Nanocomposites and nanomaterials
Lithium Ion Batteries and Supercapacitors with high energy density using electrodes from Silicon/ Graphene Nanocomposites
Khomenko V. G.
Department of electrochemical power engineering & chemistry, Kyiv National University of Technologies and Design, Nemyrovycha-Danchenka St 2,, Kyiv- 01011, Ukraine.
E-mail: v.khomenko@i.ua

The nanomaterial based on silicon has recently received great attention. Silicon has been intensively investigated as an anode material for lithium-ion batteries (LIBs) due to their high specific capacity. Today, silicon is one of the most attractive anode materials for next generation LIBs. However, the huge volume change during alloying with lithium leads to poor cycle life. Usually, the conductive carbon is needed to provide the acceptable electrochemical performance of silicon-based anode. However, the traditional carbon percolators could not overcome the pulverization and unstable Solid Electrolyte Interphase (SEI) layer during long-term cycling.  
In the current work, various methods were investigated for improving the silicon-based anode performance, including those of nanostructuring, alloying, forming hierarchic structures based on graphene, and using suitable binders. Different fabrication methods have been studied to synthesize Silicon/Graphene nanocomposites with stable characteristics.
In this research, we present a binder-free approach to forming electrodes. Graphene and silicon-based films on current collector were obtained by Plasma Enhanced Chemical Vapor Deposition (PECVD). Electrodes with the flexible and mechanically strong film of nanomaterials were prepared by Roll to Roll (R2R) processing technology. The fabrication method is simple and scalable, providing new avenues for development of power sources with high energy density. 
Our investigation shows that graphene plays a key enabling role in Si/Graphene anodes for LIBs and advanced power sources such as a lithium-ion capacitor (LIC). LIC contains a negative electrode, which is similar to LIB anode, and a positive electrode, which is similar to a supercapacitor. Employing anode from LIB and electrode from supercapacitors together in a single system would benefit both high energy and power density. Designed LIBs and LIC based on nanomaterials exhibit great potential for high-performance energy sources.

Acknowledgment
 The author would like to thank IZOVAC Technologies Ltd. for supplying a sample of advanced electrode materials.