Batteries specific energy

Table 1.8 Open circuit voltage (OCV) and specific energy values for different types of battery. Specific energy values for USABC and gasoline...

Battery Specific Energy Specific Power Cycle life... 

In this chapter, we have sketched the broad outlines of the research being conducted to improve the electrical performances of lithium-ion batteries (specific energies and lifetime). In parallel to these developments on lithium-ion technology, lithium-sulfur and lithium-air batteries are in an examination phase and should, in the coming years, become a viable competitor for lithium-ion batteries. They are examined in Chapters 9 and 10. 

Figure 10.18 Range of electric vehicles depending on the speed and battery specific energy.

The alkali metals lithiirm and sodium are attractive as battery anodes on account of their high electrode potentials and their low atomic masses, which together result in excellent values for the battery specific energy. In this chapter we consider batteries which utilize solids (fast ion conductors) or fused salts as electrolytes and which operate at temperatures of 200 to... 

Calculations show that battery specific energies of around 100-150Wh/kg and peak power capabilities of 120W/kg" are needed for traffic compatible electric delivery vans with worthwhile ranges, with even more demanding requirements for smaller vehicles such as automobiles. 

Li—Al/FeS cells have demonstrated good performance under EV driving profiles and have deUvered a specific energy of 115 Wh/kg for advanced cell designs. Cycle life expectancy for these cells is projected to be about 400 deep discharge cycles (63). This system shows considerable promise for use as a practical EV battery. 

Regarding the specific energy, i.e., the electric energy per mass, a major distinction can be made between today s aqueous and nonaqueous battery systems [15]. Apart from batteries for some special applications, there are... 

Apart from applications in sensors [21, 22], divalent-ion conductors, e.g., for Mg2+ ions, are of great interest for thin film batteries which may be incorporated into microelectronics as memory backups and into other applications. For these batteries high volumetric specific energy densities rather than high current densities are required, and thin films offer in addition a major decrease in the total ionic resistance. 

This distribution causes a problem the best-described conducting polymers interchange anions with the electrolyte, and the Li electrode liberates Li+during discharge. The salt accumulates in the electrolyte [Fig. 32(a)], requiring a great volume and mass in order to avoid the precipitation of the salt. This fact reduces the specific energy of the battery to impractical values. 

New materials can improve the specific energy of the automobile battery, which is attracting most of the scientific effort. Nevertheless, an increase in specific power can only be obtained by a good understanding of the structural and molecular aspects that affect the electrochemistry of these materials. 

A sodium-sulfur cell is one of the more startling batteries (Fig. 12.23). It has liquid reactants (sodium and sulfur) and a solid electrolyte (a porous aluminum oxide ceramic) it must operate at a temperature of about 320°C and it is highly dangerous in case of breakage. Because sodium has a low density, these cells have a very high specific energy. Their most common application is to power electric... 

Widely used parameters are the specific energy or power per unit mass (w = W/M, in Wh/kg, orp = P/M, in W/kg). In each battery type the specific energy is a falling function of specific power. Plots of w vs. p (Ragone, 1968) yield a clear illustration of the electrical performance parameters of given types of batteries and are very convenient for their comparison (see Fig. 19.4). 

FIGURE 19.4 Dependence of the specific energy w with respect to mass on the specific discharge power p for various heavy drain batteries the straight lines correspond to different times of full discharge x = 100 h (a) 10 h (i>) 1 h (c) 6 min (d). 

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