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liquid and electrolytes

Carola Schultz, Sven Vedder, Martin Winter, Sascha Nowak
The development of a novel high performance liquid chromatography (HPLC) method hyphenated to an ion-trap time-of-flight mass spectrometer (IT-TOF-MS) for the separation and identification of constituents from common organic carbonate solvent-based electrolyte systems in lithium ion batteries (LIBs) is presented in this work. The method development was developed for the qualitative structural elucidation of electrolyte main constituents with a special focus on the aging products of these components. The determination of their limits of detection was performed as well...
October 17, 2016: Analytical Chemistry
Maolin Sha, Yusheng Liu, Huaze Dong, Fabao Luo, Fangling Jiang, Zhongfeng Tang, Guanglai Zhu, Guozhong Wu
Room-temperature ionic liquids (ILs) are generally considered as structurally heterogeneous with inherent polar/apolar phase separation. However, even after a decade of research, local dynamics in the heterogeneous structures of ILs remain neglected. Such local dynamics may influence the ion transport of electrolytes, as well as the reaction rate of solvents. In this study, we performed molecular dynamics simulation to analyze the local dynamics for the structural heterogeneity of ILs. Calculations of the diffusion, reorientation, and association dynamics showed a distinct heterogeneous dynamics between the polar and apolar regions of ILs...
October 17, 2016: Soft Matter
Srđan Begić, Hua Li, Rob Atkin, Anthony F Hollenkamp, Patrick C Howlett
The electrochemical systems containing zinc dicyanamide salt (Zn(dca)2) in both 1-ethyl-3-methylimidazolium dicyanamide ([C2mim][dca]) and N-butyl-N-methylpyrrolidinium dicyanamide ([C4mpyr][dca]) ionic liquids (ILs) have been studied by atomic force microscopy (AFM) on a highly oriented pyrolytic graphite (HOPG) surface under different conditions and applied potentials. The results reveal the following: (1) interfacial layers exist in both ILs, even after the addition of 3 wt% water and 9 mol% Zn(dca)2 salt...
October 13, 2016: Physical Chemistry Chemical Physics: PCCP
Poul Erik Hansen, Torben Lund, Jacob Krake, Jens Spanget-Larsen, Soren Hvidt
The complex between diisopropylethylamine (DIPEA) and formic acid has been reinvestigated. Mixing the compounds in the ratio 1:1 leads to a phase separation in which the upper phase is DIPEA, the lower phase is the "ionic liquid" named DIPEF. A combined NMR and DFT study shows that the lower phase primarily is formic acid:formate and diisopropylammonium ions in the ratio 2:1 (acid:base) plus the formic acid dimer. Addition of more acid leads to more and more of the acid dimer. The proton transfer in the system is ~ 0...
October 12, 2016: Journal of Physical Chemistry. B
Qiang Ma, Xingguo Qi, Bo Tong, Yuheng Zheng, Wenfang Feng, Jin Nie, Yongsheng Hu, Hong Li, Xuejie Huang, Liquan Chen, Zhi-Bin Zhou
Solid polymer electrolytes (SPEs) would be promising candidates for application in high-energy rechargeable lithium (Li) batteries to replace the conventional organic liquid electrolytes, in terms of the enhanced safety and excellent design flexibility. Herein, we report novel perfluorinated sulfonimide salt-based SPEs, composed of lithium (trifluoromethanesulfonyl)(n-nonafluorobutanesulfonyl)imide (Li[(CF3SO2)(n-C4F9SO2)N, LiTNFSI) and poly(ethylene oxide) (PEO), which exhibit relatively efficient ionic conductivity (e...
October 11, 2016: ACS Applied Materials & Interfaces
Hsin-Che Lu, Sheng-Yuan Kao, Hsin-Fu Yu, Ting-Hsiang Chang, Chung-Wei Kung, Kuo-Chuan Ho
Herein, three kinds of viologens-based electrochromic devices (ECDs) (heptyl viologen (HV(BF4)2), octyl viologen (OV(BF4)2), and nonyl viologen (NV(BF4)2)) were fabricated utilizing ferrocene (Fc) as a redox mediator. Among them, the NV(BF4)2-based ECD exhibits the highest coloration efficiency (36.2 cm2/C) owing to the lowest driving energy. Besides, switching between 0 and 1.2 V, the NV(BF4)2-based ECD shows a desirable initial transmittance change (∆T = 56.7% at 605 nm), and long-term stability (∆T = 45...
October 11, 2016: ACS Applied Materials & Interfaces
Frank Tambornino, Jonathan Sappl, Felix Pultar, Trung Minh Cong, Sabine Hübner, Tobias Giftthaler, Constantin Hoch
Isothermal electrolysis is a convenient preparation technique for a large number of intermetallic phases. A solution of the salt of a less-noble metal is electrolyzed on a cathode consisting of a liquid metal or intermetallic system. This yields crystalline products at mild reaction conditions in a few hours. We show the aptness and the limitations of this approach. First, we give an introduction into the relevance of electrolytic synthesis for chemistry. Then we present materials and techniques our group has developed for electrocrystallization that are useful for electrochemical syntheses in general...
October 10, 2016: Inorganic Chemistry
Lauryn L Baranowski, Chelsea M Heveran, Virginia L Ferguson, Conrad R Stoldt
The need for smaller, lighter, and longer lasting rechargeable batteries is projected to increase rapidly in the coming years due to high demand for portable electronics and electric vehicles. While traditional Li-ion batteries use liquid-phase electrolytes, these suffer from safety risks and low energy density. Solid-phase electrolytes can avoid these issues by enabling a Li metal anode, but tend to fail during cycling due to Li metal dendrite growth between the electrodes. Because Li dendrite nucleation and growth can be viewed in terms of the mechanical behavior of the battery components, it is critical to understand the mechanical response of candidate electrolyte materials...
October 10, 2016: ACS Applied Materials & Interfaces
Sarah Chappell, Carly Brooke, Richard J Nichols, Laurence J Kershaw Cook, Malcolm Halcrow, Jens Ulstrup, Simon J Higgins
Extensive studies of various families of conjugated molecules in metal|molecule|metal junctions suggest that the mechanism of conductance is usually tunnelling for molecular lengths < ca. 4 nm, and that for longer molecules, coherence is lost as a hopping element becomes more significant. In this work we present evidence that, for a family of conjugated, redox-active metal complexes, hopping may be a significant factor for even the shortest molecule studied (ca. 1 nm between contact atoms). The length dependence of conductance for two series of such complexes which differ essentially in the number of conjugated 1,4-C6H4- rings in the structures has been studied, and it is found that the junction conductances vary linearly with molecular length, consistent with a hopping mechanism, whereas there is significant deviation from linearity in plots of log(conductance) vs...
September 14, 2016: Faraday Discussions
Peter Lobaccaro, Meenesh R Singh, Ezra Lee Clark, Youngkook Kwon, Alexis T Bell, Joel W Ager
In the last few years, there has been increased interest in electrochemical CO2 reduction (CO2R). Many experimental studies employ a membrane separated, electrochemical cell with a mini H-cell geometry to characterize CO2R catalysts in aqueous solution. This type of electrochemical cell is a mini-chemical reactor and it is important to monitor the reaction conditions within the reactor to ensure that they are constant throughout the study. We show that operating cells with high catalyst surface area to electrolyte volume ratios (S/V) at high current densities can have subtle consequences due to the complexity of the physical phenomena taking place on electrode surfaces during CO2R, particularly as they relate to the cell temperature and bulk electrolyte CO2 concentration...
September 29, 2016: Physical Chemistry Chemical Physics: PCCP
Erwan Coadou, Peter Goodrich, Alex R Neale, Laure Timperman, Christopher Hardacre, Johan Jacquemin, Mérièm Anouti
During this work, a novel series of hydrophobic room temperature ionic liquids (ILs) based on five ether functionalized sulfonium cations bearing the bis{(trifluoromethyl)sulfonyl}imide, [NTf2]- anion were synthesized and characterized. Their physicochemical properties, such as density, viscosity and ionic conductivity, electrochemical window along with thermal properties including phase transition behavior and decomposition temperature, have been measured. All of these ILs showed large liquid range temperature, low viscosity and good conductivity...
October 7, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Richard J Nichols, Simon J Higgins
It is now possible to reliably measure single molecule conductance in a wide variety of environments including organic liquids, ultrahigh vacuum, water, ionic liquids, and electrolytes. The most commonly used methods deploy scanning probe microscopes, mechanically formed break junctions, or lithographically formed nanogap contacts. Molecules are generally captured between a pair of facing electrodes, and the junction current response is measured as a function of bias voltage. Gating electrodes can also be added so that the electrostatic potential at the molecular bridge can be independently controlled by this third noncontacting electrode...
October 7, 2016: Accounts of Chemical Research
Dapeng Wu, Fujuan Wang, Hongju Wang, Kun Cao, Zhiyong Gao, Fang Xu, Kai Jiang
An in situ technique was developed to deposit Ag@Ag2S core-shell quantum dots on a SnO2 mesoporous film for solar energy conversion. When adopted as a photoanode, an impressive high photocurrent density of ∼25.6 mA cm(-2) was demonstrated in a cell configuration using polysulfide S(2-)/Sn(2-) as an electrolyte and Cu2S/brass as a counter electrode, which leads to a power conversion efficiency of ∼0.784% for this environmentally benign device. Optical measurements showed that Ag nanoparticles could be employed as plasmon resonance centers to enhance the harvesting efficiency of incident light at the visible and near-infrared range...
October 18, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Innocent S Ike, Iakovos Sigalas, Sunny E Iyuke
The influence of different charging current densities, charging times and several structural designs on symmetric electrochemical capacitor (EC) performance, including capacitance, energy density and power density, has been investigated via modelling and simulation. Understanding the effects of different operating conditions and structural design variables on a capacitor's performance will guide in the optimal design and fabrication of high performance ECs. The operating conditions and design configurations examined were charging current density, charging times, electrode and electrolyte effective conductivity, electrode thickness and electrode porosity...
October 6, 2016: Physical Chemistry Chemical Physics: PCCP
Marija Bešter-Rogač, Marina V Fedotova, Sergey E Kruchinin, Marco Klähn
The mobility and the mechanism of ion pairing of 1,1 electrolytes in aqueous solutions were investigated systematically on nine imidazolium based ionic liquids (ILs) from 1-methylimidazolium chloride, [MIM][Cl], to 1-dodecyl-3-methylimidazolium chloride, [1,3-DoMIM][Cl], with two isomers 1,2-dimethylimidazolium chloride, [1,2-MMIM][Cl], and 1,3-dimethylimidazolium chloride, [1,3-MMIM][Cl]. Molecular dynamics (MD) simulations, statistical mechanics calculations in the framework of the integral equation theory using one-dimensional (1D-) and three-dimensional (3D-) reference interaction site model (RISM) approaches as well as conductivity measurements were applied...
October 5, 2016: Physical Chemistry Chemical Physics: PCCP
Luis Aguilera, Johan Scheers, Aleksandar Matic
We investigate Li(+) coordination in mixed electrolytes based on ionic liquids (ILs) and organic solvents and its relation with the macroscopic properties such as phase behaviour and ionic conductivity. Using Raman spectroscopy we determine the solvation shell around Li(+) in mixtures formed by the IL N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, the organic solvents ethylene carbonate and dimethyl carbonate (EC : DMC 1 : 1), and the salt LiTFSI. We find that the organic solvent molecules preferentially solvate Li(+) as long as there are enough of them...
September 14, 2016: Physical Chemistry Chemical Physics: PCCP
Takuro Matsumoto, Ayaka Ono, Takahiro Ichikawa, Takashi Kato, Hiroyuki Ohno
Gemini amphiphilic zwitterions exhibit thermotropic bicontinuous cubic liquid-crystalline phases having a 3D continuous ionic domain. Incorporation of an acid into the materials led to the creation of novel electrolytes transporting protons efficiently through the 3D continuous domain.
October 6, 2016: Chemical Communications: Chem Comm
Timothy P Lodge, Takeshi Ueki
Room temperature ionic liquids are of great interest for many advanced applications, due to the combination of attractive physical properties with essentially unlimited tunability of chemical structure. High chemical and thermal stability, favorable ionic conductivity, and complete nonvolatility are just some of the most important physical characteristics that make ionic liquids promising candidates for emerging technologies. Examples include separation membranes, actuators, polymer gel electrolytes, supercapacitors, ion batteries, fuel cell membranes, sensors, printable plastic electronics, and flexible displays...
October 5, 2016: Accounts of Chemical Research
Anuja Bhalkikar, Chris M Marin, Chin Li Cheung
An ion-moderated partition high-performance liquid chromatography method was developed for the separation and identification of common organic carbonates. The separation of organic carbonates was achieved on an ion exclusion column with an exchangeable hydrogen ion. An isocratic, aqueous mobile phase was used for elution and detection was performed with a refractive index detector. The developed method was validated for specificity, linearity, limits of detection and quantification, precision and accuracy. All calibration curves showed excellent linear regression (R(2) > 0...
October 5, 2016: Journal of Separation Science
Jimin Shim, Ji Su Lee, Jin Hong Lee, Hee Joong Kim, Jong-Chan Lee
Gel polymer electrolytes (GPEs) based on semi-interpenetrating polymer network (IPN) structure for lithium-ion batteries were prepared by mixing boron-containing crosslinker (BC) composed of ion-conducting ethylene oxide (EO) chains, crosslinkable methacrylate group, and anion-trapping boron moiety with poly(vinylidene fluoride) (PVDF) followed by ultraviolet light-induced curing process. Various physical and electrochemical properties of the GPEs were systematically investigated by varying the EO chain length and boron content...
October 4, 2016: ACS Applied Materials & Interfaces
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