Production of porous silicon from silicon wafer waste for Li-ion batteries via low load metal assisted catalytic etching

Silicon (Si) is recognized as a superior anode material in lithium-ion batteries (LIBs) compared with graphite, which is currently used. Despite the high theoretical capacity (3579 mAh g- 1) of Si, designing Si-based materials is challenging because of its large volume change (280%) during the charging and discharging processes.Mesoporous structured silicon (PSi) is a promising solution for overcoming the volume expansion issue of Si-based anodes. This study proposes the feasibility of using Si wafer waste to produce porous Si materials as anodes for LIBs. By varying the etching parameters, Si particles with various porosities and surface areas were produced and electrochemically tested. The sample with low porosity (28%) and low surface area (37 m2g-1) exhibited the best rate performance and cycling stability. In addition, this sample showed the highest initial Coulombic efficiency (ICE) value of 84% and exhibited stable cycling performance for 135 cycles at 0.2 C with a capacity limit of 500 mAh g-1. Furthermore, the PSi/graphite composites were prepared with Si contents ranging from 10 to 30 wt%. The composite with 30 wt% Si delivered a reversible capacity of 1053 mAh g-1 with an ICE of 88% and a capacity of 351 mAh g-1 after 100 cycles.