Facile recycling of porous Si waste for stable Si/C anodes

As the rapid development of photovoltaic industry, vast of polycrystalline Si has been produced for photovoltaic products. Meanwhile, large amount of Si waste is generated from mechanical slicing process and retired electronic products. Reasonable recycling the Si waste can save resources and reduce environmental pollution. Herein, porous Si is prepared from Si waste by magnesium thermal reduction and then embedded in industry lignin alkali-based carbon matrix (LAC) via co-precipitation and sintering process to obtain Si/C composite anode for lithium-ion batteries. Owing to the encapsulation structure, the carbon matrix can alleviate the volumetric expansion of Si and improve electronic conductivity of composite, the obtained Si@LAC anode exhibits high charge capacity of 1017.5 mAh g −1 at 0.1 A g −1 and high capacity retention of 94.9 % at 0.5 A g −1 after 200 cycles. Furthermore, the Si@LAC composite displays superior rate performance with high capacity of 596.7 mAh g −1 at 2 A g −1 which is 61.5 % of the value at 0.2 A g −1. Such a high performance Si/C anode from facile preparation demonstrates a viable route to utilization of photovoltaic Si waste and industrial lignin.