Journal of Alloys and Compounds 479 (2009) 875–878
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Journal of Alloys and Compounds
journal homepage: www.elsevier.com/locate/jallcom
Sol–gel synthesis and electrochemical properties of CuV
2
O
6
cathode material
Cao Jun-qi
a
, Wang Xian-you
a,∗
, Tang Anping
a
, Wang Xin
a
, Wang Ying
b
, Wu Wen
a
a
School of Chemistry, Key Laboratory of Environmentally Friendly Chemistry and Applications of Minister of Education, Xiangtan University, Xiangtan, Hunan 411105, China
b
School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Hubei 430070, China
article info
Article history:
Received 18 August 2008
Received in revised form 21 January 2009
Accepted 22 January 2009
Available online 6 February 2009
Keywords:
CuV2O6
Lithium ion battery
Sol–gel method
Copper–vanadium-oxides
Cathode material
abstract
The CuV
2
O
6
cathode material was successfully synthesized using the NH
4
VO
3
and the alkaline copper
carbonate (CuCO
3
·Cu(OH)
2
·xH
2
O, malachite) as the starting reagents by a citrate sol–gel route. The struc-
tures and electrochemical properties of CuV
2
O
6
synthesized at different temperature were characterized
by X-ray diffraction (XRD), thermogravimetry/differential thermogravimetry (TG/DTG), scanning electron
microscopy (SEM) and electrochemical measurements. The results showed that the sample prepared at
550
◦
C had small particle size, and thus revealed higher initial discharge capacity (403 mAh g
-1
) and better
cycle performance than that prepared by the conventional solid-state method.
© 2009 Elsevier B.V. All rights reserved.
1. Introduction
In the past few years, vanadium-based materials, such as
V
2
O
5
, silver–vanadium-oxides (SVO, typically Ag
2
V
4
O
11
) and
copper–vanadium-oxides (CVO, typically CuV
2
O
6
and Cu
2
V
2
O
7
),
drew great interests of researchers for their high lithiated charac-
teristics [1–5]. Especially, Ag
2
V
4
O
11
has achieved a commercial suc-
cess as solid-state cathode material in primary (non-rechargeable)
lithium power sources for implantable biomedical devices [6]. Fur-
thermore, recent studies showed that the copper–vanadium-oxides
have delivered even more electrochemical capacity than SVO as
reported [7–9]. The cathode material Cu
2
V
2
O
7
could deliver an
attractive specific capacity near 500mAh g
-1
[10] while the CuV
2
O
6
could deliver the highest discharge specific capacity among all the
CVO series, more than the Ag
2
V
4
O
11
material used in commercial
Li/SVO batteries.
Like NiV
2
O
6
[11,12], Li
1+x
V
3
O
8
[13] and other vanadium-based
materials, the synthesizing technique played the important func-
tion to their electrochemical performances. As reported, the NiV
2
O
6
material synthesized by Fuentes et al. [11] was used as an anode
material (potential plateau was 0.5 V vs. Li
+
/Li) whereas the NiV
2
O
6
material synthesized by Andrukaitis et al. [12] was used as a cath-
ode material for lithium battery (potential plateau was about 1.5V
vs. Li
+
/Li). As for the synthesis of CuV
2
O
6
, there were three methods
reported in the literatures until to now. Eguchi et al. reported high
temperature solid-state method [7]. CuO and V
2
O
5
powders, which
∗
Corresponding author. Tel.: +86 732 8293043; fax: +86 732 8292282.
E-mail address: wxianyou@yahoo.com (X.-y. Wang).
has been preheated at 750
◦
C and 650
◦
C for 24 h, respectively, were
mixed at a molar ratio of 1:1 in an agate mortar and the mixture
was pressed (200 MPa) into pellets. Pellets were heated at 620
◦
C on
a platinum plate for 48.5 h under air atmosphere. It required large
energy consumption, long reaction time, and the resultant prod-
ucts exhibited low capacity. Besides, the co-precipitation method
was reported by Wei et al. [14]. The stoichiometric and oxygen defi-
cient CuV
2
O
6
was synthesized, but the electrochemical properties
of CuV
2
O
6
have not been reported yet. Recently, Cao et al. put for-
ward the soft chemistry method to synthesize the -CuV
2
O
6
[8].
The -CuV
2
O
6
was obtained from V
2
O
5
gel and Cu
2
O powders.
Although as-prepared CuV
2
O
6
could deliver the specific capacity of
nearly 350 mAh g
-1
in the discharge current density of 30 mA g
-1
,
its usage is limited because the V
2
O
5
gel could not be cosmically
manufactured.
In this work, CuV
2
O
6
was successfully synthesized via sol–gel
method for the first time. Synthesized technique and electrochem-
ical performance of the as-prepared CuV
2
O
6
material was studied
in detail.
2. Experimental
2.1. Preparation of CuV2O6
The CuV2O6 was synthesized by a sol–gel route based on citric acid using
NH4VO3 as a vanadium source. Citric acid was employed as chelating reagent in
the sol–gel process to provide the mixing of anion at the molecular level. Starting
materials were of analytical grade. The NH4VO3 and the alkaline copper carbonate
(CuCO3·Cu(OH)2·xH2O) powders were dissolved completely in citric acid solution on
the molecular ratio of 2:1:3 in vigorous magnetic stirring at 80
◦
C. The color of the
transparent solution varied from salmon pink, khaki, dark blue to greenish black at
the end. Then, the resultant sol was heated in a beaker over a hot plate for dryness
0925-8388/$ – see front matter © 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jallcom.2009.01.095