Effect of excess Li and cation mixing on electronic structure of LiNi 0.5Mn0.5O2 cathode active material of lithium-ion battery investigated by first-principle calculation

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Abstract

Co-free LiNi0.5Mno.5O2 shows better thermostability and higher discharge capacity than LIC0O2. We investigate the effects of Li content and cation mixing on electronic structure in LiXNi0.5Mn0.5O2 (x = 1.00 ∼ 1.08) by Rietveld analysis and first principle calculation. The crystal structures were well refined and excess Li existed at transition-metal site without any change of the Li and Ni occupancies at Li site. It suggests that the amount of the cation mixing has no relation with Li content. From the result of structure relaxation by calculation, it was found that the structure was stabilized by cation mixing and thus cation mixing is possible to happen theoretically. This result is caused by increase of covalent bond near the cation mixing atom. In the sample of Li1.03Nio5Mn0.5O 2 which shows good discharge performance, electron density between the transition metal and oxygen showed maximum among the investigated samples by MEM (experiment) and WIEN2k (calculation). Such result suggests that host structure stability plays an important role for the discharge performance.

Original languageEnglish
Pages (from-to)80-85
Number of pages6
JournalElectrochemistry
Volume79
Issue number2
DOIs
Publication statusPublished - Feb 2011

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Keywords

  • Crystal structure
  • Electronic structure
  • First-principle calculation
  • Li-ion battery

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