In-Depth Understanding of Oxygen Transfer in the Catalyst Layer of  High-Temperature Proton Exchange Membrane Fuel Cells

Abstract

The mass transport of oxygen in the cathode catalyst layer of high-temperature proton exchange membrane fuel cells (HT-PEMFCs) has a great impact on cell performance. However, some bulk average methods are unable to study the permeation properties of oxygen near the triple phase boundary of HT-PEMFCs due to the size mismatch. Here, we developed a microelectrode integrated system to quantitatively study the O2 mass transport behavior at the Pt/ binder interface under actual operating temperatures (100-180 °C). The oxygen diffusion coefficients and solubility obtained from potential-step chronoamperometry and a modified Cottrell equation follow the diffusion "ball-cage" model and the dual-mode solubility model. Subsequently, molecular dynamics simulations were used to describe the key structural elements and diffusion behavior of oxygen molecules from the microscopic perspective. These results provide a scientific approach to study the mass transfer process of oxygen at the local environment, endowing with insightful strategies for future improvement and applications of HT-PEMFCs.

Keywords: High-temperature proton exchange membrane fuel cells, oxygen mass transport, microelectrode, catalyst layer, Molecular dynamics