Assembling nanostructured materials into rationally designed mesoscale arrays for use as electrodes in electrochemical systems is anticipated to reveal new challenges, particularly concerning new synthesis modes, architecture-related performance limitations, and degradation mechanisms. In this work, we focus on characterizing the degradation of densely packed vertically aligned carbon nanotubes (VACNTs) grown directly on a metallic foam to form a self-supporting, hierarchically porous 3D electrode architecture with an integrated current collector. The degradation pathways of this electrode, observed with microscopy and semi in-situ XPS after cycling as a redox scaffold in aprotic Li-O-2 and Li-S batteries, shed new light on important design, performance, and degradation considerations for integrated mesoscale electrode architectures. (C) 2015 The Electrochemical Society.