# Renewal of Lead Battery Electrodes Using a Plasma--Chemical Processing Method
## 1 Introduction  
Recently, the rapidly developing industry of both renewable energy sources (such as solar power plants, etc.) and mobile devices (household battery tools, telephones, backup power sources, etc.) has been paying increasing attention to electrical energy storage devices of various types and sizes. Batteries store DC electricity using chemical reaction processes. Depending on the type of battery, the process of storing and releasing electricity is reversible or irreversible [1; 2; 3; 4]. There are two types of batteries: primary and secondary. Lead-type batteries are called secondary batteries because they are rechargeable. Lead-type batteries can be divided into starter and industrial batteries. Starter batteries are designed to provide high power impulse requiring systems, such as, e.g., vehicle starter systems, electric cars, backup power systems, etc. Industrial batteries are intended for long-term use and storage of electricity, e.g., for backup power supply of special-purpose buildings in the event of malfunctions of the external network, etc. [5; 6; 7; 8]. Pb-type batteries are produced in large quantities in the world, reaching 95 million units per year or more. In addition, the production scale of this type of battery is growing by about 2% every year. The chemical reaction during the charging of a lead-type battery: 2 PbSO4 + 2H2O \(\rightarrow\) PbO2 + Pb + H2 SO4, while the chemical reaction during the discharge process is: PbO2 + Pb + H2 SO4 \(\rightarrow\) 2 PbSO4 + 2H2O [9; 10; 11; 12; 13]. The electrodes of modern lead-type batteries are manufactured using a grid-shaped concept in order to save the materials and achieve the lowest possible mass of the device and to create the lowest possible amount of recyclable waste. During the charge/discharge cycle, the chemical reactions occur simultaneously with the corrosion of the Pb electrodes, which gradually wear and lose their original state and functionality. This process affects the number of life cycles and electrical capacity of Pb batteries. In order to reduce the corrosion of Pb electrodes, an alloy of lead and antimony is often used in the production process of this type of battery [14; 15; 16; 17]. In order to extend the service life of lead batteries and reducethe corrosion of Pb grid-shaped electrodes, it is very important to monitor the electrolyte level in the batteries, which should be sufficient. This factor is especially important in the operation of Pb-type liquid electrolyte batteries. During long-term operation of batteries, their service life depends not only on the corrosion process of Pb electrodes, but also on the formation of lead sulfate crystals on the surface of the electrodes. Lead sulfate crystals hinder the battery charging process [18; 19; 20; 21]. Lead-type batteries are characterized by the number of charge-discharge cycles of about 500-750, after which they wear out and become unusable, so there is a need to safely dispose them or recycle into the secondary raw materials. The main danger when operating the batteries is the possible release of lead particles and electrolyte into the environment. Lead is a sufficiently heavy element whose density is about 11.3 times higher than water, and lead waste also has the property of accumulating in soil, animal organisms, etc. [1; 22; 23; 24]. Other dangerous products that are left in used batteries are glass fiber in AGM-type batteries and silicon dioxide in GEL-type batteries. Almost all battery parts can be recycled. The main steps in recycling of Pb-type batteries are: collecting batteries and transporting them to a recycling facility, separating battery components, melting and refining lead components, washing plastic components, then crushing or melting them, cleaning and treating the sulfuric acid electrolyte, and waste treatment and disposal. Currently, about 98% of Pb batteries are recycled by utilizing their products or using them as secondary raw materials in circular economy processes [2; 3; 25; 26; 27].