A restoration fluid for lead acid battery plate crystallization removal, its preparation method and use method

Abstract

The application belongs to the technical field of lead-acid battery repair, and specifically discloses a repair liquid for removing lead-acid battery plate crystals, a preparation method and a use method. The repair liquid comprises deionized water, sodium sulfate, phosphoric acid, disodium EDTA, activated carbon, a preservative, cross-linked chitosan, citric acid, trisodium citrate and glacial acetic acid; the cross-linked chitosan is a gossypol-tannic acid compound modified chitosan. The preparation method comprises the following steps: after the surface of activated carbon is carboxylated by nitric acid oxidation, the activated carbon is combined with protonated cross-linked chitosan through electrostatic self-assembly to form a core-shell structure, and then the core-shell structure is compounded with an active water solution containing disodium EDTA and phosphoric acid to obtain the repair liquid. Through the construction of the core-shell structure and the multi-level complex system, the synergistic effect of deep sulfur removal and long-term film protection is achieved, the regeneration of lead sulfate crystals is effectively inhibited, and the service life of the battery is greatly prolonged.

Description

Technical Field

[0001] This invention belongs to the field of lead-acid battery repair technology, and relates to a repair solution for removing crystallization from lead-acid battery plates, its preparation method and usage method. Background Technology

[0002] Lead-acid batteries are widely used in automobiles, electric vehicles, and energy storage devices due to their advantages such as low cost, stable voltage, and good safety. However, during long-term use, especially under conditions of frequent undercharging, over-discharging, or prolonged storage, coarse and hard lead sulfate crystals, known as "sulfation," easily form on the surface of the plates. Lead sulfate crystals have poor conductivity and are difficult to reduce to active materials during charging, leading to a decrease in battery capacity, an increase in internal resistance, and a deterioration in charge-discharge performance, ultimately resulting in battery failure and disposal.

[0003] Currently, lead-acid battery sulfation repair technologies mainly fall into two categories: physical methods and chemical methods. Physical methods, such as pulse repair and high-current charging, break down the lead sulfate crystal layer through voltage impacts or high currents at specific frequencies. However, these methods require specialized equipment and have limited effectiveness in repairing severe sulfation. Chemical methods primarily involve adding chemical reagents, such as sodium sulfate, magnesium sulfate, and disodium EDTA, to the electrolyte to alter its composition and promote lead sulfate dissolution. However, existing chemical repair technologies often employ simple physical mixing of multiple active ingredients. The components act independently, lacking synergistic chemical reactions and electrochemical coupling, resulting in limited repair effectiveness and short-lasting effects.

[0004] Existing technologies have disclosed technical solutions for using single components or partial combinations of sodium sulfate, magnesium sulfate, phosphoric acid, and disodium EDTA in lead-acid battery repair solutions. For example, CN101022181A discloses a restoring activator composed of sodium sulfate, ammonium sulfate, manganese dioxide, activated carbon, tartaric acid, and distilled water; CN102013534B discloses a capacity activating solution containing components such as sodium sulfate, phosphoric acid, and disodium EDTA. However, these existing technologies have failed to reveal the synergistic mechanism of each component during battery charging and discharging, nor have they designed the activator's role in relation to different stages of the charging process; essentially, they still represent a simple superposition of components.

[0005] Therefore, there is an urgent need to develop a sulfate crystal removal and repair solution that can fully utilize the charging and discharging process of lead-acid batteries and achieve synergistic effects of various components, so as to achieve efficient and long-lasting battery repair. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention provides a repair solution for removing crystallization from lead-acid battery plates, its preparation method, and its application method. The core of the solution lies in: carboxylating the surface of activated carbon through nitric acid oxidation, followed by electrostatic self-assembly of genipin-tannic acid-modified cross-linked chitosan in a weakly acidic system to form a core-shell structure, constructing a three-phase synergistic repair dispersion system. This achieves an organic combination of EDTA-phosphoric acid synergistic dissolution and cross-linked chitosan slow-release protection, effectively inhibiting secondary crystal formation.

[0007] To achieve the above and other objectives, the technical solution adopted by the present invention is as follows:

[0008] This invention provides a repair solution for removing crystallization from lead-acid battery plates, comprising the following raw materials in parts by weight: 88-94 parts deionized water, 0.4-1.0 parts sodium sulfate, 0.2-0.5 parts phosphoric acid, 0.3-0.8 parts disodium EDTA, 0.6-1.2 parts activated carbon, 0.2-0.8 parts preservative, 0.1-0.4 parts cross-linked chitosan, 0.05-0.15 parts citric acid, 0.03-0.10 parts trisodium citrate, and 0.05-0.15 parts glacial acetic acid; wherein the preservative is at least one of sodium benzoate and potassium sorbate.

[0009] Furthermore, the activated carbon is powdered wood-based activated carbon with a particle size of 100-300 mesh.

[0010] Furthermore, the preferred weight ratio of disodium EDTA to phosphoric acid is 8:3.

[0011] Furthermore, the cross-linked chitosan is a genipin-tannic acid composite modified chitosan, and its preparation method is as follows:

[0012] (1) Dissolve chitosan with a degree of deacetylation ≥90% in a 2wt% aqueous acetic acid solution to prepare a 2-5wt% chitosan acetic acid solution;

[0013] (2) At 35-45℃, add genipin to the chitosan acetic acid solution. The mass ratio of genipin to chitosan is 0.08-0.20:1. Stir the reaction for 2-4 hours. Genipin ketone undergoes nucleophilic addition with chitosan-NH2 to form a secondary amine bond.

[0014] (3) After the reaction is completed, tannic acid is added to the system. The mass ratio of tannic acid to chitosan is 0.02-0.05:1. The reaction is continued at 35-45℃ under nitrogen protection for 1-2 hours to obtain the reaction product. During this process, tannic acid polyphenols are tightly bound to the chitosan chain through hydrogen bonds, electrostatic interactions and hydrophobic interactions. At the same time, the tannic acid catechol / pyrogallol structure is reserved as a chelating site for metal ions.

[0015] (4) The reaction product is washed with deionized water until neutral, then vacuum dried at 50-60℃ to constant weight, and then pulverized through a 200-mesh sieve to obtain the cross-linked chitosan.

[0016] This invention also provides a method for preparing a repair solution for removing crystallization from lead-acid battery plates, comprising the following steps:

[0017] S1. Pretreatment of activated carbon: Place the activated carbon in a sealed oven and dry it at 120-150℃ for 2-3 hours. After drying, cool it to room temperature and then immerse it in a 15wt% dilute nitric acid solution. Soak it at room temperature for 1-2 hours, then pour out the acid solution and wash it with deionized water until the pH of the washing solution is 5.0-6.0. Then dry it at 105℃ to constant weight to obtain activated carbon with carboxyl groups on the surface. Seal it for later use.

[0018] S2. Preparation of active aqueous solution: Dissolve citric acid and trisodium citrate in 1 / 3 of the prescribed amount of deionized water, stir to dissolve, and obtain a buffer aqueous solution. Add phosphoric acid to the buffer aqueous solution, stir for 5-10 minutes, then add disodium EDTA, sodium sulfate and preservative, and stir at 300-500 rpm for 15-25 minutes until completely dissolved, to obtain an active aqueous solution with a pH of 4.0-5.0.

[0019] S3. Preparation of gel slurry: Mix glacial acetic acid with 1 / 3 of the remaining deionized water to obtain an acetic acid aqueous solution. Then add cross-linked chitosan to the acetic acid aqueous solution and stir at 40-50℃ for 30-60 minutes to allow it to fully swell and disperse evenly to obtain a gel slurry.

[0020] S4. Mixing and Compounding: Add the activated carbon obtained in S1 to the activated aqueous solution obtained in S2, and stir at 200-400 rpm for 10-15 minutes to disperse it evenly. Then add the gel slurry obtained in S3, and continue stirring at 200-400 rpm for 10-15 minutes. At the same time, perform ultrasonic treatment with a power of 200-400W. The ultrasonic treatment is intermittent (2 seconds of ultrasonic treatment followed by 8 seconds of pause), with a total ultrasonic treatment time of 8-12 minutes, so that the ammonium ions (-NH3) on the cross-linked chitosan molecular chains are protonated. + ) and the carboxylate ions (-COO) ionized on the surface of activated carbon - Electrostatic self-assembly and coating occur, forming a core-shell structure with activated carbon as the core and cross-linked chitosan as the shell;

[0021] S5. Volume Adjustment and Homogenization: After ultrasonication, replenish the volume with the remaining deionized water, and stir at 200-300 rpm for 10-15 minutes to obtain the repair solution for removing crystals from lead-acid battery plates.

[0022] The present invention also provides a method for removing crystals from lead-acid battery plates using the above-mentioned repair solution, comprising the following steps:

[0023] (a) Discharge the lead-acid battery to be repaired to the termination voltage, open the vent valve, and extract 30%-50% of the old electrolyte from the battery.

[0024] (b) Inject the above-mentioned repair solution into each cell of the battery. The amount injected is the same as the volume of electrolyte extracted. After sealing the vent, place the battery in a constant temperature environment of 40-50℃ for 3-5 hours to allow the repair solution to fully penetrate into the plates.

[0025] (c) After the settling period, perform 3-5 charge-discharge cycles according to the conventional lead-acid battery charge-discharge system to trigger the desulfurization effect of the repair solution through the electrochemical reaction during the charging process.

[0026] (d) After the charge-discharge cycle is completed, drain the internal liquid from the battery and inject fresh liquid with a specific gravity of 1.28 g / cm³. 3 The sulfuric acid electrolyte was charged to full capacity with a current of 0.1C to complete the repair.

[0027] Furthermore, the lead-acid battery to be repaired in step (a) is a failed battery with a capacity decay of ≥30% due to sulfation.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] (1) This invention breaks through the technical bottleneck of easy agglomeration and sedimentation of traditional activated carbon through physical mixing. By subjecting activated carbon to nitric acid oxidation treatment, carboxyl groups (-COOH) are enriched on its surface. Under weakly acidic conditions, the carboxyl groups ionize into -COO. - By imbuing activated carbon with a negative charge, chemical anchoring sites are provided for subsequent electrostatic self-assembly. The modified activated carbon can serve as an anchoring substrate to participate in the construction of subsequent core-shell structures, fundamentally solving the problem of activated carbon agglomeration and deactivation due to lack of surface activity in traditional physical mixing, and fully utilizing its high conductivity and adsorption properties.

[0030] (2) This invention overcomes the limitations of conventional repair solutions that rely solely on EDTA and dissolve Pb. 2+ The system is limited by the tendency for lead sulfate to redeposit into large crystals. In this system, disodium EDTA and phosphate synergistically complex and dissolve lead sulfate on the electrode surface, releasing Pb. 2+ It is then efficiently targeted and captured by the tannic acid polyphenol chelating nodes carried by the cross-linked chitosan in the core-shell structure, significantly reducing the free Pb in the liquid phase. 2+ The local concentration continuously drives the dissolution equilibrium in a positive direction, thus preventing Pb from being released at the source. 2+ Secondary crystallization deposition achieves deep desulfurization.

[0031] (3) This invention cleverly utilizes the steric hindrance of cross-linked chitosan and the interfacial film-forming properties of phosphoric acid to achieve long-term protection. After the fresh active lead is reduced by charge-discharge cycles, the phosphoric acid in the repair solution forms a passivation film on the lead surface, while the core-shell structured chitosan gel network forms a physical barrier on the electrode surface. The two work synergistically to allow H+ in the electrolyte to pass through. + It allows free passage to maintain normal electrochemical reactions and effectively prevents the secondary growth of large lead sulfate particles.

[0032] (4) The raw materials used in this invention are all based on existing conventional commercial safe chemicals, without introducing highly corrosive or toxic substances. The preparation process is simple and scientifically rigorous. Moreover, the repair solution does not cause corrosive damage to the battery plates and casing, is suitable for various specifications of lead-acid batteries, and has good prospects for industrial promotion and application value. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0035] Unless otherwise specified, all materials used in the following implementations are commercially available analytical or chemically pure reagents. Specifically, the degree of deacetylation of chitosan is ≥90%; the purity of genipin is ≥98%; the tannic acid is analytical grade; and the activated carbon is powdered wood-based activated carbon with a particle size of 100-300 mesh.

[0036] Preparation Example 1: This preparation example provides a method for preparing cross-linked chitosan, specifically as follows:

[0037] (1) Dissolve 10g of chitosan with a degree of deacetylation ≥90% in 500mL of 2wt% acetic acid aqueous solution to prepare a 2wt% chitosan acetic acid solution;

[0038] (2) At 35°C, 0.8 g of genipin was added to the chitosan acetic acid solution. The mass ratio of genipin to chitosan was 0.08:1. The mixture was stirred for 2 hours. Genipin ketone and chitosan-NH2 underwent nucleophilic addition to form a secondary amine bond.

[0039] (3) After the reaction is complete, 0.2g of tannic acid is added to the system. The mass ratio of tannic acid to chitosan is 0.02:1. The reaction is continued at 35°C under nitrogen protection for 1 hour to obtain the reaction product.

[0040] (4) The reaction product was washed with deionized water until neutral, then dried under vacuum at 50°C to constant weight, and then pulverized through a 200-mesh sieve to obtain the cross-linked chitosan.

[0041] Preparation Example 2: This preparation example provides a method for preparing cross-linked chitosan, specifically as follows:

[0042] (1) Dissolve 10g of chitosan with a degree of deacetylation ≥90% in 285mL of 2wt% acetic acid aqueous solution to prepare a 3.5wt% chitosan acetic acid solution;

[0043] (2) At 40°C, 1.4 g of genipin was added to the chitosan acetic acid solution, with a mass ratio of genipin to chitosan of 0.14:1, and the mixture was stirred for 3 hours.

[0044] (3) After the reaction is complete, 0.35g of tannic acid is added to the system. The mass ratio of tannic acid to chitosan is 0.035:1. The reaction is continued at 40℃ under nitrogen protection for 1.5 hours to obtain the reaction product.

[0045] (4) The reaction product was washed with deionized water until neutral, then dried under vacuum at 55°C to constant weight, and then pulverized through a 200-mesh sieve to obtain the cross-linked chitosan.

[0046] Preparation Example 3: This preparation example provides a method for preparing cross-linked chitosan, specifically as follows:

[0047] (1) Dissolve 10g of chitosan with a degree of deacetylation ≥90% in 200mL of 2wt% acetic acid aqueous solution to prepare a 5wt% chitosan acetic acid solution;

[0048] (2) At 45°C, 2.0 g of genipin was added to the chitosan acetic acid solution, with a mass ratio of genipin to chitosan of 0.20:1, and the mixture was stirred for 4 hours.

[0049] (3) After the reaction is complete, 0.5g of tannic acid is added to the system. The mass ratio of tannic acid to chitosan is 0.05:1. The reaction is continued at 45°C under nitrogen protection for 2 hours to obtain the reaction product.

[0050] (4) The reaction product was washed with deionized water until neutral, then dried under vacuum at 60°C to constant weight, and then pulverized through a 200-mesh sieve to obtain the cross-linked chitosan.

[0051] Example 1: This example provides a repair solution for removing crystallization from lead-acid battery plates, comprising the following raw materials in parts by weight: 88 parts deionized water, 0.4 parts sodium sulfate, 0.2 parts phosphoric acid, 0.3 parts disodium EDTA, 0.6 parts activated carbon, 0.2 parts preservative, 0.1 parts cross-linked chitosan, 0.05 parts citric acid, 0.03 parts trisodium citrate, and 0.05 parts glacial acetic acid; the preservative is sodium benzoate; the cross-linked chitosan is the product obtained in Preparation Example 1.

[0052] This embodiment also provides a method for preparing a repair solution for removing crystallization from lead-acid battery plates, comprising the following steps:

[0053] S1. Pretreatment of activated carbon: Place 100-mesh wood-based activated carbon in a sealed oven and dry at 120°C for 2 hours. After drying, cool to room temperature and then immerse in a 15wt% dilute nitric acid solution. After soaking at room temperature for 1 hour, pour out the acid solution and wash with deionized water until the pH of the washing solution is 5.0. Then dry at 105°C to constant weight to obtain activated carbon with carboxyl groups on the surface. Seal and store for later use.

[0054] S2. Preparation of active aqueous solution: Dissolve 0.05 parts of citric acid and 0.03 parts of trisodium citrate in 1 / 3 of the prescribed amount of deionized water, stir to dissolve, and obtain a buffer aqueous solution. Add 0.2 parts of phosphoric acid to the buffer aqueous solution, stir for 5 minutes, then add 0.3 parts of disodium EDTA, 0.4 parts of sodium sulfate and 0.2 parts of sodium benzoate, and stir at 300 rpm for 15 minutes until completely dissolved to obtain an active aqueous solution with a pH of 4.0.

[0055] S3. Preparation of gel slurry: Mix 0.05 parts of glacial acetic acid with 1 / 3 of the remaining deionized water to obtain an acetic acid aqueous solution. Then add 0.1 parts of cross-linked chitosan to the acetic acid aqueous solution and stir at 40°C for 30 minutes to allow it to fully swell and disperse evenly to obtain a gel slurry.

[0056] S4. Mixing and compounding: Add 0.6 parts of the activated carbon obtained in S1 to the activated aqueous solution obtained in S2, stir at 200 rpm for 10 minutes to disperse evenly, then add the gel slurry obtained in S3, continue stirring at 200 rpm for 10 minutes, and simultaneously perform ultrasonic treatment with a power of 200W. The ultrasonic treatment is intermittent (2 seconds of ultrasonic treatment / 8 seconds of pause), with a total ultrasonic time of 8 minutes.

[0057] S5. Volume Adjustment and Homogenization: After ultrasonication, replenish the volume with the remaining deionized water, and stir at 200 rpm for 10 minutes to obtain the repair solution for removing crystals from lead-acid battery plates.

[0058] Example 2: This example provides a repair solution for removing crystallization from lead-acid battery plates, comprising the following raw materials in parts by weight: 91 parts deionized water, 0.7 parts sodium sulfate, 0.35 parts phosphoric acid, 0.55 parts disodium EDTA, 0.9 parts activated carbon, 0.5 parts preservative, 0.25 parts cross-linked chitosan, 0.10 parts citric acid, 0.06 parts trisodium citrate, and 0.10 parts glacial acetic acid; the preservative is potassium sorbate; the cross-linked chitosan is the product obtained in Preparation Example 2.

[0059] This embodiment also provides a method for preparing a repair solution for removing crystallization from lead-acid battery plates, comprising the following steps:

[0060] S1. Pretreatment of activated carbon: Place 200-mesh wood-based activated carbon in a sealed oven and dry at 135°C for 2.5 hours. After drying, cool to room temperature and then immerse in a 15wt% dilute nitric acid solution. Soak at room temperature for 1.5 hours, then pour out the acid solution and wash with deionized water until the pH of the washing solution is 5.5. Then dry at 105°C to constant weight to obtain activated carbon with carboxyl groups on the surface. Seal and store for later use.

[0061] S2. Preparation of active aqueous solution: Dissolve 0.10 parts of citric acid and 0.06 parts of trisodium citrate in 1 / 3 of the prescribed amount of deionized water, stir to dissolve, and obtain a buffer aqueous solution. Add 0.35 parts of phosphoric acid to the buffer aqueous solution, stir for 7 minutes, then add 0.55 parts of disodium EDTA, 0.7 parts of sodium sulfate and 0.5 parts of potassium sorbate, and stir at 400 rpm for 20 minutes until completely dissolved to obtain an active aqueous solution with a pH of 4.5.

[0062] S3. Preparation of gel slurry: Mix 0.10 parts of glacial acetic acid with 1 / 3 of the remaining deionized water to obtain an acetic acid aqueous solution. Then add 0.25 parts of cross-linked chitosan to the acetic acid aqueous solution and stir at 45°C for 45 minutes to allow it to fully swell and disperse evenly to obtain a gel slurry.

[0063] S4. Mixing and compounding: Add 0.9 parts of the activated carbon obtained in S1 to the activated aqueous solution obtained in S2, stir at 300 rpm for 12.5 minutes to disperse evenly, then add the gel slurry obtained in S3, continue stirring at 300 rpm for 12.5 minutes, and simultaneously perform ultrasonic treatment with a power of 300W. The ultrasonic treatment is intermittent (2 seconds of ultrasonic treatment / 8 seconds of pause), with a total ultrasonic time of 10 minutes.

[0064] S5. Volume Adjustment and Homogenization: After ultrasonication, replenish the volume with the remaining deionized water and stir at 250 rpm for 12.5 minutes to obtain the repair solution for removing crystallization from lead-acid battery plates.

[0065] Example 3: This example provides a repair solution for removing crystallization from lead-acid battery plates, comprising the following raw materials in parts by weight: 94 parts deionized water, 1.0 part sodium sulfate, 0.5 parts phosphoric acid, 0.8 parts disodium EDTA, 1.2 parts activated carbon, 0.8 parts preservative, 0.4 parts cross-linked chitosan, 0.15 parts citric acid, 0.10 parts trisodium citrate, and 0.15 parts glacial acetic acid; the preservative is a mixture of sodium benzoate and potassium sorbate in a 1:1 mass ratio; the cross-linked chitosan is the product obtained in Preparation Example 3.

[0066] This embodiment also provides a method for preparing a repair solution for removing crystallization from lead-acid battery plates, comprising the following steps:

[0067] S1. Pretreatment of activated carbon: Place 300-mesh wood-based activated carbon in a sealed oven and dry at 150°C for 3 hours. After drying, cool to room temperature and then immerse it in a 15wt% dilute nitric acid solution. After soaking at room temperature for 2 hours, pour out the acid solution and wash with deionized water until the pH of the washing solution is 6.0. Then dry at 105°C to constant weight to obtain activated carbon with carboxyl groups on the surface. Seal and store for later use.

[0068] S2. Preparation of active aqueous solution: Dissolve 0.15 parts of citric acid and 0.10 parts of trisodium citrate in 1 / 3 of the prescribed amount of deionized water, stir to dissolve, and obtain a buffer aqueous solution. Add 0.5 parts of phosphoric acid to the buffer aqueous solution, stir for 10 minutes, then add 0.8 parts of disodium EDTA, 1.0 part of sodium sulfate and 0.8 parts of preservative, and stir at 500 rpm for 25 minutes until completely dissolved to obtain an active aqueous solution with a pH of 5.0.

[0069] S3. Preparation of gel slurry: Mix 0.15 parts of glacial acetic acid with 1 / 3 of the remaining deionized water to obtain an acetic acid aqueous solution. Then add 0.4 parts of cross-linked chitosan to the acetic acid aqueous solution and stir at 50°C for 60 minutes to allow it to fully swell and disperse evenly to obtain a gel slurry.

[0070] S4. Mixing and compounding: Add 1.2 parts of the activated carbon obtained in S1 to the activated aqueous solution obtained in S2, stir at 400 rpm for 15 minutes to disperse evenly, then add the gel slurry obtained in S3, continue stirring at 400 rpm for 15 minutes, and at the same time supplement with ultrasonic treatment at 400W power. The ultrasonic treatment is intermittent (2 seconds of ultrasonic treatment / 8 seconds of pause), with a total ultrasonic time of 12 minutes.

[0071] S5. Volume Adjustment and Homogenization: After ultrasonication, replenish the volume with the remaining deionized water and stir at 300 rpm for 15 minutes to obtain the repair solution for removing crystals from lead-acid battery plates.

[0072] Example 4: This example provides a repair solution for removing crystallization from lead-acid battery plates, comprising the following raw materials by weight: 91 parts deionized water, 0.7 parts sodium sulfate, 0.3 parts phosphoric acid, 0.8 parts disodium EDTA, 0.9 parts activated carbon, 0.5 parts preservative, 0.25 parts cross-linked chitosan, 0.10 parts citric acid, 0.06 parts trisodium citrate, and 0.10 parts glacial acetic acid; the preservative is sodium benzoate; the cross-linked chitosan is the product obtained in Preparation Example 2.

[0073] This embodiment also provides a method for preparing a repair solution for removing crystallization from lead-acid battery plates, comprising the following steps:

[0074] S1. Pretreatment of activated carbon: Place 200-mesh wood-based activated carbon in a sealed oven and dry at 135°C for 2.5 hours. After drying, cool to room temperature and then immerse in a 15wt% dilute nitric acid solution. Soak at room temperature for 1.5 hours, then pour out the acid solution and wash with deionized water until the pH of the washing solution is 5.5. Then dry at 105°C to constant weight to obtain activated carbon with carboxyl groups on the surface. Seal and store for later use.

[0075] S2. Preparation of active aqueous solution: Dissolve 0.10 parts of citric acid and 0.06 parts of trisodium citrate in 1 / 3 of the prescribed amount of deionized water, stir to dissolve, and obtain a buffer aqueous solution. Add 0.3 parts of phosphoric acid to the buffer aqueous solution, stir for 7 minutes, then add 0.8 parts of disodium EDTA, 0.7 parts of sodium sulfate and 0.5 parts of sodium benzoate, and stir at 400 rpm for 20 minutes until completely dissolved to obtain an active aqueous solution with a pH of 4.5.

[0076] S3. Preparation of gel slurry: Mix 0.10 parts of glacial acetic acid with 1 / 3 of the remaining deionized water to obtain an acetic acid aqueous solution. Then add 0.25 parts of cross-linked chitosan to the acetic acid aqueous solution and stir at 45°C for 45 minutes to allow it to fully swell and disperse evenly to obtain a gel slurry.

[0077] S4. Mixing and compounding: Add 0.9 parts of the activated carbon obtained in S1 to the activated aqueous solution obtained in S2, stir at 300 rpm for 12.5 minutes to disperse evenly, then add the gel slurry obtained in S3, continue stirring at 300 rpm for 12.5 minutes, and simultaneously perform ultrasonic treatment with a power of 300W. The ultrasonic treatment is intermittent (2 seconds of ultrasonic treatment / 8 seconds of pause), with a total ultrasonic time of 10 minutes.

[0078] S5. Volume Adjustment and Homogenization: After ultrasonication, replenish the volume with the remaining deionized water and stir at 250 rpm for 12.5 minutes to obtain the repair solution for removing crystallization from lead-acid battery plates.

[0079] Comparative Example 1: This comparative example provides a repair solution, which differs from Example 2 only in that: cross-linked chitosan and glacial acetic acid are not added, and steps S3 and S4 are not performed. The activated carbon obtained in S1 is directly added to the activated aqueous solution in S2 for dispersion, and then deionized water is used to make up the volume and adjust the volume. The other types and amounts of raw materials and preparation steps are the same as in Example 2.

[0080] Comparative Example 2: This comparative example provides a repair solution, which differs from Example 2 only in that: in S1, the activated carbon is not soaked in dilute nitric acid, that is, ordinary wood-based activated carbon that has not been surface carboxylated is used. The other raw materials, amounts, and preparation steps are the same as in Example 2.

[0081] Comparative Example 3: This comparative example provides a repair solution, which differs from Example 2 only in that: unmodified ordinary chitosan is used instead of the cross-linked chitosan used in Example 2, while the other raw materials, amounts, and preparation steps are the same as in Example 2.

[0082] Comparative Example 4: This comparative example provides a repair solution, which differs from Example 2 only in that: no disodium EDTA is added, while the other raw materials, dosages, and preparation steps are the same as in Example 2.

[0083] Comparative Example 5: This comparative example provides a traditional lead-acid battery repair solution, comprising the following raw materials in parts by weight: 95 parts deionized water, 0.3 parts sodium sulfate, 0.2 parts phosphoric acid, 0.2 parts disodium EDTA, 0.5 parts activated carbon, and 0.3 parts preservative (potassium sorbate); the preparation method is as follows: each raw material is directly added to deionized water and stirred at 300 rpm for 30 minutes until it is evenly dissolved.

[0084] Effect verification experiment:

[0085] [1] Experimental subjects: 45 lead-acid batteries of the same specification with capacity decay ≥30% due to sulfation (rated capacity 20Ah, initial internal resistance 18-20mΩ) were selected and randomly divided into 9 groups of 5 batteries each. These were Example 1-3, Comparative Example 1-5 and Blank Control Group. The Blank Control Group did not use repair solution and only added an equal amount of deionized water.

[0086] [2] The repair solutions prepared in Examples 1-3 and Comparative Examples 1-5 of the present invention were used to repair each battery pack. The specific repair steps are as follows:

[0087] (a) Discharge the lead-acid battery to be repaired to the termination voltage of 10.5V, open the vent valve, and extract 40% of the old electrolyte from the battery.

[0088] (b) Inject the repair solution prepared in the corresponding embodiment or comparative example into each cell of the battery. The injection volume is equal to the volume of the extracted electrolyte. After sealing the vent plug, place the battery in a constant temperature environment of 45°C for 4 hours to allow the repair solution to fully penetrate into the electrode plate.

[0089] (c) After the settling period, perform 4 charge-discharge cycles according to the conventional lead-acid battery charge-discharge system to trigger the desulfurization effect of the repair solution by utilizing the electrochemical reaction during the charging process.

[0090] (d) After the charge-discharge cycle is completed, drain the internal liquid from the battery and inject fresh liquid with a specific gravity of 1.28 g / cm³. 3 The sulfuric acid electrolyte was charged to full capacity with a current of 0.1C to complete the repair.

[0091] [3] Test items: After repair, the actual capacity and internal resistance of each battery were tested using a battery comprehensive tester; then, a 100% deep discharge cycle test was performed, and the number of cycles when the capacity dropped to 80% of the rated capacity was recorded. The service life extension rate was calculated based on the average cycle life (100 cycles) of the failed battery that was directly replaced without repair. The specific test results are shown in Table 1 below:

[0092] Table 1. Repair effects of different repair solutions on failed lead-acid batteries

[0093]

[0094] As shown in Table 1, the blank control group, treated only with deionized water, did not improve the sulfidation of the plates due to the lack of active chemical components and film protection. After repair, the capacity was only 11.2 Ah, the internal resistance remained as high as 28.6 mΩ, and the service life was essentially not extended. Comparative Example 5 used a traditional simple physical mixing scheme, where each component acted independently, failing to penetrate deeply for desulfurization and lacking a protective mechanism. After repair, the capacity only recovered to 15.5 Ah, and the service life extension rate was only 5%. Furthermore, the capacity recovery rate, internal resistance reduction, and cycle count of Comparative Examples 1-4 all showed significant declines, with service life extension rates only between 10% and 28%.

[0095] The repair solutions prepared in Examples 1-4 of this invention show significantly better repair effects on failed lead-acid batteries than the comparative examples and the blank group. Example 4 exhibits the best repair effect, with the battery capacity recovering from the initial 10.3 Ah to 19.6 Ah after repair, the internal resistance significantly decreasing to 10.9 mΩ, and the service life extended by 63%. This demonstrates that the repair solution prepared in this invention not only effectively removes existing lead sulfate crystals on the electrode surface but also forms a chelating protective layer on the electrode surface, continuously inhibiting the regeneration of lead sulfate crystals and fundamentally delaying secondary sulfation of the battery, thus achieving long-term repair.

[0096] 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.

[0097] The present invention and its embodiments have been described above. This description is not restrictive, and practical applications are not limited thereto. In conclusion, if those skilled in the art are inspired by this description and, without departing from the spirit of the invention, design similar methods and embodiments to this technical solution without creative effort, all such designs should fall within the protection scope of the present invention.

Claims

1. A repair solution for removing crystallization from lead-acid battery plates, characterized in that, The repair solution comprises the following raw materials in parts by weight: 88-94 parts deionized water, 0.4-1.0 parts sodium sulfate, 0.2-0.5 parts phosphoric acid, 0.3-0.8 parts disodium EDTA, 0.6-1.2 parts activated carbon, 0.2-0.8 parts preservative, 0.1-0.4 parts cross-linked chitosan, 0.05-0.15 parts citric acid, 0.03-0.10 parts trisodium citrate, and 0.05-0.15 parts glacial acetic acid; The cross-linked chitosan is a genipin-tannic acid composite modified chitosan, and its preparation method is as follows: (1) Dissolve chitosan in an aqueous acetic acid solution to prepare a chitosan-acetic acid solution; (2) Add genipin to the chitosan acetic acid solution and stir to react; (3) After the reaction is complete, tannic acid is added to it to carry out the reaction and obtain the reaction product; (4) The reaction product is washed until neutral, then vacuum dried, pulverized and sieved to obtain the cross-linked chitosan; The preparation method of the repair solution includes the following steps: S1. Pretreatment of activated carbon: After drying the activated carbon, cool it to room temperature, then immerse it in a dilute nitric acid solution. After soaking, pour out the acid solution, wash it with deionized water until the pH of the washing solution is 5.0-6.0, and then dry it to obtain activated carbon. S2. Preparation of active aqueous solution: Dissolve citric acid and trisodium citrate in 1 / 3 of the total deionized water to obtain a buffer aqueous solution. Add phosphoric acid to the buffer aqueous solution, stir, then add disodium EDTA, sodium sulfate and preservative, and stir until completely dissolved to obtain an active aqueous solution. S3. Gel slurry preparation: Mix glacial acetic acid with 1 / 3 of the remaining deionized water to obtain an acetic acid aqueous solution, then add cross-linked chitosan to the acetic acid aqueous solution and stir evenly to obtain a gel slurry; S4. Mixing and compounding: Add activated carbon to the activated aqueous solution and stir evenly, then add gel slurry and stir, while performing intermittent ultrasonic treatment; S5. Volume Adjustment and Homogenization: After ultrasonication, replenish the volume with the remaining deionized water, and then stir evenly to obtain the repair solution used for removing crystals from lead-acid battery plates.

2. The repair solution for removing crystallization from lead-acid battery plates according to claim 1, characterized in that, The activated carbon is powdered wood-based activated carbon with a particle size of 100-300 mesh.

3. The repair solution for removing crystallization from lead-acid battery plates according to claim 1, characterized in that, The weight ratio of disodium EDTA to phosphoric acid is 8:

3.

4. The repair solution for removing crystallization from lead-acid battery plates according to claim 1, characterized in that, The preservative is at least one of sodium benzoate and potassium sorbate.

5. The repair solution for removing crystallization from lead-acid battery plates according to claim 1, characterized in that, The mass ratio of genipin to chitosan is 0.08-0.20:1; the mass ratio of tannic acid to chitosan is 0.02-0.05:

1.

6. A method for removing crystals from lead-acid battery plates using the repair solution according to any one of claims 1-5, characterized in that, Includes the following steps: (a) Discharge the lead-acid battery to be repaired to the termination voltage, open the vent valve, and extract 30%-50% of the old electrolyte from the battery. (b) After injecting the repair fluid into each cell of the battery, let it stand; (c) After the settling period, perform 3-5 charge-discharge cycles according to the standard lead-acid battery charge-discharge procedure; (d) After the charge-discharge cycle is completed, drain the liquid inside the battery and inject sulfuric acid electrolyte to charge it to full charge with a current of 0.1C to complete the repair.

7. The method for removing crystals from lead-acid battery plates according to claim 6, characterized in that, The lead-acid battery to be repaired in step (a) is a failed battery with a capacity decay of ≥30% due to sulfation.

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