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Improved Anode Two-Phase Mass Transfer Management of Direct Methanol Fuel Cell by the Application of Graphene Aerogel
journal contribution
posted on 2019-05-30, 00:00 authored by Weijian Yuan, Xuelin Zhang, Yufeng Zhang, Xiaowei LiuThe main purpose
of this paper is to utilize the intrinsic hydrophobicity
and microstructure of graphene aerogel to construct a novel anode
two-phase mass transfer structure for passive micro direct methanol
fuel cell. Compared with its traditional counterpart composed of carbon
black and poly(tetrafluoroethylene), the anode gas diffusion layer
based on graphene aerogel holds some greatly improved microstructures,
which contributes to an excellent gas–liquid mass transfer
management. During discharge, smaller, more evenly distributed bubbles
of CO2 fill in the pores of the three-dimensional structure
of graphene aerogel and form a convection in the opposite direction
of methanol transport, increasing the mass transfer resistance of
methanol without causing a loss of effective reaction area. A methanol
crossover test system is specifically designed to verify the effect
of CO2 on reducing methanol crossover under operation.
As a result, an increase of more than 20% in the output power density
and a significant increase of the operating methanol concentration
are achieved without additional structures. Moreover, the energy density
of the micro direct methanol fuel cell with the novel anode gas diffusion
layer is almost 3 times that of the one with commercial gas diffusion
layer, which greatly enhances its utility in portable devices.