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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)
Effect of fiber sterilization atmosphere on insertion of lithium into PAN-based carbon filter electrodes
Title
Effect of fiber sterilization atmosphere on insertion of lithium into PAN-based carbon filter electrodes.
Creator
Braun, James Christian., Florida Atlantic University, Lipka, Stephen M.
Abstract/Description
A novel electrode structure for Li-ion batteries was created by thermally treating nonwoven polyacrylonitrile (PAN) fabric in an inert atmosphere. Rapid carbonization of PAN fiber, stabilized in an inert atmosphere, produced a fused carbon fiber structure having a reversible specific capacity for lithium above 300 mAh/g; with charge reversibility between 95 and 100%. Chemical, structural and electrochemical analyses, including electrochemical impedance spectroscopy were performed on carbon...
Show moreA novel electrode structure for Li-ion batteries was created by thermally treating nonwoven polyacrylonitrile (PAN) fabric in an inert atmosphere. Rapid carbonization of PAN fiber, stabilized in an inert atmosphere, produced a fused carbon fiber structure having a reversible specific capacity for lithium above 300 mAh/g; with charge reversibility between 95 and 100%. Chemical, structural and electrochemical analyses, including electrochemical impedance spectroscopy were performed on carbon fiber electrodes. Scanning electron microscopy revealed grooves and striations on the surfaces of carbon fibers prepared from PAN precursors stabilized in oxygen; but could not resolve any surface features on the fused carbon fibers, prepared from PAN precursors stabilized in an inert atmosphere. The fused, porous carbon fibers are believed to contain a large fraction of carbon chains with relatively few carbon planes.
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Date Issued
1997
PURL
http://purl.flvc.org/fcla/dt/15484
Subject Headings
Lithium cells, Electrodes, Carbon, Nonwoven fabrics
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)