Effect of temperature on the electrode reactions in a planar solid oxide fuel cell

Understanding the temperature dependence of electrode reactions is attempted with a commercial 100 cm² class planar solid oxide fuel cell. Experimental investigations are conducted using a specially designed setup, i.e., inert gas step addition (ISA) and reactant gas step addition (RA) methods, to measure the electrode overpotential behaviour at temperatures ranging from 923 to 1073 K. The ISA reveals that the gas-phase mass transfer resistance at the anode is more substantial and becomes immensely larger with increasing temperature due to the effect of pore diffusion resistance (PDR). On the other hand, the gas-phase mass transfer resistance of the cathode shows an unclear dependence on temperature, indicating little resistance in the cathode. The RA method represents that the H₂-inducing mass transfer resistance increases with increasing temperature due to the PDR effect, while the O₂-inducing mass transfer resistance decreases with increasing temperature because of the reducing solid-phase mass transfer resistance of oxide ions.