Heat storage or thermal energy storage is one of the key technologies towards an efficient use of renewable energy resources, particulary the thermochemical heat storage looks promising, but the progress has not yet been succeeded. Therefore our research group focuses on the development of a heat storage system called "thermal battery" for private households and industry applications. On the one hand especially thermochemical reactions have a high potential for high energy density and long term storage. On the other hand the used materials in particular hygroscopic salts are related to disadvantages such as agglomeration, storage capacity loss over cycling or slow reaction kinetics. Those disadvantages are caused by deliquescence and by the occurrence of side reactions, among other effects. We combined the optimization of mixing of salt hydrates and impregnation of carriers to overcome these disadvantages. This paper reports on synthesis of thermochemical materials and comparison of the material properties energy density and effective thermal conductivity.