Recycling of silicon used in solar cells to prepare silicon-carbon composite powders as anode material in li-ion batteries

Currently, silicon (Si) coming from the recycling of solar cells is a non-valued fraction. The principal aim of this work is the development of silicon recovered during the dismantling of solar panels as an electrode material for lithium or sodium batteries. The main technological challenge associated with the use of silicon in this type of application is to control the volume expansion during charge/discharge cycles. This problem could be solved through the synthesis of Silicon/carbon composites in which the size of the silicon particles and their dispersion must be controlled [1–4].
We develop a carbon matrix consisting of graphene or carbon nanotubes (CNT) that allow the incorporation of silicon particles coated with a carbon layer (Si@C/C). The process is divided in two main steps. In the first step, Si wafer pieces are ground to prepare Si powder and then a mixed suspension of Si and an organic carbon source (Acetic acid, Ascorbic acid or Lactose) is spray-dried followed by heat treatment to generate the coverage of silicon particles with carbon (Si@C). In the second step, aqueous suspension of Si@C and graphene/CNT is spray dried and heat treated to obtain the final composite structure.
The morphology of composite materials is analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Electrochemical performance of Si@C/C composites are characterized by galvanostatic charge-discharge cycling and electrochemical impedance spectroscopy (EIS).