A lead storage battery composite busbar and a manufacturing method thereof, lead storage battery

Abstract

The application discloses a lead storage battery composite busbar and a manufacturing method thereof and a lead storage battery. In the manufacturing method, first, a first bonding transition layer is formed on the surface of at least a welding area of each positive and negative electrode lug; then, the positive and negative electrode lugs are inserted into a casting and welding cavity of a primary casting and welding mold to cast and weld an inner core of the busbar and an inner core of the pole; then, a second bonding transition layer is formed on the surface of the inner core of the busbar and the inner core of the pole; finally, the inner core of the busbar and the inner core of the pole are inserted into a casting and welding cavity of a secondary casting and welding mold to cast and weld an outer cladding layer. The prepared composite busbar breaks through the metallurgical bonding difficulty of dissimilar metals: a metallurgical active transition layer system is constructed through double coating treatment, and reliable metallurgical bonding of dissimilar metals such as aluminum / lead and copper / lead is realized. Full dense cladding is realized: through twice casting and design of a space compensation structure, it is ensured that the lead alloy outer cladding layer is 360° full dense cladding to the high-conductivity metal inner core, and corrosion hidden dangers are eliminated.

Description

Technical Field

[0001] This invention belongs to the field of lead-acid battery technology, specifically relating to a lead-acid battery composite busbar and its manufacturing method, and a lead-acid battery. Background Technology

[0002] Lead-acid batteries generally consist of a battery case, which is divided into multiple individual cells. Each cell contains a group of electrodes, which includes alternating positive and negative plates. The positive plates have positive tabs, and the negative plates have negative tabs. Each electrode group has a positive bus and a negative bus connected in series with all the positive and negative tabs, respectively. Adjacent electrode groups are connected in series through the interconnection of the positive and negative busbars. The first and last positive and negative busbars are equipped with positive and negative terminals, respectively.

[0003] Busbars are key current collector components in lead-acid batteries that connect multiple plates in parallel. Their conductivity and the reliability of their connection with the tabs directly affect the battery's internal resistance, capacity, and lifespan. With the increasing demands on battery performance from power batteries, automotive start-stop systems, and energy storage devices, reducing busbar internal resistance and improving its current-carrying capacity have become key research areas in the industry.

[0004] Traditional busbars are made of lead alloy and are often manufactured using a one-time casting and welding process, which results in problems such as poor conductivity and insufficient corrosion resistance.

[0005] To address these issues, existing technologies have proposed composite structures using highly conductive metal cores. However, the integration of dissimilar metals, full dense coating, and integrated molding of the electrode post and busbar remain technical challenges to be solved.

[0006] For example, the invention application with publication number CN108630901A discloses a lead-clad copper bus, which is made by stamping copper sheets and then placing them into a mold to cast molten lead.

[0007] The invention application with publication number CN116365176A discloses a battery using a lead-plated aluminum alloy busbar. The busbar is made of lead-plated aluminum alloy material, that is, lead is plated on the surface of the aluminum alloy material.

[0008] However, the aforementioned existing technical solutions have problems such as low bonding strength between dissimilar metals, easy pinholes in the coating layer, and interface bottlenecks at the connection between the electrode and the busbar, which cannot meet the requirements of high-performance lead-acid batteries. Summary of the Invention

[0009] To address the technical challenges in existing lead-acid battery busbar technology, such as the difficulty in metallurgically bonding the highly conductive metal core to the lead alloy shell, the tendency for pinholes to expose the core in the coating layer, and the interface bottleneck at the connection between the terminal and the busbar, this invention aims to provide a manufacturing method for a composite busbar for lead-acid batteries that can completely solve these problems. The busbar manufactured using this method exhibits excellent conductivity, mechanical strength, and corrosion resistance.

[0010] This invention first provides a method for manufacturing a composite busbar for a lead-acid battery. The lead-acid battery includes an electrode group, which includes alternately stacked positive and negative electrode plates. The positive electrode plates are provided with positive tabs, and the negative electrode plates are provided with negative tabs. In the same electrode group, the positive tabs are arranged in a row, and the negative tabs are arranged in a row. The manufacturing method includes the following steps: (1) Immerse the ends of the positive and negative tabs on the electrode group used for welding the bus into the first molten metal bath, so that at least the surface of the welding area of ​​each positive and negative tab forms a first bonding transition layer. (2) The first molten metal is poured into the casting cavity of the primary casting mold, and the positive and negative electrodes are inserted into the casting cavity of the primary casting mold to form the inner core of the busbar and the inner core of the electrode post. (3) Immerse the inner core of the busbar and the inner core of the pole on the pole group obtained in step (2) into the second molten metal bath to form a second bonding transition layer on the surface of the inner core of the busbar and the inner core of the pole. (4) The second molten metal is poured into the casting cavity of the secondary casting mold, and the inner core of the busbar and the inner core of the pole extend into the casting cavity of the secondary casting mold to form an outer cladding layer. In this process, the first metal used in the first molten metal has better electrical conductivity than the second metal used in the second molten metal, and the second metal is lead or a lead alloy. The first molten metal bath and the second molten metal bath are independently selected from one or more of tin, silver, indium, tin-lead alloy, tin-silver alloy, and tin-indium alloy.

[0011] Preferably, the temperatures of the first molten metal bath and the second molten metal bath are controlled between 250°C and 350°C.

[0012] Preferably, in steps (1) and (3), the immersion time of the first molten metal bath and the second molten metal bath is 2 to 5 seconds, respectively.

[0013] Preferably, the first metal is aluminum, an aluminum alloy, copper, or a copper alloy.

[0014] 5. The method for manufacturing the lead-acid battery composite busbar according to claim 1, wherein the thickness of the outer sheath is at least 0.1 mm.

[0015] More preferably, the thickness of the outer layer is 0.1~0.3 mm.

[0016] Preferably, the thickness of the first bonding transition layer is 0.05~0.1mm; and the thickness of the second bonding transition layer is 0.1~0.3mm.

[0017] Preferably, both the primary and secondary casting molds are equipped with cooling channels for rapid cooling after casting, with a cooling rate ≥50℃ / s.

[0018] The present invention also provides a lead-acid battery composite busbar prepared by the manufacturing method described above.

[0019] The present invention also provides a lead-acid battery, comprising an electrode group, the electrode group comprising alternating positive and negative electrode plates, the positive electrode plates having positive tabs, the negative electrode plates having negative tabs, the positive tabs in the same electrode group being arranged in a row, the negative tabs being arranged in a row, and the positive and negative electrode busbars being prepared using the manufacturing method described above.

[0020] Beneficial effects of this invention: (1) Breakthrough solution to the problem of metallurgical bonding of dissimilar metals: By constructing a metallurgical active transition layer system through double coating treatment, reliable metallurgical bonding of dissimilar metals such as aluminum / lead and copper / lead is achieved.

[0021] (2) Full dense coating is achieved: Through two castings, the design of the space compensation structure (i.e., the difference between the size of the casting cavity on the casting mold used for the two castings and weldings, leaving casting space) ensures that the lead alloy outer layer fully and densely coats the high conductivity metal core, eliminating the risk of corrosion.

[0022] (3) A low-impedance integrated current-conducting structure was constructed: the busbar and the pole were integrated by two castings, and a low-resistance interface-free path from the tab to the pole was constructed.

[0023] (4) Wide range of material compatibility and process flexibility: The highly conductive inner core can be selected from aluminum alloy or copper alloy, the coating material can be matched according to the inner core material, and the outer cladding can be selected from pure lead or lead alloy, which has a wide range of industrial application prospects. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the six electrode groups in a lead-acid battery when the busbar is not prepared.

[0025] Figure 2 This is a schematic diagram of the six electrode groups within a lead-acid battery after the busbar of the lead-acid battery of the present invention is prepared.

[0026] Figure 3 This is a cross-sectional view of the busbar with terminal posts.

[0027] Figure 4 This is a cross-sectional view of the busbar without poles.

[0028] Reference numerals: 1. Positive tab, 2. Negative tab, 3. Positive busbar, 4. Negative busbar, 5. Positive terminal post, 6. Negative terminal post, 7. Inner core, 8. Second bonding transition layer, 9. Outer cladding. Detailed Implementation

[0029] like Figures 1 to 4 As shown, a lead-acid battery includes an electrode group comprising alternating positive and negative plates. The positive plates have positive tabs 1, and the negative plates have negative tabs 2. The positive tabs 1 in the same electrode group are arranged in a row and connected in series using a positive busbar 3; the negative tabs 2 are arranged in a row and connected in series using a negative busbar 4. The structure shown is a direct-connection busbar, where adjacent electrode groups are directly connected by a positive busbar 3 and a negative busbar 4. Positive terminal posts 5 and negative terminal posts 6 are formed on the first and last positive busbar 3 and negative busbar 4, respectively.

[0030] like Figure 3 The diagram shows a cross-sectional view of a busbar (positive busbar 3 or negative busbar 4) with terminal posts (positive terminal post 5 or negative terminal post 6). Figure 4 The diagram shows a cross-sectional view of the busbar without poles. Both the busbar and poles consist of an inner core 7, a middle second bonding transition layer 8, and an outer cladding layer 9.

[0031] The manufacturing method of the positive busbar 3, the negative busbar 4, the positive terminal post 5, and the negative terminal post 6 includes the following steps: (1) The ends of the positive and negative tabs on the electrode group used for welding the busbar are immersed in a first molten metal bath, so that a first bonding transition layer is formed on at least the surface of the welding area of ​​each positive and negative tab. The first molten metal bath is selected from one or more of tin, silver, indium, tin-lead alloy, tin-silver alloy, and tin-indium alloy. The thickness of the first bonding transition layer is 0.05~0.1mm.

[0032] (2) The first molten metal is poured into the casting cavity of the primary casting mold. The positive and negative electrodes extend into the casting cavity of the primary casting mold and are cast and welded to form the inner core of the busbar and the inner core of the electrode post (uniformly labeled as inner core 7 in the figure). The first metal used in the first molten metal is aluminum, aluminum alloy, copper, or copper alloy. The ends of the electrodes and the first bonding transition layer are melted and mixed into the first molten metal and become part of the inner core.

[0033] (3) Immerse the inner core of the busbar and the inner core of the pole on the electrode group obtained in step (2) into the second molten metal bath, so that a second bonding transition layer 8 is formed on the surface of the inner core of the busbar and the inner core of the pole. The second molten metal bath is selected from one or more of tin, silver, indium, tin-lead alloy, tin-silver alloy, and tin-indium alloy. The thickness of the second bonding transition layer 8 is 0.1~0.3mm.

[0034] (4) The second molten metal is poured into the casting cavity of the secondary casting mold, and the inner core of the manifold and the inner core of the pole extend into the casting cavity of the secondary casting mold to form an outer cladding layer 9. The second metal used in the second molten metal is lead or a lead alloy. The thickness of the outer cladding layer 9 is at least 0.1 mm, preferably 0.1 to 0.3 mm.

[0035] The temperatures of the first and second molten metal baths are controlled between 250℃ and 350℃. In steps (1) and (3), the immersion times of the first and second molten metal baths are 2 to 5 seconds, respectively.

[0036] Both the primary and secondary casting molds are equipped with cooling channels for rapid cooling after casting, with a cooling rate of ≥50℃ / s.

[0037] Example 1 A method for manufacturing a composite busbar for a lead-acid battery, wherein the lead-acid battery model is 6-DZF-20, the lead-acid battery includes an electrode group, the electrode group including alternating positive and negative electrode plates, the positive electrode plates are provided with positive tabs, the negative electrode plates are provided with negative tabs, and the positive tabs in the same electrode group are arranged in a row, and the negative tabs are arranged in a row. The manufacturing method includes the following steps: (1) Immerse the ends of the positive and negative tabs on the electrode group used for welding the bus into the first molten metal bath, so that at least the surface of the welding area of ​​each positive and negative tab forms a first bonding transition layer.

[0038] The first molten metal bath uses tin.

[0039] The temperature of the first molten metal bath is controlled at 250℃. The immersion time of the first molten metal bath is 5 seconds.

[0040] The thickness of the first bonding transition layer is 0.05 mm.

[0041] (2) The first molten metal is poured into the casting cavity of the primary casting mold, and the positive and negative electrodes are inserted into the casting cavity of the primary casting mold to form the inner core of the busbar and the inner core of the electrode post. The first metal used in the first molten metal is aluminum.

[0042] (3) Immerse the inner core of the busbar and the inner core of the pole on the pole group obtained in step (2) into the second molten metal bath to form a second bonding transition layer on the surface of the inner core of the busbar and the inner core of the pole.

[0043] The second molten metal bath uses tin.

[0044] The temperature of the second molten metal bath is controlled at 250℃. The immersion time of the second molten metal bath is 5 seconds.

[0045] The thickness of the second bonding transition layer is 0.1 mm.

[0046] (4) The second molten metal is poured into the casting cavity of the secondary casting mold, and the inner core of the busbar and the inner core of the pole extend into the casting cavity of the secondary casting mold to form an outer cladding layer. The second metal used in the second molten metal is lead. The first metal used in the first molten metal has better electrical conductivity than the second metal used in the second molten metal.

[0047] The thickness of the outer cladding layer is 0.1~0.3mm.

[0048] Both the primary and secondary casting molds are equipped with cooling channels for rapid cooling after casting, with a cooling rate of ≥50℃ / s.

[0049] After preparing the lead-acid battery composite busbar using the above manufacturing method, a lead-acid battery is obtained by further manufacturing. The lead-acid battery includes an electrode group, which includes alternating positive and negative electrode plates. The positive electrode plates are provided with positive tabs, and the negative electrode plates are provided with negative tabs. In the same electrode group, the positive tabs are arranged in a row, and the negative tabs are arranged in a row. The positive and negative busbars are prepared using the manufacturing method described above.

[0050] Example 2 A method for manufacturing a composite busbar for a lead-acid battery, wherein the lead-acid battery model is 6-DZF-20, the lead-acid battery includes an electrode group, the electrode group including alternating positive and negative electrode plates, the positive electrode plates are provided with positive tabs, the negative electrode plates are provided with negative tabs, and the positive tabs in the same electrode group are arranged in a row, and the negative tabs are arranged in a row. The manufacturing method includes the following steps: (1) Immerse the ends of the positive and negative tabs on the electrode group used for welding the bus into the first molten metal bath, so that at least the surface of the welding area of ​​each positive and negative tab forms a first bonding transition layer.

[0051] The first molten metal bath uses tin.

[0052] The temperature of the first molten metal bath is controlled at 350℃.

[0053] The immersion time of the first molten metal bath was 2 seconds.

[0054] The thickness of the first bonding transition layer is 0.05 mm.

[0055] (2) The first molten metal is poured into the casting cavity of the primary casting mold, and the positive and negative electrodes are inserted into the casting cavity of the primary casting mold to form the inner core of the busbar and the inner core of the electrode post. The first metal used in the first molten metal is aluminum.

[0056] (3) Immerse the inner core of the busbar and the inner core of the pole on the pole group obtained in step (2) into the second molten metal bath to form a second bonding transition layer on the surface of the inner core of the busbar and the inner core of the pole.

[0057] The second molten metal bath uses tin.

[0058] The temperature of the second molten metal bath is controlled at 350℃.

[0059] The immersion time for the second molten metal bath was 2 seconds.

[0060] The thickness of the second bonding transition layer is 0.3 mm.

[0061] (4) The second molten metal is poured into the casting cavity of the secondary casting mold, and the inner core of the busbar and the inner core of the pole extend into the casting cavity of the secondary casting mold to form an outer cladding layer. The second metal used in the second molten metal is lead. The first metal used in the first molten metal has better electrical conductivity than the second metal used in the second molten metal.

[0062] The thickness of the outer cladding layer is 0.1~0.3mm.

[0063] Both the primary and secondary casting molds are equipped with cooling channels for rapid cooling after casting, with a cooling rate of ≥50℃ / s.

[0064] After preparing the lead-acid battery composite busbar using the above manufacturing method, a lead-acid battery is obtained by further manufacturing. The lead-acid battery includes an electrode group, which includes alternating positive and negative electrode plates. The positive electrode plates are provided with positive tabs, and the negative electrode plates are provided with negative tabs. In the same electrode group, the positive tabs are arranged in a row, and the negative tabs are arranged in a row. The positive and negative busbars are prepared using the manufacturing method described above.

[0065] Example 3 Everything else is the same as in Example 1, except that the thickness of the first bonding transition layer is 0.1 mm.

[0066] Example 4 Everything else is the same as in Example 2, except that the thickness of the first bonding transition layer is 0.1 mm.

[0067] Example 5 Everything else is the same as in Example 1, except that the thickness of the first bonding transition layer is 0 mm, meaning that the step of preparing the first bonding transition layer is omitted.

[0068] Example 6 Everything else is the same as in Example 2, except that the thickness of the first bonding transition layer is 0 mm, meaning that the step of preparing the first bonding transition layer is omitted.

[0069] Example 7 Everything else is the same as in Example 1, except that the thickness of the second bonding transition layer is 0 mm, meaning that the step of preparing the second bonding transition layer is not performed.

[0070] Example 8 Everything else is the same as in Example 3, except that the thickness of the second bonding transition layer is 0 mm, meaning that the step of preparing the second bonding transition layer is not performed.

[0071] Comparative Example 1 Using pure aluminum busbars, the busbars are formed by casting and welding in one step. There are no inner cores and outer cladding layers that are cast and welded in two steps, and there are no first and second bonding transition layers. The rest is the same as in Example 1.

[0072] Comparative Example 2 Using a pure lead busbar, the busbar is formed by a single casting and welding process. There are no two-step casting and welding processes involving an inner core and an outer cladding layer, nor are there a first and second bonding transition layers. The rest is the same as in Example 1. This is the lead busbar commonly used in the prior art.

[0073] Detection Example 1 According to the manufacturing method described in this invention, eight sets of example products (Examples 1-8) and two sets of comparative example products (Comparative Example 1 and Comparative Example 2) were prepared. Each example was prepared by adjusting the thickness parameters of the first bonding transition layer (tin layer) and the second bonding transition layer (lead-clad layer). Comparative Example 1 used a pure aluminum busbar, and Comparative Example 2 used a pure lead busbar as a control sample. The manufactured 6-DZF-20 lead-acid power battery underwent cycle life testing according to 8.11 of GB / T22199.1-2025, and the test method is as follows: 1. After the tested and qualified battery is fully charged, it is discharged at a current of 1.0I² for 1.60 hours in an environment of 25℃±5℃, and then charged at a voltage of 2.467V per cell (current limited to 0.35I²). When the current is less than 0.05I² or the charging time reaches 6 hours, it is allowed to stand for 5 minutes, and then continuously charged at a voltage of 2.317V per cell for 3 hours. The above constitutes one cycle life.

[0074] 2. The test will be terminated when the battery discharge voltage drops below 1.750V per cell for three consecutive cycles. These three cycles will not be counted in the life reliability test.

[0075] 3. The number of tests should be added to the total number of cycles according to the capacity of the test.

[0076] Table 1 The parameters of the first transition layer and the second bonding layer in each embodiment and comparative example, as well as the cycle life test results, are shown in Table 1. Based on the above life test data, the following analytical conclusions can be drawn: Comparative Example 1 shows that aluminum is chemically reactive and reacts with dilute sulfuric acid, causing the manifold to fail rapidly, thus significantly reducing its cycle life.

[0077] Comparative Example 2, produced using conventional manufacturing processes, exhibited a normal cycle life (520 cycles) and can be used as a benchmark.

[0078] Examples 5 and 6 suffer from poor performance due to the following two key defects: (1) the aluminum-based busbar lacks a necessary transition layer between the aluminum-based busbar and the lead-clad layer; and (2) the insulating oxide layer naturally formed on the aluminum-based surface severely affects the conductivity.

[0079] The failure mechanisms of Examples 7 and 8 are as follows: the external protective layer consists of only an extremely thin tin-plated layer, which is easily corroded through, allowing the electrolyte to contact the aluminum substrate and trigger a reaction. Therefore, the cycle life is significantly shortened.

[0080] Examples 3 and 4 employ an optimized design: a composite structure of a thicker tin-coated layer and a lead-clad layer, ensuring excellent conductivity and corrosion resistance, with a cycle life even superior to that of Comparative Example 2 using conventional processes.

[0081] Design features of Examples 1 and 2: A combination of a thinner tin layer and a lead-clad layer is adopted to control costs while ensuring basic protection performance. Its cycle life is comparable to that of Comparative Example 2 with conventional processes.

[0082] This invention employs a composite process of first tinning and then lead coating on the surface of an aluminum-based busbar, which has the following significant advantages: 1. Excellent electrical conductivity: Aluminum has significantly better electrical conductivity than lead. Using an aluminum substrate can greatly reduce resistance loss and improve energy transmission efficiency.

[0083] 2. Significant cost advantage: Although a tin-plating transition layer is added, the cost of aluminum-based materials is relatively low, and the overall cost is still lower than or equal to that of traditional pure lead casting and soldering processes.

[0084] 3. Good process compatibility: The tin coating can effectively improve the bonding between aluminum and lead, avoid the aluminum surface oxide layer from affecting the conductivity, and enhance the corrosion resistance.

[0085] 4. Improved overall performance: Compared with traditional pure lead processes, this invention significantly improves cycle life and conductivity while ensuring cost-effectiveness, making it suitable for high-reliability applications.

[0086] Therefore, this technical solution has both economic and high performance advantages and can be widely used in lead-acid batteries and other fields.

Claims

1. A method for manufacturing a composite busbar for a lead-acid battery, the lead-acid battery comprising an electrode group, the electrode group comprising alternately stacked positive and negative electrode plates, the positive electrode plates having positive tabs, the negative electrode plates having negative tabs, the positive tabs in the same electrode group being arranged in a row, and the negative tabs being arranged in a row, characterized in that... The preparation method includes the following steps: (1) Immerse the ends of the positive and negative tabs on the electrode group used for welding the bus into the first molten metal bath, so that at least the surface of the welding area of ​​each positive and negative tab forms a first bonding transition layer. (2) The first molten metal is poured into the casting cavity of the primary casting mold, and the positive and negative electrodes are inserted into the casting cavity of the primary casting mold to form the inner core of the busbar and the inner core of the electrode post. (3) Immerse the inner core of the busbar and the inner core of the pole on the pole group obtained in step (2) into the second molten metal bath to form a second bonding transition layer on the surface of the inner core of the busbar and the inner core of the pole. (4) The second molten metal is poured into the casting cavity of the secondary casting mold, and the inner core of the busbar and the inner core of the pole extend into the casting cavity of the secondary casting mold to form an outer cladding layer. In this process, the first metal used in the first molten metal has better electrical conductivity than the second metal used in the second molten metal, and the second metal is lead or a lead alloy. The first molten metal bath and the second molten metal bath are independently selected from one or more of tin, silver, indium, tin-lead alloy, tin-silver alloy, and tin-indium alloy.

2. The method for manufacturing the lead-acid battery composite busbar according to claim 1, characterized in that, The temperatures of the first and second molten metal baths are controlled between 250℃ and 350℃.

3. The method for manufacturing the lead-acid battery composite busbar according to claim 1, characterized in that, In steps (1) and (3), the immersion time of the first molten metal bath and the second molten metal bath is 2 to 5 seconds, respectively.

4. The method for manufacturing the lead-acid battery composite busbar according to claim 1, characterized in that, The first metal is aluminum, aluminum alloy, copper, or copper alloy.

5. The method for manufacturing the lead-acid battery composite busbar according to claim 1, characterized in that, The thickness of the outer layer is at least 0.1 mm.

6. The method for manufacturing the lead-acid battery composite busbar according to claim 5, characterized in that, The thickness of the outer cladding layer is 0.1~0.3mm.

7. The method for manufacturing the lead-acid battery composite busbar according to claim 1, characterized in that, The thickness of the first bonding transition layer is 0.05~0.1mm; The thickness of the second bonding transition layer is 0.1~0.3mm.

8. The method for manufacturing the lead-acid battery composite busbar according to claim 1, characterized in that, Both the primary and secondary casting molds are equipped with cooling channels for rapid cooling after casting, with a cooling rate of ≥50℃ / s.

9. A lead-acid battery composite busbar prepared by the manufacturing method according to any one of claims 1 to 8.

10. A lead-acid battery, comprising an electrode group, the electrode group comprising alternately stacked positive and negative electrode plates, the positive electrode plates having positive tabs, the negative electrode plates having negative tabs, the positive tabs in the same electrode group being arranged in a row, and the negative tabs being arranged in a row, characterized in that, The positive bus and the negative bus are prepared using the manufacturing method described in any one of claims 1 to 8.

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