Title: Quantifying redox heterogeneity in single-crystalline LiCoO₂ cathode particles

Abstract

Active cathode particles are fundamental architectural units for the composite electrode of Li-ion batteries. The microstructure of the particles has a profound impact on their behavior and, consequently, on the cell-level electrochemical performance. LiCoO₂(LCO, a dominant cathode material) is often in the form of well-shaped particles, a few micrometres in size, with good crystallinity. In contrast to secondary particles (an agglomeration of many fine primary grains), which are the other common form of battery particles populated with structural and chemical defects, it is often anticipated that good particle crystallinity leads to superior mechanical robustness and suppressed charge heterogeneity. Yet, sub-particle level charge inhomogeneity in LCO particles has been widely reported in the literature, posing a frontier challenge in this field. Herein, this topic is revisited and it is demonstrated that X-ray absorption spectra on single-crystalline particles with highly anisotropic lattice structures are sensitive to the polarization configuration of the incident X-rays, causing some degree of ambiguity in analyzing the local spectroscopic fingerprint. To tackle this issue, a methodology is developed that extracts the white-line peak energy in the X-ray absorption near-edge structure spectra as a key data attribute for representing the local state of charge in the LCO crystal. This method demonstrates significantlymore » improved accuracy and reveals the mesoscale chemical complexity in LCO particles with better fidelity. In addition to the implications on the importance of particle engineering for LCO cathodes, the method developed herein also has significant impact on spectro-microscopic studies of single-crystalline materials at synchrotron facilities, which is broadly applicable to a wide range of scientific disciplines well beyond battery research.« less

Authors:

Wei, Chenxi  ^[1];

• Search DOE PAGES for author "Wei, Chenxi"
• Search DOE PAGES for ORCID "0000-0003-4294-1418"

Hong, Yanshuai ^[2]; Tian, Yangchao ^[3]; Yu, Xiqian ^[2]; Liu, Yijin  ^[2];

• Search DOE PAGES for author "Liu, Yijin"
• Search DOE PAGES for ORCID "0000-0002-8417-2488"

Pianetta, Piero ^[4]

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+ Show Author Affiliations

1. Univ. of Science and Technology of China, Hefei (China) ; SLAC National Accelerator Lab., Menlo Park, CA (United States)
2. Chinese Academy of Sciences (CAS), Beijing (China)
3. Univ. of Science and Technology of China, Hefei (China)
4. SLAC National Accelerator Lab., Menlo Park, CA (United States)

Publication Date:

Fri Mar 13 00:00:00 EDT 2020

Research Org.:

SLAC National Accelerator Lab., Menlo Park, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1633187

Grant/Contract Number:  

2017YFA0402904; 2016YFB0100100; AC02-76SF00515; 51822211; 11574281; 51421002

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Synchrotron Radiation (Online)

Additional Journal Information:

Journal Name: Journal of Synchrotron Radiation (Online); Journal Volume: 27; Journal Issue: 3; Journal ID: ISSN 1600-5775

Publisher:

International Union of Crystallography

Country of Publication:

United States

Language:

English

Subject:

73 NUCLEAR PHYSICS AND RADIATION PHYSICS; spectro-microscopy; X-ray polarization; single-crystalline LiCoO₂