Effect of lanthanum tungstate hole-blocking layer for improvement of energy efficiency in anode-supported protonic ceramic fuel cells

Abstract

Conduction of minority carriers in electrolytes is one of the key factors to be controlled to realize highly efficient protonic ceramic fuel cells (PCFCs). In this study, the performance of anode-supported PCFCs using a BaZr_0.8Y_0.2O_3−δ (BZY) monolayer electrolyte membrane and a bilayer electrolyte where a lanthanum tungstate (La_28−xW_4+xO_54+3/2x; LWO) hole-blocking layer is deposited on the BZY membrane are investigated by theoretical calculations based on transport properties of the electrolytes and experimental electrochemical performance tests. The theoretical calculations indicated that the BZY|LWO bilayer cell can achieve higher open-circuit voltage (OCV) and energy efficiency than those of the BZY monolayer cell by suppressing the hole conduction in the electrolyte membrane. We experimentally confirmed that the BZY|LWO cell exhibited the OCV of 1.01 V while that of the BZY monolayer cell was 0.93 V at 600 °C. This study presents that the thin LWO hole-blocking layer is effective in the improvement of the OCV and the energy efficiency of the anode-supported PCFCs.