Vertically aligned single-walled carbon nanotubes for electrical power storage and the electronics marketplace

Charging up with carbon nanotubes
Photograph and schematic representation (inset) of a scaled-up sample of vertically-aligned solitary-walled carbon nanotubes (VA-SWCNTs) developed on Inconel steel foil. Side shots show 50 percent-cells centered on VA-SWCNT anodes illuminating red, yellow and green LEDs. Credit: Lawrence Livermore Countrywide Laboratory

Lawrence Livermore Countrywide Laboratory (LLNL) scientists have designed vertically aligned one-walled carbon nanotubes on steel foils that could be a boon for electricity storage and the electronics industry.

Vertically aligned carbon nanotubes (VACNTs) have outstanding mechanical, electrical and transport houses in addition to an aligned architecture, which is important for programs these types of as membrane separation, thermal management, fiber spinning, electronic interconnects and strength storage.

To day, popular integration of VACNTs into following-technology technologies is thwarted by a absence of suitable, economic, mass-manufacturing capabilities. Superior-high-quality VACNTs are ordinarily manufactured on substrates this kind of as silicon (Si) or quartz wafers that are rigid, high-priced and electrically insulating.

Soon after checking out steel foil selections in scientific literature, the LLNL staff turned to Inconel metallic substrates allowing them to combine VACNTs into flexible equipment, get rid of a transfer stage from Si to other substrates and minimize electrical or thermal transport resistances at the interface in between CNTs and the substrate, which is important for electronic and strength storage apps. Inconel is a spouse and children of nickel-chromium-primarily based superalloys that are oxidation-corrosion-resistant supplies effectively-suited for support in extreme environments subjected to tension and heat.

“Transitioning expansion of superior-top quality CNTs from common Si substrates to steel foils opens the door to additional economical, significant-scale, semicontinuous and roll-to-roll manufacturing of multifunctional CNT composites, nanoporous membranes and electrochemical gadgets,” reported LLNL scientist Francesco Fornasiero, co-writer of a paper showing in the journal ACS Utilized Materials & Interfaces.

Synthesis of significant-quality one-walled CNTs (SWCNTs) on metallic foils would be specially important for electrical power-storage equipment, this kind of as lithium-ion batteries (LIBs). When graphitic supplies are common LIB anodes, their ability falls small of swiftly evolving electricity-storage demands.

“The large area area and outstanding digital conductivity of CNTs make them key candidates for high-potential, significant-charge electrochemical programs,” explained LLNL scientist Kathleen Moyer-Vanderburgh, direct author of the paper. “In unique, VA-SWCNTs grown on steel foils could supply a binder-free platform with powerful adhesion between the SWCNT and present-day collector, increased conductivity and aligned channels for rapid Li-ion diffusion.”

The LLNL team grew forests of vertically aligned SWCNT on Inconel steel for use as a LIB anode. Team associates found nearly invariant structural houses of the CNT forests above a extensive variety of synthesis disorders and for multiple metal substrates. Fabricated VA-SWCNT LIB anode shown steady biking for hundreds of cycles and large capability even at high biking premiums.

“Our results suggest that these SWCNTs on Inconel steel are promising components for superior-overall performance electrochemical devices,” stated LLNL scientist Jianchao Ye.

Extra facts:
Kathleen Moyer-Vanderburgh et al, Expansion and Performance of Significant-Excellent SWCNT Forests on Inconel Foils as Lithium-Ion Battery Anodes, ACS Applied Products & Interfaces (2022). DOI: 10.1021/acsami.2c18396

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Lawrence Livermore

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Carbon nanotubes could help electronics withstand outer space’s harsh conditions

Carbon nanotubes could help electronics withstand outer space's harsh conditions
A memory chip was made of transistors with carbon nanotubes that maintained their electrical properties and memory after being bombarded by high amounts of radiation. Credit: Adapted from ACS Nano 2021, DOI: 10.1021/acsnano.1c04194

Space missions, such as NASA’s Orion that will take astronauts to Mars, are pushing the limits of human exploration. But during their transit, spacecrafts encounter a continuous stream of damaging cosmic radiation, which can harm or even destroy onboard electronics. To extend future missions, researchers reporting in ACS Nano show that transistors and circuits with carbon nanotubes can be configured to maintain their electrical properties and memory after being bombarded by high amounts of radiation.

The lifetime and distance of deep space missions are currently limited by the energy efficiency and robustness of the technology driving them. For example, harsh radiation in space can damage electronics and cause data glitches, or even make computers break down completely. One possibility is to include carbon nanotubes in widely used electronic components, such as field-effect transistors. These single-atom-thick tubes are expected to make transistors more energy efficient compared to more run-of-the-mill silicon-based versions. In principle, the ultra-small size of the nanotubes should also help reduce the effects that radiation would have when striking memory chips containing these materials. However, the radiation tolerance for carbon nanotube field-effect transistors has not been widely studied. So, Pritpal Kanhaiya, Max Shulaker and colleagues wanted to see if they could engineer this type of field-effect transistor to withstand high levels of radiation, and build memory chips based on these transistors.

To do this, the researchers deposited carbon nanotubes on a silicon wafer as the semiconducting layer in field-effect transistors. Then, they tested different transistor configurations with various levels of shielding, consisting of thin layers of hafnium oxide and titanium and platinum metal, around the semiconducting layer. The team found that placing shields both above and below the carbon nanotubes protected the transistor’s electrical properties against incoming radiation up to 10 Mrad—a level much higher than most silicon-based radiation-tolerant electronics can handle. When a shield was only placed beneath the carbon nanotubes, they were protected up to 2 Mrad, which is comparable to commercial silicon-based radiation-tolerant electronics. Finally, to achieve a balance between fabrication simplicity and radiation robustness, the team built static random-access memory (SRAM) chips with the bottom shield version of the field-effect transistors. Just as with experiments performed on the transistors, these memory chips had a similar X-ray radiation threshold as silicon-based SRAM devices.

These results indicate that carbon nanotube field-effect transistors, especially double-shielded ones, could be a promising addition to next-generation electronics for space exploration, the researchers say.

Radiation-immune and repairable chips to fabricate durable electronics

More information:
Carbon Nanotubes for Radiation-Tolerant Electronics, ACS Nano (2021). DOI: 10.1021/acsnano.1c04194
Provided by
American Chemical Society

Carbon nanotubes could help electronics withstand outer space’s harsh conditions (2021, October 27)
retrieved 29 October 2021

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