Structual and Electrochemical Effects of Sn Addition on Si-Based Alloy Anod for Lithium Ion Batteries

Various portable electronic devices are wildly used in the world due to the remarkable progress of information technology since 2000. It leads to the increasing demand for rechargeable batteries. As a result, Lithium Ion batteries (LIB) are intensively investigated by many researchers. Currently graphite-based anode materials have widely used. In order to extend to rapidly increasing demand and wider applications as electric vehicles, we have to develop a new anode material. Si-based alloy anode material is one of the strongest candidates because it has many advantageous properties such as high capacity, high safety, good electrochemical stability, and low production cost. M. Kim. et al.[1] has developed a good Si-base alloy anode material and they reported the structural and electrochemical properties[1]. The Si-base alloy is consisted of finely dispersed active silicon crystals and surrounding inactive metal matrix. The main role of inactive-matrix in Si-based alloy is suppressing the volume change and it helps the Si-based alloy maintain good cycle performance. In this study, in order to enhance the cycle performance, we have added Sn metal which has theoretical capacity of 972mAh/g. Si and Sn nanocrystallites embedded in Si-Ti-Fe matrix were developed using arc melting followed by a rapid quenching method which could produce a large scale at one time. To identify the reaction mechanism, the ex-situ XRD, SEM, TEM, analyses were employed. Si and Sn nanocrystallites of approximately 100nm were dispersed in matrix composed of Si2TiFe. Consequently the Si/Sn/Si2TiFe composite showed a good cycle performance with 1000mAh/g over 50 cycles. [1]Journal of electroanalytical Chemistry 687 (2012)84-88