Journal of Applied Electrochemistry, Vol.44, No.2, 245-253, 2014
Properties of Li4Ti5O12 as an anode material in non-flammable electrolytes
Two non-flammable electrolytes 1 M LiPF6 in sulfolane (TMS) + 5 wt% VC and 0.7 M lithium bis(trifluoromethanesulphonyl)imide (LiNTf2) in N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulphonyl)imide (MePrPyrNTf(2)) + 10 wt% gamma-butyrolactone (GBL) were tested with Li4Ti5O12 (LTO) as highly promising anode material for application in lithium-ion batteries. The results were compared for the titanium anode in the classic electrolyte: 1 M LiPF6 in propylene carbonate + dimethyl carbonate (PC + DMC, 1:1). The performances of LTO/electrolyte/Li cell were tested using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge and scanning electron microscopy (SEM). SEM images of electrodes and those taken after electrochemical cycling showed changes which may be interpreted as a result of solid-state interface formation. Good charge/discharge capacities and low capacity loss at medium C rates preliminary cycling was obtained for the Li4Ti5O12 anode. For LTO/1 M LiPF6 in PC + DMC/Li system, the best capacity was obtained at C/10 and C/3 (145 and 154 mAh g(-1), respectively). In the case of a system working on the basis of a TMS solution (1 M LiPF6 in TMS + 5 wt% VC) the best value was obtained at a C/5 current and an average of more than 150 mAh g(-1) (86 % of theoretical capacity). For the 0.7 M LiNTf2 in MePrPyrNTf(2) + 10 wt% GBL electrolyte, the highest capacitance value (at C/20 current) of about 150 mAh g(-1) was observed. The 1 M LiPF6 in TMS + 5 wt% VC and 0.7 M LiNTf2 in MePrPyrNTf(2) + 10 wt% GBL electrolytes had a relatively broad thermal stability range and no decomposition peak was observed below 150 degrees C.
Keywords:Sulfolane;N-Methyl-N-propylpyrrolidinium bis(trifluoromethanesulphonyl) imide;Li4Ti5O12/Li batteries