Anion Exchange Membrane Electrolyzers Showing 1 A/cm2 at Less Than 2 V

Abstract

This paper will describe the performance of alkaline water electrolyzers using newly developed Sustainion™-X5 membranes. Sustainion™ membranes have a styrene base, and mixtures of other components to produce a high conductivity in alkaline systems. The membranes are stable when soaked in 1 M KOH at room temperature for months. A CO2electrolyzer has run for over 4000 hours with no loss in performance. Initial tests also show stability in 1 M KOH at 60°C, See Figure 1, although no long term tests have yet been completed. The work here considers the performance of the membranes in model alkaline membrane electrolyzers. We manufactured a small MEA using platinum coated carbon paper as a cathode and a IrO2 coated carbon paper as an anode and a Sustainion™-X5 membrane. The MEA was mounted into Fuel Cell Technologies 5 cm² cell hardware with carbon flowfields. The cell was heated to 60 °C and 1 M KOH was fed into the anode and cathode. Figure 2 shows how the cell voltage varied with time at a fixed current of 0.8 A/cm² and 1 A/cm². The data were taken on a single cell, at a fixed current of 1 A/cm² during the day and 0.8 A/cm² at night. Initially the cell produced 0.8 A/cm² at 1.74 V and 1 A/cm² at 1.81 V, but the voltage rose to nearly 2V after 150 hours of operation. Disassembly of the cell showed that the carbon paper on the anode was corroding leading to a loss of anode catalyst. We have also started work on nickel catalysts. The initial results were modest, but additional results will be presented at the meeting. Acknowledgement Parts of this work were supported by ARPA-E under contract DE-AR0000684 and by 3M. The opinions here are those of the authors and may not reflect the opinions of ARPA-E or 3M. Figure 1