Industrial Aging of Field-Deployed Lead–Acid Batteries II—Case Study of Prematurely Failed OPzS-Type Flooded Lead–Acid Batteries

Premature failure of industrial lead–acid batteries can arise not only from conventional aging but also from atypical environmental exposure that changes the chemistry and morphology of corrosion products. This study presents a focused post mortem investigation of three industrial flooded lead–acid batteries that underwent premature failure shortly after building renovation, despite differing in manufacturer, nominal capacity, operational target, and service time. Corrosion products collected from electrolytes, bridges, and terminals were examined by Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and complementary electrochemical testing of lead-based alloys in sulfuric acid. Raman spectra indicated mixtures of α- and β-PbO2, PbSO4, and trace PbS, whereas XRD identified the dominant crystalline phases as PbO2 polymorphs, PbO, PbSO4, and Pb3O4. The absence of a strong PbS signal in XRD is consistent with its low amount, poor crystallinity, and surface-localized occurrence. SEM images showed loose corrosion products rather than a dense protective layer. The combined evidence indicates an atypical, sulfide-associated corrosion pattern. External H2S exposure is considered as one possible source of sulfur-containing species; however, no atmospheric H2S measurements, renovation-material analyses, or controlled exposure tests were performed.