Pacemaker batteries lithium iodine

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. 

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... 

Fig. 9.13 Projected practical capacity of a lithium-iodine pacemaker battery (Enertec Alpha 33) as a function of current drain. (By courtesy of Medtronic Inc.)...

The lithium-iodine solid-state battery is used exclusively for heart pacemaker. The electrode reactions in this case are very simple, leading to the overall cell reaction ... 

Devices based on electrochemical phenomena represent a multimillion-dollar market annually for health care (15). Applications are probably most important in the sphere of population well-being. For example, experience with heart pacemakers shows that the typical use is for those in the 60- to 80-year age bracket who will lead a relatively active and normal life and have a "statistically average" life expectancy with the assistance of a pacemaker. Without this device, the person would be debilitated and have a life expectancy of only 1 to 2 years. The current market for pacemakers is estimated at nearly 300,000 per year worldwide, about half that in the United States (15). With a battery cost on the order of 100 for an implanted pacemaker, the dollar value ranges from 15 to 30 million for the batteries alone (predominantly lithium-iodine systems). The total cost associated with implanting pacemakers is a hundred times greater. 

Battery Most pacemakers use iithium-iodine batteries. Lithium is the anode and iodine is the cathode. These batteries are ideai for pacemakers because they are iong-iived (5 to 8 years), faii graduaiiy, and do not reiease gases. 

Polymer electrolyte batteries have been used in implanted cardiac pacemakers since 1972. The system used is lithium/iodine-polyvinylpyridine. Although the conductivity of the Li ions in Li2l is poor, the current requirements are very small, and the major consideration is the storage of a high energy density of nearly 1 Whcm . ... 

A very special lithium battery has iodine as anode material. The battery is used for the running of pacemakers (Chapter 12 Lithium). 

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 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... 

Lithium iodine batteries are available mostly in the pacemaker shape, i.e. in that flat nearly semicircle geometry of, e.g. 5 x 30 x 40 mm, with 1 to 3 Ah capacity at a weight of 10 to 30 g. For industrial applications flat rectangular formats are made with contact pins that make them mountable onto electronic boards. Button cells are also realizable. All cells have glass-to-metal seals for both polarities or for the negative one only. A button cell s cross-section is shown in Figure 18.26... 

Figure 18.24 Discharge graph of voltage and inner resistance of an early lithium/iodine pacemaker battery, discharged with the relatively high current of 100 mA (Medtronic).

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. 

TABLE 15.6 WGL Specifications for Lithium/Iodine Pacemaker Batteries... 

The lithium-iodine battery has been used to power more than 3.5 million cardiac pacemakers since its introduction in 1972. During this time the lithirrm-iodine system has established a record of reliability and performance unsurpassed by any other electrochemical power source. 

In the case of pacemaker, power delivery is not a problem because the device itself is of low power consumption and lithium iodine batteries can support a... 

Beginning in 1968, the implantable prototypes of fuel cells intended to power a pacemaker were developed by the American Hospital Supply Corporation [6], the Michael Reese Hospital [8], Siemens [13], and Tyco [14]. Industries also invested in the organochemical redox systems in order to develop devices that are able to oxidize not only glucose but also other fuels, such as amino acids [15]. However, the introduction of lithium iodine batteries as a power supply for pacemakers, and the improvement in its lifetime, led to a change in the direction of the application of glucose/02 fuel cells toward sensor technology [16,17]. 

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. 

Since 1972, the Catalyst Researeh Corporation (USA) has been the supplier of the lithium-iodine batteries intended initially for eardiae paeemakers and other implantable deviees. They supply 70% of pacemaker batteries used in the world. They elaim that the capacity of this battery is four times that of the Mallory RM-I mereury-zine paeemaker battery and that the lithium-iodine battery operates more efficiently at body temperature than at room temperature. Since the lithium-iodine reaetion generates no gas, the cell can be hermetieally sealed. A feature of this type of battery is its extremely high reliability. At the time of writing, Catalyst Researeh had supplied 150000 batteries for use in eardiae paeemakers without a single failure or premature rundown. Catalyst Researeh Corporation lithium-iodine batteries are marketed in the UK by Mine Safety Appliances Ltd. 

Table 9.14 Characteristics cf Catalyst Researeh Corporation nrdd 602/23 solid lithium-iodine pacemaker battery...

Catalyst Research Corporation (USA) is a major manufacturer of lithium—iodine batteries used for pacemaker and other applications. The Catalyst Research Series 800 cells use the lithium envelope concept. The cell is constructed with a centrally located cathode current collector and a lithium envelope which surrounds and contains the iodine depolarizer material (Figure 24.14). This depolarizer material is corrosive to the stainless steel case and must be kept irxnn contacting the case for maximum cell life. A second barrier, formed from fluorocarbon plastics, surrounds the lithium envelope, insulates it from the case, and provides a second envelope for the containment of the depolarizer. The corrosive effect of iodine-containing depolarizer on stainless steel is lower than that of depolarizer made with more active halogens, such as bromine or chlorine. 

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. 

Since 1972, Catalyst Research Corporation has been the supplier of lithium-iodine batteries for cardiac pacemakers and other medical implantable devices and, more recently, for other applications of these batteries. 

These researches opened the door to the fabrication and commercialization of varieties of primary hthium batteries since the late l%0s nonaqueous hthium cells, especially the 3-V primary systems, have been developed. These systems include lithium-sulfur dioxide (Li//S02) cehs, lithium-polycarbon monofluoride (Li//(CF t) ) cells introduced by Matsuschita in 1973, lithium-manganese oxide (Li//Mn02) cells commercialized by Sanyo in 1975, lithium-copper oxide (Li//CuO) cells, lithium-iodine (Li//(P2VP)1J cells. During the same period, molten salt systems (LiCl-KCl eutecticum) using a Li-Al alloy anode and a FeS cathode were introduced [1]. The lithium-iodine battery has been used to power more than four million cardiac pacemakers since its introduction in 1972. During this time the lithium-iodine system has established a record of reliability and performance unsurpassed by any other electrochemical power source [18]. 

From the first pacemaker implant in 1958 by Dr Ake Senning surgeon at the Karolinska Hospital in Stockholm, numerous engineering developments have faced challenges in battery power. In 1972, a primary lithium-iodine battery replacing the mercury-zinc cells greatly extended the cardiac pacemaker life (about 10 years). More details on the history of this battery can be found in ref. 

The semiconductive properties and tunnel structure of sulfide and transition-metal oxides led to the use of these materials in lithium power sources (Table 2.5). Several lithium-based chemistries were successfully applied to replace the prior system Zn/AgO and later the lithium-iodine batteries in implantable medical devices [59-61]. For example, Li//CuO, Li//V205, Li//CF and more recently Li// Ag2V40ii couples have been adopted to power cardiac pacemakers requiring less that 200 pW [62,63]. The lithium/carbon monofluoride (Li//CFJ primary cells are very attractive in several applications because of the double energy density with respect to the state-of-the-art LiZ/MnOa primary batteries (theoretically 2203 against 847 Wh kg ). 

Lithium iodide is the electrolyte in a number of specialist batteries, especially in implanted cardiac pacemakers. In this battery the anode is made of lithium metal. A conducting polymer of iodine and poly-2-vinyl pyridine (P2VP) is employed as cathode because iodine itself is not a good enough electronic conductor (Fig. 2.3a). The cell is fabricated by placing the Li anode in contact with the polyvinyl pyridine-iodine polymer. The lithium, being a reactive metal, immediately combines with the iodine in the polymer to form a thin layer of lithium iodide, Lil, which acts as the electrolyte ... 

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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