Lead-acid battery negative electrode additive, preparation method and application thereof

Abstract

The present application relates to a kind of lead-acid battery negative electrode additive and its preparation method and application, belong to lead-acid battery technical field.The additive is composed of sulfonated modified lignin sulfonate (component A), graphene oxide-carbon nanotube hybrid conductive agent (component B), the mixture of modified humic acid and boric acid (component C), three are respectively as crystallization template agent, conductive network construction agent and interface film forming regulator.In preparation, first, component A is prepared by sulfomethylation reaction, component B is prepared by ultrasonic mixing graphene oxide and carbon nanotube dispersion liquid, component C is prepared by mixing after acid washing purification and oxidation humic acid and boric acid, finally, three components are mixed to obtain finished product.The additive is added to negative lead paste, can inhibit negative sulfurization, improve electrode conductivity, reduce hydrogen evolution side reaction, prolong battery cycle life and charge-discharge efficiency, suitable for various lead-acid battery production.

Description

Technical Field

[0001] This invention belongs to the field of lead-acid battery technology, and relates to a lead-acid battery negative electrode additive, its preparation method and application. Background Technology

[0002] As one of the oldest rechargeable batteries, lead-acid batteries hold an irreplaceable position in many fields such as new energy storage, electric vehicles, and emergency backup power due to their outstanding advantages, including low cost, mature manufacturing process, excellent high-current discharge performance, and high safety and reliability. Their core working principle is based on the electrochemical reaction between the positive and negative electrode active materials and the sulfuric acid electrolyte to achieve charge-discharge cycles. The reactivity and structural stability of the negative electrode lead paste directly determine the battery's capacity characteristics and cycle life; therefore, optimizing the negative electrode performance is a key direction for improving the overall quality of lead-acid batteries.

[0003] However, during long-term charge-discharge cycles, lead-acid batteries are prone to multiple performance degradation issues at the negative electrode, severely limiting their lifespan. Irreversible sulfation is the primary problem; the lead sulfate generated during discharge tends to form coarse, dense crystals that adhere to the negative electrode surface, making it difficult to reduce to spongy lead during charging. Simultaneously, the active material at the negative electrode is prone to shedding and pulverizing during cycling, leading to degradation of the internal conductive network and a significant increase in electron transport resistance. Furthermore, hydrogen evolution side reactions on the negative electrode surface continuously consume electrolyte and active material, not only reducing charging efficiency but also potentially causing safety hazards such as battery swelling.

[0004] To alleviate the aforementioned problems, existing technologies mostly employ the addition of functional additives to optimize anode performance. Traditional expanding agents, such as lignin-based substances, can inhibit lead sulfate crystal growth through steric hindrance, but their insufficient dispersibility can affect electrode conductivity. While simple carbon-based conductive agents (such as graphite and carbon black) can improve the conductive network, they have no significant inhibitory effect on sulfation and hydrogen evolution side reactions. Currently, most additives have the limitation of single function, making it difficult to simultaneously solve multiple anode degradation problems. Some composite additives also exhibit performance antagonism due to poor component matching, failing to achieve synergistic effects. Therefore, developing high-efficiency anode additives with multiple functions has become an urgent industry need. Summary of the Invention

[0005] The purpose of this invention is to provide a lead-acid battery negative electrode additive, its preparation method, and its application. The additive components A, B, and C target sulfation, conductivity decay, and hydrogen evolution side reactions, respectively, and form a synergistic enhancement effect within the negative electrode, thereby improving the battery's cycle life, charge acceptance, and overcharge tolerance.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A lead-acid battery negative electrode additive, composed of the following components:

[0008] A. Sulfonated modified lignin sulfonates, used as crystallization templates;

[0009] B. A hybrid conductive agent composed of graphene oxide and carbon nanotubes, used as a conductive network builder;

[0010] C. A mixture of modified humic acid and boron-containing compounds, used as an interfacial film-forming modifier;

[0011] The mass ratio of component A, component B, and component C is (0.05-2.0):(0.01-1.0):(0.05-2.0).

[0012] The additive is used to inhibit the sulfation of the negative electrode active material, improve conductivity, and reduce hydrogen evolution side reactions.

[0013] As a preferred embodiment of the present invention, the sulfonated modified sodium lignin sulfonate has sulfonic acid groups and carboxyl groups introduced into its molecular chain through a sulfonation methylation reaction.

[0014] In this application, sodium lignin sulfonate was modified by sulfonation, introducing additional hydrophilic sulfonic acid groups (-SO3H) and carboxyl groups (-COOH) onto the benzene ring of the lignin molecular chain. The introduced strong hydrophilic groups significantly improved its dispersibility in sulfuric acid electrolyte, allowing it to be more uniformly adsorbed onto the surface of lead and PbSO4 crystal nuclei. The uniformly adsorbed modified lignin molecules form a denser and more uniform organic molecular film on the negative electrode surface. This film acts as a "template," effectively hindering the excessive growth of PbSO4 crystals and guiding PbSO4 to precipitate in a fine, loose, and porous microcrystalline morphology. This morphology of PbSO4 is easily reduced back to active sponge-like lead during charging, thus fundamentally inhibiting irreversible sulfation. After modification, its molecular weight distribution is narrower, and its performance is more stable, avoiding the inconsistent battery performance caused by component fluctuations in traditional products.

[0015] Graphene oxide (GO) has a two-dimensional sheet structure, while carbon nanotubes (CNTs) have a one-dimensional fiber structure. After hybridization using processes such as ultrasound, CNTs can intercalate and overlap between the graphene oxide sheets, forming a stable, three-dimensional interconnected conductive framework. This framework is embedded in the lead-based active material, ensuring unobstructed electronic pathways even during volume changes, thus reducing electrode resistance and polarization. Furthermore, both GO and CNTs possess enormous specific surface areas and abundant surface functional groups. These surface sites provide a vast number of uniformly distributed nucleation centers for the deposition / precipitation of Pb and PbSO4. This facilitates uniform electrochemical reactions within the electrode, avoiding localized current concentration and restricted mass transport, further promoting the formation of a refined active material structure. This nano-carbon network also exhibits excellent mechanical strength, supporting and binding the surrounding lead-based active material, effectively inhibiting softening and shedding during cycling, and maintaining the integrity of the electrode structure.

[0016] Humic acid was purified by acid washing and oxidation. High-purity, carboxyl-rich humic acid reacts with Pb in solution. 2+ The ions possess stronger complexing ability and can adsorb onto the surface of PbSO4 crystals during crystal growth, gently inhibiting excessive growth without unduly hindering the electrochemical reduction reaction during charging. In the sulfuric acid environment of the negative electrode, boric acid participates in the formation of a very thin lead borate (Pb3(BO3)2) or boron-containing complex interfacial film. This film stabilizes the pH value of the electrode / electrolyte interface microregion and buffers H+ during charging and discharging. + Drastic fluctuations in concentration increase the overpotential of the hydrogen evolution reaction and suppress hydrogen evolution side reactions. This dense film also coats the surface of the active material, reducing its direct contact with the electrolyte and slowing down corrosion and softening.

[0017] As a preferred embodiment of the present invention, in the hybrid conductive agent, the mass ratio of graphene oxide to carbon nanotubes is 1:10 to 10:1, the sheet diameter of the graphene oxide is 0.5-20 μm, and the carbon nanotubes are short-cut multi-walled carbon nanotubes with a length of 1-20 μm.

[0018] As a preferred embodiment of the present invention, the humic acid is purified and oxidized humic acid with a carboxyl content greater than 5.0 mmol / g; the boron-containing compound is boric acid.

[0019] As a preferred embodiment of the present invention, the mass ratio of humic acid to boric acid is 1:5 to 5:1.

[0020] Furthermore, a method for preparing the aforementioned lead-acid battery negative electrode additive includes the following steps:

[0021] (1) Sodium lignosulfonate was dissolved in an alkaline aqueous solution and reacted with a sulfonylmethylating agent under heating and stirring conditions to obtain sulfonated modified lignosulfonate, which was used as component A;

[0022] (2) The dispersion of graphene oxide and the dispersion of carbon nanotubes are mixed, and the mixture is subjected to ultrasonic treatment and drying to obtain a hybrid conductive agent composed of graphene oxide and carbon nanotubes, which is used as component B.

[0023] (3) The humic acid is acid washed and purified to remove ash and metal ion impurities, and then oxidized to increase the carboxyl content to obtain modified humic acid. The modified humic acid is physically mixed with boric acid powder to obtain a uniform interfacial film-forming regulator, which is used as component C.

[0024] (4) Mix component A obtained in step (1), component B obtained in step (2), and component C obtained in step (3) evenly to obtain the final product.

[0025] As a preferred technical solution of the present invention, in step (1), the sulfonylating agent is formaldehyde and sodium sulfite or formaldehyde and sodium bisulfite.

[0026] As a preferred technical solution of the present invention, in step (3), the oxidant used in the oxidation treatment is one of hydrogen peroxide, nitric acid or potassium permanganate.

[0027] Furthermore, a lead-acid battery negative electrode paste comprises lead powder, sulfuric acid, water, and lead-acid battery negative electrode additives as described above.

[0028] As a preferred embodiment of the present invention, based on the mass of lead powder, the total amount of the additive composition is 0.1-5.0 wt%; wherein, the amount of component A is 0.05-2.0 wt%, the amount of component B is 0.01-1.0 wt%, and the amount of component C is 0.05-2.0 wt%.

[0029] The beneficial effects of this invention are:

[0030] (1) This invention combines a specially modified lignin derivative, a nano-carbon hybrid conductive agent, and a humic acid-boric acid interface modifier to form a synergistic system of "template regulation-conductivity enhancement-interface protection". This system can simultaneously overcome the core failure problems of lead-acid battery anodes such as sulfation, conductive network degradation, and hydrogen evolution side reactions from three levels: crystallography, electrical engineering, and interface chemistry, thus achieving a systematic and comprehensive improvement in battery performance.

[0031] (2) Through sulfonation modification, the hydrophilicity and adsorption uniformity of component A (lignin sulfonate) are greatly improved, and a denser and more uniform molecular template layer can be formed on the negative electrode surface. This template layer can effectively block space and guide PbSO4 to precipitate in the form of fine, loose, and porous microcrystalline morphology, rather than the traditional bulk dense crystals, thereby significantly improving the reversibility of PbSO4 during charging, fundamentally and effectively inhibiting the occurrence of irreversible sulfation, and extending the deep cycle life of the battery.

[0032] (3) Component B employs a graphene oxide (GO) and carbon nanotube (CNT) hybrid system, which can form a three-dimensional interconnected nano-conductive framework. This framework is embedded in the active material, providing an ultra-high electronic conductivity pathway, greatly reducing the internal resistance and polarization of the electrode, and improving the charge acceptance and high-current discharge performance. At the same time, this network has excellent mechanical strength, which can effectively support and bind the active material, inhibit its softening and shedding during cycling, and maintain the integrity of the electrode structure.

[0033] (4) Boric acid in component C can participate in the formation of an extremely thin borate / complex membrane at the negative electrode interface. This membrane has unique ion selectivity and can stabilize the interface pH and buffer H+. + Concentration fluctuations significantly hinder H + The modified humic acid migrates to the electrode surface, significantly increasing the hydrogen evolution overpotential and effectively suppressing hydrogen evolution side reactions. This not only reduces water loss from the battery and lowers maintenance requirements, but also improves the battery's safety and durability under harsh conditions such as overcharging. Modified humic acid also affects Pb. 2+ The mild complexing effect of boric acid complements the film-forming effect of boric acid; the three-dimensional conductive network provides a larger working area for the template agent and interface modifier; and the uniform interface environment ensures the long-term and stable performance of the functions of the former two. Detailed Implementation

[0034] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0035] Example 1

[0036] A lead-acid battery negative electrode additive, composed of the following components:

[0037] A. Sulfonated modified lignin sulfonates, used as crystallization templates;

[0038] B. A hybrid conductive agent composed of graphene oxide and carbon nanotubes, used as a conductive network builder;

[0039] C. A mixture of modified humic acid and boron-containing compounds, used as an interfacial film-forming modifier;

[0040] The additive is used to inhibit the sulfation of the negative electrode active material, improve conductivity, and reduce hydrogen evolution side reactions.

[0041] The sulfonated modified sodium lignin sulfonate has sulfonic acid groups and carboxyl groups introduced into its molecular chain through a sulfonation methylation reaction.

[0042] In the hybrid conductive agent, the mass ratio of graphene oxide to carbon nanotubes is 3:1, the diameter of the graphene oxide sheets is 0.5-20 μm, and the carbon nanotubes are short-cut multi-walled carbon nanotubes with a length of 1-20 μm.

[0043] The humic acid is purified and oxidized, and its carboxyl content is 5.5 mmol / g; the boron-containing compound is boric acid.

[0044] The mass ratio of humic acid to boric acid is 2:1.

[0045] A method for preparing the lead-acid battery negative electrode additive includes the following steps:

[0046] (1) Sodium lignosulfonate was dissolved in an alkaline aqueous solution and reacted with a sulfonylmethylating agent under heating and stirring conditions to obtain sulfonated modified lignosulfonate, which was used as component A;

[0047] (2) The dispersion of graphene oxide and the dispersion of carbon nanotubes are mixed, and the mixture is subjected to ultrasonic treatment and drying to obtain a hybrid conductive agent composed of graphene oxide and carbon nanotubes, which is used as component B.

[0048] (3) The humic acid is acid washed and purified to remove ash and metal ion impurities, and then oxidized to increase the carboxyl content to obtain modified humic acid. The modified humic acid is physically mixed with boric acid powder to obtain a uniform interfacial film-forming regulator, which is used as component C.

[0049] (4) Mix component A obtained in step (1), component B obtained in step (2), and component C obtained in step (3) evenly to obtain the final product.

[0050] In step (1), the sulfonylating agent is formaldehyde and sodium sulfite.

[0051] In step (3), the oxidant used in the oxidation treatment is hydrogen peroxide.

[0052] A lead-acid battery negative electrode paste comprises lead powder, sulfuric acid, water, and the aforementioned lead-acid battery negative electrode additive.

[0053] The mass ratio of lead powder, sulfuric acid, and water is 100:10:13.

[0054] Based on the mass of lead powder, the total amount of the additive composition is 1.7 wt%; wherein, the amount of component A is 0.8 wt%, the amount of component B is 0.3 wt%, and the amount of component C is 0.6 wt%.

[0055] Example 2

[0056] A lead-acid battery negative electrode additive, composed of the following components:

[0057] A. Sulfonated modified lignin sulfonates, used as crystallization templates;

[0058] B. A hybrid conductive agent composed of graphene oxide and carbon nanotubes, used as a conductive network builder;

[0059] C. A mixture of modified humic acid and boron-containing compounds, used as an interfacial film-forming modifier;

[0060] The additive is used to inhibit the sulfation of the negative electrode active material, improve conductivity, and reduce hydrogen evolution side reactions.

[0061] The sulfonated modified sodium lignin sulfonate has sulfonic acid groups and carboxyl groups introduced into its molecular chain through a sulfonation methylation reaction.

[0062] In the hybrid conductive agent, the mass ratio of graphene oxide to carbon nanotubes is 1:10, the diameter of the graphene oxide sheets is 0.5-20 μm, and the carbon nanotubes are short-cut multi-walled carbon nanotubes with a length of 1-20 μm.

[0063] The humic acid is purified and oxidized, and its carboxyl content is 5.5 mmol / g; the boron-containing compound is boric acid.

[0064] The mass ratio of humic acid to boric acid is 1:5.

[0065] A method for preparing the lead-acid battery negative electrode additive includes the following steps:

[0066] (1) Sodium lignosulfonate was dissolved in an alkaline aqueous solution and reacted with a sulfonylmethylating agent under heating and stirring conditions to obtain sulfonated modified lignosulfonate, which was used as component A;

[0067] (2) The dispersion of graphene oxide and the dispersion of carbon nanotubes are mixed, and the mixture is subjected to ultrasonic treatment and drying to obtain a hybrid conductive agent composed of graphene oxide and carbon nanotubes, which is used as component B.

[0068] (3) The humic acid is acid washed and purified to remove ash and metal ion impurities, and then oxidized to increase the carboxyl content to obtain modified humic acid. The modified humic acid is physically mixed with boric acid powder to obtain a uniform interfacial film-forming regulator, which is used as component C.

[0069] (4) Mix component A obtained in step (1), component B obtained in step (2), and component C obtained in step (3) evenly to obtain the final product.

[0070] In step (1), the sulfonylating agent is formaldehyde and sodium bisulfite.

[0071] In step (3), the oxidant used in the oxidation treatment is nitric acid.

[0072] A lead-acid battery negative electrode paste comprises lead powder, sulfuric acid, water, and the aforementioned lead-acid battery negative electrode additive.

[0073] The mass ratio of lead powder, sulfuric acid, and water is 100:9:12.

[0074] Based on the mass of lead powder, the total amount of the additive composition is 1.0 wt%; wherein, the amount of component A is 0.4 wt%, the amount of component B is 0.02 wt%, and the amount of component C is 0.4 wt%.

[0075] Example 3

[0076] A lead-acid battery negative electrode additive, composed of the following components:

[0077] A. Sulfonated modified lignin sulfonates, used as crystallization templates;

[0078] B. A hybrid conductive agent composed of graphene oxide and carbon nanotubes, used as a conductive network builder;

[0079] C. A mixture of modified humic acid and boron-containing compounds, used as an interfacial film-forming modifier;

[0080] The additive is used to inhibit the sulfation of the negative electrode active material, improve conductivity, and reduce hydrogen evolution side reactions.

[0081] The sulfonated modified sodium lignin sulfonate has sulfonic acid groups and carboxyl groups introduced into its molecular chain through a sulfonation methylation reaction.

[0082] In the hybrid conductive agent, the mass ratio of graphene oxide to carbon nanotubes is 10:1, the diameter of the graphene oxide sheets is 0.5-20 μm, and the carbon nanotubes are short-cut multi-walled carbon nanotubes with a length of 1-20 μm.

[0083] The humic acid is purified and oxidized, and its carboxyl content is 5.5 mmol / g; the boron-containing compound is boric acid.

[0084] The mass ratio of humic acid to boric acid is 5:1.

[0085] A method for preparing the lead-acid battery negative electrode additive includes the following steps:

[0086] (1) Sodium lignosulfonate was dissolved in an alkaline aqueous solution and reacted with a sulfonylmethylating agent under heating and stirring conditions to obtain sulfonated modified lignosulfonate, which was used as component A;

[0087] (2) The dispersion of graphene oxide and the dispersion of carbon nanotubes are mixed, and the mixture is subjected to ultrasonic treatment and drying to obtain a hybrid conductive agent composed of graphene oxide and carbon nanotubes, which is used as component B.

[0088] (3) The humic acid is acid washed and purified to remove ash and metal ion impurities, and then oxidized to increase the carboxyl content to obtain modified humic acid. The modified humic acid is physically mixed with boric acid powder to obtain a uniform interfacial film-forming regulator, which is used as component C.

[0089] (4) Mix component A obtained in step (1), component B obtained in step (2), and component C obtained in step (3) evenly to obtain the final product.

[0090] In step (1), the sulfonylating agent is formaldehyde and sodium sulfite.

[0091] In step (3), the oxidant used in the oxidation treatment is potassium permanganate.

[0092] A lead-acid battery negative electrode paste comprises lead powder, sulfuric acid, water, and the aforementioned lead-acid battery negative electrode additive.

[0093] The mass ratio of lead powder, sulfuric acid, and water is 100:11:14.

[0094] Based on the mass of lead powder, the total amount of the additive composition is 5.0 wt%; wherein, the amount of component A is 2.0 wt%, the amount of component B is 1.0 wt%, and the amount of component C is 2.0 wt%.

[0095] Example 4

[0096] A lead-acid battery negative electrode additive, composed of the following components:

[0097] A. Sulfonated modified lignin sulfonates, used as crystallization templates;

[0098] B. A hybrid conductive agent composed of graphene oxide and carbon nanotubes, used as a conductive network builder;

[0099] C. A mixture of modified humic acid and boron-containing compounds, used as an interfacial film-forming modifier;

[0100] The additive is used to inhibit the sulfation of the negative electrode active material, improve conductivity, and reduce hydrogen evolution side reactions.

[0101] The sulfonated modified sodium lignin sulfonate has sulfonic acid groups and carboxyl groups introduced into its molecular chain through a sulfonation methylation reaction.

[0102] In the hybrid conductive agent, the mass ratio of graphene oxide to carbon nanotubes is 3:1, the diameter of the graphene oxide sheets is 0.5-20 μm, and the carbon nanotubes are short-cut multi-walled carbon nanotubes with a length of 1-20 μm.

[0103] The humic acid is purified and oxidized, and its carboxyl content is 5.5 mmol / g; the boron-containing compound is boric acid.

[0104] The mass ratio of humic acid to boric acid is 2:1.

[0105] A method for preparing the lead-acid battery negative electrode additive includes the following steps:

[0106] (1) Sodium lignosulfonate was dissolved in an alkaline aqueous solution and reacted with a sulfonylmethylating agent under heating and stirring conditions to obtain sulfonated modified lignosulfonate, which was used as component A;

[0107] (2) The dispersion of graphene oxide and the dispersion of carbon nanotubes are mixed, and the mixture is subjected to ultrasonic treatment and drying to obtain a hybrid conductive agent composed of graphene oxide and carbon nanotubes, which is used as component B.

[0108] (3) The humic acid is acid washed and purified to remove ash and metal ion impurities, and then oxidized to increase the carboxyl content to obtain modified humic acid. The modified humic acid is physically mixed with boric acid powder to obtain a uniform interfacial film-forming regulator, which is used as component C.

[0109] (4) Mix component A obtained in step (1), component B obtained in step (2), and component C obtained in step (3) evenly to obtain the final product.

[0110] In step (1), the sulfonylating agent is formaldehyde and sodium sulfite.

[0111] In step (3), the oxidant used in the oxidation treatment is hydrogen peroxide.

[0112] A lead-acid battery negative electrode paste comprises lead powder, sulfuric acid, water, and the aforementioned lead-acid battery negative electrode additive.

[0113] The mass ratio of lead powder, sulfuric acid, and water is 100:10:13.

[0114] Based on the mass of lead powder, the total amount of the additive composition is 1.7 wt%; wherein, the amount of component A is 0.8 wt%, the amount of component B is 0.3 wt%, and the amount of component C is 0.6 wt%.

[0115] Comparative Example 1

[0116] Based on Example 1, no additives are added to the negative electrode lead paste; only lead powder, sulfuric acid, and water are used.

[0117] Comparative Example 2

[0118] Based on Example 1, only components B and C were added to the lead paste, but component A was not added.

[0119] Comparative Example 3

[0120] Based on Example 1, only components A and C were added to the lead paste, and component B was replaced with an equal mass of barium sulfate, while the rest remained the same as in Example 1.

[0121] Comparative Example 4

[0122] Based on Example 1, only components A and B were added to the lead paste, but component C was not added.

[0123] Comparative Example 5

[0124] Based on Example 1, component A was replaced with unmodified sodium lignosulfonate, while the rest remained the same as in Example 1.

[0125] Comparative Example 6

[0126] Based on Example 1, component B does not contain graphene oxide, but only carbon nanotubes are added, while the rest remains the same as in Example 1.

[0127] Comparative Example 7

[0128] Based on Example 1, component B does not contain carbon nanotubes, but only graphene oxide is added, while the rest remains the same as in Example 1.

[0129] Comparative Example 8

[0130] Based on Example 1, the modification of component C humic acid was omitted, and the rest remained the same as in Example 1.

[0131] Comparative Example 9

[0132] Based on Example 1, no boron-containing compound was added to component C, and the rest remained the same as in Example 1.

[0133] Performance testing:

[0134] The negative electrode lead pastes prepared in the above embodiments and comparative examples were coated onto lead-calcium alloy grids, cured, and dried to form negative electrode plates. A positive electrode plate was used as the counter electrode, and the same AGM separator was used to inject an equal amount of lead paste with a density of 1.28 g / cm³. 3 The sulfuric acid electrolyte was encapsulated into a 2V single-cell test battery, and three batteries were prepared in parallel for each formulation group.

[0135] Cycle life: The initial capacity was determined by constant current discharge according to GB / T 19638.1-2014 standard; at 25°C, a cycle life test was conducted with 100% deep discharge (1C current, cutoff voltage 1.75V / cell), and the number of cycles when the capacity decayed to 80% was recorded.

[0136] Charge acceptance: At 50% SOC, with a constant voltage of 2.40V per cell applied, the charging current value at the 10th minute is recorded as I. 10 ;

[0137] Hydrogen evolution suppression: The fully charged battery was overcharged for 24 hours at a constant voltage of 2.45V / cell, and the cumulative hydrogen evolution volume was measured by the water displacement gas collection method.

[0138] <![CDATA[Charging current I 10 (A)]]> Cycle life (times) Hydrogen evolution volume (mL) Example 1 2.5 422 34 Example 2 1.9 387 39 Example 3 2.3 403 43 Example 4 2.4 415 36 Comparative Example 1 0.8 154 121 Comparative Example 2 2.3 181 38 Comparative Example 3 1.0 253 37 Comparative Example 4 2.4 262 110 Comparative Example 5 2.0 281 52 Comparative Example 6 1.8 304 36 Comparative Example 7 2.1 317 37 Comparative Example 8 2.3 349 70 Comparative Example 9 2.5 301 105

[0139] The test results show that the embodiments, through the synergistic effect of components A, B, and C, systematically suppressed sulfation, conductivity decay, and hydrogen evolution side reactions of the negative electrode in lead-acid batteries. The comparative examples, serving as a blank control without additives, exhibited the worst performance. Comparative examples 2, 3, and 4, which included components A, B, and C respectively, showed a sharp drop in cycle life in Comparative example 2, highlighting the decisive role of component A as a "crystallization template agent" in suppressing sulfation. Comparative example 3 showed extremely low charging current, highlighting the key role of component B as a "three-dimensional conductive network" in improving charge acceptance. Comparative example 4 showed a surge in hydrogen evolution, highlighting the core role of component C as an "interfacial film-forming regulator" in suppressing side reactions. Comparative example 5, with unmodified sodium lignosulfonate, had poor dispersibility and template effects, resulting in decreased cycle and charging performance. Comparative examples 6 and 7, with only component B added, showed decreased charging and cycle performance. Comparative example 8, using unmodified humic acid, showed limited suppression of hydrogen evolution and improvement in cycle life. Comparative example 9, without the addition of boron-containing compounds, showed extremely high hydrogen evolution and shortened cycle life.

[0140] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A lead paste for the negative electrode of a lead-acid battery, characterized in that, It contains lead powder, sulfuric acid, water, and a lead-acid battery negative electrode additive, wherein the lead-acid battery negative electrode additive is composed of the following components: A. Sulfonated modified lignin sulfonate, as a crystallization template agent, wherein the sulfonated modified lignin sulfonate has sulfonic acid groups and carboxyl groups introduced into its molecular chain through a sulfonylation reaction; B. A hybrid conductive agent composed of graphene oxide and carbon nanotubes, used as a conductive network builder, wherein the mass ratio of graphene oxide to carbon nanotubes in the hybrid conductive agent is 1:10 to 10:1, the sheet diameter of the graphene oxide is 0.5-20 μm, and the carbon nanotubes are short-cut multi-walled carbon nanotubes with a length of 1-20 μm; C. A mixture of modified humic acid and boron-containing compound, used as an interfacial film-forming regulator, wherein the humic acid is purified and oxidized humic acid with a carboxyl content greater than 5.0 mmol / g; the boron-containing compound is boric acid, and the mass ratio of humic acid to boric acid is 1:5 to 5:

1. The mass ratio of component A, component B and component C is (0.05-2.0):(0.01-1.0):(0.05-2.0).

2. The lead paste for the negative electrode of a lead-acid battery according to claim 1, characterized in that, Based on the mass of lead powder, the amount of the lead-acid battery negative electrode additive added is 0.1-5.0 wt%; wherein, the amount of component A added is 0.05-2.0 wt%, the amount of component B added is 0.01-1.0 wt%, and the amount of component C added is 0.05-2.0 wt%.

3. A method for preparing lead paste for the negative electrode of a lead-acid battery as described in claim 1, characterized in that, Includes the following steps: (1) Sodium lignosulfonate was dissolved in an alkaline aqueous solution and reacted with a sulfonylmethylating agent under heating and stirring conditions to obtain sulfonated modified lignosulfonate, which was used as component A; (2) The dispersion of graphene oxide and the dispersion of carbon nanotubes are mixed, and the mixture is subjected to ultrasonic treatment and drying to obtain a hybrid conductive agent composed of graphene oxide and carbon nanotubes, which is used as component B. (3) The humic acid is acid washed and purified to remove ash and metal ion impurities, and then oxidized to increase the carboxyl content to obtain modified humic acid. The modified humic acid is physically mixed with boric acid powder to obtain a uniform interfacial film-forming regulator, which is used as component C. (4) Mix component A obtained in step (1), component B obtained in step (2) and component C obtained in step (3) evenly to obtain the lead-acid battery negative electrode additive in the lead-acid battery negative electrode paste.

4. The method for preparing lead paste for the negative electrode of a lead-acid battery according to claim 3, characterized in that, In step (1), the sulfonylating agent is formaldehyde and sodium sulfite or formaldehyde and sodium bisulfite.

5. The method for preparing lead paste for the negative electrode of a lead-acid battery according to claim 3, characterized in that, In step (3), the oxidant used in the oxidation treatment is one of hydrogen peroxide, nitric acid or potassium permanganate.