Malaysian Polymer Journal, Vol. 5, No. 2, p 1-36, 2010 Available online at www.fkkksa.utm.my/mpj 1 Recent Development of Polymer Electrolyte Membranes for Direct Methanol Fuel Cell Application – A Review M. H. D. Othman, A. F. Ismail*, A. Mustafa Advanced Membrane Technology Research Center (AMTEC), Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia ABSTRACT: Direct methanol fuel cell (DMFC) system has tremendous potential to be developed as energy converters due to the simplicity and low temperature of its operation. However, the weaknesses of commercial polymer electrolyte membrane of the cell, perfluorinated ionomer (PFI) membrane, such as methanol crossover, limited operating temperature, susceptibility to osmotic swelling and high costs are among the factors hindering the commercialization of DMFC. This paper reviews a number of studies that have been recently performed in order to overcome the weaknesses. This review has classified the membrane development into three different branches, namely the modification of PFI membranes, the development of other fluoropolymer membranes, and the development of non-fluorinated polymers membranes. Keywords: direct methanol fuel cell, polymer electrolyte membrane, perfluorinated ionomer, methanol crossover, non-fluorinated polymer 1. INTRODUCTION Nowadays, direct methanol fuel cell (DMFC) is deemed as a potential option for energy converters, apart from proton exchange membrane fuel cell (PEMFC). In DMFC, methanol is fed directly to the cell without any fuel processing beforehand and as a result, DMFC does not require any fuel processing equipment. This leads to simplicity of operation in DMFC as compared to systems using a reformer to produce hydrogen from liquid fuel, i.e. indirect methanol fuel cell. Furthermore, methanol can be operated in the fuel cell system even at room temperature, compared to hydrogen, which operate at temperature higher than 80 ºC. Although the technology behind DMFC is still at the early stages of development, it has been successfully demonstrated in powering mobile phones and other portable devices. The bright prospect of DMFC can also be foreseen in other applications such as transportation and power generation. In a DMFC system as illustrated in Figure 1, methanol at the anode is oxidized to hydrogen ion (H + ) and electron (e - ) (Equation (1)). The electrons released flow through an electrical circuit that extends from the anode to the cathode. The hydrogen ions travel simultaneously to the cathode through the electrolyte membrane. At the cathode, the electron and hydrogen ion will react with oxygen to form water and release heat (Equation (2)). CH 3 OH + H 2 O → CO 2 + 6H + + 6e - (1) 3/2O 2 + 6H + + 6e - → 3H 2 O (2) *Corresponding author: A.F. Ismail, Email: afauzi@utm.my