Researchers from China developed double-walled carbon nanotube fibers (DWCNTF) that set new records for electrical conductivity. By using a dry-jet wet spinning method, this innovation significantly improves the alignment and density of the carbon nanotubes, resulting in superior performance.
DWCNTFs exhibit an extraordinary electrical conductivity of 1.1 × 10⁷ C/m and can carry a high current density of 8.0 × 10⁸ A/m². In addition, they have a tensile strength of 1.65 GPa and a viscosity of 130.9 MJ/m³, making them some of the strongest and most durable wet-spun carbon nanotube fibers available today.
Developed by a team at the Shenyang National Materials Science Laboratory, these fibers have the potential to be used in aerospace and other mission-critical industries, including energy storage.
High-performance fibers with excellent electrical conductivity, strength, and toughness are increasingly needed to replace traditional copper in various fields of application.
Advanced innovations
Carbon nanotubes (CNTs) are ideal for high-performance fibers due to their exceptional properties. However, these advantages are often negated when CNTs are formed into large fibers, mainly due to contact resistance and weak interaction between tubes.
The common wet spinning method provides high conductivity and sufficient strength, but is inferior to individual CNTs due to these problems.
CNT alignment and packing are critical to fiber performance, and cracks formed during production due to non-uniform diffusion in the bath further reduce performance by creating non-uniform pores.
To overcome these problems, the researchers applied the advanced method of “dry jet wet spinning”. This method improves fiber quality by better aligning polymers and reducing cracks, which was not previously applied to CNT fibers.
In their study, the researchers successfully fabricated DWCNTFs with high conductivity and capacity by spinning long, high-molecular-weight DWCNTs with a stable air gap, achieving excellent alignment and density. The fibers achieved a high orientation coefficient of 0.994 and a density of 1.96 g/cm³.
Record Conductivity
The team's research shows that their fibers achieve record high electrical conductivity, reaching 86 percent of the conductivity of copper, an important indicator for electrical performance. In addition to impressive conductivity, the fibers also exhibit a tensile strength of 1.65 GPa, one of the highest for fibers produced using this method.
The researchers also tested the durability of the fibers, finding that their integrity and conductivity remained intact even after more than 5,000 bending cycles. This improvement in fiber performance solves previous problems related to contact resistance and weak intertube interaction, marking a significant improvement in carbon nanotube fiber technology, according to the South China Morning Post (SCMP).
Currently, carbon fiber is the standard for high-performance materials in advanced industries such as aerospace, and companies such as Airbus and Boeing use carbon fiber-reinforced composite materials in their aircraft modules.
However, carbon nanotubes may outperform carbon fiber , offering greater efficiency and opening up new possibilities for applications such as energy storage and space elevators.
Fun fact! Since their discovery in 1991, carbon nanotubes, also known as bactubes, were recognized as revolutionary materials. Researchers have been improving their production for over 20 years.