Characteristics of methyl cellulose-NH₄NO₃-PEG electrolyte and application in fuel cells

Abstract

We report the viability of methyl cellulose (MC) as a membrane in a polymer electrolyte membrane fuel cell (PEMFC). Methyl cellulose serves as the polymer host, ammonium nitrate (NH₄NO₃) as the doping salt and poly(ethylene glycol) (PEG) as plasticizer. Conductivity measurement was carried out using electrochemical impedance spectroscopy. The room temperature conductivity of pure MC film is $\left( {{3}.0{8}\pm 0.{63}} \right) \times {1}{0^{ - {11}}}{\hbox{S}}\,{\hbox{c}}{{\hbox{m}}^{ - {1}}}$. The conductivity increased to $\left( {{2}.{1}0\pm 0.{37}} \right) \times {1}{0^{ - {6}}}{\hbox{S}}\,{\hbox{c}}{{\hbox{m}}^{ - {1}}}$ on addition of 25 wt.% NH₄NO₃. By adding 15 wt.% of PEG 200 to the highest conducting sample in the MC-NH₄NO₃ system, the conductivity was further raised by two orders of magnitude to $\left( {{1}.{14}\pm 0.{37}} \right) \times {1}{0^{ - {4}}}{\hbox{S}}\,{\hbox{c}}{{\hbox{m}}^{ - {1}}}$. The highest conducting sample containing 15 wt.% PEG was used as membrane in PEMFC and was operated at room and elevated temperatures. From voltage-current density characteristics, the short circuit current density was 31.52 mA cm⁻² at room temperature (25 °C).