Ameliorating effect of silica addition in the anode-catalyst layer of the membrane electrode assemblies for polymer electrolyte fuel cells |
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Authors: | A K Sahu G Selvarani S Pitchumani P Sridhar A K Shukla |
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Affiliation: | (1) Central Electrochemical Research Institute, Karaikudi, 630 006, India;(2) Solid state and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560 012, India |
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Abstract: | Incorporation of silica particles through a sol-gel process into the anode-catalyst layer with a sol-gel modified Nafion-silica
composite membrane renders easy retention of back-diffused water from the cathode to anode through the composite membrane
electrolyte, increases the catalyst-layer wettability and improves the performance of the Polymer Electrolyte Fuel Cell (PEFC)
while operating under relative humidity (RH) values ranging between 18% and 100% with gaseous hydrogen and oxygen reactants
at atmospheric pressure. A peak power density of 300 mW cm−2 is achieved at a load current-density value of 1200 mA cm−2 for the PEFC employing a sol-gel modified Nafion-silica composite membrane and operating at 18% RH. Under similar operating
conditions, the PEFC with a Membrane Electrode Assembly (MEA) comprising Nafion-silica composite membrane with silica in the
anode-catalyst layer delivers a peak power density of 375 mW cm−2. By comparison, the PEFC employing commercial Nafion membrane fails to deliver satisfactory performance at 18% RH due to
the limited availability of water at its anode, acerbated electro-osmotic drag of water from anode to cathode and insufficient
water back diffusion from cathode to anode causing the MEA to dehydrate. |
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Keywords: | Polymer electrolyte fuel cell Silica-Nafion composite membrane Wettability Humidification Anode-catalyst layer |
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