Fuel cells have high efficiency, generate low levels of emissions, and can consume renewable sources, in combination with energy vectors, making them excellent candidates as for alternative power production technologies. Fuel cells generate electricity from chemical energy via oxidation of a fuel at the anode, and reduction of oxygen at the cathode . At moderate low temperatures (T<200oC), hydrogen is used as a fuel, whilst a polymeric proton exchange membrane (or solution) acts as the electrolyte to conduct protons and separate the electrodes.
One main challenge is to achieve high ionic conductivities through the electrolyte in the absence of water (or other solvents), so that fuel cells operate at higher temperatures and yield higher efficiencies . Removing solvents from polymer electrolytes will allow to increase operation flexibility, to use cheaper catalysts less sensitive to poisoning (e.g., CO), and to reduce fuel crossover in fuel cells.
The main aim of this PhD project is to prepare and test new liquid crystals with high ionic/proton conductivity, for their application as electrolytes in fuel cells in the absence of solvents.
Proton transport can be achieve by structural diffusion between molecules via the formation of hydrogen bonds . Liquid crystals have local molecular mobility, which can facilitate the diffusion of ions in the short-range, and simultaneously sustain long-range order, which can promote efficient ionic transport from anode to cathode .
Recently, researchers in Aberdeen have shown that liquid crystal polymers can exhibit ionic conductivities in the dc~10-4 S·cm-1 range . Even though these values fall below the dc~0.1 S cm-1 conductivity typical of Nafion, the new materials are promising candidates to achieve ionic conductivities in the absence of solvents. The results also suggest that ionic conductivity can be enhanced by the application of UV-light, by promoting photoisomerisation of azobenzene (light-responsive) groups.
In this PhD, new mechanisms for ionic conductivity of liquid crystals will be investigated by achieving the following objectives:
- Preparation of new liquid crystal electrolytes, by using commercial and newly synthesised monomers and cross-linkers, and including light-responsive elements (azobenzene). Materials include: low molecular weight benzoic acids, light-responsive azobenzenes containing benzoic acids and side-chain liquid crystal polymers containing sulfonate groups.
- Physic-chemical characterisation of the electrolytes, by using thermal analysis (differential scanning calorimetry, DSC, polarised optical microscopy, POM), UV-visible spectrophotometry and infrared spectroscopy (FT-IR).
- Determination of the ionic conductivity by applying electrochemical impedance spectroscopy, EIS, and calculation of the activation energy of the molecular motions. Evaluation of the effect of molecular re-organisation by the simultaneous application of UV-light (365 nm), using Indium Tin Oxide coated transparent electrodes.
Some activities will be performed in collaboration with the Department of Chemistry (University of Aberdeen), and the University of Zaragoza (Spain). The outcomes will be published in different high impact journals of the areas of materials science, engineering, chemistry and energy, including Soft Matter, Chemical Engineering Journal, Advanced Materials or Fuels. The results will be presented in international conferences such as the International Liquid Crystal Conference (ILCC) or the International Conference on Materials Chemistry (MC14).
Candidates should have (or expect to achieve) a UK honours degree at 2.1 or above (or equivalent) in Chemical Engineering, Chemistry or Physics along with knowledge of:
Materials science, including concepts on electrochemical, mechanical and electrical characterisation.
Fundamentals on chemistry and thermodynamics.
Notions on conservation and transport phenomena (mass, energy).
Fundamentals of polymer science and technology.
Alternative energy technologies.
• Apply for Degree of Doctor of Philosophy in Engineering
• State name of the lead supervisor as the Name of Proposed Supervisor
• State ‘Self-funded’ as Intended Source of Funding
• State the exact project title on the application form
When applying please ensure all required documents are attached:
• All degree certificates and transcripts (Undergraduate AND Postgraduate MSc-officially translated into English where necessary)
• Detailed CV
Informal inquiries can be made to Dr A Martinez-Felipe ([email protected]
) with a copy of your curriculum vitae and cover letter. All general enquiries should be directed to the Postgraduate Research School ([email protected]
Additional research costs (ARC) of £1,000 per annum will be required for consumables.
 Z. Sharaf, F. Orhan, “An overview of fuel cell technology: Fundamentals and applications,” Renew. Sustain. Energy Rev., 2014, 32, 810–853.
 Y. Wang, KS. Chen, J. Mishler, SC. Cho, XC. Adroher, “A review of polymer electrolyte membrane fuel cells: Technology, applications, and needs on fundamental research”, Appl. Energy, 2011, 88, 981–1007.
 ME. Schuster, WH. Meyer “Anhydrous proton-conducting polymers” Annu. Rev. Mater. Res. 2003, 33, 233–261.
 A. Martínez-Felipe, “Liquid crystal polymers and ionomers for membrane applications”, Liq. Cryst., 2011, 38, 1607–1626.
 L. Vanti, S. Mohd-Alauddin, D. Zaton, NFK. Aripin, M. Giacinti-Baschetti, CT. Imrie, A. Ribes-Greus, A. Martinez-Felipe, “Ionically conducting and photoresponsive liquid crystalline terpolymers: Towards multifunctional polymer electrolytes”, Eur. Polym. J. 2018, 109, 124-132.