Meer Safa completed his Ph.D. in Materials Science and Engineering at Florida International University (FIU) under the supervision of Dr. Bilal El-Zahab. He received his M.Sc degree in Materials Science and Engineering from Royal Institute of Technology (KTH), Sweden and B.Sc degree in Materials and Metallurgical Engineering from Bangladesh University of Engineering and Technology (BUET), Bangladesh. His area of research concentrated on the development of electrolyte systems for lithium batteries focusing on gel polymer electrolyte. His area of expertise are synthesis of ionic liquids, application of various electrochemical and characterization techniques to understand electrode-electrolyte interaction in lithium batteries. Phone: 3057108326 Address: 10555 West Flagler St.Miami, FL 33174
The demand for electric vehicles is increasing rapidly as the world is preparing for a fossil
fue... more The demand for electric vehicles is increasing rapidly as the world is preparing for a fossil fuel-free future in the automotive field. Lithium battery technologies are the most effective options to replace fossil fuels due to their higher energy densities. However, safety remains a major concern in using lithium as the anode, and the development of non-volatile, nonflammable, high conductivity electrolytes is of great importance. In this dissertation, a gel polymer electrolyte (GPE) consisting of ionic liquid, lithium salt, and a polymer has been developed for their application in lithium batteries. A comparative study between GPE and ionic liquid electrolyte (ILE) containing batteries shows a superior cyclic performance up to 5C rate and a better rate capability for 40 cycles for cells with GPE at room temperature. The improvement is attributed to GPE’s improved stability voltage window against lithium as well as higher lithium transference number. The performance of the GPE in lithium-sulfur battery system using sulfur-CNT cathodes shows superior rate capability for the GPE versus ILE for up to 1C rates. Also, GPE containing batteries had higher capacity retention versus ILE when cycled for 500 cycles vii at C/2 rate. Electrochemical impedance spectroscopy (EIS) studies reveal interfacial impedances for ILE containing batteries grew faster than in GPE batteries. The accumulation of insoluble Li2S2/Li2S on the electrodes decreases the active material thus contributes to capacity fading. SEM imaging of cycled cathodes reveals cracks on the surface of cathode recovered from ILE batteries. On the other hand, the improved electrochemical performance of GPE batteries indicates better and more stable passivation layer formation on the surface of the electrodes. Composite GPE (cGPE) containing micro glass fillers were studied to determine their electrochemical performance in Li batteries. GPE with 1 wt% micro fillers show superior rate capability for up to 7C and also cyclic stability for 300 cycles at C/2 rate. In situ, EIS also reveals a rapid increase in charge transfer resistance in GPE batteries, responsible for lowering the capacity during cycling. Improved ion transport properties due to ion-complex formations in the presence of the micro fillers is evidenced by improved lithium transference number, ionic conduction, and ion-pair dissociation detected using Raman spectroscopy
Composite gel polymer electrolyte (cGPE) containing a poly (ionic liquid) (PIL) polymer, imidazol... more Composite gel polymer electrolyte (cGPE) containing a poly (ionic liquid) (PIL) polymer, imidazolium cation-based ionic liquid as a solvent, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as salt, and glass fillers with various concentrations have been developed and tested in lithium batteries. cGPEs with 1 wt% glass filler shows the highest ionic conductivity and lithium-ion transference number with 25 % and 18.18 % improvement compared to gel polymer electrolyte (GPE), respectively. Raman results show that the improvement is due to the improved ion-pair dissociation of LiTFSI, which causes improvement of Li + mobility. Cyclic charge-discharge studies using binder-free LiFePO 4 /C cathode and lithium anode for 100 cycles at various Crates and at a fixed rate of C/2 for 300 cycles show superior performances compared to other cGPEs and GPE. Electrochemical impedance spectroscopy and scanning electron microscopy confirm uniform deposition of reaction products on the cathode surface, which improves the charge-transfer reactions and hence improves cyclic performances for cGPE-1 cells with increasing cycles.
Lithium-ion batteries are currently used for various applications since they are lightweight, sta... more Lithium-ion batteries are currently used for various applications since they are lightweight, stable, and flexible. With the increased demand for portable electronics and electric vehicles, it has become necessary to develop newer, smaller, and lighter batteries with increased cycle life, high energy density, and overall better battery performance. Since the sources of lithium are limited and also because of the high cost of the metal, it is necessary to find alternatives. Sodium batteries have shown great potential, and hence several researchers are working on improving the battery performance of the various sodium batteries. This paper is a brief review of the current research in sodium-sulfur and sodium-air batteries.
The electrochemical oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) and on CN... more The electrochemical oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) and on CNT (carbon nanotube) cathode with a palladium catalyst, palladium-coated CNT (PC-CNT), and palladium-filled CNT (PF-CNT) are assessed in an ether-based electrolyte solution in order to fabricate a lithium-oxygen battery with high specific energy. The electrochemical properties of the CNT cathodes were studied using electrochemical impedance spectroscopy (EIS). Palladium-filled cathodes displayed better performance as compared to the palladium-coated ones due to the shielding of the catalysts. The mechanism of the improvement was associated to the reduction of the rate of resistances growth in the batteries, especially the ionic resistances in the electrolyte and electrodes. The scanning electron microscopy (SEM) and spectroscopy were used to analyze the products of the reaction that were adsorbed on the electrode surface of the battery, which was fabricated using palladium-coated and palladium-filled CNTs as cathodes and an ether-based electrolyte.
Lithium-sulfur batteries using a lithium anode, sulfur-CNT cathode, and gel polymer electrolyte c... more Lithium-sulfur batteries using a lithium anode, sulfur-CNT cathode, and gel polymer electrolyte composed of a poly(ionic liquid), an ionic liquid, and lithium salt are reported. Cyclic charge-discharge studies at various discharge and charge rates for 100 cycles and at a fixed rate for 500 cycles show superior performance for the gel polymer electrolyte (GPE) compared to the ionic liquid electrolyte (ILE) containing batteries. Rapid capacity fading for the first few cycles is observed and its causes are studied using an electrochemical impedance spectroscopy (EIS) approach. EIS reveals a depth-of-discharge dependent impedance growth during the first discharge cycle, that is followed by an interfacial resistance growth between the electrodes and the electrolytes in subsequent cycles.
The demand for electric vehicles is increasing rapidly as the world is preparing for a fossil
fue... more The demand for electric vehicles is increasing rapidly as the world is preparing for a fossil fuel-free future in the automotive field. Lithium battery technologies are the most effective options to replace fossil fuels due to their higher energy densities. However, safety remains a major concern in using lithium as the anode, and the development of non-volatile, nonflammable, high conductivity electrolytes is of great importance. In this dissertation, a gel polymer electrolyte (GPE) consisting of ionic liquid, lithium salt, and a polymer has been developed for their application in lithium batteries. A comparative study between GPE and ionic liquid electrolyte (ILE) containing batteries shows a superior cyclic performance up to 5C rate and a better rate capability for 40 cycles for cells with GPE at room temperature. The improvement is attributed to GPE’s improved stability voltage window against lithium as well as higher lithium transference number. The performance of the GPE in lithium-sulfur battery system using sulfur-CNT cathodes shows superior rate capability for the GPE versus ILE for up to 1C rates. Also, GPE containing batteries had higher capacity retention versus ILE when cycled for 500 cycles vii at C/2 rate. Electrochemical impedance spectroscopy (EIS) studies reveal interfacial impedances for ILE containing batteries grew faster than in GPE batteries. The accumulation of insoluble Li2S2/Li2S on the electrodes decreases the active material thus contributes to capacity fading. SEM imaging of cycled cathodes reveals cracks on the surface of cathode recovered from ILE batteries. On the other hand, the improved electrochemical performance of GPE batteries indicates better and more stable passivation layer formation on the surface of the electrodes. Composite GPE (cGPE) containing micro glass fillers were studied to determine their electrochemical performance in Li batteries. GPE with 1 wt% micro fillers show superior rate capability for up to 7C and also cyclic stability for 300 cycles at C/2 rate. In situ, EIS also reveals a rapid increase in charge transfer resistance in GPE batteries, responsible for lowering the capacity during cycling. Improved ion transport properties due to ion-complex formations in the presence of the micro fillers is evidenced by improved lithium transference number, ionic conduction, and ion-pair dissociation detected using Raman spectroscopy
Composite gel polymer electrolyte (cGPE) containing a poly (ionic liquid) (PIL) polymer, imidazol... more Composite gel polymer electrolyte (cGPE) containing a poly (ionic liquid) (PIL) polymer, imidazolium cation-based ionic liquid as a solvent, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as salt, and glass fillers with various concentrations have been developed and tested in lithium batteries. cGPEs with 1 wt% glass filler shows the highest ionic conductivity and lithium-ion transference number with 25 % and 18.18 % improvement compared to gel polymer electrolyte (GPE), respectively. Raman results show that the improvement is due to the improved ion-pair dissociation of LiTFSI, which causes improvement of Li + mobility. Cyclic charge-discharge studies using binder-free LiFePO 4 /C cathode and lithium anode for 100 cycles at various Crates and at a fixed rate of C/2 for 300 cycles show superior performances compared to other cGPEs and GPE. Electrochemical impedance spectroscopy and scanning electron microscopy confirm uniform deposition of reaction products on the cathode surface, which improves the charge-transfer reactions and hence improves cyclic performances for cGPE-1 cells with increasing cycles.
Lithium-ion batteries are currently used for various applications since they are lightweight, sta... more Lithium-ion batteries are currently used for various applications since they are lightweight, stable, and flexible. With the increased demand for portable electronics and electric vehicles, it has become necessary to develop newer, smaller, and lighter batteries with increased cycle life, high energy density, and overall better battery performance. Since the sources of lithium are limited and also because of the high cost of the metal, it is necessary to find alternatives. Sodium batteries have shown great potential, and hence several researchers are working on improving the battery performance of the various sodium batteries. This paper is a brief review of the current research in sodium-sulfur and sodium-air batteries.
The electrochemical oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) and on CN... more The electrochemical oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) and on CNT (carbon nanotube) cathode with a palladium catalyst, palladium-coated CNT (PC-CNT), and palladium-filled CNT (PF-CNT) are assessed in an ether-based electrolyte solution in order to fabricate a lithium-oxygen battery with high specific energy. The electrochemical properties of the CNT cathodes were studied using electrochemical impedance spectroscopy (EIS). Palladium-filled cathodes displayed better performance as compared to the palladium-coated ones due to the shielding of the catalysts. The mechanism of the improvement was associated to the reduction of the rate of resistances growth in the batteries, especially the ionic resistances in the electrolyte and electrodes. The scanning electron microscopy (SEM) and spectroscopy were used to analyze the products of the reaction that were adsorbed on the electrode surface of the battery, which was fabricated using palladium-coated and palladium-filled CNTs as cathodes and an ether-based electrolyte.
Lithium-sulfur batteries using a lithium anode, sulfur-CNT cathode, and gel polymer electrolyte c... more Lithium-sulfur batteries using a lithium anode, sulfur-CNT cathode, and gel polymer electrolyte composed of a poly(ionic liquid), an ionic liquid, and lithium salt are reported. Cyclic charge-discharge studies at various discharge and charge rates for 100 cycles and at a fixed rate for 500 cycles show superior performance for the gel polymer electrolyte (GPE) compared to the ionic liquid electrolyte (ILE) containing batteries. Rapid capacity fading for the first few cycles is observed and its causes are studied using an electrochemical impedance spectroscopy (EIS) approach. EIS reveals a depth-of-discharge dependent impedance growth during the first discharge cycle, that is followed by an interfacial resistance growth between the electrodes and the electrolytes in subsequent cycles.
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fuel-free future in the automotive field. Lithium battery technologies are the most effective
options to replace fossil fuels due to their higher energy densities. However, safety remains
a major concern in using lithium as the anode, and the development of non-volatile, nonflammable, high conductivity electrolytes is of great importance.
In this dissertation, a gel polymer electrolyte (GPE) consisting of ionic liquid, lithium salt,
and a polymer has been developed for their application in lithium batteries. A comparative
study between GPE and ionic liquid electrolyte (ILE) containing batteries shows a superior
cyclic performance up to 5C rate and a better rate capability for 40 cycles for cells with
GPE at room temperature. The improvement is attributed to GPE’s improved stability
voltage window against lithium as well as higher lithium transference number.
The performance of the GPE in lithium-sulfur battery system using sulfur-CNT cathodes
shows superior rate capability for the GPE versus ILE for up to 1C rates. Also, GPE
containing batteries had higher capacity retention versus ILE when cycled for 500 cycles
vii
at C/2 rate. Electrochemical impedance spectroscopy (EIS) studies reveal interfacial
impedances for ILE containing batteries grew faster than in GPE batteries. The
accumulation of insoluble Li2S2/Li2S on the electrodes decreases the active material thus
contributes to capacity fading. SEM imaging of cycled cathodes reveals cracks on the
surface of cathode recovered from ILE batteries. On the other hand, the improved
electrochemical performance of GPE batteries indicates better and more stable passivation
layer formation on the surface of the electrodes.
Composite GPE (cGPE) containing micro glass fillers were studied to determine their
electrochemical performance in Li batteries. GPE with 1 wt% micro fillers show superior
rate capability for up to 7C and also cyclic stability for 300 cycles at C/2 rate. In situ, EIS
also reveals a rapid increase in charge transfer resistance in GPE batteries, responsible for
lowering the capacity during cycling. Improved ion transport properties due to ion-complex
formations in the presence of the micro fillers is evidenced by improved lithium
transference number, ionic conduction, and ion-pair dissociation detected using Raman
spectroscopy
fuel-free future in the automotive field. Lithium battery technologies are the most effective
options to replace fossil fuels due to their higher energy densities. However, safety remains
a major concern in using lithium as the anode, and the development of non-volatile, nonflammable, high conductivity electrolytes is of great importance.
In this dissertation, a gel polymer electrolyte (GPE) consisting of ionic liquid, lithium salt,
and a polymer has been developed for their application in lithium batteries. A comparative
study between GPE and ionic liquid electrolyte (ILE) containing batteries shows a superior
cyclic performance up to 5C rate and a better rate capability for 40 cycles for cells with
GPE at room temperature. The improvement is attributed to GPE’s improved stability
voltage window against lithium as well as higher lithium transference number.
The performance of the GPE in lithium-sulfur battery system using sulfur-CNT cathodes
shows superior rate capability for the GPE versus ILE for up to 1C rates. Also, GPE
containing batteries had higher capacity retention versus ILE when cycled for 500 cycles
vii
at C/2 rate. Electrochemical impedance spectroscopy (EIS) studies reveal interfacial
impedances for ILE containing batteries grew faster than in GPE batteries. The
accumulation of insoluble Li2S2/Li2S on the electrodes decreases the active material thus
contributes to capacity fading. SEM imaging of cycled cathodes reveals cracks on the
surface of cathode recovered from ILE batteries. On the other hand, the improved
electrochemical performance of GPE batteries indicates better and more stable passivation
layer formation on the surface of the electrodes.
Composite GPE (cGPE) containing micro glass fillers were studied to determine their
electrochemical performance in Li batteries. GPE with 1 wt% micro fillers show superior
rate capability for up to 7C and also cyclic stability for 300 cycles at C/2 rate. In situ, EIS
also reveals a rapid increase in charge transfer resistance in GPE batteries, responsible for
lowering the capacity during cycling. Improved ion transport properties due to ion-complex
formations in the presence of the micro fillers is evidenced by improved lithium
transference number, ionic conduction, and ion-pair dissociation detected using Raman
spectroscopy