Effect of Co content on [Ca2CoO3−δ]0.62[CoO2] thermoelectric properties

Abstract

The use of thermoelectric materials, which is a clean energy conversion method, can realize the direct conversion of thermal energy and electrical energy. Ceramic samples of the [Ca2CoO3−δ]0.62[CoO2] system with different contents of Co were prepared by sol–gel method combined with cold-press technology. X-ray diffraction and field emission scanning electron microscopy were used to confirm the single-phase composition and plate grain morphology of the samples. Analysis of the thermoelectric properties of [Ca2CoO3−δ]0.62[CoO2] (300–1026 K) shows that the electrical conductivity of the CCO–Co3 sample with low Co content is increased by 12% compared with that of the original sample CCO–Co1 at 1026 K. The thermal conductivity is decreased to 2.99 Wm−1 K−1. The ZT value of the samples with low Co content reaches 0.09 at 1026 K, which is 50% higher than that of the original sample CCO–Co1. Therefore, reducing Co content is an effective method to improve the thermoelectric properties of [Ca2CoO3−δ]0.62[CoO2] ceramics.