A negative electrode composite additive for improving the performance of lead-acid batteries and a method for preparing the same

Abstract

The present application relates to the technical field of lead-acid battery, and proposes a negative electrode composite additive for improving the performance of lead-acid battery and a preparation method thereof.The negative electrode composite additive comprises barium sulfate, antimony trioxide, colloidal graphite, cerium oxide, phosphorus-coated carbon and sulfonated styrene-maleic anhydride copolymer.The present application forms an inorganic-organic-carbon multi-component synergistic system by compounding the use of barium sulfate, antimony trioxide, colloidal graphite, cerium oxide, phosphorus-coated carbon and sulfonated styrene-maleic anhydride copolymer.The system can simultaneously improve the electronic conductivity, ion diffusivity and structural stability of the negative electrode material, promote the refinement of PbSO4 crystal grains and inhibit polarization, and effectively improve the discharge efficiency and cycle life of the electrode.

Description

Technical Field

[0001] This invention relates to the field of lead-acid battery technology, and in particular to a negative electrode composite additive for improving the performance of lead-acid batteries and its preparation method. Background Technology

[0002] Lead-acid batteries, as one of the most widely used rechargeable batteries, occupy an important position in fields such as automotive starting power, backup power for communication and power systems, and renewable energy storage systems due to their advantages of low cost, mature manufacturing process, safety, reliability, and high recyclability. However, with the rapid development of new energy and energy storage, higher performance requirements are being placed on lead-acid batteries, such as high specific energy, high power density, long cycle life, and wide temperature adaptability. To achieve these performance optimizations, improving the performance of the negative electrode is particularly crucial. The negative electrode material not only directly affects the battery's charge and discharge efficiency and lifespan but also determines the reversibility and stability of the electrode reactions during cycling.

[0003] Traditional lead-acid batteries primarily use sponge lead as the active material in their negative electrode. During long-term charge-discharge cycles, this material is prone to sulfation, forming large, difficult-to-reduce lead sulfate crystals. Sulfation reduces the contact between the active material and the electrolyte, increases polarization, and rapidly diminishes battery capacity, thus shortening battery life. Furthermore, conventional negative electrodes have poor conductivity and limited electron transport rates, especially under high-rate charge-discharge conditions, easily leading to undercharging or limited depth of discharge. Simultaneously, changes in ambient temperature significantly impact negative electrode performance: at high temperatures, hydrogen evolution side reactions intensify, causing electrolyte water loss and increased internal pressure; at low temperatures, electrolyte viscosity increases and ion diffusion rates decrease, resulting in a substantial reduction in battery capacity. To address these issues, developing composite additives for the negative electrode with excellent conductivity and thermal stability has become an effective way to improve the overall performance of lead-acid batteries. Summary of the Invention

[0004] In view of this, the present invention proposes a composite additive for the negative electrode of lead-acid batteries with excellent conductivity and thermal stability, and a method for preparing the same.

[0005] The technical solution of the present invention is achieved as follows: On the one hand, the present invention provides a negative electrode composite additive for improving the performance of lead-acid batteries, including barium sulfate, antimony trioxide, colloidal graphite, cerium oxide, phosphorus-coated carbon, and sulfonated styrene-maleic anhydride copolymer.

[0006] Specifically, a composite additive consisting of barium sulfate, antimony trioxide, colloidal graphite, cerium oxide, phosphorus-coated carbon, and sulfonated styrene-maleic anhydride copolymer forms a synergistic system with both electrical conductivity and thermal stability in the negative electrode plate.

[0007] Among them, colloidal graphite and phosphorus-coated carbon construct a continuous electron conduction network, significantly reducing charge transport impedance and improving discharge reversibility and 1C fast charging performance at low temperatures (-20℃). Antimony trioxide acts as a catalytic and conductive agent at the charge-discharge interface, promoting the reversible conversion of active lead and PbSO4. The reversible conversion of cerium oxide (Ce)... 3+ / Ce 4+ The system effectively suppresses hydrogen evolution reaction and maintains the chemical stability of the electrode at high temperatures. The sulfonated styrene-maleic anhydride copolymer's sulfonic acid groups improve ion migration channels and electrode wetting, resulting in uniform dispersion of the conductive phase. Barium sulfate acts as an inertial nucleus and framework component, stabilizing the electrode's microporous structure. Through this combined effect, the conductive phase is uniformly distributed, the thermal failure rate is reduced, and the battery's cycle life at -20℃ and 40℃ is significantly improved. Simultaneously, it exhibits high capacity retention during 1C fast charging, demonstrating excellent conductivity and thermal stability.

[0008] Based on the above technical solutions, the preferred composition, calculated by weight, includes: 1-3 parts barium sulfate, 0.1-0.5 parts antimony trioxide, 1-3 parts colloidal graphite, 0.1-0.3 parts cerium oxide, 0.3-0.5 parts phosphorus-coated carbon, and 0.2-0.4 parts sulfonated styrene-maleic anhydride copolymer.

[0009] Based on the above technical solutions, preferably, the method for preparing the phosphorus-coated carbon includes the following steps:

[0010] S11. Take the dried and pulverized plant raw materials and immerse them in sulfuric acid solution for acid hydrolysis for 15-30 minutes. Then filter and wash the filtrate with water until neutral. Then immerse it in NaOH solution for alkaline hydrolysis for 15-30 minutes. Filter again and rinse until neutral. Finally, immerse the filtrate in phosphoric acid solution, sonicate for 20-30 minutes, centrifuge and discard the residue to obtain a phosphorus-containing oligosaccharide solution.

[0011] S12: After mixing phosphorus-containing oligosaccharide solution with activated carbon powder evenly, filter and collect the filter cake; then calcine the filter cake at 445-455℃ for 3-4 hours under a nitrogen protective atmosphere, cool and pulverize to obtain phosphorus-coated carbon micro powder.

[0012] Based on the above technical solutions, preferably, in step S11, the volume concentration of sulfuric acid solution is 1%-2%, the mass concentration of NaOH solution is 2%-3%, and the volume concentration of phosphoric acid solution is 70%-80%; the mass ratio of plant raw material: sulfuric acid solution: NaOH solution: phosphoric acid solution is 10:20-30:22-28:20-25.

[0013] In step S12, the mass ratio of phosphorus-containing oligosaccharide solution to activated carbon powder is 3-5:1.

[0014] Based on the above technical solutions, a preferred method for preparing sulfonated styrene-maleic anhydride copolymer includes the following steps:

[0015] S21, using styrene and maleic anhydride as monomers, a solution copolymerization reaction was carried out at 60-80℃ in the presence of azobisisobutyronitrile to obtain a styrene-maleic anhydride copolymer; then the styrene-maleic anhydride copolymer was dissolved in a chlorosulfonic acid / toluene mixed solution and reacted at 40-50℃ for 2-3 hours.

[0016] S22, after the reaction is complete, ethanol and NaOH are added to neutralize the reaction, then water is added, stirred and allowed to stand, the lower hydrochloric acid aqueous solution is removed, and then filtered and vacuum dried to obtain sulfonated styrene-maleic anhydride copolymer.

[0017] Based on the above technical solutions, preferably, in step S21, the solvent is toluene or xylene, the total weight ratio of styrene and maleic anhydride to the solvent is 1:3-5; the mass ratio of styrene, maleic anhydride and azobisisobutyronitrile is 10-15:8-12:1-2; the volume ratio of chlorosulfonic acid to toluene is 1:4-6; and the mass ratio of chlorosulfonic acid to styrene-maleic anhydride copolymer is 1.2-1.5:1.

[0018] In step S22, 20% NaOH is added to the ethanol to adjust the pH to 6-7.

[0019] Based on the above technical solutions, preferably, the phosphorus-coated carbon surface is modified with SnO2.

[0020] Specifically, the SnO2 modification layer combines with carbon through chemical bonds to form a semiconductor-conductor composite interface, maintaining the high conductivity of carbon materials while providing excellent thermal conductivity and oxidation inhibition. This modification layer effectively prevents the carbon phase from oxidizing and decaying at high temperatures, stabilizing the reaction interface on the active lead surface; simultaneously, Sn... 4+ / Sn 2+ Its reversible redox behavior promotes electron migration and ion diffusion in the micro-regions of active materials, making the charge-discharge reaction more complete. When it works together with Sb2O3 and CeO2 in the system, the conductivity-thermal stability coupling effect is further enhanced, resulting in lower polarization, higher capacity retention and longer cycle life under low temperature cycling, high temperature cycling and fast charging conditions, achieving a significant efficiency improvement.

[0021] Based on the above technical solutions, the preferred method for preparing the phosphorus-coated carbon surface-modified SnO2 is as follows:

[0022] Stannous chloride was dissolved in anhydrous ethanol, citric acid was added and stirred until dissolved, then phosphorus-coated carbon powder was added, stirred evenly, and the ethanol was removed by vacuum distillation to obtain the SnO2-phosphorus-coated carbon composite precursor; then the SnO2-phosphorus-coated carbon composite precursor was calcined at 500-550℃ for 2-3h, cooled and pulverized to obtain SnO2@PC.

[0023] Based on the above technical solutions, the preferred mass ratio of stannous chloride, anhydrous ethanol, phosphoric acid citrate, and carbon-coated micro powder is 0.5-1:50-80:0.3-0.5:10.

[0024] On the other hand, the present invention also provides a method for preparing a negative electrode composite additive to improve the performance of lead-acid batteries, comprising the following steps:

[0025] Solution I was obtained by dissolving sulfonated styrene-maleic anhydride copolymer in water at 50-60℃.

[0026] Barium sulfate, antimony trioxide, colloidal graphite, cerium oxide, and SnO2@PC were mixed in a planetary mixer for 30 minutes. Then, solution I was slowly added and the mixture was stirred for another 20-30 minutes. The mixture was then vacuum dried and ground to obtain the negative electrode composite additive.

[0027] The negative electrode composite additive for improving the performance of lead-acid batteries and its preparation method of the present invention have the following advantages over the prior art:

[0028] (1) This invention employs a composite system of barium sulfate, antimony trioxide, colloidal graphite, cerium oxide, phosphorus-coated carbon, and sulfonated styrene-maleic anhydride copolymer to form a synergistic structure of conductivity and thermal stability. This combination can significantly reduce polarization, improve electron and ion conduction efficiency, improve low-temperature cycling performance at -20℃ and high-temperature cycling stability at 40℃, and improve 1C fast charging capacity retention, exhibiting excellent conductivity and thermal stability.

[0029] (2) This invention further optimizes the conductive phase structure by modifying phosphorus-coated carbon with SnO2, constructs a semiconductor-carbon composite interface, enhances the material's oxidation resistance and thermal conductivity, and promotes the reversible transformation of active lead. After this improvement, the battery cycle life and fast-charging performance are further enhanced, and the overall performance achieves continuous improvement. Detailed Implementation

[0030] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] All materials used in this invention were purchased from the market, with the colloidal graphite being colloidal graphite S-1 purchased from Qingdao Tianheda Graphite Co., Ltd.

[0032] Example 1

[0033] This embodiment provides a negative electrode composite additive to improve the performance of lead-acid batteries, including barium sulfate, antimony trioxide, colloidal graphite, cerium oxide, phosphorus-coated carbon, and sulfonated styrene-maleic anhydride copolymer.

[0034] The preparation method of phosphorus-coated carbon includes the following steps:

[0035] S11. Take 100g of dried and crushed plant material (rice straw) and soak it in 25g of sulfuric acid solution (volume concentration 1%) for acid hydrolysis for 20min. Then filter it and wash the filtrate with water until neutral. Then soak it in 260g of NaOH solution (mass concentration 2.5%) for alkaline hydrolysis for 20min. Filter it again and wash it until neutral. Finally, soak the filtrate in 230g of phosphoric acid solution (volume concentration 75%), sonicate it at 10kW for 25min, centrifuge it and discard the residue to obtain a phosphorus-containing oligosaccharide solution.

[0036] S12, take 150g of phosphorus-containing oligosaccharide solution and mix it evenly with 40g of activated carbon powder, filter it, and collect the filter cake; then calcine the filter cake at 450℃ for 3.5h under a nitrogen protective atmosphere, cool it and crush it to obtain phosphorus-coated carbon micro powder.

[0037] The preparation method of sulfonated styrene-maleic anhydride copolymer includes the following steps:

[0038] S21, 20g of maleic anhydride was dissolved in 400mL of toluene. After complete dissolution at 50℃, 25g of styrene monomer was added. After stirring evenly, nitrogen gas was purged for 20min to remove oxygen. Under a nitrogen atmosphere, the temperature was raised to 70℃, and 3g of azobisisobutyronitrile (AIBN) pre-dissolved in 80mL of toluene was added. After stirring for 4h, the mixture was cooled to room temperature, and an appropriate amount of methanol was added dropwise to precipitate the product. The solid was collected by filtration and washed three times with ethanol to remove unreacted monomers and solvent residues. The filtered copolymer was dried under vacuum at 70℃ for 10h to obtain the styrene-maleic anhydride copolymer solid.

[0039] Subsequently, 20g of styrene-maleic anhydride copolymer was dissolved in a chlorosulfonic acid / toluene mixed solution (28g of chlorosulfonic acid was used, and the volume ratio of chlorosulfonic acid to toluene was 1:5), and the mixture was reacted at 45℃ for 2.5h.

[0040] S22. After the reaction is complete, add 150 mL of ethanol, add NaOH to adjust the pH to 6.5, then add water, stir and let stand, remove the lower hydrochloric acid aqueous solution, then filter and vacuum dry to obtain sulfonated styrene-maleic anhydride copolymer.

[0041] The preparation method of the negative electrode composite additive in this embodiment includes the following steps:

[0042] S31, Dissolve 15g of sulfonated styrene-maleic anhydride copolymer in 150mL of water at 55℃ to obtain solution I;

[0043] S32, 100g barium sulfate, 15g antimony trioxide, 100g colloidal graphite, 10g cerium oxide and 20g phosphorus-coated carbon micro powder are mixed in a planetary mixer for 30min, then solution I is slowly added and stirring is continued for 25min. The mixture is then vacuum dried and ground to obtain the negative electrode composite additive.

[0044] Example 2

[0045] The difference between Example 2 and Example 1 is that SnO2 is modified on the phosphorus-coated carbon surface, and SnO2@PC is added in the preparation method of the negative electrode composite additive. The rest is the same as in Example 1.

[0046] The preparation method of phosphorus-coated carbon surface modified SnO2 includes the following steps: 4g of stannous chloride is dissolved in 300g of anhydrous ethanol, 2g of citric acid is added and stirred until dissolved, then 50g of phosphorus-coated carbon powder is added, stirred evenly, and the ethanol is removed by vacuum distillation to obtain SnO2-phosphorus-coated carbon composite precursor; then the SnO2-phosphorus-coated carbon composite precursor is calcined at 530℃ for 2.5h, cooled and pulverized to obtain SnO2@PC.

[0047] Example 3

[0048] This embodiment provides a negative electrode composite additive to improve the performance of lead-acid batteries, including barium sulfate, antimony trioxide, colloidal graphite, cerium oxide, SnO2-modified phosphorus-coated carbon, and sulfonated styrene-maleic anhydride copolymer.

[0049] The preparation method of SnO2-modified phosphorus-coated carbon includes the following steps:

[0050] S11. Take 100g of dried and pulverized plant material (rice straw) and soak it in 20g of sulfuric acid solution (volume concentration 1%) for acid hydrolysis for 15min. Then filter it and wash the filtrate with water until neutral. Then soak it in 220g of NaOH solution (mass concentration 2%) for alkaline hydrolysis for 15min. Filter it again and wash it until neutral. Finally, soak the filtrate in 200g of phosphoric acid solution (volume concentration 70%), sonicate it at 10kW for 20min, centrifuge it and discard the residue to obtain a phosphorus-containing oligosaccharide solution.

[0051] S12, take 150g of phosphorus-containing oligosaccharide solution and mix it evenly with 30g of activated carbon powder, filter it, and collect the filter cake; then calcine the filter cake at 445℃ for 3h under a nitrogen protective atmosphere, cool it and crush it to obtain phosphorus-coated carbon micro powder.

[0052] S13, 2.5g of stannous chloride was dissolved in 250g of anhydrous ethanol, 1.5g of citric acid was added and stirred until dissolved, then 50g of phosphorus-coated carbon powder was added, stirred evenly, and the ethanol was removed by vacuum distillation to obtain the SnO2-phosphorus-coated carbon composite precursor; then the SnO2-phosphorus-coated carbon composite precursor was calcined at 500℃ for 3h, cooled and pulverized to obtain SnO2@PC.

[0053] The preparation method of sulfonated styrene-maleic anhydride copolymer includes the following steps:

[0054] S21: Dissolve 16g of maleic anhydride in 400mL of toluene or xylene. After complete dissolution at 50℃, add 20g of styrene monomer. Stir until homogeneous, then purge with nitrogen for 20min to remove oxygen. Under a nitrogen atmosphere, heat to 60℃, and add 2g of azobisisobutyronitrile (AIBN) pre-dissolved in 80mL of toluene or xylene. Stir and react for 4h, then cool to room temperature. Add an appropriate amount of methanol or ethanol dropwise to precipitate the product. Filter and collect the solid, washing three times repeatedly with ethanol to remove unreacted monomers and solvent residue. Dry the filtered copolymer under vacuum at 70℃ for 10h to obtain the styrene-maleic anhydride copolymer solid.

[0055] Subsequently, 20g of styrene-maleic anhydride copolymer was dissolved in a chlorosulfonic acid / toluene mixed solution (24g of chlorosulfonic acid was used, and the volume ratio of chlorosulfonic acid to toluene was 1:4), and the mixture was reacted at 40℃ for 3h.

[0056] S22. After the reaction is complete, add 120 mL of ethanol, add NaOH to adjust the pH to 6, then add water, stir and let stand, remove the lower hydrochloric acid aqueous solution, then filter and vacuum dry to obtain sulfonated styrene-maleic anhydride copolymer.

[0057] The preparation method of the negative electrode composite additive in this embodiment includes the following steps:

[0058] S31, Dissolve 10g of sulfonated styrene-maleic anhydride copolymer in 150mL of water at 50℃ to obtain solution I;

[0059] S32, mix 50g barium sulfate, 5g antimony trioxide, 50g colloidal graphite, 5g cerium oxide and 15g phosphorus-coated carbon micro powder in a planetary mixer for 30min, then slowly add solution I, continue stirring for 20min, then vacuum dry the mixture and grind it to obtain the negative electrode composite additive.

[0060] Example 4

[0061] This embodiment provides a negative electrode composite additive to improve the performance of lead-acid batteries, including barium sulfate, antimony trioxide, colloidal graphite, cerium oxide, SnO2-modified phosphorus-coated carbon, and sulfonated styrene-maleic anhydride copolymer.

[0062] The preparation method of SnO2-modified phosphorus-coated carbon includes the following steps:

[0063] S11. Take 100g of dried and crushed plant material (rice straw) and soak it in 28g of sulfuric acid solution (volume concentration 1.3%) for acid hydrolysis for 25min. Then filter it and wash the filtrate with water until neutral. Then soak it in 260g of NaOH solution (mass concentration 2.2%) for alkaline hydrolysis for 25min. Filter it again and wash it until neutral. Finally, soak the filtrate in 220g of phosphoric acid solution (volume concentration 73%), sonicate it at 10kW for 28min, centrifuge it and discard the residue to obtain a phosphorus-containing oligosaccharide solution.

[0064] S12, take 150g of phosphorus-containing oligosaccharide solution and mix it evenly with 45g of activated carbon powder, filter it, and collect the filter cake; then calcine the filter cake at 450℃ for 3.5h under a nitrogen protective atmosphere, cool it and crush it to obtain phosphorus-coated carbon micro powder.

[0065] S13, 3.4g of stannous chloride was dissolved in 340g of anhydrous ethanol, 2.2g of citric acid was added and stirred until dissolved, then 50g of phosphorus-coated carbon powder was added, stirred evenly, and the ethanol was removed by vacuum distillation to obtain the SnO2-phosphorus-coated carbon composite precursor; then the SnO2-phosphorus-coated carbon composite precursor was calcined at 520℃ for 3h, cooled and pulverized to obtain SnO2@PC.

[0066] The preparation method of sulfonated styrene-maleic anhydride copolymer includes the following steps:

[0067] S21, 22g of maleic anhydride was dissolved in 400mL of toluene or xylene. After complete dissolution at 50℃, 22g of styrene monomer was added. After stirring evenly, nitrogen gas was purged for 20min to remove oxygen. Under a nitrogen atmosphere, the temperature was raised to 65℃, and 3.5g of azobisisobutyronitrile (AIBN) pre-dissolved in 80mL of toluene or xylene was added. After stirring for 4h, the mixture was cooled to room temperature, and an appropriate amount of methanol or ethanol was added dropwise to precipitate the product. The solid was collected by filtration and washed three times with ethanol to remove unreacted monomers and solvent residues. The filtered copolymer was dried under vacuum at 70℃ for 10h to obtain the styrene-maleic anhydride copolymer solid.

[0068] Subsequently, 20g of styrene-maleic anhydride copolymer was dissolved in a chlorosulfonic acid / toluene mixed solution (28g of chlorosulfonic acid was used, and the volume ratio of chlorosulfonic acid to toluene was 1:4.5), and reacted at 45℃ for 3h.

[0069] S22. After the reaction is complete, add 160 mL of ethanol, add NaOH to adjust the pH to 7, then add water, stir and let stand, remove the lower hydrochloric acid aqueous solution, then filter and vacuum dry to obtain sulfonated styrene-maleic anhydride copolymer.

[0070] The preparation method of the negative electrode composite additive in this embodiment includes the following steps:

[0071] S31, Dissolve 18g of sulfonated styrene-maleic anhydride copolymer in 150mL of water at 60℃ to obtain solution I;

[0072] S32, 80g barium sulfate, 10g antimony trioxide, 80g colloidal graphite, 13g cerium oxide and 18g phosphorus-coated carbon micro powder are mixed in a planetary mixer for 30min, then solution I is slowly added and stirred for another 30min. The mixture is then vacuum dried and ground to obtain the negative electrode composite additive.

[0073] Example 5

[0074] This embodiment provides a negative electrode composite additive to improve the performance of lead-acid batteries, including barium sulfate, antimony trioxide, colloidal graphite, cerium oxide, SnO2-modified phosphorus-coated carbon, and sulfonated styrene-maleic anhydride copolymer.

[0075] The preparation method of SnO2-modified phosphorus-coated carbon includes the following steps:

[0076] S11. Take 100g of dried and crushed plant material (rice straw) and soak it in 30g of sulfuric acid solution (volume concentration 2%) for acid hydrolysis for 30min. Then filter it and wash the filtrate with water until neutral. Then soak it in 280g of NaOH solution (mass concentration 3%) for alkaline hydrolysis for 30min. Filter it again and wash it until neutral. Finally, soak the filtrate in 250g of phosphoric acid solution (volume concentration 80%), sonicate it at 10kW for 30min, centrifuge it and discard the residue to obtain a phosphorus-containing oligosaccharide solution.

[0077] S12, take 150g of phosphorus-containing oligosaccharide solution and mix it evenly with 50g of activated carbon powder, filter it, and collect the filter cake; then calcine the filter cake at 455℃ for 3h under a nitrogen protective atmosphere, cool it and crush it to obtain phosphorus-coated carbon micro powder.

[0078] S13, 5g of stannous chloride was dissolved in 400g of anhydrous ethanol, 2.5g of citric acid was added and stirred until dissolved, then 50g of phosphorus-coated carbon powder was added, stirred evenly, and the ethanol was removed by vacuum distillation to obtain SnO2-phosphorus-coated carbon composite precursor; then the SnO2-phosphorus-coated carbon composite precursor was calcined at 550℃ for 2h, cooled and pulverized to obtain SnO2@PC.

[0079] The preparation method of sulfonated styrene-maleic anhydride copolymer includes the following steps:

[0080] S21, 24g of maleic anhydride was dissolved in 400mL of toluene or xylene. After complete dissolution at 50℃, 30g of styrene monomer was added. After stirring evenly, nitrogen gas was purged for 20min to remove oxygen. Under a nitrogen atmosphere, the temperature was raised to 80℃, and 4g of azobisisobutyronitrile (AIBN) pre-dissolved in 80mL of toluene or xylene was added. After stirring for 4h, the mixture was cooled to room temperature, and an appropriate amount of methanol or ethanol was added dropwise to precipitate the product. The solid was collected by filtration and washed three times with ethanol to remove unreacted monomers and solvent residues. The filtered copolymer was dried under vacuum at 70℃ for 10h to obtain the styrene-maleic anhydride copolymer solid.

[0081] Subsequently, 20g of styrene-maleic anhydride copolymer was dissolved in a chlorosulfonic acid / toluene mixed solution (30g of chlorosulfonic acid was used, and the volume ratio of chlorosulfonic acid to toluene was 1:6), and reacted at 50℃ for 2h.

[0082] S22. After the reaction is complete, add 180 mL of ethanol, add NaOH to adjust the pH to 7, then add water, stir and let stand, remove the lower hydrochloric acid aqueous solution, then filter and vacuum dry to obtain sulfonated styrene-maleic anhydride copolymer.

[0083] The preparation method of the negative electrode composite additive in this embodiment includes the following steps:

[0084] S31, Dissolve 20g of sulfonated styrene-maleic anhydride copolymer in 150mL of water at 60℃ to obtain solution I;

[0085] S32, mix 150g barium sulfate, 25g antimony trioxide, 150g colloidal graphite, 15g cerium oxide and 25g phosphorus-coated carbon micro powder in a planetary mixer for 30min; then slowly add solution I and continue stirring for 30min. Afterwards, vacuum dry the mixture and grind it to obtain the negative electrode composite additive.

[0086] Comparative Example 1

[0087] The difference between Comparative Example 1 and Example 1 is that the negative electrode composite additive lacks cerium oxide, while the rest is the same as in Example 1.

[0088] Comparative Example 2

[0089] The difference between Comparative Example 2 and Example 1 is that the negative electrode composite additive lacks phosphorus-coated carbon, while the rest is the same as in Example 1.

[0090] Comparative Example 3

[0091] The difference between Comparative Example 3 and Example 1 is that the styrene-maleic anhydride copolymer in the negative electrode composite additive is not sulfonated, and the styrene-maleic anhydride copolymer replaces the sulfonated styrene-maleic anhydride copolymer. The rest of the contents are the same as in Example 1.

[0092] Comparative Example 4

[0093] The difference between Comparative Example 4 and Example 1 is that the amount of cerium oxide used exceeds the limit, specifically 25g, while the rest is the same as in Example 1.

[0094] Comparative Example 5

[0095] The difference between Comparative Example 5 and Example 1 is that the amount of phosphorus-coated carbon used exceeds the limit, specifically 35g, while the rest is the same as in Example 1.

[0096] Comparative Example 6

[0097] The difference between Comparative Example 6 and Example 1 is that the amount of sulfonated styrene-maleic anhydride copolymer used exceeds the specified range, specifically 25g. The rest of the contents are the same as in Example 1.

[0098] Comparative Example 7

[0099] The difference between Comparative Example 7 and Example 2 is that the amount of stannous chloride used in the preparation of SnO2-modified phosphorus-coated carbon exceeded the specified range. The mass ratio of stannous chloride to carbon-coated micropowder was 2:10, and the specific amount used was 10g. The rest of the contents are the same as in Example 2.

[0100] According to the standard formula for lead-acid battery negative electrode paste: taking 100g of negative electrode paste as an example, there is 82.7g of lead and sulfuric acid (density 1.4g / cm³). 3 8g of deionized water, 8g of short fiber, 0.5g of lignin sulfonate, and 0.2% of negative electrode additive were prepared. The negative electrode materials for the lead-acid batteries in the examples and comparative examples were then prepared by coating and curing according to normal production processes, and assembled into lead-acid batteries (12V 80Ah AGM). Three batteries were prepared for each example and comparative example for experimentation. The number of cycles and capacity at -20℃, the number of cycles at 40℃ (40℃, 50% DOD), and 1C fast charging were tested. The results are shown in Table 1.

[0101] The cycle life at -20℃ is referenced in GB / T5008.1-2023. The test temperature is -20℃. The cycle life ends when the battery's discharge capacity is lower than 80% of its rated capacity.

[0102] -20℃ Low Temperature Capacity: The battery was placed in a low-temperature chamber set to -20℃ for 20 hours, and then discharged at -20℃. The capacity value was recorded. The battery was then charged after returning to room temperature.

[0103] Table 1 Performance test results of lead-acid batteries

[0104]

[0105] As shown in Table 1, the cycle performance, -20℃ capacity, and 1C fast charging performance of the samples in Examples 1-5 are significantly better than those of the comparative examples under conditions of 40℃, 25℃, and -20℃. Among them, Example 5 achieves 505 cycles at high temperature and 358 cycles at low temperature, showing the best overall performance. This indicates that with the introduction and optimization of SnO2-modified phosphorus-coated carbon, the conductivity and reversibility of the battery at low temperatures are continuously enhanced, exhibiting more stable output capability and less polarization.

[0106] In contrast, both missing and excessive components in the comparison samples led to performance degradation. In particular, the cycle counts of Comparative Examples 2 (lacking PC) and 3 (unsulfonated polymer) decreased significantly, proving that each functional component is indispensable and must be maintained in a reasonable ratio. Comparative Example 7 shows that when SnC2 is in excess, the SnO2 coating layer is too thick, which hinders electron conduction and causes performance to decline, further verifying the rationality of the optimization window.

[0107] This invention utilizes a phosphorus-coated carbon-SnO2 core-shell conductive structure and Ce... 3+ / Ce 4+ The reversible protection mechanism and the polyanion wetting and dispersion composite effect significantly improve the electron / ion transport and PbSO4 regeneration capacity of the negative electrode. The battery exhibits excellent stability and reversibility under high temperature, low temperature and fast charging conditions.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A negative electrode composite additive for improving the performance of lead-acid batteries, characterized in that: Based on weight parts, it includes: 1-3 parts barium sulfate, 0.1-0.5 parts antimony trioxide, 1-3 parts colloidal graphite, 0.1-0.3 parts cerium oxide, 0.3-0.5 parts phosphorus-coated carbon, and 0.2-0.4 parts sulfonated styrene-maleic anhydride copolymer.

2. The negative electrode composite additive for improving the performance of lead-acid batteries as described in claim 1, characterized in that: The method for preparing the phosphorus-coated carbon includes the following steps: S11. Take the dried and pulverized plant raw materials and immerse them in sulfuric acid solution for acid hydrolysis for 15-30 minutes. Then filter and wash the filtrate with water until neutral. Then immerse it in NaOH solution for alkaline hydrolysis for 15-30 minutes. Filter again and rinse until neutral. Finally, immerse the filtrate in phosphoric acid solution, sonicate for 20-30 minutes, centrifuge and discard the residue to obtain a phosphorus-containing oligosaccharide solution. S12: After mixing phosphorus-containing oligosaccharide solution with activated carbon powder evenly, filter and collect the filter cake; then calcine the filter cake at 445-455℃ for 3-4 hours under a nitrogen protective atmosphere, cool and pulverize to obtain phosphorus-coated carbon micro powder.

3. The negative electrode composite additive for improving the performance of lead-acid batteries as described in claim 2, characterized in that: In step S11, the volume concentration of the sulfuric acid solution is 1%-2%, the mass concentration of the NaOH solution is 2%-3%, and the volume concentration of the phosphoric acid solution is 70%-80%. The mass ratio of plant raw materials: sulfuric acid solution: NaOH solution: phosphoric acid solution is 10:20-30:22-28:20-25; In step S12, the mass ratio of phosphorus-containing oligosaccharide solution to activated carbon powder is 3-5:

1.

4. The negative electrode composite additive for improving the performance of lead-acid batteries as described in claim 1, characterized in that: The preparation method of sulfonated styrene-maleic anhydride copolymer includes the following steps: S21, using styrene and maleic anhydride as monomers, a solution copolymerization reaction was carried out at 60-80℃ in the presence of azobisisobutyronitrile to obtain a styrene-maleic anhydride copolymer; then the styrene-maleic anhydride copolymer was dissolved in a chlorosulfonic acid / toluene mixed solution and reacted at 40-50℃ for 2-3 hours. S22, after the reaction is complete, ethanol and NaOH are added to neutralize the reaction, then water is added, stirred and allowed to stand, the lower hydrochloric acid aqueous solution is removed, and then filtered and vacuum dried to obtain sulfonated styrene-maleic anhydride copolymer.

5. The negative electrode composite additive for improving the performance of lead-acid batteries as described in claim 4, characterized in that: In step S21, the solvent is toluene or xylene, the total weight ratio of styrene and maleic anhydride to the solvent is 1:3-5; the mass ratio of styrene, maleic anhydride and azobisisobutyronitrile is 10-15:8-12:1-2; the volume ratio of chlorosulfonic acid to toluene is 1:4-6, and the mass ratio of chlorosulfonic acid to styrene-maleic anhydride copolymer is 1.2-1.5:

1. In step S22, 20% NaOH is added to the ethanol to adjust the pH to 6-7.

6. The negative electrode composite additive for improving the performance of lead-acid batteries as described in claim 1, characterized in that: The phosphorus-coated carbon surface is modified with SnO2.

7. The negative electrode composite additive for improving the performance of lead-acid batteries as described in claim 6, characterized in that: The preparation method of the phosphorus-coated carbon surface-modified SnO2 includes the following steps: Stannous chloride was dissolved in anhydrous ethanol, citric acid was added and stirred until dissolved, then phosphorus-coated carbon powder was added, stirred evenly, and the ethanol was removed by vacuum distillation to obtain the SnO2-phosphorus-coated carbon composite precursor; then the SnO2-phosphorus-coated carbon composite precursor was calcined at 500-550℃ for 2-3h, cooled and pulverized to obtain SnO2@PC.

8. The negative electrode composite additive for improving the performance of lead-acid batteries as described in claim 7, characterized in that: The mass ratio of stannous chloride, anhydrous ethanol, phosphoric acid citrate, and carbon-coated micro powder is 0.5-1:50-80:0.3-0.5:

10.

9. A method for preparing a negative electrode composite additive for improving the performance of lead-acid batteries as described in any one of claims 6-8, characterized in that: Includes the following steps: Solution I was obtained by dissolving sulfonated styrene-maleic anhydride copolymer in water at 50-60℃. Barium sulfate, antimony trioxide, colloidal graphite, cerium oxide, and SnO2@PC were mixed in a planetary mixer for 30 minutes. Then, solution I was slowly added and the mixture was stirred for another 20-30 minutes. The mixture was then vacuum dried and ground to obtain the negative electrode composite additive.

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