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Title: Understanding Surface Densified Phases in Ni-Rich Layered Compounds

Abstract

Understanding structural transformation at the surface of Ni-rich layered compounds is of particular importance for improving the performance of these cathode materials. In this Letter, we identify the surface phases using first-principles-based kinetic Monte Carlo simulations. We show that slow kinetics precludes the conventional Li 0.5NiO 2 spinel to form from its layered parent phase at room temperature. Instead, we suggest that densified phases of the types Ni 0.25NiO 2 and Ni 0.5NiO 2 can form by Ni back diffusion from the surface owing to oxygen loss at highly charged states. Our conclusion is supported by the good agreement between the simulated STEM images and diffraction patterns and previously reported experimental data. While these phases can be mistaken for spinel and rock salt structures in STEM, they are noticeably different from these common structure types. We believe that these results clarify a long-standing puzzle about the nature of surface phases on this important class of battery materials.

Authors:
ORCiD logo [1]; ORCiD logo [2];  [3];  [2]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Univ. of California, Berkeley, CA (United States)
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Publication Date:
Research Org.:
Univ. of California, Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1507621
Alternate Identifier(s):
OSTI ID: 1508846; OSTI ID: 1513136
Report Number(s):
LLNL-JRNL-764442
Journal ID: ISSN 2380-8195; AC52-07NA27344
Grant/Contract Number:  
SC0012583; AC52-07NA27344
Resource Type:
Published Article
Journal Name:
ACS Energy Letters
Additional Journal Information:
Journal Volume: 4; Journal Issue: 4; Journal ID: ISSN 2380-8195
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Materials science

Citation Formats

Xiao, Penghao, Shi, Tan, Huang, Wenxuan, and Ceder, Gerbrand. Understanding Surface Densified Phases in Ni-Rich Layered Compounds. United States: N. p., 2019. Web. doi:10.1021/acsenergylett.9b00122.
Xiao, Penghao, Shi, Tan, Huang, Wenxuan, & Ceder, Gerbrand. Understanding Surface Densified Phases in Ni-Rich Layered Compounds. United States. doi:10.1021/acsenergylett.9b00122.
Xiao, Penghao, Shi, Tan, Huang, Wenxuan, and Ceder, Gerbrand. Mon . "Understanding Surface Densified Phases in Ni-Rich Layered Compounds". United States. doi:10.1021/acsenergylett.9b00122.
@article{osti_1507621,
title = {Understanding Surface Densified Phases in Ni-Rich Layered Compounds},
author = {Xiao, Penghao and Shi, Tan and Huang, Wenxuan and Ceder, Gerbrand},
abstractNote = {Understanding structural transformation at the surface of Ni-rich layered compounds is of particular importance for improving the performance of these cathode materials. In this Letter, we identify the surface phases using first-principles-based kinetic Monte Carlo simulations. We show that slow kinetics precludes the conventional Li0.5NiO2 spinel to form from its layered parent phase at room temperature. Instead, we suggest that densified phases of the types Ni0.25NiO2 and Ni0.5NiO2 can form by Ni back diffusion from the surface owing to oxygen loss at highly charged states. Our conclusion is supported by the good agreement between the simulated STEM images and diffraction patterns and previously reported experimental data. While these phases can be mistaken for spinel and rock salt structures in STEM, they are noticeably different from these common structure types. We believe that these results clarify a long-standing puzzle about the nature of surface phases on this important class of battery materials.},
doi = {10.1021/acsenergylett.9b00122},
journal = {ACS Energy Letters},
number = 4,
volume = 4,
place = {United States},
year = {2019},
month = {2}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1021/acsenergylett.9b00122

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