A method of repairing a valve regulated lead-acid battery
By combining negative pressure inversion and local heating with low-current charging, the performance degradation problem caused by electrolyte gravity stratification in valve-regulated lead-acid batteries was solved, achieving uniform distribution of active materials inside the battery and improving battery performance and lifespan.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TIANNENG BATTERY GROUP
- Filing Date
- 2026-03-31
- Publication Date
- 2026-06-19
AI Technical Summary
Valve-regulated lead-acid batteries experience performance degradation and uneven utilization of active materials on the plates due to electrolyte stratification caused by gravity during static storage. Existing repair methods cannot effectively solve the problem of deep electrolyte stratification, which affects battery capacity and lifespan.
The method of negative pressure inversion combined with local heating and low current charging is adopted. By inverting the negative pressure, the gravity stratification of the electrolyte is broken, which causes a small suction-backflow effect in the pores of the separator, thus breaking the gravity stratification structure. Local heating is used to improve the uniformity of active materials in the upper and lower parts of the electrode plate, and low current charging is used to achieve uniformity inside the battery.
It significantly reduces the difference in lead sulfate content on the plates, improves battery capacity and average life, reduces battery management costs during long storage periods, and extends battery life.
Smart Images
Figure CN122246295A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lead-acid battery technology, specifically relating to a valve-regulated lead-acid battery repair method. Background Technology
[0002] Valve-regulated lead-acid batteries are produced to meet market demand. During static storage, the sulfuric acid electrolyte inside the battery will separate into layers due to gravity. The density of the lower layer of electrolyte is significantly higher, and the longer the storage time (more than half a year), the more serious the phenomenon becomes. This will directly lead to the degradation of the battery's discharge performance.
[0003] Current battery factory repair methods generally employ constant voltage charging or charge-discharge cycles. For example, invention patent CN118971228A discloses a charging method for an AGM lead-acid battery charger, used for supplementary charging or recharge repair. However, this method only eliminates surface delamination; due to the adsorption effect of the AGM separator, the density difference in the deeper layers still exists, and it suffers from problems such as long charging time with low current and easy water loss with high current.
[0004] Furthermore, the proposed periodic voltage and current conversion improvement scheme fails to fundamentally solve the problem of deep electrolyte homogenization, making it difficult to eliminate electrolyte stratification. This is because, due to the gravitational stratification of the electrolyte, the lead sulfate content in the upper and lower active materials of the repaired battery plates differs significantly, with some batteries showing a difference exceeding 10%. This density difference in active materials between the upper and lower regions of the plates caused by electrolyte stratification results in the lower part of the plates being chronically undercharged, leading to a higher lead sulfate content and hindering uniform activation of the active materials. This problem not only directly reduces the actual output capacity of the battery but also further shortens the battery's cycle life due to uneven utilization of the active materials on the upper and lower plates.
[0005] In addition, existing methods, such as segmented water replenishment and charging schemes, achieve deep repair of water loss, stratification, and sulfation in after-sales batteries through segmented water replenishment, stepped charging, and pulse activation. For example, the invention patent with publication number CN101599559A discloses a battery desulfation and recovery process, including the following steps: First, fill the battery with battery recovery activator, let the lead-acid battery with the added battery recovery activator stand for 1 hour to allow the agent to fully penetrate the battery interior and fully react with the irreversible lead sulfate on the positive plate inside the battery. Different starting currents are used for batteries with different remaining capacities, and three different amounts of repair are performed to obtain different total repair dosages and total repair amounts; Second, repair the sulfated lead-acid battery with a high-frequency pulse activation instrument; Third, add deionized water to the sulfated lead-acid battery; Fourth, discharge check; Fifth, recharge; Sixth, battery grouping, discharge test after repair, lead-acid batteries that have been recharged for 8 hours, and group the stable single cells in the entire battery group; Seventh, repeat steps five, six, and seven for lead-acid single cells with unstable voltage. However, this method requires opening the cover and breaking the seal, making it unsuitable for online repair before shipment.
[0006] For example, acid replenishment repair methods, which involve adding a high concentration of sulfuric acid to the battery, can rapidly increase battery capacity, but this effect is short-lived. The liquid electrolyte severely corrodes the battery plates, accelerating battery failure. High-frequency pulse methods, using high current, high voltage, and high frequency, are prone to overheating, swelling, bulging, and powdering, resulting in low repair rates, severe damage to the plates, and short battery life. High-current repair methods, using high current and high voltage to forcibly break up some sulfuric acid crystals, offer some repair potential. However, the excessive voltage is dangerous, easily generating excessive heat, exacerbating water loss, and causing significant damage to the active materials.
[0007] In addition, the common problem of insufficient charging in the end-user market exacerbates electrolyte stratification and plate sulfation, creating a vicious cycle that seriously affects battery performance and lifespan. Summary of the Invention
[0008] To address the aforementioned technical problems in existing technologies, this invention provides a valve-regulated lead-acid battery repair method. This method aims to provide a synergistic repair approach for electrolyte stratification and plate sulfation without disassembling the battery's sealed structure, suitable for batch repairs before shipment. Specifically, negative pressure inversion is used to improve the stratification of the sulfuric acid electrolyte inside the battery, achieving rapid electrolyte homogenization. Then, the bottom of the battery is heated and charged with a small current, preferentially dissolving the lead sulfate in the lower part of the plates, effectively reducing the difference in active material content between the upper and lower layers of the plates. Ultimately, this achieves a balanced distribution of active materials within the battery, effectively improving battery performance and cycle life, and solving the industry pain point of battery performance degradation during long storage periods.
[0009] This invention provides a method for repairing valve-regulated lead-acid batteries, comprising the following steps: The battery to be repaired is placed upside down in a negative pressure chamber to perform pressure holding and depressurization operations to make the electrolyte in the battery uniform throughout, and then left to stand. After the battery has been left to stand, it is placed in a formation water tank for charging and discharging repair.
[0010] This invention breaks down the density gradient of the electrolyte due to gravity stratification by storing it under negative pressure and inverting it. This induces a slight "suction-reflux" effect within the pores of the separator, disrupting the originally stable gravity stratification structure and making the density of the upper and lower layers more uniform. By maintaining pressure, allowing it to stand, and then maintaining pressure again, local concentration fluctuations caused by unidirectional electrolyte flow are avoided, thus improving the homogenization effect.
[0011] Preferably, the battery to be repaired is a valve-regulated lead-acid battery that has experienced electrolyte stratification after being stored in inventory.
[0012] Preferably, the negative pressure of the negative pressure box is set to -0.05 to -0.02 MPa.
[0013] By using negative pressure within the aforementioned range, battery casing deformation can be avoided, and electrolyte homogenization can be promoted.
[0014] Preferably, the pressure holding and depressurization operation is a multi-stage pressure holding and depressurization operation. Each stage involves holding pressure under negative pressure, allowing the pressure to stand, then depressurizing and allowing the pressure to stand before proceeding to the next stage of pressure holding and depressurization operation.
[0015] More preferably, the pressure holding and depressurization operation includes: the battery to be repaired is held under negative pressure for a first predetermined time, then depressurized and held for a second predetermined time, and then held under negative pressure for a third predetermined time.
[0016] By using segmented pressure holding and releasing operations, local concentration fluctuations caused by unidirectional electrolyte flow can be avoided, thus improving the homogenization effect.
[0017] More preferably, the first predetermined time is 15-20 minutes; The second scheduled time is 5 minutes; The third scheduled time is 20-30 minutes.
[0018] Preferably, after removing the battery from the negative pressure box, it is left to stand at room temperature and pressure for 1 day.
[0019] Preferably, the temperature of the circulating water in the chemical formation tank is controlled at 40℃-45℃.
[0020] By injecting circulating water within the aforementioned temperature range, local heating of the bottom of the battery can be achieved, thereby increasing the solubility of lead sulfate on the bottom plate and improving the consistency of lead sulfate content on the upper and lower parts of the plate after formation.
[0021] More preferably, the circulating water submerges the electrode plate to about 1 / 3 of its height.
[0022] The circulating water only submerges 1 / 3 of the electrode plate height, which can achieve local heating at the bottom of the battery, avoiding secondary stratification of the electrolyte caused by overall heating, and at the same time improving the solubility of lead sulfate at the bottom.
[0023] Preferably, the charge-discharge repair includes discharging first and then charging to complete the battery repair; The discharge current is 0.3-0.4 C2 A, and the discharge termination voltage is 1.6-1.8 V / cell; the charging current is 0.15-0.2 C2 A, and the charging voltage is 2.48-2.50 V / cell. A is the unit of current, "ampere," and C2 is the discharge current value corresponding to the battery's rated capacity at 2-hour rate. Only the value of C2 is used here.
[0024] More preferably, the charging time is 8-10 hours.
[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) The repair method provided by the present invention breaks the density gradient of the electrolyte due to gravity stratification by storing it under negative pressure and inverting it, thereby causing a small "suction-backflow" effect in the pores of the separator, breaking the original stable gravity stratification structure and making the density of the upper and lower layers more uniform. By holding the pressure, letting it stand, and then holding the pressure again, the local concentration fluctuations caused by the unidirectional flow of the electrolyte are avoided, thus improving the homogenization effect. Local heating at the bottom of the battery increases the solubility of lead sulfate on the bottom electrode plate, thereby improving the consistency of the content of lead sulfate on the upper and lower parts of the electrode plate after formation.
[0026] (2) The battery repaired by this method has a significantly reduced lead sulfate content in the negative electrode, and a significantly improved battery capacity and average lifespan. It saves battery management costs during long storage periods, effectively utilizes resources, and reduces waste. Attached Figure Description
[0027] Fig. 1 The results are the cycle test results of the batteries after repair in Example 1 and Comparative Example 1 of this invention.
[0028] Fig. 2 The results are the cycle test results of the batteries after repair in Example 2 and Comparative Example 2 of this invention.
[0029] Fig. 3 The results are the cycle test results of the batteries after repair in Example 3 and Comparative Example 3 of this invention. Detailed Implementation
[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.
[0031] To make the above-mentioned objects, features and advantages of the present invention clearer and easier to understand, the following detailed description will be provided in conjunction with specific embodiments. Example 1 Eighteen 6-DZF-20 batteries, which had been in storage for eight months (and exhibited electrolyte stratification), were placed upside down in a negative pressure chamber. The negative pressure was controlled at -0.04 MPa. The pressure holding time was controlled as follows: first, the pressure was held for 20 minutes, then the pressure was released and the batteries were allowed to stand for 5 minutes, and then the pressure was held for 30 minutes. The batteries were then removed and allowed to stand at room temperature and pressure for 1 day.
[0032] After the battery has been left to stand, it is placed in a formation water tank for series repair charging and discharging. During the repair, 40°C circulating water is introduced into the tank, and the water level is controlled at 5 cm (the plate height is 13.8 cm) with the bottom of the battery as the reference.
[0033] The battery repair process, including charging and discharging, is as follows: First, discharge the battery to 194.4 V at 6 A, then charge it for 10 hours at a constant voltage of 270 V at 3 A to complete the battery repair.
[0034] Example 2 Eighteen 6-DZF-22 batteries, which had been in storage for 6 months (and exhibited electrolyte stratification), were placed upside down in a negative pressure chamber. The negative pressure was controlled at -0.05 MPa. The pressure holding time was controlled as follows: first, hold the pressure for 15 minutes, then release the pressure and let it stand for 5 minutes, and then hold the pressure for 20 minutes. The batteries were then removed and left to stand at room temperature and pressure for 1 day.
[0035] After the battery has been left to stand, it is placed in a formation water tank for series repair charging and discharging. During the repair, 45°C circulating water is introduced into the tank, and the water level is controlled at 5 cm (the plate height is 13.9 cm) with the bottom of the battery as the reference.
[0036] The battery repair process, including charging and discharging, is as follows: First, discharge the battery to 172.8 V at 8.8 A, then charge it for 8 hours at a constant voltage of 267.84 V at 4.4 A to complete the battery repair.
[0037] Example 3 Eighteen 6-DZF-25 batteries, which had been in storage for 7 months (and exhibited electrolyte stratification), were placed upside down in a negative pressure chamber. The negative pressure was controlled at -0.04 MPa. The pressure holding time was controlled as follows: first, the pressure was held for 18 minutes, then the pressure was released and the batteries were allowed to stand for 5 minutes, and then the pressure was held for 25 minutes. The batteries were then removed and allowed to stand at room temperature and pressure for 1 day.
[0038] The battery was placed in a formation tank for series repair charging and discharging. During the repair, 43°C circulating water was introduced into the tank, and the water level was controlled at 5.5 cm (plate height was 16.2 cm) with the bottom of the battery as the reference.
[0039] The battery repair process, including charging and discharging, is as follows: First, discharge the battery to 184 V at 8.75 A, then charge it for 9 hours at a constant voltage of 269 V at 4.4 A to complete the battery repair.
[0040] Comparative Example 1 Eighteen 6-DZF-20 batteries (with electrolyte stratification) that had been in storage for 8 months were repaired. The batteries were then placed in a charging case and charged in series. The charging and discharging process was as follows: First, discharge the battery to 194.4 V at 6 A, then charge it for 10 hours at a constant voltage of 270 V at 3 A to complete the battery repair.
[0041] Comparative Example 2 Eighteen 6-DZF-22 batteries that had been in storage for 6 months (and exhibited electrolyte stratification) were repaired. The batteries were then placed in a charging case and charged in series. The charging and discharging process was as follows: First, discharge the battery to 172.8 V at 8.8 A, then charge it for 8 hours at a constant voltage of 267.84 V at 4.4 A to complete the battery repair.
[0042] Comparative Example 3 Eighteen 6-DZF-25 batteries, which had been in storage for 7 months and exhibited electrolyte stratification, were repaired. The batteries were then placed in a charging case and charged in series. The charging and discharging process was as follows: First, discharge the battery to 184 V at 8.75 A, then charge it for 9 hours at a constant voltage of 269 V at 4.4 A to complete the battery repair.
[0043] The batteries repaired in Examples 1-3 and Comparative Examples 1-3 were dissected, and the PbO2 content on the positive electrode plate and the lead sulfate content on the negative electrode plate and the lower part of the negative electrode plate were analyzed. The data are shown in Table 1. Table 1. Lead dioxide and lead sulfate content of the electrode plates
[0044] As shown in Table 1, the range of lead dioxide content in the positive electrode of the battery in the example was the largest at 2.12%, while that in the comparative example was the largest at 6.34%. The range of lead sulfate content in the negative electrode of the battery in the example was the largest at 2.56%, while that in the comparative example was the largest at 10.31%. This indicates that the range of lead sulfate content in the negative electrode of the battery repaired using this method was significantly reduced.
[0045] Four batteries from each of Examples 1-3 and Comparative Examples 1-3 were selected to form a group of batteries. The batteries from Examples 1-3 and Comparative Examples 1-3 were subjected to a 1 / 2 C2A cycle life test. Each battery was discharged to 42.00 V at 10 A, 11 A, and 12.5 A, and then charged at a constant voltage of 59.20 V with a current limit of 6.0 A for 7 hours, constituting one cycle. The lifespan ended when the discharge time was less than 96 minutes. The cycle data are shown in Table 2 and [Table data would be inserted here]. Figs. 1-3 As shown.
[0046] Table 2 Circular Data
[0047] As shown in Table 2, after cycle life testing, the average lifespan of the example battery was 416.7 cycles, while the average lifespan of the comparative battery was 338.7 cycles. The lifespan of the example battery was significantly higher than that of the comparative battery. This indicates that the average lifespan of the battery repaired using this method is significantly improved.
[0048] The above data demonstrates that the repaired battery prepared using this method can improve battery performance and extend battery cycle life.
[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A method for repairing a valve-regulated lead-acid battery, characterized in that, Includes the following steps: The battery to be repaired is placed upside down in a negative pressure chamber to perform pressure holding and depressurization operations to make the electrolyte in the battery uniform throughout, and then left to stand. After the battery has been left to stand, it is placed in a formation water tank for charging and discharging repair.
2. The valve-regulated lead-acid battery repair method according to claim 1, characterized in that, The batteries to be repaired are valve-regulated lead-acid batteries that have experienced electrolyte stratification after being stored in inventory.
3. The valve-regulated lead-acid battery repair method according to claim 1, characterized in that, The negative pressure of the negative pressure box is set to -0.05~-0.02 MPa.
4. The valve-regulated lead-acid battery repair method according to claim 1, characterized in that, The pressure holding and depressurization operation is a multi-stage pressure holding and depressurization operation. Each stage involves holding pressure under negative pressure, allowing the pressure to stand, then depressurizing and allowing the pressure to stand before proceeding to the next stage of pressure holding and depressurization operation.
5. The valve-regulated lead-acid battery repair method according to claim 4, characterized in that, The pressure holding and depressurization operation includes: holding the battery under negative pressure for a first predetermined time, then depressurizing and holding it for a second predetermined time, and then holding it under negative pressure for a third predetermined time.
6. The valve-regulated lead-acid battery repair method according to claim 5, characterized in that, The first scheduled time is 15-20 minutes; The second scheduled time is 5 minutes; The third scheduled time is 20-30 minutes.
7. The valve-regulated lead-acid battery repair method according to claim 1, characterized in that, The temperature of the circulating water in the chemical formation tank is controlled at 40℃-45℃.
8. The valve-regulated lead-acid battery repair method according to claim 1, characterized in that, The charge-discharge repair process involves discharging the battery first and then charging it to complete the battery repair. The discharge current is 0.3-0.4 C2 A, and the discharge termination voltage is 1.6-1.8 V / cell; the charging current is 0.15-0.2 C2 A, and the charging voltage is 2.48-2.50 V / cell.
9. The valve-regulated lead-acid battery repair method according to claim 8, characterized in that, Charging time is 8-10 hours.