Investigation on LiBH4-CaH2 composite and its potential for thermal energy storage

The LiBH4/CaH2 composite are firstly studied as Concentrating Solar Power Thermal Storage Material. The LiBH4/CaH2 composite according to the stoichiometric ratio are synthesized by high-energy ball milling method. The kinetics, thermodynamics and cycling stability of LiBH4/CaH2 composite are investigated by XRD (X-ray diffraction), DSC (Differential scanning calorimeter) and TEM (Transmission electron microscope). The reaction enthalpy of LiBH4/CaH2 composite is almost 60 kJ/mol H2 and equilibrium pressure is 0.482 MPa at 450 °C. The thermal storage density of LiBH4/CaH2 composite is 3504.6 kJ/kg. XRD results show that the main phase after dehydrogenation is LiH and CaB6. The existence of TiCl3 and NbF5 can effectively enhance the cycling perfomance of LiBH4/CaH2 composite, with 6-7 wt% hydrogen capacity after 10 cycles. The high thermal storage density, high working temperature and low equilibrium pressure make LiBH4/CaH2 composite a potential thermal storage material.