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On the electrochemical performance of energy storage devices composed of cellulose and conducting polymers
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Applications that require electrical energy storage are becoming increasingly diverse. This development is caused by a number of factors, such as an increasing global energy demand, the advent of electric vehicles, the utilization of intermittent renewable energy sources, and advances in disposable and organic electronics. These applications will set different demands on their electrical energy storage and, thus, there will be no single technology used for all applications. For some applications the choice of energy storage materials will be extremely important. Conventional batteries and supercapacitors rely on the use of nonrenewable inorganic materials mined from depleting ores, hence, requiring large amounts of energy for their processing. Such materials also add a significant cost to the final product, making them less attractive for large scale applications. Conducting polymers, on the other hand, constitute a class of materials that can be used for organic matter based energy storage devices.

The aim of this thesis was to investigate the use of a composite consisting of the conducting polymer polypyrrole (PPy) and cellulose derived from Cladophora sp. algae for electrical energy storage. The polymer was coated onto the cellulose fibers by chemical polymerization resulting in a flexible material with high surface area. By using this composite as electrodes, electrochemical cells consisting of disposable and non-toxic materials can be assembled and used as energy storage devices. The resistances of these prototype cells were found to be dominated by the resistance of the current collectors and to scale with the thickness of the separator, and can hence be reduced by cell design. By addition of nanostructured PPy, the weight ratio of PPy in the composite could be increased, and the cell voltages could be enhanced by using a carbonized negative electrode. Composites of cellulose and poly(3,4-ethylenedioxythiophene) could also be synthesized and used as electrode materials. The porosities of the electrodes were controlled by mechanical compression of the composite or by coating of surface modified cellulose fibers with additional PPy. Finally, the self-discharge was studied extensively. It was found that oxygen was responsible for the oxidation of the negative electrode, while the rate of self-discharge of the positive electrode increases with increasing potential. Through measurements of the charge prior to and after self-discharge, as well as with an electrochemical quartz crystal microbalance, it was found that the self-discharge of the positive electrode was linked to an exchange of the counter ions by hydroxide ions. It is also demonstrated that the self-discharge rate of a symmetric PPy based device can be decreased dramatically by proper balancing of the electrode capacities and by reducing the oxygen concentration. The results of this work are expected to contribute towards future industrial implementation of electric energy storage devices based on organic materials.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. , 64 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1403
Keyword [en]
polypyrrole, supercapacitors, self-discharge
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
URN: urn:nbn:se:uu:diva-300917ISBN: 978-91-554-9651-7OAI: oai:DiVA.org:uu-300917DiVA: diva2:952878
Public defence
2016-09-30, Å80121, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2016-09-09 Created: 2016-08-16 Last updated: 2016-09-13
List of papers
1. The influence of electrode and separator thickness on the cell resistance of symmetric cellulose–polypyrrole-based electric energy storage devices
Open this publication in new window or tab >>The influence of electrode and separator thickness on the cell resistance of symmetric cellulose–polypyrrole-based electric energy storage devices
2014 (English)In: Journal of Power Sources, ISSN 0378-7753, Vol. 272, 468-475 p.Article in journal (Refereed) Published
Abstract [en]

The influence of the cell design of symmetric polypyrrole and cellulose-based electric energy storage devices on the cell resistance was investigated using chronopotentiometric and ac impedance measurements with different separator and electrode thicknesses. The cell resistance was found to be dominated by the electrolyte and current collector resistances while the contribution from the composite electrode material was negligible. Due to the electrolyte within the porous electrodes thin separators could be used in combination with thick composite electrodes without loss of performance. The paper separator contributed with a resistance of similar to 1.5 Omega mm(-1) in a 1.0 M NaNO3 electrolyte and the tortuosity value for the separator was about 2.5. The contribution from the graphite foil current collectors was about similar to 0.4-1.1 Omega and this contribution could not be reduced by using platinum foil current collectors due to larger contact resistances. The introduction of chopped carbon fibres into the electrode material or the application of pressure across the cells, however, decreased the charge transfer resistance significantly. As the present results demonstrate that cells with higher charge storage capacities but with the same cell resistance can be obtained by increasing the electrode thickness, the development of paper based energy storage devices is facilitated.

National Category
Nano Technology
Identifiers
urn:nbn:se:uu:diva-218812 (URN)10.1016/j.jpowsour.2014.08.041 (DOI)000344208700058 ()
Available from: 2014-02-18 Created: 2014-02-18 Last updated: 2016-09-02Bibliographically approved
2. Efficient high active mass paper-based energy-storage devices containing free-standing additive-less polypyrrole-nanocellulose electrodes
Open this publication in new window or tab >>Efficient high active mass paper-based energy-storage devices containing free-standing additive-less polypyrrole-nanocellulose electrodes
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2014 (English)In: J MATER CHEM A, ISSN 2050-7488, Vol. 2, no 21, 7711-7716 p.Article in journal (Refereed) Published
Abstract [en]

Free-standing and additive-free paper electrodes containing up to 90 wt% polypyrrole (PPy), and with PPy mass loadings up to 20 mg cm(-2), are made from PPy@nanocellulose and interconnecting PPy nanofibres for high-performance paper-based energy storage devices exhibiting close to theoretical energy densities and cell capacitances of about 1 F cm(-2) at a current density of 270 mA cm(-2).

National Category
Materials Engineering Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-227584 (URN)10.1039/c4ta01094a (DOI)000335924100012 ()
Available from: 2014-06-27 Created: 2014-06-27 Last updated: 2016-09-02
3. Asymmetric supercapacitors based on carbon nanofibre and polypyrrole/nanocellulose composite electrodes
Open this publication in new window or tab >>Asymmetric supercapacitors based on carbon nanofibre and polypyrrole/nanocellulose composite electrodes
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2015 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 21, 16405-16413 p.Article in journal (Refereed) Published
Abstract [en]

Asymmetric, all-organic supercapacitors (containing an aqueous electrolyte), exhibiting a capacitance of 25 F g-1 (or 2.3 F cm-2) at a current density of 20 mA cm-2 and a maximum cell voltage of 1.6 V, are presented. The devices contain a composite consisting of polypyrrole covered Cladophora cellulose fibres (PPy-cellulose) as the positive electrode while a carbon nanofibre material, obtained by heat treatment of the same PPy-cellulose composite under nitrogen gas flow, serves as the negative electrode. Scanning and transmission electron microscopy combined with X-ray photoelectron spectroscopy data show that the heat treatment gives rise to a porous carbon nanofibre material, topologically almost identical to the original PPy-cellulose composite. The specific gravimetric capacitances of the carbon and the PPy-cellulose electrodes were found to be 59 and 146 F g-1, respectively, while the asymmetric supercapacitors exhibited a gravimetric energy density of 33 J g-1. The latter value is about two times higher than the energy densities obtainable for a symmetric PPy-cellulose device as a result of the larger cell voltage range accessible. The capacitance obtained for the asymmetric devices at a current density of 156 mA cm-2 was 11 F g-1 and cycling stability results further indicate that the capacity loss was about 23% during 1000 cycles employing a current density of 20 mA cm-2. The present results represent a significant step forward towards the realization of all-organic material based supercapacitors with aqueous electrolytes and commercially viable capacitances and energy densities.

National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials; Computerized Image Processing
Identifiers
urn:nbn:se:uu:diva-243564 (URN)10.1039/C4RA15894F (DOI)000349524700075 ()
Available from: 2015-01-26 Created: 2015-02-10 Last updated: 2016-09-02Bibliographically approved
4. Solution-processed poly(3,4-ethylenedioxythiophene) nanocomposite paper electrodes for high-capacitance flexible supercapacitors
Open this publication in new window or tab >>Solution-processed poly(3,4-ethylenedioxythiophene) nanocomposite paper electrodes for high-capacitance flexible supercapacitors
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2016 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 5, 1714-1722 p.Article in journal (Refereed) Published
Abstract [en]

Although the development of nanostructured poly(3,4-ethylenedioxythiophene) (PEDOT) with large capacitance and high mechanical flexibility is crucial for the realization of high-performance supercapacitors, such electrodes are generally very challenging to manufacture rapidly and inexpensively. Herein, a straightforward, fast and versatile approach for the fabrication of mechanically robust, highly conductive and flexible nanostructured PEDOT paper is described. The composite material, which can be made within 30 minutes using solution based reactions, exhibits a large surface area (137 m2 g-1) and low sheet resistance (1.4 [capital Omega] [square]-1) as well as high active mass loading (7.3 mg cm-2). Symmetric PEDOT paper-based supercapacitors are shown to provide high specific electrode capacitances (i.e. 90 F g-1, 920 mF cm-2, and 54 F cm-3) and excellent cycling stability (93% capacity retention after 15 000 cycles at 30 mA cm-2) in 1.0 M H2SO4. The electrochemical performance of the supercapacitors was also maintained at different bending angles demonstrating the flexibility of the devices. Given the widespread interest in PEDOT and its broad applicability, the present straightforward procedure for the fabrication of nanostructured PEDOT holds great promise for the realization of different flexible energy storage devices.

National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-272208 (URN)10.1039/C5TA10122K (DOI)000368839200022 ()
Funder
Swedish Foundation for Strategic Research , RMA-110012Swedish Energy AgencyCarl Tryggers foundation
Available from: 2016-01-12 Created: 2016-01-12 Last updated: 2016-09-02Bibliographically approved
5. High areal and volumetric capacity sustainable all-polymer paper-based supercapacitors
Open this publication in new window or tab >>High areal and volumetric capacity sustainable all-polymer paper-based supercapacitors
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2014 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, no 39, 16761-16769 p.Article in journal (Refereed) Published
Abstract [en]

All-polymer paper-based electrodes with a thickness up to hundreds of micrometers (e.g. 290 mu m), large active mass loadings (>20 mg cm(-2)) and relatively high densities (1.23 g cm(-3)) can be straightforwardly obtained from pristine low-cost polypyrrole-cellulose composites by decreasing the porosity of the material via space engineering. By straightforward compression of the composites, compact capacitive storage devices with improved space utilization are obtained without significantly compromising the electrochemical performance of the devices. This indicates that the compression unlike other methods previously used to vary the porosity of these composites does not affect the distribution of the mesopores which mainly determines the electrochemical performance of the material. When used to manufacture green supercapacitors comprising entirely of environmentally friendly materials, the freestanding and binder-free porous yet dense electrodes yield an areal capacitance of 5.66 F cm(-2), a device volumetric energy density of 3.7 W h L-1 (based on the volume of the entire device) and the largest volumetric electrode capacitance of 236 F cm(-3) so far reported for conducting polymer-based electrodes. The presented results for symmetric supercapacitors containing aqueous electrolytes represent significant progress in the development of inexpensive and environmentally friendly high-performance paper-based energy storage devices.

National Category
Polymer Chemistry Engineering and Technology Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-236671 (URN)10.1039/c4ta03724c (DOI)000342880200056 ()
Available from: 2014-11-20 Created: 2014-11-20 Last updated: 2016-09-02
6. Surface Modified Nanocellulose Fibers Yield Conducting Polymer-Based Flexible Supercapacitors with Enhanced Capacitances
Open this publication in new window or tab >>Surface Modified Nanocellulose Fibers Yield Conducting Polymer-Based Flexible Supercapacitors with Enhanced Capacitances
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2015 (English)In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 9, no 7, 7563-7571 p.Article in journal (Refereed) Published
Abstract [en]

We demonstrate that surface modified nanocellulose fibers (NCFs) can be used as substrates to synthesize supercapacitor electrodes with the highest full electrode-normalized gravimetric (127 F g(-1)) and volumetric (122 F cm(-3)) capacitances at high current densities (300 mA cm(-2) approximate to 33 A g(-1)) until date reported for conducting polymer-based electrodes with active mass loadings as high as 9 mg cm(-2). By introducing quaternary amine groups on the surface of NCFs prior to polypyrrole (PPy) polymerization, the macropore volume of the formed PPy-NCF composites can be minimized while maintaining the volume of the micro- and mesopores at the same level as when unmodified or carboxylate groups functionalized NCFs are employed as polymerization substrates. Symmetric, aqueous electrolyte-based, devices comprising these porosity-optimized electrodes exhibit device-specific volumetric energy and power densities of 3.1 mWh cm(-3) and 3 W cm(-3) respectively; which are among the highest values reported for conducting polymer electrodes in aqueous electrolytes. The functionality of the devices is verified by powering a red light-emitting diode with the device in different mechanically challenging states.

Keyword
energy storage devices, conducting polymers, modified nanocellulose, porosity optimization, capacitance
National Category
Chemical Sciences Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-261306 (URN)10.1021/acsnano.5b02846 (DOI)000358823200094 ()26083393 (PubMedID)
Funder
Swedish Foundation for Strategic Research , RMA-110012Carl Tryggers foundation
Available from: 2015-09-03 Created: 2015-09-01 Last updated: 2016-09-02
7. Understanding and Minimising the Self-Discharge of Symmetric Polypyrrole based Energy Storage Devices
Open this publication in new window or tab >>Understanding and Minimising the Self-Discharge of Symmetric Polypyrrole based Energy Storage Devices
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(English)Manuscript (preprint) (Other academic)
Keyword
polypyrrole, energy storage, self-discharge, overoxidation, conducting polymers
National Category
Nano Technology
Identifiers
urn:nbn:se:uu:diva-300916 (URN)
Available from: 2016-08-16 Created: 2016-08-16 Last updated: 2016-09-02

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