Batteries energy storage density

In spite of the great acceleration in battery development since the 1970s, there is still a large gap between the energy storage density readily available (about 100 W hr kg-1) and the theoretical maxima. The latter (see Fig. 13.51) reaches about 500 W hr kg-1 for cells using aqueous solutions at room temperature, and 2000 W hr kg-1 for the high-temperature (molten salt) batteries (Fig. 13.52). 

At the current state of technology, the BEV has range and vehicle mass limitations due to the low energy storage density of batteries, but it shows potential for commercial success in such applications as city buses and small urban vehicles. Nowadays, EREV technology allows the end customers to drive an average distance of 40-80 km/day on electricity without the need for a second vehicle or restrictions to vehicle use. The Voltec technology is therefore a substantial enabler for the widespread use of EVs. 

Electrochemical devices have come in recent years to the forefront in many applications. An example is the provision of electrical energy for electrical vehicles, where high energy storage density is provided by (rechargeable) batteries. Another example is pulsed lasers, where high power, as delivered by supercapacitors, is needed. 

Lithium ion batteries (LIBs) and electrochemical capacitors (ECs) are two important energy storage devices that can complement each other. LIBs work slowly but provide high energy density whereas ECs offer high power density, but suffer from lower energy density [30],... 

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