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.
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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
