Design of High-Ionic Conductivity Electrodes for Direct Methanol Fuel Cells

Abstract

Axiomatic Design Theory is used to analyze the design of conventional DMFC anodes. The difficulty conventional electrode design have satisfying the requirements for ionic conductivity in the anode are shown to lead to functional coupling, and therefore, an inability to meet performance requirements. A new anode design is proposed using embossed ionically conductive channels through the thickness of the electrode. Numerical simulation of the proposed design indicates that ionic resistance is greatly reduced and, crucially, no longer a function of catalyst loading. Electrodes are fabricated with 75 μm diameter posts spaced 175 μm apart. These electrodes are tested with impedance spectroscopy and show a 46% reduction in ionic resistance and a 6% increase in catalyst area available. Cell power is estimated to increase by 4% with the current post geometry, while ideal geometry may be able to deliver 9% power improvement.

Establishment and simulation of an electrode averaged model for a lithium-ion battery based on kinetic reactions

“…The common understanding of the Randles model is that the Warburg element represents diffusion dynamics, and the resistor represents pure ohmic resistance, while the RC component represents double layer effects. [8][9][10] However, equivalent circuit models use circuit elements to mimic the behavior of batteries 11 and have limited prediction capabilities compared to the mechanism-based pseudo 2dimensional (P2D) model proposed by Newman and Doyle et al 12 which includes diffusion, intercalation, and electrochemical kinetics based on the concentrated solution theory combined with the porous electrode theory. 13 This model involves coupled nonlinear partial differential equations (PDEs) across two spatial dimensions, 14,15 so it is time consuming to solve.…”