Details
| Original language | English |
|---|---|
| Pages (from-to) | 545-552 |
| Number of pages | 8 |
| Journal | Electrochimica acta |
| Volume | 212 |
| Early online date | 12 Jul 2016 |
| Publication status | Published - 10 Sept 2016 |
Abstract
Proton exchange membrane fuel cells fed with H2/CO mixtures at the anode have a considerably lower performance than fuel cells fed with pure hydrogen. However, when operated in an autonomous oscillatory regime, the overall voltage loss decreases due to a self-cleaning mechanism. Another molecule, also widely used as feed in the fuel cell and susceptible to kinetic instabilities, is methanol. To the best of our knowledge, there are no reports on autonomous voltage oscillations in the direct methanol fuel cell (DMFC). The purpose of this work was to explore if such instabilities also occur in the DMFC system. Initially, half-cell experiments with a gas diffusion electrode were performed. Then, a DMFC was operated under current control and studied by means of electrochemical impedance spectroscopy. The half-cell measurements revealed that the induction period for oscillations depends on the mass transfer conditions, where on stagnant electrode the induction time was shorter than in the case of forced convection. The DMFC showed also autonomous voltage oscillations above a certain threshold current. The results obtained by electrochemical impedance spectroscopy give evidence of a negative differential resistance in the fuel cell, hitherto not described in the literature, which can be related to the appearance of oscillations during galvanostatic methanol electro-oxidation. These results open the possibility to evaluate the performance of low-temperature fuel cells fed with carbon-containing fuels under oscillatory operating conditions.
Keywords
- DMFC, electrocatalysis, fuel cells, methanol, oscillations
ASJC Scopus subject areas
- Chemical Engineering(all)
- Chemistry(all)
- Electrochemistry
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In: Electrochimica acta, Vol. 212, 10.09.2016, p. 545-552.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Autonomous Voltage Oscillations in a Direct Methanol Fuel Cell
AU - Nogueira, Jéssica A.
AU - Peña Arias, Ivonne K.
AU - Hanke-Rauschenbach, Richard
AU - Vidakovic-Koch, Tanja
AU - Varela, Hamilton
AU - Sundmacher, Kai
N1 - Funding information: J.A.N. and H.V. acknowledge São Paulo Research Foundation (FAPESP) for the scholarship (grant #2015/09295-9) and financial support (grants #2012/21204-0, and #2013/16930-7). J.A.N. acknowledges Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and the support by the Max Planck Society during her internship in Magdeburg , which enabled this cooperation. H.V. (#306151/2010-3) acknowledges Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for financial support. I.K.P.A and R.H.R. gratefully acknowledge financial support from Deutsche Forschungsgemeinschaft , Grant No. HA 6841/1-1 .
PY - 2016/9/10
Y1 - 2016/9/10
N2 - Proton exchange membrane fuel cells fed with H2/CO mixtures at the anode have a considerably lower performance than fuel cells fed with pure hydrogen. However, when operated in an autonomous oscillatory regime, the overall voltage loss decreases due to a self-cleaning mechanism. Another molecule, also widely used as feed in the fuel cell and susceptible to kinetic instabilities, is methanol. To the best of our knowledge, there are no reports on autonomous voltage oscillations in the direct methanol fuel cell (DMFC). The purpose of this work was to explore if such instabilities also occur in the DMFC system. Initially, half-cell experiments with a gas diffusion electrode were performed. Then, a DMFC was operated under current control and studied by means of electrochemical impedance spectroscopy. The half-cell measurements revealed that the induction period for oscillations depends on the mass transfer conditions, where on stagnant electrode the induction time was shorter than in the case of forced convection. The DMFC showed also autonomous voltage oscillations above a certain threshold current. The results obtained by electrochemical impedance spectroscopy give evidence of a negative differential resistance in the fuel cell, hitherto not described in the literature, which can be related to the appearance of oscillations during galvanostatic methanol electro-oxidation. These results open the possibility to evaluate the performance of low-temperature fuel cells fed with carbon-containing fuels under oscillatory operating conditions.
AB - Proton exchange membrane fuel cells fed with H2/CO mixtures at the anode have a considerably lower performance than fuel cells fed with pure hydrogen. However, when operated in an autonomous oscillatory regime, the overall voltage loss decreases due to a self-cleaning mechanism. Another molecule, also widely used as feed in the fuel cell and susceptible to kinetic instabilities, is methanol. To the best of our knowledge, there are no reports on autonomous voltage oscillations in the direct methanol fuel cell (DMFC). The purpose of this work was to explore if such instabilities also occur in the DMFC system. Initially, half-cell experiments with a gas diffusion electrode were performed. Then, a DMFC was operated under current control and studied by means of electrochemical impedance spectroscopy. The half-cell measurements revealed that the induction period for oscillations depends on the mass transfer conditions, where on stagnant electrode the induction time was shorter than in the case of forced convection. The DMFC showed also autonomous voltage oscillations above a certain threshold current. The results obtained by electrochemical impedance spectroscopy give evidence of a negative differential resistance in the fuel cell, hitherto not described in the literature, which can be related to the appearance of oscillations during galvanostatic methanol electro-oxidation. These results open the possibility to evaluate the performance of low-temperature fuel cells fed with carbon-containing fuels under oscillatory operating conditions.
KW - DMFC
KW - electrocatalysis
KW - fuel cells
KW - methanol
KW - oscillations
KW - FAFC
KW - Electrodissolution
KW - DMFC
KW - electrocatalysis
KW - fuel cell
KW - Methanol
KW - oscillations
UR - http://www.scopus.com/inward/record.url?scp=84978786387&partnerID=8YFLogxK
U2 - 10.1016/j.electacta.2016.07.050
DO - 10.1016/j.electacta.2016.07.050
M3 - Article
AN - SCOPUS:84978786387
VL - 212
SP - 545
EP - 552
JO - Electrochimica acta
JF - Electrochimica acta
SN - 0013-4686
ER -