Research Area

Fuel cells convert the chemical energy from fuels (such as hydrogen) to electrical energy. Solid oxide fuel cells (SOFCs) are one of the most attractive systems due to their high conversion efficiency; since they are electrochemical devices, their efficiency far surpasses combustion-based energy conversion. However, the operating temperature of current commercial SOFCs is around 800-950°C; at such temperatures, problems arise such as slow startup, reduced device durability, and limited material selection. To mitigate these issues, lower temperature operation is desired (550-700°C), and thus, interest has been growing in thin-film SOFCs (TF-SOFCs). By reducing the electrolyte layer thickness to a few micrometers, the electrolyte conductivity is maintained at lower temperatures and thus so is SOFC operation. Recently, we have developed a TF-SOFC (that contains a LSCF-YSZ cathode, GDC interlayer, YSZ electrode, and Ni-YSZ anode) fabricated completely by sputtering, in collaboration with Prof. Eric Fullerton’s group and Dr. Nguyen Q. Minh from Center for Energy Research. The cell demonstrated high power densities of 1.7 and 2.5 W/cm² at 600 and 650°C, respectively.

(a) Schematic of TF-SOFC, (b) STEM cross-section image of the cell, and (c) magnified STEM image of the LSCF-YSZ cathode

For synthesis of the TF-SOFCs, the sputtering technique is utilized. Compared to atomic layer deposition (ALD), sputtering can enable control of the porosity of films by tuning the synthesis parameters. Pulsed laser deposition (PLD) is also a popular technique for ceramic-based film fabrication, but sputtering is superior in terms of cost and scalability. To characterize the SOFCs, along with electrochemical methods, we explore the morphology and chemistry in each layer of the cell through techniques such as scanning electron microscope (SEM, in conjunction with the focused ion beam (FIB)), (scanning) transmission electron microscope (TEM), and electron energy loss spectroscopy (EELS).

Highlighted Publications

1. Y. H. Lee, H. Ren, E. Wu, E. E. Fullerton, Y. S. Meng and N. Q. Minh, “All-Sputtered, Superior Power Density Thin-Film Solid Oxide Fuel Cells with a Novel Nanofibrous Ceramic Cathode“, Nano Lett. 2020, 20, 5, 2943–2949

2. H. Ren, Y. H. Lee, E. A. Wu, H. Chung, Y. S. Meng, E. E. Fullerton and N. Q. Minh, “Nano-Ceramic Cathodes via Co-sputtering of Gd−Ce Alloy and Lanthanum Strontium Cobaltite for Low-Temperature Thin-Film Solid Oxide Fuel Cells“, ACS Appl. Energy Mater. 2020, 3, 9, 8135–8142