The lead-acid battery consists of two electrodes submerged in an electrolyte of sulfuric acid. The positive electrode is made of grains of metallic lead oxide, while the negative electrode is attached to a grid of metallic lead. Lead-acid batteries are classified into two types: flooded and valve-regulated. Lead-acid batteries are commonly used for renewable energy systems, largely because they can be easily transported and have relatively low costs. However, these batteries have some challenges, including low numbers of charging-discharging cycles over their lifetimes, low discharge intensities, restricted lifetimes, and slow charging rates. New lead-acid batteries utilize carbon on the negative electrode to create a supercapacitor negative electrode. In these batteries, the positive electrode does not undergo any change in its chemical process, and no chemical process occurs at the negative electrode. As a result, the positive electrode is less subject to corrosion, leading to longer lifetimes and higher efficiencies than conventional lead-acid batteries.