Elucidating the effect of heating induced structural change on electrical and thermal property improvement of single wall carbon nanotube

Matsumoto, Naoyuki; Oshima, Azusa; Chen, Guohai; Yudasaka, Masako; Yumura, Motoo; Hata, Kenji; Futaba, Don N.

doi:10.1016/j.carbon.2015.01.042

Cited by 17 publications

(10 citation statements)

References 31 publications

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“…[75,143,144] It has been shown that the inner shell can be electrically active where both shells contribute similarly to the transport. [145][146][147] For this reason, DWCNTs are better intrinsic conductors than large MWCNTs (in which not all shells are coupled) and possibly better than SWCNTs, [148][149][150] while maintaining a high degree of chemical stability. [74] Further, functionalization can happen exclusively on the outer shell, leaving the inner tube intact and isolated.…”

Section: Multi-wall Cntsmentioning

confidence: 99%

“…Among the unaligned FWCNT films, several reports indicate there is an optimum number of two to three shell walls to achieve highest conductivity. [148][149][150] It is thought that for FWCNTs, all shells participate in the transport. This is unlike larger MWCNTs, where only the two outer shells participate, with the rest only taking up volume.…”

Section: Average Cnt Dimensions and Graphitic Perfectionmentioning

confidence: 99%

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A Meta‐Analysis of Conductive and Strong Carbon Nanotube Materials

2021

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A study of 1304 data points collated over 266 papers statistically evaluates the relationships between carbon nanotube (CNT) material characteristics, including: electrical, mechanical, and thermal properties; ampacity; density; purity; microstructure alignment; molecular dimensions and graphitic perfection; and doping. Compared to conductive polymers and graphitic intercalation compounds, which have exceeded the electrical conductivity of copper, CNT materials are currently one‐sixth of copper's conductivity, mechanically on‐par with synthetic or carbon fibers, and exceed all the other materials in terms of a multifunctional metric. Doped, aligned few‐wall CNTs (FWCNTs) are the most superior CNT category; from this, the acid‐spun fiber subset are the most conductive, and the subset of fibers directly spun from floating catalyst chemical vapor deposition are strongest on a weight basis. The thermal conductivity of multiwall CNT material rivals that of FWCNT materials. Ampacity follows a diameter‐dependent power‐law from nanometer to millimeter scales. Undoped, aligned FWCNT material reaches the intrinsic conductivity of CNT bundles and single‐crystal graphite, illustrating an intrinsic limit requiring doping for copper‐level conductivities. Comparing an assembly of CNTs (forming mesoscopic bundles, then macroscopic material) to an assembly of graphene (forming single‐crystal graphite crystallites, then carbon fiber), the ≈1 µm room‐temperature, phonon‐limited mean‐free‐path shared between graphene, metallic CNTs, and activated semiconducting CNTs is highlighted, deemphasizing all metallic helicities for CNT power transmission applications.

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Section: Multi-wall Cntsmentioning

confidence: 99%

Section: Average Cnt Dimensions and Graphitic Perfectionmentioning

confidence: 99%

A Meta‐Analysis of Conductive and Strong Carbon Nanotube Materials

2021

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“…In short, no other process condition demonstrated the equivalent level of electrical conductivity improvement as described above. First, the heating-only treatment was carried out at 900 and 1500 °C in an Ar ambient for 5 h. Similar to the results observed for CNTs, heating-only showed observable improvement at temperatures at, or above, 1500 °C [ 29 ]. As summarized in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…While this treatment shows potential in the effective and efficient property improvement of graphite sheets, we do recognize the need for a high-power source as well as relatively high treatment temperatures (~ 900 °C) to remain time efficient. Based on our previous work on the treatment of single-wall carbon nanotubes, the treatment temperature can be decreased with an associated increase in the treatment current [ 29 ]. Therefore, one possible approach to reduce the temperature to ~ 800 °C would be to increase the applied current ~ 20%.…”

Section: Resultsmentioning

confidence: 99%

Crystalline and Electrical Property Improvement of Filtrated, Exfoliated Graphite Sheets by an In-Plane Current and Heating Treatment

et al. 2020

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We report an approach to fabricate high conductivity graphite sheets based on a heat-and-current treatment of filtrated, exfoliated graphite flakes. This treatment combines heating (~ 900 °C) and in-plane electrical current flow (550 A·cm−2) to improve electrical conductivity through the reduction of crystalline defects. This process was shown to require only a 1-min treatment time, which resulted in a 2.1-fold increase in electrical conductivity (from 1088 ± 72 to 2275 ± 50 S·cm−1). Structural characterization by Raman spectroscopy and X-ray diffraction indicated that the improvement electrical conductivity originated from a 30-fold improvement in the crystallinity (Raman G/D ratio increase from 2.8 to 85.3) with no other observable structural transformations. Significantly, this treatment was found to act uniformly across a macroscopic (10 mm) sheet surface indicating it is on the development of applications, such as electrodes for energy generation and storage and electromagnetic shielding, as well as on the potential for the development of large-scale treatment technologies.

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“…For example, the heating of SWCNTs at 1000–2400 °C has resulted in a coalescence of SWCNTs into larger diameter double-walled carbon nanotubes (DWCNTs) and MWCNTs [ 14 , 15 ]. In addition, the improvement in electrical and thermal properties of SWCNTs can occur from various structural changes, such as wall number, diameter, and crystallinity, but each of these structures are affected by high-temperature treatments (1500–2000 °C) [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

Scalability of the Heat and Current Treatment on SWCNTs to Improve their Crystallinity and Thermal and Electrical Conductivities

et al. 2015

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We have investigated the scalability of our post-synthesis graphitization process for single-walled carbon nanotubes (SWCNTs), which applies heat and current to SWCNTs to improve the thermal and electrical conductivities. This investigation was performed by examining the relationship between the processing conditions and the amount of treated SWCNTs. Characterization of all cases of treated SWCNTs showed the same level of improvement of ~3 times to both the thermal and electrical conductivities and that the SWCNTs remained SWCNTs, i.e., no change in diameter or wall number. These results provided evidence that the ability to improve the crystallinity of the SWCNTs was independent of the treatment amount. Further, our results showed that an increase in SWCNT amount required increased applied current density or increased in applied temperature to achieve optimum property improvement. Finally, we found a trade-off between the current density and temperature indicating that either a high current or high temperature was required to achieve the optimum process conditions. These results demonstrated that our heat and current SWCNT treatment was fundamentally scalable and applied towards larger scale (i.e., gram-level or more) amounts of SWCNT.

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Elucidating the effect of heating induced structural change on electrical and thermal property improvement of single wall carbon nanotube

Cited by 17 publications

References 31 publications

A Meta‐Analysis of Conductive and Strong Carbon Nanotube Materials

A Meta‐Analysis of Conductive and Strong Carbon Nanotube Materials

Crystalline and Electrical Property Improvement of Filtrated, Exfoliated Graphite Sheets by an In-Plane Current and Heating Treatment

Scalability of the Heat and Current Treatment on SWCNTs to Improve their Crystallinity and Thermal and Electrical Conductivities

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