Surface Modified Silicon Electrode for Li-ion Batteries

Abstract

Nowadays, energy storage and retrieve system are important issues to solve energy problems. There are many energy storage systems such as Pb-acid, Ni-Cd, Li-S and Li-ion batteries. Among them, Li-ion battery is one of the most viable candidates for energy storage due to its high energy and high power density. At present, conventional Li-ion batteries employ a carbonaceous material for anode material. But, it is not suitable for the new large unit applications due to due to its low specific capacity and poor rate capability. For this reason, it is necessary to develop advance anode materials for Li-ion batteries. To overcome the limitations of carbonaceous materials, many researchers are paying attention to find other candidates replacing the graphite. Most of all, Si based systems are definitely attractive candidate for replacing the carbonaceous electrode due to the large theoretical specific capacity at room temperature (Li15Si4 : 3600 mAh g-1) and low operating voltage (near 0.1 V vs. Li/Li+). However, in general, most Si based electrodes suffer from a large volume change during cycling and have a poor rate capability. The stress induced by a large volume change during the cycling cause pulverization of Si which leads to loss of electrical contact with current collector and formation of solid electrolyte interphase (SEI) layer on the electrode surface repetitively. In this work, conducting carbon and SnO2 were coated on Si nanoparticles for enhance the electrochemical properties of Si electrode, respectively. Conformal conducting carbon is one of the most famous coating material for enhance the electrochemical properties of electrode, and SnO2 is a one of the promising candidate as anode materials for Li-ion batteries due to its excellent electrochemical performance. By combining those materials with Si, respectively, Si based electrode can be utilized fully in the anodes of Li-ion batteries. As a result of electrochemical test, each electrodes showed excellent electrochemical behaviors. And also reaction mechanism of each electrodes was confirmed by various analyses. These core-shell nanostructured electrodes could be a strong candidate as an anode materials for Li-ion batteries.