Efficient Protonic Ceramic Fuel Cells' Performance Keyed by Electrokinetic Proton Movement in Triple Conducting Oxides

In a groundbreaking development, a research team led by Professor Guntae Kim at UNIST's School of Energy and Chemical Engineering has made significant strides in the field of proton-conducting fuel cells (PCFCs). The team's findings, published in the journal Advanced Science in June 2021, have shown promising results for PCFC operation at low temperatures.

The study, authored by Takashi Norby, explored the proton transport in proton-conducting oxides. The team employed the isotope exchange diffusion profile (IEDP) method to evaluate the proton kinetic properties of layered perovskite-type TCOs, PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF).

One of the key findings was the PBSCF cathode's excellent electrochemical performance for PCFC operation at low temperatures. The cathode exhibited a record-breaking performance of 0.42 W cm-2 at 500 °C, a significant improvement over previous results.

Heavy water (deuterium oxide, D2O) was used as a tracking indicator of proton diffusion in the study. The findings showed that the PBSCF had a proton tracer diffusion coefficient (DH) of 1.04 × 10-6 cm2 s-1 at 550 °C, which is two orders of magnitude higher than its oxygen diffusion coefficient (DO) at higher temperatures.

Fuel cells, including PCFCs, are eco-friendly energy conversion systems that use the chemical energy of hydrogen or another fuel to generate electricity. PCFCs have shown great potential to be operated at relatively low temperatures, making them a promising alternative to traditional fuel cells.

Advantages of PCFCs include a wide range of operating temperature and material choice, which could solve critical issues for solid-state electrochemical devices. This research was a collaborative effort, with Professor Sivaprakash Sengodan from UK's Imperial College London, Professor Meilin Liu from the Georgia Institute of Technology in the United States, and Professor Sihyuk Choi from Kumoh National Institute of Technology contributing to the study.

The final publication of the study was scheduled in June 2021, but the findings were made available online in March 2021. The research team is focusing on characterizing the electrochemical behavior of protons in triple conducting oxides (TCOs) for PCFCs, with the aim of further improving the performance of these eco-friendly energy conversion systems.

Efficient Protonic Ceramic Fuel Cells' Performance Keyed by Electrokinetic Proton Movement in Triple Conducting Oxides