Surface Doping to Enhance Structural Integrity and Performance of Li‐Rich Layered Oxide

Liu, Shuai; Liu, Zepeng; Shen, Xi; Li, Weihan; Gao, Yurui; Banis, Mohammad Norouzi; Li, Minsi; Chen, Kai; Zhu, Liang; Yu, Richeng; Wang, Zhaoxiang; Sun, Xueliang; Lü, Gang; Kong, Qingyu; Bai, Xuedong; Chen, Liquan

doi:10.1002/aenm.201802105

Cited by 260 publications

(201 citation statements)

References 36 publications

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“…The average discharge potential (3.70 V) (Figure 2c) is 150 mV higher than that of LMR. [18] These attractive performances are attributed to the native Li-Ti mixing and the unique electronic configuration of the Ti 4+ ions that ensures the integrity and stability of the LTR structure, as will be seen in the following discussion. In contrast, the discharge potential of Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 declines by 593 mV and the capacity retention is only 76%, Adv.…”

Section: Intrinsic Li-ti Mixing and Stabilized Electrochemical Performentioning

confidence: 93%

“…Figure 3f compares the Raman spectra of the as-prepared LTR and the LTR that undergoes various cycles. No signals for the spinel phase can be detected (at 630 cm −1 for LMR [18] ) even after 100 full charge/discharge cycles, revealing that the layered structure of LTR is well maintained. No signals for the spinel phase can be detected (at 630 cm −1 for LMR [18] ) even after 100 full charge/discharge cycles, revealing that the layered structure of LTR is well maintained.…”

Section: Structural Stabilitymentioning

confidence: 94%

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Li–Ti Cation Mixing Enhanced Structural and Performance Stability of Li‐Rich Layered Oxide

Liu

Shen

et al. 2019

Advanced Energy Materials

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Li‐rich layered metal oxides are one type of the most promising cathode materials in lithium‐ion batteries but suffer from severe voltage decay during cycling because of the continuous transition metal (TM) migration into the Li layers. A Li‐rich layered metal oxide Li1.2Ti0.26Ni0.18Co0.18Mn0.18O2 (LTR) is hereby designed, in which some of the Ti4+ cations are intrinsically present in the Li layers. The native Li–Ti cation mixing structure enhances the tolerance for structural distortion and inhibits the migration of the TM ions in the TMO2 slabs during (de)lithiation. Consequently, LTR exhibits a remarkable cycling stability of 97% capacity retention after 182 cycles, and the average discharge potential drops only 90 mV in 100 cycles. In‐depth studies by electron energy loss spectroscopy and aberration‐corrected scanning transmission electron microscopy demonstrate the Li–Ti mixing structure. The charge compensation mechanism is uncovered with X‐ray absorption spectroscopy and explained with the density function theory calculations. These results show the superiority of introducing transition metal ions into the Li layers in reinforcing the structural stability of the Li‐rich layered metal oxides. These findings shed light on a possible path to the development of Li‐rich materials with better potential retention and a longer lifespan.

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Section: Intrinsic Li-ti Mixing and Stabilized Electrochemical Performentioning

confidence: 93%

Section: Structural Stabilitymentioning

confidence: 94%

Li–Ti Cation Mixing Enhanced Structural and Performance Stability of Li‐Rich Layered Oxide

Liu

Shen

et al. 2019

Advanced Energy Materials

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“…[ 11–16 ] Li‐rich manganese‐based oxides, x Li 2 MnO 3 –(1 − x )Li[Ni 1/3 Co 1/3 Mn 1/3 ]O 2 , developed in recent years, can deliver an anomalously high capacity exceeding 250 mA h g −1 due to transfer of multielectron redox, involving both cationic and anionic redox processes, [ 17–21 ] and have attracted increasing attention as promising high‐capacity cathode materials. [ 22–28 ] However, it is now accepted that the use of Co and even Ni will hinder the sustainable development of power batteries due to high cost and limited resources, particularly for electric vehicles and large‐scale energy storage. Therefore, it seems intuitive to move toward low‐cost, resource rich, cobalt‐free and nickel‐free high‐capacity cathode materials.…”

Section: Figurementioning

confidence: 99%

A High‐Performance Li–Mn–O Li‐rich Cathode Material with Rhombohedral Symmetry via Intralayer Li/Mn Disordering

et al. 2020

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The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202000190. The search for new high-performance and low-cost cathode materials for Li-ion batteries is a challenging issue in materials research. Commonly used cobalt-or nickel-based cathodes suffer from limited resources and safety problems that greatly restrict their large-scale application, especially for electric vehicles and large-scale energy storage. Here, a novel Li-Mn-O Li-rich cathode material with R m3 symmetry is developed via intralayer Li/Mn disordering in the Mn-layer. Due to the special atomic arrangement and higher R m 3 symmetry with respect to the C2/m symmetry, the oxygen redox activity is modulated and the Li in the Li-layer is preferentially thermodynamically extracted from the crystal structure instead of Li in the Mn-layer. The as-obtained material delivers a reversible capacity of over 300 mAh g −1 at 25 mA g −1 and rate capability of up to 260 mAh g −1 at 250 mA g −1 within 2.0-4.8 V. The excellent performance is attributed to its highly structural reversibility, mitigation of Jahn-Teller distortion, lower bandgap, and faster Li-ion 2D channels during the lithium-ion de/intercalation process. This material is not only a promising cathode material candidate but also raises new possibilities for the design of low-cost and high-performance cathode materials.

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“…In spite of the above proposed models, there are still some important facts that cannot be ignored on understanding the voltage hysteresis. Although surface doping can well suppress the voltage decay, severe voltage hysteresis still occurs in the first cycle of the conventional Li‐rich layered oxide, Li 2 MnO 3 ⋅LiNi 1/3 Co 1/3 Mn 1/3 O 2 (or Li 1.2 Mn 0.54 Co 0.13 Ni 0.13 O 2 ). In addition, even if the intrinsic cation mixing can effectively restrain the voltage decay in the oxide, it cannot eliminate the voltage hysteresis 7a.…”

Section: Introductionmentioning

confidence: 96%

Eliminating Transition Metal Migration and Anionic Redox to Understand Voltage Hysteresis of Lithium‐Rich Layered Oxides

Han

Jiao

Liu

et al. 2020

Advanced Energy Materials

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Lithium‐rich layered oxides are promising candidate cathode materials for the Li‐ion batteries with energy densities above 300 Wh kg−1. However, issues such as the voltage hysteresis and decay hinder their commercial applications. Due to the entanglement of the transition metal (TM) migration and the anionic redox upon lithium extraction at high potentials, it is difficult to recognize the origin of these issues in conventional Li‐rich layered oxides. Herein, Li2MoO3 is chosen since prototype material to uncover the reason for the voltage hysteresis as the TM migration and anionic redox can be eliminated below 3.6 V versus Li+/Li in this material. On the basis of comprehensive investigations by neutron powder diffraction, scanning transmission electron microscopy, synchrotron X‐ray absorption spectroscopy, and density functional theory calculations, it is clarified that the ordering–disordering transformation of the Mo3O13 clusters induced by the intralayer Mo migration is responsible for the voltage hysteresis in the first cycle; the hysteresis can take place even without the anionic redox or the interlayer Mo migration. A similar suggestion is drawn for its iso‐structured Li2RuO3 (C2/c). These findings are useful for understanding of the voltage hysteresis in other complicated Li‐rich layered oxides.

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Surface Doping to Enhance Structural Integrity and Performance of Li‐Rich Layered Oxide

Cited by 260 publications

References 36 publications

Li–Ti Cation Mixing Enhanced Structural and Performance Stability of Li‐Rich Layered Oxide

Li–Ti Cation Mixing Enhanced Structural and Performance Stability of Li‐Rich Layered Oxide

A High‐Performance Li–Mn–O Li‐rich Cathode Material with Rhombohedral Symmetry via Intralayer Li/Mn Disordering

Eliminating Transition Metal Migration and Anionic Redox to Understand Voltage Hysteresis of Lithium‐Rich Layered Oxides

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