Mechanical degradation behavior of single crystal LiNixMnyCozO2 cathode in li-ion battery by indentation analysis

Ying Chen, Weiling Luan, Xuanchen Zhu, Haofeng Chen

Research output: Contribution to journalArticlepeer-review

Abstract

LiNixMnyCozO2 (NMC) is among the most promising cathode materials for commercial Li-ion batteries due to its high electrochemical performance. However, NMC composite cathode is still plagued with limited cyclic performance, which is influenced by its structural stability during the cycling process. The cathode, which comprises of the active material, polymeric binder, and porous conductive matrix, often exhibits large structural variation during the electrochemical cycling process. This inevitably increases the challenge of measuring the mechanical properties of the material. Even though single crystal NMC possesses better stability as compared to the polycrystalline NMC, the electrochemical performance degradation of single crystal NMC cathode remains relatively unexplored. Different sample preparation methods are compared systematically in accordance to the previous report, and a new method of sample preparation is proposed. Nanoindentation instrument is used to measure the elastic modulus and hardness of the single crystal NMC particles. The measured elastic modulus and hardness of NMC particles, under different electrochemical environments, are dependent on a large number of nanoindentation experiments and statistical analysis of the result obtained from the carefully prepared samples. The sample preparation method is the key factor that can significantly influence the nanoindentation experiment results of the NMC particles. This work shows that the mechanical properties of the single crystal NMC particles degrade significantly with number of electrochemical cycles. The decreasing elastic modulus with the number of electrochemical cycles can be fitted using a two-parameter logarithm model.
Original languageEnglish
Article number051505
Number of pages8
JournalJournal of Pressure Vessel Technology
Volume144
Issue number5
Early online date12 Jan 2022
DOIs
Publication statusPublished - 14 Feb 2022

Keywords

  • single crystal NMC
  • degradation
  • elastic modulus
  • hardness
  • electrochemical cycles

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