Synthesis, characterization and fuel cell test of sepiyolite and kaolinite added sulfonated poly (ether ether ketone) composite membrane


Thesis Type: Postgraduate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2017

Student: AYGÜN ÇALI

Consultant: İRFAN AR

Abstract:

Fuel cells are one of the most important technologies that are used in alternative energy production. Fuel cells are devices that use sources like hydrogen and convert chemical energy directly to the electrical energy. Proton exchange membrane fuel cells (PEMFC) are known for their quick start-up, high productivity, low investment cost and enviroment friendly. In this study, the aim is to synthesise an alternative membrane to commercial membranes like Nafion in order to use in PEMFC. As a result of the researches, poly-ether-ether-ketone (PEEK) polymer was selected as membrane structure due to its high proton conductivity, thermal stability and mechanical stability. Since the sulfonation of the PEEK polymer increases the proton conductivity of the membrane, the polymer was sulfonated before the membrane synthesis. The classic casting method was selected as membrane synthesis method, and sepiyolite and kaolinite additives were added to the membrane in different ratios (w/w). On the purpose of increasing the thermal stability of the membranes, thermal crosslinking procedure was applied. Characterization methods such as water uptake capacity, swelling property, ion exchange capacity, FT-IR analysis, mechanical stability, thermal stability, electrochemical empedance measurement and fuel cell performance tests were carried out. According to the thermal gravimetric analysis results, it was observed that the sepiolite and kaolinite additives increased the thermal stability of the sulfonated poly-ether-ether-ketone (SPEEK) membrane. Proton conductivity of the sepiolite and kaolinite added SPEEK membranes increased with increasing temperature and the highest proton conductivity at 80 °C was calculated as 0,56 S/cm (SPEEK/K9). The ion exchange capacity of the SPEEK/K9 membrane was measured as 0,02 meq/g and its water uptake was calculated as 3,98%.