Study of Nano-porous Si/Graphite/C Composite Anode Materials for Li-ion Batteries

The nano-porous Si/graphite composite was prepared via two-step ball-milling followed by etching process. Then carbon coating was introduced to obtain nano-porous Si/graphite/C. The microstructure of the nano-porous silicon material was characterized by SEM and TEM. The results from electrochemical test reveal that nano-porous Si/graphite/C composite exhibits much better cycle performance than nanosized Si/graphite/C composite. On the other hand, it is found that influence of composition, carbon precursor, binder type and content on the electrode performance is remarkable. The nano-porous Si/graphite/C composite electrode containing LA132 binder (10wt%) exhibits a reversible capacity of 649.9 mAh·g-1 after 200 cycles, with almost no capacity loss. The superior electrochemical characteristics are attributed to suppression of the volume expansion for lithium insertion via nanosized pores in Si particles, and the volume-buffering action as well as excellent electronic and ionic conductivity of carbon materials.