Metal‐Ligand π Interactions in Lithium‐Rich Li<sub>2</sub>RhO<sub>3</sub> Cathode Material Activate Bimodal Anionic Redox

Kun, Zhang; Jiang, Zewen; Ning, Fanghua; Li, Biao; Shang, Huaifang; Jin, Song; Zuo, Yuxuan; Yang, Tonghuan; Feng, Guang; Ai, Xinping; Xia, Dingguo

doi:10.1002/aenm.202100892

Cited by 28 publications

(40 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Covalency is considered to be important for stabilizing the oxidized anionic species in several postulated anionic redox mechanisms. High covalency is a prerequisite for the π-type interaction between TM cations and oxidized oxygen that requires drastic shortening of the TM–O distance and extensive overlap of the TM t 2 g and O 2 p orbitals. − Within the ligand-to-metal charge transfer (LMCT) scenario, the partially oxidized oxygen framework undergoes a cooperative distortion with shortening some of the O–O bonds. Moreover, it is further facilitated by the covalent mixing of the σ*-antibonding orbitals of these O–O dumbbells with TM n d orbitals with donating electrons from the anion back to oxidized TM. − Indeed, these mechanisms were established for the Ru (4 d )- and Ir (5 d )-based oxides as their d -orbitals are capable of providing the necessary strong overlap with the O 2 p orbitals.…”

Section: Introductionmentioning

confidence: 99%

Retardation of Structure Densification by Increasing Covalency in Li-Rich Layered Oxide Positive Electrodes for Li-Ion Batteries

et al. 2022

View full text Add to dashboard Cite

Because of the outstanding discharge capacity provided by oxygen redox activity, Li-rich layered oxide positive electrode materials for Li-ion batteries attract tremendous attention. However, there is still no full consensus on the role that the ionocovalency of transition metal (TM)−oxygen (O) chemical bonding plays in the reversibility of the oxygen redox as well as on both local crystal and electronic structure transformations. Here, we managed to tune the cationic/anionic redox contributions to the overall electrochemical activity using the xLi 2 RuO 3 -(1 − x)Li 1.2 Ni 0.2 Mn 0.6 O 2 solid solutions as a model system possessing the same crystal structure and morphology as Li-rich layered oxides. We conclusively traced the whole cascade of events from increasing the covalency of the TM−O bond, suppressing irreversible oxygen oxidation to the generation of the reduced Mn species toward retarding the structure "densification" in the Li-rich layered oxides. The results demonstrate that enhancing the degree of covalency of the TM−O bonding is vitally important for anchoring the reversibility of the charge compensation mechanism occurring through partial oxygen oxidation.

show abstract

Section: Introductionmentioning

confidence: 99%

Retardation of Structure Densification by Increasing Covalency in Li-Rich Layered Oxide Positive Electrodes for Li-Ion Batteries

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Among them, cation-disordered rocksalt (DR) Li 3 NbO 4 74 and Li 3 IrO 4 9 have been reported with anionic redox activity and large capacity, validating our hypothesis. Li 2 MnO 3 , 76 Li 2 RhO 3 , 77 Li 2 RuO 3 , 78 and Li 2 SnO 3 78 are well-known anionic redox layered electrodes, while their DR counterparts, to the best of our knowledge, have been synthesized and thus are worth exploring. Li 2 MoO 3 79 also adopts a layered structure and was found to experience migration of Mo from the metal layer to the lithium layer during slow and irreversible delithiation.…”

Section: Methodsmentioning

confidence: 99%

Exploring the Origin of Anionic Redox Activity in Super Li-Rich Iron Oxide-Based High-Energy-Density Cathode Materials

2022

View full text Add to dashboard Cite

Super alkali-rich materials (alkali:transition metal ratio of ≥2:1), such as Li 5 FeO 4 , exhibit the potential to realize anionic redox upon deep delithiation. Li 5 FeO 4 was shown to undergo reversible cycling between Li 4 FeO 3.5 and Li 3 FeO 3.5 with combined cation/anion redox, a remarkable capacity of 189 mAh/g, and no O 2 release. However, the impact of phase transformations on the reaction thermodynamics and the correlation between the structural changes and reaction reversibility remain unclear. In this study, we use first-principles calculations to examine the delithiation and (re)lithiation reactions of Li 5 FeO 4 . We show that the experimentally observed charge and discharge processes go through non-equilibrium pathways. Upon delithiation, the compound undergoes a phase transformation from Li 5 FeO 4 , with tetrahedrally coordinated (T d ) Fe ions, to a delithiated disordered rocksalt structure, with octahedral (O h ) Fe ions. Fe-ion migration has an asymmetric kinetic barrier that makes T d → O h migration facile, whereas the reverse process has a much larger barrier, explaining the difficulties in reaction reversibility. We further elucidate the transition metal and O redox sequences during the charge cycle and identify the complex electrochemistry associated with the dual participation of cationic redox (Fe 3+ /Fe 4+ ) and anionic redox (O 2− /O − /O 0 ). Armed with this knowledge, we conduct high-throughput screening of known alkali-rich transition metal oxides by evaluating their potential to enable reversible anionic redox, with multiple candidates proposed for further experimental trials. Our work provides a useful guide for the further development of super alkali-rich anionicredox-active electrodes for high-energy-density batteries.

show abstract

“…The redox activity of Li 2 RuO 3 can be regulated by the weaker covalency of the Sn-O bond. Furthermore, the intensely bonding Ir-O immensely suppresses the charge compensation ability of oxygen for Li 2 IrO 3 and all the capacity derives from the redox reaction of Ir hybridized with oxygen [29] . When Ir is partially replaced by Sn, the lower number of valence electrons at the end of charging significantly promotes the ligand-to-metal charge transfer, resulting in short Ir-O π bonds and O-O dimers with a bond length of 1.4 Å.…”

Section: Tm-o Hybridizationmentioning

confidence: 99%

“…(viii) Summary of Ru and O redox during the initial cycling profile with blue for lattice Ru 4+/5+ and yellow for lattice oxygen redox [28] . (E) Charge-discharge profiles of Li 2-x Ir 1-y Sn y O 3 for a full cycle (black) and for ~1.5 e in Ir per cycle (pink) [29] . (F) Enlarged ABF-STEM image.…”

Section: According To the Absorption Edge Analysis Of Each Element At...mentioning

confidence: 99%

“…The O-O pairs arise from twisting the opposite triangular faces of the IrO 6 octahedra (shown in yellow) [11] . (G) O K-edge mRIXS of Li 2 Ir 0.75 Sn 0.25 O 2 and Li 2 Ir 0.75 Sn 0.25 O 2 charged to 4.60 V showing a localized RIXS feature at 530.7 eV excitation energy and 522.8 eV emission energy [29] . mRIXS: Mapping of resonant inelastic X-ray scattering.…”

Section: According To the Absorption Edge Analysis Of Each Element At...mentioning

confidence: 99%

See 1 more Smart Citation

Multi-dimensional correlation of layered Li-rich Mn-based cathode materials

Yang¹,

Zheng²,

Wei³

et al. 2022

View full text Add to dashboard Cite

Lithium-rich manganese-based cathode materials are expected to promote the commercialization of lithium-ion batteries to a new stage by virtue of their ultrahigh specific capacity and energy density advantages. However, they are still restricted by complex phase transitions and electrochemical performance degradation caused by labile anion charge compensation. A deep understanding of the electrochemical properties contained in their intrinsic structures and the key driving factors of structural deterioration during cycling are crucial to guide the preparation and optimization of lithium-rich materials. Considering recent progress, this review introduces the intrinsic properties of Li-rich manganese-based cathode materials from interatomic interactions to particle morphology at multiple scales in the spatial dimension. The charge compensation mechanism and energy band reorganization of the initial charge and discharge, the structural evolution during cycling and the electrochemical reaction kinetics of the materials are analyzed in the temporal dimension. Based on the relationship between structure and electrochemical performance, preparation methods and modification methods are introduced to guide and design cathode materials. Effective characterization methods for studying anion charge compensation behavior are also demonstrated. This review provides important guidance and suggestions for making full use of the high specific capacity in these materials derived from anion redox and the maintaining of its stability.

show abstract

Metal‐Ligand π Interactions in Lithium‐Rich Li₂RhO₃ Cathode Material Activate Bimodal Anionic Redox

Cited by 28 publications

References 48 publications

Retardation of Structure Densification by Increasing Covalency in Li-Rich Layered Oxide Positive Electrodes for Li-Ion Batteries

Retardation of Structure Densification by Increasing Covalency in Li-Rich Layered Oxide Positive Electrodes for Li-Ion Batteries

Exploring the Origin of Anionic Redox Activity in Super Li-Rich Iron Oxide-Based High-Energy-Density Cathode Materials

Multi-dimensional correlation of layered Li-rich Mn-based cathode materials

Contact Info

Product

Resources

About

Metal‐Ligand π Interactions in Lithium‐Rich Li2RhO3 Cathode Material Activate Bimodal Anionic Redox

Cited by 28 publications

References 48 publications

Retardation of Structure Densification by Increasing Covalency in Li-Rich Layered Oxide Positive Electrodes for Li-Ion Batteries

Retardation of Structure Densification by Increasing Covalency in Li-Rich Layered Oxide Positive Electrodes for Li-Ion Batteries

Exploring the Origin of Anionic Redox Activity in Super Li-Rich Iron Oxide-Based High-Energy-Density Cathode Materials

Multi-dimensional correlation of layered Li-rich Mn-based cathode materials

Contact Info

Product

Resources

About

Metal‐Ligand π Interactions in Lithium‐Rich Li₂RhO₃ Cathode Material Activate Bimodal Anionic Redox