Lead-acid battery formation and residual acid treatment method

Abstract

The present invention discloses a lead-acid battery formation and residual acid treatment method. The lead-acid battery formation and residual acid treatment method comprises the following steps: (1) when the lead-acid battery is formed to the capacity inspection stage, the lead-acid battery is deep-discharged; (2) the lead-acid battery is subjected to negative pressure acid extraction, the negative pressure is maintained at -0.04 to -0.05 MPa, and the negative pressure acid extraction time is 5 to 10 seconds; (3) after the negative pressure acid extraction is completed, the lead-acid battery is fully charged in the recharge stage. In the residual acid treatment method of the present invention, after the battery is deeply discharged, the acid extraction method is performed by maintaining the negative pressure without charging, that is, when the acid is extracted, trickle charging is not required to lift the floating acid of the battery, but the method is achieved by physical squeezing by maintaining the negative pressure, thereby effectively improving the consistency of the acid consumption of each cell active material of the battery, and ensuring the consistency of the acid absorption of the battery, thereby improving the consistency of the battery pack, which is beneficial to extending the service life of the battery pack. At the same time, the residual acid treatment does not need to be performed under low current charging, thereby reducing energy consumption.

Description

Technical Field

[0001] The invention relates to the technical field of lead-acid battery production, in particular to a lead-acid battery formation and residual acid treatment method. Background Art

[0002] Lead-acid batteries are a widely used chemical power source, offering advantages such as good reversibility, stable voltage characteristics, long service life, wide applicability, abundant and renewable raw materials, and low cost. In recent years, with growing environmental awareness and increasingly serious energy issues, lead-acid batteries have played a vital role as a power source in electric vehicle systems.

[0003] The capacity of a battery is primarily determined by the mass of the positive electrode material, the mass of the negative electrode material, and the minimum amount of sulfuric acid. Both the positive and negative electrode materials have porous structures. During the charge and discharge process, sulfuric acid enters the pores of the material through the pore structure to react, thereby achieving charge and discharge. However, from plate manufacturing to formation charging until the battery is offline, the control of each process will affect the weight and structure of the material, especially in plate manufacturing and acid formation. The plate coating process in plate manufacturing affects the amount of paste applied, and curing and drying affect the material composition and structure. Acid formation mainly affects the material structure and acid amount. Studies have shown that the impact of acid formation on the overall performance of batteries is the most critical and the last line of defense. However, the usual practice is still to follow the process route of external formation and weighing, which cannot avoid the uncertain risks brought by internal formation. For example, the control of battery temperature and acid amount during internal formation are the main factors directly affecting battery performance.

[0004] Improving the consistency of acid consumption across each cell's active material while ensuring consistency in acid absorption (saturation) is key to improving battery pack consistency. Conventional residual acid treatment processes are performed under low-current charging, which increases energy consumption and compromises plate strength due to continuous gas evolution.

[0005] For example, the invention application with publication number CN103199214A discloses an acid extraction control process for an internally formed lead-acid battery, comprising the following steps: 1) first allowing the formed battery to stand for 1-3 hours to allow the plates and separators to fully absorb the acid; 2) then charging the battery at a constant voltage and current limit for 1-3 hours to allow excess free acid to precipitate; 3) then performing trickle charging; 4) after the amount of precipitated acid does not change with the length of charging time, using an acid extractor to extract excess free acid during the trickle charging state.

[0006] For another example, the invention application with publication number CN104538681A discloses a lead-acid battery formation and grouping process, including internal formation and grouping, wherein the grouping includes: (1) repeatedly charging and discharging the assembled and internally formed batteries several times; (2) charging the batteries with constant voltage and current limiting, and extracting acid from the batteries during this process; (3) after the acid extraction is completed, a rubber cap is added to the acid injection port, a group of batteries are connected in series, and constant current discharge is performed until the average voltage reaches the termination voltage, and the discharge time is recorded; (4) the battery groups with a discharge time difference less than a set value are classified into one level, the battery voltage is detected, and the batteries in the same level are grouped according to the voltage; (5) after the grouping is completed, the battery group is charged. The method of the present invention extracts acid during the constant voltage and current limiting charging process, and after the acid extraction, a rubber cap is added to seal the interior of the battery, and then discharge is performed to detect the battery capacity. This is closer to the charging and discharging process of the battery in actual use, the detection data is more accurate, the battery group obtained by grouping has a longer cycle life, and the voltage range difference between the batteries is smaller. Summary of the Invention

[0007] In response to the deficiencies in the prior art, the present invention provides a method for treating residual acid in lead-acid batteries. By extracting acid using a negative pressure without charging, the acid content of the electrode groups in each cell of the battery can be made consistent, and the saturation of the electrode groups can be made consistent, thereby improving battery consistency and facilitating the extension of battery life.

[0008] A lead-acid battery formation and residual acid treatment method comprises the following steps:

[0009] (1) When the lead-acid battery is in the stage of formation and capacity inspection, the lead-acid battery is deeply discharged;

[0010] (2) vacuum extraction of lead-acid batteries, maintaining the negative pressure at -0.04 to -0.05 MPa for 5 to 10 seconds;

[0011] (3) After completing the negative pressure acid extraction, start the recharge phase to fully charge the lead-acid battery.

[0012] Preferably, during deep discharge in step (1), the battery is discharged at a current of 0.5C2 amperes for a fixed time, discharging 100% to 110% of its rated capacity, and then discharged at a current of 0.1C2 to 0.3C2 amperes to an average voltage of 7.2V. The rated capacity is the nominal capacity of the lead-acid battery, which is set to the expected value of the amount of electricity discharged when discharged to 10.5V. The actual capacity discharged by the lead-acid battery during deep discharge (for example, discharging to 7.2V) will exceed the rated capacity. C2 represents the two-hour rate rated capacity of the battery. When the current size during charging and discharging is expressed as a multiple of C2 amperes, C2 only takes the numerical value, and the unit of the current size is amperes.

[0013] Preferably, during the deep discharge in step (1), the battery is discharged at a constant voltage with a current of 0.5C2 ampere until the voltage of a single lead-acid battery is 7.2V to 9.6V, and then discharged at a current of 0.1C2 to 0.3C2 ampere to an average voltage of 7.2V.

[0014] The battery comprises a battery container and a battery cover that cover each other. The inner cavity of the battery container is divided into a plurality of cells, each of which is equipped with a pole group. The top surface of the battery cover is provided with an acid addition hole column corresponding to each cell, and the center of the acid addition hole column has an acid addition hole.

[0015] The battery acid extraction device used in step (2) negative pressure acid extraction includes an acid extraction manifold, one side of the acid extraction manifold is provided with an acid extraction nozzle corresponding to each acid addition hole on the battery, the acid extraction nozzle is sleeved with a rubber nozzle whose end is plugged into the acid addition hole column when in use, and the acid extraction nozzle is also equipped with an acid extraction drainage tube whose end extends out of the rubber nozzle and extends into the acid addition hole when in use; the acid extraction manifold also has a negative pressure interface for connecting to a negative pressure extraction device, the negative pressure interface is provided with a solenoid valve for controlling the opening and closing of the negative pressure interface, and the acid extraction manifold also has a pressure relief valve for releasing pressure.

[0016] Preferably, the negative pressure interface is provided with a hose for connecting to a negative pressure extraction device. The negative pressure extraction device can be an independent negative pressure blower or a negative pressure system for the entire workshop. Adding a hose can facilitate the connection of the negative pressure extraction device.

[0017] Preferably, the acid extraction manifold is provided with a handle for easy operation on a side away from the acid extraction nozzle. When in use, the acid extraction nozzle side is downward, and the handle side is upward. When in use, the staff grasps the handle to operate.

[0018] Preferably, the inner cavity of the acid extraction nozzle has an internal thread, and the acid extraction drainage tube is correspondingly provided with a threaded section, and the threaded section has an external thread that matches the internal thread of the inner cavity of the acid extraction nozzle.

[0019] Preferably, the end of the acid extraction drainage tube extending into the acid addition hole has a plurality of notches arranged along the circumference. The provision of the notches prevents the end of the acid extraction drainage tube from abutting against a separator in the battery electrode group during acid extraction, thereby preventing the acid extraction drainage tube from being blocked and affecting the normal acid extraction process.

[0020] Preferably, the inner diameter of a section of the rubber nozzle that fits with the acid extraction nozzle is larger than the inner diameter of a section that fits with the acid addition hole column.

[0021] The battery acid extraction device dedicated to the present application is connected to each acid extraction nozzle through an acid extraction manifold, and unified negative pressure extraction is performed. The acid extraction manifold also has a negative pressure interface for connecting to a negative pressure extraction device. The negative pressure interface is provided with a solenoid valve that controls the opening and closing of the negative pressure interface. The opening and closing of the solenoid valve accurately controls the negative pressure time during acid extraction, thereby improving the consistency of acid absorption between each cell. After the solenoid valve is closed, the interior of the acid extraction manifold is still in a negative pressure state, and the pressure relief valve can be opened to restore the interior of the acid extraction manifold to normal pressure.

[0022] Preferably, in the recharging stage of step (3), the battery is first charged at 0.25C2 for 3 hours and then charged at 0.15C2 for 12 hours.

[0023] Negative pressure squeezes the electrolyte within each battery cell, squeezing the electrolyte out. By maintaining a constant time and height, the electrolyte level in each cell can be kept roughly constant. Practice has shown that the saturation of the battery cell after residual acid treatment using this method is generally between 92% and 94%. No power is required during the acid extraction operation; the process can simply be left idle or paused. After the extraction is complete, the recharge phase begins, charging the battery, and the process can then continue as normal.

[0024] The battery is first discharged with 0.5C2 to 100% to 110% of the rate capacity or to a single cell voltage of 7.2V to 9.6V, and then discharged with a current of 0.1C2 to 0.3C2 amperes to an average voltage of 7.2V. It is obvious that the battery is deeply discharged to completely release the battery capacity. This is to completely match and exhaust the sulfuric acid with the positive and negative electrode materials, so that the acid content is basically consistent. At the same time, negative pressure residual acid treatment is carried out afterwards. Compared with the normal process conditions, the recharged acid amount after conservative discharge is more consistent, ensuring the synchronization of positive and negative substances and sulfuric acid.

[0025] The residual acid treatment method of the present invention is to extract acid by maintaining negative pressure without charge after deep discharge of the battery. That is, when extracting acid, there is no need for trickle charging to lift the floating acid of the battery. Instead, it is achieved by physical squeezing by maintaining negative pressure, which effectively improves the consistency of the acid consumption of active materials in each cell of the battery and ensures the consistency of the acid absorption of the battery, thereby improving the consistency of the battery pack and being beneficial to extending the service life of the battery pack. At the same time, the residual acid treatment does not need to be performed under low current charging, which reduces energy consumption.

[0026] Acid extraction after deep discharge means extracting the residual acid after the battery capacity matches the acid amount (the acid density at this time is between 1.05 and 1.1). The conventional method uses a trickle method to extract acid after the recharge is completed after the capacity inspection discharge (the acid density at this time is between 1.33 and 1.37). First, the acid amount of each cell in the normal capacity inspection discharge is not completely matched. Second, processing the residual acid under the premise of incomplete acid amount matching will cause the acid to be extracted when a certain cell needs more acid (because the acid specific gravity is high, more acid is taken away), further causing the problem of inconsistent cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the battery acid extraction device of the present invention.

[0028] Figure 2 for Figure 1 A partial enlarged view.

[0029] Figure 3 for Figure 1 A partial enlarged view of middle B.

[0030] Figure 4 This is a structural schematic diagram of the battery acid extraction device of the present invention when the rubber nozzle, acid extraction drainage tube and pressure relief valve are not installed.

[0031] Figure 5 It is a schematic diagram of the cross-sectional structure of the acid extraction drainage tube.

[0032] Figure 6 This is a schematic diagram of the structure of the acid drainage tube when viewed from above.

[0033] Figure 7 It is a schematic diagram of the partial cross-sectional structure of the pressure relief valve.

[0034] Figure 8 It is a schematic diagram of the partial cross-sectional structure of the pressure relief valve from the other direction.

[0035] Figure 9 The figure is a schematic structural diagram of the battery acid extraction device of the present invention in use state.

[0036] Figure 10 for Figure 9 A partial enlarged view of center C.

[0037] Reference numerals: battery 1, battery container 101, battery cover 102, electrode group 103, acid addition hole column 104, acid addition hole 105;

[0038] Acid extraction manifold 2, acid extraction nozzle 3, rubber nozzle 4, acid extraction drainage tube 5; negative pressure interface 6, solenoid valve 7, pressure relief valve 8, hose 9, handle 10, notch 11. DETAILED DESCRIPTION

[0039] Example 1

[0040] like Figures 1 to 10 As shown, a battery acid extraction device is used to add acid to a battery 1. The battery 1 includes a battery container 101 and a battery cover 102 that cover each other. The inner cavity of the battery container 101 is divided into multiple cells, each of which is equipped with a pole group 103. The top surface of the battery cover 102 is provided with an acid addition hole column 104 corresponding to each cell, and the acid addition hole column 104 has an acid addition hole 105 in the center.

[0041] The battery acid extraction device of the present application includes an acid extraction manifold 2. Acid extraction nozzles 3 are provided on one side of the acid extraction manifold 2, corresponding one-to-one with each acid addition hole 105 on the battery 1. The acid extraction nozzles 3 protrude from the sidewall of the acid extraction manifold 2. A rubber nozzle 4 is sleeved on the acid extraction nozzle 3, the end of which is plugged into the acid addition hole column 104 during use. Also mounted on the acid extraction nozzle 3 is an acid extraction drainage tube 5, the end of which extends beyond the rubber nozzle 4 and into the acid addition hole 105 during use. The inner cavity of the acid extraction nozzle 3 has an internal thread, and the acid extraction drainage tube 5 is correspondingly provided with a threaded section having an external thread that mates with the internal thread of the inner cavity of the acid extraction nozzle 3.

[0042] The acid extraction manifold 2 also has a negative pressure interface 6 for connecting to a negative pressure extraction device. A solenoid valve 7 for controlling the opening and closing of the negative pressure interface 6 is provided at the negative pressure interface 6. The acid extraction manifold 2 also has a pressure relief valve 8 for releasing pressure.

[0043] In a preferred embodiment, a hose 9 for connecting a negative pressure extraction device is provided at the negative pressure interface 6. The negative pressure extraction device can be an independent negative pressure blower or a negative pressure system for the entire workshop. The addition of the hose 9 can facilitate the connection of the negative pressure extraction device.

[0044] The acid extraction manifold 2 is provided with a handle 10 for easy operation at a side away from the acid extraction nozzle 3. During use, the acid extraction nozzle 3 side is downward, and the handle 10 side is upward. During use, the staff holds the handle 10 and operates.

[0045] The end of the acid extraction drainage tube 5 that extends into the acid addition hole 105 has a plurality of notches 11 arranged along the circumference. The provision of the notches 11 prevents the end of the acid extraction drainage tube 5 from abutting against the separator in the battery electrode group during acid extraction, thereby preventing the acid extraction drainage tube 5 from being blocked and affecting the normal acid extraction process.

[0046] The inner diameter of a section of the rubber nozzle 4 that is fitted with the acid extraction nozzle 3 is larger than the inner diameter of a section that is fitted with the acid addition hole column 104 .

[0047] When extracting acid from a battery according to the present invention, the acid extraction drainage tube 5 and the rubber nozzle 4 are sequentially assembled onto the acid extraction manifold 2, and then one end of each rubber nozzle 4 is plugged into the acid adding hole column 104. The acid extraction drainage tube 5 is extended into the acid adding hole 105, and each acid extraction nozzle 3 is connected through the acid extraction manifold 2 to uniformly extract negative pressure. The acid extraction manifold 2 is also provided with a negative pressure interface 6 for connecting to a negative pressure extraction device. The negative pressure interface 6 is provided with a solenoid valve 7 for controlling the opening and closing of the negative pressure interface 6. The opening and closing of the solenoid valve 7 is used to accurately control the negative pressure time during acid extraction, thereby improving the consistency of acid absorption between each cell. After the solenoid valve 7 is closed, the interior of the acid extraction manifold 2 is still in a negative pressure state, and the pressure relief valve 8 can be opened to restore the interior of the acid extraction manifold 2 to normal pressure.

[0048] Example 2

[0049] The same batch of semi-finished 6-DZF-20 batteries (with the same plate batch process) was subjected to the internal formation process of the present invention, with one process forming one circuit of batteries (a total of 18 batteries), with a total formation capacity of 208 Ah. The residual acid treatment stage was performed after the capacity check discharge stage, and the acid extraction operation was carried out using the method of the present invention, with a negative pressure of -0.04 to -0.05 MPa maintained for 10 seconds.

[0050] The formation process is shown in Table 1.

[0051] Table 1

[0052]

[0053] Example 3

[0054] The same batch of semi-finished 6-DZF-20 batteries (plate batch process is the same) was formed using the internal formation process of the present invention. One process was used to form 1 circuit battery (a total of 18 batteries), with a total formation capacity of 208Ah. The residual acid treatment stage was carried out after the capacity check discharge stage. The acid extraction operation was carried out using the method of the present invention, and the negative pressure of -0.04 to -0.05 MPa was maintained for 5 seconds.

[0055] The formation process is shown in Table 2. During the capacity check discharge stage (step 7 of the process), the discharge time is limited. When the discharge capacity is 1.05C2Ah, the discharge voltage is around 9.6V, so the case of limiting the discharge voltage to 9.6V is not mentioned here.

[0056] Table 2

[0057]

[0058] Example 4

[0059] The same batch of semi-finished 6-DZF-20 batteries (with the same plate batch process) was subjected to the internal formation process of the present invention, with one process forming one circuit of batteries (a total of 18 batteries), with a total formation capacity of 208 Ah. The residual acid treatment stage was performed after the capacity check discharge stage, and the acid extraction operation was carried out using the method of the present invention, with a negative pressure of -0.04 to -0.05 MPa maintained for 7 seconds.

[0060] The formation process is shown in Table 3. During the capacitance test discharge stage (step 7 of the process), the voltage is limited to 7.2V / cell, and the discharge capacity is 1.09C2Ah, so the 1.10C2Ah case is not mentioned here.

[0061] Table 3

[0062]

[0063]

[0064] Comparative Example 1

[0065] The same batch of semi-finished 6-DZF-20 batteries (using the same plate batch process) was subjected to the internal formation process of the present invention, with one process forming one circuit of batteries (18 in total) with a total formation capacity of 211 Ah. The residual acid treatment phase was performed after the recharge phase, with normal acid extraction starting after a two-hour trickle charge.

[0066] The formation process is shown in Table 4.

[0067] Table 4

[0068]

[0069] Example 5

[0070] Two batteries were extracted from each of Examples 2-4 and Comparative Example 1 to test the liquid absorption saturation of the electrode group, and then grouped according to the normal process for comprehensive performance comparison.

[0071] Table 5 shows the measured values ​​of the liquid absorption saturation of the extreme group after treatment with different residual acids. Referring to the acid absorption saturation test method of publication number CN112103573B, it can be seen from the data comparison results that the liquid absorption saturation of several processes is between 92.6% and 93.8%, which are all within the normal range. When using the method of the present invention, the liquid absorption saturation of the negative pressure of -0.04 to -0.05 MPa decreases with the extension of the holding time, but is still within the effective range.

[0072] The liquid absorption saturation after residual acid treatment has no relationship with the discharge capacity in the capacity inspection stage, but it can be seen from the data in Table 7 that the capacity inspection discharge capacity of the present invention (see Table 5, total discharge capacity 1.2-1.3C2Ah) combined with the residual acid treatment process has a significant relationship with the comprehensive performance of the battery. The data show that the battery consistency of Examples 2-4 of the present invention is significantly better than that of Comparative Example 1, and the cycle life is also longer (on average more than 10%). This is related to the deep discharge degree of capacity inspection discharge. Acid extraction after deep discharge, that is, extracting the residual acid after the battery capacity matches the acid amount (the acid density at this time is between 1.05 and 1.1), can effectively improve the battery consistency, thereby improving the life of the battery pack. The conventional method uses a trickle method to extract acid after the recharge is completed after the capacitor is inspected and discharged (the acid density at this time is between 1.33 and 1.37). First, the acid amount of each cell in the normal capacitor inspection and discharge is not completely matched. Second, processing the residual acid under the premise of incomplete acid amount matching will cause the acid to be extracted when a cell needs more (because the acid has a high specific gravity and more acid is taken away), further causing the problem of inconsistent cells.

[0073] Table 5

[0074]

[0075] Table 6

[0076]

[0077]

[0078] Table 7

[0079]

[0080] The 18 batteries of Examples 2-4 and Comparative Example 1 were all categorized by the voltage when discharged to an average voltage of 10.1V / battery during capacity check (the capacity check discharge time was 120 minutes): that is, the batteries were formed and then left to stand for 24 hours after being taken off the production line. Then, they were grouped by open circuit voltage (OCV) (within 20mV). Table 6 shows the discharge voltage of each battery when discharged to an average voltage of 10.1V / battery. Table 7 shows the test results of each group of batteries after grouping according to the normal process for each scheme. The data show that the battery consistency of Examples 2-4 of the present invention is significantly better than that of Comparative Example 1, and the cycle life is also longer (on average, more than 10% higher).

Claims

1. A lead-acid battery formation and residual acid treatment method, characterized in that: The following steps are involved: (1) When the lead-acid battery is in the stage of formation and capacity inspection, the lead-acid battery is deeply discharged; (2) Perform negative pressure acid extraction on the lead-acid battery, maintaining the negative pressure at -0.04~-0.05Mpa, and the negative pressure acid extraction time is 5~10 seconds; (3) After completing the negative pressure acid extraction, start the recharge phase to fully charge the lead-acid battery. In step (1), during deep discharge, the battery is discharged at a current of 0.5C2 amperes for a fixed time to discharge 100% to 110% of its rated capacity, and then discharged at a current of 0.1C2 to 0.3C2 amperes to an average voltage of 7.2V; Alternatively, during deep discharge in step (1), constant voltage discharge is performed at a current of 0.5C2 ampere until the voltage of a single lead-acid battery is 7.2V~9.6V, and then discharged at a current of 0.1C2~0.3C2 ampere until the average voltage is 7.2V.

2. The lead-acid battery formation and residual acid treatment method according to claim 1, wherein: The battery comprises a battery container and a battery cover that cover each other. The inner cavity of the battery container is divided into a plurality of cells, each of which is equipped with a pole group. The top surface of the battery cover is provided with an acid addition hole column corresponding to each cell, and the center of the acid addition hole column has an acid addition hole. The battery acid extraction device used in step (2) negative pressure acid extraction includes an acid extraction manifold, one side of the acid extraction manifold is provided with an acid extraction nozzle corresponding to each acid addition hole on the battery, the acid extraction nozzle is sleeved with a rubber nozzle whose end is plugged into the acid addition hole column when in use, and the acid extraction nozzle is also equipped with an acid extraction drainage tube whose end extends out of the rubber nozzle and extends into the acid addition hole when in use; the acid extraction manifold also has a negative pressure interface for connecting to a negative pressure extraction device, the negative pressure interface is provided with a solenoid valve for controlling the opening and closing of the negative pressure interface, and the acid extraction manifold also has a pressure relief valve for releasing pressure.

3. The lead-acid battery formation and residual acid treatment method according to claim 2, wherein: The negative pressure interface is provided with a hose for connecting to a negative pressure extraction device.

4. The lead-acid battery formation and residual acid treatment method according to claim 2, wherein: The acid extraction manifold is provided with a handle for easy operation on the side away from the acid extraction nozzle.

5. The lead-acid battery formation and residual acid treatment method according to claim 2, wherein the inner cavity of the acid extraction nozzle has an internal thread, and the acid extraction drainage tube is correspondingly provided with a threaded section, and the threaded section has an external thread that cooperates with the internal thread of the inner cavity of the acid extraction nozzle.

6. The lead-acid battery formation and residual acid treatment method according to claim 2, wherein one end of the acid extraction drainage tube for extending into the acid addition hole has a plurality of notches arranged along the circumferential direction.

7. The lead-acid battery formation and residual acid treatment method according to claim 2, wherein the inner diameter of a section of the rubber nozzle that is fitted with the acid extraction nozzle is larger than the inner diameter of a section that is fitted with the acid addition hole column.

8. The lead-acid battery formation and residual acid treatment method according to claim 1, characterized in that: In step (3), the recharge phase is to first charge at 0.25C2 for 3 hours and then charge at 0.15C2 for 12 hours.

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