3D Imaging of Fuel Cell Electrode Structure Degraded under Cell Voltage Reversal Conditions Using Nanoscale X-Ray Computed Tomography

Abstract

A challenge faced by polymer electrolyte fuel cells for transportation applications is hydrogen starvation at the anode that can arise from a variety of sources such as water flooding, ice formation, foreign impurities, etc., which typically causes cell voltage reversals through water electrolysis and carbon corrosion at high anode potentials. Here we present electrochemical diagnostics and nano-scale X-ray computed tomography (nano-CT) of fuel cell electrodes with Pt/C catalysts degraded under cell voltage reversal conditions. It is found that the cell performance decreases and Ohmic resistance increases significantly after reversal tests. Anode cyclic voltammetry indicates new peaks due to severe carbon corrosion. Nano-CT imaging of the internal structure reveals that the thickness of the anode is reduced by approximately 40 % after the reversal tests, but the interface between the membrane and electrode appears mostly intact over the interfacial area even after the cell voltage reversals.