Synergistic Effect between Ultra-Small Nickel Hydroxide Nanoparticles and Reduced Graphene Oxide sheets for the Application in High-Performance Asymmetric Supercapacitor

Abstract

Nanoscale electrode materials including metal oxide nanoparticles and two-dimensional graphene have been employed for designing supercapacitors. However, inevitable agglomeration of nanoparticles and layers stacking of graphene largely hamper their practical applications. Here we demonstrate an efficient co-ordination and synergistic effect between ultra-small Ni(OH)2 nanoparticles and reduced graphene oxide (RGO) sheets for synthesizing ideal electrode materials. On one hand, to make the ultra-small Ni(OH)2 nanoparticles work at full capacity as an ideal pseudocapacitive material, RGO sheets are employed as an suitable substrate to anchor these nanoparticles against agglomeration. As a consequence, an ultrahigh specific capacitance of 1717 F g−1 at 0.5 A g−1 is achieved. On the other hand, to further facilitate ion transfer within RGO sheets as an ideal electrical double layer capacitor material, the ultra-small Ni(OH)2 nanoparticles are introduced among RGO sheets as the recyclable sacrificial spacer to prevent the stacking. The resulting RGO sheets exhibit superior rate capability with a high capacitance of 182 F g−1 at 100 A g−1. On this basis, an asymmetric supercapacitor is assembled using the two materials, delivering a superior energy density of 75 Wh kg−1 and an ultrahigh power density of 40 000 W kg−1.

A facile one-step approach to hierarchically assembled core–shell-like MnO2@MnO2 nanoarchitectures on carbon fibers: An efficient and flexible electrode material to enhance energy storage

“…Currently, energy storage devices such as lithium-ion batteries, electrochemical supercapacitors (SCs), and fuel cells that can convert chemical energy into electrical energy have attracted much attention [5][6][7][8][9]. Due to flexibility as well as desirable properties such as high power density, fast charge-discharge times, excellent cycling stability, and operational safety, SCs are considered one of the most promising devices for practical charge storage applications [10][11][12]. Additionally, because of these attractive properties, SCs can be expected to be applied in many different types of devices, including flexible electronics, memory back-up systems, pacemakers, military devices, and electric vehicles [13,14].…”

A facile hydrothermal reflux synthesis of Ni(OH)2/GF electrode for supercapacitor application

“…Hence, the electrochemical performance of supercapacitors depend on the type of active materials used, e.g. conducting polymers, transition metal oxides and hydroxides, and carbon materials [4,8]. Furthermore, the distinctive dimensions of the active materials are well essential for Electrochemical capacitors performance, considering the fact that the square of the diffusion distance is proportionate to the diffusion time of electrolyte ions [9,10].…”

“…Electrochemical capacitors also known as supercapacitors or ultracapacitors have become attractive and suitable in energy storage systems due to their excellent power performance, reasonable energy density, as well as good cycle life [4,5]. Electrochemical capacitors are classified as Electrochemical double layer capacitors (EDLC) that use reversible adsorption/desorption of ion at the surface of the active materials, e.g.…”

Liquid Exfoliated Graphene: A Practical Method for Increasing Loading and Producing Thin Films

“…The role of NH 3 in the stability of the liquid exfoliation dispersions is parallel to role it plays in the stability of graphene oxide reduction using hydrazine {N 2 H 4 }. 23,26 Notably, while the graphene dispersions produced in this work are not oxidized, both graphene oxide dispersions, documented in literature, 23 and the dispersions in NMP containing NH 3 , produced within this work, possess similar opacity and dark coloring. The inclusion of NH 4 OH is also used in the production of graphite oxide 27,28 as graphite cannot readily be dispersed in water, due to its extreme hydrophobicity, which results in the aggregation of graphite.…”