Simultaneous perforation and doping of Si nanoparticles for Lithium ion battery anode.

Silicon nanostructures have served as promising building blocks for various applications, such as lithium ion battery, thermoelectrics and solar energy conversions. Particularly, controls of porosity and doping are critical for fine tuning the mechanical, optical and electrical properties of these silicon nanostructures. However, perforation and doping are usually separated processes, both of which are complicated and expensive. Here, we demonstrate that the porous nano-Si particles with controllable dopant can be massively produced through a facile and scalable method, combining ball milling and acid etching. Nano-Si with porosity as high as 45.8% can be achieved with 9 orders of magnitude of conductivity changes compared to intrinsic silicon. As an example of demonstration, the obtained nano-Si particles with 45.8% porosity and 3.7 at% doping can serve as a promising building blocks for lithium ion batteries with 1500 mA h/g retained over 940 deep cycles and excellent rate performance with 1600 mA h/g at the current density of 5 C.