Multiwalled Carbon Nanotubes Based Nanocomposites for Supercapacitors: A Review of Electrode Materials

Abstract

Electrode materials are the most important factors to verify the properties of the electrochemical supercapacitor. In this paper, the storage principles and characteristics of electrode materials, including carbon-based materials, transition metal oxides and conducting polymers for supercapacitors are depicted in detail. Other factors such as electrode separator and electrolyte are briefly investigated. Recently, several works are conducted on application of multiwalled carbon nanotubes (MWCNTs) and MWCNTs-based electrode materials for supercapacitors. MWCNTs serve in experimental supercapacitor electrode materials result in specific capacitance (SC) value as high as 135 Fg-1. Addition of pseudocapacitive materials such as transition metal oxides and conducting polymers in the MWCNTs results in electrochemical performance improvement (higher capacitance and conductivity). The nanocomposites of MWCNTs and pseudocapacitive materials are the most promising electrode materials for supercapacitors because of their good electrical conductivity, low cost and high mass density.

A Review of Metal Oxide Composite Electrode Materials for Electrochemical Capacitors

“…In relation to the recent trends of research and development, electrochemical capacitors can be classi¯ed into three main categories: (i) EDLCs such as carbon-based materials, (ii) pseudocapacitors including transition metal oxides and conducting polymers and (iii) hybrid capacitors. 28 Carbonbased materials, ranging from ACs to carbon nanotubes (CNTs) and graphene which exhibit static double-layer capacitance via charge separation/accumulation, have become the most extensively examined electrode materials in EDLCs, owing to the large surface area, high electronic conductivity, su±cient chemical stability and low costs. 25 Transition metal oxides, lithium metal oxides and conducting polymers are examples of pseudocapacitors which might be able to contribute up to 10-100 times more than that of EDLCs due to their fast and reversible surface redox reactions.…”

“…28 Based on the storage mechanism of EDLCs, the speci¯c surface area of AC electrode material is directly proportional to the speci¯c capacitance. Theoretically, it is proposed that the higher speci¯c surface areas would strongly correlate to the improved capacitive performance.…”

“…It is proposed that microporous carbon with a high speci¯c surface area is e®ective for higher energy densities with a relatively slow charge-discharge. 28 On the other hand, in order to obtain higher power densities, carbon electrodes should contain a large amount of mesopores because their relatively larger pore size allows improved ion accessibility and di®usion. Generally, macropores which act as transport pathway into the inner carbon particles, make insigni¯cant contribution to the total surface area of porous carbon.…”

Construction of Hierarchical Ni(OH)2@CoMoO4 Nanoflake Composite for High-Performance Supercapacitors

“…SCs, also known as electrochemical capacitors, are promising energy storage devices that bridge the gap between conventional capacitors and batteries, 5 due to the advantages such as fast charges and discharges, high power, long cycling life and low maintenance cost. [6][7][8][9] SCs are generally classi¯ed into two types based on di®erent charge storage mechanisms: electric double layer capacitors (EDLCs) and pseudocapacitors. 10,11 Compared with EDLCs, the pseudocapacitors have much higher speci¯c capacitance and energy density due to the fast and reversible redox reactions occurred not only on electrode surface but also in the bulk phase.…”

Faradaic and Capacitive Components of the CNT Electrochemical Responses

“…A prevalent capacitive process will allow the design of most efficient supercapacitors (Wildgoose et al, 2006;Endo et al, 2008;Liu et al, 2008;Zhang et al, 2009;Bondavalli et al, 2012;Kiamahalleh et al, 2012;Wang et al, 2012Wang et al, , 2015Zheng et al, 2012;Li and Wei, 2013;Yan et al, 2014;Yiran et al, 2014;Abdalla et al, 2015); while a prevalent reactive, or faradic, process will allows the design of batteries for fast and ultrafast charge/discharge processes and multifunctional actuators having better control of the faradic movement (Dai et al, 2002;Landi et al, 2009;Du et al, 2011;Myung et al, 2015) acting, simultaneously, as sensor of the working and ambient conditions.…”