In-situ construction of porous Si@C composites with LiCl template to provide silicon anode expansion buffer

Abstract

Abstract Silicon-based anode material is one of the most promising alternative anodes for graphite due to its advantages of abundant reserves, environmental protection and high-energy-density. However, silicon still cannot be directly applied commercially as anode materials owing to the existences of huge volume change during the alloying and dealloying process. Herein, porous Si@C composites are prepared by employment of nano silicon as the active substance particles, lithium chloride as the template and pitch powder as the carbon precursor. Results of electrochemical performance tests show that the cell based on the in-situ prepared porous Si@C composites deliver a reversible good cycle stability. Besides, porous Si@C composites show a lower thickness expansion rate of electrode (15.38%), compared with pure nano silicon (162.46%) and conventional Si@C anodes (40.24%), respectively. It is believed that the improved performance is benefitted from the porous structure, which provides a buffer for the expansion of silicon, reduces the volume expansion of the electrode during the charge and discharge process, and thus inhibits the damage to the solid electrolyte interphase film outside the Si@C composites. This work provides an environmentally friendly method to prepare porous Si@C composite anode materials, which is suitable for large-scale preparation and industrialized production.