Recovery of manganese as spinel MgMn2O4 cathode material from electrolytic manganese residue by Na2CO3 hydrothermal-roasting process.

• Mn and Mg were recovered from EMR as MgMn 2 O 4 (MMO) through Na 2 CO 3 hydrothermal-roasting process. • Synthesis conditions significantly affect the morphology and structure of MMO. • Flower-like f-MMO and hollow h-MMO were synthesized. • The as-synthesized MMO showed superior electrochemical performances as cathode material of magnesium-ion batteries. Recovering high-value-added Mn products from electrolytic manganese residue (EMR) is prominent due to the scarcity of Mn resource and its increasing importance in various industries. In this study, we explored Mn and Mg recovery from EMR for the synthesis of cathode material MgMn 2 O 4 for the first time through Na 2 CO 3 hydrothermal-roasting method. Na 2 CO 3 concentration and roasting temperature were found to significantly affect the morphology and structure of MgMn 2 O 4. Both flower-like MgMn 2 O 4 (f-MMO) and hollow MgMn 2 O 4 (h-MMO) were synthesized under optimized conditions. Additionally, the electrochemical performances of MgMn 2 O 4 as cathode material of magnesium-ion batteries were evaluated. Both f-MMO and h-MMO showed superior rate performance. High initial reversible capacity can be achieved (237.5 mAh/g), and still retain 157.7 mAh/g after 40 cycles at 100 mA/g and 76 mAh/g after 500 cycles at 500 mA/g. This work inspires the way for recovering Mn from EMR as energy storage material. [ABSTRACT FROM AUTHOR]