Effect of type and stoichiometry of fuels on performance of polybenzimidazole-based proton exchange membrane fuel cells operating at the temperature range of 120–160 °C

Abstract

Herein, a proton exchange membrane fuel cell (PEMFC) equipped with phosphoric acid-doped polybenzimidazole (PA-PBI) membrane was exploited to determine the effects of changing type and stoichiometry of feed gas at operating temperature from 120 to 160 °C. Results show that maximum power density of proposed system increases as increasing temperature, and varying the type and stoichiometry of feed gas. For example, a typical power density of 0.254, 0.299 and 0.389 W/cm2 was obtained when operating PEMFC at 120, 140 and 160 °C respectively with pure hydrogen (H2) as feed gas. By contrast, power density of only 0.128, 0.194 and 0.243 W/cm2 was achieved when operating the PEMFC under identical condition with reformed H2 as feed gas. On the other hand, when varying oxygen (O2) stoichiometry from 2 to 6, power density of PEMFC vary from 0.330 to 0.472 W/cm2 at 160 °C. At high temperature and high O2 diffusion rate, reaction kinetics of electrodes and membrane were boosted, resulting lower mass-transfer resistance and higher PEMFC performance. In addition, we conducted long-term operation of PEMFC at 160 °C for 500 h to examine durability of PA-PBI. PA-PBI membrane was not lose open circuit voltage (OCV) significantly, indicating its good PEMFC durability.