1) Material Synthesis and characterizations
In total, 46 ionic liquids (ILs) and produced 22 IL-based ferrofluids (IL-FF) were synthesized. Among which, several IL-FFs were found to be stable up to 200°C. A toolbox for both optimized conception and experimental characterization of stable dispersions in ILs is now available.
The scale-up process was undertaken for the best performing ionic liquid, EMI-TFSI, selected for MAGENTA’s proof-of-concept prototype.
2) Thermodiffusion (TD) and thermoelectric (TE) investigations
A high temperature Forced Rayleigh Scattering device with external magnetic field application functionality was developed and used to study TD properties of magnetic nanoparticles (MNP) in IL-FFs. The adaptation of existing theoretical models to encompass TD phenomena in ionic liquids has been achieved.
The aforementioned ILs and IL-FFs were systematically characterized for their TE properties (Se coefficient, power output and capacitance) and compared to theoretical predictions. The best results were obtained with EMI TFSI (IL) and propylene carbonate in combination with Co2+/3+ redox salts. Improvements in the Se coefficient and the thermocell power output were achieved by proper tuning of MNP coating in IL-FFs. A substantial increase in the thermocell’s specific capacitance (compared to the pure IL) was also observed. These findings reveal hitherto unknown TE conversion mechanisms in complex liquid systems.
3) Theory/Simulation
The ab-initio calculations and MD-simulations have successfully incorporated the chemical and structural compositions of MNPs to reproduce corresponding magnetic and electronic nature observed experimentally. These new findings are extended to predict the FF’s Se coefficient and its optimization scheme.
Over 15000 ILs were examined (with two types of redox couples) using a QSPR algorithm to predict Se-coefficients and other key physical parameters. The comparisons with experimental measurements confirm the model validity. For IL-FFs, the particle structure optimization (including coating molecules) was performed to determine several quantum-chemical properties, such as dipole moments, relative energies, charges, etc..
Analytical models inspired dilute semiconductors have been developed. The experimentally observed I–V characteristics the two-stage Se effect in dilute ferrofluids have been successfully reproduced. The proposed models also lends support to the aforementioned concept of MNP adsorption.
4) Prototyping
Three application-specific prototypes were built and tested.
A multi-channel demonstrator TEG device was tested (with EMI-TFSI/ Co2+/3+ redox) producing a maximum power density of 72.9 mW/m2 at a temperature differential of 150 ⁰C. The electrical output of the system was connected to a stand-alone power management circuit board to light an LED
Based on the multi-channel demonstrator, numerical simulations on the electrical and thermal performance was performed for designing the ICE prototype. The prototype testing shows the scalability of TE-energy harvesting system using high temperature ILs in automotive applications. A micro-TE prototype consisting of 100 channels electrically connected in series can be used for both rigid and flexible TEG, and functional at both high and low temperature ranges. The power-output varied between 140 and 766 mW/m2 depending on the choice of IL/redox and the temperature range
5) Dissemination
In total, we have published 55 research manuscripts, made over 100 presentations at conferences and workshops, and co-organized several international conferences.
In addition to the project website, Twitter and YouTube accounts were created to reach wider audience. Other communication examples include: Popular science magazines, Science Fairs, TV, Radio interviews and partner institutions’ websites.
The members also attended EU's innovation uptake events such as EIC Pathfinder showcase, FETFX Future TechWeek (2020) and FET-Briefing Research meets Industry (2020)
