Upcycling of end-of-life photovoltaic panels and lithium from spent Li-ion batteries for the sustainable synthesis of lithium metasilicate

Abstract A wide range of portable electronic devices, such as laptops, mobile phones, electronic tools, and electric vehicles, utilize lithium-ion batteries as energy storage resource. However, its application is restricted by moderate electrochemical performance and the significant cost of production. As part of the strategies to enhance the electrochemical performance, lithium metasilicate (Li₂SiO₃) has been proposed as a coating layer for the anode material. Thus, lithium diffusion and electronic conductivity are improved while preventing the expansion of the anode volume. This potential application of Li₂SiO₃ is conditioned upon the costs associated with both the process and the raw materials required for its synthesis.This study aims to develop a cost-effective synthesis route for lithium metasilicate by replacing conventional raw materials with recycled precursors; lithium chloride recovered from spent Li-ion batteries and silicon extracted from discarded photovoltaic panels. The molar ratio of LiCl to Si was assessed to determine the best conditions for the synthesis of Li₂SiO₃. The influence of milling the time on the promotion of the formation of this metasilicate. Non-isothermal calcinations were performed throughout a temperature range of 20–900°C to evaluate the impact of temperature on the reaction path. Furthermore, isothermal calcinations were conducted to determine the impact of time on the reaction yield. The reaction mechanism also was investigated. The results indicated that a molar ratio of LiCl to Si of 5:1 and a milling time of 24 h produce a high yield of Li₂SiO₃. The synthesis of Li₂SiO₃ was found to initiate at 600°C. A yield of 97.15% was obtained from the calcination performed at 900°C for 21 min.