In situ growth of CuO nanoparticles on graphene matrix as anode
material for lithium-ion batteries
Danfeng Qiu
a,
n
, Bin Zhao
b
, Zixia Lin
b
, Lin Pu
b
, Lijia Pan
b
, Yi Shi
b
a
College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China
b
National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
article info
Article history:
Received 29 January 2013
Accepted 9 April 2013
Available online 17 April 2013
Keywords:
CuO
Graphene
Nanoparticles
Nanocomposites
Energy storage and conversion
Lithium ion battery
abstract
CuO nanoparticles are directly formed on graphene nanosheets through the in situ chemical decom-
position of Cu(NO
3
)
2
3H
2
O and are anchored tightly on the graphene surface. The lithiation-induced
strain is naturally accommodated, owing to the constraint effect of the graphene matrix. Electrochemical
characterization shows that CuO nanoparticles anchored on graphene sample exhibits a high capacity of
about 660 mAh/g at a discharge current density of 100 mA/g and a good cycling ability. During the
charge–discharge process, graphene nanosheets not only served as a three-dimensional conductive
network for CuO nanoparticles, but also improve the detachment and agglomeration of CuO nanopar-
ticles. This CuO/graphene nanocomposite displays superior Li-battery performance with large reversible
capacity, excellent cyclic performance, and good rate capability.
& 2013 Elsevier B.V. All rights reserved.
1. Introduction
Recharg eable solid-state batteries ha ve long been considered an
attractiv e power source for a wide variety of Modern electronic
devices such as cell phones, laptop computers, and electric vehicles
[1]. Lithium-ion batteries (LIBs) are one of the most suitable candi-
dates to satisfy the req uirements because of its high energy density
and light weight. Electrode materials are a determining factor for the
performance of a battery . Graphite performs well as anode for
commercial LIBs, but its theoretical capacity (372 mAh/g) is insuffi-
cient to satisfy the increasing demand for high capacity batteries.
Thus, transition metal oxides, such as SnO
2
[2],Fe
2
O
3
[3],Co
3
O
4
[4],
NiO [5],Mn
3
O
4
[6], and CuO [7], have long been e xploite d as the
anode materials of LIBs due to their high theoretical capacity. Copper
oxide(CuO),asoneofthepromisinganodematerialsforLIBs,has
been recently widely investigated due to its high theoretical capacity,
high safety , envir onmental benignity and low cost [8–10].However,in
their practical applications, the pulverization problem induced by
large volume changes, lead to electrode pulverization and loss of
interparticle contact and, consequently, result in a large irreversible
capacity loss and poor cycling stability [11,12].
Recentl y , some techniques to improve the CuO anode perfor -
mances have been reported. For example, by combining the metal
oxides with graphit e, the nanocompositesexhibitbothhighcapacity
and capacity retention as anode materials in LIBs. Graphene is an
ex cellent substrate to load active nanomaterials for LIBs due to its large
surface area, excellent conductivity , mechanical strength, and chemical
stability [13,14]. In this investigation, the possibility of higher lithium
storage capacity w as explored by loading CuO nanoparticles on layered
structures of graphene nanosheet materials. CuO-Graphene hybrid
material was synthesized by a one step in situ chemical synthesis
approach to form a CuO-Graphene h ybrid material. The CuO nano-
particles obtained are 50–100 nm in size and homogeneously anchor
on graphene sheets as spacers to keep the neighboring sheets
separated. The high porosity of the CuO particles allows easy access
of Li ions and plays as an elastic buffer for the volume change during
lithiation/delithiation process. The GNS enhances the electronic con-
ductivity of the nanocomposite and the long-term stability of the
anodes. This CuO/graphene nanocomposite display s superior LIB per -
formance with large reversible capacity of about 660 mAh/g at a
discharge current density of 1 00 mA/g and a good cycling ability (no
capacity fading after 60 cycle s at 100 mA/g). The results present a
promising method for the anchoring of nanoparticles on graphene
sheets for maximum utilization of electrochemically active CuO nano-
particles and graphene for energy storage. This growth-on-gr aphene
approach would also be very useful in improving the electrochemical
performance of highly insulating electrode materials [1 5–17].
2. Experimental
The graphene nanosheet(GNS) was fabricated via a thermal
exf oliation method in our previous work [18]. The dried graphite
oxide (GO) w as thermally exfoliated at 300 1C for 3 min in air and
subsequently treated at 900 1C for 3 h in Ar , then GNS sample was
obtained. In a typical synthesis of CuO/GNS nanocomposite, 2.41
6g of Cu(NO
3
)
2
3H
2
Owasfirstly mixed with 50 mL of ethanol,
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journal homepage: www.elsevier.com/locate/matlet
Materials Letters
0167-577X/$ -see front matter & 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.matlet.2013.04.030
n
Corresponding author. Tel./fax: +86 25 84892452.
E-mail address: dfqiu@nuaa.edu.cn (D. Qiu).
Materials Letters 105 (2013) 242–245