The efficiency of scrap Cu and Al current collector materials as reductants in LIB waste leaching

Alexander Chernyaev,Jere Partinen,Lassi Klemettinen,Benjamin P Wilson,Ari Jokilaakso,Mari Lundström

doi:10.1016/j.hydromet.2021.105608

Abstract

This current study addresses the role of copper and aluminum - typical major components of current collector scrap from battery manufacturing plants - in the leaching of pre-treated LiCoO2-rich battery waste concentrate at industrially relevant process conditions (T = 60 °C, [H2SO4] = 2 M, S/L = 200 g/L). An empirical model has been constructed which demonstrates that the effects of both copper and aluminum are significant. Both elements have independent and linear impacts on cobalt extraction and acid consumption. The model predicts that either 11 g of copper (0.75 Cu/Co, mol/mol), 4.8 g of aluminum (0.7 Al/Co, mol/mol) or a combination of both are required for full cobalt extraction from 100 g of sieved industrial battery waste concentrate. Aluminum was shown to influence cobalt leaching although it was less effective (47%) when compared to copper (66%) in terms of current efficiency due to associated side reactions, such as excess H2 formation. Aluminum has several possible reaction routes for LiCoO2 reduction; in parallel or in series via H2 formation, Cu2+ cementation and/or Fe3+ reduction, whereas copper acts solely through Fe3+ reduction. These results indicate that by using copper scrap, in preference to the more typical hydrogen peroxide, the CO2 footprint of the battery leaching stage could be decreased by at least 500 kg of CO2 per ton of recycled cobalt. In contrast, the use of aluminum, although promising, is less attractive due to the challenges related to its removal during subsequent solution purification.

Highlights

Transition from a carbon-intensive economy to a clean energy economy necessitates a rise in the use of technological applica tions that are increasingly dependent on mineral and metal-rich re sources
This current study addresses the role of copper and aluminum - typical major components of current collector scrap from battery manufacturing plants - in the leaching of pre-treated LiCoO2-rich battery waste concentrate at industrially relevant process conditions (T = 60 ◦C, [H2SO4] = 2 M, S/L = 200 g/L)
The unique feature of this investigation is that both impure indus trially produced battery waste concentrate and current collector scrap from an EV battery manufacturing site were used in the experiments, making the study highly relevant for realistic industrial-scale battery recycling process development

Summary

Introduction

Transition from a carbon-intensive (oil-based) economy to a clean energy economy necessitates a rise in the use of technological applica tions that are increasingly dependent on mineral and metal-rich re sources. The ever-growing variety of applications of lithium-ion batteries (LIBs) such as EVs, mobile devices, and energy storage, requires a significant increase in the levels of lithium-ion battery manufacturing. The anode typically comprises of graphite coated Cu foils, whereas the active materials based on Li oxides - such as LiCoO2 (LCO), LiMn2O4, LiNixMnyCozO2 (NMC), and LiFePO4, are coated on Al cathodes (Meng et al, 2020). The LiCoO2 battery chemistry was first introduced commercially in 1991 and has since become the basis for a majority of Li-ion battery technologies (Helbig et al, 2018). Chemistries like lithium nickel manganese cobalt oxide (NMC/NCM) have been introduced primarily in order to lower the amount of highcost Co present within battery cells (Helbig et al, 2018). The rapid growth in LIB use and the incremental refinement of the various battery technologies has resulted in a complex battery waste that needs new industrial approaches to optimize battery metal recoveries

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