Self-Supporting Hybrid Supercapacitor Electrodes Based on Carbon Nanotube and Activated Carbons

A.R Kerimkulova,B.T Lesbayev,M Nazhipkyzy,N.G Prikhodko,S Kuzuhara,S Noda,T.S Temirgaliyeva,Z.A Mansurov

doi:10.18321/ectj719

Abstract

Self-supporting AC (activated carbon)-FWCNT (few-wall carbon nanotubes) hybrid electrodes were fabricated by mixing of ACs with high specific surface area (SSA) and sub-millimeter-long FWCNTs. In order to fabricate the hybrid electrodes, AC and FWCNT were mixed in a weight ratio of 9:1, dispersed by bath-sonication and vacuum-filtrated on a membrane filter. The addition of FWCNTs gives conductivity and mechanical strength, and replace metallic current collectors in thick (0.1 mm) electrodes. For making an electrode, three different ACs that derived from walnut shell (WS), that from apricot stones (AS), and that commercially used for capacitors (YP-80F, Kuraray Chemical Co., Osaka Japan), were used with FWCNT in weight ratio of AC:FWCNT = 9:1. An electrode based only on FWCNT was also prepared as a reference for comparison. Electrochemical properties of the obtained electrodes were investigated by the cyclic voltammetry method (CV). Electrochemical characteristics were measured using the three-electrode cell contained of YP80F-FWCNT, AS-FWCNT, WS-FWCNT as a working electrode, a YP-80F-FWCNT counter electrode and a Ag/AgCl reference electrode with an electrolyte of 1 M Na2SO4 aqueous solution. Also, the morphological properties of obtained electrodes were studied using scanning electron microscope (SEM), the SSA was investigated by the Brunauer-Emmett-Teller analysis. SSA, conductivity, and resistivity of AS-FWCNT and WS-FWCNT electrodes were summarized. Both the AS-FWCNT and WS-FWCNT hybrid electrodes showed specific capacitances of about 140 F/g at 1 mV/s and about 100 F/g at 100 mV/s, which are similar or even better than the AC-CNT hybrid electrode made of commercialized AC (YP-80F).

Highlights

The storage of electrical energy has become one of the fundamental enablers for sustainable society in the 21st century
The mixture of AC with few-wall CNTs (FWCNTs) was dispersed in ethanol using a bath-type 600-W sonicator for 20 min with a cooling unit set at 20 °C
From the point of view of practical application, it is important to take into account the dispersability and cost of carbon nanotubes (CNTs)

Summary

Introduction

The storage of electrical energy has become one of the fundamental enablers for sustainable society in the 21st century. Because CNTs can play all the roles of binder, conductive filler, and current collector, we can increase the content of active material in the device and the energy density of supercapacitors. Due to the strong van der Waals interactions between SWCNTs, they form bundles and disordered networks, and as a consequence there is difficulties on pull out their excellent mechanical and electronic properties [9, 10] Another type of CNTs is multi-wall CNTs (MWCNTs) that are available at low cost of about 100 USD per kg, but they have some disadvantages such as smaller conductivity and smaller surface area of 300 m2/g. In order to obtain the light weight, flexible, self-supporting electrodes and replace conventional conductive additives as acetylene black it is necessary to combine the FWCNTs with AC in hybrid electrodes

Experimental

Results and discussion

80 ADS DES

Conclusions