Negative electrode additive of lead-acid battery as well as preparation method and application of negative electrode additive

Abstract

The invention relates to a lead-acid battery negative electrode additive as well as a preparation method and application thereof, and belongs to the technical field of lead-acid storage batteries. The additive consists of sulfonated modified lignosulfonate (component A), a graphene oxide-carbon nanotube hybrid conductive agent (component B) and a mixture of modified humic acid and boric acid (component C) which are respectively used as a crystallization template agent, a conductive network construction agent and an interface film forming regulator. During preparation, a component A is prepared through a sulfomethylation reaction, a component B is prepared through ultrasonic mixing of graphene oxide and a carbon nanotube dispersion liquid, a component C is prepared after humic acid is subjected to acid pickling purification and oxidation treatment and then mixed with boric acid, and finally the three components are mixed to obtain a finished product. The additive is added into the negative electrode lead paste, can inhibit negative electrode sulfation, improve electrode conductivity, reduce hydrogen evolution side reaction and prolong the cycle life and charge-discharge efficiency of the battery, and is suitable for production of various lead-acid batteries.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lead-acid batteries, and relates to a lead-acid battery negative electrode additive as well as a preparation method and application thereof. BACKGROUND

[0002] As one of the secondary batteries with the longest development history, the lead-acid battery occupies an irreplaceable position in many fields such as new energy storage, electric vehicles, emergency backup power supply and the like due to its low cost, mature preparation process, excellent high-current discharge performance and high safety and reliability. The core working principle thereof is based on the electrochemical reaction of positive and negative active materials and sulfuric acid electrolyte to realize charge and discharge cycles. The reaction activity and structural stability of the negative lead paste directly determine the capacity characteristics and cycle life of the battery, and therefore, optimizing the negative electrode performance is a key direction for improving the comprehensive quality of the lead-acid battery.

[0003] However, in the long-term charge and discharge cycle process, the lead-acid battery negative electrode is prone to multiple performance degradation problems, which seriously restricts its service life. The primary problem is irreversible sulfation. The discharged lead sulfate is easy to form coarse and dense crystals attached to the negative electrode surface, which is difficult to be reduced to sponge lead during charging. At the same time, the negative active material is easy to fall off and pulverize during the cycle process, leading to degradation of the internal conductive network and significant increase in electron transport resistance. In addition, the hydrogen evolution side reaction on the negative electrode surface continuously consumes the electrolyte and active material, not only reducing the charging efficiency, but also possibly causing battery swelling and other safety hazards.

[0004] To alleviate the above problems, the existing technology mostly adopts the method of adding functional additives to optimize the negative electrode performance. Traditional swelling agents such as lignin substances can inhibit the growth of lead sulfate crystals through steric hindrance effect, but they are easy to affect the electrode conductivity due to insufficient dispersibility. Although pure carbon-based conductive agents (such as graphite and carbon black) can improve the conductive network, they have no obvious inhibitory effect on sulfation and hydrogen evolution side reaction. Most of the current additives have the limitation of single function, and it is difficult to simultaneously solve the multiple degradation problems of the negative electrode. Some composite additives also have performance antagonism due to poor component matching, and cannot achieve synergistic effect. Therefore, it is an urgent need in the industry to develop high-efficiency negative electrode additives with multiple functions. SUMMARY

[0005] The purpose of the present application is to provide a lead-acid battery negative electrode additive as well as a preparation method and application thereof. The additive components A, B and C are respectively aimed at sulfation, conductivity decay and hydrogen evolution side reaction, and form a synergistic enhancement effect in the negative electrode, thereby improving the cycle life, charging acceptance ability and overcharge resistance of the battery.

[0006] The purpose of the present application can be achieved by the following technical solutions. A lead-acid battery negative electrode additive is composed of the following components: A. Sulfonated modified lignin sulfonate as a crystallization template agent; B. Hybrid conductive agent composed of graphene oxide and carbon nanotubes as a conductive network construction agent; C. A mixture of modified humic acid and boron-containing compounds as an interface film-forming regulator; The mass ratio of component A, component B and component C is (0.05-2.0):(0.01-1.0):(0.05-2.0). The additive is used to inhibit the sulfation of negative active material, improve the conductivity and reduce the hydrogen evolution side reaction.

[0007] As a preferred technical solution of the present application, the sulfonated modified sodium lignin sulfonate has sulfonic acid groups and carboxyl groups introduced on the molecular chain through sulfomethylation.

[0008] In the present application, the sodium lignin sulfonate is sulfomethylated and modified, and additional hydrophilic sulfonic acid groups (-SO3H) and carboxyl groups (-COOH) are introduced on the benzene ring of the lignin molecular chain. The introduction of strong hydrophilic groups greatly improves the dispersibility of the lignin in the sulfuric acid electrolyte, enabling it to be more uniformly adsorbed on the surface of lead and PbSO4 crystal nuclei. The uniformly adsorbed modified lignin molecules form a more compact and uniform organic molecular film on the surface of the negative electrode. This film acts as a "template" to effectively space the excessive growth of PbSO4 crystals, guiding the deposition of PbSO4 in the form of fine, loose and porous microcrystals. This form of PbSO4 is easily reduced to active sponge-like lead during charging, thereby fundamentally inhibiting the occurrence of irreversible sulfation. After modification, the molecular weight distribution is narrower and the performance is more stable, avoiding the inconsistent battery performance caused by component fluctuations in traditional products.

[0009] Graphene oxide has a two-dimensional sheet structure, and carbon nanotubes have a one-dimensional fiber structure. After hybridization by ultrasonic and other processes, carbon nanotubes can be inserted and overlapped between the graphene oxide sheets, forming a stable, three-dimensional interconnected conductive framework. This framework is embedded in the lead active material, and even if the active material changes in volume, the electronic path remains unobstructed, reducing the electrode resistance and polarization. Moreover, GO and CNTs both have a large specific surface area and abundant surface functional groups. These surface sites provide a large number of uniformly distributed nucleation centers for the deposition / dissolution of Pb and PbSO4. This is conducive to the uniform performance of electrochemical reactions within the electrode, avoiding local current concentration and limited material transport, further facilitating the formation of a refined active material structure. The nanocarbon network also has excellent mechanical strength, supporting and restraining the surrounding lead active material, effectively inhibiting the softening and shedding of the active material during the cycle process, and maintaining the integrity of the electrode structure.

[0010] Humic acid is purified by acid washing and oxidation. High purity carboxyl-rich humic acid can complex with Pb 2+ The ions have stronger complexing ability and can be adsorbed on the surface of PbSO4 crystal during the growth of the crystal, thereby mildly inhibiting the excessive growth of the crystal and not excessively hindering the electrochemical reduction reaction of the charging process. In the sulfuric acid environment of the negative electrode, boric acid participates in the formation of an extremely thin lead borate (Pb3(BO3)2) or boron-containing complex interface film. The film can stabilize the pH value of the electrode / electrolyte interface micro area, buffer the H + The concentration fluctuates sharply, thereby increasing the overpotential of the hydrogen evolution reaction and inhibiting the hydrogen evolution side reaction. The dense film can also cover the surface of the active material, reduce the direct contact of the active material with the electrolyte, and slow down corrosion and softening.

[0011] As a preferred technical solution of the present application, in the hybrid conductive agent, the mass ratio of graphene oxide to carbon nanotube is 1:10 to 10:1, the flake diameter of the graphene oxide is 0.5-20 μm, and the carbon nanotube is a short-cut multi-walled carbon nanotube with a length of 1-20 μm.

[0012] As a preferred technical solution of the present application, the humic acid is humic acid treated by purification and oxidation, and the carboxyl content is greater than 5.0 mmol / g; and the boron-containing compound is boric acid.

[0013] As a preferred technical solution of the present application, the mass ratio of the humic acid to the boric acid is 1:5 to 5:1.

[0014] Further, a preparation method of the lead-acid battery negative electrode additive includes the following steps: (1) Dissolving sodium lignosulfonate in an alkaline aqueous solution, and reacting with a sulfomethylation reagent under heating and stirring to obtain sulfonated modified lignosulfonate as component A; (2) Mixing a dispersion liquid of graphene oxide and a dispersion liquid of carbon nanotubes, and then performing ultrasonic treatment and drying to obtain a hybrid conductive agent composed of graphene oxide and carbon nanotubes as component B; (3) Purifying humic acid by acid washing to remove ash and metal ion impurities, and then performing oxidation treatment to increase the carboxyl content to obtain modified humic acid, and physically mixing the modified humic acid with boric acid powder to obtain a uniform interface film forming regulator as component C; (4) Mixing the component A prepared in step (1), the component B prepared in step (2), and the component C prepared in step (3) uniformly to obtain the additive.

[0015] As a preferred technical solution of the present application, in step (1), the sulfomethylation reagent is formaldehyde and sodium sulfite or formaldehyde and sodium bisulfite.

[0016] As a preferred technical solution of the present application, in step (3), the oxidizing agent used in the oxidation treatment is one of hydrogen peroxide, nitric acid or potassium permanganate.

[0017] Further, a lead acid battery negative lead paste comprises lead powder, sulfuric acid, water and the lead acid battery negative electrode additive as described.

[0018] As a preferred technical solution of the present application, the total additive amount of the additive composition is 0.1-5.0 wt% based on the mass of the lead powder; wherein the additive amount of component A is 0.05-2.0 wt%, the additive amount of component B is 0.01-1.0 wt%, and the additive amount of component C is 0.05-2.0 wt%.

[0019] The beneficial effects of the present application are: (1) The present application combines the specific modified lignin derivative, the nano-carbon hybrid conductive agent and the humic acid-boric acid interface modifier to form a synergistic system of "template regulation-conductive enhancement-interface protection". The system can simultaneously solve the core failure problems of the lead acid battery negative electrode such as sulfation, conductive network degradation and hydrogen evolution side reaction from three aspects of crystallography, electricity and interface chemistry, and realizes the systematic and comprehensive improvement of the battery performance.

[0020] (2) Through sulfomethylation modification, the hydrophilicity and adsorption uniformity of component A (lignin sulfonate) are greatly improved, and a more dense and uniform molecular template layer can be formed on the negative electrode surface. The template layer can effectively space and guide PbSO4 to precipitate in the form of small, loose and porous microcrystals instead of traditional large and dense crystals, thereby significantly improving the reversibility of PbSO4 during the charging process, fundamentally and effectively inhibiting the occurrence of irreversible sulfation, and prolonging the deep cycle life of the battery.

[0021] (3) The hybrid system of graphene oxide (GO) and carbon nanotubes (CNTs) used in component B can form a three-dimensional interconnected nano-conductive skeleton. The skeleton is embedded in the active material to provide an ultra-high electronic conductive path, greatly reducing the electrode resistance and polarization, and improving the charging acceptance capacity and large current discharge performance. At the same time, the network has excellent mechanical strength, which can effectively support and bind the active material, inhibit the softening and shedding of the active material during the cycle process, and maintain the integrity of the electrode structure.

[0022] (4) The boric acid in component C can participate in the formation of an extremely thin boric acid salt / complex film at the negative electrode interface. The film has unique ion selectivity, can stabilize the interface pH, buffer the H + concentration fluctuation, and significantly hinder the diffusion of 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

[0023] 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.

[0024] Example 1 A lead-acid battery negative electrode additive, composed of the following components: A. Sulfonated modified lignin sulfonates, used as crystallization templates; B. A hybrid conductive agent composed of graphene oxide and carbon nanotubes, used as a conductive network builder; C. A mixture of modified humic acid and boron-containing compounds, used as an interfacial film-forming modifier; The additive is used to inhibit the sulfation of the negative electrode active material, improve conductivity, and reduce hydrogen evolution side reactions.

[0025] The sulfonated modified sodium lignin sulfonate has sulfonic acid groups and carboxyl groups introduced into its molecular chain through a sulfonation methylation reaction.

[0026] 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.

[0027] The humic acid is purified and oxidized, and its carboxyl content is 5.5 mmol / g; the boron-containing compound is boric acid.

[0028] The mass ratio of humic acid to boric acid is 2:1.

[0029] A method for preparing the lead-acid battery negative electrode additive 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 subjected to acid washing purification to remove ash and metal ion impurities, and then subjected to oxidation treatment to increase the content of carboxyl groups to obtain modified humic acid. The modified humic acid is physically mixed with boric acid powder to obtain a uniform interface film forming regulator, which is component C; (4) The component A prepared in step (1), the component B prepared in step (2) and the component C prepared in step (3) are uniformly mixed to obtain the product.

[0030] In step (1), the sulfomethylating agent is formaldehyde and sodium sulfite.

[0031] In step (3), the oxidizing agent used in the oxidation treatment is hydrogen peroxide.

[0032] A lead acid battery negative electrode lead paste, comprising lead powder, sulfuric acid, water and the lead acid battery negative electrode additive.

[0033] The mass ratio of the lead powder, sulfuric acid and water is 100:10:13.

[0034] The total additive amount of the additive composition is 1.7 wt% based on the mass of the lead powder; wherein the additive amount of component A is 0.8 wt%, the additive amount of component B is 0.3 wt% and the additive amount of component C is 0.6 wt%.

[0035] Example 2 A lead acid battery negative electrode additive, consisting of the following components: A. Sulfonated modified lignin sulfonate as a crystallization template agent; B. Hybrid conductive agent composed of graphene oxide and carbon nanotube as a conductive network builder; C. Mixture of modified humic acid and boron-containing compound as an interface film forming regulator; The additive is used to inhibit negative active material sulfation, improve conductivity and reduce hydrogen evolution side reaction.

[0036] The sulfonated modified lignin sodium sulfonate has sulfonic acid groups and carboxyl groups introduced on the molecular chain through sulfomethylation reaction.

[0037] In the hybrid conductive agent, the mass ratio of graphene oxide to carbon nanotube is 1:10, the flake diameter of the graphene oxide is 0.5-20 μm, and the carbon nanotube is a short-cut multi-walled carbon nanotube with a length of 1-20 μm.

[0038] The humic acid is a purified and oxidized humic acid with a carboxyl content of 5.5 mmol / g; and the boron-containing compound is boric acid.

[0039] The mass ratio of the humic acid to boric acid is 1:5.

[0040] A method for preparing the additive for negative electrode of lead-acid battery, comprising the following steps: (1) dissolving sodium lignosulfonate in an alkaline aqueous solution, and reacting with a sulfomethylation reagent under heating and stirring to obtain a sulfonated modified lignosulfonate as component A; (2) mixing a dispersion liquid of graphene oxide and a dispersion liquid of carbon nanotubes, and obtaining a hybrid conductive agent composed of graphene oxide and carbon nanotubes through ultrasonic treatment and drying as component B; (3) purifying humic acid through acid washing to remove ash and metal ion impurities, and then increasing the content of carboxyl groups through oxidation treatment to obtain modified humic acid, and physically mixing the modified humic acid with boric acid powder to obtain a uniform interface film forming regulator as component C; (4) mixing the component A prepared in step (1), the component B prepared in step (2) and the component C prepared in step (3) uniformly to obtain the additive.

[0041] In step (1), the sulfomethylation reagent is formaldehyde and sodium bisulfite.

[0042] In step (3), the oxidizing agent used in the oxidation treatment is nitric acid.

[0043] A lead paste for negative electrode of lead-acid battery, comprising lead powder, sulfuric acid, water and the additive for negative electrode of lead-acid battery.

[0044] The mass ratio of lead powder, sulfuric acid and water is 100:9:12.

[0045] The total amount of the additive composition is 1.0 wt% based on the mass of lead powder; 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%.

[0046] Example 3 An additive for negative electrode of lead-acid battery, comprising the following components: A. a sulfonated modified lignosulfonate as a crystallization template agent; B. a hybrid conductive agent composed of graphene oxide and carbon nanotubes as a conductive network construction agent; C. a mixture of modified humic acid and a boron-containing compound as an interface film forming regulator; The additive is used to inhibit the sulfation of negative active material, improve the conductivity and reduce the hydrogen evolution side reaction.

[0047] The sulfonated modified sodium lignosulfonate has sulfonic acid groups and carboxyl groups introduced on the molecular chain through sulfomethylation reaction.

[0048] The mass ratio of the graphene oxide to the carbon nanotube in the hybrid conductive agent is 10:1, the flake diameter of the graphene oxide is 0.5-20 μm, and the carbon nanotube is a short-cut multi-walled carbon nanotube with a length of 1-20 μm.

[0049] The humic acid is a purified and oxidized humic acid with a carboxyl content of 5.5 mmol / g, and the boron-containing compound is boric acid.

[0050] The mass ratio of the humic acid to the boric acid is 5:1.

[0051] A preparation method of the lead-acid battery negative electrode additive comprises the following steps: (1) dissolving sodium lignosulfonate in an alkaline aqueous solution, and reacting with a sulfomethylation reagent under heating and stirring to obtain a sulfonated modified lignosulfonate as component A; (2) mixing a dispersion liquid of graphene oxide and a dispersion liquid of carbon nanotubes, and obtaining a hybrid conductive agent composed of graphene oxide and carbon nanotubes through ultrasonic treatment and drying as component B; (3) purifying humic acid through acid washing to remove ash and metal ion impurities, and then performing oxidation treatment to increase the carboxyl content to obtain modified humic acid, and physically mixing the modified humic acid with boric acid powder to obtain a uniform interface film modifier as component C; (4) mixing the component A prepared in step (1), the component B prepared in step (2), and the component C prepared in step (3) uniformly to obtain the additive.

[0052] In step (1), the sulfomethylation reagent is formaldehyde and sodium sulfite.

[0053] In step (3), the oxidizing agent used for the oxidation treatment is potassium permanganate.

[0054] A lead-acid battery negative electrode lead paste comprises lead powder, sulfuric acid, water, and the lead-acid battery negative electrode additive.

[0055] The mass ratio of the lead powder, sulfuric acid, and water is 100:11:14.

[0056] The total addition amount of the additive composition is 5.0 wt% based on the mass of the lead powder; wherein the addition amount of component A is 2.0 wt%, the addition amount of component B is 1.0 wt%, and the addition amount of component C is 2.0 wt%.

[0057] Example 4 A lead-acid battery negative electrode additive comprises the following components: A. sulfonated modified lignosulfonate as a crystallization template agent; B. Hybrid conductive agent composed of graphene oxide and carbon nanotube as conductive network building agent; C. Mixture of modified humic acid and boron-containing compound as interface film forming regulator; The additive is used for inhibiting negative active material sulfation, improving conductivity and reducing hydrogen evolution side reaction.

[0058] The sulfonated modified sodium lignosulfonate has sulfonic acid group and carboxyl group introduced on the molecular chain through sulfomethylation reaction.

[0059] In the hybrid conductive agent, the mass ratio of graphene oxide to carbon nanotube is 3:1, the flake diameter of the graphene oxide is 0.5-20 μm, and the carbon nanotube is short-cut multi-walled carbon nanotube with a length of 1-20 μm.

[0060] The humic acid is humic acid after purification and oxidation treatment, and the carboxyl content is 5.5 mmol / g; and the boron-containing compound is boric acid.

[0061] The mass ratio of the humic acid to boric acid is 2:1.

[0062] A preparation method of the additive for negative electrode of lead-acid battery comprises the following steps: (1) dissolving sodium lignosulfonate in alkaline aqueous solution, and reacting with sulfomethylation reagent under heating and stirring to obtain sulfonated modified lignosulfonate as component A; (2) mixing dispersion liquid of graphene oxide and dispersion liquid of carbon nanotube, and obtaining hybrid conductive agent composed of graphene oxide and carbon nanotube through ultrasonic treatment and drying as component B; (3) purifying humic acid through acid washing to remove ash and metal ion impurities, and then increasing carboxyl content through oxidation treatment to obtain modified humic acid, and physically mixing the modified humic acid with boric acid powder to obtain uniform interface film forming regulator as component C; (4) mixing component A prepared in step (1), component B prepared in step (2) and component C prepared in step (3) uniformly to obtain the additive for negative electrode of lead-acid battery.

[0063] In step (1), the sulfomethylation reagent is formaldehyde and sodium sulfite.

[0064] In step (3), the oxidizing agent used for oxidation treatment is hydrogen peroxide.

[0065] A lead paste for negative electrode of lead-acid battery comprises lead powder, sulfuric acid, water and the additive for negative electrode of lead-acid battery.

[0066] The mass ratio of lead powder, sulfuric acid and water is 100:10:13.

[0067] The total additive amount of the additive composition is 1.7 wt% based on the mass of the lead powder; wherein the additive amount of component A is 0.8 wt%, the additive amount of component B is 0.3 wt%, and the additive amount of component C is 0.6 wt%.

[0068] Comparative Example 1 On the basis of Example 1, no additive is added to the negative lead paste, only lead powder, sulfuric acid, and water.

[0069] Comparative Example 2 On the basis of Example 1, only components B and C are added to the lead paste, and no component A is added.

[0070] Comparative Example 3 On the basis of Example 1, only components A and C are added to the lead paste, and component B is replaced by an equal mass of barium sulfate, and the rest is consistent with Example 1.

[0071] Comparative Example 4 On the basis of Example 1, only components A and B are added to the lead paste, and no component C is added.

[0072] Comparative Example 5 On the basis of Example 1, component A is replaced by unmodified sodium lignosulfonate, and the rest is consistent with Example 1.

[0073] Comparative Example 6 On the basis of Example 1, component B does not add graphene oxide, only carbon nanotubes are added, and the rest is consistent with Example 1.

[0074] Comparative Example 7 On the basis of Example 1, component B does not add carbon nanotubes, only graphene oxide is added, and the rest is consistent with Example 1.

[0075] Comparative Example 8 On the basis of Example 1, the modification of component C humic acid is omitted, and the rest is consistent with Example 1.

[0076] Comparative Example 9 On the basis of Example 1, no boron-containing compound is added to component C, and the rest is consistent with Example 1.

[0077] Performance test: The negative lead paste prepared in each of the above examples and comparative examples is coated on a lead-calcium alloy grid, cured and dried to form a negative plate; using one positive plate as a counter electrode, using the same AGM separator, injecting an equal amount of sulfuric acid electrolyte with a density of 1.28 g / cm 3 The above examples and comparative examples are packaged into 2V single-cell test batteries, and each formula group is prepared in parallel for 3 batteries; Cycle life: initial capacity was determined according to GB / T 19638.1-2014 standard constant current discharge; cycle life test was carried out at 25°C with 100% depth of discharge (1C current, cut-off voltage 1.75V / cell), and the cycle number was recorded when the capacity decayed to 80%; Charge acceptance: at 50% SOC, constant voltage of 2.40V / cell was applied, and the charge current value at the 10th minute was recorded as I 10 ; Hydrogen evolution inhibition: the fully charged battery was overcharged at 2.45V / cell constant voltage for 24 hours, and the cumulative hydrogen volume was measured by drainage gas collection method.

[0078] Charging current I 10 (A)] Cycle life (times) Volume of hydrogen evolution (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

[0079] From the test results, it can be seen that the embodiment realizes the systematic inhibition of lead-acid battery negative electrode sulfation, conductivity decay and hydrogen evolution side reaction through the synergistic effect of components A, B and C. The comparative example, as a blank control without adding additives, has the worst performance; Comparative Example 2, Comparative Example 3 and Comparative Example 4 respectively add components A, B and C, Comparative Example 2 has a sharp decline in cycle life, highlighting the decisive role of component A as a "crystallization template agent" in inhibiting sulfation, Comparative Example 3 has extremely low charge current, highlighting the key role of component B as a "three-dimensional conductive network" in improving charge acceptance, and Comparative Example 4 has a sharp increase in hydrogen evolution, highlighting the core role of component C as an "interface film forming regulator" in inhibiting side reactions; Comparative Example 5 does not modify sodium lignosulfonate, and has poor dispersibility and template effect, and both cycle and charge performance are decreased; Comparative Example 6 and Comparative Example 7 only add a single component of component B, and the charge performance and cycle performance are decreased; Comparative Example 8 uses unmodified humic acid to inhibit hydrogen evolution and improve life, which is limited; Comparative Example 9 does not add boron-containing compounds, and the hydrogen evolution is extremely high, and the life is shortened.

[0080] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present application are still within the scope of the technical solution of the present application.

Claims

1. A lead-acid battery negative electrode additive characterized in that, Comprise the following components: A. sulfonated modified lignin sulfonate as a crystallization template agent; B. hybrid conductive agent composed of graphene oxide and carbon nanotube as a conductive network builder; C. mixture of modified humic acid and boron-containing compound as an interface film forming regulator; Wherein, 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-acid battery negative additive of claim 1, wherein, The sulfonated modified sodium lignin sulfonate has sulfonic acid group and carboxyl group introduced on the molecular chain by sulfomethylation reaction.

3. The lead-acid battery negative additive of claim 1, wherein, In the hybrid conductive agent, the mass ratio of graphene oxide to carbon nanotube is 1:10 to 10:1, the flake diameter of the graphene oxide is 0.5-20 μm, and the carbon nanotube is short-cut multi-walled carbon nanotube with a length of 1-20 μm.

4. The lead-acid battery negative additive of claim 1, wherein, The humic acid is purified and oxidized humic acid with a carboxyl content greater than 5.0 mmol / g; and the boron-containing compound is boric acid.

5. The lead-acid battery negative additive of claim 4, wherein, The mass ratio of the humic acid to boric acid is 1:5 to 5:

1.

6. A method of preparing a negative additive for a lead-acid battery as claimed in any one of claims 1 to 5, characterised in that, Comprise the following steps: (1) dissolving sodium lignin sulfonate in an alkaline aqueous solution, and reacting with a sulfomethylation reagent under heating and stirring to obtain a sulfonated modified lignin sulfonate as component A; (2) mixing a dispersion of graphene oxide and a dispersion of carbon nanotube, and obtaining a hybrid conductive agent composed of graphene oxide and carbon nanotube by ultrasonic treatment and drying as component B; (3) purifying humic acid by acid washing to remove ash and metal ion impurities, and then oxidizing to increase the carboxyl content to obtain modified humic acid, and physically mixing the modified humic acid with boric acid powder to obtain a uniform interface film forming regulator as component C; (4) mixing component A prepared in step (1), component B prepared in step (2) and component C prepared in step (3) uniformly to obtain the additive.

7. The method of claim 6, wherein the additive is prepared by mixing the lead oxide and the carbon black in a ratio of 1 : 1 to 1 :

3. In step (1), the sulfomethylation reagent is formaldehyde and sodium sulfite or formaldehyde and sodium bisulfite.

8. The method of claim 6, wherein the additive is prepared by the steps of: In step (3), the oxidizing agent used for oxidation is one of hydrogen peroxide, nitric acid or potassium permanganate.

9. A lead acid battery negative lead paste characterized by, Lead powder, sulfuric acid, water, and a lead-acid battery negative electrode additive as claimed in any one of claims 1-5.

10. The lead acid battery negative lead paste of claim 9, wherein, The addition amount of the lead-acid battery negative electrode additive is 0.1-5.0 wt% based on the mass of lead powder; wherein the addition amount of component A is 0.05-2.0 wt%, the addition amount of component B is 0.01-1.0 wt%, and the addition amount of component C is 0.05-2.0 wt%.