How an Ultracapacitor Works

http://www.nrel.gov/vehiclesandfuels/energystorage/ultracapacitors.html

Ultracapacitors

Like batteries, ultracapacitors are energy storage devices. They use electrolytes and configure various-sized cells into modules to meet the power, energy, and voltage requirements for a wide range of applications. But batteries store charges chemically, whereas ultracapacitors store them electrostatically. Currently, ultracapacitors are more expensive (per energy unit) than batteries. Ultracapacitors are true capacitors in that energy is stored via charge separation at the electrode-electrolyte interface, and they can withstand hundreds of thousands of charge/discharge cycles without degrading. They provide quick bursts of energy.

NREL – National Renewable Energy Laboratory

Advanced Vehicles and Fuels Research

Energy Storage

How a Battery Works

http://www.nrel.gov/vehiclesandfuels/energystorage/batteries.html

Batteries

A conventional vehicle uses a lead acid battery to start the engine and power auxillary loads (lighting, electronics, etc.). Hybrid electric, electric, and fuel cell vehicles (HEVs, EVs, and FCVs) have conventional lead acid batteries, but also have propulsion batteries, which are constructed quite differently—they are built for high power, high energy, and long cycle lives. Some low-voltage hybrid vehicles use advanced lead acid batteries, known as valve regulated lead acid (VRLA) batteries.

NREL – National Renewable Energy Laboratory

Advanced Vehicles and Fuels Research

Energy Storage