Preparation method of thin-film battery positive electrode material

Abstract

The invention discloses a preparation method of a thin film battery positive electrode material, which comprises the following steps: adding a battery positive electrode raw material and a reducing agent into water, and heating and stirring until solute is completely dissolved to obtain a mixed solution; adding a binder into water, heating and stirring until the binder is completely dissolved to obtain a binder solution; adding the mixed solution into the binder solution, continuously heating in a water bath, and stirring until the two solutions are uniformly mixed to obtain a sample; and uniformly coating the sample on a substrate, then carrying out curing treatment, and then carrying out drying and annealing to obtain the positive electrode material. The positive electrode material prepared by the invention has excellent energy storage property under large current 1A / g. The prepared positive electrode material has excellent cycle performance, and the battery capacity retention ratio in 100 cycles is greater than or equal to 90%. The prepared positive electrode thin film material has high specific capacity, and the capacity is about 80mAh / g. The method has the advantage of efficiently and quickly preparing the positive electrode thin film, and a batch of positive electrode thin film materials can be prepared every 1 hour.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical energy storage devices, and particularly relates to a preparation method of a cathode material for a thin film battery. Background Art

[0002] Traditional liquid sodium-ion batteries use carbonate or ether solvents as electrolytes, which have a series of safety problems such as electrolyte volatilization, leakage, and uncontrollable growth of sodium dendrites, leading to battery short circuit, thermal runaway, explosion, etc. All-solid-state sodium-ion batteries use highly stable solid electrolytes to replace traditional liquid organic electrolytes, which can effectively inhibit the growth of sodium dendrites and improve the battery life and stability to achieve high energy density and high safety. Although all-solid-state sodium-ion batteries have many advantages, the film preparation process involves complex technologies. The current preparation technologies for thin film electrodes mainly include physical vapor deposition (PVD), chemical vapor deposition (CVD), and sputtering deposition. Although these technologies can deposit thin film materials with specific functions on different substrates, the preparation process is relatively complex, cumbersome, and costly. To achieve industrialization, ensuring high-quality and large-scale manufacturing is a technical challenge.

[0003] The patent with the publication number CN114959662A discloses a method for preparing a porous crystalline tungsten oxide thin film by electrode electrospraying. The tungsten precursor-ethanol dispersion is sprayed on a clean substrate by electrode electrospraying for coating, then dried at a temperature of 60-80°C for 1h-2h, and finally annealed in an inert atmosphere at a heating rate of 5°C / min for 10min-120min to obtain a porous crystalline tungsten oxide thin film. The total annealing time of this scheme is relatively long. The total annealing time of the present scheme is about 1h, which greatly improves the production efficiency.

[0004] The patent with the publication number CN118431393A discloses a dry process preparation method for a solid-state battery electrode thin film and an electrolyte thin film. The binder in the electrode or electrolyte material is melted by uniformly irradiating and heating with a laser; then it is calendered three to seven times by a hot calendering module, and finally the electrode thin film or the solid-state electrolyte thin film is annealed by a laser beam with uniform light field distribution. Although the quality and thickness deviation of the prepared thin film are not large, its production process is relatively complex and energy-consuming. The production process of the present application is relatively simple, and only short-time heating is required during production, with relatively low energy consumption requirements, reducing the production cost.

[0005] The patent with the publication number CN114032508A discloses a device and method for preparing a transparent electrode film for a photovoltaic cell. The device includes a control system, a metal evaporation source, a scanning sliding device, an optical coding system, a laser coupling repair system, and a reaction chamber for the growth of the transparent electrode film. Although the device can achieve real-time repair of the transparent electrode film and ensure its flatness, the device is relatively complex and the training process is complicated, which is not conducive to industrial production. This application has simple requirements for equipment. Only a rapid annealing furnace is needed to produce the product, and the rapid annealing furnace has simple equipment and convenient operation, which is conducive to industrialization.

[0006] The patent with the publication number CN118888677A discloses a thin-film electrode material and a preparation method thereof. After heating Wood's alloy to a molten state of 80 - 100 °C, a Wood's alloy layer with a thickness of 5 - 100 μm is scrape-coated on a metal foil and immersed in an MXene solution to obtain the thin-film electrode material. Although different-performance thin-film electrode materials are prepared by a simple method, the interfacial contact between the electrode material and the metal foil is poor, and the interfacial resistance is high, which reduces the performance of the battery. This application adopts in-situ synthesis technology, greatly reducing the interfacial resistance and improving the ion conductivity of the electrode material.

[0007] In summary, thinning the cathode material and realizing industrial production is a key technical strategy to overcome the problems of traditional batteries. By making the electrolyte and electrode material into thin films, more active materials can be accommodated in a limited space, thereby improving the energy storage capacity of the battery. Therefore, studying a simpler, safer, and more convenient method for preparing the cathode thin-film material is of great significance for improving the efficiency of industrial preparation of thin-film electrodes. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides a method for preparing a cathode material for a thin-film battery.

[0009] The present invention is achieved through the following technical solutions.

[0010] A method for preparing a cathode material for a thin-film battery provided by the present invention includes the following steps:

[0011] S1: Take the raw materials of the battery cathode and a reducing agent, add them to water, and heat and stir until the solute is completely dissolved to obtain a mixed solution;

[0012] S2: Take a binder, add it to water, and heat and stir until it is completely dissolved to obtain a binder solution;

[0013] S3: Add the mixed solution obtained in step S1 to the binder solution obtained in step S2,

[0014] Continue water bath heating and stirring until the two are evenly mixed to obtain a sample;

[0015] S4: Evenly coat the sample obtained in step S3 on the substrate, and then carry out curing treatment;

[0016] S5: Dry the cured substrate coated with the sample;

[0017] S6: Obtain the positive electrode material after annealing.

[0018] Preferably, the positive electrode raw material in step S1 includes ammonium dihydrogen phosphate and ammonium metavanadate, the reducing agent is oxalic acid, and the substrate is a carbon-coated titanium substrate.

[0019] Preferably, the molar ratio of ammonium dihydrogen phosphate: ammonium metavanadate: oxalic acid is 3:2:7 - 14.

[0020] Preferably, the binder in step S2 is one or more of polyvinyl alcohol, polyacrylonitrile, and polyvinylpyrrolidone.

[0021] Preferably, in step S2, the binder is added to water and heated to 60 - 90 °C and stirred until completely dissolved. In step S3, water bath heating is carried out to 60 - 90 °C and stirred until the mixed solution and the binder solution are evenly mixed to obtain a sample.

[0022] Preferably, the temperature of the curing treatment in step S4 is 60 - 100 °C, and the time is 5 - 15 min. The drying step in step S5 includes: drying under vacuum at a temperature of 100 - 150 °C for 9 - 15 h.

[0023] Preferably, in step S6, the annealing step includes: carrying out the first-stage sintering and the second-stage sintering in a protective gas atmosphere to obtain the positive electrode material.

[0024] Preferably, in the annealing step of step S6, the heating rate is 5 - 15 °C / s, and the protective gas includes one or more of argon, nitrogen, and neon.

[0025] Preferably, in the annealing step of step S6, the temperature is raised to 300 - 400 °C and maintained for 20 - 100 s to complete the first-stage sintering, and then the temperature is continued to be raised for the second-stage sintering.

[0026] Preferably, in step S6, after the first-stage sintering is completed, the temperature is continued to be raised to 750 °C and maintained for 1 - 10 min to complete the second-stage sintering.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. The positive electrode material prepared by the present invention has high stability, low material cost and production cost, high safety, environmental friendliness, and low energy consumption.

[0029] 2. The positive electrode material prepared by the present invention has excellent energy storage properties at a high current of 1 A / g.

[0030] 3. The positive electrode material prepared by the present invention has excellent cycling performance, and the battery capacity retention rate is ≥90% during 100 cycles.

[0031] 4. The positive electrode thin film material prepared by the present invention has a high specific capacity, with a capacity of about 80 mAh / g.

[0032] 5. The present invention has the advantage of efficiently and rapidly preparing positive electrode thin films, and a batch of positive electrode thin film materials can be produced every about 1 h. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is the preparation flow chart of the present invention;

[0034] Figure 2 is the XRD pattern of the positive electrode material prepared in Example 1 of the present invention;

[0035] Figure 3 is the surface morphology diagram of the positive electrode material prepared in Example 3 of the present invention;

[0036] Figure 4 is the comparison diagram of the cycling capacity of the positive electrode material prepared in Example 3 of the present invention and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0037] The technical solutions of the present invention will be further described below, but the scope of protection is not limited thereto.

[0038] Example 1:

[0039] As Figure 1 shown, a preparation method of a positive electrode material for a thin film battery is characterized by comprising the following steps:

[0040] S1: Weigh sodium dihydrogen phosphate, ammonium metavanadate, and oxalic acid in a molar ratio of 3:2:14, then add them to water, and heat to 60°C and stir until the solutes are completely dissolved to obtain a mixed solution;

[0041] S2: Take polyvinyl alcohol, add it to water, and heat to 60°C and stir until completely dissolved to obtain a binder solution;

[0042] S3: Add the mixed solution obtained in step S1 to the binder solution obtained in step S2, continue to heat in a water bath at 60°C and stir until the two are evenly mixed to obtain a sample;

[0043] S4: Spread the sample obtained in step S3 evenly on a carbon-coated titanium substrate, and then perform a curing treatment at 60°C for 5 min;

[0044] S5: Dry the solidified substrate coated with the sample in a vacuum at a temperature of 100 - 150 °C for 9 - 15 h;

[0045] S6: Perform a rapid annealing step using an RTP rapid annealing furnace from sindin company. Under an argon protective gas atmosphere, with a heating rate of 5 °C / s, first heat up to 300 °C and hold for 20 s to complete the first-stage sintering, then continue to heat up to 750 °C and hold for 3 min to complete the second-stage sintering, forming a sodium ion fast conductor thin film to obtain the cathode material Na3V2(PO4)3.

[0046] Example 2:

[0047] As Figure 1 shown, a method for preparing a cathode material for a thin film battery, characterized by comprising the following steps:

[0048] S1: Weigh sodium dihydrogen phosphate, ammonium metavanadate, and oxalic acid in a molar ratio of 3:2:10, then add them to water and heat to 90 °C and stir until the solutes are completely dissolved to obtain a mixed solution;

[0049] S2: Take polyacrylonitrile and add it to water, and heat to 90 °C and stir until completely dissolved to obtain a binder solution;

[0050] S3: Add the mixed solution obtained in step S1 to the binder solution obtained in step S2, continue to heat in a water bath at 90 °C and stir until the two are evenly mixed to obtain a sample;

[0051] S4: Uniformly coat the sample obtained in step S3 onto a carbon-coated titanium substrate, and then carry out a curing treatment at 100 °C for 15 min;

[0052] S5: Dry the solidified substrate coated with the sample in a vacuum at a temperature of 150 °C for 15 h;

[0053] S6: Perform a rapid annealing step using an RTP rapid annealing furnace from sindin company. Under a nitrogen protective gas atmosphere, with a heating rate of 15 °C / s, first heat up to 400 °C and hold for 100 s to complete the first-stage sintering, then continue to heat up to 750 °C and hold for 4 min to complete the second-stage sintering, forming a sodium ion fast conductor thin film to obtain the cathode material Na3V2(PO4)3.

[0054] Example 3:

[0055] As Figure 1 shown, a method for preparing a cathode material for a thin film battery, characterized by comprising the following steps:

[0056] S1: Weigh sodium dihydrogen phosphate, ammonium metavanadate, and oxalic acid in a molar ratio of 3:2:7, then add them to water and heat to 80 °C with stirring until the solutes are completely dissolved to obtain a mixed solution;

[0057] S2: Take polyvinylpyrrolidone and add it to water, then heat to 80 °C with stirring until it is completely dissolved to obtain a binder solution;

[0058] S3: Add the mixed solution obtained in step S1 to the binder solution obtained in step S2, continue to heat in a water bath at 80 °C and stir until the two are uniformly mixed to obtain a sample;

[0059] S4: Evenly coat the sample obtained in step S3 onto a carbon-coated titanium substrate, and then perform a curing treatment at 80 °C for 10 min;

[0060] S5: Dry the cured substrate coated with the sample in a vacuum at a temperature of 120 °C for 12 h;

[0061] S6: Perform a rapid annealing step using an RTP rapid annealing furnace from sindin company. Under the atmosphere of neon gas as the protective gas, with a heating rate of 10 °C / s, first heat up to 350 °C and hold for 80 s to complete the first-stage sintering, then continue to heat up to 750 °C and hold for 5 min to complete the second-stage sintering to form a sodium-ion fast conductor thin film and obtain the positive electrode material Na3V2(PO4)3.

[0062] Comparative Example 1:

[0063] A powder Na3V2(PO4)3 electrode prepared by the prior art (Yang W, Wang B, Chen Q, et al. Unravelling capacity fading mechanisms in sodium vanadyl phosphate for aqueous sodium-ion batteries[J]. Journal of Colloid and Interface Science, 2022, 627:913 - 921.) method.

[0064] Example 3 in this application is the optimal example. Take the positive electrode material prepared in Example 3 as the positive electrode, use AgCl as the counter electrode, and use a sodium perchlorate solution as the electrolyte to form an electrochemical test system, and then perform charge-discharge cycling under a current density condition of 1 A / g. The cycling performance is shown in Figure 4 , in the figure, NVP-film is the data of Example 3, and NVP-Powder is the data of Comparative Example 1.

[0065] Figure 2It is the X-ray diffraction pattern of the positive electrode material of the sodium-ion battery prepared in Example 1; it can be seen from the figure that as the annealing time of the sample at 750 °C increases, the diffraction peaks of Na3V2(PO4)3 are significantly enhanced, and when the holding time at 750 °C is 4 min, the crystal orientation of Na3V2(PO4)3 particles reaches the best.

[0066] Figure 3 It is the surface morphology of the positive electrode prepared in Example 3, which are the scanning electron microscope images of the substrate coated with the sample in Step S6 after being held at 750 °C for 3 min, 4 min, and 5 min; it can be seen from the figure that different annealing times all show a relatively flat surface morphology, and the morphology reaches the best when the holding time at 750 °C is 4 min, which can make the conduction of sodium ions more efficient.

[0067] Figure 4 It is the comparison chart of the cycling capacity of the positive electrodes prepared in Examples 1-3 and the electrode of Comparative Example 1. Among them, Experimental Case 1 represents Example 1, and the NVP traditional electrode represents Comparative Example 1; it can be seen from the figure that at a current density of 1 A / g, the NVP thin-film electrode shows a cycling retention rate close to that of the traditional powder NVP electrode in the first 100 cycles. The results show that although the annealing time is compressed from 8-10 hours in the traditional process to 40 minutes, the rapid thermal annealing (RTA) process of the present invention can still effectively maintain the cycling stability of the electrode through precise gradient temperature control technology, providing a feasible path for the large-scale manufacture of highly consistent electrodes for all-solid-state sodium-ion batteries.

Claims

1. A method for preparing a positive electrode material of a thin film battery, characterized in that, It includes the following steps: S1: Take the battery positive electrode raw materials and a reducing agent, add them into water, and heat and stir until the solute is completely dissolved to obtain a mixed solution; S2: Take a binder, add it into water, and heat and stir until it is completely dissolved to obtain a binder solution; S3: Add the mixed solution obtained in step S1 into the binder solution obtained in step S2, continue to heat in a water bath and stir until the two are evenly mixed to obtain a sample; S4: Uniformly coat the sample obtained in step S3 onto a substrate, and then perform a curing treatment; S5: Dry the cured substrate coated with the sample; S6: After annealing, a positive electrode material is obtained.

2. The preparation method of a cathode material for a thin-film battery according to claim 1, characterized in that: The positive electrode raw materials in step S1 include ammonium dihydrogen phosphate and ammonium metavanadate, the reducing agent is oxalic acid, and the substrate is a carbon-coated titanium substrate.

3. The preparation method of a cathode material for a thin-film battery according to claim 2, characterized in that: The molar ratio of ammonium dihydrogen phosphate: ammonium metavanadate: oxalic acid is 3:2:7 - 14.

4. The preparation method of a thin film battery positive electrode material according to claim 1, characterized in that: The binder in step S2 is one or more of polyvinyl alcohol, polyacrylonitrile, and polyvinylpyrrolidone.

5. The preparation method of a cathode material for a thin-film battery according to claim 1, characterized in that: In step S2, take the binder, add it into water, and heat to 60 - 90 °C and stir until it is completely dissolved. In step S3, heat in a water bath to 60 - 90 °C and stir until the mixed solution and the binder solution are evenly mixed to obtain a sample.

6. The preparation method of a cathode material for a thin film battery according to claim 1, characterized in that: In step S4, the temperature of the curing treatment is 60 - 100 °C, and the time is 5 - 15 min. The drying step in step S5 includes: drying in a vacuum at a temperature of 100 - 150 °C for 9 - 15 h.

7. The preparation method of a thin-film battery cathode material as described in claim 1, wherein, In step S6, the annealing step includes: performing a first-stage sintering and a second-stage sintering in a protective gas atmosphere to obtain a positive electrode material.

8. The preparation method of a cathode material for a thin film battery according to claim 7, wherein: In the annealing step of step S6, the heating rate is 5 - 15 °C / s, and the protective gas includes one or more of argon, nitrogen, and neon.

9. The preparation method of a cathode material for a thin-film battery as described in claim 7, characterized in that: In the annealing step of step S6, heat up to 300 - 400 °C and hold for 20 - 100 s to complete the first-stage sintering, and then continue to heat up for the second-stage sintering.

10. The preparation method of a cathode material for a thin-film battery according to claim 9, characterized in that: In step S6, after completing the first-stage sintering, continue to heat up to 750 °C and hold for 1 - 10 min to complete the second-stage sintering.

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