Browsing by Author "Liang, GM"

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    Developing high-voltage spinel LiNi0.5Mn1.5O4 cathodes for high-energy-density lithium-ion batteries: current achievements and future prospects
    (Royal Society of Chemistry, 2020-05-22) Liang, GM; Peterson, VK; See, KW; Guo, ZP; Pang, WK
    High-voltage spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cathode for the next-generation high-performance lithium-ion batteries (LIBs) due to its high energy density (650 W h kg−1), high operating voltage (∼4.7 V vs. Li), low fabrication cost, and low environmental impact. However, the short cycle life of LNMO caused by rapid capacity decay during cycling limits its wide application and commercialization. Intense research effort to improve the electrochemical performance of LNMO has been moderately successful. Accordingly, it is absolutely necessary to revisit and summarize the up-to-date findings and deeper understanding of how to modify LNMO. In this review, the crystallographic structure and electrochemical properties of LNMO spinel, as well as its existing issues and corresponding solutions, are discussed in detail. In addition, the current accomplishments relating to LNMO application in full-cell configurations are also discussed. Finally, some insight into the future prospects for LNMO cathode developments is provided. © The Royal Society of Chemistry 2020
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    Effect of AlF3-coated Li4Ti5O12 on the performance and function of the LiNi0.5Mn1.5O4||Li4Ti5O12 full battery—an in-operando neutron powder diffraction study
    (Frontiers Media S.A., 2018-09-10) Liang, GM; Pillai, AS; Peterson, VK; Ko, KY; Chang, CM; Lu, CZ; Liu, CE; Liao, SC; Chen, JM; Guo, ZP; Pang, WK
    The LiNi0.5Mn1.5O4 ||Li4Ti5O12 (LMNO||LTO) battery possesses a relatively-high energy density and cycle performance, with further enhancement possible by application of an AlF3 coating on the LTO electrode particles. We measure the performance enhancement to the LMNO||LTO battery achieved by a AlF3 coating on the LTO particles through electrochemical testing and use in-operando neutron powder diffraction to study the changes to the evolution of the bulk crystal structure during battery cycling. We find that the AlF3 coating along with parasitic Al doping slightly increases capacity and greatly increases rate capability of the LTO electrode, as well as significantly reducing capacity loss on cycling, facilitating a gradual increase in capacity during the first 50 cycles. Neutron powder diffraction reveals a structural response of the LTO and LNMO electrodes consistent with a greater availability of lithium in the battery containing AlF3-coated LTO. Further, the coating increases the rate of structural response of the LNMO electrode during charge, suggesting faster delithiation, and enhanced Li diffusion. This work demonstrates the importance of studying such battery performance effects within full configuration batteries. Copyright © 2018 Liang, Pillai, Peterson, Ko, Chang, Lu, Liu, Liao, Chen, Guo and Pang.
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    A high-performance and long-cycle-life spinel lithium-ion battery cathode achieved by site-selective doping
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Liang, GM; Dider, C; Gou, ZP; Peterson, VK; Pang, WK
    Lithium-ion batteries (LIBs) form an important part of our daily life, powering portable electronic devices, as well as electric and hybrid electric vehicles. However, the limited energy density of current LIBs results in their failure to meet the increasing requirements of rapidly developing technologies. Since the performance limitation in existing LIB technology is the cathode, exploring high-energy-density cathode candidates becomes extremely important. Spinel LiNi0.5Mn1.5O4 (LNMO) is considered one of the most promising cathode materials for next-generation high energy-density LIBs, owing to its high operating voltage of 4.7 V vs. Li, low fabrication cost, and high energy density approaching 650 Wh kg-1, which is beyond that of most other LIB cathode materials, such as LiFePO4 at ∼560 Wh kg-1, LiMn2O4 at ∼480 Wh kg-1, and LiMn1/3Ni1/3Co1/3O2 at ∼510 Wh kg-1. Unfortunately, LNMO suffers from rapid capacity decay and unsatisfactory cycle stability, limiting its practical application and commercialization. Various doping strategies have been widely adopted to enhance the electrochemical stability of LNMO. Although the electrochemical performance of LNMO is enhanced through doping, the mechanism by which the performance is improved remains unclear, with the chemistry- and structure-function relationships for chemically modified LNMOs relatively unknown. In this work, we not only demonstrate a site-selective doping strategy for an easily-prepared high-performance LNMO cathode through Mg doping, but also comprehensively reveal the underlying enhancement mechanisms using a series of in operando and ex situ characterization techniques. Mg dopants, selectively residing at 8a and 16c sites of the Fd-3m structure, change the way how LNMO responses to the lithium intercalation and de-intercalation during charge-discharge processes. Meanwhile, the addition of Mg ions at such sites significantly prohibits the partially-irreversible two-phase behavior of LNMO, mitigates against the dissolution of transition metals, thus preventing the formation of the undesirable rock-salt phase and reducing the Jahn-Teller distortion and voltage polarization, consequently offering the extraordinary structure stability to LNMO. Consequently, the modified LNMO exhibits excellent extended-long-term electrochemical performance, retaining ~ 86 % and ~ 87 % of initial capacity after 1500 cycles at 1 C and 2200 cycles at 10 C, respectively in half cell configuration, which is reported for the first time and demonstrates their great commercial potential. Such excellent cycle and rate performance are also reflected in a prototype full-battery with a novel TiNb2O7 counter electrode. This work provides a new strategy for the chemical modification of electrode materials that may be applied more generally in battery researches, whereby dopants may be used strategically to address specific electrode issues.
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    Introducing 4s–2p orbital hybridization to stabilize spinel oxide cathodes for lithium-ion batteries
    (Wiley-VCH GmbH, 2022-04-25) Liang, GM; Olsson, E; Zou, JS; Wu, ZB; Li, JX; Lu, CZ; D'Angelo, AM; Johannessen, B; Thomsen, L; Cowie, BCC; Peterson, VK; Cai, Q; Pang, WK; Guo, ZP
    Oxides composed of an oxygen framework and interstitial cations are promising cathode materials for lithium-ion batteries. However, the instability of the oxygen framework under harsh operating conditions results in fast battery capacity decay, due to the weak orbital interactions between cations and oxygen (mainly 3d–2p interaction). Here, a robust and endurable oxygen framework is created by introducing strong 4s–2p orbital hybridization into the structure using LiNi0.5Mn1.5O4 oxide as an example. The modified oxide delivers extraordinarily stable battery performance, achieving 71.4 % capacity retention after 2000 cycles at 1 C. This work shows that an orbital-level understanding can be leveraged to engineer high structural stability of the anion oxygen framework of oxides. Moreover, the similarity of the oxygen lattice between oxide electrodes makes this approach extendable to other electrodes, with orbital-focused engineering a new avenue for the fundamental modification of battery materials. © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH - Open access.
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    A long cycle-life high-voltage spinel lithium-ion battery electrode achieved by site-selective doping
    (John Wiley & Sons, Inc, 2020-03-23) Liang, GM; Wu, ZB; Didier, C; Zhang, WC; Cuan, J; Li, BH; Ko, KY; Hung, PY; Lu, CZ; Chen, YZ; Leniec, G; Kaczmarek, SM; Johannessen, B; Thomsen, L; Peterson, VK; Pang, WK; Guo, ZP
    Spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cathode candidate for the next-generation high energy-density lithium-ion batteries (LIBs). Unfortunately, the application of LNMO is hindered by its poor cycle stability. Now, site-selectively doped LNMO electrode is prepared with exceptional durability. In this work, Mg is selectively doped onto both tetrahedral (8a) and octahedral (16c) sites in the Fdurn:x-wiley:14337851:media:anie202001454:anie202001454-math-0001 m structure. This site-selective doping not only suppresses unfavorable two-phase reactions and stabilizes the LNMO structure against structural deformation, but also mitigates the dissolution of Mn during cycling. Mg-doped LNMOs exhibit extraordinarily stable electrochemical performance in both half-cells and prototype full-batteries with novel TiNb2O7 counter-electrodes. This work pioneers an atomic-doping engineering strategy for electrode materials that could be extended to other energy materials to create high-performance devices. © 2020 Wiley-VCH Verlag GmbH & Co
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    A robust coin-cell design for in situ synchrotron-based x-ray powder diffraction analysis of battery materials
    (John Wiley & Sons, Inc, 2020-10-22) Liang, GM; Hao, JN; D'Angelo, AM; Peterson, VK; Guo, ZP; Pang, WK
    Understanding structure/chemistry-function relationships of active battery materials is crucial for designing higher-performance batteries, with in situ synchrotron-based X-ray powder diffraction widely employed to gain this understanding. Such measurements cannot be performed using a conventional cell, with modifications necessary for the X-ray diffraction measurement, which unfortunately compromises battery performance and stability. Consequently, these measurements may not be representative of the typical behaviour of active materials in unmodified cells, particularly under more extreme operating conditions, such as at high voltage. Herein, we report a low-cost, simple, and robust coin-cell design enabling representative and typical cell performance during in situ X-ray powder diffraction measurements, which we demonstrate for the well-known high-voltage electrode material LiNi0.5Mn1.5O4. In addition to excellent cell stability at high voltage, the modified cell delivered an electrochemical response comparable to the standard 2032-type coin cell. This work paves an efficient way for battery researchers to perform high-quality in situ structural analysis with synchrotron X-ray radiation and will enable further insight into complex electrochemical processes in batteries. © 2020 Wiley-VCH GmbH
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    Understanding rechargeable battery function using in operando neutron powder diffraction
    (John Wiley & Sons, Inc, 2020-05-07) Liang, GM; Didier, C; Guo, ZP; Peterson, VK
    The performance of rechargeable batteries is influenced by the structural and phase changes of components during cycling. Neutron powder diffraction (NPD) provides unique and useful information concerning the structure–function relation of battery components and can be used to study the changes to component phase and structure during battery cycling, known as in operando measurement studies. The development and use of NPD for in operando measurements of batteries is summarized along with detailed experimental approaches that impact the insights gained by these. A summary of the information gained concerning battery function using in operando NPD measurements is provided, including the structural and phase evolution of electrode materials and charge-carrying ion diffusion pathways through these, which are critical to the development of battery technology. © 2019 Wiley-VCH Verlag GmbH & Co.