Melting electrolytes

For this reason a lower melting electrolyte was sought, one which would melt below 350 °C. Potassium pyrosulfate, K2S207, was a natural choice though thermally unstable above 300 °C in the absence of S03,... 

Table VII gives the m.p. of other alumohalides and their mixed systems. For example, low-melting electrolytes based on AlCla MCl chloraluminates, where M is Li, Na, K, have been considered (87), and cells with A1 anode and various cathodes, both inorganic and organic, were tested. The sulfur cathode seems to be the most suitable, although complex chlorides, fluorides and sulfides show possibilities. An experimental Al/S cell is described in detail in (88). The reaction 2A1 + 3S = AI2S3 provides a TED of 1275 Wh/kg at 200°. It is viewed only as a primary battery, however at the present time (88).

In order to araise current yield of carbon phase it is advisable to use more low-melting electrolytes. For this purpose the electrolysis of C02 in the ternary eutectic Na,K,Cs Cl at temperature 500 C was carried out. In this system carbon current yield was arisen up to 80 % and the cathode product contained fullerenes phase (according to X-ray analysis) together with carbon phases obtained in NaCl - KC1 melt. 

Different salt additions to the electrolyte improve its physicochemical properties melting temperature, electrical conductivity, density, interfacial tension, etc. The general trend is to use low melting electrolytes to obtain higher current efficiencies. 

Most metals can be electrolytically deposited from water-free melts of the corresponding metal salts. It is well known that aluminum, lithium, sodium, magnesium, and potassium are mass produced by electrolytic deposition from melts. Industrial processes for the melt-electrolytic production of beryllium, rare earth metals, titanium, zirconium, and thorium are also already in use. Pertinent publications [74, 137, 163] describe the electrolytic deposition of chromium, silicon, and titanium from melts. Cyanidic melts are used for the deposition of thick layers of platinum group metals. It is with this technique that, for instance, adhesion of platinum layers on titanium materials is obtained. Reports concerning the deposition of electrolytic aluminum layers [17, 71-73, 94, 96, 102, 164, 179] and aluminum refinement from fused salts [161] have been published. For these processes, fused salt... 

M. B. Herath, S. E. Creager, R. V. Rajagopal, O. E. Geiculescu, D. D. DesMarteau, Electrochim. Acta 2009, 54, 5877-5883. Ionic conduction in polyether-based lithium aryl-fluorosulfonimide ionic melt electrolytes. 

The most attractive candidates for electrodes are thus a combination of an alkali metal (possibly an alkaline earth metal) anode with a halogen or chalcogenide cathode. These might well be immersed in a eutectic alkali metal halide melt electrolyte. 

At Stanford University in California, Lee et al. (2008) showed the possibility of using a fluidized-bed cell with a carbonate melt electrolyte for the oxidation of various pulverized carbon materials. 

Cassayre, L., Palau, R, Chamelot, P. and Massot, L. (2010) Properties of low-temperature melting electrolytes for the aluminum electrolysis process a review. J. Chem. Eng. Data, 55(11), 4549-4560. 

Another aim of the present work is to determine the influence of electrodeposition conditions (applied current density, deposition time, ratio of PC on-time/off-time) on the quality of deposited layers in such melting electrolytes. DC and PC techniques are used to prepare the titanium electrocoatings. 

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