Lead‑carbon batteries for automotive applications: Analyzing negative plate performance under partial state-of-charge cycles

This study analyzes the cycle performance of negative plate-limited lead‑carbon (LC) and lead-acid (LA) cells via a 17.5% depth-of-discharge cycle test. Both cells are above the cycling termination (voltage of 1.6667 V), but their 20-h capacities constantly decreased, revealing a progressing wear-out. The LC electrode relieves the decay shown by lower sulfation, less spatially uneven distribution of PbSO4 on the electrode cross-section, and minor loss of electrode reactivity. These result from the retarded polarization, thus the overpotential of the LC electrode varies in a smaller range and maintains the system at its effective state. This study reveals the improvement due to the carbon-coating by regulating the voltage over-change, thereby decelerating the degradation based on its large surface area and high electrochemical stability. Additionally, the study highlights that the LC electrode's high electrochemical surface can decelerate the potential increase toward the gassing level, thus, lowering the chance for the hydrogen evolution to occur. These findings suggest potential avenues for the LC electrode to maintain the cell at effective operating states based on the controlled voltage change, thereby enhancing the cell performance and lifespan.