Microstructural origin of resistance–strain hysteresis in carbon nanotube thin film conductors

Jin, Lihua; Chortos, Alex; Lian, Feifei; Pop, Eric; Linder, Christian; Bao, Zhenan; Cai, Weiping

doi:10.1073/pnas.1717217115

Cited by 121 publications

(103 citation statements)

References 42 publications

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“…The ESR increased in first 200 cycles, and remained at around 1.75 R 0 for the rest 300 cycles test. 1D conductors, like carbon nanotube (CNT) thin films, have been reported to experience reorientation and sliding during loading . We presume similar process may happen for polypyrrole chains during stretching–releasing cycles and lead to small irreversible resistance changes.…”

Section: Resultsmentioning

confidence: 82%

Strong and Stretchable Polypyrrole Hydrogels with Biphase Microstructure as Electrodes for Substrate‐Free Stretchable Supercapacitors

Chen

Song

et al. 2019

Adv Materials Inter

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materials and stretchable substrates. [15] But these substrates are generally electrochemically nonactive elastomers, which would occupy a significant volume and mass in SSCs, and reduce specific capacitance and energy density of SSCs. In addition, due to the mismatch of Young's modulus of soft substrates and rigid electroactive materials, inevitable dislocation occurs at the interface upon a large deformation, which could damage the integrity and hence the electrochemical performance of SSCs. [16] On the other hand, specific structures can extend flexibility to stretchability. For instance, wavy structure [12][13][14] resembling spongy structure, also called winkled [17,18] or buckled structure, [19,20] can be used for rigid materials to achieve a certain level of stretchability, such as single-crystal Si, [21] graphene film, [17,19] and interwoven carbon nanotube. [18,20] Multistep processing is typically required to obtain these wavy structures, such as exploiting and removing buckled templates, [17] prestraining, and releasing elastic substrates. [18] Some fiber-shaped electroactive materials can be woven into overtwisted yarn [22][23][24][25] to achieve a certain level of stretchability. Besides these strategies, there are rarely any reports of stretchable supercapacitors without using elastic substrates or complicate fabrication, like wavy or yarn structures.Carbon-based materials [26,27] are often chosen as the electroactive materials of SSCs, while the specific capacitance of obtained SSC devices is limited by the low theoretical capacitance of carbon-based materials. In contrast, conducting polymers show a much higher specific capacitance, and are often composite with carbon materials to achieve enhanced capacitance. [22,[28][29][30] Recently, conductive polymer-based hydrogels (CPHs) have been developed for flexible supercapacitors, and these CPH-based flexible supercapacitors show enhanced specific capacitance and cycling stability. [31][32][33][34] However, the conductivity of most of current CPHs is typically in the range of 10 −4 -10 −1 S cm −1 , [35,36] which is not sufficient, and conductive supports are required as current collector to assemble electrodes. Since these conductive supports such as carbon cloth or metal mesh are not stretchable, the obtained CPH-based flexible supercapacitors are not stretchable. To bypass the usage of conductive supports, the development The development of stretchable supercapacitors (SSCs) is heading to compact and robust devices with higher capacitance and simpler preparation process. Herein, a new strategy is reported to prepare a highly stretchable and conductive polypyrrole hydrogel with a unique biphase microstructure (loose phase and dense phase), which is formed by the supramolecular assembly of polypyrrole (PPy), poly(vinyl alcohol), and anionic micelles. The loose phase enables the PPy hydrogel large stretchability (elongation at a break of 500%) and good electrochemical capacitive behavior, while the dense phase enables the PPy hydrogel high tensile stre...

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Section: Resultsmentioning

confidence: 82%

Strong and Stretchable Polypyrrole Hydrogels with Biphase Microstructure as Electrodes for Substrate‐Free Stretchable Supercapacitors

Chen

Song

et al. 2019

Adv Materials Inter

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“…However, in the second and third cycles, a minimal increase of the resistance compared to the initial value was observed when the electrode was released from 200% strain to 0%. The minimal increase of the resistance could be ascribed to the reorientation, sliding, and buckling of the CNTs yet no significant interfiber CNT film breakage during the loading–unloading cycles . As shown in Figure d, the resistance difference between the backward scan ( R b ) and the forward scan ( R f ) remained almost the same from the third to the fiftieth cycle.…”

Section: Resultsmentioning

confidence: 83%

Nylon Fabric Enabled Tough and Flaw Insensitive Stretchable Electronics

Sim

Gao

Zhou

et al. 2018

Adv Materials Technologies

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The architecture of stretchable electronics, typically in the fashion of very thin functional electronics on a stretchable rubber substrate, defines their mechanical robustness which is dominantly attributed to the stretchable rubber substrate. Most of the existing and reported stretchable electronics are vulnerable to flaws or cracks in the substrate and subject to fracture upon mechanical deformation, which limits their practical usages. Here, a class of tough and flaw insensitive stretchable electronics enabled by a Nylon/rubber composite substrate is reported. The woven and stretchable fibers in the Nylon fabric are responsible for its high toughness and flaw insensitivity, as they prevent crack propagation by dissipating the energy into the nearby fiber network and also the rubber matrix to yield enhanced toughness and flaw insensitivity. Stretchable electrodes, supercapacitors, and photodetectors with high toughness and flaw insensitivity are developed as examples to illustrate the validity of such a type of stretchable electronics. Systematic studies of the associated materials, fabrication, mechanical and electrical properties, and reliability illustrate the key aspects of such a type of stretchable tough and flaw insensitive electronics and also suggest routes toward stretchable electronics with other functions.

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“…Furthermore, the sensitivity of 1.0 wt.% H-MWNT/PDMS was greater than that of 1.0 wt.% L-MWNT/PDMS at the same content. This is because the aspect ratio of L-MWNT is smaller than that of H-MWNT, resulting in increased disconnections of the electrical networks in the MWNTs according to the change [ 15 , 35 ]. Therefore, a smaller aspect ratio of MWNT and decreased content (over P c ) are appropriate conditions for an MWNTs/PDMS composite bending sensor for improving the sensitivity.…”

Section: Resultsmentioning

confidence: 99%

“…In other words, if the bending and releasing actions are repeated, the position of the MWNTs in the composite varies and the MWNTs buckle because they undergo repeated bending and releasing deformation. Therefore, the electrical networks inside the composites are reshuffled, causing hysteresis [ 15 ].…”

Section: Resultsmentioning

confidence: 99%

“…The magnitude of the piezoresistive effect and the electrical properties vary depending on the dimension, content, and morphology of the filler [ 12 , 13 , 14 ]. In addition, hysteresis may occur due to changes in the position and shape of the fillers in the composite, which are induced by various external deformations [ 15 , 16 , 17 ]. The piezoresistive effect and the hysteresis phenomenon play an important role in the sensors.…”

Section: Introductionmentioning

confidence: 99%

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Bending Properties of Carbon Nanotube/Polymer Composites with Various Aspect Ratios and Filler Contents

2020

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The key characteristics of bending sensors are piezoresistive effect, hysteresis, and durability. In this study, to investigate the influence of the aspect ratio and contents of multi-walled nanotubes (MWNTs) on the properties of bending sensors, MWNT/polydimethylsiloxane (PDMS) composites were fabricated with various aspect ratios and filler contents. The MWNTs were uniformly dispersed in the composites using the three-roll milling method. By increasing the bending angle gradually, the sensitivity of each composite was analyzed. Furthermore, discontinuous cyclic bending tests were conducted to investigate the piezoresistive effect and hysteresis. In addition, stable repeatability of the composites was confirmed through continuous cyclic bending tests. As a result, optimal aspect ratios and filler contents have been presented for application in bending sensors of MWNT composites.

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Microstructural origin of resistance–strain hysteresis in carbon nanotube thin film conductors

Cited by 121 publications

References 42 publications

Strong and Stretchable Polypyrrole Hydrogels with Biphase Microstructure as Electrodes for Substrate‐Free Stretchable Supercapacitors

Strong and Stretchable Polypyrrole Hydrogels with Biphase Microstructure as Electrodes for Substrate‐Free Stretchable Supercapacitors

Nylon Fabric Enabled Tough and Flaw Insensitive Stretchable Electronics

Bending Properties of Carbon Nanotube/Polymer Composites with Various Aspect Ratios and Filler Contents

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