Raman Spectroscopy Measurements Support Disorder-Driven Capacitance in Nanoporous Carbons
Xinyu Liu, Jaehoon Choi, Zhen Xu, Clare P. Grey, Simon Fleischmann, Alexander C. Forse
Abstract
High Resolution Image Download MS PowerPoint Slide Our recent study of 20 nanoporous activated carbons showed that a more disordered local carbon structure leads to enhanced capacitive performance in electrochemical double layer capacitors. Specifically, NMR spectroscopy measurements and simulations of electrolyte-soaked carbons evidenced that nanoporous carbons with smaller graphene-like domains have larger capacitances. In this study, we use Raman spectroscopy, a common probe of local structural disorder in nanoporous carbons, to test the disorder-driven capacitance theory. It is found that nanoporous carbons with broader D bands and smaller I D /I G intensity ratios exhibit higher capacitance. Most notably, the I D /I G intensity ratio probes the in-plane sizes of graphene-like domains and supports the findings from NMR that smaller graphene-like domains correlate with larger capacitances. This study supports our finding that disorder is a key metric for high capacitance in nanoporous carbons and shows that Raman spectroscopy is a powerful technique that allows rapid screening to identify nanoporous carbons with superior performance in supercapacitors.