A disordered rock-salt Li-excess cathode material with high capacity and substantial oxygen redox activity: Li1.25Nb0.25Mn0.5O2 |
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| Institution: | 1. Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA;2. John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA;3. Department of Materials Science and Engineering, UC Berkeley, Berkeley, CA 94720, USA;4. Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA |
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| Abstract: | A disordered rocksalt Li-excess cathode material, Li1.25Nb0.25Mn0.5O2, was synthesized and investigated. It shows a large initial discharge capacity of 287 mAh g? 1 in the first cycle, which is much higher than the theoretical capacity of 146 mAh g? 1 based on the Mn3+/Mn4+ redox reaction. In situ X-ray diffraction (XRD) demonstrates that the compound remains cation-disordered during the first cycle. Electron energy loss spectroscopy (EELS) suggests that Mn and O are likely to both be redox active, resulting in the large reversible capacity. Our results show that Li1.25Nb0.25Mn0.5O2 is a promising cathode material for high capacity Li-ion batteries and that reversible oxygen redox in the bulk may be a viable way forward to increase the energy density of lithium-ion batteries. |
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