Iodine cathode, complexed

The poly-(2-vinyl pyridine) is present in the cathode to solubilize the iodine via a complexation facilitating its diffusion. On fabrication, the cathode sheet, an iodine complex in a mixture with excess elemental iodine, is pressed against the Li metal anode. On contact a thin passivating, but Li-ion conductive, film of Lil is formed. It fails to grow further until the circuit is closed. Because the conductiv-... 

Electrochemical methods are being used increasingly in the carotenoid field. Electroreduction of /3,/3-carotene (62) at a mercury cathode gave 7,7 -dihydro-8,7 -retra-/3, -carotene (81). Similarly axerophtene (82) gave the 7,14-dihydro-product (83). Reductive electrochemical dehydrohalogenation of a j8-caro-tene-iodine complex prepared from jS-carotene with iodine and trifluoroacetic... 

A typical rechargeable battery based on this idea has been constructed. It uses the [Ni(TTL)]a, polymer as the anode, poly-2-vinyl-pyridine-iodine (P2VP (x/2)l2) (68) complex as the cathode, and aqueous KI solution as the electrolyte solution (Equation 13). In the discharging process, electrons flow from the anode [Ni(TTL)]a to the cathode P2VP (x/2)l2 through the load circuit the iodide (or polyiodide) ions formed at the cathode then enter the electrolyte while an equivalent amount of iodide ions from the electrolyte solution intercalate into the oxidized metal tetrathiolene polymer (anode). The electrolyte concentration is therefore conserved. Upon recharging with an opposite... 

The results of Suer and Lifvergren (2003) indicate that mercury was removed from a field-contaminated soil by a combination of redox and complexation processes with iodide/iodine and electrokinetic mobilization. Iodide added to the cathode compartment was transported into the soil and oxidized to iodine near the... 

Cross-linked polymers produced in this way cannot be worked easily. In this respect, charge transfer complexes from polymeric donors and acceptors are more advantageous. The poly(2-vinyl pyridine) and iodine complex, for example, has a specific conductivity of 10 H" cm . It is used as a cathode in Li/h batteries for implantable heart pacemakers. This solid state battery has a higher energy density than the best lead accumulators and a lifetime of about ten years. 

Comparatively little work on copper batteries has been reported. The substitution of silver by copper in RbAg I does not exceed 0.34 wt % and cells of/this electrolyte with copper anodes behaved in an unstable fashion. Preliminary cell measurements have also been reported using NN dimethyl triethylene-d gj ne dibromide - cuprous bromide in conjunction with copper anodes. With charge transfer complex cathodes (Br -perylene, iodine-perylene) the cells were unstable as the halogen oxidised the CuBr (or Cul) reaction product to the Cu state. With a stable behaviour was observed. 

A dry cell is not truly dry, because the electrolyte is an aqueous paste. Solid-state batteries have been developed, however. One of these is a lithium-iodine battery, a voltaic cell in which the anode is lithium metal and the cathode is an I2 complex. These solid-state electrodes are separated by a thin crystalline layer of lithium iodide (Figure 20.11). Current is carried through the crystal by diffusion of Li" ions. Although the cell has high resistance and therefore low current, the battery is very reliable and is used to power heart pacemakers. The battery is implanted within the patient s chest and lasts about ten years before it has to be replaced. 

The anode is lithium metal and the cathode is a complex of iodine, I2 the electrodes are separated by a thin crystalline layer of lithium iodide.The battery consists of two cells enclosed in a titanium shell. 

Lithium-iodine battery a voltaic cell in which the anode is lithium metal and the cathode is an I2 complex. (20.8)... 

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