Electrochemical Supercapacitors (a Review)

Contemporary scientific literature on electrochemical supercapacitors is reviewed. The electrochemical supercapacitors are fast-rechargeable energy storage devices. They are classified as electrical-double-layer capacitors based on the recharging of the electric double layer; pseudocapacitors, and hybrid capacitors. The electrochemical supercapacitors are used in devices of pulse technology, for electrical energy accumulation, for starting and recuperation of the braking energy in internal combustion engines; for smoothing out peak loads in electrical networks and in numerous portable devices. The electrochemical supercapacitors are subdivided into those of power type and energy type. The power-type (pulsed) supercapacitors have high specific power (~up to 100 kW/kg); the energy-type ones, high specific energy (~up to 25 W h/kg). Compared to batteries, the power-type supercapacitors have a much higher power density and cyclability, up to hundreds of thousands and even million cycles. The electrical-double-layer supercapacitors are also used in the capacitive water deionization devices for water desalination.