Solid electrolyte and lithium ion battery

Abstract

The present application provides a solid electrolyte having high conductivity accompanied by Br, high stability in a dry room controlled to a dew point of -40°C, and a significantly recovered reduced conductivity by heat treatment. The solid electrolyte contains Li, M α , M β , M γ , Cl, and Br, M α is at least one element selected from the group consisting of Zr and Hf, M β is at least one element selected from the group consisting of Ta, Nb, and Mo, and M γ is at least one element selected from the group consisting of Gd, Yb, Dy, Er, Ho, Eu, Sc, and Al.

Description

Technical Field

[0001] This invention relates to solid electrolytes and lithium-ion batteries. Background Technology

[0002] In recent years, there has been a strong demand for miniaturization and improved reliability (safety) of batteries used as power sources for electronic devices. Therefore, all-solid-state batteries, which use solid electrolytes instead of liquid electrolytes, have attracted considerable attention. Sulfide-based solid electrolytes are a representative type of solid electrolyte. However, sulfide-based solid electrolytes can potentially produce toxic hydrogen sulfide; therefore, from a safety perspective, there is a desire for solid electrolytes that are not sulfide-based.

[0003] Halides have been proposed as sulfur-free solid electrolytes. For example, Patent Document 1 (Japanese Patent No. 7316571) discloses a solid electrolyte that uses Li... 3－3δ－a Y 1＋δ－a M a Cl 6－x－y Br x I y (In the formula, M represents Zr and / or Hf, and -1 < δ < 1, 0.1 ≤ a ≤ 0.9, 0 < (3 - 3δ - a), 0 < (1 + δ - a), 0 ≤ x ≤ 6, 0 ≤ y ≤ 6, and (x + y) ≤ 6) This compositional expression is presented. The document discloses: Li 2.5 Y 0.5 Zr 0.5 The solid electrolyte with the Cl6 composition exhibits high lithium-ion conductivity at room temperature. Furthermore, Li₂ with Br doped at some Cl sites... 2.5 Y 0.5 Zr 0.5 Solid electrolytes composed of Cl5Br exhibit higher conductivity.

[0004] In addition, Patent Document 2 (WO2024 / 010065) discloses a solid electrolyte comprising A, Mα, Mβ, Mγ and Cl, wherein A is at least one element selected from the group consisting of Li and Na, Mα is at least one element selected from the group consisting of Zr and Hf, Mβ is at least one element selected from the group consisting of Ta and Nb, Mγ is at least one element selected from the group consisting of Gd, Yb, Dy, Er, Ho, Eu and Sc, and the mass of Cl is greater than the mass of A.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 7316571

[0008] Patent Document 2: WO2024 / 010065 Summary of the Invention

[0009] As mentioned above, Li is known 2.5 Y 0.5 Zr 0.5 Cl6, Li 2.5 Y 0.5 Zr 0.5 Chloride electrolytes such as Cl5Br (refer to Patent Document 1) exhibit high conductivity at room temperature; however, no reports have been made regarding the stability of these electrolytes. Therefore, the inventors of this invention prepared chloride electrolyte powder disclosed in Patent Document 1 and placed it in a drying chamber with the dew point controlled at -40°C. The results showed that the electrolyte decomposed and could not maintain its initial conductivity. Furthermore, it was determined that in compositions where Br was doped at a portion of the Cl sites, the conductivity increased; however, the stability decreased in the drying chamber with the dew point controlled at -40°C.

[0010] The inventors of this invention recently discovered that by including Li and M α M β M γ In solid electrolytes of Cl and Br, as M α M β and M γ By employing specific metal elements, it is possible to provide a solid electrolyte that exhibits high conductivity associated with the inclusion of Br, high stability in a dry chamber with dew point controlled to -40°C, and significant recovery of reduced conductivity through heat treatment.

[0011] Therefore, the object of the present invention is to provide a solid electrolyte having high conductivity associated with the inclusion of Br, high stability in a dry chamber with dew point controlled to -40°C, and the ability to significantly restore reduced conductivity through heat treatment.

[0012] According to the present invention, the following solution is provided.

[0013] [Option 1]

[0014] A solid electrolyte comprising Li and M α M β M γ Cl and Br,

[0015] The solid electrolyte is characterized in that...

[0016] M α To select at least one element from the group consisting of Zr and Hf,

[0017] M βTo select at least one element from the group consisting of Ta, Nb, and Mo,

[0018] M γ It is to select at least one element from the group consisting of Gd, Yb, Dy, Er, Ho, Eu, Sc and Al.

[0019] [Option 2]

[0020] The solid electrolyte according to Scheme 1 is characterized in that,

[0021] M α Including Zr.

[0022] [Option 3]

[0023] The solid electrolyte according to scheme 1 or 2 is characterized in that,

[0024] M β Including Ta.

[0025] [Option 4]

[0026] The solid electrolyte according to any one of claims 1 to 3 is characterized in that,

[0027] M γ It includes at least one element selected from the group consisting of Gd, Yb, and Er.

[0028] [Option 5]

[0029] The solid electrolyte according to any one of claims 1 to 3 is characterized in that,

[0030] Includes components expressed in the following formula:

[0031] Li 6－（4＋a－b）（1＋c） (M) α （1－a－b） M β a M γ b ) 1＋c Cl 6－2d－e－f O d F e Br f

[0032] It satisfies 0 < a, 0 < b, a + b < 1, -0.2 ≤ c ≤ 0.2, 0 ≤ d < 3, 0 ≤ e < 6, and 0 < f < 6.

[0033] [Option 6]

[0034] A lithium-ion battery comprising the solid electrolyte described in any one of embodiments 1 to 5. Attached Figure Description

[0035] Figure 1 This is a simplified cross-sectional view showing an example of an all-solid-state battery according to the present invention. Detailed Implementation

[0036] solid electrolyte

[0037] The solid electrolyte involved in this invention comprises Li and M α M β M γ Cl and Br. M α To select at least one element from the group consisting of Zr and Hf. M β To select at least one element from the group consisting of Ta, Nb, and Mo. M γ To select at least one element from the group consisting of Gd, Yb, Dy, Er, Ho, Eu, Sc, and Al. This is achieved by selecting an element containing Li, M... α M β M γ By employing specific constituent elements in solid electrolytes containing Cl and Br, it is possible to provide solid electrolytes that exhibit high conductivity associated with the inclusion of Br, high stability in a dry chamber with dew point controlled to -40°C, and significant recovery of reduced conductivity through heat treatment.

[0038] As described above, the inventors of this invention prepared the chloride electrolyte powder disclosed in Patent Document 1 and placed it in a drying chamber with the dew point controlled at -40°C. The results showed that the electrolyte decomposed and could not maintain its initial conductivity. Furthermore, it was determined that the conductivity increased in compositions where Br was doped at a portion of the Cl sites, but the stability decreased in the drying chamber with the dew point controlled at -40°C. Therefore, the inventors of this invention... x MClyBr z In a composition system (M being a cation), various cations were used to prepare materials to explore cations with good stability and their combinations, aiming to improve the stability of chloride electrolytes. Furthermore, various cations and combinations were investigated, and it was found that using cation M as M... α Includes Zr, as M β Includes Ta, as M γ Li containing Gd and / or Yb x (M) α M β M γ Cl y Br z The solid electrolyte represented by the composition formula, despite containing Br, is able to possess high initial conductivity (10 at room temperature). －4(S / cm) and high stability (conductivity of 10 at room temperature after standing in a dry chamber for 16 hours). ―4 (S / cm or higher). Furthermore, the same trend was observed with respect to combinations of elements other than those mentioned above. In addition, it was confirmed that by allowing the solid electrolyte of the above composition to stand in a drying chamber and then heat-treating it at 150°C, the temporarily reduced conductivity can be restored. This invention is based on these insights, perfectly eliminating the aforementioned problems, and as a result, providing a high-conductivity solid electrolyte material that can be processed in a drying chamber environment with a dew point of -40°C and is highly suitable for battery manufacturing processes.

[0039] As described above, the solid electrolyte of the present invention comprises Li and M. α M β M γ Cl and Br. Solid electrolytes can be halides containing these elements and possessing the properties of solid electrolytes; there are no particular limitations, however, Li... x (M) α M β M γ Cl y Br z This basic composition can be one in which Br is doped at a portion of the Cl sites, or in which not only Br is doped but also O and / or F. Specifically, such solid electrolytes preferably include compositions expressed by the following formula:

[0040] Li 6－（4＋a－b）（1＋c） (M) α （1－a－b） M β a M γ b ) 1＋c Cl 6－2d－e－f O d F e Br f

[0041] (Where, 0 < a, 0 < b, a + b < 1, -0.2 ≤ c ≤ 0.2, 0 ≤ d < 3, 0 ≤ e < 6, and 0 < f < 6). Furthermore, solid electrolytes can be crystalline or amorphous.

[0042] M α It is an element that exhibits a tetravalent cation. M α The selection is to choose at least one element from the group consisting of Zr and Hf, typically including Zr.

[0043] M β It is an element that exhibits a pentavalent cation. M βTo select at least one element from the group consisting of Ta, Nb, and Mo, typically including Ta. Regarding M... β The correlation coefficient a, 0 < a (where a + b < 1), preferably satisfies 0 < a ≤ 0.8, more preferably satisfies 0.1 ≤ a ≤ 0.5.

[0044] M γ It is an element that exhibits a trivalent cation. M γ The selection involves choosing at least one element from the group consisting of Gd, Yb, Dy, Er, Ho, Eu, Sc, and Al, typically including at least one element from the group consisting of Gd, Yb, and Er. Regarding M... γ The correlation coefficient b, 0 < b (where a + b < 1), preferably satisfies 0 < b ≤ 0.8, more preferably satisfies 0.25 ≤ b ≤ 0.75.

[0045] Regarding the coefficient c, -0.2 ≤ c ≤ 0.2, preferably -0.15 ≤ c ≤ 0.15, more preferably -0.1 ≤ c ≤ 0.1, and typically c = 0.

[0046] As can be seen from the above composition formula, the Cl site can contain not only Cl, but also Br, the desired O, and the desired F. Regarding the coefficient f associated with Br, 0 < f < 6, preferably 0 < f ≤ 2.0, more preferably 0.3 ≤ f ≤ 1.0. O is an optional element, and regarding the coefficient d associated with O, 0 ≤ d < 3, preferably 0 ≤ d < 0.5, more preferably 0 ≤ d ≤ 0.4. F is also an optional element, and regarding the coefficient e associated with F, 0 ≤ e < 6, preferably 0 ≤ e ≤ 2, more preferably 0 ≤ e ≤ 1.

[0047] In confirming whether the unknown solid electrolyte is the aforementioned solid electrolyte, a chemical analysis is performed on the unknown solid electrolyte to confirm whether the constituent elements are Li and M. α M β M γ Cl, O, F, or Br are acceptable. Additionally, in confirming whether an unknown solid electrolyte has the above composition, for example, regarding Li, M... α M β and M γ For Cl, F, and Br, quantification can be performed using an ICP-luminescence spectrophotometer. For O, quantification can be performed using ion chromatography.

[0048] Lithium-ion batteries

[0049] According to a preferred embodiment of the present invention, a lithium-ion battery comprising the solid electrolyte of the present invention is provided. This lithium-ion battery is preferably a lithium-ion secondary battery, more preferably an all-solid-state lithium-ion secondary battery. Particularly preferred is an all-solid-state lithium-ion secondary battery. Figure 1 An example of the lithium-ion battery 10 involved in the present invention is shown schematically.

[0050] The positive electrode 12 contains a positive electrode active material. The positive electrode active material preferably contains a lithium composite oxide. Examples of lithium composite oxides include lithium nickel manganese oxide (LNMO) (typically LiNi). 0.5 Mn 1.5 Lithium nickel cobalt manganese oxide (NCM) (typically Li(Ni,Co,Mn)O2), lithium cobalt oxide (LCO) (typically LiCoO2), lithium nickel cobalt aluminum oxide (NCA) (typically Li(Ni,Co,Al)O2), and lithium iron phosphate (LFP) (typically LiFePO4) and combinations thereof. NCM, LCO, and NCA have a layered rock salt structure. LNMO has a spinel-type structure. LFP has an olivine-type structure. Preferably, lithium composite oxides with a layered rock salt structure are used, such as NCM. The positive electrode 12 preferably contains, in addition to the positive electrode active material, a solid electrolyte and / or an electron conduction aid (carbon black, etc.). In this embodiment, the positive electrode 12 is obtained by integrating these materials under pressure and heat. Therefore, as... Figure 1 As shown, the positive electrode 12 is typically in the form of a positive electrode layer. When the positive electrode 12 contains a solid electrolyte, the solid electrolyte described later is preferred.

[0051] The negative electrode 14 contains a voltage that can operate at 0.1V (relative to Li / Li). ＋ The above describes the negative electrode active materials that facilitate the insertion and removal of lithium ions. Examples of negative electrode active materials include lithium titanate (LTO) (typically Li4Ti5O). 12 LTO, SiO, Si or Si alloys, TiO2, and combinations thereof are preferred as negative electrode active materials in terms of non-flammability, and LTO is particularly preferred in terms of cycle performance. It should be noted that LTO is typically known as a material with a spinel-type structure; however, other structures can be used during charge-discharge. For example, LTO can be used as Li4Ti5O during charge-discharge. 12 (Spinel structure) and Li7Ti5O 12The reaction occurs in a two-phase coexistence (rock salt structure). Therefore, LTO is not limited to a spinel structure. From the viewpoint of improving ionic conductivity, the negative electrode 14 is preferably composed of a solid electrolyte in addition to the negative electrode active material. The negative electrode 14 may further contain an electron conduction aid (carbon black, etc.). In this scheme, the negative electrode 14 is obtained by integrating these materials through pressure and heating. Therefore, as... Figure 1 As shown, the negative electrode 14 is typically in the form of a negative electrode layer. When the negative electrode 14 contains a solid electrolyte, the solid electrolyte described above in this invention is preferably used as such.

[0052] The electrolyte layer 16 is an electrolyte-containing layer disposed between the positive electrode 12 and the negative electrode 14. Typically, the electrolyte layer 16 contains a solid electrolyte, preferably composed of a solid electrolyte. In this case, the electrolyte layer 16 can be said to also serve as a separator. As the solid electrolyte contained in the electrolyte layer 16, the solid electrolyte involved in the present invention described above is preferably used.

[0053] At least one of the positive electrode 12, the negative electrode 14, and the electrolyte layer 16 comprises the solid electrolyte according to the present invention. The solid electrolyte exhibits high ionic conductivity (e.g., lithium-ion conductivity). Furthermore, this solid electrolyte is non-flammable and chemically stable, and does not produce hydrogen sulfide gas; therefore, an inherently safe lithium-ion battery 10 can be achieved. However, it is not necessary for all of the positive electrode 12, the negative electrode 14, and the electrolyte layer 16 to comprise the aforementioned solid electrolyte; at least any one of them may contain the aforementioned solid electrolyte.

[0054] The solid electrolyte of this invention can be mixed with other substances to be used as an electrolyte material. In this case, the solid electrolyte is preferably the component with the largest mass percentage in the electrolyte material, i.e., the main component. The mass percentage of the main component in the electrolyte material is preferably 50% by weight or more, more preferably 60% by weight or more, and even more preferably 70% by weight or more.

[0055] As described above, in the lithium-ion battery 10 of the present invention, the positive electrode 12, the negative electrode 14, and the electrolyte layer 16 can be made of sulfide-free materials. That is, preferably, none of the positive electrode 12, the negative electrode 14, and the electrolyte layer 16 contains sulfides. Accordingly, an inherently safe lithium-ion battery 10 that does not produce toxic gases such as hydrogen sulfide can be provided.

[0056] The lithium-ion battery 10 preferably further comprises a positive current collector 18 and a negative current collector 20. The positive current collector 18 is preferably disposed on the side of the positive electrode 12 opposite to the electrolyte layer 16, and the negative current collector 20 is preferably disposed on the side of the negative electrode 14 opposite to the electrolyte layer 16. Examples of materials constituting the positive current collector 18 and the negative current collector 20 include: aluminum (Al), copper (Cu), titanium (Ti), nickel (Ni), stainless steel (SUS), carbon, platinum (Pt), platinum (Pt) / palladium (Pd), gold (Au), silver (Ag), ITO (indium-tin oxide film), etc.

[0057] The container 22 can be any container capable of storing a single lithium-ion battery 10 or a battery stack formed by connecting multiple lithium-ion batteries 10 in series or parallel; there are no particular limitations. In particular, if the lithium-ion battery 10 is an all-solid-state battery, there is no concern about electrolyte leakage, so the container 22 can adopt a relatively simple container form. For example, it can adopt a chip form for mounting in a circuit or a laminated single-cell form (e.g., a multilayer of aluminum (Al) / polypropylene (PP)) for thin and spacious applications.

[0058] Example

[0059] The invention will be further illustrated by the following examples. However, the invention is not limited to these examples.

[0060] Example 1

[0061] (1) Preparation of electrolytes

[0062] In an argon atmosphere with a dew point below -60°C, raw material powders of LiCl, LiBr, ZrCl4, ZrF4, HfCl4, TaCl5, MoCl5, Gd2O3, YbCl3, DyCl3, ErCl3, and HoCl3 were weighed according to the molar ratio of LiCl:LiBr:ZrCl4:ZrF4:HfCl4:TaCl5:MoCl5:Gd2O3:YbCl3:DyCl3:ErCl3:HoCl3 = 1.8:0.5:0.125:0.075:0.2:0.1:0.05:0.025:0.05:0.1:0.2:0.05. These raw material powders were then pulverized and mixed in a mortar. The resulting mixture was placed in a zirconia jar and milled using a planetary ball mill at 300 rpm for 20 hours to obtain a solid electrolyte powder.

[0063] (2) Conductivity measurement

[0064] Solid electrolyte powder was placed into a mold consisting of a resin sleeve and upper and lower stainless steel punches, and uniaxially pressed at 150 MPa. Wires were connected to the upper and lower punches, and impedance measurements were performed at room temperature. The lithium-ion conductivity (hereinafter referred to as the initial conductivity C1) was calculated based on the measurement results. The results are shown in Table 1.

[0065] (3) Exposure test

[0066] Place the solid electrolyte powder into a shallow dish and let it stand for 16 hours in a dry room with the dew point controlled at -40°C.

[0067] (4) Heat treatment

[0068] The solid electrolyte powder, which had been left to stand in a drying chamber for 16 hours, was then heat-treated at 150°C.

[0069] (5) Stability evaluation

[0070] For the solid electrolyte powder that was left to stand in the drying chamber in (3) above and the solid electrolyte powder that underwent heat treatment in (4) above, impedance measurements were performed at room temperature in the same manner as in (2) above, and the lithium-ion conductivity of each powder was calculated. Then, the conductivity C2 after the exposure test and the conductivity C3 after the exposure test and heat treatment were divided by the initial conductivity C1 and multiplied by 100, respectively, to calculate the conductivity retention rate of each powder. These results are shown in Table 1.

[0071] Example 2

[0072] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, LiBr, ZrCl4, ZrF4, HfCl4, TaCl5, MoCl5, Gd2O3, YbCl3, DyCl3, ErCl3, and HoCl3 were weighed according to the molar ratio of LiCl:LiBr:ZrCl4:ZrF4:HfCl4:TaCl5:MoCl5:Gd2O3:YbCl3:DyCl3:ErCl3:HoCl3 = 1.3:1.0:0.125:0.075:0.2:0.1:0.05:0.025:0.05:0.1:0.2:0.05. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0073] Example 3

[0074] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, LiBr, ZrCl4, TaCl5 and ErCl3 were weighed according to the molar ratio of LiCl:LiBr:ZrCl4:TaCl5:ErCl3 = 1.25:0.5:0.25:0.5:0.25. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0075] Example 4

[0076] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, LiBr, ZrCl4, TaCl5 and ErCl3 were weighed according to the molar ratio of LiCl:LiBr:ZrCl4:TaCl5:ErCl3 = 0.75:1.0:0.25:0.5:0.25. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0077] Example 5

[0078] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, LiBr, ZrCl4, TaCl5, DyCl3, ErCl3, HoCl3 and AlCl3 were weighed according to the molar ratio of LiCl:LiBr:ZrCl4:TaCl5:DyCl3:ErCl3:HoCl3:AlCl3 = 2.3:0.3:0.2:0.1:0.3:0.1:0.2:0.1. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0079] Example 6

[0080] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, LiBr, ZrCl4, TaCl5, MoCl5, Gd2O3, YbCl3, DyCl3, ErCl3, HoCl3, and AlCl3 were weighed according to the molar ratio of LiCl:LiBr:ZrCl4:TaCl5:MoCl5:Gd2O3:YbCl3:DyCl3:ErCl3:HoCl3:AlCl3 = 2.2:0.45:0.15:0.05:0.05:0.025:0.05:0.35:0.15:0.05:0.1. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0081] Example 7 (Compare)

[0082] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, LiBr, YCl3 and ZrCl4 were weighed according to the molar ratio of LiCl:LiBr:YCl3:ZrCl4 = 2.0:0.5:0.5:0.5. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0083] Example 8 (Compare)

[0084] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, LiBr, YCl3 and ZrCl4 were weighed according to the molar ratio of LiCl:LiBr:YCl3:ZrCl4 = 1.5:1.0:0.5:0.5. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0085] Example 9 (Compare)

[0086] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, LiBr, YCl3 and ZrCl4 were weighed according to the molar ratio of LiCl:LiBr:YCl3:ZrCl4 = 0.5:2.0:0.5:0.5. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0087] Example 10 (refer to)

[0088] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, ZrCl4, ZrF4, HfCl4, TaCl5, MoCl5, Gd2O3, YbCl3, DyCl3, ErCl3, and HoCl3 were weighed according to the molar ratio of LiCl:ZrCl4:ZrF4:HfCl4:TaCl5:MoCl5:Gd2O3:YbCl3:DyCl3:ErCl3:HoCl3 = 2.3:0.125:0.075:0.2:0.1:0.05:0.025:0.05:0.1:0.2:0.05. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0089] Example 11 (refer to)

[0090] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, ZrCl4, TaCl5 and ErCl3 were weighed according to the molar ratio of LiCl:ZrCl4:TaCl5:ErCl3 = 1.75:0.25:0.5:0.25. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0091] Example 12 (refer to)

[0092] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, ZrCl4, TaCl5, DyCl3, ErCl3, HoCl3 and AlCl3 were weighed according to the molar ratio of LiCl:ZrCl4:TaCl5:DyCl3:ErCl3:HoCl3:AlCl3 = 2.6:0.2:0.1:0.3:0.1:0.2:0.1. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0093] Example 13 (refer to)

[0094] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, ZrCl4, TaCl5, MoCl5, Gd2O3, YbCl3, DyCl3, ErCl3, HoCl3, and AlCl3 were weighed according to the molar ratio of LiCl:ZrCl4:TaCl5:MoCl5:Gd2O3:YbCl3:DyCl3:ErCl3:HoCl3:AlCl3 = 2.65:0.15:0.05:0.05:0.025:0.05:0.35:0.15:0.05:0.1. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0095] Example 14 (refer to)

[0096] In the preparation of the electrolyte in Example 1, the raw material powders of LiCl, YCl3 and ZrCl4 were weighed according to the molar ratio of LiCl:YCl3:ZrCl4 = 2.5:0.5:0.5. Otherwise, the preparation and evaluation of the electrolyte were carried out in the same manner as in Example 1.

[0097] result

[0098] Table 1 shows the composition and measurement results of the solid electrolytes prepared in Examples 1-15. Additionally, to confirm that the compositional formulas of Examples 1-6 satisfy Li... 6－（4＋a－b）（1＋c） (M) α （1－a－b） M β a M γ b ) 1＋c Cl 6－2d－e－f O d F e Br f (where a > 0, b > 0, a + b < 1, -0.2 ≤ c ≤ 0.2, 0 ≤ d < 3, 0 ≤ e < 6 and 0 < f < 6), Table 2 shows the composition formulas and coefficients applicable to the above general formula.

[0099] Table 1

[0100]

[0101] Table 2

[0102]

[0103] The results shown in Table 1 reveal the following: Comparisons of Examples 1 and 2 (containing Br) and Reference Example 10 (excluding Br), Examples 3 and 4 (containing Br) and Reference Example 11 (excluding Br), Examples 5 (containing Br) and Reference Example 12 (excluding Br), and Examples 6 (containing Br) and Reference Example 13 (excluding Br) show that: by adding Br, a high initial conductivity can be achieved, and even after exposure for 16 hours in a dry chamber with a dew point controlled at -40°C (although reduced to some extent), the conductivity is maintained with a high retention rate. Furthermore, the conductivity reduced by the aforementioned exposure can be significantly restored through heat treatment.

[0104] In contrast, the prior art involving Li as disclosed in Patent Document 1... x (Y, Zr)Cl y Br z The composition system, compared with Comparative Examples 7-9 (containing Br) and Reference Example 14 (excluding Br), shows that the addition of Br improves the initial conductivity. However, after exposure for 16 hours in a dry chamber with a dew point controlled at -40°C, the conductivity drops sharply, and the reduced conductivity due to the exposure cannot be recovered by heat treatment. Based on these results, it can be said that the solid electrolyte of the present invention exhibits unexpectedly superior performance.

Claims

1. A solid electrolyte comprising Li and M α M β M γ Cl and Br, The solid electrolyte is characterized in that... M α To select at least one element from the group consisting of Zr and Hf, M β To select at least one element from the group consisting of Ta, Nb, and Mo, M γ It is to select at least one element from the group consisting of Gd, Yb, Dy, Er, Ho, Eu, Sc and Al.

2. The solid electrolyte according to claim 1, characterized in that, M α Including Zr.

3. The solid electrolyte according to claim 1 or 2, characterized in that, M β Including Ta.

4. The solid electrolyte according to claim 1 or 2, characterized in that, M γ It includes at least one element selected from the group consisting of Gd, Yb, and Er.

5. The solid electrolyte according to claim 1 or 2, characterized in that, Includes components expressed in the following formula: Li 6－（4＋a－b）（1＋c） (M α （1－a－b） M β a M γ b ) 1＋c Cl 6－2d－e－f O d F e Br f It satisfies 0 < a, 0 < b, a + b < 1, -0.2 ≤ c ≤ 0.2, 0 ≤ d < 3, 0 ≤ e < 6, and 0 < f < 6.

6. A lithium-ion battery comprising the solid electrolyte of claim 1 or 2.

Images