Effect of Volume Fraction of Intermetallic Phases on the Electrochemical Properties of Si1-xTix Alloys for Anode Materials

J.J. Jeong, H.J. Kwon, D.Y. Jeong, W-W Park, K.Y. Sohn
Inje University, KR

Keywords: silicon alloys, melt spinning, lithium-ion battery, anode materials, titanium

Summary:

Secondary lithium batteries have been used as power sources for various applications including portable electronic equipment. Graphite, an anode material for lithium-ion batteries has limited specific energy capacity, which limits its application to electric vehicles. Silicon is an attractive anode material due to its high specific capacity of 4200(mAh/g). Unfortunately, Silicon-based secondary batteries have poor cycleability resulting from drastic volume expansion/contraction during Li+ insertion/extraction. It has been shown that silicon particles reinforced by an inactive or partially-active second phase represent improved cycle performance, especially when the size of silicon is in nanometer scale. The size of silicon particles can be reduced by a rapid solidification process. In this work, titanium is added to silicon to form an intermetallic second phase. The objective of this work is to investigate the effect of relative volume fraction of a Si-Ti second phase on the microstructures and electrochemical behavior of the rapidly solidified alloys. The cycle performance of Si-Ti alloys were significantly influenced by the relative volume fraction of Si2Ti phase. The electrochemical behavior of the Si-Ti alloys will be discussed in terms of microstructures and volume fraction of intermetallic phases.