Green surfactants powering sustainable batteries: industrial-scale life cycle assessment of Tween and Span surfactants for battery systems

Abstract

Due to their outstanding ability to improve interfacial phenomena and battery performance, non-ionic Tween/Span surfactants have been widely applied in the battery field. However, although Tween/Span have been classified as more environmentally friendly surfactants 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. The 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 the Span series surfactants required 14.5–16.4 MWh t⁻¹ and emitted 2564–2895 kg CO₂ eq. per t. Uncertainty analysis confirmed the robustness of the data. Sensitivity analysis identified surfactant price factors and oleic acid/ethylene oxide characterization 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 reveal 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 the overall battery life cycle 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.