The project, funded by the German Federal Ministry of Education and Research under the grant number 03XP0246C and carried out from 1 October 2019 to 30 September 2022, was conducted at the MEET battery research centre of the Westfälische Wilhelms‑Universität Münster. The aim was to develop a flexible, energy‑efficient recycling route for lithium‑ion batteries that could adapt to new production technologies and material variations. The work was organised into three interlinked work packages: analytical characterisation, sub‑ and super‑critical CO₂ extraction, and resynthesis of battery‑grade materials.

In the analytical phase, shredded battery material from an industrial shredder was first optically pre‑sorted to separate copper‑rich flakes, black mass, and polymer fragments. Representative fractions (0.5–1.0 mm and 0.1–0.315 mm) were subjected to microwave‑assisted digestion and analysed by inductively coupled plasma optical emission spectroscopy (ICP‑OES). The stoichiometry of the positive electrode active material was reconstructed, yielding a Ni/Co/Mn ratio of 0.58/0.21/0.21 and a cumulative transition‑metal content of 24.03 ± 0.69 wt %. Lithium was quantified at 2.77 ± 0.08 wt %, with aluminium, copper, phosphorus, sodium, sulphur, magnesium and zirconium present at 5.14 ± 1.35, 7.61 ± 1.68, 0.77 ± 0.03, 0.15 ± 0.01, 0.14 ± 0.01, 0.38 ± 0.01 and 0.17 ± 0.01 wt % respectively. These values matched the limited data supplied by the material vendor and confirmed the presence of NMC‑622 chemistry. Where mixed chemistries such as NCM or NCA might complicate the analysis, single‑particle techniques were suggested as a complementary approach.

The extraction work package focused on recovering the electrolyte and carbonate salts. Several solvent combinations were tested that proved cheaper than conventional extraction media while delivering a markedly faster recovery of the salt. The solvent‑assisted CO₂ extraction proved capable of removing carbonate species efficiently, with significantly reduced extraction times when new co‑solvents were introduced. Mass spectrometry, pyrolysis, enrichment and extraction methods were employed to characterise organic residues and fluorinated species in the shredded material, providing essential data for downstream processing and safety assessment.

In the resynthesis phase, the recovered anode and cathode materials were converted back into battery‑grade powders. The resynthesised cathode material retained the original stoichiometry and purity, and the anode material was re‑coated onto current collectors. Full‑cell tests demonstrated that the resynthesised electrodes delivered performance comparable to fresh materials, confirming the viability of the recycling route.

Collaboration with other research institutions was integral to the project, enabling the exchange of analytical techniques and process knowledge. The project’s outcomes are expected to inform a broader recycling strategy, offering a scalable, cost‑effective, and environmentally friendly pathway for lithium‑ion battery end‑of‑life management.