Repurposing end-of-life solar panels for energy storage devices

• Main Author: Tay, Yeow Boon
• Other Authors: Nripan Mathews
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/169520
• Institution: Nanyang Technological University

With the growing concern of global warming, many countries have opted for the use of renewable and clean energy. Among the renewable energy technologies, solar panels have been a popular choice as it can be installed conveniently with minimal restriction. Due to the popularity of solar panels, the world experiences a large growth of solar panel installation. However, solar panels have limited lifespan and start to lose it efficiency after 25 years. With the worldwide installation solar panels, a large amount of solar panel waste is expected to accumulate in the near future. Landfilling is the current go to method for end-of-life solar panel due to lack of development in solar panel recycling panel. Current solar panel recycling processes mainly focus on silver recovery while ignoring the other solar panel materials. This is unfortunate as silicon material found in solar panels is of high purity and large amounts of energy is required to manufacture them. Also, the glass in solar panel is the heaviest component and would account for a substantial amount of waste. Thus, one solution to encourage recycling is to focus on both glass and silicon by developing a method to upcycle both materials into high value products. Among the various high value products, the energy storage field was selected due to the blooming interest in electrical vehicles which increases demand for energy storage materials. Among the various emerging energy storage echnology, both silicon and glass recovered from end-of-life solar panels can be applied to silicon-based batteries and solid polymer electrolytes, respectively. Silicon based electrode is a new generation of battery material with a battery capacity ten times more than conventional graphite electrode. As for solid polymer electrolyte, it is developed to replace flammable liquid electrolyte resolving the safety issue associated with lithium-ion batteries. One of the main problems of upcycling end-of-life solar panels is that the components are held tightly together by a polymer called ethylene vinyl acetate (EVA). To retrieve the individual components, reported papers generally use high temperature methods to burn off the EVA polymer. Such high temperature is undesirable due to the energy consumption and the generation of toxic byproducts. Therefore, a low temperature and simple crush and sieve technique was developed and explored in this thesis. The low temperature method proves to be efficient in removing the polymer within a short duration and the batteries made with recovered silicon performed better than the those with commercialize silicon. Finally, this thesis explores the addition of glass from end-of-life solar panels into the new solid polymer electrolyte. Although solid polymer electrolyte (SPEs) is promising in replacing flammable liquid electrolyte, it cannot charge as fast the liquid electrolyte, hindering the commercialization of the SPEs. A way to resolve the slow charging rate is to add nanosized material (10-9m) into the SPEs whereby glass waste can be a suitable material for it. A simple ball milling method was employed to break down the glass by impacting it with high energy, resulting in glass nanoparticles. Results show that by adding these glass nanoparticles, both the charging rate and mechanical strength of the SPEs can be improved, making the product more durable. Overall, this project illustrates the potential of repurposing waste material from end-of-life solar panels into emerging energy storage devices through clean and simple process.