Design of new advanced materials for Ionic Electrolyte Membrane Fuel Cells based on graphenes and superionic conductors
IEMFC – Design of new advanced materials for Ionic Electrolyte Membrane Fuel Cells based on graphenes and superionic conductors – is a proposal which focused on Fuel Cells which operate at medium temperatures ( 40- 2000C). Fuel Cells like Solar cells (photovoltaic cells) are the most promising convertors of primary energies. Photovoltaics and electrochemistry convertors (batteries, fuel cells, or super caps), are based on interfacial transfer of energy and/or charge. Fuel cells are convertors where the chemical energy, stored in chemical bonds of the fuels, is converted in electricity and heat via oxidoreduction processes at catalysts-electrolyte interfaces. Solar cells convert direct the photon energy from solar radiation in electricity via photovoltaic effect, which is a electron-hole generator at interfaces of two or multiple semiconductor junctions. Both types of cells have a high theoretical efficiency counted from the basic principles:
1. Solar cells – The theoretical maximum efficiency for this type of cell is about 86%. This is the Carnot limit for sunlight energy conversion on Earth. There is no way of ever going beyond this limit on Earth – it’s a fundamental limit. However, we can keep getting closer. Usually the operating voltage on solar cells is 0.5-0.8 V (open circuit). New advanced research in nanostructured materials and photovoltaic polymers reached 40% in the laboratory research with multilayered junctions. A three-layer cell should be tuned to 1.83, 1.16 and 0.71 eV, with an efficiency of 48%. A theoretical “infinity-layer” cell would have a theoretical efficiency of 64%. In the next step the polymer nanotechnology will bring a new era in solar cells.
2. Fuel cells – The theoretical limits of efficiency for a couple fuel-oxidant, hydrogen/oxygen, is 83-85% (at 298 K). Although fuel cells cannot be compared with Carnot cycle they are evaluated from maximum of Gibbs free energy extracted (available exergy) and enthalpy content Maximum of voltage in open circuit is 1.23V and the power density is dependent of the catalyst efficiency, specific surface area, electron mobility through gas diffusion layer, proton
(hydroxyls or other ions) mobility through electrolyte, the number of electrons participants in the oxidation process of the fuel.
Based on the overview above presented and the actual performances in fuel cells to make competitive these electrochemical convertors we established a general objective: Opening of new pathways for improving of the fuel cell performances from an average efficiency of 50 % to 70-75% and a power density of 400-700mW/cm2 using new advanced materials and appropriate design.
O1 – The study of the graphene implementation in fuel cells (PEMFC, AFC, SAFC)
Target: To free metal catalyst fuel cell
O1.1 – Development of graphenes 1-3 layers, via graphite oxides or graphite by exfoliation in supercritical
fluids. Systems water-alcohools
O1.2 – Development of the graphene foils (1-10 microns) by self assembling, support for catalyst deposition and new gas diffusion layers
O1.3- The exploring of the condition for nitrogen doping of the graphene in subcritical and supercritical conditions with different nitrogen containing substance. Evaluation of the potential of free metal catalyst in ORR
O2 – Design of new IEM:
Target: IEM with ion mobility and their density comparable with electron mobility and density in the electric circuit (the rate of HRR = the rate of ORR)
O2.1 Based on microcellular carbon – ionic conductors ( acidic salts, basic salts, ionomers).
O2.2 Exploring the pathway sol-gel process in designing of membranes composites with high content of sulfonic groups respective basic groups to improve mobility and density of protons/hydroxyls.