Doping Li-rich cathode material 
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: Interplay between lattice site preference, electronic structure, and delithiation mechanism

Hoang, Khang

doi:10.1103/physrevmaterials.1.075404

Cited by 25 publications

(36 citation statements)

References 46 publications

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“…In this mixed-metal compound, Mn is found to be stable as high-spin Mn 3+ (3d 4 ) and Mo as Mo 5+ (4d 1 ). The change in the charge states of the transition metal ions due to the Mn-Mo interaction is consistent with that previously observed in Mo-doped Li 2 MnO 3 35. The elec-FIG.…”

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confidence: 89%

Electronic Structure and Properties of Lithium-Rich Complex Oxides

Hoang

Choi

2018

ACS Appl. Electron. Mater.

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Lithium-rich complex transition-metal oxides Li2MoO3, Li2RuO3, Li3RuO4, Li3NbO4, Li5FeO4, Li5MnO4 and their derivatives are of interest for high-capacity battery electrodes. Here, we report a first-principles density-functional theory study of the atomic and electronic structure of these materials using the Heyd-Scuseria-Ernzerhof (HSE) screened hybrid functional which treats all orbitals in the materials on equal footing. Dimerization of the transition-metal ions is found to occur in layered Li2MoO3, in both fully lithiated and partially delithiated compounds. The Ru-Ru dimerization does not occur in fully lithiated Li2RuO3, in contrast to what is commonly believed; Ru-Ru dimers are, however, found to occur in the presence of lithium vacancies caused by lithium loss during synthesis and/or lithium removal during use. We also analyze the electronic structure of the complex oxides and discuss the delithiation mechanism in these battery electrode materials.

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confidence: 89%

Electronic Structure and Properties of Lithium-Rich Complex Oxides

Hoang

Choi

2018

ACS Appl. Electron. Mater.

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“…The electrochemical performance can, however, be improved via doping with electrochemically active ions [79,122]. The purpose of doping is to introduce additional charge compensation and electronic conduction mechanisms highly needed at the early stages of delithiation [41,46]; see also section 7.3.…”

Section: Delithiation Mechanism and Extraction Voltagementioning

confidence: 99%

“…In the calculations, supercell models with different cell sizes can be used to describe a range from lightly to heavily doped materials; they may contain an isolated impurity or a complex consisting of impurities or impurities and native defects. From a materials modeling perspective, lightly doped compounds can effectively serve as model systems for understanding more complex, mixed-metal materials [33,45,46]. In this section, we discuss the lattice site preference and defect structure of select transition-metal and nontransition-metal impurities in a number of battery electrode materials and the effects of doping on the electronic and ionic conduction and the delithiation mechanism.…”

Section: Theory Of Doping In Complex Materialsmentioning

confidence: 99%

“…In another example [46] [147,148] and widely studied experimentally. This example thus illustrates how charge and spin states of a transition-metal impurity can be affected by defect-defect interaction [46].…”

Section: Lattice Site Preference and Defect Structurementioning

confidence: 99%

“…The redox couples associated with different voltage points are indicated; unmarked voltage points in the shaded area are those associated with the redox activity on oxygen. Reprinted with permission from [46].…”

Section: Modification Of the Delithiation Mechanismmentioning

confidence: 99%

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Defect physics in complex energy materials

Hoang

Johannes

2018

J. Phys.: Condens. Matter

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Understanding the physics of structurally and chemically complex transition-metal oxide and polyanionic materials such as those used for battery electrodes is challenging, even at the level of pristine compounds. Yet these materials are also prone to and their properties and performance are strongly affected or even determined by crystallographic point defects. In this review, we highlight recent advances in the study of defects and doping in such materials using first-principles calculations. The emphasis is on describing a theoretical and computational approach that has the ability to predict defect landscapes under various synthesis conditions, provide guidelines for defect characterization and defect-controlled synthesis, uncover the mechanisms for electronic and ionic conduction and electrochemical extraction and (re-)insertion, and provide an understanding of the effects of doping. Though applied to battery materials here, the approach is general and applicable to any materials in which the defect physics plays a role or drives the properties of interest. Thus, this work is intended as an in-depth review of defect physics in particular classes of materials, but also as a methodological template for the understanding and design of complex functional materials.

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Fully Exploited Oxygen Redox Reaction by the Inter‐Diffused Cations in Co‐Free Li‐Rich Materials for High Performance Li‐Ion Batteries

et al. 2020

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To meet the growing demand for global electrical energy storage, high‐energy‐density electrode materials are required for Li‐ion batteries. To overcome the limit of the theoretical energy density in conventional electrode materials based solely on the transition metal redox reaction, the oxygen redox reaction in electrode materials has become an essential component because it can further increase the energy density by providing additional available electrons. However, the increase in the contribution of the oxygen redox reaction in a material is still limited due to the lack of understanding its controlled parameters. Here, it is first proposed that Li‐transition metals (TMs) inter‐diffusion between the phases in Li‐rich materials can be a key parameter for controlling the oxygen redox reaction in Li‐rich materials. The resulting Li‐rich materials can achieve fully exploited oxygen redox reaction and thereby can deliver the highest reversible capacity leading to the highest energy density, ≈1100 Wh kg−1 among Co‐free Li‐rich materials. The strategy of controlling Li/transition metals (TMs) inter‐diffusion between the phases in Li‐rich materials will provide feasible way for further achieving high‐energy‐density electrode materials via enhancing the oxygen redox reaction for high‐performance Li‐ion batteries.

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Doping Li-rich cathode material Li2MnO3 : Interplay between lattice site preference, electronic structure, and delithiation mechanism

Cited by 25 publications

References 46 publications

Electronic Structure and Properties of Lithium-Rich Complex Oxides

Electronic Structure and Properties of Lithium-Rich Complex Oxides

Defect physics in complex energy materials

Fully Exploited Oxygen Redox Reaction by the Inter‐Diffused Cations in Co‐Free Li‐Rich Materials for High Performance Li‐Ion Batteries

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