Journal
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
Volume 166, Issue 3, Pages A5343-A5348Publisher
ELECTROCHEMICAL SOC INC
DOI: 10.1149/2.0521903jes
Keywords
-
Funding
- JSPS [JP15K05138, JP15K13798, JP15H05701]
- MEXT KAKENHI [JP15K05138, JP15K13798, JP15H05701]
- MEXT, Japan, under the Elements Strategy Initiative for Catalysts and Batteries (ESICB)
- HPCI systems through the HPCI System Research Projects [hp170122, hp170169]
Ask authors/readers for more resources
Resorting to oxygen redox in addition to that of transition metal in oxide cathode materials can increase the capacity of rechargeable Na ions batteries. Through comprehensive density functional calculations, we demonstrate dominant oxygen participation in the redox reaction in cation disordered hexagonal and ordered monoclinic polymorphs of Na2-xRuO3 (0 <= x <= 0.75). In both polymorphs, when O ions are coordinated by more than three Na ions, unhybridized orphaned O 2p states are lifted closer to the Fermi level and therefore become accessible for the redox reaction. Moreover, high Ru-O covalency promotes greater 2p-4d hybridization at the top of the valence band further increasing the density of states of the electrochemically labile O 2p orbitals near the Fermi level. Consequently, throughout cycling, the contribution of the O 2p states to the charge compensation mechanism becomes nearly as twice as that of Ru 4d states in both polymorphs. Due to broader dispersion of the O 2p states near the Fermi level, the cation disordered polymorph, nonetheless, has a higher voltage of 2.458 V compared to the voltage of the cation ordered polymorph of 2.243 V. (C) The Author(s) 2019. Published by ECS.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available