Electrochemical Performance of Few-Layer Graphene Nano-Flake Supercapacitors Prepared by the Vacuum Kinetic Spray Method

Mohaned Mohammed,Doo-Man Chun

doi:10.3390/coatings8090302

Abstract

A few-layer graphene nano-flake thin film was prepared by an affordable vacuum kinetic spray method at room temperature and modest low vacuum conditions. In this economical approach, graphite microparticles, a few layers thick, are deposited on a stainless-steel substrate to form few-layer graphene nano-flakes using a nanoparticle deposition system (NPDS). The NPDS allows for a large area deposition at a low cost and can deposit various metal oxides at room temperature and low vacuum conditions. The morphology and structure of the deposited thin films are alterable by changing the scan speed of the deposition. These changes were verified by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. The electrochemical performances of the supercapacitors, fabricated using the deposited films and H3PO4–PVA gel electrolytes with different concentrations, were measured using a 2-electrode cell. The electrochemical performance was evaluated by cyclic voltammetry, galvanostatic Charge–discharge, and electrochemical impedance spectroscopy. The proposed affordable fabricated supercapacitors show a high areal capacitance and a small equivalent series resistance.

Highlights

Supercapacitors, called ultracapacitors, are promising electrochemical storage devices due to their high-power density, fast charge/discharge rates, and long Charge–discharge cycles [1,2,3,4].Supercapacitors have the potential to supplement or replace the use of batteries for energy storage applications, namely those for wearable and portable electronics, energy storage systems, and electrical and hybrid vehicles [5]
The first reason is that graphene has good electrical conductivity
Available graphite powder (MGF 10 995A, Samjung C&G, Gyeongsan, Korea) with a particle size of 10 μm or larger was used in this research for deposition on a stainless steel substrate (SUS304, Nilaco Corporation, Tokyo, Japan), with a thickness of 0.5 mm

Summary

Introduction

Supercapacitors, called ultracapacitors, are promising electrochemical storage devices due to their high-power density, fast charge/discharge rates, and long Charge–discharge cycles [1,2,3,4].Supercapacitors have the potential to supplement or replace the use of batteries for energy storage applications, namely those for wearable and portable electronics, energy storage systems, and electrical and hybrid vehicles [5]. Supercapacitors, called ultracapacitors, are promising electrochemical storage devices due to their high-power density, fast charge/discharge rates, and long Charge–discharge cycles [1,2,3,4]. EDLCs store energy via ion adsorption/desorption on the electrode surface, exhibit an excellent cycle life and power density, but are restrained by limited adsorption capacity, which adversely impacts their energy density [6]. Carbon materials with a large specific surface area and excellent electrical conductivity, such as active carbon (AC), carbon nanotubes (CNTs), and graphene, have been used for EDLCs. In contrast, pseudocapacitors store energy via fast and reversible surface redox reactions. There are two reasons why graphene is a suitable material for storage devices. The electrical conductivity is a result of graphene’s unique electronic properties, which include a massless Dirac fermion, Coatings 2018, 8, 302; doi:10.3390/coatings8090302 www.mdpi.com/journal/coatings

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