Additive acid synthesis method for preventing dendritic crystal short circuit and application

Abstract

The invention belongs to the technical field of power type lead-acid storage batteries, and particularly relates to an acid addition forming method for preventing dendritic crystal short circuit and application, and the acid addition forming method comprises the following five steps: S1, carrying out deep low-temperature treatment on a semi-finished product battery; s2, freezing treatment of the gel electrolyte; s3, vacuumizing and adding acid under negative pressure for multiple times; s4, carrying out rapid cooling treatment on the battery; and S5, formation. According to the invention, the problem that the thin AGM separator lead-acid storage battery is easy to generate dendritic crystal short circuit after being filled with electrolyte is solved, the dendritic crystal penetration ratio is reduced to 0%, and the dendritic crystal hidden danger of a continuous casting and rolling polar plate is thoroughly solved, so that the performance of the prepared battery can be kept at 75% or above in a low-temperature environment of-18 DEG C, and the service life of the battery is prolonged. And the harsh environmental requirements of the power battery are met.

Description

Technical Field

[0001] The invention belongs to the technical field of power-type lead-acid batteries, and particularly relates to an acidification formation method for preventing dendrite short circuit and its application. Background Art

[0002] Power lead-acid batteries, as an important energy storage device, are widely used in applications such as electric scooters, electric tricycles, and special vehicles. Filling the electrolyte, primarily composed of dilute sulfuric acid, is a critical step in the lead-acid battery production process. However, after electrolyte filling, the dilute sulfuric acid in the plates reacts violently with the electrolyte, producing lead sulfate and water, releasing significant heat. During this process, the internal battery temperature can rapidly rise above 80°C, and localized areas may become alkaline due to the consumption of sulfuric acid. Under high temperature and alkaline conditions, the solubility of lead sulfate increases dramatically, causing some of it to migrate into the separator paper. As the electrolyte temperature gradually decreases and the acidic environment returns, the lead sulfate in the separator paper redeposits and transforms into conductive lead dendrites during the formation process. If these lead dendrites connect the positive and negative plates, they can easily cause a short circuit, leading to battery failure. As battery manufacturers pursue greater efficiency and product quality, continuous casting and rolling processes have become widely adopted in lead-acid battery manufacturing. However, the surface of the plates produced by the continuous casting and rolling process is primarily composed of lead oxide. Compared to traditional double-sided coating processes, batteries manufactured using this process are more susceptible to dendrite shorting after electrolyte filling. This is especially true in batteries using thin AGM separators (absorbent glass fiber separators). Because the separators absorb less electrolyte, the lead oxide content in the active material is higher. This leads to greater battery heat generation after electrolyte filling and a higher probability of developing localized alkaline areas, making dendrite shorting more likely. Dendrite shorting can not only cause battery failure during the formation stage but can also gradually grow during the battery's charge and discharge cycles, causing micro-shorts in the battery, seriously impacting its lifespan and safety.

[0003] In order to alleviate the problem of dendrite short-circuiting, improvements have been made from the perspective of materials and structures. For example, patent CN106684297A - a high specific surface area AGM separator and its application, which reduces the pore size of the separator by adding nano-silicon dioxide and uses a complex pore structure to physically block the dendrite short-circuiting problem, but this method does not solve the high temperature and ion migration problems during the acid addition process; another example is patent CN219226360U - a solid-state lithium battery that prevents internal short circuits, which changes the growth direction of lithium dendrites and blocks dendrite penetration through multi-layer electrolytes, but cannot migrate to the lead-acid system, and the complex structure makes manufacturing difficult.

[0004] In the prior art, there are studies aimed at alleviating the problem of battery performance degradation and safety hazards caused by high temperatures by temperature control, such as patent CN114361609A - Power Battery Internal Formation High-Temperature Acid Addition Process, which controls the acid addition temperature and cooling method to prevent battery damage due to high temperatures during the formation process; another example is patent CN107492682A - Lead-Acid Battery Internal Formation Process Without Circulating Cooling Water, which achieves an internal formation process without circulating cooling water through formation pretreatment and specific formation treatment steps. Therefore, the existing formation process is difficult to suppress the sharp temperature rise due to insufficient pre-cooling treatment, and the conventional dilute sulfuric acid electrolyte used lacks additives to inhibit lead ion migration, which cannot reduce the solubility of lead sulfate. Water bath cooling or static cooling is time-consuming and cannot quickly reduce the temperature during the critical window period. Moreover, there is no reverse charging stage, resulting in excessive internal resistance of the plate, which easily causes excessive charging voltage and promotes the formation of dendrites.

[0005] In summary, whether mitigating the dendrite shorting problem through material and structural design, or mitigating the battery performance degradation and safety hazards caused by high temperatures through temperature control, neither can fundamentally suppress the dendrite shorting problem, which seriously affects the battery's service life and safety. Therefore, a new technical solution is needed to solve the above technical problems. Summary of the Invention

[0006] The purpose of the present invention is to provide an acidification method and application for preventing dendrite short circuiting, so as to solve the problem raised in the above background technology that at present, whether it is to alleviate dendrite short circuiting through materials and structures, or to alleviate battery performance degradation and safety hazards caused by high temperature through temperature control, it is impossible to suppress dendrite short circuiting from the root, thereby seriously affecting the service life and safety of the battery.

[0007] To achieve the above object, the present invention provides the following technical solution: an acidification method for preventing dendrite short circuit, comprising the following specific steps: S1. Cooling the semi-finished battery at -8 to -12°C for 1 to 2 days, wherein the semi-finished battery includes positive and negative plates, AGM separator paper, and battery casing produced by continuous casting and rolling; S2, freezing a colloidal electrolyte prepared by mixing 32.9-33.1% sulfuric acid, 0.3-0.7% colloidal dioxide, 1.0-2.0% sodium sulfate, 0.1-0.5% sodium silicate, 0.05-0.2% stannous sulfate, 0.01-0.05% sodium benzoate and water in a freezer to -5-5°C; S3. At an ambient temperature of ≤15°C, the frozen colloidal electrolyte is added to the semi-finished battery 3 to 5 times by using an acid adding device in a manner of first vacuuming and then injecting compressed air. The vacuuming is to vacuum the interior of the semi-finished battery at a vacuum pressure of -0.085 to -0.01 MPa for 10 to 20 seconds and then inject the colloidal electrolyte; the compressed air injection is to inject air at a pressure of 0.4 to 0.6 MPa into the acid adding device for 4 to 10 seconds to force the colloidal electrolyte into the interior of the semi-finished battery. S4. Place the battery injected with the colloidal electrolyte in 2-10°C cooling water within 2-4 minutes after the injection of the colloidal electrolyte for 30-40 minutes to cool; S5. Transfer the cooled battery to the charging water tank and perform formation in 15 stages of 1 reverse charge, 9 charges and 5 discharges. The formation must be completed within 2 hours of adding the colloidal electrolyte, and the temperature of the circulating cooling water must be controlled at 30-40°C during formation. The 15 formation stages are as follows: the first stage adopts the reverse charge mode for a control time of 0.5 hours and a control current of 0.05C; the second stage adopts the charge mode for a control time of 1 hour and a control current of 0.1C; the third stage adopts the charge mode for a control time of 1 hour and a control current of 0.2C; the fourth stage adopts the charge mode for a control time of 8 hours and a control current of 0.5C; the fifth stage adopts the discharge mode for a control time of 0.5 hours and a control current of 0.5C; the sixth stage adopts the charge mode for a control time of 4 hours and a control current of 0.5C; the seventh stage adopts the discharge mode for a control time of 1 hour and a control current of 0.5C. The charging mode is used for controlling time of 0.5h and current of 0.5C; the eighth stage adopts charging mode for controlling time of 4h and current of 0.5C; the ninth stage adopts discharging mode for controlling time of 1h and current of 0.5C; the tenth stage adopts charging mode for controlling time of 4h and current of 0.5C; the eleventh stage adopts discharging mode for controlling time of 1.5h and current of 0.5C; the twelfth stage adopts charging mode for controlling time of 4h and current of 0.5C; the thirteenth stage adopts discharging mode for controlling time of 2h and current of 0.5C, and discharges to an average of 1.75V / cell; the fourteenth stage adopts charging mode for controlling time of 4h and current of 0.5C; the fourteenth stage adopts charging mode for controlling time of 3h and current of 0.04C, and acid is extracted after charging for 2h; the above C are all 2hr capacity of the battery.

[0008] In addition to the above technical solutions, the above acidification method can also be applied to thin AGM separator lead-acid batteries.

[0009] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention subjects the semi-finished battery to a deep low-temperature treatment, so that the internal materials of the battery are already at a relatively low temperature before acid addition, significantly reducing the initial temperature inside the battery, effectively reducing the heat generated by the chemical reaction during the subsequent acid addition process, reducing the dissolution and migration of lead sulfate caused by high temperature, and providing favorable conditions for preventing dendrite short circuits. On this basis, the colloidal electrolyte is also subjected to a freezing treatment, so that the colloidal electrolyte can more stably control the reaction temperature during the acid addition process, reduce heat release, and thus reduce the risk of dendrite formation. At the same time, the silica gel in the colloidal electrolyte helps to form a more complex pore structure in the separator, further physically blocking the growth of dendrites. Multiple vacuum pumping and pressurized injection are then used to improve the uniformity of the distribution of the colloidal electrolyte inside the battery, reducing the risk of short circuits caused by local high temperature or electrolyte concentration differences. Dendrite growth, while evenly distributed colloidal electrolyte also helps to improve the overall performance of the battery. On this basis, the battery is quickly cooled to effectively control the internal temperature of the battery, prevent the rapid growth of dendrites in the critical window period, and improve the safety and service life of the battery. The use of a staged formation process helps to reduce the growth of dendrites caused by excessive current or high temperature during the formation process. The setting of the reverse charging stage can form a well-conductive lead interface at the contact section between the positive plate grid and the positive active material, greatly improving the internal resistance of the plate in the initial stage of formation, avoiding the problem of deposited lead sulfate being converted into lead dendrites due to excessive internal resistance and excessive charging voltage, and the combination of multiple charging and discharging stages helps to form a more stable battery structure and performance. In addition, the refined formation process can also improve the cycle stability and energy density of the battery. 2. The present invention clearly states that the positive and negative plates, AGM separator paper, and battery casing of the semi-finished battery are produced by continuous casting and rolling. Combined with the subsequent acidification and formation steps, this method forms a targeted optimization of the battery production process using the continuous casting and rolling process, solving the problem of dendrite short circuits that are more likely to occur in batteries under this process, extending the battery life, and improving the reliability and safety of the product. On this basis, by optimizing the composition of the colloidal electrolyte, the chemical reactions within the battery can be more effectively controlled, the dissolution and migration of lead sulfate can be reduced, thereby reducing the possibility of dendrite formation and improving the performance and stability of the battery. Furthermore, by controlling the freezing temperature of the colloidal electrolyte, it helps to maintain the stability and activity of the colloidal electrolyte, reduce performance fluctuations caused by temperature changes during the acidification process, and improve the consistency and reliability of the battery. 3. By controlling the ambient temperature during colloidal electrolyte injection, the present invention can reduce the heat generated by the reaction between the electrolyte and internal battery materials, reduce the risk of dendrite growth caused by high temperatures, and improve the safety and service life of the battery. By precisely controlling the vacuuming and compressed air injection processes, the colloidal electrolyte is ensured to penetrate the battery more evenly, which is more conducive to heat exchange and avoids the accumulation of lead sulfate caused by localized excessive temperature or rapid decrease in electrolyte density within the battery. Furthermore, a rapid cooling process can quickly reduce the internal battery temperature, prevent dendrite growth caused by continued high temperature, and improve the safety and service life of the battery. 4. The present invention uses a formation process that is completed in a short time, which helps reduce battery performance fluctuations during the formation process. Precise temperature control helps maintain internal battery stability and reduces the risk of dendrite formation. Furthermore, a reverse current is applied at the initial stage of formation to form a dense lead layer at the interface between the positive grid and the active material, reducing the internal resistance of the plate by more than 50%. This effectively avoids the sudden surge in charging voltage caused by high internal resistance in traditional processes and prevents the abnormal reduction of lead sulfate to dendrites. Through 15 stages of programmed control of charge and discharge depth and rate, the uniform conversion of active materials is promoted, active material shedding is reduced, and the risk of dendrite formation is further reduced. 5. By controlling the temperature parameters during the formation process, this invention effectively reduces the loss of activity caused by organic matter (such as humic acid and lignin) in the active materials inside the battery dissolving into the electrolyte due to high temperatures. This significantly improves the low-temperature performance of the battery, allowing the battery to maintain performance above 75% even at -18°C, meeting the high low-temperature performance requirements of batteries in cold regions. 6. The acidification process of the present invention effectively solves the problem that thin AGM separator lead-acid batteries are more prone to dendrite short circuits after filling with electrolyte. It is particularly suitable for plates produced by continuous casting and rolling production processes, meeting the needs of modern battery manufacturers for efficient and high-quality production. DETAILED DESCRIPTION

[0010] The following examples are used to further illustrate the present invention and are not intended to limit its application (all percentages below are by weight). Example

[0011] This embodiment provides an acidification method for preventing dendrite short circuit, and the specific steps are as follows: first, positive and negative plates, AGM separator paper, and battery casing are prepared into semi-finished batteries by continuous casting and rolling production; second, the semi-finished batteries are cooled at -8 to -12°C for 1 to 2 days; third, a colloidal electrolyte prepared by 32.9 to 33.1% sulfuric acid, 0.3 to 0.7% colloidal dioxide, 1.0 to 2.0% sodium sulfate, 0.1 to 0.5% sodium silicate, 0.05 to 0.2% stannous sulfate, 0.01 to 0.05% sodium benzoate, and water is frozen to -5 to 5°C in a freezer; and then the semi-finished batteries are refrigerated at a vacuum pressure of -0.085 to -0.01 MPa. The interior is vacuumed for 10 to 20 seconds, and the frozen colloidal electrolyte is injected into the interior of the vacuum semi-finished battery through the acid adding equipment at an ambient temperature of ≤15°C. Subsequently, air with a pressure of 0.4 to 0.6 MPa is injected into the acid adding equipment for 4 to 10 seconds to force the colloidal electrolyte to be pressed into the interior of the semi-finished battery. The above acid adding process is repeated 3 to 5 times. Then, the battery injected with the colloidal electrolyte is placed in 2 to 10°C cooling water for 30 to 40 minutes to cool within 2 to 4 minutes after the injection of the colloidal electrolyte. Finally, the cooled battery is transferred to the charging water tank and formed according to the 15 stages in the following table. The formation must be completed within 2 hours of adding the colloidal electrolyte, and the temperature of the circulating cooling water during the formation must be controlled at 30 to 40°C.

[0012] The following are the 15 stages of the chemical process: ; Note: C in the table is the 2-hour capacity of the battery.

[0013] The above acidification method was applied to a thin AGM separator lead-acid battery. The performance of the thin AGM separator (separator thickness ≤ 1.1 mm) 12V 20Ah lead-acid battery was tested at room temperature. The performance results are shown in the following table.

[0014] Comparative Example: This comparative example adopts a conventional acid addition and formation method. Compared with the embodiment, this comparative example does not perform deep low-temperature treatment on the semi-finished battery, nor does it adopt a method of acid addition with multiple vacuum negative pressure. A small current reverse charging stage is not provided at the initial stage of the formation process. The conventional acid addition and formation method of this comparative example is then applied to a thin AGM separator lead-acid battery. The performance of this thin AGM separator (separator thickness ≤ 1.1 mm) 12V20Ah lead-acid battery is tested at room temperature. The performance results are shown in the following table.

[0015] The following is a comparison table of the performance of the 12V20Ah batteries of the embodiment and the comparative example tested at room temperature: ; Note: C2 in the table refers to the 2-hour rate capacity of the battery; As can be seen from the above table, the performance of the battery produced by the acid formation method of the present invention is better than that of the battery produced by the conventional acid formation method, and the acid formation process of the present invention effectively solves the problem that thin AGM separator lead-acid batteries are more prone to dendrite short circuits after filling with electrolyte, reducing the dendrite penetration ratio to 0%, and completely solving the dendrite hidden danger of continuous casting and rolling plates, so that the performance of the prepared battery can be maintained at more than 75% in a low temperature environment of -18°C, meeting the stringent environmental requirements of power batteries.

Claims

1. A method for acidification to prevent dendrite short circuit, characterized in that: The specific steps are as follows: S1. Cool the semi-finished battery at -8 to -12°C for 1 to 2 days; S2. freezing a colloidal electrolyte prepared from sulfuric acid, colloidal dioxide, sodium sulfate, sodium silicate, stannous sulfate, sodium benzoate and water in a freezer; S3. The frozen colloidal electrolyte is acidified 3 to 5 times by an acid-adding device by first vacuuming and then injecting compressed air into the semi-finished battery; S4. The battery injected with the colloidal electrolyte is quickly placed in cooling water for cooling; S5. The cooled battery is transferred to a charging tank and formed in 15 stages of 1 reverse charge, 9 charges and 5 discharges.

2. The method for preventing dendrite short circuit according to claim 1, characterized in that: In S1, the semi-finished batteries including positive and negative plates, AGM separator paper, and battery casing are prepared by continuous casting and rolling production methods.

3. The acidification method for preventing dendrite short circuit according to claim 1, characterized in that: In S2, the colloidal electrolyte is composed of 32.9-33.1% sulfuric acid, 0.3-0.7% colloidal dioxide, 1.0-2.0% sodium sulfate, 0.1-0.5% sodium silicate, 0.05-0.2% stannous sulfate, 0.01-0.05% sodium benzoate, and the balance is water.

4. The acidification method for preventing dendrite short circuit according to claim 1, characterized in that: In S2, the colloidal electrolyte needs to be frozen to -5 to 5°C.

5. The acidification method for preventing dendrite short circuit according to claim 1, characterized in that: In S3, the injection of the colloidal electrolyte must be carried out at an ambient temperature of ≤15°C.

6. The acidification formation method for preventing dendrite short circuit according to claim 1, characterized in that: In S3, vacuuming is to evacuate the interior of the semi-finished battery at a vacuum pressure of -0.085 to -0.01 MPa for 10 to 20 seconds and then inject the colloidal electrolyte; injecting compressed air is to inject air at a pressure of 0.4 to 0.6 MPa into the acid adding equipment for 4 to 10 seconds to force the colloidal electrolyte to be pressed into the interior of the semi-finished battery.

7. The acidification method for preventing dendrite short circuit according to claim 1, characterized in that: In S4, the battery needs to be placed in cooling water within 2 to 4 minutes after the colloidal electrolyte is injected. The temperature of the cooling water is controlled at 2 to 10°C, and the cooling time is 30 to 40 minutes.

8. The acidification formation method for preventing dendrite short circuit according to claim 1, characterized in that: In S5, the formation must be completed within 2 hours of adding the colloidal electrolyte, and the temperature of the circulating cooling water during the formation must be controlled at 30-40°C.

9. The acidification formation method for preventing dendrite short circuit according to claim 1, characterized in that: In S5, the 15 formation stages are as follows: the first stage adopts the reverse charging mode for a control time of 0.5 h and a control current of 0.05 C; the second stage adopts the charging mode for a control time of 1 h and a control current of 0.1 C; the third stage adopts the charging mode for a control time of 1 h and a control current of 0.2 C; the fourth stage adopts the charging mode for a control time of 8 h and a control current of 0.5 C; the fifth stage adopts the discharging mode for a control time of 0.5 h and a control current of 0.5 C; the sixth stage adopts the charging mode for a control time of 4 h and a control current of 0.5 C; the seventh stage adopts the discharging mode for a control time of 0.5 h and a control current of 0.5 C; the eighth stage adopts the charging mode for a control time of 4 h and a control current of 0. 5C; the ninth stage adopts the discharge mode to control the time for 1h and the control current for 0.5C; the tenth stage adopts the charge mode to control the time for 4h and the control current for 0.5C; the eleventh stage adopts the discharge mode to control the time for 1.5h and the control current for 0.5C; the twelfth stage adopts the charge mode to control the time for 4h and the control current for 0.5C; the thirteenth stage adopts the discharge mode to control the time for 2h and the control current for 0.5C, and discharges to an average of 1.75V / cell; the fourteenth stage adopts the charge mode to control the time for 4h and the control current for 0.5C; the fourteenth stage adopts the charge mode to control the time for 3h and the control current for 0.04C, and acid is extracted after charging for 2h; where C is the 2hr capacity of the battery.

10. Use of the acidification formation method according to any one of claims 1 to 9 in a thin AGM separator lead-acid battery.