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Abstract: A new ionic liquid-based electrolyte for lithium batteries operating at an elevated temperature of 55°C was prepared by combining N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI) and lithium bis(fluorosulfonyl)imide (LiFSI). The electrolyte does not contain volatile organic components and is thermally stable (up to 285°C) and ionically conductive (2.6mScm−1 at 55°C). The 0.7m LiFSI–PP13TFSI electrolyte has been shown to work effectively with a graphite anode due to the ability of the FSI anions to create a stable solid electrolyte interface on graphite. A discharge capacity of 340–345mAhg−1 was achieved at C/10 rate with a coulombic efficiency of 97–98%. The electrolyte is also compatible with LiCo1/3Mn1/3Ni1/3O2 (NMC) cathode material. At the C/10 rate, we achieved a discharge capacity of 160mAhg−1. The coulombic efficiency remains high above 99%. [Copyright &y& Elsevier]

Abstract: Lithium bis(fluorosulfonyl)imide (LiFSI) in 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) was successfully tested as an electrolyte for graphite composite anodes at elevated temperature of 55°C. The graphite anode showed a good cyclability during the galvanostatic testing at C/10 rate and 55°C with the capacity close to theoretical. The formation of SEI in different electrolytes was the subject of study using impedance spectroscopy on symmetrical cells containing two lithium electrodes. The 0.7m LiFSI in PYR14TFSI exhibits a good ionic conductivity (5.9mScm−1 at 55°C) along with high electrochemical stability and high thermal stability. These properties allow their potential application in large-scale lithium ion batteries with improved safety. [Copyright &y& Elsevier]

Abstract: A new ionic liquid–polymer electrolyte was successfully tested in the planar amperometric solid-state sensor sensitive towards nitrogen dioxide. The electrolyte consists of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) in the ratio 57:43mol.% and exhibits ionic conductivity 1.6×10−4 Scm−1 at 20°C, high electrochemical stability (over 4V on gold or glassy carbon) and thermal stability (over 230°C). The analyte, gaseous nitrogen dioxide in air, was determined using the electrochemical reduction at −900mV vs. Pt/air on gold minigrid indicating electrode with Pt/air as a reference electrode. The sensor response is linear in the NO2 concentration range 0.3–1.1ppm and is reproducible and long-term stable. [Copyright &y& Elsevier]

Abstract: The self-discharge mechanism of LiNi0.4Mn1.6O4, investigated by electrochemical methods, is mostly attributed to oxidative electrolyte decomposition due to the high lithium (de-)insertion potentials, since the material insertion capacity appears to be fully reversible upon subsequent galvanostatic cycling. A series of 40 different compounds, such as for instance fluorinated ethylene carbonate, 1,3-propane sultone, lithium bis(oxalato)borate (LiBOB), or a variety of ionic liquids, was investigated as suitable electrolyte additives to form a stable LNMO/electrolyte interphase in order to prevent the self-discharge by the continuous oxidative electrolyte decomposition. Among these, only one compound, namely succinic anhydride, revealed to have a beneficial effect on the self-discharge of LNMO based cathodes, while showing an enhanced coulombic efficiency and a decreased capacity loss per cycle. Additionally, the modification of the LNMO particles surface by adding succinic anhydride to the electrolyte was confirmed by performing ex situ SEM and XPS analysis of galvanostatically cycled electrodes. [Copyright &y& Elsevier]