Electrode sintered

Sintered Cells. Tlie fabrication of sintered electrode batteries can be divided into fwe principal operations preparation of sintering-grade nickel powder preparation of the sintered nickel plaque impregnation of the plaque with actwe material assembly of the impregnated plaques (often called plates) into electrode groups and into cells and assembly of cells into batteries. 

For increased power requirements, electrode constructions have been developed which bring the electronic conductors in closer contact with the active material particles first, around 1930, the sinter electrode [110], recently in sealed cells largely replaced by the nichel-foam electrode, and then, around 1980, the fiber structure electrode [111]. In order to take full advantage of their increased perform-... 

It has been illustrated that polycrystalline materials can be operated in regenerative electrolytic solar cells yielding substantial fractions of the respectable energy conversion efficiency obtained by using single crystals. Pressure-sintered electrodes of CdSe subsequently doped with Cd vapor have presented solar conversion efficiencies approaching 3/4 of those exhibited by single-crystal CdSe electrodes in alkaline polysulfide PEC [84]. 

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. 

In the electrode with CuS alone, which has negligible conductivity, the precipitate ISE with a silicone rubber matrix has better properties than the electrode with a pressed pellet [314], The ISE with a mixture of CuS and Agi S finds broad application [325]. If the membrane is prepared by pressing, the grains of these two compounds combine to form jalpaite, Agi.55C%.4sS [180], This substance is a mixed conductor with transport numbers of Ag, 0.69 Cu(I), 0.30 and electrons, 0.01, at 25 C [175]. The sintered electrode also contains Ag1.2Cuo.8S or Ago.93Cu1.07S. Oxidation of these phases leads to considerable deterioration in the electrode function [180]. Good electrodes... 

The sintered electrode constructions are gradually replaced with structures of higher capacity as, for example, felted nickel fibril or foam structures [350-352]. An open nickel foam structure can be obtained by vapor deposition of nickel from nickel carbonyl into a bed of urethane foam and then burning off the polymer. The porosity increases from 80% typical for sinter electrodes and reaches 90-95% for felted or foam structures. Application of polymer bonded cadmium electrodes significantly reduces environmentally dangerous dusting during cell production [350]. 

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... 

Nickel-cadmium sealed cells are now a commercially important consumer product. They find use, both as button and cylindrical cells, in portable cordless appliances such as power tools, electric razors and photoflash apparatus, and increasingly in hybrid mains/battery equipment such as portable tape recorders, radios and television receivers. Many of these cells are readily interchangeable with primary batteries. In recent years, advances in design have increased recharge rates cylindrical cells with sintered electrodes can now be fast charged from full discharge at up to the C/l rate of 80% of capacity. 

Miyoshi, K., Kamegaya, Y. and Matsumura, M. (2004a) Electrochemical reduction of organohalo-gen compound by noble metal sintered electrode. Chemosphere 56, 187-193. 

In all Ni-Zn batteries, various techniques aiming at the reduction of the inactive Ni content (e.g., 60% in sintered electrodes) have been proposed. The limited reserves of the metal and the sensitivity of the battery s initial cost to nickel price would require an extremely efficient (—85%) metal recovery program. 

One option is to press the milled powders into pellets, and sinter. Electrodes or heater elements can be embedded in the pellet or applied after the sintering process. The sensor may be pretreated by exposure to gas at prescribed temperatures. 

Other Semiconductors.—Kennedy et alf have continued to study FcjOj photoelectrodes, and their most recent work shows that high efficiencies are obtained with Si-doped sintered electrodes. Dare-Edwards et alf have characterized lithium-doped NiO in some detail but, as expected, the very low carrier mobility in this material makes it quite unsuitable for solar energy conversion. Gissler has investigated trigonal Se films, and Davidson and Willsher have given further details of the properties of HgS powder photoanodes. Derivatized tin-oxide electrodes have been prepared by Fox et al.f and Janzen et al. have successfully attached the photosynthetic reaction centre molecule isolated from Rhodopseudomones sphaeroides to tin oxide (see also Section 2). 

In connection with the problems of emissions of fluorine compounds from the electrolytic production of aluminium, as a further example, we can mention the exchange of electrolysers with self-sintering electrodes for those with preliminarily calcinated anodes, which enabled the hermetic sealing of electrolytic vats and the complete withdrawal of the produced exhalates into separators. 

Fig.8 The efFeci of sintering electrodes on the fracture strength of ScSZ electrolyte measured by FOR...

FIGURE 4.1 Silver-silver electrodes for biopotential measurements (a) metallic silver with a silver chloride surface layer and (b) sintered electrode structure. The lower views show the electrodes in cross section. 

---