Revealing the correlation between structural evolution and long-term cyclability of the LiNi0.5Co0.2Mn0.3O2/artificial graphite pouch cells at various rates--颗粒学报PARTICUOLOGY

Zang, X.-F., Yang, S., Zou, Y., Zhang, Y., Huang, T., & Xia, H.-L. (2023). Revealing the correlation between structural evolution and long-term cyclability of the LiNi0.5Co0.2Mn0.3O2/artificial graphite pouch cells at various rates. Particuology, 81, 162-173. https://doi.org/10.1016/j.partic.2023.01.005

Revealing the correlation between structural evolution and long-term cyclability of the LiNi_0.5Co_0.2Mn_0.3O₂/artificial graphite pouch cells at various rates

Xu-Feng Zang ^a *, Shengchen Yang ^b, Ying Zou ^a, Yingying Zhang^a, Tao Huang ^a, Hui-Ling Xia ^c *

a School of Science, Huzhou University, Huzhou, 313000, China
b Department of Engineering Technology, Huzhou College, Huzhou, 313000, China
c Laboratory Management Department, Huzhou University, Huzhou, 313000, China

10.1016/j.partic.2023.01.005

Volume 81, October 2023, Pages 162-173

Received 22 November 2022, Revised 30 December 2022, Accepted 1 January 2023, Available online 24 January 2023, Version of Record 2 February 2023.

E-mail: zangxufeng@zjhu.edu.cn, 02932@zjhu.edu.cn

Highlights

• Effect of charge-discharge rates on cyclability of a NCM523/AG pouch cell is investigated.

• Influences on cyclability decrease with order of charge rate > CV charge limit current > discharge rate.

• Failure mechanisms of the cells at various charge-discharge rates are studied.

• A series of chain reactions are observed in the cell faded early.

• Active area loss on AG and surface structural damage of NCM523 are main causes for cell degradation.

Abstract

In recent years, researches on improving high-voltage performance of lithium-ion batteries incorporating LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523) and artificial graphite (AG) have been widely reported. However, limited attentions have been paid to understand the effects and influence mechanisms of charge and discharge rates and charge limit currents on cyclability of NCM523/AG cells. Herein, a ∼1.9 Ah NCM523/AG pouch cell is employed, whose electrochemical and structural evolutions after 800 cycles at various rates are comprehensively investigated. We find that cycling performances are strongly influenced by charge rate, followed by limit current and discharge rate. The cell charged at a high rate and cell charged until reaching a low limit current both exhibit low capacity retentions compared to the cell discharged at a high rate. Possible failure reasons are analyzed by advanced characterizations. Results reveal that NCM523 cathodes of the cells deteriorated early experience severe transition metal dissolution, lattice distortion, and partial phase transformation. Meanwhile, the deposited transition metals on AG anodes catalyze the electrolyte consumption, lithium plating and active area loss. Finally, these side reactions notably increase cell impedance and electrochemical polarization. Undoubtedly, these findings clearly outline the challenges and optimization direction for high-rate NCM523/AG cells.

Graphical abstract

Keywords

Lithium-ion batteries; Artificial graphite; LiNi_0.5Co_0.2Mn_0.3O₂;Cycle life; Charge-discharge rate; Failure mechanism

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