Scalable synthesis of Si/SiO2@C composite from micro-silica particles for high performance lithium battery anodes

• Si/SiO2 composite is prepared directly from irregular micro-silica.
• Si/SiO2@C composite is prepared by using phenolic resin as a carbon precursor.
• The composite exhibited stable cycling properties and excellent rate capability.

Silicon/silica (Si/SiO2) composite is prepared directly from irregular micro-silica via mechanical milling followed by modified magnesiothermic reduction process. After that, phenolic resin is introduced as carbon source to fabricate the silicon/silica@carbon (Si/SiO2@C) composite. The structure of the composite is revealed by x-ray diffraction (XRD). SEM and TEM observations reveal that the micro-silica particles are broken into submicron scale and part of the silica particles are reduced to silicon by Mg reduction. When evaluated as an anode material for Li-ion batteries, the electrochemical performance of the composite is good. At 50 mA g− 1, the Si/SiO2@C (50 wt.% C) sample exhibits a high initial charge capacity of 685.8 mAh g− 1. After 100 cycles, it retains reversible capacity of 482 mAh g− 1. The composite also shows superior rate performance. At 500 mA g− 1, it can deliver high reversible capacity of 462.3 mAh g− 1. Considering the facile preparation and low-cost of raw material, the prepared Si/SiO2@C composite holds promise in practical Li-ion batteries.

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