Effects of channel geometry and electrode architecture on reactant transportation in membraneless microfluidic fuel cells: A review

초록

The review article introduces the development in membraneless microfluidic fuel cells (MMFCs) focusing on the microchannel geometry and electrode architecture and arrangement. Lamination of fuel and oxidant streams in a microchannel lets an MMFC work without physical membrane. The lack of convective mixing across liquid-liquid interface of two streams forms a distinct diffusive mixing region, which acts as a pseudo membrane. The ions can transport across the channel through the mixing region to reach the other side of the channel and complete the ionic conduction. The advantage of MMFCs lies in the absence of the membrane, as the problems associated with the membrane are eliminated. The channel geometry and electrode architecture have been investigated extensively to eliminate the problems caused by the mixing and depletion regions, which affect the performance significantly, such as power and current densities. The absence of instabilities due to the convective mass transer along the channel allows streams containing different substances with different concentrations to flow side by side axially through a microchannel, whereas the reactant's mass transfer across the channel in an MMFC is mainly diffusion-limited. This review article mostly focuses on how the channel and electrodes can be designed effectually to enhance the mass transfers by reducing mixing and depletion regions. Additionally, the current status of theoretical and computational modeling for MMFCs to improve the performance are discussed. Moreover, the key issues and main challenges for prospective development of MMFCs are presented.

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