A new electrochemical process on the recovery metallic Mn from waste LiMn₂O₄ based Li-ion batteries in NaCl-CaCl₂ melts

A new method for the recovery of Mn is proposed via direct electrochemical reduction of LiMn₂O₄ from the waste lithium-ion batteries in NaCl-CaCl₂ melts at 750℃. The results show the reduction process of LiMn₂O₄ by electrochemical methods on the coated electrode surface are in three steps, Mn(IV) → Mn(III) → Mn(II) → Mn. The products of electro-deoxidation are CaMn₂O₄, MnO, (MnO)_x(CaO)_1-x and Mn. Metal Mn appears when the electrolytic voltage increased to 2.6 V. Increasing the voltage could promote the deoxidation reaction process. With the advancement of the three-phase interline(3PI), the electric deoxygenation gradually proceeds from the outward to core. With the high voltage, the kinetic process of the reduction reaction is accelerated, and double 3PI in different stages are generated.