Fluorination effect for stabilizing cationic and anionic redox activities in cation-disordered cathode materials

Zhou, Ke; Zheng, Shiyao; Ren, Fucheng; Wu, Jue; Liu, Haodong; Luo, Mingzeng; Liu, Xiangsi; Xiang, Yuxuan; Zhang, Chunyang; Yang, Wanli; He, Lunhua; Yang, Yong

doi:10.1016/j.ensm.2020.07.012

Cited by 52 publications

(51 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[54] Previous work shows that F mostly influences the high-voltage activity and inhibits oxygen gas release. [10,22,28,55,56] As expected, both LNTMOF and LNTOF exhibit a similar initial charge capacity (~300 mAh/g) (Figure 6a). Upon discharging, since LNTOF has less Ni compared to LNTMOF (0.35 vs. 0.45 per formula unit), less capacity originating from the Ni redox is obtained at the high-voltage plateau.…”

Section: Discussion Of Mo Cation Migration and Anionic O Redoxsupporting

confidence: 75%

“…52,53 The fingerprint of the oxidized O feature (red arrows in Figure 5a) at the excitation and emission energies of 56 And F mostly influences the high-voltage activity and prevents oxygen gas release. 10,22,29,57,58 As expected, both LNTMOF and LNTOF exhibit a similar charge capacity, 335 mAh g −1 for LNTMOF vs 317 mAh g −1 for LNTOF (Figure 6a). During discharge, because LNTOF has 0.1 less Ni than LNTMOF (0.35 vs 0.45 per formula unit), less capacity from the Ni redox is obtained at the high-voltage plateau.…”

Section: Resultssupporting

confidence: 68%

“…This LNTOF composition is selected because the charge capacity is largely determined by Li content, not Ni content, given the fact that O oxidation could compensate the charge mechanism for extractable Li + . And F mostly influences the high-voltage activity and prevents oxygen gas release. ,,,, As expected, both LNTMOF and LNTOF exhibit a similar charge capacity, 335 mAh g –1 for LNTMOF vs 317 mAh g –1 for LNTOF (Figure a). During discharge, because LNTOF has 0.1 less Ni than LNTMOF (0.35 vs 0.45 per formula unit), less capacity from the Ni redox is obtained at the high-voltage plateau.…”

Section: Results and Discussionsupporting

confidence: 57%

See 2 more Smart Citations

Interplay between Cation and Anion Redox in Ni-Based Disordered Rocksalt Cathodes

Yue

Huang

et al. 2021

ACS Nano

Self Cite

View full text Add to dashboard Cite

The reversibility of the redox processes plays a crucial role in the electrochemical performance of lithium-excess cation-disordered rocksalt (DRX) cathodes. Here, we report a comprehensive analysis of the redox reactions in a representative Ni-based DRX cathode. The aim of this work is to elucidate the roles of multiple cations and anions in the charge compensation mechanism that is ultimately linked to the unique electrochemical performance of Ni-based DRX cathode. The low-voltage reduction reaction results in the low energy efficiency and strong voltage hysteresis. Our data reveal that the Mo migration between octahedral and tetrahedral sites enhances the O reduction potential, thus offering a potential strategy to improve energy 1 efficiency. This work highlights the important role that the electrochemically inactive transition metal plays in the redox chemistry and provides useful insights into the potential pathway to further address the challenges in Ni-based DRX systems.

show abstract

Section: Discussion Of Mo Cation Migration and Anionic O Redoxsupporting

confidence: 75%

Section: Resultssupporting

confidence: 68%

Section: Results and Discussionsupporting

confidence: 57%

See 1 more Smart Citation

Interplay between Cation and Anion Redox in Ni-Based Disordered Rocksalt Cathodes

Yue

Huang

et al. 2021

ACS Nano

Self Cite

View full text Add to dashboard Cite

show abstract

“…Interestingly, the degree of lattice oxygen oxidation is negatively correlated to the electrochemical properties of the investigated cathode materials, which is contrary to the conventional wisdom. [ 33 ]…”

Section: Resultsmentioning

confidence: 99%

Enhancing the Reversibility of Lattice Oxygen Redox Through Modulated Transition Metal–Oxygen Covalency for Layered Battery Electrodes

et al. 2022

View full text Add to dashboard Cite

Utilizing reversible lattice oxygen redox (OR) in battery electrodes is an essential strategy to overcome the capacity limitation set by conventional transition metal redox. However, lattice OR reactions are often accompanied with irreversible oxygen oxidation, leading to local structural transformations and voltage/capacity fading. Herein, it is proposed that the reversibility of lattice OR can be remarkably improved through modulating transition metal–oxygen covalency for layered electrode of Na‐ion batteries. By developing a novel layered P2‐Na0.6Mg0.15Mn0.7Cu0.15O2 electrode, it is demonstrated that the highly electronegative Cu dopants can improve the lattice OR reversibility to 95% compared to 73% for Cu‐free counterpart, as directly quantified through high‐efficiency mapping of resonant inelastic X‐ray scattering. Crucially, the large energetic overlap between Cu 3d and O 2p states dictates the rigidity of oxygen framework, which effectively mitigates the structural distortion of local oxygen environment upon (de)sodiation and leads to the enhanced lattice OR reversibility. The electrode also exhibits a completely solid‐solution reaction with an ultralow volume change of only 0.45% and a reversible metal migration upon cycling, which together ensure the improved electrochemical performance. These results emphasize the critical role of transition metal–oxygen covalency for enhancing the reversibility of lattice OR toward high‐capacity electrodes employing OR chemistry.

show abstract

“…There are several approaches for the stabilization of lattice oxygen that can be differentiated with respect to the manner of electrode modification. Concerning the oxide bulk, the reversible oxygen redox reactions in LiTMOs can be facilitated when the lattice oxygen is selectively replaced by fluorine or when the cations are disordered across transition metal and lithium layers [18,19]. The fluorination of LiTMOs affects not only the lattice oxygen but also evokes suppression in the irreversible gas release and surface reactions [18].…”

Section: Introductionmentioning

confidence: 99%

Metal Substitution versus Oxygen-Storage Modifier to Regulate the Oxygen Redox Reactions in Sodium-Deficient Three-Layered Oxides

et al. 2022

View full text Add to dashboard Cite

Sodium-deficient nickel-manganese oxides with three-layered stacking exhibit the unique property of dual nickel-oxygen redox activity, which allows them to achieve enormous specific capacity. The challenge is how to stabilize the oxygen redox activity during cycling. This study demonstrates that oxygen redox activity of P3-Na2/3Ni1/2Mn1/2O2 during both Na+ and Li+ intercalation can be regulated by the design of oxide architecture that includes target metal substituents (such as Mg2+ and Ti4+) and oxygen storage modifiers (such as CeO2). Although the substitution for nickel with Ti4+ amplifies the oxygen redox activity and intensifies the interaction of oxides with NaPF6- and LiPF6-based electrolytes, the Mg2+ substituents influence mainly the nickel redox activity and suppress the deposition of electrolyte decomposed products (such as MnF2). The CeO2-modifier has a much stronger effect on the oxygen redox activity than that of metal substituents; thus, the highest specific capacity is attained. In addition, the CeO2-modifier tunes the electrode–electrode interaction by eliminating the deposition of MnF2. As a result, the Mg-substituted oxide modified with CeO2 displays high capacity, excellent cycling stability and exceptional rate capability when used as cathode in Na-ion cell, while in Li-ion cell, the best performance is achieved for Ti- substituted oxide modified by CeO2.

show abstract

Fluorination effect for stabilizing cationic and anionic redox activities in cation-disordered cathode materials

Cited by 52 publications

References 59 publications

Interplay between Cation and Anion Redox in Ni-Based Disordered Rocksalt Cathodes

Interplay between Cation and Anion Redox in Ni-Based Disordered Rocksalt Cathodes

Enhancing the Reversibility of Lattice Oxygen Redox Through Modulated Transition Metal–Oxygen Covalency for Layered Battery Electrodes

Metal Substitution versus Oxygen-Storage Modifier to Regulate the Oxygen Redox Reactions in Sodium-Deficient Three-Layered Oxides

Contact Info

Product

Resources

About