Recycling Silicon Photovoltaic Cells into Silicon Anodes for Li-ion Batteries Using 3D Printing and an Open Source Toolchain

Abstract

With the increasing adoption of solar energy, the disposal of end-of-life photovoltaic (PV) modules has become a growing environmental concern. The crystalline silicon embedded in these modules offers significant potential as a high-capacity anode material for lithium-ion batteries. This thesis addresses the central research question of how waste silicon solar cells can be upcycled into anodes for lithium-ion batteries using an open-source, low-cost, and scalable manufacturing toolchain. The aim is to develop a sustainable pathway that integrates Open-source hardware and additive manufacturing to create battery anodes from discarded materials. To investigate this question, an Open-source toolchain was designed and validated, including an AC/off-grid photovoltaic-powered ball mill, an Open-source scientific bottle roller, and an Open-source inert-gas glove box. Silicon recovered from waste PV cells was incorporated into photocurable resin formulations and 3D printed into electrode geometries using stereolithography (SLA) technology. The printed structures were pyrolyzed to convert the polymer matrix into conductive carbon, and form silicon–carbon composite anodes. An investigation was conducted across four pyrolysis temperatures including 800, 1100, 1200, and 1400 °C, to determine their influence on structural evolution, carbon formation, and electrochemical behaviour. Among these, 1200 °C provided the optimal balance between suppressing electrochemically inactive SiC formation, enhancing carbon conductivity, and maintaining mechanical integrity. The corresponding anodes delivered 771 mAh g-1 with 61% capacity retention over 120 cycles. To further improve conductivity and mitigate silicon volume changes, carbon nanotubes (CNTs) synthesized from post-consumer plastic-waste pyrolysis were incorporated into the resin. The CNT-reinforced anodes showed enhanced electrochemical behavior and exhibited an initial discharge capacity of 862 mAh g⁻¹ with 98.88% initial Coulombic efficiency, which increased to 1,044 mAh g⁻¹ upon cycling due to improved silicon activation and electronic pathways. This thesis demonstrates that waste silicon PV cells can be transformed into functional Li-ion battery anodes through an accessible, open-source, and sustainable manufacturing approach. The results provide a proof of concept for decentralized battery fabrication, advance circular-economy strategies for PV and plastic waste and expand the role of additive manufacturing in energy-storage materials research.