Particle Population Dynamics of Catalyst-Layer Degradation Induced by Carbon Support Corrosion in Proton Exchange Membrane Fuel Cells

Abstract

Carbon support corrosion limits the long-term durability of proton exchange membrane fuel cells (PEMFCs). The statistical characteristics of catalyst layer (CL) degradation are investigated by combining small-angle neutron scattering (SANS) experiments with a population balance model. Five membrane electrode assembly samples were subjected to accelerated stress tests involving triangular-wave voltage cycling between 1.0 V and 1.5 V at a scan rate of 0.5 V·s-1 for different durations. SANS results show that the particle size distribution (PSD) curve of carbon support first shits toward larger sizes and then toward smaller sizes. A critical change in structural degradation pattern after 1000 cycles was identified by comparing the slope values of carbon particle radius, primary pore radius and ionomer film thickness curves. Based on variations in CL structure and electrochemical performance, a new three-stage degradation mechanism for CL is proposed. The population balance model reveals that initial distribution parameters and electrode potential dominate the particle degradation kinetics, thereby providing a new tool for the development of high-durability PEMFCs.