ZrO2-Doped Copper Oxide Long-Life Redox Material for Thermochemical Energy Storage

Thermochemical redox couples can satisfy the demand of high-temperature energy storage in the next-generation concentrated solar power plants. Copper oxide owns the advantage of high reaction temperature and high energy storage density but suffers from poor reversibility and cycling stability due to the sintering problem. In this work, copper oxide doped with zirconia is synthesized with a detailed analysis of its reaction performance and microstructure. Cu-Zr oxide shows a high reversibility of 99.7% in the first redox cycle and maintains a reoxidation capacity of 77.8% after 1000 cycles. Scanning electron microscopy (SEM) characterization reveals that ZrO2 particles can evenly adhere to the surface of CuO, thus inhibiting the growth of CuO particles. Molecular dynamics simulations of CuO and Cu-Zr systems also prove that the addition of ZrO2 increases the diffusion activation energy of atoms in CuO, which is key to the prevention of sintering and the improvement of cycling performance. This study investigates a generalizable sintering resistance mechanism and provides guidance for the performance improvement of thermochemical energy storage materials during the long-term operation.