Titanium dioxide/graphene oxide composite and its application as an anode material in non-flammable electrolyte based on ionic liquid and sulfolane

摘要

A composite of aminosilane-grafted TiO2 (TA) and graphene oxide (GO) was prepared via a hydrothermal process. The TiO2/graphene oxide-based (TA/GO) anode was investigated in an ionic liquid electrolyte (0.7 M lithium bis(trifluoromethanesulfonyl)imide (LiNTf2)) in ionic liquid (N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPPyrNTf(2))) at room temperature and in sulfolane (1 M lithium hexafluorophosphate (LiPF6) in tetramethylene sulfolane (TMS)). Scanning and transmission electron microscopy (SEM and TEM) observations of the anode materials suggested that the electrochemical intercalation/deintercalation process in the ionic liquid electrolyte with vinylene carbonate (VC) leads to small changes on the surface of TA/GO particles. The addition of VC to the electrolyte (0.7 M LiNTf2 in MPPyrNTf(2) + 10 wt.% VC) considerably increases the anode capacity. Electrodes were tested at different current regimes in the range 5-50 mA g(-1). The capacity of the anode, working at a low current regime of 5 mA g(-1), was ca. 245 mA g(-1), while a current of 50 mA g(-1) resulted in a capacity of 170 mA g(-1). The decrease in anode capacity with increasing current rate was interpreted as the result of kinetic limits of electrode operation. A much lower capacity was observed for the system TA/GOa",1 M LiPF6 in TMS + 10 wt.% VCa",Li.