Investigation of GDL degradation behaviour by half cell tests

Kurzfassung

The objective of this work is to investigate the wettability of gas diffusion layers (GDL) by electrochemical tests and to analyse the change of hydrophobicity due to degradation effects. The common GDL consists of conductive, hydrophilic (coal) and non conductive, hydrophobic (PTFE) components. The change of the ratio of conductive to non conductive area, which can be measured by wetting with liquid electrolyte in an electrochemical measurement setup induces a change of the electrochemical double layer capacitance (Fig. 1). Therefore measurements were performed with five different GDLs to determine the double layer capacitances. Four GDL samples were pre-treated by exposure at defined time in an autoclave (Fig. 2) at 130°C in 1 N sulphuric acid to enforce a degradation effect. One untreated GDL sample was used as reference.