and what is kinetic energy spectrum?
Energy density is the amount of energy per unit of volume. So if I have 10 joules of energy stored in a capacitor, and the capacitor has a volume of 0.001 cubic meters, then the capacitor has an average energy density of 10 / 0.001 = 10 000 joules per cubic meter (for the electrical energy it stores, that is).
From a layman who has wandered in from the sticks, thank you. I glimmer of light for me.
Can I apply the above reasoning to say a lithium battery? i.e. convert the stated battery capacity in ampere hours and use the physical dimensions to arrive at an "energy density" for said battery, assuming I get my sums right?