Effect of pelletizing and temperature in silicon production using magnesiothermic reduction

Abstract

Porous silicon (Si) has lots of potential applications including anode in lithium-ion batteries, sensor, electronic, or biomedical field. The synthesis of porous Si usually involves the use of expensive precursors with complex methods, having difficulties in the application to scalable process. It is urgent to find a massive production method for the production of porous Si using inexpensive and abundant source. Here, we show that the cheap and abundant rice husk silica (RH-SiO2) can be converted into porous Si via magnesiothermic reduction in a self-propagating high temperature synthesis (SHS) approach. The SHS method is a simple and commercial method by pelletizing the powder reactants. The Si yield and physical properties were investigated varying temperatures in a range from 600 to 900 degrees C and pelletizing pressure from 5 to 30 MPa in order to find the optimum process condition. The high temperature at 900 degrees C increased the Si yield avoiding the unwanted by-product such as Mg2SiO4. And the pellet sample under pelletizing pressure of 10 MPa showed an efficient heat/mass transfer by sustaining an optimum proximity between particles. The meso- and micro-structured Si was observed in SEM/EDX analysis and battery test shows performance of 171.7 mA h/g was retained after 150 cyclic tests.