Chip scale carbon nanotube supercapacitors with ionic liquid electrolytes

Abstract

Efficient and clean energy storage is being demanded for use in a variety of technologies. In particular, the internet of things requires chip scale, high energy and power density energy storage with high cyclability. Batteries do not meet this need due to a lack of power density and poor cyclability. Capacitors do not have the required energy density. This separation of storage capabilities creates a need for supercapacitors, a technology that maintains high energy density, power density, and cyclability. Supercapacitors can utilize two storage mechanisms, the Helmholtz double layer (non-faradaic) and pseudocapacitance (faradaic). In this work, a chip scale, silicon based, embedded carbon nanotube based electrode is presented with four functionalizatons (TiOx, TiNx, ZrOx, ZrNx), introduced through atomic layer deposition, and five ionic liquid electrolytes. Each sample was tested with cyclic voltammetry, galvanostatic methods, and impedance spectroscopy to measure the capacitance and equivalent series resistance.