Mechanism of Degradation of Capacity and Charge/Discharge Voltages of High-Ni Cathode During Fast Long-Term Cycling Without Voltage Margin

Jae Yeol Park, Minji Jo, Seungki Hong, Seunggyu Park, Jae Ho Park, Yong Il Kim, Sang Ok Kim, Kyung Yoon Chung, Dongjin Byun, Seung Min Kim, Wonyoung Chang

Research output: Contribution to journalArticlepeer-review

Abstract

The authors reveal the mechanisms of degradation of capacity, charge voltage, and discharge voltage of commercially-available high-nickel cathode material when it is cycled without a voltage margin by two different charge protocols: constant-current charging and constant-current, constant-voltage charging. With repeated constant-current charging, the cathode material changes to a non-periodic cation-mixed state, which causes a relatively low voltage degradation, whereas during constant-current, constant-voltage charging, the cathode material changes from a layered structure to a periodic cation-mixed spinel-like phase, with consequent severe voltage decay. This decay results from a reduction in the equilibrium electrode potential and an increase of overpotential which are aggravated in a periodic cation-mixed state. The findings provide insights into the use of excess Li without charge-voltage margin in high-Ni cathode materials.

Original languageEnglish
JournalAdvanced Energy Materials
DOIs
Publication statusAccepted/In press - 2022

Keywords

  • cation mixing
  • electrode potential
  • high-nickel cathodes
  • lithium-ion batteries
  • overpotential
  • STEM

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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