Industrial Recycling of Lithium-Ion Batteries—A Critical Review of Metallurgical Process Routes

Abstract

Research for the recycling of lithium-ion batteries (LIBs) started about 15 years ago. In recent years, several processes have been realized in small-scale industrial plants in Europe, which can be classified into two major process routes. The first one combines pyrometallurgy with subsequent hydrometallurgy, while the second one combines mechanical processing, often after thermal pre-treatment, with metallurgical processing. Both process routes have a series of advantages and disadvantages with respect to legislative and health, safety and environmental requirements, possible recovery rates of the components, process robustness, and economic factors. This review critically discusses the current status of development, focusing on the metallurgical processing of LIB modules and cells. Although the main metallurgical process routes are defined, some issues remain unsolved. Most process routes achieve high yields for the valuable metals cobalt, copper, and nickel. In comparison, lithium is only recovered in few processes and with a lower yield, albeit a high economic value. The recovery of the low value components graphite, manganese, and electrolyte solvents is technically feasible but economically challenging. The handling of organic and halogenic components causes technical difficulties and high costs in all process routes. Therefore, further improvements need to be achieved to close the LIB loop before high amounts of LIB scrap return.

Challenges in Ecofriendly Battery Recycling and Closed Material Cycles: A Perspective on Future Lithium Battery Generations

“…In this process, the battery cells or modules can be placed in a direct pyrometallurgical step or they can be mechanically processed in a first step (analogous to the mechanical-hydrometallurgical), and the obtained valuable black mass is fed into the pyrometallurgy. Pyrometallurgical processing involves high-temperature processes such as melting and roasting to produce battery slag [52]. A pyrometallurgical recycling process of LIBs starts with an initial heating in the temperature range of 150-500 • C, during which electrolyte components and organic solvents are removed.…”

“…The processes generate only intermediates that have to be purified by further steps to enable reuse (e.g., further processing by hydrometallurgical steps). In addition, they show low economic efficiency when low concentrations of recyclable materials (e.g., Co, Cu, and Ni) are present [24,52,55].…”

“…Consequently, a circular economy for traction batteries, i.e., lithium-ion battery systems is demanded by the European Union as written in the Battery Directive 2006/66/EC and [13] as well as the Circular Economy Initiative Deutschland (CEID) of the National Academy of Science and Engineering in Germany [14]. In addition, many research studies are being done on this topic while highlighting the challenges that still exist and need to be overcome [17,21,52,72]. Such closed circles improve the sustainability of lithium-ion batteries; they especially decrease the carbon footprint, decrease the material costs, and ensure secondary material resources for Europe [73,74].…”

“…Depending on the process, graphite and binder can also be separated. Finally, metal salts are to be precipitated and re-synthesized to produce new active materials [48,52]. Alternatively, the anode and cathode active materials can be reconditioned by means of purification processes, lithium enhancement, and functionalization [47,51,[77][78][79].…”

Future Material Developments for Electric Vehicle Battery Cells Answering Growing Demands from an End-User Perspective

“…Although it is beneficial for passivating the aluminium current collector [136], HF is highly toxic and can react further with other electrolyte components to form other toxic compounds such as fluorophosphonates [137]. Therefore, it is a safety hazard during the manufacturing and recycling processes [138]. While other fluorinated salts, such as LiTFSI and LiFSI have shown higher solubility, conductivity and thermal stability than LiPF 6 -based electrolytes [139], and good electrochemical performance in high-energy-density batteries [140], they fail to passivate the aluminium and, in the case of LiFSI, it contains labile F atoms susceptible to hydrolysis [141].…”