Accepted Manuscript
Title: One-pot facile synthesis of iron oxide nanowires as high
capacity anode materials for lithium ion batteries
Authors: Hao Liu, David Wexler, Guoxiu Wang
PII: S0925-8388(09)01602-8
DOI: doi:10.1016/j.jallcom.2009.08.043
Reference: JALCOM 20491
To appear in: Journal of Alloys and Compounds
Received date: 24-5-2009
Revised date: 10-8-2009
Accepted date: 11-8-2009
Please cite this article as: H. Liu, D. Wexler, G. Wang, One-pot facile synthesis of iron
oxide nanowires as high capacity anode materials for lithium ion batteries, Journal of
Alloys and Compounds (2008), doi:10.1016/j.jallcom.2009.08.043
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Accepted Manuscript

1
One-pot facile synthesis of iron oxide nanowires as high capacity
anode materials for lithium ion batteries
Hao Liu
*
, David Wexler, Guoxiu Wang

*

be attributed to the large surface area and short pathways in nanowires for lithium ion
migration.

Keywords:
α
-Fe
2
O
3
; Nanowires; Hydrothermal synthesis; Lithium ion batteries
* Corresponding author, email:
, , Fax: 61-2-42215731 Page 2 of 14
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1. Introduction
Due to the low cost and abundance of the raw materials, the Fe
2
O
3
has been widely
investigated in many technological fields such as anode materials for lithium ion batteries, gas
sensors, catalysts and magnetic applications [1-6]. In the past decade, one-dimensional (1D)
nanomaterials have attracted great interest because of their unique morphologies and
properties in nanoscience and nanotechnology [7-9]. Iron oxides also have been synthesized
in a variety of 1D morphologies such as nanowires [10,11], nanoneedles [12]
，

3
is as high as 1005 mAh/g,
which is much higher than that of the theoretical capacity of graphite anode materials (372

mAh/g). The extraction of lithium ion from Li
2
O is thermodynamically impossible. However,
it becomes feasible for nanosize materials, as has been reported previously [17]. Capacity
fading is the main issue for all transition metal oxides proposed as anode materials for lithium
ion batteries. Using nanoscale Fe
2
O
3
materials, especially 1D structured materials, is a
feasible approach to improve its properties as an anode material, because nanostructured
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materials can provide short pathway and high kinetics for lithium ion insertion/extraction.
In this paper, we first report a facile method with low cost starting materials (FeCl
3
and
nitrilotriacetic acid) to synthesize α-Fe
2
O
3
nanowires as anode material for lithium ion
batteries. The electrochemical performance of the
α

h. The
resultant white floccules were washed with deionized water and absolute ethanol, and dried at
60
℃
in a vacuum oven. Finally, the precursors were sintered at 500
℃
for 2

h to obtain
α-Fe
2
O
3
nanowires.
The α-Fe
2
O
3
nanowire

anode electrodes were made up by mixing the active materials with
acetylene black (AB) and a binder, poly(vinylidene fluoride) (PVdF), at weight ratios of
40:40:20, in N-methyl-2-pyrrolidone (NMP) solvent. The resultant slurry was uniformly
pasted on Cu foil with a blade. These prepared electrode sheets were dried at 120
℃
in a
vacuum oven for 12 hours and pressed under a pressure of approximately 200

kg/cm
2


mV/s within the range of 0.01 to 3.0

V, using an
electrochemistry workstation (Princeton Applied Research 2273).
3. Results and discussion
Fig. 1 shows the XRD pattern of the Fe
2
O
3
nanowires, using Cu Kα radiation (λ=1.5406

Å).
The diffraction pattern confirmed that the crystal structure is coincident with the standard
hematite (α-Fe
2
O
3
) rhombohedral structure (JCPDS Card No. 33-0664). No impurity was
detected from the XRD pattern, indicating that the nanowires are of a single-phase
rhombohedral crystal structure after the 500
℃
annealing.
The SEM images of the nanowires and precursors are shown in Fig. 2(a). It clearly
demonstrated that the FeNTA precursors from the hydrothermal reaction are entirely in the
form of well dispersed nanowires. In the hydrothermal processing, Fe
3+
ions were bonded and
anchored to amino groups or carboxyl groups from the reactant of NTA, and formed 1D
long-chain polymer precursors. After being sintered at 500℃ for 2

magnification. It shows that the single nanowire has a polycrystalline structure with a width
around 200

nm. The length/diameter ratio is as high as 500. The upper right inset in Fig. 2(d)
shows a high resolution TEM (HRTEM) image of the inner part of the single nanowire. The
HRTEM image clearly shows the microstructure of the individual grains, which confirms the
polycrystalline structure of the nanowires. The spacing of the lattice planes in the image was
determined to be 0.37

nm, which is consistent with the standard value for the (012) plane
(0.368

nm). The polycrystal Fe
2
O
3
nanowires exhibit a high specific surface area of 152m
2
/g
from the BET calculation. The high surface area nanowires can provide more reaction sites
for lithium ion transport.
Cyclic voltammetry (CV) is a basic instrumental method that can reveal the
electrochemical mechanism of reactions. Fig. 3 shows the first three cycles of CV curves of
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the nanowires in the range of 0.01-3

V. It is clear that there is a substantial difference between

between cathodic/anodic peaks is bigger than in the subsequent cycles, which indicates that
the initial capacity loss can be mostly attributed to the electrolyte decomposition. For the
one-dimensional Fe
2
O
3
nanowires, the high surface energy causes irreversible capacity loss
by decomposing the electrolyte. The SEI layer could cover the reactive sites and avoid further
decomposition. On the other hand, the nanowires with high surface area can provide more
sites for lithium ion intercalation/deintercalation. The short pathways in the nanowires can
also enhance lithium ion diffusion.
The Fe
2
O
3
nanowires were tested as anode materials for lithium ion batteries. The capacity
performance and charge/discharge curves for the first cycle are shown in Fig. 4. The
charge/discharge curves are shown in the inset, and they exhibit the charge/discharge plateaus
at 1.76/0.78

V. In CV testing, the anodic/cathodic peaks are present at 1.75/0.62

V, respectively.
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The difference can be attributed to the hysteresis in CV testing, which is caused by the
mismatch between the mass transfer and charge transfer processes on the electrode/electrolyte
interphase. The initial discharge capacity is 1303

2
O
3
nanowires material appears to be a promising candidate as a high capacity anode
material for lithium ion batteries.
4. Conclusions
α-Fe
2
O
3
nanowires were successfully prepared by a hydrothermal method and subsequent
heat treatment. The nanowires are as long as 100

µm, and the diameter is less than 200

nm.
The Fe
2
O
3
nanowires were tested as anode materials for lithium ion batteries. The initial
discharge capacity is 1303

mAh/g, which is higher than the theoretical capacity of Fe
2
O
3
. The
discharge capacity retention after 100 cycles is 456


1313-1317.
[9]
P.G. Collins, M.S. Arnold, P. Avouris, Science 292 (2001) 706-709.
[10] Q. Han, Z.H. Liu, Y.Y. Xu, Z.Y. Chen, T.M. Wang, H. Zhang, J. Phys. Chem. C 111 (2007)
5034-5038.
Page 9 of 14
Accepted Manuscript

9
[11] Y.Y. Fu, R.M. Wang, J .Xu, J. Chen, Y. Yan, A.V. Narlikar, H. Zhang, Chem. Phy. Lett.
279 (2003) 373-379.
[12] X.H. Sun, W.T. Liu, D.X. Ouyang, J. Alloys Compd. 478 (2009) 38-40.
[13] J.J. Wu, Y.L. Lee, H.H. Chiang, D.K.P Wong, J. Phys. Chem. B 110 (2006) 18108-18111.
[14] X.L. Gou, G.X. Wang, J. Yang, J.S. Park, D. Wexler, Chem. Eur. J. 14 (2008) 5996-6002.
[15] X.P. Shen, H.J. Liu, L Pan, K.M. Chen, J.M. Hong, Z. Xu, Chem.Lett. 33 (2004)
1128-1129.
[16] J. Bachmann, J. Jing, M. Knez, S. Barth, H. Shen, S. Mathur, U. Goesele, K. Nielsch, J.
Am. Chem. Soc. 129 (2007) 9554-9555.
[17] P. Poizot, S. Laruelle, S. Grugeon, L. Dupont, J.M. Tarascon, Nature 407 (2000) 496-499.
[18] L.C. Yang, Q.S.Gao, Y.H. Zhang, Y. Tang, Y.P. Wu, Electrochem. Commun. 10 (2008)
118-122.
[19] D. Larcher, D. Bonnin, R. Cortes, I. Rivals, L. Personnaz, J.M. Tarascon, J. Electrochem.
Soc. 150 (2003) A1643-A1650.
[20] D. Larcher, C. Masquelier, D. Bonnin, Y. Chabre, V. Masson, J.B. Leriche, J.M. Tarascon,
J. Electrochem. Soc. 150 (2003) A133-A139.
[21] P.C. Wang, H.P. Ding, T. Bark, C.H. Chen, Electrochim. Acta 52 (2007) 6650-6655.
[22] M. Hibino, J. Terashima, T. Yao, J. Electrochem. Soc. 154 (2007) A1107-A1111.
[23] W.W. Zhou, K.B. Tang, S.A. Zeng, Y.X. Qi, Nanotechnology 19 (2008) 065602.
[24]
H. Morimoto, S.I. Tobishima, Y. Iizuka, J. Power Sources 146 (2005) 315-318.

O
3
nanowires as anode for lithium ion cell.
Fig. 4. The charge/discharge performance of Fe
2
O
3
nanowires. The top-right inset is the first
cycle charge/discharge profiles.
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Fig. 1. X-ray diffraction pattern of alpha phase iron oxide nanowires.
20 30 40 50 60 70
(300)
(214)
(018)
(116)
(024)
(113)
(012)
(110)
(104)
Intensity / a.u.
2

/ degree
Figure(s)
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-2.0
-1.5
-1.0
-0.5
0.0
0.5
3rd
3rd
2nd
2nd
1st
1st
Current / mA
Potential / V
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0 20 40 60 80 100
0
200
400
600
800
1000
1200
1400
0 200 400 600 800 1000 1200 1400
0.0
0.5