# Renewal of Lead Battery Electrodes Using a Plasma--Chemical Processing Method
## 3 The Results and Discussion
This is because, during the charge/discharge process, part of the lead is lost during the ongoing chemical reactions,  
Figure 1: SEM pictures of the surface of the lead electrodes of the battery: (**a**) Pb electrodes of the new battery; (**b**) Pb electrodes of the battery after 500 life-cycles; (**c**) battery after 500 life cycles when the surface is treated with Ar plasma; (**d**) battery after 500 life cycles when the surface is treated with O\({}_{2}\) plasma. Figure 2: The determination of the elemental composition of the surface of the lead electrodes obtained by EDS: (**a**) Pb electrodes of the new battery; (**b**) Pb electrodes after 500 life cycles. and various compounds are formed that further delay the charging process. As it can be seen, in the case of Pb electrodes exposed to Ar and O\({}_{2}\) gas plasma, the lead content is similar to that of a new battery and reaches about 81-82%. Meanwhile, in both of these cases, a reduced amount of oxygen can be observed, which varies from 10.7 to 11.3%. As we can see, the sulfur is not detected at all after the exposure of Pb electrodes in Ar and O\({}_{2}\) gas plasma. The increase in lead and the disappearance of sulfur in this case can be explained by the fact that the formed surface sulfur compounds (including lead) are eroded, and the surface of the electrode is renewed. The XRD method was used to identify the chemical compounds with a crystalline structure on the surface of Pb. The XRD studies are presented in Figure 3. Analysis of the the XRD spectrograms showed that the new electrode is mainly composed of lead, and small peaks of Pb\({}_{4}\)O\({}_{3}\)SO\({}_{4}\) are also noticeable. This compound is likely formed when the electrolyte reacts with the surface of the Pb electrode. Meanwhile, the data on the orientation of lead crystals can also be seen in Figure 3. In the case of the worn-out battery and electrodes exposed to Ar and O\({}_{2}\) gas plasma, it was possible to identify Pb\({}_{2}\)(SO\({}_{4}\))O, Pb\({}_{2}\)SO\({}_{5}\), and Pb\({}_{2}\)SO\({}_{5}\) compounds in XRD X-ray images. These compounds are likely formed during the charge/discharge cycles when the Pb surface interacts with the liquid electrolyte. Additionally, analyzing the XRD results, it became clear that the peaks of the spectrum of the Pb\({}_{4}\)O\({}_{3}\)SO\({}_{4}\) compound are more pronounced in the case of worn-out battery electrodes than in the electrodes that were exposed to Ar or O\({}_{2}\) gas plasma. Therefore, it can be said (this is also confirmed by EDS studies) that the amount of various sulfur and lead compounds on the surface of affected Pb electrodes is reduced, thus the electrodes are renewed, and the amount of pure lead in them increases. Figure 4 shows the FTIR spectra of Pb electrodes. As can be seen in all cases, the spectra contain characteristic Pb peaks in the wavelength range of 500-1200 cm\({}^{-1}\). Peak characteristics of lead are at 600, 650, 1000, and 1250 cm\({}^{-1}\). C-H, C=C and O-H groups were also identified, with characteristic peaks at 1450, 1500, and 3600 cm\({}^{-1}\) wavelength values, respectively. It is likely that the mentioned groups are characteristic of the compounds formed on the surface of Pb electrodes during chemical reactions with the electrolyte and during charge/discharge processes. As it can be seen from the spectra, the least pronounced peak of the O-H group is for Pb electrodes that were exposed to Ar or O\({}_{2}\) plasma. Such a result can be explained by the fact that surface compounds are eroded or destroyed during Pb surface treatment, which have characteristic O-H groups visible in the spectra. In this way, it can be said that the Pb surface of the battery electrodes is renewed, and compounds that interfere with the charging process are removed from the surface [1; 2; 3; 4; 5].