A preparation method of polypyrrole manganese dioxide hollow nanospheres

Abstract

The present invention relates to a preparation method of polypyrrole manganese dioxide hollow nanospheres, the preparation method comprising: first mixing sodium thiosulfate pentahydrate and a PVP solution, then adding concentrated hydrochloric acid to react, centrifugally collecting the precipitate and washing to obtain hollow nano sulfur balls. The precipitate is dispersed in a PVP aqueous solution, diluted and then added with KMnO4, stirred at high temperature, washed by alternating centrifugation with water and ethanol, collected and obtained, dried at room temperature to obtain hollow S-MnO2 nanospheres. The above-mentioned hollow S-MnO2 nanospheres are dispersed in deionized water, added with FeCl3 to dissolve, then added with pyrrole and concentrated hydrochloric acid to react, filtered to obtain black floccules, added to a CS2 solution, ultrasonically dissolved sulfur in the CS2 solution, and filtered to obtain polypyrrole manganese dioxide hollow nanospheres with sulfur removed. The prepared material has the characteristics of good lithium affinity and electrical conductivity, and the hollow sphere size is 300-600nm, which can be used as a material for preparing a lithium metal negative electrode.

Description

Technical Field

[0001] The present invention relates to a method for preparing a composite negative electrode material for a lithium ion battery, and in particular to a method for preparing polypyrrole manganese dioxide hollow nanospheres. Background Art

[0002] Countries around the world are actively developing new energy industries, one of which is lithium-ion batteries. Due to their high capacity, high voltage, excellent safety, long cycle life, and environmental friendliness, lithium-ion batteries have found widespread application in a variety of fields, including portable electronic devices, pure electric vehicles, and defense and military applications. Lithium-ion batteries are rechargeable secondary batteries primarily composed of a positive electrode, a negative electrode, an electrolyte, and a separator. The primary function of the positive and negative electrode materials is to strip and insert lithium ions, enabling charging and discharging. The negative electrode material is a crucial component of lithium batteries, and current research on negative electrode materials focuses on increasing battery capacity, improving battery safety, and reducing costs. With the advancement of science and technology, concerns about the safety of lithium-ion batteries are growing. The problems of lithium dendrites and dead lithium, which not only deplete reversible capacity but also pose safety risks, have severely hampered their further development. Therefore, the design of new, high-performance negative electrode materials is crucial.

[0003] Among them, lithium dendrite growth is the main factor affecting the safety and stability of lithium-ion batteries. The growth of lithium dendrites can lead to instability in the electrode-electrolyte interface during the cycle of lithium-ion batteries, destroying the generated SEI film. During the growth process, lithium dendrites continuously consume electrolyte and cause irreversible deposition of metallic lithium, forming "dead lithium" and causing low coulombic efficiency. The formation of lithium dendrites can even pierce the separator, causing internal short circuits in lithium-ion batteries, thermal runaway of the battery, and explosions. Therefore, it is very necessary to design a negative electrode material with good lithium affinity and good safety performance.

[0004] Therefore, using polypyrrole manganese dioxide hollow nanospheres as a negative electrode material for lithium batteries has potential advantages. Summary of the Invention

[0005] The purpose of the present invention is to provide a simple method for preparing polypyrrole manganese dioxide hollow nanospheres.

[0006] In order to solve the above technical problems, the present invention provides a method for preparing polypyrrole manganese dioxide hollow nanospheres, comprising the following steps:

[0007] Step 1: Dissolve sodium thiosulfate pentahydrate in water and PVP in water, mix the two solutions at room temperature, then add concentrated hydrochloric acid to the mixed solution and react under stirring;

[0008] Step 2: Collect the precipitate by centrifugation to obtain hollow nano-sulfur spheres, then centrifuge and wash them once with a PVP aqueous solution, redisperse the collected hollow nano-sulfur spheres in a PVP aqueous solution, and dilute the uniform dispersion by adding water;

[0009] Step 3: After adding KMnO4 to the diluted solution, react at 70°C with magnetic stirring, wash alternately with water and ethanol by centrifugation, and dry the collected precipitate to obtain hollow S-MnO2 nanospheres;

[0010] Step 4: Disperse the hollow S-MnO2 nanospheres into water, dissolve FeCl3 in the solution, add pyrrole and concentrated hydrochloric acid, stir and react, and filter to obtain black floccules;

[0011] Step 5: Add the above black flocs to the CS2 solution, dissolve the sulfur in the CS2 solution by ultrasonication, and filter to obtain the sulfur-removed polypyrrole manganese dioxide hollow nanospheres.

[0012] Furthermore, the sodium thiosulfate pentahydrate is 0.992 g, and the sodium thiosulfate pentahydrate is dissolved in 50 ml of deionized water.

[0013] Furthermore, the molecular weight of the PVP is 58,000, and the concentration of the PVP solution is 1% to 3%.

[0014] Furthermore, the concentration of the concentrated hydrochloric acid is 12M, and the stirring reaction time is 2h to 3h.

[0015] Furthermore, the concentration of the PVP aqueous solution is 0.8 mmol / L, and the solution is diluted 4 times.

[0016] Furthermore, the mass ratio of the diluted solution to KMnO4 is 200:1, and the stirring reaction time is 5 minutes to 30 minutes.

[0017] Furthermore, the centrifugal washing is performed three times, and the precipitate is dried at room temperature for 36 hours to 48 hours.

[0018] Furthermore, the amount of FeCl3 added is 100 mg, the amount of pyrrole added is 30 uL, and the amount of concentrated hydrochloric acid added is 2 mL to 3 mL.

[0019] Furthermore, the reaction stirring time is 1 h to 6 h.

[0020] Furthermore, the volume of CS2 is 25 mL.

[0021] Furthermore, the ultrasonic reaction time is 5 minutes to 30 minutes.

[0022] A button lithium battery uses polypyrrole manganese dioxide hollow nanospheres as the negative electrode material.

[0023] The beneficial effects produced by the present invention are

[0024] (1) The polypyrrole manganese dioxide hollow nanospheres prepared in the present invention can provide space for storing lithium metal during battery cycling, reduce the contact area between lithium and electrolyte, reduce the occurrence of side reactions and lithium loss, and improve the cycle performance of the battery.

[0025] (2) The manganese dioxide in the hollow nanospheres prepared by the present invention is a highly lithium-affinity substance that can effectively guide the uniform and orderly deposition of lithium. At the same time, it also controls the growth of lithium dendrites during battery charging, reduces the battery capacity loss caused by the shedding of dead lithium from the dendrites, and improves the coulombic efficiency of the battery.

[0026] (3) The polypyrrole produced in the present invention has excellent electrical conductivity and can construct a conductive path, allowing lithium metal to be deposited quickly and reducing the generation of dead lithium.

[0027] (4) The polypyrrole generated in the present invention is a nitrogen-containing polymer that can react with metallic lithium to generate Li3N in the process of forming a solid electrolyte interface layer (SEI). This substance can maintain a high ionic conductivity while enhancing the mechanical properties of the SEI. The SEI with good mechanical properties can prevent battery safety problems caused by lithium dendrite puncture, and the high ionic conductivity can make the lithium metal quickly and stabilize during the solvation process, so that the battery can operate at a high rate.

[0028] (5) The present invention uses sulfur as a template to obtain a polypyrrole manganese dioxide hollow nanosphere, and the size of the hollow nanosphere is 300-600nm, and the polypyrrole sphere wraps the manganese dioxide. The hollow structure of the present invention can provide space for storing lithium metal during the battery cycle, reduce the contact area between lithium and electrolyte, reduce the occurrence of side reactions and lithium loss, and improve the cycle performance of the battery. The manganese dioxide in the hollow nanosphere prepared by the present invention is a highly lithium-affinity substance that can effectively guide the uniform and orderly deposition of lithium. At the same time, it also controls the growth of lithium dendrites during the battery charging process, reduces the battery capacity loss caused by the shedding of dead lithium from the dendrites, and improves the coulombic efficiency of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

[0030] Figure 1 This is a scanning electron microscope image of the S-MnO2 nanospheres prepared in Example 1;

[0031] Figure 2This is a scanning electron microscope image of the PPY-MnO2 hollow nanospheres prepared in Example 1;

[0032] Figure 3 This is the electrochemical test diagram of a full battery assembled with a composite negative electrode prepared using this material as a precursor. DETAILED DESCRIPTION

[0033] The present invention is described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0034] Example 1

[0035] First, 0.992g of sodium thiosulfate pentahydrate was dissolved in 50mL of deionized water, and 1.16g of PVP was dissolved in 50mL of deionized water. The two solutions were mixed at room temperature. 0.4mL of concentrated hydrochloric acid was then added to the mixture, and the mixture was allowed to react and stirred at room temperature for 2 hours. The precipitate was collected by centrifugation and washed once with a 0.8mM aqueous solution of PVP. The collected precipitate was redispersed in 10mL of a 0.8mM aqueous solution of PVP. The homogeneous dispersion was diluted to 40mL with deionized water. 0.2212g of KMnO₄ was then added to the diluted solution. The mixture was reacted at 70°C with magnetic stirring for 5 minutes. The mixture was washed three times by alternating centrifugation with water and ethanol. The collected precipitate was dried at room temperature for 2 days to obtain hollow S-MnO₂ nanospheres. The hollow S-MnO2 nanospheres obtained above were dispersed in 100 mL of deionized water, and then 100 mg of FeCl3 was dissolved in the solution. 30 uL of pyrrole and 3 mL of concentrated hydrochloric acid were added to react for 1 hour. After filtration, black flocs were obtained. The above flocs were added to 25 mL of CS2 solution, and the sulfur was dissolved in the CS2 solution by ultrasonication for 5 minutes. The final product, polypyrrole manganese dioxide hollow nanospheres with sulfur removed, was obtained by filtration.

[0036] Example 2

[0037] First, 0.992g of sodium thiosulfate pentahydrate was dissolved in 50mL of deionized water, and 1g of PVP was dissolved in 50mL of deionized water. The two solutions were mixed at room temperature. 0.4mL of concentrated hydrochloric acid was then added to the mixture, and the mixture was allowed to react and stirred at room temperature for 2 hours. The precipitate was collected by centrifugation and washed once with a 0.8mM aqueous solution of PVP. The collected precipitate was redispersed in 10mL of a 0.8mM aqueous solution of PVP. 5mL of the homogeneous dispersion was diluted to 20mL with deionized water. 0.1106g of KMnO₄ was then added to the diluted solution. The mixture was reacted at 70°C with magnetic stirring for 5 minutes. The mixture was washed three times by alternating centrifugation with water and ethanol. The collected precipitate was dried at room temperature for 48 hours to obtain hollow S-MnO₂ nanospheres. The hollow S-MnO2 nanospheres obtained above were dispersed in 100 mL of deionized water, and then 100 mg of FeCl3 was dissolved in the solution. 30 uL of pyrrole and 2 mL of concentrated hydrochloric acid were added to react for 2 h. After filtration, black flocs were obtained. The above flocs were added to 25 mL of CS2 solution, and the sulfur was dissolved in the CS2 solution by ultrasonication for 5 min. The final product, polypyrrole manganese dioxide hollow nanospheres with sulfur removed, was obtained by filtration.

[0038] The scanning electron microscope of the S-MnO2 nanospheres prepared in Example 1 is as follows: Figure 1 shown.

[0039] Figure 2 This is a scanning electron microscope image of ppy-MnO2 hollow nanospheres.

[0040] Figure 3 This is an electrochemical test diagram of a full battery assembled with this material as a precursor. From this diagram, we can see that the coulombic efficiency is still around 99.8% after the battery has undergone 500 cycles.

[0041] Obviously, the above embodiments are merely illustrative examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will recognize that any modifications, equivalent substitutions, or improvements based on the above description and within the methods and principles of the present invention are intended to be within the scope of protection of the present invention. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing polypyrrole manganese dioxide hollow nanospheres, characterized in that: The preparation method comprises the following steps: Step 1: Dissolve sodium thiosulfate pentahydrate in water and PVP in water, mix the two solutions at room temperature to form a mixed solution, then add concentrated hydrochloric acid to the mixed solution and react under stirring; Step 2: Collecting the precipitate by centrifugation to obtain hollow nano-sulfur spheres, washing them once with a PVP aqueous solution, and redispersing the collected hollow nano-sulfur spheres in the PVP aqueous solution to form a uniform dispersion, and diluting the uniform dispersion with water to obtain a diluted solution; Step 3: After adding KMnO4 to the diluted solution, react at 70°C with magnetic stirring, wash alternately with water and ethanol by centrifugation, and dry the collected precipitate to obtain hollow S-MnO2 nanospheres; Step 4: Disperse the hollow S-MnO2 nanospheres into water, dissolve FeCl3 in the dispersion, add pyrrole and concentrated hydrochloric acid, stir and react, and filter to obtain black floccules; Step 5: Add the above black flocs to the CS2 solution, dissolve the sulfur in the CS2 solution by ultrasonication, and filter to obtain the sulfur-removed polypyrrole manganese dioxide hollow nanospheres.

2. The method for preparing polypyrrole manganese dioxide hollow nanospheres according to claim 1, wherein In the step 1, the amount of sodium thiosulfate pentahydrate is 0.992 g, which is dissolved in 50 ml of deionized water. The molecular weight of PVP is 58,000, and the mass concentration of the PVP solution is 1% to 3%.

3. The method for preparing polypyrrole manganese dioxide hollow nanospheres according to claim 1, wherein In the step 1, the concentration of concentrated hydrochloric acid is 12M, and the stirring reaction time is 2h~3h.

4. The method for preparing polypyrrole manganese dioxide hollow nanospheres according to claim 1, wherein: In the step 2, the concentration of the PVP aqueous solution is 0.8 mmol / L, and the dilution ratio of the uniform dispersion is 4 times.

5. The method for preparing polypyrrole manganese dioxide hollow nanospheres according to claim 1, wherein: In the step 3, the mass ratio of the diluted solution to KMnO4 is 200:1, and the stirring reaction time is 5 min to 30 min.

6. The method for preparing polypyrrole manganese dioxide hollow nanospheres according to claim 1, wherein: In step 3, the centrifugal washing was performed three times, and the precipitate was dried at room temperature for 36 h to 48 h.

7. The method for preparing polypyrrole manganese dioxide hollow nanospheres according to claim 1, characterized in that: In the step 4, the S-MnO2 nanospheres are dispersed in 100 mL of deionized water, the amount of FeCl3 added is 100 mg, the amount of pyrrole added is 30 μL, the amount of concentrated hydrochloric acid added is 2 mL~3 mL, the reaction stirring time is 1 h~6 h, and black flocs are obtained after filtration.

8. The method for preparing polypyrrole manganese dioxide hollow nanospheres according to claim 1, wherein: Step 5: The volume of CS2 is 25 mL, and the ultrasonic reaction time is 5 min to 30 min.

9. A button battery, characterized in that The polypyrrole manganese dioxide hollow nanospheres prepared by the preparation method of polypyrrole manganese dioxide hollow nanospheres according to any one of claims 1 to 8 are used as the negative electrode material of a button lithium battery.

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