Lead-acid battery negative grid copper plating lead technology research

Abstract: This paper describes the lead-acid batteries (Lead-acidbattery) negative grid copper plating process, before plating copper mesh pre-processing and electroplating technology to improve product quality, to achieve both high efficiency, low energy consumption.

1 copper network pretreatment

1.1 skim

Copper mesh in its production and molding process, the surface contaminated with substances other than oil is inevitable, the plating must first skim (degreasing) to deal with, otherwise difficult or lead plating plated or deposit adhesion and fall off.

Commonly used degreasing degreasing chemical, organic solvents, degreasing, electrochemical degreasing, wipe degreasing and ultrasonic degreasing. Chemical degreasing is the use of hot alkali saponification and emulsification of grease to remove the saponification of fats, the use of surfactants milk

Of the role to remove non-saponifiable oil. Lye, sodium hydroxide content should not be too high. Alkali degreasing only saponification Animal and vegetable fats and oils, copper online contain mineral oils, shall be added to the soap powder, OP emulsifier and surfactant in addition to.

Ultrasonic degreasing degreasing fluid machinery enables the use of ultrasonic oscillations generated tens of thousands of small bubbles in the production and closed the formation of strong mechanical forces, so that objects on the adhesion of grease and dirt quickly out, thus speeding up skim over

Process, skim more thoroughly. When using the ultrasonic degreasing degreasing fluid temperature and concentration is not too high, otherwise it will hinder the spread of ultrasound to reduce the degreasing ability. The copper mesh degreasing method of combining the alkali degreasing and ultrasonic degreasing. Ultrasound device security

Installed in the the lye slot intramural, the use of ultrasound can reduce the alkali concentration and temperature, can save energy and protect the copper mesh from corrosion, degreasing effect or.

Must be fully copper mesh degreasing and cleaning, to avoid the lye into the next process, affecting the erosion effect.

1.2 erosion

After the degreasing of copper network, the erosion process, erosion can remove the copper oxide film online and corroded material, to improve the bonding strength of the copper mesh substrate and the coating.

The etching solution of sulfuric acid, nitric acid and hydrochloric acid. Sulfuric acid solution at room temperature on the dissolution of the metal oxide is weak, improve concentration, did not significantly improve the erosion of the sulfuric acid capacity, the volume concentration was maintained at 200 ~ 250mL / L that is,

Can. Hydrochloric acid at room temperature, the metal oxide has a strong chemical dissolution, the volume concentration of about 3mL / L; nitric acid can effectively remove the copper thermal oxidation of the online skin, the concentration is generally 50 to 100mL / L. Nitric acid and hydrochloric acid mixed role in the copper network rendering

Metallic luster, and erosion during use should be based on the loss amount and copper networks brightness appropriate to add nitric acid to maintain their concentration.

After the etching of the copper network must be thoroughly after water and pure water cleaning can be transferred to the plating process.

· Fluoborate plating lead solution preparation and composition requirements

2.1 bath preparation

First a certain amount of pure water injected into the bath preparation of the slot, in the case of mixing gradually by adding hydrofluoric acid, and then collated by adding boric acid, hydrofluoric acid and boric acid reaction of the fluoroborate:


Bath preparation formula



To make the bath does not generate precipitation of lead fluoride solution can not be free hydrofluoric acid, boric acid should be excessive. Slowly add the oxidized lead powder, stir so that the reaction completely, generating fluoroborate lead:


Bath preparation formula



Or basic lead carbonate and water into a paste, stirring constantly, slowly add the fluoroborate lead fluoroborate generated:


Bath preparation formula



Standing, filtration, coupled with pure water, the density transferred to the appropriate level after adding lignin sulfonate or glue additive, stir

2.2 bath composition requirements

Additives for coating crystalline careful to ensure that a high current efficiency, in addition to maintain the stability of the fluoroborate lead concentration in the bath also contains a certain amount of free fluoride borate, free boric acid, and plastic (or lignin).

The fluoroborate role is to ensure the normal dissolution of PbO and lead anode, and fluoroborate lead, stable solution to increase solution conductivity, the thinner the coating crystalline, and reduce the formation of dendrites.

Excessive presence of boric acid in order to prevent the generation of hydrogen fluoride, in order to avoid the generation of the white precipitate of lead fluoride (PbF2), the lead anode dissolution good bath stability.

Additives of small amount of glue (lignin) is primarily used to improve the coating crystalline. Additive content, the coating is rough, throwing power, covering power, prone to dendrite; additive content is too high, coating will produce stripes.

Anode strips to use pure lead, antimony, silver and copper content as low as possible, to avoid the formation of anode mud, the coating is rough. The fluoborate lead plating solution is stable, the anodic dissolution and cathodic precipitation of the basic balance, and lead ion content allows a wide range of

, So the solution does not require frequent adjustment. Taking into account the copper mesh of the workpiece with a loss, according to the production, weekly or monthly, according to the analysis, appropriate to add fluoride boric acid, boric acid, and additives. A long time to stop production, to be taken

Lead anode strips, so that the lead anode excessive dissolved, resulting in the imbalance of the solution composition. The lead anode can be stored in clean water.

3 hook and conductive contact

Copper mesh plating process, plating pretreatment and electroplating solution for plating quality is good or bad is important, linked and conductive contact can not be ignored.

Linked to the plating indispensable tool for the electroplating of copper mesh, there are two hooks, one is to connect the anode bar and terrific, and the other is connected to the copper network and other great. Linked to both fixed copper network and lead anode, but also to ensure uniform current flows through the copper mesh

. Lead anode weight and length, light area of ​​the copper network features such as the rational design of the hook: there is a sufficient mechanical strength and good electrical conductivity, solid contact, handling, light weight, should be to maximize production efficiency.

Generally refers to the conductive contact linked with the other great exposure linked to contact with the anode linked to contact with the copper mesh, conductive contact with a direct impact on the current distribution, each point of contact should be to maintain the color of copper, not only can reduce the resistance of can reduce the

As the local contact for the current uneven distribution of the result of poor or non-conductive. In particular, the copper network when several pieces of parallel plating conductive contact is not good cause uneven current distribution, and its direct consequences caused by the difference of the coating weight. Recommended to contact with parts of the conductive

To regular brushing to keep clean.

4 current and time

The plating current and time is determined on the basis of the coating area, thickness, and the requirements of the work efficiency. A wide range of current density, generally between 1 ~ 3A/dm3, the actual operation can be divided into three stages. Based on actual production

, Under the premise of ensuring the quality of the coating, the current and time can be adjusted appropriately in order to achieve optimization.
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5 · Conclusion

Electroplating of copper mesh is an important process in the production of high-capacity lead-acid batteries, the process is after countless times of trial and error to get. Production, must pay attention to the process provided for a variety of technical parameters, and to strengthen the process management. Achieve

Product quality, economic and environmental benefits, win-win-win.