Improving process granularity of life cycle inventories for battery grade nickel.

Batteries are essential to transition to a fossil-free energy system, but only if coherently planned will their manufacturing generate minimal environmental impacts. Aggregated life cycle inventories for battery-grade nickel prevent life cycle analysts from easily pinpointing key impact contributors. The present work reconstructs inventories via disaggregation of current and emerging processing routes. Improving process granularity demonstrates variability in climate impacts of 74 kgCO_2eq/kWh for nickel sourcing of an NMC-811 cell. Furthermore, the global ecoinvent v.3.9.1 dataset for nickel sulfate could gravely underestimate climate impacts by 120 kgCO_2eq/kg Ni equivalent. Major contributors to climate impacts are readily identified for six nickel processing pathways, spanning two mineral families - laterite and sulfide - and three main processing routes - hydrometallurgy, bioleaching and pyrometallurgy. A preliminary assessment of all impact categories highlights the need for both improved fate models and data collection on inventory parts such as tailings management which are often neglected in carbon-focused studies.