Submerged comminution of lithium-ion batteries in water in inert atmosphere for safe recycling

Abstract

We would like to discuss the recycling process of lithium-ion batteries (LIBs) from the viewpoint of “safety”. We consider that comminution in water is a safer process than dry comminution as water can deactivate the negative electrode and organic electrolyte immediately. The comminution in water of relatively large fully-charged LIBs in a N₂ atmosphere was carried out. However, in spite of the submerged comminution, white smoke rising from the water was observed. The hydrogen concentration above the comminution equipment reached a few percent even with N₂ flow of 15–20 L min⁻¹ (or about 4% hydrogen for a comminution of an 895 mA h cell with low N₂ flow of 4.5 L min⁻¹). Considering the high ignition properties of hydrogen–air mixtures, the submerged comminution equipment should be installed not in air but in an inert atmosphere to reduce the risk of an explosion accident.