  Correlating the microstructure of an energy conversion device to its
performance is often a complex exercise, notably in solid oxide fuel cell
(SOFC) research. SOFCs combine multiple materials and interfaces that evolve in
time due to high operating temperatures and reactive atmospheres. We
demonstrate here that operando environmental transmission electron microscopy
can simplify the identification of structure-property links in such systems. By
contacting a cathode-electrolyte-anode cell to a heating and biasing
microelectromechanical system in a single-chamber configuration, a direct
correlation is found between the environmental conditions (O2 and H2 partial
pressures, temperature), the cell voltage, and the microstructural evolution of
the fuel cell, down to the atomic scale. The results shed new insights into the
impact of the anode oxidation state and its morphology on the cell electrical
properties.
