Electrolyte salts lithium halides

Lithium Iodide. Lithium iodide [10377-51 -2/, Lil, is the most difficult lithium halide to prepare and has few appHcations. Aqueous solutions of the salt can be prepared by carehil neutralization of hydroiodic acid with lithium carbonate or lithium hydroxide. Concentration of the aqueous solution leads successively to the trihydrate [7790-22-9] dihydrate [17023-25-5] and monohydrate [17023-24 ] which melt congmendy at 75, 79, and 130°C, respectively. The anhydrous salt can be obtained by carehil removal of water under vacuum, but because of the strong tendency to oxidize and eliminate iodine which occurs on heating the salt ia air, it is often prepared from reactions of lithium metal or lithium hydride with iodine ia organic solvents. The salt is extremely soluble ia water (62.6 wt % at 25°C) (59) and the solutions have extremely low vapor pressures (60). Lithium iodide is used as an electrolyte ia selected lithium battery appHcations, where it is formed in situ from reaction of lithium metal with iodine. It can also be a component of low melting molten salts and as a catalyst ia aldol condensations. 

Lithium dicyano- 1,2,3-triazolate was reported as a useful electrolyte (38) [45]. 1-Butyl-3-methylimidazoliiun 3,5-dinitro-l,2,4-triazolate (39) (Fig. 2) (m.p. 32 °C, rmaterial Some novel ionic liquids made up of azolium cations and anions were also reported. These salts are 1-ethyl-3-methyUmidazohum 1,2,4-triazolate (40) (Tg - 76 °C, T 207 °C, 7] 60.2 cP at 25 "C) and tetrazolate (41) (Tg -89°C, t] 42.5 cP at 25 °C) (Fig. 2). Both 40 and 41 were prepared by the coupUng reactions of 1-ethyl-3-methylimidazolium hydroxide with triazole or tetrazole, respectively [50]. 

Because the process is associated with the breakdown of an oxide barrier layer at the anode, it requires usually impressively high voltage (30-200 V). The products of electrochemical synthesis are always contaminated with halides and, for early transition elements, also with bimetallic alkoxides with Li when lithium salts are used as electrolytes. It means that the products after separation need to be purified by additional recrystallization or distillation. High-yield electrochemical synthesis has been proved to be an attractive approach to such precursors as Nb(OMe)s [96], Ta(OMe)s [104], MoO(OMe)4 [117], WO(OMe)4 [117], Mo (OMe)6 and W(OMe)6 [118], and Re406(0Me)12 [60]. 

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