Micro-Sized Bulk Porous Si from Fe-Si and Al-Si Alloys As High Performance Anodes for Li-Ion Batteries

Silicon has been perceived as one of the most promising anodes in the next generation lithium-ion batteries (LIBs) due to its superior theoretical capacity. However, bulk silicon experiences an enormous volume expansion during the lithiation/delithiation process, resulting in rapid capacity fading. And, its high-cost and low coulombic efficiency also present significant challenges for applications. We prepared micro-sized porous Si materials from the abundant and low-cost Fe–Si and Al-Si alloys via a facile process of ball-milling and acid etching. The method of the synthesis was simple, low-cost and industrially scalable. For example, The pure micro sized porous silicon anode from Fe-Si alloy showed a fantastic first-cycle coulombic efficiency of 88.1% and exhibited an excellent cycling stability of 1250 mA h g -1 at 500 mA g -1 after 100 charge/discharge cycles. An excellent rate capability was also demonstrated for the unique well-organized porous structure silicon Even at a high current density of 5 A g -1 , the excellent discharge capacity was 558 mA h g - 1. The unique well-organized micro sized porous structure could alleviate the volume change of the Si anode during the lithiation/delithiation process resulting in good long-term cycling stability. It is demonstrated that the low cost micro-sized porous Si material is very promising for scalable production of high-performance porous Si anode materials for high-energy lithium-ion batteries.