Safety and sustainability assessment in the development of new EDLC supercapacitors for energy storage

Next-generation energy storage solutions rely on advanced materials (AM) intentionally designed for enhanced physicochemical properties or improved functional performance. However, the development and use of AM in different applications may present challenges including human health safety and potential unintended environmental impacts. This study presents the practical application of the Safe and Sustainable by Design (SSbD) framework to the development of environmentally friendly supercapacitors in a Horizon Europe project. Safety assessments identified material hazards and occupational exposure risks, while environmental sustainability was evaluated via cradle-to-gate life cycle assessment (LCA) and material criticality and circularity assessment. Results indicated that most polar aprotic electrode inks like dimethyl sulfoxide (DMSO) lack mutagenicity or carcinogenicity. In contrast, Triton X-100 raised ecotoxicity concerns. Binders like polyvinylidene fluoride and styrene-butadiene rubber may trigger long-term inhalation concerns during electrode printing process without proper local exhaust ventilation. The LCA results showed that encapsulation accounts for more than 30% of the climate-change impact of supercapacitor production, primarily because of metal use. Owing to the higher specific capacitance, the flexible supercapacitor developed in the current project is estimated to reduce environmental burdens per farad by at most 30%. Material recycling could provide a further reduction of 15–25%.