Characterization of LiClO 4 Doped PVDF Solid Polymer Electrolyte

(1)

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 7, Issue 11, November 2017)

484

Characterization of LiClO

4

Doped PVDF Solid Polymer

Electrolyte

K.Venkata Ramana1, M. Chandra Shekar2, A.R.Subrahmanyam 3

, M.Ravindar Reddy4, V. Madhusudhana Reddy5,

1,3,4 _{Department of S&H, MVSR Engineering College, Hyderabad, TS, India} 2

Department of Physics, JNT University, Hyderabad, India

4_{Department of S & H, Malla Reddy college of Engineering &Technology, Hyderabad, TS, India}

Abstract— New polymer electrolytes based on Poly Vinylidene Difluoride (PVDF) with Lithium Per chlorate ( LiClO4) samples have been prepared by

solution casting method. X-ray diffraction measurements were carried out on these samples. The X-ray diffraction measurements clearly reveal the modification of PVDF crystalline structure with increasing Lithium per chlorate content. The surface morphology of these polymer complexed films is analyzed by Scanning Electron Microscopy (SEM). FTIR studies have been carried out to confirm the complexation of PVDF with Lithium per Chlorate. The optical measurements were taken on these samples using UV spectroscopic method .Finally the results obtained are presented and discussed.

Keywords— FTIR,LithiumPerchlorate, Optical Absorption, UV Spectra, XRD Studies

I.INTRODUCTION

:

Polymer complexes with suitable salts are widely used as solid polymer electrolytes which play very important role in development of various electro chemical devices such as batteries, photo Electron chemical cells, electro chromic display devices due to their high chemical corrosion resistance, heat resistance and mechanical strength and toughness [1, 2,3].

The aim of the present work is to study the structural, optical properties of complexed

polymer electrolytes based LiClO4 and PVDF.

These are prepared by doping different

concentrations of LiCO4 in PVDF. Various

properties of these polymer samples are studied using techniques like XRD, FTIR, SEM and UV absorption. The obtained results are presented and discussed.

II.PREPARATION OF POLYMER ELECTROLYTES:

Pure PVDF (320000MW from Merck)

complexed with LiClO4 in various compositions

(90:10), (80:20), (70:30) & (60:40) by wt% ratio, are prepared using solution caste technique.

PVDF & LiClO4 are dissolved in DMF; The

solutions obtained are stirred 10-12 hours to get homogeneous Mixture. The stirred solutions are allowed to evaporate slowly. After 48 hours a solid polymer layers are obtained about 100 microns thickness. These polymers are dried in

vacuum at 10-3torr.

The film is carefully separated from the dish and stored in an evaluated desiccator. The X-ray diffraction (XRD) patterns of these polymers were taken with PHILIPS PW 3710. X-ray

(2)

485

Fourier transform infrared(FTIR) spectra of these systems were carried out using JASCO FTIR-5300 spectrometer over a wave number range

400-4000cm-1.The surface morphology of these

polymer systems were observed using Scanning electron Microscope(SEM).Optical absorption Spectra are recorded at room temperature in the

range 200-1000 nm using optical spectrometer.

III.XRDSTUDIES

The X-ray diffraction pattern of pure PVDF and

PVDF complexed with LiClO4 are shown in

fig.1. The pure PVDF has a characteristic peak corresponding to lattice at 1804ꞌ [4,5] indicating semi crystalline nature of the polymer. As the

concentration of LiClO4 increases in PVDF, the

peaks become less intense and broadened. The existence of new peaks and change in intensities clearly indicates a decreasing in degree of crystallinity in the pure polymer and confirm the

complexation of Li COo4 With PVDF.

Fig-1: X-ray diffraction Pattern of pure PVDF

& PVDF complexed with LiClO4.

IV.FTIR Analysis

The FTIR Spectra of Pure PVDF and PVDF

doped with LiClO4 as shown in fig2. From the

fig it is observed that for pure PVDF C-H

bending is observed around 1066 cm-1, C-O

stretching at 883.4 cm-1 and band corresponding

to C-F stretching is observed at 1175 cm-1. For

all concentrations of LiClo4 these stretching are

altered.

Fig.2: FTIR Spectra of pure PVDF & PVDF complexed with LiClO4.

The broadening of existing peaks inPVDF and also presence of some additional peaks clearly

indicates the complexation of LiclO4 with

PVDF

V.OPTICAL PROPERTIES

The information about band structure can be studied by optical absorption. In direct band semiconductor, the transition of electron from conduction band to valance band is associated

with a phonon of the appropriate magnitude

.Davis and Shaliday [6] reported that near fundamental band edge direct band transitions occur and can be observed by

[image:2.612.340.575.222.383.2] [image:2.612.79.291.465.595.2]

(3)

486

The relation given in equation is based on the analysis of Thtupalli and Tomlin[7]

(h )2 =C1(h -Egd).

where hυ is photon energy, Egd is direct band

gap, n is the refractive index, α is absorption coefficient and C1 are constant The direct band

gap values obtained by plotting (αh )2

[image:3.612.70.304.113.409.2]

vs h curves are shown in fig3 and are tabulated in Table 1.

polymer Direct band

gap(ev)

Pure PVDF 2.374

PVDF: LiClO4 (90:10) 2.310

PVDF:LiClO4 (80:20) 2.169

PVDF:LiClO4( 70:30) 1.543

PVDF:LiClO4(60:40) 2:448

VI.SEMSTUDIES

The surface morphology of pure PVDF and PVDF doped with various concentrations of

LiClO4 are shown in Fig.4 (A). Pure PVDF

surface appears to be semi crystalline which is also confirmed by XRD studies. As the

concentration of Liclo4 increases the degree of

crystallinity seems to be decreased in all composites. For 70:30 composition strong link is observed between PVDF polymer and the dopant which indicates certain hopping sites for conduction, As the concentration increases drastic changes observed from hexagonal (90:10) to more amorphous (60:40).Among (70:30) in the optimal concentration for better conducting behaviour.

[image:3.612.371.538.538.692.2]

(4)

487

I.

VI. CONCLUSIONS

Pure PVDF and PVDF doped with LiClO4 for

Various Concentration are prepared by Solution cast method. The complexation of PVDF

polymer with Liclo4 has been confirmed with

XRD and FTIR spectra. The surface morphology

of pure PVDF and PVDF +LiclO4 polymer

electrolytes at different weight percentage is studied using SEM. Increase in concentration of

Liclo4 decrease the degree of crystallinity of

PVDF. The direct band gap values of PVDF

+LiClO4 (70:30) polymer electrolyte indicates

the influence of LiClO4 on PVDF for better

conducting properties.

ACKNOWLEDGEMENTS

The author thanks the Head Department Physics,

Osmania University for their constant

encouragement and providing necessary

facilities. Also one of the authors (KVR) thanks HOD, S&H, Principal, MVSR Engineering

College, Hyderabad for their constant

encouragement.

References

[1] Rao S S, Sunar M. “Piezoelectricity and Its Use in Disturbance Sensing and Control of Flexible Structures: A survey”, Applied Mechanics Review, 47, No 4, 113-123, 1994.

Fig.4 (B) SEM micrograph oPVDF:Li ClO4(90:10) complexed

electro lyte film

complexed electro lyte film

Fig.4 (C) SEM micrograph oPVDF:Li ClO4(80:20)

Fig.4 (D) SEM micrograph oPVDF:Li ClO4(70:30)

complexed electro lyte film Fig.4 (C) SEM micrograph oPVDF:Li Clo4(80:20)

Fig.4 (E) SEM micrograph oPVDF:Li ClO4(60:40) complexed

(5)

488

[2] Sundar V, Newnham R E. “Electrostriction”, ENGnetBASE 2000, CRC Press LLC, chap. 50, http://www.engnetbase.com, 1999.[3] Wirsen A. Electro active Polymer Materials, Technomic Publishing, Lancaster, PA, 1986.

[4] Gregorio R J R, Ueno E M. “Effect of Crystalline Phase, Orientation and Temperature on the Dielectric Properties of PVDF”, Journal of Material Science, 34, 4489-4500, 1999 [5] Xu H, Shanthi H, Bharti V, Zhang Q M. “Structural,

Conformational, and Polarization Changes of Poly(vinylidene fluoride-trifluoroethylene) Copolymer Induced by High Energy Electron Irradiatio”, Macromolecules, 33, 4125-4131, 2000.