Nickel oxide electrodes sintering

An interesting cost trade-off for the nickel-zinc system is available concerning the nickel electrode. The ultimate design objective is, of course, to develop a deep cycling capability upwards to 1000 cycles. However, if a much lower cycle life can be tolerated (200-250 cycles), it is possible to construct cells with non-sintered nickel oxide electrodes at a lower cost. 

The nickel-based systems include the flowing systems nickel—iron (Ni/Fe), nickel—cadmium (NiCd), nickel—metal hydrides (NiMH), nickel—hydrogen (Ni/ H2), and nickel—zinc (Ni/Zn). All nickel systems are based on the use of a nickel oxide active material (undergoing one valence change from charge to discharge or vice versa). The electrodes can be pocket type, sintered type, fibrous type, foam type, pasted type, or plastic roll-bonded type. All systems use an alkaline electrolyte, KOH. 

Nickel oxide is used in the ceramic industry for making frit, ferrites, and coloring porcelain. The oxide in sinter form is used in the production of nickel-steel alloys. It supplies oxygen to the melt for removal of carbon as carbon dioxide. Some other important uses of nickel oxide include preparation of many nickel salts, specialty chemicals, and nickel catalysts. It also is used as an electrode in fuel cells. 

Iron-nickel oxide cells are always vented. Tubular/pocket plate electrodes are constructed as described above and are generally housed in nickel-plated steel cases. Cells with sintered plate electrodes have smaller inter-electrode spacings. They use synthetic fibre fabrics as separators, and plastic containers. 

Electrodes The electrocatalytic material of an MCFC is nickel. The cathode becomes oxidized and lithiated during the first hours of the operation. Nickel oxide is soluble in molten carbonates thus in the course of the operation two undesirable effects may occur (1) metallic nickel particles are formed in the electrolyte which can lead to an electronic short circuit of the electrodes, (2) the size of the cathode diminishes. Two approaches have been proposed for solving these problems the use of less corrosive molten carbonate mixtures and more stable cathodes containing iron and cobalt. The nickel anodes usually contain chromium, which promotes the sintering process. 

The electrodes are flat. The anode is composed of porous sintered nickel along with additives, which inhibit the loss of surface area during operation. The anode is in direct contact with the electrolyte matrix. The cathode is a porous nickel oxide, which is initially fabricated in the form of a porous sintered nickel and is subsequently oxidized during the cell operation. 

Black nickel oxide Bunsenite C.l. 77777 CCRIS 431 Cl 77777 EINECS 215-215-7 Green nickel oxide HSOB 1664 Mononickel oxide Nickel (II) oxide Nickel monoxide Nickel oxide Nickel oxide (NiO) Nickel oxide sinter 76 Nickel protoxide Nickel(2+) oxide Nickel(ll) oxide Nickelous oxide. Used in preparation of nickel salts, in porcelain painting and fuel cell electrodes. Green powder mp = 1960" d = 6.6700 insoluble in H2O soluble in acids. Atomergic Chemetals Cerac Nihon Kagaku Sangyo Noah Chem. 

Fuel cells (FCs) are electrochemical devices that directly convert fuel energy into electricity without the need for a thermal cycle. They are essentially galvanic cells in which the electrodes only collect and convey electrical charges, but (unlike in the Volta pile and all other electric cells and batteries) they do not participate in the electrochemical reaction, since they are chemically and electrochemically inert conductors (amorphous carbon, sintered nickel oxide, etc.). 

Alkaline FCs (AFCs) use KOH as electrolyte and work at 70-90 C they are fully developed and very reliable (they powered on-board instrumentation of the Apollo spacecrafts and they power on-board instrumentation of the space Shuttles). Electrodes are mostly sintered nickel (anode) and sintered, lithiated nickel-oxide (cathode). 

Sintered Electrodes In these electrodes the active materials are present in pores of a sintered nickel support plate. This plate is manufactured by sintering of highly disperse nickel powder produced by thermal decomposition of nickel pentacarbonyl Ni(CO)5. The plates are filled by impregnating them in alternation with concentrated solutions of salts of the corresponding metals (Ni or Cd) and with an alkali solution serving to precipitate insoluble oxides or hydroxides. 

Justi et al. (75) had already introduced Raney-nickel anodes for anodic hydrogen oxidation in alkaline fuel cells in the early sixties. At that time they used sintered electrodes composed of Raney-nickel particles, which are, however, too heavy and too expensive to be of use for commercial cells as too high loadings of the relatively expensive nickel are needed. Today... 

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