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Lithium has the highest specific energy of all but it has only become possible comparatively recently to manufacture practical batteries. Because lithium reacts violently with water, non-aqueous electrolytes must be used. Organic solvents such as acetonitrile and propylene carbonate, plus inorganic solvents such as thionyl chloride (SOCl2) are typical, with a compatible solute to provide conductivity. Many different materials such as sulfur di, thionyl chloride, manganese dioxide, and carbon monofluoride, are used for the active cathode material.
In addition to their widespread use in consumer products, lithium primary batteries are the power source of choice for a range of medical implants. For cardiac demand pacemakers, the cell now in general use has a lithium anode with a conducting charge transfer complex formed by iodine and poly-2-vinyl-pyridine as cathode. A lithium-iodine cell was first described in 1967 and the first proposal for its use as a pacemaker power supply was made subsequently by Wilson Greatbatch and co-workers. In contrast to the low rates required in pacemakers, implanted defibrillators are required to deliver shock currents of 30J, and the battery has to charge a capacitor at a power level of over 3W. The cell for this application is based on the lithium-silver vanadium oxide (Ag2V4O11) couple with a liquid organic based electrolyte. The original battery chemistry was developed by Charles Liang and co-workers. The current status of battery has recently been described by Ann Crespi, Paul Skarstad and colleagues at Medtronic.
The highest power lithium primaries have cathodes based on soluble (SO2) or liquid (SOCl2 and SO2Cl2) cathodes. These are generally used for specialized commercial, aerospace or military applications. For example, the NASA Galileo probe which, following a flight of over six years, investigated the atmosphere of Jupiter in December 1995, used three batteries each made up of 13 lithium-sulfur dioxide cells. These delivered 18Ah, mainly in the last hour of the mission, and following deceleration forces of over 360G. Much larger batteries based on similar chemistry are used for torpedoes, rescue submarines and other underwater applications. A high rate 330Ah lithium-thionyl chloride battery weighing 35kg and with a volume of under 20dm-3 was developed for the Centaur/Titan launch vehicle by Alliant Tech Systems.
Of the many types now available, most have a long shelf life and a wide operating temperature range. For small format battery applications that require high power and high energy density, the only solution available to the military is the use of expensive primary batteries containing lithium-sulfur dioxide or lithium-manganese dioxide cells (e.g. BA5590). High operating costs limit wider use of these batteries.
The Table you can see here lists, in order of increasing open circuit voltage, the properties of selected non-rechargeable lithium D size batteries, which are available commercially. The zinc-manganese dioxide (alkaline) system is taken as a reference point for discussion purposes. Nominal load voltage is included in the table because many types of battery operate at an appreciably lower voltage than the open circuit value (the load voltage will steadily decrease as the load increases).
The energy delivered by the various battery systems is expressed in terms of weight (gravimetric), also called specific energy, or volume (volumetric). These figures are for actual commercial cells, so they include all the cell hardware. The power density figures do not represent the maximum power (pulse power) that can be generated but are based on manufacturers data for the maximum recommended continuous current possible.
It is desirable to have as high a specific energy as possible and the lithium systems can be seen to be far superior to the alkaline cells. Lithium is the lightest metal and is readily oxidized, which makes it highly desirable for use in batteries. Lithium vigorously dissolves in water and even reacts with nitrogen in the air. For this reason it is only in recent years that lithium battery technology has been developed using non-aqueous electrolytes.
Most are available in a high rate spirally wound format, as well as the lower rate bobbin and button formats. The higher rate cells are equipped with a safety vent to relieve any high internal pressure if such a problem should occur. The nature of the vented materials may need to be considered in certain applications, because of the inflammable or corrosive nature of the electrolyte.
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