Solid-electrolyte batteries lithium/iodine

Lithium-iodine batteries 56/19 Table 56.21 Duracell solid electrolyte batteries... 

The high reliability and the complete absence of faults such as electrolyte leakage or gas generation make the lithium-iodine solid state battery a particularly suitable device for powering implanted electronic devices, and it is now widely used in the cardiac pacemaker industry. The design and construction of Medtronic Inc, pacemaker batteries are shown in Fig. 9.12. A typical unit, such as the Enertec Alpha 33 , has dimensions of 33.4 mm X 27.4 mm X 7.9 mm, giving a total volume of 6.0 cm3 and a mass of 22 g. The cell has a completely welded construction and uses a specialized... 

Iodine adducts of nylon-6 formed a battery with Li and lithium iodide solid electrolyte The current efficiency at 500 kil load was about 50% based on the iodine added. Activated carbon fibre (ACF) can also be doped to form a battery with Li ... 

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. 

In contrast to the zinc-air battery, the lithium-iodine solid Lil electrolyte battery will last for almost 15 years. A 120-mAh battery with an initial voltage of 2.8 V drops to 2.6 V when discharged continuously at about 1 pA. The cell is written as... 

Lithium-iodine (Li-Ij) batteries were specifically designed and developed for medical applications. These batteries consistently demonstrated the best performance and suitability, particularly for pacemakers, over a period exceeding 25 years. This particular battery is high in energy density but low in power level. Li-Ij is a low-conductivity solid-state electrolyte, which limits the current to a few microamperes. According to the manufactures, an operational life ranging from 7 to 12 years for this battery has been demonstrated in the field. The battery suppliers claim that these batteries could be used in other applications, such as watches and memory-retention devices. 

The lithium-iodine battery has a solid anode of lithium and a polyphase cathode of poly-2-vitiyl-pyridine (P2VP), which is largely iodine (at 90% by weight). The solid electrolyte is constituted by a thin film of Lil. The discharge reaction is given by... 

Solid electrolyte lithium batteries have been produced for low-drain applications. The Catalyst Research Corporation produce a lithium-iodine solid electrolyte system, rated at 20,uA for heart pacemaker use. 

Lithium iodide pacemaker batteries use lithum iodide as the electrolyte, separating the lithium anode and the iodine anode. The function of the electrolyte is to transport ions but not electrons. Lithium iodide achieves this by the transport of Li+ ions from the anode to the cathode. This transport is made possible by the presence of Li vacancies that are generated by the intrinsic Schottky defect population present in the solid. Lithium ions jump from vacancy to vacancy during battery operation. 

Solid state electrolytes are also used, mainly in special long lasting batteries for extremely low loads, like lithium/LiJ/iodine batteries that are applied in pacemakers. High load batteries are the two examples, in Lines 11 and 12 of Table 1.1, based on sodium as active material in the negative electrodes. Both have been developed... 

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