Compact graphene powders with high volumetric capacitance: Microspherical assembly of graphene via surface modification using cyanamide

Kim, Young Hwan; Park, Byung Hoon; Choi, Yeon Jun; Lee, Geon-Woo; Kim, Hyun-Kyung; Kim, Kwang Bum

doi:10.1016/j.ensm.2019.07.039

Cited by 40 publications

(24 citation statements)

References 57 publications

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“…Moreover, numerous graphene‐like carbon with low defects have been used for high‐voltage SCs. [ 30,97,147,148 ] Hata et al [ 147 ] used single‐walled carbon nanotubes (SWNTs) with high purity (99.98% carbon content and <2% amorphous carbon) for SC applications. The fabricated SC in an organic electrolyte exhibits high voltage (4.0 V), high energy density (94 Wh kg −1 , 47 Wh L −1 ), and power density (210 kW kg −1 , 105 kW L −1 ).…”

Section: Carbon‐based Electrode Materialsmentioning

confidence: 99%

Perspective on High‐Energy Carbon‐Based Supercapacitors

Dou

Park

2020

Energy & Environ Materials

164

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Supercapacitors based on carbon materials have advantages such as high power density, fast charging/discharging capability, and long lifetime stability, playing a vital role in the field of electrochemical energy storage technologies. To further expand the practical applications of carbon-based supercapacitors, their energy density, which is essentially determined by the specific capacitance and operating voltage, should be improved. This review provides fundamental knowledge on achieving high energy density of supercapacitors. We first address the relationship of the features of carbon materials, such as the surface area, pore size distribution, and surface functional groups, with their electrochemical performances, such as the gravimetric and volumetric capacitance, surface pseudocapacitance, and operating voltage. Then, we discuss the properties of electrolytes from nonaqueous and aqueous to hybrid one from the thermodynamic and kinetic aspects, and present their effects on capacitance and operating voltage. Finally, we illustrate different cell design strategies and their basic principles for increasing operating voltage. We also highlight the recent advances related to these fields and provide our insight into high-energy supercapacitors.

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Section: Carbon‐based Electrode Materialsmentioning

confidence: 99%

Perspective on High‐Energy Carbon‐Based Supercapacitors

Dou

Park

2020

Energy & Environ Materials

164

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“…As an aqueous solution consisting of DCDA, CoAc, and GO was maintained at 80 °C prior to spray drying, GO and DCDA reacted through amide bonding to form the DCDA‐modified GO. [ 13,35,36 ] Moreover, cobalt oxide (Co x O y ) nanoparticles were formed on GO through a redox reaction between CoAc and GO, [ 37 ] thereby forming the DCDA@Co x O y @GO composites. In our previous study, we reported a microspherical assembly of GO using spray drying of an aqueous solution containing cyanamide and GO.…”

Section: Resultsmentioning

confidence: 99%

“…[ 11,12 ] In order to further explore the applications of graphene as electrode materials, 2D graphene should be assembled into microspherical assemblies with high packing density, while maintaining its inherent properties. [ 13 ] Previous studies have investigated graphene assemblies using well‐established strategies such as vacuum filtration, [ 2,14 ] hydrothermal assembly, [ 1,3,15 ] and spray drying. [ 16 − 19 ] However, it is still a challenge to develop the controllable and scalable assembly of graphene into microsized powders with a high packing density.…”

Section: Introductionmentioning

confidence: 99%

“…[ 20 ] Recently, we reported a facile and scalable assembly of graphene flakes into compact graphene microspheres (GMs) via surface modification using cyanamide. [ 13,21 ] The key features of compact GMs are high packing density (0.91 g cm −3 ), excellent compressive strength (750 MPa), and mesoporous structures (pore volume: 0.64 cm 3 g −1 ) with no macropores. Nevertheless, reduced graphene oxide (rGO) has an inevitable tendency to restack into multilayers because of the strong van der Waals interactions, which can decrease the accessibility of electrolyte ions and surface area utilization.…”

Section: Introductionmentioning

confidence: 99%

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In Situ Growth of Novel Graphene Nanostructures in Reduced Graphene Oxide Microspherical Assembly with Restacking‐Resistance and Inter‐Particle Contacts for Energy Storage Devices

Kim

Lee

Choi

et al. 2021

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Graphene is extensively investigated for various energy storage systems. However, the very low density (<0.01 g cm−3) of graphene nanosheets has hindered its further applications. To solve this issue, a controlled assembly of 2D graphene building blocks should be developed into graphene microspheres with high packing density, and restacking of graphene should be prevented to ensure an electrochemically accessible surface area during the assembly. Furthermore, graphene microspheres should have multiple 1D external conductive architecture to promote contacts with the neighbors. This study reports in situ growth of novel graphene nanostructures in reduced graphene oxide microspherical assembly (denoted as GT/GnS@rGB) with restacking resistance and interparticle contacts, for electrochemical energy storage. The GT/GnS@rGB showed high gravimetric (231.8 F g−1) and volumetric (181.5 F cm−3) capacitances at 0.2 A g−1 in organic electrolyte with excellent rate capabilities of 94.3% (@ 0.2 vs 10 Ag−1). Furthermore, GT/GnS@rGB exhibited excellent cycling stability (96.1% of the initial capacitance after 100 000 charge/discharge cycles at 2 A g−1). As demonstrated in the electrochemical evaluation as electrode materials for electrical double‐layer capacitors, unique structural and textural features of the GT/GnS@rGB would be beneficial in the use of graphene assembly for energy storage applications.

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“…The consequence of this is that, while plenty of publications report about "fantastic" values in gravimetric basis, most of the materials would be completely useless materials in practice, due to their low density. One of the best examples in this category is graphene; therefore, only attempts trying to use the advantages of graphene while aiming to enhance its density are of interest; an interesting development of such strategy is given in [75].…”

Section: What Are Carbon Requirements For Electrochemical Capacitors?mentioning

confidence: 99%

Engaging nanoporous carbons in “beyond adsorption” applications: Characterization, challenges and performance

Ania

Armstrong²,

Bandosz

et al. 2020

Carbon

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This paper addresses the challenges of explaining the behavior of porous carbons in cutting-edge applications related to energy storage, catalysis, photocatalysis, and advanced separation based on reactive adsorption. It is a summary of the outcomes of the extensive discussion which took place during the workshop "Beyond Adsorption-II: new perspectives and challenges for nanoporous carbons," organized as a satellite event to the International Carbon Conference on July 20 th 2019 in New York. It is not our intention to provide a tutorial on the applications, characterization or performance testing of porous carbons; we would rather like to focus on the controversy of the results and phenomena, on the explanation of findings, and on raising concerns to the growing carbon-researching scientific community about the importance of understanding the features of nanoporous carbons by choosing an appropriate characterization 2 technique that will bring meaningful information. We want to emphasize that nanoporous carbons have unique features ensuring them making a marked advance in science and technology. Even though recent studies have shown their potential in various emerging applications, the origin of such performance is not yet well understood. Thus, scientists are encouraged to focus on a precise characterization of porous carbons using a set of complementary techniques for triggering future technological developments.

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Compact graphene powders with high volumetric capacitance: Microspherical assembly of graphene via surface modification using cyanamide

Cited by 40 publications

References 57 publications

Perspective on High‐Energy Carbon‐Based Supercapacitors

Perspective on High‐Energy Carbon‐Based Supercapacitors

In Situ Growth of Novel Graphene Nanostructures in Reduced Graphene Oxide Microspherical Assembly with Restacking‐Resistance and Inter‐Particle Contacts for Energy Storage Devices

Engaging nanoporous carbons in “beyond adsorption” applications: Characterization, challenges and performance

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