# Renewal of Lead Battery Electrodes Using a Plasma--Chemical Processing Method
## 4 Conclusions  
Ar and O\({}_{2}\) plasmas were used to renew the Pb electrodes. The process took place in a vacuum magnetron system. Using Ar and O\({}_{2}\) plasmas, the aim was to renew the surface of the worn Pb electrodes of batteries by removing the formed surface compounds that hinder the charge/discharge process. As can be seen from the images obtained by SEM, the surface of the Pb electrode of the new battery is composed of irregularly shaped microstructures of various sizes, the dimensions of which vary in the range of 10-50 \(\upmu\)m. Meanwhile, the surfaces of worn battery electrodes and those affected by Ar plasma electrodes are more uniform and less pronounced. XRD studies showed that a Pb\({}_{4}\)O\({}_{3}\)SO\({}_{4}\) compound is formed on the surface of the Pb electrode of the new battery. From the XRD spectrograms, it can be seen that the peaks of the spectrum of the Pb\({}_{4}\)O\({}_{3}\)SO\({}_{4}\) compound are more pronounced in the case of the electrodes of the worn battery compared to the electrodes that were exposed to Ar and O\({}_{2}\) gas plasma. In the FTIR spectra of Pb electrodes, characteristic peaks of Pb are observed in the wavelength range of 500-1200 cm\({}^{-1}\). The least pronounced peak of the O-H group, with a position at 3600 cm\({}^{-1}\), is found in Pb electrodes exposed to Ar and O\({}_{2}\) plasma. The measurements show that the wear of Pb electrodes and exposure to Ar and O\({}_{2}\) plasma have almost no effect on the electrical conductivity, since the electrical conductivity of both new Pb electrodes that are worn and those exposed in plasma ranges from 6.2 to 6.7 S. After the analysis of the research results in general, it can be said that the process of renewal of Pb electrodes in Ar and O\({}_{2}\) plasma has a positive effect. This effect is also confirmed by the results of EDS and XRD studies, as the chemical compounds, inhibiting the charge/discharge process, are reduced, and the percentage of pure lead increases from 68.2% (in the case of worn electrodes without plasma processing) up to 81-82% (when the worn electrodes were processed using Ar and O\({}_{2}\) plasma). Meanwhile, in the compounds of oxygen-containing electrode material, according to EDS studies, the content of old electrodes (untreated with Ar and O\({}_{2}\) plasma) is about 21%, while the content of oxygen in plasma-treated electrodes is 10.7% and 11.3% (treated with Ar and O\({}_{2}\) plasma, respectively), which is approximately the same as in the new electrode--11%. This also confirms the effectiveness of the treatment method for these Pb electrodes, since the composition of the old electrodes becomes similar to the chemical composition of the new electrode.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Pb (New) [S]** & **Pb (Old) [S]** & **Pb (Ar) [S]** & **Pb (O\({}_{2}\)) [S]** \\ \hline
6.2 & 6.7 & 6.7 & 6.2 \\ \hline \hline \end{tabular}
\end{table}
Table 2: The electrical conductivity of Pb electrodes.  
**Author Contributions:** Methodology, G.B.; Software, I.S.; Formal analysis, G.G.; Writing--original draft, Z.K. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest.