Preparation method and application of composite material of reduced graphene oxide loaded amorphous lead

Abstract

The application relates to the technical field of lead-carbon batteries, and aims to provide a preparation method of a composite material of reduced graphene oxide loaded amorphous lead. The method comprises the following steps: adding ammonia water into a lead nitrate solution containing polyvinylpyrrolidone and uniformly mixing, then adding a sodium hypochlorite solution to perform an oxidation reaction; performing a hydrothermal reaction on the obtained solution, washing and drying a white product obtained in the reaction to obtain lead nitrate hydroxide powder; sequentially adding sodium dodecyl sulfate, lead nitrate hydroxide and ascorbic acid into a graphene oxide dispersion liquid and uniformly mixing, and performing a reduction reaction under oil bath conditions; after centrifugal washing and product collection, the product is dispersed in deionized water, and a black powder composite material product is obtained through condensation and freeze drying. The composite material can inhibit the oxygen evolution phenomenon on the surface of reduced graphene oxide, accelerate the electrochemical oxidation reaction, promote the formation of positive active material as a positive electrode additive, and greatly improve the cycle life through the pore-forming agent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lead-carbon batteries, and particularly relates to a preparation method of a reduced graphene oxide loaded amorphous lead composite material and application of the composite material in a positive electrode of a lead-carbon battery. BACKGROUND

[0002] Lead-acid batteries (LAB) are a traditional secondary battery that can act as a replacement for fossil energy and contribute to reducing carbon dioxide emissions. They are more sustainable than lithium batteries due to their lower price cost and higher recycling rate. Due to their mature technology and high safety, lead-acid batteries are attracting attention as automotive electrodes for idling, start-stop (ISG) vehicles, hybrid electric vehicles (HEV), start-lighting (SLI) vehicles and vehicles using continuous power supply. However, in these application scenarios, lead-acid batteries must be operated under high rate partial state of charge (HRPSoC). In this working state, lead-acid batteries will form lead sulfate with large grains, which will rapidly reduce the service life, leading to permanent sulfation, grid corrosion, acid stratification, active material shedding and electrolyte loss during long-term operation. Studies have shown that the key factor to alleviate sulfation is the additive of active material. In order to cope with these challenges, carbon is added to lead-acid batteries to form carbon-enhanced lead-acid batteries (i.e. lead-carbon batteries, LCBs).

[0003] However, due to the strong oxidation ability of the positive active material and the high potential of the positive electrode during charging, traditional carbon materials such as activated carbon, carbon black and mesoporous carbon are extremely easy to be oxidized during the cycle process and lose their function. Secondly, carbon materials usually have a low oxygen evolution overpotential, so they will not only inhibit the sulfation of the positive electrode but also exacerbate the oxygen evolution reaction of the positive plate during the charging process. Severe oxygen evolution reaction can easily cause electrolyte dryness and electrode grid passivation, thus leading to battery failure and reducing the cycle life of the battery. In addition, nanoscale carbon material additives have high surface energy and are easy to agglomerate, and their affinity with lead is poor, so the additive is unevenly distributed in the positive active material and is difficult to play a role in constructing a conductive network, thereby limiting the improvement of the specific capacity of the positive electrode.

[0004] In view of the above problems, some researchers have prepared lead-carbon composite additives in order to improve the overall performance of the battery without introducing other impurities. However, the prepared additives are only large particle lead oxides loaded on a carbon matrix or simple physical mixing. Although this can alleviate the oxygen evolution phenomenon to some extent, it cannot improve the affinity of the additive and the active material, and it sacrifices the active sites for reaction with the active material and exposes some active sites for oxygen evolution reaction.

[0005] Based on the above reasons, the applicant proposes a new design and development scheme to prepare a reduced graphene oxide loaded amorphous lead composite material that meets the application requirements. SUMMARY

[0006] The technical problem solved by the present application is to overcome the deficiencies in the prior art and provide a preparation method and application of a reduced graphene oxide loaded amorphous lead composite material.

[0007] To solve the technical problem, the technical solution adopted by the present application is:

[0008] A preparation method of a reduced graphene oxide loaded amorphous lead composite material is provided, comprising the following steps:

[0009] (1) Dissolve lead nitrate and polyvinylpyrrolidone (PVP) in deionized water to obtain a lead nitrate (Pb(NO3)2) solution; add ammonia water to the lead nitrate solution and mix uniformly, then add a sodium hypochlorite (NaClO) solution for oxidation reaction to obtain a milky white solution;

[0010] (2) Transfer the solution obtained in step (1) to a polytetrafluoroethylene high-pressure reaction kettle for hydrothermal reaction; after the reaction is completed and cooled to room temperature, the obtained white product is sequentially washed by centrifugation with anhydrous ethanol and deionized water, and then vacuum dried to obtain a white powder of lead hydroxide nitrate (Pb3(NO3)(OH)5);

[0011] (3) Add sodium dodecyl sulfate (C 12 H 25 SO4Na) to the graphene oxide dispersion (GO), and then disperse the white powder of lead hydroxide nitrate obtained in step (2) therein; continue to add ascorbic acid and mix uniformly, the mass ratio of ascorbic acid to graphene oxide being 4:1; perform reduction reaction under oil bath conditions, and after the reaction is completed, cool to room temperature, centrifuge, wash, and collect the product;

[0012] (4) Disperse the product obtained in step (3) in deionized water, condense at -50°C for 8 hours, and then freeze-dry to obtain a black powder of Pb / rGO, which is the reduced graphene oxide loaded amorphous lead composite material.

[0013] As a preferred scheme of the present application, in step (1), the amount relationship of polyvinylpyrrolidone, deionized water, lead nitrate, ammonia water (AR), and sodium hypochlorite solution is 500mg:35ml:600mg:0.85ml:2ml.

[0014] As a preferred scheme of the present application, in step (1), 10mg of sodium hypochlorite is dissolved in 2ml of deionized water to obtain a sodium hypochlorite solution.

[0015] As a preferred scheme of the present application, in the step (1), after the ammonia water (AR) is added, stirring is carried out for 1 hour, and after the sodium hypochlorite solution is added, stirring is continued for 1 hour.

[0016] As a preferred scheme of the present application, in the step (2), the hydrothermal reaction temperature is 90℃, and the time is 12 hours.

[0017] As a preferred scheme of the present application, in the step (2), the vacuum drying temperature is 60℃, and the time is 4 hours.

[0018] As a preferred scheme of the present application, in the step (3), first, the sodium dodecyl sulfate is added into the graphene oxide dispersion liquid and ultrasonic dispersion is carried out for 20 minutes, then the lead nitrate hydroxide powder is added and stirring is carried out for 2-4 hours, and then the ascorbic acid is added and stirring is continued for 1 hour; the dosage relationship of the graphene oxide dispersion, the sodium dodecyl sulfate, the lead nitrate hydroxide and the ascorbic acid is 20ml:10.4mg:180mg:160mg, and the concentration of the graphene oxide dispersion liquid is 2mg / ml.

[0019] As a preferred scheme of the present application, in the step (3), the temperature of the reduction reaction is 90℃, and the time is 3-6 hours.

[0020] As a preferred scheme of the present application, in the step (4), the temperature of the freeze drying is -50℃, and the time is 24 hours.

[0021] The present application further provides an application method of the reduced graphene oxide loaded amorphous lead composite material obtained by the aforementioned method, characterized in that the composite material is used as a positive electrode additive; comprising the following steps:

[0022] After the composite material is mixed with the lead powder, the stannous sulfate, the antimony trioxide, the 4BS seed and the short fiber uniformly according to a conventional processing process, deionized water and dilute sulfuric acid are added in sequence and stirred uniformly to obtain a positive electrode slurry, and then the lead-carbon battery positive electrode green plate is obtained through plate coating, acid immersion and solidification; in the positive electrode slurry, the mass ratio of the composite material to the lead powder is 0.3%-0.9%.

[0023] Invention principle description:

[0024] 1. Carbon materials are widely used as positive electrode additives of lead-carbon batteries due to their good electrical conductivity and large specific surface area, etc. However, due to the poor oxidation resistance of carbon materials at high potential, the poor affinity to lead, the high oxygen evolution overpotential and other characteristics, the carbon materials are not uniformly dispersed in the positive plate, the oxygen evolution reaction is intensified, and the mechanical structure in the charging and discharging process is damaged, etc., which limits the application of carbon materials in lead-carbon batteries.

[0025] 2. In the field of lead-carbon battery cathode additives, the anchoring composite technology of oxides or sulfides of elements such as lead, antimony, and bismuth with graphene can significantly enhance battery performance. However, this technology introduces impurities that affect recycling efficiency, and most anchoring composite technologies simply involve loading large metal oxides or sulfides onto a carbon matrix or simple physical mixing. While this alleviates oxygen evolution to some extent, it fails to improve the affinity between the additive and the active material, and it sacrifices the reactive sites of the active material and exposes some active sites used for oxygen evolution reactions, thus failing to significantly improve battery performance.

[0026] 3. In this invention, the negatively charged graphene oxide solution (ζ = -29.1 mV) electrostatically adsorbs the positively charged Pb3(NO3)(OH)5 solution (ζ = 11.4 mV), thereby attracting Pb. 2+ Lead is uniformly adsorbed onto the surface of graphene oxide; ascorbic acid is used to reduce graphene oxide to reduced graphene oxide, thereby optimizing the composite material composition and improving conductivity; during the hydrothermal reaction, lead is uniformly loaded in an amorphous form onto the surface of the reduced graphene oxide, further optimizing the composite material structure, thus obtaining a composite material of reduced graphene oxide loaded with amorphous lead. These steps are indispensable and cannot be reversed.

[0027] Compared with the prior art, the advantages of the present invention are as follows:

[0028] 1. The composite material of reduced graphene oxide supported on amorphous lead prepared in this invention, in which lead is loaded in an amorphous form on the reduced graphene oxide, can suppress proton adsorption, thereby suppressing oxygen evolution on the surface of the reduced graphene oxide, and can increase the specific capacitance of the positive electrode active material, thereby increasing the initial specific capacitance. Secondly, it can enhance the affinity of the reduced graphene oxide for the positive electrode active material, which helps to reduce the ohmic resistance of the lead / carbon contact, thereby accelerating the electrochemical oxidation reaction.

[0029] 2. The reduced graphene oxide-supported amorphous lead composite material prepared in this invention, when used as a cathode additive, can promote the formation of the cathode active material and increase the content of α-PbO2, thereby increasing its mechanical structural stability. Secondly, it acts as a pore-forming agent, enabling the cathode active material to form a structure similar to a stack of hollow spheres, thus significantly increasing the specific surface area of ​​the cathode active material, allowing for a more complete reaction with sulfuric acid and a substantial improvement in cycle life under HRPSoC.

[0030] 3. The composite material of reduced graphene oxide supported on amorphous lead prepared by the present invention has a large number of wrinkled microstructures and presents a three-dimensional curled shape. The lead on it exists in an amorphous form and does not cause damage to the structure. Because of its good conductivity, it can build a conductive path between positive electrode active materials and improve the utilization rate of positive electrode active materials.

[0031] 4. The composite material of reduced graphene oxide supported on amorphous lead prepared in this invention has good affinity with the positive electrode grid and has good conductivity and oxidation resistance, which can alleviate the corrosion rate of the positive electrode grid. Attached Figure Description

[0032] Figure 1 This is a scanning electron microscope (SEM) image of the Pb / rGO-3h sample prepared in Example 1 of this invention.

[0033] Figure 2 This is a scanning electron microscope (SEM) image of the Pb / rGO-4h sample prepared in Example 2 of the present invention.

[0034] Figure 3 This is a scanning electron microscope (SEM) image of the Pb / rGO-6h sample prepared in Example 3 of the present invention.

[0035] Figure 4 The XRD patterns are those of the Pb / rGO-3h sample prepared in Example 1 of this invention and the rGO sample in Comparative Example 2.

[0036] Figure 5 The X-ray photoelectron spectroscopy (XPS) of the Pb / rGO-3h sample prepared in Example 1 of this invention.

[0037] Figure 6 This is a transmission electron microscope (TEM) image of the Pb / rGO-3h sample prepared in Example 1 of the present invention.

[0038] Figure 7 The LSV curves of the positive electrode plates prepared in Comparative Examples 1, 2 and 1 of this invention at a scan rate of 5 mV / s are shown.

[0039] Figure 8 The cycle life of the positive electrode plates prepared in Comparative Examples 1, 2 and 1 of this invention at a 1C rate is given.

[0040] Figure 9 The cycle life of the positive electrode plates prepared in Comparative Examples 1, 2 and 2-3 at a 1C rate is given.

[0041] Figure 10 The initial specific capacity of the positive electrode plates prepared in Comparative Example 1, Comparative Example 2 and Example 1 at 0.2C. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0043] The prepared reduced graphene oxide loaded amorphous lead composite (Pb / rGO) can be used as a positive electrode additive. The specific application method is as follows: the composite material is uniformly mixed with lead powder, stannous sulfate, antimony trioxide, 4BS seed crystal and short fiber according to a conventional treatment process, then deionized water and dilute sulfuric acid are sequentially added and stirred to obtain a positive electrode slurry, and then the positive electrode slurry is coated, immersed in acid and solidified to obtain a lead-carbon battery positive electrode plate; in the positive electrode slurry, the mass ratio of the composite material to lead powder is 0.3% to 0.9%.

[0044] The conventional treatment process and the type and ratio of other materials in the positive electrode slurry can be selected by a skilled person according to the existing disclosed lead-carbon battery design scheme, and the present application does not make special requirements.

[0045] Example 1

[0046] (1) 500 mg of polyvinylpyrrolidone (PVP) was weighed and dissolved in 35 ml of deionized water; 600 mg of lead nitrate was weighed and dissolved therein to obtain a lead acetate solution; 0.85 ml of ammonia water (AR) was first added to the lead nitrate solution and stirred for 1 hour; 10 mg of sodium hypochlorite was weighed and dissolved in 2 ml of deionized water to obtain a sodium hypochlorite solution. Then 2 ml of the sodium hypochlorite solution was added to the lead acetate solution and stirred for 1 h to obtain a milky white solution.

[0047] (2) The solution obtained in step (1) was transferred to a polytetrafluoroethylene high-pressure reaction kettle for hydrothermal reaction, the hydrothermal reaction temperature was 90℃, and the time was 12 hours; after cooling to room temperature, the obtained white product was centrifuged under the condition of 9000 r / min, and then washed with anhydrous ethanol and deionized water, respectively; then the centrifuged product was vacuum dried at 60℃ for 4 hours to obtain a white powder of lead hydroxide nitrate (Pb3(NO3)(OH)5);

[0048] (3) 10.4 mg of sodium dodecyl sulfate was first added to 20 ml of graphene oxide dispersion (2 mg / ml) and ultrasonically dispersed for 20 minutes; then 180 mg of the prepared lead hydroxide nitrate powder in step (2) was added and stirred for 2 hours; then 160 mg of ascorbic acid was added and stirred for 1 hour; then it was placed in an oil bath at 90℃ and stirred for 3 h for reduction reaction. After cooling to room temperature, it was centrifuged under the condition of 9000 r / min, and then washed with anhydrous ethanol and deionized water, respectively.

[0049] (4) The sample obtained in step (3) was dispersed in 2 ml of deionized water, and after condensation at-50℃ for 8 hours, the vacuum pump was opened and freeze-dried at-50℃ for 24 hours to obtain a black powder sample, marked as Pb / rGO-3h.

[0050] (5) Different mass fractions of Pb / rGO (0.3wt%, 0.5wt%, 0.7wt%, 0.9wt% relative to lead powder) were used as positive electrode additives and mixed uniformly with lead powder (100wt%), antimony trioxide (0.1wt%), stannous sulfate (0.1wt%), 4BS crystal seeds (2.0wt%), short fibers (0.1wt%), deionized water (10.0wt%), and dilute sulfuric acid (11.0wt%, 1.26g·cm -3 ) to coat the lead grid after curing to obtain lead-acid battery positive plate, denoted as Pb / rGO-3h-0.3%, Pb / rGO-3h-0.5%, Pb / rGO-3h-0.7%, Pb / rGO-3h-0.9%.

[0051] Example 2

[0052] (1) 500mg of polyvinylpyrrolidone (PVP) was weighed and dissolved in 35ml of deionized water; 600mg of lead nitrate was then weighed and dissolved in it to obtain a lead acetate solution; 0.85ml of ammonia water (AR) was first added to the lead nitrate solution and stirred for 1 hour; 10mg of sodium hypochlorite was then weighed and dissolved in 2ml of deionized water to obtain a sodium hypochlorite solution. Then 2ml of sodium hypochlorite solution was added to the lead acetate solution and stirred for 1h to obtain a milky white solution.

[0053] (2) The solution obtained in step (1) was transferred to a polytetrafluoroethylene high-pressure reaction kettle for hydrothermal reaction, with a hydrothermal reaction temperature of 90℃ and a time of 12 hours; after cooling to room temperature, the white product obtained was centrifuged under the condition of 9000r / min, and then washed with absolute ethanol and deionized water, respectively; finally, the centrifuged product was vacuum dried at 60℃ for 4 hours to obtain white lead nitrate hydroxide (Pb3(NO3)(OH)5) powder;

[0054] (3) 10.4mg of sodium dodecyl sulfate was first added to 20ml of graphene oxide dispersion (2mg / ml) and ultrasonically dispersed for 20 minutes; then 180mg of lead nitrate hydroxide powder prepared in step (2) was added and stirred for 3 hours; 160mg of ascorbic acid was then added and stirred for 1 hour; then it was placed in an oil bath at 90℃ and stirred for 4h for reduction reaction. After cooling to room temperature, it was centrifuged under the condition of 9000r / min, and then washed with absolute ethanol and deionized water, respectively.

[0055] (4) The sample obtained in step (3) was dispersed in 2ml of deionized water, and after condensation at -50℃ for 8 hours, vacuum drying was carried out at -50℃ for 24 hours to obtain a black powder sample, labeled as Pb / rGO-4h.

[0056] (5) 0.7wt% of Pb / rGO (relative to lead powder) was used as a positive electrode additive to mix with lead powder (100wt%), diantimony trioxide (0.1wt%), stannous sulfate (0.1wt%), 4BS seed crystal (2.0wt%), short fiber (0.1wt%), deionized water (10.0wt%) and dilute sulfuric acid (11.0wt%, 1.26g·cm -3 ) uniformly, and then coated on the lead grid to obtain a lead-acid battery positive electrode plate after curing, which was marked as Pb / rGO-4h-0.7%.

[0057] Example 3

[0058] (1) 500mg of polyvinylpyrrolidone (PVP) was weighed and dissolved in 35ml of deionized water; 600mg of lead nitrate was then weighed and dissolved in the solution to obtain a lead acetate solution; 0.85ml of ammonia water (AR) was first added to the lead nitrate solution and stirred for 1 hour; 10mg of sodium hypochlorite was then dissolved in 2ml of deionized water to obtain a sodium hypochlorite solution. Then 2ml of the sodium hypochlorite solution was added to the lead acetate solution and stirred for 1h to obtain a milky white solution.

[0059] (2) The solution obtained in step (1) was transferred to a polytetrafluoroethylene high-pressure reaction kettle for hydrothermal reaction, with a hydrothermal reaction temperature of 90°C and a reaction time of 12 hours; after cooling to room temperature, the obtained white product was centrifuged at 9000r / min and sequentially washed with anhydrous ethanol and deionized water, and then the centrifuged product was vacuum dried at 60°C for 4 hours to obtain a white powder of lead nitrate hydroxide (Pb3(NO3)(OH)5);

[0060] (3) 10.4mg of sodium dodecyl sulfate was first added to 20ml of graphene oxide dispersion (2mg / ml) and ultrasonically dispersed for 20 minutes; then 180mg of the lead nitrate hydroxide powder prepared in step (2) was added and stirred for 4 hours; 160mg of ascorbic acid was then added and stirred for 1 hour; and then the mixture was placed in an oil bath at 90°C and stirred for 6h for reduction reaction. After cooling to room temperature, the mixture was centrifuged at 9000r / min and sequentially washed with anhydrous ethanol and deionized water.

[0061] (4) The sample obtained in step (3) was dispersed in 2ml of deionized water, and after condensation at -50°C for 8 hours, vacuum freeze-drying was performed at -50°C for 24 hours to obtain a black powder sample, which was marked as Pb / rGO-6h.

[0062] (5) 0.7wt% of Pb / rGO (relative to lead powder) was used as positive electrode additive to mix with lead powder (100wt%), antimony trioxide (0.1wt%), stannous sulfate (0.1wt%), 4BS seed crystal (2.0wt%), short fiber (0.1wt%), deionized water (10.0wt%) and dilute sulfuric acid (11.0wt%, 1.26g·cm -3 ) uniformly after coating on the lead grid, and the lead-acid battery positive plate was obtained after curing. It is recorded as Pb / rGO-6h-0.7%.

[0063] Comparative Example 1

[0064] Lead powder (100wt%), antimony trioxide (0.1wt%), stannous sulfate (0.1wt%), 4BS seed crystal (2.0wt%), short fiber (0.1wt%), deionized water (10.0wt%) and dilute sulfuric acid (11.0wt%, 1.26g·cm -3 ) were mixed uniformly after coating on the lead grid, and the lead-acid battery positive plate was obtained after curing. It is recorded as C1-0.0%.

[0065] Comparative Example 2

[0066] (1) 10.4mg of sodium dodecyl sulfate was first added to 20ml of graphene oxide dispersion (2mg / ml), ultrasonic dispersion for 20 minutes, stirring for 1 hour; then 160mg of ascorbic acid was added, stirring for 1 hour; then put into an oil bath at 90℃ for 3h. After cooling to room temperature, centrifugal cleaning was carried out with anhydrous ethanol and deionized water under the condition of 9000r / min.

[0067] (2) The sample obtained in step (1) was dispersed in 2ml of deionized water, and after condensation at-50℃ for 8 hours, the vacuum pump was opened and freeze-dried at-50℃ for 24 hours to obtain a black powder sample, marked as rGO.

[0068] (3) 0.7wt% (relative to lead powder) of reduced graphene oxide (rGO) was used as a positive electrode additive to mix with lead powder (100wt%), antimony trioxide (0.1wt%), stannous sulfate (0.1wt%), 4BS seed crystal (2.0wt%), short fiber (0.1wt%), deionized water (10.0wt%) and dilute sulfuric acid (11.0wt%, 1.26g·cm -3 ) uniformly after coating on the lead grid, and the lead-acid battery positive plate was obtained after curing. It is recorded as C2-rGO-0.7%.

[0069] Effect of implementation

[0070] Figures 1-3The scanning electron microscope photos of the Pb / rGO-3h, Pb / rGO-4h and Pb / rGO-6h samples show that the three-dimensional curly structure of the composite of reduced graphene oxide loaded with amorphous lead is found, there is no particulate matter on the surface, the loading of amorphous lead does not cause damage to the three-dimensional structure, thereby having a larger specific surface area. The Pb / rGO will be stacked to a certain extent as the time of the thermal reduction reaction becomes longer.

[0071] Figure 4 The XRD spectra of the Pb / rGO-3h sample and the rGO sample prove that the reduction process of ascorbic acid is relatively successful and the Pb / rGO-3h only shows the characteristic peaks corresponding to the rGO without other characteristic peak positions, which proves that the Pb is uniformly distributed on the rGO in the form of amorphous.

[0072] Figure 5 The XPS spectrum of the Pb / rGO-3h sample proves that the amorphous lead is anchored on the reduced graphene oxide by forming a COO / CO-Pb bond between the amorphous lead and the reduced graphene oxide.

[0073] Figure 6 The TEM photo of the Pb / rGO-3h sample can see that the amorphous lead is uniformly arranged on the surface of the reduced graphene oxide.

[0074] Figure 7 The LSV curves of the positive electrode plates prepared in the comparative example 1, the comparative example 2 and the example 1 at a scan rate of 5 mV / s prove that the occurrence of the positive electrode oxygen evolution reaction can be effectively inhibited by loading the amorphous lead on the reduced graphene oxide.

[0075] Figure 8 The cycle life of the positive electrode plates prepared in the comparative example 1, the comparative example 2 and the example 1 at a 1C rate shows that the cycle life of the battery at the optimal additive amount, i.e. the Pb / rGO-3h-0.7% loading level, is 2.04 times that of the sample in the comparative example 1 and 2.54 times that of the sample in the comparative example 2, proving that the cycle life of the battery can be significantly improved by introducing the Pb / rGO-3h additive.

[0076] Figure 9 The cycle life of the positive electrode plates prepared in the comparative example 1, the comparative example 2 and the example 2-3 at a 1C rate shows that the cycle life of the battery at the Pb / rGO-4h-0.7% and Pb / rGO-6h-0.7% loading levels is better than that of the sample in the comparative example 1 and the sample in the comparative example 2, and the cycle life of the Pb / rGO-4h-0.7% is between that of the Pb / rGO-6h-0.7% and the Pb / rGO-3h-0.7%.

[0077] Figure 10From the initial specific capacity of the positive plate prepared in Comparative Example 1, Comparative Example 2 and Example 1 at 0.2C, it can be seen that the initial specific capacity of the battery at the optimal additive amount, i.e. the Pb / rGO-3h-0.7% loading level, is 2.17 times that of the sample in Comparative Example 1 and 1.12 times that of the sample in Comparative Example 2, proving that the initial specific capacity of the battery can be significantly improved by introducing the Pb / rGO additive.

[0078] It should be noted that the above examples are only used to illustrate the present application and not used to limit the scope of the present application. Furthermore, it should be understood that after reading the content of the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope defined by the claims of the present application.

Claims

1. A method for preparing a composite material of reduced graphene oxide supported amorphous lead, characterized by, The method comprises the following steps: (1) dissolving lead nitrate and polyvinylpyrrolidone in deionized water to obtain a mixed solution containing lead nitrate; adding ammonia water into the mixed solution and mixing uniformly, and then adding sodium hypochlorite solution to perform an oxidation reaction to obtain a milky white solution; wherein the amount ratio of polyvinylpyrrolidone, deionized water, lead nitrate, ammonia water and sodium hypochlorite solution is 500 mg: 35 ml: 600 mg: 0.85 ml: 2 ml; in the sodium hypochlorite solution, the amount ratio of sodium hypochlorite and deionized water is 10 mg: 2 ml; stirring for 1 hour after adding the ammonia water, and stirring for 1 hour after adding the sodium hypochlorite solution; (2) transferring the solution obtained in step (1) into a polytetrafluoroethylene high-pressure reaction kettle to perform a hydrothermal reaction; after the reaction is completed and cooled to room temperature, the obtained white product is centrifuged and cleaned with anhydrous ethanol and deionized water in sequence, and then vacuum dried to obtain a white lead hydroxide nitrate powder; (3) adding sodium dodecyl sulfate into a graphene oxide dispersion solution, and then dispersing the white lead hydroxide nitrate powder obtained in step (2) in the graphene oxide dispersion solution; continuously adding ascorbic acid and mixing uniformly, the mass ratio of ascorbic acid to graphene oxide being 4:1; performing a reduction reaction under an oil bath condition, and after the reaction is completed, cooling to room temperature, centrifuging, cleaning and collecting the product; (4) dispersing the product obtained in step (3) in deionized water, condensing at-50℃ for 8 hours, and then freeze-drying to obtain a Pb / rGO black powder, which is a reduced graphene oxide loaded amorphous lead composite material.

2. The method of claim 1, wherein, In step (2), the hydrothermal reaction temperature is 90℃, and the time is 12 hours.

3. The method of claim 1, wherein, In step (2), the vacuum drying temperature is 60℃, and the time is 4 hours.

4. The method of claim 1, wherein, In step (3), the sodium dodecyl sulfate is first added into the graphene oxide dispersion solution and ultrasonically dispersed for 20 minutes, then the lead hydroxide nitrate powder is added and stirred for 2-4 hours, and then the ascorbic acid is added and stirred for 1 hour; the amount ratio of the graphene oxide dispersion, the sodium dodecyl sulfate, the lead hydroxide nitrate and the ascorbic acid is 20 ml: 10.4 mg: 180 mg: 160 mg, and the concentration of the graphene oxide dispersion is 2 mg / ml.

5. The method of claim 1, wherein, In step (3), the reduction reaction temperature is 90℃, and the time is 3-6 hours.

6. The method of claim 1, wherein, In step (4), the freeze-drying temperature is-50℃, and the time is 24 hours.

7. The method of using the reduced graphene oxide supported amorphous lead composite material obtained by the method of any one of claims 1 to 6, characterized in that, The composite material is used as a positive electrode additive; comprising the following steps: mixing the composite material with lead powder, stannous sulfate, antimony trioxide, 4BS seed and short fibers uniformly according to a conventional processing process, then adding deionized water and dilute sulfuric acid in sequence and stirring uniformly to obtain a positive electrode slurry, and then performing plate coating, acid immersion and solidification to obtain a lead-carbon battery positive electrode green plate; in the positive electrode slurry, the mass ratio of the composite material to lead powder is 0.3%-0.9%.

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