Li trapping in nanolayers of cation ‘disordered’ rock salt cathodes

Diaz‐Lopez, Maria; Chater, Philip A.; Proux, Olivier; Joly, Yves; Hazemann, Jean‐Louis; Bordet, Pierre; Raveau, B.

doi:10.1039/d2ta04262b

Cited by 10 publications

(7 citation statements)

References 47 publications

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“…In addition, the better Li + percolation in the spinel-like δ phase improves the rate performance and increases the capacity 39 . High-resolution STEM analysis indicates local variation in the extent of the δ phase ordering, which is likely closely linked to the non-uniform distribution of various TM species caused by cation SRO 27,[40][41][42] in the pristine DRX structure.…”

Section: Discussionmentioning

confidence: 99%

In situ formed partially disordered phases as earth-abundant Mn-rich cathode materials

Cai,

Ouyang,

Hau

et al. 2023

Nat Energy

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Earth-abundant cathode materials are urgently needed to enable scaling of the Li-ion industry to multiply terawatt hours of annual production, necessitating reconsideration of how good cathode materials can be obtained. Irreversible transition metal migration and phase transformations in Li-ion cathodes are typically believed to be detrimental because they may trigger voltage hysteresis, poor kinetics and capacity degradation. Here we challenge this conventional consensus by reporting an unusual phase transformation from disordered Li- and Mn-rich rock salts to a new phase (named δ), which displays partial spinel-like ordering with short coherence length and exhibits high energy density and rate capability. Unlike other Mn-based cathodes, the δ phase exhibits almost no voltage fade upon cycling. We identify the driving force and kinetics of this in situ cathode formation and establish design guidelines for Li- and Mn-rich compositions that combine high energy density, high rate capability and good cyclability, thereby enabling Mn-based energy storage.

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Section: Discussionmentioning

confidence: 99%

In situ formed partially disordered phases as earth-abundant Mn-rich cathode materials

Cai,

Ouyang,

Hau

et al. 2023

Nat Energy

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“…Compared to NMTP, the Na–O and Mn–O peaks of NMTVP show a shift to longer distance, while the Ti–O peak shift toward a shorter distance. [ 44–46 ]…”

Section: Resultsmentioning

confidence: 99%

V Doping in NASICON‐Structured Na₃MnTi(PO₄)₃ Enables High‐Energy and Stable Sodium Storage

Cai

et al. 2023

Adv Funct Materials

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NASICON‐structured Na3MnTi(PO4)3 represents an appealing cathode for sodium storage. However, the low potential from Ti3+/4+ redox pair (≈2.1 V versus Na+/Na), undesirable rate capability, and unfavorable cyclability have inhibited its practical application. Herein, this study designs a Na3.1MnTi0.9V0.1(PO4)3 (NMTVP) cathode material by doping V into the Na3MnTi(PO4)3. The V substitution not only increases the medium discharge voltage, but also increases the capacity. The as‐prepared NMTVP demonstrates a four‐step redox reaction from the redox couples of V5+/4+ (≈4.1 V), Mn4+/3+ (≈4.0 V), Mn3+/2+ (≈3.6 V), and V4+/3+ (3.4 V). The NMTVP delivers a high capacity (118.5 mAh g−1 at 0.1 C), a high medium discharge voltage (3.53 V), a decent energy density (422 Wh kg−1), and an ideal cyclability (86% retention after 4500 cycles at 5 C). In situ X‐ray diffraction (XRD) uncovers the reversible structural evolution between Na3.1MnTi0.9V0.1(PO4)3 and Na0.9MnTi0.9V0.1(PO4)3 phases. The assembled NMTVP//hard carbon (HC) full cell also delivers a high capacity, a high operating voltage, and a good cyclability. This contribution offers new insights into the design of high‐energy NASICON‐structured cathode materials.

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“…The rules for SRO formation have not been fully elucidated. The ways of SRO pattern manifestation are various − and closely related to the DRX material composition. Some high-valence d 0 cations, like Ti 4+ , Nb 5+ , and Mo 6+ , were found critical in promoting cation mixing and breaking SRO .…”

Section: Introductionmentioning

confidence: 99%

“…The electron diffraction technique could validate the existence of SRO on a larger scale yet only in a semiquantitative manner. , A method to quantitatively describe local structure variation throughout the global range is still needed. One means to hit this mark is the Monte Carlo (MC) supercell modeling combined with neutron pair distribution function (PDF) analysis, which contains abundant local structural information. , However, limited by computational expense, it is still challenging for this method to achieve robust large-scale statistical reliability, considering the current supercell size (several hundreds of atoms at maximum). Different from MC methods based on energy minimization, the reverse Monte Carlo (RMC) modeling method, directly analyzing the experimental total scattering data, , could describe local structure at both micro- and mesoscale.…”

Section: Introductionmentioning

confidence: 99%

Expandable Li Percolation Network: The Effects of Site Distortion in Cation-Disordered Rock-Salt Cathode Material

et al. 2023

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Cation-disordered rock-salt (DRX) materials receive intensive attention as a new class of cathode candidates for high-capacity lithium-ion batteries (LIBs). Unlike traditional layered cathode materials, DRX materials have a three-dimensional (3D) percolation network for Li+ transportation. The disordered structure poses a grand challenge to a thorough understanding of the percolation network due to its multiscale complexity. In this work, we introduce the large supercell modeling for DRX material Li1.16Ti0.37Ni0.37Nb0.10O2 (LTNNO) via the reverse Monte Carlo (RMC) method combined with neutron total scattering. Through a quantitative statistical analysis of the material’s local atomic environment, we experimentally verified the existence of short-range ordering (SRO) and uncovered an element-dependent behavior of transition metal (TM) site distortion. A displacement from the original octahedral site for Ti4+ cations is pervasive throughout the DRX lattice. Density functional theory (DFT) calculations revealed that site distortions quantified by the centroid offsets could alter the migration barrier for Li+ diffusion through the tetrahedral channels, which can expand the previously proposed theoretical percolating network of Li. The estimated accessible Li content is highly consistent with the observed charging capacity. The newly developed characterization method here uncovers the expandable nature of the Li percolation network in DRX materials, which may provide valuable guidelines for the design of superior DRX materials.

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Li trapping in nanolayers of cation ‘disordered’ rock salt cathodes

Abstract: Cation rearrangement during cycling of a Li1.1Mn0.7Ti0.2O2 cathode with a disordered rock-salt structure forms in situ a short-range ordered superstructure changing the connectivity of Li-migration channels and the electrochemical performance.

Cited by 10 publications

References 47 publications

In situ formed partially disordered phases as earth-abundant Mn-rich cathode materials

In situ formed partially disordered phases as earth-abundant Mn-rich cathode materials

V Doping in NASICON‐Structured Na₃MnTi(PO₄)₃ Enables High‐Energy and Stable Sodium Storage

Expandable Li Percolation Network: The Effects of Site Distortion in Cation-Disordered Rock-Salt Cathode Material

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Li trapping in nanolayers of cation ‘disordered’ rock salt cathodes

Abstract: Cation rearrangement during cycling of a Li1.1Mn0.7Ti0.2O2 cathode with a disordered rock-salt structure forms in situ a short-range ordered superstructure changing the connectivity of Li-migration channels and the electrochemical performance.

Cited by 10 publications

References 47 publications

In situ formed partially disordered phases as earth-abundant Mn-rich cathode materials

In situ formed partially disordered phases as earth-abundant Mn-rich cathode materials

V Doping in NASICON‐Structured Na3MnTi(PO4)3 Enables High‐Energy and Stable Sodium Storage

Expandable Li Percolation Network: The Effects of Site Distortion in Cation-Disordered Rock-Salt Cathode Material

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V Doping in NASICON‐Structured Na₃MnTi(PO₄)₃ Enables High‐Energy and Stable Sodium Storage