Solid electrolyte for lithium secondary battery and lithium secondary battery

Abstract

Disclosed are a solid electrolyte for lithium secondary batteries and a lithium secondary battery, wherein the solid electrolyte comprises Li a A1 b1 A2 b2 A3 b3 Y c X d The compounds are represented by Li. Li is lithium. A1, A2, and A3 are distinct from each other and each of A1, A2, and A3 includes antimony (Sb), tin (Sn), germanium (Ge), silicon (Si), or phosphorus (P). Y includes oxygen (O), sulfur (S), selenium (Se), or tellurium (Te). X includes chlorine (Cl), bromine (Br), iodine (I), and X1. e X2 1‑e X1 and X2 are distinct from each other, and X1 and X2 each include Cl, Br, or I. Furthermore, a satisfies 5 ≤ ​​a ≤ 8, b1, b2, and b3 each satisfy 0 ≤ b1 ≤ 1, 0 ≤ b2 ≤ 1, 0 ≤ b3 ≤ 1, and b1 + b2 + b3 = 1, c satisfies 4 ≤ c ≤ 6, d satisfies 0 ≤ d ≤ 2, and e satisfies 0

Description

Technical Field

[0001] This disclosure relates to a solid electrolyte for use in lithium secondary batteries and lithium secondary batteries. Background Technology

[0002] Currently, lithium-ion batteries are used in small electronic devices such as mobile phones and tablets, as well as in large transportation vehicles such as electric vehicles. Therefore, the demand for stability is increasing, and there is in-depth research into solid electrolytes to replace the liquid electrolytes in existing lithium-ion batteries.

[0003] Currently, commercially available lithium-ion batteries pose safety concerns due to their flammable organic liquid electrolytes. Therefore, it is believed that using non-flammable solid electrolytes can prevent the root cause of these safety issues. Furthermore, solid electrolytes offer high packaging efficiency, which can reduce the size and weight of lithium-ion batteries.

[0004] The synthesis and research of solid electrolytes with different crystal structures and compositions require significant time and effort. Therefore, numerous attempts have been made to calculate and predict the performance of solid electrolytes, such as lithium-ion conductivity. However, all these attempts have focused on developing solid electrolytes with high lithium-ion conductivity. Even if a solid electrolyte with high lithium-ion conductivity is developed, the battery may still fail to function properly when applied to a practical battery due to micro-short circuits within the electrodes.

[0005] The description in the background section provides only background information relevant to this disclosure and may not constitute prior art. Summary of the Invention

[0006] Each aspect will provide a solid electrolyte for lithium secondary batteries that exhibits excellent stability and high lithium-ion conductivity when applied to actual batteries.

[0007] The various aspects are not limited to the foregoing. These aspects should be clearly understood through the following description and implemented by the apparatus described in this invention.

[0008] Various aspects provide a solid electrolyte comprising a compound represented by the following chemical formula 1:

[0009] [Chemical Formula 1]

[0010] Li a A1 b1 A2 b2 A3 b3 Y c X d

[0011] Wherein: Li is lithium; A1, A2, and A3 are different from each other and each may include antimony (Sb), tin (Sn), germanium (Ge), silicon (Si), or phosphorus (P); Y may include oxygen (O), sulfur (S), selenium (Se), or tellurium (Te); X may include chlorine (Cl), bromine (Br), iodine (I), or X1 e X2 1-e X1 and X2 are distinct from each other and may each include Cl, Br, or I; a satisfies 5 ≤ ​​a ≤ 8; b1, b2, and b3 each satisfy 0 ≤ b1 ≤ 1, 0 ≤ b2 ≤ 1, 0 ≤ b3 ≤ 1, and b1 + b2 + b3 = 1; c satisfies 4 ≤ c ≤ 6; d satisfies 0 ≤ d ≤ 2; and e satisfies 0 <e<1。

[0012] The compound can be a compound in which b3 is 0, A1 and A2 are different from each other, and A1 and A2 each include Sb, Sn or Ge.

[0013] Solid electrolytes may include compounds represented by the following chemical formula 2-1:

[0014] [Chemical Formula 2-1]

[0015] Li 6.4 Sb 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8 .

[0016] Solid electrolytes may include compounds represented by the following chemical formula 2-2:

[0017] [Chemical Formula 2-2]

[0018] Li 6.4 Ge 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8 .

[0019] Solid electrolytes may include compounds represented by the following chemical formulas 2-3:

[0020] [Chemical Formula 2-3]

[0021] Li 6.4 Sb 0.25 Ge 0.75 S 4.4 Cl 0.8 Br 0.8 .

[0022] The compound can be a compound in which b3 is 0, A1 and A2 are different from each other, and A1 and A2 each include Si or Ge.

[0023] Solid electrolytes may include compounds represented by the following chemical formula 3-1:

[0024] [Chemical Formula 3-1]

[0025] Li 6.4 SiS 4.4 Cl 0.8 Br 0.8 .

[0026] Solid electrolytes may include compounds represented by the following chemical formula 3-2:

[0027] [Chemical Formula 3-2]

[0028] Li 6.4 SiSe 4.4 Cl 0.8 Br 0.8 .

[0029] Solid electrolytes may include compounds represented by the following chemical formula 3-3:

[0030] [Chemical Formula 3-3]

[0031] Li 6.4 Si 0.75 Ge 0.25 S 4.4 Cl 0.8 Br 0.8 .

[0032] Solid electrolytes may include compounds represented by the following chemical formula 4:

[0033] [Chemical Formula 4]

[0034] Li8SiS6.

[0035] The compound can be one in which A1, A2, and A3 are different from each other and each of A1, A2, and A3 includes Sb, Ge, or P.

[0036] Solid electrolytes may include compounds represented by the following chemical formula 5-1:

[0037] [Chemical Formula 5-1]

[0038] Li5SbS4Br2.

[0039] Solid electrolytes may include compounds represented by the following chemical formula 5-2:

[0040] [Chemical Formula 5-2]

[0041] Li 5.9 Ge 0.5 P 0.25 Sb0.25 S 4.4 Cl 0.8 Br 0.8 .

[0042] Solid electrolytes may include compounds represented by the following chemical formula 5-3:

[0043] [Chemical Formula 5-3]

[0044] Li 6.4 GeS 4.4 Cl 0.8 Br 0.8 .

[0045] Various aspects provide a lithium secondary battery including a solid electrolyte. The solid electrolyte comprises a compound represented by the following chemical formula 1:

[0046] [Chemical Formula 1]

[0047] Li a A1 b1 A2 b2 A3 b3 Y c X d ,

[0048] Wherein: Li is lithium; A1, A2, and A3 are different from each other and each may include antimony (Sb), tin (Sn), germanium (Ge), silicon (Si), or phosphorus (P); Y may include oxygen (O), sulfur (S), selenium (Se), or tellurium (Te); X may include chlorine (Cl), bromine (Br), iodine (I), or X1 e X2 1-e X1 and X2 are distinct from each other and may each include Cl, Br, or I; a satisfies 5 ≤ ​​a ≤ 8; b1, b2, and b3 each satisfy 0 ≤ b1 ≤ 1, 0 ≤ b2 ≤ 1, 0 ≤ b3 ≤ 1, and b1 + b2 + b3 = 1; c satisfies 4 ≤ c ≤ 6; d satisfies 0 ≤ d ≤ 2; and e satisfies 0 <e<1。

[0049] The compound can be a compound in which b3 is 0, A1 and A2 are different from each other, and A1 and A2 each include Sb, Sn or Ge.

[0050] Solid electrolytes may include compounds represented by the following chemical formula 2-1:

[0051] [Chemical Formula 2-1]

[0052] Li 6.4 Sb 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8 .

[0053] Solid electrolytes may include compounds represented by the following chemical formula 2-2:

[0054] [Chemical Formula 2-2]

[0055] Li 6.4 Ge 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8

[0056] Solid electrolytes may include compounds represented by the following chemical formulas 2-3:

[0057] [Chemical Formula 2-3]

[0058] Li 6.4 Sb 0.25 Ge 0.75 S 4.4 Cl 0.8 Br 0.8

[0059] The compound can be a compound in which b3 is 0, A1 and A2 are different from each other, and A1 and A2 each include Si or Ge. Detailed Implementation

[0060] The above and other objects, features, and advantages of this disclosure will become clearer from the following embodiments. However, this disclosure is not limited to the embodiments disclosed herein and may be modified in different forms. These embodiments are provided to fully explain this disclosure and to fully convey the spirit of this disclosure to those skilled in the art.

[0061] It should be understood that when the terms "comprising," "including," "having," etc., are used in this specification, they indicate the presence of the stated feature, integral, step, operation, element, component, or combination thereof, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, or combinations thereof. Furthermore, it should be understood that when an element such as a layer, film, region, or sheet is referred to as being "on" another element, it may be directly on the other element, or there may be intermediate elements therein. Similarly, when an element such as a layer, film, region, or sheet is referred to as being "under" another element, it may be directly under the other element, or there may be intermediate elements therein.

[0062] Unless otherwise specified, all numerical values, specifications, and / or representations used herein to indicate the amounts of components, reaction conditions, polymer compositions, and mixtures should be considered approximate, including various uncertainties affecting the measurement, which inherently occur in obtaining these values, and therefore should in all cases be understood to be modified by the term "about". Furthermore, when numerical ranges are disclosed in this specification, the range is continuous and includes all values ​​from the minimum to the maximum of the range, unless otherwise specified. Additionally, when such ranges involve integer values, all integers from the minimum to the maximum are included, unless otherwise specified.

[0063] In this document, the excellent moisture stability of solid electrolytes can mean that when exposed to moisture in the air (hydrogen monoxide, H2O), the solid electrolyte can maintain its performance and physicochemical properties without undergoing chemical reactions or structural changes. Solid electrolytes according to embodiments of this disclosure do not react with moisture to produce hydrogen sulfide (H2S) and are able to maintain properties such as strength, ductility, and lithium-ion conductivity.

[0064] In this document, the excellent interfacial stability of a solid electrolyte can mean that when in contact with positive and / or negative electrode active materials, the solid electrolyte maintains structural stability without inducing a chemical reaction at the interface between the two components. The solid electrolyte according to embodiments of this disclosure does not react with the positive and / or negative electrode active materials, and therefore does not decompose or deform, and is able to form a stable interface with the positive and / or negative electrode active materials, thereby reducing the interfacial resistance within the electrode.

[0065] In this document, the excellent voltage stability of a solid electrolyte can mean that the solid electrolyte can maintain high physicochemical stability over a specific voltage range. Solid electrolytes according to embodiments of this disclosure can remain stable over low and / or high voltage ranges without undergoing chemical decomposition or structural changes.

[0066] The solid electrolyte according to embodiments of this disclosure may include sulfide-based solid electrolytes and may include compounds represented by the following chemical formula 1:

[0067] [Chemical Formula 1]

[0068] Li a A1 b1 A2 b2 A3 b3 Y c X d .

[0069] In chemical formula 1, Li is lithium, and A1, A2 and A3 are different from each other and may each include antimony (Sb), tin (Sn), germanium (Ge), silicon (Si) or phosphorus (P).

[0070] Y can include oxygen (O), sulfur (S), selenium (Se), or tellurium (Te).

[0071] X may include chlorine (Cl), bromine (Br), iodine (I), or X1. e X2 1-e X1 and X2 are different from each other and may each include Cl, Br or I.

[0072] In chemical formula 1, a, b1, b2, b3, c, d, and e can satisfy 5 ≤ a ≤ 8, 0 ≤ b1 ≤ 1, 0 ≤ b2 ≤ 1, 0 ≤ b3 ≤ 1, b1 + b2 + b3 = 1, 4 ≤ c ≤ 6, 0 ≤ d ≤ 2, and 0 <e<1。

[0073] Solid electrolytes include those in which b3 is 0, A1 and A2 are distinct from each other, and A1 and A2 each comprise Sb, Sn, or Ge. Solid electrolytes include compounds represented by the following chemical formula 2-1, compounds represented by the following chemical formula 2-2, or compounds represented by the following chemical formula 2-3:

[0074] [Chemical Formula 2-1]

[0075] Li 6.4 Sb 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8 ;

[0076] [Chemical Formula 2-2]

[0077] Li 6.4 Ge 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8 ;or

[0078] [Chemical Formula 2-3]

[0079] Li 6.4 Sb 0.25 Ge 0.75 S 4.4 Cl 0.8 Br 0.8 .

[0080] The compounds represented by chemical formula 2-1 or chemical formula 2-2 have excellent moisture stability and prevent the generation of hydrogen sulfide gas when in contact with moisture in the air.

[0081] The moisture stability can be evaluated by calculating the hydrogen sulfide gas generation reaction energy of each compound using density functional theory (DFT) during computer simulation. The process is as follows.

[0082] The pseudo-binary reaction equation of the product composition (C) generated by the reaction between the solid electrolyte (SE) to be calculated and moisture (H2O) is designed as the following equation (1):

[0083] C 产物 (SE, H2O, x) = x·C(SE) + (1 - x)C(H2O) - (1)

[0084] The reaction energy of this equation is calculated as in the following equation (2):

[0085] E 反应 (SE, H2O, x) = E eq (C 产物 (SE, H2O, x)) - E(C 产物 (SE, H2O, x)) - (2)

[0086] where eq represents the phase equilibrium state of the product of reaction equation (1).

[0087] By applying this equation to the range 0 < x < 1, calculate E 反应 of x, and then determine the reaction at the x with the lowest reaction energy as the reaction equation of the solid electrolyte and moisture (H2O).

[0088] To compare the reaction energies between various solid electrolytes, the reaction equation is normalized to H2S.

[0089] The final hydrogen sulfide gas formation energy can be obtained by multiplying the reaction energy by a conversion factor that takes into account the conversion rate of sulfur contained in the solid electrolyte as a reactant to the formation of hydrogen sulfide gas.

[0090] An example of obtaining the hydrogen sulfide gas formation energy of Li6PS5Cl in this way is as follows.

[0091] - Obtain the pseudo-binary reaction equation using Li6PS5Cl and H2O:

[0092] C 产物 (Li6PS5Cl, H2O, x) = x·Li6PS5Cl + (1 - x)·H2O

[0093] - When x = 0.2, obtain the lowest reaction energy:

[0094] E 反应(Li6PS5Cl,H2O,0.2)

[0095] =E eq (0.2Li3PO4+0.4LiHS+0.6H2S+0.2LiCl)-(0.2E(Li6PS5Cl)+0.8E(H2O))

[0096] =-10.60eV / atom

[0097] - H2S equivalent normalized to 0.6

[0098] E 反应 =-10.60 / 0.6=-17.67eV / atom

[0099] - The conversion factor = 0.6 / 0.2 x 5 = 0.6, which reflects the formation of 0.6H2S from S contained in 0.2Li6PS5Cl.

[0100] E 形成 = -17.67 eV / atom × 0.6 = -10.6 eV / atom

[0101] Hydrogen sulfide gas formation energy (H2SE) of solid electrolytes according to embodiments of this disclosure 形成 The results are shown in Table 1 below.

[0102] Table 1

[0103] Classification Components <![CDATA[H2S E 形成 [eV]]> Example <![CDATA[Li 6.4 Sb 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8 ]]> 0.598 Example <![CDATA[Li 6.4 Ge 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8 ]]> 0.585 Comparative example <![CDATA[Li 6.5 If 0.5 P 0.5 S5Cl]]> -0.243 Comparative example <![CDATA[Li6PS5Cl]]> -0.440

[0104] Referring to Table 1, as shown in the following reaction equations, phosphorus (P) and silicon (Si) readily form Li3PO4 and Li2SiO3, and hydrogen sulfide is produced from the hydrogen (H) remaining in the process:

[0105] 1.33H₂O + 0.33Li₆PS₅Cl → 0.33LiCl + 0.33Li₃PO₄ + H₂S + 0.66LiHS; and

[0106] H2O+0.33Li7SiS5Cl→0.33LiCl+0.33Li2SiO3+H2S+0.67Li2S

[0107] Conversely, as shown in the following reaction formula, the antimony (Sb) in the example forms Li3SbS3, and due to the reaction of sulfur (S) with antimony (Sb), the formation of hydrogen sulfide is difficult to occur:

[0108] H2O+Li6SbS5Cl→LiCl+0.25Li2SO4+Li3SbS3+H2S+0.75Li2S.

[0109] Furthermore, as shown in the following reaction formula, germanium (Ge) and tin (Sn) in the embodiment competitively form Li4GeO4 and Li2SnO3, making it difficult for hydrogen sulfide formation reaction to occur:

[0110] H2O + 0.29Li7Sn 0.5 Ge 0.5 S5Cl→0.29LiCl+0.14Li2SnO3+0.14Li4GeO4+H2S+0.43Li2S.

[0111] Furthermore, compounds represented by chemical formula 2-2 or chemical formula 2-3 exhibit excellent positive electrode interface stability. Therefore, when in contact with positive electrode active materials such as NCM 811, these compounds do not react with the positive electrode active materials to form an intermediate phase and can maintain physicochemical stability.

[0112] The stability of the cathode interface can be evaluated by calculating the interfacial reaction energy. The process is as follows:

[0113] C 界面 (C SE C 电极 ,x)→xC SE +(1-x)C 电极 (Expression 1)

[0114] (C 界面 (C SE C 电极 ,x): Interface components, C SE : Composition of the solid electrolyte in contact, C 电极 : Composition of active materials in contact, 0 <x<1)

[0115] The formula in Expression 1 is modified to the following equation for calculating interfacial energy:

[0116] E 界面 (SE, electrode, x) = xE(SE) + (1-x)E(electrode) (Expression 2).

[0117] The decomposition energy (ΔE) between the two components can be used to determine the composition of the components. D To assess the stability between solid electrolytes and active materials.

[0118] ΔE D (SE, electrode, x) = E eq (C 界面 (C SE C 电极 ,x))-E 界面 (SE, electrode, x)(expression 3)(E) eq Interfacial energy at equilibrium, E 界面: Interface composition energy to be obtained

[0119] The reaction energy considering the equivalence number (0-1) between the solid electrolyte and the active material under equilibrium conditions can be defined as follows: ΔE D,相互 (SE, electrode, x):

[0120] ΔE D,相互 (SE, electrode, x) = ΔE D (SE, electrode, x) - xΔE D (SE)-(1-x)ΔE D (Electrode)(Expression 4)

[0121] (ΔE D (SE): Decomposition energy of solid electrolyte, ΔE D (Electrode): Decomposition energy of active material).

[0122] When x = x m The energy at which the time energy is minimized is as follows:

[0123] ΔE D,相互 (SE, electrode, x) = ΔE D,相互 (SE, electrode, x) m (Expression 5).

[0124] Use the ΔE obtained therefrom D,相互 (SE, electrode, x) can be used to calculate the interfacial reaction energy between the solid electrolyte and the positive electrode active material. The decomposition energy and equilibrium energy of each component can be obtained using the Materials Project database, thereby allowing for the calculation and evaluation of the positive electrode interfacial stability of each component.

[0125] The interfacial reaction energy (E) of a solid electrolyte for a positive electrode active material according to embodiments of this disclosure int The results are shown in Table 2 below.

[0126] Table 2

[0127] Classification Components <![CDATA[E int [eV]]> Example <![CDATA[Li 6.4 Ge 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8 ]]> -0.339 Example <![CDATA[Li 6.4 Sb 0.25 Ge 0.75 S 4.4 Cl 0.8 Br 0.8 ]]> -0.340 Comparative example <![CDATA[Li 5.9 Si 0.5 P 0.5 S 4.4 Cl 0.8 Br 0.8 ]]> -0.418 Comparative example <![CDATA[Li6PS5Cl]]> -0.424

[0128] Referring to Table 2, it was found that compounds containing silicon (Si) and phosphorus (P) have poor cathode interface stability.

[0129] Solid electrolytes may include those in which b3 is O, A1 and A2 are different from each other, and A1 and A2 each comprise Si or Ge. Solid electrolytes include compounds represented by the following chemical formula 3-1, compounds represented by the following chemical formula 3-2, compounds represented by the following chemical formula 3-3, or compounds represented by the following chemical formula 4:

[0130] [Chemical Formula 3-1]

[0131] Li 6.4 SiS 4.4 Cl 0.8 Br 0.8 ;

[0132] [Chemical Formula 3-2]

[0133] Li 6.4 SiSe 4.4 Cl 0.8 Br 0.8 ;

[0134] [Chemical Formula 3-3]

[0135] Li 6.4 Si 0.75 Ge 0.25 S 4.4 Cl 0.8 Br 0.8 ;or

[0136] [Chemical Formula 4]

[0137] Li8SiS6.

[0138] Compounds represented by chemical formula 3-1, chemical formula 3-2, or chemical formula 3-3 exhibit excellent stability in a low voltage range.

[0139] The voltage stability of solid electrolytes can be evaluated using the electrochemical window (ECW). The electrochemical window (ECW) is the range within which a solid electrolyte remains stable without decomposition even when the voltage changes, and is obtained by subtracting the reduction potential from the oxidation potential. Since the solid electrolyte is in contact with the electrode, a wide electrochemical window (ECW) can be advantageous for stable battery operation. The procedure for determining the electrochemical window (ECW) is as follows.

[0140] To perform electrochemical window (ECW) calculations using pymatgen and the Material API, the chemical potential of lithium (Li) is first defined using the Materials Project database. By generating a phase diagram of the materials decomposed from the desired component containing lithium (Li), the decomposed material can be understood based on the voltage range of the desired material. In this way, the electrochemical window (ECW) can be calculated.

[0141] The evaluation results of the low voltage stability (low V) of the solid electrolyte according to the embodiments of this disclosure are shown in Table 3 below.

[0142] Table 3

[0143] Classification Components Low V [eV] Example <![CDATA[Li 6.4 SiS 4.4 Cl 0.8 Br 0.8 ]]> 1.497 Example <![CDATA[Li 6.4 SiSe 4.4 Cl 0.8 Br 0.8 ]]> 1.552 Example <![CDATA[Li 6.4 Si 0.75 Ge 0.25 S 4.4 Cl 0.8 Br 0.8 ]]> 1.620 Comparative example <![CDATA[Li 5.9 Si 0.5 P 0.5 S 4.4 Cl 0.8 Br 0.8 ]]> 1.689 Comparative example <![CDATA[Li6PS5Cl]]> 1.708

[0144] Referring to Table 3, it is found that the solid electrolyte according to the embodiments of the present disclosure has excellent low voltage stability.

[0145] Compounds represented by chemical formula 3-1, chemical formula 3-3, or chemical formula 4 exhibit excellent anode interface stability. Therefore, when in contact with anode active materials such as lithium metal, these compounds do not react with the anode active materials to form an intermediate phase and can maintain physicochemical stability.

[0146] The stability of the negative electrode interface can be calculated and evaluated in the same way as the stability of the positive electrode interface described above.

[0147] Interfacial reaction energy (E) of the solid electrolyte according to embodiments of the present disclosure for use as a negative electrode active material int The results are shown in Table 4 below.

[0148] Table 4

[0149]

[0150]

[0151] Referring to Table 4, it was found that the solid electrolyte according to the embodiments of the present disclosure has excellent negative electrode interface stability.

[0152] Solid electrolytes may include those in which A1, A2, and A3 are distinct from each other and each of A1, A2, and A3 comprises Sb, Ge, or P. Solid electrolytes include compounds represented by the following chemical formula 5-1, the following chemical formula 5-2, or the following chemical formula 5-3:

[0153] [Chemical Formula 5-1]

[0154] Li5SbS4Br2;

[0155] [Chemical Formula 5-2]

[0156] Li 5.9 Ge 0.5 P 0.25 Sb 0.25 S 4.4 Cl 0.8 Br 0.8 ;or

[0157] [Chemical Formula 5-3]

[0158] Li 6.4 GeS 4.4 Cl 0.8 Br 0.8 .

[0159] Compounds represented by chemical formula 5-1, chemical formula 5-2, or chemical formula 5-3 can exhibit excellent stability over a high voltage range.

[0160] High voltage stability can be calculated and evaluated in the same way as the low voltage stability described above.

[0161] The evaluation results of the high voltage stability (high V) of the solid electrolyte according to the embodiments of this disclosure are shown in Table 5 below.

[0162] Table 5

[0163] Classification Components High V [eV] Example <![CDATA[Li5SbS4Br2]]> 2.299 Example <![CDATA[Li 5.9 Ge 0.5 P 0.25 Sb 0.25 S 4.4 Cl 0.8 Br 0.8 ]]> 2.288 Example <![CDATA[Li 6.4 GeS 4.4 Cl 0.8 Br 0.8 ]]> 2.129 Comparative example <![CDATA[Li 5.4 P 0.25 Sb 0.75 S 4.4 Cl 0.8 Br 0.8 ]]> 2.229 Comparative example <![CDATA[Li6PS5Cl]]> 2.129

[0164] Referring to Table 5, it is found that the solid electrolyte according to the embodiments of this disclosure has excellent high voltage stability.

[0165] According to embodiments of this disclosure, a solid electrolyte for lithium secondary batteries that exhibits excellent moisture stability, positive electrode interface stability, negative electrode interface stability, high voltage stability, and low voltage stability when applied to actual batteries can be obtained.

[0166] According to embodiments of this disclosure, a solid electrolyte for lithium secondary batteries with excellent stability and high lithium-ion conductivity can be obtained.

[0167] The effects of this disclosure are not limited to those described above. It should be understood that the effects of this disclosure include all effects that can be inferred from the description herein.

[0168] Although various aspects have been described, those skilled in the art will understand that this disclosure may be embodied in other specific forms without altering its technical spirit or essential characteristics. Therefore, the above embodiments should be understood as non-limiting and illustrative in any way.

Claims

1. A solid electrolyte comprising a compound represented by the following chemical formula 1: [Chemical Formula 1] Li a A1 b1 A2 b2 A3 b3 Y c X d Where Li is lithium. A1, A2, and A3 are distinct from each other, and each of A1, A2, and A3 includes antimony (Sb), tin (Sn), germanium (Ge), silicon (Si), or phosphorus (P). Y includes oxygen (O), sulfur (S), selenium (Se), or tellurium (Te). X includes chlorine (Cl), bromine (Br), iodine (I), or X1. e X2 1-e , X1 and X2 are different from each other, and X1 and X2 each include Cl, Br or I. a satisfies 5 ≤ ​​a ≤ 8. b1, b2, and b3 each satisfy 0 ≤ b1 ≤ 1, 0 ≤ b2 ≤ 1, 0 ≤ b3 ≤ 1, and b1 + b2 + b3 = 1. c satisfies 4≤c≤6. d satisfies 0 ≤ d ≤ 2, and e satisfies 0 <e<1。 2. The solid electrolyte according to claim 1, wherein... b3 is 0 A1 and A2 are different from each other, and A1 and A2 each include Sb, Sn, or Ge.

3. The solid electrolyte according to claim 1, comprising a compound represented by the following chemical formula 2-1: [Chemical Formula 2-1] Li 6.4 Sb 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8 。 4. The solid electrolyte according to claim 1, comprising a compound represented by the following chemical formula 2-2: [Chemical Formula 2-2] Li 6.4 Ge 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8 。 5. The solid electrolyte according to claim 1, comprising compounds represented by the following chemical formulas 2-3: [Chemical Formula 2-3] Li 6.4 Sb 0.25 Ge 0.75 S 4.4 Cl 0.8 Br 0.8 。 6. The solid electrolyte according to claim 1, wherein b3 is 0, A1 and A2 are different from each other, and A1 and A2 each comprise Si or Ge.

7. The solid electrolyte according to claim 1, comprising a compound represented by the following chemical formula 3-1: [Chemical Formula 3-1] Li 6.4 SiS 4.4 Cl 0.8 Br 0.8 。 8. The solid electrolyte according to claim 1, comprising compounds represented by the following chemical formulas 3-2: [Chemical Formula 3-2] Li 6.4 SiSe 4.4 Cl 0.8 Br 0.8 。 9. The solid electrolyte according to claim 1, comprising compounds represented by the following chemical formula 3-3: [Chemical Formula 3-3] Li 6.4 Si 0.75 Ge 0.25 S 4.4 Cl 0.8 Br 0.8 。 10. The solid electrolyte according to claim 1, comprising a compound represented by the following chemical formula 4: [Chemical Formula 4] Li8SiS6.

11. The solid electrolyte of claim 1, wherein A1, A2 and A3 are different from each other and each of A1, A2 and A3 comprises Sb, Ge or P.

12. The solid electrolyte according to claim 1, comprising a compound represented by the following chemical formula 5-1: [Chemical Formula 5-1] Li5SbS4Br2.

13. The solid electrolyte according to claim 1, comprising compounds represented by the following chemical formula 5-2: [Chemical Formula 5-2] Li 5.9 Ge 0.5 P 0.25 Sb 0.25 S 4.4 Cl 0.8 Br 0.8 。 14. The solid electrolyte according to claim 1, comprising compounds represented by the following chemical formulas 5-3: [Chemical Formula 5-3] Li 6.4 GeS 4.4 Cl 0.8 Br 0.8 。 15. A lithium secondary battery comprising a solid electrolyte, said solid electrolyte comprising a compound represented by the following chemical formula 1: [Chemical Formula 1] Li a A1 b1 A2 b2 A3 b3 Y c X d Where Li is lithium. A1, A2, and A3 are distinct from each other, and each of A1, A2, and A3 includes antimony (Sb), tin (Sn), germanium (Ge), silicon (Si), or phosphorus (P). Y includes oxygen (O), sulfur (S), selenium (Se), or tellurium (Te). X includes chlorine (Cl), bromine (Br), iodine (I), or X1. e X2 1-e , X1 and X2 are different from each other, and X1 and X2 each include Cl, Br or I. a satisfies 5 ≤ ​​a ≤ 8. b1, b2, and b3 each satisfy 0 ≤ b1 ≤ 1, 0 ≤ b2 ≤ 1, 0 ≤ b3 ≤ 1, and b1 + b2 + b3 = 1. c satisfies 4≤c≤6. d satisfies 0 ≤ d ≤ 2, and e satisfies 0 <e<1。 16. The lithium secondary battery according to claim 15, wherein... b3 is 0 A1 and A2 are different from each other, and A1 and A2 each include Sb, Sn, or Ge.

17. The lithium secondary battery according to claim 15, comprising a compound represented by the following chemical formula 2-1: [Chemical Formula 2-1] Li 6.4 Sb 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8 。 18. The lithium secondary battery according to claim 15, comprising a compound represented by the following chemical formula 2-2: [Chemical Formula 2-2] Li 6.4 Ge 0.25 Sn 0.75 S 4.4 Cl 0.8 Br 0.8 。 19. The lithium secondary battery according to claim 15, comprising a compound represented by the following chemical formulas 2-3: [Chemical Formula 2-3] Li 6.4 Sb 0.25 Ge 0.75 S 4.4 Cl 0.8 Br 0.8 。 20. The lithium secondary battery according to claim 15, wherein b3 is 0, A1 and A2 are different from each other and A1 and A2 each comprise Si or Ge.

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