Design of high voltage AC/AC electrochemical capacitors in aqueous electrolytes

177 Pages·2015·7.37 MB·English

by  Ratajczak, Paulina

Poznan University of Technology
Faculty of Chemical Technology
Institute of Chemistry and Technical Electrochemistry
Field of study: Chemical Technology

Paula Ratajczak

DESIGN OF HIGH VOLTAGE
AC/AC ELECTROCHEMICAL CAPACITORS
IN AQUEOUS ELECTROLYTE
Projektowanie wysokonapięciowych kondensatorów
elektrochemicznych,
pracujących w elektrolitach wodnych

DOCTORAL DISSERTATION

Promoter:
prof. François Béguin

Poznań 2015
Design of high voltage AC/AC electrochemical capacitors in aqueous electrolyte

Badania do niniejszej pracy prowadzone były przy wsparciu przez projekt ECOLCAP
realizowany w ramach Programu Welcome, finansowanego przez Fundację Nauki Polskiej
(FNP)zgodnie z Działaniem 1.2. „Wzmocnienie potencjału kadrowego nauki”, Programu
Operacyjnego Innowacyjna Gospodarka wspieranego przez Unię Europejską
Kierownik projektu: Profesor François Béguin

This thesis’ research was supported by ECOLCAP project funded in the frame of the
Welcome Programme implemented by the Foundation for Polish Science (FNP) within
the Measure 1.2. ‘Strengthening the human resources potential of science’, of the
Innovative Economy Operational Programme supported by European Union.

Project leader: Professor François Béguin

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Design of high voltage AC/AC electrochemical capacitors in aqueous electrolyte

Część praca badawczej została wsparta przez projekt LIDER finansowany przez
Narodowe Centrum Badań i Rozwoju LIDER/018/513/L-4/12/NCBR/201„Kondensator
elektrochemiczny o wysokiej gęstości energii i mocy operujący w roztworach
sprzężonych par redoks:
Kierownik projektu: dr inż. Krzysztof Fic

A port of the research work was supported by the LIDER project funded by the National
Centre for Research and Development (NCBiR) LIDER/018/513/L-4/12/NCBR/201
"Electrochemical capacitor with high energy density and power operating in coupled
redox couples solutions”.
Project leader: Dr Eng. Krzysztof Fic

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Design of high voltage AC/AC electrochemical capacitors in aqueous electrolyte

I am sincerely grateful to my supervisor,
Prof. François Béguin,
for his guidance and all the efforts he put in my PhD work

I am also greatly thankful to Dr hab Eng Krzysztof Jurewicz,
for our collaborative work
on carbon materials and supercapacitors

It is also a great pleasure to thank
Prof. Dr hab Elżbieta Frąckowiak,
and Dr Eng Krzysztof Fic
for helping me to develop the skills and knowledge
in electrochemistry and carbon materials

My sincere gratitude is also dedicated
to all the ECOLCAP group members, especially,
Dr Qamar Abbas,
M.Sc Eng Piotr Skowron
and M.Sc Eng. Paweł Jeżowski
for their experimental support

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Design of high voltage AC/AC electrochemical capacitors in aqueous electrolyte
TABLE OF CONTENTS
INTRODUCTION _____________________________________________________ 9
CHAPTER I
LITERATURE REVIEW ON ELECTROCHEMICAL CAPACITORS __________ 16
I.1. General properties of electrochemical capacitors______________________ 17
1.1. The electrical double-layer models ______________________________________________ 17
1.2. Operation principle of an EDLC _______________________________________________ 19
1.3. Energy and power of electrochemical capacitors ___________________________________ 21
1.4. Pseudo-capacitive contribution _________________________________________________ 23
I.2. Electrode materials for electrochemical capacitors ____________________ 25
2.1. Commonly used carbon materials_______________________________________________ 25
2.2. Redox-active electrode materials _______________________________________________ 31
I.3. Structural and textural properties of activated carbons__________________ 31
3.1. Manufacturing of porous carbons _______________________________________________ 31
3.2. Surface functional groups on carbons ____________________________________________ 33
3.3. Effect of porous texture of activated carbons on the capacitive performance______________35
I.4. Electrolytes for electrochemical capacitors___________________________ 39
4.1. Aqueous electrolytes_________________________________________________________ 40
4.2. Organic electrolytes _________________________________________________________ 48
4.3. Ionic liquids _______________________________________________________________ 49
I.5. Conclusion ___________________________________________________ 51
CHAPTER II
ELECTROCHEMICAL TECHNIQUES
FOR ELECTROCHEMICAL CAPACITORS INVESTIGATION _______________ 53
II.1. Cyclic voltammetry ____________________________________________ 54
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Design of high voltage AC/AC electrochemical capacitors in aqueous electrolyte
II.2. Constant current charging/discharging ______________________________ 56
II.3. Impedance spectroscopy _________________________________________ 58
II.4. Accelerated ageing test __________________________________________ 60

CHAPTER III
STATE OF HEALTH OF AQUEOUS ELECTROCHEMICAL CAPACITORS
WITH STAINLESS STEEL CURRENT COLLECTORS
UNDER ACCELERATED AGEING _____________________________________ 63
III.1. High voltage ageing assessment of AC/AC electrochemical capacitors
in lithium sulfate electrolyte ______________________________________ 65
1.1. Exploring the high operating voltage of AC/AC electrochemical capacitors
in lithium sulfate electrolyte ___________________________________________________ 65
1.2. Degradation of ECs electrochemical performance under accelerated ageing ______________ 67
III.2. Factors contributing to ageing in aqueous electrolyte __________________ 74
2. 1. Oxidation of carbon electrodes and corrosion of stainless steel current collectors __________ 74
2.1.1. Post-floating analysis of ECs by electrochemical techniques __________________________ 74
2.1.2. Post-floating analyses on carbon electrodes _______________________________________ 78
2.1.3. Effect of temperature on ageing ________________________________________________ 82
2.2. Gas evolution during floating __________________________________________________ 83
III.3. Conclusion ___________________________________________________ 87

CHAPTER IV
STRATEGIES FOR IMPROVING THE LONG TIME PERFORMANCE
OF HIGH VOLTAGE CAPACITORS IN AQUEOUS ELECTROLYTES ________ 89
IV.1. Corrosion reduction of positive current collector ______________________ 90
1.1. Alternative nickel current collectors _____________________________________________ 91
1.2. Improvement of the current collector/electrode interface _____________________________ 95
1.2.1. Carbon electrodes glued to stainless steel current collectors __________________________ 95
1.2.2. Nickel foil substrate _________________________________________________________ 97
1.2.3. Carbon conductive sub-layer _________________________________________________ 100
1.3. Addition of corrosion inhibitor ________________________________________________ 103
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Design of high voltage AC/AC electrochemical capacitors in aqueous electrolyte
IV.2. Shifting of electrodes operating potentials __________________________ 109
2.1. Asymmetric configuration ___________________________________________________ 109
2.2. Current collectors coupling___________________________________________________ 117
IV.3. Conclusion __________________________________________________ 122

CHAPTER V
TOWARDS A NEW CONCEPT
OF HIGH VOLTAGE AC/AC CAPACITOR IN AQUEOUS ELECTROLYTES__ 124
III.1. The new concept of high voltage cell in aqueous electrolytes ___________ 125
III.2. Extension of voltage range by electrodes asymmetry _________________ 134
2.1 Adjustment of electrodes potential window by increasing m /m ______________________ 134
+ -
2.2. Voltage extension by use of different carbon electrodes ____________________________ 136
III.3. Conclusion __________________________________________________ 138

GENERAL CONCLUSION ____________________________________________ 138

EXPERIMENTAL ANNEX____________________________________________ 142
A.1. Cell construction _________________________________________________ 143
1.1. Materials and chemicals _____________________________________________________ 143
1.2. Preparation of electrodes ____________________________________________________ 145
1.3. Cells configurations ________________________________________________________ 146
A.2. Electrochemical characterization ____________________________________ 147
A.3. Physico-chemical and surface characterization _________________________ 147

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Design of high voltage AC/AC electrochemical capacitors in aqueous electrolyte
REFERENCES ______________________________________________________ 149
SCIENTIFIC ACHIEVEMENTS________________________________________ 165
ABSTRACT ________________________________________________________ 172
STRESZCZENIE ____________________________________________________ 175

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Design of high voltage AC/AC electrochemical capacitors in aqueous electrolyte

INTRODUCTION

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Design of high voltage AC/AC electrochemical capacitors in aqueous electrolyte
Energy management has a deep influence in the humans’ everyday life,
considering social, economic, ecological and political aspects. During the last 50 years,
the world energy consumption, mainly based on petroleum-based fuels (oil, coal and
natural gas), has considerably increased (Figure 1), due to industrial development of the
western countries after the 2nd World War, accompanied by improving wealth in
emerging markets and growth of the human population, especially in China and India.
Although renewable energy and nuclear power are the world fastest-growing energy
sources in the recent years (each increasing around by 2.5% per year), fossil fuels still
share more than 80% of the global energy consumption [1].

Figure 1 World energy consumption (based on [2]).
Over the past decade, a general awareness appeared that fossil fuel consumption
presents severe drawbacks, such as an important depletion of reserves and the emission
of noxious gases leading in particular to the greenhouse effect and to associated
temperature increase of the planet. The industry is partly able to handle with some of
these problems, by introducing modern solutions, such as reducing emissions by placing
catalysts in the exhaust systems of vehicles and in the chimneys of power plants.
Notwithstanding, if fossil fuels would remain the only power source for the future, the
forthcoming crunch of their availability would lead to economic dislocations and
serious political problems. Therefore, the incoming environmental and economic crisis
predictions have suggested to develop strategies for improving energy efficiency (e.g.,
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