(Invited) New Brands of High Energy Electrochemical Capacitors with Hybridized Carbon Electrodes

摘要

The main disadvantages of electrical double-layer capacitors - EDLCs, are the relatively low amount of energy stored and the high cost of the devices. For new applications, as powering of e.g., electric vehicles, the concept of hybrid capacitor (HC) appears as a promising approach enabling to enhance the energy output. HCs behave as EDLC (e.g., linear galvanostatic charge/discharge, rectangular cyclic voltammogram, low time constant), while combining capacitive and battery-like electrodes. Since the battery-type electrode operates in a narrow potential range, the potential excursion of the EDL electrode is almost twice larger than in a symmetric EDLC, leading to approximately doubling of the discharge capacitance. Hence, for the same voltage range, the specific energy of the HC is twice higher than for an EDLC. In the last decade, HCs using a redox active electrolyte such as the iodine/iodide system and lithium-ion capacitors (LIC) have emerged as very promising technologies, essentially owing to the fact that carbon electrodes are highly conductive and relatively inexpensive.