As we all know, solar energy is playing a pivotal role in the ongoing energy transition (in 2022, solar power accounted for more 7.6 % of total electricity production in EU) and the solar panel market is experiencing a remarkable growth. The several early installed PV panels are now beginning to reach their EoL stage. Consequently, establishing strategies for PV panels waste management and recycling is a urgent need to anticipate the forthcoming environmental. The EU commission has implemented the 2012/19/EU directive, which mandates the recycling of at least 80 % of the EoL PV panels. In this context, this ecological crisis can be transformed into a significant opportunity through a sustainable recovery of precious element such as aluminium (Al), silver (Ag), copper (Cu), and particularly solar–grade silicon (Si) metal, leading to economic and environmental benefits.
In this study, through rational process design approach, we have successfully developed a pilot-scale process production (> 1 kg) of Si/C composite using Si sourced from EoL photovoltaic panels as high-efficiency anode active material. The process began with the purification of Si fragments obtained from EoL PV solar cells through leaching methods. Next, the pure Si was processed through two milling steps (dry and wet) to produce nano-sized primary particles of Si. The optimized Si-based suspension was then modified by incorporating carbon nanotubes (CNTs) and polymer binder before being injected into a pilot spray-dryer machine. The final Si/C composite material was obtained after a heat treatment. Multiple batches were produced, and all the structural characterizations were consistent, demonstrating a stable and optimized process suitable for producing Si/C composite material at the pilot–scale (> 1 kg).
The electrochemical performance of the half–cells demonstrate remarkable cycling stability with an average CE exceeding 99 % over 1200 cycles upon controlled capacity and an average 1800 mAh/g over 280 cycles without capacity limitation. The C rate performance tests were conducted to assess the stability of our composite and to evaluate the impact of Si particles volume variation at high cycling rates. The capacities remained consistent from 0.1C to 0.5C, but exhibited a gradual decline at higher rates due to the low Li+ diffusion kinetics. Notably, the restoration of performance at low current densities highlights the good structural stability of the composite upon charge and discharge cycling.