Characterization of nanocomposite polymer electrolyte based on P(ECH-EO)

Article abstract of DOI:10.1016/j.physb.2011.05.047

ZrO₂ nanoparticles have been prepared by poly acrylamide gel route. The synthesized nanosized ZrO₂ have been incorporated into plasticized polymer electrolyte (PPE), P(ECH-EO): LiClO₄: γ-BL system to understand the effect

Full text of DOI:10.1016/j.physb.2011.05.047

Physica B 406 (2011) 3367–3373
Contents lists available at ScienceDirect
Physica B
journal homepage: www.elsevier.com/locate/physb
Characterization of nanocomposite polymer electrolyte based on P(ECH-EO)
a
a,b,c,
n
d
b,a
H. Nithya , S. Selvasekarapandian
, P. Christopher Selvin , D. Arun Kumar
,
a
e
M. Hema , D. Prakash
a
DRDO-BU Center for Life Sciences, Bharathiar University, Coimbatore, Tamil Nadu, India
Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu, India
Kalasalingam University, Krishnankoil, Srivilliputtur-626 190, Tamil Nadu, India
Department of Physics, NGM College, Pollachi, Tamil Nadu, India
b
c
d
e
Department of Physics, Alagappa University, Karaikudi, Tamil Nadu, India
a r t i c l e i n f o
a b s t r a c t
Article history:
ZrO2 nanoparticles have been prepared by poly acrylamide gel route. The synthesized nanosized ZrO2
have been incorporated into plasticized polymer electrolyte (PPE), P(ECH-EO): LiClO4: -BL system to
understand the effect of ZrO on the ionic conductivity. The X-ray diffraction pattern of the synthesized
ZrO nanoparticles reveals the crystalline phase. The X-ray diffraction patterns of P(ECH-EO) based
NCPEM confirm the polymer–salt-nanoparticle complexation. The scanning electron microscope image
of NCPEM confirms that the ZrO nanoparticles were distributed uniformly in the polymer matrix. The
Received 3 August 2010
Received in revised form
g
2
1
5 May 2011
2
Accepted 22 May 2011
Available online 1 June 2011
2
Keywords:
presence of nano filler has increased the ionic conductivity and the maximum dc conductivity value is
P(ECH-EO)
found to be 6.24 ꢀ 10ꢁ6 S cmꢁ1 at 303 K for 96(PPE): 4ZrO
2
(mol%).
2011 Elsevier B.V. All rights reserved.
ZrO
2
&
Differential scanning calorimetry
Electrical properties
1
. Introduction
proportion of the amorphous phase. Several strategies were used
to decrease the crystalline nature of PEO and improve the
conductivity of its complexes at room temperature. One way to
generate this modification could be to use a substituted monomer
in order to form another polymer, a copolymer or a terpolymer.
Works on copolymers based on PEO have been reported to reduce
the crystalline nature of PEO and to increase its ionic conductiv-
ity. Among the copolymers reported, the halogenated polyether,
poly(epicholorohydrin co ethyleneoxide) (P(ECH-EO), has been
chosen as the host polymer to prepare the polymer electrolyte.
To enhance the ionic conductivity, several approaches have
been made such as adding organic plasticizer, blending polymers,
incorporating fillers, etc. The addition of plasticizer, though
improves the conductivity of the polymer electrolyte, faces
problems such as the electrolyte leakage which deteriorates the
mechanical stability of the polymer electrolyte. This leads to
serious problems in the battery application. The addition of inert
filler into polymer matrix improves the mechanical stability, ionic
conductivity and electrode electrolyte interfacial stability which
are important factors affecting a battery [11–15]. Scrosati et al.
The development of a new polymer electrolyte to be used in
advanced batteries and fuel cell is critical for the commercial
success of these types of power systems. The problems faced in
using the polymer electrolyte as electrolyte material in batteries
and fuel cells are their low ionic conductivity at ambient tem-
perature, reaction with the lithium metal electrode, and mechan-
ical stability for use as an electrolyte. A lot of research efforts have
been made to optimize the properties of polymer electrolytes for
its applicability in solid-state lithium polymer electrolyte battery
[
1–4]. In the past two decades, a number of polymer electrolytes
based on poly (acrylonitrile) [5], poly (propylene oxide) [6] and
polyethylene oxide (PEO) [7,8] etc. have been investigated to
meet these requirements to some extent. Among all these poly-
mers, the polyether, polyethylene oxide, remained as one of the
most preferred polymer matrix, since it is the best matrix for the
alkaline salts [9,10]. Due to its high crystalline nature, PEO based
electrolytes show high ionic conductivity only above its melting
temperature (65 1C), which is inadequate for most of the practical
applications. In order to improve the electrical properties of PEO,
it is necessary to modify the polymer structure to obtain a larger
[16] reported the effect of nanoparticles SiO
electrode electrolyte interfacial stability. Ahmad et al. have
studied the effect of ZnO, TiO and Al fillers on the room
temperature conductivity of PVC:LiClO [17]. Ji et al. have devel-
oped PEO:LiClO –SiO composite electrolyte with improved con-
ductivity in the order of 10 S cm
[18]. Pitawala et al. have studied the effect of incorporation of
2 2
, TiO fillers on the
2
2 3
O
4
n
4
2
Corresponding author. Kalasalingam University, Krishnankoil,
ꢁ
5
ꢁ1
at ambient temperature
Srivilliputhur-626 190.
E-mail address: sekarapandian@yahoo.com (S. Selvasekarapandian).
0921-4526/$ - see front matter & 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.physb.2011.05.047

3
368
H. Nithya et al. / Physica B 406 (2011) 3367–3373
Al
PEO)
of filler leads to a significant improvement in the ionic conduc-
2
O
3
filler along with the plasticizers EC and PC into the
:LiTf solid polymer electrolyte system. The incorporation
3. Results and discussion
(
9
3.1. Thermal analysis of ZrO
2
ꢁ
4
ꢁ1
tivity to an order of 10 S cm
present study nano sized ZrO
polyacrylamide gel method. The prepared nano sized ZrO
been used for the preparation of nano composite polymer
electrolyte membrane (NCPEM) based on P(ECH-EO): -BL:LiClO
at 25 1C [19]. Hence, in the
have been synthesized by the
have
2
2
The TG/DTA traces of the polyacrylamide gel based ZrO is
2
presented in Fig. 1. The degradation of polymer gel takes place in
multiple steps which completes around 600 1C. The weight loss of
about 20% below 250 1C was attributed to the removal of the
bound moisture. The elimination of the organic moieties through
oxidation is observed by the weight loss step around 350 and
550 1C. The presence of nitrate ions initiates the degradation of
polymeric network which is supported by the presence of
exothermic peak around 250 1C in the DTA signal [21]. The gel
completely decomposes at 600 1C which confirms the formation
g
4
by the simple solution casting technique. XRD, SEM and con-
ductivity studies have been used to study the effect of nanopar-
4
ticles on the polymer electrolyte system P(ECH-EO): g-BL:LiClO .
2
. Experimental method
.1. Synthesis of ZrO nanoparticle
Monomers of acrylamide, (AM) and N-N -methylene bisacry-
2
of ZrO .
2
2
3.2. Structural analysis of ZrO
2
0
lamide (MBAM), were added to the aqueous solution of zirconium
oxynitrate in the molar ratio 1:1. The initiators, ammonium
oempty4X-ray diffraction studies have been employed to
study the phase pure formation of ZrO . The XRD pattern of the
2
0
0
persulfate (APS) and N,N,N ,N -tetramethyl ethylenediamide
TEMED) were then added to the transparent solution to initiate
(
the free radical cross-linking polymerization between the AM and
MBAM [20]. The transparent gel was obtained rapidly. The gel
was then ground to get a homogeneous mixture and calcined at
100
80
6
00 1C for 6 h. The phase purity and the degree of the crystalline
nature of the obtained ZrO were studied by XRD analysis.
2
6
0
2.2. Preparation of nanocomposite polymer electrolyte membrane
The host polymer P(ECH-EO)(64%–36%)(Aldrich) and ionic
dopant, lithium perchlorate (Himedia), were dried in vaccum,
-butyrolactone (Merck) and acetone (Merck) were used as
purchased. The nanocomposite polymer electrolyte membranes
of various compositions were prepared by the simple solution
casting technique as given below.
40
g
2
0
0
Based on the conductivity and the mechanical stability of the
film, the ratio of plasticized polymer electrolyte, P(ECH-EO):
1
00
200
300
400
500
600
700
800
Temperature (°C)
g
-BL:LiClO
electrolyte 77.5 P(ECH-EO):7.5
ered as PPE. The homogeneous solution of P(ECH-EO):
was prepared by using acetone as solvent, to which ZrO
4
was kept fixed as 77.5:7.5:15. The plasticized polymer
-BL:15LiClO (mol%) was consid-
-BL:LiClO
nano-
g
4
2
Fig. 1. TG/DTA curve ZrO xerogel.
g
4
2
particle was dispersed and sonicated. The obtained colloidal
solution was cast in the glass petri dishes and dried in vacuum
oven at 50 1C to remove traces of acetone. The obtained thin film
polymer electrolyte obtained after the removal of acetone was
stored inside dessicator to avoid absorption of moisture. The
different compositions of nanocomposite polymer electrolyte
membrane prepared are,
6
00°C
(c)
Nanocomposite polymer electrolyte
membrane (mol%)
Sample code
500°C
(
b)
a)
9
9
9
8(PPE): 2ZrO
6(PPE): 4ZrO
4(PPE): 6ZrO
2
2
2
I1
I2
I3
4
00°C
15
The XRD diffractograms were recorded using PANanalytical
X-pert pro-X-ray diffractometer using CuK radiation. The SEM
(
a
images were recorded using HITACHI S-3000 H scanning electron
microscope. The thermal analysis has been carried out using
Perkin Elmer STA6000 and NETZSCH DSC 204 F1. The electrical
measurements have been carried out using computer controlled
HIOKI 3532 LCZ analyzer in the frequency range of 42 Hz–1 MHz.
0
30
45
60
75
90
2
θ (degree)
Fig. 2. XRD pattern of the synthesized ZrO
(c) 600 1C.
2
calcined at (a) 400 1C, (b) 500 1C and

H. Nithya et al. / Physica B 406 (2011) 3367–3373
3369
ZrO
ZrO
2
calcined at 400, 500 and 600 1C is shown in Fig. 2(a–c). The
powder calcined at 400 1C shows the amorphous nature of
separate phase in the polymer electrolyte system which con-
firms the complete dissociation of LiClO in the polymer matrix.
3. The broadness of the peak at 2
¼211 shown in Fig. 3(c–d)
increases with the addition of nano-sized ZrO to the polymer
electrolyte and the high intensity peaks of ZrO are found to
decrease. This suggests that the complexation of ZrO with the
2
4
the prepared powder indicating the presence of organic residues.
The precursor calcined at 500 1C (Fig. 2(a–b)) shows the presence
y
2
of ZrO
shows a well resolved peak for the sample calcined at 600 1C,
indicating the formation of phase pure ZrO with high crystal-
lanity. The result is compatible with the total weight loss results
obtained from the TG/DTA analysis as shown in Fig. 1. The XRD
2
peaks with low crystallanity. The XRD pattern (Fig. 2(c))
2
2
2
polymer electrolyte takes place in the amorphous phase of the
polymer to promote the local structural relaxation and seg-
mental motion of the polymer. The peak angle at 2
corresponding to the ZrO appears with increase in ZrO
concentration (Fig. 3(e)), which may be due to phase separa-
tion of ZrO from the host polymer matrix at higher concen-
tration of ZrO (6 mol%).
y¼301
pattern of ZrO
values 301, 351, 501, 601, 741 and 821 corresponds to the (1 1 1),
2 0 0), (2 2 0), (3 1 1), (4 0 0) and (3 1 1) plane reflections respec-
tively, which confirms the formation of single phase cubic
structure of ZrO [20–22]. The XRD pattern matches with JCPDS
2
calcined at 600 1C shows intense peaks at 2
y
2
2
(
2
2
2
card no. 89-9069. The particle size was calculated using Debye–
Scherrer formula
3.4. Morphological characteristics of NCPEM
K
l
D ¼
ð1Þ
Fig. 4 shows the SEM image of the 96(PPE): 4ZrO2 (mol%)
nanocomposite polymer electrolyte membrane. It can be seen
that the ZrO2 nanoparticles are uniformly distributed in the
polymer matrix. The presence of pores between the polymer
b
cos
where, D represents the crystallite size, K¼0.94,
wavelength of CuK radiation and
half maxima of the diffraction peak.
The synthesized zirconia nanocrystallites were found to have
an average particle size of 9 nm.
y
l
represents the
b represents the full width at
a
interface and filler suggests that the plasticizer g-BL is present
both in the pores and P(ECH-EO) matrix. This paves way for the
ionic conduction through the polymer matrix, ZrO2 and the
plasticizer [23].
3.3. XRD analysis of NCPEM
3.5. Thermal analysis of NCPEM
4
Fig. 3(a–e) shows the XRD pattern of LiClO , pure P(ECH-EO),
Thermal analysis has been performed using differential scan-
P(ECH-EO)-LiClO
complexation of ZrO
confirmed from the XRD pattern of the polymer complexes. In
order to investigate the influence of ZrO nanoparticle, XRD
studies were performed for pure P(ECH-EO) and 98(PPE): 2ZrO
mol%), 96(PPE): 4ZrO (mol%), 94(PPE): 6ZrO (mol%) nanocom-
4
based nanocomposite polymer electrolyte. The
ning calorimetric analysis in order to observe the change in glass
transition temperature that is caused by the addition of ZrO . The
2
with the polymer electrolyte has been
2
DSC thermograms of pure polymer P(ECH-EO) and the nanocom-
posite polymer electrolyte are represented in Fig. 5. The DSC
thermogram reveals an increase in glass transition temperature
2
2
(
2
2
(
T
g
) with the addition of ZrO
appears at 231 K. With the addition of ZrO2, the T
2
. The T
g
of the pure P(ECH-EO)
is increased to
(mol%). The increase in T with the
2
may be due to the formation of ‘transient
posite polymer electrolyte. The following distinct features have
been observed:
g
2
39 K for 96(PPE): 4ZrO
2
g
addition of ZrO
1
. Fig. 3(a) shows intense peaks of angles 2
and 351 which reveals the crystalline nature of ionic salt [JCPDS:
0-0751]. A broad peak at angle 2
¼211 in Fig. 3(b) reveals the
amorphous nature of P(ECH-EO).
. The peaks corresponding to LiClO
Fig. 3(c–d) indicating that the LiClO
y¼211, 231, 271, 311
crosslinking’ between the oxygen ions in the polymer matrix
þ
and the Li ions which causes strong ion–dipole interactions
3
y
in the polymer promoting a stiffening effect in the polymer
2
4
were not observed in
does not remain as a
4
(
e)
(
d)
(
c)
(
b)
(
a)
0
10
20
30
40
50
60
70
80
90
2
θ (degree)
Fig. 3. XRD pattern of (a) LiClO
4
, (b) pure, (c) 98(PPE): 2ZrO
2
(mol%), (d) 96(PPE):
2
Fig. 4. SEM image of 96(PPE): 4ZrO (mol%) nano composite polymer electrolyte
4
ZrO (mol%) and (e) 94(PPE): 6ZrO
2
2
.
membrane.

3
370
H. Nithya et al. / Physica B 406 (2011) 3367–3373
Tg
I1
I2
I3
1
1
1
5000
2500
0000
303K
(
a)
(
b)
7
5
2
500
000
500
0
(
c)
2
00
220
240
260
280
300
Temperature (K)
0
2500
5000
7500
10000
12500
15000
Fig. 5. DSC plot for (a) P(ECH-EO), (b) 98(PPE): 2ZrO
ZrO (mol%).
2
(mol%) and (c) 96(PPE):
Z' (ohm)
4
2
4
3
2
1
000
000
000
000
0
chain [24]. Zoppi et al. [25] has reported similar effect for P(ECH-
EO)/LiClO /SiO polymer electrolyte.
I2
4
2
3.6. Impedance spectroscopy analysis of NCPEM
0
00
The complex impedance plot (Z vs. Z ) for different composi-
tions of the nano composite polymer electrolyte at 303 K is shown
in Fig. 6a. The plot shows two well-defined regions, a high
frequency semicircle and the low frequency spike. The high-
frequency semicircle is related to bulk conduction processes
303K
3
3
3
3
3
08K
13K
18K
23K
33K
[
26]. The low-frequency spike results from electrode/electrolyte
interface properties. Z-view software program was used to extract
the bulk electrical resistance (R ) of the polymer electrolytes. The
b
bulk resistance values have been calculated from the low-
0
frequency intercept on the real axis (Z ) of impedance plot. The
high-frequency semicircle is represented by the frequency depen-
0
1000
2000
Z' (ohm)
3000
4000
dent capacitor (C
frequency spike is represented by the constant phase element
CPE). The equivalent circuit is shown in Fig. 6b. The ionic
conductivity is calculated using the relation
g b
) parallel to the bulk resistance (R ) and the low-
(
Fig. 6. Cole–Cole plot for (a) all composition at 303 K, (b) equivalent circuit:
frequency independent capacitor constant phase element CPE and bulk
resistance R and (c) 96(PPE): 4ZrO (mol%) at different temperatures.
g
C ,
b
2
s
¼ l=ðARbÞ
where A is the effective contact area of the sample with the
electrode, R is the bulk resistance of the sample and l is the
ð2Þ
reported by Feng Zhao et al. [13] for the nanocomposite polymer
electrolyte system poly (styrene-co-maleican hydride) as the back-
b
thickness of the sample.
bone and poly (ethylene glycol) methyl ether as side chain/SiO
LiCF SO
The complex impedance plot for the highest conductivity
electrolyte system 96(PPE): 4ZrO (mol%) (I2) at various tem-
2
/
From the impedance spectra, it is observed that the highest
conductivity is found to be 6.24 ꢀ 10 S cm
polymer electrolyte system with 4 mol% ZrO
3
3
.
ꢁ
6
ꢁ1
at 303 K for the
2
.
2
From the DSC results, it is observed that the glass transition
temperature increases as the ZrO concentration is increased. From
the impedance spectra results, the ionic conductivity is found to
increase with the increase in ZrO concentration. In general, when
the glass transition temperature increases, the ionic conductivity
decreases. However, the experimental results obtained are con-
trary to this. From the investigation of the ionic conductivities of
these nanocomposite polymer electrolytes, the samples show a
conductivity enhancement. The only reason for the conductivity
enhancement is the nanoparticles–polymer–plasticizer–salt inter-
peratures is shown in Fig. 6(c). The bulk resistance decreases with
the increase in temperature. Decrease in impedance corresponds
to the increase in charge carrier density. In the complex impe-
dance plot, the disappearance of the high-frequency semicircle
with the increase in temperature reveals the absence of capacitive
nature due to the random orientation of dipoles in the side chains
of the polymer electrolyte [27]. Hence, it is found that the amount
2
2
2
of ZrO considerably increases the ionic conductivity of the nano
composite polymer electrolyte.
action, especially the interaction of the nanoparticle’s (ZrO
2
) sur-
3.7. Conductivity analysis of NCPEM
face with the side chain of the polymer, but not much with the
backbone of the main chain which has little effect on the mobility
of Li ions at ambient temperature. Similar results have been
The frequency dependence of conductivity for the entire
polymer electrolyte at 303 K is shown in Fig. 7(a). The spectra
þ

H. Nithya et al. / Physica B 406 (2011) 3367–3373
3371
shows three well-defined regions: a low-frequency region, mid-
frequency plateau region and the high-frequency dispersion
region. The conductivity is found to obey Jonscher’s power law
observed which is due to the electrode polarization effects. At
these temperatures the ionic conductivity is high due to the
significant build-up of charges at the electrodes which reduces
the effective applied field across the samples and apparently
increases the ionic conductivity. The ionic conductivity increases
[
28]
n
sð
o
Þ ¼ sdc þA
o
ð3Þ
ꢁ6
ꢁ4
ꢁ1
from 10 to 10 Scm and the values are tabulated in Table 1.
It is observed from the table that the conductivity reaches a
where dc is the dc ionic conductivity, A and n are temperature
s
ꢁ
4
ꢁ1
maximum of 1.21 ꢀ 10 Scm
polymer electrolyte system with 4 mol% ZrO
concentration of ZrO (6 mol%), the conductivity decreases which
may be due to the agglomeration of the inorganic particles (ZrO ).
at 333 K for nano composite
dependent parameters. The dc conductivity values have been
calculated by fitting the Jonscher’s power law equation to the
experimental data obtained and it is found that the values lie in
2
. Also, at higher
2
ꢁ
6
ꢁ1
2
the 10 S cm range at 303 K (Table 1) for all the composition.
Fig. 7(b) shows the frequency dependent conductivity spectra of
The increase in conductivity with temperature is interpreted as
the hopping of ions between the coordinating sites, local struc-
tural relaxations and segmental motion of the polymer matrix
9
2
6(PPE): 4ZrO (mol%) (I2) the polymer electrolyte with high
conductivity. At high temperatures, the low frequency spike is
[29,30]. From the spectra it is clear that as the temperature is
increased the spike gets increased due to the increase in mobile
charge carrier and the DC plateau region shifts towards the
high-frequency region. The high-frequency spike disappears as
the temperature increases within the frequency region measured.
I1
I2
I3
303 K
-
-
-
-
-
-
-
4.6
4.8
5.0
5.2
5.4
5.6
5.8
3.8. Temperature dependence of the ionic conductivity
The temperature dependent ionic conductivity of the compo-
site polymer electrolytes was evaluated to analyze the mechan-
ism of ionic conduction in polymer electrolyte. Fig. 8 shows the
variation of ionic conductivity with the reciprocal of temperature
for the nano composite polymer electrolytes. The linear variation
of log
s versus 1000/T plots suggests an Arrhenius type thermally
activated process. This suggests that there is no phase transition
of nanocomposite polymer matrix in the temperature range
studied. It is also supported by the results of the obtained DSC
thermograms in this temperature range studied. The conductivity
2
3
4
5
6
7
log ω
-
1.2
I1
I2
I3
3
03 K
-
-
-
-
4.0
4.4
4.8
5.2
308 K
-1.6
-2.0
3
3
3
3
3
13 K
18 K
23 K
28 K
33 K
Linear Fit
-
-
-
2.4
2.8
3.2
2
3
4
5
6
7
3.00
3.05
3.10
3.15
3.20
3.25
3.30
log ω
1000 / T
Fig. 7. Conductance plot of 96(PPE): 4ZrO
2
(mol%) at different temperatures.
Fig. 8. Arrhenius plot for P(ECH-EO) based nanocomposite polymer electrolyte.
Table 1
Conductivity of the NCPEM at different temperatures.
ꢁ
1
Nanocomposite polymer electrolyte membrane
Conductivity Scm
03 K
Activation energy (eV)
3
318 K
333 K
ꢁ
ꢁ
ꢁ
6
6
6
ꢁ5
ꢁ5
ꢁ5
ꢁ5
ꢁ4
ꢁ5
7
7
7
5.95P(ECH-EO):7.35
4.4P(ECH-EO):7.2 -BL:14.4LiClO
2.85P(ECH-EO):7.05 -BL:14.1LiClO
g
-BL:14.7LiClO
: 4ZrO
: 6ZrO
2
4
: 2ZrO
(I2)
(I3)
2
(I1)
2.62 ꢀ 10
6.24 ꢀ 10
4.32 ꢀ 10
1.12 ꢀ 10
3.55 ꢀ 10
1.89 ꢀ 10
4.00 ꢀ 10
1.21 ꢀ 10
7.05 ꢀ 10
0.39
0.36
0.38
g
4
2
g
4

3
372
H. Nithya et al. / Physica B 406 (2011) 3367–3373
can be expressed as
expðꢁE =KTÞ
is the pre-exponential factor, E
and T is the absolute temperature in K. The activation energy
values have been calculated from the slope of the Arrhenius plot.
Table 1 shows the activation energy of nano composite polymer
1
x105
I2
303K
08K
313K
318K
s
s
o
a
ð4Þ
dc ¼
3
where
s
o
a
is the activation energy
9x104
3
3
3
23K
28K
33K
films with different compositions and the results reveal that E
decreases effectively with the ZrO concentration. As temperature
a
6
x104
2
increases, the polymer chain acquires faster internal modes in
which bond rotations produce segmental motion. This, in turn,
favours inter-chain hopping and intra-chain ion movements and,
accordingly, the conductivity of the polymer electrolyte becomes
high [31].
3x104
0
3.9. Dielectric behavior
1
2
3
4
5
6
The dielectric behavior of the highest conductivity nanocom-
log f
posite polymer electrolyte membrane 96(PPE): 4ZrO
2
(mol%) is
n
Fig. 10. Dielectric loss plot of 96(PPE): 4ZrO
2
(mol%) at different temperatures.
described by using the dielectric function
e
0
00
e* ¼
e
2ie
ð5Þ
0
0
.030
.025
0
00
is dielectric loss
where
e
is dielectric constant and
e
3
3
3
3
03K
08K
13K
18K
I2
0
Fig. 9 shows log f vs.
6(PPE): 4ZrO
the dielectric constant decreases with increasing frequency.
A rapid decrease in dielectric constant may be noticed over the
frequency range of 1 kHz. The decrease in the dielectric constant
with the increase in the frequency may be due to the tendency of
the dipoles in the polymer chains to orient themselves in the
direction of the applied electric field [32]. The higher values of
for 96(PPE): 4ZrO
e
plot at different temperatures for
(mol%) (I2) polymer electrolyte. It is observed that
9
2
0.020
.015
0.010
323K
3
3
28K
33K
0
0
e
2
(mol%) at low frequency for the system is due
to the enhanced charge carrier density at the electrolyte–
electrode interface, resulting in an increase in the equivalent
0
0
.005
.000
’
capacitance [33–35]. The observed variation in
can be attributed to the formation of space charge region at the
e
with frequency
(nꢁ1)
electrode–electrolyte interface which is known as
o
varia-
tion or the non-debye behavior where the space charge with
respect to frequency is explained in terms of ion diffusion [36]. At
high frequencies, the fast periodic reversal of the electric field
occurs. Hence, the polarization due to charge accumulation
decreases at the electrode–electrolyte interface which, in turn,
1
2
3
4
5
6
log f
2
Fig. 11. Modulus plot of 96(PPE): 4ZrO (mol%) at different temperatures.
contributes to the decrease in
e’ [37].
0
0
Dielectric loss factor (
e
) is a direct measure of energy
x105
dissipated and is generally composed of the contributions from
3
2
1
the ionic transport and from the polarization of the charge or
I2
303K
00
dipole. Fig. 10 shows
temperature range for 96(PPE): 4ZrO
dielectric loss at lower frequency and maximum in the mid-
frequency have been observed in the 96(PPE): 4ZrO (mol%)
polymer electrolyte system. This observed peak is due to the
-relaxation which may be due to the movement of the side
chains of the polymer. The shifting of -relaxation to the high-
e
as a function of frequency in wide
3
3
08K
13K
2
(mol%) (I2). A decrease in
x105
x105
0
318K
2
3
3
3
23K
28K
33K
b
b
frequency range with the increase in temperature indicates a
decrease in the relaxation time of the side chains [38,39].
3.10. Electric modulus analysis
The dielectric behavior of the sample can also be studied using
the electric modulus. Fig. 11 shows the frequency dependence of
the imaginary part of the modulus for 96(PPE): 4ZrO (mol%) (I2)
2
nanocomposite polymer electrolyte membrane. It is observed that
the modulus increases with the increase in frequency. At
low frequency, the modulus value approaches to zero indicating
that the electrode polarization phenomenon makes a negligible
1
2
3
4
5
6
Log f
2
Fig. 9. Dielectric constant plot of 96(PPE): 4ZrO (mol%) at different temperatures.

H. Nithya et al. / Physica B 406 (2011) 3367–3373
3373
contribution. The appearance of long tail in the low frequency
region is due to the capacitance effect at the electrodes. The
increases in modulus spectra at higher frequencies indicates that
the polymer electrolyte systems are ionic conductors and this is
attributed to the bulk of the material. The maximum of the peak
decreases with the increase in temperature indicates distribution
of relaxation mechanism [40].
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The nanocomposite polymer electrolyte based on P(ECH-EO) has
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phous nature and the complexation of ZrO to the polymer matrix
have been confirmed by the XRD analysis. The uniform distribution of
ZrO in the polymer matrix has been analyzed by SEM. The
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[
2
4
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nanocomposite polymer electrolyte membrane having 4 mol% ZrO
2
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ꢁ
6
ꢁ1
exhibits a maximum conductivity of 6.24 ꢀ 10 Scm
at 303 K.
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One of the authors, Ms. H. Nithya, would like to thank the DRDO-
BU Center for Life Sciences for providing Senior Research Fellowship.
The authors would like to thank Prof. T. Kurian Mathew (Retd.),
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