Doped porous carbon / lead composite negative electrode material and preparation method thereof

Abstract

The invention provides a doped porous carbon / lead composite negative electrode material and a preparation method thereof, and belongs to the technical field of battery materials, the composite negative electrode material comprises the following raw materials by weight: 95-100 parts of lead powder, 0.4-0.6 part of barium sulfate, 0.2-0.4 part of humic acid, 0.1-0.3 part of zinc stannate, 0.08-0.12 part of carbon black, 0.08-0.12 part of composite fiber, and 1.0-1.5 parts of doped porous carbon / lead powder; wherein the doped porous carbon / lead powder is prepared from the following raw materials: chitosan, dicyandiamide, thiourea, lead citrate and sodium borohydride. According to the prepared composite negative electrode material, the chemical property of the carbon surface is optimized by doping heteroatoms, and the growth of lead dendrites is inhibited by utilizing a porous structure, so that the cycle life and the performance of a battery are effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, and particularly relates to a doped porous carbon / lead composite anode material and its preparation method. Background Technology

[0002] With the rapid development of industries such as new energy vehicles and renewable energy power generation, higher requirements have been placed on the cycle life and reliability of energy storage batteries. In the field of new energy vehicles, batteries need to have a long lifespan to reduce replacement costs and improve ease of use; in the field of renewable energy storage, batteries need to be able to withstand frequent charge-discharge cycles to stably store and release energy. Lead-carbon batteries, as an important energy storage device, have wide applications in renewable energy storage, electric vehicles, and backup power supplies, and they have advantages such as low cost, high safety, and good high-current discharge performance. However, traditional lead-carbon batteries suffer from short cycle life, making it difficult to meet the needs of these emerging markets and hindering their further development and promotion.

[0003] Currently, the battery industry is developing towards high energy density, long lifespan, and low cost. To gain an advantage in the fierce market competition, the lead-carbon battery industry needs continuous technological upgrades. The market urgently needs to develop long-life lead-carbon batteries, and high-performance anode materials are one of the keys to achieving this goal. In the production of lead-carbon batteries, the performance of the anode material plays a crucial role in the overall lifespan and performance of the battery. Traditional lead anodes are prone to lead dendrite growth and sulfation during charge and discharge, which leads to electrode structure damage, reduced utilization of active materials, and consequently, a significant shortening of the battery's cycle life. Furthermore, lead is a heavy metal, and improper handling of traditional lead anodes during production and use can pollute the environment. Improving the cycle life of lead-carbon batteries can reduce the frequency of battery replacement, thereby reducing lead consumption and waste generation, which aligns with environmental protection and sustainable development requirements.

[0004] Porous carbon materials possess advantages such as high specific surface area, good conductivity, and abundant pore structure, making them highly promising as electrode material carriers in the battery field. Embedding lead nanoparticles into porous carbon networks can utilize the porous structure to suppress lead dendrite growth, providing more deposition sites for lead and improving the utilization rate of active materials. However, the surface chemistry of pure porous carbon materials is relatively inert, resulting in a high deposition energy barrier for lead, which is detrimental to uniform lead deposition and electrochemical reactions. Electrochemical co-deposition technology is a method for simultaneously depositing multiple substances on the electrode surface, offering advantages such as ease of operation and strong controllability. With the continuous deepening of research on battery electrode materials, electrochemical co-deposition technology has been increasingly applied in the preparation of composite electrode materials. Using this technology to embed lead nanoparticles into porous carbon networks holds promise for achieving uniform composite of lead and porous carbon, forming composite anode materials with good conductivity and suitable structure.

[0005] In conclusion, the development of a doped porous carbon / lead composite anode material and its preparation method is of great practical significance. It is not only a key technical approach to solving the problem of short cycle life in lead-carbon batteries, but also an inevitable requirement to meet market demand, promote technological upgrading in the industry, and achieve environmental protection and sustainable development. Summary of the Invention

[0006] The purpose of this invention is to provide a doped porous carbon / lead composite anode material that optimizes the chemical properties of the carbon surface by doping with heteroatoms and suppresses lead dendrite growth by utilizing the porous structure, thereby effectively improving the cycle life and performance of the battery.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a doped porous carbon / lead composite anode material, which is made from the following raw materials in parts by weight:

[0009] 95-100 parts lead powder, 0.4-0.6 parts barium sulfate, 0.2-0.4 parts humic acid, 0.1-0.3 parts zinc stannate, 0.08-0.12 parts carbon black, 0.08-0.12 parts composite fiber, and 1.0-1.5 parts doped porous carbon / lead powder.

[0010] Barium sulfate can act as a nucleus for lead sulfate, a product of negative electrode discharge, preventing the formation of a lead sulfate passivation layer covering the electrode. When dispersed in lead powder active material, barium sulfate maintains high porosity of the negative electrode, reduces the tendency of sponge lead crystal particles to agglomerate and shrink, improves the discharge performance of the negative electrode, and extends battery life. Humic acid can inhibit negative electrode passivation, improve battery capacity and cold-start discharge performance, enhance battery charge acceptance, and extend battery life. Zinc stannate can reduce its impact on the structural stability of the negative electrode; its addition reduces impedance and hydrogen evolution, increasing battery life. Carbon black has high dynamic charge acceptance, which can improve cycle life under partial charge conditions.

[0011] Preferably, the method for preparing the doped porous carbon / lead powder includes the following steps:

[0012] Chitosan was soaked in an aqueous citric acid solution, filtered, and dried to obtain a pretreated material. The pretreated material, dicyandiamide, and thiourea were mixed and stirred evenly, heated and calcined under a nitrogen atmosphere, cooled, and ground into powder to obtain doped porous carbon.

[0013] Doped porous carbon was added to an aqueous solution of lead citrate, sonicated, and then an aqueous solution of sodium borohydride was added. The mixture was then heated under a nitrogen atmosphere to carry out a reduction reaction, filtered, dried, and ground into powder to obtain doped porous carbon / lead powder.

[0014] Embedding lead nanoparticles into porous carbon material networks can suppress lead dendrite growth by utilizing the porous structure, providing more deposition sites for lead and improving the utilization rate of active materials. However, the surface chemical properties of porous carbon materials are relatively inert, and the deposition energy barrier for lead on their surface is relatively high, which is not conducive to uniform lead deposition and electrochemical reactions.

[0015] Therefore, this invention optimizes the chemical properties of the carbon surface by doping the porous carbon framework with heteroatoms such as nitrogen and sulfur, introducing more active sites and lowering the lead deposition energy barrier, thereby further improving the performance of the electrode material. By using pre-embedded lead nanoparticles as nucleation sites, irreversible sulfation during the first charge-discharge cycle can be reduced, further enhancing the utilization rate of the active material. The doped porous carbon / lead composite anode material increases the utilization rate of the active material, improves energy density, and reduces lead waste. Its preparation process is green and environmentally friendly, further promoting the sustainable development of the lead-carbon battery industry.

[0016] Preferably, the weight ratio of chitosan to citric acid aqueous solution is 20-40:40-60.

[0017] Preferably, the weight ratio of the pretreated material, dicyandiamide, and thiourea is 5-15:2-8:1-3.

[0018] Preferably, the weight ratio of the doped porous carbon, lead citrate aqueous solution, and sodium borohydride aqueous solution is 1-2:3-6:0.2-0.5.

[0019] Preferably, the method for preparing the doped porous carbon / lead powder includes the following steps:

[0020] By weight, 20-40 parts of chitosan are added to 40-60 parts of citric acid aqueous solution and soaked for 0.5-2 hours, filtered, and dried to obtain pretreated material; 5-15 parts of pretreated material, 2-8 parts of dicyandiamide, and 1-3 parts of thiourea are mixed and stirred evenly, heated and calcined under nitrogen atmosphere, cooled to room temperature, and ground into powder to obtain doped porous carbon.

[0021] Add 1-2 parts of doped porous carbon to 3-6 parts of lead citrate aqueous solution, sonicate for 20-40 min, then add 0.2-0.5 parts of sodium borohydride aqueous solution, heat to 40-45℃ under nitrogen atmosphere for 0.5-1.5 h for reduction reaction, filter, dry, grind into powder to obtain doped porous carbon / lead powder.

[0022] Preferably, the heating and calcination conditions are as follows: heating to 350-500℃ and holding for calcination for 1-2 hours, then raising the temperature to 800-900℃ and holding for calcination for 2-4 hours.

[0023] Preferably, the frequency of the ultrasound is 20-40kHz and the power is 100-300W.

[0024] Preferably, the concentration of the citric acid aqueous solution is 0.1-0.3M.

[0025] Preferably, the concentration of the lead citrate aqueous solution is 0.2-0.4M.

[0026] Preferably, the concentration of the sodium borohydride aqueous solution is 0.01-0.03M.

[0027] Preferably, the composite fiber is composed of carbon fiber and polyester fiber; the weight ratio of the carbon fiber to polyester fiber is 3-5:1.

[0028] The present invention also provides a method for preparing the above-mentioned doped porous carbon / lead composite anode material, comprising the following steps:

[0029] Lead powder, barium sulfate, humic acid, zinc stannate, carbon black, and composite fibers are added to a high-speed mixer and mixed for 10-20 minutes. Then, doped porous carbon / lead powder is added and the mixture is mixed for another 7-15 minutes. Water and sulfuric acid with a density of 1.2-1.4 g / mL are added and stirred evenly in a paste mixer to obtain a doped porous carbon / lead composite anode material.

[0030] Preferably, the high-speed mixer rotates at a speed of 500-800 rpm.

[0031] Preferably, the weight ratio of water to lead powder is 0.1-0.15:1.

[0032] Preferably, the weight ratio of sulfuric acid to lead powder is 0.06-0.1:1.

[0033] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0034] 1. This invention provides a method for preparing a doped porous carbon / lead composite anode material. By doping the porous carbon framework with heteroatoms such as nitrogen and sulfur to optimize the surface chemical properties of the porous carbon, more active sites are introduced, the deposition energy barrier of lead is reduced, and the porous structure is used to inhibit the growth of lead dendrites, thereby effectively improving the cycle life and performance of the battery. At the same time, the doped porous carbon / lead composite anode material can increase the utilization rate of active materials, improve energy density, and reduce lead waste, which is in line with the trend of technological upgrading in the industry. The development of this new anode material and its preparation method will help improve the technological level and competitiveness of my country's lead-carbon battery industry.

[0035] 2. In the raw material composition of the composite negative electrode material of the present invention, barium sulfate can serve as the nucleus for lead sulfate, a negative electrode discharge product, preventing the formation of a lead sulfate passivation layer covering the electrode, reducing the tendency of sponge lead crystal particles to stick and shrink, improving the discharge performance of the negative electrode, and extending the battery life; humic acid can inhibit the passivation of the negative electrode plate, improve the battery capacity and cold start discharge performance, improve the battery's charge acceptance capability, and extend the battery life; zinc stannate can reduce the impact on the structural stability of the negative electrode plate, and the addition of zinc stannate reduces impedance and hydrogen evolution, thus increasing the battery life; carbon black has high dynamic charge acceptance capability and can improve the cycle life under partial charge state. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The following are some of the raw materials used in the examples and comparative examples:

[0038] The lead powder was purchased from Shanghai Gelin Technology Co., Ltd., with a Pb content of >99.94%.

[0039] The carbon fiber was purchased from Shanghai Lishuo Composite Materials Technology Co., Ltd. as PAN-based short-cut carbon fiber, with a specification of 0.5mm.

[0040] The polyester fiber was purchased from Shandong Jinkeli Power Technology Co., Ltd., and its specification is 1.5mm.

[0041] The carbon black was purchased from Shandong Jinkeli Power Technology Co., Ltd., model number PBX09.

[0042] Chitosan was purchased from Shenzhen Lijin Biochemical Technology Co., Ltd., with an average molecular weight of 20,000 and a degree of deacetylation ≥95%.

[0043] Example 1

[0044] This embodiment provides a doped porous carbon / lead composite anode material, which is made from the following raw materials in parts by weight:

[0045] 97.5 parts lead powder, 0.5 parts barium sulfate, 0.3 parts humic acid, 0.2 parts zinc stannate, 0.1 parts carbon black, 0.1 parts composite fiber, and 1.3 parts doped porous carbon / lead powder.

[0046] The composite fiber is composed of carbon fiber and polyester fiber in a weight ratio of 4:1.

[0047] The method for preparing the doped porous carbon / lead powder includes the following steps:

[0048] By weight, 30 parts of chitosan were added to 50 parts of 0.15M citric acid aqueous solution and soaked for 1 hour. After filtration and drying, the pretreated material was obtained. 10 parts of the pretreated material, 4 parts of dicyandiamide and 2 parts of thiourea were mixed and stirred evenly. The mixture was heated to 400℃ and calcined for 1.5 hours under a nitrogen atmosphere. Then the temperature was raised to 850℃ and calcined for 3 hours. After cooling to room temperature, the mixture was ground into powder to obtain doped porous carbon.

[0049] 1.5 parts of doped porous carbon were added to 4.5 parts of 0.3M lead citrate aqueous solution and sonicated for 30 min at an ultrasonic frequency of 30 kHz and a power of 250 W. Then, 0.3 parts of 0.02M sodium borohydride aqueous solution were added and the mixture was heated to 42 °C under a nitrogen atmosphere for 1 h for reduction reaction. The mixture was then filtered, dried, and ground into powder to obtain doped porous carbon / lead powder.

[0050] This embodiment provides a method for preparing a doped porous carbon / lead composite anode material, including the following steps:

[0051] Lead powder, barium sulfate, humic acid, zinc stannate, carbon black, and composite fibers were added to a high-speed mixer and mixed for 15 minutes at 600 rpm. Then, doped porous carbon / lead powder was added and mixing continued for 10 minutes. Next, water and sulfuric acid with a density of 1.3 g / mL were added, and the mixture was stirred evenly in a paste mixer to obtain a doped porous carbon / lead composite anode material. The weight ratio of water to lead powder was 0.12:1, and the weight ratio of sulfuric acid to lead powder was 0.08:1.

[0052] Example 2

[0053] This embodiment provides a doped porous carbon / lead composite anode material, which is made from the following raw materials in parts by weight:

[0054] 95 parts lead powder, 0.4 parts barium sulfate, 0.2 parts humic acid, 0.1 parts zinc stannate, 0.08 parts carbon black, 0.08 parts composite fiber, and 1.0 parts doped porous carbon / lead powder.

[0055] The composite fiber is composed of carbon fiber and polyester fiber in a weight ratio of 3:1.

[0056] The preparation method of the doped porous carbon / lead powder is the same as that in Example 1.

[0057] This embodiment provides a method for preparing a doped porous carbon / lead composite anode material, including the following steps:

[0058] Lead powder, barium sulfate, humic acid, zinc stannate, carbon black, and composite fibers were added to a high-speed mixer and mixed for 10 minutes at 800 rpm. Then, doped porous carbon / lead powder was added and mixing continued for 15 minutes. Next, water and sulfuric acid with a density of 1.2 g / mL were added, and the mixture was stirred evenly in a paste mixer to obtain a doped porous carbon / lead composite anode material. The weight ratio of water to lead powder was 0.1:1, and the weight ratio of sulfuric acid to lead powder was 0.06:1.

[0059] Example 3

[0060] This embodiment provides a doped porous carbon / lead composite anode material, which is made from the following raw materials in parts by weight:

[0061] 100 parts lead powder, 0.6 parts barium sulfate, 0.4 parts humic acid, 0.3 parts zinc stannate, 0.12 parts carbon black, 0.12 parts composite fiber, and 1.5 parts doped porous carbon / lead powder.

[0062] The composite fiber is composed of carbon fiber and polyester fiber in a weight ratio of 5:1.

[0063] The preparation method of the doped porous carbon / lead powder is the same as that in Example 1.

[0064] This embodiment provides a method for preparing a doped porous carbon / lead composite anode material, including the following steps:

[0065] Lead powder, barium sulfate, humic acid, zinc stannate, carbon black, and composite fibers were added to a high-speed mixer and mixed for 20 minutes at 500 rpm. Then, doped porous carbon / lead powder was added and mixing continued for 7 minutes. Next, water and sulfuric acid with a density of 1.4 g / mL were added, and the mixture was stirred evenly in a paste mixer to obtain a doped porous carbon / lead composite anode material. The weight ratio of water to lead powder was 0.15:1, and the weight ratio of sulfuric acid to lead powder was 0.1:1.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 1 is that the preparation methods of the doped porous carbon / lead powder are different, as follows: The preparation method of the doped porous carbon / lead powder includes the following steps:

[0068] By weight, 30 parts of chitosan were added to 50 parts of 0.15M citric acid aqueous solution and soaked for 1 hour. After filtration and drying, the pretreated material was obtained. 10 parts of the pretreated material and 2 parts of thiourea were mixed and stirred evenly. The mixture was heated to 400℃ and calcined for 1.5 hours under a nitrogen atmosphere. Then, the temperature was raised to 850℃ and calcined for 3 hours. After cooling to room temperature, the mixture was ground into powder to obtain doped porous carbon.

[0069] 1.5 parts of doped porous carbon were added to 4.5 parts of 0.3M lead citrate aqueous solution and sonicated for 30 min at an ultrasonic frequency of 30 kHz and a power of 250 W. Then, 0.3 parts of 0.02M sodium borohydride aqueous solution were added and the mixture was heated to 42 °C under a nitrogen atmosphere for 1 h for reduction reaction. The mixture was then filtered, dried, and ground into powder to obtain doped porous carbon / lead powder.

[0070] Comparative Example 2

[0071] The difference between this comparative example and Example 1 is that the preparation methods of the doped porous carbon / lead powder are different, as follows: The preparation method of the doped porous carbon / lead powder includes the following steps:

[0072] By weight, 30 parts of chitosan were added to 50 parts of 0.15M citric acid aqueous solution and soaked for 1 hour. After filtration and drying, the pretreated material was obtained. 10 parts of the pretreated material and 4 parts of dicyandiamide were mixed and stirred evenly. The mixture was heated to 400℃ and calcined for 1.5 hours under a nitrogen atmosphere. Then, the temperature was raised to 850℃ and calcined for 3 hours. After cooling to room temperature, the mixture was ground into powder to obtain doped porous carbon.

[0073] 1.5 parts of doped porous carbon were added to 4.5 parts of 0.3M lead citrate aqueous solution and sonicated for 30 min at an ultrasonic frequency of 30 kHz and a power of 250 W. Then, 0.3 parts of 0.02M sodium borohydride aqueous solution were added and the mixture was heated to 42 °C under a nitrogen atmosphere for 1 h for reduction reaction. The mixture was then filtered, dried, and ground into powder to obtain doped porous carbon / lead powder.

[0074] Comparative Example 3

[0075] The difference between this comparative example and Example 1 is that the doped porous carbon / lead powder is replaced with doped porous carbon, specifically as follows: The preparation method of the doped porous carbon includes the following steps:

[0076] By weight, 30 parts of chitosan were added to 50 parts of 0.15M citric acid aqueous solution and soaked for 1 hour. After filtration and drying, the pretreated material was obtained. 10 parts of the pretreated material, 4 parts of dicyandiamide and 2 parts of thiourea were mixed and stirred evenly. The mixture was heated to 400℃ and calcined for 1.5 hours under a nitrogen atmosphere. Then, the temperature was raised to 850℃ and calcined for 3 hours. After cooling to room temperature, the mixture was ground into powder to obtain doped porous carbon.

[0077] Comparative Example 4

[0078] The difference between this comparative example and Example 1 is that barium sulfate was not added.

[0079] Comparative Example 5

[0080] The difference between this comparative example and Example 1 is that no humic acid was added.

[0081] Comparative Example 6

[0082] The difference between this comparative example and Example 1 is that zinc stannate was not added.

[0083] Comparative Example 7

[0084] The difference between this comparative example and Example 1 is that no carbon black was added.

[0085] Performance testing

[0086] The doped porous carbon / lead composite negative electrode materials prepared in Examples 1-3 and Comparative Examples 1-7 were coated onto a negative electrode plate (weighing 25g), with a coating amount of 26g / plate. The negative electrode plate was flattened, leached with sulfuric acid with a density of 1.3g / mL, cured, and dried to obtain a lead-carbon battery negative electrode plate. A lead-carbon battery cell was assembled in the following order: positive electrode plate, glass fiber, negative electrode plate, glass fiber, and positive electrode plate. The positive electrode plate was composed of lead powder, polyester fiber, red lead, and conductive agent colloidal graphite in a weight ratio of 85:15:0.3:0.8, with an injection density of 1.265g / cm³. 3Lead-carbon batteries were manufactured using sulfuric acid electrolyte and sealed in a battery casing, and their performance was tested. The cycle life test method for the lead-carbon batteries was as follows: a CT-4008-5V6A-S1 Xinwei battery charge-discharge tester was used to test the high-rate partial state-of-charge cycle life. Based on the battery's theoretical capacity, a 1C current was set as the cycle life test current, with each charge-discharge cycle lasting 1 minute. The cycle cutoff voltage of a single cell was 1.75V. Charge acceptance was tested according to the national standard GB / T23638-2009. The results are shown in Table 1.

[0087] Table 1: Performance test results of doped porous carbon / lead composite anode materials

[0088]

[0089] Comparing the results in Table 1 above, it can be seen that the doped porous carbon / lead composite anode materials prepared in Examples 1-3 exhibit excellent battery performance when applied to lead-carbon batteries, with significantly improved cycle life and charge acceptance. In particular, the doped porous carbon / lead composite anode material prepared in Example 3 demonstrates the best performance in all aspects. This is because the present invention optimizes the raw material formulation of the composite anode materials by adding specific doped porous carbon / lead powder and components such as barium sulfate, humic acid, zinc stannate, and carbon black, thereby significantly improving the battery performance, enhancing charge acceptance, and extending battery life. Compared to Examples 1-3, the doped porous carbon / lead powders prepared in Comparative Examples 1-3 were not prepared using a specific method, and Comparative Examples 4-7 did not add any of the following: barium sulfate, humic acid, zinc stannate, or carbon black. This results in inferior cycle life and charge acceptance for the composite anode materials prepared in Comparative Examples 4-7, demonstrating the necessity of the above-mentioned technical solutions employed in the present invention for achieving beneficial technical effects.

[0090] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A doped porous carbon / lead composite anode material, characterized in that, By weight, it includes the following ingredients: 95-100 parts lead powder, 0.4-0.6 parts barium sulfate, 0.2-0.4 parts humic acid, 0.1-0.3 parts zinc stannate, 0.08-0.12 parts carbon black, 0.08-0.12 parts composite fiber, and 1.0-1.5 parts doped porous carbon / lead powder.

2. The doped porous carbon / lead composite anode material according to claim 1, characterized in that, The method for preparing the doped porous carbon / lead powder includes the following steps: Chitosan was soaked in an aqueous citric acid solution, filtered, and dried to obtain a pretreated material. The pretreated material, dicyandiamide, and thiourea were mixed and stirred evenly, heated and calcined under a nitrogen atmosphere, cooled, and ground into powder to obtain doped porous carbon. Doped porous carbon was added to an aqueous solution of lead citrate, sonicated, and then an aqueous solution of sodium borohydride was added. The mixture was then heated under a nitrogen atmosphere to carry out a reduction reaction, filtered, dried, and ground into powder to obtain doped porous carbon / lead powder.

3. The doped porous carbon / lead composite anode material according to claim 2, characterized in that, The weight ratio of chitosan to citric acid aqueous solution is 20-40:40-60.

4. The doped porous carbon / lead composite anode material according to claim 2, characterized in that, The weight ratio of the pretreated material, dicyandiamide, and thiourea is 5-15:2-8:1-3.

5. The doped porous carbon / lead composite anode material according to claim 2, characterized in that, The weight ratio of the doped porous carbon, lead citrate aqueous solution, and sodium borohydride aqueous solution is 1-2:3-6:0.2-0.

5.

6. The doped porous carbon / lead composite anode material according to claim 2, characterized in that, The concentration of the citric acid aqueous solution is 0.1-0.3M; the concentration of the lead citrate aqueous solution is 0.2-0.4M; and the concentration of the sodium borohydride aqueous solution is 0.01-0.03M.

7. The doped porous carbon / lead composite anode material according to claim 2, characterized in that, The heating and calcination conditions are as follows: heat to 350-500℃ and hold for calcination for 1-2 hours, then raise the temperature to 800-900℃ and hold for calcination for 2-4 hours; the frequency of the ultrasound is 20-40kHz and the power is 100-300W.

8. The doped porous carbon / lead composite anode material according to claim 1, characterized in that, The composite fiber is composed of carbon fiber and polyester fiber.

9. The method for preparing the doped porous carbon / lead composite anode material according to any one of claims 1-8, characterized in that, Includes the following steps: Lead powder, barium sulfate, humic acid, zinc stannate, carbon black, and composite fibers are added to a high-speed mixer and mixed. Then, doped porous carbon / lead powder is added and mixed again. Water and sulfuric acid are then added and stirred evenly in a paste mixer to obtain a doped porous carbon / lead composite anode material.

10. The method for preparing the doped porous carbon / lead composite anode material according to claim 9, characterized in that, The weight ratio of water to lead powder is 0.1-0.15:1; the weight ratio of sulfuric acid to lead powder is 0.06-0.1:1.

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