High temperature thermochemical energy storage materials
Disclosed are high enthalpy thermochemical energy storage materials that exhibit high thermal conductivity and stability at high temperature reaction conditions. Disclosed materials include hydride-based alloys that can undergo high temperature reversible hydrogenation/dehydrogenation reactions without phase change of any metal or metalloid components of the alloy. The materials undergo a reversible exothermic hydrogenation reaction to form a metal hydride and a ternary alloy that includes a high thermal conductivity metal that, in its pure state, would exhibit a phase change at the hydrogenation reaction conditions.
1. A thermochemical energy storage material comprising:
a) a single phase composition comprising a combination of CaAl 2 Si 2 and CaH 2 ; and
b) a thermal conductivity moderator comprising graphitic carbon; wherein
the thermochemical energy storage material is stable at a temperature of from 700° C. to 900° C. and at a pressure of from about 5 bar H 2 to about 60 bar H 2 .
2. The thermochemical energy storage material of claim 1 , wherein a dehydrogenation reaction of the single phase composition forms Ca 3 Al 2 Si 2 and H 2 .
3. The thermochemical energy storage material of claim 1 , wherein the single phase composition has a thermal conductivity of at least about 4 W/mK at a temperature of about 100° C.
4. The thermochemical energy storage material of claim 1 , wherein the single phase composition has a thermal conductivity of at least about 6 W/mK at a temperature of about 100° C.
5. The thermochemical energy storage material of claim 1 , wherein the thermal conductivity moderator defines pores, the pores containing the single phase composition.