Acid spraying treatment process of high-capacity double-punching net pole plate

Abstract

The invention discloses an acid spraying treatment process of a high-capacity double-punching net pole plate. Through an innovative acid spraying treatment process, the pretreatment of the pole plate before assembly is changed from traditional pickling to controllable spraying-purging-standing circulation, and the colloid electrolyte with a specific formula is adopted, so that the acid adding reaction heat is released in advance from the source. A series of problems (such as sodium lignosulfonate precipitation and partition plate sintering) caused by high temperature are directly solved, and the 3 hr 100% DOD cycle life of the battery is remarkably prolonged to 460-550 times from original 320-350 times. Meanwhile, the process reduces the dependence on rear-end complex cooling facilities (such as a semi-finished product refrigeration house and cold acid equipment), simplifies the production control, reduces the equipment investment cost and the operation energy consumption, effectively improves the integrity of the polar plate film-coated paper, reduces the breakage and lead plaster exposure in the wrapping process, and comprehensively improves the product quality, the consistency and the production efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of punched grid plate preparation, and particularly relates to a pickling treatment process for high-capacity double-punched grid plates. BACKGROUND

[0002] As an important electrochemical energy storage device, the performance and service life of a lead-acid battery largely depend on the manufacturing process of the grid plate. In recent years, high-capacity double-punched grid plates have been widely used due to their excellent performance. However, this type of grid plate has exposed a significant technical problem in the acid adding process of battery manufacturing: the internal temperature of the grid group rises sharply after acid addition. This heating phenomenon is not an isolated problem, as it can trigger a series of chain reactions, forming a technical bottleneck that restricts the performance improvement of the product.

[0003] Firstly, the high-temperature environment will have an adverse effect on the active material of the grid plate. Specifically, excessively high temperature will cause the key auxiliary material in the negative plate, sodium lignosulfonate, to dissolve and precipitate, which will directly damage the electrochemical performance of the negative electrode, ultimately resulting in a significant decrease in the capacity of the battery in a low-temperature environment. Secondly, sustained high temperature will impact the physical structure of the battery, possibly causing local sintering of the separator, which not only damages the microstructure of the separator, but also causes differences in performance between individual batteries within the battery pack, leading to poor product consistency and significantly shortening the cycle service life of the battery.

[0004] From the perspective of production process, the high-temperature state after acid addition forces the production process to introduce longer standing cooling time and requires precise control of the entire temperature rise curve, which directly leads to the extension of the charging formation process time after acid addition, severely restricting the production capacity improvement of the production line. At the same time, high temperature also affects the conversion process of the active material in the grid plate, especially the generation ratio of tetra-aluminum sulfate and tri-aluminum sulfate, which is one of the key factors determining the long-term cycle life of the battery. In addition, the acid content and saturation in the grid group are also difficult to control within the optimal range due to uneven temperature rise, further limiting the potential of the battery cycle life.

[0005] In the existing production technology, the main way to deal with the above problems is to directly assemble the battery after the grid plate is solidified and dried, and then implement strict temperature control before and after acid addition. This usually means that the temperature of the semi-finished battery needs to be lowered before acid addition, the injected acid solution needs to be cooled, and the battery needs to be placed in a temperature-controlled water tank for a long time after acid addition. This solution, which relies on forced cooling in the backend, can alleviate the problem to some extent, but it faces the challenges of difficult process parameter control and poor stability. More importantly, it requires the construction of a full set of cooling facilities such as a semi-finished battery cold storage, an acid solution cooling device, and a large-scale cooling water tank, which has high equipment investment cost, high energy consumption, and significantly increases production cost.

[0006] In the prior art document, the disclosure number CN103035884A discloses a pretreatment method of internalization with green plate. The technical solution is aimed at the traditional gravity cast plate, and the core is to soak the solidified and dried green plate in dilute sulfuric acid with a specific density range for a period of time, and then dry treatment. The purpose of this method is to form a lead sulfate layer in the plate in advance through pretreatment, so as to reduce the temperature rise during subsequent battery acid addition, and to create more favorable conditions for formation. However, the "acid immersion" process used in this technology is essentially different from the technical path of the present application. On the one hand, the processing object is the gravity cast plate with different structure; on the other hand, the acid immersion method has its limitations in processing efficiency, uniform distribution of reagents and adaptability to special plate structure.

[0007] Therefore, there is an urgent need in the art to develop an innovative pretreatment process that can effectively solve the problem of high-capacity double-punch net plate acid addition temperature rise from the source, and can simultaneously improve the comprehensive performance and production efficiency of the battery. SUMMARY

[0008] Based on the deficiencies in the prior art, the present application provides a high-capacity double-punch net plate acid spraying treatment process. The technical solution of the present application can effectively solve a series of problems caused by high temperature in the internal group of high-capacity double-punch net plate battery after acid addition in the prior art: including avoiding the dissolution and precipitation of sodium lignosulfonate, an auxiliary material for negative plate, due to high temperature, thereby improving the low-temperature capacity of the battery; preventing the sintering of the separator due to high temperature, thereby improving the consistency and cycle life of the battery; shortening the production time of acid charging and charging by pre-releasing reaction heat, improving production capacity; optimizing the ratio of tetraalkali sulfate lead and trialkali sulfate lead in the generated lead sulfate after acid addition, improving the cycle life of the product; and accurately controlling the acid content and saturation of the internal group, further improving the cycle life of the battery.

[0009] The specific technical solution of the present application is as follows: A high-capacity double-punch net plate acid spraying treatment process, comprising the following steps: Lay the solidified and dried double-punch net plate flat on the chain plate; Spray the upper and lower surfaces of the plate with gel electrolyte; Blow off the residual gel electrolyte on the surface of the plate with gas; Let the plate stand, so that the lead paste in the plate and the electrolyte undergo exothermic reaction; Repeat the steps of spraying gel electrolyte, blowing and standing at least once; Dry the treated plate.

[0010] As preferred, the steps of spraying the gel electrolyte, blowing and standing are repeated for 2 cycles. Through the two-cycle treatment, the lead paste of the plate can be subjected to acid absorption and exothermic reaction in stages and more fully, thereby releasing more heat before the battery is assembled, and significantly reducing the temperature rise during subsequent acid addition.

[0011] Further preferably, the gel electrolyte comprises the following components, with dilute sulfuric acid being 100%, the gel electrolyte being proportionally prepared: Dilute sulfuric acid, density at 25℃ being 1.10-1.25 g / ml; Gel mother liquor containing SiO2, the addition amount accounting for 0.4%-0.7% of the mass of the dilute sulfuric acid; Phosphoric acid, the addition amount accounting for 0.2%-0.6% of the mass of the dilute sulfuric acid; Sodium carboxymethyl cellulose, the addition amount accounting for 0.05%-0.1% of the mass of the dilute sulfuric acid.

[0012] Further, the gel mother liquor contains 15% of SiO2 in mass percentage.

[0013] The preparation method of the gel mother liquor is that pure water and fumed silica are mixed by stirring through a high-speed shearing machine; The specific preparation method is as follows: 1. 266.6 kg of pure water is added into the high-speed shearing machine; 2. 40 kg of fumed silica is extracted by the high-speed shearing machine under negative pressure; 3. After stirring for 8 min at a high speed (the rotating speed can be 5000 r / min), the mixture is put into a plastic glue bucket.

[0014] The volume percentage concentration of the phosphoric acid is 85%.

[0015] The main purpose of the gel electrolyte treatment of the high-capacity double-punch mesh plate is to release part of the heat of the plate before the battery is assembled, thereby reducing the heat generated during the acid addition process.

[0016] The mechanism of the gel electrolyte with the specific ratio is that the dilute sulfuric acid reacts with the lead paste to generate lead sulfate and release heat, the density range of the dilute sulfuric acid, the density being too high will cause the generated lead sulfate layer to be non-uniform, and the exothermic temperature to be non-uniform; the density being too low will cause the generated lead sulfate layer to be not thick enough, and the released heat to be not enough; The silica in the gel electrolyte prevents the acid liquid from being stratified, adsorbs the acid liquid to increase the acid amount, and improves the cycle life of the battery; The phosphoric acid helps the silica powder to adhere to the film paper of the punched mesh plate, avoiding falling off; The sodium carboxymethyl cellulose makes the silica uniformly distributed in the electrolyte, avoiding stratification.

[0017] The cooperation of the ratio ensures the uniform generation of lead sulfate layer and the effective and uniform release of heat.

[0018] Preferably, the chain plate is made of PVC in the step of spraying the gel electrolyte and made of stainless steel in the drying step. The material selection takes into account the requirements of corrosion resistance and high temperature resistance.

[0019] Since the high-capacity double-punch mesh plate has no lug, the punch mesh plate can only be laid flat on the PVC chain plate and placed on the PVC chain plate by suction cups. Then the punch mesh plate is sprayed with gel electrolyte from top to bottom.

[0020] Further, the conveying speed of the chain plate is 8 m / h, which matches the process requirements of controlling the spraying, standing and drying time.

[0021] Preferably, the drying step is carried out at 110-170°C, which can effectively remove the moisture of the plate and make the plate weight gain reach the process standard, providing protection for subsequent mass production.

[0022] Preferably, the gas blowing step uses high-pressure gas flow to ensure uniform distribution of the lead sulfate layer on the top and bottom surfaces of the plate, avoiding the problem of inconsistent thickness of the lead sulfate on the same surface or both surfaces due to uneven residual electrolyte on the surface of the plate.

[0023] Preferably, the standing time of the standing step is adjusted according to the needs of the heat release reaction of the plate to release the internal heat of the plate.

[0024] Advantages of the present application: The present application uses an innovative acid spraying process to replace the traditional acid immersion with a controllable spraying-scrubbing-standing cycle before the plate is assembled, and uses a gel electrolyte with a specific formula to release the heat of the acid addition reaction from the source. This not only directly solves a series of problems caused by high temperature (such as the precipitation of sodium lignosulfonate and the sintering of the separator), but also significantly improves the 3hr 100% DOD cycle life of the battery from the original 320-350 times to 460-550 times. At the same time, the process reduces the dependence on complex cooling facilities (such as semi-finished product cold storage, cold acid equipment, cooling water tank equipment, and cooling water cooling equipment) at the back end, simplifies production control, reduces equipment investment cost and operating energy consumption, and effectively improves the integrity of the plate coating paper, reduces the rupture and lead paste exposure during the wrapping process, and improves the product quality, consistency and production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The figure shows the cycle life comparison of the double-punch plate battery of the present application embodiment 1, embodiment 4 and the existing process. DETAILED DESCRIPTION

[0026] This invention provides an acid spraying process for high-capacity dual-strike grid plates, comprising the following steps: The cured and dried double-grid electrode plate is laid flat on the chain plate; Spray colloidal electrolyte onto the upper and lower surfaces of the electrode plates; The residual electrolyte on the surface of the electrode plate is removed by blowing away the gas. The electrode plate is left to stand, allowing the lead paste in the electrode plate to undergo an exothermic reaction with the electrolyte; Repeat the steps of spraying colloidal electrolyte, blowing air, and letting stand at least once; The treated plates are then dried.

[0027] Preferably, the steps of spraying the gel electrolyte, blowing air, and letting it stand are repeated twice.

[0028] Further preferably, the colloidal electrolyte comprises the following components, with dilute sulfuric acid as 100%, and the colloidal electrolyte is prepared in the following proportions: Dilute sulfuric acid has a density of 1.10-1.25 g / ml at 25°C. The colloidal mother liquor contains SiO2 and is added at a rate of 0.4%-0.7% of the mass of the dilute sulfuric acid. Phosphoric acid, added in an amount accounting for 0.2%-0.6% of the mass of the dilute sulfuric acid; Sodium carboxymethyl cellulose is added at a rate of 0.05%-0.1% of the mass of the dilute sulfuric acid.

[0029] Furthermore, the colloidal mother liquor contains 15% SiO2 by mass.

[0030] The colloidal mother liquor of this invention is self-made, prepared by mixing pure water and fumed silica using a high-speed shear mixer. The specific preparation method is as follows: 1. Add 266.6 kg of pure water to the high-speed shearing machine; 2. A high-speed shearing machine extracts 40 kg of fumed silica under negative pressure; 3. After high-speed shearing (speed can be 5000 rpm) and stirring for 8 minutes, put it into a plastic bucket.

[0031] The volume percentage concentration of the phosphoric acid is 85%.

[0032] Preferably, the chain plate is made of PVC in the spraying of the colloidal electrolyte step and of stainless steel in the drying step.

[0033] Because the high-capacity double-punched electrode plate has no hanging ears, the punched electrode plate can only be laid flat on the PVC chain plate, and then placed on the PVC chain plate by suction cup. After that, the punched electrode plate is sprayed with colloidal electrolyte from top to bottom.

[0034] Furthermore, the conveying speed of the chain plate is 8m / h.

[0035] Preferably, the drying step is carried out at 120-170°C.

[0036] Preferably, the gas purging step uses a high-pressure airflow to ensure that the lead sulfate layer on the upper and lower surfaces of the electrode is evenly distributed.

[0037] Preferably, the time of the settling step is adjusted according to the needs of the exothermic reaction of the electrode plate in order to release the heat inside the electrode plate.

[0038] The technical solution of the present invention will be specifically illustrated below through specific embodiments.

[0039] Example 1

[0040] The preparation method of the colloidal electrolyte of the present invention is as follows: 1. Add dilute sulfuric acid at 25℃ @ 1.13 g / ml, 1000 kg; 2. Add 5 kg of colloidal mother liquor containing 15% SiO2 by mass and stir for 3 min; 3. Add industrial-grade phosphoric acid, 3 kg in total; 4. Add sodium carboxymethyl cellulose, 0.75 kg, and continue stirring for 5 minutes.

[0041] This embodiment provides a method for acid spraying treatment of high-capacity dual-strike grid plates, including the following steps: (1) The punched plate is transported to the designated position, and is picked up by the suction cup and placed on the PVC chain plate. The upper and lower nozzles are aligned with the plate surface and the spraying time is 8 seconds. (2) The plate passes the high-pressure air nozzle (30kPa) position to blow off the colloidal electrolyte on the plate. The blowing time is 2s. (3) The electrode plate continues to move forward with the PVC chain plate, and the upper and lower nozzles are aligned with the electrode plate surface for 6 seconds. (4) The electrode plate passes the high-pressure air nozzle position to blow off the colloidal electrolyte on the electrode plate. The blowing time is 3s. (5) The electrode plate enters the drying kiln along with the stainless steel chain plate. The kiln temperature is 150-170℃ and the kiln speed is 8m / h.

[0042] Weight gain requirements for dual-electrode plates after drying with sprayed colloidal electrolyte: Weight gain range: 0.025-0.032 g / cm³ 2 .

[0043] Example 2

[0044] The preparation method of the colloidal electrolyte of the present invention is as follows: 1. Add dilute sulfuric acid at 25℃ @ 1.13 g / ml, 1000 kg; 2. Add 6 kg of colloidal mother liquor containing 15% SiO2 by mass and stir for 3 min; 3. Add 2 kg of industrial-grade phosphoric acid; 4. Add sodium carboxymethyl cellulose, 0.6 kg, and continue stirring for 5 minutes.

[0045] This embodiment provides a method for acid spraying treatment of high-capacity dual-strike grid plates, including the following steps: (1) The punched plate is transported to the designated position, and is picked up by the suction cup and placed on the PVC chain plate. The upper and lower nozzles are aligned with the plate surface and the spraying time is 7 seconds. (2) The plate passes the high-pressure air nozzle (30kPa) position to blow off the colloidal electrolyte on the plate. The blowing time is 3s. (3) The electrode plate continues to move forward with the PVC chain plate, and the upper and lower nozzles are aligned with the electrode plate surface for 7 seconds. (4) The plate passes the high-pressure air nozzle and the colloidal electrolyte on the plate is blown off. The blowing time is 4s. (5) The electrode plate enters the drying kiln along with the stainless steel chain plate. The kiln temperature is 130-150℃ and the kiln speed is 6m / h.

[0046] Weight gain requirements for dual-electrode plates after drying with sprayed colloidal electrolyte: Weight gain range: 0.025-0.032 g / cm³ 2 .

[0047] Example 3

[0048] The preparation method of the colloidal electrolyte of the present invention is as follows: 1. Add dilute sulfuric acid at 25℃ @ 1.13 g / ml, 1000 kg; 2. Add 7 kg of colloidal mother liquor containing 15% SiO2 by mass and stir for 3 min; 3. Add 4 kg of industrial-grade phosphoric acid; 4. Add sodium carboxymethyl cellulose, 0.85 kg, and continue stirring for 5 minutes.

[0049] This embodiment provides a method for acid spraying treatment of high-capacity dual-strike grid plates, including the following steps: (1) The punched plate is transported to the designated position, and is picked up by the suction cup and placed on the PVC chain plate. The upper and lower nozzles are aligned with the plate surface and the spraying time is 6 seconds. (2) The plate passes the high-pressure nozzle (30kPa) position to blow off the colloidal electrolyte on the plate. The blowing time is 4s. (3) The electrode plate continues to move forward with the PVC chain plate, and the upper and lower nozzles are aligned with the electrode plate surface for 8 seconds. (4) The electrode plate passes the high-pressure air nozzle position to blow off the colloidal electrolyte on the electrode plate. The blowing time is 5s. (5) The electrode plate enters the drying kiln along with the stainless steel chain plate. The kiln temperature is 120-140℃ and the kiln speed is 5m / h.

[0050] Weight gain requirements for dual-electrode plates after drying with sprayed colloidal electrolyte: Weight gain range: 0.025-0.032 g / cm³ 2 .

[0051] Example 4

[0052] The preparation method of the colloidal electrolyte of the present invention is as follows: 1. Add dilute sulfuric acid at 25℃ @ 1.13 g / ml, 1000 kg; 2. Add 4 kg of colloidal mother liquor containing 15% SiO2 by mass and stir for 3 min; 3. Add 5 kg of industrial-grade phosphoric acid; 4. Add sodium carboxymethyl cellulose, 0.95 kg, and continue stirring for 5 minutes.

[0053] This embodiment provides a method for acid spraying treatment of high-capacity dual-strike grid plates, including the following steps: (1) The punched mesh electrode plate is transported to the designated position, and is picked up by the suction cup and placed on the PVC chain plate. The upper and lower nozzles are aligned with the electrode plate surface and the spraying time is 5 seconds. (2) The plate passes the high-pressure air nozzle (30kPa) position to blow off the colloidal electrolyte on the plate. The blowing time is 3s. (3) The electrode plate continues to move forward with the PVC chain plate, and the upper and lower nozzles are aligned with the electrode plate surface for 6 seconds. (4) The electrode plate passes the high-pressure air nozzle position to blow off the colloidal electrolyte on the electrode plate. The blowing time is 6s. (5) The electrode plate enters the drying kiln along with the stainless steel chain plate. The kiln temperature is 110-130℃ and the kiln speed is 4m / h.

[0054] Weight gain requirements for dual-electrode plates after drying with sprayed colloidal electrolyte: Weight gain range: 0.025-0.032 g / cm³ 2 .

[0055] Comparative Example 1 1. After the assembly of the dual-plate semi-finished battery is completed, it is placed in a cooling warehouse and kept at an ambient temperature of 20°C for more than 20 hours. 2. Add acid to the semi-finished battery with dual-plate electrode. The amount of acid added should correspond to the corresponding model. The acid temperature should be ≤-7℃. 3. After adding acid, the battery flows into the cooling water tank, and the temperature of the circulating water in the tank is controlled to be ≤20℃; 4. The electrolyte used is a common electrolyte, consisting of pure water, anhydrous sodium sulfate, and silica sol. Preparation method: 1. Add 10 tons of pure water to the acid mixing tank; 2. Add 3.1 tons of concentrated sulfuric acid and continue for 10 minutes. After the acid solution cools, measure the acid density. 5. After the acid density meets the process parameter requirements, add 104.8 kg of anhydrous sodium sulfate. Measure the acid density after the anhydrous sodium sulfate has completely dissolved. 6. After the acid density meets the process parameter requirements, add 42.3 kg of silica sol, stir for 3 minutes, and then measure the acid density. The acid can only be used after the acid density meets the process parameter requirements.

[0056] Detection Example 1 3hr 100% DOD cycle count detection.

[0057] Examples 1 and 4, along with Comparative Example 1, were assembled into dual-charge plate batteries and subjected to cycle tests at 25°C. The cycle process is as follows: (1) Discharge: Discharge at a constant current of 33.3A to 10.5V / unit; (2) Charging: Charge at a current of 1.0I3 (33.3A) and a constant voltage of 14.8V / each for 6 hours; (3) Let stand for 0.5 hours; (4) (1) ~ (3) form one cycle, and the cycle is terminated when the discharge capacity is below 80% C3 for 10 consecutive cycles.

[0058] The results are as follows Figure 1 As shown, high-capacity dual-charge plate batteries produced by existing processes have short cycle life, with 320-350 cycles at 3 hours and 100% DOD. The high-capacity dual-charge plate batteries prepared by the acid spraying process of this invention can improve the cycle life to 460-550 cycles.

Claims

1. An acid spraying process for a high-capacity dual-strike grid plate, characterized in that, Includes the following steps: The cured and dried double-grid electrode plate is laid flat on the chain plate; Spray colloidal electrolyte onto the upper and lower surfaces of the electrode plates; The residual colloidal electrolyte on the surface of the electrode plate is removed by blowing with gas; The electrode plate is left to stand, allowing the lead paste in the electrode plate to undergo an exothermic reaction with the electrolyte; Repeat the steps of spraying colloidal electrolyte, blowing air, and letting stand at least once; The treated plates are then dried.

2. The acid spraying process for the high-capacity dual-strike grid plate according to claim 1, characterized in that, The steps of spraying the gel electrolyte, blowing air, and letting it stand are repeated twice.

3. The acid spraying process for the high-capacity dual-strike grid plate according to claim 1 or 2, characterized in that, The colloidal electrolyte comprises the following components: Dilute sulfuric acid has a density of 1.10-1.25 g / ml at 25°C. The colloidal mother liquor contains SiO2, and its addition amount accounts for 0.4%-0.7% of the mass of the dilute sulfuric acid. Phosphoric acid, added in an amount accounting for 0.2%-0.6% of the mass of the dilute sulfuric acid; Sodium carboxymethyl cellulose is added at a rate of 0.05%-0.1% of the mass of the dilute sulfuric acid.

4. The acid spraying process for the high-capacity dual-strike grid plate according to claim 3, characterized in that, The colloidal mother liquor contains 15% SiO2 by mass. The colloidal mother liquor is prepared by mixing pure water and fumed silica using a high-speed shear mixer. The volume percentage concentration of the phosphoric acid is 85%.

5. The acid spraying process for the high-capacity dual-strike grid plate according to claim 1, characterized in that, The chain plate is made of PVC in the spraying of the colloidal electrolyte and of stainless steel in the drying step.

6. The acid spraying process for the high-capacity dual-strike grid plate according to claim 1, characterized in that, The conveying speed of the chain plate is 8m / h.

7. The acid spraying process for the high-capacity dual-strike grid plate according to claim 1, characterized in that, The drying step is carried out at 110-170°C.

8. The acid spraying process for the high-capacity dual-strike grid plate according to claim 1, characterized in that, The gas purging step uses a high-pressure airflow to ensure that the lead sulfate layer on the upper and lower surfaces of the electrode is evenly distributed.

9. The acid spraying process for the high-capacity dual-strike grid plate according to claim 1, characterized in that, The settling time is adjusted according to the needs of the exothermic reaction of the electrode plate in order to release the heat inside the electrode plate.

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