Using In-Situ TEM Electrochemistry for the Analysis of Automotive Fuel Cell Degradation

A fuel cell is capable of converting chemical energy from a fuel into electricity via a chemical reaction with oxygen or other oxidizing agent. However, the materials used in the fuel cells are expensive and charge efficiency tends to degrade quickly. These issues hinder their use in the automotive sector.

The article will study the degradation in the fuel cell’s charge efficiency, which is their ability to charge and discharge at the requisite performance levels.

Current Generation of Fuel Cells

Fuel cells currently available have a maximum usage period of five years when they start degrading and have to be replaced in automotive applications. Manufacturers of automobiles expect at least a healthy life cycle of 10 years. Although the key reasons for degradation are understood to an extent, it has not been observed and studied closely.

Plug-in Hybrid Vehicles

Plug-in hybrid cars are the first kind of low emission electric vehicles to enter the automobile sector. It is expected that a more effective and powerful fuel cell with replace the battery, which is presently the most cost effective option available for storing energy.

This new fuel cell can be easily demonstrated, and current models can provide a 300-mile range on a single charge.

However, fuel cells have drawbacks such as making automobiles cost prohibitive and their degradation at a fast rate thereby rendering them not viable half way through the life of the chassis. To solve these issues automakers, government, and commercial researchers are getting involved in extensive research to increase the fuel cell’s lifespan.

Protochips’ Poseidon 500 to Observe Degradation Mechanisms

By looking at the way in which degradation mechanisms progress on the nanoscale, a possible solution can be arrived at to enhance the service life of the fuel cells. David Muller’s research group at Cornell University used Protochips’ Poseidon 500 system within an FEI Titan transmission electron microscope (TEM) to image the degradation mechanisms as they occurred. During the whole procedure, the researchers gathered quantifiable analytical data along with visual observations.

Figure 1. Cyclic voltammetry of Pt on a carbon support in situ.

Degradation was initially considered to be caused by the effect of Ostwald ripening, where larger nanoparticles seized atoms from smaller nanoparticles. It was also thought that the rest of the degradation occurred due to coalescence.

Although difficult to demonstrate, coalescence can be easily studied using a TEM. The observation revealed that both coalescence and Ostwald ripening had an equal effect on fuel cell degradation.

Moreover, both mechanisms displayed a cooperative effect that led to coarsening within the cell. This cooperative nature of the mechanisms helped to formulate a strategy to decrease coalescence, which subsequently will also reduce Ostwald ripening.

Figure 2. Carbon support degradation when 1.9V is applied after 0s, 38s, 86s and 260s.

Using the Poseidon 500 system, Dr. Mueller proved that he could minimize the degradation mechanisms by reducing loading of particles on the catalyst. The spatial distributions helped to minimise coalescence by allowing particles to move a longer distance before colliding with another particle.

Conclusion

Fuel cells are the viable answer to the future needs for automotive energy storage, therefore extensive research on degradation mechanisms will continue as it is crucial for commercial applications.

About Protochips

Protochips, Inc. is a rapidly growing early-stage company focused on providing the world's leading materials and life sciences research breakthrough analytical tools for targeted research and development of nano-scale materials.

Using its proprietary technology, Protochips is addressing the market need by transforming the most widely used tools in nanotechnology – electron and optical microscopes - from cameras into complete nano-scale laboratories.

Protochips' core competency lies in the application of semiconductor techniques to development of MEMS devices capable of providing heat, electrical, liquid and gas environments to samples in situ.

This information has been sourced, reviewed and adapted from materials provided by Protochips.

For more information on this source, please visit Protochips.

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