investigation on transport properties and structural ...

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3. 1.2.2.3 Polymer Solid Electrolyte. 4. 1.2.2.4 Composites Electrolyte. 4. 1.2.2.5 .... electronic conductivity so this is also termed as solid electrolyte (SEs) (Cool, 1981;. Chowdari et ...... W. S. K., Careem, M. A., and West, A. R. 1994. Solid State ...

INVESTIGATION ON TRANSPORT PROPERTIES AND STRUCTURAL CHARACTERIZATION OF SOME NANOMATERIALS FOR FABRICATION OF HYBRID SUPERCAPACITORS

Thesis submitted to

Chhattisgarh Swami Vivekanand Technical University Bhilai (India) For award of the degree of

DOCTOR OF PHILOSOPHY in Applied Physics by

Nirbhay Kumar Singh Enrollment No.: AM 6538 February 2014

© 2014 Nirbhay Kumar Singh. All rights reserved.

INVESTIGATION ON TRANSPORT PROPERTIES AND STRUCTURAL CHARACTERIZATION OF SOME NANOMATERIALS FOR FABRICATION OF HYBRID SUPERCAPACITORS

Thesis submitted to

Chhattisgarh Swami Vivekanand Technical University Bhilai (India) For award of the degree of

DOCTOR OF PHILOSOPHY in Applied Physics by Nirbhay Kumar Singh Under the Guidance of

Dr. Mohan L. Verma February 2014

© 2014 Nirbhay Kumar Singh. All rights reserved.

DECLARATION BY THE SCHOLAR I the undersigned solemnly declare that the report of the thesis work entitled “Investigation on Transport Properties and Structural Characterization of Some Nanomaterials for Fabrication of Hybrid Supercapacitors” is based on my own work carried out during the course of my study under the supervision of Dr Mohan L. Verma. I assert that the statements made and conclusions drawn are an outcome of my research work. I further certify that i.

The work contained in the thesis is original and has been done by me under the general supervision of my supervisor.

ii.

The work has not been submitted to any other Institute for any other degree/diploma/certificate in this University or any other University of India or abroad.

iii.

I have followed the guidelines provided by the University in writing the thesis.

iv.

I have conformed to the norms and guidelines given in the concerned Ordinance of the University.

v.

Whenever I have used materials (data, theoretical analysis, and text) from other sources, I have given due credit to them by citing them in the text of the thesis and giving their details in the references.

vi.

Whenever I have quoted written materials from other sources, I have put them under quotation marks and given due credit to the sources by citing them and giving required details in the references.

Nirbhay Kumar Singh Enrollment No.: AM 6538

CERTIFICATE FROM THE SUPERVISOR This is to certify that the work incorporated in the thesis entitled “Investigation on Transport Properties and Structural Characterization of Some Nanomaterials for Fabrication of Hybrid Supercapacitors” is a record of research work carried out by Nirbhay Kumar Singh bearing Enrollment No.: AM 6538 under my guidance and supervision for the award of Degree of Doctor of Philosophy in the faculty of Applied Physics of Chhattisgarh Swami Vivekanand Technical University, Bhilai, Chhattisgarh, India. To the best of my knowledge and belief the thesis i)

Embodies the work of the candidate himself

ii)

Has duly been completed

iii)

Fulfils the requirement of the Ordinance relating to the PhD degree of the University and

iv)

Is up to the desired standard both in respect of contents and language for being referred to the examiners.

(Dr. Mohan L. Verma) Supervisor

Forwarded to Chhattisgarh Swami Vivekanand Technical University, Bhilai

(Dr. P. B. Deshmukh) Director Shri Shankaracharya College of Engineering and Technology Junwani, Bhilai (Chhattisgarh)

ACKNOWLEDGEMENTS

It is a matter of immense pleasure and pride for me to extend my sincere thanks and deep sense of gratitude to my ‘Guruji’, Dr. Mohan L. Verma for his expertise, painstaking guidance, foresightedness, strong will and his positive and simple approach to solve every kind of problems. I have been overwhelmed by his constant encouragements. Extra-care and affections throughout the tenure of my Ph.D. I am quite fortunate to have been associated with him. I also express my deep sense of gratitude to Dr. R. C. Agrawal (Pt. RSSU Raipur, C.G.), Dr. S. L. Agrawal, (A P S, University, Riwa, M.P.), Dr. Ameresh Chandra (IIT Kharagarpur, W. B.) for providing their lab facilities and help during my research work. I will forever be deeply grateful to Dr. Mannikam Minakshi (Murdoc, University, Australlia), Dr. S. K. Panday, V. C. Pt. R S S U Raipur, Dr. N. K. Chakradhari, Prof. Pt. R S S U, Raipur, Dr. Dinesh Sahu, Researcher, Pt. R S S U, Raipur, Dr. Alok Bhatt, Prof. C C E T, Bhilai, Dr. Ranveer Singh, Prof. Sagar University, M.P., for insightful discussion, encouragement and personal attention. I would like to express my special thanks to all faculty member of my research centre, especially Dr. R. P. Patel, Dr. Mimi Pateria, Dr. D. S Raghuvahshi, Dr. K. Deshmukh, Dr. B. Kehsev Rao, Mr. Homendra Sahu, Mrs. Manmeet Kaur and staff members, Mr. Chandra Shekhar Verma, Mr. S. Pandey, Mr. Sohan for their friendly cooperation during my research. I also express special thanks to Dr. Nalini. Dixit, Mr. Jay Verma, Mr. Rohit Verma, Mr. Amit Shrivastava, Mr. O. P. Verma, Mr. P. K. Singh, Mrs Mili. Singh, Dr. A. Singh, Dr. A. Diwakar, Mr. A. Taide who always helped me during the tenure of research work. I owe my deep regards and thanks to Shri V. P. Sharma, Presicent (SSIET), Shri I. P. Mishra, Chairman (SSIET), Dr. Deepak Sharma, Principal (SSIET), Dr. Monisha Sharma, Director (SSIET) for granting me permission and special relief to carry out my Ph.D. work. Finally, I would like to express my sincere gratitude to all of them; who helped me directly or indirectly during Ph.D. work.

Nirbhay Kumar Singh

ABSTRACT

Solid state ionics is the study of solid electrolytes and their uses. Some materials fall into this category, including inorganic crystalline and polycrystalline solids, ceramics, glasses, polymers and composites. It shows several technological promises in the various solid state electrochemical devices viz. solid state batteries, fuel cells, electro chromic displays, sensors, super capacitors etc. Solid state ionic materials are termed as Superionic Solids or Fast Ion Conductors or Solid Electrolytes or Hyperionic Solids. A large number of fast ion conductors with various mobile cations as well as anions have been investigated. In the composite electrolyte systems a better enhancement in the conductivity have been achieved by the dispersion of nano-size particles in the ionic host salt. Many experimental works have been done in this regards to understand the mechanism responsible for the enhancement of ionic conductivity. In the present thesis, preparation of poly ethylene oxide (PEO) based composite polymer electrolytes and electrodes for supercapacitor applications are reported. The investigation on interaction between the various components in the composite polymers and the surface functionalization of inert filler (SiO2, Al2O3) particles to improve the compatibility between the inorganic and polymer phases are reported. The hot press technique is used for the casting of polymer electrolytes at room temperature. Various measures are taken for the enhancement of amorphousity of the polymer membrane. The impedance spectroscopic technique is used for materials characterization, i.e. conductivity (σ) and activation energy (Ea). DC polarization method and TIC technique are used for the analysis of ionic transference number (tion). The composites are characterized by scanning electron microscopy (SEM), thermo gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetric (DSC) and X-ray diffraction (XRD) analysis. The electrochemical transport properties of the composite polymer electrolytes are determined by electrochemical impedance spectroscopy (IS) and direct current (DC) polarization method. Finally, thin supercapacitors are prepared and their performance is analyzed by impedance spectroscopy (IS), Bode plot, cyclic voltommetry (CV), discharge characteristics and leakage current profile. At last, a modeling is performed for the performance of hybrid electric vehicle (HEV) run by supercapacitor, battery and ultrabattery by using MATLAB software.

i

LIST OF TABLES

Table No. 2.1

Heading Room Temperature Values of Conductivity, Mobility and

Page No. 10

Carrier Concentration of Electronic and Ionic Solid 2.2

Some Important Framework Crystalline Superionic Solids

17

2.3

Some Important 2-Phase Composite Electrolyte Systems

22

Along With Conductivity Value and Order of σ-Enhancement 2.4

Some Important Glassy Electrolyte Systems Along With

28

Conductivity Value 2.5

Some Selected Polymer Hosts, Their Corresponding

31

Chemical Formulae and Tg/Tm Values 2.6

Some Important Plasticized Polymer –Salt Electrolytes Along

34

With Their Conductivity Values 2.7

Some Important Polymer Gel Electrolytes (Conventional and

35

Composite) Along With Their Conductivity Values 2.8

Some Important 2-Phase Composite Electrolyte Systems

42

Along With Conductivity Value and Order of σ-Enhancement 2.9

Specific Capacitances of Some Polymer Composite Electrode

49

Materials 2.10

Comparisons of Capacitor, Supercapacitor and Battery

55

3.1

FTIR Peak for PEO Based Polymer Electrolyte

74

4.1

Experimental Data of Prepared Polymer Electrolyte

106

4.2

Initial and Decomposition Temperatures and Percentage of

116

Total Weight Loss 4.3

Content of Different Element in SPE(OCC) ii

122

4.4

Content Present in NCPE(OCC)-I and NCPE(OCC)-II

127

5.1

Elements Present in PAC(OCC)

141

5.2

Summary of Electrochemical Performance of Supercapacitor

154

6.1

Battery and Supercapacitor Parameters Used

158

iii

LIST OF FIGURES

Figure No. 2.1

Caption

Page No.

Log σ vs. l000/T Plot of Some NICs, Crystalline and Glassy

10

SICs. 2.2

Two Possible Crystal Structures of α-AgI Unit Cell.

13

2.3

Cluster Induced Distortion Model: Site:A (Ag+-Occupied),

14

Site: B (Ag+-Empty), Site: C (I- Occupied) Sublattices for AgI. B Sublattices Progressively Get Occupied on Heating (Ishii and Kamishma, 1999). 2.4

(i) Schematic Representation of a Dispersoid Particle (A)

24

Embedded into Host Salt (MX) and Bearing a Space Charge Layer of Thickness λ, (ii) Spherical Approximation of A Phase Particle, (iii) Schematic Cross Section View of a Single A-Phase of Radius rA, (iv) Defect Concentration Profile in Space Charge Region, (v) Average Excess Charge Density in the Space Charge Region. 2.5

A Segment of a Polyethylene Oxide Chain.

40

2.6

Cation Motion in a Polymer Electrolyte Assisted By Polymer

44

Chains Only (Wang et al., 2006). 2.7

Cations Motion in a Polymer Electrolyte Facilitated By the

45

Ionic Cluster (Wang et al., 2006). 2.8

A Schematic Diagram Showing a Single Grain Dispersed in

45

the Polymer electrolyte Matrix. 2.9

Schematic

Diagram

of

All-Solid-State

(S/S/S)

Cell

50

Configuration. 2.10

A General Configuration Fuel Cell System.

iv

51

2.11

Schematic

Diagrams

of

Conventional

Capacitor

and

52

Supercapacitor. 2.12

Construction of Ultrabattery.

3.1

Experimental

54

Arrangement

of

Electrical

Conductivity

60

Complex Impedance Plots for Some Elementary R, C and RC

61

Measurement By IS Technique. 3.2

Circuits. 3.3

Typical Electrochemical Cells and Their Equivalent Circuits

61

Along With Complex Impedance Plots With: (i) Non-Bulk Electrode and (ii) Bulk Electrodes. 3.4

Typical Impedance Plots for Different Resistive Element (Rb,

62

Rgb, Rel ). 3.5

(a) Experimental Set-Up for Wagner’s DC Polarization Measurements

and (b) TIC

Plot

for

64

Ionic Mobility

Measurement. 3.6

Schematic Diagram of Scanning Electron Microscope.

68

3.7

Typical EDS Pattern of a Material.

70

3.8

Schematic Representation of Diffraction of X-Rays By a

71

Crystal. 3.9

(a) Schematic Representation of FTIR Ray Diagram and (b)

73

Block Diagram of the FTIR Spectrophotometer. 3.10

Thermogravimetric Curve of Some Polymer Electrolyte.

76

3.11

Experimental Setup for DSC Studies.

77

3.12

DSC Thermograms (a) Glass Transition Tg, (b) Crystallization

78

Tc, (c) Melting Tm. 3.13

V-t Curve of Cyclic Voltammetry.

80

3.14

I-V Curve of Cyclic Voltammetry.

81

3.15

Discharge Curve of Supercapacitor.

82

3.16

Leakage Current of Supercapacitor.

82

4.1

Cole-Cole Plot for Different Composition of SPE.

87

v

4.2

Variation of Conductivity vs. wt% of AgI in PEO.

88

4.3

Cole-Cole Plot for NCPE-I.

89

4.4

Cole-Cole Plot for NCPE-II.

89

4.5

Variation of Conductivity of NCPE-I.

90

4.6

Variation of Conductivity With Filler of NCPE-II.

91

4.7

(a-e) Cole-Cole Plot of

95

(1-x)PEO:xAgI at Different

Temperatures. 4.8

Arrhenius Plot of SPE.

96

4.9

Activation Energy vs. Salt wt% ( σ-x) Plot for SPE.

96

4.10

(a-f) Cole-Cole Plot of NCPE –I at Different Temperatures.

100

4.11

(a-f) Cole-Cole Plot of NCPE-II at Different Temperatures.

102

4.12

Log σ – 1000/T Plot of NCPE-I.

103

4.13

Log σ – 1000/T Plot of NCPE-II.

103

4.14

Variation of Activation Energy Ea of NCPE-I.

104

4.15

Variation of Activation Energy Ea of NCPE-II.

104

4.16

Current vs. Time Plot of (a) SPE(OCC), (b) NCPE(OCC)-I

105

and (c) NCPE(OCC)-II. 4.17

(a-c) Various Impedance Parameters of SPE (OCC).

109

4.18

(a-c) Various Impedance Parameters of NCPE(OCC)-I.

112

4.19

(a-c) Various Impedance Parameters of NCPE(OCC)-II.

113

4.20

TGA Curve of (a) Pure PEO, (b) SPE(OCC), (c) NCPE

115

(OCC)-I and (d) NCPE (OCC)-II. 4.21

DSC Thermogrames of (a) Pure PEO, (b) SPE(OCC), (c)

118

NCPE(OCC)-I and (d) NCPE(OCC)-II. 4.22

(a,b) SEM of Pure PEO at Two Different Magnifications.

120

4.23

(a,b) SEM of SPE(OCC) at Two Different Magnifications.

121

4.24

EDS of SPE(OCC).

122

4.25

(a-c) SEM of Prepared NCPE(OCC)-I.

124

4.26

(a-c) SEM of NCPE(OCC)-II at Different Magnification.

126

4.27

EDS of NCPE(OCC)-I.

127 vi

4.28

EDS of NCPE(OCC)-II.

127

4.29

FTIR Spectroscopy of (a) Pure PEO, (b) SPE(OCC), (c)

131

NCPE(OCC)-I and (d) NCPE(OCC)-II. 4.30

XRD of (a) Pure PEO, (b) SPE(OCC), (c) NCPE(OCC)-I and

135

(d) NCPE(OCC)-II. 5.1

Cole-Cole Plot for PAC Polymer Electrode.

137

5.2

Conductivity Variation of Polymer Electrode PAC.

138

5.3

TGA Curve of PAC(OCC) Electrode.

139

5.4

(a-c) SEM of PAC(OCC) Electrode at Different Magnification

140

5.5

EDS of PAC(OCC) Electrode

141

5.6

TGA Curve of ESM Used as Separator

143

5.7

Sweling and Water Uptake Properties of ESM.

145

5.8

Cross Section View of Prepared Supercapacitor.

146

5.9

Cole-Cole Plot of Supercapacitor-1.

148

5.10

Cole-Cole Plot of Supercapacitor-2.

148

5.11

Cole-Cole Plot of Supercapacitor-3.

149

5.12

Bode Plot of Supercapacitors

149

5.13

Cyclic Voltommery of Supercapacitor-1.

151

5.14

Cyclic Voltommetry of Supercpacitor-2.

152

5.15

Cyclic Voltommetry of Supercapacitor-3.

153

5.16

Discharge Characteristics of Supercapacitors.

155

5.17

Leakage Current of Supercpacitors.

156

6.1

MATLAB Simulink Modeling of Supercapacitor and Battery.

159

6.2

SOC, Current and Voltage Characteristics of Battery.

160

6.3

SOC, Current and Voltage Characterstics of Supercapacitor.

160

6.4

Supercapacitor and Battery Power.

161

6.5

Model of HEV Run by ESS and Supercapacitor as Peak Power

162

6.6

MATLAB SIMULINK Model of HEV.

165

vii

6.7

(a) Rotar speed and Electromagnatic Torque of HEV Run by Supercapacitor, (b) Rotar Speed and Electromagnatic Torque of HEV Run by Supercapacitor and (c) Rotar Speed and Electromagnatic Torque of HEV Run by Supercapacitor and Ultrabattery battery

viii

166-168

LIST OF ABBREVIATIONS/SYMBOLS AFCs

Alkaline Fuel Cells

CV

Cyclic Voltommetry

DMFCs

Direct Methanol Fuel Cells

DSC

Differential Scanning Calorimetry

DMSO

Dimethylsulfoxide

DMF

Dimethyle Farmamide

DEC

Diethyl Carbonate

DMC

Dimethyle Carbonate

EC

Ethylene Carbonate

e.m.f

Electromotive Force

FTIR

Fourier Transform Infra-Red Spectroscopic

HEV

Hybrid Electricle Vehicle

IS

Impedance Spectroscopic

MCFC

Molten Carbonate Fuel Cells

NCPE

Nanocomposite Polymer Electrolyte

OCC

Optimum Composite Composition

PEO

Polyethylene Oxide

PPO

Polypropylene Oxide

PEG

Poly Ethyleneglycol

PVdF

Poly Vinylidenedi Fluoride

PVC

Poly Vinyle Chloride

PMMA

Poly Methylemethacrylate

PC

Propylene Carbonate

PAN

Poly Acrylonitrile

PMMA

Poly Methylmethaacrylateb

PVDF-co-HFP

Poly Vinylidine Fluoride-Hexafluoroproplene

PEFC

Polymer Electrolyte Fuel Cells

PEMFC

Polymer Electrolyte/Exchange Membrane Fuel Cells

PAFCs

Phosphoric Acid Fuel Cells

ix

Redox

Reduction Oxidation

SOFCs

Solid Oxide Fuel Cells

SOC

State Of Charge

SPE

Solid Polymer Electrolyte

SEM

Scanning Electron Microscope

TGA

Thermogrevemetric Analysis

XRD

X-Rays Diffration Spectroscopic

x

TABLE OF CONTENTS

ABSTRACT

i

LIST OF TABLES

ii

LIST OF FIGURES

iv

LIST OF ABBREVIATIONS/SYMBOLS

ix

CHAPTER 1

AN INTRODUCTION TO SOLID STATE

1-7

IONICS 1.1

Solid State Ionics

1

1. 2

Classification of Ionic Conductors

1

1.2.1

Normal Ionic Conductors

2

1.2.2

Superionic Conductors (SICs)

2

1.2.2.1

Crystalline/Polycrystalline

3

1.2.2.2

Amorphous/Glassy

3

1.2.2.3

Polymer Solid Electrolyte

4

1.2.2.4

Composites Electrolyte

4

1.2.2.5

Nano Composites Electrolyte

5

1.3

1.4

CHAPTER 2

Solid State Electronics Devices

5

1.3.1

Solid State Batteries

5

1.3.2

Fuel Cell

6

1.3.3

Supercapacitor

6

1.3.4

Miscellaneous Devices

6

Purpose, Scope and Objective of Research Work

REVIEW OF LITERATURE

6

8-57

2.1

Historical Background

8

2.2

Characteristics Properties of Ion Conducting

9

Materials 2.3

xi Classification of Solid State Ionics Materials

11

2.3.1

Framework Crystalline/Polycrystalline

12

Electrolyte Phase

2.4

2.3.2

Composite Electrolyte Phase

21

2.3.3

Glassy/Amorphous Electrolyte Phase

27

2.3.4

Polymer Electrolyte Phase

29

Broad Classification of Polymer Electrolytes

30

2.4.1

31

Conventional Polymer Salt Complexes/Dry Solid Polymer Electrolytes (SPEs)

2.4.2

Plasticized Polymer-Salt Complexes

32

and/or Solvent Swollen Polymers

2.5

2.4.3

Polymer Gel Electrolytes

34

2.4.4

Rubbery Electrolytes

36

2.4.5

Composite Polymer Electrolytes

36

PEO-Based Polymer Electrolyte

39

2.5.1

Basic Atomic Structure

39

2.5.2

Physical Property

40

2.5.3

Mechanism of Solvation of Salt in PEO

41

2.5.4

Transport Mechanisms in a Solvent-Free

43

Polymer Electrolyte 2.5.5

Methods for Improving Conductivity of

46

PEO-Based Electrolytes 2.6

2.7

Electrode Materials

47

2.6.1

Carbon Electrode

47

2.6.2

Polymer Electrode

48

2.6.3

Metal Oxides

48

Applications of Polymer Electrolyte Materials

49

2.7.1

Solid State Batteries

50

2.7.2

Fuel Cells

51

xii

2.7.3

Electrochemical Capacitors or

52

Supercapacitors 2.7.4 2.8

CHAPTER 3

UltraBattery

Scope and Relevance of Present Thesis Work

MATERIAL PREPERATION AND

54 55

58-83

CHARACTERIZATION 3.1

3.2

3.3

Method of Preparation

58

3.1.1

Casting Method

58

3.1.2

Spin Coating Method

58

3.1.3

Hot Press Method

58

Techniques Used for Material Characterization

59

3.2.1

Impedance Spectroscopy

59

3.2.2

Wegner’s DC Polarization Method

63

3.2.3

Transient ionic Current (TIC) Technique

64

3.2.4

Transport Number

66

Techniques use for Structural Characterization

67

3.3.1

Scanning Electron Microscopic (SEM)

67

3.3.2

Energy Dispersive X-ray Spectrometry

69

(EDS/EDX) 3.3.3

X-Ray Diffraction (XRD)

70

3.3.4

Fourier transform infrared spectroscopy

72

(FTIR) Study 3.4

3.5

Techniques Used for Thermal Characterization

75

3.4.1

Thermogravimetric Analysis

75

3.4.2

Differential Scanning Calorimetric (DSC)

76

Technique Used for Supercapacitor Characterization xiii

78

3.6

CHAPTER 4

3.5.1

Cyclic Voltammetry

78

3.5.2

Discharge Curve and Leakage Current

81

HEV Modeling Tool : MATLAB Simulink

PREPERATION AND

83

84-135

CHARACTERIZATION OF SOME PEO BASED SILVER ION (Ag+) CONDUCTING POLYMER ELECTROLYTES 4.1

Material Preparation and Method

84

4.1.1

84

Preparation of PEO/AgI Based Polymer Electrolyte

4.1.2

Preparation of PEO/AgI/SiO2 and

85

PEO/AgI/Al2O3 Based Nanocomposite Polymer Electrolyte 4.2

Conductivity Measurement of Polymer Electrolyte

86

4.2.1

86

Salt Concentration Dependent Conductivity Measurement

4.2.2

Filler Concentration Dependent

88

Conductivity Analysis of NCPE-I and NCPE-II 4.2.3

Temperature Dependent Conductivity

92

Study of SPE 4.2.4

Temperature Dependent Conductivity

97

Study of NCPE-I and NCPE-II 4.3

Determination of Ionic and Electronic Transferred

105

Number of Polymer Electrolyte 4.4

Impedance Spectroscopy Study

106

4.4.1

107

Impedance Spectroscopy Study of xiv

SPE(OCC) 4.4.2

Impedance Spectroscopy Study of

110

NCPE(OCC)-I and NCPE(OCC)-II 4.5

Thermogravimetric (TGA) Analysis of Polymer

114

Electrolyte 4.5.1

Thermogravimetric Analysis of Pure PEO

114

and SPE(OCC) 4.5.2

Thermogravitic Analysis of NCPE(OCC)-I

114

and NCPE(OCC)-II 4.6

Differential Scanning Calorimetric (DSC) of

116

Polymer Electrolyte 4.6.1

DSC Analysis of Pure PEO and SPE(OCC)

116

4.6.2

DSC Analysis of NCPE(OCC)-I and

117

NCPE(OCC)-II 4.7

Scanning Electronic Microscopy (SEM) and

118

Energy Dissipative Spectroscopy (EDS) Analysis of Polymer electrolyte 4.7.1

SEM and EDS analysis of Pure PEO and

118

SPE(OCC) 4.7.2

SEM and EDS analysis of NCPE(OCC)-I

122

and NCPE(OCC)-II 4.8

FTIR Analysis of Polymer Electrolyte

128

4.8.1 FTIR analysis of Pure PEO and SPE(OCC)

128

4.8.2 FTIR Analysis of NCPE(OCC)-I and

129

NCPE(OCC)-II 4.9

X- Rays Diffraction (XRD) Analysis of Polymer

132

Electrolyte 4.9.1

XRD analysis of Pure PEO and SPE(OOC)

132

4.9.2

XRD analysis of NCPE(OCC)-I and

132

xv

NCPE(OCC)-II

CHAPTER 5

SUPERCAPACITOR FABRICATION AND

136-157

PERFORMANCE ANALYSIS 5.1

Preperation and Characterization of Electrode

136

5.1.1

136

Preparation of PEO/AgI/AC based Electrode

5.1.2

Preparation of PEO/AgI/AC based

136

Electrode 5.1.3

Thermal Characterization of Electrode by

138

TGA 5.1.4

Morphology Characterization of Electrode

139

by SEM and EDS 5.2

Preparation and Characterization of Separator

142

5.2.1

Preparation of ESM as Separator

143

5.2.2

Thermal Characterization of ESM by TGA

143

5.2.3

Swelling and Water uptake properties of

144

ESM 5.3

Preparation and Characterization of Solid State

146

Supercapacitor 5.3.1

Impedance Spectroscopy Analysis of

147

Supercapacitors 5.3.2

Cyclic Voltommetry Analysis

150

5.3.3

Discharge Characteristics and Leakage

155

Current of Supercapacitor 5.3.3.1

Self Discharge Characteristics of

155

Supercapacitors

5.3.3.2 Leakage Current of xvi

156

Supercapacitor

CHAPTER 6

MODELING AND SIMULATION OF

158-169

HYBRID ELECTRIC VEHICLE 6.1

The Need of Hybrid Electric Vehicles

158

6.2

MATALAB Simulink Model of Supercapacitor

158

6.3

Model of Hybrid Electric Vehicle

163

6.4

Mathematical Modeling for Number of

164

Supercapacitors in HEV

CHAPTER 7

6.5

MATLAB Simulink Modeling of HEV

165

6.6

Resultant Outcome by Simulink

166

SUMMARY AND CONCLUSIONS

170-173

Summary

170

Conclusions

171

174-197

REFERENCES PUBLICATIONS BY THE AUTHOR

198

ANNEXURE

199

xvii

CHAPTER – 1

AN INTRODUCTION TO SOLID STATE IONICS

1.1 Solid State Ionics Solid State Ionics (SSI) is an interdisciplinary area of research for the physicists, chemists, material scientists, engineers and technologists deals with the properties of ionic solids, which exhibit a wide range of ionic conductivity (10-1 to 10-13 S/cm)(Tuller, 1989; Takahashi and Munshi, 1995; Bunde, 1998; Chawdari, 1998; Funke ,2005; Pandey and Hasmi, 2010). Some class of ionic solids exhibit higher conductivity order of 10-6 S/cm and more are called superionic conductors(SICs), fast ionic conductors (FICs). Since the value of conductivity is of the order of liquid electrolytes with negligible electronic conductivity so this is also termed as solid electrolyte (SEs) (Cool, 1981; Chowdari et al., 1988; 1992; 1996; West, 1989; Tetsuichi, 1990, Hench, 1990; Chen, 2001; Klein, 2002; Pereira, 2002; Kartini, E., 2002; 2004; 2008; Minakshi, 2012). It has potential applications in various electrochemical devices, such as, solid state batteries, sensors, timers, fuel cells, memory devices, capacitors, supercapacitors etc. The main attractive properties of superionic conducting materials are high ionic conductivity, stability, ruggedness, miniaturization, wide range of operating temperature, etc. (Chowdari, 1998; Fusco, 1989). Superionic conducting materials are synthesized by various techniques such as melt quench, sol-gel process, solid state reactions, thermal evaporation, sputtering and hot press etc. for different ionic device applications.

1.2 Classification of Ionic Conductors In crystalline solid, ion conduction occurs because of imperfections or defects and also due to the long range diffusion of ions. The flow of ions through the lattice occurs in two ways, i.e. via interstitial sites (Frenkel disorder) or hopping through the vacancies at the normal lattice sites (Schottky disorder). On the basis of physical properties and microstructure, superionic solid are classified into following phases: Normal ionic conductors, Super ionic conductors. 1

1.2.1 Normal Ionic Conductors Ionic conductors having the conductivity in the order of 10-13 to 10-6 S/cm at ambient temperature, for example KCl, NaCl etc. are called normal ionic conductors (NICs). The activation process involves the energy due to defect formations as well as energy due to ion migration (Leroy, 1978; Haldik, 1985). It has high activation energy, and high conductivity just below melting point. The number of mobile charge carrier (1016- 1018) are strongly temperature dependent.

1.2.2 Superionic Conductors (SICs) Some materials have a high ionic conductivity of the order of

10-6 – 10-1 S/cm or more

with negligible electronic conductivity of the order of ~10-12 S/cm at room temperature as well as high temperature (Chandra, 1980; Fusco, 1989; Bunde, 1998; Chowdhari, 1999; Kreuer, 1999; Funke, 2005) are called 'superionic' conductors (SICs). Mobile charge carriers are almost temperature independent (1022 cm-3). These conductors are of two type, anionic conductors and cationic conductors. Superionic conductors with negative ions as charge carriers are called anionic conductors. It shows poor ionic conductivity at ambient temperature. These are of two types, Oxide ion and Fluoride ion conductors. In oxide ion conductor, oxygen ion is responsible for conduction, viz. Bi2Zn0.1V0.9 O5.35, Bi2O3-WO3, ZrO2-Y2O3, Zr1-xYxO2-x/2 (Martin, 2005; 2008). In fluoride ion conductors fluorine is responsible of ion conduction viz. CaF2, SrF2, KBiF4, LaF3, Zr-Ba-CCs-F etc. (Leroy,1978; Chandrasekhar,1978) TBAPF6 (Martin, 2008). In cationic conductors positive ion Li+, Na+, Ca+, Ag+ are responsible for current conduction, mainly; Lithium ion conductors: LiAlSiO4, Li5GaO4, Li4AlO4, Li6ZnO4 and Li+, Na+, β- alumina, LiNi0.5Mn0.5O2 (Zhao, 2008), LiMnO2 (Ohzuku et al., 2001). Copper ion conductors: αCuI, Cu2ICdI4, Cu2HgI4, Cu2Se, Rb4Cu16I7Cl13 and KCu4I5 (Philips, 1977), Ag1-xCuxI (Hamakaswa et al., 2008). β-alumina conductor: A2O3B2O (A = Al3+,Ca2+,Fe3+, B = Na+,K+,Rb+,Ag+,Ti+,H3O+, etc) (Qui, 1981; Zhao et al., 2008). Protonic conductor: hydrogen uranyl phosphate H8UO2(IO6).4H2O, polyanudes and polysulfinimide (Belushkin et al., 1999; Feki et al., 2001; Matsuda

et al., 2002; 2

Tadanaga, et al., 2002). Silver ion conductor: Ag6I4WO4, RbAg4I5, KAg4I5, NH4Ag4I5, Ag7I4PO4, Ag6I4CrO4, Ag6I4MoO4 etc. (Bradley et al., 1966; Owens et al., 1967; Hamakawa 2008), AgI, Ag2O-V2O5, (Dalvi et al., 2008). On the basis of phaseace and microstructure superionic conductor classified as: crystalline/polycrystalline, amorphous/glass, composites, polymer.

1.2.2.1 Crystalline/Polycrystalline Number of crystalline cation (Ag+,Cu+,Li+,Na+,H+,etc), anion (O2-, F-) and mixed ion (K+,Rb+,Ag+,I-,CN-,β Alumina etc.) SIC compounds have been reported. The Silver ion conducting compounds are mostly based on AgI and are synthesized by substituting either cation or anion or both (Bradley 1966; Owens et al., 1967; Schlaikjer 1973; Philips 1977; Chandrasekhar et al., 1978; Takahashi, 1980; Qui et al., 1981; Chandra et al., 1981; Minarni 1985; Fusco et al., 1989; Takahashi et al., 1995; Bunde et al., 1998; Chowdari et al., 1999; Belushkin et al., 1999; Feki et al., 2001; Mizuno et al., 2002; Kohjiya et al., 2002; Hayashi et al., 2002; Matsuda et al., 2002; Tadanaga 2002; Long et al., 2003; Funke et al., 2004; Machida, 2005; Anshuman et al., 2003).

1.2.2.2 Amorphous/Glassy Electrolyte Glassy superionics solids are found to exhibit an excellent conductivity due to their structural and thermodynamic properties. A wide range of glass formers have been used to form different types of local structures. The conductivity increases with the addition of alkali oxides and halides. Presence of two glass formers also enhances the conductivity. Large number of high ionic conducting glassy compounds with different types of ionic species, like Ag+, Cu+, Li+, Na+, H+, F-and O2- have been reported (Charles, 1961; Chiodelli, 1976; Minami, 1977; Hashmi et al., 1988; Agarwal et al., 1994;1995; Adams et al., 1996; Deshpandey et al., 2002; Dalvi, 2004; Ranveer et al., 2008; Deshpandey et al., 2008) and studied. Ag+ and Li+ conducting glasses attract worldwide in the recent year due to their fundamental and technological aspects as well as several advantageous over their crystalline/polycrystalline counterpart viz. high isotropic ionic conductivity at room temperature with low activation energy for ion migration, extremely low electronic conduction, absence of grain boundaries, possibility of wide range of compositional 3

variations for glass formation, possibility of molding into any desired shape and thin film formation greater thermal stability below the glass transition temperature (Tg), good workability etc.

1.2.2.3 Polymer Solid Electrolyte The polymer electrolyte are new class of fast ion conducting system, having several unique advantageous material properties over other solid electrolyte (MacCallum and Vincent, 1987; Ratner and Shriver, 1988; Armand, 1986; Watanabe and Ogata, 1988; Watanabe, 1992; Chandra, 1994). It is synthesized by dissolving the salt of alkali metals of type MX (M = Na, Li, Ag, NH4, Cu, etc) and (X= F, Cl, I etc) in polymer, like polyethylene oxide, polypropylene oxide etc. Polymer solid electrolytes are classified as solvent free salt complexes, solvent swollen polymers and polyelectrolyte. These can be prepared in the form of bulk as well as thin film (Bradley, 1965; Owens et al., 1967; Sorensen, 1983; Goreeki, 1986; Wintersgill, 1984; Mallick, 2000; Feki et al., 2001; Sun, 2001; Matsuda et al., 2002; Tadanaga, 2002; Sasaki, 2002, Verma et al., 2008; 2012; Suriani et al., 2012).

1.2.2.4 Composites Electrolyte Composites are also called dispersed or multiphase heterogeneous solid electrolyte. Liang (1973) has reported the enhancement in the ionic conductivity of lithium ion in the LiI-Al2O3 system. These electrolytes are classified into four categories. Crystal-crystal, crystal- polymer, crystal- glass, glass-polymer composite. Designing composite solid electrolyte with better control of important physical and chemical properties is an active area of research. In crystal-crystal composite, moderate ion like silver halides, copper halides etc. are taken as first phase host material and an another ionic solid (such as AgCl or AgBr in AgI) or an inert and insulating material (Al2O3, SiO2, SnO2, ZrO2 etc.) as the second phase dispersoid (Nagai and Nishino, 1992; 1994). High ion conducting glasses are dispersed into the polymer electrolyte during the sample preparation in crystal-polymer electrolyte. Crystal-glass composite consists α-AgI frozen into a glass-matrix of Ag2O:MxOy (MxOy = B2O3, CeO2, WO3, P2O5, V2O5, MoO3 4

etc.) (Tatsumisago et.al., 1991; Minami et al., 1998). In glass-polymer electrolyte organic/inorganic filler like PEO-PMMA, Al2O3, SiO2, NASICON, β-Alumina, LiAlO3, LiClO4 etc. are dispersed (Przyluski et al., 1992).

1.2.2.5 Nano Composites Electrolyte When fine particle size of second phase dispersoid i.e. Al2O3, SiO2, SnO2, ZrO2, TiO2 etc. are dispersed into AgI, AgCl, LiI, CuI, AgBr, LiCl etc. termed as first phase host matrix (Shahi and Wagner, 1982; Agrawal et al., 1992; Maier, 1998; Agarwal and Gupta, 1999; Yamada et al., 2002) are called nano-composite electrolytes. The ion transport mechanism in these systems explained by different model such as space charge model (Jow and Wangner, 1979), Pack’s model (Pack, 1976), resister network model (Dudney, 1985), percolation model (Bunde et al., 1985) and concentration gradient model (Shastry and Rao, 1992) etc. These electrolytes attracted great interest in recent years due to their new and enhanced properties, which have been exploited in very different applications.

1.3 Solid State Electronics Devices Solid state Ionics material used in different electrochemical devices i.e. solid state batteries, electrochemical display devices, fuel cell, sensor, colometer timer, electrochemical supcapacitor etc.

1.3.1 Solid State Batteries Batteries are portable power sources providing continuous electrical energy to run a wide variety of electronic/digital appliances. Majority of the commercially available batteries are based on liquid/aqueous electrolytes. A large number solid state electrochemical battery have been fabricated/tested as well as commercially manufactured in variety of shapes/sizes. It works on a simple principle of electrochemical redox reaction. These chemical reactions involve the usual Gibbs free energy which ultimately leads to the generation of an e.m.f. across the two electrodes.

5

1.3.2 Fuel Cell Fuel cells are electrochemical devices composed of an anode, an electrolyte and cathode which also easily convert chemical energy into electrical energy like battery and supercapacitor. These are capable of delivering electrochemical voltage and current continuously. One type of electrochemical species (H2O, CO, CH4 etc.) is being continuously consumed at one of the electrode or electrolyte (Etsell and Flengs, 1970; Mazanec et al., 1992; Iwahar 1996).

1.3.3 Supercapacitor The electrochemical double layer capacitor (EDLC) also known as supercapacitor. Its technology is similar to the batteries involving particularly of electrostatic phenomenon (Non Faradic) and higher power density. Supercapacitor are structured of two electrodes, a separator and an electrolyte. Charge transfer at the boundary energy depends on electrode surface, size of the ions and the level of electrolyte decomposition voltage. It has high power density but low energy density. It can be used as power source in several electronic circuits, accelerator, hybrid vehicle, engine starter, pulsed generator for mobile telecommunication (Jow and Zheng, et al., 1995). Present work is devoted to supercapacitor therefore this part is explained in Chapter-5.

1.3.4 Miscellaneous Devices In addition to above solid state electrochemical devices the solid state ionics material are also used to fabricate memory devices Electrolyzers (Iwahara 1994), Colometer timer (Kennedy et al., 1977; 1986) and Sensor (Fitterer, 1966; Madou et al., 1992; Mathewe, 1992) etc.

1.4 Purpose, Scope and Objective of Research Work The supply of fossil fuel (coal, petrol, diesel, natural gasoline etc.) is adequate at present. However, we would be in trouble when these fuels are seriously depleted. Hence, and alternate source with equivalent energy density and power density must be explored before fossil fuels get exhausted. Rechargeable batteries and supercapacitor are 6

seemingly the most appropriate and promising options as supplement source of energy. In this work we develop polymer electrolyte and electrode material for supercapacitor application and studied their transport properties, material and thermal characterization. With the prepared conducting polymer electrolyte and composite electrode material small supercapacitor is fabricated. Their characteristics properties i.e. capacitance and power density, analyzed by cyclic voltammetery. A model of hybrid electric vehicle (HEV) run with supercapacitor, battery, ultrabattery and combination of these is suggested. A comparative performance studies was performed using MATLAB Simulink software.

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7

CHAPTER – 2

REVIEW OF LITERATURE

2.1 Historical Background Ag2S was one of the earliest known ionic solid to exhibit very high ionic conductivity at high temperature (Farade, 1883). Highest ionic conductivity was obtained in AgI, when it was heated beyond 147 ºC (Tubandt and Lorenz, 1912; 1914). This temperature had been well identified as the transition temperature (Tc) at which AgI undergoes an abrupt 1st order structural change from a low conducting β-phase (hexagonal) to high conducting α - phase (cubic). A typical 3-4 orders enhancement in the conductivity was observed in AgI after 147ºC. This is one of the unique characteristic features of AgI. AgI in the α phase ( ≥ 1470C) is a pure Ag+ ion conducting superionic solid with ionic conductivity as high as ~1 Scm-1. The experimental study on temperature variation of conductivity in AgI (Tubandt and Lorenz , 1914) has been marked as the first systematic investigation in search for high ionic conduction in solid systems. Other ionic salts identified earlier for their high ionic conduction including: α - Li2SO4 ( Benrath and Drekopf, 1921), α-CuI (Tubandt et al., 1928), α- and β- CuBr (Geiler, 1928 ), α – Ag2HgI4 (Ketelaar, 1934), Ag3SI (Reuter and Hardel, 1961; 1965; 1966; Takahashi and Yamamoto, 1964; 1965; 1966 ) etc. The solid solution of double salt: Ag2S:AgI, Ag3SI exhibited very high Ag+ ionic conductivity (σ ~ 10-2 Scm-1) at room temperature, which brought revolution in the quest for materials exhibiting high ion conduction at room temperature. The area 1967 has been marked as the beginning of solid state ionics when two groups of solids: MAg4I5 (M = Rb, K, NH4) and Na - β - alumina, were discovered (Owens and Argue, 1967; Yao and Kummer, 1967). A wide variety of solid state ionic materials involving different kinds of ions viz. H+, Ag+, Cu+, Li+, Na+, O2-, F1- etc. as mobile species, has been reported since then. These superionic materials show tremendous technological potentials to develop variety of solid state electrochemical 8

devices. Number of articles/books/monographs/conference proceedings exist in the literature which would be helpful to review the progress made in the field of Solid State Ionics since its inception (van Gool, 1973; Mahan and Roth, 1976; Chandra, 1981; Boyce et al., 1986; Chowdary et al., 1992;1994; 1995; 1998; 2002; 2004; 2006; Maier, 2000; Badwal, 2002; Khalifa and ElMashri, 2002; Hull, 2004; Sunandana and Kumar, 2004; Martin et al., 2005; Niiya et al., 2006; Lange and Nilges., 2006; Ivers- Tiffee et at., 2006; Chaudhary, 2008). Lots of fast ion conducting materials has been discovered in the last 45 decades (Van Gool, 1973; Mahan and Roth, 1976; Kulkarni et al., 1977; Chandra, 1981; Boyce et al., 1986; Munshi et al., 1995; Souquet, 1995; Maier et al., 2000; Badwal, 2002; Khalifa and El Mashri, 2002; Hull, 2004; Sunandana and Kumar, 2004; Martin et al., 2005; Niiya et al., 2006; Lange and Nilges, 2006; Ivers- Tiffee et al., 2006; Chowdary et al., 1992; 1994;1995; 1998; 2002; 2004; 2006; 2008, 2010; Verma et al., 2008). Now a days, a new area of activity referred to as ‘Nanoionics’ has been initiated (Schooman, 2000; Maier, 2000; Despotuli et al., 2003; 2004; 2005). ‘Nanoionics’, drawing considerable attention worldwide as it is expected that this novel phase of solid state ionics materials will involve new phenomena/effects akin to nano science/nanotechnology which is currently one of the most sought for and frontline area of research. Now a days, PEO based polymer electrolyte is an active area of research which brings attention of researcher in this field (Wright et al., 1973; Agrawal, 2008).

2.2 Characteristics Properties of Ion Conducting Materials The room temperature value of some basic transport parameters (conductivity, mobility and carrier concentration) for various electron and ion conducting materials is shown in Table 2.1. Superionics solids behave as electronic insulators and have extremely high ionic conductivity (Wert and Thomson, 1964; Chandra, 1981; Agrawal and Gupta, 1999). Temperature variations of ionic conductivity for some important ionic/superionic solids along with some liquid/aquous electrolyte systems are mentioned in Fig. 2.1. One can note that the conductivity of several superionic systems is extremely close to liquid/aqueous electrolytes.

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Table 2.1: Room Temperature Values of Conductivity, Mobility and Carrier Concentration of Electronic and Ionic Solids.

Type

Material

Conductivity (S/cm)

Mobility (cm2V-1s-1)

Carrier Concentration

~105

~102

(cm-3) ~1022

Semiconductors

~10-5-100

~103

~1010-1013

Superionic solids

~10-1-10-4

Ionic

Normal Ionic

~10-5-10-10

Conductors

Solids

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