Role of Calcium Doping to Improve the Performance of Titanate-Based Cathode for Low-Temperature Solid Oxide Fuel Cell

Abstract

The stable, efficient, compatible, and cost-effective cathode material is essential for low-temperature solid oxide fuel cells. In this work, Ba_0.5Sr_0.5Ca_x\({\text{T}}{{{\text{i}}}_{{1-x}}}\)\({{{\text{O}}}_{{3-\delta }}}\) (BSCT, x = 0.02, 0.04, 0.06, 0.08) cathode material has been synthesized using the sol-gel method. XRD analysis confirmed a single cubic phase structure (JCPDS 96-152-1268) with space group Pm3m. The average crystallite size of the cubic phase is 33.49 nm. The surface morphology revealed that particles are spherical and homogeneous, and no agglomeration is found. The void in the microstructures shows the porosity in the prepared material. UV‑visible spectroscopy has been used to calculate the bandgap, which shows a redshift from 3.84 to 3.72 eV with increasing calcium concentration. Metal–metal formation of Ba–Ti is identified at 544 cm^–1 with Fourier transform infrared spectroscopy. Among all samples, Ba_0.5Sr_0.5Ca_0.08Ti_0.92\({{{\text{O}}}_{{3-\delta }}}\) possesses a maximum conductivity of 1.82 S cm^–1 at 600°C in an oxygen atmosphere. The composition Ba_0.5Sr_0.5Ca_0.08Ti_0.92\({{{\text{O}}}_{{3-\delta }}}\) displayed a maximum power density of 106 mW cm^–2 at 550°C with 0.98 V open circuit voltage using H₂ fuel.