Study on Effects of Titanium Silicide Coating onto Porous Silicon Nanospheres for Lithium Ion Battery Anodes

Abstract

Lithium ion batteries (LIBs) have been applied mainly in small-portable devices as power sources. However, the medium-large size battery sector such as electric vehicles (EVs) and energy storage system (ESS) have opened recently, and thus the demand for much higher power density, and low cost materials bas been increased.. Si is considered as one of the most promising anode material for LIBs, due to its high theoretical capacity, nontoxic, low cost and abundance. On the other hand, Si anode has intrinsic limitations such as severe volume change and low electrical conductivity, which leads to poor cycling and rate performances, which severely limits their applications. In this research, we present a facile synthesis of porous Si structure and enhancement of electrical conductivity via magnesiothermic reduction and TiSi2 coating layer, overcoming these limitations. Taking advantages of the porous structure and the high electrically conductive coating layer make this anode exhibit a significantly enhanced electrochemical performance in terms of cyclic, rate capability and charge transfer resistance. The TiSi2 is inactive toward lithium, which is negatively influenced in terms of specific capacity. Nevertheless, the TiSi2, which has good electrical conductivity and physical strength, not only enhance the conductivity but also maintain Si structure during cycling. This combination of porous structure via magnesiothermic reduction and highly conductive TiSi2 coating makes a synergistic effect of electrochemical performance. This novel synthesis is demonstrated as promising method for producing high capacity anode materials applicable in the next generation LIBs.