The Impact of Surface Structure Transformations on the Performance of Li-Excess Cation-Disordered Rocksalt Cathodes

Deok-Hwang Kwon; Jinhyuk Lee; Nongnuch Artrith; Hyunchul Kim; Lijun Wu; Zhengyan Lun; Yaosen Tian; Yimei Zhu; Gerbrand Ceder

Cell Reports Physical Science (Sep 2020)

The Impact of Surface Structure Transformations on the Performance of Li-Excess Cation-Disordered Rocksalt Cathodes

Deok-Hwang Kwon,
Jinhyuk Lee,
Nongnuch Artrith,
Hyunchul Kim,
Lijun Wu,
Zhengyan Lun,
Yaosen Tian,
Yimei Zhu,
Gerbrand Ceder

Affiliations

Deok-Hwang Kwon: Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA 94720, USA; Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Corresponding author
Jinhyuk Lee: Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA 94720, USA; Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Department of Mining and Materials Engineering, McGill University, Montréal, QC H3A 0C5, Canada
Nongnuch Artrith: Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA 94720, USA; Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
Hyunchul Kim: Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
Lijun Wu: Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY 11973, USA
Zhengyan Lun: Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA 94720, USA; Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
Yaosen Tian: Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA 94720, USA; Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
Yimei Zhu: Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY 11973, USA
Gerbrand Ceder: Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA 94720, USA; Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Corresponding author

Journal volume & issue: Vol. 1, no. 9
p. 100187

Abstract

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Summary: Li-excess cation-disordered rocksalt (DRX) oxides have shown potential as high-energy-density Li-ion cathodes. They typically exploit O redox to achieve high capacity, which can trigger oxygen loss at the surface, thereby affecting the cathode performance. Here, we elucidate the impact that the surface structural evolution has on their electrochemical properties by comparing two prototypical DRX cathodes, Li1.2Ni0.333Ti0.333Mo0.133O2 (LNTMO) and Li1.2Mn0.6Nb0.2O2 (LMNO). Both cathodes achieve high capacity, but oxygen loss leads to significant polarization for LNTMO, whereas LMNO is far less affected. We show that while metal densification at the particle surface occurs for both materials, the resulting surface structure is strikingly different. A spinel phase forms at the surface of LMNO, which effectively alleviates oxygen loss and allows fast Li transport, whereas a densified DRX forms at the LNTMO surface, which impedes Li transport and cannot mitigate oxygen loss. These findings demonstrate the importance of the surface structure of DRX cathode.

Published in Cell Reports Physical Science

ISSN: 2666-3864 (Online)
Publisher: Elsevier
Country of publisher: United States
LCC subjects: Science: Physics
Website: https://www.cell.com/cell-reports-physical-science

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