Low temperature synthesis of Fe2O3 and LiFeO2 as cathode materials for lithium-ion batteries

Amorphous FeOOH and α-FeOOH were synthesized by simple solvothermal methods and used as the reactants to prepare iron oxide-based cathode materials. Amorphous FeOOH transforms to α-Fe2O3 at temperatures as low as 80 °C, and is stable enough to avoid the transformation to α-LiFeO2 even at 200 °C in LiOH ethanol solution under solvothermal condition. α-FeOOH transforms to α-LiFeO2 in the same reaction system at 140 °C. Both α-Fe2O3 and α-LiFeO2 demonstrate good electrochemical performances, especially α-Fe2O3, which delivers a high reversible capacity (105 mAh/g at 100 mA/g after 50 cycles) in the voltage range from 1.5 to 4.5 V. The electrochemical performances of α-Fe2O3 were found to be influenced by the solvent, temperature, reaction duration and alkali concentration of the solvothermal reactions. It was found that ethanol solution, low temperature, and moderate reaction duration and alkali concentration lead to α-Fe2O3 with reversible capacity of about 100 mAh/g.