Development of a kilowatt class PEMFC stack using Au-coated LF11 Al alloy bipolar plates

Abstract

Investigations on alternative material for bipolar plates of PEMFC (polymer electrolyte membrane fuel cell) are becoming a research hotspot for many fuel cell researchers. In this paper, LF11 Al alloy bipolar plates via a surface plasma Au plating preparation were applied as bipolar plates. Performances and duration times of PEMFC single cells using graphite; Au-coated LF11 Al bipolar (ALABP) and Au-coated 316L stainless steel plates were compared. It was shown that ALABP exhibited preferable properties. Based on the preparations illustrated above, a kilowatt class proton exchange membrane fuel cell stack consisting of 30 cells was successfully assembled. Pure hydrogen and air were used as the fuel and oxidant, respectively, in the stack. External humidification was employed and cycle cooling water was used to remove the heat from the reaction in order to maintain a constant temperature. A Nafion 1135 membrane and Johnson-Matthy platinum on carbon with a Pt loading of 0.4 mg/cm2 were adopted as the electrolyte and catalyst, respectively. The working temperature of the stack ranged from 25 to 100°C. The stack typically worked well under conditions in which the pressure ratio of H2/air was 0.2/0.22 MPa. The output power, current and voltage were 1–1.3 kW, 40–80 A, and 26–20 V, respectively. The normal current density of the electrode was 200–800 mA/cm2, and the energy efficiency of the stack was 51%.