We propose new Li2CO3-doped dark CaCO3 pellets. The solar full-spectrum absorption of the new pellets can be as high as 73.25%. After 60 cycles, the energy storage density of the new CaCO3 pellets is still as high as 1671 kJ/kg, and the decay rate of the energy storage density decreased from 56.73% to 4.24% compared with pure CaCO3 pellets. At the same temperature, the average decomposition rate of the new CaCO3 pellets in the first cycle is 2.1 times that of the ordinary dark CaCO3 pellets. Therefore, this new CaCO3 pellets can simultaneously achieve the characteristics of fast heat storage, excellent cyclic stability and high solar absorptance.
Keywords CaCO3, Li2CO3, fast heat storage, cyclic stability, solar absorptance