FeCr gas diffusion layer with surface modification for fuel processing in direct-methane solid oxide fuel cells

Abstract

A solid oxide fuel cell (SOFC) with an Ni-YSZ anode was tested both without and with porous FeCr disk as a gas diffusion layer (GDL) under direct methane feeding. The surface of GDL was modified by coating with YSZ or Ni-YSZ powders. When gold mesh was used as the current collector, the performance of the direct-methane SOFC degraded very quickly. When FeCr GDL was used as the current collector over the anode, the performance became better and stable. Surface modification of GDL increased the current density. Both in GDL and over the anode, the major methane reaction was CH 4 dissociation, which yielded C species. The C species produced in GDL can be removed via gasification by carbon dioxide that forms over the anode. The formation of CO 2 can become the major reaction in the GDL of FeCr + YSZ while that of CO is the major reaction in the GDL of either FeCr or FeCr + Ni-YSZ. The electrochemical oxidation of CO formed in GDL increases the current density. The electrochemical promotion of lattice-oxygen extraction promotes the oxidation of CO and C species over the anode.