Self-assembly CuO surface decorated with NiAl2O4 for high-temperature thermochemical energy storage: Excellent performance and strong interaction mechanism

Abstract

High-temperature thermochemical energy storage materials with high energy density is the key technical support for the third generation concentrated solar power plants equipped with advanced energy storage system. CuO/Cu2O redox couple is one of the most promising systems due to its low cost and high energy density, but its application is limited by poor reaction performance. Herein, the self-assembly CuO surface decorated with 15 wt% NiAl2O4 is prepared with excellent redox reversibility and ultralong lifespan. Its reaction rate is increased by 4.2 times with re-oxidation degree increasing from 46 % to 99.9 %. The thermochemical energy density of storage and release reach −772.726 kJ/kg and 764.655 kJ/kg, respectively. After 1000 cycles, the degree of reduction and oxidation reaction can keep 99.9 % and 98 %. The material characterization shows that NiAl2O4 are uniformly and firmly loaded on the surface of CuO/Cu2O, which significantly increases the sintering temperature and improves the reaction performance. DFT studies further confirm that NiAl2O4 has a high binding energy with CuO/Cu2O and can increase the formation energy of copper vacancy. The study reveals the anti-sintering modification mechanism of CuO/Cu2O by introducing NiAl2O4, which provides a solution toward sintering resistance of high-temperature thermochemical energy storage materials.