Performance and Ethanol Crossover of Passive Direct Ethanol Fuel Cell Stack

Faculty of Science, Energy and Environment, King Mongkut’s University of Technology North Bangkok, Rayong Campus, Rayong, Thailand

^* Corresponding author: panuwat.e@sciee.kmutnb.ac.th

Abstract

A dual-cell passive direct ethanol fuel cell (DEFC) stack with single ethanol tank was designed and tested to obtain the voltage requirement of electronics and to reduce weight and volume for practical applications. Ethanol crossover and cell performance were determined at different ethanol feed concentrations. Characterization techniques were used, including a cell polarization tests, a long-term steady voltage discharging measurement, and an electrochemical impedance spectroscopy (EIS). It was found that, before long-term steady voltage test, the optimum ethanol feed concentration was 2 M. The ethanol crossover increases with ethanol concentration increment over 2 M and the ethanol crossover exhibited a negative effect on the open circuit voltage (OCV) and the cell performance. However, after a long-term steady voltage test, the best ethanol feed concentration was changed to 3 M. It was due to the difference of current density discharged during long-term operation. It can also be found that, after long-term steady voltage test, the cell resistance was apparently reduced. It may be explained that the mass transport of both liquid fuel and air as a reactant in the cell structure reached equilibrium during long-term operation.