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Title: Dual-ion intercalation to enable high-capacity VOPO4 cathodes for Na-ion batteries
Authors: Zhang, Z
Ni, Y
Avdeev, M
Kan, WH
He, G
Keywords: Cathodes
Lithium ion batteries
Electric batteries
Redox potential
Issue Date: 1-Jan-2021
Publisher: Elsevier
Citation: Zhang, Z., Ni, Y., Avdeev, M., Kan, W. H., & He, G. (2021). Dual-ion intercalation to enable high-capacity VOPO4 cathodes for Na-ion batteries. Electrochimica Acta, 365, 137376, doi:10.1016/j.electacta.2020.137376
Abstract: VOPO4 is a potential cathode candidate in sodium-ion batteries for multi-electron reactions to attain high capacity up to 330 mAh g−1. However, most current efforts are focused on the V5+/V4+ redox reaction with a moderate capacity of <150 mAh g−1. Here, we report for the first time the Na intercalation behaviors for both αI- and β-VOPO4 polymorph cathodes through the V5+/V4+/V3+ redox reactions. Electrochemical evaluations suggest further reduction of V4+ ions can be attained for both cathodes, as indicated by the high discharge capacities derived from a large plateau below 1.5 V vs Na/Na+ as well as various structural analyses of electrodes at different discharge states. However, only the layered αI- cathode is preferable for deep sodiation to maintain stable structure over cycling. Theoretical studies by bond-valence sum (BVS) mismatch map calculations reveal similar Na-ion migration pathways in VOPO4•2H2O and αI-NaVOPO4, but H2O molecules in the hydrate cathode have negative effect on the diffusion of Na-ions in betweenVOPO4 layers. © 2020 Elsevier Ltd. All rights reserved.
ISSN: 0013-4686
Appears in Collections:Journal Articles

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