Covergence in a Calcium Microcosm

This composite SEM–BSE image captures the calcium metal counter electrode surface after stripping during the evaluation of emerging calcium battery technologies. Blue–green gradients indicate light elements (C, O, and F), while red denotes Ca. Two closely spaced pits appear to merge, forming a microcosmic convergence. This morphology reveals pronounced interfacial heterogeneity, challenging the common assumption of a homogeneous counter electrode.