Assessing the critical role of graphite in the carbon footprint of lithium-ion battery production

The central focus of existing life cycle assessment (LCA) studies on lithium-ion battery (LIB) cell production has been around cell manufacturing energy, different cathode chemistries, and the supply chain of cathode active materials. In contrast, the crucial role of graphite as the anode active material on the carbon footprint (CF) of LIB cell production has remained largely underexplored. Particularly the differences between synthetic and natural graphite, and their varying compositions in LIB anodes and sourcing are not considered. This work addresses this gap by conducting an LCA on LIB cell production using latest industrial primary LCA data for both graphite types. The results highlight that the CF of LIB cell production is substantially higher (93 kg CO2eq. kWh$^{-1}$) than LIB cell with older graphite datasets (58 kg CO$_2$eq. kWh$^{-1}$), with graphite emerging as a key hotspot (37 kg CO$_2$eq. kWh$^{-1}$, 26.85 kWh kWh$^{-1}$). Results show that the choice and proportion of the graphite types in the anode strongly influence the CF of LIB cell production. Furthermore, the findings reveal the importance of relative
proportions of the two graphite types in benchmarking where different ratios of graphite types may lead to different benchmarking results. ... mehrMoreover, the origin of the graphite substantially influences the overall CF of LIB cell production. Utilizing graphite sourced from regions with a higher proportion of renewable energy in their electricity mix significantly reduces the CF of cell production compared to graphite sourced from regions with a lower share of renewables. Nevertheless, the study underscores the importance of including the full life cycle data (use-phase and end-of-life) into future assessments to fully capture the effects of different proportions of the two different graphite types on performance and cycle life for a robust decision making on the optimal ratio of graphite in LIB cell design from an environmental perspective. Overall, the study provides important insights for multiple stakeholders by highlighting the pivotal role of graphite, its types, and sourcing in determining the environmental performance of LIB cell.