Electrolyte for lead storage battery and use thereof

Abstract

An electrolyte for a lead storage battery, and a use thereof, belonging to the technical field of lead storage battery production. Improving the electrolyte by means of adding a surfactant changes the surface tension of the electrolyte, and can thus slow the phenomenon of delamination of the electrolyte from a source. Additionally, the introduced surfactant forms a stable complex by means of capturing lead ions in the electrolyte, thereby preventing the formation of lead dendrites and reducing the risk of short circuits.

Description

Electrolyte for lead storage battery and application thereof TECHNICAL FIELD

[0001] The present application belongs to the technical field of lead storage battery production, and particularly relates to an electrolyte for lead storage battery and application thereof. BACKGROUND

[0002] Valve regulated lead-acid battery (VRLA battery) as a kind of efficient and reliable energy storage device has been widely used in power systems, UPS power sources, railway systems, communication equipment and various emergency equipment. Its core advantages lie in its maintenance-free characteristics and long service life, which are largely attributed to the AGM (Absorbent Glass Mat) separator used. As a key component of VRLA battery, the AGM separator not only has excellent acid corrosion resistance, high porosity and good insulation performance, but also can effectively fix the electrolyte and provide hydrogen-oxygen composite channels during charging and discharging, thereby realizing the maintenance-free function of the battery and improving the overall performance of the battery.

[0003] However, although the AGM separator performs well in VRLA battery, its shortcomings gradually appear in specific application scenarios such as stationary applications and deep cycle power batteries, which significantly restricts the cycle service life of the battery. The main problems are concentrated in two aspects: electrolyte stratification and lead dendrite short circuit.

[0004] I. Electrolyte stratification problem

[0005] Electrolyte stratification is a common problem in VRLA batteries, especially under long-term operation or extreme working conditions. Due to the influence of electrolyte surface tension and separator characteristics, the electrolyte density inside the battery will be uneven along the height direction, which is manifested as the sulfuric acid content at the bottom being significantly higher than that in the middle and upper parts. This stratification phenomenon leads to the intensification of positive and negative electrode sulfation, the damage of positive electrode structure, the appearance of softening phenomenon, and the more irreversible sulfation of negative electrode. Ultimately, the positive and negative electrodes fail, and the battery capacity significantly decreases.

[0006] To solve the problem of electrolyte stratification, the current main method is to adjust the ratio of coarse and fine cotton in the separator formula. Increasing the fine cotton ratio can enhance the anti-stratification ability of the separator, but at the same time, it will reduce the wet state pressure, which has a negative impact on the battery life. Therefore, manufacturers need to carefully balance the formula design to maintain a certain wet state pressure while improving the anti-stratification ability as much as possible. However, for the thin separator of extreme design, especially when the thickness is less than 0.50mm (100kPa), the problem of electrolyte stratification is still serious, which seriously restricts the cycle life of the battery.

[0007] II. Lead dendrite short circuit problem

[0008] Lead dendrite short circuit is another major challenge faced by VRLA batteries during long-term use. During charge-discharge cycling, lead ions are constantly dissolved and precipitated, eventually accumulating into lead dendrites on the internal fibers of the separator. As the number of cycles increases, lead dendrites can penetrate the separator, causing micro-short circuits between the positive and negative electrodes, which in turn leads to voltage drop and shortened battery discharge time. For stationary batteries, the risk of lead dendrite short circuit is higher due to long-term storage. Thin separators are more prone to micro-short circuits during cycling due to their relatively low structural strength, further accelerating the decay of battery capacity.

[0009] To address the problem of lead dendrite short circuit, various strategies have been adopted, including controlling the discharge rate of the battery, adding additives to stabilize the electrolyte, and using external circuits to limit dendrite growth. However, these measures have limited effectiveness in practical applications, especially for long-term running and high-intensity cycling battery systems, further exploration of more effective solutions is needed. SUMMARY

[0010] Based on the deficiencies in the prior art, the present application provides an electrolyte for lead-acid batteries and its application, which improves the electrolyte by adding a surfactant, solving the problems of electrolyte stratification and lead dendrite short circuit.

[0011] The specific technical solutions of the present application are as follows:

[0012] An electrolyte for lead-acid batteries, the electrolyte for lead-acid batteries comprises sulfuric acid and an additive, the additive comprises the following raw materials: inorganic salt 0.5% to 1.0% and surfactant 0.05% to 0.20% by mass of sulfuric acid;

[0013] Wherein, the inorganic salt is anhydrous sodium sulfate, and the surfactant is at least one of sodium dodecyl sulfate and sodium dodecyl benzene sulfonate.

[0014] Preferably, the mass fraction of sulfuric acid is 31% to 35%. The sulfuric acid used in the present application is diluted from concentrated sulfuric acid, the density of concentrated sulfuric acid is 1.83 g / cm 3 , and the mass fraction is 98.3%.

[0015] Preferably, when the surfactant is sodium dodecyl sulfate and sodium dodecyl benzene sulfonate, the mass fraction of sodium dodecyl sulfate in the surfactant is not less than 50%.

[0016] On the one hand, the surfactants used are sodium dodecyl sulfate and sodium dodecylbenzene sulfonate, and the effect of adding both in combination is better than using either one. On the other hand, after the surfactant is added during the formation process, foaming occurs, and the foam flows out, resulting in a loss of the added surfactant. In severe cases, it can even lead to a short circuit. Experiments have shown that the most crucial factor is controlling the ratio of sodium dodecyl sulfate to sodium dodecylbenzene sulfonate in the surfactant. By increasing the proportion of sodium dodecyl sulfate, foaming can be controlled. Finally, the foaming phenomenon can also be controlled to some extent by controlling the amount of inorganic salt added and the formation voltage.

[0017] The present invention also provides the application of the electrolyte for lead-acid batteries in the preparation of lead-acid batteries.

[0018] Specifically, when the separator thickness h of the lead-acid battery is less than 0.5 mm, the amount of surfactant added is not less than 0.1%; when the separator thickness h of the lead-acid battery is greater than or equal to 0.5 mm, the amount of surfactant added is not more than 0.18%.

[0019] Furthermore, let H be the height of the plates and L be the distance between the positive and negative plates.

[0020] Different battery performance requirements and different design parameters result in different resistance to stratification. Batteries can be distinguished by their H and L designations.

[0021] H represents the electrode height, which determines the battery capacity and the likelihood of delamination. A higher H indicates a greater likelihood of delamination. L represents the distance between the positive and negative electrodes, which determines the thickness of the separator. A smaller L results in a thinner separator, making it more prone to dendrite short circuits and less substrate material, further contributing to delamination. In such cases, a fine cotton separator with good anti-delamination properties is typically chosen. However, thinner separators cannot solve the aforementioned problems and are more expensive. Conversely, a thicker separator with more substrate material allows for the use of a coarse cotton separator. However, coarse cotton separators have an inherent disadvantage in delamination, necessitating consideration of reducing delamination through electrolyte formulation.

[0022] In battery design, H and L are actually two important parameters. Usually, batteries are not too short, because if they are too short, it is difficult to achieve the required capacity. Therefore, H will be kept at a certain value, that is, the H / L ratio. From this perspective, it depends on L. The larger L is, the smaller the H / L ratio is, the wider the distance between the positive and negative sides is, the less likely it is to dendrite short circuit, and the easier it is to add acid and control the temperature. However, the battery specific energy will be lower.

[0023] The smaller L is, the narrower the distance between the positive and negative sides becomes, resulting in a larger H / L value, which makes dendrite short circuits more likely and temperature control more difficult. Therefore, the present invention aims to solve the problem of separator delamination by using an electrolyte.

[0024] When the separator thickness h of the lead-acid battery is less than 0.5 mm, the amount of surfactant added shall not be less than 0.15% when H / L > 120; and the amount of surfactant added shall be less than 0.15% when H / L ≤ 120.

[0025] If the thickness of the separator is less than 0.5mm, it means that the separator base itself is very thin. As mentioned above, the separator that prevents delamination cannot solve the problem. If H / L>120, it means that L is very small. A separator with a thickness of 0.45mm is selected. In the experiment, in order to prevent delamination and short circuit, the amount of surfactant added should not be less than 0.15%, and the effect is better. If H / L≤120, L is slightly larger, and the thickness of the separator should be slightly larger. From the perspective of experimental effect and cost, the amount of surfactant added should be less than 0.15%.

[0026] When the separator thickness h of the lead-acid battery is ≥0.5mm, the amount of surfactant added is 0.15% to 0.18% when H / L >120; and 0.05% to 0.10% when H / L ≤120.

[0027] If the thickness of the partition is greater than 0.5mm, it means that the partition base itself is barely adequate. A partition that resists delamination can solve some of the problems, but the price of the partition will be much higher. In order to control design costs, partitions with this thickness are usually made of coarse cotton, which naturally reduces the anti-delamination effect.

[0028] Therefore, if H / L > 120, meaning L is very small, for example, if the thickness of the separator is 0.52mm, in the experiment, in order to prevent delamination and short circuit, the addition amount is 0.15% to 0.18%, and the effect is also relatively good. If H / L ≤ 120, L is too large, the thickness of the separator base is perfectly adequate, but delamination will still occur. However, from the perspective of experimental effect and cost, the addition amount of surfactant is 0.05% to 0.10%, which can solve the problem.

[0029] Specifically, the preparation method of the electrolyte for lead-acid batteries includes the following steps:

[0030] Sulfuric acid used in the preparation of chemical reactions;

[0031] The surfactant is added to the prepared sulfuric acid according to the thickness of the separator, the height of the plates, and the distance between the positive and negative plates of the lead-acid battery. Then, the inorganic salt is added to obtain the electrolyte for the lead-acid battery.

[0032] Specifically, the following steps are included:

[0033] 1) Prepare dilute sulfuric acid according to the required mass fraction of dilute sulfuric acid for this batch of formation. The amount of dilute sulfuric acid is A (kg). Calculate the amount of concentrated sulfuric acid B (kg). Calculate the amount of pure water C (kg) required to prepare the dilute sulfuric acid. Weigh 0.8C (kg) of pure water and slowly add the weighed concentrated sulfuric acid B (kg). Let it cool down before use.

[0034] 2) Weigh 0.2C (kg) of pure water. Based on the design parameters (h and H / L) of this batch of batteries, determine the addition ratio. Weigh out the surfactant according to mass A (kg) and dissolve it in the pure water. The surfactant can be sodium dodecyl sulfate or sodium dodecylbenzene sulfonate alone, or a mixture of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate. When it is a mixture of two, the proportion of sodium dodecyl sulfate in the mixed sample should not be less than 50%. Stir until the surfactant is completely dissolved in the pure water and set aside for use.

[0035] 3) Add the surfactant solution prepared in step (2) to the dilute sulfuric acid prepared in step (1);

[0036] 4) Finally, add a certain proportion of anhydrous sodium sulfate according to mass A (kg);

[0037] 5) Cool the prepared electrolyte to the range of 0℃~5℃ and set aside for later use.

[0038] The prepared electrolyte is added to the acid-adding machine according to the amount of batteries to be added in this batch, and the acid-adding volume is set to complete the acid addition.

[0039] After adding acid, cool in a water-cooling tank (water temperature below 20℃) for no less than 25 minutes.

[0040] After cooling, it flows into the formation tank and begins charging and formation.

[0041] Because surfactants are prone to foaming, during the formation stage of lead-acid battery manufacturing, the formation current is controlled and the formation voltage is kept below 16.5V to prevent foaming and ensure the amount of surfactant added.

[0042] The beneficial effects of this invention are:

[0043] This invention improves the electrolyte by adding a surfactant to change the surface tension of the electrolyte, which can reduce the stratification phenomenon of the electrolyte from the source. At the same time, the introduced surfactant captures lead ions in the electrolyte to form a stable complex, avoiding the formation of lead dendrites and reducing the risk of short circuit. Attached Figure Description

[0044] Figure 1 shows lead dendrites in the AGM separator of battery number 9 in Example 3.

[0045] Figure 2 shows lead dendrites in the AGM separator of battery number 14 in Example 3.

[0046] Figure 3 shows lead dendrites in the AGM separator of battery number 1 in Example 4.

[0047] Figure 4 shows lead dendrites in the AGM separator of battery number 7 in Example 4.

[0048] Figure 5 shows lead dendrites in the AGM separator of battery number 4 in Example 5.

[0049] Figure 6 shows lead dendrites in the AGM separator of battery number 7 in Example 5. Detailed Implementation

[0050] In electrolyte preparation and battery use, if the sulfuric acid concentration is less than 31%, the initial capacity will be too low and it will be difficult to meet the standard requirements. If it exceeds 35%, the open circuit voltage of the battery will be too high, which will seriously affect the battery's lifespan. The typical range is 31% to 35%. This invention uses a concentration of 32% as an example.

[0051] The required electrolyte concentration is 32%, and the weight is 100 kg. Using 51% concentrated sulfuric acid as the mother liquor, 62.75 kg of mother acid is weighed. The required amount of pure water is calculated as follows:

[0052] 100kg - 62.75kg = 37.25kg;

[0053] Divide the pure water into two portions, one portion being 29.80 kg, which is 37.25 kg × 0.8 = 29.80 kg;

[0054] The remaining portion weighs: 37.25kg - 29.80kg = 7.45kg;

[0055] Slowly pour 62.75 kg of sulfuric acid mother liquor into 29.80 kg of pure water, stir well, and cool to room temperature before use.

[0056] Depending on the battery design, different formulations are selected. Based on 100 kg, the additive (surfactant) is weighed out at a rate of 0.05% to 0.20%. The additive is added to 7.45 kg of pure water and stirred until all the additives are completely dissolved. Then, it is poured into a solution of dilute sulfuric acid that has been cooled to room temperature.

[0057] Weigh out 0.5% to 1.0% of anhydrous sodium sulfate (inorganic salt) per 100 kg of solution, add it to dilute sulfuric acid, stir well, and the electrolyte is ready.

[0058] Place the electrolyte in a low-temperature chamber and cool it to the range of 0℃~5℃ for later use.

[0059] Example 1

[0060] Based on the above configuration method, different electrolyte formulations were designed. The additives were one or a mixture of sodium dodecyl sulfate or sodium dodecylbenzenesulfonate, and the inorganic salt additive was anhydrous sodium sulfate. During the formation stage, the voltage usually reaches about 16.5V. The voltage can be controlled to not exceed 16.5V. If the electrolyte foams and a large amount of foam flows out, it proves that the electrolyte formulation is not acceptable, as shown in Table 1 below.

[0061] Table 1

[0062] As shown in Table 1, when the amount of anhydrous sodium sulfate added is less than 0.50% or more than 1.0%, foaming is likely to occur regardless of whether sodium dodecyl sulfate or sodium dodecylbenzene sulfonate is added alone or in combination.

[0063] The amount of anhydrous sodium sulfate added should be controlled within the range of 0.5% to 1.0%. Sodium dodecyl sulfate or sodium dodecylbenzene sulfonate, whether added alone or in combination, should not exceed 0.20% in total.

[0064] Example 2

[0065] A type A battery was selected as the experimental battery, with an electrode plate height of 120 mm, a positive and negative electrode plate spacing of 0.885 mm, and a separator thickness of 0.48 mm (100 kPa).

[0066] The electrolyte formulation available in Example 1 was selected for experimentation. The battery was dissected at 0 cycles (i.e., the initial state), 100 cycles, 300 cycles, and the end of its lifespan. The dissection requirement was that after being fully charged, the resting time should not exceed 10 minutes. After dissection, the separator was cut into three parts proportionally along the height direction: the upper, middle, and lower parts. Each part was subjected to acid extraction, filtration, and chemical titration to test the sulfuric acid mass fraction of the electrolyte. The range of the upper, middle, and lower parts was used to reflect the stratification of the electrolyte. At the same time, the separator at the end of its lifespan was selected, washed and dried, and then characterized by SEM to measure the size of the lead sulfate particles. The larger the grain size, the higher the probability of a short circuit.

[0067] Semi-finished batteries from the same batch were selected as a control sample, and only sodium sulfate was added to the electrolyte.

[0068] Table 2

[0069] The results in Table 2 show that the amount of surfactant added should not be less than 0.15%, and the effect of adding sodium dodecyl sulfate and sodium dodecylbenzene sulfonate together is better than adding them alone. When adding them together, the effect is better when the mass ratio of sodium dodecyl sulfate exceeds 50%.

[0070] Increasing the amount added to 0.20% will yield even better results, but it will also increase manufacturing costs.

[0071] Example 3

[0072] Battery B was selected as the experimental battery. A and B have the same type of casing, but are designed with different capacities and different plate height directions. The plate height of battery B is 100mm, the distance between the positive and negative plates is 0.885mm, and the thickness of the separator used is 0.48mm (100kPa).

[0073] The electrolyte formulation available in Example 1 was selected for experimentation. The battery was dissected at 0 cycles (i.e., the initial state), 100 cycles, 300 cycles, and the end of its lifespan. The dissection requirement was that after being fully charged, the resting time should not exceed 10 minutes. After dissection, the separator was cut into three parts proportionally along the height direction: upper, middle, and lower. Each part was subjected to acid extraction, filtration, and chemical titration to test the sulfuric acid mass fraction of the electrolyte. The range of the upper, middle, and lower parts was used to reflect the stratification of the electrolyte. At the same time, the separator at the end of its lifespan was selected, washed and dried, and then characterized by SEM to measure the size of the lead sulfate particles. The larger the grain size, the higher the probability of a short circuit.

[0074] Semi-finished batteries from the same batch were selected as a control sample, and only sodium sulfate was added to the electrolyte.

[0075] Table 3

[0076] The lead dendrite patterns in the AGM separators of batteries numbered 9 and 14 are shown in Figures 1 and 2, respectively. Combining the data in Table 3, Figure 1 shows that the grain size is approximately 3 μm, much smaller than the control samples (batteries numbered 1 and 2 in this embodiment), indicating a significant improvement. In this embodiment, batteries numbered 3-10 were treated with a single surfactant addition. As the surfactant content increased, the lead dendrite size gradually decreased. When the addition amount reached 0.15%, further increases in the addition amount resulted in a grain size of approximately 3 μm. Combining the results in Figure 2 and Table 3, batteries numbered 11-20 used a mixed surfactant. From batteries numbered 11-12, it can be seen that when the total amount of the mixed surfactant added did not exceed 0.10%, the grain size was greater than 12 μm. For batteries numbered 13-14, when the total amount of the mixed surfactant added was 0.10%, the grain size decreased, and the grain size gradually decreased as the proportion of sodium dodecyl sulfate in the mixed surfactant increased.

[0077] Based on the above results, the effect of adding surfactant in the range of 0.10% to 0.15% is more ideal and significantly better than the control sample. When the amount added reaches 0.15%, further increasing the amount does not improve the effect.

[0078] Furthermore, the combined addition of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate is more effective than adding them alone. When added together, the effect is even better when the mass ratio of sodium dodecyl sulfate exceeds 50%.

[0079] Example 4

[0080] Battery C was selected as the experimental battery. A, B, and C have the same type of casing but are designed with different capacities. Battery C has the same plate height of 120mm as battery A, the distance between the positive and negative plates is 0.980mm, and the selected separator thickness is 0.52mm (100kPa).

[0081] A suitable electrolyte formulation was selected and experiments were conducted. The battery was dissected at 0 cycles (initial state), 100 cycles, 300 cycles, and end of life. The dissection requirement was that after full charging, the resting time should not exceed 10 minutes. After dissection, the separator was cut into three parts proportionally along the height direction: upper, middle, and lower. The upper, middle, and lower parts were individually subjected to acid extraction, filtration, and chemical titration to test the sulfuric acid mass fraction of the electrolyte. The range of the upper, middle, and lower parts was used to reflect the stratification of the electrolyte. At the same time, the separator at the end of life was selected, washed and dried, and then characterized by SEM to measure the size of the lead sulfate particles. The larger the grain size, the higher the probability of short circuit.

[0082] Semi-finished batteries from the same batch were selected as a control sample, and only sodium sulfate was added to the electrolyte.

[0083] Table 4

[0084] The lead dendrite patterns in the AGM separators of batteries numbered 1 and 7 are shown in Figures 3 and 4, respectively. Battery number 1 is the control sample, with only inorganic salt added. As can be seen, the crystal size exceeds 14 μm, making the battery prone to short circuits. In battery number 7, by adding sodium dodecylbenzenesulfonate alone, the proportion of inorganic salt was increased, and the crystal size was significantly reduced. From the results in Table 4, the surfactant addition range of 0.15%–0.18% showed the best effect, significantly better than the control sample. When the addition reached 0.18%, further increasing the addition did not improve the effect further.

[0085] Furthermore, the combined addition of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate is more effective than adding them alone. When added together, the effect is even better when the mass ratio of sodium dodecyl sulfate exceeds 50%.

[0086] Example 5

[0087] Battery D was selected as the experimental battery. A, B, C and D have the same type of casing but are designed with different capacities. Battery D has a plate height of 100 mm, the same as battery B, a positive and negative plate spacing of 0.980 mm, and a separator thickness of 0.52 mm (100 kPa).

[0088] A suitable electrolyte formulation was selected and experiments were conducted. The battery was dissected at 0 cycles (initial state), 100 cycles, 300 cycles, and end of life. The dissection requirement was that after full charging, the resting time should not exceed 10 minutes. After dissection, the separator was cut into three parts proportionally along the height direction: upper, middle, and lower. The upper, middle, and lower parts were individually subjected to acid extraction, filtration, and chemical titration to test the sulfuric acid mass fraction of the electrolyte. The range of the upper, middle, and lower parts was used to reflect the stratification of the electrolyte. At the same time, the separator at the end of life was selected, washed and dried, and then characterized by SEM to measure the size of the lead sulfate particles. The larger the grain size, the higher the probability of short circuit.

[0089] Semi-finished batteries from the same batch were selected as a control sample, and only sodium sulfate was added to the electrolyte.

[0090] Table 5

[0091] The lead dendrite patterns in the AGM separators of batteries 4 and 7 are shown in Figures 5 and 6, respectively. In battery 4, by adding 0.05% sodium dodecyl sulfate to the inorganic salt additive, compared to battery 1, the grain size decreased to 4 μm, indicating a significant slowdown in grain growth. In battery 7, by adding 0.04% sodium dodecylbenzenesulfonate to the inorganic salt additive, compared to battery 2, the grain size decreased to 7 μm, also indicating a significant slowdown in grain growth. From the results in Table 5, the surfactant addition range of 0.05%–0.10% showed the best effect, significantly better than the control sample. When the addition reached 0.10%, further increases in the addition did not improve the effect further.

[0092] Furthermore, the combined addition of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate is more effective than adding them alone. When added together, the effect is even better when the mass ratio of sodium dodecyl sulfate exceeds 50%.

Claims

1. An electrolyte for lead-acid batteries, characterized in that, The electrolyte for lead-acid batteries includes sulfuric acid and additives. Based on the mass of sulfuric acid, the additives include the following raw materials: 0.5% to 1.0% inorganic salts and 0.04% to 0.20% surfactants. The inorganic salt is anhydrous sodium sulfate, and the surfactant is at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

2. The electrolyte for lead-acid batteries according to claim 1, characterized in that, The sulfuric acid has a mass fraction of 31% to 35%.

3. The electrolyte for lead-acid batteries according to claim 1, characterized in that, When the surfactant is sodium dodecyl sulfate and sodium dodecylbenzene sulfonate, the mass ratio of sodium dodecyl sulfate to the surfactant is not less than 50%.

4. The application of the electrolyte for lead-acid batteries according to any one of claims 1 to 3 in the preparation of lead-acid batteries.

5. The application according to claim 4, characterized in that, When the thickness h of the separator of the lead-acid battery is less than 0.5 mm, the amount of surfactant added shall not be less than 0.1%; when the thickness h of the separator of the lead-acid battery is greater than or equal to 0.5 mm, the amount of surfactant added shall not be greater than 0.18%.

6. The application according to claim 5, characterized in that, Let H be the height of the plates, and L be the distance between the positive and negative plates. When the separator thickness h of the lead-acid battery is less than 0.5 mm, the amount of surfactant added shall not be less than 0.15% when H / L > 120; and the amount of surfactant added shall be less than 0.15% when H / L ≤ 120. When the separator thickness h of the lead-acid battery is ≥0.5mm, the amount of surfactant added is 0.15% to 0.18% when H / L >120; and 0.05% to 0.10% when H / L ≤120.

7. The application according to claim 6, characterized in that, The method for preparing the electrolyte for lead-acid batteries includes the following steps: Sulfuric acid used in the preparation of chemical reactions; The surfactant is added to the prepared sulfuric acid according to the thickness of the separator, the height of the plates, and the distance between the positive and negative plates of the lead-acid battery. Then, the inorganic salt is added to obtain the electrolyte for the lead-acid battery.

8. The application according to claim 4, characterized in that, When manufacturing lead-acid batteries, the voltage formed should not exceed 16.5V.

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