Relating Precursor Pyrolysis Conditions and Aqueous Electrolyte Capacitive Energy Storage Properties for Activated Carbons Derived from Anhydrous Glucose-d

Abstract

The importance of precursor structure on the activation process step was investigated for carbons derived from carbohydrates, a consistent and abundant precursor stream. Precursor (nonactivated) carbons were derived from anhydrous α-D-glucose precursor by pyrolysis in Ar atmosphere at temperatures ranging from 500 to 1000°C. These carbons were then characterized and chemically (KOH) activated at 800°C. The electrochemical and physicochemical characteristics of the KOH-activated carbons were studied during and after synthesis using thermogravimetric analysis, X-ray diffractometry (XRD), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy, nitrogen gas adsorption method, and cyclic voltammetry. Both XRD and HRTEM results on the pyrolyzed carbons reveal that more graphene layers align in a parallel way with higher precursor carbonization temperatures. Chemical activation on the carbon prepared at lower temperatures achieved surface areas greater than 2900 m2 g-1, and specific capacitance numbers in excess of 180 F g-1 in 1 M Na2 S O4 solution. Relationships between electrochemical and physical properties are discussed. © 2010 The Electrochemical Society.