Effect of Lattice Structure of Bismuth Sesquioxide on the Electrochemical Energy Storage Characteristics
Bismuth sesquioxide (Bi 2 O 3 ) exists in different polymorphs such as monoclinic α phase, tetragonal β phase, face centered cubic ( fcc ) δ phase, and body centered cubic ( bcc ) γ phase. The stable phase at room temperature is α- phase, and at temperatures between 729-824 °C the δ phase is stable....
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Published in | Meeting abstracts (Electrochemical Society) Vol. MA2018-01; no. 44; p. 2555 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
13.04.2018
|
Online Access | Get full text |
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Summary: | Bismuth sesquioxide (Bi
2
O
3
) exists in different polymorphs such as monoclinic α phase, tetragonal β phase, face centered cubic (
fcc
) δ phase, and body centered cubic (
bcc
) γ phase. The stable phase at room temperature is α- phase, and at temperatures between 729-824 °C the δ phase is stable. Other phases are metastable which transform from the δ phase during the cooling cycle. The metastable phases can be stabilized at room temperature either by doping with aliovalent cations in the Bi
2
O
3
lattice or by controlling the synthesis parameters.
Bi
2
O
3
polymorphs are used in several engineering applications such as electrode materials for sensors, photocatalysts, and solid state electrolytes for fuel cells. Furthermore, Bi
2
O
3
is a building block for advanced ferroelectric, and multiferroic materials. Our modeling calculations suggest that β-Bi
2
O
3
could show auxetic behavior in certain crystallographic planes. Bi
2
O
3
has been investigated as a potential supercapacitor electrode material because of its promising theoretical specific capacitance (1370 F/g). Depending on the morphology and the matrix in which a composite structure was formed, the reported capacity varied from 94 – 332 F/g [[1], [2]]. Most of the investigations focused on the morphology of the Bi
2
O
3
or the composite structure of the electrode. The investigated material was either alpha [[3]] or delta phase [[4]], but no particular attention was given to the crystal structure. The effect of the lattice structure of the Bi
2
O
3
on the energy storage properties was not investigated in detail to the best of our knowledge. A recent report focused on the engineered lattice defects to enhance the capacitance [4]. In this presentation, the results of electrochemical energy storage behavior of Bi
2
O
3
electrodes prepared in the form of pure α-phase, a mixture of α+β, β-phase, and δ by electrodeposition will be reported.
The α-Bi
2
O
3
thin film specimens were electrodeposited on to ITO-coated glass surfaces under galvanostatic condition at +5 mA/cm
2
in a 100 ml solution containing 0.1 M bismuth nitrate, 0.2 M tartaric acid, and NaOH to adjust the pH to 12.0 at room temperature. In order to obtain β-Bi
2
O
3
deposition, 0.05 M of Na
2
Cr
2
O
7
was added to the solution used for electrodepositing the α-phase and the electrodeposition was carried out under galvanostatic condition at 45 °C. Thin film electrodeposits with mixed α+β phases were obtained by varying the dichromate concentration in the electrolyte. The δ-Bi
2
O
3
was obtained by using a pH:14 solution containing bismuth salt on to a
fcc
lattice substrate (austenitic stainless steel) at 65 °C, following a similar procedure reported by Helfen et al. [[5]].
Cyclic voltammetry, and galvanostatic charge-discharge experiments were carried out on the thin film Bi
2
O
3
specimens in 0.5 M LiCl + 0.1 M NaOH solution at room temperature. The β-Bi
2
O
3
specimens showed significantly higher specific capacitance than the α-Bi
2
O
3
. The electrochemical behavior of different phases will be discussed based on the impedance spectroscopy, and Mott-Schottky results before and after charge-discharge cycles.
[1] S. X. Wang, C. C. Jin, W. J. Qian,
J. Alloys Compd.
2014
,
615
, 12
[2] M. Ciszewski, A. Mianowski, P. Szatkowski, G. Nawrat, J. Adamek,
Ionics
2015
,
21
, 557.
[3] S.T. Senthilkumar, R. Kalai Selvan, M. Ulaganathan, J.S. Melo,
Electrochimica Acta
115 (2014) 518– 524
[4] R. Liu, L. Ma, G. Niu, X.-L. Li, E. Li, Y.Bai, G. Yuan,
Adv. Funct. Mater.
2017
,
27
, 1701635
[5] A. Helfen et al.,
Solid State Ionics
176 (2005) 629–633 |
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ISSN: | 2151-2043 2151-2035 |
DOI: | 10.1149/MA2018-01/44/2555 |