Solid electrolyte material and preparation method and application thereof

Abstract

The invention belongs to the technical field of solid electrolyte materials, and discloses a solid electrolyte material and a preparation method and application thereof. According to the preparation method, the sintering aid is added in the sintering process of the solid electrolyte material, so that the expansion problem and the bonding problem in the existing processing process are effectively solved on the premise of not influencing the product performance. The adopted sintering aid is a biomass material, so that the problem that the sintered material is adhered to the inner wall of a mold is effectively solved, the problem of material expansion is solved by reducing instantaneous release of gas in the sintering process, oxidation reaction can be completely carried out in the heating and heat preservation stages to be consumed and discharged, and other impurities are not contained; the performance of the material is not influenced; by effectively exhausting gas, the internal structure of the sintered material is more uniform and compact, the high purity and high ionic conductivity of the material are ensured, the machinability of the material is effectively improved, the single-batch sintering amount is increased, and the production and preparation cost of the material is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid-state electrolyte materials, and particularly relates to a solid-state electrolyte material and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of lithium ion batteries, the concept of all-solid-state / batteries is gradually popularized, and solid-state batteries are considered to be a form capable of achieving the high energy density and high safety requirements of lithium ion secondary batteries. Based on this, the research on solid-state electrolyte materials has become a hot topic in the academic field, and has attracted widespread attention in the industry. Oxide solid-state electrolyte, sulfide solid-state electrolyte and polymer solid-state electrolyte have become the three major systems at present.

[0003] The sulfide solid-state electrolyte has relatively excellent ionic conductivity and interface performance, but its poor chemical stability limits its current wide application; the polymer solid-state electrolyte has excellent interface performance and good chemical stability, but its ionic conductivity is relatively low, and it is currently relatively difficult to achieve independent application, and is mainly used as a composite solid-state electrolyte in combination with other materials; the oxide solid-state electrolyte has relatively good ionic conductivity, chemical stability and air stability, making it one of the systems that have attracted much attention, but its interface performance is poor, and it is difficult to be applied to all-solid-state electrolyte materials at the present stage.

[0004] The lithium titanium aluminum phosphate Li 1+x Al x Ti 2-x (PO4)3, lithium germanium aluminum phosphate Li 1+x Al x Ge 2-x (PO4)3 solid-state electrolyte material is considered to be a main material with commercial application prospect. At present, the preparation method of the above-mentioned solid-state electrolyte material is mainly a solid phase method, but in the preparation process, due to the use of phosphate raw materials, a molten state is formed under heating, which causes the gas generated in the sintering process of the raw materials to be difficult to discharge, and serious expansion phenomenon is formed, and the sintered material is seriously bonded to the sintering mold, which is difficult to effectively take out the material, causing material waste and difficulty in collecting the material. Therefore, it is urgent to solve the material expansion and bonding problems in the preparation process of the above-mentioned solid phase method. SUMMARY

[0005] In order to overcome the shortcomings and deficiencies of the prior art, the primary purpose of the present application is to provide a preparation method of a solid-state electrolyte material.

[0006] The method of this invention effectively solves the problems of material expansion and adhesion in existing processing procedures by adding sintering aids during the sintering process of solid electrolyte materials, without affecting the performance of the product. This improves the processability of solid electrolyte materials, the amount of sintering per batch, and reduces the production cost, without affecting the high purity and high ionic conductivity of the sintered product.

[0007] The present invention also provides a solid electrolyte material prepared by the above method.

[0008] The objective of this invention is achieved through the following solution:

[0009] A method for preparing a solid electrolyte material involves mixing a solid electrolyte precursor material and a sintering aid, followed by sintering.

[0010] In the technical solution of the present invention, the solid electrolyte material includes at least one of lithium titanium aluminum phosphate and its doped materials, and lithium germanium aluminum phosphate and its doped materials.

[0011] Furthermore, the chemical formula of lithium titanium aluminum phosphate material can be Li 1+x Al x Ti 2-x (PO4)3, 0.1≤x≤0.7.

[0012] Furthermore, the chemical formula of lithium aluminum germanium phosphate material can be Li 1+x Al x Ge 2-x (PO4)3, 0.1≤x≤0.5.

[0013] Furthermore, the doped material refers to materials obtained by doping solid electrolyte materials with other elements to improve their performance, such as lithium aluminum titanium phosphate (LiTi) based materials (LiTi) doped with at least one of the elements Si, Mg, Zr, B, and La to the Ti site. 1+x+(4-a)y Al x Ti 2-x-y M y (PO4)3, 0.1≤x≤0.7, 0≤y≤0.2, a is the valence state of dopant element M, which can be +2, +3, +4), lithium aluminum germanium phosphate-based materials (Li 1+x+(4-a)y Al x Ge 2-x-y M y (PO4)3, 0.1≤x≤0.5, 0≤y≤0.2, where a is the valence state of dopant element M (which can be +2, +3, or +4). The use of dopant elements does not affect the preparation of the above solid electrolyte materials based on the solid-state reaction.

[0014] In the technical scheme of the present application, the sintering method is a conventional sintering method for solid electrolyte materials in the art, i.e., the mixed material is added into a mold and sintered according to a set program.

[0015] In the technical scheme of the present application, the mass ratio of the solid electrolyte precursor material and the sintering aid can be 100:0.1 to 100:15.

[0016] In the technical scheme of the present application, the sintering aid is at least one of biomass materials.

[0017] Further, the biomass material can be at least one of lignin, tea polyphenol, tannic acid, hyaluronic acid, natural cellulose, chitosan, starch, guar gum, xylan, etc.

[0018] Further, the biomass material monomer contains at least one of hydroxyl, carboxyl, aldehyde groups, etc.; and the total number of the above groups in the monomer is three or more.

[0019] In the technical scheme of the present application, the solid electrolyte precursor material is determined according to the target solid electrolyte material:

[0020] (1) For example, when the target solid electrolyte material is a lithium aluminum titanium phosphate material, the precursor material includes a lithium source, an aluminum source, a titanium source, a phosphorus source, etc.

[0021] Further, the titanium source is a conventional titanium source used in the art, which can be at least one of titanium dioxide, titanium hydroxide, titanium pyrophosphate, etc.

[0022] Further, the lithium source is a conventional lithium source used in the art, which can be at least one of lithium carbonate, lithium hydroxide, lithium oxide, lithium oxalate, lithium acetate, lithium dihydrogen phosphate, etc.

[0023] Further, the aluminum source is a conventional aluminum source used in the art, which can be at least one of aluminum oxide, aluminum hydroxide, aluminum phosphate, etc.

[0024] Further, the phosphorus source is a conventional phosphorus source used in the art, which can be at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, diphosphorus pentoxide, lithium dihydrogen phosphate, etc.

[0025] (2) For another example, when the target solid electrolyte material is a lithium aluminum germanium phosphate material, the precursor material can include a lithium source, an aluminum source, a germanium source, a phosphorus source, etc.

[0026] Further, the germanium source is a conventional germanium source used in the art, which can be at least one of germanium dioxide, germanium tetrahydroxide, etc.

[0027] Further, the lithium source can be any lithium source commonly used in the art, for example, at least one selected from lithium carbonate, lithium hydroxide, lithium oxide, lithium oxalate, lithium acetate, lithium dihydrogen phosphate, etc.

[0028] Further, the aluminum source can be any aluminum source commonly used in the art, for example, at least one selected from aluminum oxide, aluminum hydroxide, aluminum phosphate, etc.

[0029] Further, the phosphorus source can be any phosphorus source commonly used in the art, for example, at least one selected from ammonium dihydrogen phosphate, diammonium hydrogen phosphate, diaphosphorus pentoxide, lithium dihydrogen phosphate, etc.

[0030] In the method of the present application, by adding biomass material as a sintering aid and co-sintering with the solid electrolyte precursor material, the hydroxyl, carboxyl, aldehyde group and other groups rich in biomass material can play a role as a "network modifier" in the phosphate melt, break the long-chain structure of the phosphate, reduce the intermolecular force, and reduce the degree of polymerization, so that the viscosity of the phosphate is greatly reduced during heating, and after contacting with the inner wall of the sintering mold, it will not form a strong bond, effectively solving the problem of the material sticking to the inner wall of the mold after sintering.

[0031] When the precursor material contains NH4 + -containing phosphorus source, the active groups in the biomass material can combine with NH4 + , reducing the instantaneous release of NH3 during sintering and delaying its release rate, while combining with the decrease in the viscosity of the phosphate melt, effectively discharging NH3, H2O, CO2 and other gases from the sintered body, solving the problem of material expansion due to the difficulty of gas discharge, and the sintered material showing a tight shrinkage state.

[0032] The sintering aid used in the present application is biomass material, which can completely oxidize and be discharged during the heating and holding stages, and does not contain other impurities. The gases released at high temperature are released slowly and do not cause material expansion or affect the performance of the material, improving the processability and single-batch sintering amount of the solid electrolyte material, reducing the production cost of the material, and ensuring the high purity and high ionic conductivity of the sintered material.

[0033] In the technical solution of the present application, the mixing can be carried out by dry mechanical mixing.

[0034] In the technical solution of the present application, the mold used for sintering can be any mold commonly used in the art, for example, a box, a crucible, a boat, etc.

[0035] In the technical solution of the present application, the sintering temperature can be 600-1000℃, the holding time can be 2-20h, and the heating rate can be 2-10℃ / min.

[0036] In the technical scheme of the present application, the sintering is carried out in an air atmosphere.

[0037] In the technical scheme of the present application, the flow rate of the air atmosphere can be 0.5-5.0 L / min.

[0038] In the technical scheme of the present application, the sintered powder can be further processed into a nano-powder through conventional processes such as crushing, drying, etc.

[0039] Further, the crushing process can be a conventional crushing process in the art, such as mechanical crushing, ball milling, sand milling, air flow crushing, etc.

[0040] Further, the drying process can be a conventional drying process in the art, such as oven drying, air blowing drying, microwave drying, spray drying, etc.

[0041] In the technical scheme of the present application, the particle size D50 of the obtained nano-powder can be 100-1000 nm.

[0042] The present application also provides a solid electrolyte material prepared by the above method.

[0043] The method of the present application effectively avoids the expansion problem caused by the molten state of the phosphorus source during the sintering process of the material, and forms an effective barrier between the material and the mold, thereby avoiding the problem of adhesion between the sintered material and the mold, improving the sintering amount and yield of the material per batch, and facilitating the large-scale industrial production, cost reduction and subsequent processing of the material.

[0044] The sintering aid used in the method of the present application is a biomass material which is oxidized and consumed without residue during high-temperature sintering, does not produce new impurities, has no effect on the composition of the electrolyte material itself, and through the solution of expansion, adhesion and other problems, the structure of the sintered material is more uniform and dense, and a high-purity, easy-to-process, high-ionic-conductivity, low-cost solid electrolyte material is obtained.

[0045] Compared with the prior art, the present application has the following advantages and beneficial effects: (1) The present application provides a preparation method of a solid electrolyte material, specifically a solid phase method. The present application adds a biomass material rich in active groups such as hydroxyl groups, carboxyl groups and aldehyde groups during the preparation process, and uses the hydroxyl groups, carboxyl groups and aldehyde groups to break the long-chain structure of the phosphate salt in the phosphate salt melt, reduce the intermolecular force, reduce the degree of polymerization, reduce the viscosity of the phosphate salt melt, ensure the orderly and efficient discharge of the gas generated during the sintering process, and solve the problems of material expansion and wall adhesion during the sintering process of the solid phase method for preparing the electrolyte material. (2) the sintering aid added in the preparation method of the present application is all oxidized and discharged in the sintering process, no residue is left, no new impurity is produced, thus the performance of the electrolyte material itself is not affected, and through effective discharge of gas, the internal structure of the material obtained by sintering is more uniform and compact, the high purity of the material is ensured, the high ionic conductivity of the material is realized, the processability of the material is effectively improved, the sintering amount of a single batch is increased, and the production cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows, and it should be understood that the following drawings only show some of the embodiments of the present application, and should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0047] Figure 1 Material state of the electrolyte material sintered in Example 1.

[0048] Figure 2 Material state of the material sintered in Comparative Example 1-Comparative Example 2.

[0049] Figure 3 Phase diagram of the solid-state electrolyte material sintered in the present application.

[0050] Figure 4 Nyquist diagram of the electrolyte material prepared in Example 1. DETAILED DESCRIPTION

[0051] The present application will be further described in detail below in combination with examples, but the embodiments of the present application are not limited thereto. The materials involved in the following examples can be obtained from commercial channels if not otherwise specified. The methods are conventional methods if not otherwise specified. The amounts of the components are measured by mass parts and volume parts, g and mL. Example 1

[0052] According to Li 1.3 Al 0.3 Ti 1.7The total amount of lithium carbonate, alumina, titanium dioxide, and ammonium dihydrogen phosphate raw materials is 4000 parts by mass, and 20 parts by mass of lignin is added. Dry mixing is performed until the materials are uniform. Then, the materials are placed in an alumina crucible and sintered in a high-temperature furnace. The sintering air atmosphere flow rate is 1.0 L / min, the sintering temperature is 700°C, the holding time is 2 h, and the heating rate is 10°C / min. After sintering is complete, the materials are removed and subjected to mechanical crushing, sand grinding, and subsequent drying and jet milling to obtain a nano-powder with a particle size D50 of 200 nm. Example 2

[0053] According to Li 1.4 Al 0.4 Ti 1.6 The total amount of lithium carbonate, alumina, titanium dioxide, and ammonium dihydrogen phosphate raw materials is 4000 parts by mass, and 20 parts by mass of lignin is added. Dry mixing is performed until the materials are uniform. Then, the materials are placed in an alumina crucible and sintered in a high-temperature furnace. The sintering air atmosphere flow rate is 1.0 L / min, the sintering temperature is 700°C, the holding time is 2 h, and the heating rate is 10°C / min. After sintering is complete, the materials are removed and subjected to mechanical crushing, sand grinding, and subsequent drying and jet milling to obtain a nano-powder with a particle size D50 of 200 nm. Example 3

[0054] According to Li 1.5 Al 0.5 Ti 1.5 The total amount of lithium carbonate, alumina, titanium dioxide, and ammonium dihydrogen phosphate raw materials is 4000 parts by mass, and 20 parts by mass of lignin is added. Dry mixing is performed until the materials are uniform. Then, the materials are placed in an alumina crucible and sintered in a high-temperature furnace. The sintering air atmosphere flow rate is 1.0 L / min, the sintering temperature is 700°C, the holding time is 2 h, and the heating rate is 10°C / min. After sintering is complete, the materials are removed and subjected to mechanical crushing, sand grinding, and subsequent drying and jet milling to obtain a nano-powder with a particle size D50 of 200 nm. Example 4

[0055] According to Li 1.6 Al 0.6 Ti 1.3 Si 0.1(PO4)3stoichiometric ratio of lithium oxalate, aluminum phosphate, titanium dioxide, silicon dioxide, and phosphorus pentoxide were weighed in total 3000 parts by mass, 45 parts by mass of lignin and 45 parts by mass of hyaluronic acid were added, dry mixing was performed until uniform, then the material was added to a zirconium corundum crucible and sintered in a high-temperature furnace, the sintering air atmosphere flow rate was 2.5 L / min, the sintering temperature was 750°C, the holding time was 10 h, and the heating rate was 2°C / min, after sintering was completed, the material was taken out and then subjected to mechanical crushing, micron particle crushing, ball milling, micron particle powdering, and the powder particle size D50 was 600 nm. Example 5

[0056] According to Li 1.7 Al 0.7 Ti 1.3 (PO4)3stoichiometric ratio of lithium acetate, aluminum oxide, titanium dioxide, and ammonium dihydrogen phosphate were weighed in total 5000 parts by mass, 200 parts by mass of tea polyphenol was added, dry mixing was performed until uniform, then the material was added to an aluminum oxide crucible and sintered in a high-temperature furnace, the sintering air atmosphere flow rate was 3 L / min, the sintering temperature was 600°C, the holding time was 20 h, and the heating rate was 3°C / min, after sintering was completed, the material was taken out and then subjected to mechanical crushing, micron particle crushing, sand milling, nanoscale slurry, subsequent spray drying and jet milling to obtain a nanoscale powder, and the powder particle size D50 was 450 nm. Example 6

[0057] According to Li 1.3 Al 0.3 Ti 1.65 Zr 0.05 (PO4)3stoichiometric ratio of lithium carbonate, aluminum oxide, titanium dioxide, zirconium dioxide, and ammonium dihydrogen phosphate were weighed in total 4000 parts by mass, 240 parts by mass of natural cellulose was added, dry mixing was performed until uniform, then the material was added to a corundum crucible and sintered in a high-temperature furnace, the sintering air atmosphere flow rate was 3.2 L / min, the sintering temperature was 1000°C, the holding time was 4 h, and the heating rate was 6°C / min, after sintering was completed, the material was taken out and then subjected to mechanical crushing, micron particle crushing, sand milling, nanoscale slurry, subsequent air drying and jet milling to obtain a nanoscale powder, and the powder particle size D50 was 850 nm. Example 7

[0058] According to Li 1.55 Al 0.4 Ti 1.45 La 0.15(PO4)3stoichiometric ratio of lithium dihydrogen phosphate, alumina, titanium dioxide, lanthanum oxide, ammonium dihydrogen phosphate raw materials total 5000 parts by mass, add 500 parts by mass of chitosan, dry mixing to uniform, then the material is added to the alumina crucible in the high temperature furnace sintering, sintering air atmosphere flow is 3.5L / min, sintering temperature is 800℃, holding time is 12h, the heating rate is 5℃ / min, after sintering is completed the material is taken out in turn through mechanical crushing coarse micron particles, sand grinding broken to nano slurry, followed by spray drying and jet milling to obtain nano powder, the powder particle size D50 is 750nm. Example 8

[0059] According to Li 1.3 Al 0.3 Ti 1.7 (PO4)3stoichiometric ratio of lithium dihydrogen phosphate, alumina, titanium dioxide, lanthanum oxide, ammonium dihydrogen phosphate raw materials total 5000 parts by mass, add 500 parts by mass of chitosan, dry mixing to uniform, then the material is added to the alumina crucible in the high temperature furnace sintering, sintering air atmosphere flow is 3.5L / min, sintering temperature is 800℃, holding time is 12h, the heating rate is 5℃ / min, after sintering is completed the material is taken out in turn through mechanical crushing coarse micron particles, sand grinding broken to nano slurry, followed by spray drying and jet milling to obtain nano powder, the powder particle size D50 is 750nm. Example 9

[0060] According to Li 1.1 Al 0.1 Ti 1.9 (PO4)3stoichiometric ratio of lithium dihydrogen phosphate, alumina, titanium dioxide, lanthanum oxide, ammonium dihydrogen phosphate raw materials total 5000 parts by mass, add 500 parts by mass of chitosan, dry mixing to uniform, then the material is added to the alumina crucible in the high temperature furnace sintering, sintering air atmosphere flow is 3.5L / min, sintering temperature is 800℃, holding time is 12h, the heating rate is 5℃ / min, after sintering is completed the material is taken out in turn through mechanical crushing coarse micron particles, sand grinding broken to nano slurry, followed by spray drying and jet milling to obtain nano powder, the powder particle size D50 is 750nm. Example 10

[0061] According to Li 1.2 Al 0.2 Ti 1.8The lithium carbonate, alumina, titanium dioxide, and ammonium dihydrogen phosphate raw materials are weighed in stoichiometric ratio of (PO4)3, and the total amount is 1000 parts by mass. 3 parts by mass of tannic acid is added, and dry mixing is performed until uniform. Then, the material is added to a corundum boat and sintered in a high-temperature furnace. The sintering air atmosphere flow rate is 0.8 L / min, the sintering temperature is 800°C, the holding time is 4 h, and the heating rate is 6°C / min. After sintering is completed, the material is taken out, and then subjected to mechanical crushing, micron particle crushing, sand grinding, drying, and jet milling to obtain a nano powder. The powder particle size D50 is 300 nm. Example 11

[0062] According to Li 1.3 Al 0.3 Ti 1.7 The lithium carbonate, alumina, titanium dioxide, and ammonium dihydrogen phosphate raw materials are weighed in stoichiometric ratio of (PO4)3, and the total amount is 400 parts by mass. 40 parts by mass of xylan and 200 parts by mass of natural cellulose are added, and dry mixing is performed until uniform. Then, the material is added to a cordierite boat and sintered in a high-temperature furnace. The sintering air atmosphere flow rate is 5 L / min, the sintering temperature is 900°C, the holding time is 10 h, and the heating rate is 10°C / min. After sintering is completed, the material is taken out, and then subjected to mechanical crushing, micron particle crushing, sand grinding, drying, and jet milling to obtain a nano powder. The powder particle size D50 is 1000 nm. Example 12

[0063] According to Li 1.4 Al 0.4 Ti 1.6 The lithium carbonate, alumina, titanium dioxide, and ammonium dihydrogen phosphate raw materials are weighed in stoichiometric ratio of (PO4)3, and the total amount is 1000 parts by mass. 130 parts by mass of hyaluronic acid is added, and dry mixing is performed until uniform. Then, the material is added to a zirconia crucible and sintered in a high-temperature furnace. The sintering air atmosphere flow rate is 4 L / min, the sintering temperature is 850°C, the holding time is 16 h, and the heating rate is 5°C / min. After sintering is completed, the material is taken out, and then subjected to mechanical crushing, micron particle crushing, sand grinding, drying, and jet milling to obtain a nano powder. The powder particle size D50 is 900 nm. Example 13

[0064] According to Li 1.5 Al 0.5 Ge 1.5The lithium carbonate, alumina, germanium dioxide, and ammonium dihydrogen phosphate raw materials are weighed in a stoichiometric ratio of (PO4)3, and a total of 1000 parts by mass is added to 100 parts by mass of lignin. Dry mixing is performed until the mixture is uniform, and then the material is added to a corundum crucible for sintering in a high-temperature furnace. The sintering air atmosphere flow rate is 4 L / min, the sintering temperature is 850°C, the holding time is 6 h, and the temperature rise rate is 4°C / min. After sintering is completed, the material is removed and subjected to mechanical crushing, sand grinding, and subsequent drying and jet milling to obtain a nano-powder. The powder particle size D50 is 700 nm. Example 14

[0065] According to Li 1.5 Al 0.4 Ge 1.55 Mg 0.05 The lithium carbonate, alumina, germanium dioxide, and ammonium dihydrogen phosphate raw materials are weighed in a stoichiometric ratio of (PO4)3, and a total of 1000 parts by mass is added to 100 parts by mass of lignin. Dry mixing is performed until the mixture is uniform, and then the material is added to a corundum crucible for sintering in a high-temperature furnace. The sintering air atmosphere flow rate is 4 L / min, the sintering temperature is 850°C, the holding time is 6 h, and the temperature rise rate is 4°C / min. After sintering is completed, the material is removed and subjected to mechanical crushing, sand grinding, and subsequent drying and jet milling to obtain a nano-powder. The powder particle size D50 is 700 nm. Example 15

[0066] According to Li 1.3 Al 0.3 Ge 1.7 The lithium carbonate, alumina, germanium dioxide, and ammonium dihydrogen phosphate raw materials are weighed in a stoichiometric ratio of (PO4)3, and a total of 1000 parts by mass is added to 100 parts by mass of lignin. Dry mixing is performed until the mixture is uniform, and then the material is added to a corundum crucible for sintering in a high-temperature furnace. The sintering air atmosphere flow rate is 4 L / min, the sintering temperature is 850°C, the holding time is 6 h, and the temperature rise rate is 4°C / min. After sintering is completed, the material is removed and subjected to mechanical crushing, sand grinding, and subsequent drying and jet milling to obtain a nano-powder. The powder particle size D50 is 700 nm. Example 16

[0067] According to Li 1.2 Al 0.2 Ge 1.8The total amount of lithium carbonate, aluminum oxide, germanium oxide, and ammonium dihydrogen phosphate raw materials is 1000 parts by mass, 20 parts by mass of guar gum is added, dry mixing is performed until uniform, then the material is added to a mullite crucible for sintering in a high-temperature furnace, the sintering air atmosphere flow rate is 1.5 L / min, the sintering temperature is 750°C, the holding time is 12 h, the temperature rising rate is 2°C / min, after sintering is completed, the material is taken out, and then subjected to mechanical crushing, micron particle crushing, sand grinding to nanoscale slurry, and subsequent drying and jet milling to obtain a nanometer powder, the powder particle size D50 is 650 nm. Example 17

[0068] According to Li 1.1 Al 0.1 Ge 1.9 The total amount of lithium carbonate, aluminum oxide, germanium oxide, and ammonium dihydrogen phosphate raw materials is 1000 parts by mass, 80 parts by mass of tannic acid is added, dry mixing is performed until uniform, then the material is added to a magnesium oxide boat for sintering in a high-temperature furnace, the sintering air atmosphere flow rate is 2 L / min, the sintering temperature is 800°C, the holding time is 2 h, the temperature rising rate is 4°C / min, after sintering is completed, the material is taken out, and then subjected to mechanical crushing, micron particle crushing, sand grinding to nanoscale slurry, and subsequent drying and jet milling to obtain a nanometer powder, the powder particle size D50 is 350 nm. Comparative Example 1: sintering to prepare a LATP material without adding any additives

[0069] According to Li 1.3 Al 0.3 Ti 1.7 The total amount of lithium carbonate, aluminum oxide, titanium dioxide, and ammonium dihydrogen phosphate raw materials is 4000 parts by mass, dry mixing is performed until uniform, then the material is added to an aluminum oxide sagger for sintering in a high-temperature furnace, the sintering air atmosphere flow rate is 0.5 L / min, the sintering temperature is 1000°C, the holding time is 6 h, the temperature rising rate is 5°C / min. After sintering is completed, the material is taken out, and then subjected to mechanical crushing, micron particle crushing, sand grinding to nanoscale slurry, and subsequent spray drying and jet milling to obtain a nanometer powder, the powder particle size D50 is 600 nm. Comparative Example 2: using methyl cellulose biomass as a sintering aid

[0070] According to Li 1.3 Al 0.3 Ti 1.7(PO4)3 stoichiometrically weighed lithium carbonate, alumina, titanium dioxide, and ammonium dihydrogen phosphate totaling 4000 parts by weight, added 200 parts by weight of methylcellulose, and mixed uniformly using a dry method. The material was then added to an alumina crucible and sintered in a high-temperature furnace. The sintering air flow rate was 3 L / min, the sintering temperature was 850℃, the holding time was 6 h, and the heating rate was 4℃ / min. After sintering, the material was removed and subjected to mechanical crushing to coarsely break down micron-sized particles, followed by sand milling to break down into nano-slurry. Subsequently, it was spray-dried and air-jet pulverized to obtain nano-powder with a particle size D50 of 600 nm. Comparative Example 3: Using glycolic acid biomass as a sintering aid

[0071] According to Li 1.4 Al 0.4 Ti 1.6 (PO4)3 stoichiometrically weighed 4000 parts by weight of lithium carbonate, alumina, titanium dioxide, and ammonium dihydrogen phosphate raw materials, added 500 parts by weight of glycolic acid, and mixed uniformly using a dry method. The material was then added to a corundum sagger and sintered in a high-temperature furnace. The sintering air flow rate was 4 L / min, the sintering temperature was 850℃, the holding time was 6 h, and the heating rate was 4℃ / min. After sintering, the material was removed and subjected to mechanical crushing to coarsely break down micron-sized particles, followed by sand milling to break down into nano-slurry. Subsequently, it was spray-dried and air-jet pulverized to obtain nano-powder with a particle size D50 of 600 nm.

[0072] Performance testing: (1) Visual inspection: The appearance, expansion, and bonding of the sintered material were observed, and the results are shown in the figure. Figures 1-2 and Table 1; (2) The phase structure of the powders in the examples and comparative examples was determined by X-ray diffraction. The results are shown in the figure. Figure 3 ; (3) 0.8 g of the powders prepared in the above examples and comparative examples were weighed and pressed into ceramic green sheets with a diameter of 15 mm using a unidirectional tablet press at a pressure of 200 MPa. The green sheets were then sintered in an alumina crucible using master powder embedding. The sintering temperature was 900 °C, the holding time was 12 h, and the heating rate was 2 °C / min. After sintering, ceramic sheets were obtained. The ceramic sheets were polished flat on both sides and then sprayed with gold. The EIS impedance of the ceramic sheets was tested at 25 °C using an electrochemical workstation, and the ionic conductivity was calculated. The resulting Nyquist plot is shown in the figure. Figure 4 And Table 1.

[0073] Table 1

[0074] Depend on Figures 1-2It can be seen that the solid electrolyte material obtained by sintering according to the method of the present application does not expand, and the sticking of the material to the wall after sintering is obviously improved, and the material can be easily taken out in one piece; while the sintered material in the comparative examples cannot discharge the generated gas in time, resulting in a large pore in the material, especially in comparative example 1, the material expands to the outside of the sagger, affecting the collection of the material, and obvious sticking of the material to the wall can be observed, and the material in comparative examples 1 and 2 is difficult to take out.

[0075] By Figure 3 It can be seen that the LATP material obtained by sintering according to the method of the present application has high phase purity, which is consistent with the standard card PDF#35-0754. It can be seen that the sintering aid added in the method of the present application does not bring additional impurity phases to affect the purity of the material.

[0076] By combining Table 1 and Figure 4 It can be seen that the ionic conductivity of the electrolyte material obtained by sintering according to the method of the present application is not affected, and maintains high ionic conductivity.

[0077] In summary, the method of the present application solves the expansion problem of the existing solid electrolyte material in the sintering process by introducing a sintering aid, and at the same time solves the problem of sticking of the sintered material to the mold, improves the sintering amount and yield of the material per batch, and is beneficial to the mass industrial production of the material, reduces the cost and improves the convenience of subsequent processing; and the introduction of the sintering aid does not produce new impurity phases, and does not affect the ionic conductivity of the sintered material, and can sinter high-purity, easy-to-process, high-ionic-conductivity, low-cost solid electrolyte material.

[0078] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above embodiments, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A method for preparing a solid electrolyte material, characterized in that... The solid electrolyte precursor material is obtained by mixing and sintering with a sintering aid; the sintering aid is at least one of the biomass materials.

2. The preparation method according to claim 1, characterized in that: The solid electrolyte material includes at least one of lithium titanium aluminum phosphate and its doped materials, and lithium germanium aluminum phosphate and its doped materials.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the solid electrolyte precursor material to the sintering aid is 100:0.1 to 100:

15.

4. The preparation method according to claim 1, characterized in that: The biomass material is selected from at least one of lignin, tea polyphenols, tannic acid, hyaluronic acid, natural cellulose, chitosan, starch, guar gum, and xylan; the biomass material monomer contains at least one of hydroxyl, carboxyl, and aldehyde groups; and the total number of the above groups in the monomer is three or more.

5. The preparation method according to claim 1, characterized in that: The sintering temperature is 600~1000℃, the holding time is 2~20h, and the heating rate is 2~10℃ / min.

6. The preparation method according to claim 1, characterized in that: The sintering is carried out in an air atmosphere with an air flow rate of 0.5~5.0 L / min.

7. The preparation method according to claim 1, characterized in that: The particle size D50 of the prepared solid electrolyte material is 100~1000nm.

8. The preparation method according to claim 1, characterized in that: When the target solid electrolyte material is lithium titanium aluminum phosphate, the precursor material includes a lithium source, an aluminum source, a titanium source, and a phosphorus source; the titanium source includes at least one of titanium dioxide, titanium hydroxide, and titanium pyrophosphate; the lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium oxide, lithium oxalate, lithium acetate, and lithium dihydrogen phosphate; the aluminum source includes at least one of alumina, aluminum hydroxide, and aluminum nitrate; and the phosphorus source includes at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphorus pentoxide, and lithium dihydrogen phosphate.

9. The preparation method according to claim 1, characterized in that: When the target solid electrolyte material is lithium aluminum germanium phosphate, the precursor material includes a lithium source, an aluminum source, a germanium source, and a phosphorus source; the germanium source includes at least one of germanium dioxide and germanium tetrahydric hydroxide; the lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium oxide, lithium oxalate, lithium acetate, and lithium dihydrogen phosphate; the aluminum source includes at least one of aluminum oxide, aluminum hydroxide, and aluminum nitrate; and the phosphorus source includes at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphorus pentoxide, and lithium dihydrogen phosphate.

10. A solid electrolyte material, characterized in that... Prepared by the method according to any one of claims 1-9.

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