Revisit of metallothermic reduction for macroporous Si: compromise between capacity and volume expansion for practical Li-ion battery

Abstract

We revisit the metallothermic reduction process to synthesize shape-preserving macro-/nanoporous Si particles via aluminothermic and subsequent magnesiotheric reaction of porous silica particles. This process enables us to control the specific capacity and volume expansion of shape-preserving porous Si-based anodes. Two step metallothermic reactions have several advantages including a successful synthesis of shape-preserving Si particles, tunable specific capacity of as-synthesized Si anode, accommodation of a large volume change of Si by porous nature and alumina layers, and a scalable synthesis (hundreds of gram per batch). An optimized macroporous Si/Al2O3 composite anode exhibits a reversible capacity of ~1500mAhg−1 after 100 cycles at C/5 and a volume expansion of ~34% even after 100 cycles.