Mixed cation- and anion-exchange hybrid membranes for use in fuel cells, redox flow batteries and electrodialysis cells

Lead Research Organisation: University of Surrey
Department Name: Chemistry


The research involves the development of hybrid polymer electrolyte membranes and membrane electrode assemblies (HyMEA) that contain distinct cation(proton)- and anion(alkali)-exchange phases with a defined interface or junction between the phases. Two different approaches will be investigated: Approach 1 (lower risk) will involve the fabrication of HyMEAs using commercially available Nafion ionomers and proton-exchange membranes along with Surrey's previously developed alkaline ionomer formulations and alkaline anion-exchange membranes. The second approach (higher risk involving more fundamental explorations) will involve the synthesis of innovative hybrid membranes from a single precursor polymer film where the distinct cation- and anion-exchange phases are separated by a chemical junction/interface and where there are no interferences from undesirable physical separation phenomena between the phases.The HyMEAs will firstly be evaluated in fuel cells with a preferred embodiment where the acidic phase is located at the anode and the alkaline phase is located at the cathode. The use of HyMEAs will allow the use of low humidity hydrogen and air gas supplies as the water generation in the operating fuel cells is at the cation-/anion-exchange junction, which is located away from the electrodes themselves (water generation in the electrodes in traditional fuel cells can disrupt the supply of the reactant gases, which leads to mass transport derived performance losses); the cation-/anion-exchange junction is ideally located inside the HyMEA for maximum retention of the hydration state of the polymer electrolyte membranes and films for maximum ionic conductivity. The synthetic approaches detailed above were deliberately chosen to allow for HyMEAs and hybrid membranes to be synthesised where the cation-/anion-exchange junctions can be located at controlled (and varying) distances from the anode and cathodes; hence the optimum location of water generation (e.g. near to the anode, near to the cathode, located dead centre) can be determined for each approach. The presence of a high pH cathode will also allow for the use of non-platinum (non-Pt) cathodes (the cathodes of traditional hydrogen fuel cells, where the oxygen reduction reaction kinetics are sluggish, contain the bulk of the Pt content; the anode electrokinetics are superior and hence significantly less Pt can be used at the anodes).Recently, hybrid (bipolar) membranes have been applied to technologies such as redox flow batteries and electrodialysis cells: therefore, the project will also evaluate if the application of the hybrid membranes developed above is pertinent to these technologies. The model systems for this impact assessment will be a vanadium redox flow battery and a sodium formate electrodialysis cell.PRINCIPAL AIMS: To develop a range of HyMEAs that are initially targeted for use in hydrogen fuel cells that require non-humidified gas supplies and that contain non-platinum-group-metal cathodes.ENSUING PROJECT AIMS: An initial feasibility study on the use of the developed hybrid membranes in electrodialysis cells and redox flow batteries to explore the potential impact of the developing technologies in non-energy generation applications (water technologies and energy storage).

Planned Impact

The primary commercial beneficiaries of the research (potential wealth generation in 2-10 years) will be companies that are developing / commercialising clean energy and water technologies including materials and components. The programme will generate new knowledge, both fundamental and applied. A direct output of the proposed programme (3-4 year impact window) will be a highly skilled researcher who will have developed multidisciplinary skills and experience of energy generation, energy storage and electrodialysis systems, which are vitally important to the building of sustainable societies; this assists towards the assurance of the trained personnel pipeline. In the long-term, (30-50 years), society itself will be a beneficiary on successful completion of the research as breakthroughs in clean energy generation technologies will have positive impacts on quality of life and health (low pollution levels, mitigation of global warming and energy security). The proposed research programme will involve collaboration with Acta and Mintek. A key advantage of the proposed hybrid fuel cells is the ability to use non-Pt catalysts at the cathode; as such the proposed collaborations with world leaders in the production of non-Pt catalysts, is timely and fully compliments Surrey's alkaline polymer electrolyte expertise. Surrey is now considered to be a world leader in anion-exchange polymer electrolyte materials. Hence, for maximum impact, a 1 - 2 day national workshop on technologies incorporating anion-exchange membranes (including the hybrid membrane systems) will be organised at Surrey in the final 6 months of the proposed project: Academic participants, industrial parties, research councils/policy makers will all be invited. This workshop will help consolidate the UK's leadership in this technological arena and will stimulate new links between the water treatment - clean energy sectors. To further facilitate impact, the results generated from the research will be disseminated at international and UK conferences and meetings (after IP assessment and protection), that are known to attract a mixture of academic participants, policy makers and government agencies, industrial end users and component manufacturers. To foster UK economic competitiveness, the results will also be directly or indirectly fed back into 4 UK consortia, (Alkaline Polymer Electrolyte Fuel Cells (coordinated by a member of the Supergen Fuel Cell Consortium who will act as an indirect link), Supergen Energy Storage and Supergen Biological Fuel Cells), which have associated industrial clubs or industrial collaborators. As is mentioned in the case for support, Surrey started to develop a portfolio of protected IP around alkaline ionomers (identified as a key component for the next breakthrough in alkaline polymer containing fuel cells). The proposed project will explore hybrid membrane fuel cells containing alkaline ionomers and on successful completion will assist in maximising the commercial possibilities applicable to Surrey alkaline ionomer patents. The management of any background and foreground IP will be in consultation with the University's highly successful Research and Enterprise Support Office (see news articles on Surrey Satellite Technology for evidence of excellence). In March 2009, Surrey was awarded a 3.85m Knowledge Transfer Account by the EPSRC, which starts on 01/10/09 and over its 3 year duration Surrey's EPSRC-funded research will drive increased engagement with industrial users and accelerate the exploitation of new technology. Surrey was also awarded funds (Dec 2009) for 2 Doctoral Training Centres (Sustainability for Engineering and Energy Systems & Micro- and NanoMaterials and Technologies). These major awards will maximise the possibilities for generating UK-orientated impact from all of the University's EPSRC funded research and provide clear evidence of Surrey's excellence in the field of novel materials and clean energy.


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Description The aim of the project was to develop mixed cation- and anion-exchange hybrid membranes for use in various electrochemical devices such as hybrid membrane fuel cells (that can operate with low humidity gas supplies). The target materials were where membranes were fabricated that contained cationic [anion-exchange] groups on once side of the membranes and anionic [proton-exchange] groups on the other side such that there would be a cationic/anionic chemical interface inside the membranes. Several strategies were tried involving radiation-grafting techniques, the development of ionically crosslinked materials, and modification of Nafion sulfonyl fluoride precursors. Unfortunately these strategies were unsuccessful in producing the desired hybrid cationic-anionic membranes. For example, the literature suggested that Nafion-sulfonyl fluoride precursor could be used to make high performance anion-exchange membranes. However, the research conducting during this project suggested that this is not the case: We rapidly published a paper to communicate this finding [Ref: J. Mater. Chem. A, 2013, 1, 1018: http://dx.doi.org/10.1039/C2TA00955B (CC-BY open access)].

Despite the lack of success in synthesising the target hybrid cationic-anionic membranes, several new classes of ion-exchange materials were synthesised that would have uses in fuel cells and other electrochemical energy systems. This includes anion-exchange ionomers made from ionically crosslinked polymers (with very high ion-exchange capacities) and radiation-grafted powder materials [J. Mater. Chem. A, 2014, 2, 5124: http://dx.doi.org/10.1039/c4ta00558a (CC-BY open access)].

A major success in the project was the method development allowing radiation-grafted anion-exchange membranes to be fabricated using substantially decreased quantities of expensive (and toxic) vinylbenzyl chloride.
Exploitation Route The materials developed in this project have potential for application in the following technologies:

- Solid Alkaline Fuel Cells and Electrolysers.

- Redox Flow Batteries: Some of the materials and knowhow was given to the EPSRC Supergen Energy Storage grant for testing in redox flow batteries (via Prof Slade [Dept. of Chemistry, University of Surrey] who is CI of this grant);

-Reverse Electrodialysis Cells (Salinity Gradien Power);

-Bioelectrochemical systems such as Microbial Fuel Cells;

-Water purification and desalination;

-CO2 electrolysis cells.

The fabrication of radiation-grafted powders towards the development of a mass producible anion-exchange ionomer concept is a development that holds a significant amount of promise [J. Mater. Chem. A, 2014, 2, 5124 and multiple papers since]. A significant amount of work is being conducted to follow up this development with new ideas on how to modify the process so that a solubilised/dispersed form can be fabricated. There is significant amounts of IP related to these ideas and this is being developed via a Surrey funded PhD studentship.
Sectors Digital/Communication/Information Technologies (including Software),Energy,Environment

URL http://www.surrey.ac.uk/chemistry/people/john_varcoe/
Description Findings being further developed by EPSRC Fellowship (grant EP/I004882/1 and EP/M014371/1).
First Year Of Impact 2013
Sector Chemicals,Energy,Environment
Description Fuel Cell Technologies for an Ammonia Economy (Supergen H2 and Fuel Cell Challenge Call)
Amount £381,469 (GBP)
Funding ID EP/M014371/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 03/2015 
End 03/2019
Description High Spec Raman Spectrometer Regional Facility (Equipment Business Case)
Amount £350,780 (GBP)
Funding ID EP/M022749/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 07/2015 
End 08/2018
Description Multidisciplinary research into linking renewable energy with utilising atmospheric carbon dioxide and with water desalination
Amount £1,200,000 (GBP)
Funding ID EP/I004882/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 08/2010 
End 12/2015
Description Collaboration with Cellera (Israel-based alkaline membrane fuel cell company) 
Organisation CellEra
Country Israel 
Sector Private 
PI Contribution Cellera has supplied electrode samples for testing at Surrey Surrey has supplied anion-exchange membranes and polymer powders for testing at Cellera
Collaborator Contribution CellEra is undertaking extensive fuel cell testing of Surrey membranes and dispersible ionomers.
Impact Joint publications envisaged. In discussions regarding EU funding opportunities (along with Next Energy and DLR in Germany)
Start Year 2013
Description University of Surrey - University of Science and Technology of China (Hefei, PR China) 
Organisation University of Science and Technology of China USTC
Country China 
Sector Academic/University 
PI Contribution Developing new membrane chemistries for alkaline anion-exchange membrane fuel cells. Exchange of materials. Testing of USTC Hefei membranes in Surrey Fuel Cell Test Stations
Collaborator Contribution Supply of USTC Hefei membranes to test in Surrey Fuel Cell Test Stations
Impact NSFC joint grant awarded (NSFC grant 21720102003). Joint papers published: X. Liang, M. A. Shehzad, Y. Zhu, L. Wang, X. Ge, J. Zhang, Z. Yang, L. Wu, J. R. Varcoe, T. Xu, "Ionomer Cross-linking Immobilization of Catalyst Nanoparticles for High Performance Alkaline Membrane Fuel Cell", Chemistry of Materials, 31, 7812 (2019). L. Wu, Q. Pan, J. R. Varcoe, D. Zhou, J. Ran, Z. Yang, T. Xu, "Thermal Crosslinking of an Alkaline Anion Exchange Membrane Bearing Unsaturated Side Chains", J. Membr. Sci., 490, 1 (2015). Y. Zhu, L. Ding, X. Liang, M. A. Shehzad, L. Wang, X. Ge, Y. He, L. Wu, J. R. Varcoe, T. Xu, "Beneficial use of rotatable-spacer side-chains in alkaline anion exchange membrane fuel cells" Energy Environ. Sci., 11, 3472 (2018). X. Lin, X. Liang, S. D. Poynton, J. R. Varcoe, A. Ong, J. Ran, Y. Li, Q. Li, T. Xu, "Alkaline anion exchange membranes containing pendant benzimidazolium groups for alkaline fuel cells", J. Membr. Sci., 443, 193 (2013). X. Lin, J. R. Varcoe, S. D. Poynton, X. Liang, A. Ong, J. Ran, Y. Li, T. Xu, "Alkaline polymer electrolytes containing pendant dimethylimidazolium groups for alkaline membrane fuel cells", J. Mater. Chem. A, 1, 7262 (2013). X. Lin, Y. Liu, S. D. Poynton, A. Ong, J. R. Varcoe, L. Wu, Y. Li, X. Liang, Q. Li, T. Xu, "Cross-linked anion exchange membranes for alkaline fuel cells synthesized using a solvent free strategy", J. Power Sources, 233, 259 (2013). Z. Zhang, L. Wu, J. Varcoe, C. Li, A. Ong, S. Poynton, T. Xu, "Aromatic polyelectrolytes via polyacylation of pre-quaternized monomers for alkaline fuel cells.", J. Mater. Chem. A, 1, 2595 (2013). X. Lin, L. Wu, Y. Liu, A. L. Ong, S. D. Poynton, J. R. Varcoe, T. Xu, "Alkali resistant and conductive guanidinium-based anion-exchange membranes for alkaline polymer electrolyte fuel cells", J. Power Sources, 217, 373 (2012). J. Ran, L. Wu, J. R. Varcoe, A. L. Ong, S. D. Poynton, T. Xu, "Development of imidazolium-type alkaline anion exchange membranes for fuel cell application", J. Membr. Sci., 415-416, 242 (2012). Y. Wu, C. Wu, J. R. Varcoe, S. D. Poynton, T. Xu, Y. Fu, "Novel silica/poly(2,6-dimethyl-1,4-phenylene oxide) hybrid anion exchange membranes for alkaline fuel cells: effect of silica content and the single cell performance", J. Power Sources, 195, 3069 (2010).
Start Year 2010
Description University of Surrey - University of Stuttgart 
Organisation University of Stuttgart
Country Germany 
Sector Academic/University 
PI Contribution Materials exchange Paid for John Varcoe's fliight and hotel to visit Uni Stuttgart Anika Katfuss visit to Surrey to test her materials in our lab (19-23 March 2012)
Collaborator Contribution Supply of materials to Surrey (ion-exchange membranes).
Impact Joint paper published: A. Katzfuss, S. D. Poynton, J. R. Varcoe, V. Gogel, U. Storr, J. Kerres, "Methylated polybenzimidazole and its application as a blend component in covalently cross-linked anion-exchange membranes for DMFC", J. Membr. Sci., 465, 129 (2014).
Start Year 2011
Description Hosted Workshop: Anion-exchange membranes for energy generation technologies 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation workshop facilitator
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The PI organised a workshop (with invited delegates) on 25 - 26th July 2013 [hosted at the University of Surrey] to discuss anion-exchange membranes in various clean water and energy generation technologies. The funding was provided by: The UK's Engineering and Physical Sciences Research Council (EPSRC grants EP/I004882/1 and EP/H025340/1), the University of Surrey's Institute of Advanced Studies, the Research Council UK's Energy Programme's Supergen Hydrogen and Fuel Cell Research Hub (EPSRC grant EP/J016454/1), the Royal Society of Chemistry (Energy and Environmental Science), Caltest Instruments Ltd. (UK), Alvatek Ltd. (UK), Solartron Analytical UK (Ametek), and Prof Andrew Herring (Colorado School of Mines).

Since 2003, the Department of Chemistry, University of Surrey has been looking at anion-exchange membrane in electrochemical energy technologies. To mark the 10th year of these efforts, Surrey hosted a 2 day workshop to establish a consensus of the state-of-the-art. Select and renowned researchers from around the world [industrial and academic] were invited to participate. The workshop will also look at suitable next steps along with establishing new international collaborations in the field.

An invited 56 page review published:

J. R. Varcoe, P. Atanassov, D. R. Dekel, A. M. Herring, M. A. Hickner, P. A. Kohl, A. R. Kucernak, W. E. Mustain, K. Nijmeijer, K. Scott, T. Xu, L. Zhuang,
"Anion-exchange membranes in electrochemical energy systems",
Energy Environ. Sci. 7, 3135 (2014)
Year(s) Of Engagement Activity 2013
URL http://www.ias.surrey.ac.uk/workshops/membranes/report.php