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

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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 Paula Ratajczak Pa g e 2 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 Paula Ratajczak Pa g e 3 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 Paula Ratajczak Pa g e 4 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 Paula Ratajczak Pa g e 5 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 Paula Ratajczak Pa g e 6 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 Paula Ratajczak Pa g e 7 Design of high voltage AC/AC electrochemical capacitors in aqueous electrolyte REFERENCES ______________________________________________________ 149 SCIENTIFIC ACHIEVEMENTS________________________________________ 165 ABSTRACT ________________________________________________________ 172 STRESZCZENIE ____________________________________________________ 175 Paula Ratajczak Pa g e 8 Design of high voltage AC/AC electrochemical capacitors in aqueous electrolyte INTRODUCTION Paula Ratajczak Pa g e 9 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., Paula Ratajczak Pa g e 10

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Badania do niniejszej pracy prowadzone były przy wsparciu przez projekt ECOLCAP on carbon materials and supercapacitors for their experimental support The electrical double-layer models Accelerated ageing test the pore volume and surface area of the material by a controlled carbon.
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