Cycling Performance of Ppy Derived Carbon Based Symmetric Supercapacitors in Aqueous Electrolyte

Abstract

Electrochemical capacitors (ECs) also known as supercapacitors have attracted significant interest for the development of next generation of energy storage systems. ECs are characterized by their high power density and low energy density when compared with batteries [1,2]. ECs are suitable for transient energy saving application such as energy capture during braking in vehicles, in construction equipment such as cranes and for opening of doors in the A380 Jumbo jet, portable and flexible electronics [1]. However, the performance of ECs devices for most of these applications is exclusively dependent on the physicochemical properties of the electrode materials. Electrode materials with diverse dimensionalities such as 1D, 2D and 3D nanostructures have been explored to improve supercapacitive properties by taking advantages of the unique ability of the different nanostructure for ion propagation and charge storage [3,4]. The stability of supercapacitors is a very important feature for characterization of ECs devices. The traditional method of evaluating the stability is via the constant current charge-discharge (CCCD) cycling over several thousands of cycles which in many cases does not show degradation to the ECs devices. As an alternative to this, voltage holding or floating test has been proposed as a reliable technique to test the stability of electrode materials [5,6]. Here we report on the performance (specific capacitance) of symmetric capacitors based on mesoporous PPY derived carbons and the stability of the symmetric capacitors based on voltage holding (floating conditions) operating in aqueous electrolytes evaluated by cyclic constant current charge-discharge tests. Variation in the specific capacitance values with the floating conditions shows a good cycling life performance in alkaline electrolyte for ~190 h with slight degradation observed after 140 h.