: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

With the rapid expansion in energy demands and depletion of fossil fuel reservoirs, the importance of clean energy production and storage has increased drastically. The renewable energy recourses are cost effective, sustainable and carbon dioxide emission free alternatives. Nevertheless, this energy is not always available and needs to be stored. Lithium ion batteries (LIBs) are rapidly used in various applications such as powering electronics, electric vehicles and grid energy storage. However, the increasing concerns regarding load leveling of renewable energy and rise in cost of LIBs due to limited availability of lithium reserves arises doubts whether LIBs alone can meet the rising demands for mid-to-large-scale energy storage. Therefore, attention has been shifted towards development of sodium ion batteries (SIBs) which have wide reserves and low precursor cost and thus is considered as appropriate choice for solar and wind energy development. The prime problem encountered in development of large-scale SIBs is the low effectiveness of appropriate anode material because of large size and sluggish kinetics of Na ions. A comprehensive study regarding anode materials is reported focusing on storage mechanism and structural changes involved during storage of Na ions in various classes of anode materials including carbon-based materials, conversion, conversion/alloying and organic materials. A brief overview of various components of SIBs such as cathode, electrolyte and separator are also discussed.

Prospects in anode materials for sodium ion batteries - A review

Heteroatom-doped carbon-based materials for lithium and sodium ion batteries

The demand for sustainable energy storage and production is vital and continues to grow with increasing human population. Energy utilization and environmental protection demand urgent attention in the development of energy devices, including the expansion and assessment of earth abundant and inexpensive materails. Recently, two-dimensional (2D) structured graphene has emerged as an outstanding energy material due to its excellent physicochemical properties, for example, high thermal and electrical conductivity, high surface area, strong mechanical strength, and an excellent chemical stability. However, pure graphene has a band gap of zero significantly limiting its application as a material. Among the various approaches used to alter the properties of graphene is doping with a heteroatom, which has been shown to be an efficient process in tailoring the properties of 2D-graphene. Heteroatom-doped graphene has several improved physicochemical properties, making graphene a favorable material for application in various fields. In this review, we report the usage and advancement of heteroatom-doped graphene materials in various energy conversion and storage technologies, including supercapacitors, batteries, dye-sensitized solar cells, and hydrogen production from electrocatalytic water splitting. Furthermore, we have also highlighted the recent developments made to date and systematically discuss physicochemical mechanisms, and the precise advantages obtained by the doping of heteroatoms. Finally, the challenges and future perspectives for heteroatom-doped graphene materials are outlined. The information provided in this review should be useful to any researchers involved in the field of graphene research for wide-ranging applications, and structural-oriented (morphology, structure, size and composition) research.

Heteroatom-doped graphene-based materials for sustainable energy applications: A review

High-safety separators for lithium-ion batteries and sodium-ion batteries: advances and perspective

We report an effective approach of utilizing multiwalled carbon nanotubes (MWCNTs) as an active anode material in sodium ion batteries by expanding the interlayer distance in a few outer layers of multiwalled carbon nanotubes. The performance enhancement was investigated using a density functional tight binding (DFTB) molecular dynamics simulation. It is found that a sodium atom forms a stable bonding with the partially expanded MWCNT (PECNT) with the binding energy of −1.50 eV based on the density functional theory calculation with van der Waals correction, where a sodium atom is caged between the two carbon hexagons in the two consecutive MWCNTs. Wave function and charge density analyses show that this binding is physisorption in nature. This larger exothermic nature of binding energy favors the stable bonding between the PECNT and a sodium atom, and thereby, it helps to enhance the electrochemical performance. In the experimental works, partial opening of the MWCNT with the expanded interlayer has been...

Enhanced Sodium Ion Storage in Interlayer Expanded Multiwall Carbon Nanotubes

Facile synthesis of heteroatom doped and undoped graphene quantum dots as active materials for reversible lithium and sodium ions storage

Strong Surface Bonding of Polysulfides by Teflonized Carbon Matrix for Enhanced Performance in Room Temperature Sodium-Sulfur Battery

Sodium-ion batteries (NIBs) are an alternative low-cost battery technology for large-scale energy storage application, and the development of high-performance polymer-based electrolytes is crucial for further advancement of low-cost NIBs. Though electrode materials provide significant contribution to the energy density of the battery, the separator plays a vital role in deciding the safety, duration, and performance of batteries. The glass fiber membrane is considered as the most compatible separator for NIBs because of its high ionic conductivity and reasonable performance. However, the leakage and flammability of the liquid electrolytes while using the glass fiber separator can lead to safety issues. Therefore, herein, we present an alternative approach for the first time to replace the glass fiber separator in NIBs using the porous ceramic membrane (PCM). The polymer blend-based PCM is prepared by a simple solution-casting technique and used as the separator in NIBs. The good thermal stability of the PCM up to 400 °C, high ionic conductivity of about 10-3 S cm-1, high electrolyte uptake, and porous nature make it a better choice over the glass fiber membrane. To demonstrate the applicability of PCM in NIBs, the sodium-ion storage property of hard carbon is evaluated using the PCM as the separator at room temperature. The specific capacity of hard carbon using the PCM-based separator is about 270 mA h g-1 at a current density of 30 mA g-1 which is ∼23% higher than the glass fiber separator (208 mA h g-1) at the same current density. The enhancement in specific capacity is due to the compatibility of the PCM with sodium electrodes, low interfacial resistance, high sodium-ion transference number (0.8), and good electrochemical stability (4.9 V) than the glass fiber separator. This study demonstrates a promising alternative separator to the glass fiber membrane, which can lead to the development of a practical and safe NIB.

Barium Titanate-Based Porous Ceramic Flexible Membrane as a Separator for Room-Temperature Sodium-Ion Battery.

Room-temperature sodium sulfur batteries are receiving immense attention because of their low cost and higher energy density compared to lithium ion batteries. The key challenges of room-temperatur...

Core–Shell Cathode Design with Molybdenum Trioxide as the Electrocatalytic Trapping Layer for High-Energy Density Room-Temperature Sodium Sulfur Batteries

Ajay Piriya Vijaya Kumar Saroja

Papers

Enhanced Sodium Ion Storage in Interlayer Expanded Multiwall Carbon Nanotubes

Facile synthesis of heteroatom doped and undoped graphene quantum dots as active materials for reversible lithium and sodium ions storage

Strong Surface Bonding of Polysulfides by Teflonized Carbon Matrix for Enhanced Performance in Room Temperature Sodium-Sulfur Battery

Barium Titanate-Based Porous Ceramic Flexible Membrane as a Separator for Room-Temperature Sodium-Ion Battery.

Core–Shell Cathode Design with Molybdenum Trioxide as the Electrocatalytic Trapping Layer for High-Energy Density Room-Temperature Sodium Sulfur Batteries