Recycling of electrode production scrap: Development of dry, solvent-based and thermal mechanical processes for direct recycling

The production of electrodes and cells for lithium-ion batteries (LIBs) accounts for a large proportion of the energy and materials used in the lifecycle of a battery. In addition, the ramp-up phase of a gigafactory in particular is associated with significant amounts of production scrap, which is in principle suitable for direct recycling as the active materials used (anode and cathode) do not yet show signs of electrochemical degradation. The direct recycling of these production scrap would therefore represent a significant reduction in the need for primary materials and thus a major environmental and economic benefit. However, it is still unclear which of the processes currently being investigated, mostly on a laboratory scale, will prove most successful in a large-scale industrial environment and have the greatest potential for direct and sustainable recycling of these production scraps.

In our presentation, we will give an overview of the most common processes (thermal, dry and solvent-based) and our in-depth investigations into the recycling of electrode scrap with the associated characteristics, advantages, disadvantages and challenges in terms of recovery rates, recyclate quality, process complexity, scalability and the resulting electrochemical performance of LIBs containing recyclate. Our investigations show that, depending on the type of electrode (anode or cathode), different processes lead to recycling rates of (in some cases well above) 90% and that these materials are in principle suitable for direct re-use in electrode production [1].

In the context of electrode processing, the recycling strategy and process complexity varies depending on the process route chosen, so rheological investigations and other electrode characterisation methods (such as adhesion and conductivity measurements) are presented. The results also show that the use of recyclates affects the electrode and cell properties and that this must be taken into account for successful direct recycling. Investigations into the performance of LIB cells containing recyclates demonstrate that they have the same or even improved capacities (approx. 165 mAh g-1 for graphite/NMC622 coin cells), so possible causes such as a shift in the electrode (anode and cathode) potentials are discussed. Finally, the results of the research will contribute to a better understanding of the direct recycling of electrode scrap and overall sustainable battery production.

[1] Marco Ahuis, Anas Aluzoun, Miriam Keppeler, Sebastian Melzig, Arno Kwade, Direct recycling of lithium-ion battery production scrap – Solvent-based recovery and reuse of anode and cathode coating materials, Journal of Power Sources, Volume 593, 2024