Thermodynamic and kinetic study of the dehydration process of CaO/Ca(OH)2 thermochemical heat storage system with Li doping

• The heat storage capacity remains almost unchanged with Li doping.
• The kinetic process of Ca(OH)2 with Li doping is divided into two stages.
• The specific kinetic parameters and control equations are obtained.

Thermochemical heat storage material is very promising to realize long-term heat storage. In this paper, Li-doped Ca(OH)2 prepared by ball grinding is compared with pure Ca(OH)2 to study the influence of Li doping amount on heat storage speed by thermogravimetric (TG) experiment. Furthermore, the heat storage capacity (including the reaction enthalpy and specific heat capacity) with Li doping is studied, and the related kinetic control equation is derived. The results show that the heat storage capacity remains almost unchanged with Li doping, but the kinetic process of Ca(OH)2 heat storage with Li doping is divided into two stages which can be analyzed from the molecular structure. There is an interesting coincidence in the reduction of energy between the apparent activation energy and the energy barrier of Ca(OH)2 dehydration process with Li doping. Finally, the theoretical results using the kinetic control equations agree well with the experimental results.