Effect of composition on the structure of lithium- and manganese-rich transition metal oxides

Shukla, Alpesh Khushalchand; Ramasse, Quentin M.; Ophus, Colin; Kepaptsoglou, Demie; Hage, Fredrik S.; Gammer, Christoph; Bowling, Charles; Gallegos, Pedro Alejandro Hern andez; Venkatachalam, S.

doi:10.1039/c7ee02443f

Cited by 43 publications

(20 citation statements)

References 35 publications

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“…[ 10 ] As demonstrated in our previous study, [ 8 ] the degree of the honeycomb ordering denotes how many excess‐Li ions are localized and the excess‐Li localization can be identified as more intense, dumbbell‐like spots. [ 11 ] Instead, for DS‐LMR, additional spots between the two dumbbell‐like spots appeared with slightly lower intensities across the whole area of the sub‐micrometer particles (Figure 1d). This implied that DS‐LMR exhibited shorter‐range honeycomb orderings, forming a relatively delocalized, excess‐Li system (Figure S7, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Lattice‐Oxygen‐Stabilized Li‐ and Mn‐Rich Cathodes with Sub‐Micrometer Particles by Modifying the Excess‐Li Distribution

et al. 2021

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In recent years, Li‐ and Mn‐rich layered oxides (LMRs) have been vigorously explored as promising cathodes for next‐generation, Li‐ion batteries due to their high specific energy. Nevertheless, their actual implementation is still far from a reality since the trade‐off relationship between the particle size and chemical reversibility prevents LMRs from achieving a satisfactory, industrial energy density. To solve this material dilemma, herein, a novel morphological and structural design is introduced to Li1.11Mn0.49Ni0.29Co0.11O2, reporting a sub‐micrometer‐level LMR with a relatively delocalized, excess‐Li system. This system exhibits an ultrahigh energy density of 2880 Wh L−1 and a long‐lasting cycle retention of 83.1% after the 100th cycle for 45 °C full‐cell cycling, despite its practical electrode conditions. This outstanding electrochemical performance is a result of greater lattice‐oxygen stability in the delocalized excess‐Li system because of the low amount of highly oxidized oxygen ions. Geometric dispersion of the labile oxygen ions effectively suppresses oxygen evolution from the lattice when delithiated, eradicating the rapid energy degradation in a practical cell system.

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Section: Resultsmentioning

confidence: 99%

Lattice‐Oxygen‐Stabilized Li‐ and Mn‐Rich Cathodes with Sub‐Micrometer Particles by Modifying the Excess‐Li Distribution

et al. 2021

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“…[27][28][29] It is therefore suggested that it is the inclusion of increasing amounts of Mn, rather than decreasing Ni, would promote the higher concentration of Li observed in the samples as this phase is oen observed in Mn rich NMC. 30,31 A representation of the MO 6 slab for both R 3m and C2/m is shown in Fig. 2b where MO 6 polyhedra are shown in grey and Li + in green.…”

Section: Resultsmentioning

confidence: 99%

Stoichiometrically driven disorder and local diffusion in NMC cathodes

et al. 2021

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“…In the [100] monoclinic view of HAADF‐STEM, a localized excess‐Li domain (long‐range ordered LiMn 6 ) is displayed as dumbbell‐like two spots (TM‐TM‐Li), and a delocalized excess‐Li domain (short‐range ordered LiMn 6 ) as continuous spots with relatively lower intensities (TM/Li‐TM/Li‐TM/Li) (Figure S3, Supporting Information). [ 12 ] In the presented STEM images, while L‐LMR shows dumbbell‐like two spots in most areas, D‐LMR shows not only the dumbbell‐like two spots, but also the continuous spots (gray shaded areas) in a fairly large area. This indicates that L‐LMR is mainly composed of localized excess‐Li domains, and D‐LMR is composed of the mixtures of localized and delocalized excess‐Li domains.…”

Section: Figurementioning

confidence: 91%

Excess‐Li Localization Triggers Chemical Irreversibility in Li‐ and Mn‐Rich Layered Oxides

et al. 2020

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Li‐ and Mn‐rich layered oxides (LMRs) have emerged as practically feasible cathode materials for high‐energy‐density Li‐ion batteries due to their extra anionic redox behavior and market competitiveness. However, sluggish kinetics regions (<3.5 V vs Li/Li+) associated with anionic redox chemistry engender LMRs with chemical irreversibility (first‐cycle irreversibility, poor rate properties, voltage fading), which limits their practical use. Herein, the structural origin of this chemical irreversibility is revealed through a comparative study involving Li1.15Mn0.51Co0.17Ni0.17O2 with relatively localized and delocalized excess‐Li in its lattice system. Operando fine‐interval X‐ray absorption spectroscopy is used to simultaneously observe the interplay between transition‐metal–oxygen (TM‐O) redox chemistry and TM migration behavior in real time. Density functional theory calculations show that excess‐Li localization in the LMR structure attenuates TM‐O covalency and stability, leading to overall chemical irreversibility. Hence, the delocalized excess‐Li system is proposed as an alternative design for practically feasible LMR cathodes with restrained TM migration and sustainable O‐redox chemistry.

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Effect of composition on the structure of lithium- and manganese-rich transition metal oxides

Abstract: In this work, we establish a definitive structural model for lithium- and manganese-rich transition metal oxides and demonstrate the effect of composition on their bulk as well as the surface structure.

Cited by 43 publications

References 35 publications

Lattice‐Oxygen‐Stabilized Li‐ and Mn‐Rich Cathodes with Sub‐Micrometer Particles by Modifying the Excess‐Li Distribution

Lattice‐Oxygen‐Stabilized Li‐ and Mn‐Rich Cathodes with Sub‐Micrometer Particles by Modifying the Excess‐Li Distribution

Stoichiometrically driven disorder and local diffusion in NMC cathodes

Excess‐Li Localization Triggers Chemical Irreversibility in Li‐ and Mn‐Rich Layered Oxides

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