Non-destructive analysis of Pb-acid battery positive plates, based on neutron tomography

Abstract

Abstract Notwithstanding the in-depth understanding of lead-acid battery degradation processes developed in a time-honoured field of science, there is still wide scope for knowledge-based technological advancements, in particular, targeting positive plate durability. Non-destructive imaging of the internal morphology, structure and chemistry of these components, enabled by neutron-based methods, is capable of disclosing otherwise inaccessible observables, that can form the factual basis for new pathways to device improvement. In this study, we propose a post mortem investigation of as-formed and electrochemically aged positive plates (PP), centered on neutron tomography and complemented by X-ray radiography and scanning-electron microscopy. These complementary imaging methods, thriving on different contrast mechanisms, allow 2D/3D position-sensitive morphological analyses of the nature and evolution of the positive active material (PAM) and of the spines of the PP, including: morphology variation, crack location, porosity distribution and identification of hydrogenated compounds. Specifically, in this work, we have pinpointed the differences in degradation modes - resulting from the application of a standard ageing protocol - of positive plates fabricated in two technologically alternative ways: punching and gravity-casting, showing the superiority of the formed in terms of electrode stability upon charging abuse conditions.