Ion chromatography was used to investigate the stability of LiTFSI in water at various temperatures. The addition of HNO 3 , LiOH and HTFSI as pH adjustment measures was studied and the long-term stability of the electrolytes at different pH values stored at 60 • C investigated. A minor degradation product was found upon the addition of HNO 3 to the electrolyte and identified via electrospray ionization mass spectrometry. The compound was formed only in traces immediately after the acidification and the concentration is not increasing over time. Electrochemical stability window investigations, using two different methods, indicate the wide applicable potential range of the aqueous LiTFSI electrolyte, which, combined with the high stability of the TFSI anion vs. hydrolysis and elevated temperature, smoothens the path for a possible application in aqueous lithium-ion systems.Secondary energy storage devices based on lithium-ion transport and storage are of particular interest and under development worldwide due to their high specific energy, high energy density and their extended charge-discharge capabilities. 1 Most of these systems are based on low potential anodes, e.g. graphite or metallic lithium, a high potential cathode and a mixture of organic solvents as electrolyte. 2,3 These organic electrolytes, typically based on cyclic and/or linear carbonates 4-6 display favorable properties on the negative electrode side, including the formation of a lithium conducting passivation layer on the surface of the electrode, the so-called solid electrolyte interphase (SEI). 2,7,8 The presence of the SEI layer extends the electrochemical stability window of the electrolyte at the negative electrode, even with very reducing anode materials, such as metallic Li and lithiated graphite. 9-11 However, on the positive electrode side, the stability window of these systems limits the number of applicable active materials, especially due to the limited stability of most of these compounds at potentials exceeding 5 V vs. Li/Li + . 12-14 Additional drawbacks are the flammability of the organic solvents, 15,16 the relative low conductivity of these systems compared to aqueous electrolytes and the necessity to assemble the electrochemical cells in a water-free and therefore cost-intensive environment, especially but not only because of the tendency to hydrolysis of the commonly used electrolyte salt LiPF 6 . 12, [17][18][19][20] As possible ease and solution of these issues, Dahn et al. pioneered and proposed the use of aqueous electrolytes in lithium-ion batteries. 21 Part of their work is based on LiMn 2 O 4 and VO 2 (B) with the application of a lithium nitrate based aqueous electrolyte. 21,22 In this early study, the crucial influence of the pH value regarding the stability and the oxygen pressure control was pointed out and emphasized. 21 This continued in the application of different active materials and electrochemical systems, e.g. a Li 2 Mn 4 O 9 /LiMn 2 O 4 /H 2 O-LiNO 3 -LiOH cell 23 and LiCoO 2 or LiFePO 4 in combination wi...

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The hazard potential, including carcinogenicity, of inhaled man-made vitreous fibers (MMVFs) is correlated with their biodurability in the lung, as prerequisite for biopersistence. Abiotic dissolution testing serves to predict biodurability. We reanalyzed the International Agency for Research on Cancer Monograph on MMVFs and found that the correlation between in vivo biopersistence and abiotic dissolution presented therein confounded different simulant fluids and further confounded evaluation of leaching vs structural elements. These are critical choices for abiotic dissolution testing, as are binder removal and the rate of the flow that removes ions during testing. Therefore, we experimentally demonstrated how fluid composition and binder affect abiotic dissolution of a representative stone wool MMVF. We compared six simulant fluids (all pH 4.5, reflecting the environment of alveolar macrophage lysosomes) that differed in organic acids, which have a critical role in their ability to modulate the formation of Si-rich gels on the fiber surfaces. Removing the binder accelerates the average dissolution rate by +104% (max. + 273%) across the fluids by suppression of gel formation. Apart from the high-citrate fluid that predicted a 10-fold faster dissolution than is observed in vivo, none of the five other fluids resulted in dissolution rates above 400 ng/cm 2 /h, the limit associated with the exoneration from classification for carcinogenicity in the literature. These findings were confirmed with and without binder. For corroboration, five more stone wool MMVFs were assessed with and without binder in one specific fluid. Again, the presence of the binder caused gel formation and reduced dissolution rates. To enhance the reliability and robustness of abiotic predictions of biodurability, we recommend replacing the critically influential citric acid in pH 4.5 fluids with other organic acids. Also, future studies should consider structural transformations of the fibers, including changes in fiber length, fiber composition, and reprecipitation of gel layers.

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