A team of researchers at MIT and Pennsylvania State University, which has been working on a new layer-by-layer (LbL) method for producing novel kinds of membranes, has developed a new solid-state polymer electrolyte for use in electrochemical devices such as fuel cells and batteries using that method.

One potential advantage of such a system is that it could produce electrolytes that are firmly bonded to the fuel-cell electrodes on either side of them. In conventional fuel cells, the three parts are made separately and then pressed together, and these bonds can be a source of inefficiency. With the new process, the membrane could be formed directly on the electrode, creating a uniform and highly controlled membrane-electrode assembly.

By creating interfaces that are tightly bonded, the efficiency and reliability of the systems can be improved, according to Avni Argun, a postdoctoral researcher at MIT working with Paula Hammond, the Bayer Professor of Chemical Engineering. By improving the efficiency of the system, it should be possible to reduce the amount of platinum needed in the electrodes, with a resulting reduction in cost.

In a paper published in the ACS journal Chemistry of Materials, Argun et al. describe their use of the LbL assembly method to create homogeneous blends of MEEP (poly[bis(methoxyethoxyethoxy) phosphazene]), a hydrogen bonding acceptor and PAA (poly(acrylic acid)) with controlled film growth, high ionic conductivity, and excellent hydrolytic stability.

To the best of our knowledge, this is the first

incorporation of a phosphazene based polymer into a multilayer structured thin film. These films are promising candidates as truly solid-state polymer electrolytes in

electrochemical devices such as fuel cells and batteries.

—Argun et al.

Resources

• Avni A. Argun, J. Nathan Ashcraft, Marie K. Herring, David K.Y. Lee,

  Harry R. Allcock, and Paula T. Hammond (2010) Ion Conduction and Water Transport in Polyphosphazene-Based Multilayers. Chem. Mater. 226–232 doi: 10.1021/cm902769m