Asymmetric structuring of ceramic composite via co-electrospun sodium cobaltite and calcium cobaltite nanoribbons

An asymmetrically structured sodium cobaltite–calcium cobaltite ceramic composite with enhanced texture was synthesized using co-electrospinning of nanoribbons and rapid thermal processing (RTP). Long-term stability tests revealed that embedding the unstable sodium cobaltite in the chemically more stable calcium cobaltite effectively shields it from degradation at high temperatures in air. The composite has overall impressive thermoelectric properties. Measured at 1073 K, the composite showed an electrical conductivity of 183 S cm−1, a Seebeck coefficient of 233 µV K−1, and heat conductivity of 2.2 W m−1 K−1. It features a high power factor of 9.9 µW cm−1 K−2 and a figure-of-merit of 0.49, significantly surpassing the thermoelectric performance of sodium cobaltite–calcium cobaltite ceramic composites from previous studies.