Access Type

Open Access Dissertation

Date of Award

January 2013

Degree Type


Degree Name



Materials Engineering

First Advisor

Simon Ng

Second Advisor

Steven Salley


The ever evolving technological applications such as with portable electronics and electric vehicles have led to increasing energy demands that have proven the existing commercial LIB capacity insufficient. Recently, the most promising anode material to substitute the traditional graphite is Si. As an anode Si has low discharge potential and theoretical the highest known theoretical capacity (>10 fold of graphite). However, due to the increased accommodated Li+ during charge-discharge reactions, silicon's volume varies up to 400%, causing pulverization and loss of electrical contact.

This dissertation focuses on a systematic approach in developing effective means to utilize Si for improved battery cycle life performance. We pair Si with a state-of-the-art material, graphene, to form a standalone Si nanoparticle/graphene composite anode and implement the electrode design improvements via (1) optimized particle dispersion, (2) modifications of graphene and C coatings; and (3) the use of a conversion active material in the form of SiNx. Imaging, spectroscopy and electrochemical characterizations are highlighted. These strategies contribute to the elucidation of the underlying electrochemical mechanisms pertaining to the N-doping effect, Si alloying and conversion reactions. With the resulting balance of enhanced capacity and improved cyclability, this study advances the development of Si-based composite anodes and its charge towards commercialization.