Carbon-Assisted Technique to Modify the Surface of Recycled Silicon/Silicon Carbide Composite for Lithium-Ion Batteries

A green source of microsized silicon/silicon carbide (Si/SiC) composite represent the wastes of solar cell industries that are created during ingot cutting process; the composite can be used as a Si-based anode for lithium ion batteries. In contrast to Si nanoparticles with a particular morphology design, the microsized Si/SiC composite from the wastes show severe capacity degradation due to the formation of a solid electrolyte interface (SEI) that affects the conductivity and stability of the electrode. In this study, an external treatment of the electrode (a carbon-assisted technique (CAT)) was adopted to modify the surface of the electrode and compared with an internal treatment of electrode between particles (namely a pitch-wrapping technique (PWT)). The external and internal carbon treatments of the electrodes were analyzed individually by cyclic voltammetry and ac impedance spectroscopy. The electrochemical behavior reveals that the characteristic peak of SEI formation and the resistance of SEI of CAT was improved with more efficiency than PWT. Furthermore, based on the cycling performance and irreversibility, the charge retention of the microsized composite could be boosted. Therefore, CAT could replace PWT in the case of microsized Si particles. Conclusively, a method was developed to stabilize SEI formation, which could not only enhance the cyclability but also provide an alternative approach to solve the issue related to SEI formation of a Si-based anode.