Toward 100% fuel utilization in protonic ceramic fuel cells: modelling gas and current density distributions in a dead-end anode

Abstract

Reaching 100% fuel utilization in protonic ceramic fuel cells (PCFCs) is advantageous for developing compact systems but remains challenging due to high overpotentials and anode material degradation caused by oxidation under low H₂ partial pressure. We propose a dead-end anode design where the anode outlet is sealed, and a pre-filled H₂O-H₂ gas mixture ensures the required humidity for proton conductivity. The feasibility of 100% fuel utilization has been verified by a numerical model combining mass transfer (convection and diffusion) and charge transfer. Electrical performance is optimized by the pre-filled H₂O mole fraction, height and length of the anode channel. Increasing the anode channel height and reducing its length significantly enhance performance of the dead-end-anode type PCFC, enabling a comparable current density–voltage performance at 100% fuel utilization to that of a relatively small coin-type configuration operating at 3% fuel utilization. Moreover, the combined effects of convection and diffusion of H₂ and H₂O gases help stabilize the anode gas partial pressures, thereby suppressing excessive local overpotentials. These findings, along with discussions on PCFC designs and potential applications, provide valuable insights for developing high-performance PCFCs with 100% fuel utilization for compact systems.