Magnetic field-assisted bioleaching of cathode materials from spent Li-ion batteries using Acidithiobacillus ferrooxidans

A relatively weak static magnetic field with field strength is externally applied during the growth of using Acidithiobacillus ferrooxidans and subsequent bioleaching of spent Li-ion batteries (LIBs) to recover Li, Ni, Co, and Mn. 5 mT is the optimal field strength which allows 100 % Li to be recovered from a commercial black mass containing Li[Ni_0.6Co_0.2Mn_0.2]O₂ after 3 days of leaching. 85 % Ni, 95 % Co, and 100 % Mn are also recovered as dissolved in biogenic H₂SO₄ after 3 days. Without the external magnetic field, the leaching efficiency is limited to 20–40 % after the same leaching period. It is shown that the magnetic state of the substrate largely influences bioleaching efficiency since the magnetic enhancement is observed only from paramagnetic and ferromagnetic materials through improved cell attachment and not from antiferromagnetic materials. The proposed magnetic field-assisted bioleaching of spent LIBs using A. ferrooxidans can help the recycling of raw materials back into the circular economy for LIBs.