Surface Modification of Silicon-Based Alloy Materials for Lithium-Ion Battery Applications

Lithium-ion batteries have been considered as a promising power source for electric vehicles and energy storage systems, due to their high energy density and long cycle life.  In order to further increase the energy densities of lithium-ion batteries, it is essential to improve the specific capacity of active electrode materials.  It has been well known that the silicon-based anode materials have an extremely high theoretical capacity.  However, the main problem of silicon-based anode materials is high volume expansion during cycling, which leads to the loss of electrical contacts and poor capacity retention.  To solve these issues, many studies have been carried out in terms of thin film, nanostructure, alloy and composites. The capacity fading is known to be closely related to the interfacial instability of the Si-based electrodes.  In this study, we report synthesis and electrochemical characterization of Si-based alloy materials for high energy density lithium-ion batteries.  Furthermore, we modified their surface to form stable interfacial layer and obtain good capacity retention.  Their interfacial studies and cycling performances are investigated by electrochemical impedance spectroscopy, XPS, FE-SEM, HR-TEM and galvanostatic cycling test.