Invited: Development of Nstf Electrode for PEMFC

Ionomer-free ultrathin electrodes, such as the 3M Nanostructured Thin Film (NSTF) electrode, provide a plausible pathway to reduce Pt cost and enhance the electrode durability in low temperature fuel cells. However, the absence of ionomer, the small electrode thickness, and the small Pt area make operating a fuel cell a challenge.

We have developed several materials and system solutions to mitigate these issues^1,2 and numeric models^3,4 to enhance our understanding of fuel cell performance in NSTF electrodes. We then further investigated the stability of the NSTF electrodes under accelerated tests⁵ and tests that were designed to simulate real-life automotive operation⁶. We observed irreversible voltage decay behavior that could not be explained by known electrode degradation mechanisms of carbon corrosion, Pt dissolution, or membrane thinning. Correlation among different events that contribute to the degradation will be discussed. For example, we found that it is important to avoid entering a potential window in which irreversible degradation occurs. Mitigation strategies to maximize the electrode life will be suggested.

Lastly, we will present our recent development in using atomic layer deposition to form a uniform thin layer of Pt on an NSTF support. This method can reduce the Pt loading by a factor of three compared to the current method. Its fuel cell activity will be also discussed.

Acknowledgements

The authors thank Mark K. Debe, Edward M. Fischer, and Andrew Steinbach of 3M for providing NSTF MEAs and for useful discussions. Thanks are also extended to Frank Coms, Wenbin Gu, Yeh-hung Lai for insightful comments; Ted Gacek, Heidi Viterise, Tom Jackson, Matt Dioguardi, Jeanette Owejan, Scott Moose, Travis Downs, and Rob Moses for engineering support.

References

1. A. Kongkanand, M. Dioguardi, C. Ji and E. L. Thompson, Journal of the Electrochemical Society, 159, F405 (2012).
2. A. Kongkanand, J. E. Owejan, S. Moose, M. Dioguardi, M. Biradar and R. Makharia, Journal of the Electrochemical Society, 159, F676 (2012).
3. A. Kongkanand and P. K. Sinha, Journal of the Electrochemical Society, 158, B703 (2011).
4. P. K. Sinha, W. Gu, A. Kongkanand and E. Thompson, Journal of the Electrochemical Society, 158, B831 (2011).
5. A. Kongkanand, Z. Liu, I. Dutta and F. T. Wagner, Journal of the Electrochemical Society, 158, B1286 (2011).
6. A. Kongkanand, J. Zhang, Z. Liu, Y. Lai, P. Sinha, E. Thompson, R. Makharia, submitted to Journal of the Electrochemical Society (2014).