Homogenization-Enabled Fabrication of Silicon/Carbon Anodes from Photovoltaic Wire-Cutting Silicon Waste

Abstract

The rise of the photovoltaic (PV) industry has made it increasingly important to address the environmentally and economically effective treatment of wire-cutting silicon waste powder. To tackle this issue and utilize the high-purity waste silicon, this paper presents a scalable fabrication of silicon/carbon anodes through a homogenization process. This process aims to alleviate the tendency of nanoparticles to aggregate, and further achieves good distribution. The high-pressure homogenization process lies in its ability to efficiently disperse carbon nanotube (CNT) agglomerations, significantly improve the homogeneous distribution of CNTs and nano-silicon in the carbon matrix, build up an integrated conductive framework, and avoid agglomeration of nano-silicon. Accordingly, great improvements have been achieved in the electrochemical response of this hybrid electrode. Even after 500 cycles, the prepared Si/CNTs/C anode keeps a stable reversible capacity at 490.1 mAh g⁻¹, indicating its outstanding cycling stability. Furthermore, to prepare full cells, a pre-lithiated Si/CNTs/C composite served as the anode, while commercial NCM622 served as the cathode. The full cell maintained a capacity of 101.1 mAh g⁻¹ after 50 cycles, corresponding to a capacity retention of 96.1%. This research develops a new scalable synthetic technique to reutilize silicon powder discarded in solar PV wire cutting, indicating that silicon waste from photovoltaics may emerge as a crucial resource when manufacturing lithium-ion batteries in the future.