Transmission X-Ray Microscopy of the Galvanostatic Growth of Lead Sulfate on Lead: Impact of Lignosulfonate

Abstract

The galvanostatic growth of PbSO 4 on Pb in H 2 SO 4 was studied using scanning electron microscopy and in situ transmission x-ray microscopy (TXM). Images from the TXM are used to investigate the effects of sodium lignosulfonate on the PbSO 4 formation and the initial growth of the PbSO 4 crystals. Sodium lignosulfonate is shown to retard, on average, the growth of the PbSO 4 crystals, yielding a film with smaller crystals and higher crystal densities. In addition, results from experiments with and without sodium lignosulfonate indicate an increase in the nucleation rate of the PbSO 4 crystals when the oxidation current is applied, which was attributed to an increase in the supersaturation of the electrolyte. Furthermore, an analysis of the growth rates of individual, large crystals showed an initial rapid growth which declined as the PbSO 4 surface coverage increased. It was concluded that the increase in PbSO 4 provides additional sites for precipitation and reduces the precipitation rate on the existing crystals. Finally, the potentialtime transient at the beginning of oxidation is suggested to result from the relaxation of a supersaturated solution and the development of a PbSO 4 film with increasing resistance.

Visualization of Electrolyte Reaction Field Near the Negative Electrode of a Lead Acid Battery by Means of Amplitude/Frequency Modulation Atomic Force Microscopy

“…When the LS was added, the density of PbSO crystals formed on the lead electrode after anodic oxidation (discharging) decreased, and the crystals grew [ 22 ]. Knehr et al also suggested a similar tendency for crystal growth by means of TXM [ 20 , 21 ]. However, research on the adsorption site of the expander and the solvation structure in the electrolyte has not significantly progressed, while a number of research papers on morphological changes in the negative electrode during the reaction due to the addition of expander were published [ 10 , 11 , 12 , 13 , 14 ].…”

“…Several evaluation methods for negative electrodes have been demonstrated, such as contact-mode AFM [ 16 , 17 ], scanning electron microscopy (SEM) [ 18 ], confocal laser scanning microscopy (CLSM) [ 19 ], and transmission X-ray microscopy (TXM) [ 20 , 21 ]. In these studies, when using contact-mode AFM for the in situ observation of the lead electrode surface, the reaction that occurred on the electrode surface could be observed directly [ 16 , 17 ], and SEM images of PbSO films on lead showed that the crystallite size was clearly a function of the potential [ 18 ].…”