Caesium doping accelerates the hydration rate of potassium carbonate in thermal energy storage

Potassium carbonate has recently been identified as a promising candidate for thermochemical energy storage. However, as for many salt hydrates, its reaction kinetics is relatively slow. K2CO3 has a metastable zone, where the reaction is kinetically hindered, which limits the temperature operating window. This work aims to improve the material performance, focusing on two aspects; improving the kinetics outside the metastable zone and reducing the metastable zone width. This work shows that doping with Cs2CO3, can improve both. Moreover, it is shown that the dopant enhances the hydration rate by introducing mobility due to local deliquescence. This lays the foundation for further material research using dopants to enhance the performance of salt hydrates.