SILICON-BASED ANODE MATERIALS FOR LI-ION BATTERIES:

Silicon-based materials have recently emerged as a promising candidate for anodes in lithium-ion batteries because they exhibit a higher energy-storage capacity than the conventional graphite anode. Silicon (Si) has a theoretical lithium (Li) capacity of Li_4.4Si » 4200 mAh/g, which is more than ten times greater than that of graphite (372 mAh/g). Moreover, Si is safer, less expensive, and far more abundant than graphite. However, the practical use of Si as an anode material is hampered by its low intrinsic electrical conductivity and poor cycling performance. In particular, the volume changes up to 400 % during lithiation and delithiation can cause severe cracking and pulverization of the Si electrode and consequent capacity fading arising from the loss of electrical contacts. Considerable efforts have been made to overcome these problems, for instance, through structural modifications such as amorphous phases, nanoparticles, nanowires and alloying with active/inactive elements. In addition, first principles calculations have recently been applied to investigate fundamental aspects of the structural changes and lithiation behavior of Si-based materials, yet many of which still remain unclear. This project aims to identify new promising Si-based anode materials for Lithium ion batteries using systematic theoretical investigations as to atomic arrangements, phase stabilities, volume changes, and lithiation voltages.