Cycle performance analysis of lead–carbon electrode under high-load conditions for automotive battery applications

This work studies the cycle performance of lead-carbon (LC) negative electrode and reference lead negative electrode via a 50% depth-of-discharge (50%DoD) cycle test for automotive applications. The cycle performance results reveal a greater cycle number for the LC cell. The discharge voltages and the growth of peaks at high DoD in differential voltage analysis exhibit alleviated concentration loss phenomenon for the LC cell. Sulfation is confirmed for both kinds of electrodes via X-ray diffraction. Scanning electron microscopy (SEM) and cyclic voltammetry (CV) reveal better preserved inner morphology and electrochemical reactivity for the cycled LC electrode, respectively, while SEM and energy-dispersive X-ray spectroscopy (EDS) detect PbSO4 existence on the carbon layer. EDS on the electrode cross-section confirms PbSO4 deposition on the carbon layer and less sulfation in the LC electrode interior. CV results indicate effects resulting from PbSO4 deposition on the carbon layer through decreasing capacitance and suppressed hydrogen gassing. Conclusively, the carbon layer of the LC electrode creates exterior sharing space for PbSO4 precipitation, causing lower sulfation of the inner electrode interface. Thus, the present study establishes the electrode degradation mode and cycle performance of the lead-carbon electrode in this cycling profile.