Double-Decker Design for High Performance Solid Oxide Cells

Abstract

The solid oxide cell is one of the key energy conversion devices for achieving a low-carbon society. A single solid-ion conductor such as oxide ion or proton conductor is generally used for the electrolyte sandwiched between positive and negative electrodes. However, because of the low oxide ion conductivity, a high operating temperature is required resulting in low stability and high operational cost. In contrast, a cell using a proton-conducting oxide can operate at intermediate or low temperatures, unfortunately, the Faradaic efficiency is low because of the partial electronic conductivity. Here, we propose a double decker design for a solid oxide cell by depositing oxide and proton conducting solid oxide films onto an intermediate porous electrode. A proton-conducting electrolyte, BaZr0.44Ce0.36Y0.1O3-δ film was deposited on a porous NiO-SrZr0.5Ce0.4Y0.1O3-δ substrate by the tape-casting and co-sintering method. Onto this half-cell, a porous interlayer electrode of several oxides was deposited, and the upper electrolyte film of La0.9Sr0.1Ga0.8Mg0.2O3-δ was further deposited by the pulsed laser deposition method. Finally, an air electrode was deposited to assemble a single cell with two electrolyte layers. By using oxide, proton and electron triple conductor for the interlayer electrode, the newly designed cell generated good performance for both fuel cell and steam electrolysis modes at low temperature. More importantly, this cell shows a high and stable Faradaic efficiency despite the BaZr0.44Ce0.36Y0.1O3-δ proton conductor cell, which makes it more promising for green H2 production from steam electrolysis.