Journal of Power Sources 189(20 09) 620–623
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Journal of Power Sources
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Short communication
Electrochemical properties of LiMnO2for lithium polymer battery
En Mei Jina,BoJin
b,a, Yeon-Su Jeona, Kyung-Hee Parka, Hal-Bon Gu a,∗
aDepartment of Electrical Engineering, Chonnam National University, 300 Yongbong-dong,Buk-gu, Gwangju 500-757, Republic of Korea
bCollege of Materials Science and Engineering, Jilin University, Changchun130025, China
article info
Article history:
Received 5 July 2008
Received in revised form 27 August20 08
Accepted 16September 20 08
Available online 7 October 2008
Keywords:
Quenching method
LiMnO2
Solid polymer electrolyte
Liquid electrolyte
abstract
Well-defined o-LiMnO2cathode materials were synthesized by quenchingmethod at 1050 ◦Cinanargon
flow. The synthesized LiMnO2particle was characterized by X-ray diffraction (XRD) and field emission
scanning electron microscopy (FE-SEM). LiMnO2/solid polymer electrolyte (SPE)/Li batteries were char-
acterized electrochemically by charge/dischargeexperiments, cyclic voltammetry (CV) and ac impedance
spectroscopy. The charge/discharge results show that the discharge capacities of LiMnO2are 62 mAh g−1
at the first cycle and 124mAh g−1after 70 cycles, respectively. Moreover, we evaluated batteries using
liquid electrolyte and SPE. From the charge/discharge results, the discharge capacity of LiMnO2/SPE/Li
battery is greater than that of LiMnO2/Li battery with liquid electrolyte.
© 2008 Published by Elsevier B.V.
1. Introduction
Lithium polymer batteries have been utilized in a wide range
of applications, such as cellular phones, notebooks, camcorders
and digital cameras [1,2]. The successful commercialization of Li-
ion gel polymer batteries for portable electronic devices has led
to the other applications where the size and weight of batteries
are important. A considerable investment in this battery technol-
ogy that utilizes LiCoO2cathodes has been made [3–8]. However,
low-cost cathode materials arerequired for many applications such
as in electrical vehicles (EVs) and hybrid electric vehicles (HEVs)
[9,10]. The Mn-based materials have attracted attention as interca-
lation cathode materials because of their low cost and nontoxicity.
The LiMn2O4has shown excellent cycle performance at roomtem-
perature in the 4 V region, but also exhibits a significant capacity
loss in the 3–4 V region as well as at high-temperature [11,12].In
contrast to LiMn2O4, the trivalent manganese compounds LiMnO2
(both orthorhombic and monoclinic) exhibited a better cyclability
even between 2 and 4.5 V vs. Li+/Li [13,14]. Orthorhombic LiMnO2
(hereafter referred toas o-LiMnO2) should b e the best substitutefor
spinel LiMn2O4. Meanwhile, it becomes clear that o-LiMnO2is par-
ticularly attractivebecause of its potential to offer a high theoretical
capacity of 286 mAh g−1, which is twice that of spinel LiMn2O4
within the same Mn4+/Mn3+ redox couple [15,16]. Orthorhom-
bic LiMnO2can be synthesized by various methods such as
∗Corresponding author. Tel.:+82 62 530 0740; fax: +82 62 530 0077.
solid-state method [4], hydrothermal method [17] and quenching
method [18].
In this study, o-LiMnO2particles were prepared by quenching
method. The electrochemical properties of the as-synthesized o-
LiMnO2for lithium ion batteries and lithium polymer batteries are
presented.
2. Experimental
Orthorhombic LiMnO2was prepared with the starting materi-
als of LiOH·H2O (Aldrich, 99.995%) and Mn3O4(Aldrich, 97%) by
quenching method. The precursors were mixed. After the mixture
was pelleted and heated at 1050◦C for 15 h, the obtained sam-
ple was cooled by liquid state of nitrogen. The heating rate was
10 ◦Cmin
−1. The resulting LiMnO2was obtained after ball-milling
at 30 0 rpm for 10 h.
The crystalline phases of the obtained o-LiMnO2powders were
identified with X-ray diffraction (XRD, Dmax/1200, Rigaku). The
XRD pattern was collected by a step-scanning mode in the range
of 10–80◦withasteptimeof5
◦min−1. Powder morphologies were
observed by FE-SEM.
The composite electrodes were prepared by mixing o-LiMnO2,
acetylene black (AB) and polyvinylidenefluoride(PVDF) binder dis-
solved in N-mehtylpyrrolidinone in different weight ratios. The
obtained slurry was ball-milled for 1 h, and coated onto an Al-
foil, and dried at 90 ◦C for 1 h. The resulting electrode films were
pressed with a twin roller, cut into a round plate (˚=15.958 mm),
and dried at 110 ◦C for 24h under vacuum. A lithium foil was used
as an anode. Liquid electrolyte was 1M LiPF6dissolved in ethy-
0378-7753/$ – see front matter © 2008 Published by Elsevier B.V.
doi:10.1016/j.jpowsour.2008.09.102
