CN105633479A - Preparation method of all-solid-state lithium-sulfur battery - Google Patents

Abstract

The invention discloses a preparation method of an all-solid lithium-sulfur battery. This method adopts the solid-state method to sinter raw materials such as Li ₂ CO ₃ at high temperature to obtain an all-solid electrolyte, and then vapor-deposits a layer of metal lithium on one side of the all-solid electrolyte sheet as the negative electrode, and coats the sulfur-carbon composite material on the other side as the positive electrode and drips Add ionic liquid to enhance its conductivity, and finally package the battery with aluminum-plastic packaging to obtain a rechargeable and dischargeable all-solid-state lithium-sulfur battery. The all-solid-state lithium-sulfur battery prepared by the method has good electrochemical performance, practicability and good medium-high temperature safety.

Description

A kind of preparation method of all-solid-state lithium-sulfur battery

technical field

The invention relates to a preparation method of a rechargeable all-solid-state lithium-sulfur battery, in particular to an all-solid-state lithium battery with positive and negative active materials in good contact with all-solid-state electrolyte sheets and good electrochemical performance Preparation method of sulfur battery.

Background technique

With the development of social science and technology, portable electronic products such as mobile phones and notebook computers have been more and more widely used, and lithium batteries that provide electric energy for these electronic products are popular due to their high energy storage density and high output voltage. Welcome, the current commercial secondary lithium-ion batteries generally use organic electrolytes, which will heat up the organic electrolytes in the event of abnormal conditions such as short circuit or overcharging, which will cause dangerous situations such as spontaneous combustion or explosion of the battery. In order to improve the safety and Reliability, an effective method is to replace the flammable organic electrolyte with a substance with excellent thermal stability. In an all-solid-state battery, the solid electrolyte replaces the traditional organic electrolyte, which has the characteristics of non-flammability and good stability. Can greatly improve the safety of the battery.

In secondary lithium-ion batteries, lithium-sulfur batteries have great development potential and application prospects. The active material sulfur has extremely high energy density, and it shows great advantages in terms of cost and environmental friendliness. The biggest defect of organic lithium-sulfur batteries is that it is difficult to solve the "shuttle effect", that is, the intermediate product of sulfur in the charging and discharging process will dissolve into the electrolyte and directly react with the negative metal lithium. Once the "shuttle effect" occurs, The negative electrode of lithium-sulfur batteries will be corroded, which will seriously reduce the Coulombic efficiency of the battery and make it unable to work normally, and may cause safety hazards.

All-solid-state lithium-sulfur batteries can completely solve the "shuttle effect" problem, so they have received a lot of attention and research, because after using all-solid-state electrolyte sheets, the polysulfides generated by positive electrode discharge cannot pass through the electrolyte sheet to reach the negative electrode, thereby protecting the battery. The negative electrode metal lithium prolongs the working life of the lithium-sulfur battery. Compared with the organic electrolyte, the all-solid-state electrolyte sheet has good high-temperature stability, so the safety of the all-solid-state lithium-sulfur battery is very good.

Since the general all-solid-state lithium-sulfur battery does not use electrolyte, the positive and negative electrodes and the all-solid-state electrolyte are in solid-solid contact, which will cause a relatively large interface impedance and affect the performance of the battery. Adding ionic liquid to the positive electrode of solid-state lithium-sulfur battery can effectively improve the conductivity of the battery and reduce the impedance. Moreover, the high-temperature stability of ionic liquids is also very good, which will not affect the safety of all-solid-state lithium-sulfur batteries. On the other hand, if the positive and negative electrodes are not in close contact with the all-solid-state electrolyte sheet or even fall off, the battery will be disconnected and unable to work. , improving the contact between the two as much as possible is a key factor to improve the performance of the all-solid-state lithium-sulfur battery. The metal lithium is deposited on the all-solid-state electrolyte sheet by evaporation method, and a layer of battery lithium negative electrode that will not fall off can be obtained. .

In summary, compared with traditional organic secondary lithium batteries, all-solid-state lithium-sulfur batteries have the characteristics of no leakage, wide operating temperature range, and high safety, and have great research, exploration, development and utilization values.

Contents of the invention

1. Purpose of the invention

The purpose of the present invention is to provide a preparation method of an all-solid-state lithium-sulfur battery, which can be applied in the preparation process of lithium batteries, and has the characteristics of good contact between positive and negative active materials and all-solid-state electrolyte sheet, high electrochemical performance, etc. .

2. Technical solution

The invention provides a solid-state electrolyte sheet prepared by high-temperature sintering by a solid-state method. Lithium metal is vapor-deposited on one side of the electrolyte sheet as a negative electrode, and then a composite material of sulfur and carbon is coated on the other side of the electrolyte sheet as a positive electrode. A general method of adding ionic liquids and encapsulating cells using aluminum-plastic packaging.

The working principle of the present invention is: weigh Li ₂ CO ₃ , Al ₂ O ₃ , GeO ₂ , NH ₄ H ₂ PO ₄ and other substances in a certain proportion, go through a series of ball milling and heating processes, and then press into tablets and sinter to obtain an all-solid electrolyte sheet LAGP; metal lithium is deposited on the other side of the LAGP sheet by evaporation as a negative electrode; the mixture of sulfur and multi-walled carbon nanotubes is heated in an argon-hydrogen environment to obtain a composite material, and then coated with PVDF as a binder. One side of the LAGP sheet is used as the positive electrode; a small amount of ionic liquid is dropped on the positive electrode; current collectors are placed on the surface of the positive and negative electrodes respectively, and then packaged in aluminum-plastic packaging to obtain a usable all-solid-state lithium-sulfur battery.

A method for preparing an all-solid-state lithium-sulfur battery, the preparation steps of which are as follows:

(1) Weigh various substances according to the weight ratio Li ₂ CO ₃ : Al ₂ O ₃ : GeO ₂ : NH ₄ H ₂ PO ₄ =3:1:9:20, put them into a ball mill jar and mill at a speed of 300rpm 4 hours;

(2) Transfer the mixed powder obtained in step 1 to a muffle furnace and heat at 600°C for 1 hour in an air atmosphere;

(3) Transfer the mixed powder obtained in step 2 to a ball mill tank, and ball mill at a speed of 300rpm for 4 hours;

(4) Transfer the mixed powder obtained in step 3 to a muffle furnace, and heat at 900°C for 10 hours in an air atmosphere;

(5) Transfer the mixed powder obtained in step 4 to a ball mill tank, and ball mill at a speed of 300rpm for 4 hours;

(6) Transfer the mixed powder obtained in step 5 to a mold and press at a pressure of 30 MPa for 10 minutes to obtain a circular electrolyte tablet;

(7) Transfer the circular electrolyte sheet obtained in step 6, which has a diameter of 12 mm and a thickness of 1 mm, to a muffle furnace, and heat at 900°C for 10 hours in an air atmosphere to obtain the target solid electrolyte sheet;

(8) Put the solid electrolyte sheet obtained in step 7 into an evaporation apparatus, and heat the evaporation boat with the metal lithium sheet in an argon atmosphere, so that the evaporated metal lithium is deposited on the other side of the solid electrolyte sheet;

(9) Mix and grind sulfur and multi-walled carbon nanotubes according to the mass ratio of 4:1 to make them evenly mixed;

(10) Put the mixed powder obtained in step 9 into a tube furnace, heat at 165°C for 10 hours in an argon atmosphere, and cool naturally;

(11) Mix the mixed powder obtained in step 10 with a binder according to the mass ratio of 85:15, use magnetic stirring and add 5ml of NMP to disperse to make it a uniform slurry;

(12) Apply the slurry obtained in step 11 evenly on one side of the solid electrolyte sheet obtained in step 8 and dry it;

(13) Add the ionic liquid bis(trifluoromethylsulfonyl)1-ethyl-3-methylimidazole dropwise on the side of the solid electrolyte sheet obtained in step 12 coated with the slurry;

(14) Transfer the solid electrolyte sheet obtained in step 13 to an argon atmosphere glove box, wrap the solid electrolyte sheet with aluminum-plastic packaging and heat seal it.

In the preparation method of the all-solid-state lithium-sulfur battery, the mass ratio of ball milling in step 1 is 4:1.

In the preparation method of the all-solid-state lithium-sulfur battery, the heating rate in steps 2, 4, and 7 is 2° C./min.

In the preparation method of the all-solid-state lithium-sulfur battery, the mass ratio of ball milling in steps 3 and 5 is 2:1.

In the preparation method of the all-solid-state lithium-sulfur battery, the binder in step 11 is PVDF.

In the preparation method of the all-solid-state lithium-sulfur battery, the drying heating temperature in step 12 is 80°C.

In the preparation method of the all-solid-state lithium-sulfur battery, the evaporation time in step 8 is 1 hour.

In the preparation method of the all-solid-state lithium-sulfur battery, the ionic liquid added dropwise in step 13 is 0.05ml.

3. Beneficial effect

The present invention uses a high-temperature solid-state sintering method to prepare an all-solid-state electrolyte sheet, then vapor-deposits metal lithium on the other side of the electrolyte sheet as a negative electrode, and then coats a composite material of sulfur and carbon nanotubes on one side of the electrolyte sheet as a positive electrode, and finally Practical all-solid-state lithium-sulfur batteries are obtained by adding ionic liquid to the positive electrode and packaging the battery with aluminum-plastic packaging. The advantages are as follows: First, the all-solid electrolyte sheet prevents the intermediate product of positive electrode discharge from contacting the negative electrode, protecting the Negative metal lithium; second, the sulfur-carbon composite material coated on the all-solid electrolyte sheet and the metal lithium evaporated on the all-solid electrolyte sheet have very good contact with the all-solid electrolyte sheet and will not fall off; third, the all-solid electrolyte Both the electrolyte sheet and the ionic liquid have good high-temperature stability, so the battery system has very good safety. Using this ingenious preparation method can obtain all-solid lithium-sulfur that is practical, safe, and has excellent electrochemical properties. Battery.

4. Description of drawings

Figure 1: SEM image of the all-solid electrolyte LAGP at a resolution of 5 μm;

Figure 2: SEM image of the sulfur-carbon nanotube composite at a resolution of 500nm;

Figure 3: SEM image of the evaporated metal lithium layer at a resolution of 10 μm;

Figure 4: All solid electrolyte LAGP impedance diagram;

Figure 5: Impedance diagram of all-solid-state lithium-sulfur battery before and after charge and discharge;

Figure 6: XRD of discharge products of all-solid-state lithium-sulfur batteries;

Figure 7: Electrochemical performance of all-solid-state lithium-sulfur batteries at room temperature;

Figure 8: Electrochemical performance of all-solid-state lithium-sulfur batteries at different temperatures and currents.

5. Specific implementation

A preparation method of an all-solid-state lithium-sulfur battery, characterized in that the steps of the preparation method are as follows:

(1) Weigh various substances according to the weight ratio Li ₂ CO ₃ : Al ₂ O ₃ : GeO ₂ : NH ₄ H ₂ PO ₄ =3:1:9:20, put them into a ball mill jar and mill at a speed of 300rpm 4 hours, the ball-to-mass ratio of ball milling is 2:1;

(2) Transfer the mixed powder obtained in step 1 to a muffle furnace and heat at 600°C for 1 hour in an air atmosphere with a heating rate of 2°C/min;

(3) Transfer the mixed powder obtained in step 2 to a ball mill tank, and ball mill at a speed of 300rpm for 4 hours, and the ball-to-mass ratio of the ball mill is 2:1;

(4) Transfer the mixed powder obtained in step 3 to a muffle furnace and heat at 900°C for 10 hours in an air atmosphere with a heating rate of 2°C/min;

(5) Transfer the mixed powder obtained in step 4 to a ball mill tank, and ball mill at a speed of 300rpm for 4 hours, and the ball-to-mass ratio of the ball mill is 2:1;

(6) Transfer the mixed powder obtained in step 5 to a mold and press at a pressure of 30 MPa for 10 minutes to obtain a circular electrolyte tablet;

(7) Transfer the round electrolyte sheet obtained in step 6 with a diameter of 12 mm and a thickness of 1 mm to a muffle furnace, and heat at 900 °C for 10 hours in an air atmosphere at a heating rate of 2 °C/min to obtain the target product solid electrolyte sheet;

(8) Put the solid electrolyte sheet obtained in step 7 into the vapor deposition apparatus, heat the evaporation boat with the metal lithium sheet in the argon atmosphere, so that the evaporated metal lithium is deposited on the other side of the solid electrolyte sheet, and evaporate The time is 1 hour;

(9) Mix and grind sulfur and multi-walled carbon nanotubes according to the mass ratio of 4:1 to make them evenly mixed;

(10) Put the mixed powder obtained in step 9 into a tube furnace and heat at 165°C in an argon atmosphere

10 hours, natural cooling;

(11) Mix the mixed powder obtained in step 10 with a binder according to the mass ratio of 85:15, use magnetic stirring and add 5ml of NMP to disperse to make it a uniform slurry;

(12) Apply the slurry obtained in step 11 evenly on one side of the solid electrolyte sheet obtained in step 8 and dry at a heating temperature of 80 degrees;

(13) Add 0.05ml of ionic liquid bis(trifluoromethylsulfonyl)1-ethyl-3-methylimidazole dropwise on the side of the solid electrolyte sheet obtained in step 12 coated with the slurry;

(14) Transfer the solid electrolyte sheet obtained in step 13 to an argon atmosphere glove box, wrap the solid electrolyte sheet with aluminum-plastic packaging and heat seal it.

The SEM electron microscope image of the all-solid electrolyte LAGP at a resolution of 5 μm is shown in Figure 1, the SEM electron microscope image of the sulfur-carbon nanotube composite material at a resolution of 500 nm is shown in Figure 2, and the evaporated metal lithium layer is at a resolution of 10 μm The SEM electron microscope picture below is shown in Figure 3, the impedance diagram of the all-solid electrolyte LAGP is shown in Figure 4, the impedance diagram of the all-solid-state lithium-sulfur battery before and after charging and discharging is shown in Figure 5, and the XRD of the discharge product of the all-solid-state lithium-sulfur battery is shown in Figure 6 As shown, the electrochemical performance of the all-solid-state lithium-sulfur battery at room temperature is shown in Figure 7, and the electrochemical performance of the all-solid-state lithium-sulfur battery at different temperatures and currents is shown in Figure 8. It can be seen that the all-solid electrolyte sheet prevents the intermediate product of positive electrode discharge from contacting the negative electrode and protects the lithium metal of the negative electrode; the sulfur-carbon composite material coated on the all-solid electrolyte sheet and the metal lithium evaporated on the all-solid electrolyte sheet All have very good contact and will not fall off; both the all-solid electrolyte sheet and the ionic liquid have good high-temperature stability, so the battery system has very good safety. Using this original preparation method can obtain practical, An all-solid-state lithium-sulfur battery with good safety and excellent electrochemical performance.

Claims (8)

1. A preparation method of an all-solid-state lithium-sulfur battery, characterized in that the steps of the preparation method are as follows: (1) Weigh various substances according to the weight ratio Li ₂ CO ₃ : Al ₂ O ₃ : GeO ₂ : NH ₄ H ₂ PO ₄ =3:1:9:20, put them into a ball mill jar and mill at a speed of 300rpm 4 hours; (2) Transfer the mixed powder obtained in step (1) to a muffle furnace, and heat at 600°C for 1 hour in an air atmosphere; (3) Transfer the mixed powder obtained in step (2) to a ball mill tank, and ball mill at a speed of 300rpm for 4 hours; (4) Transfer the mixed powder obtained in step (3) to a muffle furnace, and heat at 900°C for 10 hours in an air atmosphere; (5) Transfer the mixed powder obtained in step (4) to a ball mill jar, and ball mill at a speed of 300rpm for 4 hours; (6) Transfer the mixed powder obtained in step (5) to a mold, press at a pressure of 30 MPa for 10 minutes, and obtain a circular electrolyte tablet; (7) Transfer the circular electrolyte sheet obtained in step (6) with a diameter of 12 mm and a thickness of 1 mm to a muffle furnace, and heat at 900°C for 10 hours in an air atmosphere to obtain the target solid electrolyte sheet; (8) Put the solid electrolyte sheet obtained in step (7) into an evaporation apparatus, and heat the evaporation boat with the metal lithium sheet in an argon atmosphere, so that the evaporated metal lithium is deposited on the other side of the solid electrolyte sheet; (9) Mix and grind sulfur and multi-walled carbon nanotubes according to the mass ratio of 4:1 to make them evenly mixed; (10) Put the mixed powder obtained in step (9) into a tube furnace, heat at 165°C for 10 hours in an argon atmosphere, and cool naturally; (11) Mix the mixed powder obtained in step (10) with a binder according to the mass ratio of 85:15, use magnetic stirring and add 5ml of NMP to disperse to make it a uniform slurry; (12) Apply the slurry obtained in step (11) evenly on one side of the solid electrolyte sheet obtained in step (8) and dry; (13) Adding the ionic liquid bis(trifluoromethylsulfonyl)1-ethyl-3-methylimidazole dropwise on the side of the solid electrolyte sheet obtained in step (12) coated with the slurry; (14) Transfer the solid electrolyte sheet obtained in step (13) to an argon atmosphere glove box, wrap the solid electrolyte sheet with aluminum-plastic packaging and heat seal it. 2. A method for preparing an all-solid-state lithium-sulfur battery according to claim 1, characterized in that the ball-to-mass ratio of the ball mill in step (1) is 4:1. 3. The method for preparing an all-solid-state lithium-sulfur battery according to claim 1, wherein the heating rate in steps (2), (4) and (7) is 2°C/min. 4. A method for preparing an all-solid-state lithium-sulfur battery according to claim 1, characterized in that the ball-to-mass ratio of ball milling in steps (3) and (5) is 2:1. 5. The method for preparing an all-solid-state lithium-sulfur battery according to claim 1, wherein the binder in step (11) is PVDF. 6. A method for preparing an all-solid-state lithium-sulfur battery according to claim 1, characterized in that the drying heating temperature in step (12) is 80°C. 7. The method for preparing an all-solid-state lithium-sulfur battery according to claim 1, wherein the evaporation time in step (8) is 1 hour. 8. A method for preparing an all-solid-state lithium-sulfur battery according to claim 1, characterized in that the ionic liquid added dropwise in step (13) is 0.05ml.