Recycling of solar cells recovered from waste panels into efficient silicon-based composite electrodes for energy-storage applications

Abstract

The significant increase in the cumulative installation capacity of solar photovoltaic modules as a source of renewable energy has led to a tremendous increase in the volume of end-of-life (EoL) solar modules, creating an essential requirement for sustainable waste management. In this work, an eco-friendly and less toxic recycling process has been developed to recover silicon and native silica (SiO₂) from discarded crystalline silicon solar cells for their use as functional electrode materials for different faradaic energy storage applications. The recovered materials were chemically treated and employed to fabricate slurry-coated electrodes over copper foil. This recovered silicon was also deposited over various substrates, including indium tin oxide (ITO)-coated glass and graphite sheets, to examine how the substrates affect the overall charge-storage reaction mechanism. The recycled material was structurally characterized using XPS, XRD, XRF and Raman spectroscopy, whereas morphological properties were analysed by employing TEM, SEM, EDAX and AFM. Thermal analysis was carried out using TGA to evaluate the thermal stability and compositional changes of the recycled silicon powder. The surface properties were also analysed using BET to determine the surface area and porosity of the powder. Electrochemical characterizations, including CV, EIS and GCD, were also performed on the prepared electrodes. This study presents an eco-friendly solution by integrating recycled photovoltaic waste into electrode materials for use in Li-ion electrochemical systems, with an emphasis on substrate-dependent faradaic charge storage behaviour. It further highlights substrate-dependent charge storage with electrodes formed on ITO and graphite sheets showing different charge-storage characteristics. The prepared electrodes over Cu foils, ITO and graphite sheets exhibited specific capacitance values of 143.23 Fg⁻¹, 30.53 Fg⁻¹ and 163.92 Fg⁻¹, respectively.