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Electrochemical intercalation of lithium-ion into carbon fibers prepared from synthetic cellulose precursor
Title
Electrochemical intercalation of lithium-ion into carbon fibers prepared from synthetic cellulose precursor.
Creator
Kashauer, Robert Lewis., Florida Atlantic University, Lipka, Stephen M., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
A number of fibrous carbon materials have been investigated as intercalation host materials. Commercially available rayon fiber (synthetic cellulose) based carbon fibers were synthesized for use as anode material in lithium-ion batteries. The effects of oxidation and carbonization temperature, heating ramp rate, soak time and gaseous atmosphere during thermal treatment on the electrochemical performance of the carbon fibers were studied. Intercalation/deintercalation experiments were...
Show moreA number of fibrous carbon materials have been investigated as intercalation host materials. Commercially available rayon fiber (synthetic cellulose) based carbon fibers were synthesized for use as anode material in lithium-ion batteries. The effects of oxidation and carbonization temperature, heating ramp rate, soak time and gaseous atmosphere during thermal treatment on the electrochemical performance of the carbon fibers were studied. Intercalation/deintercalation experiments were performed to evaluate the electrochemical performance of the carbon fibers. The highest reversible capacity and lowest irreversible capacity loss were obtained for carbon fibers carbonized at 1100C at a ramp rate of 10C/min held at soak times of 1 and 5 hours. Electrolyte containing 1M LiPF6 in 70/30 v/o EC:DMC proved to be most suitable for these carbon fiber materials. The influence of electrolyte composition (solvent and salt) on the reversible and irreversible capacities as well as on the intercalation/deintercalation potential profile were also studied.
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Date Issued
1997
PURL
http://purl.flvc.org/fcla/dt/15452
Subject Headings
Carbon fibers, Lithium cells, Electrolytes
Format
Document (PDF)
Carbon nano-fibers for electrochemical double-layer capacitors
Title
Carbon nano-fibers for electrochemical double-layer capacitors.
Creator
Cao, Xuejun., Florida Atlantic University, Lipka, Stephen M.
Abstract/Description
A novel carbon nano-fiber was prepared using catalytic vapor phase growth. Electrochemical capacitors were assembled using these fibers. Physical analysis was conducted on the carbon nano-fibers and electrochemical analysis was performed on capacitors made from these carbon nano-fibers. Scanning electron microscopy revealed that the nano-fibers had diameters ranging from 20nm to 400nm. X-ray diffraction showed the nano-fibers were more ordered than some commercial carbon fibers. BET...
Show moreA novel carbon nano-fiber was prepared using catalytic vapor phase growth. Electrochemical capacitors were assembled using these fibers. Physical analysis was conducted on the carbon nano-fibers and electrochemical analysis was performed on capacitors made from these carbon nano-fibers. Scanning electron microscopy revealed that the nano-fibers had diameters ranging from 20nm to 400nm. X-ray diffraction showed the nano-fibers were more ordered than some commercial carbon fibers. BET adsorption yielded specific surface areas of the nano-fibers at around 400 m$\sp2$/g. Electrochemical studies including cyclic voltammetry and electrochemical impedance spectroscopy indicated that capacitors made from carbon nano-fibers were promising for practical use. Further modification/activation of the carbon nano-fibers was conducted and capacitors made from these materials were also evaluated.
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Date Issued
1999
PURL
http://purl.flvc.org/fcla/dt/15622
Subject Headings
Capacitors, Electric double layer, Carbon fibers
Format
Document (PDF)
Lithium intercalation into PAN-based carbon fiber materials
Title
Lithium intercalation into PAN-based carbon fiber materials.
Creator
Nechev, Kamen S., Florida Atlantic University, Lipka, Stephen M., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
High energy density PAN-based carbon fiber anode materials for lithium-ion type batteries were developed. Commercially available organic precursors were thermally converted to carbons. The effects of precursor material, carbonization temperature, heating ramp rate, soak time and gaseous atmosphere during the thermal treatment on the electrochemical performance of the carbon fibers were studied. In order to evaluate the electrochemical performance of the carbon fibers, test cells were assemble...
Show moreHigh energy density PAN-based carbon fiber anode materials for lithium-ion type batteries were developed. Commercially available organic precursors were thermally converted to carbons. The effects of precursor material, carbonization temperature, heating ramp rate, soak time and gaseous atmosphere during the thermal treatment on the electrochemical performance of the carbon fibers were studied. In order to evaluate the electrochemical performance of the carbon fibers, test cells were assemble using the carbon materials prepared in the laboratory and intercalation/deintercalation experiments were performed. The results indicated that the highest reversible capacity and lowest irreversible capacity loss was obtained for carbon fibers carbonized at 1100C at fast ramp rate of 26C/min. X-ray diffraction experiments revealed a relation between the capacity and the irreversible capacity loss on first cycle, and the size of the crystallites Lc. A phenomenological explanation for this behavior was developed. Using electrochemical impedance spectroscopy the diffusion coefficient of Li in the tested carbon fibers was calculated. In addition, the influence of electrolyte composition (solvent and salt) on the reversible and irreversible capacities as well as on the intercalation/deintercalation potential profile was investigated. An electrolyte containing 1M LiPF6 in EC:DEC:DMC (40:30:30 v/o) proved to be most suitable for these carbon fiber materials improving significantly their electrochemical performance. Finally, coin cells were assembled containing the carbon fiber material prepared in the laboratory. They were tested for reversible and irreversible capacity. The coin cells proved that the synthesized carbon anode materials possess high energy density and could be used in commercial applications.
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Date Issued
1996
PURL
http://purl.flvc.org/fcla/dt/12471
Subject Headings
Lithium cells, Carbon fibers, Electric batteries
Format
Document (PDF)
Electrochemical behavior of carbon fiber cathode materials in organic electrolytes containing various lithium salts
Title
Electrochemical behavior of carbon fiber cathode materials in organic electrolytes containing various lithium salts.
Creator
Durand, Severine Nathalie., Florida Atlantic University, Lipka, Stephen M.
Abstract/Description
The intercalation of anions into carbon fiber from organic electrolytes containing lithium salts was studied. The reversible intercalation of anions into carbon could lead to the possible substitution of conventional metal oxide cathode materials in lithium-ion cells. EWC300 was selected as the most suitable carbon fiber material based on data from preliminary tests. Experiments were performed with LiClO4 in EC/DMC and LiPF6 in EC/DMC electrolytes. Slow scan cyclic voltammetry (0.1 mV/s) and...
Show moreThe intercalation of anions into carbon fiber from organic electrolytes containing lithium salts was studied. The reversible intercalation of anions into carbon could lead to the possible substitution of conventional metal oxide cathode materials in lithium-ion cells. EWC300 was selected as the most suitable carbon fiber material based on data from preliminary tests. Experiments were performed with LiClO4 in EC/DMC and LiPF6 in EC/DMC electrolytes. Slow scan cyclic voltammetry (0.1 mV/s) and galvanostatic charge/discharge experiments at various C rates were used. Intercalation of PF6- occurred by staging and was highly dependent on the current density. High current density (20 mA/g) was necessary to reach potentials over 5 V vs Li to achieve intercalation capacities over 80 mAh/g. Powder x-ray diffraction revealed that carbon fibers became less crystalline after anions were intercalated into their structure. Scanning electron microscopy showed longitudinal cracking on the carbon fibers after 120 cycles indicating dimensional instability.
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Date Issued
1999
PURL
http://purl.flvc.org/fcla/dt/15624
Subject Headings
Anions, Carbon fibers, Lithium cells, Electrochemical analysis
Format
Document (PDF)
Feasibility studies on carbon fiber composite cables in reinforced/prestressed concrete structures
Title
Feasibility studies on carbon fiber composite cables in reinforced/prestressed concrete structures.
Creator
Kanneganti, Srikanth., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
The feasibility studies on the use of non-metallic continuous fiber reinforcement in reinforced and prestressed concrete structures are presented herein. Experimental results from studies on relaxation, bond and transfer length of Carbon Fiber Composite Cables (CFCC) are presented followed by results of flexural load tests on concrete beams reinforced and prestressed with CFCC. Durability of the CFCC is another prime concern, and hence part of the study also focuses on establishing the...
Show moreThe feasibility studies on the use of non-metallic continuous fiber reinforcement in reinforced and prestressed concrete structures are presented herein. Experimental results from studies on relaxation, bond and transfer length of Carbon Fiber Composite Cables (CFCC) are presented followed by results of flexural load tests on concrete beams reinforced and prestressed with CFCC. Durability of the CFCC is another prime concern, and hence part of the study also focuses on establishing the durability of the CFCC exposed to aggressive environments like alkali solution and sea water. The basic mechanics that govern the structural behavior of the beams, provide important insight into the potential that CFCC has to offer.
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Date Issued
1994
PURL
http://purl.flvc.org/fcla/dt/15080
Subject Headings
Fiber reinforced plastics, Reinforced concrete, Fiber, Composite materials, Prestressed concrete construction--Deterioration, Carbon fibers
Format
Document (PDF)
Feasibility of using carbon fiber reinforced plastic tendons in prestressed concrete Double-Tee bridge system
Title
Feasibility of using carbon fiber reinforced plastic tendons in prestressed concrete Double-Tee bridge system.
Creator
Zhuang, Ming., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
One of the major problems the construction industry faces today is corrosion of reinforcing and prestressing steel, which significantly affects the durability of concrete structures. Fiber reinforced plastics (FRPs) are highly regarded as prospective replacement for steel in prestressed concrete structures under corrosive environment. This investigation was conducted to establish the feasibility of using Carbon Fiber Composite (CFC) cables as reinforcing/prestressing elements in concrete...
Show moreOne of the major problems the construction industry faces today is corrosion of reinforcing and prestressing steel, which significantly affects the durability of concrete structures. Fiber reinforced plastics (FRPs) are highly regarded as prospective replacement for steel in prestressed concrete structures under corrosive environment. This investigation was conducted to establish the feasibility of using Carbon Fiber Composite (CFC) cables as reinforcing/prestressing elements in concrete bridge structures. Besides investigating durability of CFC cables and pretensioned concrete beams with CFC cables in adverse environments (alkali and seawater), flexure and shear tests were performed on single Double-Tee beams, together with service load behavior, fatigue strength and ultimate load capacity tests on a half scale model Double-Tee girder bridge system prestressed with CFC cables. Exposure to seawater and alkali environments has no adverse effect on the strength of the CFRP tendons as well as the pretensioned beams with CFRP. Based on the flexural strength tests on Double-Tee beams, the bond between CFRP tendons and concrete is satisfactory. The Double-Tee bridge system exhibited good fatigue resistance and adequate ductility under ultimate load conditions. The ultimate load capacity of the bridge is approximately three times the service load corresponding to two HS20-44 trucks and equals 2.4 times the first crack load. Finite element analyses were carried out to predict elastic deformations and collapse load of the Double-Tee bridge prestressed with CFC cables. Feasibility of using CFC cables in bridge structures is assessed based on the experimental and analytical parameters such as deflections, strains, crack distributions and crack widths.
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Date Issued
1996
PURL
http://purl.flvc.org/fcla/dt/12465
Subject Headings
Carbon fibers, Composite construction, Fiber reinforced plastics, Bridges, Iron and steel, Reinforced concrete construction, Prestressed concrete construction
Format
Document (PDF)
Electrochemical impedance spectroscopy to monitor degradation of carbon fiber reinforced polymer composites subjected to simulated ocean environment
Title
Electrochemical impedance spectroscopy to monitor degradation of carbon fiber reinforced polymer composites subjected to simulated ocean environment.
Creator
Ahmed, Mohammad Mesbahuddin., Florida Atlantic University, Lipka, Stephen M.
Abstract/Description
This research evaluated the applicability of electrochemical impedance spectroscopy (EIS) as a non-destructive technique to predict and characterize the degradation of carbon fiber reinforced polymer (CFRP) composites exposed to aqueous environments at ambient and 6.2 $\pm$ 0.3 MPa. Changes in EIS data were related to water uptake into the composite material as a function of exposure time. Electrochemically induced damage (both anodic and cathodic) were also evaluated using impedance...
Show moreThis research evaluated the applicability of electrochemical impedance spectroscopy (EIS) as a non-destructive technique to predict and characterize the degradation of carbon fiber reinforced polymer (CFRP) composites exposed to aqueous environments at ambient and 6.2 $\pm$ 0.3 MPa. Changes in EIS data were related to water uptake into the composite material as a function of exposure time. Electrochemically induced damage (both anodic and cathodic) were also evaluated using impedance measurements. Three point flexure tests with concurrent EIS measurements were employed to study the effect of stresses on water uptake and mechanical degradation. Visual observation of the extent of damage (i.e., fiber-matrix debonding) was made using scanning electron microscopy (SEM) and correlated with EIS observation.
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Date Issued
1993
PURL
http://purl.flvc.org/fcla/dt/14962
Subject Headings
Polymers--Deterioration, Composite materials--Environmental aspects, Carbon fibers, Polymeric composites, Spectrum analysis
Format
Document (PDF)
Theoretical analysis of reinforced and prestressed concrete bridge members strengthened with CFRP laminates
Title
Theoretical analysis of reinforced and prestressed concrete bridge members strengthened with CFRP laminates.
Creator
Qu, Rong., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
Nonlinear finite element analyses of the reinforced rectangular beams, prestressed solid slab and prestressed voided slab retrofitted with CFRP laminates are carried out using the software ANSYS(version 5.0) on the Sunwork station. The computer analyses are based on the proposed stress-strain relationship considering the effects of tensile stress on both elastic modulus and maximum compressive stress of concrete. Several assumptions are made in predicting the loss of tensile strength due to...
Show moreNonlinear finite element analyses of the reinforced rectangular beams, prestressed solid slab and prestressed voided slab retrofitted with CFRP laminates are carried out using the software ANSYS(version 5.0) on the Sunwork station. The computer analyses are based on the proposed stress-strain relationship considering the effects of tensile stress on both elastic modulus and maximum compressive stress of concrete. Several assumptions are made in predicting the loss of tensile strength due to crack, confinement due to the laminate bonding, tensile strength due to the prestress force, failure pattern due to the concentrated stress adjacent to the loading point and concrete crushing due to large compressive strain. A subroutine is developed using macro commands of ANSYS. In this research, Branson's equation or Ie procedure is assumed in the prediction of deflection of retrofitted concrete members. The modifications needed due to laminate bonding are the cracking moments of inertia (Icr) of the beams or slabs bonded with CFRP laminates, which are included in the analysis.
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Date Issued
1994
PURL
http://purl.flvc.org/fcla/dt/15083
Subject Headings
ANSYS (Computer system), Reinforced concrete--Plastic properties, Carbon composites, Fiber reinforced plastics, Bridges--Design and construction, Prestressed concrete construction
Format
Document (PDF)