Title: Rational synthesis and electrochemical performance of LiVOPO₄ polymorphs

Abstract

LiVOPO₄ is a promising cathode material for Li-ion batteries due to its ability to intercalate up to two electrons per vanadium redox center. However, LiVOPO₄ exhibits polymorphism, forming either the α_I, β, or ε phase. A thorough comparison between the properties of these phases is difficult because they usually differ in synthesis methods. Here, we synthesize all three polymorphs by annealing a single precursor, LiVOPO₄·2H₂O, thereby reducing the effect of synthesis on the properties of the materials. We show through in situ XRD with heating and DFT calculations that, in terms of stability, α_I-LiVOPO₄ $$\lll$$ ε-LiVOPO₄ ≤ β-LiVOPO₄. We also show experimentally and through DFT calculations that the tolerance to O-interstitials and O-vacancies can explain the differences in stability, morphology, and electrochemical performance between β- and ε-LiVOPO₄. β-LiVOPO₄ is more stable in the presence of O-interstitials while ε-LiVOPO₄ is favored in the presence of O-vacancies. These defects affect the surface energies and morphology of the products formed, which are confirmed in the Wulff shape calculations and transmission electron microscopy images. These imply that β-LiVOPO₄ has an improved rate performance under an oxidizing atmosphere due to the increased presence of facets with superior ion diffusion at the surface. This improved performance is seen by the improved rate capability and capacity of β-LiVOPO₄ in the high-voltage region. In contrast, synthesis conditions have little effect on improving the rate performance of ε-LiVOPO₄.

Authors:

Hidalgo, Marc Francis V.  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-5801-442X"

Lin, Yuh-Chieh  ^[2];

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Grenier, Antonin ^[3]; Xiao, Dongdong ^[1]; Rana, Jatinkumar  ^[1];

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Tran, Richard ^[2]; Xin, Huolin ^[4]; Zuba, Mateusz ^[1]; Donohue, Jennifer ^[1]; Omenya, Fredrick O. ^[1]; Chu, Iek-Heng ^[2]; Wang, Zhenbin ^[5]; Li, XiangGuo ^[2]; Chernova, Natasha A. ^[1]; Chapman, Karena W. ^[3]; Zhou, Guangwen  ^[1];

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Piper, Louis  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-3421-3210"

Ong, Shyue Ping  ^[2];

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• Search DOE PAGES for ORCID "0000-0001-5726-2587"

Whittingham, M. Stanley  ^[1]

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• Search DOE PAGES for ORCID "0000-0002-5039-9334"

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+ Show Author Affiliations

1. Binghamton Univ., NY (United States)
2. Univ. of California San Diego, La Jolla CA (United States)
3. Argonne National Lab. (ANL), Lemont, IL (United States). Advanced Photon Source (APS)
4. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
5. Univ. of California, San Diego, CA (United States)

Publication Date:

Wed Mar 06 00:00:00 EST 2019

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Northeastern Center for Chemical Energy Storage (NECCES); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; National Science Foundation (NSF)

OSTI Identifier:

1529230

Alternate Identifier(s):

OSTI ID: 1501958

Grant/Contract Number:  

AC02-05CH11231; SC0012583; AC02-06CH11357; SC0012704; ACI-1053575

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Materials Chemistry. A

Additional Journal Information:

Journal Volume: 7; Journal Issue: 14; Journal ID: ISSN 2050-7488

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY