Supercapacitor

A supercapacitor, also called an ultracapacitor, is an energy-storage device that sits between an ordinary electrolytic capacitor and a rechargeable battery, able to store 10 to 100 times more energy per unit of mass or volume than an electrolytic capacitor while charging and discharging much faster than a battery. Rather than the solid dielectric of an ordinary capacitor, it stores charge using electrostatic double-layer capacitance and electrochemical pseudocapacitance across two electrodes separated by an ion-permeable membrane and connected through an electrolyte, building up charge at the boundary between each electrode and the electrolyte. General Electric researchers experimented with porous carbon electrodes for the concept in the 1950s, NEC brought the first commercial supercapacitors to market in 1978 for backing up computer memory, and through the late 1970s and 1980s the researcher Brian Evans Conway did much of the work distinguishing supercapacitor behavior from battery behavior, including work with ruthenium oxide electrodes, and gave the device its modern name by the late 1990s.