An equimolar mixture of lithium bis-(trifluoromethanesulfonyl)amide (Li [TFSA]) and either triglyme (G3) or tetraglyme (G4) yielded stable molten complexes: [Li(G3)][TFSA] and [Li(G4)][TFSA]. These are known as solvate ionic liquids (SILs). Glyme-based SILs have thermal and electrochemical properties favorable for use as lithium-conducting electrolytes in lithium batteries. However, their intrinsically high viscosities and low ionic conductivities prevent practical application. Therefore, we diluted SILs with molecular solvents in order to enhance their ionic conductivities. To determine the stabilities of the complex cations in diluted SILs, their conductivity and viscosity, the self-diffusion coefficients, and Raman spectra were measured. [Li(G3)] + and [Li(G4)] + were stable in nonpolar solvents, that is, toluene, diethyl carbonate, and a hydrofluoroether (HFE); however, ligand exchange took place between glyme and solvent when polar solvents, that is, water and propylene carbonate, were used. In acetonitrile (AN) mixed solvent complex cations [Li(G3)(AN)] + and [Li(G4)(AN)] + were formed. [Li(G4)][TFSA] was more conductive than [Li(G3)][TFSA] when diluted with nonpolar solvents due to the greater ionic dissociativity in [Li(G4)][TFSA] mixtures. In view of the stability of the Li−glyme complex cations, the enhanced ionic conductivities, and the intrinsic electrochemical stabilities of the diluting solvents, [Li(G4)][TFSA] diluted by toluene or HFE, can be a candidate for an alternative battery electrolyte.

Highly concentrated, molten mixtures of lithium bis(trifluoromethanesulfonyl)amide (Li[TFSA]) and ether solvents (tetrahydrofuran (THF), monoglyme (G1), diglyme (G2), and triglyme (G3)) were investigated as electrolytes for Li batteries. To compare the electrochemical reactions in the electrolytes with different solvents, the ratio of ether–oxygen atoms and Li+ ([O]/[Li]) in the electrolytes was fixed at four. The capacity of a Li–LiCoO2 cell with [Li(THF)4][TFSA] dramatically decreased upon charge/discharge cycling, whereas [Li(G3)1][TFSA] allowed the cell to have a stable charge–discharge cycles and a Coulombic efficiency of greater than 99% over 100 cycles. Corrosion of the Al current collector of the cathode was also affected by the composition of the electrolytes. Persistent Al corrosion took place in [Li(THF)4][TFSA] and [Li(G1)2][TFSA], which contain shorter ethers, but the corrosion was effectively suppressed in [Li(G3)1][TFSA]. Furthermore, lithium polysulfides, which are formed as discharge intermediates at the sulfur cathode of the Li–S cell, were much less soluble in electrolytes with longer ethers. Therefore, a higher Coulombic efficiency and more stable cycle ability were achieved in Li–S cells with [Li(G3)1][TFSA]. All the electrochemical properties in the batteries were dominated by the presence or absence of uncoordinating solvents in the concentrated electrolytes. This paper demonstrates that the structural stability of [Li(glyme or THF) x ]+ cations in electrolytes plays an important role in the performance of Li batteries.

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OBJECTIVEGlycated albumin (GA) relative to A1C is a useful marker of short-term glycemic control. We investigated whether endogenous insulin secretion in type 2 diabetes has different effects on GA and A1C levels.RESEARCH DESIGN AND METHODSA1C, GA, and GA-to-A1C ratio were compared in 202 type 2 diabetic patients by type of treatment. Effect of β-cell function determined by homeostasis model assessment (HOMA-%β) on GA-to-A1C ratio was examined. In addition, GA-to-A1C ratio was compared between type 2 diabetic patients and 16 patients with type 1 diabetes.RESULTSIn type 2 diabetic patients, GA-to-A1C ratio was significantly higher in those treated with insulin than in those treated with diet or oral hypoglycemic agents. HOMA-%β showed a significant inverse correlation with GA-to-A1C ratio. This ratio was higher in type 1 diabetic patients than in type 2 diabetic patients.CONCLUSIONSIn diabetic patients with decreased insulin secretion, serum GA levels are higher relative to A1C.

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