Electric Double Layer Capacitors: A Review

A review of modern scientific literature on the electric double layer capacitors based on the recharging of the electric double layer is presented. The electric double layer capacitors are used in pulse technology devices, as electric energy storage devices, for starter firing, for the recuperating of the braking energy of internal combustion engines, for smoothing peak loads in electric networks, and in various portable devices. The electric double layer capacitors are subdivided into the power electric double layer capacitors and the energy ones. The power (pulse) electric double layer capacitors have a high specific power (up to hundreds of kW/kg), whereas the energy electric double layer capacitors have a high specific energy (~25 W h/kg and higher). Compared to batteries, the power electric double layer capacitors have a much higher power density and better cyclability—up to hundreds of thousands and millions of cycles. Publications on the electric double layer capacitors’ self-discharge are reviewed.