Solid electrolyte, method for preparing the same, and all-solid-state battery

Abstract

To provide a solid electrolyte having high ionic conductivity.SOLUTION: According to a first aspect, provided is a solid electrolyte represented by the general formula 1: LiaMbX3OC, where M is a metal element having an oxidation number of +3, X is a halogen element, and 0<a≤2, 0<b≤1 and 0<c≤2 are satisfied.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a solid electrolyte, and more particularly to a solid electrolyte, a method for producing the same, and an all-solid-state battery. [Background technology]

[0002] Recently, industrial fields requiring lithium secondary batteries have expanded from power sources for small mobile devices to power sources for medium- and large-sized electric vehicles and energy storage devices. In particular, interest in environmentally friendly electric vehicles (EVs) has been growing, and major automakers around the world have made environmental friendliness their motto and are accelerating their technological development, recognizing EVs as a next-generation growth technology. Unlike small-sized batteries, medium- and large-sized EVs not only face harsh operating environments (e.g., temperature and impact), but also require the maintenance of their integrity due to the large number of batteries they contain. As a result, as industrial fields requiring lithium secondary batteries expand to include large-sized batteries, interest in the safety of these batteries is also increasing.

[0003] Conventional lithium secondary batteries, which use organic liquid electrolytes, have problems such as poor thermal stability, flammability, and leakage. In fact, explosions in products using these electrolytes have been reported on an ongoing basis, making it urgent to resolve these issues. As a result, all-solid-state batteries using solid electrolytes have emerged as an alternative solution. To achieve the full potential of such all-solid-state batteries, excellent contact properties between the solid electrolyte and electrodes are required.

[0004] Active research is being conducted into the development of solid electrolytes and the realization of all-solid-state batteries, with sulfide-based, oxide-based, and chloride-based solid electrolytes being developed, which can be broadly divided into three types depending on the type of anion. While various solid electrolytes have been developed, each has its own unique issues that limit the realization of ideal all-solid-state batteries. In particular, oxide-based solid electrolytes have high electrochemical stability, but it is difficult to easily form interfacial contact with the electrode, while sulfide-based solid electrolytes have low oxidation and reduction stability, making the introduction of a coating layer inevitable.

[0005] Chloride-based solid electrolytes, which were developed relatively recently, exhibit high oxidation stability, but have fatal weaknesses due to the need for expensive precursors and poor reduction stability, necessitating the introduction of a double solid electrolyte when fabricating an all-solid-state battery. Due to these limitations of each solid electrolyte, the industrial market is turning to sulfide-based solid electrolytes, which can achieve stable charging and discharging by adding a coating layer. However, the introduction of an additional coating layer increases costs. Therefore, to effectively replace liquid electrolyte-based lithium secondary batteries, a more economical and stable-performance solid electrolyte needs to be developed. Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a solid electrolyte having high ionic conductivity.

[0007] Another object of the present invention is to provide a solid electrolyte having high oxidative and reductive stability.

[0008] It is still another object of the present invention to provide a method for producing the solid electrolyte.

[0009] It is still another object of the present invention to provide an all-solid-state battery that can be stably charged and discharged even with an uncoated positive electrode.

[0010] Yet another object of the present invention is to provide an all-solid-state battery that has excellent life characteristics and electrochemical stability.

[0011] The objects and advantages of the present invention are not limited to those mentioned above, but may be understood from the following description and may be more clearly understood from the examples of the present invention. Furthermore, it should be readily apparent that the objects and advantages of the present invention can be achieved by the means and combinations thereof described in the specification. [Means for solving the problem]

[0012] According to a first aspect of the present invention, there is provided a solid electrolyte represented by the following general formula 1: [Formula 1] Li a M b X3O C

[0013] In the general formula 1, M is a metal element having an oxidation number of +3, X is a halogen element, and 0 <a≦2、0<b≦1、0<c≦2である。

[0014] According to a second aspect of the present invention, in the first aspect, M in General Formula 1 may be any one selected from the group consisting of Al, Ga, Y, La, and Ac.

[0015] According to a third aspect of the present invention, in the first or second aspect, M in General Formula 1 may include Al.

[0016] According to a fourth aspect of the present invention, in any one of the first to third aspects, the halogen element in General Formula 1 may be F, Cl, or Br.

[0017] According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a and c in Formula 1 may be the same or a=2c.

[0018] According to a sixth aspect of the present invention, there is provided a method for producing a solid electrolyte, comprising the step of (S1) mixing and reacting lithium oxide with MX3 to synthesize a solid electrolyte represented by the following general formula 1: [Formula 1] Li a M b X3O C

[0019] In the general formula 1, M is a metal element having an oxidation number of +3, X is a halogen element, and 0 <a≦2、0<b≦1、0<c≦2である。

[0020] According to a seventh aspect of the present invention, in the sixth aspect, the reaction may be carried out in an organic solvent or by solid-phase mixing.

[0021] According to an eighth aspect of the present invention, in the sixth or seventh aspect, the mixing may be carried out at 400 to 600 rpm for a time period exceeding 0 and not exceeding 72 rpm.

[0022] According to a ninth aspect of the present invention, there is provided an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte according to any one of the first to fifth aspects interposed between the positive electrode and the negative electrode. For example, the solid electrolyte may be manufactured by the manufacturing method according to at least one of the sixth to eighth aspects.

[0023] According to a tenth aspect of the present invention, in the ninth aspect, the solid electrolyte includes a first layer in contact with the positive electrode and a second layer in contact with the negative electrode, and at least one of the first layer and the second layer may include the solid electrolyte.

[0024] The above solution to the problem is not an exhaustive list of the features of the present invention, and the various features and advantages and results thereof will be more fully understood by reference to the following detailed description. [Effects of the Invention]

[0025] According to one aspect of the present invention, a solid electrolyte having high ionic conductivity and high oxidation and reduction stability can be realized.

[0026] According to another aspect of the present invention, an all-solid-state battery having excellent life characteristics and electrochemical stability can be realized.

[0027] The specific effects of the present invention, together with the above-mentioned effects, will be described together with the details of the embodiments of the present invention below. Furthermore, the effects of the present invention are not limited to the above-mentioned effects, and can be easily realized by the means and combinations thereof described in the specification. [Brief explanation of the drawings]

[0028] [Figure 1a] FIG. 1 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention. [Figure 1b] FIG. 2 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention. [Figure 2] 1 shows the results of XRD (X-ray Diffraction) analysis of LiOH, LiO, and the solid electrolytes according to Examples 1 to 10. [Figure 3] 1 is a graph showing the discharge capacity of each of the all-solid-state batteries according to Production Examples 3 and 4 as a function of the number of cycles. [Figure 4a] 10 is a graph showing the current due to changes in voltage applied to the electrolyte of Example 5. [Figure 4b] This is a graph of cyclic voltammetry for Li2ZrCl6(Ref). [Figure 4c] 10 shows the oxidation current depending on the voltage applied when the number of cycles of the all-solid-state battery according to Example 5-2 is different. [Figure 4d] 10 shows the reduction current depending on the voltage applied when the number of cycles of the all-solid-state battery according to Example 5-2 is different. [Figure 5] 10 is a graph showing the charge and discharge characteristics of the all-solid-state battery according to Production Example 3 at different cycle numbers. [Figure 6]10 is a graph showing the charge and discharge characteristics of the all-solid-state battery according to Production Example 4 at different cycle numbers. DETAILED DESCRIPTION OF THE INVENTION

[0029] In this specification, the singular expression includes the plural expression unless the context clearly indicates otherwise.

[0030] As used herein, the terms "comprise" and / or "comprising" specify the presence of a stated shape, step, number, operation, member, element, and / or group thereof, but do not exclude the presence or addition of one or more other shapes, steps, numbers, operations, members, elements, and / or groups thereof.

[0031] As used herein, "at least one of a, b, and c" may include a, b, or c alone, or a combination of two or more selected from the group consisting of a, b, and c.

[0032] When several examples are described in this specification, unless otherwise specified, the respective embodiments may be combined. In this case, the effects of the present invention may be defined to include effects based on each embodiment and effects resulting from organically combining the respective embodiments. For example, even if Embodiments 1 and 2 are described independently in this specification, unless otherwise clearly indicated in the context, Embodiments 1 and 2 may be organically combined with each other, and the effects of the present invention may include effects resulting from combining Embodiments 1 and 2.

[0033] In this specification, numerical ranges indicated using the term "to" indicate a numerical range that includes the values ​​before and after the term as the lower and upper limits, respectively. If multiple numerical values ​​are disclosed as the upper and lower limits of a given numerical range, the numerical range disclosed in this specification can be understood as any numerical range with any one value among the multiple lower limits and any one value among the multiple upper limits as the lower and upper limits, respectively. For example, if the specification states a to b or c to d, it can be understood that the ranges described are a to b, a to d, c to d, or c to b.

[0034] As used herein, terms such as "about" or "substantially" refer to a reasonable amount of deviation from the modified term so as not to significantly alter the end result. Such terms may be interpreted to include a deviation of at least ±5% or at least ±10%, within the limits where such deviation does not alter or invalidate the meaning of the word.

[0035] According to one aspect of the present invention, there is provided a solid electrolyte represented by the following general formula 1: [Formula 1] Li a M b X3O C

[0036] In the general formula 1, M is a metal element having an oxidation number of +3, X is a halogen element, and 0 <a≦2、0<b≦1、0<c≦2である。

[0037] According to one aspect of the present invention, a solid electrolyte containing a halogen element or an oxygen element can be realized, which exhibits high oxidation stability and high reduction stability.

[0038] The configuration of the present invention will be described in more detail below.

[0039] 1.Solid electrolyte According to a first aspect of the present invention, there is provided a solid electrolyte represented by the following general formula 1: [Formula 1] Li a Mb X3O C

[0040] In the general formula 1, M is a metal element having an oxidation number of +3, X is a halogen element, and 0 <a≦2、0<b≦1、0<c≦2である。

[0041] Specifically, in the general formula 1, a and c may each independently be 1 to 1.2. When a and c in the general formula 1 each independently are 1 to 1.2, the effect of increasing the ionic conductivity of the solid electrolyte may be realized.

[0042] Specifically, in the general formula 1, M may be any one selected from the group consisting of Al, Ga, Y, La, and Ac, and more specifically, may include Al. When M is Al, it is more economical than other metal elements, and when O (oxygen) anions are used together, a synergistic effect can be obtained in terms of electrochemical stability.

[0043] Specifically, in the general formula 1, the halogen element may be F, Cl, or Br, and more specifically, Cl. Here, if the halogen element is Cl, the effect of higher ionic conductivity compared to F may be realized, and the effect of less decomposition into halogen gas may be realized compared to Br. Therefore, if the halogen element is Cl, higher oxidation stability may be realized.

[0044] In some embodiments of the present invention, a and c may be the same or a=2c in General Formula 1. According to some embodiments of the present invention, by adjusting a and c to be the same in General Formula 1, high ionic conductivity and a solid electrolyte having high oxidation and reduction stability may be realized, and an all-solid-state battery having excellent life characteristics and electrochemical stability may be realized.

[0045] In some embodiments, the solid electrolyte is Li 0.6 AlCl3O 0.6 , Li 0.8 AlCl3O 0.8 , Li 0.9AlCl3O 0.9 , LiAlCl3O, Li 1.1 AlCl3O 1.1 , Li 1.2 AlCl3O 1.2 , Li 1.3 AlCl3O 1.3 , Li 1.4 AlCl3O 1.4 , Li 1.5 AlCl3O 1.5 , or Li 1.6 AlCl3O 1.6 It could be.

[0046] In some embodiments of the present invention, the amorphous phase content of the solid electrolyte may be 50 to 85% based on the total phase. The amorphous phase content may be measured using an XRD analysis method and a purification method using an internal standard. According to some embodiments of the present invention, when the amorphous phase content is within the above range, a synergistic effect of increasing the ionic conductivity of the solid electrolyte may be realized.

[0047] 2. Manufacturing method of solid electrolyte According to another aspect of the present invention, there is provided a method for producing a solid electrolyte, comprising the step of (S1) mixing and reacting lithium oxide and MX3 to synthesize a solid electrolyte represented by the following general formula 1: [Formula 1] Li a M b X3O C

[0048] In the general formula 1, M is a metal element having an oxidation number of +3, X is a halogen element, and 0 <a≦2、0<b≦1、0<c≦2である。

[0049] Specifically, the lithium oxide may include Li2O2. According to some embodiments of the present invention, the lithium oxide may include Li2O2, which may result in higher ionic conductivity of the solid electrolyte and improved oxidation and reduction stability.

[0050] In some embodiments of the present invention, the mixing may be performed at 400 to 600 rpm, 450 to 600 rpm, 500 to 600 rpm, 550 to 600 rpm, or 580 to 600 rpm for a time of more than 0 to 72 hours, 10 to 60 hours, 20 to 50 hours, 20 to 40 hours, 20 to 30 hours, 20 to 25 hours, 21 to 24 hours, 22 to 24 hours, or 23 to 24 hours. Specifically, when the stirring speed and stirring time of the mixing are within the above ranges, a solid electrolyte having higher ionic conductivity may be achieved.

[0051] In some embodiments of the present invention, the molar ratio of the lithium oxide to MX3 (lithium oxide:MX3) may be 0.1:1 to 1:1, 0.2:1 to 1:1, 0.3:1 to 0.9:1, 0.3:1 to 0.8:1, 0.4:1 to 0.75:1, 0.4:1 to 0.7:1, 0.45:1 to 0.65:1, 0.5:1 to 0.65:1, 0.5:1 to 0.6:1, or 0.55:1 to 0.6:1. According to some embodiments of the present invention, when the molar ratio of the lithium oxide to MX3 satisfies the above numerical ranges, a synergistic effect on the ionic conductivity of the solid electrolyte may be more effectively exhibited.

[0052] 3.All-solid-state battery FIG. 1a is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0053] FIG. 1b is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0054] 1a and 1b, an all-solid-state battery 100 according to some embodiments of the present invention may include a positive electrode 10, a negative electrode 30, and a solid electrolyte 50 according to some embodiments interposed between the positive electrode 10 and the negative electrode 30.

[0055] As shown in FIG. 1a, the solid electrolyte 50 of one embodiment of the present invention may have a single composition without separating the positive and negative electrodes.

[0056] 1b, a solid electrolyte 50 according to another embodiment of the present invention may include a first layer 50a adjacent to the positive electrode 10 and a second layer 50b adjacent to the negative electrode 30. In some embodiments of the present invention, the solid electrolyte 50 may be included in at least one of the first layer 50a and the second layer 50b.

[0057] positive electrode The cathode 10 according to the present invention may be a layer containing a cathode active material, which may be a lithium-containing metal oxide capable of electrochemically inserting or extracting lithium through an oxidation-reduction reaction.

[0058] In some embodiments of the present invention, the cathode 10 may be an uncoated cathode material without a coating layer. In some embodiments of the present invention, a coating layer may not be required at the cathode because a solid electrolyte with high ionic conductivity and excellent oxidation and reduction stability is implemented.

[0059] For example, the positive electrode active material may include a lithium transition metal oxide. x1 CoO2(0.5 <x1<1.3)、Li x2 NiO2(0.5 <x2<1.3)、Li x3 MnO2(0.5 <x3<1.3)、Li x4 Mn2O4(0.5 <x4<1.3)、Li x5 (Ni a1 Co b1 Mn c1 )O2(0.5 <x5<1.3、0<a1<1、0<b1<1、0<c1<1、a1+b1+c1=1)、Li x6 Ni 1-y1 Co y1 O2(0.5 <x6<1.3、0<y1<1)、Li x7 Co 1-y2 Mn y2 O2(0.5 <x7<1.3、0≦2<1)、Li x8 Ni 1-y3 Mn y3 O2(0.5 <x8<1.3、O≦3<1)、Li x9(Ni a2 Co b2 Mn c2 )O4 (0.5 < x9 < 1.3, 0 < a2 < 2, 0 < b2 < 2, 0 < c2 < 2, a2 + b2 + c2 = 2), Li x10 Mn 2-z1 Ni z1 O4 (0.5 < x10 < 1.3, 0 < z1 < 2), Li x11 Mn 2-z2 Co z2 O4 (0.5 < x11 < 1.3, 0 < z2 < 2), Li x12 CoPO4 (0.5 < x12 < 1.3), and Li x13 FePO4 (0.5 < x13 < 1.3), and may be one or more selected from the group consisting of.

[0060] In some embodiments, the positive electrode may further include a conductive material. For example, the conductive material can improve the conductivity between the particles of the positive electrode active material or with the positive electrode current collector in the positive electrode and prevent the binder from acting as an insulator. The conductive material can be, for example, a mixture of one or more conductive materials selected from the group consisting of graphite, carbon black, carbon fiber, metal fiber, metal powder, conductive whisker, conductive metal oxide, activated carbon, and polyphenylene derivative, and more specifically, natural graphite, artificial graphite, Super - P, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, Denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide, and can be a mixture of one or more conductive materials selected from the group consisting of.

[0061] In some examples, the positive electrode can further include a binder. Examples of the binder include poly(vinylidene fluoride co-hexafluoropropylene), poly(vinylidene fluoride-co-trichloroethylene), poly(methylmethacrylate), poly(ethylhexylacrylate), poly(butylacrylate), poly(acrylonitrile), poly(vinylpyrrolidone), poly(vinyl acetate), ethylene-vinyl acetate copolymer (poly(ethylene-co-vinyl acetate)), polyethylene oxide, polyacrylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, and the like. The polymer may be, but is not limited to, pullulan, cyano ethyl poly(vinylalcohol), cyanoethylcellulose, cyanoethylsucrose, pullulan, styrene-butadiene rubber, and carboxyl methyl cellulose.

[0062] If necessary, the positive electrode 10 may further include a current collector. Specifically, the current collector may include SUS, aluminum, nickel, iron, titanium, carbon, and the like.

[0063] negative electrode The negative electrode 30 according to the present invention may include a negative electrode active material capable of electrochemically inserting or extracting lithium through an oxidation-reduction reaction.

[0064] For example, the negative electrode active material may be metallic lithium, or a LiAl-based, LiAg-based, LiPb-based, LiSi-based, or LiIn-based alloy that is alloyed with lithium. The negative electrode active material may also be a common carbon material such as non-graphitizable carbon obtained by carbonizing graphite or resin, easily graphitizable carbon obtained by heat-treating coke, or fullerene, or a metal oxide such as TiO2 or SnO2 that has a potential relative to lithium of less than 2 V, but is not limited thereto.

[0065] In some embodiments, the negative electrode 30 may further include at least one of a binder and a conductive material, where the binder and conductive material may have the same or different compositions as those described above.

[0066] If necessary, the negative electrode 30 may further include a current collector. Specifically, the current collector may include SUS, aluminum, nickel, iron, titanium, carbon, and the like.

[0067] Hereinafter, the embodiments of the present invention will be described in detail so that a person having ordinary skill in the art to which the present invention pertains can easily implement the present invention. However, this is merely an example, and the scope of the present invention is not limited by the following content.

[0068] [Production Example 1: Production of solid electrolyte] <Examples 1 and 11: Solid electrolytes with different molar ratios of Li2O2 and AlCl3> A mixture of Li2O2 and AlCl3 in the molar ratios shown in Table 1 below was milled in a high energy ball mill at 400 to 600 rpm for 0 to 72 hours.

[0069] [Table 1]

[0070] <Comparative Example 1: Commercial LiAlCl4> LiAlCl4 was synthesized as Comparative Example 1. A 1:1 molar mixture of LiCl and AlCl3 was milled at 600 rpm for 24 hours using a high-energy ball mill. Alternatively, a 1:1 molar mixture of LiCl and AlCl-3 was heated in a quartz crucible in a vacuum atmosphere at 120 °C for 24 hours to synthesize commercial LiAlCl4.

[0071] <Comparative example 2: LiAlCl 2.5 O 0.75 Synthesis example of LiAlCl 2.5 O 0.75 is synthesized through two processes. First, LiAlCl4 was synthesized by heating a mixture of LiCl and AlCl3 in a 1:1 molar ratio at 180°C. Second, the synthesized LiAlCl-4 was mixed with Sb2O3 in a 4:1 molar ratio and heated at 250°C for over an hour to remove gaseous SbCl5, resulting in LiAlCl 2.5 O 0.75 was synthesized.

[0072] Comparative Example 3: Synthesis of LiOH-AlCl A mixture of LiOH and AlCl3 in a 1:1 molar ratio was milled using a high-energy ball mill at 600 rpm for 24 h.

[0073] Comparative Example 4: Synthesis of Li2O-AlCl3 A mixture of Li2O and AlCl3 in a 1:1 molar ratio was milled using a high-energy ball mill at 600 rpm for 72 h.

[0074] [Experimental Example 1: Ionic Conductivity of Solid Electrolytes] In a glove box under an argon atmosphere, a sample of the solid electrolyte of Preparation Example 1 was weighed and placed in a polyetheretherketone tube (PEEK tube, inner diameter 10 mm, outer diameter 30 mm, height 20 mm) and sandwiched between powder molding jigs containing stainless steel (SUS) from above and below. Next, the sample was pressed at 3 tons using a uniaxial press (Lambda Scientific) to form pellets with a diameter of 10 mm and a desired thickness. The resulting pellets were placed in a sealed electrochemical cell capable of maintaining an argon atmosphere.

[0075] [Table 2]

[0076] Referring to Table 2 and FIG. 2, Example 5 exhibited higher ionic conductivity of the solid electrolyte than Comparative Examples 1, 3, and 4.

[0077] [Experimental Example 2: Phase analysis of solid electrolytes] FIG. 2 shows the XRD analysis results of LiOH, Li2O, and the solid electrolytes according to Examples 1 to 10.

[0078] Referring to Figure 2, it was confirmed that the solid electrolytes of Examples 4 to 10 had a phase consisting of LiCl and amorphous material. Here, LiCl may act as a space-charge layer and not block the ion conductivity path. The amorphous material may play a role in increasing the ion conductivity of the solid electrolyte.

[0079] [Production Example 3: Production of all-solid-state battery containing double solid electrolyte] The positive electrode is made of a positive electrode active material (LiNi 0.6 Co 0.2 Mn 0.2An all-solid-state battery of Example 5-1 including a dual solid electrolyte was manufactured using a cathode containing LiO, NCM622, and the solid electrolyte of Example 5, which was manufactured using a precursor with a molar ratio of LiO:AlCl of 0.55:1 only in the cathode side solid electrolyte, a Li-In alloy as the anode; a solid electrolyte of Azirodite Li6PS5Cl as the anode side; and a current collector made of Steel Use Stainless (SUS).

[0080] [Production Example 4: Production of all-solid-state battery containing a single solid electrolyte] An all-solid-state battery was manufactured in the same manner as in Preparation Example 3, except that the electrolytes on the positive and negative electrodes were not separated. An all-solid-state battery of Example 5-2 was manufactured, which included the single solid electrolyte of Example 5 manufactured using a precursor with a Li2O2:AlCl3 molar ratio of 0.55:1.

[0081] [Experimental Example 3: Evaluation of life performance of all-solid-state batteries] The all-solid-state batteries according to Preparation Examples 3 and 4 were charged and discharged in the range of 3.0 to 4.3 V vs. Li, and the current density was adjusted to 18 mA / g to evaluate the lifespan performance.

[0082] FIG. 3 is a graph showing the discharge capacity of the all-solid-state batteries according to Production Examples 3 and 4 as a function of the number of cycles.

[0083] 3, it was confirmed that the all-solid-state batteries according to Preparation Examples 3 and 4 had excellent lifespan characteristics and were capable of stable charge and discharge. Specifically, it was confirmed that the all-solid-state batteries according to Preparation Examples 3 and 4 maintained their discharge capacities well without significant decline even with an increase in the number of cycles.

[0084] [Experimental Example 4: Evaluation of Linear Sweep Voltammetry] FIG. 4a is a graph showing the current as a function of the applied voltage to the electrolyte of Example 5. FIG. 4b is a graph showing the cyclic voltammetry of Li2ZrCl6(Ref). Here, Ref is the current measured by the cyclic voltammetry method described in "Kwak, Hiram, et al., New cost-effective halide solid electrolytes for all-solid-state batteries: mechanochemically prepared Fe 3+ -substituted LiZrCl. "Advanced Energy Materials 11.12 (2021): 2003190." Figure 4c shows the oxidation current as a function of applied voltage when the all-solid-state battery according to Example 5-2 is cycled at different numbers. Figure 4d shows the reduction current as a function of applied voltage when the all-solid-state battery according to Example 5-2 is cycled at different numbers.

[0085] 4a to 4d, it was confirmed that the electrolyte of Example 5 exhibited high oxidation stability due to the Cl anions in its structure and high reduction stability due to the introduction of oxygen anions. As a result, it was confirmed that the electrolyte of Example 5 maintained a stable phase over a wide voltage range of 0.9-4.4 V vs. Li. This means that the electrolyte of Example 5 is much more stable over a wide voltage range compared to LiAlCl4, which has a potential window of 1.54-4.4 V vs. Li, and Li6PS5Cl, which has a potential window of 1.71-2.01 V vs. Li.

[0086] [Experimental Example 5: Evaluation of the electrochemical performance of all-solid-state batteries] The all-solid-state batteries of Production Examples 3 and 4 were each charged and discharged at a current of 18 mA / g in the range of 3.0 to 4.3 V.

[0087] Fig. 5 is a charge / discharge graph showing different cycle numbers of the all-solid-state battery according to Production Example 3. Fig. 6 is a charge / discharge graph showing different cycle numbers of the all-solid-state battery according to Production Example 4.

[0088] 5 and 6, it was confirmed that the all-solid-state batteries according to Preparation Examples 3 and 4 had excellent electrochemical stability even after a large number of cycles.

[0089] The features described in one embodiment above may be combined with other embodiments unless explicitly stated to the contrary. Furthermore, although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention. [Explanation of symbols]

[0090] 10: Positive electrode 30: Negative electrode 50: Solid electrolyte 100: All-solid battery

Claims

1. A solid electrolyte represented by the following general formula 1: [Formula 1] Li ａ M ｂ X ３ O Ｃ In the general formula 1, M is a metal element having an oxidation number of +3; X is a halogen element; 0<a≦2, 0<b≦1, 0<c≦2.

2. In the general formula 1, M is any one selected from the group consisting of Al, Ga, Y, La, and Ac; The solid electrolyte according to claim 1 .

3. In the general formula 1, M contains Al. The solid electrolyte according to claim 1 .

4. In the general formula 1, the halogen element is F, Cl, or Br. The solid electrolyte according to claim 1 .

5. In the general formula 1, a and c are the same or a=2c; The solid electrolyte according to claim 1 .

6. (S1) Lithium oxide and MX ３ The method includes mixing and reacting the above to synthesize a solid electrolyte represented by the following general formula 1: Method for producing solid electrolyte: [Formula 1] Li ａ M ｂ X ３ O Ｃ In the general formula 1, M is a metal element having an oxidation number of +3; X is a halogen element; 0<a≦2, 0<b≦1, 0<c≦2.

7. The reaction is carried out in an organic solvent or by solid-phase mixing. The method for producing the solid electrolyte according to claim 6 .

8. The mixing is carried out at 400 to 600 rpm for a time greater than 0 and less than 72 hours. The method for producing the solid electrolyte according to claim 6 .

9. A positive electrode and a negative electrode; The solid electrolyte according to any one of claims 1 to 5 is interposed between the positive electrode and the negative electrode. All-solid-state battery.

10. The solid electrolyte is a first layer in contact with the positive electrode; a second layer in contact with the negative electrode, At least one of the first layer and the second layer contains the solid electrolyte. The all-solid-state battery according to claim 9 .

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