Solid electrolyte, preparation method thereof, solid-state battery and device

Abstract

The invention relates to a solid electrolyte and a preparation method thereof, a solid battery and a device, the general formula of the solid electrolyte is LiaMbX1cX26-c, M comprises at least one of Nb, Ta, W, Mo, Zr, Ti, Hf, Y, In, Yb, Sc, Fe, La and Sm, X1 and X2 are selected from two of F, Cl, Br and I, 0.6 < = a < = 3, 0.8 < = b < = 2, and 0.1 < = c < = 1. According to the solid electrolyte, the ion migration potential barrier is reduced, the ion conductivity is improved, the structural stability, the chemical stability and the interface compatibility are good, and the cycling stability is improved.

Description

Technical Field

[0001] The present application relates to the field of solid electrolyte technology, and in particular to a solid electrolyte and a preparation method thereof, a solid-state battery and a device. Background Art

[0002] As people's requirements for battery energy density continue to increase, in order to obtain excellent performance such as higher energy density and long cycle life, all-solid-state lithium batteries have come into being. All-solid-state lithium batteries use solid electrolytes instead of liquid electrolytes. At present, sulfide solid electrolytes and oxide solid electrolytes are two widely studied inorganic solid electrolytes, but neither of them can achieve the best balance between conductivity and stability. Halide-based solid electrolytes are regarded as one of the most promising solid electrolytes due to their good room temperature ionic conductivity, compatibility with high-voltage positive electrode materials, chemical stability and scalability. However, although some halide solid electrolytes have high conductivity and cycle stability, the overall level still needs to be improved. When facing the requirements of high-performance batteries, their conductivity and cycle stability still need to be further improved. Summary of the invention

[0003] Based on this, it is necessary to provide a solid electrolyte and a preparation method thereof, a solid-state battery and a device that can improve conductivity and cycle stability.

[0004] In one aspect of the present application, a solid electrolyte is provided, wherein the general formula of the solid electrolyte is Li a M b X1 c X2 6-c , wherein M includes at least one of Nb, Ta, W, Mo, Zr, Ti, Hf, Y, In, Yb, Sc, Fe, La and Sm, X1 and X2 are selected from two of F, Cl, Br and I, 0.6≤a≤3, 0.8≤b≤2, and 0.1≤c≤1.

[0005] The above-mentioned solid electrolyte forms a crystal structure with larger gaps and more regular ion transmission channels through the mutual coordination between specific metal M ions and lithium ions and dihalogen ions (two different halogen ions), thereby promoting ion migration, reducing the ion migration barrier, and improving ion conductivity; the above-mentioned solid electrolyte can improve the surface density, flatness and compaction density of the solid electrolyte through the coordination between specific metal M ions and lithium ions and dihalogen ions, thereby improving the structural stability, chemical stability and interface compatibility of the solid electrolyte, so that the interface stability between the halide solid electrolyte and the electrode is excellent, and the cycle stability is improved.

[0006] The above-mentioned solid electrolyte can still obtain high ionic conductivity and cycle stability when only a single transition metal cation is introduced, achieving unexpected results in improving the electrical properties of the solid electrolyte.

[0007] In some embodiments, M is at least one of In, Ta, Hf, Nb, Zr, Y, W and La.

[0008] In some embodiments, 1≤a≤3; and / or, 1≤b≤1.5; and / or, 0.2≤c≤1.

[0009] In some embodiments, the general formula of the solid electrolyte includes Li3InBr 0.6 Cl 5.4 , Li 1.2 La 0.4 Mo 0.6 F 0.4 Cl 5.6 、LiNbBr 0.2 Cl 5.8 , Li 1.3 Zr 0.8 Y 0.5 Cl 0.8 F 5.2 and LiW 0.3 Zr 0.5 La 0.4 I 0.6 Br 5.4 At least one of the .

[0010] The second aspect of the present application provides a method for preparing the solid electrolyte as described in the first aspect, comprising the following steps:

[0011] Mixing a Li source and a halide of M according to the stoichiometric molar ratio of the solid electrolyte under an inert atmosphere to prepare a mixed material;

[0012] The mixed material is subjected to solid phase sintering treatment to obtain the solid electrolyte.

[0013] In some embodiments, the Li source includes at least one of LiF, LiCl, LiBr and LiI.

[0014] In some embodiments, the halide of M includes at least one of fluoride of M, chloride of M, bromide of M and iodide of M.

[0015] In some embodiments, the mixing is performed by ball milling, and the ball milling satisfies at least one of the following conditions:

[0016] (1) The rotation speed of the ball milling treatment is 400 rpm to 900 rpm;

[0017] (2) The number of cycles of the ball milling treatment is 10 to 40 times;

[0018] (3) One cycle of the ball milling treatment comprises the following steps: rotating forward at a speed of 400 rpm to 900 rpm for 10 min to 20 min, then stopping for 5 min to 10 min, then rotating reversely at a speed of 400 rpm to 900 rpm for 10 min to 20 min, then stopping for 10-20 min;

[0019] (4) The ball milling medium used in the ball milling treatment is a zirconium dioxide ball with a particle size of 3 mm to 10 mm.

[0020] In some embodiments, the solid phase sintering process satisfies at least one of the following conditions:

[0021] (1) The atmosphere of the solid phase sintering process is an inert gas;

[0022] (2) The sintering temperature of the solid phase sintering treatment is 200° C. to 800° C.;

[0023] (3) The sintering time of the solid phase sintering treatment is 2h to 10h.

[0024] In some embodiments, before subjecting the mixed material to solid phase sintering treatment, the mixed material is also subjected to a step of cold pressing into sheets, the pressure of the cold pressing sheets is 100 MPa to 500 MPa; and / or the cold pressing time of the cold pressing sheets is 3 min to 5 min.

[0025] The third aspect of the present application provides a solid-state battery, comprising the solid-state electrolyte as described in the first aspect, or a solid-state electrolyte prepared by the preparation method of the solid-state electrolyte as described in the second aspect.

[0026] The fourth aspect of the present application provides an electrical device comprising the solid-state battery as described in the third aspect. DETAILED DESCRIPTION

[0027] For ease of understanding of the present application, the present application will be described more fully below with reference to the relevant embodiments, wherein preferred embodiments of the present application are provided. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0029] Lithium-ion batteries have the advantages of high energy density, low self-discharge and good cycle performance, and they do not have the memory effect problem of secondary battery systems such as nickel-cadmium, nickel-metal hydride, and lead-acid. Therefore, they are widely used in various fields such as portable electronic devices, electric vehicles, and power storage devices. Today's lithium-ion batteries generally use organic liquid electrolytes, including electrolyte lithium salts, high-purity organic solvents, and necessary additives. These substances have many safety issues, such as flammable and toxic solvents, poor thermal stability, and many side reactions at the electrode interface, which lead to heating, short circuits, and even explosions, thus posing safety hazards. With the continuous improvement of people's requirements for energy density, traditional lithium-ion batteries can no longer meet the needs of people's daily lives. All-solid-state lithium batteries use solid electrolytes instead of liquid electrolytes to obtain excellent performance such as high energy density and long cycle life. The current solid electrolytes mainly include oxide solid electrolytes, sulfide solid electrolytes, borate solid electrolytes, and halogen solid electrolytes. Among them, halogen solid electrolytes show higher ionic conductivity, but the overall level still needs to be improved. When facing the requirements of high-performance batteries, their conductivity and cycle stability still need to be further improved.

[0030] Based on this, an embodiment of the first aspect of the present application provides a solid electrolyte, the general formula of the solid electrolyte is Li a M b X1 c X2 6-c , wherein M includes at least one of Nb, Ta, W, Mo, Zr, Ti, Hf, Y, In, Yb, Sc, Fe, La and Sm, X1 and X2 are selected from two of F, Cl, Br and I, 0.6≤a≤3, 0.8≤b≤2, and 0.1≤c≤1.

[0031] The above-mentioned solid electrolyte forms a crystal structure with larger gaps and more regular ion transmission channels through the mutual coordination between specific metal M ions and lithium ions and dihalogen ions (two different halogen ions), thereby promoting ion migration, reducing the ion migration barrier, and improving ion conductivity; the above-mentioned solid electrolyte can improve the surface density, flatness and compaction density of the solid electrolyte through the coordination between specific metal M ions and lithium ions and dihalogen ions, thereby improving the structural stability, chemical stability and interface compatibility of the solid electrolyte, so that the interface stability between the halide solid electrolyte and the electrode is excellent, and the cycle stability is improved.

[0032] The above-mentioned solid electrolyte can still obtain high ionic conductivity and cycle stability when only a single transition metal cation is introduced, achieving unexpected results in improving the performance of the solid electrolyte.

[0033] As an example, a can be 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 and 3.0, or can be in a range consisting of any two of the above values ​​as end values. Preferably, 1≤a≤3.

[0034] As an example, b can be 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 and 2.0, or can be within a range consisting of any two of the above values ​​as end values. Preferably, 1≤b≤1.5.

[0035] As an example, c can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0, or can be within a range consisting of any two of the above values ​​as end values. Preferably, 0.2≤c≤1.

[0036] In some embodiments, Y, In, Yb, Sc, Fe, La and Sm are all +3 valence; Zr, Ti and Hf are all +4 valence; Nb and Ta are all +5 valence; W and Mo are all +6 valence; F, Cl, Br and I are all -1 valence.

[0037] In some embodiments, 1≤a≤3, 1≤b≤1.5, 0.2≤c≤1. Within this value range, the ion migration barrier is further reduced and the ion conductivity is improved.

[0038] In some embodiments, M is at least one of In, Ta, Hf, Nb, Zr, Y, W and La. When M is the aforementioned transition metal cation, the solid electrolyte not only has high ion conductivity and good cycle stability, but also has excellent formability and high-voltage stability.

[0039] In some embodiments, M is at least one of Nb, Zr, Y, W and La. When M is the aforementioned transition metal cation, the cycle capacity retention rate of the solid electrolyte is high.

[0040] In some embodiments, X1 and X2 are selected from two of F, Cl, Br and I.

[0041] In some embodiments, X1 is Br, X2 is Cl, and 0.2≤c≤1. The surface density, ionic conductivity and capacity retention of the solid electrolyte are further improved by the coordination among the metal M ions, lithium ions, Br ions and Cl ions.

[0042] In some embodiments, X1 is F, X2 is Cl, and 0.2≤c≤1. The coordination of fluoride ions and chloride ions helps to enhance the stability of the solid electrolyte interface and inhibit side reactions, especially maintaining good cycle stability during long-term use. The coordination between metal M ions, lithium ions, Cl ions and F ions further improves the surface density, ionic conductivity and capacity retention of the solid electrolyte.

[0043] In some embodiments, the general formula of the solid electrolyte includes Li3InBr 0.6 Cl 5.4 , Li 1.2 La 0.4 Mo 0.6 F 0.4 Cl 5.6 、LiNbBr 0.2 Cl 5.8 , Li 1.3 Zr 0.8 Y 0.5 Cl 0.8 F 5.2 and LiW 0.3 Zr 0.5 La 0.4 I 0.6 Br 5.4 At least one of the .

[0044] The second aspect of the present application provides a method for preparing the solid electrolyte described in the first aspect, comprising the following steps:

[0045] Mixing a Li source and a halide of M according to the stoichiometric molar ratio of the solid electrolyte under an inert atmosphere to prepare a mixed material;

[0046] The mixed material is cold pressed into sheets and then subjected to solid phase sintering treatment to obtain the solid electrolyte.

[0047] The above preparation method combines mechanical ball milling and high-temperature sintering methods to make the surface of the prepared solid electrolyte dense, with high flatness and compaction density, which can promote ion transmission and thus better inhibit the growth of dendrites; the above preparation method also has the advantages of simple operation and safety and environmental protection.

[0048] In some embodiments, the Li source is a lithium halide.

[0049] In some embodiments, the Li source includes at least one of LiF, LiCl, LiBr and LiI.

[0050] In some embodiments, the halide of M includes at least one of fluoride of M, chloride of M, bromide of M and iodide of M.

[0051] In some embodiments, the mixing is performed by ball milling.

[0052] In some embodiments, the ball milling process uses a planetary ball mill.

[0053] In some embodiments, the ball milling process has a rotation speed of 400 rpm to 900 rpm.

[0054] In some embodiments, the ball milling process is performed for 10 to 40 cycles.

[0055] In some embodiments, one cycle of the ball milling treatment includes the following steps: forward rotation at a speed of 400 rpm to 900 rpm for 10 min to 20 min, then stop rotation for 5 min to 10 min, then reverse rotation at a speed of 400 rpm to 900 rpm for 10 min to 20 min, then stop rotation for 10 min to 20 min. This ball milling treatment improves the surface properties of the solid electrolyte, thereby improving the interface stability between the solid electrolyte and the electrode material.

[0056] In some embodiments, the ball milling medium used in the ball milling treatment is a zirconium dioxide ball with a particle size of 3 mm to 10 mm.

[0057] In some embodiments, the mass ratio of the ball powder after ball milling is (10-40):1.

[0058] It can be understood that the ball powder mass ratio is the mass ratio of the zirconium dioxide balls to the solid electrolyte mass raw materials (Li source and M halide).

[0059] In some embodiments, the ball milling medium includes zirconium dioxide balls with four different particle sizes of 3 mm, 5 mm, 8 mm and 10 mm, and the mass ratio of 3 mm, 5 mm, 8 mm and 10 mm zirconium dioxide balls is 4:3:2:1, and the ball powder mass ratio is (10-40): 1. The ball milling effect of the ball milling medium with the above graded distribution is good, which improves the texture and uniformity of the solid electrolyte.

[0060] In some embodiments, the atmosphere of the solid phase sintering process is an inert gas.

[0061] In some embodiments, the sintering temperature of the solid phase sintering treatment is 200° C. to 800° C. The sintering temperature of the solid phase sintering treatment is preferably 250° C. to 350° C. The sintering treatment further improves the surface properties of the solid electrolyte, thereby further improving the interface stability between the solid electrolyte and the electrode material.

[0062] In some embodiments, the sintering time of the solid phase sintering process is 2 hours to 10 hours, preferably 4 hours to 10 hours.

[0063] In some embodiments, before subjecting the mixed material to solid phase sintering, the process further includes subjecting the mixed material to cold pressing and tableting.

[0064] In some embodiments, the pressure of the cold-pressed tablet is 100 MPa to 500 MPa.

[0065] In some embodiments, the cold pressing time of the cold pressed tablet is 3 min to 5 min.

[0066] In some embodiments, before subjecting the mixed material to solid phase sintering treatment, the mixed material is also subjected to a step of cold pressing into sheets, the pressure of the cold pressing sheets is 100 MPa to 500 MPa; and / or the cold pressing time of the cold pressing sheets is 3 min to 5 min.

[0067] The third aspect of the present application provides a solid-state battery, comprising the solid-state electrolyte as described in the first aspect, or a solid-state electrolyte prepared by the preparation method of the solid-state electrolyte as described in the second aspect.

[0068] In some embodiments, a solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode.

[0069] In some embodiments, the positive electrode of the solid-state battery includes a positive electrode active layer, and the positive electrode active layer includes a positive electrode active material and the above-mentioned solid electrolyte.

[0070] Understandably, incorporating a solid electrolyte into the positive electrode allows for better ion transport within it.

[0071] Further, in the positive electrode active layer, the mass content of the positive electrode active material is 50%-80%, and the mass content of the above-mentioned solid electrolyte is 20%-50%. Further, the positive electrode active material includes but is not limited to lithium nickel cobalt manganese oxide, such as NCM111. Further, in the positive electrode active layer, the mass content of the positive electrode active material is 80%, and the mass content of the above-mentioned solid electrolyte is 20%.

[0072] In some examples, a composite positive electrode is used, wherein the composite positive electrode is prepared by weighing the aforementioned solid electrolyte and NCM111 (lithium nickel cobalt manganese oxide) in a mass ratio of 8:2 and then grinding them in a mortar.

[0073] In some embodiments, the negative electrode of the solid-state battery uses a lithium-indium alloy.

[0074] In some embodiments, a solid electrolyte layer is disposed between the positive electrode and the negative electrode of the solid-state battery, and the material of the solid electrolyte layer includes Li 5.4 PS 4.4 Cl 1.6 The interlayer is used to prevent the solid electrolyte from reacting with the negative electrode.

[0075] The fourth aspect of the present application provides an electrical device comprising the solid-state battery as described in the third aspect.

[0076] Electrical devices include, but are not limited to, electronic products, drones, robots, electric vehicles, watches, wireless headphones, digital products, smart cards, medical devices, and energy storage devices.

[0077] The following are specific embodiments.

[0078] Example 1

[0079] Preparation of Lithium Ion Halide Solid Electrolyte Li3InBr 0.6 Cl 5.4 , the specific preparation steps are as follows:

[0080] (1) Weigh 2 g of the raw materials LiCl, LiBr, and InCl3 according to the stoichiometric molar ratio of 2.4:0.6:1.0, pour them into a mortar and grind them into a uniform mixture;

[0081] (2) Then pour the mixed raw materials into a 100 mL ball mill, and put a total of 120 g of ZrO2 balls with particle sizes of 3 mm (48 g), 5 mm (36 g), 8 mm (24 g), and 10 mm (12 g) into the jar, with a ball-to-powder mass ratio of 40:1;

[0082] (3) Ball milling was performed on a planetary ball mill, with high-speed ball milling (700 rpm) running forward for 20 min, stopping to cool for 5 min, counter-milling for 20 min, stopping to cool for 5 min, and repeating 16 times to complete the ball milling process;

[0083] (4) The ball mill is transferred to a glove box, and the powder after ball milling is poured into a mortar for grinding. The ground material is cold pressed at 100 MPa for 2 min. The solid electrolyte sheet is placed in a quartz boat, placed in a high-temperature furnace, sintered at 300 ° C for 5 h, and then cooled to room temperature;

[0084] (5) The sintered material was moved to a glove box, ground with a mortar, and placed in a bottle to obtain the solid electrolyte Li3InBr 0.6 Cl 5.4 .

[0085] Example 2

[0086] Preparation of Li-ion Halide Solid Electrolyte Li 1.2 La 0.4 Mo 0.6 F 0.4 Cl 5.6 .

[0087] The preparation steps of Example 2 are basically the same as those of Example 1, except that: the raw materials LiCl, LaCl3, MoCl6, and LiF are weighed according to a stoichiometric ratio of 0.8:0.4:0.6:0.4, totaling 2 g, poured into a mortar and ground and mixed evenly; high-speed ball milling is performed at 650 rpm for 35 times, and then sintered at 300°C for 10 hours, and then cooled to room temperature.

[0088] Example 3

[0089] Preparation of Lithium-ion Halide Solid Electrolyte LiNbBr 0.2 Cl 5.8 .

[0090] The preparation steps of Example 3 are basically the same as those of Example 1, except that: the raw materials LiCl, NbCl5, and LiBr are weighed according to a stoichiometric molar ratio of 0.8:1:0.2, totaling 2 g, poured into a mortar and ground and mixed evenly; high-speed ball milling is performed at 600 rpm for 28 times, and then sintered at 280°C for 8 hours, and then cooled to room temperature.

[0091] Example 4

[0092] Preparation of Li-ion Halide Solid Electrolyte Li 1.3 Zr 0.8 Y 0.5 Cl 0.8 F 5.2 .

[0093] The preparation steps of Example 4 and Example 1 are basically the same, except that the raw materials LiCl, ZrCl4, YCl3, and LiF are weighed according to the stoichiometric molar ratio of 0.8:0.8:0.5:0.5, totaling 2 g, poured into a mortar and ground and mixed evenly, high-speed ball milled at 650 rpm for 35 times, then sintered at 350°C for 6 h, and then cooled to room temperature.

[0094] Example 5

[0095] Preparation of Lithium-ion Halide Solid Electrolyte LiW 0.3Zr 0.5 La 0.4 I 0.6 Br 5.4 .

[0096] The preparation steps of Example 5 and Example 1 are basically the same, except that the raw materials LiBr, WCl6, ZrCl4, LaCl3, and LiI are weighed in a stoichiometric molar ratio of 1:0.3:0.5:0.4:0.6, totaling 2 g, poured into a mortar and ground and mixed evenly, high-speed ball milled 40 times at 800 rpm, high-speed ball milled 40 times at 650 rpm, and then sintered at 270°C for 4 hours and cooled to room temperature.

[0097] Comparative Example 1

[0098] Comparative Example 1 is basically the same as Example 1, except that LiCl and InCl3 are weighed as raw materials in a molar ratio of 3:1 to prepare a halide solid electrolyte Li3InCl6.

[0099] Comparative Example 2

[0100] Comparative Example 2 is substantially the same as Example 1, except that LiCl, HfCl4 and TaCl5 are weighed in a molar ratio of 1.25:0.25:0.75 to prepare a halide solid electrolyte Li 1.25 Hf 0.25 Ta 0.75 Cl6.

[0101] The lithium ion halide solid electrolytes prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were assembled into all-solid-state lithium batteries for electrical performance testing. The test results are shown in Table 1 below.

[0102] The steps for assembling an all-solid-state lithium battery are as follows: the prepared lithium ion halide solid electrolyte and NCM111 are weighed in a ratio of 8:2, ground in a mortar, and put into a bottle as a composite positive electrode in the all-solid-state battery. The negative electrode uses a lithium-indium alloy. To prevent the electrolyte from reacting with the negative electrode, a solid electrolyte layer Li is added in the middle. 5.4 PS 4.4 Cl 1.6 .

[0103] The ionic conductivity test steps are as follows:

[0104] (1) Weigh 80 mg of lithium ion halide solid electrolyte and pour it into a PEEK mold with an inner diameter of 10 mm;

[0105] (2) Then put it under a hydraulic press, keep the pressure at 150MPa for 5 minutes, press it into a sheet, and perform AC impedance spectrum test under pressure to draw the AC impedance spectrum of lithium ion halide solid electrolyte at 30℃~80℃. Calculate the ionic conductivity according to the following formula:

[0106]

[0107] σ is the ionic conductivity, in S / cm; L is the thickness of the solid electrolyte after pressing, in cm; R is the impedance of the solid electrolyte being tested, in ohm; S is the effective area of ​​the electrode contact, in cm 2 .

[0108] The test conditions for discharge specific capacity and capacity retention rate are as follows:

[0109] At 100mA g -1 The initial discharge specific capacity, discharge specific capacity after 40 cycles and capacity retention rate were tested at a current density of .

[0110] Table 1

[0111]

[0112] As can be seen from Table 1 above, the double halogen combination helps to broaden the ion transport channel of the solid electrolyte through the interaction of ion size differences. This structural optimization allows ions to move more smoothly, thereby improving the conductivity, such as: Example 2 (Li 1.2 La 0.4 Mo 0.6 F 0.4 Cl 5.6 ) has an ionic conductivity of 2.1 mS / cm, which is much higher than the 1.5 mS / cm performance of the single halogen comparison sample in Comparative Example 1. In addition, the fluoride ion (F - ) and chloride ions (Cl - ) helps to enhance the stability of the solid electrolyte interface and inhibit side reactions, especially maintaining good cycle stability during long-term use, such as: Example 4 (Li 1.3 Zr 0.8 Y 0.5 Cl 0.8 F 5.2 ) showed a capacity retention rate of up to 95%, which is much better than the 81% of single halogen. - ) and bromide ion (Br - ) The capacity retention rate is as high as 93%, and excellent cycle performance is obtained. In addition, with the appropriate halogen ratio, when 0.2≤c≤1, the capacity retention rate can be improved while further improving the conductivity, taking into account both high capacity and long cycle life. Example 3 (LiNbBr0.2 Cl 5.8 ) and Example 4 (Li 1.3 Zr 0.8 Y 0.5 Cl 0.8 F 5.2 ) embodies this point well, with outstanding performance in both ionic conductivity and capacity retention, making it suitable for higher performance battery applications.

[0113] Compared with single halogen electrolytes, dual halogen electrolytes have obvious advantages in performance, especially in improving ionic conductivity, optimizing cycle stability and extending battery life.

[0114] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0115] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A solid electrolyte, characterized in that The general formula of the solid electrolyte is Li a M b X1 c X2 6-c , wherein M includes at least one of Nb, Ta, W, Mo, Zr, Ti, Hf, Y, In, Yb, Sc, Fe, La and Sm, X1 and X2 are selected from two of F, Cl, Br and I, 0.6≤a≤3, 0.8≤b≤2, and 0.1≤c≤1.

2. The solid electrolyte according to claim 1, characterized in that The M is at least one of In, Ta, Hf, Nb, Zr, Y, W and La.

3. The solid electrolyte according to any one of claims 1 to 2, characterized in that 1≤a≤3; and / or, 1≤b≤1.5; and / or, 0.2≤c≤1.

4. The solid electrolyte according to any one of claims 1 to 2, characterized in that The general formula of the solid electrolyte includes Li3InBr 0.6 Cl 5.4 , Li 1.2 La 0.4 Mo 0.6 F 0.4 Cl 5.6 、LiNbBr 0.2 Cl 5.8 , Li 1.3 Zr 0.8 Y 0.5 Cl 0.8 F 5.2 and LiW 0.3 Zr 0.5 La 0.4 I 0.6 Br 5.4 At least one of the .

5. The method for preparing a solid electrolyte according to any one of claims 1 to 4, characterized in that: The following steps are involved: Mixing a Li source and a halide of M according to the stoichiometric molar ratio of the solid electrolyte under an inert atmosphere to prepare a mixed material; The mixed material is subjected to solid phase sintering treatment to obtain the solid electrolyte.

6. The method for preparing a solid electrolyte according to claim 5, characterized in that: The Li source includes at least one of LiF, LiCl, LiBr and LiI.

7. The method for preparing a solid electrolyte according to claim 5, characterized in that: The halide of M includes at least one of fluoride of M, chloride of M, bromide of M and iodide of M.

8. The method for preparing a solid electrolyte according to any one of claims 5 to 7, characterized in that: The mixing is performed by ball milling, and the ball milling satisfies at least one of the following conditions: (1) The rotation speed of the ball milling treatment is 400 rpm to 900 rpm; (2) The number of cycles of the ball milling treatment is 10 to 40 times; (3) One cycle of the ball milling treatment comprises the following steps: rotating forward at a speed of 400 rpm to 900 rpm for 10 to 20 minutes, then stopping for 5 to 10 minutes, then rotating reversely at a speed of 400 rpm to 900 rpm for 10 to 20 minutes, then stopping for 10 to 20 minutes; (4) The ball milling medium used in the ball milling treatment is a zirconium dioxide ball with a particle size of 3 mm to 10 mm.

9. The method for preparing a solid electrolyte according to any one of claims 5 to 7, characterized in that: The solid phase sintering process satisfies at least one of the following conditions: (1) The atmosphere of the solid phase sintering process is an inert gas; (2) The sintering temperature of the solid phase sintering treatment is 200° C. to 800° C.; (3) The sintering time of the solid phase sintering treatment is 2h to 10h.

10. The method for preparing a solid electrolyte according to any one of claims 5 to 7, characterized in that: Before subjecting the mixed material to solid phase sintering, the mixed material is also subjected to a step of cold pressing to form a sheet, wherein the pressure of the cold pressing sheet is 100 MPa to 500 MPa; and / or the cold pressing time of the cold pressing sheet is 3 min to 5 min.

11. A solid-state battery, characterized in that: A solid electrolyte comprising the solid electrolyte as claimed in any one of claims 1 to 4, or a solid electrolyte prepared by the preparation method of the solid electrolyte as claimed in any one of claims 5 to 10.

12. An electrical device, characterized in that: Comprising the solid-state battery as claimed in claim 11.

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