Upcycling of EVA resin from photovoltaics into supercapacitor material and combustible gas by autogenic pressure pyrolysis

In response to the growing challenge of photovoltaic waste management, developing sustainable and value-added treatment strategies is imperative. In this study, ethylene-vinyl acetate (EVA) resins sourced from waste photovoltaic modules and virgin materials were utilized for the production of hierarchical porous carbon (HPC) and methane-rich combustible gas via autogenic pressure pyrolysis coupled with KOH activation. Temperature-dependent pyrolysis revealed that 700 °C was the optimal condition, yielding pyrolysis gas with a high methane content (43.39 vol%) and producing graphitized carbon spheres. Subsequent KOH activation generated HPC with a large specific surface area of 765.4 m²/g. When applied as a supercapacitor electrode in 6 mol/L KOH electrolyte, the HPC exhibited a high specific capacitance of 152 F/g at 0.2 A/g. Additionally, EVA resins with higher vinyl acetate content and melt index (MI) produced greater amounts of methane and pyrolytic carbon, while the resins with lower MI values showed enhanced reactivity toward chemical activation. This work offers a green and efficient route for the high-value recycling of EVA in PV waste and contributes to the sustainable synthesis of advanced HPC materials for energy storage applications.