Summer 2012 Intern Project- Benjamin Abrams
PREPARATION OF SILICON CONTAINING ANODE MATERIALS FOR LITHIUM-ION BATTERIES
UC Santa Barbara
Mentor: Ferenc Somodi
Faculty Advisor: Dan Morse
Department: Molecular, Cellular, and Developmental Biology
Silicon based anodes for lithium ion batteries have become a critical area of research, as silicon offers extremely high capacity, but deteriorates quickly due to large volume changes during charge cycling. We have explored three methods of synthesis for novel composites of carbon and silicon nanoparticles, to maximize capacity while achieving good cycle life. In our first method, silica (SiO2) and hydrosilica (HSiO1.5 ) nanoparticles were prepared on a polyvinyl alcohol (PVA) modified graphite surface using catalytic vapor diffusion. These materials were further reduced at high temperature in H2/N2 atmosphere, in order to prepare SiOx and Si@SiO2 nanoparticles, respectively. Secondly, mesoporous hydrosilica (m-HSiO1.5) was synthesized. The high temperature reductive treatment of this material results in not only the formation of a conductive carbon layer on the walls of the mesopores, due to the decomposition of the structure directing agent, but also the formation of silicon nanocrystals in the walls. Finally, magnesiothermic reduction of Stöber silica spheres to silicon and their use as electrode material was also investigated. Preliminary results were gathered via X-Ray Diffraction, Scanning Electron Microscopy and Infrared and Raman Spectroscopy.