The launch of full electric vehicles to the market requires a significant increase of energy densities of
lithium ion batteries to enhance the range of these vehicles. Therefore it is necessary to improve
batteries particularly in the fields of electrodes and electrolytes. The use of nanostructured anodes
thereby turned out as a promising option.
This work focused on the electrochemical synthesis of nanostructures made of relevant anode
materials using ionic liquids. At first lithium was deposited in an ionic liquid, 1-butyl-1-
methylpyrrolidinum bis(trifluoromethylsulfonyl)imide ([Py1,4] TFSI), with LiTFSI within different
templates. For the preparation of macroporous structures lithium was deposited inside a matrix of
colloidal polystyrene spheres and the deposition inside the pores of a polycarbonate membrane
induced the formation of nanotubes. The polystyrene templates for the deposition were prepared by
applying several layers of polystyrene spheres on a copper plate. For the directed growth of lithium
nanotubes membranes with a porediameter of ~200 nm were used. The dimensions were thus given by
the pores of the polycarbonate membrane. After a deposition time of 15 minutes solely nanotubes
occurred which were evenly distributed over the whole electrode surface and partly free standing.
Furthermore, this work focussed on the synthesis of silicon nanowires. For this purpose silicon was
deposited inside the ~90 nm wide pores a polycarbonate membrane. The electrochemical deposition
was done from [P1,4] TFSI with SiCl4 as silicon source. By the use of potentiostatic deposition of
silicon comparatively short nanowires of only 500 nm were formed, whereas pulsed deposition
produced significantly longer nanowires of up to 2.5 μm. Additionally, experiments with SiBr4 as
silicon source were carried out, since it has around ambient temperature a significantly lower vapour
pressure than SiCl4.
The same process as described for the silicon nanowires was used to form germanium nanotubes.
Furthermore, it was shown that germanium nanotubes could also be prepared by using a membrane
with the smaller pore diameter (90 nm)
