Performance Enhancement of Alkaline Direct Methanol Fuel Cells by Ni/Al Layered Double Hydroxides

Abstract

This paper reports the results of fuel cell performance tests detailing the effects of Ni/Al layered double hydroxide (Ni-LDH) on the performance of alkaline direct methanol fuel cells (DMFCs). It is desirable to enhance the maximum rate of methanol consumption at a fuel cell’s anode so that expensive bimetallic catalysts (such as Pt-Ru) would not be as essential to remedy the well-known sluggish kinetics and Pt catalyst deactivation tendencies of DMFCs. The test cells were constructed using partially hydrolyzed polyvinyl alcohol film membranes impregnated with a 10 M potassium hydroxide electrolyte. The cells were tested at a constant temperature of 40°C, and the effect of the addition of Ni-LDH to the membrane surface was studied by comparison of fuel cell polarization and power production curves of cells with Pt or Pt-Ru anodes paired with Pt cathodes. The benefits of Ni-LDH addition to DMFCs are clearly shown vis-à-vis the extended operating current densities and associated increases in power density for each catalyst type. The enhancement effect of Ni-LDH appears largely as enhancement of cell mass transport. Cells constructed with Pt anodes and membrane surfaces modified by Ni-LDH perform very nearly as well as Ni-LDH-free cells using bimetallic Pt-Ru anodes.