Environmental monitoring at the Lawrence Livermore National Laboratory. 1985 annual report

Griggs, K.S.; Buddemeier, Robert W.

doi:10.2172/5624524

Cited by 1 publication

(1 citation statement)

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“…Perry et al 45 suggest a diagnostic tool for PEFC that exploits the region of the Tafel plot where the slope is double that of the Tafel slope. Based on mathematical derivations, 52,53 models 45,46 and experiments, 47,[53][54][55] it has been concluded that losses contributing to the double Tafel slope region are a compounded effect of the kinetics of the electrode (single Tafel slope) plus another source of loss, namely, either oxygen transport or ionic transport. In both of these limiting cases, the current is dependent on the oxygen concentration.…”

Section: Resultsmentioning

confidence: 99%

Laser Modified Fuel Cell Diffusion Media: Engineering Enhanced Performance via Localized Water Redistribution

Manahan¹,

Clement²,

Srouji³

et al. 2014

J. Electrochem. Soc.

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The present work demonstrates an innovative concept of obtaining enhanced performance via laser treatment of the cathode-side diffusion medium (DM) while mitigating identified degradation modes. A diffusion medium was modified such that hydrophilic heat affected zones (HAZ) were introduced, which led to localized water redistribution. However, no perforation was created, thus mitigating accelerated degradation of the catalyst layer and diffusion medium. This material was compared to a diffusion medium with 100-μm diameter perforations that contained heat affected zones surrounding the perforations. In-situ net water drag experiments indicate that at low humidity and low-to-moderate current densities, a non-perforated microporous layer (MPL) forces more water to back diffuse from the cathode to the anode. However, when more water is produced at higher currents or the inlet streams are close to saturation, the non-perforated MPL acts as a barrier to prevent liquid water in the cathode DM from moving toward the anode. Furthermore, a computational model showed that the thermal gradients introduced as a result of the perforations can significantly change the water transport, particularly due to phase-change induced flow. This work adds understanding to the role of the MPL and the laser-induced heat affected zones in polymer electrolyte fuel cell performance.

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