Issue 24, 2021

Direct observation of the in-plane crack formation of O3-Na0.8Mg0.2Fe0.4Mn0.4O2 due to oxygen gas evolution for Na-ion batteries

Abstract

Crack formation is considered one of the significant failure modes of layered oxide cathode materials for Na-ion batteries because particle cracks accelerate electrolyte decomposition, transition metal dissolution, and electrical contact loss. However, the crack formation mechanism of layered sodium transition metal oxides has not been fully understood yet. Herein, the in-plane crack formation mechanism of O3-type Na0.8Mg0.2Fe0.4Mn0.4O2 is demonstrated in terms of oxygen gas evolution due to air-exposure using in situ mass spectrometry and various atomic-scale analyses. When Na0.8Mg0.2Fe0.4Mn0.4O2 is exposed to air, Na+ ions are unevenly deintercalated in a form of stripe pattern along the in-plane direction. The deintercalation of Na+ ions gives rise to phase transition from the layered structure to the disordered structure, including spinel-like and rock salt-like structures, resulting in forming the nanoscale vertical heterostructure of alternating layered and disordered phases along the out-of-plane direction. The formation of the disordered structure is accompanied by oxygen gas evolution. As a result, cracks occur along the in-plane direction of Na0.8Mg0.2Fe0.4Mn0.4O2 because of the internal gas pressure due to oxygen gas evolution. Moreover, air-stable surface-modified Na0.8Mg0.2Fe0.4Mn0.4O2 is introduced to suppress crack formation, leading to excellent electrochemical performance, such as stable capacity retention over 200 cycles.

Graphical abstract: Direct observation of the in-plane crack formation of O3-Na0.8Mg0.2Fe0.4Mn0.4O2 due to oxygen gas evolution for Na-ion batteries

Supplementary files

Article information

Article type
Paper
Submitted
30 Mar 2021
Accepted
08 Jun 2021
First published
08 Jun 2021

J. Mater. Chem. A, 2021,9, 14074-14084

Direct observation of the in-plane crack formation of O3-Na0.8Mg0.2Fe0.4Mn0.4O2 due to oxygen gas evolution for Na-ion batteries

S. Lee, S. W. Doo, M. S. Jung, S. G. Lim, K. Kim and K. T. Lee, J. Mater. Chem. A, 2021, 9, 14074 DOI: 10.1039/D1TA02639A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements