Recent advances in proton exchange membranes for fuel cell applications

Fuel cell technology has drawn much attention from scientists and engineers due to its high energy conversion efficiency, quick start-up in the beginning of operation, portability, and minimal pollution. Proton exchange membranes (PEMs) play an important role in the fuel cell systems. A good PEM must meet a series of requirements such as high proton conductivity, excellent mechanical strength and stability, chemical and electrochemical stability, low fuel or oxidant crossover, and be amenable for fabrication into membrane electrode assemblies. In this paper, we focus on the recent advances in development of novel PEMs that work well under elevated temperature and/or low relative humidity. All PEMs described in this paper are divided into three categories: polymeric, ceramic, and inorganic-organic composite membranes. The Nafion membrane with structural and compositional modifications is the most promising candidate that can adapt to high temperature and low relative humidity operating conditions. Ceramic and inorganic-organic composite membranes display some desired properties, but the development of these membranes is still in early stages and further in-depth studies are needed. Possible approaches focusing on (1) improvement of proton conductivity and (2) enhancement of mechanical and thermal stabilities to improve the performance of novel PEMs are also discussed. (C) 2012 Elsevier B.V. All rights reserved.