Abstract An economical metallic material for absorption and desorption of hydrogen comprising an alloy having the general formula represented by ABx, wherein A is Ca or a metallic material which is an alloy including Ca, B is Ni or a metallic material which is an alloy including Ni, and x is in the range of 3.8-6.3, and exhibiting a hydrogen dissociation equilibrium pressure (or plateau pressure, pressure of the plateau region of hydrogen dissociation pressure-hydride composition isotherm) below 1 atm at normal temperatures. The material of the invention very easily absorbs large amounts of hydrogen and efficiently releases it at other predetermined temperatures, pressure and electrochemical conditions, whereby it is able to store hydrogen safely, usefully and economically. It is also suitable for use especially as media for thermal energy storage such as solar energy, waste heat from the electric power generators, and iron foundries, as the alloy of this invention has a plateau pressure below 1 atm at room temperature and of several atmospheres at 35 DEG -100 DEG C.
Material for hydrogen absorption and desorption comprising an alloy represented by the formula AB x in which A represents an alloy consisting of calcium and magnesium, B represents a metal comprising nickel, x is a value indicating the ratio of B to A and is 3.8 to 6.3, the hydride of said alloy having a hydrogen dissociation eqilibrium pressure of less than atmospheric pressure at room temperature and of several atmospheres at 35° to 100° C., said material having a single homogeneous hexagonal structure phase of the CaCu 5 type in more than 95% of the alloy.
Claim 2
Dependent Claim
97 words
Material for hydrogen absorption and desorption comprising an alloy represented by the formula AB x in which A represents an alloy consisting of calcium and magnesium, B represents a metal comprising nickel, x is a value indicating the ratio of B to A and is 3.8 to 6.3, the hydride of said alloy having a hydrogen dissociation eqilibrium pressure of less than atmospheric pressure at room temperature and of several atmospheres at 35° to 100° C., said material having a single homogeneous hexagonal structure phase of the CaCu 5 type in more than 95% of the alloy.
Claim 3
Dependent Claim
19 words
The material of claim 1 which has the formula Ca 1-y -Mg y -Ni x , in which 0<y≦0.27.
Claim 4
Dependent Claim
12 words
The material of claim 2 wherein y is approximately equal to 0.1.
Claim 5
Independent Claim
25 words
A method for heat storage which comprises contacting the hydride of the alloy of any one of claims 1 to 3 with a heat source.
Claim 6
Dependent Claim
24 words
The method for heat storage according to claim 4 wherein the heat source is at a temperature of between about 35° and 100° C.
Claim 7
Dependent Claim
24 words
The method for heat storage according to claim 5 wherein the heat source is at a temperature of between about 35° and 70° C.