Lithium primary batteries design

Lithium primary batteries with liquid cathodes are a relatively mature technology. Incremental improvements in capacity and performance may occur through design modifications and the use of new materials such as improved carbons in the passive cathode. The U.S. Army is adopting Lithium/Manganese Dioxide replacements for some of the Lithium/Sulfur Dioxide Batteries listed in Table 1 in certain applications. These replacements provide higher capacity and energy at room temperature but not at lower temperature. See the chapter on Lithium Primary Cells Solid Cathodes in this work. 

Primary Battery Design, Fig. 3 (Lithium) Wound layers of cathode coated onto a metal current collector with a solid Li foil anode which also serves as a current collector. High rate - newest construction... 

Figure 18.1 and Table 18.1 give an overview on the wide variety of lithium primary systems which have been at least temporarily introduced into the market. This variety gets remarkably wider if one takes into account also all those systems which were tested on the laboratory scale but not fully developed for practical applications. A small selection of lithium primary batteries which were successful in their special markets shall be described in detail here to show some design and building principles. 

Parallel Diodes to Prevent Voltage Reversal. Some battery designers, particularly for multicell lithium primary batteries, add diodes in parallel to each cell to limit voltage reversal. 

Special Considerations When Designing Lithium Primary Batteries... 

Lithium primary batteries contain an anode of elemental lithium (see Chap. 14) and, because of the activity of this metal, special precautions may be required in the design and use of the batteries, particularly when multiple cells are used in the battery pack. Some of the special precautions that should be taken in the design of these batteries, include the following ... 

A listing of the major lithium primary batteries now in production or advanced development and a summary of their constmctional features, key electrical characteristics, and available sizes are presented in Table 14.6. The types of batteries, their sizes, and some characteristics are subject to change depending on design, standardization, and market development. Manufacturers data should be obtained for specific characteristics. The performance characteristics of these systems, under theoretical conditions, are given in Table 14.4. Comparisons of the performance of the lithium batteries with comparably sized conventional primary batteries are covered in Secs. 6.4 and 7.3. Detailed characteristics of some of these batteries are covered in Secs. 14.5 to 14.12. 

In the reserve construction, the electrolyte is physically separated from the electrode active materials until the battery is used and it is stored in a reservoir prior to activation. This design feature provides a capability of essentially undiminished output even after storage periods, in the inactive state, of over 14 years. The reserve feature, however, results in an energy density penalty of as much as 50% compared with the active lithium primary batteries. Key contributors to this penalty are the activation device and the electrolyte reservoir. 

The liquid electrolyte generally requires hermetic sealing, which may reduce the energy density. In addition, for safety reasons, lithium ion rechargeable batteries and lithium-metal primary batteries having liquid electrolytes are designed to vent automatically when certain abuse conditions exist, sucb as a substantial increase in internal pressure which can be caused by internal or external overheating. If the cell is not vented under extreme pressure, it can explode because the liquid electrolyte used in liquid Li cells is extremely flammable. 

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