Recover value materials from waste photovoltaic modules as secondary resource: Layer separation by eco-friendly reagent DMC combined pyrolysis

Abstract

Recovery of value materials from waste photovoltaic (PV) modules is conducive to resource recycling and environmental protection. Recycling waste PV modules is the reverse process of manufacturing, and the key is to separate different layers. Herein, an eco-friendly reagent, DMC (dimethyl carbonate, C₃H₆O₃), was firstly utilized to separation different layers of waste PV modules, achieving clean glass and back sheet in which the solid-to-liquid ratio was 1:6 g/mL, reaction temperature was 80 °C, and the size of sample was 2 × 2 cm. The mechanism reflected that DMC mainly reacted with the vinyl acetate portion to decompose EVA into ethylene-vinyl alcohol copolymer and destroyed the tight cross-linking structure. DMC retained its original properties and was cycled for several times. Pure solar cells and connecting strips were obtained by pyrolysis without fluorinated gas after layer separation. The chains of EVA broke and was decomposed by oxidation in the air atmosphere. The whole process did not produce hazardous substances and provided a referable route for the recovery of waste PV modules.