Synthesis and characterization of SPE membrane based on sulfonated FEP‐g‐acrylic acid by radiation induced graft copolymerization for PEM fuel cell

Abstract

A Novel solid polymer electrolyte (SPE) membrane containing both COOH and SO3H group has been prepared by simultaneous method of radiation grafting of acrylic acid onto FEP followed by sulfonation. The presence of weakly acidic acrylic acid controls the swelling in water while SO3H group provides conductivity due to its strongly ionic characteristic. FEP‐g‐acrylic acid and its sulfonated derivatives were characterized by their properties. While the mechanical properties decreased, other properties such as ion exchange capacity (IEC), water uptake and ionic conductivity increased with increase in graft content. These properties further changed on sulfonation. Acrylic acid being weakly acidic in nature, conductivity values of the grafted membrane were quite low. However, introduction of strong SO3H group resulted in conductivity closer to Nafion 117. Few sulfonated membranes have been tested with respect to H2/O2 fuel cell performance. Short‐term fuel cell test for 100 hr gave a stable performance. These membranes are less expensive compared to Nafion. Copyright © 2004 John Wiley & Sons, Ltd.

Improvement of polymer electrolyte membrane by radiation-induced grafting of styrene onto FEP film with subsequent sulfonation

“…The ion exchange capacity (IEC) [3] was measured by using the following procedure. First, the sulfonated FEP membrane is immersed in a saturated NaCl solution and equilibrated for several hours to exchange the H + ions in the sulfonic acid groups with Na + ions.…”

“…Several kinds of fluorinated polymers such as FEP [10][11][12], PTFE [13,14], and ETFE [15] have been tested for the purpose of manufacturing fuel cell membranes. The grafted polymers should be sulfonated in order to introduce sulfonic acid groups into the polymeric structure, causing them to exhibit the hydrophilic polarity of SO 3 − in aqueous solution, which makes it possible to transfer protons from the anode to the cathode through such a membrane. The electron beam radiation process is known to be economical, due to its high production rate and high power efficiency.…”

“…However, Nafion membranes have some disadvantages [4] such as their high cost, low operating temperature and high methanol permeability when used in DMFCs [1,[5][6][7]. The membranes used in PEFCs should exhibit good features in terms of several properties such as their ion conductivity, thermo-chemical stability, mechanical strength, and anti-permeability of fuel through the membrane [3]. Dupont Co. started developing Nafion membranes in 1968 and the most recent version, Nafion 120, has a lifetime of up to 60,000 hours at an operating temperature of 80 o C [1].…”

“…In recent years, it has been suggested that in the future PEFCs will become one of the most attractive sources of clean energy in automobile, distributed power, and portable power applications [1,2]. Several kinds of fluorinated polymers have been used as the basic polymers for manufacturing fuel cell membranes, of which DuPont's Nafion membrane is typically used as the polymer electrolyte membrane (FEM) in PEMFCs, because of its excellent chemical and mechanical stability, as well as its high proton conductivity [3]. However, Nafion membranes have some disadvantages [4] such as their high cost, low operating temperature and high methanol permeability when used in DMFCs [1,[5][6][7].…”

Modified Sulfonated Poly(arylene ether sulfone) Membranes Prepared via a Radiation Grafting Method for Fuel Cell Application

“…[1][2][3][4][5][6][7][8] Various recent studies have also utilized radiation modification techniques to prepare proton exchange membranes (PEMs). 3,[9][10][11][12] PEMs are membranes which have the ability to selectively transfer protons generated by electrochemical reactions from the anode to the cathode in fuel cells. For this purpose, polymers having strong acidic functional group as proton carriers (e.g.…”