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Local spring effect in titanium-based layered oxides
DOI:10.1039/d0ee02313b.png)
Abstract
En 中文
Titanium-based layered oxides (TLOs) are one of the most promising electrode material families for sodium-ion batteries (NIBs) due to their smooth charge/discharge profiles and excellent cycle performance. However, the reaction mechanism of these materials, especially the reason for the disappearance of multiple voltage plateaus, is still not clear. Herein, two representative TLOs (Na2/3Ni1/3Ti2/3O2 and Na2/3Co1/3Ti2/3O2) with the same P2 crystal structure have been studied to scrutinize those unexplained issues. In situ synchrotron high-energy X-ray diffraction revealed a solid solution reaction mechanism for both, suggesting the absence of rigid phase transitions upon electrochemical cycling. An interesting spring effect of the TiO6 octahedron, i.e., the reversible vibration of the central Ti atom inside the local octahedron upon electrochemical redox, was demonstrated by advanced X-ray absorption spectroscopy and theoretical calculations. Such an effect could suppress the rigid phase transitions, and result in smooth charge/discharge profiles and enhanced cycle stability. This work not only accounts for the disappearance of multiple voltage plateaus of TLOs for NIBs, but also provides an effective local-structure viewpoint to increase the cycle stability of electrode materials for other advanced battery systems.
Keywords:
RATE CATHODE MATERIAL
SODIUM-ION BATTERIES
HIGH-ENERGY CATHODE
NEGATIVE ELECTRODE
METAL-OXIDE
COMPOSITE
INTERCALATION
ANODE
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Journal
IF:
30.8
Papers:
6.9K
Citations:
12.4W
Organization
Cited Papers
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Energy Environ. Sci.
IF30.8

