Fabrication and electrochemical characterization of super-capacitor based on three-dimensional composite structure of graphene and a vertical array of carbon nanotubes

Abstract

We have demonstrated a three-dimensional composite structure of graphene and carbon nanotubes as electrodes for super-capacitors. The goal of this study is to fabricate and test the vertically grown carbon nanotubes on the graphene layer acting as a spacer to avoid self-aggregation of the graphene layers while realizing high active surface area for high energy density, specific capacitance, and power density. A vertical array of carbon nanotubes on silicon substrates was grown by a low-pressure chemical vapor deposition process using anodized aluminum oxide nanoporous template fabricated on silicon substrates. Subsequently, a graphene layer was grown by another low-pressure chemical vapor deposition process on top of a vertical array of carbon nanotubes. The Raman spectra confirmed the successful growth of carbon nanotubes followed by the growth of high-quality graphene. The average measured capacitance of the three-dimensional composite structure of graphene-carbon nanotube was 780 µFcm−2 at 100 mVs−1.

Highly Stretchable Supercapacitors Enabled by Interwoven CNTs Partially Embedded in PDMS

“…Electric energy storage occurs at the electrode/electrolyte interface of both positive and negative electrodes or through surface oxidation/reduction . High surface area, electrical conductivity, mesoporosity, and electrolyte accessibility are important properties desired for an ideal electrode material. , Carbon in its various forms, such as activated carbon, carbon fibers, carbon clothes, carbon aerogels, graphene, and carbon nanotubes (CNTs), has been widely studied as an electrode material for electrochemical capacitors. − The capacitance and charge storage/delivery essentially depend on the variation of electrode materials because poor accessibility of the carbon surface to the electrolyte has been confirmed to be the most important reason for the absence of proportionality between specific capacitance and surface area of the materials. , CNTs are an attractive electrode material toward high performance supercapacitors owing to their high electrical conductivity, high charge transport capability, chemical stability, and an appropriate balance between the surface area and the mesoporosity of a carbon material, which provide easier access for electrolyte ions to form an electrical double layer on the interface between electrode and electrolyte. − In recent years, vertically aligned carbon nanotubes (VACNTs) have been widely studied for supercapacitor applications, ,− owing to their advantages of exhibiting a combined charge capacity from all individual tubes, high effective surface area (2200 m 2 /g), electrical conductivity (7–14 S/cm), power density (98.9 kW/kg), and energy density (24.7 Wh/kg). Several studies have been conducted to investigate the fabrication and characterization of CNT-based flexible supercapacitors. ,,− ,,,− Though significant accomplishments have been demonstrated for flexible/stretchable supercapacitors, fabrication processes are often complicated or time-consuming.…”

Material models and finite analysis of additively printed polymer composites

“…Additive manufacturing (AM) can create complicated three-dimensional (3D) objects that are impossible to be fabricated with conventional subtractive or transformative methods, such as lathe, mill, and injection molding. 1,2 While AM originally attracted interest as a facile prototyping process, advancements in functionality of the materials have allowed it to be used in novel applications, such as bespoke prosthesis, 3 dental surgery, 4 tissue engineering, 5,6 3D microfluidics devices, 7 energy storage devices, 8 biochemical sensors, 9 self-healing, 10 and flexible electronics. 11–17…”