Lead-acid storage battery positive electrode lead paste additive and preparation method thereof

Abstract

The invention provides a lead-acid storage battery positive electrode lead paste additive and a preparation method thereof, and relates to the technical field of lead-acid storage batteries. The lead-acid storage battery positive electrode lead paste additive comprises the following components in parts by mass: 5-15 parts of nitrogen-doped graphene, 2-10 parts of polyaniline nanotubes, 1-3 parts of conductive ceramic, 2-6 parts of fumed silica powder, 1-4 parts of antimony trioxide and 0.05-0.5 part of carbon fibers. The lead-acid storage battery positive electrode lead paste additive can significantly improve the utilization rate of active substances of an electrode material, enhance the stability of an electrode structure, effectively inhibit capacity fading, and meet the requirements of high power output and long cycle life.

Description

Technical Field

[0001] The present invention relates to the technical field of lead - acid batteries, and particularly to a positive - lead - paste additive for lead - acid batteries and a preparation method thereof. Background Art

[0002] Due to its advantages such as low cost, mature technology, and high reliability, lead - acid batteries play an important role in fields such as automotive starting power sources, energy storage systems, and industrial backup power sources. However, with the rapid development of the new - energy industry, traditional lead - acid batteries are facing the contradiction between high - power output requirements and limited cycle life. As the core component of lead - acid batteries, the performance of the positive - lead paste directly determines the capacity, rate performance, and service life of the battery. The positive - active material (mainly lead dioxide, PbO 2 ) is prone to irreversible phase transformation and shedding during charge - discharge processes, resulting in low utilization rate of the active material (usually less than 50%) and capacity attenuation, which is particularly prominent in high - rate charge - discharge scenarios.

[0003] Currently, the industry generally improves the electrode performance by adding functional additives such as conductive agents and structure - enhancing agents to the positive - lead paste. Although these methods can improve the conductivity and mechanical stability of the battery to a certain extent, and thus improve the overall performance of the battery, they often cannot fundamentally solve the problems of low utilization rate of the active material and rapid capacity attenuation. Especially under high - rate charge - discharge conditions, traditional additives are difficult to effectively prevent the irreversible phase transformation and shedding of the positive - active material during repeated charge - discharge processes, which not only limits the full utilization of the active material but also accelerates the capacity attenuation of the battery.

[0004] Therefore, there is an urgent need to develop a new positive - lead - paste additive for lead - acid batteries to improve the charge - discharge cycle performance of the battery and extend its service life. Summary of the Invention

[0005] In view of this, the present invention provides a positive - lead - paste additive for lead - acid batteries and a preparation method thereof. This additive not only enhances the stability of the electrode structure but also optimizes the conductive network of the battery, thereby extending the cycle life of the battery while ensuring high - power output.

[0006] In a first aspect, the present invention provides a positive - lead - paste additive for lead - acid batteries, which includes the following components by mass fraction: 5 - 15 parts of nitrogen - doped graphene, 2 - 10 parts of polyaniline nanotubes, 1 - 3 parts of conductive ceramics, 2 - 6 parts of fumed silica powder, 1 - 4 parts of antimony trioxide, and 0.05 - 0.5 parts of carbon fiber.

[0007] In one or some possible embodiments, the doping amount of the nitrogen - doped graphene is 2 - 9%, and the specific surface area is 400 - 600 m 2 / g.

[0008] By adopting the above technical solution, not only the conductivity of the electrode is enhanced, but also a large number of active sites are provided, improving the efficiency of the electrochemical reaction.

[0009] In one or some possible embodiments, the diameter of the polyaniline nanotubes is 30-70 nm, and the length is 2-8 μm.

[0010] By adopting the above technical solution, an efficient three-dimensional conductive network can be constructed, further enhancing the electron transport ability and improving the mechanical strength of the electrode material.

[0011] In one or some possible embodiments, the particle size of the fumed silica powder is 0.2-20 μm.

[0012] In one or some possible embodiments, the particle size of the conductive ceramic is 50-500 nm; the conductive ceramic is zirconia and / or silicon carbide.

[0013] By adopting the above technical solution, it helps to form a uniform conduction path and reduce the resistance loss.

[0014] In one or some possible embodiments, the aspect ratio of the carbon fiber is 100-200:1, and the conductivity is 100-500 S / cm.

[0015] By adopting the above technical solution, the mechanical strength and conductivity of the electrode are significantly improved, and the shedding of the active material during the charge and discharge process is reduced.

[0016] In a second aspect, the present invention relates to a method for preparing the positive lead paste additive of the above lead-acid battery, comprising the following steps: S1. Prepare each component according to the said mass fraction, prepare the nitrogen-doped graphene dispersion liquid and the polyaniline nanotube dispersion liquid, and pickle the conductive ceramic at the same time; S2. After stirring and mixing the nitrogen-doped graphene dispersion liquid and the polyaniline nanotube dispersion liquid prepared in step S1, sequentially add the pickled conductive ceramic, fumed silica powder, antimony trioxide, carbon fiber and a dispersant accounting for 0.3-1% of the total mass of the mixture, and shear and disperse under the protection of inert gas to obtain a slurry; S3. Add an adhesive accounting for 2-5% of the mass of the slurry to the slurry in step S2, stir, dry, grind and sieve to obtain the positive lead paste additive.

[0017] In one or some possible embodiments, in step S1, the acid solution is selected as a nitric acid solution with a concentration of 5-10%.

[0018] In one or some possible embodiments, in step S2, the rotation speed for shearing and dispersing is 1000 - 2000 rpm, and the time is 40 - 60 min.

[0019] In one or some possible embodiments, in step S3, the particle size D50 of the positive electrode lead paste additive does not exceed 50 μm.

[0020] The positive electrode lead paste additive for lead - acid batteries and its preparation method provided by the present invention have the following beneficial effects compared with the prior art: (1) The positive electrode lead paste additive of the present invention constructs an efficient three - dimensional conductive network and a strong structural framework, making the electron transfer more efficient. At the same time, it improves the ability of the electrode to resist expansion and contraction, thus significantly extending the cycle life of the battery and enhancing its high - rate charge - discharge performance. In addition, this additive also improves the safety of the battery and reduces the risk of thermal runaway, providing a solid foundation for realizing high - performance, long - life, safe and reliable lead - acid batteries.

[0021] (2) The positive electrode lead paste additive of the present invention can significantly improve the utilization rate of the active material of the electrode material, enhance the structural stability of the electrode, effectively inhibit capacity decay, and meet the requirements of high - power output and long cycle life.

[0022] (3) The method for preparing the positive electrode lead paste additive of the present invention not only ensures the excellent dispersion and uniform distribution of each component, but also effectively optimizes the stability and consistency of the slurry. In addition, the preparation method of the present invention significantly improves the compatibility between the additive and the lead paste matrix, thereby enhancing the overall performance and service life of the battery, having certain economic benefits, and providing a feasible technical path for the large - scale production and application of high - performance lead - acid batteries. Detailed embodiments

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] Traditional lead - acid batteries have certain limitations in performance, especially in terms of energy density, charge - discharge efficiency, cycle life, etc., and it is difficult to meet the growing demands. The positive electrode lead paste is an important part of lead - acid batteries, and its performance directly affects the overall performance of the battery. As a key component in the positive electrode lead paste, the additive plays a crucial role in improving the battery performance.

[0025] Therefore, the inventor has proposed a positive lead paste additive for lead-acid batteries, which includes the following components by mass fraction: 5-15 parts of nitrogen-doped graphene, 2-10 parts of polyaniline nanotubes, 1-3 parts of conductive ceramics, 2-6 parts of fumed silica powder, 1-4 parts of antimony trioxide, and 0.05-0.5 parts of carbon fiber. The preparation method of the additive includes the following steps: S1. Prepare each component according to the above mass fraction, prepare a nitrogen-doped graphene dispersion and a polyaniline nanotube dispersion, and pickle the conductive ceramics at the same time; S2. After stirring and mixing the nitrogen-doped graphene dispersion and the polyaniline nanotube dispersion prepared in step S1, sequentially add the pickled conductive ceramics, fumed silica powder, antimony trioxide, carbon fiber, and a dispersant accounting for 0.3-1% of the total mass of the mixture, and shear and disperse under the protection of inert gas to obtain a slurry; S3. Add an adhesive accounting for 2-5% of the mass of the slurry in step S2, stir, dry, grind and sieve to obtain the positive lead paste additive.

[0026] The following further describes the present invention in conjunction with specific embodiments. The protection scope of the present invention is not limited by the following embodiments. Unless otherwise specified, the main materials involved in the following examples are all conventional commercially available products.

[0027] In the embodiment of the present invention, the preparation method of nitrogen-doped graphene includes the following steps: Under the condition of an ice-water bath, add 4 g of graphite powder and 1 g of sodium nitrate to 150 ml of concentrated sulfuric acid with a concentration of 98%, and slowly add 9 g of potassium permanganate while stirring vigorously. After the addition of potassium permanganate is completed, keep the mixture at room temperature for at least 6 h; then sequentially add 300 ml of distilled water and 500 ml of hydrogen peroxide with a concentration of 3 wt% to the above mixture to obtain a bright yellow suspension; then add 300 ml of hydrochloric acid with a concentration of 4 wt% dropwise to the suspension, pour out the supernatant after standing and sedimentation, and repeat this step at least 4 times; finally, add 2 L of distilled water, pour out the supernatant after standing and sedimentation, repeat 3 times and then centrifuge, dialyze and purify, and dry to obtain graphene oxide; Ultrasonically disperse 0.03 g of graphene oxide in 20 ml of deionized water to obtain a graphene oxide aqueous dispersion with a concentration of 1.5 mg / ml; Mix and dissolve the graphene oxide aqueous dispersion with a concentration of 1.5 mg / ml and solid urea, wherein the mass ratio of the graphene oxide aqueous dispersion to urea is 0.1-1:1, hydrothermal at 150-200 °C for 5-20 h, naturally cool to room temperature, dialyze, and freeze-dry to obtain nitrogen-doped graphene with a nitrogen doping amount of 2-9% and a specific surface area of 400-600 m 2 / g.

[0028] Exemplarily, Preparation Examples 1 to 4 respectively provide a nitrogen-doped graphene, and Preparation Example 5 provides a polyaniline nanotube.

[0029] Preparation Example 1 This preparation example provides a method for preparing nitrogen-doped graphene, including the following steps: Mix and dissolve the graphene oxide aqueous dispersion with a concentration of 1.5 mg / ml and solid urea, wherein the mass ratio of the graphene oxide aqueous dispersion to urea is 0.3:1, hydrothermally react at 180 °C for 6 h, naturally cool to room temperature, dialyze, and freeze-dry to obtain nitrogen-doped graphene with a nitrogen doping amount of 5% and a specific surface area of 400 - 600 m 2 / g.

[0030] Preparation Example 2 This preparation example provides a method for preparing nitrogen-doped graphene, including the following steps: Mix and dissolve the graphene oxide aqueous dispersion with a concentration of 1.5 mg / ml and solid urea, wherein the mass ratio of the graphene oxide aqueous dispersion to urea is 0.1:1, hydrothermally react at 180 °C for 6 h, naturally cool to room temperature, dialyze, and freeze-dry to obtain nitrogen-doped graphene with a nitrogen doping amount of 9% and a specific surface area of 400 - 600 m 2 / g.

[0031] Preparation Example 3 This preparation example provides a method for preparing nitrogen-doped graphene, including the following steps:

[0032] Mix and dissolve the graphene oxide aqueous dispersion with a concentration of 1.5 mg / ml and solid urea, wherein the mass ratio of the graphene oxide aqueous dispersion to urea is 0.3:1, hydrothermally react at 180 °C for 6 h, naturally cool to room temperature, dialyze, and freeze-dry to obtain nitrogen-doped graphene with a nitrogen doping amount of 5% and a specific surface area of 400 - 600 m 2 / g.

[0033] Preparation Example 4 This preparation example provides a method for preparing nitrogen-doped graphene, including the following steps: Mix and dissolve the graphene oxide aqueous dispersion with a concentration of 1.5 mg / ml and solid urea, wherein the mass ratio of the graphene oxide aqueous dispersion to urea is 0.3:1, hydrothermally react at 150 °C for 20 h, naturally cool to room temperature, dialyze, and freeze-dry to obtain nitrogen-doped graphene with a nitrogen doping amount of 5.5% and a specific surface area of 400 - 600 m 2 / g.

[0034] Preparation Example 5 The method for preparing polyaniline nanotubes includes the following steps: 0.465 g of aniline was slowly added dropwise to 40 ml of carbon tetrachloride, and ultrasonic dispersion was carried out for 30 min to obtain an organic phase; 1.1 g of ammonium persulfate (APS) was dissolved in 320 ml of distilled water, and magnetic stirring was carried out to prepare an aqueous phase; the aqueous phase was slowly added to the organic phase, and after standing for 24 h to separate layers, an appropriate amount of acetone was added, stirred for 10 min, filtered to obtain a filter cake, the filter cake was washed with acetone, and then washed with absolute ethanol and deionized water until there was no foam, and finally dried at 60 °C for 48 h to obtain polyaniline nanotubes with a diameter of 50 ± 20 nm and a length of 5 ± 3 μm.

[0035] Exemplarily, taking the nitrogen-doped graphene of Preparation Example 4 and the polyaniline nanotubes of Preparation Example 5 as examples, the preparation of the positive lead paste additive for lead-acid batteries was carried out, and the following examples were designed.

[0036] Example 1 This example provides a positive lead paste additive for lead-acid batteries, including 50 g of nitrogen-doped graphene, 20 g of polyaniline nanotubes, 10 g of silicon carbide, 20 g of fumed silica powder, 10 g of antimony trioxide, and 0.5 g of carbon fiber.

[0037] The preparation of the positive lead paste additive for lead-acid batteries in this example includes the following steps: S1. 50 g of nitrogen-doped graphene was dispersed in an appropriate amount of deionized water, and 1% of sodium dodecylbenzenesulfonate based on the mass of nitrogen-doped graphene was added to obtain a nitrogen-doped graphene dispersion; 10 g of polyaniline nanotubes was dispersed in an appropriate amount of deionized water, and 1% of sodium dodecylbenzenesulfonate based on the mass of the mixture was added to obtain a polyaniline nanotube dispersion; 20 min of ultrasonic cleaning of silicon carbide was carried out with a 5% nitric acid solution, and it was dried for standby. S2. The nitrogen-doped graphene dispersion and the polyaniline nanotube dispersion in step S1 were mixed, stirred at a speed of 300 rpm for 15 min, and then silicon carbide, fumed silica powder, antimony trioxide, carbon fiber, and 0.3% of polyvinylpyrrolidone (PVP) based on the total mass of the mixture were added in sequence, and shear dispersion was carried out at a speed of 1000 rpm for 40 min under nitrogen protection to obtain a slurry. S3. 2% of polytetrafluoroethylene emulsion based on the mass of the slurry was added to the slurry in step S2, stirred at a speed of 80 rpm for 30 min, dried at 200 °C, ground, and passed through a 200-400 mesh sieve to obtain a positive lead paste additive with D50 ≤ 50 μm.

[0038] Comparative Example 1 The difference from Example 1 is that: it does not contain nitrogen-doped graphene, and the preparation steps are adjusted accordingly, and the other conditions are the same as those in Example 1.

[0039] Comparative Example 2 The difference from Example 1 is that it does not contain polyaniline nanotubes, and the preparation steps are adjusted accordingly, with the remaining conditions being the same as in Example 1.

[0040] Example 2 The difference from Example 1 is that this example provides a positive lead paste additive for a lead-acid battery, including 80 g of nitrogen-doped graphene, 80 g of polyaniline nanotubes, 10 g of silicon carbide, 20 g of fumed silica powder, 10 g of antimony trioxide, and 0.5 g of carbon fiber. The preparation steps are the same as in Example 1.

[0041] Example 3 The difference from Example 1 is that this example provides a positive lead paste additive for a lead-acid battery, including 100 g of nitrogen-doped graphene, 60 g of polyaniline nanotubes, 10 g of silicon carbide, 20 g of fumed silica powder, 10 g of antimony trioxide, and 0.5 g of carbon fiber. The preparation steps are the same as in Example 1.

[0042] Example 4 The difference from Example 1 is that this example provides a positive lead paste additive for a lead-acid battery, including 80 g of nitrogen-doped graphene, 40 g of polyaniline nanotubes, 10 g of silicon carbide, 20 g of fumed silica powder, 10 g of antimony trioxide, and 0.5 g of carbon fiber. The preparation steps are the same as in Example 1.

[0043] Example 5 The difference from Example 1 is that this example provides a positive lead paste additive for a lead-acid battery, including 150 g of nitrogen-doped graphene, 100 g of polyaniline nanotubes, 10 g of silicon carbide, 20 g of fumed silica powder, 10 g of antimony trioxide, and 0.5 g of carbon fiber. The preparation steps are the same as in Example 1.

[0044] Example 6 The difference from Example 1 is that this example provides a positive lead paste additive for a lead-acid battery, including 70 g of nitrogen-doped graphene, 50 g of polyaniline nanotubes, 10 g of silicon carbide, 20 g of fumed silica powder, 10 g of antimony trioxide, and 0.5 g of carbon fiber. The preparation steps are the same as in Example 1.

[0045] Example 7 This example provides a positive lead paste additive for a lead-acid battery, including 120 g of nitrogen-doped graphene, 80 g of polyaniline nanotubes, 30 g of zirconia, 60 g of fumed silica powder, 40 g of antimony trioxide, and 5 g of carbon fiber.

[0046] The preparation of the positive lead paste additive for the lead-acid battery in this example includes the following steps: S1. Disperse 120 g of nitrogen-doped graphene in an appropriate amount of deionized water, add sodium dodecylbenzenesulfonate accounting for 1% of the mass of nitrogen-doped graphene to obtain a nitrogen-doped graphene dispersion; disperse 80 g of polyaniline nanotubes in an appropriate amount of deionized water, add sodium dodecylbenzenesulfonate accounting for 1% of the mass of the mixture to obtain a polyaniline nanotube dispersion; ultrasonically clean silicon carbide with a 10% nitric acid solution for 20 min and dry it for standby; S2. Mix the nitrogen-doped graphene dispersion and the polyaniline nanotube dispersion obtained in step S1, stir at a speed of 300 rpm for 15 min, then sequentially add zirconia, fumed silica powder, antimony trioxide, carbon fiber and polyvinylpyrrolidone (PVP) accounting for 1% of the total mass of the mixture, and shear and disperse at a speed of 2000 rpm for 60 min under nitrogen protection to obtain a slurry; S3. Add polytetrafluoroethylene emulsion accounting for 5% of the mass of the slurry obtained in step S2, stir at a speed of 80 rpm for 30 min, then dry at 200 °C, grind, and pass through a 200 - 400 mesh sieve to obtain a positive lead paste additive with D50 ≤ 50 μm.

[0047] Comparative Example 3 The difference from Example 7 is that in step S1, when preparing the nitrogen-doped graphene dispersion and the polyaniline nanotube dispersion, sodium dodecylbenzenesulfonate is not added; the remaining steps remain unchanged.

[0048] Example 8 This example provides a positive lead paste additive for lead-acid batteries, including 120 g of nitrogen-doped graphene, 80 g of polyaniline nanotubes, 15 g of zirconia, 15 g of silicon carbide, 60 g of fumed silica powder, 40 g of antimony trioxide and 5 g of carbon fiber.

[0049] The preparation of the positive lead paste additive for lead-acid batteries in this example includes the following steps: S1. Disperse 120 g of nitrogen-doped graphene in an appropriate amount of deionized water, add sodium dodecylbenzenesulfonate accounting for 1% of the mass of nitrogen-doped graphene to obtain a nitrogen-doped graphene dispersion; disperse 80 g of polyaniline nanotubes in an appropriate amount of deionized water, add sodium dodecylbenzenesulfonate accounting for 1% of the mass of the mixture to obtain a polyaniline nanotube dispersion; ultrasonically clean silicon carbide with a 10% nitric acid solution for 20 min and dry it for standby; S2. Mix the nitrogen-doped graphene dispersion and the polyaniline nanotube dispersion obtained in step S1, stir at a speed of 300 rpm for 15 min, then sequentially add zirconia, silicon carbide, fumed silica powder, antimony trioxide, carbon fiber and polyvinylpyrrolidone (PVP) accounting for 1% of the total mass of the mixture, and shear and disperse at a speed of 1500 rpm for 60 min under nitrogen protection to obtain a slurry; S3. Add polytetrafluoroethylene emulsion accounting for 5% of the mass of the slurry in step S2, stir for 30 min at a speed of 80 rpm, then dry at 200 °C, grind, and sieve through a 200-400 mesh sieve to obtain a positive electrode lead paste additive with D50 ≤ 50 μm.

[0050] Use the positive electrode lead paste additives prepared in the above Examples 1-8 and Comparative Examples 1-3 for the preparation of the positive electrode lead paste of lead-acid batteries. Among them, the mass of the positive electrode lead paste additive accounts for 0.8% of the total mass of the positive electrode lead paste. Then configure lead-acid batteries according to the obtained positive electrode lead pastes of each group. The performance tests include the following four aspects: (1) Conductivity Make the positive electrode material into a thin sheet and measure its conductivity using a conductivity tester. The conductivity tester calculates the conductivity by applying a constant voltage and measuring the current passing through the material.

[0051] (2) Battery cycle life Perform continuous charge and discharge cycles on the battery under standard charge and discharge conditions until the battery capacity drops below 80% of the initial capacity, and record the number of cycles as the battery cycle life.

[0052] (3) Rated capacity Under standard charge and discharge conditions, fully charge the battery and then discharge it to the cut-off voltage, and record the total amount of electricity released during the discharge process as the rated capacity of the battery.

[0053] (4) High-rate charge and discharge performance test At 25 °C, use an Arbin BT2000 tester. First, charge and discharge at a rate of 0.2C, record the initial capacity, then increase the charge and discharge rate to 2C, record the discharge capacity each time, and calculate the capacity retention rate as shown in formula (Ⅰ): Capacity retention rate = initial capacity / high-rate discharge capacity × 100%.

[0054] Record the above test results in Table 1 below.

[0055] Table 1 Performance test results

[0056] It can be seen from the performance test results in Table 1 that the lead-acid batteries configured in the present invention have higher conductivity, battery cycle life, rated capacity, and capacity retention rate.

[0057] Through Example 1 and Comparative Examples 1-2 and in combination with the performance test results of Table 1, it can be seen that nitrogen-doped graphene and polyaniline nanotubes have a significant synergistic effect in the positive lead paste additive of lead-acid batteries. This is because: nitrogen-doped graphene, with its excellent electrical conductivity and mechanical strength, constructs an efficient electronic conduction network and provides structural stability, which is crucial for maintaining the integrity of the electrode during the charge and discharge process. And polyaniline nanotubes, due to their good electrochemical activity and high specific surface area, increase the number of reactive sites, promote charge transfer efficiency, and contribute to the effective migration of ions in the electrolyte, thereby improving the performance of the electrode / electrolyte interface. When the two are used together, the two-dimensional sheet structure of nitrogen-doped graphene and the one-dimensional tubular structure of polyaniline nanotubes form an interpenetrating conductive network, providing a fast channel for electrons, while the presence of polyaniline nanotubes enhances the electrochemical activity of the material, and the two work together to improve the conductivity and reaction efficiency of the entire electrode. In addition, this combination can also be more effectively dispersed in the lead paste to form a uniformly distributed composite material system, reduce local overheating or uneven current density, and further improve the overall performance of the battery.

[0058] Through Examples 1 to 6 and the performance test results in Table 1, it can be seen that when the mass ratio of nitrogen-doped graphene to polyaniline nanotubes in the positive electrode lead paste additive is further limited to 1.5 to 2:1, the performance of the lead-acid battery is optimal. This is because: when the mass ratio of nitrogen-doped graphene to polyaniline nanotubes is controlled at 1.5 to 2:1, the two materials can form an ideal three-dimensional network structure. On the one hand, the appropriate amount of nitrogen-doped graphene ensures sufficient conductive pathways and structural support; on the other hand, the appropriate amount of polyaniline nanotubes provides sufficient active surface and effective ion transmission channels. This combination not only optimizes the transmission path of electrons and ions, reduces energy loss, but also enhances the overall stability and durability of the electrode.

[0059] It can be seen from Example 7 and Comparative Example 3 that in Comparative Example 3, sodium dodecylbenzene sulfonate is not used to pre-disperse nitrogen-doped graphene and polyaniline nanotubes, and nitrogen-doped graphene and polyaniline nanotubes may produce a phenomenon of material aggregation in local areas. This aggregation will form an obstacle to the transmission of electrons and ions, increase the internal resistance of the electrode, and may affect the stability and uniformity of the entire electrode structure. In Example 7, sodium dodecylbenzene sulfonate is used for pre-dispersion, which makes full use of the proton acid doping characteristics of polyaniline nanotubes and the nitrogen defect sites of nitrogen-doped graphene, improves the interface electron transmission efficiency, promotes the rapid migration of electrons on the electrode surface, and thus improves the high-rate discharge performance of the battery. It can be explained that the rational use of sodium dodecylbenzene sulfonate for pre-dispersion not only helps to improve the efficiency of a single material, but also promotes the synergy between different materials, thereby significantly enhancing the overall performance of the lead-acid battery.

[0060] The inventors further found that the dosage of the positive electrode lead paste additive also has a certain impact on the performance of lead-acid batteries. Taking the lead-acid battery prepared in Example 5 as an example, the following examples were designed and the following performance test results were obtained. All relevant data are recorded in Table 2 below.

[0061] Table 2 Dosage of positive electrode lead paste additive and performance test results

[0062] As can be seen from Table 2: when the dosage of the positive electrode lead paste additive is between 0.8% and 1.2%, the battery exhibits the best performance. Excessive doping will cause a slight decrease in the battery cycle life and capacity retention rate. This may be because the excessive additive leads to an overly complex or tight electrode structure, affecting the ion migration efficiency. When the dosage of the positive electrode lead paste additive is too low, it will cause a significant decrease in battery performance. It can thus be shown that: an appropriate amount of additive helps to construct an efficient conductive network, improve the electron transfer efficiency, thereby extending the battery cycle life and enhancing the capacity retention rate; in addition, it can optimize the microstructure of the electrode material, reduce the internal resistance, promote the ion migration in the electrolyte, and thus enhance the overall performance of the battery.

[0063] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A lead paste additive for positive electrode of lead-acid battery, characterized in that: The composition comprises the following components by weight: 5-15 parts of nitrogen-doped graphene, 2-10 parts of polyaniline nanotubes, 1-3 parts of conductive ceramics, 2-6 parts of fumed silica powder, 1-4 parts of antimony trioxide and 0.05-0.5 parts of carbon fiber.

2. The lead-acid battery positive electrode lead paste additive according to claim 1, characterized in that: The doping amount of the nitrogen-doped graphene is 2-9%, and the specific surface area is 400-600m 2 / g.

3. The lead paste additive for lead-acid battery positive electrode according to claim 1, characterized in that: The polyaniline nanotube has a diameter of 30-70 nm and a length of 2-8 μm.

4. The positive electrode lead paste additive for lead-acid batteries according to claim 1, characterized in that: The particle size of the fumed silica powder is 0.2-20 μm.

5. The positive electrode lead paste additive for lead-acid batteries according to claim 1, characterized in that: The particle size of the conductive ceramic is 50-500 nm; the conductive ceramic is zirconium oxide and / or silicon carbide.

6. The positive electrode lead paste additive for lead-acid batteries according to claim 1, characterized in that: The aspect ratio of the carbon fiber is 100-200:1, and the conductivity is 100-500 S / cm.

7. A method for preparing the positive lead paste additive for lead-acid batteries according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, preparing each component according to the mass fraction, preparing a nitrogen-doped graphene dispersion and a polyaniline nanotube dispersion, and pickling the conductive ceramic at the same time; S2, stirring and mixing the nitrogen-doped graphene dispersion and the polyaniline nanotube dispersion prepared in step S1, sequentially adding the acid-washed conductive ceramic, fumed silica powder, antimony trioxide and carbon fiber, and shearing and dispersing under inert gas protection to obtain a slurry; S3. Add a binder to the slurry of step S2, stir, dry, grind and sieve to obtain a positive electrode lead paste additive.

8. The method for preparing the positive lead paste additive for lead-acid batteries according to claim 7, characterized in that: In step S1, the acid solution is a nitric acid solution with a concentration of 5-10%.

9. The method for preparing the positive electrode lead paste additive for lead-acid batteries according to claim 7, characterized in that: In step S2, the shear dispersion is performed at a rotation speed of 1000-2000 rpm and for a time of 40-60 min.

10. The positive electrode lead paste additive for lead-acid batteries according to claim 7, characterized in that: In step S3, the particle size D50 of the positive electrode lead paste additive does not exceed 50 μm.

Images