Monopolar cells

The lshi2uka cell (39—41), another multipolar cell that has been ia use by Showa Titanium (Toyama, Japan), is a cylindrical cell divided ia half by a refractory wall. Each half is further divided iato an electrolysis chamber and a metal collection chamber. The electrolysis chamber contains terminal and center cathodes, with an anode placed between each cathode pair. Several bipolar electrodes are placed between each anode—cathode pair. The cell operates at 670°C and a current of 50 kA, which is equivalent to a 300 kA monopolar cell. 

In the electrolysis zone, the electrochemical reactions take place. Two basic electrode configurations are used (/) monopolar cells where the same cell voltage is appHed to all anode/cathode combinations and (2) bipolar cells where the same current passes through all electrodes (Eig. 4). To minimize the anodic oxidation of OCL , the solution must be quickly moved out of this zone to a reaction zone. Because the reaction to convert OCk to CIO (eq. 

Monopolar cells operate at low voltages, and may requite high amperages. Industrial citcuits of cells may consist of one hundred or more monopolar cells in series. Monopolar electrodes are used in some membrane chlor-aLkaU cells (Figs. 4 and 5), fluorine cells (Fig. 6), and in metal electrowinning cells (Fig. 7). 

Figure 6.22 Schematic diagrams of electrolytic cells for metal extraction from moltent salts (a-f) monopolar cells.

A cell of this type is called a monopolar cell. In a cell bank, several cells have their negative electrodes and (heir positive electrodes connected... 

Commercial electrolyzers have been developed using both the bipolar and monopolar cell configuration. The cell unit is generally made of metal or corrosion resistant plastics. 

Brown Boveri Cie and Electrolyzer Corporation achieved a main progress in the mid-1980s with respect to the performance of the alkaline monopolar cells. The first company was able to enlarge the efficiency from 2 to 3.4 kA/m2 with 500 m3/h [13], on the other hand the second company that was able to achieve only 1.74 V reached 134 mA/cm2 at 87% efficiency with nickel-boride materials and NiCo204 anodes (prepared from the freeze-dry technique) [14]. 

Figure 9. Traces of intracellular recordings from photoreceptor axon terminals (a and b) while the soma of the cell and the soma of a coupled cell were stimulated by a laser and from a monopolar cell (c) while two coupled photoreceptors were stimulated. Half-second stimuli were used in all three cases. In a and b the photoreceptor that contributes its axon terminal to the same cartridge was stimulated by a laser with increasing intensity, and the voltage was recorded from the impaled terminal. The recordings show that coupling is strong between adjacent axon terminals and also that disparate information is retained and encoded by the monopolar cell.

Bipolar cells are claimed to have superior current density distribution compared to monopolar cells.103 108 However, properly designed monopolar cells should also have uniform current distribution if several contact points are provided between the anode and current collector as well as the cathode and current collector. In the case of bipolar cells, the metal frame is the current collector which results in negligible structural ohmic drop and uniform current distribution. 

When a cell or cell stack contains more than two electrodes, there are two ways of making the electrical connection the cell may be monopolar (Fig. 2.10(a)) or bipolar (Fig. 2.10(b)). In the monopolar cell there is an external electrical contact to each electrode and the cell voltage is applied between each cathode and anode. 

---