Effect of hydrophilic SiO2 additive in cathode catalyst layers on proton exchange membrane fuel cells

Hydrophilic nanosized SiO2 and sulfonated SiO2 particles were added to the cathode catalyst layer (CL) to improve the water wettability and the performance of a proton exchange membrane fuel cell (PEMFC) at low humidity. It was found that both nanosized SiO2 and sulfonated SiO2 additive improved the hydrophilicity of the cathode CL by the contact angle measurement. Contrary to nanosized SiO2, sulfonated SiO2 improved the conductivity of the cathode CL. Increased wettability of the cathode CL from SiO2 maintained fuel cell at hydration conditions. This phenomenon had a profound influence on electrode performance at low humidity. Since the sulfonic groups in sulfonated SiO2 improved the proton conductivity of the cathode CL, the cell with sulfonated SiO2 showed better performance.