A simple method to fabricate size and porosity tunable Si by Al–Si alloy as lithium ion battery anode material

Many research works demonstrate that an appropriate size and porosity of Si can effectively alleviate the problem of large volume change. Although there are many methods to tune the size and porosity of Si, high cost and complicated processes hinder them from a large-scale application. Here a simple method is developed by ball milling and acid etching Al–Si alloy ingots with high Si contents. The porosity and size distribution of the obtained porous Si (P–Si) can be tuned effectively by adjusting the Si content in the Al–Si alloy. As a result, with Si content of 50 wt% in the Al–Si alloy ingot, P–Si50 presents relatively small and uniform particle size distribution, and the largest pore volume. After carbon coated, the obtained P–Si50/C maintains a reversible capacity of 1226 mAh g−1 after 200 cycles at a 0.2C current density. The method might provide a significant scientific contribution to further understanding of P–Si synthesized by the Al–Si alloy and guidelines for structure optimization of the P–Si for advanced lithium ion battery applications.