A high-performance and long-cycle-life spinel lithium-ion battery cathode achieved by site-selective doping
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Date
2020-11-11
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Publisher
Australian Institute of Nuclear Science and Engineering (AINSE)
Abstract
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.
Description
Keywords
Hybrid electric-powered vehicles, Density, Materials, Polarization, Cathodes, Energy density
Citation
Liang, G., Dider, C., Gou, Z., Peterson, V., & Pang, W. K. (2020). A high-performance and long-cycle-life spinel lithium-ion battery cathode achieved by site-selective doping. Paper presented to the ANBUG-AINSE Neutron Scattering Symposium, AANSS 2020, Virtual Meeting, 11th - 13th November 2020. (pp. 88). Retrieved from: https://events01.synchrotron.org.au/event/125/attachments/725/1149/AANSS_Abstract_Booklet_Complete_-_1_Page_Reduced.pdf