Red mud and Li-ion batteries: A magnetic connection

Exceptional Li-ion battery performance is presented with the oxide component of the anode was extracted from red mud by simple magnetic separation and applied directly without any further processing. The extracted material has γ-Fe₂O₃ as the major phase with inter-dispersed phases of Ti, Al, and Si oxides. In a half-cell assembly, the phase displayed a reversible capacity (~697 mAhg^-1) with excellent stability upon cycling. Interestingly, the stability is rendered by the multiphase constitution of the material with the presence of other electrochemically inactive metal oxides, such as Al₂O₃, SiO₂, and Fe₂TiO₄, which could accommodate the strain and facilitate release during the charge-discharge processes in the electrochemically active maghemite component. We fabricated the full-cell assembly with eco-friendly cathode LiMn₂O₄ by adjusting the mass loading. Prior to full-cell assembly, an electrochemical pre-lithiation was enforced to overcome the irreversible capacity loss obtained from the anode. The full-cell delivered a capacity of ~ 100mAhg^-1 (based on cathode loading) with capacity retention of ~61 % after 2000 cycles under ambient conditions.