[Nature]LITHIUM-ION BATTERIES: Simply silicon
The use of silicon nanomaterials in anodes of rechargeable lithium-ion batteries has resulted in a keen interest in the development of new synthetic routes to these materials. Now, Ning Lin et al. report the preparation of polycrystalline nanosized silicon from the reduction of SiCl4 in the presence of metallic Mg and AlCl3 at 200 °C inside a stainless steel autoclave. The resultant nanoparticles are shown to have a high reversible capacity of 3,083 mAh g−1 at 1.2 A g−1 after 50 cycles when used as anode materials and good long-term cycling stability. The researchers investigate the mechanism of the reduction reaction and reveal that the molten salt AlCl3 is reduced by metallic Mg to form metallic Al, which then proceeds to reduce SiCl4 to Si. The silicon nanoparticles range in size from several tens of nanometres to about 100 nm. Furthermore, the method is high yielding (over 80%) and uses relatively mild reaction conditions.
