SOLID ELECTROLYTE, METHOD FOR PREPARING THE SAME, AND ALL-SOLID-STATE BATTERY

Abstract

Provided is a solid electrolyte having high ion conductivity. According to an aspect, provided is a solid electrolyte represented by General Formula 1 below.

Li.sub.aM.sub.bX.sub.3O.sub.c[General Formula 1]

In General Formula 1 above, M is a metal element having an oxidation number of +3, X is a halogen element, and 0<a2, 0<b1, and 0<c2.

Claims

1. A solid electrolyte represented by General Formula 1 below:
Li.sub.aM.sub.bX.sub.3O.sub.c[General Formula 1] wherein in General Formula 1 above, M is a metal element having an oxidation number of +3, X is a halogen element, and 0<a2, 0<b1, and 0<c2.

2. The solid electrolyte of claim 1, wherein in General Formula 1 above, M is one selected from the group consisting of Al, Ga, Y, La, and Ac.

3. The solid electrolyte of claim 1, wherein in General Formula 1 above, M comprises Al.

4. The solid electrolyte of claim 1, wherein in General Formula 1 above, the halogen element is F, Cl, or Br.

5. The solid electrolyte of claim 1, wherein in General Formula 1 above, a and c are the same, or a=2c.

6. A method for preparing a solid electrolyte, the method comprising (S1) mixing and reacting lithium oxide and MX.sub.3 to synthesize a solid electrolyte represented by General Formula 1 below:
Li.sub.aM.sub.bX.sub.3O.sub.c[General Formula 1] wherein in General Formula 1 above, M is a metal element having an oxidation number of +3, X is a halogen element, and 0<a2, 0<b>1, and 0<c2.

7. The method of claim 6, wherein the reaction is performed in an organic solvent or by solid-phase mixing.

8. The method of claim 6, wherein the mixing is performed at 400 rpm to 600 rpm for more than 0 hour to 72 hours or less.

9. An all-solid-state battery comprising: a positive electrode; a negative electrode; and a solid electrolyte according to claim 1 interposed between the positive electrode and the negative electrode.

10. The all-solid-state battery of claim 9, wherein the solid electrolyte comprises: a first layer in contact with the positive electrode; and a second layer in contact with the negative electrode, wherein at least one of the first layer and the second layer includes the solid electrolyte.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Exemplary embodiments can be understood in more detail from the following description taken in conjunction with the accompanying drawings, in which:

[0027] FIG. 1A is a cross-sectional view of an all-solid-state battery in accordance with an exemplary embodiment of the present invention;

[0028] FIG. 1B is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention;

[0029] FIG. 2 shows results of X-ray diffraction (XRD) analysis of LiOH, Li.sub.2O, and solid electrolytes according to Examples 1 to 10;

[0030] FIG. 3 is a graph showing a discharge capacity according to the number of cycles of each all-solid-state battery according to Preparation Examples 3 and 4;

[0031] FIG. 4A is a graph showing a current according to a change in the voltage applied to an electrolyte of Example 5;

[0032] FIG. 4B shows a cyclic voltammetry graph of Li.sub.2ZrCl.sub.6 (Ref);

[0033] FIG. 4C shows an oxidation current according to a voltage applied when the number of cycles of an all-solid-state battery according to Example 5-2 is changed;

[0034] FIG. 4D shows a reduction current according to a voltage applied when the number of cycles of the all-solid-state battery according to Example 5-2 is changed;

[0035] FIG. 5 is a charge/discharge graph according to a change in the number of cycles of an all-solid-state battery according to Preparation Example 3; and

[0036] FIG. 6 is a charge/discharge graph according to a change in the number of cycles of an all-solid-state battery according to Preparation Example 4.

DETAILED DESCRIPTION OF EMBODIMENTS

[0037] In the present specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0038] In the present specification, the terms comprise and/or comprising specify the presence of stated shapes, steps, numbers, operations, members, elements and/or groups thereof, and do not preclude the presence or addition of one or more other shapes, steps, numbers, operations, members, elements and/or groups thereof.

[0039] In the present specification, at least one of a, b and c may include a, b and c alone or a combination of two or more selected from the group consisting of a, b and c.

[0040] In the present specification, if several embodiments are described, each embodiment may be combined unless specifically stated otherwise. In this case, an effect of the present invention may be defined as including an effect derived from each embodiment and an effect derived from an organic combination of each embodiment. For example, even if embodiments 1 and 2 are independently described in the present specification, unless the context clearly indicates otherwise, the embodiments 1 and 2 may be organically combined with each other, and an effect of the present invention may include an effect derived from the combination of the embodiments 1 and 2.

[0041] In the present specification, the range of numerical values expressed using the term to indicates the range of numerical values including values described before and after the term as lower and upper limit values, respectively. If a plurality of numerical values are described as an upper limit and a lower limit of an arbitrary numerical range, respectively, the numerical range described in the present specification may be understood as an arbitrary numerical range having any one value among a plurality of lower limit values and any one value among a plurality of upper limit values as a lower limit value and an upper limit value, respectively. For example, if a to b, or c to d is described in the specification, it may be understood that equal to or higher than a to equal to or lower than b, equal to or higher than a to equal to or lower than d, equal to or higher than c to equal to or lower than d, or equal to or higher than c to equal to or lower than b is described.

[0042] In the present specification, a term such as about or substantially refers to a reasonable amount of deviation of a term modified such that a final result does not significantly change. These terms may be interpreted as including a deviation of at least+5% or at least+10% within a limit in which the deviation does not modify and invalidate the meaning of a word.

[0043] According to an aspect of the present invention, there is provided a solid electrolyte represented by General Formula 1 below.

Li.sub.aM.sub.bX.sub.3O.sub.c[General Formula 1]

[0044] In General Formula 1 above, M is a metal element having an oxidation number of +3, X is a halogen element, and 0<a2, 0<b1, and 0<c2.

[0045] According to an aspect of the present invention, a solid electrolyte exhibiting high oxidation stability and high reduction stability may be implemented by including a halogen element and an oxygen element in the solid electrolyte.

[0046] Hereinafter, the configuration of the present invention will be described in more detail.

1. Solid Electrolyte

[0047] According to an aspect of the present invention, there is provided a solid electrolyte represented by General Formula 1 below.

Li.sub.aM.sub.bX.sub.3O.sub.c[General Formula 1]

[0048] In General Formula 1 above, M is a metal element having an oxidation number of +3, X is a halogen element, and 0<a2, 0<b1, and 0<c2.

[0049] Specifically, in General Formula 1 above, a and c may each independently be 1 to 1.2. In General Formula 1 above, if a and c are each independently 1 to 1.2, an effect of further increasing the ion conductivity of the solid electrolyte may be implemented.

[0050] Specifically, in General Formula 1 above, M may be one selected from the group consisting of Al, Ga, Y, La, and Ac, and more specifically, may include Al. If M is Al, it has excellent economic feasibility compared to other metal elements, and if used together with O (oxygen) anions, a synergistic effect in electrochemical stability may be obtained.

[0051] Specifically, in General Formula 1 above, the halogen element may be F, Cl, or Br, and specifically, may be Cl. Here, if the halogen element is Cl, an effect of further increasing the ion conductivity may be implemented compared to F, and an effect of allowing less decomposition into a halogen gas may be implemented compared to Br. Accordingly, if the halogen element is Cl, higher oxidation stability may be implemented.

[0052] In some embodiments of the present invention, in General Formula 1 above, it may be that a and c are the same, or a=2c. According to some embodiments of the present invention, since a and c are controlled to be the same as each other in General Formula 1 above, a solid electrolyte implementing high ion conductivity, and having high oxidation stability and reduction stability may be implemented, and at the same time, an all-solid-state battery having excellent lifespan properties and electrochemical stability may be implemented.

[0053] In some examples, the solid electrolyte may be Li.sub.0.6AlCl.sub.3O.sub.0.6, Li.sub.0.8AlCl.sub.3O.sub.0.8, Li.sub.0.9AlCl.sub.3O.sub.0.9, LiAlCl.sub.3O, Li.sub.1.1AlCl.sub.3O.sub.1.1, Li.sub.1.2AlCl.sub.3O.sub.1.2, Li.sub.1.3AlCl.sub.3O.sub.1.3, Li.sub.1.4AlCl.sub.3O.sub.1.4, Li.sub.1.5AlCl.sub.3O.sub.1.5, or Li.sub.1.6AlCl.sub.3O.sub.1.6.

[0054] In some embodiments of the present invention, the content of an amorphous phase based on the total phase of the solid electrolyte may be 50% to 85%. The content of the amorphous phase may be measured by a method of refinement using an internal standard material by using an XRD analysis method. According to some embodiments of the present invention, if the content of the amorphous phase satisfies the above-described numerical range, a synergistic effect of further increasing the ion conductivity of the solid electrolyte may be implemented.

2. Method for Preparing Solid Electrolyte

[0055] According to another aspect of the present invention, there is provided a method for preparing a solid electrolyte, the method including (S1) mixing and reacting lithium oxide and MX.sub.3 to synthesize a solid electrolyte represented by General Formula 1 below.

Li.sub.aM.sub.bX.sub.3O.sub.c[General Formula 1]

[0056] In General Formula 1 above, M is a metal element having an oxidation number of +3, X is a halogen element, and 0<a2, 0<b1, and 0<c2.

[0057] Specifically, the lithium oxide may include Li.sub.2O.sub.2. According to some embodiments of the present invention, since the lithium oxide includes Li.sub.2O.sub.2, the ion conductivity of the solid electrolyte may be implemented further higher, and at the same time, the oxidation stability and reduction stability thereof may be further improved.

[0058] In some embodiments of the present invention, the mixing may be performed at 400 rpm to 600 rpm, 450 rpm to 600 rpm, 500 rpm to 600 rpm, 550 rpm to 600 rpm, or 580 rpm to 600 rpm for more than 0 hour to 72 hours or less, 10 hours to 60 hours, 20 hours to 50 hours, 20 hours to 40 hours, 20 hours to 30 hours, 20 hours to 25 hours, 21 hours to 24 hours, 22 hours to 24 hours, or 23 hours to 24 hours. Specifically, if the mixing rate and the stirring time of the mixing satisfy the above-described numerical ranges, a solid electrolyte having further higher ion conductivity may be implemented.

[0059] In some embodiments of the present invention, the molar ratio (lithium oxide:MX.sub.3) of the lithium oxide to the MX.sub.3 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, if the molar ratio of the lithium oxide to the MX.sub.3 satisfies the above-described numerical range, a synergistic effect on the ion conductivity of the solid electrolyte may be further expressed.

3. All-Solid-State Battery

[0060] FIG. 1A is a cross-sectional view of an all-solid-state battery in accordance with an exemplary embodiment of the present invention.

[0061] FIG. 1B is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0062] Referring to FIGS. 1A and 1B, an all-solid-state battery 100 of some embodiments of the present invention may include a positive electrode 10, a negative electrode 30, and a solid electrolyte 50 of some embodiments interposed between the positive electrode 10 and the negative electrode 30.

[0063] As illustrated in FIG. 1A, the solid electrolyte 50 according to an embodiment of the present invention may have a single composition without distinction between a positive electrode and a negative electrode.

[0064] As illustrated in FIG. 1B, the 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.

Positive Electrode

[0065] The positive electrode 10 according to the present invention may be a layer containing a positive electrode active material. The positive electrode active material may be a metal oxide including lithium, the metal oxide capable of electrochemically intercalating or deintercalating lithium by an oxidation-reduction reaction.

[0066] In some embodiments of the present invention, the positive electrode 10 may be a non-coated positive electrode material without a coating layer. According to some embodiments of the present invention, since a solid electrolyte having high ion conductivity and excellent oxidation stability and reduction stability is implemented, a coating layer may not be required in a positive electrode.

[0067] For example, the positive electrode active material may include a lithium transition metal oxide. The lithium transition metal oxide may be, for example, one more selected from the group consisting of Li.sub.x1CoO.sub.2(0.5<x1<1.3), Li.sub.x2NiO.sub.2(0.5<.sub.x2<1.3), Li.sub.x3MnO.sub.2(0.5<x3<1.3), Li.sub.x4Mn.sub.2O.sub.4 (0.5<x4<1.3), Li.sub.x5(Ni.sub.a1Co.sub.b1Mn.sub.c1)O.sub.2(0.5<x5<1.3, 0<a1<1, 0<b1<1, 0<c1<1, a1+b1+c1=1), Li.sub.x6Ni.sub.1-y1Co.sub.y1O.sub.2 (0.5<x6<1.3, 0<y1<1), Li.sub.x7Co.sub.1-y2Mn.sub.y2O.sub.2 (0.5<x7<1.3, 02<1), Li.sub.x8Ni.sub.1-y3Mn.sub.y3O.sub.2 (0.5<x8<1.3, O<3<1), Li.sub.x9 (Nia.sub.2CO.sub.b2Mn(2)O.sub.4 (0.5<x9<1.3, 0<a2<2, 0<b2<2, 0<c2<2, a2+b2+c2=2), Li.sub.x10Mn.sub.2-z1Ni.sub.z1O.sub.4 (0.5<x10<1.3, 0<z1<2), Li.sub.x11Mn.sub.2-z2Co.sub.z2O.sub.4 (0.5<x11<1.3,0<z2<2), Li.sub.x12CoPO.sub.4 (0.5<x12<1.3), and Li.sub.x13FePO.sub.4 (0.5<x13<1.3).

[0068] In some examples, the positive electrode may further include a conductive material. For example, the conductive material may improve conductivity between positive electrode active material particles or with a positive electrode current collector in the positive electrode, and may prevent a binder from acting as a non-conductor. The conductive material may be, for example, a mixture of one or two or more conductive materials selected from the group consisting of graphite, carbon black, carbon fiber, metal fiber, metal powder, a conductive whisker, a conductive metal oxide, activated carbon and a polyphenylene derivative, and more specifically, may be a mixture of one or two or more conductive materials selected from the group consisting of natural graphite, artificial graphite, Super-p, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, Denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide.

[0069] In some examples, the positive electrode may further include a binder. For example, the binder may be, for example, poly(vinylidene fluoride co-hexafluoropropylene), poly(vinylidene fluoride-co-trichloroethylene), poly(methylmethacrylate), poly(ethylhexylacrylate), poly(butylacrylate), poly(acrylonitrile), poly(vinylpyrrolidone), poly(vinyl acetate), poly(ethylene-co-vinyl acetate), poly(ethylene oxide), polyacrylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyano ethyl pullulan, cyano ethyl poly(vinylalcohol), cyano ethylcellulose, cyano ethylsucrose, pullulan, styrene-butadiene rubber, carboxyl methyl cellulose, or the like, but is not limited thereto.

[0070] If necessary, the positive electrode 10 may further include a current collector, and specifically, the current collector may include SUS, aluminum, nickel, iron, titanium, carbon, or the like.

Negative Electrode

[0071] The negative electrode 30 according to the present invention may include a negative electrode active material capable of electrochemically intercalating or deintercalating lithium by an oxidation-reduction reaction.

[0072] For example, the negative electrode active material may be metal lithium or a LiAl-based, LiaG-based, LiPb-based, LiSi-based, or LiIn-based alloy that is alloyed with lithium. In addition, the negative electrode active material may use a general carbon material such as graphite, non-graphitized carbon in which a resin is calcined-carbonized, graphitized carbon in which cokes are heat-treated, or fullerene, or may use a metal oxide such as TiO.sub.2, or SnO.sub.2 having a potential of less than 2 V for lithium, but is not limited thereto.

[0073] In some examples, the negative electrode 30 may further include one or more of a binder and a conductive material. Here, the binder and the conductive material may be the same as or different from the above-described composition.

[0074] If necessary, the negative electrode 30 may further include a current collector, and specifically, the current collector may include SUS, aluminum, nickel, iron, titanium, carbon, or the like. Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art to which the present invention belongs may easily implement the present invention, but this is merely an example, and the scope of rights of the present invention is not limited by the following contents.

Preparation Example 1: Preparation of Solid Electrolyte

5<Examples 1 to 11: Solid electrolytes with different molar ratios of Li.SUB.2.O.SUB.2 .to AlCl.SUB.3.>

[0075] Mixtures obtained by mixing Li.sub.2O.sub.2 and AlCl.sub.3 at molar ratios described in Table 1 below were crushed at 400 rpm to 600 rpm for more than 0 hour to 72 hours using a high energy ball mill.

TABLE-US-00001 TABLE 1 Rotation Stirring Molar ratio of rate time Li.sub.2O.sub.2 to AlCl.sub.3 Classification (rpm) (hour) (Li.sub.2O.sub.2:AlCl.sub.3) Product Example 1 600 24 0.3:1 Li.sub.0.6AlCl.sub.3O.sub.0.6 Example 2 600 24 0.4:1 Li.sub.0.8AlCl.sub.3O.sub.0.8 Example 3 600 24 0.45:1 Li.sub.0.9AlCl.sub.3O.sub.0.9 Example 4 600 24 0.5:1 LiAlCl.sub.3O Example 5 600 24 0.55:1 Li.sub.1.1AlCl.sub.3O.sub.1.1 Example 6 600 24 0.6:1 Li.sub.1.2AlCl.sub.3O.sub.1.2 Example 7 600 24 0.65:1 Li.sub.1.3AlCl.sub.3O.sub.1.3 Example 8 600 24 0.7:1 Li.sub.1.4AlCl.sub.3O.sub.1.4 Example 9 600 24 0.75:1 Li.sub.1.5AlCl.sub.3O.sub.1.5 Example 10 600 24 0.8:1 Li.sub.1.6AlCl.sub.3O.sub.1.6

Comparative Example 1: Commercial LiAlCl.SUB.4

[0076] LiAlCl.sub.4 was synthesized as Comparative Example 1. A mixture obtained by mixing LiCl and AlCl.sub.3 at a molar ratio of 1:1 was crushed at 600 rpm for 24 hours using a high energy ball mill. Alternatively, a mixture obtained by mixing LiCl and AlCl.sub.3 at a molar ratio of 1:1 was heated in a quartz crucible under a vacuum atmosphere at 120 C. for 24 hours to synthesize commercial LiAlCl.sub.4.

Comparative Example 2: Synthesis Example of LiAlCl.SUB.2.5.O.SUB.0.75

[0077] LiAlCl.sub.2.5O.sub.0.75 was synthesized through two processes. First, a mixture obtained by mixing LiCl and AlCl.sub.3 at a molar ratio of 1:1 was heated at 180 C. to synthesize LiAlCl.sub.4. Second, a mixture obtained by mixing the synthesized LiAlCl.sub.4 and Sb.sub.2O.sub.3 at a molar ratio of 4:1 was heated at 250 C. for 1 hour or more to remove gaseous SbCls, thereby synthesizing LiAlCl.sub.2.5O.sub.0.75.

Comparative Example 3: Synthesis Example of LiOHAlCl.SUB.3

[0078] A mixture obtained by mixing LiOH and AlCl.sub.3 at a molar ratio of 1:1 was crushed at 600 rpm for 24 hours using a high energy ball mill.

Comparative Example 4: Synthesis example of LizO-AlCl.SUB.3

[0079] A mixture obtained by mixing Li.sub.2O and AlCl.sub.3 at a molar ratio of 1:1 was crushed at 600 rpm for 72 hours using a high energy ball mill.

Experimental Example 1: Ion conductivity of solid electrolyte

[0080] In a glove box under an argon atmosphere, a sample of the solid electrolyte of Preparation Example 1 was weighed and placed in a polyether ether ketone tube (PEEK tube, inner diameter 10 mm, outer diameter 30 mm, and height 20 mm), and inserted from above and below between powder molding jigs containing Stainless Use Steel (SUS). Next, the sample was pressed using a uniaxial press machine (manufactured by Lambda Scientific Co., Ltd.) at 3 ton to mold a pellet having a diameter of 10 mm and an arbitrary thickness. The obtained pellet was placed in a sealed-type electrochemical cell capable of maintaining an argon atmosphere.

TABLE-US-00002 TABLE 2 Molar ratio of Ion Li.sub.2O.sub.2 to AlCl.sub.3 Chemical conductivity Classification (Li.sub.2O.sub.2:AlCl.sub.3) Formula (S/cm) Comparative LiAlCl.sub.4 1.2*10.sup.6 Example 1 Comparative LiAlCl.sub.2.5O.sub.0.75 1.52*10.sup.3 Example 2 Comparative LiAlCl.sub.3OH 5.3*10.sup.6 Example 3 Comparative Li.sub.2AlCl.sub.3O 6.19*10.sup.5 Example 4 Example 1 0.3:1 Li.sub.0.6AlCl.sub.3O.sub.0.6 3.5*10.sup.5 Example 2 0.4:1 Li.sub.0.8AlCl.sub.3O.sub.0.8 1.62*10.sup.4 Example 3 0.45:1 Li.sub.0.9AlCl.sub.3O.sub.0.9 1.70*10.sup.4 Example 4 0.5:1 LiAlCl.sub.3O 2.1*10.sup.4 Example 5 0.55:1 Li.sub.1.1AlCl.sub.3O.sub.1.1 3.77*10.sup.4 Example 6 0.6:1 Li.sub.1.2AlCl.sub.3O.sub.1.2 3.24*10.sup.4 Example 7 0.65:1 Li.sub.1.3AlCl.sub.3O.sub.1.3 1.56*10.sup.4 Example 8 0.7:1 Li.sub.1.4AlCl.sub.3O.sub.1.4 6.2*10.sup.5 Example 9 0.75:1 Li.sub.1.5AlCl.sub.3O.sub.1.5 5.39*10.sup.5 Example 10 0.8:1 Li.sub.1.6AlCl.sub.3O.sub.1.6 1.37*10.sup.5

[0081] Referring to Table 2 above and FIG. 2, Example 5 exhibited higher ion conductivity of the solid electrolyte than Comparative Examples 1, 3, and 4.

Experimental Example 2: Analysis of Phase of Solid Electrolyte

[0082] FIG. 2 shows results of X-ray diffraction (XRD) analysis of LiOH, LizO, and solid electrolytes according to Examples 1 to 10.

[0083] Referring to FIG. 2, it has been confirmed that the solid electrolytes of Examples 4 to 10 had a phase consisting of LiCl and an amorphous. Here, the LiCl may serve as a space-charge layer, and at the same time, may not block a path of ion conduction. The amorphous serve to increase ion conductivity of the solid electrolytes.

Preparation Example 3: Preparation of all-Solid-State Battery Including Double Solid Electrolytes

[0084] An all-solid-state battery of Example 5-1 including double solid electrolytes was prepared by using a positive electrode including a positive electrode active material (LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2, NCM622) as a positive electrode, the solid electrolyte of Example 5, which was prepared using a precursor having a molar ratio of Li.sub.2O.sub.2: AlCl.sub.3 of 0.55:1, as a solid electrolyte of the positive electrode only, a LiIn alloy as a negative electrode, argyrodite Li.sub.6PS.sub.5Cl as a solid electrolyte of the negative electrode, and Steel Use Stainless (SUS) as a current collector.

Preparation Example 4: Preparation of all-Solid-State Battery Including Single Solid Electrolyte

[0085] An all-solid-state battery of Example 5-2 including a single solid electrolyte was prepared, wherein the all-solid-state battery was prepared in the same manner as in Preparation Example 3, except that the solid electrolyte of Example 5, which was prepared using a precursor having a molar ratio of Li.sub.2O.sub.2: AlCl.sub.3 of 0.55:1 was used without differentiating between the positive electrode and negative electrode electrolytes.

Experimental Example 3: Evaluation of Lifespan Performance of all-Solid-State Battery

[0086] Charge/discharge was performed on each of the all-solid-state batteries according to Preparation Examples 3 and 4 in a band of 3.0 V to 4.3 V compared to Li, and at this time, the current density was controlled to 18 mA/g to evaluate lifespan performance.

[0087] FIG. 3 is a graph showing a discharge capacity according to the number of cycles of each all-solid-state battery according to Preparation Examples 3 and 4.

[0088] Referring to FIG. 3, it has been confirmed that the all-solid-state batteries according to Preparation Examples 3 and 4 both have excellent lifespan properties and are capable of being charged and discharged stably. Specifically, it has been confirmed that the solid-state batteries according to Preparation Examples 3 and 4 maintain the discharge capacity well without significant degradation even if the number of cycles increases.

Experimental Example 4: Evaluation of linear sweep voltammetry

[0089] FIG. 4A is a graph showing a current according to a change in the voltage applied to an electrolyte of Example 5. FIG. 4B shows a cyclic voltammetry graph of Li.sub.2ZrCl.sub.6 (Ref). Here, the Ref is Kwak, Hiram, et al. New cost-effective halide solid electrolytes for all-solid-state batteries: mechanochemically prepared Fe3+-substituted Li2ZrC16. Advanced Energy Materials 11.12 (2021): 2003190. FIG. 4C shows an oxidation current according to a voltage applied when the number of cycles of an all-solid-state battery according to Example 5-2 is changed. FIG. 4D shows a reduction current according to a voltage applied when the number of cycles of the all-solid-state battery according to Example 5-2 is changed.

[0090] Referring to FIGS. 4A to 4B, it has been confirmed that the electrolyte of Example 5 implements high oxidation stability with the introduction of Cl anions into the structure and high reduction stability with the introduction of oxygen anions thereinto. Accordingly, it has been confirmed that the electrolyte of Example 5 stably maintains the phase in a wide voltage band of 0.9 V to 4.4 V compared to Li. This means that the electrolyte is a much more stable electrolyte in a wide voltage range compared to LiAlCl.sub.4, which has a potential window of 1.54 V to 4.4 V, or Li.sub.6PS.sub.5Cl, which has a potential window of 1.71 V to 2.01 V, compared to Li.

Experimental Example 5: Evaluation of Electrochemical Performance of all-Solid-State Battery

[0091] Charge/discharge was performed on each of the all-solid-state batteries according to Preparation Examples 3 and 4 at a current of 18 mA/g and a band of 3.0 V to 4.3 V.

[0092] FIG. 5 is a charge/discharge graph according to a change in the number of cycles of an all-solid-state battery according to Preparation Example 3. FIG. 6 is a charge/discharge graph according to a change in the number of cycles of an all-solid-state battery according to Preparation Example 4.

[0093] Referring to FIGS. 5 and 6, it has been confirmed that the all-solid-state batteries according to Preparation Examples 3 and 4 have excellent electrochemical stability even if the number of cycles increases.

[0094] According to an aspect of the present invention, a solid electrolyte implementing high ion conductivity, and having high oxidation stability and reduction stability may be implemented.

[0095] According to another aspect of the present invention, an all-solid-state battery having excellent lifespan properties and electrochemical stability may be implemented.

[0096] In addition to the above-described effects, specific effects of the present invention will be described together while explaining the specific details for carrying out the invention below.

[0097] In addition, effects of the present invention are not limited to the effects mentioned above, and may be easily implemented by means described herein and combinations thereof.

[0098] The features described in the above-described one embodiment may be combined with other embodiments, unless explicitly stated otherwise. In addition, although 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 by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

Description of the Reference Numerals or Symbols

[0099] 10: Positive electrode [0100] 30: Negative electrode [0101] 50: Solid electrolyte [0102] 100: All-solid-state battery