In:
Journal of Materials Chemistry A, Royal Society of Chemistry (RSC), Vol. 10, No. 2 ( 2022), p. 912-927
Abstract:
Al 0.17 V 2 O 5 (H 2 O) 2 ·H 2 O (AlVO) and Ca 0.23 V 2 O 5 (H 2 O)·H 2 O (CaVO) are synthesized herein, and their Rietveld refinements reveal that they are composed of V–O–V layers, lamellar hydrated Al 3+ or Ca 2+ and dissociated water molecules. The preintercalation of metal ions into V 2 O 5 leads to the elongation of V–O bonds, and all the V centers are unsaturated coordinated. The V–O–V bilayer in V 2 O 5 is split into two discrete V–O–V monolayers with the (001) facet as the division plane. Meanwhile, the exposed V centers on the (001) surface are unsaturated with oxygen vacancies, which can facilitate the migration of Zn 2+ along the (001) surface of AlVO with a lower energy barrier of 0.88 eV, as evidenced by density functional theory (DFT) simulations. AlVO shows a dominant pseudocapacitive behavior with excellent rate capability and outstanding cycling performance. It can deliver a high capacity of 441 mA h g −1 at 0.1 A g −1 with capacity retentions of 96.7% and 90.5% after 1000 and 2000 discharge/charge cycles at 5 A g −1 , respectively, which are superior to that of CaVO. In addition, DFT calculations also reveal that the intercalation of Zn 2+ on some sites in the interlayer channels of AlVO and CaVO is irreversible with very negative binding energies, leading to the accumulation of Zn 2+ in AlVO and CaVO. Furthermore, ex situ characterization of AlVO and quasi-reversible change of the pH value during the 1 st discharge/charge process indicate a co-(de)intercalation mechanism of H + and Zn 2+ . The pH-induced V species and the accumulation of Zn 2+ give rise to partial transformation of AlVO → Al 3+ -doped Zn 3 (OH) 2 V 2 O 7 ·2H 2 O, which is also observed for CaVO.
Type of Medium:
Online Resource
ISSN:
2050-7488
,
2050-7496
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
2702232-8
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