Upcycling of waste photovoltaic silicon: Co-MOF derived coating layer enhanced lithium storage

Abstract

Large amounts of silicon waste (W-Si) powders or ingots from the photovoltaic (PV) industry can be recycled as the improved raw negative electrode material in Lithium-ion batteries. Herein, Co-MOFs (ZIF-67) is produced in the form of small particles which turns into the uniform coating layer on the surface of micro-sized W-Si by solvent evaporation, and then ZIF-67 is carbonized to form nitrogen-doped carbon (NC) layer and carbon nanotubes (CNTs). Finally, W-Si/NC/Co/CNTs composites are formed. The continuous and uniform NC layer and CNTs formed by the catalyzation of Co on the surface of the silicon particles can inhibit the volume expansion of silicon during the charge and discharge process, showing the reversible discharge capacity of 1039 mAh g−1 after 100 cycles. The rate performance is also improved due to the high conductivity composite structure. This work can provide a choice for the composite of MOF and micro-silicon, and the meaning guidance for the application of silicon waste from PV industry.