Development of LiCoO2 and CuO co-doped cobalt oxide composites for the comprehensive performance improvement of thermochemical energy storage in concentrated solar power plants

Due to its high energy storage density and ability to operate in an air atmosphere, cobalt oxide (Co3O4/CoO)-based redox thermochemical energy storage (TCES) has attracted considerable attention for concentrated solar power (CSP) plants. However, the large temperature hysteresis and low oxidation rate degrade the system's thermal output. Additionally, the high reduction temperature increases the costs of solar filed. In this work, we proposed a LiCoO2 and CuO co-doped cobalt oxide composite. The composites showed a 105 °C lower onset reduction temperature compared to pure Co3O4. A narrowed temperature hysteresis of ∼5 °C was achieved by varying the doping amount. The oxidation rate was improved, peaking at over 0.5 min−1, significantly higher than pure CoO (0.35 min−1). Thermogravimetric analysis over 30 cycles demonstrated excellent stability of these modifications. Moreover, the composites exhibited enhanced energy storage capacity of Co3O4, reaching 81.6 % of its theoretical potential, higher than the 64.1 % of undoped Co3O4. Cycling experiments using over 10 g of the optimal composite indicated stable repeatability, with exceeding 88 % conversion ratio over 32 cycles. This study highlights the comprehensive performance improvement of cobalt oxide-based composites achieved through co-doping with multiple foreign compounds and enhances the potential of cobalt oxide-based materials for CSP applications.