This article examines some of the basic questions about silicon module recycling: (1) What can be recovered from silicon modules? (2) What recycling technologies are needed? (3) What are the potential revenues for different recycling scenarios? And (4) what are the major challenges for different recycling scenarios? Three recycling scenarios are considered: module reuse, component extraction, and material extraction. Recycling process sequences for different scenarios are outlined. The discussions conclude that module reuse generates the highest revenue with the fewest processing steps, while material extraction leads to the lowest revenue with the most processing steps. It is suggested that gentle and clean separation of silicon solar cells from the glass pane is a critical technology for silicon module recycling. It is also argued that two low‐concentration metals must be recovered from silicon modules: silver as a scarce material and lead as a toxic material. Their recovery requires chemical methods, while bulky materials including glass cullet, aluminum frame, and copper wiring can be recovered with physical methods. The silicon in the cells can be extracted with different qualities: ferro‐silicon, metallurgical‐grade silicon, or solar‐grade silicon, with a higher revenue and more complicated recycling process for purer silicon. Markets outside the solar industry for the recovered silicon should be explored. The biggest challenge for module reuse is to find a large and sustained market for hundreds of gigawatts peak of decommissioned modules a year, and the biggest challenge for component extraction is the many different module and cell structures on the market and cell efficiency variability. For all the three scenarios, the cost of collecting and processing waste modules is a common challenge.

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The effects of pyrolysis on the composition of the battery cell materials as a function of treatment time and temperature were investigated. Waste of Li-ion batteries was pyrolyzed in a nitrogen atmosphere at 400, 500, 600, and 700 °C for 30, 60, and 90 min. Thermodynamic calculations for the carbothermic reduction of active materials LiCoO2, LiMn2O4, and LiNiO2 by graphite and gas products were performed and compared to the experimental data. Ni, Mn, and Co (NMC) cathode materials recovered from spent Li-ion batteries were also studied. The results indicate that the organic compounds and the graphite are oxidized by oxygen from the active material and provide the reductive atmosphere. Such removal of the organic components increases the purity of the metal bearing material. Reactions with C and CO(g) led to a reduction of metal oxides with Co, CoO, Ni, NiO, Mn, Mn3O4, Li2O, and Li2CO3 as the main products. The reduction reactions transformed the metal compounds in the untreated LiB black mass to more soluble chemical forms. It was concluded that the pyrolysis can be used as an effective tool for the battery waste pretreatment to increase the efficiency of the leaching in hydrometallurgical processing of the black mass. The results obtained can help to optimize the parameters in the industrial processing already used for Li-ion battery recycling, especially if followed by hydrometallurgical treatment. Such optimization will decrease the energy demand and increase the metal recovery rate and utilization of the byproducts.

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