Experimental Evaluation of the Effect of the Anode Diffusion Layer Properties on the Performance of a Passive Direct Methanol Fuel Cell

Beatriz A Braz,Vânia B Oliveira,Alexandra M F R Pinto

doi:10.3390/en13195198

Abstract

Passive direct methanol fuel cells (pDMFCs) are promising devices to replace the conventional batteries in portable electronic devices, due to their higher energy densities, autonomies, and instant recharging. However, some challenges, such as their costs, efficiency, and durability, need to be overcome before their commercialization. Towards that, this work presents the effect of the anode diffusion layer (ADL) properties on the performance of a pDMFC using a membrane electrode assembly (MEA) with reduced loadings on both anode and cathode catalysts (3 mg/cm2 Pt/Ru on the anode and 1.3 mg/cm2 of Pt on the cathode). The pDMFC behavior was evaluated through polarization and electrochemical impedance spectroscopy measurements, which allow identifying and quantifying the different losses that affect these systems. The results showed better performances when a diffusion layer with a dual-layer structure was used using higher methanol concentrations. The maximum power density achieved was 3.00 mW/cm2, using carbon cloth with a microporous layer, CC_MPL, as ADL, and a methanol concentration of 5 M. In this work, a tailored and low-cost MEA, using the materials available in the market, was proposed to achieve higher performances working under higher methanol concentrations. This work demonstrates that performing modifications on the fuel cell structure/design is an efficient way to achieve optimized performances.

Highlights

IntroductionIn emerging countries and rural areas where the grids are unreliable, small and decentralized power systems are seen as a promising power solution to provide the power needed by the population
In emerging countries and rural areas where the grids are unreliable, small and decentralized power systems are seen as a promising power solution to provide the power needed by the population.Among these systems, fuel cells (FCs) are in the Energy Agenda since were target as the ideal technology to provide power to education, auxiliary and back-up power systems, recreational, medical, and military applications
Compact and small FCs, which use methanol as fuel, known as direct methanol fuel cells (DMFCs), emerge as a promising solution to develop advanced small and portable FCs to overcome the limitations of the conventional batteries, providing back-up and small-decentralized power

Summary

Introduction

In emerging countries and rural areas where the grids are unreliable, small and decentralized power systems are seen as a promising power solution to provide the power needed by the population Among these systems, fuel cells (FCs) are in the Energy Agenda since were target as the ideal technology to provide power to education, auxiliary and back-up power systems, recreational, medical, and military applications. A passive DMFC produces electricity without power consumption, since uses natural forces, such as diffusion and convection to achieve all the processes that occur in a working fuel cell. These systems are simpler and more compact being for these reasons more suitable for providing energy for portable and small power sources. Significant efforts should be done towards its commercialization in order to overcome its different scientific challenges, which include its higher costs, due to the use of noble metals as catalysts with higher loadings (usually, 4 mg/cm Pt/Ru and 4 mg/cm of Pt), and lower power outputs, due to the Energies 2020, 13, 5198; doi:10.3390/en13195198 www.mdpi.com/journal/energies

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