Composite expander and its use in negative plates of lead-acid batteries

Abstract

This invention discloses a composite expander and its application in the negative electrode plate of a lead-acid battery, belonging to the field of lead-acid battery technology. Ammonium persulfate is used as an oxidant, added to an ethanol solution mixture of pyrrole / aniline monomers (conductive monomers), sodium lignosulfonate, and acrylamide, causing an oxidation reaction. Subsequently, it is calcined at high temperature under a nitrogen or argon atmosphere to obtain a compound in which a composite polymer encapsulates sodium lignosulfonate. After calcination under a protective gas atmosphere, some of the composite material carbonizes, forming a carbon-encapsulated sodium lignosulfonate composite expander. The carbon-encapsulated composite expander can slow down the consumption of sodium lignosulfonate. Using the composite expander results in a higher hydrogen evolution overpotential and more durable low-temperature performance. The application of the composite expander in the negative electrode plate of a lead-acid battery improves the sulfation problem of the negative electrode plate operating under high efficiency partial charge conditions, extending the cycle life of the lead-acid battery.

Description

Technical Field

[0001] This invention belongs to the field of lead-acid battery technology, specifically relating to a composite expanding agent and its application in the negative electrode plate of a lead-acid battery. Background Technology

[0002] Lead-acid batteries, with their advantages of low cost and abundant, readily available raw materials, hold a crucial position in chemical power sources, accounting for approximately half of the market share. With the continuous development of new energy storage and new energy power markets, higher demands are being placed on battery charge acceptance and cycle life. Secondary batteries are required to exhibit long cycle life at high-rate partial charge state of charge (HRPSoC). However, in traditional lead-acid batteries, irreversible coarse sulfation occurs on the negative electrode during charging and discharging, preventing ions and electrons from reacting and further exacerbating electrode degradation. To address this, additives are being added to the negative electrode to improve its conductivity and capacitance, significantly limiting lead sulfate formation and suppressing irreversible sulfation.

[0003] To improve the cycle life of lead-acid batteries under high-rate partial charge conditions, many studies have focused on adding lignin, an expansion agent, to the negative electrode. The aim is to increase the porosity of the negative electrode, thereby enhancing ion channels and suppressing the deposition of a continuous lead sulfate passivation layer during discharge. This also helps form a porous lead sulfate layer that is easily converted into sponge lead, thus improving the battery's cycle performance. However, lignin has low conductivity and a low hydrogen evolution overpotential. When added to the negative electrode of a lead-acid battery, it easily leads to water loss or even drying out during operation, limiting further improvements in cycle performance and failing to adequately meet the needs of lead-acid battery development. Summary of the Invention

[0004] The purpose of this invention is to provide a composite expanding agent and its application in the negative electrode plate of a lead-acid battery, so as to solve the problem that conventional expanding agents limit the further improvement of battery cycle performance.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A composite expanding agent comprises the following raw materials in parts by weight: 1-3 parts conductive monomer, 1-3 parts sodium lignosulfonate, 1-5 parts acrylamide, 10-40 parts anhydrous ethanol, and 3-9 parts ammonium persulfate solution.

[0007] Furthermore, the composite expanding agent is prepared by the following steps:

[0008] Conductive monomers, sodium lignosulfonate, acrylamide, and anhydrous ethanol were mixed and ultrasonicated for 30 minutes using an ultrasonic cleaner. Then, ammonium persulfate solution was added dropwise, and the mixture was allowed to stand for 12 hours to obtain a reaction solution. After filtering and cleaning the reaction solution, it was placed in a tube furnace under protective gas and calcined at 300-500℃ for 2 hours under the protective gas atmosphere. The composite expanding agent was then obtained by grinding.

[0009] Furthermore, the conductive monomer is one or a mixture of two of pyrrole and aniline in equal mass.

[0010] Furthermore, the concentration of the ammonium persulfate solution is 1 mol / L.

[0011] Furthermore, the protective gas is either nitrogen or argon.

[0012] The application of a composite expanding agent in the negative electrode plate of a lead-acid battery includes the following steps: preparing negative electrode lead paste using the composite expanding agent as a raw material;

[0013] Water, sulfuric acid, composite expanding agent and polyacrylamide are stirred evenly to obtain composite expanding agent solution. The stirring speed is 1000 r / min-1500 r / min.

[0014] Barium sulfate, humic acid, carbon black, and short fibers are mixed evenly to form mixture I. Mixture I is added to lead powder and mixed evenly. During the mixing and stirring of mixture I and lead powder, a composite expansion agent solution and water are added by high-pressure spraying. After stirring evenly, a negative electrode lead paste is obtained. The composite expansion agent is mixed evenly with lead powder, short fibers, humic acid, carbon black, barium sulfate, and water, and then coated onto the negative electrode grid. After coating, curing, and drying, a negative electrode green plate modified with the composite expansion agent is prepared.

[0015] Further, by weight, the composite expanding agent solution contains 100 parts water, 50-120 parts sulfuric acid, 10-20 parts composite expanding agent, and 0.5-2 parts polyacrylamide, with a sulfuric acid concentration of 1.0-1.2 g / cm³. 3 .

[0016] Furthermore, by weight, the negative electrode lead paste contains 100 parts lead powder, 0.5-1 parts barium sulfate, 0.1-0.6 parts humic acid, 0.1-1 parts carbon black, 0.1-0.4 parts short fibers, and 5-10 parts composite expansion agent solution.

[0017] Furthermore, the lead paste has an apparent density of 4.0-4.8, and the short fibers are polyester short fibers with a length ≤6mm.

[0018] The beneficial effects of this invention are:

[0019] This invention uses ammonium persulfate as an oxidant, which is added to an ethanol solution mixture of pyrrole / aniline monomer (conductive monomer), sodium lignosulfonate, and acrylamide to undergo an oxidation reaction. Subsequently, it is calcined at high temperature under a nitrogen or argon atmosphere to obtain a polypyrrole / aniline-sodium lignosulfonate composite expander. After adding ammonium persulfate, pyrrole or aniline and acrylamide can polymerize into polypyrrole, polyaniline, and polyacrylamide, which can form a compound that encapsulates sodium lignosulfonate in a composite polymer. After calcination under a protective gas atmosphere, some of the composite will carbonize to form a carbon-encapsulated sodium lignosulfonate composite expander.

[0020] Carbon itself is beneficial to battery performance and lifespan. Carbon-encapsulated composite expanders can slow down the consumption of sodium lignin sulfonate. Using composite expanders results in higher hydrogen evolution overpotential and more sustained low-temperature performance. When applied to the negative electrode plate of lead-acid batteries, composite expanders improve the sulfation problem of the negative electrode plate operating under high-efficiency partial charge conditions, reduce battery internal resistance, improve the utilization rate of lead paste activity, and give the electrode plate more sustained and superior low-temperature performance, thus extending the cycle life of lead-acid batteries. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1

[0023] This embodiment provides a composite expanding agent, which is prepared through the following steps:

[0024] By weight, 2 parts pyrrole, 1 part sodium lignosulfonate, 1 part acrylamide, and 10 parts anhydrous ethanol were mixed and ultrasonicated for 30 min using an ultrasonic cleaner. Then, 3 parts of 1 mol / L ammonium sulfate solution were added dropwise, and the mixture was allowed to stand for 12 h to obtain a reaction solution. After filtering and cleaning the reaction solution, it was placed in a tube furnace under nitrogen protection and calcined at 300°C for 2 h under nitrogen atmosphere protection. After grinding, a composite expanding agent was obtained.

[0025] Example 2

[0026] This embodiment provides a composite expanding agent, which is prepared through the following steps:

[0027] By weight, 1.5 parts pyrrole, 1.5 parts sodium lignosulfonate, 3 parts acrylamide, and 30 parts anhydrous ethanol were mixed and ultrasonicated for 30 minutes. Then, 6 parts of 1 mol / L ammonium sulfate solution were added dropwise, and the mixture was allowed to stand for 12 hours to obtain a reaction solution. After filtering and washing, the reaction solution was placed in a tube furnace under nitrogen protection and calcined at 400°C for 2 hours. The resulting composite expanding agent was obtained by grinding. The conductive monomer was a mixture of pyrrole and aniline in equal parts by weight.

[0028] Example 3

[0029] This embodiment provides a composite expanding agent, which is prepared through the following steps:

[0030] By weight, 1 part aniline, 2 parts sodium lignosulfonate, 5 parts acrylamide, and 40 parts anhydrous ethanol were mixed and ultrasonicated for 30 min using an ultrasonic cleaner. Then, 9 parts of 1 mol / L ammonium sulfate solution were added dropwise, and the mixture was allowed to stand for 12 h to obtain a reaction solution. After filtering and cleaning the reaction solution, it was placed in a tube furnace under nitrogen protection and calcined at 500°C for 2 h under nitrogen protection. After grinding, a composite expanding agent was obtained.

[0031] Example 4

[0032] The application of a composite expanding agent in the negative electrode plate of a lead-acid battery includes the following steps: preparing negative electrode lead paste using the composite expanding agent as a raw material;

[0033] By weight, 100 parts water, 50 parts sulfuric acid, 10 parts of the composite expanding agent prepared in Example 1, and 0.5 parts polyacrylamide were stirred evenly at a stirring rate of 1000 r / min to obtain a composite expanding agent solution; the sulfuric acid concentration was 1.0 g / cm³. 3 .

[0034] By weight, 0.5 parts barium sulfate, 0.1 parts humic acid, 0.1 parts carbon black, and 0.1 parts short fibers are mixed evenly to form mixture I. Mixture I is added to 100 parts lead powder and mixed evenly. During the mixing and stirring of mixture I and lead powder, 5 parts composite expansion agent solution and water are added by high-pressure spraying. After stirring evenly, negative electrode lead paste is obtained. The lead paste has an apparent density of 4.0, and the short fibers are polyester short fibers with a length ≤6mm. The negative electrode lead paste is coated on the negative electrode grid, and after coating, curing, and drying, a negative electrode green plate modified with composite expansion agent is prepared.

[0035] Example 5

[0036] The application of a composite expanding agent in the negative electrode plate of a lead-acid battery includes the following steps: preparing negative electrode lead paste using the composite expanding agent as a raw material;

[0037] By weight, 100 parts water, 90 parts sulfuric acid, 15 parts of the composite expanding agent prepared in Example 2, and 1 part polyacrylamide were stirred evenly at a stirring rate of 1200 r / min to obtain a composite expanding agent solution; the sulfuric acid concentration was 1.2 g / cm³. 3 .

[0038] By weight, 0.8 parts barium sulfate, 0.5 parts humic acid, 0.8 parts carbon black, and 0.3 parts short fibers are mixed evenly to form mixture I. Mixture I is added to 100 parts lead powder and mixed evenly. During the mixing and stirring of mixture I and lead powder, 8 parts composite expansion agent solution and water are added by high-pressure spraying. After stirring evenly, negative electrode lead paste is obtained. The apparent density of the lead paste is 4.6, and the short fibers are polyester short fibers with a length ≤6mm. The negative electrode lead paste is coated on the negative electrode grid, and after coating, curing, and drying, a negative electrode green plate modified with composite expansion agent is prepared.

[0039] Example 6

[0040] The application of a composite expanding agent in the negative electrode plate of a lead-acid battery includes the following steps: preparing negative electrode lead paste using the composite expanding agent as a raw material;

[0041] By weight, 100 parts water, 120 parts sulfuric acid, 20 parts of the composite expanding agent prepared in Example 3, and 2 parts polyacrylamide were stirred evenly at a stirring rate of 1500 r / min to obtain a composite expanding agent solution; the sulfuric acid concentration was 1.2 g / cm³. 3 .

[0042] By weight, 1 part barium sulfate, 0.6 parts humic acid, 1 part carbon black, and 0.4 parts short fibers are mixed evenly to form mixture I. Mixture I is added to 100 parts lead powder and mixed evenly. During the mixing and stirring of mixture I and lead powder, 10 parts composite expansion agent solution and water are added by high-pressure spraying. After stirring evenly, negative electrode lead paste is obtained. The apparent density of the lead paste is 4.8, and the short fibers are polyester short fibers with a length ≤6mm. The negative electrode lead paste is coated on the negative electrode grid, and after coating, curing, and drying, a negative electrode green plate modified with composite expansion agent is prepared.

[0043] When the electrode plates are dried and cured, a medium-temperature and high-humidity curing process is adopted, with a curing time of 24-48 hours, a relative humidity of 90-98%, a drying time of 24-36 hours, and a temperature of 50-60℃.

[0044] The test method for the strength of the battery plates is as follows: Weigh the plate mass and record it as m1; then place the plate in a free fall impact test at a height of 1.5m above the ground, and repeat the test 4 times; after that, measure the mass of the plate after the free fall impact test and record it as m2; finally, calculate the percentage reduction in plate mass before and after the test, i.e., m2 ÷ m1 × 100% = t.

[0045] The experiment used two positive plates and one negative plate to assemble a lead-acid battery. The purpose was to ensure an excess of positive electrode active material and to focus on the effect of adding different expansion agents to the negative electrode active material on the high-rate partial state of charge (HRPSoC) cycle life of the lead-acid battery.

[0046] The HRPSoC cycle performance test procedure for lead-acid batteries is as follows: First, discharge the battery to 40% partial state of charge (SoC) under a constant current of 1C; then, charge it under a constant current of 1C for 60 seconds; then, let it rest for 10 seconds; immediately after, discharge it under a constant current of 1C for 60 seconds; finally, let it rest for another 10 seconds. This constitutes one complete HRPSoC cycle. Multiple cycles are performed until the discharge voltage drops below the national standard reference voltage of 1.75V, at which point the cycle ends. The Neware battery testing system manufactured by Shenzhen Neware Electronics Co., Ltd. was used in the experiment.

[0047] The results are shown in Table 1:

[0048] Table 1

[0049] project Example 4 Example 5 Example 6 Plate drop strength 98.7％ 99.0％ 99.2％ High-rate partial state-of-charge cycle life (cycles) 1864 1578 1245

[0050] As shown in Table 1, the composite expander applied to the negative plate of lead-acid battery improves the sulfation problem of the negative plate when operating under high efficiency partial charge state, reduces the internal resistance of the battery, improves the utilization rate of lead paste activity, and the plate has more durable and better low-temperature performance, thus extending the cycle life of lead-acid battery.

[0051] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite expanding agent, characterized in that, The composite expanding agent comprises the following raw materials in parts by weight: 1-3 parts conductive monomer, 1-3 parts sodium lignosulfonate, 1-5 parts acrylamide, 10-40 parts anhydrous ethanol, and 3-9 parts ammonium persulfate solution; the concentration of the ammonium persulfate solution is 1 mol / L; the composite expanding agent is prepared by the following steps: The conductive monomer, sodium lignosulfonate, acrylamide, and anhydrous ethanol were mixed and ultrasonicated for 30 minutes using an ultrasonic cleaner. Then, ammonium persulfate solution was added dropwise, and the mixture was allowed to stand to obtain a reaction solution. After filtering and cleaning the reaction solution, it was placed in a tube furnace under protective gas and calcined at 300-500℃ for 2 hours under the protective gas atmosphere. The composite expanding agent was then obtained by grinding.

2. The composite expanding agent according to claim 1, characterized in that, The conductive monomer is one or a mixture of two of pyrrole and aniline in equal mass.

3. The composite expanding agent according to claim 1, characterized in that, The protective gas is either nitrogen or argon.

4. The application of the composite expanding agent according to claim 1 in the negative electrode plate of a lead-acid battery, characterized in that, Including the preparation of negative electrode lead paste: Water, sulfuric acid, composite expanding agent and polyacrylamide are stirred evenly to obtain composite expanding agent solution. Barium sulfate, humic acid, carbon black and short fibers are mixed evenly to form mixture I. Mixture I is added to lead powder and mixed evenly. During the mixing and stirring of mixture I and lead powder, composite expanding agent solution and water are added and stirred evenly to obtain negative electrode lead paste.

5. The application of the composite expanding agent according to claim 4 in the negative electrode plate of a lead-acid battery, characterized in that, The composite expanding agent solution, by weight, contains 100 parts water, 50-120 parts sulfuric acid, 10-20 parts composite expanding agent, and 0.5-2 parts polyacrylamide, with a sulfuric acid concentration of 1.0-1.2 g / cm³. 3 .

6. The application of the composite expanding agent according to claim 4 in the negative electrode plate of a lead-acid battery, characterized in that, By weight, the negative electrode lead paste contains 100 parts lead powder, 0.5-1 parts barium sulfate, 0.1-0.6 parts humic acid, 0.1-1 parts carbon black, 0.1-0.4 parts short fibers, and 5-10 parts composite expansion agent solution.

7. The application of the composite expanding agent according to claim 4 in the negative electrode plate of a lead-acid battery, characterized in that, The lead paste has an apparent density of 4.0-4.8, and the short fibers are polyester short fibers with a length ≤6mm.