Is Coating Oxide on Porous Metal Thin-Film for Low-Temperature Solid Oxide Fuel Cell Cathode a Panacea for Performance Enhancement?

Abstract

The Pt thin-film cathode thermo-mechanically reinforced by using atomic layer-deposited (ALD) alumina overcoat for low-temperature solid oxide fuel cells was investigated on electrochemical and electrical performances and its area specific resistance (ASR) with respect to cell dimension was evaluated. The nanoporous Pt thin-film cathode was fabricated by direct current magnetron sputtering with a deposition pressure of 50 mTorr. And alumina overcoat was deposited with thermal ALD 30 cycles onto the nanoporous Pt thin-film cathode. Compared to bare Pt thin-film cathode, ALD alumina-overcoated Pt thin-film cathode provided ~ 3-times lower activation ASR and ~ 2-times lower effective electrical conductivity after 4-h operation at 550 °C. Despite increases in the thermo-mechanical stability of Pt thin-film cathode by ALD alumina overcoating, it was evaluated that the total ASR of ALD alumina-overcoated Pt thin-film cathode was lower than that of the bare Pt thin-film cathode only if cell dimension is below 0.95 cm2 because of its lower current collecting performance in the in-plane direction.