Atomic-scale investigation of Lithiation/Delithiation mechanism in High-entropy spinel oxide with superior electrochemical performance

Chih Yang Huang, Chun Wei Huang, Min Ci Wu, Jagabandhu Patra, Thi Xuyen Nguyen, Mu Tung Chang, Oliver Clemens, Jyh Ming Ting*, Ju Li, Jeng Kuei Chang, Wen Wei Wu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Transition-metal high-entropy oxides (HEOs) are promising electrode materials for lithium-ion batteries (LIBs) due to their superior electrochemical properties and excellent long-term cycling stability. The performance of HEOs for LIBs is highly correlated with their microstructures, especially their evolution during charging/discharging. However, there is limited information regarding this topic in the literature. In this study, the unique transition behavior of a spinel HEO, (CrMnFeCoNi)3O4, at various states of charge and cycle numbers is examined in detail for the first time. Although the elemental segregation of lithiated HEO particles is observed, the crystal structure remains spinel, leading to great cyclability. Mn nanocrystals form at 0.5 V lithiation and metallic Cr, Fe, Ni, and Co particles form at 0.01 V lithiation. The spinel CrxFe3-xO4 and LiNixCo1-xO2 phases act as seeds that grow by devouring surrounding metal nanoparticles during delithiation. The Mn can reversibly move at least dozens of nanometers across the oxide during lithiation/delithiation. The detailed cycling mechanism is examined using electron energy-loss spectroscopy. The reversible valence state variations of the constituent elements are observed. The results provide an in-depth understanding of the fundamental lithiation/delithiation mechanism of HEO, which will facilitate the development of better multi-element HEOs for Li+ storage applications.

Original languageEnglish
Article number129838
JournalChemical Engineering Journal
Volume420
DOIs
StatePublished - 15 Sep 2021

Keywords

  • Cycling stability
  • Electron energy-loss spectroscopy
  • High-resolution electron microscopy
  • Lithium-ion batteries
  • Phase segregation
  • Spinel anode materials

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