Effects of exfoliated graphite addition in ultra-trace concentration on industrial-scale lead-acid battery performance

The present investigation has the main objective to elucidate the hypothesis whether the addition of graphite nanoplatelets in ultra-trace concentrations (mg.kg-1) in negative plates are able to affect the electrochemical behavior of lead-acid batteries. The 60 Ah full scale batteries were produced in an industrial unit and assembled with three types of graphite nanoplatelets of different exfoliation intensities and in five different concentrations. Through electrical tests, it was possible to establish that certain concentrations of types of these additives are capable of increasing CCA performance, charge acceptance and PSOC cycling. The analysis of the structure (new, charged and discharged and post mortem) through SEM and evaluation of the macroporosity variation identified that the increase in electrochemical performance is associated with the structural change caused by the addition of these additives. Due to the small amounts of additives involved, the polarization is only slightly altered, signaling that the water loss is not appreciably affected. Discharge tests with constant current and interruptions reinforce the idea that the structure can be positively modified to increase electrochemical performance.