B. Gao

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.

Dynamic radiography using a carbon-nanotube-based field-emission x-ray source

We report a dynamic radiography system with a carbon nanotube based field-emission microfocus x-ray source. The system can readily generate x-ray radiation with continuous variation of temporal resolution as short as nanoseconds. Its potential applications for dynamic x-ray imaging are demonstrated. The performance characteristics of this compact and versatile system are promising for noninvasive imaging in biomedical research and industrial inspection.

A nanotube-based field emission x-ray source for microcomputed tomography

Microcomputed tomography (micro-CT) is a noninvasive imaging tool commonly used to probe the internal structures of small animals for biomedical research and for the inspection of microelectronics. Here we report the development of a micro-CT scanner with a carbon nanotube- (CNT-) based microfocus x-ray source. The performance of the CNT x-ray source and the imaging capability of the micro-CT scanner were characterized.

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.

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.