A large series of ionic liquids (ILs) based on the weakly coordinating alkoxyaluminate [Al(hfip)(4)](-) (hfip: hexafluoroisopropoxy) with classical as well as functionalized cations were prepared, and their principal physical properties determined. Melting points are between 0 ([C(4)MMIM][Al(hfip)(4)]) and 69 °C ([C(3)MPip][Al(hfip)(4)]); three qualify as room-temperature ILs (RTILs). Crystal structures for six ILs were determined; their structural parameters and anion-cation contacts are compared here with known ILs, with a special focus on their influence on physical properties. Moreover, the biodegradability of the compounds was investigated by using the closed-bottle and the manometric respirometry test. Temperature-dependent viscosities and conductivities were measured between 0 and 80 °C, and described by either the Vogel-Fulcher-Tammann (VFT) or the Arrhenius equations. Moreover, conductivities and viscosities were investigated in the context of the molecular volume, V(m). Physical property-V(m) correlations were carried out for various temperatures, and the temperature dependence of the molecular volume was analyzed by using crystal structure data and DFT calculations. The IL ionicity was investigated by Walden plots; according to this analysis, [Al(hfip)(4)](-) ILs may be classified as "very good to good ILs"; while [C(2)MIM][Al(hfip)(4)] is a better IL than [C(2)MIM][NTf(2)]. The dielectric constants of ten [Al(hfip)(4)](-) ILs were determined, and are unexpectedly high (ε(r)=11.5 to 16.8). This could be rationalized by considering additional calculated dipole moments of the structures frozen in the solid state by DFT. The determination of hydrogen gas solubility in [Al(hfip)(4)](-) RTILs by high-pressure NMR spectroscopy revealed very high hydrogen solubilities at 25 °C and 1 atm. These results indicate the significant potential of this class of ILs in manifold applications.

Several, partly new, ionic liquids (ILs) containing imidazolium and ammonium cations as well as the medium-sized [NTf2 ](-) (0.230 nm(3) ; Tf=CF3 SO3 (-) ) and the large [Al(hfip)4 ](-) (0.581 nm(3) ; hfip=OC(H)(CF3 )2 ) anions were synthesized and characterized. Their temperature-dependent viscosities and conductivities between 25 and 80 °C showed typical Vogel-Fulcher-Tammann (VFT) behavior. Ion-specific self-diffusion constants were measured at room temperature by pulsed-gradient stimulated-echo (PGSTE) NMR experiments. In general, self-diffusion constants of both cations and anions in [Al(hfip)4 ](-) -based ILs were higher than in [NTf2 ](-) -based ILs. Ionicities were calculated from self-diffusion constants and measured bulk conductivities, and showed that [Al(hfip)4 ](-) -based ILs yield higher ionicities than their [NTf2 ](-) analogues, the former of which reach values of virtually 100 % in some cases.From these observations it was concluded that [Al(hfip)4 ](-) -based ILs come close to systems without any interactions, and this hypothesis is underlined with a Hirshfeld analysis. Additionally, a robust, modified Marcus theory quantitatively accounted for the differences between the two anions and yielded a minimum of the activation energy for ion movement at an anion diameter of slightly greater than 1 nm, which fits almost perfectly the size of [Al(hfip)4 ](-) . Shallow Coulomb potential wells are responsible for the high mobility of ILs with such anions.

The step-change in gravimetric energy density needed for electrochemical energy storage devices to power unmanned autonomous vehicles, electric vehicles, and enable low-cost clean grid storage is unlikely to be provided by conventional lithium ion batteries. Lithium-sulfur batteries comprising lightweight elements provide a promising alternative, but the associated polysulfide shuttle in typical ether-based electrolytes generates loss in capacity and low coulombic efficiency. The first new electrolyte based on a unique combination of a relatively hydrophobic sulfonamide solvent and a low ion-pairing salt, which inhibits the polysulfide shuttle, is presented. This system behaves as a sparingly solvating electrolyte at slightly elevated temperatures, where it sustains reversible capacities as high as 1200-1500 mAh g over a wide range of current density (2C-C/5, respectively) when paired with a lithium metal anode, with a coulombic efficiency of >99.7 % in the absence of LiNO additive.

Structures of the reactive intermediates (enamines and iminium ions) of organocatalysis with diarylprolinol derivatives have been determined. To this end, diarylprolinol methyl and silyl ethers, 1, and aldehydes, PhÀCH 2 ÀCHO, t BuÀCH 2 ÀCHO, PhÀCH ¼ CHÀCHO, are condensed to the corresponding enamines, A and 3 (Scheme 2), and cinnamoylidene iminium salts, B and 4 (Scheme 3). These are isolated and fully characterized by melting/decomposition points, [a] D , elemental analysis, IR and NMR spectroscopy, and high-resolution mass spectrometry (HR-MS). Salts with BF 4 , PF 6 , SbF 6 , and the weakly coordinating Al[OC(CF 3 ) 3 ] 4 anion were prepared. X-Ray crystal structures of an enamine and of six iminium salts have been obtained and are described herein (Figs. 2 and 4 -8, and Tables 2 and 7) and in a previous preliminary communication (Helv. Chim. Acta 2008Acta , 91, 1999. According to the NMR spectra (in CDCl 3 , (D 6 )DMSO, (D 6 )acetone, or CD 3 OD; Table 1), the major isomers 4 of the iminium salts have (E)-configuration of the exocyclic N¼C(1') bond, but there are up to 11% of the (Z)-isomer present in these solutions (Fig. 1). In all crystal structures, the iminium ions have (E)-configuration, and the conformation around the exocyclic N-CÀC-O bond is synclinal-exo (cf. C and L), with one of the phenyl groups over the pyrrolidine ring, and the RO group over the p-system. One of the metasubstituents (Me in 4b, CF 3 in 4c and 4e) on a 3,5-disubstituted phenyl group is also located in the space above the p-system. DFT Calculations at various levels of theory (Tables 3 -6) confirm that the

The fast, high yield synthesis and full characterization of Na[B(hfip)(4)] (hfip: OC(H)(CF(3))(2)) from NaBH(4) and hexafluoroisopropanol (hfipH) is presented. By anion metathesis, five [B(hfip)(4)](-) salts with classical/functionalized ionic liquid (IL) cations with melting points between 0 ([C(6)MIM](+)[B(hfip)(4)](-)) and 113 °C ([C(4)MMorph](+)[B(hfip)(4)](-)) were prepared. Four of these qualify as ILs and one as room temperature IL (RTIL). The properties of the borate anion [B(hfip)(4)](-) and its aluminum analogue [Al(hfip)(4)](-) were compared based on the available structural information from XRD. Viscosities (10.3 (90 °C) to 855 (0 °C) mPa s(-1)) and conductivities (0.603 (30 °C) to 4.844 (90 °C) mS cm(-1)) were measured between 0 and 90 °C, and described by the Vogel-Fulcher-Tammann (VFT) equations. The properties of the [B(hfip)(4)](-) ILs were analyzed in the context of the anion-dependent molecular volume V(m)-viscosity-/conductivity-correlations, also in comparison to ILs with [BF(4)](-)/[PF(6)](-), [N(CN)(2)](-), [Tf(2)N](-) and [Al(hfip)(4)](-) counterions. The viscosities and conductivities of [B(hfip)(4)](-) ILs are slightly inferior to [Al(hfip)(4)](-) ILs, similar to/better than all other anions given above. According to the Walden plots, the ionicity of the [B(hfip)(4)](-) ILs may at least be classified as "good". By sharp contrast to the [Al(hfip)(4)](-) ILs, the [B(hfip)(4)](-) ILs have good stability against humidity/water. Thus, handling of [B(hfip)(4)](-) ILs in an open laboratory atmosphere over hours and days is allowed and further facilitates the use of this new IL class.

The fluorinated phosphate lithium bis (2,2,2-trifluoroethyl) phosphate (LiBFEP) has been investigated as a film-forming additive employed to passivate the cathode and hinder continuous oxidation of the electrolyte. Cyclic voltammetry (CV) and linear sweep voltammetry coupled with online electrochemical mass spectrometry (LSV-OEMS) on a conductive carbon electrode (i.e., a C65/PVDF composite) showed that LiBFEP decreases electrolyte oxidation (CV and LSV) and LiPF 6 decomposition at high potentials. Incorporation of LiBFEP (0.1 and 0.5 wt%) into LiPF 6 in ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (3:7 wt) results in improved coulombic efficiency and capacity retention for LNMO/graphite cells. Ex-situ surface analysis of the electrodes suggests that incorporation of LiBFEP results in the formation of a cathode electrolyte interface (CEI) and modification of the solid electrolyte interface (SEI) on the anode. The formation of the CEI mitigates electrolyte oxidation and prevents the decomposition of LiPF 6 , which in turn prevents HF-induced manganese dissolution from the cathode and destabilization of the SEI. The passivation of the cathode and stabilization of the SEI is responsible for the increased coulombic efficiency and capacity retention. Since their debut in 1991, lithium ion batteries (LIB) have become the universal power source for consumer electronics.1 Larger format LIBs such as those needed to power electric vehicles (EVs), an important future market, have amassed considerable interest; however higher specific energy densities are required for larger format LIBs.1,2 The practical way to increase energy density is to employ cathode materials with increased theoretical capacities and/or high discharge plateaus, and thus high energy (HE) or high voltage (HV) cathodes are required in order for LIBs to meet the demands of the EV market.3 While both HE and HV cathodes have been implemented, current research efforts are focused on overcoming the caveats associated with these materials. The oxidative instability of carbonate-based electrolytes is a central limitation for cells with various cathode chemistries operated above 4.4 V. [3][4][5][6][7] In addition to the instability of the electrolyte, cathodes such as nickel-rich layered oxides (LiNi x Mn y Co z O 2 ), lithium-rich layered oxides (0.6 Li 2 MnO 3 • 0.4 Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 ), and HV spinel (LiNi 0.5 Mn 1.5 O 4 ) (LNMO) all suffer from structural instability when operated at high potentials.5-11 While the layered oxides are capable of delivering higher practical energy densities, the lack of cobalt in LNMO alleviates the issues of cost and resource limitations.7 As the higher energy densities associated with HE materials can only be obtained at higher cutoff potentials, oxidation of the electrolyte is a universal problem to both HE and HV cathodes. This work focuses on improving the performance of LNMO/Graphite cells.The capacity fading observed in LNMO/Graphite cells is due to continuous oxidation of the electrolyte and transition...

Measurements of electrical properties of MnO2 and Mn2O3 were carried out on material obtained by pyrolysis of normalMnfalse(NO3)2 . From resistivity data, it is proposed that the conduction process is due to oxygen forming a donor level at 0.044 eV. In Mn2O3 , oxygen vacancies might be acting as an acceptor level with an activation energy of 0.30 eV. Resistivity measurements were used to establish the MnO2‐Mn2O3 transition temperature at 545°C. The Hall mobility of MnO2 was measured at 25°C. For resistivities of 0.1–100 ohm‐cm, the mobility depends on the resistivity. This was taken as an indication that impurity scattering is the dominating process in this region. The voltage‐current characteristic was measured for samples from 0.1 to 105 ohm‐cm. The material showed ohmic behavior for fields from 10 mV/cm to 100 V/cm. The Seebeck coefficient was investigated over the temperature range 25°‐125°C. A response of 0.6 mV/°C was found in high‐resistivity n‐type MnO2 , and 0.37 mV/°C in normalp‐type Mn2O3 .

Several new ionic liquids (ILs) were prepared from Na[B(tfe)4] (tfe=OCH2 CF3 ) via metathesis, including one room temperature IL (RTIL). Prior to synthesis, suitable cations were chosen via predictive quantum-chemical calculations. Nuclear magnetic resonance monitoring over almost a month showed a total stability of the anion in the presence of water. The temperature-dependent viscosities and melting points of all the new ILs were determined. The data indicate that [B(tfe)4 ](-) ILs may be too viscous for electrochemical applications, but are interesting candidates for lubricant research.