Manufacturing basis of lead-acid batteries

Lead-acid battery manufacturing involves multiple key steps, from plate production to battery assembly, each of which significantly impacts the performance of the final product. Plate production begins the entire process, encompassing sub-steps such as lead powder production, grid casting, plate manufacturing, and plate formation. Lead powder production requires a pelletizer or segmenter, a lead powder machine, and a transportation and storage system. First-grade electrolytic lead is oxidized and screened using a lead powder machine to produce qualified lead powder. Grid casting utilizes a lead melting furnace, plate casting machine, and various molds to gravity-cast lead-antimony alloys, lead-calcium alloys, or other lead alloys into various types of grids. Plate manufacturing involves applying a mixture of lead powder, dilute sulfuric acid, and additives to the grid surface. The resulting green plates are then processed through surface drying and a curing and drying system. Plate formation involves using a charger and discharger to induce a redox reaction between the positive and negative plates and dilute sulfuric acid under the influence of direct current to produce lead oxide. This is then cleaned and dried to produce the positive and negative plates ready for battery assembly.

Principle of internalization process

The internal formation process involves charging and forming the battery directly after assembly. During this process, the positive and negative plates within the battery come into full contact with a dilute sulfuric acid electrolyte, where a complex series of redox reactions occur under the influence of direct current. The active material on the positive plate gradually transforms into lead dioxide, while the active material on the negative plate transforms into spongy lead. The internal formation process leverages the battery's internal chemical reaction environment and its inherent structural characteristics, allowing the plates to undergo the formation process in a relatively closed environment. This process better simulates the actual operating conditions of the battery, ensuring a more uniform distribution of active material across the plates, thereby improving battery consistency and stability. For example, in the production of a lead-acid battery manufacturer, the use of the internal formation process has significantly improved the consistency of the battery's initial capacity and significantly reduced capacity variations between different batteries.

Advantages of internalization process

The internal formation process offers several advantages. First, it can effectively reduce production costs. Since formation occurs directly after battery assembly, it eliminates the need for cleaning and drying the plates after formation, saving significant manpower, material resources, and time. Second, the internal formation process can improve the battery's sealing and safety. Performing formation inside the battery avoids potential contamination and damage to the plates during external formation, thereby reducing safety hazards such as battery leakage. Furthermore, batteries produced using the internal formation process exhibit improved consistency. Because the electrolyte distribution within the battery is more even, the plate reactions during the formation process are more consistent, resulting in more stable battery performance. According to statistics, the capacity consistency error of lead-acid batteries produced using the internal formation process can be controlled within a relatively small range, offering significant advantages over external formation processes.

Principle of externalization process

The external formation process involves a separate formation treatment of the plates after they are manufactured. The plates are placed in a dedicated formation tank filled with a dilute sulfuric acid electrolyte. A direct current is applied to the plates via a charger and discharger, causing the active substances on the plates to undergo a redox reaction, producing lead oxide. This external formation process, performed before the plates are assembled into a battery, focuses on treating the plates themselves, ensuring they possess excellent electrochemical properties before entering battery assembly. Precisely controlling parameters such as the formation current and time during this process ensures full conversion of the active substances in the plates, improving plate quality.

Advantages of externalized chemical processing

The external formation process also has unique advantages. It allows for more precise control of the plate formation process. Since individual plates are formed, the formation parameters can be flexibly adjusted to suit different plate specifications and requirements, ensuring optimal plate performance. Furthermore, plates produced using the external formation process can be thoroughly cleaned and dried to remove surface impurities and residual electrolyte, improving their purity and stability. Furthermore, the external formation process facilitates quality inspection and screening of the plates. After formation, various performance tests can be performed to promptly identify substandard plates, preventing their integration into batteries and improving overall battery quality. For example, one manufacturer has effectively reduced the defective rate of its batteries by rigorously testing its plates using the external formation process.

Comparison and selection of two processes

Both internal and external formation processes have their advantages and disadvantages, and lead-acid battery manufacturers need to consider multiple factors when choosing between them. From a cost perspective, the internal formation process offers significant advantages in large-scale production, reducing production steps and equipment investment. However, the external formation process offers more sophisticated plate quality control and testing, making it more suitable for applications requiring higher battery performance. In terms of production efficiency, the internal formation process reduces intermediate steps and offers a relatively short production cycle. While the external formation process involves more complex steps, production efficiency can be improved by optimizing formation parameters and equipment. Regarding product quality, batteries produced using the internal formation process have greater consistency, while plates produced using the external formation process exhibit higher purity and stability. Manufacturers need to weigh the pros and cons of both processes and make the appropriate choice based on factors such as their production scale, product positioning, and market demand. For example, for manufacturers primarily producing mid- and low-end automotive starting lead-acid batteries, the internal formation process may be more suitable; whereas for manufacturers producing high-end energy storage lead-acid batteries, the external formation process may better meet their product quality requirements.

In summary, lead-acid battery manufacturers employ both internal and external formation processes, each with its own unique characteristics and advantages. Understanding the principles, advantages, and applicable scenarios of these two processes will help manufacturers select the appropriate formation process based on their specific circumstances, improve production efficiency and product quality, and achieve better market competitiveness. Furthermore, with the continuous advancement of technology, lead-acid battery formation processes are also undergoing continuous innovation and improvement, and the future is expected to see the emergence of even more efficient, environmentally friendly, and high-quality formation processes.