Capacity and Energy Density Aspects

In spite of the extraordinarily high ionic conductivity of silver- and copper-ion conductors, these materials suffer from their low capacity and energy density. In addition, only a few positive electrode materials have been found until now. 

Some fluorine-ion conductors exhibit high ionic conductivities, even at room temperature [4], which are not equaled by other haUde-ion conductors. However, 

3Alo3Til.7(P04)3 7 X 10- 3 (total) 0.35 (total) 150°C Cold-pressed samples, sintering temperature 980-1000°C [18] 

5LiTa03-0.5SrTi03 5 X IQ- (bulk) 0.33 (bulk) 150 °C Cold-pressed samples, sintering temperature 1350-1400 °C [20] 

51TiO2.94 10-3 7 5 X 7Q-3 (grain-b.) 0.40 (bulk) 0.42 (grain-b.) 100°C Cold-pressed samples, sintering temperature 1200 C [21, 22] 

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Figures 1.27-1.29 illustrate the interrelationship of discharge time with discharge current, end-point e.m.f.. A h capacity and energy density. Thus, if 2 min and 30 rnin discharges are adopted, the effect of this on the above parameters would be as illustrated in Table 1.21. Information of this kind enables trade-offs to be made in the various aspects of battery performance.

Another aspect of battery performance can be studied by preparing plots of discharge current against end-point e.m.f. and electrical resistance (Figure 1.30) and Ah capacity and energy density (Figure 1.31). 

The Li/SOCIj ceUs 5n- 3) (Mallory (USA), GTE (USA), Honeywell (USA) ) use LiAlCl4,/SOCl2 as the electrolyte solution the open-circuit voltage is 3.6 V available capacities range from 0.8 to 10.8 A h at energy densities of about 660 W h/kg Studies on the cell reaction and further aspects of the chemistry... 

An optimal SEI layer formation not only minimizes the irreversible capacity, and thus the energy density of the cell, it also affects the cycling stability, rate capabiUty, and safety aspects of the cell. hi addition, an effective SEI layer suppresses the electrochemical exfoliation of graphite caused by the co-intercalation of solvated Uthium between the graphite layers. The unstable solvated Uthium intercalation compound formed as a short-living intermediate is decomposed... 

Material properties can be further classified into fundamental properties and derived properties. Fundamental properties are a direct consequence of the molecular structure, such as van der Waals volume, cohesive energy, and heat capacity. Derived properties are not readily identified with a certain aspect of molecular structure. Glass transition temperature, density, solubility, and bulk modulus would be considered derived properties. The way in which fundamental properties are obtained from a simulation is often readily apparent. The way in which derived properties are computed is often an empirically determined combination of fundamental properties. Such empirical methods can give more erratic results, reliable for one class of compounds but not for another. 

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