Lithium Alloys as an Alternative

This is a common problem when using elemental lithium negative electrodes in contact with electrolytes containing organic cationic groups, regardless of whether the electrolyte is an organic Uquid or a polymer [4]. 

In order to achieve good rechargeability, one has to maintain a consistent geometry on both the macro and micro scales and avoid electrical disconnection of the electroactive species. 

Attention has been given for some time to the use of lithium alloys as an alternative to elemental lithium. Groups working on batteries with molten salt electrolytes that operate at temperatures of 400-450 °C, well above the melting point of lithium, were especially interested in this possibility. Two major directions evolved. One involved the use of Hthium-aluminum alloys (5, 6], while the other was concerned with lithium-silicon alloys [7-9]. 

In practical cases, however, the excess weight and volume due to the use of alloys may not be very far from those required with pure lithium electrodes, for one generally has to operate with a large amount of excess lithium in rechargeable cells in order to make up for the capacity loss related to the filament growth problem 

The first use of hthium alloys as negative electrodes in commercial batteries to operate at ambient temperatures was the employment of Wood s metal alloys in lithium-conducting button-type cells by Matsushita in Japan. Development work 

Lithium alloys have been used for a number of years in the high-temperature thermal batteries that are produced commercially for military purposes. These devices are designed to be stored for long periods at ambient temperatures before use, where their self-discharge kinetic be- 

It was also shown in 1983 [11] that lithium can be reversibly inserted into graphite at room temperatures when a polymeric electrolyte is used. Prior experiments with liquid electrolytes were unsuccessful due to co-intercalation of species from the organic electrolytes that were used at that time. This problem has been subsequently solved by the use of other electrolytes. 

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Lithium has been proposed as an alternative metallic fuel for IRCM flares [53]. Hahma has developed a series of compositions based on ZrW alloy with both Bi203 and PTFE as oxidizers. These payloads deliver low specific energy in both A and B band at static conditions and sea level (A. Hahma, personal communication) [54]. 

The electrolyte for the battery is a LiCl/KCl mixture with a temperature of 430—490°C. Batteries are constructed on the parallel-plate principle with alternate anodes and cathodes, and in each inter-electrode space there is a boron nitride cloth or felt separator. Commonly there is one extra negative plate because some lithium is lost during cycling. The plates, typically 5 mm thick, were initially prepared by cold compaction techniques, the active material being compressed into a fine metal lioneycomb material which also acts as the current collector. The negative electrode was just the li/Al alloy in an Fe lattice while the positive electrode was a mixture... 

The lithium is in the form of an alloy with magnesium or aluminium which retains much of the tritium until it is released by treatment with acid. Alternatively the tritium can be produced by neutron irradiation of enriched LiF at 450° in a vacuum and then recovered from the gaseous products by diffusion through a palladium barrier. As a result of the massive production of tritium for thermonuclear devices and research into energy production by fusion reactions, tritium is available cheaply on the megacurie scale for peaceful purposes. The most convenient way of storing the gas is to react it with finely divided uranium... 

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