Towards environmentally sustainable battery anode materials: Life cycle assessment of mixed niobium oxide (XNO™) and lithium‑titanium-oxide (LTO)

Abstract

Electric mobility has proven to be essential for the carbon neutrality of the transport sector. However, several studies have demonstrated the environmental costs linked to the supply of rechargeable batteries, which should not be overlooked. The supply of some elements has raised concerns, either because they are associated with environmental and social risks, or because they are considered critical raw materials due to their concentrated geographical supply. It is therefore important to look for innovative technologies capable of reducing the demand for traditional battery raw materials and technologies, but that also have lower environmental impacts linked to their supply. Niobium has been reported to improve the performance of battery components and could (partially) replace some traditional battery materials, but little is known about the environmental impacts of niobium-based battery materials. This study compares two commercial lithium-ion battery anode materials, namely lithium-titanate (LTO) and an innovative mixed niobium oxide anode material (ECA-302, a formulation of XNOTM). Life cycle assessment is employed to quantify the environmental impacts of both technologies, taking into account impacts on global warming potential (GWP), acidification, ozone depletion, photochemical ozone formation (POF) and the use of fossil resources. The impacts were quantified by mass (1 kg anode material) and functionality (1 kWh delivered/cycle life), using primary industrial data for ECA-302 and literature-adapted data for the LTO. Results show that ECA-302 performs better than LTO considering both the material mass and energy delivery per cycle levels. The GWP for the supply of the ECA-302 was 51% lower than the LTO, but the most remarkable differences were observed for POF, for which ECA-302 had an impact about 72% lower than LTO at the production stage and 77% lower at the energy delivery. The results also indicate that 20% less ECA-302 material is needed to deliver 1 kWh over the cycle life of the battery compared to LTO.