Date of Completion

8-24-2011

Embargo Period

2-14-2012

Open Access

Campus Access

Abstract

Cationic contamination degrades polymer electrolyte membrane fuel cell

(PEMFC) performance by decreasing proton conductivity and water content in

perfluorosulfonic membranes such as Nafion. Hydration of the membrane is important

for cell durability and longevity; low relative humidity accelerates membrane

degradation. Cations can exchange with the proton on the sulfonate group in the polymer

and modify exchange site properties.

In an effort to build upon the existing knowledge of polymer electrolyte

membrane fuel cell (PEMFC) contamination effects, characterization of Nafion 117 and

212 in proton and sodium form has been performed. An emphasis has been placed on

sodium because it is found in close proximity to automobiles on roads and marine

environments, and in large enough quantities to potentially contaminate membrane

materials. High diffusivity, thermal stability, and existing research make sodium an

important cation. Cations Li+, K+, Cs+, Ca2+, Ni2+, and Cr3+ have been studied for

comparison. Virgin and used gas diffusion layer (GDL), catalyst coated membrane

(CCM), and uncatalyzed membrane (UCM) materials were examined to aid in single cell

post-test characterization where separation of materials is difficult and may alter results.

Through thermal analysis, FTIR, and vapor sorption the study shows how

membranes of salt form differ in water content, freezable water, water cluster structure,

water diffusion, and decomposition. Membranes of varying thickness in acid and sodium

form have been tested in vapor sorption and FTIR for comparison.

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