The document describes using a soft PEO10LiTFSI polymer swellable gel as a nanoscale reservoir to improve the performance of lithium-sulfur batteries under lean electrolyte conditions. The gel immobilizes the electrolyte and confines polysulfides within the ion conducting gel phase. A lithium-sulfur cell using a low electrolyte to sulfur ratio of 4 gE/gS (3.3 mLE/gS) and the PEO10LiTFSI gel delivered a capacity of 1200 mAh/g and good cycle life. Accumulation of polysulfide reduction products like Li2S on the cathode is identified as a potential mechanism for capacity fading under lean electrolyte conditions, which is different
A molecular-dynamics-investigation-of-the-stability-of-a-charged-electroactiv...Darren Martin Leith
1) A molecular dynamics simulation investigates the stability of a charged electroactive polymer monolayer consisting of an amphiphilic polythiophene on a sodium chloride solution.
2) When the monolayer is chemically reduced, negative charges are conferred on the thiophene rings. This leads to a loss of planarity and buckling of the monolayer, eventually causing it to rupture. It also attracts excess sodium ions to the interface.
3) At low levels of reduction, interface sodium ions are more mobile than sodium ions in the NaCl solution, responding to electric fields by jumping between sites with an energy barrier of 0.33 eV. The instability of the charged polymer membrane is discussed using Gou
Myoglobin is a protein that binds oxygen and contains a heme group and protoporphyrin IX. The heme group coordinates with the protein through bonds and forms pockets on the protein surface where other molecules can bind. Visualizations of myoglobin show its secondary structure as a ribbon including side chains of hydrophobic residues, and a space-filling model depicting all amino acid side chains and how steric effects impact ligand binding to the heme group.
This document provides an overview of protein structure and function. It discusses tertiary structure, which involves interactions between amino acid side chains that cause folds and loops in the polypeptide chain. Supersecondary structures combine different secondary structures. Protein domains consist of structural motifs and can function independently. Quaternary structure involves interactions between polypeptide subunits. The amino acid sequence determines the three-dimensional structure of a protein. Protein folding involves interactions that bury hydrophobic residues in the core and expose hydrophilic residues. Misfolded proteins can accumulate and cause disease.
Photogeneration of Gelatinous Networks from Pre-existing PolymersGregory Carroll
In this manuscript we report the crosslinking
of pre-existing macromolecules in solution through the use
of photoactive benzophenone chromophores. We show that
a bifunctional crosslinker composed of two benzophenone
chromophores as well as a single benzophenone chromophore
crosslink poly (butadiene) and poly (ethylene oxide)
in solution to form insoluble gels when irradiated with UV
light. The molecular weight between crosslinks of the photogenerated
gels was compared for the two crosslinkers, for an
equivalent amount of benzophenone chromophores in each
solution, by measuring the swelling ratio of the gels formed.
Gels formed from the bifunctional benzophenone crosslinker
were shown to contain more than twice as many
crosslinks compared to gels formed from the crosslinker
composed of a single benzophenone chromophore. EPR
measurements of a nitroxide derivative absorbed into the
gels further supported a higher crosslink density for the
gels formed from the bifunctional benzophenone crosslinker.
Layer-by-layer (LbL) films have been produced with poly(o-ethoxyaniline) (POEA), chitosan and chitosan-poly(methacrylic acid) (CS-PMAA) nanoparticles. Because the adsorption of LbL films depends on ionic interactions and H-bonding, optimized conditions had to be established for the growth of multilayer films. Unusually thick
films were obtained for POEA and CS-PMAA, thus demonstrating the importance of using chitosan in the form of nanoparticles. These nanostructured films were deposited on chromium electrodes to form a sensor array (electronic tongue) based on impedance spectroscopy. This system was used to detect copper ions in aqueous solutions.
The document summarizes research investigating the interface phenomena of poly(o-ethoxyaniline) (POEA) films using atomic force spectroscopy. The study found that POEA films consist of conducting islands surrounded by a less conductive matrix. The conducting islands were characterized by the presence of double-layer forces and visualized using transmission electron microscopy. The conducting islands were only 15 nm in diameter and could only be identified using adhesion mapping, not contact mode atomic force microscopy which showed larger aggregates. The degree of doping and pH affected the morphology and interactions observed, with fully dedoped POEA at pH 5 and partially conducting polyaniline.
Rotaxanes are supramolecular assemblies consisting of a macrocyclic molecule threaded onto a linear molecule capped with bulky stoppers. They can be synthesized through template-directed methods like clipping, threading, and snapping. Switchable rotaxanes have applications in logic gates and memory due to their ability to shuttle between binding stations. Rotaxanes can also be used to enhance or reduce reactivity, act as molecular muscles, and self-assemble into structures that can slowly release dye.
A molecular-dynamics-investigation-of-the-stability-of-a-charged-electroactiv...Darren Martin Leith
1) A molecular dynamics simulation investigates the stability of a charged electroactive polymer monolayer consisting of an amphiphilic polythiophene on a sodium chloride solution.
2) When the monolayer is chemically reduced, negative charges are conferred on the thiophene rings. This leads to a loss of planarity and buckling of the monolayer, eventually causing it to rupture. It also attracts excess sodium ions to the interface.
3) At low levels of reduction, interface sodium ions are more mobile than sodium ions in the NaCl solution, responding to electric fields by jumping between sites with an energy barrier of 0.33 eV. The instability of the charged polymer membrane is discussed using Gou
Myoglobin is a protein that binds oxygen and contains a heme group and protoporphyrin IX. The heme group coordinates with the protein through bonds and forms pockets on the protein surface where other molecules can bind. Visualizations of myoglobin show its secondary structure as a ribbon including side chains of hydrophobic residues, and a space-filling model depicting all amino acid side chains and how steric effects impact ligand binding to the heme group.
This document provides an overview of protein structure and function. It discusses tertiary structure, which involves interactions between amino acid side chains that cause folds and loops in the polypeptide chain. Supersecondary structures combine different secondary structures. Protein domains consist of structural motifs and can function independently. Quaternary structure involves interactions between polypeptide subunits. The amino acid sequence determines the three-dimensional structure of a protein. Protein folding involves interactions that bury hydrophobic residues in the core and expose hydrophilic residues. Misfolded proteins can accumulate and cause disease.
Photogeneration of Gelatinous Networks from Pre-existing PolymersGregory Carroll
In this manuscript we report the crosslinking
of pre-existing macromolecules in solution through the use
of photoactive benzophenone chromophores. We show that
a bifunctional crosslinker composed of two benzophenone
chromophores as well as a single benzophenone chromophore
crosslink poly (butadiene) and poly (ethylene oxide)
in solution to form insoluble gels when irradiated with UV
light. The molecular weight between crosslinks of the photogenerated
gels was compared for the two crosslinkers, for an
equivalent amount of benzophenone chromophores in each
solution, by measuring the swelling ratio of the gels formed.
Gels formed from the bifunctional benzophenone crosslinker
were shown to contain more than twice as many
crosslinks compared to gels formed from the crosslinker
composed of a single benzophenone chromophore. EPR
measurements of a nitroxide derivative absorbed into the
gels further supported a higher crosslink density for the
gels formed from the bifunctional benzophenone crosslinker.
Layer-by-layer (LbL) films have been produced with poly(o-ethoxyaniline) (POEA), chitosan and chitosan-poly(methacrylic acid) (CS-PMAA) nanoparticles. Because the adsorption of LbL films depends on ionic interactions and H-bonding, optimized conditions had to be established for the growth of multilayer films. Unusually thick
films were obtained for POEA and CS-PMAA, thus demonstrating the importance of using chitosan in the form of nanoparticles. These nanostructured films were deposited on chromium electrodes to form a sensor array (electronic tongue) based on impedance spectroscopy. This system was used to detect copper ions in aqueous solutions.
The document summarizes research investigating the interface phenomena of poly(o-ethoxyaniline) (POEA) films using atomic force spectroscopy. The study found that POEA films consist of conducting islands surrounded by a less conductive matrix. The conducting islands were characterized by the presence of double-layer forces and visualized using transmission electron microscopy. The conducting islands were only 15 nm in diameter and could only be identified using adhesion mapping, not contact mode atomic force microscopy which showed larger aggregates. The degree of doping and pH affected the morphology and interactions observed, with fully dedoped POEA at pH 5 and partially conducting polyaniline.
Rotaxanes are supramolecular assemblies consisting of a macrocyclic molecule threaded onto a linear molecule capped with bulky stoppers. They can be synthesized through template-directed methods like clipping, threading, and snapping. Switchable rotaxanes have applications in logic gates and memory due to their ability to shuttle between binding stations. Rotaxanes can also be used to enhance or reduce reactivity, act as molecular muscles, and self-assemble into structures that can slowly release dye.
The document summarizes research into developing new solid polymer electrolytes (SPEs) for lithium-ion batteries. SPEs offer safety advantages over liquid electrolytes but have lower conductivity at room temperature. The researchers synthesized a new lithium salt called 4mer-O-Li and combined it with polyoctahedral silsesquioxane-ethylene glycol (POSS-PEG8) to create electrolytes. Testing found the conductivity of the 4mer-O-Li/POSS-PEG8 electrolyte was 1.5 x 10-5 S/cm at 60°C and 4.04 x 10-6 S/cm at 25°C. However, the conductivity at room temperature is still too low for
The document discusses using molecular dynamics simulations to investigate ion transport properties in solid polymer electrolytes (SPEs) and liquid electrolytes for battery applications. The simulations examined the coordination and diffusivity of lithium, sodium, magnesium, potassium, chloride, and fluoride ions in polyethylene oxide (PEO) polymer electrolytes and dimethyl ether liquid electrolytes. The results showed that ion diffusion was generally higher in the liquid electrolyte, while larger ions like sodium and potassium diffused more quickly in the polymer electrolyte than smaller lithium ions. The study provides a way to screen electrolyte materials for batteries using molecular dynamics simulations.
Silicon is of great interest for use as the anode material in lithium-ion batteries due to its high
capacity. However, certain properties of silicon, such as a large volume expansion during the
lithiation process and the low diffusion rate of lithium in silicon, result in fast capacity
degradation in limited charge/discharge cycles, especially at high current rate. Therefore, the
use of silicon in real battery applications is limited. The idea of using porous silicon, to a large
extent, addresses the above-mentioned issues simultaneously. In this review, we discuss the
merits of using porous silicon for anodes through both theoretical and experimental study.
Recent progress in the preparation of porous silicon through the template-assisted approach
and the non-template approach have been highlighted. The battery performance in terms of
capacity and cyclability of each structure is evaluated.
Dynamics of Poly(ethylene oxide) in the bulk and in close proximity to silica...Eleni 'Hellen' Papananou
The behavior of polymers when they are restricted in space can be very different from that in the bulk especially when the molecules are confined to dimensions comparable to their sizes. The dynamics of polymer chains under confinement and its difference from the respective of the bulk has attracted the scientific interest because it greatly affects many of the material macroscopic properties. Besides planar polymer films, other experimental geometries have been utilized to study the effect of confinement on the various polymer relaxation processes such as: polymer / nanoparticle, polymer / nanorods and polymer / layered silicate nanocomposites to name a few.
In the past, we have systematically pursued the understanding of the parameters that influence the structure and dynamics under confinement in intercalated PEO / layered silicate nanocomposites. The confined polymer chains remain purely amorphous; crystallinity is observed only for hybrids with high polymer content and shows an abrupt drop to zero at a certain composition. The study of dynamics in confinement in comparison to the respective in the bulk utilizing dielectric relaxation spectroscopy showed an acceleration of the PEO segmental dynamics that display an Arrhenius temperature dependence with very low activation energy, whereas the local β-process remains unaffected.
Using nanoparticles to restrict the polymer can provide the advantage of altering the polymer confinement by changing the nanoparticle size and loading. Thus, in this work, we utilize PEO / SiO2 nanohybrids to control the thickness of the confined polymer film. DSC measurements showed decreasing crystallinity with the amount of additive whereas in hybrids with polymer content lower than 50wt%, a second crystallization and melting appears, indicating that the polymer crystallizes differently, when forced to crystallize near the silica surface.
The PEO dynamics is studied utilizing dielectric spectroscopy for hybrids with different composition to investigate the effect of the chain proximity to the surface on dynamics. The results are compared to the respective results on PEO / clay nanocomposites and the effect of the geometry of the filler on the behavior will be explored, as well.
This document provides an overview of surfactants in aqueous solutions. It discusses how amphiphilic surfactant molecules associate to form micelles above a critical concentration known as the critical micelle concentration (CMC). The CMC can be determined from a graph of surface tension versus surfactant concentration, where the surface tension levels off at the CMC as micellization begins. Factors that influence the CMC include the surfactant structure, temperature, presence of electrolytes or alcohols, and competitive interactions. Micellization allows solubilization of non-polar compounds. Models are presented for micellar solutions and mixtures.
- The document studies using water as an alternative solvent to the commonly used acetonitrile for applying organic layers from diazonium salts.
- When using water, the diazonium salt solution had to be replaced every couple days to maintain a consistent concentration, as the salt decomposed over time, turning the solution orange.
- Preliminary results found that layers could be applied using water as a solvent, but it may lack control over completeness of the layer compared to acetonitrile.
This document discusses the complexation and phase behavior of DNA with cationic surfactants and lipids in aqueous mixtures. When DNA forms a complex with a cationic surfactant, replacing the sodium counterions, an insoluble "complex salt" is formed (CSDNA). CSDNA can form liquid crystalline phases when mixed with water and additives like alcohols, lipids, or cyclodextrins. The phase diagrams of these ternary mixtures demonstrate a rich liquid crystallinity determined by factors like the components' hydrophobicity, CSDNA/surfactant ratio, and DNA packing constraints. Small-angle X-ray scattering was used to investigate the molecular arrangements in these phases.
Role of ionic liquid [BMIMPF6] in modifying theSHALU KATARIA
This document discusses a study on the effect of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) on the crystallization kinetics of the polymer electrolyte PEO-LiClO4. Three techniques were used: isothermal crystallization using DSC, non-isothermal crystallization using DSC, and monitoring spherulite growth over time using polarized optical microscopy. All techniques showed that BMIMPF6 suppresses the crystallization rate due to its plasticization effect. Isothermal data fit the Avrami equation well. Non-isothermal crystallization was best explained by Mo's method. Polarized optical microscopy
The document discusses cell membranes and their structure and function. It covers how the hydrophobic effect causes phospholipids to form bilayers in water. Bilayers allow for the separation of hydrophilic and hydrophobic regions which is important for cell structure and function. Membranes contain proteins and transport molecules that allow for selective movement of substances across the membrane through processes like diffusion, facilitated transport, and active transport. Membrane structure and composition impact many cellular functions.
This document proposes developing a bifunctional separator for lithium sulfur batteries (LSBs) using glass fiber coated with aluminum oxide on one side and carbon nanotubes on the other. Aluminum oxide coating is intended to suppress lithium dendrite growth at the anode, while carbon nanotubes are intended to capture polysulfides migrating from the cathode and improve cycling stability. The separator fabrication process involves coating glass fiber with carbon nanotube/PVDF slurry on one side and filtering aluminum oxide powder dispersed in NMP on the other side. Coin cells using the bifunctional separator, lithium anode, and sulfur cathode will be tested for performance. The goal is to incorporate benefits of various materials to
Lithium Iron Phosphate: Olivine Material for High Power Li-Ion Batteries - Cr...CrimsonPublishersRDMS
Lithium Iron Phosphate: Olivine Material for High Power Li-Ion Batteries by Christian M Julien* in Crimson Publishers: Peer Reviewed Material Science Journals
This document describes the fabrication of a thin film polymer light-emitting diode (OLED). It involves coating an indium tin oxide (ITO) substrate with the light-emitting polymer MEH-PPV dissolved in chloroform, followed by a layer of PEDOT:PSS as a hole transport layer. When a voltage is applied, electrons and holes recombine in the MEH-PPV layer, causing it to emit a bright orange glow. The project allows students to develop an understanding of OLED technologies and their applications. Challenges included finding solvents that could dissolve the polymer and using an appropriate molecular weight of MEH-PPV. Future work may involve testing other electrolumines
This document describes the fabrication of a thin film polymer light-emitting diode (OLED). It involves coating an indium tin oxide (ITO) substrate with the light-emitting polymer MEH-PPV dissolved in chloroform, followed by a layer of PEDOT:PSS as a hole transport layer. When a voltage is applied, electrons and holes recombine in the MEH-PPV layer, causing it to emit a bright orange glow. The project allows students to develop an understanding of OLED technologies and their applications. Challenges included finding solvents that could dissolve the polymer and using an appropriate molecular weight of MEH-PPV. Future work may involve testing other electrolumines
This document summarizes research into depositing electron transport layers (ETLs) for perovskite solar cells using atomic layer deposition (ALD) at low temperatures. TiO2 and SnO2 were deposited as ETLs using thermal ALD at 185°C with and without a plasma pre-clean treatment. XRD analysis found the films were amorphous. XPS showed doping TiO2 with Al2O3 did not change the Ti oxidation state. A plasma pre-clean improved conductivity for TiO2 and SnO2. Wetting of the perovskite layer differed between ETLs, with O2 plasma SnO2 displaying the best wettability despite not having the highest conductivity. Further
Hybrid Polymer Electrolytes for Use in Secondary Lithium Ion Batteries-V2-LBAnisha Joenathan
This document summarizes research into improving the properties of hybrid polymer electrolytes for use in lithium ion batteries. The researcher added ionic liquids and varied the molecular weight of polyethylene glycol (PEG) to enhance ionic conductivity and lithium ion transference numbers. Scanning transmission electron microscopy, differential scanning calorimetry, and conductivity measurements were used to characterize the hybrid polymer electrolytes. The addition of ionic liquids, specifically 1-butyl-3-methylimidazolium trifluoromethanosulfonate, increased conductivity by over two orders of magnitude. 400 Da PEG achieved the highest conductivity. Replacement of the lithium salt with sodium resulted in similar conductivity, showing potential for sodium ion batteries.
2016 Journal of Power Sources 301 (2016) 35-40Alexis B. B
This document summarizes research on producing transparent thin-film electrodes of Li4Ti5O12 and LiMn2O4 via sol-gel dip coating. Key findings include:
1) Transparent and uniform Li4Ti5O12 and LiMn2O4 thin films were prepared on fluorine-doped tin oxide (FTO) substrates via sol-gel dip coating and heat treatment.
2) X-ray diffraction analysis confirmed the films had the target spinel crystal structures of Li4Ti5O12 and LiMn2O4.
3) Electrochemical characterization including cyclic voltammetry and galvanostatic charging/discharging demonstrated the films were electrochem
The document discusses cell membranes and their structure. It notes that the hydrophobic effect causes phospholipids to form bilayers when placed in water, with their hydrophobic tails buried inside and hydrophilic heads facing out. Bilayers naturally form biological membranes and combine different lipid species. Membranes are fluid and allow proteins and lipids to move freely within. Membranes undergo endocytosis and exocytosis to transport materials in and out of cells. Damage to membranes is repaired through various enzymatic processes.
The document summarizes research into developing new solid polymer electrolytes (SPEs) for lithium-ion batteries. SPEs offer safety advantages over liquid electrolytes but have lower conductivity at room temperature. The researchers synthesized a new lithium salt called 4mer-O-Li and combined it with polyoctahedral silsesquioxane-ethylene glycol (POSS-PEG8) to create electrolytes. Testing found the conductivity of the 4mer-O-Li/POSS-PEG8 electrolyte was 1.5 x 10-5 S/cm at 60°C and 4.04 x 10-6 S/cm at 25°C. However, the conductivity at room temperature is still too low for
The document discusses using molecular dynamics simulations to investigate ion transport properties in solid polymer electrolytes (SPEs) and liquid electrolytes for battery applications. The simulations examined the coordination and diffusivity of lithium, sodium, magnesium, potassium, chloride, and fluoride ions in polyethylene oxide (PEO) polymer electrolytes and dimethyl ether liquid electrolytes. The results showed that ion diffusion was generally higher in the liquid electrolyte, while larger ions like sodium and potassium diffused more quickly in the polymer electrolyte than smaller lithium ions. The study provides a way to screen electrolyte materials for batteries using molecular dynamics simulations.
Silicon is of great interest for use as the anode material in lithium-ion batteries due to its high
capacity. However, certain properties of silicon, such as a large volume expansion during the
lithiation process and the low diffusion rate of lithium in silicon, result in fast capacity
degradation in limited charge/discharge cycles, especially at high current rate. Therefore, the
use of silicon in real battery applications is limited. The idea of using porous silicon, to a large
extent, addresses the above-mentioned issues simultaneously. In this review, we discuss the
merits of using porous silicon for anodes through both theoretical and experimental study.
Recent progress in the preparation of porous silicon through the template-assisted approach
and the non-template approach have been highlighted. The battery performance in terms of
capacity and cyclability of each structure is evaluated.
Dynamics of Poly(ethylene oxide) in the bulk and in close proximity to silica...Eleni 'Hellen' Papananou
The behavior of polymers when they are restricted in space can be very different from that in the bulk especially when the molecules are confined to dimensions comparable to their sizes. The dynamics of polymer chains under confinement and its difference from the respective of the bulk has attracted the scientific interest because it greatly affects many of the material macroscopic properties. Besides planar polymer films, other experimental geometries have been utilized to study the effect of confinement on the various polymer relaxation processes such as: polymer / nanoparticle, polymer / nanorods and polymer / layered silicate nanocomposites to name a few.
In the past, we have systematically pursued the understanding of the parameters that influence the structure and dynamics under confinement in intercalated PEO / layered silicate nanocomposites. The confined polymer chains remain purely amorphous; crystallinity is observed only for hybrids with high polymer content and shows an abrupt drop to zero at a certain composition. The study of dynamics in confinement in comparison to the respective in the bulk utilizing dielectric relaxation spectroscopy showed an acceleration of the PEO segmental dynamics that display an Arrhenius temperature dependence with very low activation energy, whereas the local β-process remains unaffected.
Using nanoparticles to restrict the polymer can provide the advantage of altering the polymer confinement by changing the nanoparticle size and loading. Thus, in this work, we utilize PEO / SiO2 nanohybrids to control the thickness of the confined polymer film. DSC measurements showed decreasing crystallinity with the amount of additive whereas in hybrids with polymer content lower than 50wt%, a second crystallization and melting appears, indicating that the polymer crystallizes differently, when forced to crystallize near the silica surface.
The PEO dynamics is studied utilizing dielectric spectroscopy for hybrids with different composition to investigate the effect of the chain proximity to the surface on dynamics. The results are compared to the respective results on PEO / clay nanocomposites and the effect of the geometry of the filler on the behavior will be explored, as well.
This document provides an overview of surfactants in aqueous solutions. It discusses how amphiphilic surfactant molecules associate to form micelles above a critical concentration known as the critical micelle concentration (CMC). The CMC can be determined from a graph of surface tension versus surfactant concentration, where the surface tension levels off at the CMC as micellization begins. Factors that influence the CMC include the surfactant structure, temperature, presence of electrolytes or alcohols, and competitive interactions. Micellization allows solubilization of non-polar compounds. Models are presented for micellar solutions and mixtures.
- The document studies using water as an alternative solvent to the commonly used acetonitrile for applying organic layers from diazonium salts.
- When using water, the diazonium salt solution had to be replaced every couple days to maintain a consistent concentration, as the salt decomposed over time, turning the solution orange.
- Preliminary results found that layers could be applied using water as a solvent, but it may lack control over completeness of the layer compared to acetonitrile.
This document discusses the complexation and phase behavior of DNA with cationic surfactants and lipids in aqueous mixtures. When DNA forms a complex with a cationic surfactant, replacing the sodium counterions, an insoluble "complex salt" is formed (CSDNA). CSDNA can form liquid crystalline phases when mixed with water and additives like alcohols, lipids, or cyclodextrins. The phase diagrams of these ternary mixtures demonstrate a rich liquid crystallinity determined by factors like the components' hydrophobicity, CSDNA/surfactant ratio, and DNA packing constraints. Small-angle X-ray scattering was used to investigate the molecular arrangements in these phases.
Role of ionic liquid [BMIMPF6] in modifying theSHALU KATARIA
This document discusses a study on the effect of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) on the crystallization kinetics of the polymer electrolyte PEO-LiClO4. Three techniques were used: isothermal crystallization using DSC, non-isothermal crystallization using DSC, and monitoring spherulite growth over time using polarized optical microscopy. All techniques showed that BMIMPF6 suppresses the crystallization rate due to its plasticization effect. Isothermal data fit the Avrami equation well. Non-isothermal crystallization was best explained by Mo's method. Polarized optical microscopy
The document discusses cell membranes and their structure and function. It covers how the hydrophobic effect causes phospholipids to form bilayers in water. Bilayers allow for the separation of hydrophilic and hydrophobic regions which is important for cell structure and function. Membranes contain proteins and transport molecules that allow for selective movement of substances across the membrane through processes like diffusion, facilitated transport, and active transport. Membrane structure and composition impact many cellular functions.
This document proposes developing a bifunctional separator for lithium sulfur batteries (LSBs) using glass fiber coated with aluminum oxide on one side and carbon nanotubes on the other. Aluminum oxide coating is intended to suppress lithium dendrite growth at the anode, while carbon nanotubes are intended to capture polysulfides migrating from the cathode and improve cycling stability. The separator fabrication process involves coating glass fiber with carbon nanotube/PVDF slurry on one side and filtering aluminum oxide powder dispersed in NMP on the other side. Coin cells using the bifunctional separator, lithium anode, and sulfur cathode will be tested for performance. The goal is to incorporate benefits of various materials to
Lithium Iron Phosphate: Olivine Material for High Power Li-Ion Batteries - Cr...CrimsonPublishersRDMS
Lithium Iron Phosphate: Olivine Material for High Power Li-Ion Batteries by Christian M Julien* in Crimson Publishers: Peer Reviewed Material Science Journals
This document describes the fabrication of a thin film polymer light-emitting diode (OLED). It involves coating an indium tin oxide (ITO) substrate with the light-emitting polymer MEH-PPV dissolved in chloroform, followed by a layer of PEDOT:PSS as a hole transport layer. When a voltage is applied, electrons and holes recombine in the MEH-PPV layer, causing it to emit a bright orange glow. The project allows students to develop an understanding of OLED technologies and their applications. Challenges included finding solvents that could dissolve the polymer and using an appropriate molecular weight of MEH-PPV. Future work may involve testing other electrolumines
This document describes the fabrication of a thin film polymer light-emitting diode (OLED). It involves coating an indium tin oxide (ITO) substrate with the light-emitting polymer MEH-PPV dissolved in chloroform, followed by a layer of PEDOT:PSS as a hole transport layer. When a voltage is applied, electrons and holes recombine in the MEH-PPV layer, causing it to emit a bright orange glow. The project allows students to develop an understanding of OLED technologies and their applications. Challenges included finding solvents that could dissolve the polymer and using an appropriate molecular weight of MEH-PPV. Future work may involve testing other electrolumines
This document summarizes research into depositing electron transport layers (ETLs) for perovskite solar cells using atomic layer deposition (ALD) at low temperatures. TiO2 and SnO2 were deposited as ETLs using thermal ALD at 185°C with and without a plasma pre-clean treatment. XRD analysis found the films were amorphous. XPS showed doping TiO2 with Al2O3 did not change the Ti oxidation state. A plasma pre-clean improved conductivity for TiO2 and SnO2. Wetting of the perovskite layer differed between ETLs, with O2 plasma SnO2 displaying the best wettability despite not having the highest conductivity. Further
Hybrid Polymer Electrolytes for Use in Secondary Lithium Ion Batteries-V2-LBAnisha Joenathan
This document summarizes research into improving the properties of hybrid polymer electrolytes for use in lithium ion batteries. The researcher added ionic liquids and varied the molecular weight of polyethylene glycol (PEG) to enhance ionic conductivity and lithium ion transference numbers. Scanning transmission electron microscopy, differential scanning calorimetry, and conductivity measurements were used to characterize the hybrid polymer electrolytes. The addition of ionic liquids, specifically 1-butyl-3-methylimidazolium trifluoromethanosulfonate, increased conductivity by over two orders of magnitude. 400 Da PEG achieved the highest conductivity. Replacement of the lithium salt with sodium resulted in similar conductivity, showing potential for sodium ion batteries.
2016 Journal of Power Sources 301 (2016) 35-40Alexis B. B
This document summarizes research on producing transparent thin-film electrodes of Li4Ti5O12 and LiMn2O4 via sol-gel dip coating. Key findings include:
1) Transparent and uniform Li4Ti5O12 and LiMn2O4 thin films were prepared on fluorine-doped tin oxide (FTO) substrates via sol-gel dip coating and heat treatment.
2) X-ray diffraction analysis confirmed the films had the target spinel crystal structures of Li4Ti5O12 and LiMn2O4.
3) Electrochemical characterization including cyclic voltammetry and galvanostatic charging/discharging demonstrated the films were electrochem
The document discusses cell membranes and their structure. It notes that the hydrophobic effect causes phospholipids to form bilayers when placed in water, with their hydrophobic tails buried inside and hydrophilic heads facing out. Bilayers naturally form biological membranes and combine different lipid species. Membranes are fluid and allow proteins and lipids to move freely within. Membranes undergo endocytosis and exocytosis to transport materials in and out of cells. Damage to membranes is repaired through various enzymatic processes.
Did you know that drowning is a leading cause of unintentional death among young children? According to recent data, children aged 1-4 years are at the highest risk. Let's raise awareness and take steps to prevent these tragic incidents. Supervision, barriers around pools, and learning CPR can make a difference. Stay safe this summer!
Do People Really Know Their Fertility Intentions? Correspondence between Sel...Xiao Xu
Fertility intention data from surveys often serve as a crucial component in modeling fertility behaviors. Yet, the persistent gap between stated intentions and actual fertility decisions, coupled with the prevalence of uncertain responses, has cast doubt on the overall utility of intentions and sparked controversies about their nature. In this study, we use survey data from a representative sample of Dutch women. With the help of open-ended questions (OEQs) on fertility and Natural Language Processing (NLP) methods, we are able to conduct an in-depth analysis of fertility narratives. Specifically, we annotate the (expert) perceived fertility intentions of respondents and compare them to their self-reported intentions from the survey. Through this analysis, we aim to reveal the disparities between self-reported intentions and the narratives. Furthermore, by applying neural topic modeling methods, we could uncover which topics and characteristics are more prevalent among respondents who exhibit a significant discrepancy between their stated intentions and their probable future behavior, as reflected in their narratives.
Interview Methods - Marital and Family Therapy and Counselling - Psychology S...PsychoTech Services
A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
2. because it has a strong Li+
solvating ability.29−31
Several groups
also reported PEO as a binder material for Li−S systems.32−35
However, pure PEO tends to crystallize after solvent
evaporation, limiting its binding ability and practical application
in sulfur cathodes.36
Here, we use a combination of PEO and
LiTFSI to form a swelled amorphous gel-like polymer
nanocoating film on conductive carbon. Compared to rigid
high surface area carbon, this preformed PEO-LiTFSI gel
functions as a soft media for Li-ion conducting, electrolyte
wetting, and serves as a swellable reservior for retaining the
electrolyte and polysulfides near the conducting carbon
surfaces, thus enable extended cycling of lean electrolyte Li−
S cells. This study also provides a new insight of potential
degradation mechanism under lean electrolyte conditions that
are different from those under flooded electrolyte conditions.
Demonstration of Nanoscale Confinement with Soft
Swellable Gels for the Lean Electrolyte Li−S Operation.
First, we demonstrate that the PEO10LiTFSI soft gel as
swellable reservoir has excellent capability to solvate and retain
the electrolyte in the mixture. Figure 1a shows the swelling and
electrolyte uptake tests of different binders with the commonly
used 1 M LiTFSI/DME-DOL with the E/S ratio = 4 gE/gS (3.3
mLE/gS) The PEO10LiTFSI is well-swelled in the electrolytes
and absorbs 10 mL/g electrolyte within the gel layer phase.
There is no obvious interaction with other binders: poly-
(vinylidene fluoride) (PVDF), sodium carboxymethyl cellulose
(CMC), and LA133. The electrolyte retention is further
demonstrated by evaporation ratio test. The evaporation of
adsorbed electrolyte is shown in Figure 1b. Due to its low
boiling point, the electrolyte in traditional binders quickly
evaporates. However, the electrolyte evaporation loss in
PEO10LITFSI is significantly lower (<15%), which means a
good capture of the electrolyte. We believe that the key
characteristic of the PEO/LiTFSI gel is its ability to maintain an
amorphous state for an EO/Li ratio between 6 and 10 (a
phenomenon called “crystalline gap”).37,38
This crystalline gap
is formed mainly because the nucleation and growth of ordered
crystalline phases is slowed or inhibited when there is no
favorable way to pack the solvated PEO with LiTFSI solvates
together under this given concentration (PEO10LiTFSI in this
case).39
The XRD patterns of PEO before and after adding
LiTFSI confirmed this (Figure 1c). The crystalline phase of
pure PEO reflected two characteristic diffraction peaks at 20°
and 25°. After adding LiTFSI, the strong interaction between
PEO and LiTFSI resulted in a broadened peak around 20°,
suggesting that the crystalline structure of LiTFSI and PEO
disappeared. The TEM images also confirms a good nano-
coating layer of the PEO10LiTFSI on the host surface with
amorphous structure (Figure S1). The coating thickness is
around 20 nm. After it is swelled, the coating thickness is
expected to be around 100 nm based on the swelling test, and
this thin gel layer retains a good ion transfer property. It also
improves the wettability of the electrodes.
In traditional Li−S cells, the abundant electrolyte facilitates
continuous polysulfide dissolution and causes the loss of active
materials from the sulfur cathode and collapse of the host
scaffold. PEO has a similar chemical structure with DME; the
ether group would retain the dissolved polysulfides within the
swelled gel. To prove that, PEO10LITFSI was added into a
mixed solution of 18 mM Li2S8 + 1 M LiTFSI/DME + DOL
electrolyte. It needs to point out that, due to an ultra high
molecular weight of PEO we used, the dissolution of the PEO
into the electrolyte is significantly suppressed. After the phase
separation was completed, distinct color changes between the
liquid phase on the top and the swelled PEO gel electrolyte in
the bottom (Figure 1d, inset) indicates the selective confine-
ment of polysulfides within the swelled PEO10LiTFSI. The
UV−vis spectrum of the standard 18 mM Li2S8 solution and
liquid phase on top was shown in Figure 1d. The polysulfide
concentration was greatly decreased from 18 mM to ∼2 mM in
the liquid phase after it is mixed with PEO10LiTFSI.40,41
This
means a gel on the carbon host surface can selectively dissolve
Figure 1. (a) Up: solid binder powder before adding the electrolyte, bottom: swelling and electrolyte uptake test of binders in the 1 M LiTFIS
DME/DOL electrolyte. 1-PEO10LiTFSI, 2-LA133, 3-CMC, 4-PVDF. PEO10LiTFSI swelled more than 4 times in volume and uptaked ∼10 mL
electrolyte/g PEO10LiTFSI. (b) Solvent evaporation test of the electrolyte infiltrated in different binders showing a strong absorption ability of PEO
based gel capture mediate; (c) XRD patterns of PEO10LiTFSI composite before and after adding LiTFSI indicating an amorphous region due to the
interaction of Li+
with the ether group; (d) UV−vis spectra of 18 mM Li2S8 swelled in the PEO electrolyte and the polysulfide concentration changes
from 18 mM to ∼2 mM after resting for 12 h; (e) 13
C solid-state NMR spectra of PEO based composite before and after adding LiTFSI and Li2S8,
showing CH2 chain peak narrowing, indicating an increased carbon main chain flexibility due to the interaction of Li+
with ether group; (f) schematic
diagram of the electrode with PEO10LiTFSI nanofilm coating and the confinement of polysulfides by the swelled PEO10LiTFSI gel.
Nano Letters Letter
DOI: 10.1021/acs.nanolett.7b00417
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3. more polysulfides species. During the swelling process, the
working electrolyte itself can be well-restricted within the gel
coating surface. Dipole moments and dielectric constants
increase with the increase in ethylene oxide chain length, and
PEO represents a longer chain glyme so that a higher Li+
solvation ability than DME is achieved after it was swelled with
DOL/DME blends.42,43
This leads to the strong interaction
between Li2Sx and the swelled LiTFSI/PEO gel matrix.44
In
addition, the solid state 13
C NMR spectrum of PEO10LiTFSI
before and after adding saturated Li2S8 polysulfide in the
electrolyte was used to better understand the polysulfide
interaction in the gel phase (Figure 1e). The crystalline phase
of pure PEO reflected a broad CH2 resonance peak, due to the
poor mobility of the polymer chain, and the amorphous
PEO10LiTFSI exhibits narrower sharp peaks.45
After adding the
polysulfide, the PEO10LiTFSI maintained amorphous as seen
from the unchanged narrow CH2 resonance peaks. Based on
the above discussion, the role of the new PEO10LiTFSI gel is
illustrated in Figure 1f. The swelled PEO10LiTFSI on the
cathode surface forms a Li+
-ion conducting gel network across
the whole sulfur cathode, and the gel surrounds S/CNT which
interacts with the polysulfides and confined the electrolyte and
polysulfides within the gel. Because of the good wetting
properties of PEO toward CNT, a uniform nanocoating of the
PEO10LiTFSI would be achieved which facilitates the charge
transfer at the interfaces.
The sulfur composite electrode was made by mixing 80 wt %
S-CNT composite powder, 10% super P carbon additive, and
10% PEO10LiTFSI (dry weight) to form a slurry in acetonitrile
and coated onto an Al current collector in a dry room. The
amorphous PEO10LiTFSI also functions as a good binder and
protective layer to enable a thick, uniform coating of the
cathode materials with a high sulfur loading (4−7 mg/cm2
,
Figure S2).
The electrochemical behavior of PEO10LiTFSI bound sulfur
cathode was evaluated in coin cells. The electrodes bound with
LA133/SBR binder(∼4 mg/cm2
sulfur loading) was also tested
for comparison. Under a flooded electrolyte condition (i.e.,
with excessive electrolyte), two typical discharge/charge
plateaus occur for all electrodes (Figure 2a, d). The one at
2.35 V corresponds to the transformation from elemental sulfur
to long-chain polysulfides; the other one at 2.05 V is due to the
further reduction of polysulfides to Li2S.46
The two cells with
LA133/SBR and PEO10LiTFSI nano coating cathode delivered
specific capacities of 900 mA h/g and 1208 mA h/g,
respectively, at E/S = 17 gE/gS (14.2 mLE/gS). Previously,
our group has reported in a flooded cell, the large amount of
the electrolyte can accelerate the polysulfide dissolution loss
from the cathode and resulted in a characteristic initial quick
capacity fades at first 10 cycles.23,47−49
However, the cell using
LA133/SBR binder shows a significant polarization when the
E/S ratio is reduced from 17 gE/gS to 6.8 gE/gS (5.6 mLE/gS),
especially in the second discharge plateau (Figure 2d). Under
E/S = 6.8 gE/gS condition, the cell initially showed only 580
mA h/g specific capacity and larger than 300 mV overpotential
in comparison with that using PEO10LiTFSI gel. In addition, a
further decrease of the E/S ratio to 4 gE/gS led to an even
poorer kinetics of polysulfides and delivered only a 120 mA h/g
capacity. However, the PEO10LiTFSI cell still functions well
without noticeable polarization under E/S = 4 gE/gS (3.3 mLE/
gS) and delivers an initial capacity of 1183 mA h/g (Figure 2b).
The Li−S cell also shows good cycling stability under various
E/S ratios. The capacity retention after 100 cycles under E/S =
4 gE/gS is 87.3%.
The electrochemical impedance spectra (EIS) (Figure 2c, f)
reveal that not only internal resistance but also the charge
transfer resistance is greatly reduced in PEO10LiTFSI cell in
comparison with the LA133/SBR binder cell. PEO not only
provides a pathway for the electrolyte to penetrate into the
thick cathode but also serves as an electrolyte/lithium ion
reservoir within the cathode architecture. As a result, the active
materials are well-connected with each other by highly
conductive swelled gel electrolyte.
Figure 2. (a, d) Charge−discharge curves of Li−S coin cells with PEO10LiTFSI or LA133 binder in coin cell level, (b, e) the cycling performance of
Li−S coin cell with PEO10LiTFSI or LA133 binder under different electrolyte amounts. (c, f) electrochemical impedance spectra of Li−S coin cells
with different binders under different electrolyte amount conditions.
Nano Letters Letter
DOI: 10.1021/acs.nanolett.7b00417
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4. To further prove the effect on the cycling stability of the
electrolyte reservoir nanocoating, the electrodes with
PEO10LiTFSI gel and LA133 binder before and after 100
cycles under the E/S ratio = 6.8 gE/gS were characterized with
SEM (Figure 3). After cycles, both of the electrodes were
attached on the Al collector. The total thickness of the cathodes
remained stable at 125 um after 100 cycles for PEO10LiTFSI
based electrode, comparing to decreased thickness and rough
morphology of LA133 based electrode. This is consistent with
the speculation that the swelled PEO10LiTFSI within the
cathode scaffold would capture the electrolyte and dissolved
intermediates, then further stabilize the cathode.
Failure Mechanism of Li−S Pouch Cells under a Lean
Electrolyte Condition. In the literature, the dissolution of
polysulfides from cathode and failure of lithium anode was
assigned as the main failure mechanisms of reported Li−S
battery under the flooded electrolyte condition.50
As we
discussed above, in our system, polysulfides are well-confined
within cathode architecture. Our post-test analysis also
indicates Li metal still functioned very well (see Supporting
Information, Figure S3 for detailed discussion). Here, we focus
on the cell failure mechanisms as it seems to be one of the
biggest obstacles for practical rechargeable Li−S batteries. It
should be noted that, in our pouch cell, the anode/cathode
ratio and other parameters still need to be optimized, which is
well-known to affect the pouch cell performance. The cycling
performances of corresponding single layer pouch cell used for
NMR tests were shown in Figure S4. We could expect a further
decrease of E/S ratio in a multilayer pouch cell. The baseline is
set to the E/S ratio = 8 gE/gS (6.7 mLE/gS), and the lean
condition is set to E/S = 3 gE/gS(2.5 mLE/gS). Under this
condition, the cell is stably cycled at the initial 25 cycles, and
there is a quick fading afterward, comparing to a stable cycling
for 40 cycles at E/S = 8 gE/gS. To understand the degradation
mode under lean electrolyte conditions, solid-state 6
Li MAS
NMR techniques were used to characterize the cathode from
the cycled pouch cells (at charged state) (Figure 4a); the
cathode was vacuum-dried without solvent washing. There are
two main peaks at 2.4 ppm (Li2S) and −1.2 ppm (LiTFSI),
with a wide peak in-between.51
With the increase in E/S ratio,
the intensity of 6
Li peak at −1.2 ppm of the cathode increases
linearly, due to the residual electrolyte left inside the cathode
architecture. In contrast, the intensity of 2.4 ppm Li2S peak is 7
times higher under the lean condition than the flooded cell
(Supporting Information, Table S1 for detailed discussion).
This indicates that Li2S accumulated in the sulfur cathode after
cycling. The XRD patterns after different cycles further
confirms the Li2S accumulation under the lean electrolyte
conditionan increased Li2S characteristic peak after 30 cycles
comparing to the one after 10 cycles (Figure 4b). Under a lean
electrolyte condition, Li2S accumulation at the electrode is
potentially a huddle for long cycle life since it could lead to
electrode passivation and polarization after an extended cycle
life. EIS results with a different cycle number under the lean
condition were recorded and shown in Figure 4c. After cycles,
an additional semicircle at low-frequency region appeared
which could be attributed to the growth of the passivating layer
on the surface of the electrode.52−55
Under a lean electrolyte
condition, the consumption of the electrolyte and Li2S growth
at the electrode was critical according to the continuous
increase of both semicircles in the impedance spectrum, which
Figure 3. Cross-section SEM image of PEO10LiTFSI bounded
cathodes (a, b) and LA133 binder cathode (c, d) before and after
100 cycles at an E/S ratio = 6.8 gE/gS.
Figure 4. (a) 6
Li MAS NMR spectra of the cathodes after 30 cycles collected from Li−S pouch cell using a different amount of the electrolyte,
indicating a serious Li2S accumulation under the lean condition comparing to the flooded cell; (b) XRD spectrum of cycled cathode under a lean
condition with different cycling numbers, indicating the accumulation of Li2S with cycling. (c) AC impedance spectrum of Li−S single layer pouch
cell with different cycles under a E/S = 3 gE/gS lean condition.
Nano Letters Letter
DOI: 10.1021/acs.nanolett.7b00417
Nano Lett. 2017, 17, 3061−3067
3064
5. could lead to a serious polarization after an extended cycle life.
Future work should consider approaches to improve the
rechargeability and reversibility of Li2S through the control of
Li2S solubility and catalyzing the charge process using redox
mediators or additives.56−58
Conclusion. In summary, we report a soft gel encapsulation
approach for rechargeable Li−S cell under lean electrolyte
conditions. The swellable PEO10LiTFSI soft gel provides strong
binding ability within the cathode scaffold, absorbs electrolyte,
and forms a highly efficient Li+
conducting gel network within
the cathode. At the same time, the high polysulfide solubility in
the gel enables good polysulfides confinement, so that the
cycling stability can be improved under a lean electrolyte
condition. The Li−S cell with a much lower electrolyte to sulfur
ratio (E/S) of 4 gE/gS could deliver a capacity of 1200 mA h/g,
4.6 mA h/cm2
, and good cycle life. The mechanism study
points to the passivation of the cathode which needs more
undeetsanding in the future.
Experimental Section. Material Synthesis and Charac-
terization. The procedure to prepare S-coated MWCNTs (S-
CNT) has been previously reported.47,59
Elemental sulfur (S8,
Alfa Aesar) and the MWCNTs (Cheap Tubes Inc.) (80:20 w/
w) were mixed together by mechanical ball milling for 2 h. The
mixture was then sealed in a PTFE container and heated to 155
°C in an oven for 24 h under the protection of inert Ar gas.
Morphology observations were performed with a dual-FIB
scanning electron microscope (SEM) (FEI Helios). The solid
state 13
C NMR spectra for the polymers were obtained from
Fourier transformed free induction decays after a single pulse
excitation at Larmor frequencies of 233.2 and 81.4 MHz,
respectively, at ambient temperature (∼25 °C) using a 600
MHz NMR spectrometer (Agilent, USA). The 13
C chemical
shifts for TMS were used as an external reference (i.e., 0 ppm).
6
Li MAS NMR experiments for post cycled pouch cathodes
were performed at 20 °C on a Varian-Inova 850 MHz NMR
spectrometer, operating at a magnetic field of 19.975 T. The 6
Li
MAS spectra were acquired at 125.050 MHz using a single π/4
pulse sequence with a pulse width of 2 μs and a recycle delay at
10 s. A 4 mm pencil type MAS rotor at a sample spinning rate
of 10 kHz were used. 6
Li chemical shifts were externally
referenced to 1 M LiCl aqueous solution (i.e., 0 ppm). All of
the samples were collected from a single layer pouch cell and
packed into an airtight MAS rotor in an argon-filled glovebox.
The ionic conductivity of the electrolytes was measured by a
conductivity meter (Orion 3 Star, Thermo Scientific) 3 times.
The UV−vis spectrum was conducted in the Shimadzu UV−vis
3600 at room temperature using the 1 M LiTFSI and 0.2 M
LiNO3 dissolved in a mixture of 1,3-dioxolane (DOL) and 1,2-
dimethoxyethane (DME) (1:1 v/v) electrolyte as the baseline.
Electrochemical Test. PEO (Sigma-Aldrich, Mw =
4,000,000) was dried under vacuum at 120 °C for 5 days
before use. PEO10LiTFSI was prepared by mixing 40 wt %
LiTFSI and 60 wt % PEO in acetonitrile and stirred at 60 °C
for 24 h. This forms a molar ratio of EO/Li = 10. The
PEO10LiTFSI based cathode with ca. 4 mg-S cm−2
loading was
prepared by mixing 80 wt % S-CNT composite powder, 10%
super P carbon additive, and 10% PEO10LiTFSI in acetonitrile
under the dry atmosphere to form a cathode slurry. Then the
slurry was coated on a carbon coated aluminum collector (MTI
Corp.) and baked at 60 °C under vacuum overnight. The dry
electrode thickness is well-controlled to 120 um at 4 mg/cm2
sulfur loading, and the porosity of the cathode is optimized to
65−70%. The LA133/SBR reference cathode with ca. 4 mg-S
cm−2
loading was prepared similarly by mixing 80 wt % S-CNT
composite powder, 10% super P carbon additive, 5 wt % LA133
binder (Chengdu Indigo Co.), and 5 wt % SBR binder (MTI
Corp.) and forming a slurry with water. The slurries were also
coated onto a C-coated Al foil current collector. Electrodes
were punched to a 1.6 mm2
diameter size. The electrolytes used
were 1 M LiTFSI and 0.2 M LiNO3 dissolved in a mixture of
1,3-dioxolane (DOL) and 1,2-dimethoxyethane (DME) (1/1
v/v), respectively. Half cells with 200 μm thick Li metal foil as
the anode and Celgard 3501 as the separator were assembled
using CR2032 coin cells in an argon-filled glovebox. The
galvanostatic discharge/charge cycles were tested using a
LANHE battery tester at 300 K in a voltage cutoff protocol
between 2.7 and 1.8 V. The specific capacity (SC) was based on
the sulfur mass in the C/S composites, and the areal capacity
(AC) was calculated by the equation AC = SC × areal sulfur
loading. AC impedance was measured using the Solartron
electrochemical workstation. The AC amplitude was ±15 mV,
and the applied frequency range was from 100 kHz to 0.1 Hz.
■ ASSOCIATED CONTENT
*S Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.nano-
lett.7b00417.
(PDF)
■ AUTHOR INFORMATION
Corresponding Authors
*E-mail: jun.liu@pnnl.gov.
*E-mail: yuyan.shao@pnnl.gov.
ORCID
Jian Zhi Hu: 0000-0001-8879-747X
Karl T. Mueller: 0000-0001-9609-9516
Ji-Guang Zhang: 0000-0001-7343-4609
Jun Liu: 0000-0001-8663-7771
Present Address
J.C.: 24 M Technologies, Inc., Cambridge, MA 02139, United
States.
Notes
The authors declare no competing financial interest.
■ ACKNOWLEDGMENTS
This work was supported as part of the Joint Center for Energy
Storage Research (JCESR), an Energy Innovation Hub funded
by the U.S. Department of Energy (DOE), Office of Science,
Basic Energy Sciences (BES). The NMR spectroscopy and
SEM were performed in the Environmental Molecular Sciences
Laboratory (EMSL), a national scientific user facility sponsored
by the U.S. Department of Energy’s Office of Biological and
Environmental Research and located at Pacific Northwest
National Laboratory (PNNL). We gratefully acknowledge Dr.
Kevin R. Zavadil and Dr. Kevin G. Gallagher for helpful
discussions.
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