L. Fleming

Electrochemical intercalation of single-walled carbon nanotubes with lithium

Abstract Single-walled carbon nanotubes (SWNT) synthesized by laser ablation were electrochemically intercalated with lithium. As-grown SWNTs showed a reversible saturation composition of Li 1.2 C 6 (450 mAh g −1 ). After removing the impurity phases by filtration, the reversible saturation composition increased to Li 1.6 C 6 (600 mAh g −1 ), significantly higher than the ideal value of LiC 6 (372 mAh g −1 ) for graphite. All the SWNT materials showed large irreversible capacities and voltage hysteresis. Upon processing the nanotubes by ball-milling, the reversible Li capacity increased to 1000 mAh g −1 (Li 2.7 C 6 ) while the irreversible capacity decreased to 650 mAh g −1 .

Enhanced saturation lithium composition in ball-milled single-walled carbon nanotubes

Abstract The effects of processing on the structure and morphology of single-walled carbon nanotubes (SWNT) and their electrochemical intercalation with lithium were investigated. Purified SWNTs were processed by impact ball-milling and were electrochemically intercalated with lithium. The reversible saturation Li composition increased from Li 1.7 C 6 in purified SWNTs to Li 2.7 C 6 after 10 min of milling. The irreversible capacity decreased from Li 3.2 C 6 to Li 1.3 C 6 . Electron microscopy, Raman and X-ray diffraction measurements indicated that ball-milling induced disorder within the bundles and fractured the nanotubes.

Fabrication and properties of composites of poly(ethylene oxide) and functionalized carbon nanotubes

Abstract : We show that composites with improved uniformity and dispersion can be formed using chemically functionalized carbon nanotubes. A significant enhancement of the mechanical properties was obtained at low nanotube loading. In contrary to previous results from pristine nanotubes, the composites show efficient load transfer between the fillers and matrix.

Application of carbon nanotubes as electrodes in gas discharge tubes

turn-on fields. Recent experiments have reported turn-on electric fields in the range of 1.5‐3 V/mm. 3‐5 The nanotubes emitters, especially the SWNTs, are capable of producing stable electron emission with a current density exceeding 4 A/cm 2 ~Ref. 5! which make them attractive cold-cathode materials for microvacuum electronic applications. Assynthesized SWNTs are in the form of either free-standing mat or powder, unsuitable for device applications. We have processed the raw materials to uniform films by a spray method. 6 Adhesion between the substrates and the films is enhanced by introducing either a carbon-dissolving or a carbide-forming metal interlayer. In this letter, we report the effects of carbon nanotube coating on the performance of the gas discharge tubes. The direct current ~dc! breakdown voltages of GDTs fabricated using SWNT-coated electrodes were measured and compared with commercial GDTs. A significant reduction in the breakdown voltage and voltage fluctuation ~over 1000 surges! was observed for the nanotubebased GDTs as compared to typical commercial devices.

Lithium intercalation into etched single-wall carbon nanotubes

Abstract The effects of structure and morphology on lithium storage in single-wall carbon nanotubes (SWNTs) were studied by electrochemistry. SWNTs were chemically etched and were intercalated with Li. The reversible Li storage capacity increased from LiC6 in close-end SWNTs to LiC3 after etching, which is twice the value observed in Li intercalated graphite. The enhanced capacity is attributed to Li diffusion into the interior of the SWNTs through the opened ends and sidewall defects.

Formation of macroscopically ordered carbon nanotube membranes by self-assembly

Abstract In this paper, we report the formation membranes of the aligned single-wall carbon nanotube (SWNT) bundles on a substrate by self-assembly. SWNTs produced by the laser ablation method and purified by reflux and filtration were chemically etched to short bundles by ultrasonic-assisted oxidation. After removing the acid by filtration, the processed SWNTs were dispersed in de-ionized water. Thin film appears on the surface of a soaked glass substrate in the SWNTs/water dispersion with natural vaporization of water. Transmission electron microscopy measurements show that the SWNT bundles are uniaxially aligned.

Structure and Electrochemical Properties of Carbon Nanotube Intercalation Compounds

Abstract This article summarizes the current status of carbon nanotube intercalation compounds. It focuses on the structure and electrochemical properties of intercalated single-walled carbon nanotubes (SWNTs). Materials synthesis, purification and characterization methods are also discussed. This article draws mostly from works performed at UNC.

Lithium storage in single wall carbon nanotubes

The effects of structure and morphology on lithium storage in single wall carbon nanotubes (SWNTs) were studied by electrochemistry, x-ray diffraction and nuclear magnetic resonance (NMR) techniques. Purified SWNT bundles were chemically etched to variable lengths and were reacted with Li via the electrochemical and solid state routes. The reversible Li storage capacity increased from LiC6 in close-end SWNTs to LiC3 after etching. The increase is attributed to diffusion of the Li ions into the interior space of the individual SWNTs through the open ends and defects on the sidewalls.