Substitution of Acetylene Black by Using Modified Flake Graphite Applied in Activated Carbon Supercapacitors

Peng Zhao,Wencheng Hu,Chunmei He,X Lei,S.P Kozaitis,C.-C Ku

doi:10.1051/matecconf/201816003005

Abstract

Flake graphite was mechanically modified at different times in N-methyl pyrrolidone under normal pressure. The results of the scanning electron microscopy, X-ray diffraction, and transmission electron microscopy suggested that the structure of the flake graphite was modified. The crystallinity of the flake graphite, and many defects were introduced into the material. The evaluation of capacitor performance by cyclic voltammetry, galvanostatic charge/discharge tests, and electrochemical impedance spectroscopy was also performed. Results showed that the electrochemical performance of flake graphite was strongly enhanced, particularly when it was exfoliated for 6 h. Moreover, the electrochemical capacitive properties of activated carbon were obviously enhanced through the substitution of acetylene black by flake graphite modified for 6 h.

Highlights

Supercapacitors (SCs), known as electrochemical capacitors (ECs), hybrid capacitors, or ultracapacitors, are highly promising power devices that are superior to conventional physical capacitors and batteries in many aspects
According to energy storage mechanism, SCs can be divided into two different types: double-layer capacitors (EDLCs) and faraday pseudocapacitor
Two diffraction peaks were observed near 25.5° and 54.6°, which corresponded to (002) and (004) reflections

Summary

Introduction

Supercapacitors (SCs), known as electrochemical capacitors (ECs), hybrid capacitors, or ultracapacitors, are highly promising power devices that are superior to conventional physical capacitors and batteries in many aspects These devices play an important role in the energy-storage field [1, 2]. The obtained graphite with high surface area has high specific capacitance and good Faradaic interfacial charge-transfer resistance (Rct). This material can improve the electrochemical performance of activated carbon (AC) while doped into AC at an appropriate ratio. Its crystallinity was reduced, the specific surface area was increased and electrochemical performance was enhanced after flake graphite was exfoliated. The result indicated that the electrochemical performance with S6was better, and the best content is 20%

Sample preparation

Electrochemical measurements

Results and discussion

Characterization

Preparation of electrodes