Speaking of patents, here's a very early one mentioning Ni-H. (1991)
Electrolysis apparatus and electrodes and electrode material therefor
Jun 1, 1999
An improved electrolysis system includes a cylindrical anode, a cylindrical cathode, a cathode material including nanocrystalline particles, and an insulator disposed between the anode and the cathode material to prevent contact between the anode and the cathode material.
It should be mentioned that nickel is relatively inexpensive compared with palladium, which is the electrode material of choice used in many other electrolysis apparatuses. While the solubility of hydrogen in nickel is relatively lower at room temperature and one atmosphere pressure (0.005 atom percent) than that of palladium, significant trapping is known to occur at elevated temperature and pressure conditions.
The particulate reaction material, i.e., either unconsolidated or consolidated nanocrystalline nickel, is disposed within an electrolysis cell apparatus 100, as shown in FIG. 1. Various alternative configurations are illustrated in FIGS. 2 and 3; other variations are expected to occur to those of ordinary skill in the art and are considered to be within the scope of the present invention. The elemental cell 100 includes an anode 102 and a cathode 104, which cathode is electrically connected to the cathode nanocrystalline reaction material 106. Advantageously, the anode 102 and the cathode 104 can be cylindrical members which collectively define an annular space or torus. It should be mentioned that the configuration is exemplary and not a limiting cell geometry.
Preferably, a portion of the annular space between end caps generally denoted 110 forms the reaction volume 112 of the cell 100. The end caps 110 advantageously can be a gas-porous insulating material, which preferably is an insulating ceramic material. In an exemplary case, both end caps are permeable to helium, with at least one of the end caps 110 being permeable to hydrogen gas as well. Between the two end caps 110 is disposed a porous reaction vessel 108 which, in an exemplary case, is a cylindrical reaction vessel. It will be appreciated that the reaction vessel 108 is contained within the reaction volume 112. Advantageously, the reaction vessel can be a porous, rugged, ceramic matrix composite member, which beneficially functions to electrically insulate the cathode reaction material 106 from the anode 102 while permitting hydrogen gas to flow easily up to the surface of the reaction material 106. See FIG. 1.
ETA - link to google patent with diagrams of reactor types.