Electronic structure and electrochemical analysis of the Li2Mn1-xSexO3 materials

With the aim of probing the influence of the highly oxidizable selenium in the electrochemically inactive cathode Li2MnO3 material, samples were prepared with selenium substitution in the manganese coordination according to the general formula of Li2Mn1-xSexO3. In Li-ion batteries, oxygen instabilities are one of the major problems confronted that effect the performances of the cathode materials. The crystal and electronic structure properties of the materials were studied with x-ray absorption techniques. Selenium atoms were determined to build Li2SeO4 crystal and due to the oxygen removal during sample preparation mechanisms were determined to cause lower ionic conductivity than the parent Li2MnO3 oxide. The atomic distances in the materials were determined by the fits performed by the commercial code FEFF 8.2. Li2SeO4 crystal was determined as stacked between manganese and lithium atoms and isolated with each other. •Electronic and crystal structure properties of Se substituted Li2MnO3 materials were investigated.•Oxygen loss in the samples were detected due to over annealing.•The analysis results revealed over oxidation mechanisms in the Se coordinations.•Manganese atoms are determined to preserve their crystal structure, i.e., Li2MnO3.•The oxidation of the Se4+ ions were determined to shift to Se6+.