Garnet solid state electrolyte tabletting process

Abstract

The application belongs to the technical field of lithium batteries, and particularly relates to a garnet solid electrolyte tabletting process. The garnet solid electrolyte tabletting process comprises the following steps: (1) mixing LiOH, La2O3 and ZrO2, then wet ball milling, and then drying to obtain a mixed powder; (2) further grinding the mixed powder, then heat treating, and then screening to obtain an electrolyte powder; (3) uniformly mixing the electrolyte powder with a binder, then laying in a tabletting die, and then tabletting to obtain a garnet solid electrolyte tablet. The tabletting process is low in cost and simple in method, improves the forming degree of the solid electrolyte, and solves the defect that the solid electrolyte tablet is easy to break in the tabletting process.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery technology, specifically relating to a garnet-type solid electrolyte pressing process. Background Technology

[0002] Solid-state electrolytes represent a future trend in lithium-ion battery development, and solid-state lithium-ion batteries are widely recognized as a promising next-generation power battery technology. Many domestic and international lithium-ion battery companies have designated all-solid-state battery technology as a crucial next-generation technology reserve. Compared to liquid batteries, solid-state lithium batteries offer higher energy density, greater safety and reliability, and the potential for miniaturization. They also boast greater energy storage and faster charging compared to current liquid lithium batteries. Furthermore, because solid-state electrolytes are non-flammable, non-corrosive, non-volatile, and leak-proof, they will not ignite even at high temperatures, resulting in enhanced safety. Vehicles equipped with all-solid-state lithium batteries will experience increased range and faster charging speeds, significantly reducing the risk of fire.

[0003] Solid electrolytes are a crucial component in solid-state batteries, playing a pivotal role in overall battery performance. The preparation of solid electrolytes primarily involves mechanical ball milling and heat treatment, followed by tableting the resulting solid electrolyte powder using a tablet press. However, direct tableting using a press can easily lead to electrolyte tablet breakage, significantly hindering large-scale industrial production. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a garnet-type solid electrolyte tableting process that is low in cost, simple in method, improves the formability of solid electrolyte, and solves the defect of solid electrolyte tablets being fragile during the tableting process.

[0005] The garnet-type solid electrolyte tableting process of the present invention includes the following steps:

[0006] (1) LiOH, La2O3 and ZrO2 are mixed and then wet-milled, and then dried to obtain a mixed powder;

[0007] (2) The mixed powder is further ground, then heat-treated and sieved to obtain electrolyte powder;

[0008] (3) Add a binder to the electrolyte powder and mix evenly. Then spread it evenly in the tableting mold and press it to obtain a garnet-type solid electrolyte tablet.

[0009] In step (1), the molar ratio of LiOH, La2O3, and ZrO2 is (7.5-12):1.5:2. LiOH is in excess to compensate for the amount of Li volatilized at high temperatures.

[0010] In step (1), a planetary ball mill is used for wet ball milling, with agate balls as grinding balls, a ball-to-material ratio of (8-12):1, a ball milling speed of 250-300 rpm, and a ball milling time of 12-24 h. Isopropanol is used as a solvent during ball milling, and the amount of isopropanol used is 10-20% of the total mass of LiOH, La2O3, and ZrO2.

[0011] In step (2), the mixed powder is further ground to 700-800 mesh.

[0012] In step (2), during heat treatment, the temperature is increased to 850-950℃ at a rate of 2-5℃ / min and held for 8-12 hours.

[0013] In step (2), the electrolyte powder obtained by sieving has a particle size of less than 700 mesh.

[0014] In step (3), the pressure during tablet compression is 10-15 MPa, and the holding time is 2-5 min.

[0015] In step (3), the binder is terpineol, and the amount of binder added is 0.5-1% of the mass of the electrolyte powder.

[0016] In step (3), the molecular formula of the garnet-type solid electrolyte sheet prepared is Li7La3Zr2O 12 .

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The garnet-type solid electrolyte pressing process of the present invention uses terpineol as a binder to prepare garnet-type solid electrolytes with good formability, which improves the strength of solid electrolyte sheets and greatly reduces the thickness of solid electrolytes. This helps to improve the success rate of solid electrolyte pressing and provides the possibility for further preparation of high energy density all-solid-state batteries. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the ionic conductivity of the solid electrolyte prepared in Example 1 of the present invention;

[0020] Figure 2 This is a schematic diagram of the solid electrolyte sheet prepared in Example 1 of the present invention;

[0021] Figure 3 This is a schematic diagram of the solid electrolyte sheet prepared in Comparative Example 1 of the present invention;

[0022] Figure 4 This is a schematic diagram of the solid electrolyte sheet prepared in Comparative Example 2 of the present invention;

[0023] Figure 5This is a schematic diagram of the solid electrolyte sheet prepared in Comparative Example 3 of the present invention;

[0024] Figure 6 This is a schematic diagram of the solid electrolyte sheet prepared in Comparative Example 4 of the present invention. Detailed Implementation

[0025] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto. Any changes made to the technical solutions of the present invention by those skilled in the art should fall within the scope of protection of the present invention.

[0026] Example 1

[0027] A garnet-type solid electrolyte tableting process includes the following steps:

[0028] (1) LiOH, La2O3 and ZrO2 were mixed in a molar ratio of 7.5:1.5:2, with LiOH in excess by 20% to compensate for the amount of Li volatilized at high temperature; after mixing, the mixture was placed in a planetary ball mill with agate balls as grinding balls at a ball-to-material ratio of 8:1, and isopropanol accounting for 10% of the total mass of LiOH, La2O3 and ZrO2 was added for wet ball milling at a speed of 250 rpm for 12 h; after ball milling, the mixture was dried at 80℃ for 8 h to obtain a white mixed powder.

[0029] (2) Grind the mixed powder to 700 mesh, then put it into a muffle furnace, set the heating rate to 2℃ / min, heat to 850℃, keep it at 850℃ for 8 hours, cool it naturally to room temperature, and sieve it to obtain electrolyte powder below 700 mesh.

[0030] (3) Take 0.5g of electrolyte powder, add 0.5% of terpineol by weight of electrolyte powder, grind thoroughly and spread evenly in the tablet press mold, press with 10Mpa pressure, hold pressure for 2min and take out, the tableting is completed, and garnet-type solid electrolyte tablets are obtained.

[0031] Example 2

[0032] A garnet-type solid electrolyte tableting process includes the following steps:

[0033] (1) LiOH, La2O3 and ZrO2 were mixed in a molar ratio of 8:1.5:2, with LiOH in excess by 20% to compensate for the amount of Li volatilized at high temperature; after mixing, the mixture was placed in a planetary ball mill with agate balls as grinding balls at a ball-to-material ratio of 9:1, and 12% isopropanol (based on the total mass of LiOH, La2O3 and ZrO2) was added for wet ball milling at a speed of 280 rpm for 16 h; after ball milling, the mixture was dried at 80 °C for 8 h to obtain a white mixed powder.

[0034] (2) Grind the mixed powder further to 750 mesh, then put it into a muffle furnace, set the heating rate to 3℃ / min, heat to 900℃, keep it at 900℃ for 10h, cool it naturally to room temperature, and sieve it to obtain electrolyte powder below 800 mesh.

[0035] (3) Take 0.5g of electrolyte powder, add 0.6% of terpineol by weight of electrolyte powder, grind thoroughly and spread evenly in the tablet press mold, press with 12Mpa pressure, hold pressure for 3min and take out, the tableting is completed, and garnet-type solid electrolyte tablets are obtained.

[0036] Example 3

[0037] A garnet-type solid electrolyte tableting process includes the following steps:

[0038] (1) LiOH, La2O3 and ZrO2 were mixed in a molar ratio of 9:1.5:2, with LiOH in excess by 20% to compensate for the amount of Li volatilized at high temperature; after mixing, the mixture was placed in a planetary ball mill with agate balls as grinding balls at a ball-to-material ratio of 10:1, and 14% isopropanol (based on the total mass of LiOH, La2O3 and ZrO2) was added for wet ball milling at a speed of 300 rpm for 18 h; after ball milling, the mixture was dried at 80 °C for 8 h to obtain a white mixed powder.

[0039] (2) Grind the mixed powder to 800 mesh, then put it into a muffle furnace, set the heating rate to 2℃ / min, heat to 900℃, keep it at 900℃ for 12h, cool it naturally to room temperature, and sieve it to obtain electrolyte powder below 700 mesh.

[0040] (3) Take 0.5g of electrolyte powder, add 0.7% of terpineol by weight of electrolyte powder, grind thoroughly and spread evenly in the tablet press mold, press with 15Mpa pressure, hold pressure for 4min and take out, the tableting is completed, and garnet-type solid electrolyte tablets are obtained.

[0041] Example 4

[0042] A garnet-type solid electrolyte tableting process includes the following steps:

[0043] (1) LiOH, La2O3 and ZrO2 were mixed in a molar ratio of 10:1.5:2, with LiOH in excess by 20% to compensate for the amount of Li volatilized at high temperature; after mixing, the mixture was placed in a planetary ball mill with agate balls as grinding balls at a ball-to-material ratio of 11:1, and 16% isopropanol (based on the total mass of LiOH, La2O3 and ZrO2) was added for wet ball milling at a speed of 300 rpm for 20 h; after ball milling, the mixture was dried at 80℃ for 8 h to obtain a white mixed powder.

[0044] (2) Grind the mixed powder further to 800 mesh, then put it into a muffle furnace, set the heating rate to 2℃ / min, heat to 950℃, keep it at 950℃ for 12h, cool it naturally to room temperature, and sieve it to obtain electrolyte powder below 800 mesh.

[0045] (3) Take 0.5g of electrolyte powder, add 0.8% of terpineol by weight of electrolyte powder, grind thoroughly and spread evenly in the mold of the tablet press, press the tablet with 15Mpa pressure, hold the pressure for 5min and take it out. The tablet pressing is completed and garnet-type solid electrolyte tablets are obtained.

[0046] Example 5

[0047] A garnet-type solid electrolyte tableting process includes the following steps:

[0048] (1) LiOH, La2O3 and ZrO2 were mixed in a molar ratio of 11:1.5:2, with LiOH in excess by 20% to compensate for the amount of Li volatilized at high temperature; after mixing, the mixture was placed in a planetary ball mill with agate balls as grinding balls at a ball-to-material ratio of 12:1, and 18% isopropanol (based on the total mass of LiOH, La2O3 and ZrO2) was added for wet ball milling at a speed of 300 rpm for 22 h; after ball milling, the mixture was dried at 80℃ for 8 h to obtain a white mixed powder.

[0049] (2) Grind the mixed powder further to 800 mesh, then put it into a muffle furnace, set the heating rate to 2℃ / min, heat to 950℃, keep it at 950℃ for 12h, cool it naturally to room temperature, and sieve it to obtain electrolyte powder below 700 mesh.

[0050] (3) Take 0.5g of electrolyte powder, add 0.9% of terpineol by weight of electrolyte powder, grind thoroughly and spread evenly in the mold of the tablet press, press the tablet with 15Mpa pressure, hold the pressure for 5min and take it out. The tablet pressing is completed and garnet-type solid electrolyte tablets are obtained.

[0051] Example 6

[0052] (1) LiOH, La2O3 and ZrO2 were mixed in a molar ratio of 12:1.5:2, with LiOH in excess by 20% to compensate for the amount of Li volatilized at high temperature; after mixing, the mixture was placed in a planetary ball mill with agate balls as grinding balls at a ball-to-material ratio of 12:1, and 20% isopropanol of the total mass of LiOH, La2O3 and ZrO2 was added for wet ball milling at a speed of 300 rpm for 24 h; after ball milling, the mixture was dried at 80℃ for 8 h to obtain a white mixed powder.

[0053] (2) Grind the mixed powder further to 800 mesh, then put it into a muffle furnace, set the heating rate to 2℃ / min, heat to 950℃, keep it at 950℃ for 12h, cool it naturally to room temperature, and sieve it to obtain electrolyte powder below 800 mesh.

[0054] (3) Take 0.5g of electrolyte powder, add 1% of terpineol by weight of electrolyte powder, grind thoroughly and spread evenly in the mold of the tablet press, press the tablet with 15Mpa pressure, hold the pressure for 5min and take it out. The tablet pressing is completed and garnet-type solid electrolyte tablets are obtained.

[0055] Comparative Example 1

[0056] The only difference between this comparative example and Example 1 is that the binder terpineol is not added during tableting in step (3), and the product obtained after tableting is as follows: Figure 3 As shown, the tablet press fails to form tablets; the tablets remain in powder form.

[0057] Comparative Example 2

[0058] The only difference between this comparative example and Example 1 is that, during tableting in step (3), the binder terpineol is replaced with an equal mass of binder polyvinyl alcohol. The product obtained after tableting is as follows: Figure 4 As shown, the electrolyte sheet is prone to breakage.

[0059] Comparative Example 3

[0060] The only difference between this comparative example and Example 1 is that the molar ratio of LiOH, La2O3, and ZrO2 in step (1) is 7:1.5:2, and the resulting product is as follows: Figure 5 As shown, at high temperatures, a certain amount of Li volatilizes, resulting in a rough surface on the final electrolyte sheet product.

[0061] Comparative Example 4

[0062] The only difference between this comparative example and Example 1 is that the heat preservation time in step (2) is 6 hours, and the resulting product is as follows: Figure 6 As shown, electrolyte sheet products are prone to cracking after the heat preservation time is shortened.

Claims

1. A garnet-type solid electrolyte tableting process, characterized in that, It consists of the following steps: (1) LiOH, La2O3 and ZrO2 are mixed and then wet-milled, and then dried to obtain a mixed powder; (2) Grind the mixed powder further to 700-800 mesh, then heat treat and sieve to obtain electrolyte powder with a particle size of less than 700 mesh; during heat treatment, heat to 850-950℃ at a rate of 2-5℃ / min and keep warm for 8-12h. (3) Add binder to electrolyte powder and mix evenly. Then spread it evenly in tableting mold. The pressure during tableting is 10-15 MPa and the holding time is 2-5 min. After tableting, garnet-type solid electrolyte tablets with the molecular formula Li7La3Zr2O are obtained. 12 The binder is terpineol; the amount of binder added is 0.5-1% of the mass of the electrolyte powder. In the above steps, only one heat treatment is performed in step (2), and no secondary sintering treatment is performed after tableting; The molar ratio of LiOH, La2O3, and ZrO2 is (7.5-12):1.5:2; In step (1), a planetary ball mill is used for wet ball milling, with agate balls as grinding balls, a ball-to-material ratio of (8-12):1, a ball milling speed of 250-300 rpm, and a ball milling time of 12-24 h. Isopropanol is used as a solvent during ball milling, and the amount of isopropanol used is 10-20% of the total mass of LiOH, La2O3, and ZrO2.

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