scholarly journals Comprehensive characterization and understanding of micro-fuel cells operating at high methanol concentrations

2015 ◽  
Vol 6 ◽  
pp. 2000-2006 ◽  
Author(s):  
Aldo S Gago ◽  
Juan-Pablo Esquivel ◽  
Neus Sabaté ◽  
Joaquín Santander ◽  
Nicolas Alonso-Vante
Keyword(s):  
Mass Transport ◽  
Direct Methanol Fuel Cell ◽  
Open Circuit Potential ◽  
Reference Electrode ◽  
Open Circuit ◽  
Cathode Potential ◽  
Direct Methanol ◽  
Transport Problems ◽  
Methanol Fuel Cell ◽  
Comprehensive Characterization

We report on the analysis of the performance of each electrode of an air-breathing passive micro-direct methanol fuel cell (µDMFC) during polarization, stabilization and discharge, with CH3OH (2–20 M). A reference electrode with a microcapillary was used for separately measuring the anode the cathode potential. Information about the open circuit potential (OCP), the voltage and the mass transport related phenomena are available. Using 2 M CH3OH, the anode showed mass transport problems. With 4 and 6 M CH3OH both electrodes experience this situation, whereas with 10 and 20 M CH3OH the issue is attributed to the cathode. The stabilization and fuel consumption time depends mainly on the cathode performance, which is very sensitive to fuel crossover. The exposure to 20 M CH3OH produced a loss in performance of more than 75% of the highest power density (16.3 mW·cm−2).

A Model of a High-Temperature Direct Methanol Fuel Cell

2013 ◽  
Vol 10 (5) ◽  
Author(s):  
K. Scott ◽  
S. Pilditch ◽  
M. Mamlouk
Keyword(s):  
Fuel Cell ◽  
Direct Methanol Fuel Cell ◽  
Proton Exchange Membrane ◽  
Open Circuit ◽  
Proton Exchange ◽  
Cell Performance ◽  
Effect Of Temperature ◽  
Fuel Cell Performance ◽  
Direct Methanol ◽  
Methanol Fuel Cell

A steady-state, isothermal, one-dimensional model of a direct methanol proton exchange membrane fuel cell (PEMFC), with a polybenzimidazole (PBI) membrane, was developed. The electrode kinetics were represented by the Butler–Volmer equation, mass transport was described by the multicomponent Stefan–Maxwell equations and Darcy's law, and the ionic and electronic resistances described by Ohm's law. The model incorporated the effects of temperature and pressure on the open circuit potential, the exchange current density, and diffusion coefficients, together with the effect of water transport across the membrane on the conductivity of the PBI membrane. The influence of methanol crossover on the cathode polarization is included in the model. The polarization curves predicted by the model were validated against experimental data for a direct methanol fuel cell (DMFC) operating in the temperature range of 125–175 °C. There was good agreement between experimental and model data for the effect of temperature and oxygen/air pressure on cell performance. The fuel cell performance was relatively poor, at only 16 mW cm−2 peak power density using low concentrations of methanol in the vapor phase.

Mass transport of direct methanol fuel cell species in sulfonated poly(ether ether ketone) membranes

2006 ◽  
Vol 51 (18) ◽  
pp. 3699-3706 ◽  
Author(s):  
V.S. Silva ◽  
B. Ruffmann ◽  
S. Vetter ◽  
M. Boaventura ◽  
A.M. Mendes ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Mass Transport ◽  
Direct Methanol Fuel Cell ◽  
Ether Ether Ketone ◽  
Poly Ether Ether Ketone ◽  
Direct Methanol ◽  
Ether Ketone ◽  
Methanol Fuel Cell ◽  
Sulfonated Poly

Improved Electrocatalytic Activity of Oxygen Reduction on Platinum Using Nano-Cobalt in Direct Methanol Fuel Cell Cathode Electrodes

2006 ◽  
Author(s):  
Kimberly McGrath ◽  
Douglas Carpenter
Keyword(s):  
Fuel Cell ◽  
Oxygen Reduction ◽  
Electrocatalytic Activity ◽  
Direct Methanol Fuel Cell ◽  
High Surface ◽  
High Surface Area ◽  
Reduction Reaction ◽  
Open Circuit ◽  
Direct Methanol ◽  
Methanol Fuel Cell

High surface area nanometal particles of nano-cobalt (n-Co) (approx 8 nm particles), produced at QuantumSphere Inc., were blended in various ratios with Pt and Nafion® ionomer, and investigated for their electrocatalytic activity in the oxygen reduction reaction (ORR). The ORR was evaluated by voltammetry using Pt/n-Co blended catalyst on glassy carbon to determine both kinetic activity and as an indicator of direct methanol fuel cell (DMFC) cathode performance. Kinetic enhancement was observed for Pt:n-Co where n-Co is 30–50% (by weight) of the catalyst mixture, including a minimum of 10 mV improvement in the open circuit voltage (OCV). By Tafel slope measurements, it is clear that the mechanism for ORR does not change, however the reaction rate is enhanced by addition of n-Co to Pt in the catalytic ink. For ink compositions similar to those used for standard DMFC cathodes, eliminating 50% of the Pt black resulting in 50% higher energy density while reducing total catalyst cost by roughly 44%.

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