LSCF-WO₃ semiconductor composite electrolytes for low-temperature solid oxide fuel cells

The La_0.6Sr_0.4Co_0.2Fe_0.8O_3- (LSCF)-WO₃ semiconductor composite was applied as an electrolyte for low-temperature solid oxide fuel cells (LTSOFCs). The study results revealed that the fuel cell could output a maximum power density (P _max) of 812 mW cm^-2 when the weight ratio of LSCF to WO₃ was 8 : 2 (8LSCF-2WO₃), and its open-circuit voltage (OCV) was higher than 1.0 V. This indicated that there was no short circuit problem in this fuel cell device and 80 wt% LSCF existed in the electrolyte layer. This was mainly due to the suppressed electronic conductivity and increased ionic conductivity of the composite as compared with LSCF due to the introduction of the WO₃ wide band semiconductor. The oxygen ionic conductivity of the 8LSCF-2WO₃ electrolyte was 0.337 S cm^-1, which is much higher than that of the pure LSCF material. According to the XPS analysis results, a higher oxygen vacancy content at the heterointerface between LSCF and WO₃ contributed to the increased ionic conductivity.