Electrochemical Performance of Si Modified TiO2 Nanotube Arrays Investigated in Li-Ion Containing Ionic Liquid Electrolyte
This paper will discuss recent results from the author's labs on the application of TiO2nanotube arrays as templates for magnetron sputtering of Si. Tuning of the deposition parameters (power and time) allowed obtaining a specific particulate Si morphology with sufficient free space, suitable for application as anode material in Li ion batteries (Fig.1).
Fig1. Scanning electron microscopy (SEM) image of the Si-modified TiO2 nanotube layer.
The electrochemical performance of the Si containing structures elucidates the importance of the Si surface morphology for the cycling stability of the anodes. The structures deposited at 50 W are favorable for Si stabilization during electrochemical cycling in Li ion electrolyte.
The nanostructured Ti/TiO2layers were electrochemically tested for Li-ion exchange in 1-butyl-1-methylpyrrolidinium bis (trifluoromethyl) sulfonylimide ([BMP][TFSI]) containing 1M Li[TFSI]. The results show that the ionic liquid [BMP][TFSI] is a promising electrolyte for batteries with silicon anodes.
The substrate type significantly influences the long term galvanostatic cycling of the samples. It was found that the structures deposited at 50 W on amorphous TiO2 exhibit a superior constant current cycling, finishing the 200th galvanostatic cycle with discharge capacity value of 1150 mAh g-1, with a tendency for further stabilization of the cycling. The good electrochemical performance of this sample type was attributed to the specific morphology of the Si deposit and structural stability of the amorphous TiO2 nanotubes.
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