Lead acid battery negative lead paste, method of manufacture and negative electrode
The hybrid expander constructed by modifying lignin and core-shell ceramic microspheres solves the problems of dissolution and compatibility of expanders in lead-acid battery negative electrodes, improves the structural stability and electrochemical activity of the negative electrode, and extends battery life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIESHOU HUAYU POWER SUPPLY
- Filing Date
- 2026-04-30
- Publication Date
- 2026-07-24
Smart Images
Figure SMS_3
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery technology, and in particular to a lead paste for the negative electrode of a lead-acid battery, its preparation method, and the negative electrode itself. Background Technology
[0002] Lead-acid batteries are widely used in energy storage, transportation, and industrial fields due to their low cost, good high-current discharge performance, and high reliability. The negative electrode lead paste, as a crucial component, directly determines the battery's electrochemical performance and cycle life. Expanding agents are key additives in negative electrode lead paste. Sodium lignin sulfonate-based organic expanders have become the mainstream choice due to their excellent expansion effect. However, during battery formation and high-temperature cycling, they are prone to dissolution and degradation due to changes in electrolyte pH and increased temperature, leading to the failure of the expansion effect, shrinkage of the negative electrode active material, and a decrease in battery capacity and cycle life. Current technologies for modifying lignin mostly involve physical functionalization or simple alkyl bridging, and the dissolution problem remains unresolved. Inorganic expanders, such as hollow ceramic microspheres, are resistant to high temperatures and degradation, and can improve the porosity of the negative electrode. However, pure inorganic microspheres have poor compatibility with the organic phase of lead paste, easily leading to interfacial separation and failing to exert an effective expansion effect.
[0003] Therefore, there is an urgent need to develop a new type of hybrid expander to overcome the shortcomings of organic and inorganic expanders and achieve a comprehensive improvement in the performance of lead paste. Summary of the Invention
[0004] The purpose of this invention is to provide a lead paste for the negative electrode of lead-acid batteries, in order to solve the technical problems in the prior art where organic expanding agents used for the negative electrode of lead-acid batteries are easily dissolved and degraded, and inorganic expanding agents have poor compatibility with the lead paste matrix, which cannot exert a stable expanding effect for a long time, thus leading to shrinkage of the active material of the negative electrode, severe sulfation, rapid capacity decay, short cycle life, and poor high and low temperature performance.
[0005] The present invention also aims to provide a preparation method that features controllable process steps, simple operation, and requires no special equipment. This method ensures uniform dispersion of the hybrid expanding agent in the lead paste system, fully leveraging the synergistic effect of each component. The present invention also aims to provide a negative electrode made of negative electrode lead paste, which has excellent structural stability, electrochemical activity and cycle durability, and can significantly improve the overall performance and service life of lead-acid batteries.
[0006] In a first aspect, the present invention discloses a lead paste for the negative electrode of a lead-acid battery, comprising the following components by weight: 1000 parts lead powder, 80-100 parts sulfuric acid, 100-120 parts water, 0.5-1 part short fiber, 2-3 parts acetylene black, 10-12 parts barium sulfate, and 0.3-1 part hybrid expansion agent; The hybrid expansion agent includes modified lignin and core-shell ceramic microspheres in a mass ratio of 1:(0.3-1).
[0007] By employing the above technical solutions, this invention modifies traditional sodium lignin sulfonate by adding a hybrid expanding agent. For example, it performs maleic anhydride-acrylamide binary graft copolymerization modification, covalently grafting acid-resistant maleic anhydride segments and acrylamide segments containing strongly polar amide and carboxyl groups onto the lignin macromolecule. These functional groups not only significantly enhance the chemical stability of lignin in sulfuric acid electrolyte, effectively inhibiting its dissolution and degradation during battery cycling and ensuring the long-term effectiveness of the expanding agent, but also introduce abundant hydrophilic groups and groups that may interact with lead ions, thereby constructing a more stable and uniformly distributed network structure in the negative electrode active material, maintaining the porosity and reactivity of the negative electrode. On the other hand, the core-shell ceramic microspheres in the hybrid expanding agent use hollow ceramic microspheres with a specific silicon-aluminum ratio as rigid cores. These microspheres themselves have excellent high-temperature resistance and degradation resistance, and can play a supporting role in the negative electrode framework, preventing the shrinkage of the active material and providing a stable ion transport channel for electrochemical reactions. Furthermore, coating the surface with polyvinylidene fluoride-hexafluoropropylene copolymer and further grafting sulfonic acid groups creates an organic shell that significantly improves the interfacial compatibility between the ceramic microspheres and other organic components in the lead paste, as well as the lead powder, preventing phase separation. In addition, the sulfonic acid groups grafted onto the shell possess excellent hydrophilicity and ion exchange capacity, enabling them to conduct protons. This is equivalent to endowing the originally inert inorganic microspheres with electrochemical activity, allowing them to participate in the ion conduction network of the negative electrode, rather than merely serving as an inert filler.
[0008] Modified lignin and core-shell ceramic microspheres synergistically enhance the structural durability, interfacial stability, and electrochemical activity of negative electrode lead paste. Specifically, the network structure constructed by modified lignin provides an ideal dispersion carrier for the core-shell ceramic microspheres, while the rigid framework of the core-shell ceramic microspheres provides stable physical support for the lignin network structure. The organic shell layer on the surface of the ceramic microspheres solves the problem of poor compatibility between inorganic microspheres and organic expanding agents. Modified lignin can be tightly adsorbed and wrapped around the surface of ceramic microspheres with a vinylidene fluoride-hexafluoropropylene copolymer shell, forming a tightly bonded composite material that ensures the continuity of stress transmission and structural integrity. In addition, the carboxyl / amide groups provided by modified lignin and the sulfonic acid groups provided by the core-shell microspheres together constitute a highly efficient three-dimensional proton conduction network.
[0009] Preferably, the modified lignin is prepared by binary graft copolymerization of sodium lignin sulfonate and maleic anhydride-acrylamide.
[0010] Preferably, the core-shell type ceramic microspheres include hollow ceramic microspheres, with the shell being a copolymer of polyvinylidene fluoride and hexafluoropropylene and the shell being grafted with sulfonic acid groups.
[0011] Preferably, the hollow ceramic microspheres comprise 55%–60% silicon dioxide and 35%–40% aluminum oxide.
[0012] Preferably, the raw materials for modified lignin include sodium lignin sulfonate, maleic anhydride, acrylamide, N,N'-methylenebisacrylamide, and an initiator in a mass ratio of 1:(8-12):(6-10):(0.02-0.06):(0.1-0.3).
[0013] Preferably, the initiator includes potassium persulfate or ammonium persulfate.
[0014] Preferably, the raw materials for the core-shell ceramic microspheres include hollow ceramic microspheres in a mass ratio of 1:(0.03-0.1):(0.5-2.0), a copolymer of polyvinylidene fluoride and hexafluoropropylene, and a sulfonating agent.
[0015] Preferably, the sulfonating agent includes chlorosulfonic acid and acesulfonate.
[0016] Preferably, the modified lignin is prepared by the following method: Acrylamide was dissolved in distilled water, and maleic anhydride and N,N'-methylenebisacrylamide were added to the acrylamide solution. The mixture was stirred to obtain solution 1. Sodium lignin sulfonate was dissolved in water to obtain an aqueous solution of sodium lignin sulfonate. Solution 1 was added to the aqueous solution of sodium lignin sulfonate, the pH was adjusted, an initiator was added, and the mixture was stirred at 60-90℃ for 1-2 hours. After washing and drying, modified lignin was obtained.
[0017] Preferably, the pH value is 3.5 to 4.5.
[0018] Preferably, core-shell ceramic microspheres are prepared by the following method: Polyvinylidene fluoride and hexafluoropropylene copolymer were added to N,N-dimethylformamide and stirred to dissolve. Hollow ceramic microspheres were added, and the mixture was sonicated for 1–3 h. After filtration, washing, and drying, a core-shell structure precursor was obtained. The core-shell structure precursor was added to an isopropanol solution of sodium hydroxide and stirred for 10–30 min. Then, it was added to deionized water, filtered, washed with deionized water until neutral, and dried to obtain a defluorinated core-shell precursor. The defluorinated precursor was added to 1-methyl-2-pyrrolidone, and a sulfonating agent was slowly added dropwise while stirring and reacting for 10–15 h. Then, it was added to ice water while stirring to precipitate the product. After filtration, it was washed with deionized water until the pH value was 7 and dried to obtain core-shell ceramic microspheres.
[0019] Preferably, in the isopropanol solution of sodium hydroxide, the concentration of sodium hydroxide is 0.01–0.1 mol / L.
[0020] Secondly, the present invention also discloses a preparation method, comprising the following steps: The lead powder, short fiber, acetylene black, and barium sulfate are dry-mixed evenly. Then, a hybrid expansion agent and deionized water are added and wet-mixed. Sulfuric acid is then slowly added and stirred. The temperature during the acid addition process should not exceed 60°C. After the acid addition is complete, the mixture is stirred for another 10 to 20 minutes to obtain the negative electrode lead paste.
[0021] Preferably, the dry mixing time is 3-7 minutes and the wet mixing time is 3-7 minutes.
[0022] Preferably, the density of sulfuric acid is 1.3 to 1.4 g / mL, and the dropping rate of sulfuric acid is 5 to 8 mL / min.
[0023] The beneficial effects of this invention are: This invention addresses the technical shortcomings of both organic and inorganic expanders in lead-acid battery negative electrode paste by designing an organic-inorganic hybrid expander system, achieving a significant improvement in the overall performance of the negative electrode. Traditional organic expanders, such as lignin sulfonates, while exhibiting good compatibility with the organic phase of lead paste, are prone to oxidative degradation during battery charging and discharging, leading to a rapid decline in expansion effect and shortened battery cycle life. While simple inorganic expanders, such as hollow ceramic microspheres, possess excellent high-temperature resistance and anti-degradation properties, effectively increasing negative electrode porosity, their lack of active functional groups on the surface results in poor interfacial compatibility with the organic phase of lead paste, easily leading to phase separation and failing to provide stable expansion. This invention utilizes a hybrid organic-inorganic expander system... Acrylamide-grafted lignin was composited with surface-sulfonated core-shell ceramic microspheres to construct a hybrid expansion agent system exhibiting both excellent interfacial compatibility and structural stability. The modified lignin retained the organic compatibility of sodium lignin sulfonate, while the polar groups introduced through graft copolymerization enhanced its antioxidant capacity and lead paste adhesion. The core-shell ceramic microspheres were constructed by coating hollow ceramic microspheres with vinylidene fluoride. The hexafluoropropylene copolymer shell grafted with sulfonic acid groups leverages the high-temperature resistance and high porosity advantages of the inorganic core while significantly improving interfacial affinity with the lead paste matrix through the introduction of organic polymers and sulfonic acid groups in the shell. This allows the organic and inorganic phases to form a stable three-dimensional network structure at the microscale. This hybrid design enables the expander to be uniformly dispersed in the lead paste and maintain a stable expansion effect over a long period, effectively inhibiting sulfation of the negative electrode active material and grid corrosion. It significantly improves the battery's low-temperature start-up performance, high-rate discharge capability, and cycle durability, thereby greatly extending the lifespan of lead-acid batteries and showing broad prospects for industrial application. Detailed Implementation
[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.
[0025] A lead-acid battery negative electrode paste, comprising the following components by weight: 1000 parts lead powder, 80-100 parts sulfuric acid, 100-120 parts water, 0.5-1 part short fiber, 2-3 parts acetylene black, 10-12 parts barium sulfate, and 0.3-1 part hybrid expansion agent; The hybrid expansion agent includes modified lignin and core-shell ceramic microspheres in a mass ratio of 1:(0.3-1).
[0026] By employing the above technical solutions, this invention modifies traditional sodium lignin sulfonate by adding a hybrid expanding agent. For example, it performs maleic anhydride-acrylamide binary graft copolymerization modification, covalently grafting acid-resistant maleic anhydride segments and acrylamide segments containing strongly polar amide and carboxyl groups onto the lignin macromolecule. These functional groups not only significantly enhance the chemical stability of lignin in sulfuric acid electrolyte, effectively inhibiting its dissolution and degradation during battery cycling and ensuring the long-term effectiveness of the expanding agent, but also introduce abundant hydrophilic groups and groups that may interact with lead ions, thereby constructing a more stable and uniformly distributed network structure in the negative electrode active material, maintaining the porosity and reactivity of the negative electrode. On the other hand, the core-shell ceramic microspheres in the hybrid expanding agent use hollow ceramic microspheres with a specific silicon-aluminum ratio as rigid cores. These microspheres themselves have excellent high-temperature resistance and degradation resistance, and can play a supporting role in the negative electrode framework, preventing the shrinkage of the active material and providing a stable ion transport channel for electrochemical reactions. Furthermore, coating the surface with vinylidene fluoride-hexafluoropropylene copolymer and further grafting sulfonic acid groups creates an organic shell that significantly improves the interfacial compatibility between the ceramic microspheres and other organic components in the lead paste, as well as the lead powder, preventing phase separation. In addition, the sulfonic acid groups grafted onto the shell possess excellent hydrophilicity and ion exchange capacity, enabling them to conduct protons. This is equivalent to endowing the originally inert inorganic microspheres with electrochemical activity, allowing them to participate in the ion conduction network of the negative electrode, rather than merely serving as an inert filler.
[0027] Modified lignin and core-shell ceramic microspheres synergistically enhance the structural durability, interfacial stability, and electrochemical activity of negative electrode lead paste. Specifically, the network structure constructed by modified lignin provides an ideal dispersion carrier for the core-shell ceramic microspheres, while the rigid framework of the core-shell ceramic microspheres provides stable physical support for the lignin network structure. The organic shell layer on the surface of the ceramic microspheres solves the problem of poor compatibility between inorganic microspheres and organic expanding agents. Modified lignin can be tightly adsorbed and wrapped around the surface of ceramic microspheres with a vinylidene fluoride-hexafluoropropylene copolymer shell, forming a tightly bonded composite material that ensures the continuity of stress transmission and structural integrity. In addition, the carboxyl / amide groups provided by modified lignin and the sulfonic acid groups provided by the core-shell microspheres together constitute a highly efficient three-dimensional proton conduction network.
[0028] In some embodiments, the modified lignin is obtained by binary graft copolymerization of sodium lignin sulfonate and maleic anhydride-acrylamide; the raw materials for the modified lignin include sodium lignin sulfonate, maleic anhydride, acrylamide, N,N'-methylenebisacrylamide and an initiator in a mass ratio of 1:(8-12):(6-10):(0.02-0.06):(0.1-0.3); the initiator includes potassium persulfate and ammonium persulfate.
[0029] By employing the above technical solutions, the introduction of maleic anhydride segments can significantly improve the acid resistance of lignin, while acrylamide segments provide abundant polar amide and carboxyl groups, enhancing the binding force between lignin and lead-based active substances. N,N'-methylenebisacrylamide, as a crosslinking agent, can construct a moderately crosslinked lignin molecular network, further reducing its dissolution rate in the electrolyte. Potassium persulfate / ammonium persulfate, as a water-soluble initiator, can efficiently initiate graft copolymerization reactions in a mild aqueous system. This raw material ratio range ensures both the deep modification effect of lignin and avoids excessive grafting that leads to a decrease in lignin surface activity and loss of the basic surface adsorption and expansion functions of the swelling agent.
[0030] In some embodiments, core-shell ceramic microspheres include hollow ceramic microspheres, the shell being a copolymer of polyvinylidene fluoride and hexafluoropropylene and grafted with sulfonic acid groups; the hollow ceramic microspheres comprise 55%–60% silica and 35%–40% alumina. The raw materials for the core-shell ceramic microspheres include hollow ceramic microspheres in a mass ratio of 1:(0.03–0.1):(0.5–2.0), the polyvinylidene fluoride and hexafluoropropylene copolymer, and a sulfonating agent. The sulfonating agent includes chlorosulfonic acid and acetylsulinate.
[0031] By adopting the above technical solutions, hollow ceramic microspheres can provide a stable three-dimensional channel for electrolyte transport, while avoiding the increased brittleness of microspheres caused by excessive silica content and the decreased acid resistance caused by excessive alumina content. By limiting the raw material ratio of core-shell ceramic microspheres, the coating thickness of the shell polymer can be precisely controlled, ensuring complete coating of the inorganic core by the shell layer, greatly improving compatibility with the lead paste matrix, and avoiding the blockage of the pore structure of ceramic microspheres by excessive coating. By selecting chlorosulfonic acid and acetylsulinate as sulfonating agents, sulfonic acid groups can be efficiently introduced into the shell polymer, endowing the inorganic microspheres with proton conduction ability and hydrophilicity, so that the originally inert ceramic microspheres have electrochemical activity and can participate in the electrochemical reaction process of the negative electrode, rather than just serving as an inert filler material.
[0032] In some embodiments, modified lignin is prepared by the following method: Acrylamide was dissolved in distilled water. Maleic anhydride and N,N'-methylenebisacrylamide were added to the acrylamide solution and stirred to obtain solution 1. Sodium lignin sulfonate was dissolved in water to obtain an aqueous solution of sodium lignin sulfonate. Solution 1 was added to the aqueous solution of sodium lignin sulfonate, the pH was adjusted to 3.5-4.5, an initiator was added, and the mixture was stirred at 60-90℃ for 1-2 hours. After washing and drying, modified lignin was obtained.
[0033] By adopting the above technical solution, firstly, acrylamide, maleic anhydride, and crosslinking agent N,N'-methylenebisacrylamide are pre-mixed to form solution 1, ensuring uniform distribution of monomers. The crosslinking agent can form a slightly crosslinked three-dimensional network structure during polymerization, locking the graft copolymer chains onto the lignin skeleton, greatly enhancing the structural stability of the modified lignin in the electrolyte and preventing it from being washed away during long-term cycling. Adding solution 1 to the sodium lignin sulfonate solution and adjusting the pH to 3.5–4.5 is to prevent premature hydrolysis of maleic anhydride under alkaline conditions, ensuring that it participates in the grafting reaction in anhydride form. Finally, free radical polymerization is initiated by an initiator at 60–90℃, achieving efficient grafting of monomers onto lignin.
[0034] In some embodiments, core-shell ceramic microspheres are prepared by the following method: Polyvinylidene fluoride and hexafluoropropylene copolymer were added to N,N-dimethylformamide and stirred to dissolve. Hollow ceramic microspheres were added, and the mixture was sonicated for 1–3 h. After filtration, washing, and drying, a core-shell structure precursor was obtained. The core-shell structure precursor was added to an isopropanol solution of sodium hydroxide and stirred for 10–30 min. Then, it was added to deionized water, filtered, washed with deionized water until neutral, and dried to obtain a defluorinated core-shell precursor. The defluorinated precursor was added to 1-methyl-2-pyrrolidone, and a sulfonating agent was slowly added dropwise while stirring and reacting for 10–15 h. Then, it was added to ice water while stirring to precipitate the product. After filtration, it was washed with deionized water until the pH value was 7 and dried to obtain core-shell ceramic microspheres.
[0035] In the isopropanol solution of sodium hydroxide, the concentration of sodium hydroxide is 0.01–0.1 mol / L.
[0036] By employing the above technical solution, a uniform physical coating layer is formed on the surface of hollow ceramic microspheres using the solubility of polyvinylidene fluoride and hexafluoropropylene copolymer (PVDF-HFP) in N,N-dimethylformamide and ultrasonic action, thus obtaining a core-shell precursor. Then, the PVDF-HFP shell is mildly defluorinated with hydrogen using a dilute NaOH isopropanol solution. This introduces active carbon-carbon double bonds into the inert PVDF-HFP molecular chain, providing reaction anchors for subsequent chemical grafting. Finally, sulfonating agents such as chlorosulfonic acid undergo electrophilic addition reactions with the double bonds, covalently bonding sulfonic acid groups to the shell. This method of introducing functional groups through chemical bonds is more robust than simple physical adsorption or blending, ensuring the long-term effectiveness of the sulfonic acid groups during battery cycling.
[0037] In some embodiments, the short fibers include aramid fibers, polypropylene fibers, and polyester fibers, wherein the aramid fibers include poly(p-phenylene terephthalamide).
[0038] A preparation method, comprising the following steps: The lead powder, short fiber, acetylene black, and barium sulfate are dry-mixed evenly. Then, a hybrid expansion agent and deionized water are added and wet-mixed. Sulfuric acid is then slowly added and stirred. The temperature during the acid addition process should not exceed 60°C. After the acid addition is complete, the mixture is stirred for another 10 to 20 minutes to obtain the negative electrode lead paste.
[0039] In some embodiments, the dry mixing time is 3 to 7 minutes, and the wet mixing time is 3 to 7 minutes.
[0040] In some embodiments, the density of sulfuric acid is 1.3 to 1.4 g / mL, and the dropping rate of sulfuric acid is 5 to 8 mL / min.
[0041] By adopting the above technical solutions and employing the classic paste-making process of dry mixing, wet mixing, and acid addition, and specifically adding the hybrid expansion agent during the wet mixing stage, it is beneficial for the agent to be pre-wetted and dispersed in water before being fully mixed with the dry mix, thus avoiding local agglomeration caused by direct dry mixing. Strict control of the acid addition rate and process temperature is to prevent excessively high local acid concentrations or rapid temperature rises from damaging the structure of the hybrid expansion agent, especially to prevent the sulfonic acid groups from detaching or the modified lignin from degrading under extreme conditions, ensuring the uniformity of the lead paste and the consistency of the final product's performance.
[0042] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.
[0043] Preparation Example Preparation Example 1-1: A modified lignin was prepared by the following method: 9g of acrylamide was dissolved in 100mL of distilled water. 8g of maleic anhydride and 0.02g of N,N'-methylenebisacrylamide were added to the acrylamide solution, and the mixture was stirred to obtain solution 1. 1g of sodium lignin sulfonate was dissolved in 50mL of water to obtain an aqueous solution of sodium lignin sulfonate. Solution 1 was added to the sodium lignin sulfonate aqueous solution, the pH was adjusted to 4, and 0.12g of potassium persulfate initiator was added. After stirring and reacting at 80℃ for 1h, the product was poured into excess anhydrous ethanol to precipitate, and then filtered. The product was washed three times with distilled water, then once with anhydrous ethanol, and dried at 50℃ to obtain modified lignin.
[0044] Preparation Examples 1-2: A modified lignin was prepared by the following method: 4g of acrylamide was dissolved in 80mL of distilled water. 6g of maleic anhydride and 0.02g of N,N'-methylenebisacrylamide were added to the acrylamide solution, and the mixture was stirred to obtain solution 1. 1g of sodium lignin sulfonate was dissolved in 50mL of water to obtain an aqueous solution of sodium lignin sulfonate. Solution 1 was added to the sodium lignin sulfonate aqueous solution, the pH was adjusted to 4, and 0.12g of potassium persulfate initiator was added. After stirring and reacting at 80℃ for 1h, the product was poured into excess anhydrous ethanol to precipitate, and then filtered. The product was washed three times with distilled water, then washed once with anhydrous ethanol, and dried at 50℃ to obtain the modified lignin.
[0045] Preparation Example 2-1: A core-shell type ceramic microsphere was prepared by the following method: Add 0.04g of polyvinylidene fluoride and hexafluoropropylene copolymer to 50mL Dissolve N,N-dimethylformamide by stirring, add 1g of hollow ceramic microspheres (55%–60% silica, 35%–40% alumina), sonicate for 1h, filter to separate the solid product, wash twice with N,N-dimethylformamide, and dry at 60℃ for 12h to obtain a core-shell structure precursor; add the core-shell structure precursor to a 0.05M sodium hydroxide isopropanol solution, stir for 30min, then add it to deionized water, filter, wash with deionized water until pH 7, and dry at 60℃ for 12h to defluorinate the core-shell precursor; add the defluorinated precursor to 300mL of 1-methyl-2-pyrrolidone, stir and disperse in an ice bath, slowly add 1mL of sulfonating agent chlorosulfonic acid, stir and react for 12h, then add it to ice water while stirring to precipitate the product, filter, wash with deionized water until pH 7, and dry at 60℃ for 12h to obtain core-shell ceramic microspheres.
[0046] Preparation Example 2-2: A core-shell type ceramic microsphere was prepared by the following method: 0.04 g of polyvinylidene fluoride and hexafluoropropylene copolymer was added to 50 mL of N,N-dimethylformamide and stirred to dissolve. 1 g of hollow ceramic microspheres (55%–60% silica and 35%–40% alumina) were added, and the mixture was sonicated for 1 h. The solid product was separated by filtration, washed twice with N,N-dimethylformamide, and dried at 60 °C for 12 h to obtain core-shell ceramic microspheres.
[0047] Preparation Examples 2-3: A core-shell type ceramic microsphere was prepared by the following method: 0.04 g of polyvinylidene fluoride and hexafluoropropylene copolymer was added to 50 mL of N,N-dimethylformamide and stirred to dissolve. 1 g of hollow ceramic microspheres (55%–60% silica, 35%–40% alumina) were added, and the mixture was sonicated for 1 h. The solid product was separated by filtration, washed twice with N,N-dimethylformamide, and dried at 60 °C for 12 h to obtain the core-shell structure precursor. The core-shell structure precursor was added to a 0.05 M sodium hydroxide solution in isopropanol and stirred for 30 min. Then, it was added to deionized water, filtered, washed with deionized water until the pH value was 7, and dried at 60℃ for 12h to defluorinate the core-shell precursor. The defluorinated precursor was added to 300mL of 1-methyl-2-pyrrolidone, stirred and dispersed in an ice bath, and 0.1mL of sulfonating agent chlorosulfonic acid was slowly added dropwise. After stirring and reacting for 12h, it was added to ice water while stirring to precipitate the product. After filtration, it was washed with deionized water until the pH value was 7, and dried at 60℃ for 12h to obtain core-shell ceramic microspheres.
[0048] Example Example 1: A lead paste for the negative electrode of a lead-acid battery is prepared by the following method: Mix 1000 parts lead powder, 0.8 parts short fibers (poly(p-phenylene terephthalamide)), 3 parts acetylene black, and 11 parts barium sulfate dry for 5 minutes to ensure uniform mixing. Add 0.6 parts hybrid expansion agent and 110 parts deionized water and wet mix for 5 minutes. Then add 90 parts sulfuric acid (density 1.4 g / cm³) at a dropping rate of 6 mL / min. 3 Stirring, the temperature during acid addition should not exceed 60℃, and stirring for another 20 minutes after acid addition is complete to obtain negative electrode lead paste; The hybrid expansion agents include modified lignin prepared in Preparation Example 1-1 at a mass ratio of 1:0.6 and core-shell ceramic microspheres prepared in Preparation Example 2-1.
[0049] Example 2, a lead-acid battery negative electrode paste, differs from Example 1 only in that the hybrid expansion agent includes modified lignin prepared in Preparation Example 1-1 at a mass ratio of 1:0.3 and core-shell ceramic microspheres prepared in Preparation Example 2-1.
[0050] Example 3, a lead-acid battery negative electrode paste, differs from Example 1 only in that the hybrid expansion agent includes modified lignin prepared in Preparation Example 1-1 and core-shell ceramic microspheres prepared in Preparation Example 2-1 at a mass ratio of 1:1.
[0051] Example 4: A lead paste for the negative electrode of a lead-acid battery, prepared by the following method: Mix 1000 parts lead powder, 0.8 parts short fibers (poly(p-phenylene terephthalamide)), 2 parts acetylene black, and 10 parts barium sulfate dry for 5 minutes to ensure uniform mixing. Add 0.3 parts hybrid expansion agent and 100 parts deionized water and wet mix for 5 minutes. Then add 80 parts sulfuric acid (density 1.4 g / cm³) at a dropping rate of 6 mL / min. 3 Stirring, the temperature during acid addition should not exceed 60℃, and stirring for another 20 minutes after acid addition is complete to obtain negative electrode lead paste; The hybrid expansion agents include modified lignin prepared in Preparation Example 1-1 at a mass ratio of 1:0.6 and core-shell ceramic microspheres prepared in Preparation Example 2-1.
[0052] Example 5: A lead paste for the negative electrode of a lead-acid battery, prepared by the following method: Mix 1000 parts lead powder, 1 part short fiber (poly(p-phenylene terephthalamide)), 3 parts acetylene black, and 12 parts barium sulfate dry for 5 minutes to ensure uniform mixing. Add 1 part hybrid swelling agent and 120 parts deionized water and wet mix for 5 minutes. Then add 80 parts sulfuric acid (density 1.4 g / cm³) at a dropping rate of 6 mL / min. 3 Stirring, the temperature during acid addition should not exceed 60℃, and stirring for another 20 minutes after acid addition is complete to obtain negative electrode lead paste; The hybrid expansion agents include modified lignin prepared in Preparation Example 1-1 at a mass ratio of 1:0.6 and core-shell ceramic microspheres prepared in Preparation Example 2-1.
[0053] Comparative Example Comparative Example 1, a negative electrode paste for lead-acid batteries, differs from Example 1 only in that the hybrid expansion agent includes modified lignin prepared in Preparation Examples 1-2 at a mass ratio of 1:0.6 and core-shell ceramic microspheres prepared in Preparation Examples 2-1.
[0054] Comparative Example 2, a negative electrode paste for lead-acid batteries, differs from Example 1 only in that the hybrid expansion agent includes modified lignin prepared in Preparation Example 1-1 at a mass ratio of 1:0.6 and core-shell ceramic microspheres prepared in Preparation Example 2-2.
[0055] Comparative Example 3, a lead-acid battery negative electrode paste, differs from Example 1 only in that the hybrid expansion agent includes modified lignin prepared in Preparation Example 1-1 at a mass ratio of 1:0.6 and core-shell ceramic microspheres prepared in Preparation Example 2-3.
[0056] Comparative Example 4, a lead-acid battery negative electrode paste, differs from Example 1 only in that it uses a hybrid expanding agent comprising sodium lignosulfonate and hollow ceramic microspheres in a mass ratio of 1:0.6.
[0057] Performance testing Taking the 6-DZF-20 battery as an example, according to GB / T 22199.1-2017, the negative electrode lead paste for lead-acid batteries prepared in Examples 1-4 and Comparative Examples 1-4 of this invention was applied to lead-acid batteries. The electrochemical performance of the resulting lead-acid batteries is shown in Table 1. Table 1 Performance test results
[0058] Compared to Example 1, Comparative Example 1 used the modified lignin prepared in Preparation Examples 1-2. The amount of maleic anhydride and acrylamide monomers added was lower in Comparative Example 1, resulting in an imbalance of functional groups on the modified lignin molecular chain and reduced grafting efficiency. This led to insufficient chemical stability of the modified lignin in the electrolyte, weakened complexation with lead ions, and increased sulfation of the negative electrode during cycling, resulting in accelerated shrinkage of the active material. Therefore, its cycle life and low-temperature performance were lower than those of Example 1.
[0059] Comparative Example 2 used untreated core-shell ceramic microspheres. Although the surface of the microspheres was coated with a polyvinylidene fluoride and hexafluoropropylene copolymer shell, improving its physical compatibility with the organic phase, the lack of sulfonic acid groups on the shell resulted in poor interfacial hydrophilicity and ion conductivity. This caused the microspheres to act as inert fillers in the negative electrode, unable to form an effective synergistic conduction with the organic network constructed from modified lignin. Therefore, although the initial capacity was acceptable, due to the high interfacial resistance and hindered ion transport, its high-current performance and cycle life were far lower than those of Example 1, and its performance degraded more rapidly during long-term cycling.
[0060] Comparative Example 3 used core-shell ceramic microspheres with insufficient sulfonating agent. Although a small amount of sulfonic acid groups were introduced into its shell, the grafting density was low, making it impossible to form a continuous and efficient proton conduction network. The abundant carboxyl / amide groups of the modified lignin could not fully construct a hydrogen bond network with the sparse sulfonic acid groups, resulting in weak synergistic effects between the organic and inorganic phases. Therefore, the performance indicators of Comparative Example 3 were still lower than those of Example 1.
[0061] Comparative Example 4 used a simple mixture of unmodified sodium lignin sulfonate and uncoated hollow ceramic microspheres as an expanding agent. Unmodified lignin dissolved and degraded significantly during formation and cycling, rapidly becoming ineffective; the unmodified ceramic microspheres had extremely poor compatibility with the lead paste matrix, easily undergoing phase separation and failing to provide a supporting framework. There was also no synergistic effect between the two.
[0062] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.
Claims
1. A lead paste for the negative electrode of a lead-acid battery, characterized in that, By weight, it includes the following components: 1000 parts lead powder, 80-100 parts sulfuric acid, 100-120 parts water, 0.5-1 part short fiber, 2-3 parts acetylene black, 10-12 parts barium sulfate, and 0.3-1 part hybrid expansion agent; The hybrid expansion agent comprises modified lignin and core-shell ceramic microspheres in a mass ratio of 1:(0.3-1).
2. The lead paste for the negative electrode of a lead-acid battery according to claim 1, characterized in that, The modified lignin is obtained by binary graft copolymerization of sodium lignin sulfonate and maleic anhydride-acrylamide.
3. The lead paste for the negative electrode of a lead-acid battery according to claim 1, characterized in that, The core-shell type ceramic microspheres include hollow ceramic microspheres, with the shell being a copolymer of polyvinylidene fluoride and hexafluoropropylene, and the shell being grafted with sulfonic acid groups. The hollow ceramic microspheres comprise 55%–60% silicon dioxide and 35%–40% aluminum oxide.
4. The lead paste for the negative electrode of a lead-acid battery according to claim 2, characterized in that, The modified lignin raw materials include sodium lignin sulfonate, maleic anhydride, acrylamide, N,N'-methylenebisacrylamide and an initiator in a mass ratio of 1:(8-12):(6-10):(0.02-0.06):(0.1-0.3).
5. The lead paste for the negative electrode of a lead-acid battery according to claim 3, characterized in that, The raw materials for the core-shell ceramic microspheres include hollow ceramic microspheres in a mass ratio of 1:(0.03~0.1):(0.5~2.0), a copolymer of polyvinylidene fluoride and hexafluoropropylene, and a sulfonating agent.
6. The lead paste for the negative electrode of a lead-acid battery according to claim 4, characterized in that, The modified lignin was prepared by the following method: Acrylamide was dissolved in distilled water. Maleic anhydride and N,N'-methylenebisacrylamide were added to the acrylamide solution and stirred to obtain solution 1. Solution 1 was added to an aqueous solution of sodium lignosulfonate, the pH was adjusted, an initiator was added, and the mixture was stirred at 60-90°C for 1-2 hours. After washing and drying, modified lignin was obtained.
7. The lead paste for the negative electrode of a lead-acid battery according to claim 5, characterized in that, The core-shell ceramic microspheres were prepared by the following method: Polyvinylidene fluoride and hexafluoropropylene copolymer were added to N,N-dimethylformamide and stirred to dissolve. Hollow ceramic microspheres were added, and the mixture was sonicated for 1–3 h. After filtration, washing, and drying, a core-shell structure precursor was obtained. The core-shell structure precursor was added to an isopropanol solution of sodium hydroxide and stirred for 10–30 min. Then, it was added to deionized water, filtered, washed with deionized water until neutral, and dried to obtain a defluorinated core-shell precursor. The defluorinated precursor was added to 1-methyl-2-pyrrolidone, and a sulfonating agent was slowly added dropwise while stirring and reacting for 10–15 h. Then, it was added to ice water while stirring to precipitate the product. After filtration, it was washed with deionized water until the pH value was 7 and dried to obtain core-shell ceramic microspheres.
8. A preparation method for preparing the negative electrode lead paste for lead-acid batteries according to any one of claims 1-7, characterized in that, Includes the following steps: The lead powder, short fiber, acetylene black, and barium sulfate are dry-mixed evenly. Then, a hybrid expansion agent and deionized water are added and wet-mixed. Sulfuric acid is then slowly added and stirred. The temperature during the acid addition process should not exceed 60°C. After the acid addition is complete, the mixture is stirred for another 10 to 20 minutes to obtain the negative electrode lead paste.
9. The preparation method according to claim 8, characterized in that, The dry mixing time is 3-7 min, and the wet mixing time is 3-7 min; the density of the sulfuric acid is 1.3-1.4 g / mL, and the dropping rate of the sulfuric acid is 5-8 mL / min.
10. A negative electrode, characterized in that, Includes the lead paste for the negative electrode of a lead-acid battery as described in any one of claims 1-7.