(73n) An Efficient Anode for Lithium Ion Battery: Inverse Silicon Opal Prepared By Magnesium Thermal Reduction of SiO2

Lithium ion batteries (LIBs) with high power performance and energy density are required for the substantial market growth in renewable energy storage and EV applications. Unfortunately, poor characteristics of commercial graphite; low theoretical capacity and poor rate capability, make it difficult to apply to high performance LIB anodes.

Several researches have reported transition metal oxides and alloys materials as high performance materials. Silicon has received much attention by its highly reversible capacity with lithium ions (4200 mAh g⁻¹). A crucial drawback of silicon, however, is to undergo huge volume change ( > 300%), leading to mechanical stress of the electrode and pulverization of the particles during the alloying/dealloying with lithium ions. As a result, the rapid capacity fading occurs during cycling process. Many approaches have been studied to prevent the volume changes of silicon.

In recent years, the porous Si-based anode materials have attracted attention to avoid the common problems of Si powders such as volume expansion, electrically disconnected smaller particles and application. Especially, macroporous nano-materials prepared in the form of inverse-opal films were provided a number of advantages when used as anode/cathode active materials for LIBs. First, macroporosity can accommodate the volume change during the cycling process, resulting in maintaining the structure of electrode without collapse. Second, electrolyte and lithium ion can be easily penetrated and moved in the macroporos, leading to the improvement of rate capability and the decrease in the polarization.

 In this work, an inverse opal structured-silicon will be fabricated by a magnesium reduction method. The inverse opal structure will be observed through X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). To evaluate the electrochemical characterization of the inverse opal structured-silicon, we will conduct coin-half cell tests including several electrochemical tests such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy.