivity of lithium equivalent to that of a sulfide-based electrolyte having a general azirodite-based crystal structure despite an increase in lithium content. The solid electrolyte is stable at high voltage and reduces side reactions in the interfacial reaction between the anode layer and the electrolyte, thereby enabling the manufacture of an electrochemical battery with increased discharge capacity and improved lifespan and rate-specific characteristics.

[0042] The azidite-based solid electrolyte according to one embodiment is, for example, a compound represented by the following chemical formula 2.

[0043] <Chemical Formula 2>

[0044] Li 7-d+x PS 6-d-x (N) x (X) d

[0045] In Chemical Formula 2, X is chlorine (Cl), bromine (Br), iodine (I), or a combination thereof, and

[0046] 0 <x<1, 0<d≤1이다.

[0047] 0 in the above chemical formula 2 <x≤0.9, 0<x≤0.8, 0<x≤0.6, 또는 0<x≤0.5이다.

[0048] In the above chemical formula 2 (X) d is (Cl) d , (Br) d , or (Br 1-x1 (Cl) x1 ) d and 0 <x1<1, 0<d≤1이다. x1은 예를 들어 0.1 내지 0.9, 예를 들어 0.2 내지 0.8, 0.3 내지 0.7, 0.4 내지 0.6, 또는 0.5이다.

[0049] The compound represented by the above chemical formula 1 is, for example, a compound represented by the following chemical formula 3 or chemical formula 4.

[0050] <Chemical Formula 3>

[0051] (Li 1-a Na a ) 7-d+x PS 6-d-x (N) x (X) d

[0052] In Chemical Formula 3, X is chlorine (Cl), bromine (Br), fluorine (F), iodine (I), pseudohalogen, or a combination thereof, and

[0053] 0 <x<1, 0<a<1, 0<d≤1이고,

[0054] <Chemical Formula 4>

[0055] (Li 1-a K a ) 7-d+x PS 6-d-x (N) x (X) d

[0056] In Chemical Formula 4, X is chlorine (Cl), bromine (Br), fluorine (F), iodine (I), pseudohalogen, or a combination thereof, and

[0057] 0 <x<1, 0<d≤1, 0<a<1이다.

[0058] The compound of Chemical Formula 1 may be a compound represented by, for example, Chemical Formula 5 below.

[0059] <Chemical Formula 5>

[0060] Li 7-d+x PS 6-d-x (N) x (Br 1-x1 (Cl) x1 ) d

[0061] Of chemical formula 5, 0 <x<1, 0<d≤1, 0<x1<1이다.

[0062] The compound represented by the above chemical formula 1 is, for example, Li 6.125 PS 4.875 N 0.125 Cl, Li 6.25 PS 4.75 N 0.25 Cl, Li 6.5 PS 4.5 N 0.5 Cl, Li6Na 0.125 PS 4.875 N 0.125 Cl, Li6Na 0.25 PS 4.75 N 0.25 Cl, Li6K 0.125 PS 4.875 N 0.125 Cl, Li6K 0.25 PS 4.75 N 0.25 Cl, Li 6.125 PS 4.875 N 0.125 Cl 0.5 Br 0.5 , Li 6.25 PS 4.75 N 0.25 Cl 0.5 Br 0.5 , Li6Na 0.125 PS 4.875 N 0.125 Cl 0.5 Br 0.5 , Li6Na 0.25 PS 4.75 N 0.25 Cl 0.5 Br 0.5 , Li6K 0.125 PS 4.875 N0.125 Cl 0.5 Br 0.5 , Li6K 0.25 PS 4.75 N 0.25 Cl 0.5 Br 0.5 , Li 6.125 PS 4.875 N 0.125 Cl 0.16 Br 0.84 , Li 6.25 PS 4.75 N 0.25 Cl 0.16 Br 0.84 , Li6Na 0.125 PS 4.875 N 0.125 Cl 0.16 Br 0.84 , Li6Na 0.25 PS 4.75 N 0.25 Cl 0.16 Br 0.84 , Li6K 0.125 PS 4.875 N 0.125 Cl 0.16 Br 0.84 , Li6K 0.25 PS 4.75 N 0.25 Cl 0.16 Br 0.84 , Li 6.125 PS 4.875 N 0.125 Br, Li 6.25 PS 4.75 N 0.25 Br, Li6Na 0.125 PS 4.875 N 0.125 Br, Li6Na 0.25 PS 4.75 N 0.25 Br, Li6K 0.125 PS 4.875 N 0.125 Br, Li6K 0.25 PS 4.75 N 0.25 Br, Li 6.115 Cu 0.01 PS 4.88 N 0.125 Cl, Li 6.115 Mg 0.01 PS 4.88 N0.125 Cl, Li 6.115 Ca 0.01 PS 4.88 N 0.125 Cl, Li 6.115 Fe 0.01 PS 4.88 N 0.125 Cl, Li 6.115 Zn 0.01 PS 4.88 N 0.125 Cl, Li 5.9 K 0.1 Na 0.125 PS 4.875 N 0.125 It is Cl or a combination thereof.

[0063] The solid electrolyte according to one embodiment can be used as an electrolyte and / or a positive electrode electrolyte material for an all-solid-state battery. In addition, the solid electrolyte can be used as a positive electrode and / or electrolyte for a lithium-sulfur battery.

[0064] The solid electrolyte according to one embodiment can be used as an anode electrolyte and can be used as a protective film for the negative electrode layer of a lithium metal battery.

[0065] The solid electrolyte according to one embodiment has an ionic conductivity of 1 mS / cm or more, 1.3 mS / cm or more, 1.5 mS / cm or more, 1.6 mS / cm or more, 2.0 mS / cm or more, 2.0 to 20 mS / cm, or 2.0 to 10 mS / cm at 25°C. Since the solid electrolyte has a high ionic conductivity of 1 mS / cm or more, it can be applied as an electrolyte for an electrochemical cell.

[0066] An electrochemical cell according to another embodiment comprises a positive electrode layer; a negative electrode layer; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein one or more selected from the solid electrolyte layer and the positive electrode layer comprises the solid electrolyte described above.

[0067] Since the solid electrolyte layer includes the solid electrolyte according to the above-described embodiment, side reactions with the lithium metal included in the negative electrode layer are suppressed, thereby improving the cycle characteristics of the electrochemical battery.

[0068] The electrochemical battery may be, for example, an all-solid-state secondary battery or a lithium-air battery, but is not necessarily limited to these; any electrochemical battery usable in the relevant technical field is acceptable.

[0069] In an electrochemical cell according to one embodiment, the positive electrode layer contains a compound represented by the following chemical formula 1 and includes a solid electrolyte having an argyrodite crystal structure.

[0070] <Chemical Formula 1>

[0071] (Li 1-a M a ) 7-d+x PS 6-d-x+k (N) x (X) d

[0072] In Chemical Formula 1, M is sodium (Na), potassium (K), calcium (Ca), iron (Fe), magnesium (Mg), silver (Ag), copper (Cu), zirconium (Zr), zinc (Zn), or a combination thereof, and

[0073] X is chlorine (Cl), bromine (Br), fluorine (F), iodine (I), pseudohalogen, or a combination thereof, and

[0074] 0 <x<1, 0≤a<1, 0<d≤1.8, 0≤k<1이다.

[0075] The compound of the above chemical formula 1 may be, for example, a compound represented by the following chemical formula 1-1.

[0076] <Chemical Formula 1-1>

[0077] (Li 1-a M a ) 7-d+x PS 6-d-x (N) x (X) d

[0078] In Chemical Formula 1-1, M is sodium (Na), potassium (K), iron (Fe), magnesium (Mg), calcium (Ca), silver (Ag), copper (Cu), zirconium (Zr), zinc (Zn), or a combination thereof, and

[0079] X is chlorine (Cl), bromine (Br), fluorine (F), iodine (I), pseudohalogen, or a combination thereof, and

[0080] 0 <x<1, 0<a<1, 0<d≤1.8이다.

[0081] In chemical formula 1-1, M is sodium (Na) or potassium (K).

[0082] The content of the solid electrolyte in the anode layer is 2 to 70 parts by weight, for example 3 to 70 parts by weight, for example 3 to 60 parts by weight, for example 10 to 60 parts by weight, based on 100 parts by weight of the anode active material. When the content of the solid electrolyte in the anode layer is within the above range, the high voltage stability of the electrochemical cell is improved.

[0083] The electrochemical cell according to one embodiment is charged at 4V or higher, for example 4.25V, in a constant temperature bath at 25℃, and discharged at 2.5V, and after 100 cycles, has a capacity retention rate of 85% or higher, for example 86% or higher, for example 88% or higher, for example 88 to 99.5%.

[0084] In an all-solid-state secondary battery according to one embodiment, the solid electrolyte used in the active material layer has a different particle size range than the solid electrolyte used in the solid electrolyte layer. For example, the solid electrolyte used in the active material layer has a smaller average particle size compared to the solid electrolyte used in the solid electrolyte layer.

[0085] The average particle size of the solid electrolyte used in the active material layer is 100 nm to 10 µm, 300 nm to 8 µm, or 500 nm to 5 µm, and the average particle size of the solid electrolyte used in the solid electrolyte layer is 500 nm to 20 µm, 700 nm to 15 µm, or 900 nm to 10 µm.

[0086] Hereinafter, an all-solid-state secondary battery will be described in more detail as an example of an electrochemical battery according to one embodiment.

[0087] Referring to FIGS. 6 to 8, the all-solid-state secondary battery (1) comprises a negative electrode layer (20) including a negative electrode current collector layer (21) and a first negative electrode active material layer (22); a positive electrode layer (10) including a positive electrode active material layer (12); and a solid electrolyte layer (30) disposed between the negative electrode layer (20) and the positive electrode layer (10). The positive electrode layer (10) may contain a solid electrolyte according to one embodiment. The positive electrode layer (10) contains, for example, a positive electrode active material, a solid electrolyte, and a conductive agent.

[0088] (Cathode layer)

[0089] Referring to FIGS. 6 to 8, the cathode layer (20) includes a cathode current collector layer (21) and a first cathode active material layer (22), and the first cathode active material layer (22) includes a cathode active material.

[0090] The negative electrode active material included in the first negative electrode active material layer (22) has, for example, a particle shape. The average particle size of the negative electrode active material having a particle shape is, for example, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or 900 nm or less. The average particle size of the negative electrode active material having a particle shape is, for example, 10 nm to 4 μm, 10 nm to 3 μm, 10 nm to 2 μm, 10 nm to 1 μm, or 10 nm to 900 nm. By having the negative electrode active material with an average particle size in this range, the reversible absorption and / or desorption of lithium during charging and discharging may be more easily facilitated. The average particle size of the negative electrode active material is, for example, the median diameter (D50) measured using a laser particle size distribution meter.

[0091] The cathode active material included in the first cathode active material layer (22) comprises, for example, one or more selected from carbon-based cathode active materials and metal or metalloid cathode active materials.

[0092] The carbon-based cathode active material is, in particular, amorphous carbon. Amorphous carbon is, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, etc., but is not necessarily limited to these, and any material classified as amorphous carbon in the relevant technical field is acceptable. Amorphous carbon is carbon that does not have crystallinity or has very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon.

[0093] The metal or metalloid cathode active material comprises one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), but is not necessarily limited to these; any metal cathode active material or metalloid cathode active material that forms an alloy or compound with lithium in the relevant technical field is acceptable. For example, nickel (Ni) is not a metal cathode active material because it does not form an alloy with lithium.

[0094] The first negative electrode active material layer (22) may include a type of negative electrode active material among these negative electrode active materials, or may include a mixture of multiple different negative electrode active materials. For example, the first negative electrode active material layer (22) may include only amorphous carbon, or one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Alternatively, the first negative electrode active material layer (22) may include a mixture of amorphous carbon and one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). In a mixture of amorphous carbon and an element such as gold, the mixing ratio of the amorphous carbon and the element such as gold is, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1 by weight, but is not necessarily limited to these ranges and is selected according to the required characteristics of the all-solid-state secondary battery (1). By having the negative electrode active material have this composition, the cycle characteristics of the all-solid-state secondary battery (1) are further improved.

[0095] The negative electrode active material included in the first negative electrode active material layer (22) comprises a mixture of first particles made of, for example, amorphous carbon and second particles made of a metal or metalloid. The metal or metalloid comprises, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), or a combination thereof. Alternatively, the metalloid is a semiconductor. The content of the second particles is 8 to 60 weight%, 10 to 50 weight%, 15 to 40 weight%, or 20 to 30 weight% based on the total weight of the mixture. By having the second particles in this range, the cycle characteristics of, for example, the all-solid-state secondary battery (1) are further improved.

[0096] The first negative electrode active material layer (22) includes, for example, a binder. The binder may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but is not necessarily limited to these, and any binder used in the relevant technical field may be used. The binder may be composed of a single binder or a plurality of different binders.

[0097] The first negative active material layer (22) is stabilized on the negative current collector (21) by including a binder. Additionally, cracking of the first negative active material layer (22) is suppressed despite changes in volume and / or relative position of the first negative active material layer (22) during the charging and discharging process. For example, if the first negative active material layer (22) does not include a binder, it is possible for the first negative active material layer (22) to be easily separated from the negative current collector (21). The portion where the first negative active material layer (22) is separated from the negative current collector (21) is exposed and comes into contact with the solid electrolyte layer (30), thereby increasing the likelihood of a short circuit. The first negative active material layer (22) is manufactured, for example, by applying a slurry in which the material constituting the first negative active material layer (22) is dispersed onto the negative current collector (21) and drying it. By including a binder in the first cathode active material layer (22), stable dispersion of the cathode active material in the slurry is possible. For example, when the slurry is applied to the cathode current collector (21) by a screen printing method, it is possible to suppress clogging of the screen (e.g., clogging by aggregates of the cathode active material).

[0098] The thickness (d22) of the first negative electrode active material layer is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness (d12) of the positive electrode active material layer. The thickness (d22) of the first negative electrode active material layer is, for example, 1 μm to 20 μm, 2 μm to 10 μm, or 3 μm to 7 μm. If the thickness (d22) of the first negative electrode active material layer is excessively thin, lithium dendrites formed between the first negative electrode active material layer (22) and the negative electrode current collector (21) cause the first negative electrode active material layer (22) to collapse, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1). If the thickness (d22) of the negative electrode active material layer increases excessively, the energy density of the all-solid-state secondary battery (1) decreases and the internal resistance of the all-solid-state secondary battery (1) due to the first negative electrode active material layer (22) increases, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1).

[0099] If the thickness (d22) of the first negative active material layer decreases, for example, the charging capacity of the first negative active material layer (22) also decreases. The charging capacity of the first negative active material layer (22) is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, or 2% or less compared to the charging capacity of the positive active material layer (12). The charging capacity of the first negative active material layer (22) is, for example, 0.1% to 50%, 0.1% to 40%, 0.1% to 30%, 0.1% to 20%, 0.1% to 10%, 0.1% to 5%, or 0.1% to 2% compared to the charging capacity of the positive active material layer (12). If the charge capacity of the first negative electrode active material layer (22) is excessively small, the thickness of the first negative electrode active material layer (22) becomes very thin, and thus, during repeated charge-discharge processes, lithium dendrites formed between the first negative electrode active material layer (22) and the negative electrode current collector (21) cause the first negative electrode active material layer (22) to collapse, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1). If the charge capacity of the first negative electrode active material layer (22) increases excessively, the energy density of the all-solid-state secondary battery (1) decreases, and the internal resistance of the all-solid-state secondary battery (1) caused by the first negative electrode active material layer (22) increases, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1).

[0100] The charge capacity of the positive active material layer (12) is obtained by multiplying the charge capacity density (mAh / g) of the positive active material by the mass of the positive active material in the positive active material layer (12). When multiple types of positive active materials are used, the charge capacity density × mass value is calculated for each positive active material, and the sum of these values ​​is the charge capacity of the positive active material layer (12). The charge capacity of the first negative active material layer (22) is also calculated in the same way. That is, the charge capacity of the first negative active material layer (22) is obtained by multiplying the charge capacity density (mAh / g) of the negative active material by the mass of the negative active material in the first negative active material layer (22). When multiple types of negative active materials are used, the charge capacity density × mass value is calculated for each negative active material, and the sum of these values ​​is the capacity of the first negative active material layer (22). Here, the charge capacity density of the positive active material and the negative active material is a capacity estimated using an all-solid-state half-cell using lithium metal as the counter electrode. The charge capacity of the positive active material layer (12) and the first negative active material layer (22) is directly measured by measuring the charge capacity using an all-solid-state half-cell. By dividing the measured charge capacity by the mass of each active material, the charge capacity density is obtained. Alternatively, the charge capacity of the positive active material layer (12) and the first negative active material layer (22) may be the initial charge capacity measured during the first cycle of charging.

[0101] The negative electrode current collector (21) is composed of a material that does not react with, for example, lithium, that is, does not form any alloys or compounds. The material constituting the negative electrode current collector (21) may be, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not necessarily limited to these; any material used as an electrode current collector in the relevant technical field is acceptable. The negative electrode current collector (21) may be composed of one of the metals described above, or may be composed of an alloy or coating material of two or more metals. The negative electrode current collector (21) is, for example, in the form of a plate or foil.

[0102] The first negative electrode active material layer (22) may further include additives used in conventional all-solid-state secondary batteries (1), such as fillers, dispersants, ion conductors, etc.

[0103] Referring to FIG. 7, the all-solid-state secondary battery (1) further comprises, for example, a thin film (24) containing an element capable of forming an alloy with lithium on a negative electrode current collector (21). The thin film (24) is disposed between the negative electrode current collector (21) and the first negative electrode active material layer (22). The thin film (24) contains, for example, an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium is, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but is not necessarily limited to these, and any element capable of forming an alloy with lithium in the art is possible. The thin film (24) is composed of one of these metals or is composed of an alloy of various types of metals. By placing the thin film (24) on the negative electrode current collector (21), for example, the deposition shape of the second negative electrode active material layer (not shown) deposited between the thin film (24) and the first negative electrode active material layer (22) is further flattened, and the cycle characteristics of the all-solid-state secondary battery (1) can be further improved.

[0104] The thickness (d24) of the thin film is, for example, 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. If the thickness (d24) of the thin film is less than 1 nm, it may be difficult to perform the function of the thin film (24). If the thickness of the thin film is excessively thick, the thin film (24) itself absorbs lithium, and the amount of lithium precipitated in the negative electrode layer decreases, which lowers the energy density of the all-solid-state battery and may degrade the cycle characteristics of the all-solid-state secondary battery (1). The thin film (24) may be placed on the negative electrode current collector (21) by, for example, vacuum deposition, sputtering, plating, etc., but is not necessarily limited to these methods, and any method capable of forming the thin film (24) in the relevant technical field is possible.

[0105] Referring to FIG. 8, the all-solid-state secondary battery (1) further includes a second negative active material layer (23) disposed between, for example, a negative current collector (21) and a solid electrolyte layer (30) by charging. The all-solid-state secondary battery (1) further includes a second negative active material layer (23) disposed between, for example, a negative current collector (21) and a first negative active material layer (22) by charging. Although not shown in the drawing, the all-solid-state secondary battery (1) further includes a second negative active material layer (23) disposed between, for example, a solid electrolyte layer (30) and a first negative active material layer (22) by charging. Although not shown in the drawing, the all-solid-state secondary battery (1) further includes a second negative active material layer (23) disposed inside, for example, a first negative active material layer (22) by charging.

[0106] The second negative electrode active material layer (23) is a metal layer containing lithium or a lithium alloy. The metal layer contains lithium or a lithium alloy. Therefore, since the second negative electrode active material layer (23) is a metal layer containing lithium, it acts as, for example, a lithium reservoir. The lithium alloy is, for example, Li-Al alloy, Li-Sn alloy, Li-In alloy, Li-Ag alloy, Li-Au alloy, Li-Zn alloy, Li-Ge alloy, Li-Si alloy, etc., but is not limited to these; any alloy used as a lithium alloy in the relevant technical field is possible. The second negative electrode active material layer (23) may be composed of one of these alloys or lithium, or may be composed of various types of alloys.

[0107] The thickness (d23) of the second negative electrode active material layer is not particularly limited, but, for example, is 1 μm to 1000 μm, 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 150 μm, 1 μm to 100 μm, or 1 μm to 50 μm. If the thickness (d23) of the second negative electrode active material layer is excessively thin, it is difficult for the second negative electrode active material layer (23) to perform the role of a lithium reservoir. If the thickness (d23) of the second negative electrode active material layer is excessively thick, the mass and volume of the all-solid-state secondary battery (1) increase, and there is a possibility that the cycle characteristics may deteriorate. The second negative electrode active material layer (23) may, for example, be a metal foil having a thickness within this range.

[0108] In the all-solid-state secondary battery (1), the second negative electrode active material layer (23) is disposed between the negative electrode current collector (21) and the first negative electrode active material layer (22) before assembly of the all-solid-state secondary battery (1), for example, or is deposited between the negative electrode current collector (21) and the first negative electrode active material layer (22) by charging after assembly of the all-solid-state secondary battery (1).

[0109] When a second negative electrode active material layer (23) is placed between the negative electrode current collector (21) and the first negative electrode active material layer (22) before assembly of the all-solid-state secondary battery (1), the second negative electrode active material layer (23) acts as a lithium reservoir because it is a metal layer containing lithium. The cycle characteristics of the all-solid-state secondary battery (1) including the second negative electrode active material layer (23) are further improved. For example, a lithium foil is placed between the negative electrode current collector (21) and the first negative electrode active material layer (22) before assembly of the all-solid-state secondary battery (1).

[0110] When the second negative electrode active material layer (23) is formed by charging after assembly of the all-solid-state secondary battery (1), the energy density of the all-solid-state secondary battery (1) increases because the second negative electrode active material layer (23) is not included during assembly of the all-solid-state secondary battery (1). For example, when charging the all-solid-state secondary battery (1), it is charged beyond the charging capacity of the first negative electrode active material layer (22). That is, the first negative electrode active material layer (22) is overcharged. At the beginning of charging, lithium is absorbed in the first negative electrode active material layer (22). That is, the negative electrode active material contained in the first negative electrode active material layer (22) forms an alloy or compound with lithium ions that have moved from the positive electrode layer (10). When charging is performed beyond the capacity of the first negative electrode active material layer (22), lithium is deposited, for example, on the back surface of the first negative electrode active material layer (22), that is, between the negative current collector (21) and the first negative electrode active material layer (22), and a metal layer corresponding to the second negative electrode active material layer (23) is formed by the deposited lithium. The second negative electrode active material layer (23) is a metal layer composed mainly of lithium (i.e., metallic lithium). This result is obtained, for example, by the negative electrode active material included in the first negative electrode active material layer (22) being composed of a material that forms an alloy or compound with lithium. During discharge, the lithium in the first negative electrode active material layer (22) and the second negative electrode active material layer (23), i.e., the metal layer, is ionized and moves toward the positive electrode layer (10). Therefore, it is possible to use lithium as a negative electrode active material in the all-solid-state secondary battery (1). In addition, since the first negative electrode active material layer (22) covers the second negative electrode active material layer (23), it serves as a protective layer for the second negative electrode active material layer (23), i.e., the metal layer, and at the same time, it performs the role of suppressing the precipitation growth of lithium dendrites. Therefore, it suppresses short circuits and capacity degradation of the all-solid-state secondary battery (1), and consequently improves the cycle characteristics of the all-solid-state secondary battery (1).Additionally, when the second negative electrode active material layer (23) is formed by charging after assembly of the all-solid-state secondary battery (1), the negative electrode current collector (21), the first negative electrode active material layer (22), and the region between them are Li-free regions that do not contain lithium (Li) metal or lithium (Li) alloy, for example, in the initial state or after discharge state of the all-solid-state secondary battery.

[0111] Referring to FIG. 12, the all-solid-state secondary battery (1) has a structure in which a second negative electrode active material layer (23) is disposed on a positive electrode current collector (21), and a solid electrolyte layer (30) is directly disposed on the second negative electrode active material layer (23). The second negative electrode active material layer (23) is, for example, a lithium metal layer or a lithium alloy layer.

[0112] Since the solid electrolyte layer (30) includes the aforementioned sulfide-based solid electrolyte, the side reaction between the second negative electrode active material layer (23), which is a lithium metal layer, and the solid electrolyte layer (30) is suppressed, thereby improving the cycle characteristics of the all-solid secondary battery (1).

[0113] (Solid electrolyte layer)

[0114] Referring to FIGS. 6 to 8, the solid electrolyte layer (30) includes a solid electrolyte according to one embodiment disposed between the anode layer (10) and the cathode layer (20).

[0115] In addition to the solid electrolyte according to one embodiment, the solid electrolyte may further include a conventional general sulfide-based solid electrolyte. The solid electrolyte may be, for example, Li2S-P2S5, Li2S-P2S5-LiX, where X is a halogen element, 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, n are positive numbers, Z is one of Ge, Zn, or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, and M is one or more selected from P, Si, Ge, B, Al, Ga, In, and further comprises a sulfide-based solid electrolyte. The sulfide-based solid electrolyte further included in the solid electrolyte is amorphous, crystalline, or a mixture thereof.

[0116] General sulfide-based solid electrolytes further include, for example, argyrodite-type solid electrolytes represented by the following chemical formula 5-1:

[0117] <Chemical Formula 5-1>

[0118] Li + 12-n-x A n+ X 2- 6-x Y - x

[0119] In the above chemical formula 5-1, A is P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta; X is S, Se, or Te; Y is Cl, Br, I, F, CN, OCN, SCN, or N3; 0≤x≤2; and n is the oxidation number A. For example, n is a number from 2 to 5.

[0120] Azirodite-type solid electrolytes are, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I xIt includes one or more selected from (0≤x≤2). The azirodite-type solid electrolyte particularly includes one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0121] The solid electrolyte layer (30) further includes, for example, a binder. The binder included in the solid electrolyte layer (30) is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these and any binder used in the relevant technical field is possible. The binder of the solid electrolyte layer (30) may be of the same type as or different from the binder of the positive electrode active material layer (12) and the negative electrode active material layer (22).

[0122] (Bipolar layer)

[0123] The positive layer (10) includes a positive current collector (11) and a positive active material layer (12).

[0124] The positive current collector (11) is made of, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof, such as a plate or foil. The positive current collector (11) can be omitted.

[0125] The positive active material layer (12) includes, for example, a positive active material and a solid electrolyte. The solid electrolyte included in the positive layer (10) is similar to or different from the solid electrolyte included in the solid electrolyte layer (30). For details regarding the solid electrolyte, refer to the solid electrolyte layer (30). According to one embodiment, the solid electrolyte contains the solid electrolyte according to one embodiment.

[0126] The anode layer contains an anode active material, and the anode active material is a compound capable of reversibly absorbing and desorbing lithium ions, and is, for example, one or more selected from lithium transition metal oxides having a layered crystal structure, lithium transition metal oxides having an olivine crystal structure, and lithium transition metal oxides having a spinel crystal structure. The cathode active material may be, for example, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganese oxide, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but is not necessarily limited to these and any material used as a cathode active material in the relevant technical field is acceptable. Each cathode active material may be a single material or a mixture of two or more materials.

[0127] Lithium transition metal oxides are, for example, Li a A 1-b B b D2(wherein 0.90 ≤ a ≤ 1, and 0 ≤ b ≤ 0.5); Li a E 1-b B b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2-b B b O 4-c D c (In the above equation, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Cob B c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Co b B c O 2-α F α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Co b B c O 2-α F2(wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mn b B c O 2-α F α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c O 2-α F2(wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c G d O2(wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mnd GeO2(wherein the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a CoG b O2(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a MnG b O2(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4(wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f)Fe2(PO4)3(0 ≤ f ≤ 2); a compound represented by any one of the chemical formulas of LiFePO4. In such a compound, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. A compound having a coating layer added to the surface of such a compound may also be used, and a mixture of the compound described above and a compound having a coating layer added may also be used. The coating layer applied to the surface of such a compound comprises, for example, a coating element compound of an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxycarbonate of a coating element. The compound forming this coating layer is amorphous or crystalline. The coating elements included in the coating layer are Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the cathode active material. The coating method is, for example, spray coating or immersion. Since specific coating methods are well understood by those skilled in the art, a detailed explanation will be omitted.

[0128] The positive electrode active material comprises, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen and metal atomic layers are alternately and regularly arranged in a specific direction, thereby forming a two-dimensional plane for each layer. The "cubic rock salt type structure" represents a sodium chloride (NaCl type) structure, which is a type of crystal structure; specifically, it exhibits a structure in which the face-centered cubic lattices (fcc) formed by cations and anions, respectively, are offset from each other by half the ridge of the unit lattice. Lithium transition metal oxides having such a layered rock salt type structure are, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn z It is a ternary lithium transition metal oxide such as O2(NCM) (0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1). When the positive electrode active material includes a ternary lithium transition metal oxide having a layered rock salt structure, the energy density and thermal stability of the all-solid-state secondary battery (1) are further improved.

[0129] As described above, the positive active material may be covered by a coating layer. The coating layer may be any material known as a coating layer for the positive active material of an all-solid-state secondary battery. For example, the coating layer is Li2O-ZrO2.

[0130] When the positive electrode active material contains nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, for example, the capacity density of the all-solid-state secondary battery (1) is increased. In addition, it is possible to reduce the metal leaching of the positive electrode active material in the charged state. As a result, the cycle characteristics of the all-solid-state secondary battery (1) in the charged state are improved.

[0131] The shape of the positive active material is, for example, a particle shape such as a sphere, an elliptical sphere, etc. The particle size of the positive active material is not particularly limited and is within a range applicable to the positive active material of a conventional all-solid-state secondary battery. The content of the positive active material of the positive layer (10) is also not particularly limited and is within a range applicable to the positive layer of a conventional all-solid-state secondary battery.

[0132] The anode layer (10) may further include additives such as a conductive agent, binder, filler, dispersant, and ion conductivity aid in addition to the anode active material and solid electrolyte described above. Such conductive agents include, for example, graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powder, etc. Binders include, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc. Known materials generally used in electrodes of solid secondary batteries are used as coating agents, dispersants, and ion conductivity aids that can be incorporated into the anode layer (10).

[0133] A method for manufacturing a solid electrolyte according to another embodiment may be prepared by mixing a sulfur (S) precursor, a phosphorus (P) precursor, an X precursor, and a nitrogen (N) precursor to provide a precursor mixture, reacting the precursor mixture to obtain a solid electrolyte precursor, and heat-treating at 300°C or higher. X in the X precursor is chlorine (Cl), bromine (Br), fluorine (F), iodine (I), pseudohalogen, or a combination thereof.

[0134] One or more selected from the above sulfur precursor, phosphorus precursor, X precursor, and nitrogen precursor may contain lithium.

[0135] Examples of sulfur precursors include Li2S, and examples of phosphorus precursors include P2S5, red phosphorus, white phosphorus, phosphorus powder, P2O5, (NH4)2HPO4, (NH4)H2PO4, Na2HPO4, Na3PO4, etc.

[0136] Nitrogen precursors such as Li3N and N2S3 can be used.

[0137] X precursor is, for example, a lithium halide. The lithium halide is, for example, LiCl, LiI, or LiBr.

[0138] M precursors may be further added to the precursor mixture. M in the M precursor is sodium (Na), potassium (K), calcium (Ca), iron (Fe), magnesium (Mg), silver (Ag), copper (Cu), zirconium (Zr), zinc (Zn), or a combination thereof.

[0139] The reaction of the above precursor mixture can, for example, produce a solid electrolyte precursor by reacting the mixture and heat-treating it at 300°C or higher to produce a solid electrolyte. The solid electrolyte according to one embodiment contains nitrogen, which can extend the temperature range in which an ion-conducting phase is formed.

[0140] The heat treatment temperature is, for example, in the range of 300°C to 600°C, 300°C to 550°C, or, for example, 350°C to 500°C. If the heat treatment is performed at a temperature below 300°C, it is impossible to obtain a solid electrolyte having an azironite-based crystal structure.

[0141] The method of reacting the mixture is not particularly limited, but for example, mechanical milling (MM). For example, when using mechanical milling, a solid electrolyte precursor is prepared by stirring and reacting starting materials such as Li2S and P2S5 using a ball mill, etc. The stirring speed and stirring time of the mechanical milling method are not particularly limited, but the faster the stirring speed, the faster the rate of formation of the solid electrolyte precursor, and the longer the stirring time, the higher the conversion rate of the raw materials into the solid electrolyte precursor.

[0142] Next, a solid electrolyte precursor obtained by mechanical milling or the like is heat-treated at a predetermined temperature and then ground to produce a solid electrolyte in the form of particles. If the solid electrolyte has glass transition characteristics, it is possible to change from an amorphous state to a crystalline state through heat treatment. The heat treatment temperature is, for example, 400 to 600°C. By having such a heat treatment temperature, a solid electrolyte with a uniform composition is easily obtained.

[0143] The heat treatment time varies depending on the heat treatment temperature, for example, 1 to 100 hours, 10 to 80 hours, 10 to 50 hours, 10 to 30 hours, or 10 to 20 hours. Excellent ionic conductivity and high-temperature stability are simultaneously obtained in solid electrolytes produced within this range of heat treatment times.

[0144] The heat treatment atmosphere is an inert atmosphere or a vacuum atmosphere. The heat treatment atmosphere may be nitrogen, argon, etc., but is not necessarily limited to these; any atmosphere used as an inert atmosphere in the relevant technical field is acceptable.

[0145] The thickness of the solid electrolyte according to one embodiment is 10 to 200 μm. When the thickness of the solid electrolyte is within the above range, the improvement effect on the high rate characteristics and lifespan characteristics of the all-solid-state secondary battery is excellent.

[0146] A method for manufacturing an all-solid-state secondary battery according to another embodiment is to manufacture a solid electrolyte by the method described above, and then, using the manufactured solid electrolyte, manufacture, for example, a positive electrode layer (10), a negative electrode layer (20) and / or a solid electrolyte layer (30), respectively, and then manufacture the battery by stacking these layers.

[0147] The thickness of the solid electrolyte (30) is 10 to 200 μm.

[0148] (Manufacturing of the cathode layer)

[0149] A slurry is prepared by adding materials constituting the first cathode active material layer (22), such as a cathode active material, a conductive material, a binder, and a solid electrolyte, to a polar solvent or a non-polar solvent. The prepared slurry is applied onto a cathode current collector (21) and dried to prepare a first laminate. Subsequently, the dried first laminate is pressed to prepare a cathode layer (20). Pressing may be, for example, a roll press or a flat press, but is not necessarily limited to these methods; any press used in the relevant technical field is possible. The press step may be omitted.

[0150] The above-mentioned cathode layer comprises a cathode current collector and a first cathode active material layer containing a cathode active material disposed on the cathode current collector, wherein the cathode active material comprises one or more selected from carbon-based cathode active materials and metal or metalloid cathode active materials, and the carbon-based cathode active material comprises one or more selected from amorphous carbon and crystalline carbon. The metal or metalloid cathode active material is one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn).

[0151] The invention further comprises a second cathode active material layer disposed between one or more of the above-mentioned cathode current collector and the first cathode active material layer and between the solid electrolyte layer and the first cathode active material layer, wherein the second cathode active material layer is a metal layer comprising lithium or a lithium alloy.

[0152] (Manufacturing of the anode layer)

[0153] A slurry is prepared by adding materials constituting the positive active material layer (12), such as a positive active material, a conductive material, a binder, and a starting material for forming a solid electrolyte, to a non-polar solvent. The prepared slurry is applied onto a positive current collector (11) and dried. The obtained laminate is pressed to produce the positive layer (10). Pressing can be, for example, a roll press, a flat press, or a press using hydrostatic pressure, but is not necessarily limited to these methods; any press used in the relevant technical field is possible. The pressurization process may be omitted. Alternatively, the positive layer (10) is produced by compacting and molding the mixture of materials constituting the positive active material layer (12) into a pellet shape or by stretching (molding) it into a sheet shape. When the positive layer (10) is produced in this way, the positive current collector (11) may be omitted.

[0154] (Preparation of solid electrolyte layer)

[0155] The solid electrolyte layer (30) includes a solid electrolyte according to one embodiment.

[0156] The solid electrolyte layer (30) may further contain a general sulfide-based solid electrolyte used in all-solid secondary batteries in addition to the solid electrolyte described above.

[0157] A general sulfide-based solid electrolyte can be produced, for example, by mixing a starting material for forming a sulfide-based solid electrolyte with a solvent and a binder, applying the mixture, drying, and pressurizing. Alternatively, a solid electrolyte can be produced by depositing the sulfide-based solid electrolyte obtained by the above-described method using known film deposition methods, such as aerosol deposition, cold spray, or sputtering. Alternatively, the solid electrolyte can be produced by pressurizing solid electrolyte particles (simple substance).

[0158] (Manufacturing of all-solid-state secondary batteries)

[0159] A solid-state secondary battery (1) is manufactured by stacking and pressing the positive electrode layer (10), negative electrode layer (20), and solid electrolyte (30) produced by the above-described method, such that the positive electrode layer (10) and the negative electrode layer (20) have the solid electrolyte (30) between them.

[0160] For example, a second laminate is prepared by placing a solid electrolyte layer (20) on an anode layer (10). Subsequently, a third laminate is prepared by placing a cathode (20) on the second laminate so that the solid electrolyte layer (30) and the first cathode active material layer come into contact, and the third laminate is pressed to manufacture an all-solid-state secondary battery (10). Pressurization is performed, for example, at a temperature of room temperature (20°C to 25°C) to 90°C. Alternatively, pressurization is performed at a high temperature of 100°C or higher. The time for which pressurization is applied is, for example, 30 minutes or less, 20 minutes or less, 15 minutes or less, or 10 minutes or less. The time for which pressurization is applied is 1 ms to 30 minutes, 1 ms to 20 minutes, 1 ms to 15 minutes, or 1 ms to 10 minutes. The pressurization method may be, for example, isotactic press, roll press, flat press, etc., but is not necessarily limited to these methods and any pressurization method used in the relevant technical field is possible. The pressure applied during pressurization is, for example, 500 MPa or less, for example, 400 MPa or less, 300 MPa or less, 200 MPa or less, or 100 MPa or less. The pressure applied during pressurization is, for example, 50 MPa to 500 MPa, 50 MPa to 480 MPa, 50 MPa to 450 MPa, 50 MPa to 400 MPa, 50 MPa to 350 MPa, 50 MPa to 300 MPa, 50 MPa to 250 MPa, 50 MPa to 200 MPa, 50 MPa to 150 MPa, or 50 MPa to 100 MPa. By such pressurization, for example, solid electrolyte powder is sintered to form a solid electrolyte.

[0161] The configuration and manufacturing method of the all-solid-state secondary battery described above are examples of embodiments, and the constituent members and manufacturing procedures, etc., can be appropriately modified.

[0162] Hereinafter, a method for manufacturing a solid electrolyte related to an embodiment will be described in detail with reference to examples and comparative examples. Additionally, the examples shown below are provided for illustrative purposes only, and the present invention is not limited to the examples below.

[0163] (Preparation of solid electrolytes)

[0164] Example 1

[0165] A precursor mixture is obtained by mixing Li2S, P2S5, LiCl, and Li3N, and when preparing the precursor mixture, the content of Li2S, P2S5, LiCl, and Li3N is Li 6.125 PS 4.875 N 0.125 After weighing each stoichiometrically controlled sample to obtain Cl, mechanical milling treatment was performed by mixing for 20 hours using a high energy mill (Pulnerisette 7). The mechanical milling treatment was carried out for 20 hours at a rotational speed of 380 rpm, 25°C, and an argon atmosphere.

[0166] 300 mg of the powder material obtained from the above mechanical milling treatment was heat-treated at 500°C for 12 hours in a vacuum atmosphere to obtain a solid electrolyte. The solid electrolyte of Example 1 (Li 6.125 PS 4.875 N 0.125 The nitrogen content in Cl) was 2.0 mol% based on the total content of sulfur and nitrogen.

[0167] Example 2

[0168] The content of Li2S, P2S5, LiCl, and Li3N is Li 6.25 PS 4.75 N 0.25 A solid electrolyte was obtained by following the same method as in Example 1, except that the sample was stoichiometrically modified to obtain Cl and heat-treated at 500°C for 12 hours. The solid electrolyte of Example 3 (Li 6.25 PS4.75 N 0.25 The nitrogen content in Cl) was 5.0 mol% based on the total content of sulfur and nitrogen.

[0169] Example 3

[0170] The content of Li2S, P2S5, LiCl, and Li3N is Li 6.5 PS 4.5 N 0.5 A solid electrolyte was obtained by following the same method as in Example 1, except that the sample was stoichiometrically modified to obtain Cl and heat-treated at 500°C for 12 hours. The solid electrolyte of Example 3 (Li 6.5 PS 4.5 N 0.5 The nitrogen content in Cl) was 5.0 mol% based on the total content of sulfur and nitrogen.

[0171] Example 4

[0172] When preparing the precursor mixture, use more LiBr, and the content of Li2S, P2S5, LiCl, LiBr, and Li3N is Li 6.25 PS 4.75 N 0.25 Cl 0.5 Br 0.5 A solid electrolyte was obtained by carrying out the same method as in Example 1, except that it was stoichiometrically modified to obtain and heat-treated at 450°C for 12 hours.

[0173] Examples 5-1 to 5-5

[0174] A solid electrolyte was prepared by following the same method as in Example 1, except that the contents of Li2S, Na2S, K2S, P2S5, LiCl, LiBr, and Li3N were stoichiometrically varied to obtain a solid electrolyte having the composition of Table 1 below.

[0175] division solid electrolyte Heat treatment temperature and time 5-1 Li6Na 0.125 PS 4.875 N 0.125 Cl 500℃, 12 hours 5-2 Li6Na 0.125 PS 4.875 N 0.125 Cl 0.5 Br 0.5 450℃, 12 hours 5-3 Li 6.1 PS 4.9 N 0.1 Cl 500℃, 12 hours 5-4 Li 6.5 PS 5.5 N 0.5 Cl 500℃, 12 hours 5-5 Li 5.9 K 0.1 Na0 .125 PS 4.875 N 0.125 Cl 500℃, 12 hours

[0176] In the table above, Example 5-5 is a solid electrolyte in which some of the lithium (Li) is replaced with potassium (K) and some of the sulfur (S) is replaced with nitrogen (N).

[0177] Comparative Example 1

[0178] A solid electrolyte was obtained by carrying out the same procedure as in Example 1, except that Li2S, P2S5, and LiCl were used when preparing the precursor mixture, the content of Li2S, P2S5, and LiCl was stoichiometrically controlled to obtain Li6PS5Cl, and heat treatment was performed at 500°C for 12 hours.

[0179] Comparative Example 2

[0180] A solid electrolyte was obtained by carrying out the same procedure as in Example 1, except that the heat treatment was performed at 250°C.

[0181] When carried out according to Comparative Example 2, the desired agilonite-based solid electrolyte could not be obtained.

[0182] Comparative Example 3

[0183] LiN3 (lithium azide), S8, Li2S, and P2S5 were prepared in stoichiometric ratios under an argon gas atmosphere, and these mixtures were placed in graphite salt ampoules and melted under vacuum. Subsequently, the resulting product was heat-treated in a tubular furnace at 550 °C for 6 days. After heat treatment, the mixture was slowly cooled to obtain Li6PS5N3.

[0184] The Li6PS5N3 obtained according to Comparative Example 3 did not achieve a crystal structure in which N3 substitutes sulfur, as in the arginite-based solid electrolyte of Example 1.

[0185] Comparative Example 3A

[0186] A particulate solid electrolyte glass was obtained by carrying out the same procedure as Comparative Example 1, except that a raw material composition consisting of 0.5360 g of amorphous Li2S, 0.8910 g of P2S5, 0.2861 g of LiI, 0.2785 g of LiBr, and 0.0084 g of Li3N (high-purity chemical product) was used as the precursor mixture. The content of Li3N is 1.13 mol% based on the total of Li2S, P2S5, LiI, LiBr, and Li3N (100 mol%).

[0187] delete

[0188] A solid electrolyte glass is heated in an inert gas atmosphere at a temperature above the crystallization temperature for 3 hours to produce an N-containing amorphous A solid sulfide electrolyte was obtained.

[0189] When carried out according to Comparative Example 3A above, an amorphous sulfide-based solid electrolyte was obtained. The ionic conductivity of this amorphous sulfide-based solid electrolyte was approximately 0.3 mS / cm, which is lower than that of Example 1.

[0190] Preparation Example 1

[0191] A cathode active material having an aLi2O-ZrO2 coating film was prepared according to the method disclosed in Korean Patent Publication No. 10-2016-0064942, and the one prepared according to the following method was used.

[0192] An alcoholic solution of aLi2O-ZrO2 (a=1) (coating solution for aLi2O-ZrO2 coating) was prepared by stirring and mixing for 30 minutes in a mixture of lithium methoxide, zirconium propoxide, ethanol, and ethyl acetoacetate. Here, the content of lithium methoxide and zirconium propoxide is the same as that of the cathode active material LiNi 0.8 Co 0.15 Mn 0.05 The content of aLi2O-ZrO2 (a=1) coated on the surface of O2 (NCM) was adjusted to 0.5 mol%.

[0193] Next, the above aLi2O-ZrO2 coating solution is applied to the positive electrode active material LiNi 0.8 Co 0.15 Mn 0.05 O2(NCM) fine powder was mixed, and the mixed solution was heated to about 40°C while stirring to evaporate and dry the solvent, such as alcohol. At this time, ultrasound was applied to the mixed solution.

[0194] By carrying out the above process, it was possible to support an aLi2O-ZrO2 precursor on the particle surface of the anode active material fine powder.

[0195] In addition, a precursor of aLi2O-ZrO2 (a=1) supported on the particle surface of the positive electrode active material was heat-treated at approximately 350°C for 1 hour under an oxygen atmosphere. During this heat treatment process, the precursor of aLi2O-ZrO2 (a=1) present on the upper surface of the positive electrode active material was transformed into aLi2O-ZrO2 (a=1). The content of Li2O-ZrO2 (LZO) is approximately 0.4 parts by weight based on 100 parts by weight of NCM.

[0196] According to the manufacturing process described above, LiNi having an aLi2O-ZrO2 coating film 0.8 Co 0.15 Mn 0.05 O2(NCM) could be obtained. In aLi2O-ZrO2, a is 1.

[0197] (Manufacturing of all-solid-state secondary batteries)

[0198] Example 6

[0199] (Bipolar layer)

[0200] Li2O-ZrO2 (LZO) coated LiNi obtained according to Preparation Example 1 as a cathode active material 0.8 Co 0.15 Mn 0.05 O2(NCM) was prepared.

[0201] As the solid electrolyte, the solid electrolyte powder prepared in Example 1 was prepared. Carbon nanofibers (CNF) were prepared as the conductive agent. These materials were mixed in a weight ratio of positive active material:solid electrolyte:conductive agent = 60:35:5, and the mixture was formed into a large sheet to produce a positive sheet. The prepared positive sheet was pressed onto a positive current collector made of carbon-coated aluminum foil with a thickness of 18 μm to produce a positive layer. The thickness of the positive active material layer was approximately 100 μm.

[0202] (Cathode layer)

[0203] A lithium metal with a thickness of about 30 μm was used as the cathode layer.

[0204] (Solid electrolyte layer)

[0205] A mixture was prepared by adding 1 part by weight of styrene-butadiene rubber (SBR) binder to 100 parts by weight of a crystalline argyrodite-based solid electrolyte (Li6PS5Cl). A slurry was prepared by stirring while adding xylene and diethylbenzene to this mixture. The prepared slurry was applied onto a nonwoven fabric using a blade coater and dried in air at a temperature of 40°C to obtain a laminate. The obtained laminate was vacuum dried at 40°C for 12 hours. A solid electrolyte layer was prepared by the above process.

[0206] A laminate was prepared by placing a solid electrolyte layer on a cathode layer and an anode layer on a solid electrolyte layer. The prepared laminate was subjected to plate pressing at 25°C and a pressure of 100 MPa for 10 minutes. Through this pressing treatment, the solid electrolyte layer was sintered, and the battery characteristics were improved.

[0207] Examples 7 to 10

[0208] An all-solid-state secondary battery was manufactured in the same manner as in Example 6, except that the solid electrolyte prepared in Example 1 in the anode layer was changed to the solid electrolyte prepared in Examples 2 to 5, respectively. Here, Example 5 includes all of Examples 5-1 to 5-5.

[0209] Comparative Examples 4 and 5

[0210] An all-solid-state secondary battery was manufactured in the same manner as in Example 6, except that the solid electrolyte prepared in Example 1 in the anode layer and the solid electrolyte were changed to the solid electrolyte prepared in Comparative Example 1 and Comparative Example 2, respectively.

[0211] Evaluation Example 1: Measurement of ion conductivity

[0212] (1) Examples 1 and 2

[0213] The powder of the solid electrolyte prepared in Examples 1 and 2 was placed in a mold with a diameter of 10 mm and molded into a pellet by applying a pressure of 350 MPa. A thin film of indium (In) was coated on both sides of the pellet to prepare a sample for measuring ionic conductivity. The impedance of the prepared sample was measured using an AUTOLAB PGSTAT30 (Metrohm Autolab Co. Ltd.) potentiostat to plot a Nyquist plot, and the ionic conductivity was measured from this at 25°C, 45°C, or 60°C.

[0214] The measured ionic conductivity is shown in Table 2 below.

[0215] division Ionic conductivity [mS / cm] 25℃ 45℃ 60℃ Example 1 2.21 5.02 8.52 Example 2 1.51 3.44 5.52 Comparative Example 1 2.21 4.81 -

[0216] As shown in Table 2, the solid electrolyte of Example 1 achieved improved ionic conductivity compared to the solid electrolyte of Comparative Example 1 at temperatures of 25°C, 45°C, and 60°C, and the solid electrolyte of Example 2 achieved an ionic conductivity of 1 mS / cm or higher, confirming that it possesses ionic conductivity suitable for solid electrolytes for all-solid-state secondary batteries. In addition, the ionic conductivity of the solid electrolyte of Example 3 was evaluated according to the same method as in Example 1. As a result of the evaluation, the solid electrolyte of Example 3 achieved a level of ionic conductivity similar to that of the solid electrolyte of Example 1.

[0217] (2) Examples 5-1 to 5-5

[0218] The powders of the solid electrolytes prepared according to Examples 5-1 to 5-5 were used to prepare samples for measuring ionic conductivity in the same manner as the solid electrolyte powder of Example 1. The ionic conductivity of the samples is as shown in Table 3 below.

[0219] division Ionic conductivity (mS / cm) 5-1 2.5 5-2 3 5-3 2.19 5-4 1.45 5-5 0.6

[0220] Referring to Table 3, the solid electrolyte of Example 5-1 exhibited a higher level of ionic conductivity compared to the case of Example 1 due to the substitution of Na. Additionally, the solid electrolyte of Example 5-2 showed higher conductivity compared to the solid electrolyte of Example 5-1 due to the substitution of Br in the composition of the solid electrolyte of Example 5-1.

[0221] The solid electrolyte of Example 5-3 exhibited ionic conductivity equivalent to that of Example 1, and the solid electrolyte of Example 5-4 exhibited ionic conductivity of 1.5 mS / cm or less, similar to the solid electrolyte of Example 2. Additionally, the solid electrolyte of Example 5-5 is a case where K is substituted, and it showed lower ionic conductivity compared to the solid electrolyte of Example 5-1. The solid electrolyte of Example 5-5 contains potassium and was obtained because it has lower structural stability and ionic conductivity compared to the solid electrolyte of Example 5-1, which contains lithium.

[0222] Evaluation Example 2: X-ray Diffraction (XRD) Analysis

[0223] XRD spectra were measured for the solid electrolytes prepared in Example 1, Example 2 and Comparative Example 1, and the results are shown in Figure 1. X-ray diffraction analysis was performed using a Bruker D8 Advance, and Cu Kα radiation was used for XRD spectrum measurement.

[0224] Referring to Fig. 1, it was found that the solid electrolytes of Examples 1 and 2 have an azidide crystal structure, similar to that of Comparative Example 1.

[0225] Evaluation Example 3: High Rate Characteristics

[0226] The charge-discharge characteristics of the all-solid-state secondary batteries of Example 6, Example 7, and Comparative Example 4 were evaluated by the following charge-discharge test. The charge-discharge test was performed by placing the all-solid-state secondary batteries in a constant temperature bath at 25°C.

[0227] The battery was charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V, and then discharged at a constant current of 0.05C for 20 hours until the battery voltage reached 2.5V (1st cycle).

[0228] Next, the battery was charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V, and then discharged at a constant current of 0.33C for 3 hours until the battery voltage reached 2.5V (2nd cycle).

[0229] After that, the battery was charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V. Subsequently, the battery was discharged at a constant current of 0.5C for 2 hours until the battery voltage reached 2.5V (3rd cycle).

[0230] After that, the battery was charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V. Subsequently, the battery was discharged at a constant current of 1C for 1 hour until the battery voltage reached 2.5V (4th cycle).

[0231] After that, the battery was charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V. Subsequently, the battery was discharged at a constant current of 0.1C for 10 hours until the battery voltage reached 2.5V (5th cycle).

[0232] After that, the battery was charged at a constant current of 0.33C for 3 hours until the battery voltage reached 4.25V. Subsequently, the battery was discharged at a constant current of 0.33C for 3 hours until the battery voltage reached 2.5V (6th cycle).

[0233] The charge-discharge profiles of the all-solid-state batteries of Examples 6-7 and Comparative Example 4 are shown in FIG. 3.

[0234] As shown in Fig. 3, it was found that the all-solid-state secondary batteries of Examples 6 and 7 had improved high-rate characteristics, unlike the all-solid-state secondary battery of Comparative Example 4.

[0235] Evaluation Example 4: Cycle Characteristics

[0236] The charge-discharge characteristics of the all-solid-state secondary batteries of Examples 6 and 7 using the solid electrolytes of Examples 1 and 2, and the all-solid-state secondary battery of Comparative Example 4 using the solid electrolyte of Comparative Example 1, were evaluated by the following charge-discharge test.

[0237] The cycle characteristics were performed by placing the above-mentioned all-solid-state secondary battery in a constant temperature bath at 25°C.

[0238] The battery was charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V, and then discharged at a constant current of 0.05C for 20 hours until the battery voltage reached 2.5V (1st cycle). Subsequently, the battery was charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V, and then discharged at a constant current of 0.33C for 3 hours until the battery voltage reached 2.5V (2nd cycle). After that, the battery was charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V. Subsequently, the battery was discharged at a constant current of 0.5C for 2 hours until the battery voltage reached 2.5V (3rd cycle). After that, the battery was charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V. Next, the battery was discharged at a constant current of 1C for 1 hour until the battery voltage reached 2.5V (4th cycle). After that, the battery was charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V. Subsequently, the battery was discharged at a constant current of 0.1C for 10 hours until the battery voltage reached 2.5V (5th cycle).

[0239] After that, the battery was charged at a constant current of 0.33C for 3 hours until the battery voltage reached 4.25V, and then discharged at a constant current of 0.33C for 3 hours until the battery voltage reached 2.5V.

[0240] The above cycle was repeated a total of 100 times to evaluate the change in capacity and the capacity retention rate according to the number of cycles, respectively, and are described in FIGS. 4 and 5. The capacity retention rate was calculated according to Equation 1 below.

[0241] <Equation 1>

[0242] Capacity Retention Rate (%) = (Discharge Capacity of Each Cycle / Discharge Capacity of the First Cycle) x 100

[0243] It was found that the all-solid-state secondary batteries of Examples 6 and 7 not only had excellent discharge capacity characteristics compared to the all-solid-state secondary battery of Comparative Example 4, as shown in FIG. 4, but also had significantly improved capacity retention rate, as shown in FIG. 5.

[0244] Although an exemplary embodiment has been described above, it is not limited thereto. It is possible to implement the invention with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the invention. Explanation of the symbols

[0245] 1: Solid-state secondary battery 10: Positive electrode layer 11: Positive current collector 12: Positive active material layer 20: Cathode layer 21: Cathode current collector 22: Cathode active material layer 30: Solid electrolyte

Claims

Claim 1 Solid electrolyte comprising a compound represented by the following chemical formula 1 and having an argyrodite crystal structure: <Chemical Formula 1> (Li 1-a M a ) 7-d+x PS 6-d-x+k (N) x (X) d In Chemical Formula 1, M is sodium (Na), potassium (K), calcium (Ca), iron (Fe), magnesium (Mg), silver (Ag), copper (Cu), zirconium (Zr), zinc (Zn), or a combination thereof, and X is one or more selected from i) chlorine (Cl); and ii) bromine (Br), fluorine (F), and iodine (I), and 0 <x<1, 0≤a<1, 0<d≤1.8, 0≤k<1이다. Claim 2 In claim 1, a solid electrolyte in which the compound is a compound represented by the following chemical formula 1-1: <Chemical Formula 1-1> (Li 1-a M a ) 7-d+x PS 6-d-x (N) x (X) d In Chemical Formula 1-1, M is sodium (Na), potassium (K), calcium (Ca), iron (Fe), magnesium (Mg), silver (Ag), copper (Cu), zirconium (Zr), zinc (Zn), or a combination thereof, and X is one or more selected from i) chlorine (Cl); and ii) bromine (Br), fluorine (F), and iodine (I), and 0 <x<1, 0≤a<1, 0<d≤1.8이다. Claim 3 In claim 1, 0 in the above chemical formula 1 <x≤0.5인 고체 전해질. Claim 4 In claim 1, 0 in the above chemical formula 1 <d≤1인 고체 전해질. Claim 5 delete Claim 6 In claim 1, (X) in the above chemical formula 1 d is (Br 1-x1 (Cl) x1 ) d and 0 <x1<1, 0<d≤1인 고체 전해질. Claim 7 In claim 1, the solid electrolyte wherein the compound is a compound represented by the following chemical formula 2: <Chemical Formula 2>Li 7-d+x PS 6-d-x (N) x (X) d In Chemical Formula 2, X is one or more selected from i) chlorine (Cl); and ii) bromine (Br), fluorine (F), and iodine (I), and 0 <x<1, 0<d≤1이다. Claim 8 In claim 1, the solid electrolyte wherein the compound is a compound represented by the following chemical formula 3: <Chemical Formula 3> (Li 1-a Na a ) 7-d+x PS 6-d-x (N) x (X) d In Chemical Formula 3, X is one or more selected from i) chlorine (Cl); and ii) bromine (Br), fluorine (F), and iodine (I), and 0 <x<1, 0<a<1, 0<d≤1이다. Claim 9 In claim 1, the solid electrolyte wherein the compound is a compound represented by the following chemical formula 4: <Chemical Formula 4> (Li 1-a K a ) 7-d+x PS 6-d-x (N) x (X) d In Chemical Formula 4, X is one or more selected from i) chlorine (Cl); and ii) bromine (Br), fluorine (F), and iodine (I), and 0 <x<1, 0<d≤1, 0<a<1이다. Claim 10 In claim 1, the solid electrolyte wherein the compound is a compound represented by the following chemical formula 5: <Chemical Formula 5>Li 7-d+x PS 6-d-x (N) x (Br 1-x1 (Cl) x1 ) d Of chemical formula 5, 0 <x<1, 0<d≤1, 0<x1<1이다. Claim 11 In claim 1, the compound represented by the above chemical formula 1 is Li 6.125 PS 4.875 N 0.125 Cl 0.5 Br 0.5 , Li 6.25 PS 4.75 N 0.25 Cl 0.5 Br 0.5 , Li6Na 0.125 PS 4.875 N 0.125 Cl 0.5 Br 0.5 , Li6Na 0.25 PS 4.75 N 0.25 Cl 0.5 Br 0.5 , Li6K 0.125 PS 4.875 N 0.125 Cl 0.5 Br 0.5 , Li6K 0.25 PS 4.75 N 0.25 Cl 0.5 Br 0.5 , Li 6.125 PS 4.875 N 0.125 Cl 0.16 Br 0.84 , Li 6.25 PS 4.75 N 0.25 Cl 0.16 Br 0.84 , Li6Na 0.125 PS 4.875 N 0.125 Cl 0.16 Br 0.84 , Li6Na 0.25 PS 4.75 N 0.25 Cl 0.16 Br 0.84 , Li6K 0.125 PS 4.875 N 0.125 Cl 0.16 Br 0.84 , Li6K 0.25 PS 4.75 N 0.25 Cl 0.16 Br 0.84 , or a combination thereof, a solid electrolyte. Claim 12 In claim 1, the solid electrolyte has an ionic conductivity of 1 mS / cm or more at room temperature (25℃). Claim 13 In claim 1, the solid electrolyte has a thickness of 10 to 200 μm. Claim 14 An electrochemical cell comprising an anode layer; a cathode layer; and a solid electrolyte layer disposed between the anode layer and the cathode layer, wherein one or more selected from the solid electrolyte layer and the anode layer comprises a solid electrolyte according to any one of claims 1 to 4 and 6 to 13. Claim 15 In claim 14, the anode layer contains a compound represented by the following chemical formula 1, and the electrochemical cell comprises a solid electrolyte having an azirodite crystal structure: <Chemical Formula 1> (Li 1-a M a ) 7-d+x PS 6-d-x (N) x (X) d In Chemical Formula 1, M is sodium (Na), potassium (K), iron (Fe), magnesium (Mg), silver (Ag), copper (Cu), zirconium (Zr), zinc (Zn), or a combination thereof, X is chlorine (Cl), bromine (Br), fluorine (F), iodine (I), pseudohalogen, or a combination thereof, and 0 <x<1, 0≤a<1, 0<d≤1.8이다. Claim 16 In claim 14, the anode layer comprises an electrochemical cell comprising an anode active material, a solid electrolyte, and a conductive agent. Claim 17 An electrochemical cell according to claim 16, wherein the content of the solid electrolyte in the anode layer is 2 to 70 parts by weight based on 100 parts by weight of the anode active material. Claim 18 In claim 14, the electrochemical cell is an electrochemical cell that is charged at 4V or higher in a constant temperature bath at 25℃ and discharged at 2.5V, and has a capacity retention rate of 85% or higher after 100 cycles. Claim 19 An electrochemical cell according to claim 14, wherein the negative electrode layer comprises a negative electrode current collector and a first negative electrode active material layer comprising a negative electrode active material disposed on the negative electrode current collector, and wherein the negative electrode active material comprises one or more selected from a carbon-based negative electrode active material and a metal or metal-metal negative electrode active material. Claim 20 In claim 19, the carbon-based negative electrode active material comprises one or more selected from amorphous carbon and crystalline carbon, forming an electrochemical cell. Claim 21 An electrochemical cell according to claim 19, wherein the metal or metalloid negative electrode active material comprises one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Claim 22 An electrochemical battery according to claim 19, further comprising a second negative active material layer disposed between the negative current collector and the first negative active material layer and between the solid electrolyte layer and the first negative active material layer, wherein the second negative active material layer is a metal layer comprising lithium or a lithium alloy. Claim 23 An electrochemical cell according to claim 14, wherein the positive electrode layer comprises a positive electrode active material, and the positive electrode active material is one or more selected from a lithium transition metal oxide having a layered crystal structure, a lithium transition metal oxide having an olivine crystal structure, and a lithium transition metal oxide having a spinel crystal structure. Claim 24 In paragraph 14, the above electrochemical cell is an electrochemical cell that is an all-solid-state secondary battery. Claim 25 A method for manufacturing a solid electrolyte according to any one of claims 1 to 4 and 6 to 13, comprising the steps of: mixing a sulfur (S) precursor, a phosphorus (P) precursor, an X precursor, and a nitrogen (N) precursor to provide a precursor mixture; and reacting the mixture to obtain a solid electrolyte precursor and heat-treating at 300°C or higher, wherein X of the X precursor is one or more selected from i) chlorine (Cl); and ii) bromine (Br), fluorine (F), and iodine (I). Claim 26 A method for manufacturing a solid electrolyte according to claim 25, wherein an M precursor is further added to the above precursor mixture, and M of the M precursor is sodium (Na), potassium (K), calcium (Ca), iron (Fe), magnesium (Mg), silver (Ag), copper (Cu), zirconium (Zr), zinc (Zn), or a combination thereof. Claim 27 A method for manufacturing a solid electrolyte according to claim 25, wherein the heat treatment is carried out at 300°C to 600°C.

Images