Charlottenlund, Denmark
Charlottenlund, Denmark

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Liao J.H.,CAS Changchun Institute of Applied Chemistry | Liao J.H.,Technical University of Denmark | Li Q.F.,Technical University of Denmark | Rudbeck H.C.,Danish Power Systems Aps | And 5 more authors.
Fuel Cells | Year: 2011

Polybenzimidazole membranes imbibed with acid are emerging as a suitable electrolyte material for high-temperature polymer electrolyte fuel cells. The oxidative stability of polybenzimidazole has been identified as an important issue for the long-term durability of such cells. In this paper the oxidative degradation of the polymer membrane was studied under the Fenton test conditions by the weight loss, intrinsic viscosity, size exclusion chromatography, scanning electron microscopy and Fourier transform infrared spectroscopy. During the Fenton test, significant weight losses depending on the initial molecular weight of the polymer were observed. At the same time, viscosity and SEC measurements revealed a steady decrease in molecular weight. The degradation of acid doped PBI membranes under Fenton test conditions is proposed to start by the attack of hydroxyl radicals at the carbon atom linking imidazole ring and benzenoid ring, which may eventually lead to the imidazole ring opening and formation of small molecules and terminal groups for further oxidation by an endpoint oxidation. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yang J.S.,Northeastern University China | Yang J.S.,Technical University of Denmark | Cleemann L.N.,Technical University of Denmark | Steenberg T.,Danish Power Systems Aps | And 6 more authors.
Fuel Cells | Year: 2014

High temperature operation of proton exchange membrane fuel cells under ambient pressure has been achieved by using phosphoric acid doped polybenzimidazole (PBI) membranes. To optimize the membrane and fuel cells, high performance polymers were synthesized of molecular weights from 30 to 94 kDa with good solubility in organic solvents. Membranes fabricated from the polymers were systematically characterized in terms of oxidative stability, acid doping and swelling, conductivity, mechanical strength and fuel cell performance and durability. With increased molecular weights the polymer membranes showed enhanced chemical stability towards radical attacks under the Fenton test, reduced volume swelling upon the acid doping and improved mechanical strength at acid doping levels of as high as about 11 mol H3PO4 per molar repeat polymer unit. The PBI-78kDa/10.8PA membrane, for example, exhibited tensile strength of 30.3 MPa at room temperature or 7.3 MPa at 130 °C and a proton conductivity of 0.14 S cm-1 at 160 °C. Fuel cell tests with H2 and air at 160 °C showed high open circuit voltage, power density and a low degradation rate of 1.5 μV h-1 at a constant load of 300 mA cm-2. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Martin S.,Technical University of Denmark | Li Q.,Technical University of Denmark | Steenberg T.,Danish Power Systems Aps | Jensen J.O.,Technical University of Denmark
Journal of Power Sources | Year: 2014

A new electrode concept was proved with no polymeric binder in the catalyst layer for acid-doped polybenzimidazole (PBI) membrane fuel cells. It shows that a stable interface between the membrane and the catalyst layer can be retained when a proton conducting acid phase is established. The absence of the polymer in the catalytic layer turned out to be beneficial for the PBI cell performance particularly under high load operation. The influence on performance of the Pt loading of the cathode was studied in a range from 0.11 to 2.04 mgPtcm-2showing saturation of the maximum performance for Pt loadings higher than 0.5 mgPtcm-2. For fuel cell operation on H2and air supplied under ambient pressure, a peak power density as high as 471 mW cm-2was measured. The tolerance to carbon monoxide (CO) was also studied with Pt loadings of the anode ranging from 0.24 to 1.82 mgPtcm-2. Lifetime test for a MEA loaded with 0.96 mgPtcm-2on both electrodes revealed no voltage decay during 900 h of uninterrupted operation at 200 mA cm-2and 160 °C. © 2014 Published by Elsevier B.V.

Li Q.F.,Technical University of Denmark | Rudbeck H.C.,Danish Power Systems Aps | Chromik A.,University of Stuttgart | Jensen J.O.,Technical University of Denmark | And 5 more authors.
Journal of Membrane Science | Year: 2010

Polybenzimidazoles (PBIs) with synthetically modified structures and their blends with a partially fluorinated sulfonated aromatic polyether have been prepared and characterized for high temperature proton exchange membrane fuel cells. Significant improvement in the polymer chemical stability in terms of the oxidative weight loss, molecular weight decrease and onset temperatures for the thermal SO2 and CO splitting-off was achieved with the electron-deficient polybenzimidazoles containing -S(O)2- and -C(CF3)2- bridging groups. Ionical cross-linking in the form of acid-base blends was found to further improve the polymer stability and assist maintaining the membrane integrity. Upon acid doping the membrane swelling was reduced for the modified PBI and their blend membranes, which, in turn, results in enhancement of the mechanical strength, proton conductivity and high temperature fuel cell performance. © 2009 Elsevier B.V. All rights reserved.

Jensen J.O.,Technical University of Denmark | Vassiliev A.,Technical University of Denmark | Olsen M.I.,Technical University of Denmark | Li Q.F.,Technical University of Denmark | And 5 more authors.
Journal of Power Sources | Year: 2012

Direct dimethyl ether (DME) fuel cells suffer from poor DME-water miscibility and so far peak powers of only 20-40 mW cm -2 have been reported. Based on available literature on solubility of dimethyl ether (DME) in water at ambient pressure it was estimated that the maximum concentration of DME at 80 °C will be 300-600 times lower than the ratio 1 to 3 which is the stoichiometric ratio for full conversion to CO 2. To overcome this dilution problem a high temperature polymer fuel cell was operated on DME-water vapor at ambient pressure and with air as oxidant. A peak power density of 67 mW cm -2 was measured at 200 °C. A series of performance curves at temperatures ranging from 150 to 250 °C showed a pronounced temperature effect on the performance. Comparison was made between performances as direct DME and direct methanol cells and the difference was not as large as normally seen with conventional liquid fed cells below 100 °C. © 2012 Elsevier B.V. All rights reserved.

Dey R.S.,Technical University of Denmark | Hjuler H.A.,Danish Power Systems Aps | Chi Q.,Technical University of Denmark
Journal of Materials Chemistry A | Year: 2015

We report a facile and low-cost approach for the preparation of all-in-one supercapacitor electrodes using copper foam (CuF) integrated three-dimensional (3D) reduced graphene oxide (rGO) networks. The binder-free 3DrGO@CuF electrodes are capable of delivering high specific capacitance approaching the theoretical capacitance of graphene and exhibiting high charge-discharge cycling stability. This journal is © The Royal Society of Chemistry 2015.

Steenberg T.,Danish Power Systems Aps | Hjuler H.A.,Danish Power Systems Aps | Terkelsen C.,Danish Power Systems Aps | Sanchez M.T.R.,Technical University of Denmark | And 2 more authors.
Energy and Environmental Science | Year: 2012

We employed roll-to-roll coating in the preparation of 40 μm thick poly[2,2′(m-phenylene)-5,5′bibenzimidazole] (PBI) films for fuel cells using both knife-coating (KC) and slot-die (SD) coating. The films were coated directly from a 9% (w/w) solution of PBI in dimethylacetamide onto a sacrificial low cost paper or plastic based carrier substrate and dried using a hot air oven with a length of 1 m at 140 °C. A web width of 305 mm, a working width of 250 mm and a web speed of 0.2 m min -1 were explored to ensure efficient drying of the thick wet film. A large air flow was found to efficiently avoid skinning. Films were prepared by a single coating step and by two subsequent coating steps in order to explore whether two coating steps gave films with fewer defects. A significant development towards upscaling the PEM fuel cell technology was that the PBI membrane was coated onto a sacrificial carrier substrate allowing for easy recoating on top of the firstly prepared film. It was thus possible to prepare free-standing films by a simple coating procedure followed by delamination from the carrier substrate post-film formation and drying. We finally carried out systematic membrane characterization with respect to solubility, phosphoric acid doping and fuel cell performance. Our results showed that the PBI membranes prepared in this work have identical properties compared to traditionally cast membranes while enabling an increase of a factor of 100 in manufacturing speed. © 2012 The Royal Society of Chemistry.

Agency: Cordis | Branch: H2020 | Program: SME-2 | Phase: SIE-01-2014 | Award Amount: 3.28M | Year: 2015

The German company Siqens has developed a High Temperature Methanol Fuel Cell (HT-MFC) with outstanding technical and economical characteristics. The first product will be an eco-friendly and affordable system named EcoPort for the camping and boat market. EcoPort generates electrical power using renewable methanol liquid fuel. The Danish company Danish Power Systems manufactures the key fuel cell component, the MEA (Membrane Electrode Assembly), for the Siquens products. The project aim sets a significant basis for the efficient and effective transformation of chemical energy from the substance methanol into clean (carbon neutral) electrical energy. The fuel cell from Siquens allows an expanded use of electricity from renewable energies. The production of methanol from wind and sun by Carbon Capture Utilization (CCU) methods is a great chance to store energy of renewables allowing to reach the individual climate goal of the German government (80% renewables in 2050). The ecological benefits of our solution makes it a valuable contribution to the EU climate goals. The market in 2018 for the 800 Watt variant (EcoPort800) is expected to be 930 units with a delivery price of 5,000 EUR each, generating a turnover of more than 4.6 million Euros. In the present project the components and final products need to be finally developed and manufactured with lower costs.

Agency: Cordis | Branch: FP7 | Program: JTI-CP-FCH | Phase: SP1-JTI-FCH.2012.3.1;SP1-JTI-FCH.2012.3.5 | Award Amount: 6.10M | Year: 2013

The vision of the CISTEM project is to develop a new fuel cell (FC) based CHP technology, which is suitable for fitting into large scale peak shaving systems in relation to wind mills, natural gas and SMART grid applications. The technology should be integrated with localized power/heat production in order to utilize the heat from the FC via district heating and should deliver an electrical output of up to 100kW. Additionally the CHP system should be fuel flexible by use of natural gas or use of hydrogen and oxygen which can be provided by electrolysis. This gives the additional opportunity to store electrical energy in case of net overproduction by production of hydrogen and oxygen for use in the CHP system and gives an additional performance boost for the fuel cell. The main idea of the project is a combined development of fuel cell technology and CHP system design. This gives the opportunity to develop an ideal new fuel cell technology for the special requirements of a CHP system in relation to efficiency, costs and lifetime. On the other hand the CHP system development can take into account the special advantages and disadvantages of the new fuel cell technology to realize an optimal system design. The purpose of the CISTEM project is to show a proof of concept of high temperature PEM (HT-PEM) MEA technology for large combined heat and power (CHP) systems. A CHP system of 100 kWel will be set up and demonstrated. These CHP system size is suitable for district heat and power supply. The system will be build up modularly, with FC units of each 5 kWel output. This strategy of numbering up will achieve an optimal adaption of the CHP system size to a very wide area of applications, e.g. different building sizes or demands for peak shaving application. Within CISTEM at least two 5 kWel modules will be implemented as hardware; the remaining 18 modules will be implemented as emulated modules in a hardware in the loop (HIL) test bench. The advantages of the 5 kW modular units are: suitable for mass production at lower production costs, higher system efficiency due to optimized operation of each unit, maintenance on the run, stability and reliability of the whole system. With the help of the HIL approach different climate conditions representing the European-wide load profiles can be emulated in detail. Furthermore, interfaces to smart grid application will be prepared. Increased electrical efficiency for the FC will be obtained by the utilization of oxygen from the electrolyser which is normally wasted, as well as by general improvement of the FCs. Besides, the overall energy efficiency will also be improved by utilization of the produced heat in the district heating system. The latter is facilitated by high working temperature of the HT-PEM FC (i.e. 140 - 180C).

Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: ENERGY-2007-1.2-01 | Award Amount: 3.17M | Year: 2008

Hydrogen has the potential to provide a reliable, secure, and clean source of power. The barrier is the challenge of getting hydrogen economically to the point of use. Water electrolyser offers a practical way of hydrogen production in association with renewable energy sources. Compared to the conventional alkaline electrolyte electrolyser, the polymer electrolyte membrane (PEM) electrolyser can operate at high current densities and pressure with compact design. The main challenges for PEM electrolysers are high capital cost of key materials, components and the overall system as well as insufficient long-term durability. The strategic development of the WELTEMP project is an elevated operating temperature of the PEM electrolyser. In this way the energy efficiency will be significantly improved because of the decreased thermodynamic energy requirement, enhanced electrode kinetics, and the possible integration of the heat recovery. Key issues to achieve this strategic target are breakthroughs of fundamental materials developments, including catalysts, membranes, current collectors, bipolar plates, and other construction materials. The WELTEMP will start with developing active and stable anodic catalysts based on mixed metal oxides, temperature-resistant PEM based on composite PFSA, sulfonated aromatic and/or acid-base cross-linked polymers, and highly conducting and corrosion-resistant tantalum thin surface coatings as current collectors and bipolar plates. Based on these materials, a 1 kW prototype electrolyser will be constructed for demonstration and evaluation. It is aimed to reach operational temperature above 120C and a hydrogen production of 320 NL/h at 80% efficiency (LHV basis) at system level. These innovative developments need trans-national efforts from European industries and R&D groups. The expertise and know-how of the consortium in the field of refractory metals, electrocatalysts, polymers and membranes, MEA fabrication, and most importantly the construction and operation of water electrolysers, will ensure a success of the proposed project.

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