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

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.