If a system has a high energy density then it is able tostore a lot of energy in a small amount of mass. A high energy density does not necessarily mean a high power density. An object with a high energy density, but low power density can perform work for a relatively long period of time. What material has the highest energy density?
For example, Fuel cells will have very high energy densities, with relatively low power densities. If a system has a high power density, than it can output large amounts of energy based on its mass. For example, a tiny capacitor may have the same power output as a large battery.
For energy storage, the energy density relates the stored energy to the volume of the storage equipment, e.g. the fuel tank. The higher the energy density of the fuel, the more energy may be stored or transported for the same amount of volume. The energy of a fuel per unit mass is called its specific energy.
Energy density is the amount of energy in a given mass (or volume) and power density is the amount of power in a given mass. The distinction between the two is similar to the difference between Energy and power. Batteries have a higher energy density than capacitors, but a capacitor has a higher power density than a battery.
Despite being one of the highest energy density energy storage devices, the energy density of LIB is still significantly less than that of gasoline. Hence, the number of LIB cells required for achieving a driving range of 200–300 miles is more.
For example, a tiny capacitor may have the same power output as a large battery. However, since the capacitor is so much smaller, it has a higher power density. Since they release their energy quickly, high power density systems can also recharge quickly. An example application of this type of energy storage is a camera flash.
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When discussing the chemical energy contained, there are different types which can be quantified depending on the intended purpose. One is the theoretical total amount of thermodynamic work that can be derived from a system, at a given temperature and pressure imposed by the surroundings, called exergy. Another is the theoretical amount of electrical energy that can be derived from