Efb start-stop lead-acid battery pole group welding alloy and preparation method and application thereof

Abstract

The present application relates to the technical field of lead-acid battery, and discloses an EFB start-stop lead-acid battery pole group welding alloy, which comprises the following components in percentage by mass: tin 1% to 1.79%, lead 98.21% to 99%, and impurities less than or equal to 0.2745%. The present application adds 1% to 1.79% of tin element in the EFB start-stop lead-acid battery pole group welding alloy, so that the tin element in the welding alloy can be well melted into one body with the pole group lug lead-calcium alloy and cannot form intercrystalline inclusions. In the process of battery charging and discharging cycle, the bus bar exposed to air cannot produce corrosion and fracture phenomenon, thereby prolonging the service life of the battery. The present application also discloses a preparation method of the EFB start-stop lead-acid battery pole group welding alloy.

Description

Technical Field

[0001] This invention belongs to the field of lead-acid battery technology, specifically relating to the EFB start-stop lead-acid battery electrode group welding alloy, its preparation method and application. Background Technology

[0002] EFB start-stop batteries are a type of battery that combines high starting performance with deep cycle capability, meaning they need to achieve both. They must have instantaneous high-current discharge performance and long-term, repeated deep discharge cycle performance. As a deep-cycle battery, its grid alloy is made of lead-calcium alloy, and the electrode group welding alloy is made of lead-antimony alloy. The advantages of lead-antimony alloy are its high hardness and strong vibration resistance. However, lead-antimony alloy has certain drawbacks. In the later stages of use, the electrolyte level in the EFB start-stop battery gradually decreases, exposing the busbar to the air. During deep discharge cycles, this can cause corrosion and cracking at the interface between the negative electrode group lugs and the busbar, prematurely ending the battery's lifespan. Furthermore, antimony, a strategic material in lead-antimony alloy, has seen its price rise significantly year by year, resulting in a substantial increase in the manufacturing cost of EFB batteries.

[0003] Currently, the electrode welding alloys for EFB start-stop lead-acid batteries on the market are all lead-antimony alloys (antimony 2.0%-3.5%, arsenic 0.15%-0.3%, tin 0.2%-0.5%, copper 0.05%-0.1%). To prevent corrosion and fracture at the contact interface between the negative electrode lugs and the busbar, most manufacturers in the industry increase the thickness of the negative electrode lugs and add a tinning process to the lugs during welding. This prevents lug corrosion and fracture, but this method suffers from uneven tinning and some corrosion. Furthermore, lead-antimony alloys are too expensive. Therefore, it is necessary to develop new alloys to solve the problems of corrosion and fracture at the contact interface between the negative electrode lugs and the busbar, as well as the high price of lead-antimony alloys. Summary of the Invention

[0004] To address the problems of corrosion and fracture of the negative electrode lugs and the high cost of purchasing lead-antimony alloys in existing EFB start-stop lead-acid batteries, which result in short battery life, this invention provides an EFB start-stop lead-acid battery electrode group welding alloy. This alloy can reduce the failure rate of negative electrode lug corrosion and fracture during battery use, improve the corrosion resistance of the positive and negative electrode lugs, and reduce the cost of electrode group welding alloys.

[0005] According to a first aspect of the invention, an EFB start-stop lead-acid battery electrode group welding alloy is provided, comprising the following components by mass percentage: 1%-1.79% tin, 98.21%-99% lead, and impurities ≤0.2745%.

[0006] The tin content in the EFB start-stop lead-acid battery electrode group welding alloy of the present invention is 1%-1.79%, and the impurity content is ≤0.2745%. Under the condition of high impurity content and low tin content, the material obtained after welding the alloy has good corrosion resistance.

[0007] In some embodiments, the impurities include arsenic, calcium, iron, copper, nickel, bismuth, aluminum, sulfur, zinc, cadmium, tellurium, silver, mercury, and antimony.

[0008] In some embodiments, the EFB start-stop lead-acid battery electrode group welding alloy contains impurities comprising the following components by mass percentage: arsenic ≤ 0.009%, calcium ≤ 0.003%, iron ≤ 0.0015%, copper ≤ 0.0015%, nickel ≤ 0.0015%, bismuth ≤ 0.05%, aluminum ≤ 0.002%, sulfur ≤ 0.002%, zinc ≤ 0.0015%, cadmium ≤ 0.002%, tellurium ≤ 0.002%, silver ≤ 0.1%, mercury ≤ 0.0005%, and antimony ≤ 0.1%.

[0009] In some embodiments, the EFB start-stop lead-acid battery electrode group welding alloy contains impurities comprising the following components by mass percentage: arsenic 0.008%-0.009%, calcium 0.0015%-0.003%, iron 0.0001%-0.0002%, copper 0.003%-0.004%, nickel 0.00009%-0.0002%, bismuth 0.001%-0.002%, and aluminum. 0.000009%-0.00001%, sulfur 0.0003%-0.0005%, zinc 0.000025%-0.00004%, cadmium 0.00005%-0.00006%, tellurium 0.0002%-0.0003%, silver 0.0001%-0.0002%, mercury 0.0001%-0.0002%, and antimony 0.09%-0.1%.

[0010] According to a second aspect of the present invention, a method for preparing an EFB start-stop lead-acid battery electrode group welding alloy is provided, comprising the following steps: A tin master alloy is prepared by mixing refined lead and tin in a 1:1 mass ratio. The tin master alloy is then added to a lead-tin pot at 450-490℃, stirred, and cooled to obtain the final product.

[0011] In some implementations, the tin is 99.5%-100% tin by mass.

[0012] In some implementations, refined lead is electrolytic lead. Electrolytic lead is a product obtained by electrolyzing crude lead and depositing it at the cathode.

[0013] According to a third aspect of the present invention, the application of an EFB start-stop lead-acid battery electrode group welding alloy in the manufacture of an EFB start-stop lead-acid battery is provided. Specifically, the EFB start-stop lead-acid battery electrode group welding alloy is used as a welding alloy to manufacture a busbar connecting at least two electrode group lugs.

[0014] In some implementations, two adjacent busbars are connected by through-wall welding.

[0015] The EFB start-stop lead-acid battery electrode group welding alloy of the present invention has good corrosion resistance. When applied to EFB start-stop lead-acid batteries, the prepared busbar is easy to weld and is not prone to cracking.

[0016] The beneficial effects of this invention are: (1) Adding 1%-1.79% tin to the alloy results in a lower melting point and better fluidity of the welding alloy. It is easy to melt and fill the gaps between the poles during welding, ensuring a strong weld. Moreover, the tin can be well integrated with the lead-calcium alloy of the pole lugs, without forming intergranular interlayers.

[0017] (2) Lead-tin alloy has good corrosion resistance in electrolyte and can resist the erosion of sulfuric acid electrolyte. In particular, it has good corrosion resistance at the interface between the negative electrode lug and the busbar of the deep-cycle EFB start-stop battery. It avoids the corrosion problem caused by the contact between the lead-antimony alloy used for busbar welding and the lead-calcium alloy of the lug. During the battery charge-discharge cycle, the busbar will not corrode or break when exposed to air, thus extending the battery service life.

[0018] (3) The present invention develops an EFB start-stop lead-acid battery electrode group welding alloy. When it is used to weld the electrode group lugs of the EFB start-stop battery, the electrode group welding alloy material cost can be reduced. Compared with lead-antimony alloy, the raw material procurement price can be reduced by 8%-15%.

[0019] (4) The EFB start-stop lead-acid battery electrode group welding alloy of the present invention produces less harmful gas during the welding process, is easy to achieve large-scale production, and helps to reduce environmental pollution. Both lead and tin can be recycled materials, which meets the requirements of sustainable development. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view of the positive electrode busbar of the present invention; Figure 2 This is a cross-sectional view of the negative electrode busbar of the present invention; Figure 3 This is a cross-sectional view of the through-wall welding of the present invention; Figure 4 Image of the test sample; Figure 5 Images of the test sample after dissection and acid removal; Figure 6The polar groups after dissection of the test sample; Figure 7 The results are from a 50% DOD cycle discharge test of a lead-acid battery. Figure 8 The electrode group of a lead-acid battery after failure in a 50% DOD cycle discharge test; Figure 9 This is a diagram of the positive electrode plate of a lead-acid battery after it failed a 50% DOD cycle discharge test. Figure 10 This refers to the positive and negative busbars of a lead-acid battery after it fails the 50% DOD cycle discharge test. Figure 11 The results are from a 17.5% DOD cycle discharge test of a lead-acid battery. Figure 12 The electrode group of the lead-acid battery after failure in the 17.5% DOD cycle discharge test; Figure 13 This is the positive electrode plate of a lead-acid battery after it failed a 17.5% DOD cycle discharge test. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings, but the embodiments of the present invention are not limited thereto. The raw materials and reagents involved in the following embodiments are all commercially available.

[0022] Example 1 This embodiment provides a welding alloy for EFB start-stop lead-acid battery electrode groups, including the following steps: First, refined lead and tin (tin content ≥99.5%) are mixed in a 1:1 ratio to prepare a 50% tin master alloy. Then, the 50% tin master alloy is added to a lead-tin pot at 450-490℃, stirred evenly, and then cast into ingots for cooling to obtain the lead-tin alloy. Testing shows that the lead-tin alloy contains 1% tin and no less than 98.21% lead.

[0023] Example 2 This embodiment provides a welding alloy for EFB start-stop lead-acid battery electrode groups, including the following steps: First, mix refined lead and tin (tin content ≥99.5%) in a 1:1 ratio to prepare a 50% tin master alloy; then add the 50% tin master alloy to a lead-tin pot at 450-490℃, stir evenly, and then remove the pot to cast ingots and cool to obtain a lead-tin alloy.

[0024] The EFB start-stop lead-acid battery electrode group welding alloy from Example 2 was melted in a lead furnace and then sampled and tested. Three samples were taken, and the average of the three test results was calculated. The elements and their contents in the lead-tin alloy are shown in Table 1. As shown in Table 1, the average tin content in the lead-tin alloy is 1.11813%, and the average lead content is 98.7666%.

[0025] Table 1. Elements and their contents in the electrode group welding alloy of EFB start-stop lead-acid batteries.

[0026] Application Example 1 This application example demonstrates the use of EFB start-stop lead-acid battery electrode group welding alloy in electrode group preparation, including the following steps: (1) Setting of casting and welding process parameters: The temperature of lead pot, lead pipe and lead valve is 450-490℃; the temperature of casting and welding mold is 180-210℃; the EFB start-stop lead-acid battery electrode group welding alloy of Example 2 is molten lead liquid in lead pot, and the molten lead liquid is transported to casting and welding mold through lead pipe and lead valve. (2) After setting the casting and welding process parameters, run the equipment. First, put the electrode group with the partition plate in the fixture of the casting and welding machine. Clean the positive and negative electrode plates to remove the residual paste and oxides on the surface of the plates. Then, apply flux to the plates. The depth of the flux covering the plates should be greater than 5mm. (3) Insert the upper part of the pole group ear 2-2.5mm into the molten lead liquid, and melt the upper part of the pole group ear with the busbar to form a mold, cool and demold.

[0027] It should be noted that both the positive electrode tab and the negative electrode tab are lead-calcium alloys. The lead-calcium alloy used for the positive electrode tab has a calcium content of 0.075%-0.085% and a tin content of 1.25%-1.35%; the lead-calcium alloy used for the negative electrode tab has a calcium content of 0.09%-0.1% and a tin content of 0.1%-0.5%.

[0028] See the cross-sectional diagram of the positive busbar. Figure 1 See the cross-sectional diagram of the negative busbar. Figure 2 It can be seen that both the positive and negative electrode lugs are completely fused with the busbar, and the fusion effect between the positive and negative lugs and the busbar is good. The two busbars are connected by through-wall welding, as shown in the cross-sectional view below. Figure 3 As shown in the through-wall welding, by Figure 3 It can be seen that after adjacent positive and negative busbars are connected by through-wall welding, the alloy has no obvious pores or hard cores. This indicates that when the EFB start-stop lead-acid battery electrode group welding alloy is used for welding, the temperature of the casting mold used in the process is appropriate, the alloy components are fully melted, and no segregation occurs. The dense and non-porous structure of the welded product can more effectively resist electrolyte corrosion and extend its service life. The above results also show that when the tin content of the EFB start-stop lead-acid battery electrode group welding alloy is selected as 1%-1.79%, the welded busbar does not produce cracks, and the casting and through-wall welding quality does not have a negative impact.

[0029] Battery vibration resistance test The welded electrode groups were assembled into a lead-acid battery, and then acid was added to obtain a test sample (see...). Figure 4 ).

[0030] According to GB / T5008.1-2023.5.11 standard, the battery was tested under Class A (3G ≥ 2 hours) for 24 hours of vibration. Then, it was tested according to the vibration-resistant battery standard of 5G ≥ 8 hours for 100 hours of vibration, for a total vibration time of 124 hours. Multiple tests were performed on the battery, and the results are shown in Table 2. Table 2 shows that after 24 hours of vibration at 3G, followed by five rounds of vibration at 5G (20 hours each), the battery remained intact and showed no abnormalities; the voltage test results all met the inspection standards.

[0031] Table 2 Test Items and Results

[0032] Dissect the sample and pour out the acid, such as Figure 5 and Figure 6 As shown, it is clearly observable that the busbar, through-wall weld, and terminals are undamaged. This demonstrates that the welding alloy of the EFB start-stop lead-acid battery electrode group of the present invention can resist the corrosion of sulfuric acid electrolyte, especially the corrosion resistance of the interface between the negative electrode lug and the busbar in deep-cycle EFB start-stop batteries. During battery charging and discharging, the busbar exposed to air will not experience corrosion or fracture. The battery exhibits good mechanical integrity, electrical safety, and reliability under vibration conditions.

[0033] Corrosion resistance test According to the test methods of GB / T43346-2023 standard, the number of DOD (Discharge Over Time) cycles of the welded electrode assembly into a lead-acid battery is tested to evaluate the corrosion resistance of the busbar. In GB / T43346-2023 standard, the corrosion resistance of the busbar is determined by a 50% DOD cycle count ≥ 120 cycles and a 17.5% DOD cycle count ≥ 9 cells.

[0034] 50% DOD cycle discharge test results are as follows Figure 7 As shown, from Figure 7 It can be seen that the lead-acid battery prepared from the EFB start-stop lead-acid battery electrode group welding alloy prepared in Example 2 has an actual 50% DOD of 211 cycles, which is far higher than the standard 120 cycles. Dissection of the battery reveals its busbar and positive electrode plate. Figure 8-10 It can be seen that there are no cracks or obvious corrosion on the positive and negative busbars, but the active material of the positive plate of the battery has fallen off. This indicates that the failure mode of the lead-acid battery is caused by the softening and falling off of the positive active material.

[0035] The results of the 17.5% DOD cycle discharge test are as follows: Figure 11 As shown, from Figure 11It can be seen that the lead-acid battery prepared from the EFB start-stop lead-acid battery electrode group welding alloy prepared in Example 2 has 16 cells with a 17.5% DOD cycle discharge capacity, which is much higher than 9 cells. Next, the battery was dissected, and its electrode group and the positive electrode plate were observed... Figure 12 and Figure 13 .from Figure 12 and Figure 13 It can be seen that after the lead-acid battery underwent a 17.5% DOD cycle discharge test until discharge failure, no cracks or obvious corrosion were observed in its positive and negative busbars, but the active material of the positive plate of the battery fell off. This indicates that the failure mode of the lead-acid battery was caused by the softening and falling off of the positive active material.

[0036] The above results demonstrate that the busbar prepared by the EFB start-stop lead-acid battery electrode group welding alloy of the present invention has corrosion resistance.

[0037] In practical use, lead-antimony alloy batteries often fail due to corrosion and fracture at the interface between the negative electrode lug and the busbar. The EFB start-stop lead-acid battery electrode group welding alloy of this invention exhibits good corrosion resistance in electrolytes, resisting the erosion of sulfuric acid electrolytes. It is particularly effective against corrosion at the interface between the negative electrode lug and the busbar in deep-cycle EFB start-stop batteries, preventing corrosion problems caused by the lead-antimony alloy used for busbar welding contacting the lead-calcium alloy of the lug. During battery charge-discharge cycles, the busbar, exposed to air, will not experience corrosion and fracture. Therefore, in practical applications, batteries prepared using the EFB start-stop lead-acid battery electrode group welding alloy have a 10-20% longer lifespan compared to existing lead-antimony alloy batteries.

[0038] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. An EFB start-stop lead-acid battery electrode group welding alloy, characterized in that, It includes the following components by weight percentage: tin 1%-1.79%, lead 98.21%-99%, and impurities ≤0.2745%.

2. The EFB start-stop lead-acid battery electrode group welding alloy according to claim 1, characterized in that, The impurities are selected from at least one of arsenic, calcium, iron, copper, nickel, bismuth, aluminum, sulfur, zinc, cadmium, tellurium, silver, mercury and antimony.

3. The EFB start-stop lead-acid battery electrode group welding alloy according to claim 2, characterized in that, Impurities include the following components by mass percentage: arsenic ≤ 0.009%, calcium ≤ 0.003%, iron ≤ 0.0015%, copper ≤ 0.0015%, nickel ≤ 0.0015%, bismuth ≤ 0.05%, aluminum ≤ 0.002%, sulfur ≤ 0.002%, zinc ≤ 0.0015%, cadmium ≤ 0.002%, tellurium ≤ 0.002%, silver ≤ 0.1%, mercury ≤ 0.0005%, and antimony ≤ 0.1%.

4. The method for preparing the EFB start-stop lead-acid battery electrode group welding alloy according to any one of claims 1 to 3, characterized in that, Includes the following steps: A tin master alloy is prepared by mixing refined lead and tin in a 1:1 mass ratio. The tin master alloy is then added to a lead-tin pot at 450-490℃, stirred, and cooled to obtain the final product.

5. The EFB start-stop lead-acid battery electrode group welding alloy according to claim 4, characterized in that, The tin is 99.5%-100% by mass.

6. The application of the EFB start-stop lead-acid battery electrode group welding alloy according to any one of claims 1 to 3 in the preparation of EFB start-stop lead-acid batteries, characterized in that, The EFB start-stop lead-acid battery electrode group welding alloy is used to prepare a busbar connecting at least two electrode group lugs.

7. The application according to claim 6, characterized in that, The two adjacent busbars are connected by through-wall welding.

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