Soldering flux for welding lead-acid storage battery and preparation method thereof

Abstract

The invention discloses a soldering flux for welding a lead-acid storage battery, which is characterized by comprising the following components in percentage by weight: 20-25% of a deoxidant, 10-20% of an activator, 2-5% of a surfactant, 1-2% of a corrosion inhibitor, 2-3% of an additive and the balance of a solvent, the deoxidant is any one of phosphoric acid, phosphorous acid and metaphosphoric acid; the activating agent is any one of oxalic acid, succinic acid, glutaric acid, citric acid, malic acid and tartaric acid; the surfactant is any one of polyoxyethylene ether, sodium dodecyl benzene sulfonate, alkyl betaine and perfluoroalkyl sulfonate; the corrosion inhibitor is any one of triethanolamine, octadecylamine, hexadecyl trimethyl ammonium bromide, benzimidazole and benzotriazole; the additive is ethyl acetate and s-triazine in a ratio of 4: 3; the solvent is any one of ethylene glycol, propylene glycol ether, propylene glycol, glycerol and 1, 4-butanediol. The method aims to solve the problem of halogen element residues in the cast welding process of the lead-acid storage battery.

Description

Technical Field

[0001] This invention relates to the technical field of lead-acid batteries, and specifically to a flux for welding lead-acid batteries and its preparation method. Background Technology

[0002] Lead-acid batteries are widely used due to their high performance and low cost. Lead-acid batteries are assembled in units of electrode groups. The same electrode plates within each group are cast-welded to a busbar to form the positive and negative busbars. The casting-welding method generally involves: wetting the stacked electrode plate group's plates in flux, then inserting the plates into molten lead, allowing the lead to melt the plate surface. The molten lead then cools and solidifies, thus connecting multiple plates together. The purpose of wetting the plate plates with flux is to aid welding, fusing the plates with the molten lead. The main function of flux in the welding process is to remove oxides from the plate surface, reduce the surface tension of the solder, enhance wettability, and prevent the plates from re-oxidizing during welding. Besides considering the flux's welding effect, the influence of the flux's components on battery performance must also be considered. Most lead-acid battery manufacturers in China commonly use fluxes containing halogens. Halogens are very effective at removing oxides from the surface of the lugs. However, halogen elements remain in the busbars and are oxidized during battery charging and discharging to form highly corrosive substances, which can lead to a decrease in battery life. Therefore, there is an urgent need to develop a new type of flux that can effectively remove the oxide layer on the lug surface, ensure welding quality, and avoid the problem of halogen element residue, thereby improving battery reliability and service life. Summary of the Invention

[0003] The purpose of this invention is to provide a flux for welding lead-acid batteries, which aims to solve the problem of residual halogen elements during the casting and welding process of lead-acid batteries, and the manufacturing method is simple.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A flux for welding lead-acid batteries comprises the following components by weight percentage: 20-25% oxidizing agent, 10-20% activator, 2-5% surfactant, 1-2% corrosion inhibitor, and 2-3% additive, with the balance being solvent; wherein the oxidizing agent is any one of phosphoric acid, phosphorous acid, and metaphosphoric acid; the activator is any one of oxalic acid, succinic acid, glutaric acid, citric acid, malic acid, and tartaric acid; the surfactant is any one of polyoxyethylene ethers, sodium dodecylbenzenesulfonate, alkyl betaine, and perfluoroalkyl sulfonate; the corrosion inhibitor is any one of triethanolamine, octadecylamine, hexadecyltrimethylammonium bromide, benzimidazole, and benzotriazole; the additive is ethyl acetate and triazine in a ratio of 4:3; and the solvent is any one of ethylene glycol, propylene glycol ether, propylene glycol, glycerol, and 1,4-butanediol.

[0005] Preferably, the deoxidizing agent comprises 20-23% phosphorous acid or 5% metaphosphoric acid by weight.

[0006] Preferably, the activator is 10% oxalic acid or 15% citric acid by weight.

[0007] Preferably, the surfactant is 3% sodium dodecylbenzenesulfonate or 5% alkyl betaine by weight percentage.

[0008] Preferably, the corrosion inhibitor is 1% benzimidazole or 1.5% triethanolamine by weight.

[0009] Preferably, the solute is ethylene glycol or propylene glycol.

[0010] Preferably, it consists of the following components in weight percentage: 20% phosphorous acid, 15% citric acid, 3% sodium dodecylbenzenesulfonate, 1% benzimidazole and 2% additives, with the balance being solvent.

[0011] The preparation method of the above-mentioned flux for welding lead-acid batteries specifically includes the following steps: Step 1: Mix the activator, surfactant and solvent according to the formula and stir with a magnetic stirrer until clear to obtain liquid A. The speed of the magnetic stirrer is 500-700 r / min. Step 2: Slowly add the deoxidizing agent to liquid A and stir until homogeneous. After cooling to room temperature, liquid B is obtained. Step 3: After adding the additive to the liquid B, stir with a magnetic stirrer for 30-40 minutes at a speed of 500-700 r / min until the additive is completely dissolved to obtain a flux for welding lead-acid batteries.

[0012] Compared with the existing technology, the present technical solution has the following beneficial effects: The flux of this invention can efficiently remove stubborn oxides such as lead oxide and lead hydroxide from the surface of the electrode plate lugs, solving the problem of false welding and cold welding caused by oxide layer blockage, and significantly improving the stability and reliability of casting welding; at the same time, compared with the flux containing halogens in the prior art, this invention has no halogen element residue, eliminating the battery corrosion risk caused by it.

[0013] The deoxidizing agent corrodes and reduces the oxide layer on the surface of the plate, exposing fresh metallic lead. A protective phosphate film forms on the plate surface, preventing secondary oxidation. This phosphate film dissolves after the plate enters the molten lead, improving its bonding strength. The activator and deoxidizing agent work synergistically to further remove oxides from the plate surface and ensure the flux's activation effect throughout the welding process, promoting solder wetting and achieving good welding results for the lead-acid battery busbar. Simultaneously, the high temperature during welding promotes the decomposition and volatilization of the activator, preventing residues on the plate surface and ensuring no impact on subsequent battery performance. The surfactant is selected from polyoxyethylene ethers, sodium dodecylbenzene sulfonate, alkyl betaine, and perfluoroalkyl sulfonates. It is readily soluble in organic solvents, enhancing the dissolution and uniform mixing of flux components. Furthermore, the surfactant is less affected by inorganic salts, exhibits stable behavior, effectively reduces the surface tension of the lugs, improves flux spreading and wetting on the metal surface, assists solder climbing and flow, and improves the cleanability of oxidation residues, ensuring a strong weld between the lugs and the busbar. The corrosion inhibitor inhibits the corrosion of the alloy in the lugs by oxidizing agent and activator residues. After immersing the electrode group in the electrolyte, it can block the erosion of the busbar by residual electrolyte. The additives have good compatibility with other components in the flux, improving the uniformity and stability of the flux. They are also easily volatilized during welding, leaving no residue after welding and not affecting the quality of the cast weld. Moreover, they can isolate oxygen, further preventing the lugs from being re-oxidized.

[0014] The solvent's role is to dilute the deoxidizer and activator, reduce the viscosity of the deoxidizer, and improve the drying efficiency of the tabs after flux application. It also further improves the wettability and spreadability of the flux, ensuring a uniform coating of the flux on the tab surface. Furthermore, its high boiling point stability and strong wettability prevent the solvent from evaporating while the tab is awaiting soldering, thus preventing secondary oxidation. When the tab comes into contact with molten lead for soldering, the high temperature promotes the decomposition and evaporation of the solvent, leaving no residue on the tab surface and not affecting subsequent battery performance. Additionally, the solvent decomposes and evaporates upon contact with the high-temperature liquid solder, breaking down and eliminating pores generated during the solidification and shrinkage of the liquid solder. This prevents pores from causing excessive internal resistance at the solder joint, which would hinder current conduction. It also avoids the problem of solvent exploding or causing short circuits when it encounters molten lead. Attached Figure Description

[0015] Figure 1 This is a cyclic test diagram of Embodiment 2 and Comparative Example 1 of the present invention. Detailed Implementation

[0016] The embodiments of the present invention will be further described below with reference to examples: A flux for welding lead-acid batteries comprises the following components in weight percentage: 20-25% oxidant, 10-20% activator, 2-5% surfactant, 1-2% corrosion inhibitor and 2-3% additive, with the balance being solvent. The deoxidizing agent can be any one of phosphoric acid, phosphorous acid, or metaphosphoric acid. The activator is any one of oxalic acid, succinic acid, glutaric acid, citric acid, malic acid, and tartaric acid; The surfactant is any one of polyoxyethylene ethers, sodium dodecylbenzene sulfonate, alkyl betaine, and perfluoroalkyl sulfonate. The corrosion inhibitor is any one of triethanolamine, octadecylamine, hexadecyltrimethylammonium bromide, benzimidazole, and benzotriazole; The additives are ethyl acetate and triazine in a ratio of 4:3; The solvent is any one of ethylene glycol, propylene glycol ether, propylene glycol, glycerol, and 1,4-butanediol.

[0017] In a preferred embodiment, the deoxidizing agent comprises 20-23% phosphorous acid or 5% metaphosphoric acid by weight.

[0018] In a preferred embodiment, the activator is 10% oxalic acid or 15% citric acid by weight percentage.

[0019] In a preferred embodiment, the surfactant comprises 3% sodium dodecylbenzenesulfonate or 5% alkyl betaine by weight percentage.

[0020] In a preferred embodiment, the corrosion inhibitor is 1% benzimidazole or 1.5% triethanolamine by weight.

[0021] In a preferred embodiment, the solute is ethylene glycol or propylene glycol.

[0022] In a preferred embodiment, it comprises the following components in weight percentage: 20% phosphorous acid, 15% citric acid, 3% sodium dodecylbenzenesulfonate, 1% benzimidazole and 2% additives, with the balance being solvent.

[0023] The preparation method of the flux for welding lead-acid batteries in the above-described scheme specifically includes the following steps: Step 1: Mix the activator, surfactant and solvent according to the formula and stir with a magnetic stirrer until clear to obtain liquid A. The preferred speed of the magnetic stirrer is 500-700 r / min. Step 2: Slowly add the deoxidizing agent to liquid A and stir until homogeneous. After cooling to room temperature, liquid B is obtained. Step 3: After adding the additive to liquid B, stir with a magnetic stirrer for 30-40 minutes, preferably at a speed of 500-700 r / min, until the additive is completely dissolved to obtain a flux for lead-acid battery welding. Example 1

[0024] A flux for welding lead-acid batteries, by weight percentage, comprises: 20% metaphosphoric acid, 10% oxalic acid, 2% sodium dodecylbenzenesulfonate, 1% triethanolamine, 1.1% ethyl acetate, 0.9% triazine, and 65% ethylene glycol. It is prepared by the following steps: a) Mixing 10% oxalic acid, 2% sodium dodecylbenzenesulfonate, and 65% ethylene glycol, and stirring with a magnetic stirrer until clear, obtaining liquid 1 at a speed of 600 r / min; 2) Slowly adding 20% ​​metaphosphoric acid to liquid 1 and stirring until homogeneous, and after cooling to room temperature, obtaining liquid 2; 3) Adding 1.1% ethyl acetate and 0.9% triazine to liquid 2, and stirring with a magnetic stirrer at a speed of 600 r / min for 40 min until the ethyl acetate and triazine are completely dissolved, obtaining flux A for welding lead-acid batteries. Example 2

[0025] A flux for welding lead-acid batteries, by weight percentage, comprises: 25% phosphorous acid, 15% citric acid, 3% alkyl betaine, 2% benzimidazole, 1.7% ethyl acetate, 0.3% triazine, and 53% propylene glycol. It is prepared by the following steps: a) mixing 15% citric acid, 3% alkyl betaine, and 53% propylene glycol, and stirring with a magnetic stirrer until clear to obtain liquid 3 at a speed of 600 r / min; 2) slowly adding 25% phosphorous acid to liquid 3 and stirring until homogeneous, and after cooling to room temperature to obtain liquid 4; 3) adding 1.7% ethyl acetate and 0.3% triazine to liquid 4, and stirring with a magnetic stirrer at a speed of 600 r / min for 35 min until the ethyl acetate and triazine are completely dissolved to obtain flux B for welding lead-acid batteries. Example 3

[0026] A flux for welding lead-acid batteries, by weight percentage, comprises: 23% phosphoric acid, 20% citric acid, 2% polyoxyethylene ether, 2% benzimidazole, 1.1% ethyl acetate, 0.9% triazine, and 51% propylene glycol. It is prepared by the following steps: a) Mixing 20% ​​citric acid, 2% polyoxyethylene ether, and 51% propylene glycol, and stirring with a magnetic stirrer until clear, yielding liquid 5 at a speed of 600 r / min; 2) Slowly adding 23% phosphoric acid to liquid 5 and stirring until homogeneous, and after cooling to room temperature, yielding liquid 6; 3) Adding 1.1% ethyl acetate and 0.9% triazine to liquid 6, and stirring with a magnetic stirrer at a speed of 600 r / min for 35 min until the ethyl acetate and triazine are completely dissolved, yielding flux C for welding lead-acid batteries. Example 4

[0027] A flux for welding lead-acid batteries, by weight percentage, comprises: 23% metaphosphoric acid, 15% malic acid, 5% sodium dodecylbenzenesulfonate, 2% benzotriazole, 1.1% ethyl acetate, 0.9% triazine, and 53% propylene glycol ether. It is prepared by the following steps: a) mixing 15% malic acid, 5% sodium dodecylbenzenesulfonate, and 53% propylene glycol, and stirring with a magnetic stirrer until clear, to obtain liquid 7 at a speed of 600 r / min; 2) slowly adding 23% metaphosphoric acid to liquid 7 and stirring until homogeneous, and after cooling to room temperature, obtaining liquid 8; 3) adding 1.1% ethyl acetate and 0.9% triazine to liquid 8, and stirring with a magnetic stirrer at a speed of 600 r / min for 35 min until the ethyl acetate and triazine are completely dissolved, to obtain flux D for welding lead-acid batteries.

[0028] Comparative Example 1 is a commercially available flux.

[0029] Example 5: 50% Discharge Depth Cycling The flux prepared in Example 2 and the flux in Comparative Example 1 were used to fabricate 12V 70Ah batteries for testing. The batteries were cycled at 50% depth discharge, discharged at 17.5A for 2 hours at 40°C, and then charged at 17.5A for 5 hours with a current limit of 14.4V. This process was repeated 360 times or terminated when the battery terminal voltage ≤10V. The termination voltage for each cycle was recorded. Comparative data between the batteries of Example 2 and Comparative Example 1 are shown below. Figure 1 .

[0030] As can be seen from Figure 1, the lead-acid battery prepared with the flux of the present invention has better cycle performance than the lead-acid battery prepared with existing flux.

[0031] The embodiments are merely illustrative of the concept and implementation of the present invention and are not intended to limit it. Under the concept of the present invention, technical solutions without substantial changes are still within the scope of protection.

Claims

1. A flux for welding lead-acid batteries, characterized in that, It consists of the following components by weight percentage: 20-25% deoxidizer, 10-20% activator, 2-5% surfactant, 1-2% corrosion inhibitor and 2-3% additives, with the balance being solvent. The deoxidizing agent is any one of phosphoric acid, phosphorous acid, and metaphosphoric acid; The activator is any one of oxalic acid, succinic acid, glutaric acid, citric acid, malic acid, and tartaric acid; The surfactant is any one of polyoxyethylene ethers, sodium dodecylbenzene sulfonate, alkyl betaine, and perfluoroalkyl sulfonate. The corrosion inhibitor is any one of triethanolamine, octadecylamine, hexadecyltrimethylammonium bromide, benzimidazole, and benzotriazole. The additive is ethyl acetate and triazine in a ratio of 4:3; The solvent is any one of ethylene glycol, propylene glycol ether, propylene glycol, glycerol, or 1,4-butanediol.

2. The flux for welding lead-acid batteries as described in claim 1, characterized in that, The deoxidizing agent comprises 23-25% phosphorous acid or 20-23% metaphosphoric acid by weight.

3. The flux for welding lead-acid batteries as described in claim 2, characterized in that, The activator is 10-13% oxalic acid or 15-20% citric acid by weight percentage.

4. The flux for welding lead-acid batteries as described in claim 3, characterized in that, The surfactant is 2-3% sodium dodecylbenzenesulfonate or 3-5% alkyl betaine by weight percentage.

5. The flux for welding lead-acid batteries as described in claim 4, characterized in that, The corrosion inhibitor is 1-2% benzimidazole or 1-1.5% triethanolamine by weight.

6. The flux for welding lead-acid batteries as described in claim 5, characterized in that, The solute is ethylene glycol or propylene glycol.

7. The method for preparing flux for welding lead-acid batteries as described in any one of claims 1 to 6, characterized in that, Specifically, the following steps are included: Step 1: Mix the activator, surfactant and solvent according to the formula and stir with a magnetic stirrer until clear to obtain liquid A. The speed of the magnetic stirrer is 500-700 r / min. Step 2: Slowly add the deoxidizing agent to liquid A and stir until homogeneous. After cooling to room temperature, liquid B is obtained. Step 3: After adding the additive to the liquid B, stir with a magnetic stirrer for 30-40 minutes at a speed of 500-700 r / min until the additive is completely dissolved to obtain a flux for welding lead-acid batteries.

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