ultrakondensator

An ultrakondensator, known in English as an ultracapacitor or supercapacitor, is an electrical energy storage device that stores energy primarily by electrostatic charge in an electric double layer, and in some variants by reversible redox reactions (pseudocapacitance). It differs from a battery by offering very high power density and a longer cycle life, but typically holds less energy per unit mass or volume.

There are two main families: electric double-layer capacitors (EDLCs), which store energy in the electric double layer at the electrode–electrolyte interface, and pseudocapacitors, where energy storage involves fast surface redox reactions on the electrode. Hybrid capacitors combine features of both. Typical electrodes are porous carbon materials (activated carbon, graphene, carbon nanotubes) with electrolytes ranging from aqueous to organic and ionic liquids. A separator and current collectors complete the cell.

Performance characteristics include high power density, enabling rapid charging and discharging; long cycle life (often over 100,000 cycles) and wide operating temperature ranges; but lower energy density than lithium‑ion batteries. Practical energy density is generally in the range of several to a few tens of watt-hours per kilogram, while power density can reach kilowatts per kilogram.

Applications include power buffering for automotive start‑stop systems and regenerative braking, uninterruptible power supplies, memory backup, and grid or renewable energy smoothing. Ultrakondensators are not usually a primary energy source but complement batteries or other storage by delivering bursts of power and absorbing pulses.

See also: ultracapacitor, electric double-layer capacitor, energy storage.