Bulk protonated mesitylene, toluene, and benzene bromoaluminate salts were stabilized and characterized in the superacidic system HBr/n AlBr3 with NMR spectroscopy and X-ray analysis of [HC6 H3 (CH3 )3 ](+) [AlBr4 ](-) (1), [HC6 H5 (CH3 )](+) [AlBr4 ](-) (2), and [C6 H7 ](+) [Al2 Br7 ](-) ⋅C6 H6 (3). Protonation attempts in bromoaluminate ILs led to a complete protonation of mesitylene, and a protonation degree of up to 15 % for toluene in the IL BMP(+) [Al2 Br7 ](-) . Benzene could only be protonated in the more acidic IL BMP(+) [Al3 Br10 ](-) , with a degree of 25 %. Protonation attempts on aromatics provide evidence that the bromoaluminate ILs tolerate superacidic environments. On the basis of the absolute Brønsted acidity scale, quantum chemical calculations confirmed the superacidic properties, and rank the acidities in ILs down to a pHabs value of 164 with an error of less than one pH unit compared with experimental findings. The neat AlBr3 /HBr system even may reach acidities down to pHabs 163.

Crystalline and properly ordered protonated benzene as the [C6 H7 ](+) [Al2 Br7 ](-) ⋅(C6 H6 ) salt 1 are obtained by the combination of solid AlBr3 , benzene, and HBr gas. Compound 1 was characterized and verified by NMR, Raman and X-Ray spectroscopy. This unexpected simple and straight forward access shows that HBr/AlBr3 is an underestimated superacid that should be used more frequently.

This study reports the behavior of the compounds BF3·D (with D = dimethyl carbonate, ethylene carbonate, ethyl methyl carbonate, propylene carbonate) as electrolyte additives in Li[Ni0.33Co0.33Mn0.33O2]/graphite cells with LiPF6 (1 M) in EC:EMC (3:7 wt%) as electrolyte. The adducts were prepared from gaseous BF3 with the corresponding carbonates in a simple Lewis acid base reaction and fully characterized (FT–IR and NMR spectroscopy, single crystal X-ray diffraction). The electrochemical behavior of the additives was examined at concentrations of 1 wt% and 0.25 wt% added to the electrolyte. Electrochemical impedance spectroscopy of cells with 1 wt% additive, display a significantly lower cell impedance than cells without additive, but also a slightly decreased capacity. To combine the high capacity retention with a low cell impedance the concentration of the additive was reduced. Thus, cell testing with 0.25 wt% additive incorporated with the electrolyte showed no difference in capacity retention after 55 cycles at 25 °C, but had lower cell impedance. The rate-performance test shows a higher capacity retention for cells with additive at high C–rates. The surface chemistry of the electrodes was studied by X-ray photoelectron spectroscopy and suggests that the additives react on both electrodes (Li[Ni0.33Co0.33Mn0.33O2] and graphite) and improve the electrode interphases.

Die Reaktion von festem AlBr 3 , Benzol und HBr-Gas führte zur ausgeordneten Kristallstruktur des protonierten Benzols der Zusammensetzung [C 6 H 7 ] + [Al 2 Br 7 ] À ·(C 6 H 6 ) (1). Die Verbindung konnte mittels Rçntgenstrukturanalyse, NMRund Raman-Spektroskopie zweifelsfrei nachgewiesen werden. Dieser unerwartet einfache und leicht zugängliche Syntheseweg zeigt, dass HBr/AlBr 3 eine Supersäure ist, deren Potential bisher unterschätzt wurde und noch weiter untersucht werden sollte.Areniumionen, die üblicherweise Wheland-Zwischenstufen [1] genannt werden, aber korrekterweise auf Pfeiffer und Wizinger [2] zurückzuführen sind, werden allgemein als Zwischenstufen in elektrophilen aromatischen Substitutionsreaktionen akzeptiert. Die ersten spektroskopischen Nachweise eines protonierten Aromaten gelang Gold und Tye [3] am Beispiel von Anthracen sowie Reid [4] am Beispiel eines alkylierten Benzols. In den darauffolgenden Jahren wurden protonierte Aromaten in klassischen supersauren Systemen untersucht und nachgewiesen. [5] Stabile Salze von Areniumionen konnten erstmals mit elektronendonierenden Gruppen, wie z. B. als [C 6 (CH 3 ) 7 ] + -Ion, [6] oder mit Pyrrolidinium- [7] oder Silylsubstituenten [8] stabilisiert und isoliert werden.Benzol ist das einfachste unsubstituierte protonierbare Aren. Für seine protonierte Form, das Benzeniumion [C 6 H 7 ] + , wurden drei verschiedene Strukturen formuliert: die s-(C 2v ), die verbrückte p-(C s ) und die flächenzentrierte p-Struktur (C 6v ; Schema 1). Intensive NMR-Untersuchungen an [C 6 H 7 ] + in HF-SbF 5 -SO 2 ClF bei À78 8C, À129 8C und À140 8C, [9] IR-Spektroskopie, [10,11] UV-Spektroskopie [11] und theoretische Studien [12] ergaben eindeutige Beweise für die s-Struktur als stabilste Form. Obwohl Festkçrper-NMR-und IR-Untersuchungen von [C 6 H 7 ] + [CB 11 H 6 Cl 6 ] und [C 6 H 7 ] + [CB 11 HMe 5 Br 6 ] [13,14] durchgeführt wurden, wurde nur die Einkristallstruktur des [C 6 H 7 ] + -Salzes mit dem [CB 11 HMe 5 Br 6 ] À -Anion verçffentlicht. Das Benzeniumion weist hier allerdings eine Fehlordnung auf und macht damit eine genaue Differenzierung der drei mçglichen Formen in Schema 1 unmçglich. [13][14][15] Daher fehlt immer noch ein kristallographischer Beweis für die bevorzugte s-Struktur im Festkçrper.Seit einiger Zeit beschäftigen wir uns mit Studien des HBr/AlBr 3 -Systems. Durch Kombination der Brønsted-Säure HBr mit der Lewis-Säure AlBr 3[16] kann Brønsted-Superazidität erreicht werden. [17] Dieses System erlaubte die kristallographische Charakterisierung einiger instabiler und reaktiver protonierter Teilchen, wie des tert-Butylkations als [Al 2 Br 7 ] À -Salz (eine ionische Flüssigkeit bei Raumtemperatur; RT-IL) [18] oder sogar des Salzes des nichtklassischen 2-Norbornylkations [C 7 H 11 ] + [Al 2 Br 7 ] À

Weakly coordinating anions (WCAs) facilitate the stabilization and isolation of highly reactive and almost “naked” cations. Alkoxyaluminate-based WCAs such as [Al(OC(CF3)3)4]− ([pf]−) are widely used due to their synthetic accessibility...

The stoichiometric 1:1 combination of LiX (X = OCH 2 CF 3 , OC(H)(CF 3 ) 2 , CO 2 CF 3 ) with BF 3 •D (D = dimethyl carbonate, ethylene carbonate, ethyl methyl carbonate, propylene carbonate and diethyl ether) yields an electrolyte with a significantly increased conductivity in comparison to pure LiX in EC:EMC (3:7 wt%). The combination of Li[CO 2 CF 3 ] and BF 3 •EC displays with 5.8 mS•cm -1 (1.5 mol•L -1 ) the highest conductivity of all investigated systems, which is also higher than that of LiBF 4 in the same solvent. NMR studies of all composite electrolytes show the presence of various boron species like BX 3 , Li[BF 3 X], Li[BF 2 X 2 ] and Li[BFX 3 ], which distribute characteristically for each LiX. The investigation of the electrochemical behavior of the composite electrolytes in Li[Ni 0.33 Mn 0.33 Co 0.33 O 2 ]/graphite cells showed a direct relation between cycling behavior, impedance and boron content on CEI/SEI. In the differential plots of the first cycle, an irreversible oxidation was observed in all cells, which is attributed to the formation of the SEI of the composite electrolyte. Ex situ analysis of the electrodes with XPS showed an increase of the boron content on the surface of both electrodes in the order of Li[OC(H)(CF 3 ) 2 ] < Li[OCH 2 CF 3 ] < Li[CO 2 CF 3 ]. This ordering was also found for the growth of the impedance of the cells.

The synthesis, spectroscopic and electrochemical characterization of Li[N(SiMe 3 )(SO 2 R F )] (R F = CF 3 , n-C 4 F 9 ) as well their behavior as electrolyte additive in lithium ion batteries (LIBs) is reported. The lithium salts were obtained by deprotonation of the corresponding acids HN(SiMe 3 )(SO 2 R F ) with n-butyllithium in n-pentane. The electrochemical investigations suggested poten-tial as additives for LIBs. Thus, NCM111/graphite cells (NCM111 = Li[Ni 0.33 Co 0.33 Mn 0.33 ]O 2 ) with LP57 as electrolyte (LP57 = 1.0 M LiPF 6 in EC/EMC 3 : 7) were built to test the performance. Cells with Li[N(SiMe 3 )(SO 2 R F )] as additives show coulombic efficiencies of over 99.6 %, less capacity fading over 55 cycles and a significantly lower cell impedance built up. in 3 : 7 (wt.%) EC/EMC (LP57, battery grade water content � 50 ppm, BASF®) were used. Additives used were added as weight percentage (0.25 wt.%) relating to the total mass of the electrolyte. All cells were prepared in duplicate. 4 5 6 7 8

Ni-rich cathode active material Li 1+x [Ni 0.85 Co 0.10 Mn 0.05 ] 1−x O 2 (NCM851005) was exposed to BF 3 gas at room temperature with pressures between 25 mbar and 2478 mbar. It mainly gave an LiBF 4 coating by reaction with the basic surface lithium impurities. The electrochemical investigations up to full-cell level displayed a significantly improved long-term cycling behavior at 45 °C for only 0.08 wt% BF 3 coated NCM851005 material, compared to pristine NCM851005 material. The internal resistance of full-cells was reduced for all tested amounts of BF 3 coating (after 300 cycles: pristine NCM851005 +293% and 0.08 wt% BF 3 coated NCM851005 +133% resistance built-up). Moreover, online electrochemical mass spectrometry studies showed a reduced CO 2 release in the first cycle of half-cells built with the coated NCM851005 material compared to those with pristine NCM851005 material. The thermal annealing of the coated NCM851005 material at 200 °C or 400 °C led to a decrease of LiBF 4 , but to an increase of LiF content on the surface. However, coated NCM851005 material with thermal annealing exhibits lower discharge capacities after 250 cycles compared to NCM851005 material with equal coating amount, which were not thermally annealed.