PVA-based polymer electrolytes were prepared with various concentrations of CdCl2 using solvent casting method. Prepared polymer films were investigated using line profile analysis employing X-ray diffraction (XRD) data. XRD results show that the crystallite size decreases and then increases with increase in CdCl2. AC conductivity in these polymer increases films first and then decreases. These observations are in agreement with XRD results. The highest ionic conductivity of 1.68
There is a continued interest in conducting polymers due to their properties like easy fabrication, low cost, leak proof, biodegradability, and good storage capacity. Conducting polymers find application in the development of advanced high energy electrochemical devices for example, batteries, fuel cells, electrochemical display devices, and photoelectrochemical cells. The development of conducting polymers involves several approaches: (i) dry solid state polymers, (ii) gel/plasticizer polymer, and (iii) composite polymer. Many lithium-based polymer electrosystems have been investigated earlier [
The present study focused on the AC electrical conductivity of PVA doped with CdCl2 blends which will be an interesting study for being used as a final product in some technical applications like electrochemical applications, fuel cells, batteries, electrochemical display devices, and photo electrochemical cells. The present study is also concerned with the correlation between crystallite ellipsoids and conductivity in CdCl2-based polymer films. An explanation in terms of C–O and C–H bond stretching using FTIR data has been made in this paper. FTIR spectra are useful in identifying the change in functional groups due to the presence of cadmium ions. Cadmium ions have a tendency to break polymer network because of its reasonable positive charge behaviour which is indicated in our FTIR studies.
Poly vinyl alcohol (PVA) was purchased from Loba Chemie, Mumbai, India, and was used without further purification. CdCl2 was purchased from M/s SD fine chemicals, Bangalore, Karnataka, India. The polymer films were prepared by solvent casting method [
X-ray diffraction patterns of the polymer films were recorded using Rigaku MiniFlex II Diffractometer with Ni filtered CuK
The AC conductivity of these polymer films was measured using Hioki (Japan) model 3532–50 computer interfaced digital LCR meter in the range of 50 Hz–5 MHz. The infrared spectra of these polymer films were recorded at room temperature in the (wave number) range of 4000 cm−1 to 400 cm−1 using JASCO FTIR 4100 type A spectrometer.
X-ray diffraction analysis is a very useful method in determining the microstructure of the material. The microstructural parameters like crystal size (
Microstructural parameters of CdCl2 doped with PVA polymer using exponential distribution function.
Samples | Bragg’s reflections
|
|
|
Surface density ( |
|
|
|
Delta | Crystallite area (nm2) |
---|---|---|---|---|---|---|---|---|---|
Pure |
|
19.56 |
1.35 |
4.47 |
3.9 |
1.76 |
0.52 |
|
1.39 |
1% |
|
19.40 |
1.35 |
4.51 |
4.05 |
1.85 |
0.47 |
|
1.32 |
2% |
|
19.56 |
1.35 |
4.47 |
4.17 |
1.88 |
0.45 |
|
1.16 |
3% |
|
19.24 |
1.35 |
4.54 |
3.66 |
1.68 |
0.56 |
|
1.07 |
4% |
|
19.02 |
1.5 |
4.60 |
3.94 |
1.83 |
0.52 |
|
1.20 |
XRD pattern of pure PVA and (PVA + CdCl2) polymer films.
Experimental and simulated profiles using whole powder pattern fitting method.
Unit cell crystallite shape and crystallite size along different Bragg angles.
Crystallite ellipsoids in (PVA + CdCl2) based polymer films. 1out: 1% CdCl2, 2out: 2% CdCl2; 3out: 3% CdCl2; 4out: 4% CdCl2; pureout: pure PVA.
The measured conductance
Microstructural parameters of CdCl2 doped PVA films.
Sample | Crystallite size ( |
Conductivity (Scm−1) |
---|---|---|
Pure PVA | 1.76 |
|
1% CdCl2 | 1.85 |
|
2% CdCl2 | 1.88 |
|
3% CdCl2 | 1.68 |
|
4% CdCl2 | 1.83 |
|
Variation of conductivity with frequency.
The recorded FTIR spectra are shown in Figure
FTIR spectrum of pure PVA and various concentrations of CdCl2 polymer films.
Frequency of the fundamental transition = 1944 cm−1
Frequency of the first overtone = 3830 cm−1
Solving these two equations, we get equilibrium vibration frequency and hence we can calculate anharmonicity constant. For pure PVA, the calculated equilibrium vibration frequency and anharmonicity constant are 2002 cm−1 and 14.48 × 10−3. The equilibrium vibration frequency decreases for various concentrations of CdCl2 salt. Zero point energy is calculated for these samples using the following relation [
The zero point for pure PVA sample is 993.7 cm−1 and it decreases for various concentrations of CdCl2 salt. The force constant for all the samples is calculated using the following relation:
IR data of pure and CdCl2 doped PVA polymer films.
Samples | Equilibrium vibration frequency |
Anharmonicity constant |
|
Force constant |
---|---|---|---|---|
Pure | 2002 | 14.48 | 998.7 | 222.2 |
1% CdCl2 | 1988 | 9.05 | 989.5 | 219.1 |
2% CdCl2 | 1982 | 10.59 | 985.7 | 217.7 |
3% CdCl2 | 1999 | 14.50 | 998.2 | 221.5 |
4% CdCl2 | 1931 | 1.55 | 964.7 | 206.7 |
Polymer blend electrolytes were prepared with PVA for different concentrations of CdCl2 and we observe the highest conductivity of
The authors would like to thank UGC, India, for the grants under Centre with Potential of Excellence in Particular Area (CPEPA) and University for Potential of Excellence (UPE) research program for the University of Mysore, Mysore, Karnataka, India.