From Electrochemical Capacitors to Supercapatteries

Abstract

The enormous technical developments and rapid changes in life patterns made in the recent decades have largely been attributed to the exploitation of contemporary forms of energy sources, i.e. fossil fuels. However, their finite availability and significantly high environmental impacts have aroused concerns and spurred research to find alternatives and more efficient ways to store energy. In particular, recent developments of batteries and fuel cells as energy storage devices have been proven to be very promising, but their poor power characteristics and cyclic stability hinder their wider applications. Conversely, conventional capacitors display a great outputting pulsed power, but disappointing energy characteristics. Electrochemical capacitors (ECs), which are also known as supercapacitors, bridge the crucial performance disparity between fuel cells or batteries with high energy capacities and the traditional capacitors capable of outputting pulsed high power. The main focus of this review is to outline the latest developments of the ECs and determine their current status in terms of energy and power characteristics. In particular, recent developments in materials including new synthesis methods, structural studies and advanced configurations of ECs are discussed. Moreover, several technical challenges to further development are identified. Based on the latest results, the potential of developing supercapatteries, whose performance is in between batteries and contemporary supercapacitors, are also discussed in this review.