Atomic layer deposition of ultrathin blocking layer for low-temperature solid oxide fuel cell on nanoporous substrate

Abstract

An ultrathin yttria-stabilized zirconia (YSZ) blocking layer deposited by atomic layer deposition (ALD) was utilized for improving the performance and reliability of low-temperature solid oxide fuel cells (SOFCs) supported by an anodic aluminum oxide substrate. Physical vapor-deposited YSZ and gadolinia-doped ceria (GDC) electrolyte layers were deposited by a sputtering method. The ultrathin ALD YSZ blocking layer was inserted between the YSZ and GDC sputtered layers. To investigate the effects of an inserted ultrathin ALD blocking layer, SOFCs with and without an ultrathin ALD blocking layer were electrochemically characterized. The open circuit voltage (1.14 V) of the ALD blocking-layered SOFC was visibly higher than that (1.05 V) of the other cell. Furthermore, the ALD blocking layer augmented the power density and improved the reproducibility.

Ultrathin Atomic Layer-Deposited CeO2 Overlayer for High-Performance Fuel Cell Electrodes

“…Consequently, the cell with the ALD CeO 2 -coated cathode shows a very high peak power density of 800 mW cm –2 at an even more elevated temperature of 500 °C, which is the record-high performance among nanoporous-substrate-based thin-film SOFCs reported at this temperature range (≤500 °C) (Figure and Figure S11). ,,,− Compared to the performances of nanoporous substrate-supported LT-SOFCs reported previously, which are mostly ≤400 mW/cm 2 at the temperature range of ≤500 °C, the LT-SOFC of this work demonstrates a high power density that is close to that of high-temperature SOFCs (∼1 W/cm 2 ), and it is easily scalable due to the use of nanoporous substrates as well as batch thin-film processes.…”

Surface engineering of nanoporous substrate for solid oxide fuel cells with atomic layer-deposited electrolyte

“…The EIS curve for the Cell-B contains two predominant semicircles with peak imaginary values at 1 kHz and at 20 Hz by a non-linear least square fitting to the equivalent circuit consisting of one resistance (related to ohmic resistance) and two pairs of constant phase element and resistance (related to electrode–electrolyte interfacial resistance) [6]. Referring to the previous literatures [6,20–22], it is considered that semicircles at higher and lower frequencies correspond to the anode and cathode interfacial resistances, respectively. The Cell-A, on the other hand, shows the EIS behavior with a diagonal form at a lower frequency region below 20 Hz, which is not observed in the impedance spectra of Cell-B.…”

Review on process-microstructure-performance relationship in ALD-engineered SOFCs

“…However, the cell performance was very low (<1 mW cm −2 at 550°C) due to physical defects induced by the chemical etching process leading to chemical shorting through the electrolyte. ALD YSZ electrolytes on a nanoporous substrate ALD thin films have also been widely employed as dense electrolytes for nanoporous substrates (e.g., anodized aluminum-oxide (AAO))-based MEA designs [59][60][61][62][63][64][65][66][67][68][69][70][71]. In 2011, ALD Al 2 O 3 , which is not an ionic conductor, was used to fabricate gas-tight electrolytes by physically filling pinholes and voids.…”

“…In addition, the anode structure was stabilized [64]. Cha's group reported the use of an ALD YSZ layer at the anode to impede reduction of doped CeO 2 (GDC or YDC) at elevated temperature [60,61,70,71]. By adopting the ALD YSZ layer, the OCV increased from ∼0.3 V to >1.0 V. Hong et al reported anodized aluminum oxide (AAO)-based SOFCs with a 180 nm layer of YSZ electrolyte fabricated by ALD [62].…”