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1.
ACS Nano ; 11(8): 8464-8470, 2017 08 22.
Article in English | MEDLINE | ID: mdl-28767215

ABSTRACT

The determination of structural evolution at the atomic level is essential to understanding the intrinsic physics and chemistries of nanomaterials. Mechanochemistry represents a promising method to trace structural evolution, but conventional mechanical tension generates random breaking points, which makes it unavailable for effective analysis. It remains difficult to find an appropriate model to study shear deformations. Here, we synthesize high-modulus carbon nanotubes that can be cut precisely, and the structural evolution is efficiently investigated through a combination of geometry phase analysis and first-principles calculations. The lattice fluctuation depends on the anisotropy, chirality, curvature, and slicing rate. The strain distribution further reveals a plastic breaking mechanism for the conjugated carbon atoms under cutting. The resulting sliced carbon nanotubes with controllable sizes and open ends are promising for various applications, for example, as an anode material for lithium-ion batteries.

2.
Adv Mater ; 28(30): 6429-35, 2016 Aug.
Article in English | MEDLINE | ID: mdl-27183868

ABSTRACT

Thin and flexible supercapacitors with low cost and individual variation are fabricated by a new and efficient slicing method. Tunable output voltage and energy can be realized with a high specific capacitance of 248.8 F g(-1) or 150.8 F cm(-3) , which is well maintained before and after bending.

3.
Sci Adv ; 1(4): e1500166, 2015 May.
Article in English | MEDLINE | ID: mdl-26601185

ABSTRACT

Highly crystalline mesoporous materials with oriented configurations are in demand for high-performance energy conversion devices. We report a simple evaporation-driven oriented assembly method to synthesize three-dimensional open mesoporous TiO2 microspheres with a diameter of ~800 nm, well-controlled radially oriented hexagonal mesochannels, and crystalline anatase walls. The mesoporous TiO2 spheres have a large accessible surface area (112 m(2)/g), a large pore volume (0.164 cm(3)/g), and highly single-crystal-like anatase walls with dominant (101) exposed facets, making them ideal for conducting mesoscopic photoanode films. Dye-sensitized solar cells (DSSCs) based on the mesoporous TiO2 microspheres and commercial dye N719 have a photoelectric conversion efficiency of up to 12.1%. This evaporation-driven approach can create opportunities for tailoring the orientation of inorganic building blocks in the assembly of various mesoporous materials.

4.
Angew Chem Int Ed Engl ; 54(36): 10539-44, 2015 Sep 01.
Article in English | MEDLINE | ID: mdl-26178766

ABSTRACT

An aligned and laminated sulfur-absorbed mesoporous carbon/carbon nanotube (CNT) hybrid cathode has been developed for lithium-sulfur batteries with high performance. The mesoporous carbon acts as sulfur host and suppresses the diffusion of polysulfide, while the CNT network anchors the sulfur-absorbed mesoporous carbon particles, providing pathways for rapid electron transport, alleviating polysulfide migration and enabling a high flexibility. The resulting lithium-sulfur battery delivers a high capacity of 1226 mAh g(-1) and achieves a capacity retention of 75% after 100 cycles at 0.1 C. Moreover, a high capacity of nearly 900 mAh g(-1) is obtained for 20 mg cm(-2), which is the highest sulfur load to the best of our knowledge. More importantly, the aligned and laminated hybrid cathode endows the battery with high flexibility and its electrochemical performances are well maintained under bending and after being folded for 500 times.

6.
Adv Mater ; 27(8): 1363-9, 2015 Feb 25.
Article in English | MEDLINE | ID: mdl-25641501

ABSTRACT

Stretchable lithium-ion batteries (LIBs) consisting of an arch structure and a stretchable anode and cathode are developed using a general strategy. The LIB maintains a remarkable and stable electrochemical performance after hundreds of stretching cycles at a strain of 400%. Compared with other stretchable LIBs, which stretch at the device level, but whose components (electrodes) remain rigid, the component-level stretchability is here the design key to the LIB's highly stable performance.

7.
Adv Mater ; 27(2): 356-62, 2015 Jan 14.
Article in English | MEDLINE | ID: mdl-25424189

ABSTRACT

A fiber-shaped supercapacitor that can be stretched over 400% is developed by using two aligned carbon nanotube/polyaniline composite sheets as electrodes. A high specific capacitance of approximately 79.4 F g(-1) is well maintained after stretching at a strain of 300% for 5000 cycles or 100.8 F g(-1) after bending for 5000 cycles at a current density of 1 A g(-1). In particular, the high specific capacitance is maintained by 95.8% at a stretching speed as high as 30 mm s(-1).

8.
Small ; 11(6): 675-80, 2015 Feb 11.
Article in English | MEDLINE | ID: mdl-25236579

ABSTRACT

Power yourself up: a sweater made from solar cells! Stretchable and wearable fibers are shown to be highly efficient polymer solar cells. Their stable energy conversion efficiency variation is below 10% even after 1000 bending cycles or stretching under a strain of 30%. These fibers can easily be woven into fabric from which any type of clothing can be made.

9.
Adv Mater ; 26(48): 8126-32, 2014 Dec 23.
Article in English | MEDLINE | ID: mdl-25338545

ABSTRACT

An electrochromic fiber-shaped super-capacitor is developed by winding aligned carbon nanotube/polyaniline composite sheets on an elastic fiber. The fiber-shaped supercapacitors demonstrate rapid and reversible chromatic transitions under different working states, which can be directly observed by the naked eye. They are also stretchable and flexible, and are woven into textiles to display designed signals in addition to storing energy.

10.
Angew Chem Int Ed Engl ; 53(43): 11571-4, 2014 Oct 20.
Article in English | MEDLINE | ID: mdl-25154353

ABSTRACT

An all-solid-state, lightweight, flexible, and wearable polymer solar cell (PSC) textile with reasonable photovoltaic performance has been developed. A metal textile electrode made from micrometer-sized metal wires is used as the cathode, and the surfaces of the metal wires are dip-coated with the photoactive layers. Two ultrathin, transparent, and aligned carbon nanotube sheets that exhibit remarkable electronic and mechanical properties were coated onto the modified metal textile at both sides as the anode to produce the desired PSC textile. Because of the designed sandwich structure, the PSC textile displays the same energy conversion efficiencies regardless of which side it is irradiated from. As expected, the PSC textiles are highly flexible, and their energy conversion efficiencies varied by less than 3% after bending for more than 200 cycles. The PSC textile shows an areal density (5.9 mg cm(-2)) that is lower than that of flexible film-based PSCs (31.3 mg cm(-2)).

11.
Angew Chem Int Ed Engl ; 53(36): 9526-31, 2014 Sep 01.
Article in English | MEDLINE | ID: mdl-25044134

ABSTRACT

Electrically conducting wires play a critical role in the advancement of modern electronics and in particular are an important key to the development of next-generation wearable microelectronics. However, the thin conducting wires can easily break during use, and the whole device fails to function as a result. Herein, a new family of high-performance conducting wires that can self-heal after breaking has been developed by wrapping sheets of aligned carbon nanotubes around polymer fibers. The aligned carbon nanotubes offer an effective strategy for the self-healing of the electric conductivity, whereas the polymer fiber recovers its mechanical strength. A self-healable wire-shaped supercapacitor fabricated from a wire electrode of this type maintained a high capacitance after breaking and self-healing.

12.
Adv Mater ; 26(26): 4444-9, 2014 Jul 09.
Article in English | MEDLINE | ID: mdl-24789733

ABSTRACT

Smart supercapacitors are developed by depositing conducting polymers onto aligned carbon-nanotube sheets. These supercapacitors rapidly and reversibly demonstrate color changes in response to a variation in the level of stored energy and the chromatic transitions can be directly observed by the naked eye.

13.
Adv Mater ; 26(3): 466-70, 2014 Jan 22.
Article in English | MEDLINE | ID: mdl-24174379

ABSTRACT

An all-solid-state, coaxial and self-powered "energy fiber" is demonstrated that simultaneously converts solar energy to electric energy and further stores it. The "energy fiber" is flexible and can be scaled up for the practical application by the well-developed textile technology, and may open a new avenue to future photoelectronics and electronics.

14.
Adv Mater ; 25(44): 6436-41, 2013 Nov 26.
Article in English | MEDLINE | ID: mdl-23955920

ABSTRACT

A coaxial electric double-layer capacitor fiber is developed from the aligned carbon nanotube fiber and sheet, which functions as two electrodes with a polymer gel sandwiched between them. The unique coaxial structure enables a rapid transportation of ions between the two electrodes with a high electrochemical performance. These energy storage fibers are also flexible and stretchable, and can be woven into and widely used for electronic textiles.

15.
Adv Mater ; 25(41): 5965-70, 2013 Nov 06.
Article in English | MEDLINE | ID: mdl-23956005

ABSTRACT

A flexible and weaveable electric double-layer capacitor wire is developed by twisting two aligned carbon nanotube/ordered mesoporous carbon composite fibers with remarkable mechanical and electronic properties as electrodes. This capacitor wire exhibits high specific capacitance and long life stability. Compared with the conventional planar structure, the capacitor wire is also lightweight and can be integrated into various textile structures that are particularly promising for portable and wearable electronic devices.

16.
Angew Chem Int Ed Engl ; 52(30): 7776-80, 2013 Jul 22.
Article in English | MEDLINE | ID: mdl-23775762

ABSTRACT

Making sense: A novel polyacetylene composite material with incorporated aligned carbon nanotubes shows rapid changes in both fluorescent intensity and color appearance in response to applied electric currents, and these electrochromatic transitions remain reversible even after a thousand cycles. The composite material is anticipated to be suitable for various other sensing applications.

17.
Adv Mater ; 23(45): 5436-9, 2011 Dec 01.
Article in English | MEDLINE | ID: mdl-22021101

ABSTRACT

Aligned carbon nanotube sheets are developed as a new family of electrodes to fabricate dye-sensitized solar cells. The energy conversion efficiency of the resulting cell is higher than the randomly dispersed carbon nanotube film and comparable with the platinum. Novel and flexible solar cells can be easily made from such carbon nanotube sheets with high potentials.


Subject(s)
Electric Power Supplies , Nanotubes, Carbon/chemistry , Organic Chemicals/chemistry , Sunlight , Electric Conductivity , Electrodes
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