Solid-state electrolyte and method for preparing the same

Abstract

This application discloses a solid electrolyte and its preparation method, wherein the solid electrolyte is Li. 1+x‑2y Al x Ti 2‑x‑y M y (PO 4‑ z F 2z )3, where 0.3≤x≤0.5, 0.004<y<0.02, 0<z≤0.01; where M is a metallic element with a valence greater than +4. The solid electrolyte Li provided in this application... 1+x‑2y Al x Ti 2‑x‑y M y (PO 4‑ z F 2z )3. By doping lithium titanium aluminum phosphate with a high-valence metal element M, the ionic conductivity of the solid electrolyte was improved, while the water content of the solid electrolyte was reduced.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a solid electrolyte and its preparation method. Background Technology

[0002] Currently, lithium-ion batteries play a crucial role in the modern energy field, experiencing rapid growth and achieving great success in power, consumer, and energy storage applications. However, traditional lithium-ion battery systems all use liquid, flammable organic electrolytes, posing safety risks such as leakage and flammability. Furthermore, with the rapidly increasing demand for higher battery energy density, current lithium-ion battery systems have reached a bottleneck, limiting their further application in various fields. To fundamentally solve safety issues and overcome energy density limitations, the development of solid-state batteries has become a key area of ​​competition among numerous battery-related companies both domestically and internationally, and has become the most promising next-generation battery technology.

[0003] In recent years, lithium titanium aluminum phosphate, as an inorganic solid electrolyte material with high lithium-ion conductivity, has become a research hotspot and attracted widespread attention due to its excellent stability, high ionic conductivity, and high electrochemical oxidation potential, making it a promising candidate for solid-state batteries. The ionic conductivity of solid-state electrolytes is a crucial indicator limiting their commercialization, making the development of solid-state electrolyte materials with high ionic conductivity a key research focus. Meanwhile, in the manufacturing process of lithium-ion batteries, the moisture content of raw materials is a critical criterion that requires strict control. Therefore, effectively reducing the moisture content of solid-state electrolytes is particularly important to ensure their full utilization. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this application is to provide a solid electrolyte and its preparation method, which solves the problems of insufficient ionic conductivity and high water content in existing solid electrolytes.

[0005] To achieve one or more of the above objectives or other objectives, the first aspect of this application provides a solid electrolyte, wherein the solid electrolyte is Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where 0.3≤x≤0.5, 0.004<y<0.02, 0<z≤0.01; where M is a metallic element with a valence greater than +4.

[0006] Furthermore, M is a metallic element with a valence state of +6; preferably, M is selected from one or more of tungsten, molybdenum, and chromium.

[0007] Furthermore, when 0.004 < y ≤ 0.01, 0.005 ≤ z ≤ 0.01; when 0.01 < y < 0.02, 0 < z < 0.005.

[0008] A second aspect of this application provides a method for preparing a solid electrolyte, the method comprising:

[0009] The raw materials are mixed to obtain a mixed material, wherein the raw materials include pretreated solid electrolyte powder and fluoride; wherein the pretreated solid electrolyte contains lithium, aluminum, titanium, M, phosphorus and oxygen, and M is a metal element with a valence greater than +4; the molar ratio of lithium, aluminum, titanium, M and phosphorus is (1+x-2y):x:(2-xy):y:3, and 0.3≤x≤0.5, 0.004<y<0.02;

[0010] The mixed material was subjected to a fluorine substitution reaction under preset temperature conditions to prepare the solid electrolyte Li. 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where 0.3≤x≤0.5, 0.004<y<0.02, 0<z≤0.01.

[0011] Furthermore, M is a metallic element with a valence state of +6; preferably, M is selected from one or more of tungsten, molybdenum, and chromium.

[0012] Furthermore, the fluoride includes at least one of lithium fluoride and ammonium fluoride.

[0013] Furthermore, prior to the step of mixing the raw materials, the method further includes:

[0014] Phosphoric acid, lithium source, aluminum source, titanium source, M-containing compound, and water are mixed and stirred to obtain a mixed slurry; wherein, the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are adjusted according to the molar ratio of lithium, aluminum, titanium, M, and phosphorus as (1+x-2y):x:(2-xy):y:3, where 0.3≤x≤0.5, 0.004<y<0.02;

[0015] The mixed slurry is dried to obtain the precursor material;

[0016] The precursor material is pre-sintered to obtain a pretreated solid electrolyte;

[0017] The pretreated solid electrolyte is crushed and sieved to obtain the pretreated solid electrolyte powder.

[0018] Further, the M-containing compound includes at least one of lithium tungstate, ammonium tungstate, ammonium metatungstate, ammonium paratungstate, lithium molybdate, ammonium orthomolybdate, ammonium paramolybdate, ammonium dimolybdate, ammonium tetramolybdate, ammonium molybdate tetrahydrate, ammonium heptamolybdate, lithium chromate, and ammonium dichromate; the lithium source includes at least one of lithium carbonate and lithium hydroxide; the aluminum source includes at least one of aluminum oxide and aluminum hydroxide; and the titanium source includes at least one of titanium dioxide and titanate.

[0019] Furthermore, in the step of drying the mixed slurry, the drying temperature range is 120℃~200℃, and the drying time is 1h~3h; in the step of pre-sintering the precursor material, the pre-sintering temperature range is 600℃~800℃, and the pre-sintering time is 1h~3h.

[0020] Further, the step of carrying out a fluorine substitution reaction on the mixed material under a preset temperature condition includes:

[0021] The mixed materials are ball-milled to obtain a mixed powder.

[0022] The mixed powder is calcined at a temperature greater than or equal to 700°C and less than 1000°C, and the calcination temperature is greater than the pre-sintering temperature. The calcination time is 3h to 10h to obtain the solid electrolyte.

[0023] The solid electrolyte Li provided in this application 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z 3. By doping lithium titanium aluminum phosphate with a high-valence metal element M, its microcrystalline structure is altered, lithium vacancy defects are created, and the migration and conduction speed of lithium ions are improved, thereby increasing the ionic conductivity of lithium titanium aluminum phosphate. Doping with the high-valence metal element M not only changes the microcrystalline structure of lithium titanium aluminum phosphate but also introduces additional active substitution sites on the surface of lithium titanium aluminum phosphate. This allows more oxygen ions on the surface of the doped lithium titanium aluminum phosphate to be replaced by fluoride ions, meaning that fluoride ions are more easily enriched on the surface of the material particles. This effectively modifies the irregular surface of the solid electrolyte particles, making the crystal form of the solid electrolyte more regular and significantly reducing the surface energy, thus reducing water absorption and facilitating the reduction of water content in the solid electrolyte material, allowing it to exist stably in a low-water-content state. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] in:

[0026] Figure 1 XRD comparison diagrams of solid electrolytes from Comparative Example 1, Comparative Example 5, and Example 1;

[0027] Figure 2 (a) is an EDS photograph of the solid electrolyte of Comparative Example 5; Figure 2 (b) is an EDS photograph of the solid electrolyte of Example 1. Detailed Implementation

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0031] This application provides a solid electrolyte, wherein the solid electrolyte is Li. 1+x-2y Al x Ti 2-x-y M y (PO 4- z F 2z)3, where 0.3≤x≤0.5, 0.004<y<0.02, 0<z≤0.01; where M is a metallic element with a valence greater than +4.

[0032] The solid electrolyte Li provided in this embodiment 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z 3. By doping lithium titanium aluminum phosphate with a high-valence metal element M, its microcrystalline structure is altered, lithium vacancy defects are created, and the migration and conduction speed of lithium ions are improved, thereby increasing the ionic conductivity of lithium titanium aluminum phosphate. Doping with the high-valence metal element M not only changes the microcrystalline structure of lithium titanium aluminum phosphate but also introduces additional active substitution sites on the surface of lithium titanium aluminum phosphate. This allows more oxygen ions on the surface of the doped lithium titanium aluminum phosphate to be replaced by fluoride ions, meaning that fluoride ions are more easily enriched on the surface of the material particles. This effectively modifies the irregular surface of the solid electrolyte particles, making the crystal form of the solid electrolyte more regular and significantly reducing the surface energy, thus reducing water absorption and facilitating the reduction of water content in the solid electrolyte material, allowing it to exist stably in a low-water-content state. The value of x can be exemplarily 0.3, 0.4, 0.5, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable. The values ​​of y can be, for example, 0.005, 0.008, 0.01, 0.015, 0.018, 0.019, etc., but are not limited to the listed values; other unlisted values ​​within this range also apply. The values ​​of z can be, for example, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, etc., but are not limited to the listed values; other unlisted values ​​within this range also apply.

[0033] In one specific embodiment, M is a metallic element with a valence state of +6; preferably, M is selected from one or more of tungsten, molybdenum, and chromium.

[0034] In one specific embodiment, when 0.004 < y ≤ 0.01, 0.005 ≤ z ≤ 0.01; when 0.01 < y < 0.02, 0 < z < 0.005.

[0035] The higher the doping concentration of the high-valence metal element M (i.e., the larger the value of y), the greater the substitution amount of F (i.e., the larger the value of z). The high-valence metal ion M introduces additional active substitution sites on the surface of lithium titanium aluminum phosphate. These sites have higher reactivity, which is beneficial for the adsorption and substitution of fluoride ions. Simultaneously, the interaction between the high-valence metal ion and oxygen ions alters the electron cloud distribution of oxygen ions. Fluoride ions, with their strong electronegativity, can more easily undergo substitution reactions with oxygen ions at the active substitution sites.

[0036] This application also provides a method for preparing a solid electrolyte, used to prepare the solid electrolyte of the aforementioned embodiments, the preparation method comprising:

[0037] S1. The raw materials are mixed to obtain a mixed material, wherein the raw materials include pretreated solid electrolyte powder and fluoride; wherein the pretreated solid electrolyte contains lithium, aluminum, titanium, M, phosphorus and oxygen, and M is a metal element with a valence greater than +4; the molar ratio of lithium, aluminum, titanium, M and phosphorus is (1+x-2y):x:(2-xy):y:3, and 0.3≤x≤0.5, 0.004<y<0.02;

[0038] S2. The mixed material is subjected to a fluorine substitution reaction under a preset temperature condition to prepare the solid electrolyte Li. 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where 0.3≤x≤0.5, 0.004<y<0.02, 0<z≤0.01.

[0039] In this embodiment, in step S1 above, the pretreated solid electrolyte powder can be Li with a preliminary doped crystal phase structure. 1+x-2y Al x Ti 2-x-y M y (PO4)3, or Li that has already formed a stable crystal structure. 1+x-2y Al x Ti 2-x-y M y (PO4)3.

[0040] In one specific embodiment, M is a metallic element with a valence state of +6; preferably, M is selected from one or more of tungsten, molybdenum, and chromium. In one specific embodiment, the fluoride includes at least one of lithium fluoride and ammonium fluoride. Lithium fluoride and ammonium fluoride are used as fluorine sources for the fluorine substitution reaction.

[0041] In step S2 above, fluoride ions replace some of the oxygen ions during the reaction, forming the solid electrolyte Li. 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z 3. The value of z depends on the extent of the fluorine substitution reaction. In one specific embodiment, when 0.004 < y ≤ 0.01, 0.005 ≤ z ≤ 0.01; when 0.01 < y < 0.02, 0 < z < 0.005.

[0042] The solid electrolyte Li prepared by the method in this embodiment 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z 3. By doping lithium titanium aluminum phosphate with a high-valence metal element M, its microcrystalline structure is altered, lithium vacancy defects are created, and the migration and conduction speed of lithium ions are improved, thereby increasing the ionic conductivity of lithium titanium aluminum phosphate. Doping with the high-valence metal element M not only changes the microcrystalline structure of lithium titanium aluminum phosphate but also introduces additional active substitution sites on the surface of lithium titanium aluminum phosphate. This allows more oxygen ions on the surface of the doped lithium titanium aluminum phosphate to be replaced by fluoride ions, meaning that fluoride ions are more easily enriched on the surface of the material particles. This effectively modifies the irregular surface of the solid electrolyte particles, making the crystal form of the solid electrolyte more regular and significantly reducing the surface energy, thus reducing water absorption and facilitating the reduction of water content in the solid electrolyte material, allowing it to exist stably in a low-water-content state.

[0043] In one specific embodiment, before step S1 of mixing the raw materials, the method further includes:

[0044] S01. Phosphoric acid, lithium source, aluminum source, titanium source, M-containing compound and water are mixed and stirred to obtain a mixed slurry; wherein, the amounts of lithium source, aluminum source, titanium source, M-containing compound and phosphoric acid are adjusted according to the molar ratio of lithium, aluminum, titanium, M and phosphorus as (1+x-2y):x:(2-xy):y:3, where 0.3≤x≤0.5, 0.004<y<0.02;

[0045] S02. Dry the mixed slurry to obtain the precursor material;

[0046] S03. The precursor material is pre-sintered to obtain a pretreated solid electrolyte.

[0047] S04. The pretreated solid electrolyte is crushed and sieved to obtain the pretreated solid electrolyte powder.

[0048] In this embodiment, the pretreated solid electrolyte powder prepared by steps S01-S04 is Li with a preliminary doped crystal phase structure. 1+x-2y Al x Ti 2-x-y M y (PO4)3 has not yet formed a stable crystal structure, which is conducive to the subsequent fluorine substitution in step S2.

[0049] Specifically, in step S01 above, the compound containing M includes at least one of lithium tungstate, ammonium tungstate, ammonium metatungstate, ammonium paratungstate, lithium molybdate, ammonium orthomolybdate, ammonium paramolybdate, ammonium dimolybdate, ammonium tetramolybdate, ammonium molybdate tetrahydrate, ammonium heptamolybdate, lithium chromate, and ammonium dichromate; the lithium source includes at least one of lithium carbonate and lithium hydroxide; the aluminum source includes at least one of alumina and aluminum hydroxide; and the titanium source includes at least one of titanium dioxide and titanate. The phosphoric acid is 85-90 wt% concentrated phosphoric acid. The water content is not specifically limited, as long as it can achieve sufficient and uniform mixing of phosphoric acid, lithium source, aluminum source, titanium source, and the compound containing M. Those skilled in the art can adaptively adjust the water content according to the specific operating scenario. This application also does not specifically limit the stirring time and speed, which can be adjusted according to the specific situation to ensure sufficient mixing of the raw materials.

[0050] Specifically, in step S02 of drying the mixed slurry, the drying temperature range is 120℃~200℃, and the drying time is 1h~3h. The mixed slurry is placed in a drying device for drying treatment to remove moisture from the mixed slurry and obtain a dried precursor material. The drying temperature can be, for example, 120℃, 140℃, 160℃, 180℃, 200℃, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable. The drying time can be, for example, 1h, 1.5h, 2h, 2.5h, 3h, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0051] Specifically, in step S03, which involves pre-sintering the precursor material, the pre-sintering temperature range is 600℃ to 800℃, and the pre-sintering time is 1h to 3h. The precursor material is placed in a sintering furnace for pre-sintering. Pre-sintering allows the raw materials in the precursor material to undergo a preliminary chemical reaction, forming a pretreated solid electrolyte with a preliminary doped crystal phase structure and composition. At this stage, a stable crystal structure has not yet formed, facilitating the subsequent fluorine substitution reaction. The pre-sintering temperature can be, for example, 600℃, 650℃, 700℃, 750℃, 800℃, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable. The pre-sintering time can be, for example, 1h, 1.5h, 2h, 2.5h, 3h, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0052] In step S04 above, the pretreated solid electrolyte obtained by pre-sintering is crushed and sieved to form particles of uniform size for subsequent mixing with other materials. This step does not impose special restrictions on particle size; it simply aims to initially homogenize the irregularly shaped pretreated solid electrolyte formed after pre-sintering.

[0053] In one specific embodiment, step S2, which involves subjecting the mixed material to a fluorine substitution reaction at a preset temperature, includes:

[0054] S21. The mixed material is ball-milled to obtain a mixed powder;

[0055] S22. The mixed powder is calcined at a temperature greater than or equal to 700°C and less than 1000°C, and the calcination temperature is greater than the pre-sintering temperature. The calcination time is 3h to 10h to obtain the solid electrolyte.

[0056] In this embodiment, in step S21 above, the mixed material is placed in a ball mill, and an appropriate amount of grinding balls and an optional dispersant are added for ball milling. The ball milling speed, time, and the material and size of the grinding balls can be selected by those skilled in the art based on the properties of the mixed material and the required powder particle size. Ball milling refines the particles in the mixed material, improves the mixing uniformity, and facilitates the subsequent calcination reaction.

[0057] In step S22 above, the mixed powder obtained by ball milling is placed in a sintering furnace and heated at 700°C.

[0058] Calcination is performed within a temperature range of ~1000℃ (excluding 1000℃). During calcination at higher temperatures, the fluoride decomposes and undergoes a substitution reaction with oxygen ions in the pretreated solid electrolyte powder to form the aforementioned solid electrolyte. Exemplary calcination temperatures can be 700℃, 800℃, 900℃, 950℃, etc., but are not limited to the listed values; other unlisted values ​​within this range are also applicable. In specific implementations, the calcination temperature setting must also be higher than the pre-sintering temperature setting. Exemplary calcination times can be 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, etc., but are not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0059] The preparation method in this embodiment can be used to prepare a solid electrolyte that has both high ionic conductivity and low water content.

[0060] In an optional embodiment, after calcination in step S22, the process further includes step S23: pulverizing the solid electrolyte, adding isopropanol for ball milling, and then drying it in a vacuum oven at 60–90°C for 12–24 hours to obtain solid electrolyte powder with a particle size meeting the requirements, for example, a median particle size D50 of 100 nm to 1 μm. The preparation method of this embodiment can prepare nanoscale solid electrolytes, further improving the ionic conductivity of the solid electrolyte. Solid electrolyte particles within the aforementioned particle size range help shorten the ion transport path, improve ionic conductivity, and help improve the interfacial contact between the solid electrolyte and the positive and negative electrode materials, reducing interfacial resistance, thereby improving the overall performance of the battery, including energy density, power density, and cycle stability.

[0061] In yet another specific embodiment, the pretreated solid electrolyte powder in step S1 above can also be Li that has already formed a stable crystal structure. 1+x-2y Al x Ti 2-x-y M y (PO4)3. At this point, step S2 above can be carried out using a hydrothermal method for the fluorine substitution reaction. For example, Li... 1+x-2y Al x Ti 2-x-y M y(PO4)3 powder, fluoride, and water are mixed to obtain a mixture, and the pH is adjusted to 8-9 to obtain a first mixture. The first mixture is dispersed, and the resulting suspension is used as a second mixture. The second mixture is placed in a hydrothermal reactor for hydrothermal reaction at a pressure of 1-10 MPa and a temperature of 100-300°C for 3-5 hours. After cooling, it is aged at room temperature for 5-24 hours to obtain a third mixture. The third mixture is centrifuged, washed, and dried to obtain the above-mentioned solid electrolyte in block form. The block form is then pulverized to obtain the solid electrolyte powder.

[0062] Example 1

[0063] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.015, z = 0.003; M is the metallic element tungsten.

[0064] The preparation steps are as follows:

[0065] Step 1: Thoroughly mix concentrated phosphoric acid (86.4 wt%), lithium carbonate, aluminum hydroxide, titanium dioxide, lithium tungstate, and a certain amount of pure water to obtain a mixed slurry; the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are based on the molar ratio of lithium, aluminum, titanium, M, and phosphorus as follows:

[0066] The calculation is performed using the formula 1.27:0.3:1.685:0.015:3.

[0067] Step 2: Place the mixed slurry in a vacuum oven to dry at 150°C for 2 hours to obtain the precursor material.

[0068] Step 3: Pre-sinter the precursor material at a temperature of 800℃ for 1 hour to obtain a pretreated solid electrolyte.

[0069] Step 4: Crush and sieve the pretreated solid electrolyte to obtain pretreated solid electrolyte powder;

[0070] Step 5: Add lithium fluoride to the pretreated solid electrolyte powder at a phosphorus to fluorine molar ratio of 1:0.006 to obtain a mixed material;

[0071] Step 6: Ball mill the mixed materials to obtain a mixed powder;

[0072] Step 7: Calcine the mixed powder again at 900℃ for 3 hours to obtain the solid electrolyte Li. 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.015, z = 0.003; M is the metallic element tungsten;

[0073] Step 8: Crush the solid electrolyte, add isopropanol for ball milling, and then dry it in a vacuum oven at 90°C for 12 hours to obtain solid electrolyte powder with a median particle size D50 = 500 nm.

[0074] Example 2

[0075] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.01, z = 0.005; M is the metallic element tungsten.

[0076] The difference between the preparation steps in this embodiment and those in Example 1 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M, and phosphorus as follows:

[0077] The calculation is performed using the formula 1.28:0.3:1.69:0.01:3; the drying temperature in step two is 120℃ and the drying time is 3h; and the molar ratio of phosphorus to fluorine in step five is 1:0.01.

[0078] The remaining steps are the same as in Example 1.

[0079] Example 3

[0080] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.005, z = 0.009; M is the metallic element tungsten.

[0081] The difference between the preparation steps in this embodiment and those in Example 1 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M, and phosphorus as follows:

[0082] The calculation is performed using the formula 1.29:0.3:1.695:0.005:3; the drying temperature in step two is 200℃ and the drying time is 1h; and the molar ratio of phosphorus to fluorine in step five is 1:0.018.

[0083] The remaining steps are the same as in Example 1.

[0084] Example 4

[0085] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.4, y = 0.017, z = 0.0025; M is the metallic element tungsten.

[0086] The difference between the preparation steps in this embodiment and those in Example 1 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M, and phosphorus as follows:

[0087] The calculation is performed using the formula 1.366:0.4:1.583:0.017:3; the pre-sintering temperature in step three is 600℃ and the pre-sintering time is 3h; and the molar ratio of phosphorus to fluorine in step five is 1:0.005.

[0088] The remaining steps are the same as in Example 1.

[0089] Example 5

[0090] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.4, y = 0.011, z = 0.0045; M is the metallic element tungsten.

[0091] The difference between the preparation steps in this embodiment and those in Example 1 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M, and phosphorus as follows:

[0092] The calculation is performed using the formula 1.378:0.4:1.589:0.011:3; the pre-sintering temperature in step three is 700℃ and the pre-sintering time is 2h; and the molar ratio of phosphorus to fluorine in step five is 1:0.009.

[0093] The remaining steps are the same as in Example 1.

[0094] Example 6

[0095] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.4, y = 0.006, z = 0.0085; M is the metallic element tungsten.

[0096] The difference between the preparation steps in this embodiment and those in Example 1 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M, and phosphorus as follows:

[0097] The calculation is performed using the formula 1.388:0.4:1.594:0.006:3; the calcination temperature in step seven is 950℃ and the calcination time is 3h; and the molar ratio of phosphorus to fluorine in step five is 1:0.017.

[0098] The remaining steps are the same as in Example 1.

[0099] Example 7

[0100] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.5, y = 0.019, z = 0.002; M is the metallic element tungsten.

[0101] The difference between the preparation steps in this embodiment and those in Example 1 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M, and phosphorus as follows:

[0102] The calculation is performed using the ratio 1.462:0.5:1.481:0.019:3; the calcination temperature in step seven is 850℃ and the calcination time is 7h; and the molar ratio of phosphorus to fluorine in step five is 1:0.004.

[0103] The remaining steps are the same as in Example 1.

[0104] Example 8

[0105] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.5, y = 0.012, z = 0.004; M is the metallic element tungsten.

[0106] The difference between the preparation steps in this embodiment and those in Example 1 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M, and phosphorus as follows:

[0107] The calculation is performed using the ratio 1.476:0.5:1.488:0.012:3; the calcination temperature in step seven is 800℃ and the calcination time is 10h; and the molar ratio of phosphorus to fluorine in step five is 1:0.008.

[0108] The remaining steps are the same as in Example 1.

[0109] Example 9

[0110] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.5, y = 0.006, z = 0.008; M is the metallic element tungsten.

[0111] The difference between the preparation steps in this embodiment and those in Example 1 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M, and phosphorus as follows:

[0112] The calculation is performed using the ratio 1.488:0.5:1.494:0.006:3; the pre-sintering temperature in step three is 600℃ and the pre-sintering time is 3h; the calcination temperature in step seven is 700℃ and the calcination time is 10h; and the molar ratio of phosphorus to fluorine in step five is 1:0.016.

[0113] The remaining steps are the same as in Example 1.

[0114] Example 10

[0115] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.015, z = 0.003; M is the metallic element molybdenum.

[0116] The preparation steps are as follows:

[0117] Step 1: Thoroughly mix concentrated phosphoric acid (86.4 wt%), lithium carbonate, aluminum hydroxide, titanium dioxide, lithium molybdate, and a certain amount of pure water to obtain a mixed slurry; the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are based on the molar ratio of lithium, aluminum, titanium, M, and phosphorus as follows:

[0118] The calculation is performed using the formula 1.27:0.3:1.685:0.015:3.

[0119] Step 2: Place the mixed slurry in a vacuum oven to dry at 150°C for 2 hours to obtain the precursor material.

[0120] Step 3: Pre-sinter the precursor material at a temperature of 800℃ for 1 hour to obtain a pretreated solid electrolyte.

[0121] Step 4: Crush and sieve the pretreated solid electrolyte to obtain pretreated solid electrolyte powder;

[0122] Step 5: Add lithium fluoride to the pretreated solid electrolyte powder at a phosphorus to fluorine molar ratio of 1:0.006 to obtain a mixed material;

[0123] Step 6: Ball mill the mixed materials to obtain a mixed powder;

[0124] Step 7: Calcine the mixed powder again at 900℃ for 3 hours to obtain the solid electrolyte Li. 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.015, z = 0.003; M is the metallic element molybdenum;

[0125] Step 8: Crush the solid electrolyte, add isopropanol for ball milling, and then dry it in a vacuum oven at 90°C for 12 hours to obtain solid electrolyte powder with a median particle size D50 = 500 nm.

[0126] Example 11

[0127] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.01, z = 0.005; M is the metallic element molybdenum.

[0128] The difference between the preparation steps in this embodiment and those in Example 10 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M and phosphorus as 1.28:0.3:1.69:0.01:3; in step two, the drying temperature is 120℃ and the drying time is 3h; and in step five, the molar ratio of phosphorus to fluorine is 1:0.01.

[0129] The remaining steps are the same as in Example 10.

[0130] Example 12

[0131] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.005, z = 0.009; M is the metallic element molybdenum.

[0132] The difference between the preparation steps in this embodiment and those in Example 10 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M and phosphorus as 1.29:0.3:1.695:0.005:3; in step two, the drying temperature is 200℃ and the drying time is 1h; and in step five, the molar ratio of phosphorus to fluorine is 1:0.018.

[0133] The remaining steps are the same as in Example 10.

[0134] Example 13

[0135] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.4, y = 0.017, z = 0.0025; M is the metallic element molybdenum.

[0136] The preparation steps in this embodiment differ from those in Example 10 in that the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid in step one are calculated according to the molar ratio of lithium, aluminum, titanium, M, and phosphorus as 1.366:0.4:1.583:0.017:3; the pre-sintering temperature in step three is 600℃, and the pre-sintering time is 3 hours; and the molar ratio of phosphorus to fluorine in step five is 1:0.005. All other steps are the same as in Example 10.

[0137] Example 14

[0138] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.5, y = 0.019, z = 0.002; M is the metallic element molybdenum.

[0139] The difference between the preparation steps in this embodiment and those in Example 10 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M and phosphorus as 1.462:0.5:1.481:0.019:3; in step three, the pre-sintering temperature is 700℃ and the pre-sintering time is 2h; and in step five, the molar ratio of phosphorus to fluorine is 1:0.004.

[0140] The remaining steps are the same as in Example 10.

[0141] Example 15

[0142] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.015, z = 0.003; M is the metallic element chromium.

[0143] The preparation steps are as follows:

[0144] Step 1: Thoroughly mix concentrated phosphoric acid (86.4 wt%), lithium carbonate, aluminum hydroxide, titanium dioxide, lithium chromate, and a certain amount of pure water to obtain a mixed slurry; the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are based on the molar ratio of lithium, aluminum, titanium, M, and phosphorus as follows:

[0145] The calculation is performed using the formula 1.27:0.3:1.685:0.015:3.

[0146] Step 2: Place the mixed slurry in a vacuum oven to dry at 150°C for 2 hours to obtain the precursor material.

[0147] Step 3: Pre-sinter the precursor material at a temperature of 850℃ for 1 hour to obtain a pretreated solid electrolyte.

[0148] Step 4: Crush and sieve the pretreated solid electrolyte to obtain pretreated solid electrolyte powder;

[0149] Step 5: Add lithium fluoride to the pretreated solid electrolyte powder at a phosphorus to fluorine molar ratio of 1:0.006 to obtain a mixed material;

[0150] Step 6: Ball mill the mixed materials to obtain a mixed powder;

[0151] Step 7: Calcine the mixed powder again at 900℃ for 3 hours to obtain the solid electrolyte Li. 1+x-2y Al x Ti2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.015, z = 0.003; M is the metallic element tungsten;

[0152] Step 8: Crush the solid electrolyte, add isopropanol for ball milling, and then dry it in a vacuum oven at 90°C for 12 hours to obtain solid electrolyte powder with a median particle size D50 = 500 nm.

[0153] Example 16

[0154] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.01, z = 0.005; M is the metallic element chromium.

[0155] The difference between the preparation steps in this embodiment and those in Example 15 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M and phosphorus as 1.28:0.3:1.69:0.01:3; in step seven, the calcination temperature is 950℃ and the calcination time is 3h; and in step five, the molar ratio of phosphorus to fluorine is 1:0.01.

[0156] The remaining steps are the same as in Example 15.

[0157] Example 17

[0158] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.005, z = 0.009; M is the metallic element chromium.

[0159] The difference between the preparation steps in this embodiment and those in Example 15 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M and phosphorus as 1.29:0.3:1.695:0.005:3; in step seven, the calcination temperature is 850℃ and the calcination time is 7h; and in step five, the molar ratio of phosphorus to fluorine is 1:0.018.

[0160] The remaining steps are the same as in Example 15.

[0161] Example 18

[0162] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.4, y = 0.017, z = 0.0025; M is the metallic element chromium.

[0163] The difference between the preparation steps in this embodiment and those in Example 15 is that in step one, the amounts of lithium source, aluminum source, titanium source, M-containing compound and phosphoric acid are calculated according to the molar ratio of lithium, aluminum, titanium, M and phosphorus as 1.366:0.4:1.583:0.017:3; in step seven, the calcination temperature is 800℃ and the calcination time is 10h; and in step five, the molar ratio of phosphorus to fluorine is 1:0.005.

[0164] The remaining steps are the same as in Example 15.

[0165] Example 19

[0166] Preparation of solid electrolyte Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.5, y = 0.019, z = 0.002; M is the metallic element chromium.

[0167] The difference between the preparation steps in this embodiment and those in Example 15 is that the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid in step one are calculated according to the molar ratio of lithium, aluminum, titanium, M, and phosphorus as 1.462:0.5:1.481:0.019:3; and the molar ratio of phosphorus to fluorine in step five is 1:0.004. The remaining steps are the same as in Example 15.

[0168] Comparative Example 1

[0169] Preparation of solid electrolyte lithium titanium aluminum phosphate Li 1.3 Al 0.3 Ti 1.7 (PO4)3, that is, for the expression Li 1+x-2y Al x Ti 2-x- y M y (PO 4-z F 2z )3, where x = 0.3, y = 0, z = 0.

[0170] Step 1: Mix concentrated phosphoric acid (86.4 wt%), lithium carbonate, aluminum hydroxide, titanium dioxide and a certain amount of pure water thoroughly according to the element ratio to obtain a mixed slurry;

[0171] Step 2: Place the mixed slurry in a vacuum oven to dry at 150°C for 2 hours to obtain the precursor material.

[0172] Step 3: Pre-sinter the precursor material at a temperature of 800℃ for 1 hour to obtain a pretreated solid electrolyte.

[0173] Step 4: Crush and sieve the pretreated solid electrolyte to obtain pretreated solid electrolyte powder;

[0174] Step 5: The pretreated solid electrolyte powder is calcined again at 900℃ for 3 hours to obtain the solid electrolyte Li. 1.3 Al 0.3 Ti 1.7 (PO4)3;

[0175] Step 6: Crush the solid electrolyte, add isopropanol for ball milling, and then dry it in a vacuum oven at 90°C for 12 hours to obtain solid electrolyte powder with a median particle size D50 = 500 nm.

[0176] Comparative Example 2

[0177] Preparation of solid electrolyte Li 1.27 Al 0.3 Ti 1.685 W 0.015 (PO4)3, that is, for the expression Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.015, z = 0; M is tungsten.

[0178] Step 1: Mix concentrated phosphoric acid (86.4 wt%), lithium carbonate, aluminum hydroxide, titanium dioxide, lithium tungstate and a certain amount of pure water thoroughly according to the element ratio to obtain a mixed slurry;

[0179] Step 2: Place the mixed slurry in a vacuum oven to dry at 150°C for 2 hours to obtain the precursor material;

[0180] Step 3: Pre-sinter the precursor material at 800℃ for 1 hour to obtain a pretreated solid electrolyte.

[0181] Step 4: Crush and sieve the pretreated solid electrolyte to obtain pretreated solid electrolyte powder;

[0182] Step 5: The pretreated solid electrolyte powder is calcined again at 900℃ for 3 hours to obtain the solid electrolyte Li. 1.27 Al 0.3 Ti 1.685 W 0.015 (PO4)3;

[0183] Step 6: Crush the solid electrolyte, add isopropanol for ball milling, and then dry it in a vacuum oven at 90°C for 12 hours to obtain solid electrolyte powder with a median particle size D50 = 500 nm.

[0184] Comparative Example 3

[0185] Preparation of solid electrolyte Li 1.27 Al 0.3 Ti 1.685 Mo 0.015 (PO4)3, that is, for the expression Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.015, z = 0; M is molybdenum.

[0186] Step 1: Mix concentrated phosphoric acid (86.4 wt%), lithium carbonate, aluminum hydroxide, titanium dioxide, lithium molybdate, and a certain amount of pure water thoroughly according to the element ratio to obtain a mixed slurry;

[0187] Step 2: Place the mixed slurry in a vacuum oven to dry at 150°C for 2 hours to obtain the precursor material;

[0188] Step 3: Pre-sinter the precursor material at 800℃ for 1 hour to obtain a pretreated solid electrolyte.

[0189] Step 4: Crush and sieve the pretreated solid electrolyte to obtain pretreated solid electrolyte powder;

[0190] Step 5: The pretreated solid electrolyte powder is calcined again at 900℃ for 3 hours to obtain the solid electrolyte Li. 1.27 Al 0.3 Ti 1.685 Mo 0.015 (PO4)3;

[0191] Step 6: Crush the solid electrolyte, add isopropanol for ball milling, and then dry it in a vacuum oven at 90°C for 12 hours to obtain solid electrolyte powder with a median particle size D50 = 500 nm.

[0192] Comparative Example 4

[0193] Preparation of solid electrolyte Li 1.27 Al 0.3 Ti 1.685 Cr 0.015 (PO4)3, that is, for the expression Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0.015, z = 0; M is chromium.

[0194] Step 1: Mix concentrated phosphoric acid (86.4 wt%), lithium carbonate, aluminum hydroxide, titanium dioxide, lithium chromate and a certain amount of pure water thoroughly according to the element ratio to obtain a mixed slurry;

[0195] Step 2: Place the mixed slurry in a vacuum oven to dry at 150°C for 2 hours to obtain the precursor material;

[0196] Step 3: Pre-sinter the precursor material at 850℃ for 1 hour to obtain a pretreated solid electrolyte.

[0197] Step 4: Crush and sieve the pretreated solid electrolyte to obtain pretreated solid electrolyte powder;

[0198] Step 5: The pretreated solid electrolyte powder is calcined again at 900℃ for 3 hours to obtain the solid electrolyte Li. 1.27 Al 0.3 Ti 1.685 Cr 0.015 (PO4)3;

[0199] Step 6: Crush the solid electrolyte, add isopropanol for ball milling, and then dry it in a vacuum oven at 90°C for 12 hours to obtain solid electrolyte powder with a median particle size D50 = 500 nm.

[0200] Comparative Example 5

[0201] Preparation of solid electrolyte Li 1.3 Al 0.3 Ti 1.7 (PO 3.99 F 0.02 )3, that is, for the expression Li 1+x-2y Alx Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.3, y = 0, z = 0.01.

[0202] Step 1: Mix concentrated phosphoric acid (86.4 wt%), lithium carbonate, aluminum hydroxide, titanium dioxide and a certain amount of pure water thoroughly according to the element ratio to obtain a mixed slurry;

[0203] Step 2: Place the mixed slurry in a vacuum oven to dry at 150°C for 2 hours to obtain the precursor material.

[0204] Step 3: Pre-sinter the precursor material at a temperature of 800℃ for 1 hour to obtain a pretreated solid electrolyte.

[0205] Step 4: Crush and sieve the pretreated solid electrolyte to obtain pretreated solid electrolyte powder;

[0206] Step 5: Add lithium fluoride to the pretreated solid electrolyte powder at a phosphorus to fluorine molar ratio of 1:0.01 to obtain a mixed material;

[0207] Step 6: Ball mill the mixed materials to obtain a mixed powder;

[0208] Step 7: Calcine the mixed powder again at 900℃ for 3 hours to obtain the solid electrolyte Li. 1.3 Al 0.3 Ti 1.7 (PO 3.99 F 0.02 3;

[0209] Step 8: Crush the solid electrolyte, add isopropanol for ball milling, and then dry it in a vacuum oven at 90°C for 12 hours to obtain solid electrolyte powder with a median particle size D50 = 500 nm.

[0210] Comparative Example 6

[0211] Preparation of solid electrolyte lithium titanium aluminum phosphate Li 1.4 Al 0.4 Ti 1.6 (PO4)3, that is, for the expression Li 1+x-2y Al x Ti 2-x- y M y (PO 4-z F 2z )3, where x = 0.4, y = 0, z = 0.

[0212] The difference between the preparation steps of this comparative example and those of Comparative Example 1 is that the amounts of lithium source, aluminum source, titanium source and phosphoric acid in step one are calculated according to the molar ratio of lithium, aluminum, titanium, M and phosphorus as 1.4:0.4:1.6:3.

[0213] The remaining steps are the same as those in Comparative Example 1.

[0214] Comparative Example 7

[0215] Preparation of solid electrolyte Li 1.366 Al 0.4 Ti 1.583 W 0.017 (PO4)3, that is, for the expression Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.4, y = 0.017, z = 0; M is tungsten.

[0216] The difference between the preparation steps of this comparative example and those of Comparative Example 2 is that the amounts of lithium source, aluminum source, titanium source, tungsten source and phosphoric acid in step one are calculated according to the molar ratio of lithium, aluminum, titanium, M and phosphorus as 1.366:0.4:1.583:0.017:3.

[0217] The remaining steps are the same as those in Comparative Example 2.

[0218] Comparative Example 8

[0219] Preparation of solid electrolyte Li 1.4 Al 0.4 Ti 1.6 (PO 3.99 F 0.02 )3, that is, for the expression Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.4, y = 0, z = 0.01.

[0220] The difference between the preparation steps of this comparative example and those of Comparative Example 5 is that the amounts of lithium source, aluminum source, titanium source and phosphoric acid in step one are calculated according to the molar ratio of lithium, aluminum, titanium and phosphorus as 1.4:0.4:1.6:3.

[0221] The remaining steps are the same as those in Comparative Example 5.

[0222] Comparative Example 9

[0223] Preparation of solid electrolyte Li 1.5 Al0.5 Ti 1.5 (PO4)3, that is, for the expression Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.5, y = 0, z = 0.

[0224] The difference between the preparation steps of this comparative example and those of Comparative Example 1 is that the amounts of lithium source, aluminum source, titanium source and phosphoric acid in step one are calculated according to the molar ratio of lithium, aluminum, titanium, M and phosphorus as 1.5:0.5:1.5:3.

[0225] The remaining steps are the same as those in Comparative Example 1.

[0226] Comparative Example 10

[0227] Preparation of solid electrolyte Li 1.462 Al 0.5 Ti 1.481 W 0.019 (PO4)3, that is, for the expression Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.5, y = 0.019, z = 0; M is tungsten.

[0228] The difference between the preparation steps of this comparative example and those of Comparative Example 2 is that the amounts of lithium source, aluminum source, titanium source, tungsten source and phosphoric acid in step one are calculated according to the molar ratio of lithium, aluminum, titanium, M and phosphorus as 1.462:0.5:1.481:0.019:3.

[0229] The remaining steps are the same as those in Comparative Example 2.

[0230] Comparative Example 11

[0231] Lithium titanium aluminum phosphate solid electrolyte preparation 1.5 Al 0.5 Ti 1.5 (PO 3.99 F 0.02 )3, that is, for the expression Li 1+x- 2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where x = 0.5, y = 0, z = 0.01.

[0232] The difference between the preparation steps of this comparative example and those of Comparative Example 5 is that the amounts of lithium source, aluminum source, titanium source and phosphoric acid in step one are calculated according to the molar ratio of lithium, aluminum, titanium and phosphorus as 1.5:0.5:1.5:3.

[0233] The remaining steps are the same as those in Comparative Example 5.

[0234] The solid electrolyte powders of Examples 1-19 and Comparative Examples 1-11 were subjected to ionic conductivity and moisture content tests, and the results are shown in Table 1.

[0235] Ionic conductivity was tested according to the test method specified in industry standard T / SPSTS 019-2021 "Performance Requirements and Test Methods for Solid Electrolytes for Solid-State Lithium Batteries - Inorganic Oxide Solid Electrolytes". The solid electrolyte material was fabricated into a wafer sample, and gold sputtering was applied to both sides of the wafer to obtain a gold-sputtered wafer. AC impedance spectroscopy was performed on the gold-sputtered wafer using an electrochemical workstation. The ionic conductivity of the material was obtained through conventional fitting, analysis, and calculation of the AC impedance test results.

[0236] Moisture content was determined using the conventional Karl Fischer moisture determination method.

[0237] Table 1 Comparison of ionic conductivity and moisture content between Examples 1-19 and Comparative Examples 1-11

[0238] Ionic conductivity (S / cm) Moisture content (ppm) Comparative Example 11 <![CDATA[2.01*10 -4 ]]> 867 Example 1 <![CDATA[8.24*10 -4 ]]> 588 Example 2 <![CDATA[7.71*10 -4 ]]> 601 Example 3 <![CDATA[7.15*10 -4 ]]> 624 Example 4 <![CDATA[7.70*10 -4 ]]> 597 Example 5 <![CDATA[7.41*10 -4 ]]> 614 Example 6 <![CDATA[7.01*10 -4 ]]> 631 Example 7 <![CDATA[7.24*10 -4 ]]> 633 Example 8 <![CDATA[6.83*10 -4 ]]> 634 Example 9 <![CDATA[6.17*10 -4 ]]> 645 Example 10 <![CDATA[7.78*10 -4 ]]> 615 Example 11 <![CDATA[7.24*10 -4 ]]> 618 Example 12 <![CDATA[6.83*10 -4 ]]> 627 Example 13 <![CDATA[7.29*10 -4 ]]> 634 Example 14 <![CDATA[7.08*10 -4 ]]> 666 Example 15 <![CDATA[7.47*10 -4 ]]> 630 Example 16 <![CDATA[6.99*10 -4 ]]> 639 Example 17 <![CDATA[6.54*10 -4 ]]> 641 Example 18 <![CDATA[7.17*10 -4 ]]> 644 Example 19 <![CDATA[6.96*10 -4 ]]> 677 Comparative Example 1 <![CDATA[2.45*10 -4 ]]> 2499 Comparative Example 2 <![CDATA[8.19*10 -4 ]]> 2397 Comparative Example 3 <![CDATA[7.86*10 -4 ]]> 2479 Comparative Example 4 <![CDATA[7.51*10 -4 ]]> 2483 Comparative Example 5 <![CDATA[2.51*10 -4 ]]> 793 Comparative Example 6 <![CDATA[2.21*10 -4 ]]> 2534 Comparative Example 7 <![CDATA[7.69*10 -4 ]]> 2457 Comparative Example 8 <![CDATA[2.33*10 -4 ]]> 842 Comparative Example 9 <![CDATA[1.98*10 -4 ]]> 2521 Comparative Example 10 <![CDATA[7.23*10 -4 ]]> 2497 Comparative Example 11 <![CDATA[2.01*10 -4 ]]> 867

[0239] As can be seen from the comparison of the results of the examples and comparative examples in Table 1, by doping high-valence metal ions into lithium titanium aluminum phosphate, the ionic conductivity of the solid electrolyte is effectively improved, and after further introducing fluoride ions to replace part of the oxygen ions, the water content of the solid electrolyte powder is effectively reduced.

[0240] from Figure 1 It can be seen that no impurity phases appeared in the solid electrolyte samples after composite doping in Example 1.

[0241] from Figure 2 It can be seen that, Figure 2 (b) The solid electrolyte of Example 1 has a greater distribution of fluorine, indicating that doping with high-valence metal ions can introduce additional active substitution sites on the surface of lithium titanium aluminum phosphate, allowing more oxygen ions on the surface of the doped lithium titanium aluminum phosphate to be replaced by fluorine ions. That is, fluorine ions are more easily enriched on the surface of the material particles. Therefore, even if the fluorine ion doping amount is less than that of Comparative Example 5 (see Comparative Example 5), the fluorine ion doping concentration is higher. Figure 2 (a)), but the particle surface still exhibits a higher concentration of fluoride ions, which is beneficial for reducing the moisture content of the material.

[0242] The solid electrolytes prepared in the various embodiments of this application have both high ionic conductivity and low water content, making them suitable for use in lithium-ion batteries and possessing excellent application prospects and economic value.

[0243] Obviously, the embodiments described above are only some embodiments of this application, not all embodiments. The accompanying drawings show preferred embodiments of this application, but do not limit the patent scope of this application. This application can be implemented in many different forms; rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this application's specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this application.

Claims

1. A solid electrolyte, characterized in that, The solid electrolyte is Li 1+x-2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where 0.3≤x≤0.5, 0.004<y<0.02, 0<z≤0.01; where M is a metallic element with a valence greater than +4.

2. The solid electrolyte as described in claim 1, characterized in that, M is a metallic element with a valence state of +6; preferably, M is selected from one or more of tungsten, molybdenum, and chromium.

3. The solid electrolyte as described in claim 1, characterized in that, When 0.004 < y ≤ 0.01, 0.005 ≤ z ≤ 0.01; when 0.01 < y < 0.02, 0 < z < 0.

005.

4. A method for preparing a solid electrolyte, characterized in that, The method for preparing the solid electrolyte as described in any one of claims 1-3 comprises: The raw materials are mixed to obtain a mixed material, wherein the raw materials include pretreated solid electrolyte powder and fluoride; wherein the pretreated solid electrolyte contains lithium, aluminum, titanium, M, phosphorus and oxygen, and M is a metal element with a valence greater than +4; the molar ratio of lithium, aluminum, titanium, M and phosphorus is (1+x-2y):x:(2-xy):y:3, and 0.3≤x≤0.5, 0.004<y<0.02; The mixed material was subjected to a fluorine substitution reaction under preset temperature conditions to prepare the solid electrolyte Li. 1+x- 2y Al x Ti 2-x-y M y (PO 4-z F 2z )3, where 0.3≤x≤0.5, 0.004<y<0.02, 0<z≤0.

01.

5. The method for preparing a solid electrolyte as described in claim 4, characterized in that, M is a metallic element with a valence state of +6; preferably, M is selected from one or more of tungsten, molybdenum, and chromium.

6. The method for preparing a solid electrolyte as described in claim 4, characterized in that, The fluoride includes at least one of lithium fluoride and ammonium fluoride.

7. The method for preparing a solid electrolyte as described in claim 4 or 5, characterized in that, Before the step of mixing the raw materials, the method further includes: Phosphoric acid, lithium source, aluminum source, titanium source, M-containing compound, and water are mixed and stirred to obtain a mixed slurry; wherein, the amounts of lithium source, aluminum source, titanium source, M-containing compound, and phosphoric acid are adjusted according to the molar ratio of lithium, aluminum, titanium, M, and phosphorus as (1+x-2y):x:(2-xy):y:3, where 0.3≤x≤0.5, 0.004<y<0.02; The mixed slurry is dried to obtain the precursor material; The precursor material is pre-sintered to obtain a pretreated solid electrolyte; The pretreated solid electrolyte is crushed and sieved to obtain the pretreated solid electrolyte powder.

8. The method for preparing a solid electrolyte as described in claim 7, characterized in that, The M-containing compound includes at least one of lithium tungstate, ammonium tungstate, ammonium metatungstate, ammonium paratungstate, lithium molybdate, ammonium orthomolybdate, ammonium paramolybdate, ammonium dimolybdate, ammonium tetramolybdate, ammonium molybdate tetrahydrate, ammonium heptamolybdate, lithium chromate, and ammonium dichromate; the lithium source includes at least one of lithium carbonate and lithium hydroxide; the aluminum source includes at least one of aluminum oxide and aluminum hydroxide; and the titanium source includes at least one of titanium dioxide and titanate.

9. The method for preparing a solid electrolyte as described in claim 7, characterized in that, In the step of drying the mixed slurry, the drying temperature range is 120℃~200℃, and the drying time is 1h~3h; in the step of pre-sintering the precursor material, the pre-sintering temperature range is 600℃~800℃, and the pre-sintering time is 1h~3h.

10. The method for preparing a solid electrolyte as described in claim 7, characterized in that, The step of carrying out a fluorine substitution reaction on the mixed material under a preset temperature condition includes: The mixed materials are ball-milled to obtain a mixed powder. The mixed powder is calcined at a temperature greater than or equal to 700°C and less than 1000°C, and the calcination temperature is greater than the pre-sintering temperature. The calcination time is 3h to 10h to obtain the solid electrolyte.

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