Method for repairing lead-acid storage battery by utilizing active electrolyte and reversely charging storage battery

Abstract

The invention discloses a method for repairing a lead-acid storage battery by utilizing an active electrolyte and a reverse charging storage battery, and relates to the technical field of lead-acid battery repairing. The method is suitable for regeneration of batteries with capacity fading or pole plate sulfation failure. The conversion and activation of PbSO4 crystals in a polar plate are realized by configuring an active electrolyte of a multifunctional additive and cooperating with forward and reverse constant-current alternate charging. And pulse disturbance, temperature control management and auxiliary electrode orientation mechanisms are introduced, so that a pole plate passivation layer can be thoroughly removed on the premise of not disassembling the battery, and the capacity recovery rate and the cycle life are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of lead-acid battery repair technology, specifically a method for repairing lead-acid batteries using an active electrolyte and a reverse-charge battery. Background Technology

[0002] Lead-acid batteries are widely used in electric vehicles, energy storage, and emergency backup applications due to their mature structure, low manufacturing cost, and excellent instantaneous discharge performance. However, these batteries commonly suffer from irreversible sulfation during long-term use, where the surface of the active plates is gradually covered by large, difficult-to-reduce PbSO4 particles, leading to decreased specific capacity, increased internal resistance, and ultimately premature failure. Existing repair technologies are mainly divided into physical and chemical methods. Physical methods, such as high-voltage constant-current charging or pulse charging, can temporarily increase voltage, but are prone to causing plate corrosion and water depletion due to localized overheating, and are essentially ineffective against severe sulfation. Pulse desulfurization technologies mainly rely on fixed-frequency current pulses to shatter crystals, which is only suitable for mildly passivated areas and remains ineffective against deeply deposited grains. In terms of chemical repair, current methods often use EDTA-type chelating agents, magnesium sulfate, and alkaline solutions to destroy PbSO4 crystals, but this often requires complete acid removal and repeated rinsing, which is not only complex but also leads to side effects such as continued capacity reduction and increased self-discharge due to residual chelation. Furthermore, most existing technologies only consider the reduction pathway of lead sulfate (PbSO4→Pb), neglecting to utilize its reverse pathway of oxidation and transformation at the negative electrode, thus failing to fully realize the potential of the electrochemical reversibility of the lead-acid system. Existing processes generally lack a full-process temperature control mechanism and cannot achieve targeted enhanced repair of severely sulfided negative electrodes. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides the following technical solution: a method for repairing lead-acid batteries using an active electrolyte and a reverse-charge battery, comprising the following steps: S1, discharging the battery to be repaired at 0.05-0.20C until the terminal voltage is close to 0V; S2, draining at least 80% of the original electrolyte and injecting an active electrolyte, wherein the active electrolyte contains, per liter of solution: 1-5g of organic ligand, 1-4g of MgSO4, 1-5g of Na2SO4, and Sn. 2+ 0.2-0.8g, Bi 3+ 0.5-2g, Co 2+0.2-0.8g, H3PO4 3-6g, deionized water as the equilibrium solvent; S3, let stand for 0.5-1h; S4, charge at a constant current of 0.05-0.20C to 2.35-2.45V of the single cell according to the normal polarity of the battery; S5, after power off, reverse the polarity and charge at a constant current of 0.05-0.15C to 1.90-2.20V of the single cell; S6, repeat steps S4-S5 2-4 times; S7, restore normal polarity and charge at a constant voltage of 2.40V / division until the current ≤0.01C; S8, adjust the specific gravity of the electrolyte to 1.25–1.28g·cm³. -3 After sealing and allowing it to stand and balance, the capacity was tested by discharging at 0.1C.

[0004] Preferably, the organic ligand is glycerol, and the addition amount is 2-4 g / L.

[0005] Preferably, during the constant current charging process in steps S4 and S5, a narrow pulse current with an amplitude of 5-50% of the main charging current or an ultrasonic vibration of 20-40kHz is superimposed to accelerate ion migration and crystal stripping.

[0006] Preferably, during reverse charging in step S5, an inert auxiliary electrode is placed in the electrolyte, and the negative terminal of the charging power supply is connected to the auxiliary electrode to directionally oxidize the negative electrode PbSO4.

[0007] Preferably, the battery casing temperature is controlled to be ≤40℃ throughout the entire process from step S1 to step S6 and monitored in real time. If the temperature exceeds the threshold, the charging current is automatically reduced or charging is paused.

[0008] Preferably, 10-30% of the original electrolyte is retained in step S2 to maintain the mass balance of sulfate and reduce acid overshoot.

[0009] Preferably, the number of cycles in step S6 is selected based on the remaining capacity of the battery before discharge: 3-4 cycles when the remaining capacity is less than 40% of the rated capacity, and 2 cycles when the remaining capacity is greater than 50%.

[0010] Preferably, for sealed valve-regulated lead-acid batteries, step S2 involves electrolyte replacement via microneedle injection or valve orifice injection, and step S8 involves sealing the valve orifice with flame-retardant epoxy.

[0011] Preferably, after the terminal constant voltage charging is completed in step S7, the device is left to stand for 2-4 hours. If the total voltage drops by more than 3%, a 0.05C constant current supplementary charging is performed for 1-3 hours to ensure that the active material is fully restored.

[0012] A regeneration system for implementing a lead-acid battery repair method using an active electrolyte and a reverse-charge battery includes: a programmable constant current / constant voltage charge / discharge power supply module for performing deep discharge, forward constant current charging, reverse constant current charging, and terminal constant voltage charging; an electrolyte extraction and injection module for extracting old acid and injecting active electrolyte; a temperature and pressure monitoring module for real-time detection and feedback control of the charging current; and a controller and human-machine interface for storing and recalling the process parameters of the above steps to achieve an automated regeneration process.

[0013] Compared with the prior art, the present invention has the following advantages: (1) The present invention achieves complete conversion of large-particle, dense-structured lead sulfate on the electrode plate by combining active electrolyte and forward and reverse constant current charging strategies, avoiding the problem that traditional forward charging is difficult to penetrate the passivation layer. In the closed-loop path of PbSO4→PbO2→Pb, the negative electrode PbSO4, which is originally difficult to reduce, is converted back into active material after oxidation, and then recovered in the next round of forward charging, effectively restoring the original capacity, especially suitable for heavily sulfated lead-acid batteries; (2) The present invention adopts low-rate constant current, temperature control ≤40℃, and avoids high-voltage and high-current impact throughout the process, reducing the risk of electrode plate corrosion, electrolyte decomposition and explosive gas release. At the same time, through the temperature and pressure monitoring module, real-time feedback and intelligent adjustment are realized to ensure the stability of the process and the safe operation of the equipment, solving the common thermal runaway problem in the existing repair methods; (3) The organic ligand, disulfate and metal catalytic ions in the active electrolyte of the present invention work together to effectively dissolve or replace Pb in the passivation crystal. 2+ Meanwhile, under repeated positive and negative current action, a micro-catalytic layer is formed and stabilized on the electrode plate surface, improving the charging acceptance and sulfation resistance. Combined with positive-reverse cycle and pulse perturbation, the ion migration and crystal stripping are more thorough, enhancing the overall repair effect; (4) Compared with the traditional chemical method that requires disassembly, rinsing, and remixing of acid solution, this invention adopts an integrated process of liquid injection-static-charge-discharge, which is suitable for VRLA sealed batteries and open batteries, and has good batch operation compatibility. The materials used are inexpensive and non-toxic, and do not require cleaning or neutralization treatment after repair, which meets the actual needs of battery repair shops and green production standards, and has the basis for promotion and standardization implementation; (5) This invention introduces an inert auxiliary electrode, so that the current is concentrated on the negative electrode plate during reverse charging, thereby directionally strengthening the oxidation conversion process of negative electrode PbSO4. This measure is especially suitable for the repair of large-capacity single cells and deeply passivated batteries, which can avoid the side effects caused by excessive reduction of positive electrode material to the greatest extent. It is the first time that a directional action mechanism has been realized in the existing electrochemical repair path, which has outstanding technical progress. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0015] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0016] This invention provides 1. A method for repairing lead-acid batteries using an active electrolyte and a reverse-charge battery, comprising the following steps: S1, discharging the battery to be repaired at 0.05-0.20C until the terminal voltage is close to 0V; S2, draining at least 80% of the original electrolyte and injecting an active electrolyte, wherein the active electrolyte contains, per liter of solution: 1-5g of organic ligand (preferably 2-4g of glycerol), disulfate (1-4g of MgSO4 + 1-5g of Na2SO4), and metal catalyst (Sn). 2+ 0.2-0.8g, Bi 3+ 0.5-2g, Co 2+ 0.2-0.8g), buffer stabilizer (H3PO4 3-6g), equilibrium solvent is deionized water (pH 1 < pH < 2.5); S3, let stand for 0.5-1h; S4, charge at a constant current of 0.05-0.20C to 2.35-2.45V of the single cell according to the normal polarity of the battery; S5, after power off, reverse the polarity and charge at a constant current of 0.05-0.15C to 1.90-2.20V of the single cell; In heavily sulfated lead-acid batteries, the sulfuric acid at the negative electrode The lead (PbSO4) layer has a dense structure, and normal forward charging cannot completely reduce it to metallic lead. If the current is reversed, the original negative electrode becomes the anode, at which point PbSO4 undergoes an oxidation reaction to generate PbO2. PbO2 is more reactive and has a looser structure than PbSO4, making it easier to convert to metallic lead in the next normal charge. At the same time, the PbSO4 on the original positive electrode will be reduced to Pb (metallic lead) during reverse charging, and then restored to PbO2 through subsequent forward charging. Reverse charging to 1.90–2.20V per cell refers to controlling the voltage of each individual cell (i.e., the voltage of a 2V battery cell) under reverse polarity connection. The voltage increase indicates that the electrode reaction is in progress, and lead sulfate is being oxidized or reduced. Controlling the voltage within this range ensures that the reaction proceeds effectively, prevents overheating or excessive gas evolution, and prevents damage to the battery plates due to overcharging. S6. Repeat steps S4-S5 2-4 times; S7. Restore normal polarity and charge at a constant voltage of 2.40V / division until the current ≤0.01C; S8. Adjust the electrolyte specific gravity to 1.25–1.28 g·cm³. -3 After sealing and allowing it to stand for equilibrium, the capacity is tested by discharging at 0.1C. The electrolyte density (specific gravity) is measured using a densitometer. If it deviates from the target value (1.25–1.28 g / cm³), the capacity is not considered. 3If the specific gravity is not properly adjusted, fine-tune it by adding concentrated sulfuric acid or deionized water. After adjusting the specific gravity, replace the filling cap or seal the safety valve to ensure the battery is sealed (especially for VRLA lead-acid batteries). After sealing, let it stand for several hours until the electrolyte and plates are fully rebalanced and the internal ion distribution is stable. Finally, discharge the battery at 0.1C (i.e., 10% of the rated capacity) to test its capacity recovery effect.

[0017] The working principle of active electrolyte: Its core is to add a variety of functional additives to deionized water, so that the electrolyte not only provides an ion-conducting medium, but also participates in and promotes the conversion of lead sulfate on the electrode plate.

[0018] Organic ligands (such as polyols or organic acids like glycerol): with Pb 2+ Coordination is formed, increasing the solubility of PbSO4, refining the grain size, and increasing the electrolyte viscosity to improve ion transport stability. For example, adding about 1–4 g of glycerol per liter of electrolyte helps activate the electrode plates.

[0019] Sulfate additives (such as magnesium sulfate MgSO4, anhydrous sodium sulfate Na2SO4): provide inert cations, promoting the transfer of lead sulfate into the solution through ion exchange. Mg 2+ Na + It can displace Pb in PbSO4 by entering the electrode pores. 2+ This process dissolves the large, insoluble PbSO4 particles, gradually converting them back into a chargeable state (the sulfate ions return to the electrolyte to become active sulfuric acid).

[0020] Metal ion catalysts (such as stannous sulfate SnSO4, bismuth trioxide Bi2O3 dissolved Bi) 3+ / BiO + (Ions, Cobalt Sulfate): During repeated charge-discharge cycles, these metal ions deposit in trace amounts on the electrode surface, acting as electrochemical catalysts and crystal nuclei. For example, bismuth and tin doping can improve the negative electrode's charge acceptance and suppress recrystallization; introducing approximately 0.05–0.1% (wt) of bismuth into the negative electrode helps improve charging efficiency and cycle life. Cobalt ions, on the other hand, can form Co at the positive electrode. 4+ The oxide microlayer reduces the oxygen evolution overpotential and improves the utilization rate of active materials. ppm-level Sn is introduced through the electrolyte. 2+ Bi 3+ Co 2+ This allows for in-situ modification, thereby delaying the re-sulfation that occurs after repair.

[0021] Buffer stabilizers (such as phosphoric acid H3PO4): A small amount of phosphate ions in solution can react with lead to form insoluble lead phosphate, inhibiting excessive crystal growth of PbSO4 and thus improving its crystal structure. Phosphoric acid additives are commonly used in industrial battery life-extending formulations to form a fine and stable active material structure. Their concentration should be controlled within a few grams per liter to avoid excessively reducing battery capacity.

[0022] The components of the active electrolyte work synergistically to gradually activate the inert lead sulfate on the old battery plates: some dissolve into ions that can participate in the reaction, and some are converted into compounds with higher valence states, preparing for the next charging conversion. It should be noted that most of these additives do not participate in irreversible side reactions and can be retained in the battery after the repair is completed to continue to play an anti-sulfation role without producing harmful residues or pollution.

[0023] The principle of reverse charging mechanism: During the repair process, a charging current with the opposite polarity to the normal polarity is applied to the battery (i.e., the positive and negative terminals of the battery are reversed when connecting to the charger) or a pulsed reverse current is applied. The purpose is to utilize the reversibility of electrochemical reactions to reactivate the plates from another direction, especially for the negative electrode, lead sulfate, which is difficult to reduce with traditional forward charging. The principle can be divided into two aspects: Lead sulfate oxidation at the negative electrode: During discharge of a lead-acid battery, the negative electrode (Pb) is oxidized to PbSO4. Due to the low reactivity of the generated PbSO4 crystals, it is difficult to reduce them to sponge lead during normal charging. By reversing the charging process, the original negative electrode is used as the anode in the charging circuit, and the reaction direction is reversed—the low-activity PbSO4 is further oxidized to PbO2 (accompanied by a small amount of oxygen evolution). This process is similar to converting the stubborn lead sulfate on the negative electrode into a higher valence state of lead dioxide. PbO2 has greater reactivity and specific surface area than PbSO4, and is subsequently easily reduced to sponge lead during forward charging, thus completely removing the sulfation of the negative electrode. Expressed as a formula: The electrochemical equation for the PbSO4→PbO2 conversion at the original negative electrode is: PbSO4 (solid)+2H2O→PbO2+HSO4 - +3H + +2e - ; The sulfate ions released from the anodic oxidation reaction enter the electrolyte and are converted back into an active electrolyte.

[0024] Lead sulfate reduction at the positive electrode: Similarly, during reverse charging, the original positive electrode (PbO2 becomes PbSO4 after discharge) is connected to the cathode of the charging circuit. Since PbSO4 can be directly reduced to sponge lead (Pb) at the cathode, this means that some of the original positive electrode lead sulfate will be converted into elemental lead and adhere to the electrode plate (effectively causing localized negative polarization of the original positive electrode). Although this temporarily changes the chemical state of the electrode material, these deposited lead deposits will be oxidized back to PbO2 during subsequent forward charging, completing one cycle. Through this cathode reduction pathway, large PbSO4 grains adhering to the surface of the positive electrode can also be eliminated. This process has little impact on the structure of the positive electrode active material because the positive electrode PbSO4 itself is easily converted to PbO2 during normal charging.

[0025] In summary, the reverse charging mechanism is equivalent to attacking lead sulfate from two opposite directions: on the one hand, it oxidizes the difficult-to-reduce PbSO4 at the negative electrode, and on the other hand, it reduces the residual PbSO4 at the positive electrode, ultimately restoring both to their original states. After using the reverse charging method, the original large-particle lead sulfate at the negative electrode disappears, and the repair capacity can be restored to 85-95% of the rated capacity. This mechanism effectively bypasses the difficult step of directly converting PbSO4 back to Pb, instead following the PbSO4→PbO2→Pb path to improve conversion efficiency.

[0026] Improve repair efficiency and uniformity: Pulse and polarity switching charging: Compared to constant DC, this invention uses narrow pulse current superposition or periodically alternating forward / reverse current to further disturb the concentration layer and crystals on the electrode surface. Specifically, during the main constant current charging phase, high-frequency, small-amplitude current pulses are superimposed, or the current direction is briefly switched every few minutes (e.g., alternating between 5 minutes of forward charging and 30 seconds of reverse charging). This pulse polarity strategy generates micro-vibrations and ion disturbances, which helps to strip lead sulfate crystals and promotes the penetration of additive ions. It should be noted that the pulse / switching parameters need to be optimized to avoid side reactions caused by excessive inrush current or frequent switching. The pulse amplitude should not exceed 50% of the main charging current, and the switching frequency should ideally be a few minutes per cycle to maximize the desulfurization effect while ensuring safety.

[0027] Ultrasonic / Vibration Assistance (Optional): For severely sulfated batteries, ultrasonic vibration can be applied during charging (by placing the battery in an ultrasonic water bath or immersing an acid-resistant ultrasonic probe in the electrolyte). The cavitation effect generated by ultrasound in the liquid can physically break up and peel off the PbSO4 crystals on the electrode surface, enhancing the penetration of the electrolyte into the electrode pores. Under the combined action of the active electrolyte and current, ultrasonic assistance is expected to significantly shorten the repair time. This step requires careful control of the ultrasonic power and duration to avoid damaging the active material structure of the electrode. However, appropriate mechanical disturbance is a beneficial physical means for electrodes with thicker deposition layers, accelerating the chemical reaction.

[0028] A combination of chemical activation and electrochemical reversal is used: first, lead sulfate is softened and dissolved using an active electrolyte, then it is converted into a reversible active substance from different directions using a reverse current. Glycerol is used as the organic ligand, added at a concentration of 2-4 g / L. During the constant current charging process in steps S4 and S5, a narrow pulse current with an amplitude of 5-50% of the main charging current or ultrasonic vibration at 20-40 kHz is superimposed to accelerate ion migration and crystal exfoliation. During reverse charging in step S5, an inert auxiliary electrode is placed in the electrolyte, and the negative terminal of the charging power supply is connected to the auxiliary electrode to directionally oxidize the negative electrode PbSO4. Throughout steps S1-S6, the battery casing temperature is controlled to ≤40℃ and monitored in real time. If the temperature exceeds the threshold, the charging current is automatically reduced or charging is paused. In step S2, 10-30% of the original electrolyte is retained to maintain sulfate mass conservation and reduce acid overshoot. The number of cycles in step S6 is selected based on the remaining battery capacity before discharge: 3-4 cycles when the remaining capacity is below 40% of the rated capacity, and 2 cycles when the remaining capacity is above 50%. For sealed valve-regulated lead-acid batteries, electrolyte replacement is completed in step S2 using microneedle injection or valve orifice injection, and the valve orifice is sealed with flame-retardant epoxy in step S8. After the terminal constant voltage charging is completed in step S7, the battery is allowed to stand for 2-4 hours. If the total voltage drops by more than 3%, a 0.05C constant current supplementary charge is performed for 1-3 hours to ensure complete recovery of the active materials.

[0029] Repair process: Initial inspection and preparation: Clean the exterior of the battery to be repaired and check for any irreparable mechanical faults such as deformation, cracks, or internal short circuits. Confirm that the battery is not leaking and that the terminals are intact.

[0030] Pre-discharge (deep discharge): Perform a deep discharge of the battery to near 0 volts (approximately 0V per cell). A high-power resistor or DC electronic load can be used to continuously discharge at a current of 0.1–0.2C until the battery voltage drops to near 0 (for multi-cell batteries, monitor each cell individually to ensure each cell is as completely discharged as possible). Deep discharge converts as many plates as possible to lead sulfate, creating conditions for subsequent activation. At the end of the discharge, the battery voltage is very low; prolonged periods of reverse polarity (negative voltage in a cell) should be avoided. Discharge should only be stopped when the voltage reaches approximately 0V.

[0031] Used electrolyte disposal: Carefully remove the battery's filler cap or valve (for sealed batteries, pry open the valve's rubber stopper). Use a plastic suction pump to extract and collect as much of the used electrolyte as possible from inside the battery. Measure and record its density (specific gravity) and volume. Do not discard the used acid directly; it can be disposed of in the following two ways: Clarification and Reuse – Allow the extracted old acid to settle or filter to remove precipitates and impurities for later use. If the old acid concentration is acceptable (>1.20 g / cm³), it can be reused. 3This can be used in subsequent processes to adjust the final electrolyte concentration to reduce waste. Otherwise, it should be left for centralized neutralization and disposal.

[0032] Moderate Retention – If complete drainage is inconvenient, a small amount of the original acid solution can be retained in the battery (e.g., 20% by volume). This will mix with the newly added active electrolyte. This helps retain some of the original sulfuric acid content in the battery, preventing the final acidity from becoming too low. However, care should be taken to reduce the volume appropriately when adding the active electrolyte later.

[0033] Adding the active electrolyte: Prepare the active electrolyte according to the formula designed in this scheme. Using a graduated cylinder and a precision balance, take the above components (e.g., glycerol 3g / L, MgSO4 2g / L, Na2SO4 3g / L, Bi2O3 1.5g / L, SnSO4 0.5g / L, H3PO4 4g / L, CoSO4 0.5g / L; the actual ratio can be slightly adjusted within this range) into a clean container, and dissolve them completely in an appropriate amount of deionized water with stirring. Do not use metal containers to avoid leaching impurities. Then, pour the prepared active electrolyte into each cell of the battery, ensuring the liquid level covers the plates and mixes thoroughly with the original residual liquid. At this point, the electrolyte concentration in the battery is relatively low (only about 1.10 specific gravity, as most of the sulfuric acid remains in the plates as PbSO4), but this is beneficial for the subsequent conversion of lead sulfate into the solution. Twist or gently shake the battery to release air bubbles in the gaps between the grids and separators, ensuring that the active electrolyte completely wets the plates.

[0034] Activation soaking (static pretreatment): After injecting the active electrolyte, let the battery stand for about 0.5 to 1 hour to allow the additives to fully penetrate the pores of the plates and begin to react with PbSO4 (some complex crystals slowly dissolve or exchange into other salts). No load needs to be connected during the standing period to allow the battery to naturally equalize. If possible, small current pulses (such as short pulses below 0.05C) can be applied intermittently to the battery to enhance ion penetration, but overall, significant heat generation or gas production should be avoided.

[0035] Forward constant current charging (Stage 1): Connect the charging equipment, connect the wires according to the battery's nominal voltage and normal polarity, and begin the first forward constant current charging. The initial current should be relatively small (approximately 0.1C) to prevent the battery from overheating under low acidity. As charging progresses, the PbSO4 on the plates is gradually converted: some PbSO4 at the positive electrode is converted to PbO2, and some PbSO4 at the negative electrode is reduced to Pb. Initially, the battery terminal voltage rises slowly because a large amount of energy is used to decompose lead sulfate. This stage should continue until the battery terminal voltage rises close to the charging termination threshold or the current drops significantly. Do not pursue high voltage blindly; the conversion reaction should be completed. This process may last for several hours. During this time, monitor the temperature to ensure that the battery casing temperature does not exceed 40°C (a temperature sensor can be placed around the battery). If necessary, use a water bath or fan to cool the battery. If the temperature approaches the upper limit, temporarily stop charging or reduce the current, and continue charging after cooling.

[0036] Reverse Constant Current Charging (Stage 2): After the first positive charge is completed, disconnect the power supply and reverse the polarity to reverse charge the battery. Connect the positive terminal of the charger to the negative terminal of the battery, and the negative terminal of the charger to the positive terminal of the battery. Set the charging current to approximately 0.05–0.1C (slightly lower than the positive charge to gently remove lead sulfate). Since the battery is already partially charged, applying a reverse voltage will first cause the battery to pass through the zero discharge point before entering the reverse charging zone. Control the upper limit of the reverse charging voltage to approximately 2.2V per cell (e.g., the total voltage of a 12V battery should not be lower than 13V) to ensure the reaction is achieved without excessive heat generation. During reverse charging, the battery voltage can be observed to rise from high to low and then rise again; this is the result of the internal transition from normal charging to reverse polarization. Maintain a constant current until the battery voltage reaches the preset upper limit in the reverse direction or remains unchanged, indicating that the main reverse polarization reaction has been completed. The typical reverse charging duration depends on the battery capacity and degree of sulfation, generally several hours. Temperature must be closely monitored during the reverse charging stage and must be ≤40℃. During reverse charging, current migrates between the electrodes through the electrolyte. Additive ions move directionally towards the electrode surface under the influence of the electric field (electromigration conduction), and then diffuse back into the solution, thus repeating the cycle. This migration accelerates the interaction between the additive and the electrode surface, making it extremely effective for removing lead sulfate.

[0037] Cyclic charge-discharge (Phase 3, optional enhancement): Depending on the severity of battery sulfation, the forward → reverse charging combination of Phase 1 and Phase 2 can be repeated 2-4 times. That is, after completing one reverse charge, perform another constant current forward charge, and then reverse charge again. Multiple cycles help to fully utilize the active electrolyte and gradually penetrate and transform residual lead sulfate crystals. In each cycle, the forward charging current can be gradually increased to about 0.2C to shorten the time, but it must be ensured that it does not overheat. If multiple cycles are performed, a short constant current discharge (e.g., 0.1C discharge until the voltage drops by 10-20%) is added between each round of forward charge-reverse charge to simulate activation, which will promote a more uniform distribution of newly formed PbO2 and Pb and eliminate concentration polarization. If possible, the electrolyte can be replaced once between cycles: the current active solution is extracted, filtered, and then re-injected with fresh active solution of the same formulation to replenish the additive concentration (usually, a complete replacement is not necessary from the second round onwards, unless the liquid is significantly turbid or the additive is exhausted).

[0038] Repair completion assessment: After the last reverse charge, restore the battery to normal polarity and perform a long-term constant-current, constant-voltage charge (e.g., 0.1C constant current to constant voltage, constant voltage 2.4V / cell, continuous charging for more than 10 hours). This ensures that all plate materials are fully charged. After charging, let the battery stand for several hours and measure the open-circuit voltage and electrolyte density of each cell. If the cell voltage stabilizes above 2.10V, the total voltage is ≥ rated (e.g., ≥12.6V for a 12V battery), and the electrolyte specific gravity recovers to the range of 1.25-1.28, it indicates that the sulfuric acid inside the battery has been basically restored, and the capacity is close to the rated value (the battery capacity after repair can be increased from the initial 60% to over 90%). If the voltage still remains above the full charge threshold after standing (e.g., ≥2.17V for a single cell, ≥13.0V for a 12V battery), it means that the battery is almost like new.

[0039] Electrolyte Adjustment and Sealing: If the electrolyte specific gravity is found to be slightly lower than the standard, a small amount of sulfuric acid solution of appropriate concentration can be added for adjustment; conversely, if it is too high, distilled water can be added for fine-tuning. Be sure to add the electrolyte gradually in small amounts and mix thoroughly to avoid overcharging. After confirming the battery is fully charged and the electrolyte specific gravity is normal, remove excess active liquid to the correct level (do not disturb impurities deposited at the bottom of the battery). Then clean the terminals and apply petroleum jelly for corrosion protection. Finally, reseal the battery filler cap or safety valve to ensure a good seal.

[0040] Performance Testing: Standard discharge tests are used to verify the repair effect. The battery capacity is discharged at the rated discharge rate (e.g., 0.1C or I5 discharge), and the termination voltage and discharge duration are recorded. Under normal circumstances, the repaired battery should be able to discharge close to its rated capacity (>90% of rated capacity), with a significant reduction in internal resistance and a stable voltage curve without early collapse. A balance test is performed on multiple battery packs to check the consistency of voltage across individual cells. If any individual cell does not recover satisfactorily, the individual repair cycle can be repeated once. Once all indicators are satisfactory, the battery can be put back into use.

[0041] A regeneration system for implementing a lead-acid battery repair method using an active electrolyte and a reverse-charge battery includes: a programmable constant current / constant voltage charge / discharge power supply module for performing deep discharge, forward constant current charging, reverse constant current charging, and terminal constant voltage charging; an electrolyte extraction and injection module for extracting old acid and injecting active electrolyte; a temperature and pressure monitoring module for real-time detection and feedback control of the charging current; and a controller and human-machine interface for storing and recalling the process parameters of the above steps to achieve an automated regeneration process.

Claims

1. A method for repairing lead-acid batteries using an active electrolyte and a reverse-charge battery, characterized in that, Includes the following steps: S1. Discharge the battery to be repaired at 0.05-0.20C until the terminal voltage is close to 0V; S2. Drain at least 80% of the original electrolyte and inject active electrolyte. The active electrolyte contains, per liter of solution: Organic ligand 1-5g, MgSO4 1-4g, Na2SO4 1-5g, Sn 2+ 0.2-0.8g, Bi 3+ 0.5-2g, Co 2+ 0.2-0.8g, H3PO4 3-6g, equilibrium solvent is deionized water; S3, let stand for 0.5-1 hour; S4. Charge the battery at a constant current of 0.05-0.20C to a single cell voltage of 2.35-2.45V, following the normal polarity of the battery. S5. After power failure, reverse polarity and charge the individual cell to 1.90-2.20V with a constant current of 0.05-0.15C. S6. Repeat steps S4-S5 2-4 times; S7. Restore normal polarity and charge at a constant voltage of 2.40V / division until the current is ≤0.01C; S8. Adjust the electrolyte specific gravity to 1.25–1.28 g·cm³. -3 After sealing and allowing it to stand and balance, the capacity was tested by discharging at 0.1C.

2. The method for repairing a lead-acid battery using an active electrolyte and a reverse-charging battery according to claim 1, characterized in that: The organic ligand is glycerol, and the addition amount is 2-4 g / L.

3. The method for repairing a lead-acid battery using an active electrolyte and a reverse-charging battery according to claim 1, characterized in that: During the constant current charging process in steps S4 and S5, a narrow pulse current with an amplitude of 5-50% of the main charging current or an ultrasonic vibration of 20-40kHz is superimposed to accelerate ion migration and crystal stripping.

4. The method for repairing a lead-acid battery using an active electrolyte and a reverse-charging battery according to claim 1, characterized in that: In step S5, during reverse charging, an inert auxiliary electrode is placed in the electrolyte, and the negative terminal of the charging power supply is connected to the auxiliary electrode to directionally oxidize the negative electrode PbSO4.

5. The method for repairing a lead-acid battery using an active electrolyte and a reverse-charging battery according to claim 1, characterized in that: Steps S1-S6 control the battery casing temperature to ≤40℃ throughout the entire process and monitor it in real time. If the temperature exceeds the threshold, the charging current will be automatically reduced or charging will be paused.

6. The method for repairing a lead-acid battery using an active electrolyte and a reverse-charging battery according to claim 1, characterized in that: In step S2, 10-30% of the original electrolyte is retained to maintain the mass balance of sulfate and reduce acid overshoot.

7. The method for repairing a lead-acid battery using an active electrolyte and a reverse-charging battery according to claim 1, characterized in that: The number of cycles in step S6 is selected based on the remaining capacity of the battery before discharge: 3-4 cycles when the remaining capacity is less than 40% of the rated capacity, and 2 cycles when the remaining capacity is greater than 50%.

8. The method for repairing a lead-acid battery using an active electrolyte and a reverse-charging battery according to claim 1, characterized in that: For sealed valve-regulated lead-acid batteries, step S2 involves electrolyte replacement via microneedle injection or valve orifice injection, and step S8 involves sealing the valve orifice with flame-retardant epoxy.

9. A method for repairing a lead-acid battery using an active electrolyte and a reverse-charging battery according to claim 1, characterized in that: After the terminal constant voltage charging is completed in step S7, let it stand for 2-4 hours. If the total voltage drops by more than 3%, perform a 0.05C constant current supplementary charging for 1-3 hours to ensure that the active material is completely restored.

10. A lead-acid battery regeneration system for implementing the method according to any one of claims 1-9, characterized in that, include: Programmable constant current / constant voltage charge and discharge power supply module, used to perform deep discharge, forward constant current charging, reverse constant current charging and terminal constant voltage charging; The electrolyte pumping and injection module is used to pump out old acid and inject active electrolyte; Temperature and pressure monitoring module is used to detect and provide feedback control of charging current in real time; The controller and human-machine interface are used to store and recall the process parameters of the above steps to realize the automated regeneration process.

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