Scalable and low-cost synthesis of porous silicon nanoparticles as high-performance lithium-ion battery anode

Abstract

We design porous silicon (Si) nanoparticles with both nanosize and porous structures via a simple alkaline etching method. The etching at grain boundaries and the anisotropic etching of the different crystal planes of the polycrystalline silicon are responsible for the homogeneous porous nanostructures. After the porous Si nanoparticles are coated with carbon layer, the composite delivering a discharge capacity of 1645.6 mAh g−1 at 0.4 A g−1 after 200 cycles, an outstanding discharge capacity of 861.5 mA g−1 at 4 A g−1 after 800 cycles with a high capacity retention of more than 65%, and a rate capacity of 904.7 mA g−1 at 12.8 A g−1. The porous nanoparticles show both the nanosize (∼100 nm) and the porous structure, which can furthest accommodate the large volume changes of the Si anode, resulting in the good electrochemical performance. The design of porous Si nanoparticles with a high yield of 93% may give a scalable, low-cost, and green approach for commercial silicon-based anodes of lithium-ion batteries.