A stable nanoporous silicon anode prepared by modified magnesiothermic reactions

Porous silicon prepared by low-cost and scalable magnesiothermic reactions is a promising anode material for Li-ion batteries; yet, retaining good cycling stability for such materials in electrodes of practical loading remains a challenge. Here, we engineered the nanoporous silicon from a modified magnesiothermic reaction by controlled surface oxidization forming a <5 nm oxide layer on the 10-20 nm Si nanocrystallites. High loading electrodes of similar to 3 mAh/cm(2) demonstrates stable cycling with similar to 80% capacity retention over 150 cycles. The specific discharge capacity based on the total electrode weight is similar to 1000 mAh/g at the lithiation/delithiation current density of 0.5/0.75 nnA/cm(2). This work reveals the importance of the surface treatment on nanostructured Si, which will lead to a well-controlled ratio of silicon and surface oxide layer and provide guidance on further improvement on silicon-based anode materials. (C) 2015 Elsevier Ltd. All rights reserved.