Molecular and electronic insights of mixing bis(trifluorosulfonyl)imide with bis(fluorosulfonyl)imide anions in imidazolium based ionic liquids: modified hybrid electrolytes with improved performance for Li-ion battery.

Ionic liquids (IL) can be modified into hybrid electrolytes, either with lithium salts and/or organic solvents, which can effectively reduce the viscosity and ionic transferring resistance, which thereby improves the ion transport and interfacial properties of battery electrolytes. Several IL based electrolytes with an imidazolium cation (EMI) have been investigated trying to find beneficial effect of mixing [FSI]- with [TFSI]- anions. However, a compromise would exist between thermal stability and electrochemical performance at elevated temperatures. To further advance the development of the hybrid electrolytes with improved electrochemical performance by decreasing the viscosity, it is important to understand, at a molecular level, the underlying molecular and electronic interactions which influence the viscosity and transport properties of such hybrid ILs. With this in mind, the purpose of the current study is to present detailed structural and electronic insights of imidazolium [EMI] bis(trifluorosulfonyl)imide [TFSI]/bis(fluorosulfonyl)imide [FSI] hybrid electrolytic systems, and their mixtures with ethylene carbonate (EC)/dimethyl carbonate (DMC), which are potential candidates for next generation LIB electrolytes.The nature of molecular interactions in a series of ion pair conformers have been thoroughly discussed by analyzing the interaction energies, stabilization energies and natural orbital analysis of the ion pair conformers.The [FSI]- anions, unlike the [TFSI]- anions, exist on top position with respect to the imidazolium rings. On the basis of a distance criteria, the [EMI]+ and [FSI]- ions show distances of rather weak hydrogen bonds. Charge transfer occurs via the lone pairs of oxygen and nitrogen atom to the σ-type anti-bonding orbital of the C–H bonds (Ylp→σ*C–H), π-type anti-bonding orbitals of C=C bonds (Ylp→π*C=C) and π-type anti-bonding orbitals of N ̶ C bonds (Ylp→π*C–N), where Y = N, O, or F. The values of the stabilization energy E(2) for [EMI][FSI] ion pair conformers are generally small (E(2)n→σ* < 2 kcal/mol) for the individual E(2)n→σ*, E(2)n→π*C=C and/or E(2)n→π*N-C interactions. The [EMI]+ cation and [FSI]- anions tend to form multiple σ* and π* interactions, but reducing the strength of the individual contributions from a potential (linear) maximum.By comparison, from the SDF study, the coordination of the N1 atom of [TFSI]− anion to the atom H1 was enhanced upon the addition of carbonate into the mixture. In sharp contrast to this, the coordination of the N1 atom of [FSI]− anion to the atom H1 was decreased upon the addition of carbonate into the mixture, suggesting that H1 has a stronger interaction with N1 of the [TFSI]- anion than [FSI]- anion. Furthermore, in the pure ionic liquid, the [TFSI]- anions occupy both the on top position and in plane position in the [EMI]+ ring. With lower carbonate contenet, the [FSI]- anions occupy regions that are not occupied by [TFSI] anions which mainly occupy the on top and in plane positions. For higher carbonate content, however, adjacent [FSI]- anions are almost exclusively located on top and below the [EMI]+ ring

Structure and molecular interactions in 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide ionic liquid/carbonate co-solvents -– combined DFT and molecular dynamics study.

Both density functional theory (DFT) and molecular dynamics (MD) based on classical force field were used to provide both structural and electronic insight into the multifold interactions occurring in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid in the presence of ethylene carbonate and dimethyl carbonate co-solvent mixtures which are currently being targeted for applications in next-generation Li-ion battery electrolytes. In order to give a visual understanding of the molecular interactions, the structures of cations, anions, and cation - anion ion pairs were systematically studied using DFT calculations. The nature of hydrogen bond interactions in a series of ion pair conformers have been thoroughly discussed by analyzing the interaction energies, stabilization energies and natural orbital analysis of the ion pair conformers. Multiple but weak C ̶ H---O/N hydrogen bonds and anion donor π*C–N interactions have been observed. Charge transfer occurs mainly from the lone pairs of oxygen and nitrogen atom to the σ-type anti-bonding orbital of the C–H bonds and π-type anti-bonding orbitals of N ̶ C bonds. According to the MD study, the addition of carbonate co-solvents into the pure ionic liquid creates a more structured system than the pure ionic liquid. The coordination of the O/N atoms of the bis(trifluoromethylsulfonyl)imide anion to the most acidic H atom of 1-ethyl-3-methylimidazolium cation showed a marked decrease with increase in carbonate concentration indicating that the C ̶ H---O/N hydrogen bond interaction is reduced by the presence of high carbonate content. Furthermore, in the pure ionic liquid, adjacent cations are almost exclusively located on top and below the ring cation, whereas the anions mainly coordinate to the cation within the ring plane. The addition of large amount of carbonate co-solvents disturb the original near ordering which is found in the pure ionic liquid. Key words: electrolyte, Li-ion, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, ethylene carbonate, dimethyl carbonate

Liquid structure in mixtures of imidazolium based ionic liquid/carbonate solvents for application in next generation lithium ion battery electrolytes: molecular dynamics simulation

We used molecular dynamics (MD) simulations based on classical force field to provide the liquid structure in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid in the presence of ethylene, dimethyl carbonate co-solvents and 1M LiTFSI mixtures which are currently being targeted for applications in next-generation Li-ion battery electrolytes. To show the dependence of the properties on the concentration, we simulated both pure IL and ternary mixtures of IL, EC and DMC with different mixing ratios. The solvation of lithium cations in pure and mixed IL/organic carbonate solvents has been investigated. The MD simulations have predicted a preference of Li+ ions to interact with DMC molecules within its first solvation shell rather than with the highly polar EC ones in the IL/carbonate mixtures, a phenomon which is attributed to the local tetrahedral packing of the solvent molecules in the first solvation shell of Li+ ions.The coordination of the O/N atoms of the bis(trifluoromethylsulfonyl)imide anion to Li+ ions as well as to the most acidic H atom of 1-ethyl-3-methylimidazolium cation has also been analysed, which showed a marked increase in the amplitude of RDF peaks with increase in carbonate concentration, indicating that the interaction between the ions was enhanced by the presence of high carbonate content. Furthermore, in the pure ionic liquid, adjacent cations are almost exclusively located on top and below the ring cation, whereas the anions mainly coordinate to the cation within the ring plane. The addition of large amount of carbonate co-solvents disturb the original near ordering which is found in the pure ionic liquid

Structural and Electronic Insights into 1‑Ethyl-3-Methylimidazolium Bis(fluorosulfonyl)imide Ion Pair Conformers: Ab Initio DFT Study

An understanding of the nature of molecular interactions among the ion pairs of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide [EMI[FSI]] can offer a starting point and significant insight into the more dynamic and multiple interactions within the bulk liquid state. In this context, close inspection of ion pair conformers can offer insight into the effects in bulk [EMI][FSI] liquid. The current work, therefore, gives a detailed analysis of the [EMI][FSI] ion pair conformers through analysis of the interaction energies, stabilization energies, and natural orbital of the ion pair conformers. The structures of the cations, anions, and cation–anion ion pairs of the conformers are optimized systematically by the ωB97X-D method with the DGDZVP basis sets, considering both the empirical dispersion corrections and the presence of a polar solvent, and the most stable geometries are obtained. The [FSI]− anions, unlike [TFSI]− anions, exist at the top position with respect to imidazolium rings. The presence of out-of-plane interactions between the [EMI]+ and [FSI]− ions is in good agreement with the stronger interactions of the [FSI]− anions with alkyl group hydrogens. The presence of out-of-plane conformers could also be related to the interaction of the anion with the π clouds of the [EMI]+ ring. In the [EMI]+ cation, the aromatic ring is π-acidic due to the presence of a positive charge in the N1–C1–N2 ring, which leads to the presence of [FSI]− anion donor [EMI]+ π-acceptor type interactions. The [EMI]+ cation and [FSI]− anions tend to form multiple σ* and π* interactions but reduce the strength of the individual contributions from a potential (linear) maximum. For the ion pair [EMI][FSI], the absolute value of the interaction energies is lower than the normal hydrogen bond energy (50 kJ/mol), which indicates that there is a very weak electrostatic interaction between the [EMI]+ cations and [FSI]− anions. The weaker attraction between the [EMI]+ and [FSI]− ions is suggested to contribute to the larger diffusion coefficients of the ions

sj-docx-1-smo-10.1177_20503121241233232 – Supplemental material for Facilitators and barriers to implementing chest radiography in tuberculosis systematic screening of clinically high-risk groups in Ethiopia: A qualitative study

Supplemental material, sj-docx-1-smo-10.1177_20503121241233232 for Facilitators and barriers to implementing chest radiography in tuberculosis systematic screening of clinically high-risk groups in Ethiopia: A qualitative study by Yishak Abraham, Tsegahun Manyazewal, Zekarias Amdemariam, Hezkiel Petros, Firehiwot Ayenadis, Hana Mekonen and Firehiwot Workneh in SAGE Open Medicine</p

Burden of mental disorders and unmet needs among street homeless people in Addis Ababa, Ethiopia

BackgroundThe impact of mental disorders among homeless people is likely to be substantial in low income countries because of underdeveloped social welfare and health systems. As a first step towards advocacy and provision of care, we conducted a study to determine the burden of psychotic disorders and associated unmet needs, as well as the prevalence of mental distress, suicidality, and alcohol use disorder among homeless people in Addis Ababa, the capital of Ethiopia.MethodsA cross-sectional survey was conducted among street homeless adults. Trained community nurses screened for potential psychosis and administered standardized measures of mental distress, alcohol use disorder and suicidality. Psychiatric nurses then carried out confirmatory diagnostic interviews of psychosis and administered a locally adapted version of the Camberwell Assessment of Needs Short Appraisal Schedule.ResultsWe assessed 217 street homeless adults, about 90% of whom had experienced some form of mental or alcohol use disorder: 41.0% had psychosis, 60.0% had hazardous or dependent alcohol use, and 14.8% reported attempting suicide in the previous month. Homeless people with psychosis had extensive unmet needs with 80% to 100% reporting unmet needs across 26 domains. Nearly 30% had physical disability (visual and sensory impairment and impaired mobility). Only 10.0% of those with psychosis had ever received treatment for their illness. Most had lived on the streets for over 2 years, and alcohol use disorder was positively associated with chronicity of homelessness.ConclusionPsychoses and other mental and behavioural disorders affect most people who are street homeless in Addis Ababa. Any programme to improve the condition of homeless people should include treatment for mental and alcohol use disorders. The findings have significant implications for advocacy and intervention programmes, particularly in similar low income settings