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dc.contributor.authorGraves, Brian Mackenzie
dc.date.accessioned2020-03-23T09:51:41Z
dc.date.available2020-03-23T09:51:41Z
dc.date.issued2020-05-16
dc.date.submitted2019-09-26
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/303663
dc.description.abstractCarbon nanotubes (CNTs) possess numerous exceptional structural, thermal, and electrical properties that have the potential to be highly disruptive and impactful in many areas of technology. Unfortunately, synthesis methods of CNT-containing materials are often complex, expensive, and require prefabricated precursors. For CNT-based materials to experience widespread adoption, they must be produced by simple, inexpensive, and scalable means. The outcome of this work presents straightforward, fast, and industrially-relevant processes using microwave plasma for synthesis of CNT materials starting from widely-available, inexpensive precursor materials. The plasma system has been developed to accommodate multiple gases including mixtures with hydrogen fractions of at least 50%. Stabilization has been accomplished with custom ceramic "axial" and "swirl" torches which result in low background particle generation and the ability to operate nearly indefinitely with little to no component wear. The excitation temperature and electron density of the plasma were characterized using the Boltzmann plot method with a rubidium aerosol as a tracer species. The first application of the plasma system was to produce a metal oxide-CNT hybrid material for lithium-ion battery anodes. The process is both fully continuous and fast (~5 seconds from raw precursors to final product). The metal oxide particles are formed from readily-available coarse powders using a bespoke powder feeder and the final product was well-characterized using aerosol methods that agreed well with microscopy results. This anode material eliminated the need for a conductive additive in the electrode, and showed both good capacity recovery from high-rate cycling and promising long-term stability. Finally, work towards a high mass throughput CNT production process is also presented. High-quality CNTs were synthesized using the axial torch. Using the swirl torch, higher hydrogen fractions could be achieved and the carbon precursor could be introduced through the front of the reactor. This led to abundant growth of long CNTs (tens of µm) with diameters of ~50 nm. Given additional parameter optimization, it is likely that mass throughput could be increased further and aerogel formation may be possible. Fast, scalable processes such as those presented here may contribute to the widespread integration of CNTs in the next generation of high performance materials.
dc.description.sponsorshipEquipment funded by EPSRC grant EP/ M015211/1 (Advanced Nanotube Application and Manufacturing Initiative) Personal funding from Cambridge Trust, Churchill Society of Edmonton, and National Sciences and Engineering Research Council of Canada
dc.language.isoen
dc.rightsAll rights reserved
dc.subjectPlasma
dc.subjectCarbon Nanotube
dc.subjectSynthesis
dc.subjectScalable
dc.subjectMicrowave
dc.subjectLi-Ion
dc.subjectLithium Ion
dc.subjectAerogel
dc.subjectCatalyst
dc.subjectAtmospheric Pressure
dc.subjectTemperature
dc.subjectMetal Oxide
dc.subjectAnode
dc.subjectRubidium
dc.subjectBoltzmann Plot
dc.subjectTorch
dc.subjectAerosol
dc.subjectElectron Density
dc.subjectHybrid
dc.subjectHigh Throughput
dc.subjectProcess
dc.subjectCVD
dc.subjectFloating Catalyst
dc.subjectContinuous
dc.subjectOptical Emission Spectroscopy
dc.subjectOES
dc.subjectHydrogen
dc.subjectNitrogen
dc.subjectArgon
dc.subjectHelium
dc.subjectStabilization
dc.subjectTracer
dc.subjectPowder
dc.subjectPrecursor
dc.subjectDistribution
dc.titleSynthesis of Carbon Nanotube Materials from a Microwave Plasma
dc.typeThesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridge
dc.publisher.departmentEngineering
dc.date.updated2020-03-20T13:42:55Z
dc.identifier.doi10.17863/CAM.50740
dc.contributor.orcidGraves, Brian Mackenzie [0000-0002-5282-5253]
dc.publisher.collegeChurchill
dc.type.qualificationtitlePhD in Engineering
cam.supervisorBoies, Adam
cam.supervisor.orcidBoies, Adam [0000-0003-2915-3273]
cam.thesis.fundingfalse


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