Si Electrodes for Li-Ion Batteries—A New Way to Look at an Old Problem

Abstract

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 3.75mol3.75mol of Li reacting with 1mol1mol 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 (<33wt%)((33–56wt%)(33–56wt%) cycle at large capacities (∼660mAh∕g)(∼660mAh∕g) for hundreds of cycles. No special electrode processing or cycling procedures are required to achieve high capacities with good cyclability.