Long-term cycling behavior of Mg-doped LiCoO2 materials investigated with the help of laboratory scale X-ray absorption near-edge spectroscopy

Katja Lahtinen, Maximilian Labmayr, Ville Mäkelä, Hua Jiang, Jouko Lahtinen, Lide Yao, Ekaterina O. Fedorovskaya, Samuli Räsänen, Simo Huotari, Tanja Kallio*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

11 Citations (Scopus)
84 Downloads (Pure)

Abstract

The use of Li-ion batteries is increasing rapidly. Understanding the processes behind active material aging helps to enhance the materials, and therefore, development of new in situ methods for structural studies is important. In addition, understanding the effect of different synthesis methods on the active material properties is necessary to optimize the material cycle life. In this work, the performance of LiCoO2 doped with Mg during the lithiation step is compared to LiCoO2 prepared using an Mg-doped Co3O4 precursor. In situ laboratory-scale X-ray absorption near-edge spectroscopy is used to analyze the Co valence changes in LiCoO2 to understand the electrochemical behavior of the investigated materials. The maximum reachable Co valence state is found to decrease upon aging, a small decrease indicating a good cycle-life, and this is attributed to the enhanced stacking order, better Mg distribution in the lattice, and fine primary particle size in the material. In the synthesis conditions used in this study, Mg doping during the lithiation step is shown to perform better compared to the precursor doping. Overlithiation is shown to reduce the electrochemical performance of nondoped and precursor-doped LiCoO2 materials but not to affect the cyclability of lithiation-doped LiCoO2.

Original languageEnglish
Article number101040
Number of pages14
JournalMaterials Today Energy
Volume27
Early online date17 Jun 2022
DOIs
Publication statusPublished - Jul 2022
MoE publication typeA1 Journal article-refereed

Keywords

  • Doping
  • Li-ion battery
  • Overlithiation
  • Synthesis
  • Valence state
  • XANES

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