Ni Stability in Anion Exchange Membrane Fuel Cells

Hydrogen gas is a clean energy storage material because it can store and supply a large amount of energy, in theory, with no greenhouse gas (GHG) emission. Hydrogen fuel cells convert the chemical energy of hydrogen gas into electricity. In 2016, the Paris Climate Agreement was signed with major countries and economic entities, which has created a massive demand for hydrogen fuel cells. However, the conventional PEM fuel cell design has high reliance on expensive platinum group metal (PGM) catalysts. An anion exchange membrane fuel cell (AEMFC) is one of many alternatives. The AEMFC provides an alkaline environment that enables the use of many non-platinum group metal (non-PGM) catalysts. This grants AEMFCs the potential to become Pt-free and thus compete with PEM fuel cells, but the development of AEMFCs is still at an early stage. The thesis examined the hypothesis of using Ni Ni alloy catalysts to substitute for PGM catalysts for AEMFC applications. As a result, the thesis discovered a stability issue of Ni-based catalysts under AEMFC cathode conditions after long-term operations. The Ni metal, carbon-supported or in an alloy system, was irreversibly oxidized and formed a soluble species which migrated into other cell components. As supported by ICP, SEM, TEM, XPS, XRD, and FTIR analyses, the result is significant because it may limit the use of Ni-based catalysts in AEMFCs. Therefore, the use of Ni in AEMFCs needs to be carefully considered and researched. The thesis also includes works on other areas relevant to the study on the stability of Ni. As a benchmark of the Ni study, Pt was also tested under the same conditions, and the study found significant Pt agglomerations at cathodes. To provide a reliable AEMFC test environment for the Ni study, multiple AEMs were tested and compared in terms of alkaline resistance, and an alkaline exchange process was developed with improved conversion performance and stability of AEMs. To measure the in-situ Ni dissolution conditions, an operando half-cell measurement system was developed to determine the Ni dissolution form. The candidate verifies that all these findings and results are original.

Department dc:contributor.department

Chemical Engineering Applied Chemistry

Year dc:date.issued

2021

Author dc:creator

• Xie, Lin

Advisor dc:contributor.advisor

• Kirk, Donald W

Handle dc:identifier.uri

http://hdl.handle.net/1807/108974

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/108974