Production and Characterization of Pb-Carbon Composite for Manufacturing Metal Grids Applied in Lead-Acid Batteries

For decades, lead-acid batteries have been supplying power to electrical systems through redox reactions involving Pb and PbO₂. However, the energy supply capacity is inherently constrained by low energy density and challenges associated with charge/discharge cycles. Studies have indicated that additions of C to the composition of the active mass improve the electrochemical properties of batteries. This work aims to produce, characterize the microstructure and evaluate the electrochemical properties of Pb-Carbon composites, comparing different types of C (graphite, graphene and xerogel). The samples were produced through powder metallurgy, pressed at 550 MPa and sintered at 320°C-48 h. The microstructure was characterized by XRD, SEM/EDS, and Vickers microhardness. Electrochemical analyses were evaluated through OCP, polarization, and cyclic voltammetry (CV) measurements in a solution of 4.91 mol•L^-1 of H₂SO₄. Microstructural characterizations revealed dispersions of C particles in the Pb matrix and an increase in the microhardness of the composites. Electrochemical analyses showed an increase in polarization resistance and a reduction in the corrosion rate compared to Pb. CV curves, demonstrated that C particles enhanced electrical conductivity for the formation of PbSO₄ and PbO₂, allowing greater absorption of electrical overpotentials when compared to Pb, thereby improving charge/discharge cycles in positive grids.

Keywords:
Powder Metallurgy; Pb Carbon Composites; Microstructural characterization; Electrochemical characterization