Measurement of methanol crossover in direct methanol fuel cell

Hikita, S.

doi:10.1016/s0389-4304(01)00086-8

Cited by 86 publications

(35 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Notably, the borohydride-crossover concentrations in DBFCs are much lower as compared to methanol-crossover concentrations reported for DMFCs. 34,35 The cell performance data at various temperatures with varying pH values of H 2 O 2 solution are shown in Fig. 3a-c.…”

Section: Resultsmentioning

confidence: 99%

A High Output Voltage Direct Borohydride Fuel Cell

Ramanujam¹,

Choudhury²,

Shukla³

2004

Electrochem. Solid-State Lett.

119

View full text Add to dashboard Cite

A direct borohydride fuel cell ͑DBFC͒ employing hydrogen peroxide as oxidant with a power density of about 350 mW cm Ϫ2 at the cell voltage of almost 1.2 V at 70°C is reported. The use of liquid reactants in DBFCs not only simplifies the engineering problems at the front end of the fuel cell, driving down complexity and hence cost, but operating a DBFC with an oxidant such as hydrogen peroxide also extends the operational environment for fuel cells to locations where free convection of air is limited, e.g., underwater applications. © 2004 The Electrochemical Society. ͓DOI: 10.1149/1.1817855͔ All rights reserved. Polymer electrolyte fuel cells ͑PEFCs͒ have advanced substantially but their successful commercialization is restricted owing to carbon monoxide poisoning of the anode while using a reformer with the PEFC, and hydrogen storage while using a directly-fueled PEFC.1-5 Therefore, certain hydrogen-carrying organic liquid-fuels, such as methanol, ethanol, propanol, ethylene glycol, and diethyl ether, have been considered for fuelling PEFCs directly.6 Among these, methanol, with a capacity value of 5.06 Ah/g and a hydrogen content of 12.8 wt %, is undisputedly the most attractive organicliquid fuel at present for directly-fueled PEFCs. Such fuel cells are referred to as direct methanol fuel cells ͑DMFCs͒.7-9 But DMFCs have limitations of low open-circuit-potential, low electrochemicalactivity, and methanol crossover. 4,10 An obvious solution to the aforesaid scientific problems is to explore other promising hydrogen-carrying liquid fuels such as sodium borohydride, [11][12][13][14][15][16][17][18] which has a capacity value of 5.67 Ah/g and a hydrogen content of about 11 wt %. Amendola et al. 14,15 were the first to propose an OH Ϫ -ion conducting anion exchange membranebased borohydride-air fuel cell with a power density close to 60 mW cm Ϫ2 at 70°C. However, the borohydride-air fuel cell due to Amendola et al. 14,15 suffers from borohydride crossover as the BH 4 Ϫ -ions can permeate through the anion exchange membrane. In additon, it would be mandatory to scrub CO 2 from air inlet of such a fuel cell to avoid carbonate fouling. Suda et al. [16][17][18][19] mitigated the BH 4 Ϫ crossover problem by adopting a fuel cell structure using Nafion membrane as electrolyte to separate the fuel from the cathode and were able to achieve a power density as high as 160 mW cm Ϫ2 at 70°C with such a fuel cell. But even in the borohydride-air fuel cell proposed by Suda et al., [16][17][18][19] it would be mandatory to scrub CO 2 from air both to avoid carbonate fouling as well as to prevent accumulation of alkali in the cathode pores to facilitate oxidant flux.In this paper, we report a DBFC using hydrogen peroxide as oxidant with a power density of about 350 mW cm Ϫ2 at a cell voltage of almost 1.2 V at 70°C. 20 In this fuel cell, sodium borohydride is oxidized at its anode according toAt the cathode of this DBFC, hydrogen peroxide is decomposed into oxygen and water at the catalyst/electrode interface 21 according toElectr...

show abstract

Section: Resultsmentioning

confidence: 99%

A High Output Voltage Direct Borohydride Fuel Cell

Ramanujam¹,

Choudhury²,

Shukla³

2004

Electrochem. Solid-State Lett.

119

View full text Add to dashboard Cite

show abstract

“…The methanol concentration can be expressed as eq. (4) as a function of time (4) where C A0 is the initial concentration of methanol, L membrane thickness, S surface area, and V B the volume of deionized water bath. Methanol diffusivity and sorption coefficient of the membrane are denoted as D and K, respectively.…”

Section: Characterizationmentioning

confidence: 99%

“…3 Methanol crossover induces an unexpected drop in the open circuit voltage and therefore the overall efficiency of the system decreases. 4 Various solutions to these problems have been proposed, such as synthesis of cost-effective alternative polymers 5-10 and blending of organic-inorganic compounds or acid-doped polymers. [11][12][13][14][15] However, they fail to adequately mitigate loss in the proton conductivity when the methanol permeability is reduced.…”

Section: Introductionmentioning

confidence: 99%

Transport properties of polymer blend membranes of sulfonated and nonsulfonated polysulfones for direct methanol fuel cell application

Kim

2008

Macromol. Res.

View full text Add to dashboard Cite

The relation between the phase separated morphologies and their transport properties in the polymer blend membrane for direct methanol fuel cell application was studied. In order to enhance the proton conductivity and reduce the methanol crossover, sulfonated poly(arylene ether sulfone) copolymer, with a sulfonation of 60 mol% (sPAES-60), was blended with nonsulfonated poly(ether sulfone) copolymer (RH-2000, Solvay). Various morphologies were obtained by varying the drying condition and the concentration of the casting solution (10, 15, 20 wt%). The transport properties of proton and methanol molecule through the polymer blend membranes were studied according to the absorbed water. AC impedance spectroscopy was used to measure the proton conductivity and a liquid permeability measuring instrument was designed to measure the methanol permeability. The state of water in the blend membranes was confirmed by differential scanning calorimetry and was used to correlate the morphology of the membrane with the membrane transport properties.

show abstract

“…The standard potential of the DMFC is 1.21 V (at 25°C), which is very close to that of the hydrogen/oxygen fuel cell (1.23 V). The cell output voltage is much lower, however, due to a number of factors [1][2][3][4]. One of the reasons for the poor DMFC performance is the slow reaction kinetics of methanol oxidation at the anode.…”

Section: Introductionmentioning

confidence: 99%

A model for mass transport in the electrolyte membrane of a DMFC

Vernersson

Lindbergh

2007

J Appl Electrochem

View full text Add to dashboard Cite

A steady state model for multicomponent mass transport was derived for the direct methanol fuel cell membrane. Data for development and validation of the model was taken both from experiments and literature. The experimental data was collected in a polarisation cell, where mass transport of methanol across the electrolyte membrane was measured through a potentiostatic method. The results from modelling and experiments showed good agreement. The model was capable of describing the non-linear response in mass transport to increased methanol feed concentration. The model also accurately described the change in membrane conductivity with methanol concentration. From the model transport equations, it was also possible to derive some characteristic transport parameters, namely the electro osmotic drag of both water and methanol, diffusive drag of water and methanol, and effective, concentration dependent, diffusion coefficients for methanol and water. Keywords Direct methanol fuel cell Á Modelling Á Mass transport Á Methanol crossover Á Electrolyte membrane List of symbols a i Activity of species ''i'' c i Concentration of species ''i'' [mol m -3 ] c T Sum of all concentrations [mol m -3 ] c 1 Concentration of water [mol m -3 ] c 2 Concentration of methanol [mol m -3 ] c 3 Concentration of protons [mol m -3 ] c 4 Concentration of sulphonic acid groups [mol m -3 ] D H 2 O Fickian diffusion coefficient of water [m 2 s -1 ] D CH 3 OH Fickian diffusion coefficient of methanol [m 2 s -1 ] D ij Stefan-Maxwell diffusion coefficient of species ''i'' and ''j'' [m 2 s -1 ] D 12 Stefan-Maxwell diffusion coefficient of water/methanol [m 2 s -1 ] D 13 Stefan-Maxwell diffusion coefficient of water/proton [m 2 s -1 ] D 14 Stefan-Maxwell diffusion coefficient of water/sulphonic acid [m 2 s -1 ] D 23 Stefan-Maxwell diffusion coefficient of methanol/proton [m 2 s -1 ] D 24 Stefan-Maxwell diffusion coefficient of methanol/sulphonic acid [m 2 s -1 ] D 34 Stefan-Maxwell diffusion coefficient of proton/sulphonic acid [m 2 s -1 ] f i Activity factor of species ''i'' [m 3 mol -1 ] F Faraday constant [As mol -1 ] i crossover Methanol crossover current [A m -2 ] i lim Limiting current of methanol crossover [A m -2 ] i load Current density load [A m -2 ] N i Flux of species ''i'' [mol m -1 s -1 ] N 1 Flux of water [mol m -1 s -1 ] N 2 Flux of methanol [mol m -1 s -1 ] N 3 Flux of protons [mol m -1 s -1 ] R Gas constant [J mol -1 K -1 ] T Temperature [K] z i Electric charge of species ''i'' T. Vernersson (

show abstract

Measurement of methanol crossover in direct methanol fuel cell

Cited by 86 publications

References 3 publications

A High Output Voltage Direct Borohydride Fuel Cell

A High Output Voltage Direct Borohydride Fuel Cell

Transport properties of polymer blend membranes of sulfonated and nonsulfonated polysulfones for direct methanol fuel cell application

A model for mass transport in the electrolyte membrane of a DMFC

Contact Info

Product

Resources

About