Different sources of energy in electric vehicle?

Three main sources of energy or electricity for hybrids are batteries, Fuel Cells, and capacitors. Each device has a low cell voltage, and, hence, needs many cells in series to obtain the voltage demanded by an HEV. The difference in the source of energy can be explained below as:

a. The fuel cell provides high energy but low power.
b. The battery supplies both modest power and energy.
c. The capacitor supplies very large power but low energy