Thermodynamic Activation of Charge Transfer in Anionic Redox Process for Li‐Ion Batteries

Anionic redox processes are vital to realize high capacity in lithium‐rich electrodes of lithium‐ion batteries. However, the activation mechanism of these processes remains ambiguous, hampering further implementation in new electrode design. This study demonstrates that the electrochemical activity...

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Bibliographic Details
Published in:Advanced functional materials 2018-01, Vol.28 (4), p.n/a
Main Authors: Li, Biao, Jiang, Ning, Huang, Weifeng, Yan, Huijun, Zuo, Yuxuan, Xia, Dingguo
Format: Article
Language:English
Subjects:
Activation
anionic redox processes
Aquatic plants
Charge transfer
Chemical bonds
Electrodes
First principles
Lithium
Lithium-ion batteries
Materials science
Oxygen ions
Rechargeable batteries
Substitutes
thermodynamic activation
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Summary:Anionic redox processes are vital to realize high capacity in lithium‐rich electrodes of lithium‐ion batteries. However, the activation mechanism of these processes remains ambiguous, hampering further implementation in new electrode design. This study demonstrates that the electrochemical activity of inert cubic‐Li2TiO3 is triggered by Fe3+ substitution, to afford considerable oxygen redox activity. Coupled with first principles calculations, it is found that electron holes tend to be selectively generated on oxygen ions bonded to Fe rather than Ti. Subsequently, a thermodynamic threshold is unravelled dictated by the relative values of the Coulomb and exchange interactions (U) and charge‐transfer energy (Δ) for the anionic redox electron‐transfer process, which is further verified by extension to inactive layered Li2TiS3, in which the sulfur redox process is activated by Co substitution to form Li1.2Ti0.6Co0.2S2. This work establishes general guidance for the design of high‐capacity electrodes utilizing anionic redox processes. The charge transfer process of anionic redox processes is thermodynamically dictated by the relative values of the Coulomb and exchange interactions (U) and charge‐transfer energy (Δ), as experimentally validated by the activation of oxygen and sulfur redox in Li1.2Ti0.4Fe0.4O2 and Li1.2Ti0.6Co0.2S2, respectively. This work establishes general guidance for the design of high‐capacity electrodes utilizing anionic redox processes.
ISSN:1616-301X
1616-3028
DOI:10.1002/adfm.201704864