Abstract

Carbon nanotube (CNT) conductors are an enabling technology for advancing the efficacy of sustainable energy systems. In parallel, proactive consideration for each of the phases in the material life cycle can enhance device performance while minimizing unwanted impacts. Increasing the yield of CNTs through advances in synthesis will help reduce the electricity, chemicals, and costs associated with their production. Modifications to the nanoscale morphology (alignment, bundling, density and lower contact resistances) are needed to improve the CNT material properties to meet or exceed those of conventional metallic conductors. Also, a robust evaluation of methods for contacting carbon-based wires is needed when interfacing with metallic contacts. Finally, it's important to begin looking at upstream options for proper treatment of waste streams containing CNT conductors when they reach the end of their useable life. Therefore, the subject of this dissertation focuses on the development of functional CNT conductors and considers approaches to improve each phase of their life cycle. Specifically, progress towards using more efficient catalysts in the laser vaporization process has led to a 50% increase in SWCNT yield and simplified the purification procedure. The use of chemical dopants such as KAuCl4 has increased the electrical conductivity up to 1x106 S/m which is over an order of magnitude higher than the pre-doping baseline value. Alternatively, chlorosulfonic acid was used to disperse high weight loadings of SWCNTs and modify the nanoscale morphology through the use of selective coagulation and mechanical extrusions of binder free SWCNT wires. The highly dense and aligned wires have electrical conductivities as high as 4.9x106 S/m and are in agreement with the highest CNT conductivities reported. The ability to contact bulk CNT conductors through ultrasonic welding was demonstrated for the first time and exhibit low carbon-copper contact resistances of 4.3 mΩ-cm2. Finally, a refunctionalization procedure was developed for upcycling end-of-life CNT electrodes from lithium ion anodes. This is the first reported recycling procedure developed for CNT materials and was successful in reducing the direct electricity consumption by 75 % and the volumetric waste generation by 66 % compared to synthesizing new CNT materials. Overall, CNT based conductors have been enhanced at each point in their life cycle the results presented in this dissertation represent a significant step forward towards manufacturing of next generation carbon conductors.

Library of Congress Subject Headings

Carbon nanotubes--Electric properties; Nanotubes--Materials; Electric conductivity; Product life cycle; Remanufacturing

Publication Date

5-10-2013

Document Type

Dissertation

Student Type

Graduate

Department, Program, or Center

Sustainability (GIS)

Advisor

Landi, Brian

Comments

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works. Physical copy available through RIT's The Wallace Library at: TA418.9.N35 S34 2013

Campus

RIT – Main Campus

Plan Codes

SUST-PHD

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