Scalable and Sustainable Ionic Liquid Supercapacitors with Engineered Nanocarbons

Abstract

The development of high volumetric energy density of carbon-based supercapacitors is the key to satisfy the market trend of device miniaturization. One effective strategy is to improve their working voltage window, areal and volumetric capacitance without sacrificing rate performance. This makes ionic liquids and porous nanocarbons become emerging electrolytes and electrode materials due to their wide decomposition voltage and large effective surface area, respectively. Here, we report nanocarbons produced from ball-milling of pristine graphite as the electrode material. The obtained spherical morphologies and close arrangements of nanocarbons shorten the ion transport pathway and enlarge the ion accessible surface area for better rate capability and volumetric energy density. To demonstrate the feasibility of facile and sustainable production potential, ionic liquid pouch-type supercapacitors using green aqueous binder are fabricated, which achieves a remarkable specific areal capacitance of 0.091 F m-2 and volumetric capacitance of 53 F cm-3 at 0.5 A g-1 with outstanding volumetric energy densities of 22.73 Wh L-1 at 481.25 W L-1 and 12.79 Wh L-1 at 23020.85 W L-1. Both volumetric energy density and rate performance are considerably better compared to commercial activated carbons (YP-50F) but without involving complicated, toxic and corrosive traditional activation processes while producing capacitive carbons.

Keywords: Scalable, sustainable, ionic liquid, supercapacitors, defects, nanocarbons