Electrolytic cell disc stack

BASF in Germany considered the use of the capillary gap cell (see Fig. 2.16 in Chapter 2) for this electrolysis. The cell consists of a stack of carbon discs closely spaced by 0.2 mm thick strips of an insulator. The electrolyte is pumped through the inter-electrode gaps and a voltage is applied to endplates so that a bipolar cell is formed. The cell design is compact, simple and cheap compared with a filter press cell and the tetraalkylammonium concentration could be reduced to below 0.5% without loss of yield and with an energy consumption below 3000 kWh ton . ... 

The pump-cell concept (32) devised by Jansson and coworkers in Southampton Is another variant of the rotating cell. In the simplest version (Fig.4) the process stream enters the thin layer between the rotating disc cathode and the stationary cell body. The electrolyte Is accelerated to high mass transfer rates and the cell becomes self priming. In metal recovery applications the deposited metal film is discharged from the cell in the form of fine powder. It is also relatively straightforward to scale-up this cell design to produce a multiplate bipolar stack a 500-amp version of this cell has been tested. 

Suitable electrolytes for the lithium thermal batteries may be chosen from the low melting eutectics of the lithium halides. Their melting points are from 300 to 350 °C. For improved stability they are mixed with magnesia and compressed to flat discs for assembly into the cell stacks. The eutectic point of the LiCl-KCl electrolyte is at 352 °C and that of a LiCl-LiBr-KBr electrolyte is at 310°C. 

Fig. 2.33 Capillary gap (1 mm) cells, (a) The bipolar capillary gap cell. The electrodes are a stack of closely spaced discs. Electrolyte flows radially outwards in each interelectrode gap. (After Beck, F. and Guthke, H. (1969) Chem.-Ing.-Teck, 41, 943). (b) The monopolar capillary gap cell. The inner cylindrical electrode is concentrically mounted in a confirming tube. (After Eberson, L., Nyberg, K. and Sternerup, H. (1973) Chemica Scripta, 3, 12).

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