High-Power Energy Storage: Ultracapacitors

Electrical energy-storage technologies have substantially revolutionized communications and transportation of our society, facilitating the massive adoption of portable electronic devices and electrified vehicles, and freeing us from being tethered to the grid. Utracapacitors (UCs), also referred to as supercapacitors (SCs) or electric double-layer capacitors (EDLCs), have attracted increasing attention as energy-storage systems (ESSs), due to their high power density, high efficiency, fast charge, wide temperature window, and excellent recyclability. These advantages make UCs well-suited for working independently or in tandem with high-energy ESSs (e.g., fuel cells, lithium-ion batteries) for power sourcing/delivering in electrified vehicles. In particular, combination with a high-energy ESS provides a hybrid energy-storage system (HESS) that can fully leverage the synergistic benefits of each constituent device. To ensure efficient, reliable, and safe operation of UC systems, numerous challenges including modeling and characterization and state estimation should be effectually surmounted.