Optimization of ionic-liquid based electrolyte concentration for high-energy density graphene supercapacitors

Wong, Shao Ing; Lin, Han; Sunarso, Jaka; Wong, Basil T.; Jia, Baohua

doi:10.1016/j.apmt.2019.100522

Cited by 47 publications

(32 citation statements)

References 35 publications

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“…The flash reduction process of GO has been proven as an effective approach to restore the conductivity and produce porosity in producing high-performance graphene electrodes. [15,16] The high-power flash pulse triggered the rapid dissociation of oxygencontaining functional groups (OCFGs) due to instant high temperature and the outburst of gaseous products such as CO, CO 2 , and H 2 O, which caused local pressure rise to build up porous 3D graphene network. Such gaseous environment encouraged the water-gas shift reaction [20] and formed by-products such as H 2 gas within the system (Figure S1, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

“…The irradiation of intensive flash light pulse triggers fierce reduction and exfoliation of graphene oxide (GO) films due to efficient photothermal effect, leaving highly conductive and porous flash reduced graphene oxide (frGO) electrodes with excellent electrochemical performances. [14][15][16][17] Large amount of gases such as carbon monoxide (CO), carbon dioxide (CO 2 ), water vapor (H 2 O), and hydrogen (H 2 ) are released from the reduction of GO, coupled with instant temperature rise within GO films after flash irradiation, which provides an ideal environment for the reduction of MnO 2 to MnO. [18,19] In this paper, we report, for the first time, a green and simple co-reduction method for producing high-performance graphene/MnO electrodes via ultrafast flash reduction process within several milliseconds.…”

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confidence: 99%

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Flash‐Induced Ultrafast Production of Graphene/MnO with Extraordinary Supercapacitance

Zhang

Yang

et al. 2021

Small Methods

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MnO 2 ) electrodes (1110 F g −1 ), [10,11] which indicates its potential to further improve the capacitance of carbon-based electrodes. In 2013, Liao et al. [10] proposed the fabrication of vertically-aligned graphene@MnO nanosheets as high-performance SC electrodes through a hydrothermal process, and increased the specific capacitance of electrode to 790 F g −1 . Later, other fabrication approaches such as carbon-coating of self-assembly of MnO nanoparticles, direct electrospinning on carbon nanofibers, and thermal plasma deposition of MnO onto porous carbon materials have also been investigated to synthesize MnO/carbon electrodes. [11][12][13] However, although nano-MnO has been synthesized and deposited in carbon-based electrodes, the process is relatively complicated and usually requires multiple steps. This is because nano-MnO suffers from agglomeration of the particles during the synthesis process, which leads to loss of surface active sites and thus a decrease in electrochemical activity. As a result, the reported capacitances of MnO/carbon electrodes are generally less than 800 F g −1 , which are far below the theoretical limit of MnO (only approximately 60% is achieved). Therefore, it remains challenging to well anchor the MnO homogeneously onto carbon networks through a facile and simple process to produce high capacitance SC electrodes.Flash reduction is considered as one promising solution to the production of graphene/MnO electrodes in a green and facile manner. The irradiation of intensive flash light pulse triggers fierce reduction and exfoliation of graphene oxide (GO) films due to efficient photothermal effect, leaving highly conductive and porous flash reduced graphene oxide (frGO) electrodes with excellent electrochemical performances. [14][15][16][17] Large amount of gases such as carbon monoxide (CO), carbon dioxide (CO 2 ), water vapor (H 2 O), and hydrogen (H 2 ) are released from the reduction of GO, coupled with instant temperature rise within GO films after flash irradiation, which provides an ideal environment for the reduction of MnO 2 to MnO. [18,19] In this paper, we report, for the first time, a green and simple co-reduction method for producing high-performance graphene/MnO electrodes via ultrafast flash reduction process within several milliseconds. We tailor the reducing gases (CO and H 2 ) generated from flash reduction of GO to fully transform the pre-deposited MnO 2 nano-needles into MnO without agglomeration simultaneously during the production of high-quality porous graphene materials. Through rational control the feeding ratio guided by simulation studies, optimal Production of high-capacitance electrodes beyond the theoretical limit of 550 F g −1 of pure graphene materials is highly desired for energy storage applications, yet remains an open challenge, especially with a facile and simple process. By rational design of reaction condition guided by theoretical analysis, the ultrafast (within millisecond) fabrication of highperformance graphene/MnO electrodes via a low-cost ...

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Flash‐Induced Ultrafast Production of Graphene/MnO with Extraordinary Supercapacitance

Zhang

Yang

et al. 2021

Small Methods

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“…And then, to remove adsorbed solvents, the samples were dried at 50 °C for 12 h. In the synthesis, urea is the source of both carbonate and hydroxyl anions, as www.mrs.org/jmr Article © The Author(s) 2021 indicated in Eqs. (7)(8)(9). The synthesis of NiCu(CO 3 )(OH) 2 is as follows (7-9) [10,27].…”

Section: Electrode Preparationmentioning

confidence: 99%

“…These supercapacitors can be classified into two types: electrical double-layer capacitors (EDLCs), which usually use carbon active materials, and faradaic capacitors, which use redox-active materials [8]. EDLC devices store electrochemical energy via electrostatic accumulation of charges in the electric double layer and currently dominate the SC market because of their ability to accumulate large amounts of charge [9]. However, their relatively low specific capacitance is inhibitive for the increasing requirements of SCs with higher electrochemical performance, which also restricts their potential large-scale applications [10,11].…”

Section: Introductionmentioning

confidence: 99%

Hybrid nanostructured PAN@NiCu(CO3)(OH)2 composite for flexible high-performance supercapacitors

Lee

Verma

Lê

et al. 2021

Journal of Materials Research

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A binder-free porous NiCu(CO3)(OH)2 composite was grown on a polyacrylonitrile (PAN) nanofiber substrate using a hydrothermal method. PAN nanofibers were fabricated by the electrospinning method, thus producing a substrate with a nano-sized diameter and high specific surface area. The composite NiCu(CO3)(OH)2 nanowires on PAN nanofibers provided the large specific surface area required for the redox reaction. Transition metal-based nanowires and nano-sized PAN substrates indicate a synergistic effect in electrochemical performance. The NiCu(CO3)(OH)2 on PAN composite showed a remarkable maximum specific capacity of 870 mAh g−1 at a current density of 3 A g−1, which indicates that it can be a suitable electrode material. In addition, an asymmetric supercapacitor with NiCu(CO3)(OH)2 on PAN composite as the cathode and graphene as the anode showed an ultra-high energy density of 89.2 W h kg−1 at a power density of 835 W kg−1 and a capacitance retention of 90.1% after 5000 cycles. Graphic abstract

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“…One very interesting work involving the application of ionic liquids as electrolyte additives was developed by Wong et al [ 49 ], who studied the concentration of [emim][BF 4 ] in an electrolyte to optimize the capacitive performance of high-energy density graphene supercapacitors. The authors reported that the electrolyte viscosity increased exponentially with the increase of IL concentration, while the ionic conductivity decreased with an increase in IL concentration.…”

Section: Imidazolium-based Ionic Liquidsmentioning

confidence: 99%

Application of Ionic Liquids in Electrochemistry—Recent Advances

2020

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In this review, the roles of room temperature ionic liquids (RTILs) and RTIL based solvent systems as proposed alternatives for conventional organic electrolyte solutions are described. Ionic liquids are introduced as well as the relevant properties for their use in electrochemistry (reduction of ohmic losses), such as diffusive molecular motion and ionic conductivity. We have restricted ourselves to provide a survey on the latest, most representative developments and progress made in the use of ionic liquids as electrolytes, in particular achieved by the cyclic voltammetry technique. Thus, the present review comprises literature from 2015 onward covering the different aspects of RTILs, from the knowledge of these media to the use of their properties for electrochemical processes. Out of the scope of this review are heat transfer applications, medical or biological applications, and multiphasic reactions.

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Optimization of ionic-liquid based electrolyte concentration for high-energy density graphene supercapacitors

Cited by 47 publications

References 35 publications

Flash‐Induced Ultrafast Production of Graphene/MnO with Extraordinary Supercapacitance

Flash‐Induced Ultrafast Production of Graphene/MnO with Extraordinary Supercapacitance

Hybrid nanostructured PAN@NiCu(CO3)(OH)2 composite for flexible high-performance supercapacitors

Application of Ionic Liquids in Electrochemistry—Recent Advances

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