Method for capacity repair and matching of after-sales battery

Abstract

The application discloses a capacity repairing and matching method for after-sales batteries and belongs to the field of storage battery repairing and matching. The electrolyte supplementing, charging, matching repairing process method is adopted to solve the early performance decline defect problems of the batteries caused by over-discharge, water loss and early shedding of active substances, so that the structural recombination of the electrolyte and the active substances during charging and discharging of the batteries can be greatly improved, the reactivated activity can be activated, the electrochemical oxidation and reduction reactions of the electrolyte and the active substances can be balanced, the discharge capacity of the batteries can be recovered, the repairing rate and utilization rate of the after-sales batteries can be improved, and the secondary bad batteries can be screened out through the repairing method.

Description

Technical Field

[0001] This invention belongs to the field of battery repair and matching, specifically relating to a method for capacity repair and matching of after-sales batteries. Background Technology

[0002] In the lead-acid valve-regulated power batteries for electric vehicles on the market, the battery pack is composed of multiple individual cells connected in series. Although the batteries undergo capacity matching and quality screening to ensure performance consistency before leaving the factory, due to the characteristics of the battery series connection method, as well as different riding habits of electric vehicles and different charging parameters of chargers, the internal resistance and voltage of each battery will vary after a period of use, resulting in poor performance consistency and individual cells lagging behind, requiring after-sales quality repair.

[0003] Most of the batteries returned from the market after-sales service have already shown signs of deformation. Due to excessive charge and discharge cycles, the electrochemical reaction mechanism of the positive and negative plates inside the battery, overcharging, poor internal gas recombination, and other reasons have led to water loss and thermal runaway, resulting in varying degrees of expansion. This manifests as side deformation and bulging on the exterior. The active materials inside the battery also detach early on under reduced wet compressive force, especially in the individual cells on both sides of the 1×6 single-cell structure battery. This means that the battery capacity decreases, resulting in differences in the performance of individual cells and individual units, which accelerates the capacity decay of the entire battery pack.

[0004] For example, patent application CN117790935A discloses a method for repairing and grouping lead-acid batteries. This method activates active materials through high and low temperature treatment, solving the passivation phenomenon of internal plates in the battery, thereby enabling the detection, screening, classification, and repair of problematic batteries returned from the market. Patent application CN111082167A discloses a method for repairing returned batteries. This method, based on the current situation of after-sales batteries, quickly assesses batteries that pass initial inspection, classifying them as unrepairable, easily repairable, or difficult to repair. After classification, different repair methods are applied to each type of battery.

[0005] Therefore, to address the above shortcomings, it is necessary to provide more advanced processes for classifying and screening returned batteries for problems, and then repairing and reassembling them for reuse. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention relates to a method for capacity repair and grouping of after-sales batteries. The method involves correcting the appearance of the battery, adding excess electrolyte, extracting residual acid, recharging and discharging capacity testing, and combining the battery capacity repair method to screen usable batteries for regrouping.

[0007] The specific technical solution of the present invention is as follows: This invention provides a method for capacity repair and battery matching in after-sales service, comprising the following steps: S1. Add a quantitative amount of modified electrolyte containing β-aminoethanesulfonic acid to the after-sales battery until it reaches a rich electrolyte state; S2. After replenishing the electrolyte, the battery is subjected to negative pressure adsorption treatment and then allowed to stand. S3. Perform multi-stage progressive constant current and voltage limiting charging on the battery after it has been left to stand, and extract excess free acid during the charging process to control the electrolyte saturation. S4. Group the batteries that have completed the charge and discharge process according to the discharge time parameters.

[0008] Furthermore, step S1, before adding electrolyte to the after-sales battery, also includes compressing and shaping the battery, the steps of which include: After-sales batteries with cracks, dents, bulges, or leakage (external damage and severe deformation) are excluded. Batteries with slight external deformation are selected. After prying open the battery cover and vent valve, a compression shaping and correction fixture is used to compress and shape the batteries, and the bolts are tightened to secure them. This compresses the slightly bulging battery casing to a preset standard thickness range. After proper compression, subsequent electrolyte replenishment is performed to ensure that the internal electrode groups of each battery achieve a consistent compression state and electrolyte replenishment amount, thus ensuring more consistent subsequent battery assembly.

[0009] By compressing and reshaping the after-sales batteries, the slightly bulging battery casings are restored to the standard thickness, significantly improving the consistency of subsequent repair results. After compression, the pressure between the internal electrode groups and plates of the battery tends to be uniform, eliminating local gaps and stress concentrations caused by bulging. This ensures uniform wetting and distribution of added electrolyte within the battery, avoiding uneven local 'lean' or 'rich' electrolyte phenomena caused by casing deformation. Based on this, multi-stage progressive charging repair can improve the capacity recovery rate of individual cells, and significantly reduce the capacity difference between cells within the repaired battery pack, thus improving the overall power output.

[0010] β-Aminoethanesulfonic acid (chemical formula C2H7NO3S; melting point 305.11℃; molecular weight 125.15; density 1.734 g / cm³) is a colorless or white oblique crystal. 3 (-173.15K)).

[0011] Furthermore, the modified electrolyte containing β-aminoethanesulfonic acid is prepared by the following steps: dissolving β-aminoethanesulfonic acid in water to prepare a pre-prepared additive solution, and then mixing the pre-prepared additive solution with a sulfuric acid solution.

[0012] Preferably, the mass ratio of β-aminoethanesulfonic acid to water is 20–25:100, and the pre-prepared additive solution has a density of 1.330–1.340 g / cm³. 3The volume or mass ratio of the sulfuric acid solution is 5–8:100, and the resulting mixture has a density of 1.340–1.350 g / cm³. 3 sulfuric acid electrolyte.

[0013] Aftermarket batteries have undergone multiple charge-discharge cycles and are generally dehydrated and lack electrolyte. Adding a mixture of β-aminoethanesulfonic acid and water aims to enhance the regeneration of β-aminoethanesulfonic acid and sulfate ions, acting as a catalyst to strengthen the electrochemical reaction with active materials and improve battery activity.

[0014] Preferably, the present invention dissolves β-aminoethanesulfonic acid in water to prepare a pre-prepared additive solution. The water used is pure water (i.e., distilled water) with a conductivity of 1 to 50 μs / cm to remove impurities and avoid impurities such as iron and chloride ions from affecting hydrogen evolution in the battery.

[0015] Furthermore, the amount of modified electrolyte added quantitatively is 10-20 ml per cell.

[0016] Preferably, the negative pressure adsorption treatment is performed under the following conditions: a negative pressure of -0.085 MPa is maintained for 8–10 seconds, followed by a settling time of 5–10 minutes. The negative pressure is used to ensure that the electrolyte is fully adsorbed by the battery electrode group plates and separators, thereby improving the uniformity of the chemical reaction between sulfate ions and the active material.

[0017] Furthermore, the multi-stage progressive constant current constant voltage charge-discharge process includes the following steps performed sequentially: Step 1: Charge at a constant current of 0.5CA to a single cell voltage of 2.37V, then charge at a constant voltage for 2-3 hours; Step 2: Discharge at a constant current of 0.5CA until the single-cell voltage reaches 1.00V; Step 3: Charge at a constant current of 0.3CA until the voltage of a single cell reaches 2.47V, and then charge at a constant voltage for 5 hours; Step 4: Discharge at a constant current of 0.5CA until the single-cell voltage reaches 1.70V; Step 5: Charge at a constant current of 0.2CA until the voltage of a single cell reaches 2.57V, and then charge at a constant voltage for 5 hours; Step 6: Discharge at a constant current of 0.5CA until the single-cell voltage reaches 1.75V; Step 7: Charge at a constant current of 0.5CA until the voltage of a single cell reaches 2.67V, and then charge at a constant voltage for 5 hours.

[0018] Furthermore, during the constant voltage charging process in step 1, the external heating status of the battery is monitored. When the temperature of any single cell reaches or exceeds 45°C, it is determined that there is a short circuit problem inside the battery and it is eliminated. Then, steps 2 to 7 are continued.

[0019] Preferably, when the charging time in step 7 reaches 2 to 3 hours, excess free acid is extracted to control the electrolyte saturation inside the battery to 94 to 96%; and the battery vent valve and cover are put on 0.5 to 1.0 hours after the charging in step 7 is completed.

[0020] Furthermore, the step of grouping the batteries that have completed the charge and discharge process according to the discharge time parameter includes: screening and grouping according to the battery series, based on the discharge time, open circuit voltage, open circuit voltage difference within the same group, and termination voltage difference. Among them, for valve-regulated lead-acid batteries for electric vehicles (DZF series), IC2 current discharge is adopted, the discharge time is ≥118min, the open circuit voltage is 13.10~13.45V, the open circuit voltage difference of the same group is ≤0.04V and the termination voltage difference is ≤0.60V for use as after-sales turnover batteries, and the open circuit voltage difference of the same group is ≤0.05V and the termination voltage difference is ≤0.75V for use as after-sales maintenance batteries; For maintenance-free batteries specifically designed for electric vehicles (EVF series), discharge using IC3 current is adopted, with a discharge time ≥178min, open-circuit voltage 13.10~13.45V, open-circuit voltage difference within the same group ≤0.04V, and termination voltage difference ≤0.60V for use as after-sales temporary batteries, and open-circuit voltage difference within the same group ≤0.05V, and termination voltage difference ≤0.75V for use as after-sales maintenance batteries.

[0021] The beneficial effects of this invention are: This electrolyte replenishment, charging, and grouping repair process can significantly improve the structural reorganization of the battery electrolyte and active materials during charging and discharging, activate regenerative activity, balance the electrochemical oxidation and reduction reactions of the electrolyte and active materials, restore the battery discharge capacity, and improve the after-sales battery repair rate and utilization rate. At the same time, the repair method can screen out secondary defective batteries. Attached Figure Description

[0022] Figure 1 The graph shows the cycle life test results of the battery packs in Example 1 and Comparative Example 1. Detailed Implementation

[0023] Example 1 Pre-prepared battery modification and repair electrolyte additive solution: 2.0 kg of pure white, oblique crystalline β-aminoethanesulfonic acid was dissolved in boiled, room-temperature pure water at a ratio of 20:100 and stirred thoroughly to form the battery electrolyte additive solution. Then, the additive solution was diluted with sulfuric acid at a ratio of 5:100 (density 1.330 g / cm³ at room temperature). 3 Add it to the sulfuric acid solution and stir until well mixed.

[0024] 200 after-sales 6-DZF-20 batteries were collected. 20 batteries with visible damage, leakage, or severe bulging were eliminated. The remaining 180 batteries had minor deformation and bulging and could be repaired. Each battery was fitted and shaped using a specialized jig, and then divided into 10 circuits, with 18 batteries connected in series in each circuit.

[0025] Pry open the battery covers and vent valves, attach the acid reservoir, and add 15ml of pre-mixed repair electrolyte to each cell. Then, apply negative pressure vacuum for 8 seconds and let stand for 6 minutes to observe acid stability. The charging process of this invention, step 1, is as follows: constant current charging current 5A, constant voltage charging cutoff voltage 14.22V / cell, total circuit voltage 256V, and charging time 3 hours. Observe the external heating state of the batteries; the battery voltage gradually increases with charging time, and some cells show heat, measured at 47℃, ruling out batteries with internal short circuits. Next, execute steps 2-7. After the acid has uniformly precipitated inside the batteries and the battery voltage is consistently 16.02V, after 2.5 hours, use negative pressure to remove excess free acid, ending the charging process. Replace the battery vent valves and covers, and label each battery with the discharge capacity test results from step 6. The discharge time is shown in Table 1.

[0026] Table 1 The batteries listed above meet the discharge capacity requirement of ≥118 min. Batteries with a discharge capacity <118 min are excluded. The open-circuit voltage of the batteries for both turnover and maintenance is between 13.1 and 13.45 V. The batteries are then matched in terms of capacity. The open-circuit voltage difference of the turnover batteries is ≤0.04 V, and the open-circuit voltage difference of the maintenance batteries is ≤0.05 V. The matching results are shown in Table 2.

[0027] Table 2 Example 2 Pre-prepared battery modification and repair electrolyte additive solution: 2.0 kg of pure white, oblique crystalline β-aminoethanesulfonic acid was dissolved in boiled, room-temperature pure water at a ratio of 20:100 and stirred thoroughly to form the battery electrolyte additive solution. Then, the additive solution was diluted with sulfuric acid at a ratio of 5:100 (density 1.335 g / cm³ at room temperature). 3 Add it to the sulfuric acid solution and stir until well mixed.

[0028] 200 after-sales 6-EVF-32 batteries were collected. Sixteen batteries with visible damage, leakage, or severe bulging were eliminated. The remaining 184 batteries had minor deformation and bulging and could be repaired. A specially invented jig was used to fit and shape each battery, dividing them into 10 circuits, with 18 batteries connected in series in each circuit.

[0029] Pry open the battery covers and vent valves, attach the acid reservoir, and add 10ml of pre-mixed repair electrolyte to each cell. Then, apply negative pressure vacuum for 10 seconds and let stand for 5 minutes to observe acid stability. The charging process step 1 of this invention is used: constant current charging current 5A, constant voltage charging cutoff voltage 14.22V / cell, total circuit voltage 256V, and charging time 2.5 hours. Observe the external heating state of the batteries; the battery voltage gradually increases with charging time. Some cells show heat, measured at 56℃, ruling out batteries with internal short circuits. Next, execute steps 2-7. After the acid has uniformly precipitated inside the batteries and the battery voltage is consistently 16.02V, at 2.8 hours, use negative pressure to remove excess free acid, ending charging. Replace the battery vent valves and covers, and label each battery with the discharge capacity test result from step 6. The discharge time is shown in Table 3.

[0030] Table 3 The batteries listed above meet the discharge capacity requirement of ≥178 min, excluding those <178 min. The open circuit voltage of the batteries for both turnover and maintenance is between 13.1 and 13.45 V. The batteries are then matched in terms of capacity. The open circuit voltage difference of the turnover batteries is ≤0.04 V, and the open circuit voltage difference of the maintenance batteries is ≤0.05 V. The matching results are shown in Table 4.

[0031] Table 4 Comparative Example 1 500 after-sales 6-DZF-20 batteries were collected. 100 batteries with visible damage, leakage, or bulging were visually excluded. The remaining 400 batteries were divided into circuits, with 18 batteries connected in series in each circuit. A standard charging and discharging process was used, with a charging current of 0.5C and a time of 5 hours. The charging voltage per cell was 2.47V, the discharging current was 0.5C, and the discharge termination voltage per cell was 1.75V. The results are shown in Table 5.

[0032] Table 5 Batteries with qualified capacity were screened. Batteries with an open circuit voltage of 13.0V or higher and a capacity of ≥118 min or higher were considered qualified. A total of 400 batteries were selected, with 70 failing and 330 passing, resulting in a pass rate of 82.5%, as shown in Table 6.

[0033] Table 6 330 batteries with qualified charging and discharging capacity were grouped together as shown in Table 7.

[0034] Table 7 Comparative Example 2 800 6-DZF-12 batteries were collected. 180 batteries with visible damage, leakage, or bulging were eliminated. The remaining 620 batteries were divided into circuits, with 18 batteries connected in series in each circuit. A standard charging and discharging process was used, with a charging current of 0.5C and a time of 5 hours. The charging voltage per cell was 2.47V, the discharging current was 0.5C, and the discharge termination voltage per cell was 1.75V. The results are shown in Table 8.

[0035] Table 8 Batteries with qualified capacity were screened. Batteries with an open circuit voltage of 13.0V or higher and a capacity of ≥118 min or higher were considered qualified. A total of 620 batteries were screened, with 190 failing and 430 passing, resulting in a pass rate of 69.3%, as shown in Table 9.

[0036] Table 9 430 batteries with qualified charging and discharging capacity were grouped together as shown in Table 10.

[0037] Table 10 Test Example 1 Two sets of battery packs were prepared for sampling comparison examples 1 and 2, and examples 1 and 2, and their performance was compared. The capacity at room temperature (25℃) and low temperature (-18℃) are shown in Tables 11 and 12.

[0038] Table 11 Table 12 The battery pack in the example showed an average capacity increase of 7.15 min per unit at room temperature (25°C) and an average capacity increase of 13.5 min per unit at low temperature (-18°C).

[0039] Cycle life tests were conducted on sampled battery packs from Comparative Example 1 and Example 1. The highest capacity plateau increased by approximately 1.5 Ah, and the cycle life increased by approximately 80 cycles. Figure 1 ).

Claims

1. A method for capacity repair and battery matching in after-sales service, characterized in that, Includes the following steps: S1. Add a quantitative amount of modified electrolyte containing β-aminoethanesulfonic acid to the after-sales battery until it reaches a rich electrolyte state; S2. After replenishing the electrolyte, the battery is subjected to negative pressure adsorption treatment and then allowed to stand. S3. Perform multi-stage progressive constant current and voltage limiting charging on the battery after it has been left to stand, and extract excess free acid during the charging process to control the electrolyte saturation. S4. Group the batteries that have completed the charge and discharge process according to the discharge time parameters.

2. The method according to claim 1, characterized in that, The modified electrolyte containing β-aminoethanesulfonic acid is prepared by the following steps: dissolving β-aminoethanesulfonic acid in water to prepare a pre-additive solution, and then mixing the pre-additive solution with a sulfuric acid solution.

3. The method according to claim 2, characterized in that, The mass ratio of β-aminoethanesulfonic acid to water is 20–25:100, and the pre-prepared additive solution has a density of 1.330–1.340 g / cm³. 3 The volume or mass ratio of the sulfuric acid solution is 5–8:100, and the resulting mixture has a density of 1.340–1.350 g / cm³. 3 sulfuric acid electrolyte.

4. The method according to claim 1, characterized in that, The amount of modified electrolyte added quantitatively is 10-20 ml per cell.

5. The method according to claim 1, characterized in that, The negative pressure adsorption treatment conditions are: -0.085 MPa negative pressure maintained for 8 to 10 seconds, and standing time of 5 to 10 minutes.

6. The method according to claim 1, characterized in that, The multi-stage progressive constant current constant voltage charge-discharge process includes the following steps performed sequentially: Step 1: Charge at a constant current of 0.5CA to a single cell voltage of 2.37V, then charge at a constant voltage for 2-3 hours; Step 2: Discharge at a constant current of 0.5CA until the single-cell voltage reaches 1.00V; Step 3: Charge at a constant current of 0.3CA until the voltage of a single cell reaches 2.47V, and then charge at a constant voltage for 5 hours; Step 4: Discharge at a constant current of 0.5CA until the single-cell voltage reaches 1.70V; Step 5: Charge at a constant current of 0.2CA until the voltage of a single cell reaches 2.57V, and then charge at a constant voltage for 5 hours; Step 6: Discharge at a constant current of 0.5CA until the single-cell voltage reaches 1.75V; Step 7: Charge at a constant current of 0.5CA until the voltage of a single cell reaches 2.67V, and then charge at a constant voltage for 5 hours.

7. The method according to claim 6, characterized in that, During the constant voltage charging process in step 1, the external heating status of the battery is monitored. When the temperature of any single cell reaches or exceeds 45°C, it is determined that there is a short circuit problem inside the battery and it is eliminated. Then, steps 2 to 7 are continued.

8. The method according to claim 1 or 7, characterized in that, When the charging time in step 7 reaches 2 to 3 hours, excess free acid is extracted to control the electrolyte saturation inside the battery at 94 to 96%; and the battery vent valve and cover are put on 0.5 to 1.0 hours after the charging in step 7 is completed.

9. The method according to claim 1, characterized in that, The step of grouping batteries that have completed the charge and discharge process according to the discharge time parameter includes: screening and grouping according to the battery series, based on the discharge time, open circuit voltage, open circuit voltage difference within the same group, and termination voltage difference. For the DZF series batteries, IC2 current discharge is used, with a discharge time ≥118min, open circuit voltage 13.10~13.45V, open circuit voltage difference within the same group ≤0.04V, and termination voltage difference ≤0.60V for use as after-sales temporary batteries, and open circuit voltage difference within the same group ≤0.05V, and termination voltage difference ≤0.75V for use as after-sales maintenance batteries; For EVF series batteries, use IC3 current discharge, discharge time ≥178min, open circuit voltage 13.10~13.45V, open circuit voltage difference within the same group ≤0.04V, termination voltage difference ≤0.60V for after-sales temporary batteries, and open circuit voltage difference within the same group ≤0.05V, termination voltage difference ≤0.75V for after-sales maintenance batteries.

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