On improving the corrosion and growth resistance of positive Pb-acid battery grids by grain boundary engineering

A frequent failure mode of Starting–Lighting–Ignition (SLI) and other lead-acid batteries relates to weight loss and growth of positive electrode grids, arising from intergranular corrosion/cracking and creep. The present investigation examines the impact of increasing the frequency of grain boundaries having low-Σ misorientations (Σ≤29), described by the Coincident Site Lattice (CSL) model. Such grain boundaries are known to be resistant to intergranular degradation phenomena. Electrode microstructures of various PbCaSn alloys processed to contain frequencies of special boundaries in excess of 50% exhibited significant reductions in weight loss and grid growth relative to both cast and rolled grid products. Modifying the crystallographic structure of grain boundaries in Pb alloy battery grids thus provides an opportunity for extending the service life and/or minimizing grid thicknesses (weight) and hence, material costs in battery production.