Preparation method of low-cost and easy-to-process oxide solid electrolyte

Abstract

The invention belongs to the technical field of solid-state batteries, and discloses a preparation method of a low-cost and easy-to-process oxide solid-state electrolyte, which comprises the following steps: uniformly mixing a lithium source, a lanthanum source, a zirconium source and a tantalum source according to a certain proportion, and ball-milling in an organic solvent for a certain time to obtain a lithium-lanthanum-zirconium-tantalum mixture; and transferring the dried material into a muffle furnace, and calcining according to a certain sintering system. Mixing the sintered powder with a certain amount of surface modifier to perform low-temperature surface treatment, and performing reconstruction modification on functional groups on the surface of the material while removing redundant residual alkali on the surface, so that the surface of the prepared oxide solid electrolyte material has rich bipolar groups; the specific electrostatic steric hindrance stabilizing effect can be beneficial for the material to form stable dispersed slurry in the later stage, and then the uniform electrolyte membrane is processed and formed. The method is simple and convenient in preparation process, the problem that the oxide solid electrolyte is difficult to process at present is greatly solved, and subsequent macro industrial application of the oxide solid electrolyte is facilitated.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid-state batteries and relates to a preparation method of an easily processed oxide solid-state electrolyte. BACKGROUND

[0002] With the wide application of lithium ion batteries in the field of power batteries and energy storage, the market has higher requirements for the energy density and rapid charge-discharge performance of lithium ion batteries, but this has led to increasing safety hazards. The use of non-flammable or less flammable solid-state electrolyte in all-solid-state lithium ion batteries instead of flammable organic electrolyte in traditional batteries can effectively solve the safety problem of lithium ion batteries and improve the use temperature range, cycle life and energy density of the battery.

[0003] Oxide solid-state electrolytes have been widely studied due to their high stability and excellent ion conductivity, and are one of the main development routes for currently commercially available all-solid-state batteries. Currently, oxide solid-state electrolytes mainly have the problems of poor solid-solid interface contact and high difficulty in later processing. The interface problem leads to poor performance of assembled all-solid-state batteries, and the high brittleness of the material leads to the fact that the existing oxide electrolyte can only exist in the laboratory button cell or small soft package battery, which is still far from real commercial use. At present, in view of the difficulty in processing the oxide solid-state electrolyte, the patent 202411517991.0 Solid-state electrolyte composite film and its preparation method, solid-state battery proposes a method of combining polymer electrolyte and oxide electrolyte, which can process the electrolyte into a film to a certain extent, but also brings some problems. The combination of the polymer affects the high-voltage characteristics of the overall electrolyte, and does not fundamentally solve the problem of the difficulty in processing the oxide electrolyte itself. SUMMARY

[0004] To solve the above problems, the application provides a method for preparing an easily processed oxide solid-state electrolyte, which removes excess residual alkali from the surface through low-temperature surface treatment and modifies the functional groups on the surface of the material, so that the surface of the prepared oxide solid-state electrolyte material has rich bipolar groups, and the unique electrostatic steric stabilization effect can help the material to form a stable dispersion slurry in the later stage, and then process to form a uniform electrolyte film. The surface modified groups can effectively improve the poor interface contact between the electrode material and the oxide solid-state electrolyte, and the performance of the assembled battery is greatly improved compared with the traditional scheme. The preparation method is simple, and greatly solves the current difficulty in processing the oxide solid-state electrolyte, which is conducive to the subsequent macro-scale industrial application of the oxide solid-state electrolyte.

[0005] The technical scheme of the application is as follows:

[0006] A preparation method of a low-cost and easily processed oxide solid-state electrolyte, comprising the following steps:

[0007] (1) uniformly mixing a lithium source, a lanthanum source, a zirconium source and a tantalum source according to a proportion, adding a ball milling aid to perform wet ball milling, and then transferring to a muffle furnace to perform calcination, thereby obtaining a high-temperature ceramicized oxide solid electrolyte material;

[0008] (2) performing crushing and refining on the high-temperature ceramicized oxide solid electrolyte material, and then adding a surface modifier to perform ball milling mixing again;

[0009] (3) transferring the mixed material to a tube furnace to perform sintering under a nitrogen atmosphere, thereby obtaining an oxide solid electrolyte.

[0010] In step (1), the lithium source is one or a mixture of two or more of lithium hydroxide, lithium carbonate and lithium nitrate.

[0011] In step (1), the lanthanum source is one or a mixture of two or more of lanthanum oxide, lanthanum nitrate and lanthanum carbonate.

[0012] In step (1), the zirconium source is one or a mixture of two or more of zirconium oxide, zirconium chloride and zirconium sulfate.

[0013] In step (1), the tantalum source is one or a mixture of two or more of tantalum oxide, tantalum sulfate and tantalum phosphate.

[0014] In step (1), the ball milling aid is one or a mixture of two or more of ethanol, isopropyl alcohol and methanol.

[0015] In step (1), the molar ratio of the lithium source, the lanthanum source, the zirconium source and the tantalum source is 4-4.6:1:1:0.15-0.2; the mass ratio of the ball milling aid to the total mass of the four metal sources is 1:1.2-2, and the ball milling time is 4-24h.

[0016] In step (1), the calcination temperature is 800-1300℃, the calcination time is 8-36h, and the heating rate is 2-10℃ / min.

[0017] In step (2), the surface modifier is one or a mixture of two or more of citric acid, ascorbic acid, polystyrene acid, oxalic acid and ethanedioic acid tetraethyl acid.

[0018] In step (2), the surface modifier is added in an amount of 5‰-2% of the mass of the high-temperature ceramicized oxide solid electrolyte material obtained in step (1).

[0019] In step (3), the sintering temperature is 150-500℃, and the sintering time is 0.5-5h.

[0020] The beneficial effects of the present application are as follows:

[0021] (1) The surface of the oxide solid electrolyte material prepared by low-temperature surface modification has abundant bipolar groups, and the unique electrostatic steric stabilization effect can facilitate the formation of stable dispersed slurry of the material in the later stage, and then process to form a uniform electrolyte film. The preparation process is simple, and greatly solves the current processing problem of oxide solid electrolyte, which is beneficial to the subsequent macro-scale industrial application of oxide solid electrolyte.

[0022] (2) The unique bipolar groups on the surface of the surface-modified oxide electrolyte can also effectively improve the interface contact between the electrode material and the solid electrolyte, thereby ensuring the performance of the assembled all-solid-state lithium ion battery. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The XRD pattern of the oxide solid electrolyte prepared in the present application.

[0024] Figure 2 The electrochemical performance diagram of the oxide solid electrolyte prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0025] The specific embodiments of the present application will be further described in combination with the drawings and technical solutions.

[0026] The oxide solid electrolyte provided by the embodiment of the present application is modified by a surface modifier on the surface of the electrolyte, and by adjusting the proportion and temperature of the modifier, the bipolar functional groups on the surface of the electrolyte can be precisely controlled, so that the modified electrolyte material has the characteristics of easy processing and high ionic conductivity.

[0027] In the preferred embodiment of the present application, the lithium source is a mixture of one or more of lithium hydroxide, lithium carbonate and lithium nitrate; the lanthanum source is a mixture of one or more of lanthanum oxide, lanthanum nitrate and lanthanum carbonate; and the zirconium source is a mixture of one or more of zirconium oxide, zirconium chloride and zirconium sulfate.

[0028] In the preferred embodiment of the present application, the ball milling aid for uniform ball milling is a mixture of one or more of ethanol, isopropanol and methanol, and the proportion added is in the range of ball milling aid: previous material = 1:1.2~1:2, and the ball milling time is 4~24h.

[0029] In the preferred embodiment of the present application, the sintering temperature for preparing the oxide electrolyte precursor is 800~1300℃, the sintering time is 8~36h, and the heating rate is 2~10℃ / min.

[0030] In the preferred embodiment of the present application, the modifier for the surface modification treatment is one or more of a mixture of citric acid, ascorbic acid, polystyrene acid, oxalic acid and ethanedioic acid, the added proportion is 5‰-2%, the selected modification temperature is 150-500 DEG C, and the sintering time is 0.5-12h.

[0031] Example 1

[0032] Step 1: first, weigh 27.847g of lithium hydroxide, 44.961g of lanthanum oxide, 17.002g of zirconium oxide and 62.355g of tantalum oxide, transfer them to a ball mill jar, add 160g of ethanol as an auxiliary agent for wet ball milling for 8h, transfer the dried material to a muffle furnace and heat it to 900 DEG C at a rate of 5 DEG C / min and keep it for 12h;

[0033] Step 2: add 5‰ of citric acid to the sintered precursor, and ball mill for 5min to make it uniformly mixed.

[0034] Step 3: transfer the mixed material to a tube furnace and keep it at 300 DEG C for 4h under nitrogen atmosphere to obtain the final material.

[0035] Example 2

[0036] Step 1: first, weigh 36.45g of lithium carbonate, 57.88g of lanthanum nitrate, 17.002g of zirconium oxide and 62.355g of tantalum oxide, transfer them to a ball mill jar, add 230g of isopropanol as an auxiliary agent for wet ball milling for 12h, transfer the dried material to a muffle furnace and heat it to 900 DEG C at a rate of 5 DEG C / min and keep it for 12h;

[0037] Step 2: add 1% of ascorbic acid to the sintered precursor, and ball mill for 10min to make it uniformly mixed.

[0038] Step 3: transfer the mixed material to a tube furnace and keep it at 350 DEG C for 6h under nitrogen atmosphere to obtain the final material.

[0039] Example 3

[0040] Step 1: first, weigh 27.847g of lithium hydroxide, 44.961g of lanthanum oxide, 17.002g of ZrO2 and 62.355g of Ta2O5, transfer them to a ball mill jar, add 160g of ethanol as an auxiliary agent for wet ball milling for 8h, transfer the dried material to a muffle furnace and heat it to 700 DEG C at a rate of 5 DEG C / min and keep it for 12h;

[0041] Step 2: add 2% of citric acid to the sintered precursor, and ball mill for 5min to make it uniformly mixed.

[0042] Step 3: The mixed material was transferred to a tube furnace and kept at 200°C for 4h under nitrogen atmosphere to obtain the final material.

[0043] Example 4

[0044] Step 1: First, 36.45g of lithium carbonate, 68.88g of lanthanum carbonate, 17.002g of zirconium oxide and 62.355g of tantalum oxide were weighed and transferred to a ball mill jar, 190g of isopropyl alcohol was added as an aid for wet ball milling for 8h, and the dried material was transferred to a muffle furnace and heated to 1200°C at a rate of 5°C / min and kept for 6h.

[0045] Step 2: 1% of oxalic acid based on the total mass was added to the calcined precursor and ball milled for 5min to mix uniformly.

[0046] Step 3: The mixed material was transferred to a tube furnace and kept at 350°C for 8h under nitrogen atmosphere to obtain the final material.

[0047] Example 5

[0048] Step 1: First, 27.847g of lithium hydroxide, 57.88g of lanthanum nitrate, 17.002g of zirconium oxide and 62.355g of tantalum oxide were weighed and transferred to a ball mill jar, 190g of isopropyl alcohol was added as an aid for wet ball milling for 12h, and the dried material was transferred to a muffle furnace and heated to 1000°C at a rate of 10°C / min and kept for 9h.

[0049] Step 2: 5‰ of oxalic acid based on the total mass was added to the calcined precursor and ball milled for 15min to mix uniformly.

[0050] Step 3: The mixed material was transferred to a tube furnace and kept at 250°C for 4h under nitrogen atmosphere to obtain the final material.

[0051] Comparative Example 1

[0052] First, 27.847g of lithium hydroxide, 57.88g of lanthanum nitrate, 17.002g of zirconium oxide and 62.355g of tantalum oxide were weighed and transferred to a ball mill jar, 190g of isopropyl alcohol was added as an aid for wet ball milling for 12h, and the dried material was transferred to a muffle furnace and heated to 1000°C at a rate of 10°C / min and kept for 9h.

[0053] Table 1

[0054]

[0055] It can be seen from the data in Table 1 that the oxide electrolyte of Comparative Example 1 obviously settled in 30 min in the organic solvent NMP, while the oxide solid electrolytes in Examples 1-5 can achieve stable dispersion in the organic solvent NMP for more than 36 h, and the stable dispersion time of Example 5 is as long as 72 h. This result shows that the processability of the oxide solid electrolyte is significantly improved after surface modification treatment, which provides a good foundation for subsequent coating and film forming. The difference in stable dispersion time of each example is mainly caused by the difference in the selected modifier and modification conditions. Different modifiers have different contents of polar groups, and the modification treatment temperature and time result in the difference in the surface groups of the modified oxide electrolyte.

Claims

1. A method of producing a low cost, easy to process oxide solid state electrolyte, characterized by, The steps are as follows: (1) uniformly mixing a lithium source, a lanthanum source, a zirconium source and a tantalum source according to a proportion, adding a ball milling aid to perform wet ball milling, and then transferring to a muffle furnace to perform calcination, so as to obtain a high-temperature ceramicized oxide solid electrolyte material; (2) adding a surface modifier to the high-temperature ceramicized oxide solid electrolyte material after crushing and refining, and then performing ball milling mixing again; (3) transferring the mixed material to a tube furnace to perform sintering under a nitrogen atmosphere, so as to obtain an oxide solid electrolyte.

2. The preparation method according to claim 1, characterized in that, in step (1), the lithium source is one or a mixture of two or more of lithium hydroxide, lithium carbonate and lithium nitrate; the lanthanum source is one or a mixture of two or more of lanthanum oxide, lanthanum nitrate and lanthanum carbonate; the zirconium source is one or a mixture of two or more of zirconium oxide, zirconium chloride and zirconium sulfate; the tantalum source is one or a mixture of two or more of tantalum oxide, tantalum sulfate and tantalum phosphate; the ball milling aid is one or a mixture of two or more of ethanol, isopropyl alcohol and methanol.

3. The preparation method according to claim 2, characterized in that, in step (1), the molar ratio of the lithium source, the lanthanum source, the zirconium source and the tantalum source is 4-4.6:1:1:0.15-0.2; the mass ratio of the ball milling aid to the total mass of the four metal sources is 1:1.2-2, and the ball milling time is 4-24 h.

4. The preparation method according to claim 3, characterized in that, in step (1), the calcination temperature is 800-1300℃, the calcination time is 8-36 h, and the heating rate is 2-10℃ / min.

5. The preparation method according to claim 4, characterized in that, in step (2), the surface modifier is one or a mixture of two or more of citric acid, ascorbic acid, polystyrene acid, oxalic acid and ethanedioic acid tetraethyl acid.

6. The preparation method according to claim 5, characterized in that, in step (2), the surface modifier is added in an amount of 5‰-2% of the mass of the high-temperature ceramicized oxide solid electrolyte material obtained in step (1).

7. The preparation method according to claim 6, characterized in that, in step (3), the sintering temperature is 150-500℃, and the sintering time is 0.5-5 h.

8. An oxide solid electrolyte prepared by the preparation method of any one of claims 1-7.

9. A lithium-ion battery, characterized by An oxide solid electrolyte material as claimed in claim 8.

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