Development of Carbon Nanotube Manufacturing and Applications

This WTEC study focuses on the manufacturing and applications of carbon nanotubes (CNTs) to identify recent progress in understanding the commercial potential of CNTs as viewed by academic, industrial, and government research facilities around the world. CNT manufacturing methods and equipment, processing and separation techniques, characterization procedures, and opportunities for international collaboration are highlighted in this study. These issues are also discussed in the context of leading electronic, optical, and mechanical applications of CNTs ranging from transistors to structural composites. CNTs can be produced by many methods, and depending on the diameter, one can obtain either single-walled CNTs (SWCNTs) or multi-walled CNTs (MWCNTs). The current capacity for the production of MWCNTs far exceeds that of SWCNTs. SWCNTs are much more expensive and difficult to manufacture than MWCNTs, and there is not yet a distinct large-scale market for SWCNTs, which is needed to drive down the production cost. For both types of CNTs, Asia’s production capacity is two to three times higher than that estimated for North America and Europe combined; Japan is the prominent leader in the production of MWCNTs. Use of CNTs in lithium-ion battery electrodes is the current driving force of ton-scale MWCNT production in Japan. CNT-replacement products for indium tin oxide (ITO) and field emission devices (FEDs) are driving increased production of SWCNTs, whereas applications using transistors require precise control over CNT diameter and conductivity, which is farther from commercial realization. When the cost of bulk SWCNTs decreases significantly, applications in electromagnetic shielding (EMI) and electrostatic discharge (ESD) protection can be expected, and SWCNTs will replace MWCNTs in conductive plastics. Currently, owing to challenges in CNT functionalization and dispersion, CNTs can only achieve modest enhancements in mechanical properties of materials. While sporting goods with CNT reinforcement are beginning to appear on the market, improved processing techniques along with manufacturing techniques for long and aligned CNTs (e.g., yarns and aligned arrays) are needed to realize CNT-based materials that provide compelling advantages over existing fiber composites in lightweight structures. World Technology Evaluation Center, Inc. (WTEC) R.D. Shelton, President Michael DeHaemer, Executive Vice President Geoffrey M. Holdridge, Vice President for Government Services David Nelson, Vice President for Development Y.T. Chien, Senior Fellow Hassan Ali, Director of International Study Operations Maria L. DeCastro, Director of Publications, Editor Masanobu Miyahara, Advance Contractor (Japan) Gerald Hane, Advance Contractor (China and Korea) Copyright 2007 by WTEC, Inc. The U.S. Government retains a nonexclusive and nontransferable license to exercise all exclusive rights provided by copyright. Some WTEC final reports are distributed by the National Technical Information Service (NTIS) of the U.S. Department of Commerce. A list of available WTEC reports and information on ordering them from NTIS is on the inside back cover of this report.