Energy storage in carbon nanotube super-springs

A new technology is proposed for lightweight, high density energy storage. The objective of this thesis is to study the potential of storing energy in the elastic deformation of carbon nanotubes (CNTs). Prior experimental and modeling studies of the mechanical properties of CNTs have revealed nanoscale structures with a unique combination of high stiffness, strength and flexibility. With a Young's modulus of 1 TPa and the ability to sustain reversible tensile strains of 6% [1, 2] and potentially as high as 20% [3-5], mechanical springs based on these structures are likely to surpass the current energy storage capabilities of existing steel springs and provide a viable alternative to electrochemical batteries. Models were generated to estimate the strain energy of CNTs subject to axial tension, compression, bending and torsion. The obtainable energy density is predicted to be highest under tensile loading, with an energy density in the springs themselves about 2500 times greater than the maximum energy density that can be reached in steel springs, and ten times greater than the energy density of lithium-ion batteries. Practical systems will have lower overall stored energy density once the mass and volume of the spring's support structure and any additional extraction hardware are taken into account, with a maximum achievable stored energy density predicted to be comparable to lithium-ion batteries. Due to the poor load transfer between MWCNT shells and the radial deformation of larger SWCNTs, bundles of SWCNTs with diameters of 1 nm or smaller are identified as the best structure for high-performance springs. The conceptual design of a rechargeable portable power source is developed as a tool to study the performance and feasibility of building such a device.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Hill, Frances Ann

Advisor dc:contributor.advisor

• Carol Livermore.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/44887

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/44887