Ag/Ce0.9Gd0.1O2- δ Based Vertically Aligned Nanocomposite Thin Film Electrodes for Low-Temperature Solid Oxide Cells

Abstract

Low temperature solid oxide cells (LT-SOCs, 300-500°C) have become the "next generation" technology following the commercialized high temperature SOCs (650–850 °C). The current research is focused on screening new materials and microstructural designs that are ideal for low-temperature operations. This study explores the vertically aligned nanocomposite (VAN) heterostructure design, which has been shown to provide novel properties and new functionalities at the heterointerfaces of two oxide materials.1 In this design, we combine two materials known to show exceptionally fast electrokinetics at low temperatures. However, instead of two oxide materials, we explore a combination of electronically conducting metal and an ionically conducting oxide. The electrode composed of Ag and Ce0.9Gd0.1O2-d (CGO) is deposited epitaxially on oriented yttria-stabilized zirconia substrates by pulsed laser deposition. Silver is a highly active catalyst for oxygen reduction reactions (ORR), exhibits high electrical conductivity at low temperatures and is resistant to oxidation in air, but has a relatively low melting point and agglomerates easily in air. Therefore, it is necessary to prevent Ag agglomeration during operation. Addition of CGO is expected to (i) stabilize Ag by surrounding it through vertically grown columns and (ii) extend the ionically conducting path onto the cathode and share the oxygen ion diffusion pathway with Ag.2 Preliminary results show successful growth of ~40 nm thick oriented Ag/CGO VAN films. The investigations will be complemented with electrochemical performance and stability measurements using impedance spectroscopy. This study will provide insights into enhanced ORR performance at low temperatures by controlling crystal orientation and strain tuning at the metal/oxide VAN heterointerfaces. J. Huang, W. Li, H. Yang and J. L. MacManus-Driscoll, MRS Bull., 2021, 46, 159–167.H. R. Choi, K. C. Neoh, H. J. Choi, G. D. Han, D. Y. Jang, D. Kim and J. H. Shim, J. Power Sources, 2018, 402, 246–251.