[HMIM] [Br 9 ] ([HMIM] = 1-hexyl-3-methylimidazolium) has been investigated by Raman spectroscopy, single-crystal X-ray diffraction and NMR spectroscopy. Conductivity measurements show a high electrical conductivity like other polybromides.

Twelve bromoaluminate based ionic liquids (ILs) were synthesized and characterized by IR, Raman, and NMR spectroscopy, as well as single crystal X-ray diffraction in part. Their principal physicochemical properties including melting points, conductivities, viscosities, and densities were determined and compared with related ILs. The influence of the cation and anion on the physicochemical properties are discussed. The [AlBr ] based salts are-with one exception-solid at room temperature, while the compounds based on the anion [Al Br ] are liquid at room temperature. The liquid salts show low viscosities (49-139 mPa s), medium to high conductivities (0.76-3.53 mS cm ) and high densities (1.82-2.04 g cm ) at 28 °C. Furthermore, we showed aluminum electrodeposition from Lewis acidic ILs based on AlBr and 1-hexyl-3-methylimidazolium bromide and investigated the stability range of various formulations.

Mixtures of AlX (X=Cl, Br) with 1-butylimidazole (BuIm) in various ratios were investigated. The mixtures were characterized by multinuclear ( H, Al, C, and N) NMR, IR, and Raman spectroscopy and in part by single-crystal X-ray diffraction. Depending on the molar fraction x(AlBr ) of the AlBr -based mixtures, the cationic aluminum complexes [Al(BuIm) ] and [AlBr (BuIm) ] , the neutral adduct [AlBr (BuIm)], as well as the anions Br , [AlBr ] , and [Al Br ] could be identified as the products of the symmetric and asymmetric cleavage of dimeric Al Br . Furthermore, there are hints at the formation of [AlBr (BuIm) ] or related cations. Comparison of the AlBr /BuIm system with AlCl -based mixtures revealed the influence of the halide: In contrast to AlBr , the trication [Al(BuIm) ] could not be detected as main product in a 1:6 mixture of AlCl and BuIm. Additionally, [AlCl (BuIm)] crystallizes from a mixture with x(AlCl )=0.60 at room temperature, whereas the corresponding AlBr -based mixture remains liquid even at +6 °C. Three AlBr -based mixtures are liquid at room temperature, whereas all other mixtures are solids with melting points between 46 and 184 °C. The three liquid mixtures exhibit medium to high viscosities (117 to >1440 mPa s), low conductivities (0.03-0.20 mS cm ), but high densities (1.80-2.21 g cm ). Aluminum could be successfully deposited from one of the neat Lewis acidic mixtures of the AlBr -based system.

We present first investigations towards the feasibility of an Al/Br2 battery based on ionic liquids (ILs). The charged battery consisted of an Al anode, a bromoaluminate IL as the anolyte, an ion‐exchange membrane, a polybromide IL as the catholyte, and an inert cathode. The open‐circuit voltage (OCV) of the battery was strongly dependent on the molar ratio of AlBr3 in the anolyte with values of 1.9 V when using a Lewis basic anolyte and 1.1 V when using a Lewis neutral anolyte. NMR studies with different organic cations in both electrolytes revealed the migration of organic cations as major charge‐balancing ions, which leads to a reduced theoretical energy density of 33 Wh L−1 (as opposed to 166 Wh L−1 for an anion mechanism). The battery could be discharged with high discharge resistance values of up to 3 kΩ cm2, and preliminary charging attempts revealed high overpotentials. Hitherto, an Al/Br2 cell with a Lewis basic anolyte could be used as primary battery with an OCV of 1.9 V.

HMIM][Br 9 ]: A Room-Temperature Ionic Liquid Based on a Polybromide Anion. -[hmim][Br9] is prepared by addition of Br2 to [hmim]Br in a molar ratio of 5:1 (-40°C, 72 h). The compound crystallizes in the orthorhombic space group P212121 (Z = 4, single crystal XRD). The anionic structure is built up by Brions and Br2 molecules. A central Branion is end-on coordinated by six Br2 molecules, four of which are asymmetrically bridging two bromide ions resulting in two-dimensional ] layers. The compound is further characterized by Raman spectroscopy and NMR spectroscopy. Temperature-dependent conductivity measurements show a high electrical conductivity like in other polybromides. -(HALLER, H.; HOG, M.; SCHOLZ, F.; SCHERER, H.; KROSSING*, I.; RIEDEL, S.; Z. Naturforsch., B: Chem. Sci. 68b (2013) 10, 1103-1107, http://dx.doi.org/10.5560/ZNB.2013-3143 ; Inst. Anorg. Anal. Chem., Albert-Ludwigs-Univ., D-79104 Freiburg/Br., Germany; Eng.) -J. Schramke 04-215 [Br -9