A thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy (Engineering)

RECHARGEABLE Ni-Zn MICROBATTERIES EMPLOYING MCM-41 SEPARATOR

BY

SHAHRUL RAZI MESKON

A thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy (Engineering)

Kulliyyah of Engineering

International Islamic University Malaysia

APRIL 2018

ii

ABSTRACT

Although MCM-41 inorganic membrane could act as separator in primary cells such as zinc-air and zinc-manganese dioxide, its efficacy in a rechargeable cell such as nickel-zinc (Ni-Zn) has never been determined. The impracticality of MCM-41 incorporation in Ni-Zn battery system is fortified by the fact that silica is etched away by potassium hydroxide (KOH); besides, MCM-41 transforms into MCM-50 in a concentrated KOH. In order to ascertain the hypothesis, MCM-41 inorganic membrane was employed as a separator in the Ni-Zn cells and microbatteries. Its hexagonally arranged pore channels are expected to act as an electrolyte reservoir and ionic diffusion pathways for the electrochemical reactions. It is due to the hydrophilic nature of its pore walls and the high surface area it possesses. A multilayer MCM-41 thin film was synthesized onto the nickel hydroxide electrode by drop coating of the parent solution consisting of cethyltrimethylammonium bromide (CTAB), hydrochloric acid (HCl), distilled water (H2O), ethanol (C2H5OH) and tetraethyl orthosilicate (TEOS) with a molar ratio formulation of 0.05 CTAB, 1.0 TEOS, 0.5 HCl, 25 C2H5OH and 75 H2O. Zinc and nickel hydroxide thin films were electrodeposited onto copper current collectors to form the anode and the cathode, respectively and a zinc oxide slurry was drop coated onto the electrodeposited zinc, forming a complete anode. The structural formation of MCM-41, zinc and nickel hydroxide was confirmed by X-ray diffraction (XRD) measurements. The surface morphologies of the zinc and nickel hydroxide essentially consisted of nanoflakes and hierarchically structured aggregated nanoparticles, respectively. The structural integrity study of MCM-41 separator in the Ni-Zn cells showed that the MCM-41 partially transformed into MCM-50 phase at the early stage of charge-discharge process i.e. the 5th cycle, almost completely at the 25th cycle, while completely at the 80th cycle. The viability of MCM-41 as separator for alkaline secondary cells was confirmed through the structural properties of the resulting separator materials and the discharge capacity profiles. The reversibility of zinc electrodes in various KOH- MCM-41 surrounds was demonstrated in the cyclic voltammetry measurements which lead to a conclusion that 70:30 KOH-to-MCM-41 weight ratio should result in a lower solubility of zinc discharge products in the electrolyte. Very thin, circular shaped rechargeable Ni-Zn microbatteries were fabricated employing a side-by-side-electrode design with an electrode separation distance of ca. 800 µm. The microbatteries sustained > 130 cycles of cycling with a high depth of discharge. The microbatteries were 200 µm thick, measured 6.41 cm² in area and weighed 1.14 g (excluding the cap and the substrate). The microbattery discharged at a rate of 0.1 mA possessed an energy density of 3.82 Wh l^-1 and power levels of 0.014–0.023 mW cm^-2 (i.e. a current density of 15.6 µA cm^-2). Whereas the microbattery discharged at a rate of 0.2 mA possessed an energy density of 2.65 Wh l^-1 and power levels of 0.023–0.040 mW cm^-2 (i.e. a current density of 31.2 µA cm^-2). Nevertheless, the present microbattery performance was not optimized since it was noted that cuprous oxide and cupric oxide layers were really forming during the charge-discharge process, i.e. based on the XRD results.

iii

ثحبلا صخلم

يوضعلا يرغ ءاشغلا نأ نم مغرلا ىلع MCM-41

ةيلولأا يالالخا في لصاف ةباثبم لمعي نأ نكيم

كنزلا لثم -

كنزلا و ءاولها -

نيثا ةيللخا في هتيلاعف نأ لاإ ،زينجنلما ديسكأ ةلباق

لثم نحشلا ةداعلإ

لكينلا - كنزلا ( Ni-Zn ادبأ اهديدتح متي لم )

. جمد ةيلمع ةيلاعف مدع زيزعت متي MCM-41

في

يراطب ماظن ة

Ni-Zn ت اكيليسلا نبأ

مويستاوبلا ديسكورديه ةطساوب لكآت (

KOH )

بناج لىإ ؛

لوحتي ،كلذ MCM-41

لىإ MCM-50 في

زّكرلما KOH .

تم ،ةيضرفلا نم ققحتللو

يوضعلا يرغ ءاشغلا مادختسا MCM-41

يالاخ في لصافك Ni-Zn

فيو ةيرغص تياراطب .

نمو

نوزخمك ا يسادس ةبترلما ةماسلما تاونقلا لمعت نأ عقوتلما لوتركلإ

تيي تلاعافتلل ةينويأ راشتنا تاراسمكو

ةيئايميكورهكلا .

تيلا ةيربكلا ةيحطسلا ةحاسلماو ءاملل ةبلمحا ةيماسلما انهاردج ةعيبط لىإ كلذ عجريو

اهكلتتم . تاقبطلا ددعتم قيقر مليف عينصت تم MCM-41

قيرط نع لكينلا ديسكورديه بطق ىلع

لأا لولحملل يرطقتلا ءلاط يساس

نوكتت تيس نم ديمورب موينومأ ليثيم يثلاث لي (CTAB)

ضحمو

كيرولكورديلها (

HCl ) رطقلما ءالماو (

2

O H ) لوناثيلإاو (

5

OH

2

H C ) تاكيليسوثروأ ليثيإ عبارو

(TEOS) عم

ةبيكرت نم ةيلولما ةبسنلا 0.05

لوم CTAB ،

1.0 لوم TEOS ،

0.5

لوم HCl ، 25 لوم

5

OH

2

H C و 75 لوم

2

O H . و كنزلا ديسكأ نم ةقيقر ملافأ بيسرت تم

تمو ،لياوتلا ىلع ،دوثاكلاو دونلأا ليكشتل يساحنلا رايتلا تاعممج ىلع ايئبارهك لكينلا ديسكورديه ءلاط ءبارهكلبا بسترلما كنزلا ىلع طوقسلبا ينط

لماك دونأ لكش امم ،كنزلا ديسكأ .

نم دكأتلا تم

ةدالم يلكيلها نيوكتلا MCM-41

ةعشلأا دويح تاسايق ةطساوب لكينلا ديسكورديهو كنزلاو

ةينيسلا ( XRD ةيوننا قئاقر نم ا ساسأ لكينلا ديسكورديهو كنزلل يحطسلا لكشتلا فلأتي .)

لياوتلا ىلع ،ةّيمره ةقيرطب ةعمجتم ةيوننا تاميسجو .

ةملاسلا ةسارد ترهظأ لصافل ةيلكيلها

MCM-41 يالاخ في

Ni-Zn نأ

MCM-41 ت دق

روط لىإ ايئزج لوح ت MCM-50

في

ةيلمع نم ةركبلما ةلحرلما نحشلا

- غيرفتلا ةسمالخا ةرودلا في ابيرقت لماك لكشب ،ةسمالخا ةرودلا يأ ،

،نيرشعلاو ايلك و

يننامثلا ةرودلا في .

ةيحلاص دكأتلا تم MCM-41

ةيولقلا ةيوناثلا يالاخلل لصافك

صئاصلخا للاخ نم ةيبيكترلا

داوملل لصافلا ة و ةتجانلا غيرفتلا ةعس فصو للاخ نم

. ةيلباق حيضوت تم

تاطيمح في كنزلا باطقأ ساكعنا KOH-MCM-41

تاسايق في ةفلتخلما يترماتلوف

يرود

نأ جاتنتسا لىإ تّدأ تيلاو 70:30

( KOH لىإ

MCM-41 )

اهنع جتني نأ بيج نزولا ةبسن نم

ةينباوذ في جتانلا كنزلل لقأ باطقتسلاا لولمح

( للإا تيلوترك .)

ةيراطب عينصت تم Ni-Zn

ةيرغص

iv

يرئاد لكش ىلع نحشلا ةداعلإ ةلباقو قيقرو

بنج لىإ ا بنج يئبارهك بطق ميمصت مادختسبا ،ةياغلل

لا لصف ةفاسم عم لا بطق

يئبارهك 800

ترموركيم .

نم رثكأ ةيرغصلا تياراطبلا ةمادتسا 130

ةرود

لاع غيرفت قمع عم ريودتلا نم .

تناك كمسب ةيرغصلا تياراطبلا 200

اهتحاسم تغلبو ،ترموركيم

6.41 مس تنزوو

1.14 مارج ( ةيلفسلا ةقبطلاو ءاطغلا ءانثتسبا .)

ت غرف لدعبم ةيرغصلا تياراطبلا 0.1

غلبت ةقاطلا ةفاثك كلتتمو يربمأ يلم 3.82

طاو ةعاس ترل

1

نم ةردقلا تياوتسمو

0.014 - 0.023

طاو يلم

2

مس (

تلا ةفاثك يأ راي

يربْمَأوركيم 15.6

2

مس .)

لدعبم غرفت ةيرغصلا تياراطبلا نأ ينح في

0.2 نم ةقاطلا ةفاثك كلتتمو يربمأ يلم 2.65

طاو ةعاس

1

ترل نم ةردقلا تياوتسمو ،

0.023 -

0.040 طاو يلم

مس

2

(

رايتلا ةفاثك يأ يربْمَأوركيم 31.2

مس

2

).

ينستح ةظحلام متي لم ،كلذ عم

نياثلا ساحنلا ديسكأ و يداحلأا ساحنلا ديسكأ تاقبط نأ ببسب ةيلالحا ةيرغصلا ةيراطبلا ءادأ ةيلمع ءانثأ تنوكت نحشلا

- تاسايق جئاتن ىلع ادامتعاو ،غيرفتلا ةينيسلا ةعشلأا دويح

.

v

APPROVAL PAGE

The thesis of Shahrul Razi Meskon has been approved by the following:

________________________

Raihan Othman Supervisor

________________________

Mohd. Hanafi Ani Co-Supervisor

________________________

Iis Sopyan Internal Examiner

_________________________

Nor Sabirin Mohamed External Examiner

_________________________

Ahmad Azmin Mohamed External Examiner

_________________________

Fouad Mahmoud Rawash Chairman

vi

DECLARATION

I hereby declare that this thesis is the result of my own investigations, except where otherwise stated. I also declare that it has not been previously or concurrently submitted as a whole for any other degrees at IIUM or other institutions.

Shahrul Razi Meskon

Signature………. Date………....

vii

INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA

DECLARATION OF COPYRIGHT AND AFFIRMATION OF FAIR USE OF UNPUBLISHED RESEARCH

RECHARGEABLE Ni-Zn MICROBATTERIES EMPLOYING MCM-41 SEPARATOR

I declare that the copyright holder of this thesis/dissertation are jointly owned by the student and IIUM.

Copyright © 2018 by International Islamic University Malaysia. All rights reserved.

No part of this unpublished research may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without prior written permission of the copyright holder except as provided below:

1. Any material contained in or derived from this unpublished research may only be used by others in their writing with due

acknowledgement.

2. IIUM or its library will have the right to make and transmit copies (print or electronic) for institutional and academic purposes.

3. The IIUM library will have the right to make, store in a retrieval system and supply copies of this unpublished research if requested by other universities and research libraries.

By signing this form, I acknowledged that I have read and understand the IIUM Intellectual Property Right and Commercialization policy.

Affirmed by Shahrul Razi Meskon

………. ………..

Signature Date

viii

ACKNOWLEDGEMENTS

In the Name of Allah, the Most Compassionate, the Most Merciful.

May the blessings and peace of Allah be upon our prophet Muhammad ibn Abdullah (peace be upon him), his families, his companions and

all of his righteous followers.

All glory is due to Allah, the Almighty, whose Grace and Mercies have been with me throughout the course of my programme. Although it has been challenging, His Mercies and Blessings on me ease the enormous task of completing this thesis.

This work has been done at the Energy Research Laboratory, Kulliyyah of Engineering, International Islamic University Malaysia, under the supervision of Assoc. Prof. Dr. Raihan Othman.

I would like to extend my sincere appreciation and thanks to my supervisor, Assoc. Prof. Dr. Raihan Othman for his kind advice, continuous support, valuable suggestions and encouragement throughout the course of this work as well as critical comments on this thesis. Despite his commitments, he took time to listen and attended to me whenever requested. The moral support he extended to me is in no doubt; a boost that helped in building and writing the draft of this research work. I am also grateful to my co-supervisor, Assoc. Prof. Dr. Mohd. Hanafi Ani for his kind advice, fruitful discussion and continuous support.

I would like to express my appreciation to all staff and technicians of various laboratories of the Kulliyyah of Engineering, particularly Br. Rahimie (Surface Engineering Laboratory), Br. Sanadi (Characterization Lab) and Br. Ibrahim (Metallography Laboratory) for assisting me in using the equipment. I would also like to express my gratitude to my PhD colleagues, i.e. Br. Abdul Aziz, Bro.

Mukhtaruddin and Br. Edhuan for their friendly cooperation and inspirations.

I am deeply grateful to the Ministry of Science, Technology and Innovation (MOSTI) Malaysia, for the funding of this project through an e-science research grant.

Finally, my sincere and abundant thanks go to my wife, Nurul Huda Abdullah, my son, Muhammad Iman Mukhlis and my daughters, Iman Nur Nasuha and Iman Nur Fathiyyah, also my parents, brothers and sisters for their prayers, tremendous patience, and relentless encouragement and support.

Last but not least, as it may not be possible to list all the names, who have contributed either directly or indirectly towards the completion of this work, please accept my apologies. I wish to convey my true appreciation for all the helps.

June 8, 2017 13 Ramadhan 1438 H Shahrul Razi Meskon

ix

TABLE OF CONTENTS

Abstract ……….……….………. ii

Abstract in Arabic ………... iii

Approval Page ……….……… v

Declaration ……….………. vi

Copyright ……….……….... vii

Acknowledgements ………. viii

List of Tables ………... xii

List of Figures ….……… xiii

List of Abbreviations ………... xviii

List of Symbols ………... xx

List of Publications ………. xxi

CHAPTER ONE: INTRODUCTION ………. 1

1.1 Overview ………. 1

1.2 Problem Statement and Its Significance ………. 3

1.3 Research Philosophy ………... 3

1.4 Research Objectives ……….………... 4

1.5 Research Methodology ………... 5

1.6 Scope of Research ………... 6

1.7 Thesis Organization ……… 7

CHAPTER TWO: Ni-Zn SECONDARY BATTERIES AND RECENT DEVELOPMENT OF MICROBATTERIES: A REVIEW …….….….….. 9

2.1 Introduction ………. 9

2.2 Ni-Zn Battery Chemistry ……… 11

2.3 Cell Components ………. 12

2.3.1 Zinc Anode ………... 13

2.3.2 Nickel Hydroxide Cathode ………... 16

2.3.2.1 Nickel Hydroxide Materials ………... 17

2.3.3 Electrolyte ………. 23

2.3.4 Separator ………... 24

2.3.4.1 MCM-41 Material and Its Derivatives ………... 25

2.4 Cell Drawbacks and Solutions ………. 34

2.5 Electrical Performance of Ni-Zn Batteries ……….. 36

2.6 Recent Development and Applications of Ni-Zn Batteries …………. 37

2.6.1 Ni-Zn Batteries for Hybrid Electric Vehicles ………... 38

2.6.2 Ni-Zn Batteries for Consumer Devices ……… 42

2.6.3 Ni-Zn Microbatteries for Microsystem Applications ………... 42

2.7 Recent Development of Microbatteries ……….. 47

2.8 Summary ………. 53

x

CHAPTER THREE: STABILITY STUDY OF MCM-41 SILICA IN THE

RECHARGEABLE Ni-Zn CELL CONDITION ………... 54

3.1 Introduction ………. 54

3.2 Experimental Procedures ………. 55

3.2.1 Synthesis of MCM-41 Thin Films and Powder ……… 56

3.2.2 Preparation of Nickel Hydroxide Cathode ……… 57

3.2.3 Preparation of Zinc Anode ……… 57

3.2.4 Fabrication Ni-Zn Cell ……….. 58

3.2.5 Physical Characterizations ……… 59

3.2.6 Electrochemical Characterization ………. 60

3.3 Results and Analysis ………... 62

3.3.1 XRD of the Starting Materials ……….. 62

3.3.2 Surface Morphology of the Starting Materials ………. 66

3.3.3 Electrochemical Study of Ni-Zn Cells ………. 71

3.3.4 Structural Integrity Study of MCM-41 Membrane ………….. 74

3.3.5 Crystal Structure Variation of Resulting Separator Material ... 77

3.3.6 Surface Morphology of Resulting Separator Material ………. 80

3.4 Summary ………. 83

CHAPTER FOUR: CYCLIC VOLTAMMETRY STUDY OF ZINC ELECTRODE IN MCM-41-ADDED KOH ELECTROLYTES …………. 84

4.1 Introduction ………. 84

4.2 Experimental Procedures ……… 86

4.3 Results and Analysis ………... 87

4.4 Summary ………. 98

CHAPTER FIVE: ELECTROCHEMICAL STUDY OF THE Ni-Zn MICROBATTERIES ……… 100

5.1 Introduction ………. 100

5.2 Experimental Procedures ………. 101

5.2.1 Fabrication of Printed Circuit Board ……… 102

5.2.2 Preparation of Anode and Cathode ………... 104

5.2.2.1 Designs of Electrodeposition Substrate ………. 104

5.2.2.2 Design of Electrodeposition Cell ………... 104

5.2.2.3 Preparation of Zinc Anode ………. 106

5.2.2.3 Preparation of Nickel Hydroxide Cathode ………. 106

5.2.3 Assembly of Components of Microbattery ……….. 107

5.2.4 Electrochemical Performance Testing of Microbatteries ……. 109

5.2.5 XRD Analysis of Cathode Materials of the Tested Cells ……. 109

5.3 Results and Analysis ……… 110

5.3.1 XRD of Zinc Electrodeposit ………. 110

5.3.2 Surface Morphology of Zinc and Nickel Hydroxide Thin Films ……….. 111

5.3.3 Appearances of Microbatteries During Testing ……… 116

5.3.4 Electrochemical Characteristics of the Microbatteries ……... 118

5.3.4.1 MBD1 Microbattery ………... 118

5.3.4.2 Microbatteries with Different KOH:MCM-41 Ratios … 123 5.3.4.3 MBD2-0.1 Microbattery ………. 127

5.3.4.4 MBD2-0.2 Microbattery ………. 143

xi

5.3.4.5 MBD2-0.3 Microbattery ………. 150

5.3.5 Phase Identifying of Materials of the Tested Cells …………... 156

5.4 Summary ……….. 163

CHAPTER SIX: DISCUSSION ………... 165

CHAPTER SEVEN: CONCLUSION AND RECOMMENDATION …….. 174

7.1 Conclusion ………... 174

7.2 Major Contributions ……… 175

7.3 Recommendations for Future Work ……… 176

REFERENCES ……….. 177

xii

LIST OF TABLES

Table 2.1 Various zinc electrode compositions, CV experimental conditions

and the corresponding results 15

Table 2.2 Power requirement for remote sensing system (Humble et al., 2001) 43 Table 3.1 Conditions for the galvanostatic charge-discharge cycling test

configurations 61

Table 4.1 Cyclic voltammetry characteristics of zinc electrode with different weight percent of MCM-41 silica addition in the electrolyte 97 Table 5.1 Energy and power values of the MBD1 microbattery as a function of

cycle number 119

Table 5.2 Energy and power values of MBD2-0.1 microbattery for the

emphasized cycles (8th-to-62nd-cycle timeframe) 129 Table 5.3 Energy and power values of the MBD2-0.1 microbattery for the

“bulged” cycles 133

Table 5.4 Energy and power values of the MBD2-0.1 microbattery for the

emphasized cycles (106th-to-132nd-cycle timeframe) 134 Table 5.5 Energy and power values of the MBD2-0.2 microbattery for the

emphasized cycles (3rd-to-43rd-cycle timeframe) 145 Table 5.6 Energy and power values of the MBD2-0.2 microbattery for the

emphasized cycles (99th-to-130th-cycle timeframe) 148 Table 5.7 Energy and power values of the MBD2-0.3 microbattery for the

selected cycles (2nd-to-11th-cycle timeframe) 152 Table 6.1 Performance characteristics of the present microbatteries and the

published microbatteries 170

xiii

LIST OF FIGURES

Figure 1.1 Flowchart of the research methodology. 6 Figure 2.1 A general scheme of the chemical and electrochemical processes that

occur at a nickel hydroxide battery electrode (Hall et al., 2015). 18 Figure 2.2 Schematic illustrations of the different structures of the M41S

mesoporous materials: (a) MCM-41, (b) MCM-48 and (c) MCM-50 (Bhattacharyya, Lelong and Saboungi, 2006). 26 Figure 2.3 XRD pattern of MCM-50, as obtained by Monnier et al. (1993) 27 Figure 2.4 XRD pattern of MCM-50, as obtained by Fajula (2007) 28 Figure 2.5 XRD pattern of thermally unstable lamellar MCM-50, as prepared by

Beck et al. (1992) 28

Figure 2.6 XRD patterns of (a) C16TMA-intercalated Na-RUB-18 mesophase, as obtained by Alam and Mokaya (2008) and (b) C16TMA-

exchanged Na-magadiite layered silicate, as obtained by Mochizuki

and Kuroda (2006) 30

Figure 2.7 Possible mechanistic pathways for the formation of MCM-41: (a) liquid-crystal phase and (b) silicate-anion (Hoffmann, Cornelius,

Morell and Fröba, 2006) 31

Figure 2.8 Side-by-side-electrode design of the microbattery developed by

Humble et al. (2001) 44

Figure 2.9 Interdigitated electrode post array design of the microbattery

developed by Chamran et al. (2007) 44

Figure 2.10 Schematic diagram of a cardiac pacemaker (depicting its components) in the heart (Cleveland Clinic, 2018, as cited in

Zielinski, 2017) 47

Figure 3.1 Schematic diagram of the Ni-Zn cell construction layout 59 Figure 3.2 XRD pattern of the as-prepared MCM-41 silica powder 63 Figure 3.3 XRD pattern of the MCM-41 silica thin film, coated on the as-

prepared α-Ni(OH)2 thin film 64

Figure 3.4 XRD pattern of the as-prepared Ni(OH)2 thin film (on a Cu substrate) 64

xiv

Figure 3.5 XRD patterns of the Ni(OH)2 samples prepared using the same

procedure and characterized using diffractometers of different brands 66 Figure 3.6 FE-SEM images of (a), (b), (c) the as-prepared MCM-41 powder at

different magnifications 68

Figure 3.7 FE-SEM images of the as-prepared α-Ni(OH)2 thin film at different

magnifications 69

Figure 3.8 FE-SEM images of (a) one-layer MCM-41-coated Ni(OH)2

microspheres; (b) six-layer MCM-41-coated Ni(OH)2 microspheres;

photographic images of the (c) as-prepared; and (d) MCM-41-coated Ni(OH)2 thin films. The arrows show the areas of the delaminated

layers 70

Figure 3.9 Cross-sectional FE-SEM image of a Ni(OH)2 thin film 71 Figure 3.10 Discharge capacity curves of the various cell configurations of

charge-discharge cycling test 72

Figure 3.11 XRD patterns of the MCM-41 membranes for the 5th, 25th and 80th

cycles 75

Figure 3.12 XRD patterns of the resulting separator materials based on their

cycle number of charge-discharge process and substrate material 79 Figure 3.13 Photographic images of (a) the gel-like MCM-50 coated on Ni(OH)2

thin film and ZnO powder after going through a charge-discharge test, (b) a wet MCM-50 membrane coated on a substrate of PCB, (c)

a vacuum oven-dried MCM-50 82

Figure 3.14 FE-SEM images of the MCM-41 membranes which had gone through 5 (a), 25 (b) and 80 (c) cycles of charge-discharge cycling

test 82

Figure 4.1 Photographic image of the cyclic voltammetry experimental setup 87 Figure 4.2 Cyclic voltammogram of the Zn electrode in a 6 M aqueous KOH

electrolyte at a scan rate of 20 mV s^-1 employing PE microporous

membrane as the separator 89

Figure 4.3 Cyclic voltammograms of the Zn electrodes in a 6 M KOH electrolyte at a scan rate of 20 mV s^-1 with different separator

materials, i.e. 20 wt. % MCM-41 silica and PE sheet 91 Figure 4.4 Discharge curve of a Ni-Zn microbattery on the 4th cycle of charge-

discharge process 92

xv

Figure 4.5 Cyclic voltammogram of the Zn electrode in a 6 M aqueous KOH at a scan rate of 20 mV s^-1, with an addition of 20 wt. % MCM-41 silica 94 Figure 4.6 Cyclic voltammogram of the Zn electrode in a 6 M aqueous KOH at

a scan rate of 20 mV s^-1, with an addition of 25 wt. % MCM-41 silica 95 Figure 4.7 Cyclic voltammogram of the Zn electrode in a 6 M aqueous KOH at

a scan rate of 20 mV s^-1, with an addition of 30 wt. % MCM-41 silica 95 Figure 4.8 MCM-41-silica-added 6 M aqueous KOH, i.e. at (a) 80:20, (b) 75:25

and (c) 70:30 weight ratios of KOH-MCM-41 composition after 24

hours 98

Figure 5.1 Box diagram of the process flow of the fabrication and

characterizations of the Ni-Zn microbatteries 103 Figure 5.2 Schematic diagram of photolithography process of PCB fabrication 103 Figure 5.3 (a) Schematic diagram of the microbattery substrate design, i.e.

MBD1 105

Figure 5.3 (b) Schematic diagram of the microbattery substrate design, i.e.

MBD2 105

Figure 5.4 (a)Schematic diagram of the casing of the microbattery, i.e. for

MBD1 108

Figure 5.4 (b) Schematic diagram of the casing of the microbattery, i.e. for

MBD1 108

Figure 5.5 XRD pattern of the as-prepared Zn electrodeposit (on a Cu substrate) 110 Figure 5.6 (a), (b) FE-SEM images of a Zn electrodeposit and cross-sectional

FE-SEM images of (c) a Zn electrodeposit and (d) a Ni(OH)2 thin

film 113

Figure 5.7 (a), (b) FE-SEM images of the Ni(OH)2 thin film of the MBD2

microbattery at different scanning areas 114 Figure 5.8 Photographic images of the (a) Zn electrodeposit and Ni(OH)2 thin

film (on Cu substrates) of the MBD1 microbattery; the as-prepared (b) Zn electrodeposit and (c) Ni(OH)2 thin film of the MBD2

microbattery; (d) the Zn foil oxidized surface; and the MCM-41 thin film coatings on the anode and cathode of the (e) MBD1 and (f)

MBD2 microbatteries 115

Figure 5.9 Photographic image of the MBD1 Ni-Zn microbattery at the 7th

cycle of charge-discharge process 117

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Figure 5.10 Photographic images of the MBD2 Ni-Zn microbattery at the (a) 5th, (b) 25th, (c) 50th and (d) 80th cycles of charge-discharge process 117 Figure 5.11 Discharge curves of the MBD1 microbattery for different cycle

numbers as a function of discharge duration 121 Figure 5.12 Charge curves of the MBD1 microbattery for different cycle numbers

as a function of charge duration 122

Figure 5.13 Discharge capacity and efficiency profiles of the MBD1 microbattery

as a function of cycle number 123

Figure 5.14 Discharge curves of the Ni-Zn microbatteries for the 17th cycle of charge-discharge process employing different KOH-MCM-41 compositions, discharged at 0.1 mA

125 Figure 5.15 Discharge curves of the Ni-Zn microbatteries for the 48th cycle of

charge-discharge process employing different KOH-MCM-41

compositions, discharged at 0.1 mA 126

Figure 5.16 Discharge capacity and efficiency profiles of the MBD2-0.1

microbattery as a function of cycle number 130 Figure 5.17 Discharge curves of the MBD2-0.1 microbattery for the selected

cycle numbers 131

Figure 5.18 Discharge curves of the MBD2-0.1 microbattery for the selected

cycle numbers (continuation) 135

Figure 5.19 Discharge curves of the MBD2-0.1 microbattery for the selected

cycles corresponding to the stabilizing phase 137 Figure 5.20 Discharge curves of the MBD2-0.1 microbattery for the selected

cycles corresponding to the mature phase 138 Figure 5.21 Charge curves of the MBD2-0.1 microbattery for the selected cycle

numbers 141

Figure 5.22 Charge curves of the MBD2-0.1 microbattery for the selected cycle

numbers (continuation) 142

Figure 5.23 Discharge capacity and efficiency profiles of the MBD2-0.2

microbattery as a function of cycle number 146 Figure 5.24 Discharge curves of the MBD2-0.2 microbattery, for the selected

cycles 147

Figure 5.25 Discharge curves of the MBD2-0.2 microbattery, for the selected

cycles (continuation) 149

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Figure 5.26 Charge curves of the MBD2-0.2 microbattery for the selected cycles 151 Figure 5.27 Discharge curves of the MBD2-0.3 microbattery for all cycles of the

charge-discharge cycling 154

Figure 5.28 Charge curves of the MBD2-0.3 microbattery for all cycles of the

charge-discharge cycling 155

Figure 5.29 (a) XRD pattern of the cathode of the charged Ni-Zn microbattery

(for the 6th cycle) for the specific 2θ range 158 Figure 5.29 (b) XRD patterns of the cathode of the charged Ni-Zn microbattery

(for the 6th cycle) with the specific 2θ range (continuation) 159 Figure 5.30 XRD patterns of the cathode of the charged Ni-Zn microbattery for

the 6th, 25th and 80th cycles of charge-discharge cycling 160 Figure 5.31 Overlay of the XRD patterns of the cathode of the discharged Ni-Zn

microbattery for the 5th (a), 25th (b) and 80th (c) cycles of charge-

discharge cycling 162

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LIST OF ABBREVIATIONS

a.u. arbitrary unit

BET Brunauer–Emmett–Teller

CMOS complementary metal-oxide semiconductor

CTAB cethyltrimethylammonium bromide C16TMA hexadecyltrimethylammonium DOD depth of discharge

DRIE deep reactive-ion etching DVD digital video disk

EV electric vehicle

FR-4 fibreglass-epoxy laminate (flame retardant) FWHM full width at half maximum

HEV hybrid electric vehicle

IAD Institute of Automotive Technologies Dresden ICE internal combustion engine

iR lost volts due to internal resistance

JCPDS Joint Committee on Powder Diffraction Standards

l litre

M molar

mAh milliamp-hour

MCM Mobil Composition of Matter MEMS microelectromechanical system

MH metal hydride

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MP megapixel

n.d. no date

OEM original equipment manufacturer OER oxygen evolution reaction ORNL Oak Ridge National Laboratory PCB printed circuit board

PE polyethylene

pH a measure of hydrogen ion (H⁺) concentration; a measure of the acidity or alkalinity of a solution. The pH is equal to -log10 c, where c is the hydrogen ion concentration in moles per litre

PHEV plug-in hybrid electric vehicle

PPYDBS dodecylbenzenesulfonate-doped polypyrrole PVP polyvinyl pyridine

RF radio frequency

RGO reduced graphene oxide rpm rotation per minute SOC state of charge SS stainless steel

TEOS tetraethyl orthosilicate

USABC United State Advanced Battery Consortium

UV ultraviolet

vol. volume

W watt

Wh watt-hour

wt. weight

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LIST OF SYMBOLS

Å Angstrom (equivalent to 1.0 x 10^-10 m) a0 Repeat distance between two pore centres

C Rate at which a battery is discharged relative to its maximum capacity

°C Degree Celsius d Interplanar spacing E” Standard cell potential

EpA, EpC Anodic and cathodic peak potentials, respectively ΔEp Peak potential separation

e^- Electron

hkl A set of numbers which quantify the intercepts and thus may be used to determine the plane

I Intensity

IpA, IpC Anodic and cathodic peak currents, respectively j Current density

n Integer

O Oxidized species R Reduction product

S Siemens

Z Chemical reaction product

λ Wavelength

θ Theta; an angle of incidence that the incident X-ray beam makes with the plane of atoms (hkl)

° Degree

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LIST OF PUBLICATIONS

Meskon, S. R., Othman, R. & Ani, M. H. (2018). The viability of MCM-41 as separator in secondary alkaline cells. IOP Conf. Ser.: Mater. Sci. Eng., 290, 012045 doi:10.1088/1757-899X/290/1/012045.

Meskon, S. R., Othman, R. & Ani, M. H. (2018). A secondary, coplanar design Ni/MCM-41/Zn microbattery. IOP Conf. Ser.: Mater. Sci. Eng., 290, 012073 doi:10.1088/1757-899X/290/1/012073.

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CHAPTER ONE INTRODUCTION

1.1 OVERVIEW

Over the decades, the growth of portable electronic devices has been dramatic (Pillot, 2014). It is strongly driven by the advancements in electrochemical energy storage technology. The early generations of secondary batteries are big and bulky, e.g. lead- acid batteries which are primarily intended for automobile starting, lighting and ignition applications (PC Control, 2008). The flooded version of lead-acid batteries needs regular maintenance due to a high rate of water lost during charging and relatively hard to be installed in various positions due to a concern of sulfuric acid leakage (Evolving Energy, n.d.). Even the valve-regulated version still has some disadvantages, i.e. controlled charging regime requirement, additional charge time and overcharge at elevated temperature and significant variations in top-of-charge voltages of individual cells (Newnham, 1994). While generally, the disadvantages of lead-acid battery include: contains corrosive electrolyte (can cause burns to people and corrosion on metals) and lead is environmentally unfriendly (Poole, 2017); during charge, some of the electrolyte may evaporate and the battery releases a flammable gas i.e. hydrogen (Sandoval, n.d.); and cannot be left in discharged state as this would cause sulfation of the lead sulphate (Roberge, 2017).

The early (1920s to 1930s) radios used as many as three batteries of different voltage and current specifications to operate. Thus, they could consist of different types of batteries, i.e. a rechargeable lead-acid battery and the dry cells (zinc-carbon battery packs) (Nelson, 2017; Clutter, 2016). The modern alkaline dry battery was

2

made available on the market in the 1950s with various sizes of cylindrical shape. In the early days, the miniature batteries such as used in hearing aids were mostly zinc/silver oxide batteries. The zinc-air battery with a cheaper electrode material and comparable performance came later on the market. Nowadays, small and light batteries power high performance portable appliances such as mobile phones, notebook computers, camcorders, tablets and DVD players.

Today, thin batteries mostly are lithium-based due to their much higher energy density and lower self-discharge rate (Reisch, 2017). However, lithium-ion battery does not tolerate overcharge and overdischarge as well as deep discharge which may cause detrimental temperature rise. As a consequence, the cell may explode due to the electrolyte decomposition which releases gasses thus increasing the internal pressure (Bonheur, 2016). Apart of a higher manufacturing cost due to the required on-board computer circuitry to maintain the voltage within the safe limits, a large quantity shipment of the batteries will be subjected to transportation restrictions (Bonheur, 2016; Buchmann, 2017a).

According to Ratner, Hoffman, Schoen and Lemons (as cited in Bocan and Sejdić, 2016), over one million patients in the U.S. have cardiac pacemakers; 250,000 new pacemakers are implanted each year; 100,000 implantable cardioverter defibrillators are implanted each year; and 120,000 patients in the U.S. have cochlear implants. The associated cost for implantable medical devices (IMDs) have reached

$300 billion in 2000 (Bocan and Sejdić, 2016). The IMDs include continuous therapy devices such as the implantable cardioverter/defibrillator, electronic pacemaker, implantable neurostimulators, wireless implantable biosensors and fully-implantable drug delivery pumps (St. Jude Medical, 2013; Medtronic, 2015; Cyberonics, 2015;

and Medtronic, 2014, as cited in Bocan and Sejdić, 2016).

3

Rechargeable nickel-zinc (Ni-Zn) battery has the potential to be incorporated in a microdevice to power microelectronic system such as medical microchip. This is viable due to the fact that it has a high power density, contains non-toxic materials, is inexpensive to manufacture, is lighter than lithium-ion battery, is capable for a fast recharge and has a safe chemistry that is abuse-tolerant (ZincFive, 2017).

1.2 PROBLEM STATEMENT AND ITS SIGNIFICANCE

The structural stability of MCM-41 silica in a highly alkaline electrolyte is often doubted since potassium hydroxide (KOH) does etch silica away. Although the efficacy of MCM-41 (as separator) in non-rechargeable batteries was satisfactory, its efficacy in a rechargeable battery (e.g. Ni-Zn battery) is yet to be determined. The transformation of MCM-41 to gel-like MCM-50 (in a concentrated KOH) could possibly improve battery discharge capacity. However, electrochemical performance in the case of a rechargeable battery and structural integrity of the gel phase in the operating conditions of the battery, have never been known. As battery performance differs with size and design, the efficacy of MCM-41 membrane separator in both the Ni-Zn cell and microbattery needs to be determined. The Ni-Zn microbattery is especially needed as a power source for implantable medical devices since the battery materials are not harmful inside the human body.

1.3 RESEARCH PHILOSHOPHY

In order to develop an ultrathin, high power density Ni-Zn microbattery, a substitution of polymer-based separator with an inorganic membrane is opted since polymeric materials have poor wettability, cannot be cast into a membrane at a low temperature near to room temperature (Yen and Patel, 2014). MCM-41 is a prospective substitute