On process-based granular reconstruction of life cycle inventories: sustainably coherent planning of primary battery-grade nickel

Abstract

Batteries are essential to transition to a fossil-free energy system, but only if coherently planned will their manufacturing generate minimal environmental impacts. Available inventories for battery-grade nickel suffer from many layers of aggregation, preventing life cycle analysts from easily pinpointing key contributors to its potential environmental impacts. The present work reconstructs life cycle inventories for nickel via disaggregation of current and emerging processing routes. Our proposed process-based method for inventory modelling demonstrates high variability in impacts from increased process granularity. Only considering nickel sourcing for an NMC-811 cell, climate impacts may vary by 74 kgCO2eq/kWh produced. It is also found that the global ecoinvent v.3.9.1 dataset for battery-grade nickel sulfate could gravely underestimate climate impacts by more than 120 kgCO2eq/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. Furthermore, a preliminary assessment of all impact categories is performed and highlights the need for both improved fate models and further data collection on inventory parts such as tailings management which are often neglected in previous studies assessing carbon only.