Energy density of batteries

Figure 4.6 In the last 15 years, the energy density of batteries has increased 5.8-fold.

For smaller power requirements (e.g. flash lights, toys and so forth) or short-duration loads (for instance in car starter batteries) the inherent disadvantages of batteries are insignificant. With increasing performance and operation time, however, the small energy density of batteries is a considerable restraint and fuel cells may be better suited for the application since the size of the converter (fuel cell) and the size of the energy storage (tank) can be scaled independently. 

Zheng, J. R 2003. The limitations of energy density of battery/double-layer capacitor asymmetric cells. Journal of the Electrochemical Society 150 A484-A492. 

The slim or flat rectangular batteries are designed to meet the needs of lightweight and compact equipments. The rectangular shape permits more efficient battery assembly, eliminating the voids that occur with the assembly or cylindrical batteries. The volumetric energy density of batteries can be increased by a factor of about 20%. 

Na + NaAia4 4NaCl + A1 Table 21.2 Theoretical energy densities of batteries. 

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