Mesoporous silicon engineered by the reduction of biosilica from rice husk as a high-performance anode for lithium-ion batteries

In this work we demonstrate a scalable synthetic approach for the transformation of rice husk, a cheap source of biosilica, into highly valuable porous silicon using a magnesiothermic reaction. The synthesized porous silicon with a high porosity (0.62 cm3 g−1) and a large specific surface area (150.1 m2 g−1) is a promising material for lithium-ion battery applications. As an anode material, the porous silicon can retain a considerably high reversible capacity of 1220.2 mA h g−1 at a specific discharge–charge current of 1000 mA g−1 after 100 cycles. The approach is generic and can be applied to other sources of biogenic silica to obtain high-performance and highly valuable porous Si for many applications.