Lithium-iodine cells

Lithium hydroxide, 15 134, 140-141 Lithium hypochlorite, 4 52 15 141 pool sanitizer, 26 175 Lithium iodide, 3 417 15 140 Lithium-iodine cells, 3 463-464 characteristics, 3 462t speciality for military and medical use, 3 430t... 

Lithium-iodine cells are produced simply by making direct contact between anode and cathode. On touching, a thin layer of lithium iodide is formed by direct reaction. As soon as the layer becomes complete, the reaction rate decreases sharply, since diffusiou of iodine through lithium iodide is very slow. Thus the cell may be written as... 

Solid Cathode Cells. Solid cathode cells include lithium-manganese dioxide cells, lithium carbon inonofluoridc cells, lithium iron disulfide cells, and lithium—iodine cells. 

The maximum power density is also developed in cells with liquid oxidants 50-100 W/kg and 70-200 W/dm. The minimum power density is characteristic for lithium iodine cells designed for continuous operation for 10 years and more. 

Primary lithium cells compare favorably with cells with aqueous electrolytes because of their very good shelf life in other words, very low self-discharge. The best shelf life is characteristic for lithium iodine cells, in which the capacity loss under storage for 10 years at the temperature of 40°C does not exceed 10% The guaranteed shelf life (under due conditions) of lithium cells with other electrochemical systems is... 

The requirements for a heart pacemaker power supply are quite different (see Table 10.3). A primary cell will suffice and it need only have a power output of a few microwatts (jliW) but this must be supplied continuously for several years without maintenance and with absolute reliability. It must also be compatible with the body and operate at 37.4°C. Lithium/iodine cells are presently used for this application. 

The first lithium/iodine cardiac pacemaker battery was implanted in 1972. This type of battery proved to be very successful in this field and for other applications, too. The special features of this solid state battery are explained with its technique, which is limited with its extremely high energy density and reliability, especially for low rate applications. This technique is based firstly on the electrode couple of lithium and iodine with its high energy content - the OCV of the lithium/iodine cell is 2.80 V -and secondly on the favorable fact that the product of the cell reaction, the lithium iodide (LiJ), forms very tight and continuous layers between the active material of the electrodes, which are acceptable ionic conductors with negligible electronic... 

Give two advantages of a lithium/iodine cell compared with an ordinary dry cell. 

Figure 24.14 Catalyst Research Corporation model 802/803 solid lithium-iodine cell (Courtesyof Catalyst Research Corporation)...

Two main types of medical pacemaker lithium-iodine cells are manufactured ... 

The lithium-iodine cell is an example of a highly reliable lithium power source, proven in the pacemaker industry. It is used in security, space and defence systems and, more recently, CMOS-RANI data retention applieations. It is available in several sizes, suitable for watehes (LCD and analogue stepping motor) and for low-eurrent LCD calculators. Life spans as long as... 

The lithium-iodine combination has been used for most implanted cardiac pacemakers since 1972. It thus has a believable reliability history, at least at human body temperature. Because of its critical main use, the lithium-iodine cell comes in a hermetically sealed (laser-welded) nickel or steel container, which makes it more expensive than other types ( 5-8 for the 200-350mAh coin-shaped cells). Yet the high quality of the chemical processing and encapsulation makes it a good choice where very long shelf life (10 years and beyond) is the objective. 

Hazardous incidents have been experienced with some lithium systems, particularly those using sulphur dioxide and thionyl chloride cathodes. These incidents generally occur at later stages in battery life under reverse current conditions, during voltage reversal and while operating at high temperatures. Safety incidents have not been experienced with lithium-iodine cells, which is why they power 90% of the cardiac pacemakers presently in use. 

The 900 Series Lithiode lithium-iodine implantable medical cell manufactured by Catalyst Research represents the latest innovation in lithium-iodine batteries. The innovation is in the cell s internal construction. Instead of using a cooked-and-cast cathode, as employed in the earlier 700 and 800 series of Catalyst Research lithium-iodine cells, the 900 series utilizes a unique pelletized cathode. 

All components of the cell are solid, including the cathode. This precludes cathode migration to the anode current collector, a possible latent failure mode in other lithium-iodine cells. 

Figure 56.21 Projected performance of Catalyst Research Corporation Lithiode TM lithium-iodine cells based on 5 years test data, (a) Voltage under 190kn load, (b) voltage under load (Courtesyof Catalyst Research Corporation)...

Figure 56.22 Configuration of Eagle Richer lithium-iodine cells (Courtesyof Eagle Richer)...

The full range of Catalyst Research Series 900 pacemaker lithium—iodine cells is shown in Table 56.23. A diagrammatic representation of one of the cells in this series (Model 901) 5 shown in Figure 56.22. Projected performance curves for a single anode cell in this range ace shown in Figure 56.23. Included in the... 

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