Abstract
Due to the outstanding properties in improving interfacial phenomena and battery performance, non-ionic Tween/Span surfactants have been widely applied in the battery field. However, although Tween/Span was classified as a more environmentally friendly product compared with other surfactants, there remains a lack of quantitative research on its environmental footprint. This study presents a comprehensive life cycle assessment (LCA) of Tween/Span surfactants, utilizing primary industrial data. Results indicated that producing 1000 kg of Tween series surfactants required 16.5-17.1 MWh of energy and emitted 2922-3019 kg CO₂ eq, while Span series surfactants required 14.5-16.4 MWh/t and emitted 2564-2895 kg CO₂ eq/t. Uncertainty analysis confirmed the robustness of the data. Sensitivity analysis identified surfactant price factors and oleic acid/ethylene oxide characterisation factors as key parameters. Reducing the environmental impact of upstream oleic acid/ethylene oxide production helps improve the sustainability of Tween/Span. Moreover, when considering carbon uptake, bio-based raw materials significantly reduced the carbon footprint (44.8%). Crucially, our data reveals that Ecoinvent proxies overestimate the carbon footprint by 14% (Tween) and 92% (Span), and energy demand by 71% for both. A case study on Tween 80-assisted Si/C anode manufacturing demonstrates that, despite added production burdens, surfactant-driven performance enhancements reduce overall battery lifecycle impacts. This work provides validated and high-quality LCI, demonstrates the sustainability of Tween/Span surfactants for battery applications, and offers critical metrics for advancing green chemistry in sustainable energy storage.