Oxidation state of manganese in LiMn2O4 powders and its effect on electrochemcal properties

Abstract

Lithium manganese oxide (LiMn2O4) powders for lithium ion batteries were synthesized from two separate raw material pairs, LiOH/MnO and LiOH/MnO2. The prepared powders and their electrochemical properties were investigated. Powders calcined at 780 degrees C were composed of a single-phase spinet structure but those treated at 850 degrees C showed a higher intensity ratio of I-400 to I-311, a slightly larger lattice parameter, and an increased discharge capacity by 10% under 3.0 similar to 4.3V voltage range. The XPS study on the oxidation states of manganese repealed that powders made from LiOH/MnO had less Mn3+ ion and gave better battery performances than those from LiOH/MnO2.