Parameters of PEM fuel-cells based on new membranes fabricated from Nafion®, silicotungstic acid and thiophene

Abstract Several new cation exchange membranes of different thicknesses (15–500 μm) based on a Nafion® solution and silicotungstic acid with and without thiophene (named NASTATH and NASTA respectively) were synthesized by a simple chemical route for PEM fuel-cell applications. The optimum parameters for the preparation of the membranes have been determined: 10 ml of 5% of the Nafion® 117 solution was reduced by 50% and mixed with 10−3–10−5 MSTA to produce a NASTA membrane. If liquid thiophene (0.5% by volume) is added to the above solution, a NASTATH membrane is produced. The water uptake and ionic conductivity of NASTA and NASTATH were compared with those of Nafion® 117. The effect of membrane thickness and the concentrations of STA and thiophene used during the preparation of NASTA and NASTATH on their water uptake and ionic conductivity were determined. It was shown that the water uptake of the NASTA membrane (60%) was significantly better than that of Nafion® 117 (27%), while the water uptake of NASTATH (40%) was higher than that of Nafion® 117 (27%). The ionic conductivity of both the NASTA (10.10×10−2 Ω−1 cm−1) and the NASTATH (9.5×10−2 Ω−1cm−1) was found to be significantly higher than that of the Nafion® 117 (1.23×10−2 Ω−1 cm−1). The membrane performances were also determined by chemical stability studies. The membranes fabricated with Nafion® and silicotungstic acid with and without thiophene still exhibited good mechanical strength and stability after they had been dipped in an acid or a basic medium for at least 10 months. The voltage-current characteristics of solid polymer electrolyte fuel cells were determined for Nafion® 117, NASTA and NASTATH based membranes. The fuel cell parameters were correlated to the membrane water uptake and ionic conductivity. The current density at 0.600 V of the solid polymer electrolyte fuel cells (SPEFCs) based on NASTATH (810 mA cm−2) membranes was higher than that of SPEFCs based on Nafion® 117 (640 mA cm−2). It was shown that the better fuel cell parameters were not obtained with the modified membranes having the higher water uptake.

[1]  O. Savadogo.  The hydrogen evolution reaction in alkaline medium on nickel modified with W042− or Mo042− , 1992 .

[2]  V. Nefedov,et al.  Electronic structures of MRhO2, MRh2O4, RhMO4 and Rh2MO6 on the basis of X-ray spectroscopy and ESCA data , 1982 .

[3]  R. Stone.  Sweeping Patents Put Biotech Companies on the Warpath , 1995, Science.

[4]  K. Mandal,et al.  Studies on new chemically deposited photoconducting antimony trisulphide thin films , 1992 .

[5]  O. Savadogo,et al.  2% Platinum-H[sub 2]WO[sub 4] based electrocatalysts for phosphoric acid fuel-cell cathode , 1994 .

[6]  M. Cassir,et al.  Behavior of titanium species in molten Li2CO3–Na2CO3 and Li2CO3–K2CO3 under anodic and cathodic conditions. I – Thermodynamic predictions at 550–750°C , 1998 .

[7]  D. Ostrovskii,et al.  Water sorption properties of and the state of water in PVDF-based proton conducting membranes , 1997 .

[8]  Supramaniam Srinivasan,et al.  Analysis of proton exchange membrane fuel cell performance with alternate membranes , 1995 .

[9]  P. Björnbom,et al.  Electrochemical characterization of PVDF-based proton conducting membranes for fuel cells , 1998 .

[10]  H. A. Liebhafsky,et al.  Fuel cells and fuel batteries , 1968 .

[11]  G. Müller,et al.  Comb‐like poly(aryl‐ether‐ketones) containing naphthalene moieties in the main chain , 1993 .

[12]  C. Nordling,et al.  Molecular Spectroscopy by Means of ESCA II. Sulfur compounds. Correlation of electron binding energy with structure , 1970 .

[13]  Sanjeev Mukerjee,et al.  Effects of Nafion impregnation on performances of PEMFC electrodes , 1998 .

[14]  B. Gupta,et al.  Materials research aspects of organic solid proton conductors , 1993 .

[15]  K. Mandal,et al.  Photoelectrochemical (PEC) solar cell properties of chemically deposited cadmium selenide thin films with heteropolyacids , 1992 .

[16]  O. Savadogo,et al.  Effect of Platinum Particle Size on the Oxygen Reduction Reaction on 2% Pt‐1% H 2 WO 4 in Phosphoric Acid , 1996 .

[17]  G. Scherer.  Polymer Membranes for Fuel Cells , 1990 .

[18]  K. Mandal,et al.  Fabrication of low-cost n-Sb2S3/p-Ge heterojunction solar cells , 1994 .

[19]  O. Savadogo,et al.  Electrocatalytic parameters of the electrodeposition of copper with silicotungstic acid (STA) , 1999 .

[20]  J. R. Stevens,et al.  Proton conducting polymer gels based on a polyacrylamide matrix , 1995 .

[21]  F. Sundholm,et al.  Effects of irradiation on sulfonation of poly(vinyl fluoride) , 1997 .

[22]  M. Elomaa,et al.  Thermal stability of styrene grafted and sulfonated proton conducting membranes based on poly(vinylidene fluoride) , 1998 .

[23]  P. Souchay.  Ions minéraux condensés , 1969 .