Research on thin film characteristics and adhesion energy of fuel cells

Abstract

In this thesis, there are total two topics on the major fields of fuel cell. On the first topic, the surface morphology evolutions of low temperature SOFC were directly observed by delamination. Until recently, only top surfaces of SOFC’s electrode were observed. However, on this thesis, clear interfacial delamination between SOFC’s electrode and substrate was achieved and its surface morphology changes due to different annealing temperatures were investigated. Contrary to current assumption, the top surface of electrode’s morphology is different to that of interfacial surface. Also, as the annealing temperature increased, electrode grains merged together. By investigating the surface morphology evolution, triple-phase-boundary (TPB) density changes were measured quantitatively. For the second topic, adhesion measurements of PEMFC’s thin film structures (MEA and GDL) were investigated. Also, in this topic, standard methods, such as choosing correct substrate, adhesive, and curing conditions, for adhesion measurement of MEA and GDL were studied. Successful adhesion measurement of MEA-1 was achieved. However, adhesion measurement of MEA-2 was futile, highlighting the fact that more works are needed for standard methods of measuring adhesion for MEA. While investigating the adhesion energy vales for GDL, influences of following factors were researched: content of hydrophobic agents in micro-porous substrate (MPS), type of MPS, and type of micro-porous layer (MPL). The adhesion measurement of GDL showed that as the content of hydrophobic increased, the adhesion energy increased also. For the type of MPS, GDL with carbon fiber paper as MPS resulted in higher adhesion than that of GDL using carbon fiber felt. Finally, smooth type MPL showed higher adhesion than rough type MPL.