Formation of Heterostructured Silicon Thick Films in Atmospheric-Pressure Very High-Frequency Plasma for Possible Application to Lithium Ion Battery Anode

The superiority of silicon (Si) film performance as anode material in the rechargeable battery technologies is tormented by the huge volume expansion during cycle. The combined structure of a microcrystalline Si with high porous/defect density and an isotropic amorphous Si has been proposed as a feasible solution. Our own deposition process using atmospheric-pressure (AP) plasma excited by very high-frequency (VHF) power has managed to create a non-composite Si film with gradient phase along thickness direction. It is highly indicated that a slower gas flow rate and/or a larger power input cause the nanoparticle formation in the AP-VHF plasma to occur more actively, which significantly influenced the development of a crystalline layer with a high density of grain boundaries. A good film reproducibility on Cu substrate imply an interesting possibility of heterostructured Si application for LIBs anode.