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Title: Tuning the Morphology and Electronic Properties of Single-Crystal LiNi 0.5Mn 1.5O 4-δ: Exploring the Influence of LiCl–KCl Molten Salt Flux Composition and Synthesis Temperature

Abstract

Single-crystal materials have played a unique role in the development of high-performance cathode materials for Li batteries due to their favorable chemomechanical stability. The molten salt synthesis method has become one of the most prominent techniques used to synthesize single-crystal layered and spinel materials. In this work, the molten salt synthesis method is used as a technique to tune both the morphology and Mn 3+ content of high-voltage LiNi 0.5Mn 1.5O 4 (LNMO) cathodes. The resulting materials are thoroughly characterized by a suite of analytical techniques, including synchrotron X-ray core-level spectroscopy, which are sensitive to the material properties on multiple length scales. Furthermore, the multidimensional characterization allows us to build a materials library according to the molten salt phase diagram as well as to establish the relationship among synthesis, material properties, and battery performance. The results of this work show that the Mn 3+ content is primarily dependent on the synthesis temperature and increases as the temperature is increased. Additionally, the particle morphology is mostly dependent on the composition of the molten salt flux, which can be tailored to obtain well-defined octahedrons enclosed by (111) facets, plates with predominant ($$11\tilde{2}$$) facets, irregularly shaped particles, or mixtures of these. The electrochemical measurements indicate that the Mn 3+ content has a larger contribution to the battery performance of LNMO than do morphological characteristics and that a significant amount of Mn 3+ could become detrimental to the battery performance. However, with similar Mn 3+ contents, morphology still plays a role in influencing the battery cycle life and rate performance. The insights of molten salt synthesis parameters on the formation of LNMO, with deconvolution of the roles of Mn 3+ and morphology, are crucial to continuing studies in the rational design of LNMO cathode materials for high-energy Li batteries.

Authors:
ORCiD logo [1];  [1];  [2];  [3]; ORCiD logo [1]
  1. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
  3. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94035, United States
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Science Foundation (NSF)
OSTI Identifier:
1656567
Grant/Contract Number:  
AC02-76SF00515; DMR-1832613
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Volume: 59; Journal Issue: 15; Journal ID: ISSN 0020-1669
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
Salts; morphology; transition metals; fluxes; materials

Citation Formats

Spence, Stephanie L., Xu, Zhengrui, Sainio, Sami, Nordlund, Dennis, and Lin, Feng. Tuning the Morphology and Electronic Properties of Single-Crystal LiNi0.5Mn1.5O4-δ: Exploring the Influence of LiCl–KCl Molten Salt Flux Composition and Synthesis Temperature. United States: N. p., 2020. Web. doi:10.1021/acs.inorgchem.0c01042.
Spence, Stephanie L., Xu, Zhengrui, Sainio, Sami, Nordlund, Dennis, & Lin, Feng. Tuning the Morphology and Electronic Properties of Single-Crystal LiNi0.5Mn1.5O4-δ: Exploring the Influence of LiCl–KCl Molten Salt Flux Composition and Synthesis Temperature. United States. doi:10.1021/acs.inorgchem.0c01042.
Spence, Stephanie L., Xu, Zhengrui, Sainio, Sami, Nordlund, Dennis, and Lin, Feng. Thu . "Tuning the Morphology and Electronic Properties of Single-Crystal LiNi0.5Mn1.5O4-δ: Exploring the Influence of LiCl–KCl Molten Salt Flux Composition and Synthesis Temperature". United States. doi:10.1021/acs.inorgchem.0c01042.
@article{osti_1656567,
title = {Tuning the Morphology and Electronic Properties of Single-Crystal LiNi0.5Mn1.5O4-δ: Exploring the Influence of LiCl–KCl Molten Salt Flux Composition and Synthesis Temperature},
author = {Spence, Stephanie L. and Xu, Zhengrui and Sainio, Sami and Nordlund, Dennis and Lin, Feng},
abstractNote = {Single-crystal materials have played a unique role in the development of high-performance cathode materials for Li batteries due to their favorable chemomechanical stability. The molten salt synthesis method has become one of the most prominent techniques used to synthesize single-crystal layered and spinel materials. In this work, the molten salt synthesis method is used as a technique to tune both the morphology and Mn3+ content of high-voltage LiNi0.5Mn1.5O4 (LNMO) cathodes. The resulting materials are thoroughly characterized by a suite of analytical techniques, including synchrotron X-ray core-level spectroscopy, which are sensitive to the material properties on multiple length scales. Furthermore, the multidimensional characterization allows us to build a materials library according to the molten salt phase diagram as well as to establish the relationship among synthesis, material properties, and battery performance. The results of this work show that the Mn3+ content is primarily dependent on the synthesis temperature and increases as the temperature is increased. Additionally, the particle morphology is mostly dependent on the composition of the molten salt flux, which can be tailored to obtain well-defined octahedrons enclosed by (111) facets, plates with predominant ($11\tilde{2}$) facets, irregularly shaped particles, or mixtures of these. The electrochemical measurements indicate that the Mn3+ content has a larger contribution to the battery performance of LNMO than do morphological characteristics and that a significant amount of Mn3+ could become detrimental to the battery performance. However, with similar Mn3+ contents, morphology still plays a role in influencing the battery cycle life and rate performance. The insights of molten salt synthesis parameters on the formation of LNMO, with deconvolution of the roles of Mn3+ and morphology, are crucial to continuing studies in the rational design of LNMO cathode materials for high-energy Li batteries.},
doi = {10.1021/acs.inorgchem.0c01042},
journal = {Inorganic Chemistry},
issn = {0020-1669},
number = 15,
volume = 59,
place = {United States},
year = {2020},
month = {7}
}

Journal Article:
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