Volume 59, Issue 6 pp. 2385-2391
Research Article

In-Depth TEM Investigation on Structural Inhomogeneity within a Primary LixNi0.835Co0.15Al0.015O2 Particle: Origin of Capacity Decay during High-Rate Discharge

Hyesu Lee

Hyesu Lee

Center for Energy Storage Research, Korea Institute of Science and Technology (KIST), 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Korea

Department of Materials Science and Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, Korea

These authors contributed equally to this work.

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Eunmi Jo

Eunmi Jo

Center for Energy Storage Research, Korea Institute of Science and Technology (KIST), 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Korea

Division of Energy & Environment Technology, KIST School, Korea University of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Korea

These authors contributed equally to this work.

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Dr. Kyung Yoon Chung

Dr. Kyung Yoon Chung

Center for Energy Storage Research, Korea Institute of Science and Technology (KIST), 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Korea

Division of Energy & Environment Technology, KIST School, Korea University of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Korea

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Prof. Dongjin Byun

Prof. Dongjin Byun

Department of Materials Science and Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, Korea

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Dr. Seung Min Kim

Corresponding Author

Dr. Seung Min Kim

Carbon Composite Materials Research Center, Korea Institute of Science and Technology (KIST), 92, Chudong-ro, Bongdong-eup, WanjuGun, Jeollabuk-do, Korea

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Dr. Wonyoung Chang

Corresponding Author

Dr. Wonyoung Chang

Center for Energy Storage Research, Korea Institute of Science and Technology (KIST), 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Korea

Division of Energy & Environment Technology, KIST School, Korea University of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Korea

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First published: 17 October 2019
Citations: 19

Graphical Abstract

Origin of capacity decay: Structural evolutions within a primary LiNi0.835Co0.15Al0.015O2 (NCA83) particle, as a cathode material for Li-ion batteries, were investigated during various electrochemical processes using TEM. Significant reduction in the electrochemical capacity of NCA83 in the second charge is correlated with the development of nano-scale and micro-scale structural inversions.

Abstract

The structural stability of cathode materials during electrochemical reactions, in particular, under high-rate discharge, is pertinent to the design and development of new electrode materials. This study investigates the structural inhomogeneity that develops within a single LiNi0.835Co0.15Al0.015O2 (NCA83) particle during a fast discharging process under different cutoff voltages. Some of the NCA83 particles discharged from a high cutoff voltage (4.8 V) developed surface areas in which the layered structure was recovered, although the interiors retained the degraded spinel structure. These micro- and nano-scale structural inversions from high cutoff voltage seem highly correlated with structural evolutions in the initial charged state, and may ultimately degrade the cycling stability. This study advances understanding of the structural inhomogeneity within primary particles during various electrochemical processes and may facilitate the development of new Ni-rich cathode materials.

Conflict of interest

The authors declare no conflict of interest.

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