Exploration of LiCoO2-doped cobalt oxide composite for thermochemical energy storage at high temperature

Abstract

Due to the high energy storage density, long-term energy storage and long-distance transport possibility, as well as operation possibility under open system, metal oxide-based thermochemical energy storage (TCS) was considered as a promising candidate for efficient energy utilization. Herein, lithium cobalt oxide (LiCoO2)-doped cobalt oxide composite was proposed and investigated for the metal oxide-based TCS application. Doping with LiCoO2 diminished the onset temperature of reduction and re-oxidation by 50 °C and 65 °C, respectively. Also, doping with appropriate amount of LiCoO2 contributed to improve the re-oxidation rate of cobalt oxide-based system under a high cooling rate, resulting the discharging heat (423.8 kJ/kg) increased significantly in comparison with pure cobalt oxide (289.8 kJ/kg) under temperature cooling rate of 20 °C/min. It was found that doping with LiCoO2 decreased the apparent activation energy of reduction and oxidation. Meanwhile, the results obtained from in-situ X-ray diffraction indicate that LiCoO2 was involved in the reduction/re-oxidation process. Moreover, excellent repeatability of the composite was attested in 30 cycles. Hence, doping with LiCoO2 was verified as an effective method to expanding the possibility of cobalt oxide for TCS application.