CN116111183A - Preparation method of solid ceramic electrolyte membrane applied to all-solid lithium battery - Google Patents

Abstract

The invention relates to the field of battery technology, in particular to a method for preparing a solid ceramic electrolyte membrane applied to an all-solid lithium battery, which comprises the following steps: ball milling and sieving the prepared electrolyte powder, and then sequentially adding a dispersant to increase the Plasticizers, binders, etc. are ball milled to obtain a uniform cast slurry; cast it, and control the height of the scraper at 5μm-1mm to obtain a cast film; the cast film dried at room temperature is laminated and hot-pressed , to obtain a plain embryo; the plain embryo is placed in a muffle furnace and sintered in stages to obtain a dense ceramic electrolyte membrane. The water-based tape casting process adopted in the present invention uses water as the only solvent, which is safe, green, and environmentally friendly, and the stability of the slurry is good. The prepared ceramic electrolyte membrane has excellent sintering ability, ion conductivity and mechanical properties; the process is simple , and the production cost is low, it is easy to realize large-scale production, and can be used in solid-state lithium battery, fuel cell technology and other fields.

Description

A preparation method of a solid ceramic electrolyte membrane applied to an all-solid lithium battery

technical field

The invention relates to the technical field of fuel cells, in particular to a method for preparing a solid ceramic electrolyte membrane applied to an all-solid lithium battery.

Background technique

In recent years, due to the development of electric vehicles, the demand for large-capacity energy storage in human life is increasing day by day, and the research on lithium batteries has once again sparked an upsurge. Secondary lithium batteries with high safety, high power, large capacity and long cycle life have become a new direction for the development of lithium batteries. After years of development, the output voltage and energy density of lithium-ion batteries are significantly higher than other types of batteries. In addition to meeting the basic needs of long battery life and high-power charging and discharging, lithium batteries also have to be safe. Due to the flammability of the organic electrolyte and the easy generation of lithium dendrites in the current commercial lithium-ion batteries, once the battery is short-circuited, a large amount of heat will be released inside, which will cause the organic electrolyte to burn and cause serious safety accidents. In order to improve the safety of lithium batteries and further expand their application scenarios, it is urgent to develop lithium batteries with good safety, high rate performance, and long cycle life. All-solid-state lithium batteries based on solid-state electrolytes are expected to solve the safety problems of traditional liquid lithium-ion batteries. Compared with traditional liquid lithium-ion batteries, the most prominent advantages of all-solid-state batteries are high safety and high energy density. Therefore, solid-state electrolytes have become the first choice for researchers to study lithium-ion batteries.

NASICON type lithium ion electrolyte, ^the simplified structure is LiA ₂ (PO ₄ ) ₃ , where A is tetravalent cations such as Ti ⁴⁺ , Zr ⁴⁺ , Ge ⁴⁺ , Hf ⁴⁺ , Sn ⁴⁺ , and its skeleton structure is composed of AO ₆ octahedron and PO ₄ tetrahedron are jointly formed, each AO ₆ octahedron is connected with 6 PO ₄ tetrahedrons, each PO ₄ tetrahedron is connected with 4 AO ₆ octahedrons, and these polyhedrons are connected by mutual contact The oxygen atoms at the top corners are connected to form a three-dimensional staggered skeleton structure, forming an ion transport channel that is conducive to Li ⁺ transport, and using low-priced cations (such as Al, Ga, In, Sc, Y, La) without changing the crystal phase structure. , Cr, Fe, Zn, Ca, etc.) to replace part of A ⁴⁺ , on the one hand, the size of the ion transport channel can be changed to match the size of the Li ⁺ radius, and on the other hand, more mobile Li ⁺ can be introduced due to the charge balance , thereby improving the ionic conductivity of the material in two ways. Among these materials, lithium aluminum titanium phosphate (LATP), lithium aluminum zirconium phosphate (LAZP) and lithium aluminum germanium phosphate (LAGP) have the most outstanding performance.

At present, the common forming methods of ceramic electrolyte materials include plasma spraying method, sputtering method, hot and cold pressing method, tape casting method, etc. Among them, tape casting method is widely used because it is suitable for commercial mass production. The tape casting process includes water-based and non-water-based casting. The membrane prepared by non-water-based casting has uniform structure and good flexibility, and has been used in industrial production for many years. However, the non-water-based casting process needs to use a large amount of toxic organic substances as solvents, which has high production costs, causes environmental pollution after discharge, and is harmful to human health. Compared with this, water-based casting uses water as the only solvent, which has low cost, no pollution, and is convenient for industrial production. Therefore, it has become a future trend to study the casting technology using water as a solvent instead of organic solvents.

Contents of the invention

In order to solve the problems of non-environmental protection and high cost of the existing organic casting slurry, the invention discloses a preparation method of a solid ceramic electrolyte membrane applied to an all-solid lithium battery.

In order to achieve the above technical effects, the present invention is achieved through the following technical solutions: a method for preparing a solid ceramic electrolyte membrane applied to an all-solid lithium battery, characterized in that it comprises the following steps:

Step1: Prepare water-based casting slurry;

Step2: casting;

Step3: hot pressing;

Step4: Sintering.

Further, in the Step1, add an appropriate amount of deionized water to a certain amount of electrolyte powder and mix evenly, add a pre-configured dispersant and perform a ball mill; add a plasticizer for a second ball mill; add a binder The aqueous solution is ball-milled three times; the ball-milled slurry is subjected to vacuum degassing at 20-80kpa for 5-15 minutes to prepare a water-based casting slurry;

In the Step2, the prepared electrolyte slurry is sieved to remove impurities or large particles, and then cast on high-temperature glassine paper at a speed of 8-15 cm/min using an automatic coating machine, wherein the height of the scraper is 5 μm- 1mm, to prepare electrolyte casting membrane;

In Step 3, cut the tape that has been dried at room temperature for 24 hours into the required size and peel it off, laminate with different layers according to the required thickness, and then hot press at 60-120°C for 5-30 minutes to prepare ceramic elements Embryo;

In the Step4, the specific process of placing the ceramic green body in a muffle furnace for heating and heat preservation is to raise the temperature to 300-600°C at a heating rate of 1-5°C/min, keep it warm for 1-12 hours, and then heat it up at a temperature of 1-5°C. Raise the temperature to 700~1200℃ at a heating rate of /min, and keep it warm for 1~12h.

Further, in the Step1, based on the weight of the electrolyte powder, the mass percentage of the electrolyte powder (solid content) is 30% to 60%, the content of the solvent is 30% to 45%, and the content of the dispersant The content of the binder is 4% to 8%, the content of the plasticizer is 3% to 10%, and the content of the defoaming agent is 0.3% to 1%.

Further, the electrolyte powder is a NASICON type lithium ion electrolyte, and its simplified structure is LiA ₂ (PO ₄ ) ₃ , where A includes but not limited to Ti ⁴⁺ , Zr ⁴⁺ , Ge ⁴⁺ , Hf ⁴⁺ , One of the tetravalent cations of Sn ⁴⁺ , the electrolyte powder adopts one or more of LATP powder materials, LAZP powder materials, and LAGP powder materials;

The LATP powder material is one or more of Li _1+x Al _x Ti _2-x (PO ₄ ) ₃ (where x is between 0.1 and 0.5);

The LAZP powder material is one or more of Li _1+x Al _x Zr _2-x (PO ₄ ) ₃ (where x is between 0.1 and 0.5);

The LAGP powder material is one or more of Li _1+x Al _x Ge _2-x (PO ₄ ) ₃ (where x is between 0.1 and 0.5).

Further, the dispersant is triethanolamine, sodium polyacrylate, triethyl phosphate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium hexametaphosphate, polyacrylic acid, cetyl trimethyl One or more of ammonium bromide, polyethylene glycol, potassium polyacrylate, octylphenol polyoxyethylene ether or sulfonate fluorine dispersant.

Further, the binder is polyvinylidene fluoride, styrene-butadiene latex, styrene-acrylic latex, polyvinyl alcohol, polyvinyl butyral, sodium alginate, polyacrylamide, polymethyl methacrylate, butyl acrylate Grease, ethylene-vinyl acetate copolymer, polyvinyl acetate, polyurethane, hydroxyethyl cellulose, methyl hydroxyethyl cellulose, sodium carboxymethyl cellulose, polyacrylamide, polyethylene oxide and polytetrafluoroethylene one or more of them.

Further, the plasticizer is dibutyl phthalate, butyl benzyl phthalate, butyl stearate, dimethyl phthalate, tricresyl phosphate, polyethylene glycol, rosin One or more of methyl ester, polyol, dimethyl phthalate, triethylene glycol, tributyl phosphate, and polyalkylene glycol.

Further, the solvent is deionized water.

Beneficial effect

The water-based tape casting process adopted in the present invention uses water as the only solvent, which is safe, green, and environmentally friendly. The stability of the slurry is good, and the prepared ceramic electrolyte membrane has excellent sintering ability, ion conductivity and mechanical properties; the process is simple , and the production cost is low, and it is easy to realize large-scale production, and can be used in solid-state lithium battery, fuel cell technology and other fields.

The ceramic electrolyte membrane prepared by water-based casting in the present invention has large area and good uniformity; and to a certain extent, the sintering ability, ion conductivity and mechanical properties of the ceramic electrolyte membrane are improved; water is used as the only solvent to effectively improve the ceramic electrolyte Environmental protection problems in the film preparation process, and through the casting process, the preparation process is simplified and the processing cost is effectively reduced.

Of course, any product implementing the present invention does not necessarily need to achieve all the above-mentioned advantages at the same time.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that are required for the description of the embodiments. The accompanying drawings in the following description are only some embodiments of the present invention. As far as people are concerned, other drawings can also be obtained based on these drawings on the premise of not paying creative work.

Fig. 1 is a flow chart of a method for preparing a solid ceramic electrolyte membrane applied to an all-solid lithium battery of the present invention;

Fig. 2 is a picture of the dense electrolyte prime embryo provided by the present invention.

Fig. 3 is a picture of the sintered electrolyte membrane provided by the present invention.

Fig. 4 is an EIS diagram in the range of 0.01 Hz to 1 MHz in Example 1 of the present invention.

Fig. 5 is an EIS diagram in the range of 0.01 Hz to 1 MHz in Example 2 of the present invention.

Fig. 6 is an EIS diagram in the range of 0.01 Hz to 1 MHz in Example 3 of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1

A method for preparing a solid ceramic electrolyte membrane applied to an all-solid lithium battery, comprising the following steps:

(1) 10 g of the prepared LATP powder was ball milled for 12 hours, and sieved (200 mesh).

(2) The triethanolamine (TEA) dispersant is pre-configured as an aqueous solution with a mass fraction of 15%, and ultrasonically treated for 6 hours; an appropriate amount of polyvinyl alcohol (PVA) binder is added to the aqueous solution in batches, and stirred in a water bath at 60°C 24h, pre-configured as an aqueous solution with a mass fraction of 15%.

(3) Using LATP electrolyte powder as raw material, add 5g of water and 1.5g of pre-prepared dispersant for ball milling for 4 hours; add 1.3g of polyethylene glycol plasticizer, and continue ball milling for 12 hours.

(4) Add 7.5 g of pre-prepared polyvinyl alcohol binder to the obtained slurry, and ball mill for 6 hours. Then carry out vacuum degassing at 50kpa for 15min.

(5) Sieve the slurry obtained in (4) (200 mesh). The height of the scraper was adjusted to 500 μm, and the casting speed was 10 cm/min.

(6) The film obtained by casting was dried at room temperature, and three layers were selected for hot-pressing at a temperature of 90° C., a pressure of 10 MPa, and a time of 15 minutes; the hot-pressed film was cut into discs with a diameter of 16 mm.

(7) The hot-pressed plain embryo is placed in a muffle furnace, heated to 550°C at a heating rate of 2°C/min, and kept for 12 hours, then raised to 850°C at a heating rate of 2°C/min, and kept for 6 hours. A dense ceramic electrolyte membrane was obtained after programmed cooling.

The prepared LATP solid electrolyte membrane was tested for impedance at room temperature in the range of 0.01 Hz to 1 MHz, as shown in Figure 4, its ionic conductivity was 2.06×10 ^-4 S/cm.

Example 2

A method for preparing a solid ceramic electrolyte membrane applied to an all-solid lithium battery, comprising the following steps:

(1) 10 g of the prepared LAZP powder was ball milled for 12 hours, and sieved (200 mesh).

(2) The triethanolamine (TEA) dispersant is pre-configured as an aqueous solution with a mass fraction of 15%, and ultrasonically treated for 6 hours; an appropriate amount of polyvinyl alcohol (PVA) binder is added to the aqueous solution in batches, and stirred in a water bath at 60°C 24h, pre-configured as an aqueous solution with a mass fraction of 15%.

(3) Using LAZP electrolyte powder as the raw material, add 5g of water and 1.7g of pre-prepared dispersant for ball milling for 6 hours; add 1.53g of polyethylene glycol plasticizer, and continue ball milling for 12 hours.

(4) Add 8.52 g of pre-prepared polyvinyl alcohol binder to the obtained slurry, and ball mill for 6 hours. Then carry out vacuum degassing at 50kpa for 15min.

(5) Sieve the slurry obtained in (4) (200 mesh). Adjust the height of the scraper to 300 μm, and the casting speed to 8 cm/min.

(6) The film obtained by casting was dried at room temperature, and 5 layers were selected for hot-pressing at a temperature of 90° C., a pressure of 10 MPa, and a time of 15 minutes; the hot-pressed film was cut into discs with a diameter of 16 mm.

(7) The hot-pressed plain embryo is placed in a muffle furnace, heated to 550°C at a heating rate of 2°C/min, and kept for 12 hours, then raised to 900°C at a heating rate of 2°C/min, and kept for 2 hours. A dense ceramic electrolyte membrane was obtained after programmed cooling.

The prepared LAZP solid electrolyte membrane was tested for impedance at room temperature in the range of 0.01 Hz to 1 MHz, as shown in Figure 5, its ionic conductivity was 5.42×10 ^-6 S/cm.

Example 3

A method for preparing a solid ceramic electrolyte membrane applied to an all-solid lithium battery, comprising the following steps:

(1) 10 g of the prepared LAGP powder was ball milled for 12 hours, and sieved (200 mesh).

(2) The triethanolamine (TEA) dispersant is pre-configured as an aqueous solution with a mass fraction of 15%, and ultrasonically treated for 6 hours; an appropriate amount of polyvinyl alcohol (PVA) binder is added to the aqueous solution in batches, and stirred in a water bath at 60°C 12h, pre-configured as an aqueous solution with a mass fraction of 15%.

(3) Using electrolyte powder as raw material, add 5g of water and 1.95g of pre-prepared dispersant for ball milling for 3 hours; add 2.3g of polyethylene glycol plasticizer and 0.15g of polypropylene glycol defoamer, and continue ball milling for 12 hours.

(4) Add 8 g of pre-prepared polyvinyl alcohol binder to the obtained slurry, and ball mill for 6 hours. Then carry out vacuum degassing at 50kpa for 15min.

(5) Sieve the slurry obtained in (4) (200 mesh). Adjust the height of the scraper to 300 μm, and the casting speed to 8 cm/min.

(6) The film obtained by casting was dried at room temperature, and 5 layers were selected for hot-pressing at a temperature of 95° C., a pressure of 8 MPa, and a time of 20 minutes; the hot-pressed film was cut into discs with a diameter of 16 mm.

(7) The hot-pressed plain embryo is placed in a muffle furnace, heated to 550°C at a heating rate of 2°C/min, and kept for 12 hours, then raised to 900°C at a heating rate of 2°C/min, and held for 12 hours. A dense ceramic electrolyte membrane was obtained after programmed cooling.

The prepared LAGP solid electrolyte membrane was tested for impedance at room temperature in the range of 0.01 Hz to 1 MHz, as shown in Figure 6, its ionic conductivity was 3.14×10 ^-4 S/cm.

In summary, the ceramic electrolyte membrane prepared by water-based casting has a large area and good uniformity; and to a certain extent, the sintering ability, ion conductivity and mechanical properties of the ceramic electrolyte membrane are improved; the use of water as the only solvent effectively improves the Environmental protection problems in the preparation process of the ceramic electrolyte membrane, and through the casting process, the preparation process is simplified and the processing cost is effectively reduced.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, may use the technical content disclosed above to make some changes or modify them into equivalent embodiments with equivalent changes. Technical Essence of the Invention Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solutions of the present invention.

Claims (8)

1. The preparation method of the solid ceramic electrolyte membrane applied to the all-solid lithium battery is characterized by comprising the following steps of:

step1: preparing water-based casting slurry;

step2: casting;

step3: hot pressing;

step4: sintering.

2. The method for preparing a solid ceramic electrolyte membrane for an all-solid lithium battery according to claim 1, wherein in Step1, a proper amount of deionized water is added into a certain amount of electrolyte powder to be mixed uniformly, and ball milling is performed after a pre-prepared dispersing agent is added; adding plasticizer for secondary ball milling; adding an aqueous solution of a binder for ball milling for three times; vacuum defoaming is carried out on the slurry after ball milling for 5-15 min at 20-80 kpa to prepare water-based casting slurry;

in Step2, sieving the prepared electrolyte slurry to remove impurities or large particles, and then using an automatic coater to cast on high-temperature cellophane at a speed of 8-15 cm/min, wherein the height of a scraper is 5 mu m-1mm, so as to prepare an electrolyte casting film;

in Step3, the casting dried for 24 hours at room temperature is cut into the required size and peeled off, the layers are laminated according to the required thickness, and then the ceramic blank is prepared by hot pressing for 5-30min at 60-120 ℃;

in Step4, the ceramic biscuit is heated and preserved in a muffle furnace to 300-600 ℃ at a heating rate of 1-5 ℃/min for 1-12 h, and then heated to 700-1200 ℃ at a heating rate of 1-5 ℃/min for 1-12 h.

3. The method for preparing a solid ceramic electrolyte membrane for an all-solid lithium battery according to claim 2, wherein: in Step1, the mass percent of electrolyte powder (solid content) in the water-based casting slurry is 30% -60%, the content of solvent is 30% -45%, the content of dispersing agent is 0.8% -2%, the content of binder is 4% -8%, the content of plasticizer is 3% -10%, and the content of defoaming agent is 0.3% -1%.

4. A method for preparing a solid ceramic electrolyte membrane for an all-solid lithium battery according to claim 3, wherein: the electrolyte powder is NASICON type lithium ion electrolyte, and the structural formula is LiA ₂ (PO ₄ ) ₃ Wherein A includes but is not limited to Ti ⁴⁺ 、Zr ⁴⁺ 、Ge ⁴⁺ 、Hf ⁴⁺ 、Sn ⁴⁺ The electrolyte powder adopts one or more of LATP powder material, LAZP powder material and LAGP powder material.

The LATP powder material is Li _1+x Al _x Ti _2-x (PO ₄ ) ₃ (wherein x is between 0.1 and 0.5);

the LAZP powder material is Li _1+x Al _x Zr _2-x (PO ₄ ) ₃ (wherein x is between 0.1 and 0.5);

the LAGP powder material is Li _1+x Al _x Ge _2-x (PO ₄ ) ₃ (wherein x is between 0.1 and 0.5).

5. A method for preparing a solid ceramic electrolyte membrane for an all-solid lithium battery according to claim 3, wherein: the dispersing agent is one or more of triethanolamine, sodium polyacrylate, triethyl phosphate, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium hexametaphosphate, polyacrylic acid, cetyltrimethylammonium bromide, polyethylene glycol, potassium polyacrylate, octyl phenol polyoxyethylene ether or sulfonate fluorine dispersing agent.

6. A method for preparing a solid ceramic electrolyte membrane for an all-solid lithium battery according to claim 3, wherein: the binder is one or more of polyvinylidene fluoride, styrene-butadiene latex, styrene-acrylic latex, polyvinyl alcohol, polyvinyl butyral, sodium alginate, polyacrylamide, polymethyl methacrylate, butyl acrylate, ethylene-vinyl acetate copolymer, polyvinyl acetate, polyurethane, hydroxyethyl cellulose, methyl hydroxyethyl cellulose, sodium carboxymethyl cellulose, polyacrylamide, polyethylene oxide and polytetrafluoroethylene.

7. A method for preparing a solid ceramic electrolyte membrane for an all-solid lithium battery according to claim 3, wherein: the plasticizer is one or more of dibutyl phthalate, butyl benzyl phthalate, butyl stearate, dimethyl phthalate, tricresyl phosphate, polyethylene glycol, methyl abietate, polyalcohol, dimethyl phthalate, triethylene glycol, tributyl phosphate and polyalkyl glycol.

8. A method for preparing a solid ceramic electrolyte membrane for an all-solid lithium battery according to claim 3, wherein: the solvent is deionized water.

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