Si electrodes for li-ion batteries - A new way to look at an old problem

High-capacity Si-based electrodes could replace carbon-based electrodes in the next generation of Li-ion batteries. Although Si-based electrodes have large gravimetric capacities, they typically suffer from poor cyclability. One reason for the poor cyclability is large volume expansion associated with 3.75 mol of Li reacting with 1 mol of Si. A theoretical approach to design electrodes that can accommodate this large volume expansion is discussed. It is shown that experimental results agree well with the theoretical approach. We show that Si-based electrodes with a relatively low Si content (< 33 wt %) and high binder content (33-56 wt %) cycle at large capacities (similar to 660 mAh/g) for hundreds of cycles. No special electrode processing or cycling procedures are required to achieve high capacities with good cyclability. (c) 2007 The Electrochemical Society.