Microscopic conductivity of passive films on ferritic stainless steel for hydrogen fuel cells

TL;DR

This study investigates the microscopic electrical conductivity of passive oxide films on ferritic stainless steel used in hydrogen fuel cell separators, revealing highly conductive regions that influence material performance.

Contribution

It introduces advanced microscopy techniques to map microscopic conductivity variations in passive films, providing new insights into their electrical behavior in fuel cell applications.

Findings

Highly conductive regions identified within passive films

Conductivity varies depending on location within the film

Insights support improved separator material design

Abstract

Hydrogen fuel cells offer a clean and sustainable energy conversion solution. The bipolar separator plate, a critical component in fuel cells, plays a vital role in preventing reactant gas cross-contamination and facilitating efficient ion transport in a fuel cell. High chromium ferritic stainless steel with an artificially formed thin chromium oxide passive film has recently gained attention due to its superior electrical conductivity and corrosion resistance, making it a suitable material for separators. In this study, we investigate the microscopic electrical conductivity of the intrinsic passive oxide film on such ferritic stainless steel. Through advanced surface characterization techniques such as current sensing atomic force microscopy and scanning tunneling microscopy/spectroscopy, we discover highly conductive regions within the film that vary depending on location. These findings provide valuable insights into the behavior of the passive oxide film in fuel cells. By understanding the microscopic electrical properties, we can enhance the design and performance of separator materials in hydrogen fuel cells. Ultimately, this research contributes to a broader understanding of separator materials and supports the wider application of hydrogen fuel cells.