A method for manufacturing an agm gel lead storage battery

Abstract

The application discloses a kind of AGM colloidal lead battery manufacturing method.The application is through the deep discharge of battery, and the AGM separator of battery AGM is greatly reduced by the way of vacuum drying after negative pressure acid extraction, so that the colloid can be smoothly added to AGM battery, so that the AGM separator fully absorbs the colloid, so that the distribution of the colloid in the AGM separator is more uniform, thereby facilitating the extension of the service life of the battery pack, while the capacity loss rate can be controlled within 7.5%, even within 5%, compared with the general capacity loss rate of colloidal battery, which greatly reduces the capacity loss rate.

Description

Technical Field

[0001] This invention belongs to the field of lead-acid battery technology, specifically relating to a method for manufacturing an AGM gel lead-acid battery. Background Technology

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

[0003] Gel-VRLA batteries (gel batteries) are a type of lead-acid battery. The simplest way to make them is to add a gelling agent to sulfuric acid to turn the sulfuric acid electrolyte into a gel state.

[0004] For example, the invention with publication number CN103280602A discloses a colloidal electrolyte for lead-acid batteries, including a gelling agent, sulfuric acid and sodium sulfate, wherein the gelling agent includes fumed silica and dispersed silica gel A and dispersed silica gel B with different particle sizes.

[0005] Gel batteries have largely solved the problems associated with AGM-VRLA batteries, such as thermal runaway, poor deep discharge performance, and acid stratification. Therefore, they are widely used in demanding applications. In existing technologies, gel batteries can be manufactured using either raw or matured plates (raw plates are formed into mature plates). When using raw plates, the plates generally need to be formed first, followed by an acid-removing process before the gel electrolyte is added. When using matured plates, after electrode assembly and the addition of the gel electrolyte, no further formation is required, and the battery can be directly charged.

[0006] The aforementioned gel batteries generally employ a flooded electrode assembly method, which uses PVC or phenolic resin separators with minimal assembly pressure, facilitating acid removal and glue application. However, batteries using AGM separators are inherently difficult to manufacture as gel batteries due to the assembly pressure involved.

[0007] Chinese patent application CN107046119A discloses an AGM separator with a soluble colloid. This soluble colloid AGM separator comprises 74-95% glass fiber, 0-8% organic fiber, 2-25% nano-silica, and 0-5% functional additives by mass. The nano-silica has a particle size of 1.5-10 nm and a specific surface area of ​​680-1100 m² / g. This technical solution addresses the difficulty of adding a colloid to AGM separator batteries by adding nano-silica to the separator. During the initial charge-discharge cycles, the nano-silica dissolves into the electrolyte, thus partially realizing the application of a colloidal electrolyte in AGM separator batteries. Summary of the Invention

[0008] This invention addresses the difficulties in manufacturing AGM separator batteries into gel batteries in the prior art by providing a method for manufacturing AGM gel lead-acid batteries. This method combines the performance of AGM batteries and gel batteries, retaining the advantages of both, and forming a more competitive new type of gel battery.

[0009] A method for manufacturing an AGM gel lead-acid battery includes the following steps:

[0010] (1) After assembling the positive plate, negative plate and AGM separator into an electrode group, they are assembled into the battery case to make a semi-finished lead-acid battery.

[0011] (2) After quantitative addition of acid to the rich solution, the formation and charging are carried out, and then the capacity is released to 1.1 to 1.3 times the rated capacity during the deep discharge stage of the formation.

[0012] (3) Turn on the negative pressure to remove the residual acid, and put the lead-acid battery into the vacuum drying oven for drying.

[0013] (4) After drying, remove the lead-acid battery, allow it to cool naturally, and then apply glue.

[0014] (5) After the glue is applied, start the recharge phase to fully charge the lead-acid battery.

[0015] Preferably, in step (1), when assembling the electrode group, the number of positive electrode plates is one less than the number of negative electrode plates. The positive and negative electrode plates are arranged alternately and separated by an AGM separator. The dry pressure of the electrode group is controlled at 45–65 kPa. The assembly pressure directly affects the pore size of the AGM separator. Excessively high assembly pressure should not be used. After compression at 50 kPa, the pore size of the AGM separator is 3–4 micrometers. The actual pore size of the AGM separator in use will decrease as the pressure increases.

[0016] Preferably, in step (2), during the deep discharge stage, the battery is discharged for a fixed time at a current of 0.5C2 amperes to release 100% to 110% of its rated capacity, and then discharged at a current of 0.05C2 to 0.3C2 amperes to release 10% to 20% of its rated capacity. The rated capacity is the nominal capacity of the lead-acid battery, which is the expected amount of electricity released when discharged to 10.5V. Under deep discharge conditions (e.g., discharged to 7.2V), the actual capacity released by the lead-acid battery will exceed the rated capacity. C2 represents the battery's two-hour rate rated capacity. When the charging and discharging current is expressed as a multiple of C2 amperes, only the numerical value of C2 is used, and the unit of current is amperes.

[0017] Discharging the battery to 1.1-1.3 times its rated capacity is clearly deep discharge, fully releasing its capacity. This is to ensure the sulfuric acid is as thoroughly mixed as possible with the positive and negative electrode materials, resulting in an electrolyte with a specific gravity close to water (generally between 1.03 and 1.06). This ensures the acid content within the plates meets the battery's capacity requirements and facilitates subsequent gluing processes. Because the plates have sufficient acid content after deep discharge, there's no need to replenish the acid solution with a mixture of dilute sulfuric acid and colloid during subsequent gluing. Mixing the colloid with dilute sulfuric acid would cause a cross-linking reaction, gradually forming a gel and affecting the uniformity of gluing.

[0018] Preferably, in step (2), the amount of acid added is controlled at 10-11 ml / Ah, and the acid density is 1.22-1.26 g / cm³. 3 The net charge during formation charging before the deep discharge stage is 6.5C2–7.5C2 amp-hours. This is achieved when the density is 1.22–1.26 g / cm³. 3 When using dilute sulfuric acid, electrolyte additives such as stannous sulfate, anhydrous sodium sulfate, and magnesium sulfate can be added.

[0019] To better and more evenly add the colloid to the battery electrode group, the saturation of the battery electrode group needs to be controlled. Preferably, during the negative pressure acid extraction in step (3), the electrode group liquid absorption saturation is controlled at 92% to 100% after the residual acid is extracted, and at 55% to 80% after the battery is vacuum dried. The residual acid treatment method disclosed in the invention application with publication number CN114744299A can be used, or conventional methods can be used. The main difference is the electrode group saturation after acid extraction. Using publication number CN114744299A, the electrode group saturation can generally be controlled at 92% to 94%, while the saturation is basically 100% when using conventional methods for acid extraction. Of course, this is acid extraction without charge, which is different from the method of adding a small current to extract acid in the later stage of charging, because the residual acid treatment in this application is carried out after deep discharge. After the above acid extraction process, the battery is vacuum dried and its electrode group liquid saturation is controlled at 55% to 85.5%. This is to allow the battery electrode group to have more pores to better absorb the colloid.

[0020] Preferably, in step (3), during drying, the vacuum degree is set to -0.085MPa to -0.1MPa, the temperature is set to 55 to 70℃, and the drying time is 2 to 16 hours. Utilizing the principle that water has a low boiling point in a negative pressure environment, water is evaporated, causing the electrode group saturation to decrease.

[0021] Preferably, in step (4), the glue is injected quantitatively by vacuuming, and the vacuuming is performed 2 to 3 times, which is the same as the vacuum acid addition method.

[0022] Preferably, in step (4), the colloid is selected from one or a mixture of two of the following: gaseous silica dispersion and silica sol. The silica particle size of gaseous silica dispersion is generally 100-200 nm, while the silica sol has a smaller particle size, making it easier to add during the colloid addition process.

[0023] More preferably, the content of nano-silica solids in the colloid is 15% to 40% by mass percentage, and the particle size of nano-silica is 3 to 20 nm.

[0024] The amount of solid silica added to the battery is 1.5% to 8.0% of the total mass of the electrolyte.

[0025] The silica solid content is directly related to gel strength; higher content results in better strength and stronger acid-locking ability (i.e., resistance to acid stratification), but also greater capacity loss. This is because higher colloidal content increases internal resistance, leading to capacity loss. More preferably, the silica solid content is controlled between 2.2% and 5% to balance the above relationship.

[0026] Preferably, in step (5), the recharge stage is first charged with a current of 0.25C2 Amperes for 3 hours, and then charged with a current of 0.15C2 Amperes for 12 hours.

[0027] The present invention has the following beneficial effects:

[0028] This invention significantly reduces the liquid saturation of the AGM separator after deep discharge of the battery by using negative pressure acid extraction combined with vacuum drying. This allows the gel to be smoothly added to the AGM battery, enabling the AGM separator to fully absorb the gel and resulting in a more uniform distribution of the gel within the separator. This, in turn, helps extend the battery pack's lifespan. At the same time, the capacity loss rate can be controlled within 7.5%, or even within 5%, which is significantly lower than the typical capacity loss rate of gel batteries, which is generally above 10%. Detailed Implementation

[0029] Example 1

[0030] The specific processes for the same batch of semi-finished 6-DZF-20 batteries (with identical electrode plate batch processes) are as follows:

[0031] Table 1

[0032]

[0033]

[0034] Example 2

[0035] The specific processes for the same batch of semi-finished 6-DZF-20 batteries (with identical electrode plate batch processes) are as follows:

[0036] Table 2

[0037]

[0038] Example 3

[0039] The specific processes for the same batch of semi-finished 6-DZF-20 batteries (with identical electrode plate batch processes) are as follows:

[0040] Table 3

[0041]

[0042]

[0043] Example 4

[0044] The specific processes for the same batch of semi-finished 6-DZF-20 batteries (with identical electrode plate batch processes) are as follows:

[0045] Table 4

[0046]

[0047] Example 5

[0048] The specific processes for the same batch of semi-finished 6-DZF-20 batteries (with identical electrode plate batch processes) are as follows:

[0049] Table 5

[0050]

[0051]

[0052] Example 6

[0053] The specific processes for the same batch of semi-finished 6-DZF-20 batteries (with identical electrode plate batch processes) are as follows:

[0054] Table 6

[0055]

[0056] Comparative Example 1

[0057] The specific processes for the same batch of semi-finished 6-DZF-20 batteries (with identical electrode plate batch processes) are as follows:

[0058] Table 7

[0059]

[0060]

[0061] Comparative Example 2

[0062] Traditional gel batteries are assembled and formed using the same batch of electrode plates (with identical batch processes). The specific process is as follows:

[0063] Table 8

[0064]

[0065] Example 7

[0066] In addition to Examples 1-6 and Comparative Examples 1-2 described above, an experiment was also conducted to mix the colloid with dilute sulfuric acid before formation charging, in order to illustrate the effects of the present invention. Although the colloid mixed with dilute sulfuric acid could be injected into the battery electrode group in a short time, the cross-linking reaction that occurred after mixing with dilute sulfuric acid gradually caused gelation, making formation impossible to complete. Therefore, no further comparative experiments were conducted.

[0067] Two batteries each from Examples 1-6 and Comparative Examples 1-2 were randomly selected for comprehensive performance comparison. The internal resistance and open circuit voltage values ​​in Table 9 were measured 24 hours after the finished battery was produced. The 2-hour capacity test is the time value for discharging from 10A current to 10.5V (the maximum value is taken from three tests). Cycle life test process: (1) Discharge to 10.5V with 10A current; (2) Charge at constant voltage of 14.6V and current limit of 8A for 6 hours; (3) Cycle steps (1) and (2) together. The experiment is terminated when the discharge capacity is lower than 80% of the rated capacity.

[0068] Table 9

[0069]

[0070] First, comparing the capacity baseline, the capacity of the traditional gel battery using phenolic resin separator (Comparative Example 2) is only 88.1% of that of the conventional AGM battery (Comparative Example 1), with a capacity loss of more than 10%. In contrast, the capacity loss of gel batteries using AGM separators in Examples 1 to 5 is within 7.5%, especially in Examples 1, 2, 4, and 6, where the capacity loss rate is within 5%. Example 2 performs the best, followed by Example 1.

[0071] As can be seen from Table 8, the internal resistance increases with the increase of the solid content of the gel, but the higher the solid content, the better the gel strength and the stronger the acid-locking function (i.e., the ability to resist acid stratification), which is beneficial to the cycle life (the overall performance of batteries of different gel types also varies). Overall, the life of AGM gel batteries is more than 100 cycles longer than that of conventional AGM batteries (an increase of more than 30%). Examples 1 and 2 show less capacity loss and longer life, basically retaining the advantages of AGM and gel batteries, and their cycle life is even better than that of traditional gel batteries.

Claims

1. A method for manufacturing an AGM gel lead-acid battery, characterized in that, Includes the following steps: (1) After assembling the positive plate, negative plate and AGM separator into an electrode group, they are assembled into the battery case to make a semi-finished lead-acid battery. (2) After quantitative addition of acid to the rich solution, the formation and charging are carried out, and then the capacity is released to 1.1 to 1.3 times the rated capacity during the deep discharge stage of the formation. (3) Turn on the negative pressure to remove the residual acid, and put the lead-acid battery into the vacuum drying oven for drying. (4) After drying, remove the lead-acid battery, allow it to cool naturally, and then apply glue. (5) After the glue is applied, start the recharge phase to fully charge the lead-acid battery.

2. The method for manufacturing an AGM gel lead-acid battery according to claim 1, characterized in that, In step (1), when assembling the electrode group, the number of positive electrode plates is one less than the number of negative electrode plates. The positive and negative electrode plates are arranged alternately and separated by AGM separators. The dry pressure of the electrode group is controlled at 45-65 kPa.

3. The method for manufacturing an AGM gel lead-acid battery according to claim 1, characterized in that, In step (2), during the deep discharge stage, a discharge is performed for a fixed time with a current of 0.5C2 Amperes to discharge 100% to 110% of its rated capacity, and then a discharge is performed with a current of 0.05C2 to 0.3C2 Amperes to discharge 10% to 20% of its rated capacity.

4. The method for manufacturing an AGM gel lead-acid battery according to claim 1, characterized in that, In step (2), the amount of acid added is controlled at 10-11 ml / Ah, and the acid density is 1.22-1.26 g / cm³. 3 The net charge amount during the formation charge before the deep discharge stage is 6.5C2 to 7.5C2 amp-hours.

5. The method for manufacturing an AGM gel lead-acid battery according to claim 1, characterized in that, When the residual acid is removed in step (3), the saturation of the electrode group is controlled at 92% to 100% after the residual acid is removed. After the battery is vacuum dried, the saturation of the electrode group is controlled at 55% to 85.5%.

6. The method for manufacturing an AGM gel lead-acid battery according to claim 1, characterized in that, In step (3), during drying, the vacuum degree is set to -0.085MPa to -0.1MPa, the temperature is set to 55 to 70℃, and the drying time is 2 to 16 hours.

7. The method for manufacturing an AGM gel lead-acid battery according to claim 1, characterized in that, In step (4), vacuum injection is used for quantitative injection during glue addition, with 2 to 3 vacuum cycles.

8. The method for manufacturing an AGM gel lead-acid battery according to claim 1, characterized in that, In step (4), the colloid is selected from one or a mixture of two of the following: gaseous silica dispersion and silica sol.

9. The method for manufacturing an AGM gel lead-acid battery according to claim 8, characterized in that, The content of nano-silica solids in the colloid is 15% to 40% by mass percentage, and the particle size of nano-silica is 3 to 20 nm. The amount of solid silica added to the battery is 1.5% to 8.0% of the total mass of the electrolyte.

10. The method for manufacturing an AGM gel lead-acid battery according to claim 1, characterized in that, In step (5), during the recharge phase, the device is first charged with a current of 0.25C2 Amperes for 3 hours, and then charged with a current of 0.15C2 Amperes for 12 hours.

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