FEMTO-ST-Franche Comté Electronique Mécanique Thermique et Optique - Sciences et Technologies
Video de présentationFrom basic research to industrial partnership
Miniature fuel cells
- Nanosciences
- Miniature fuel cells
Objectives
The aim of this project is to fabricate miniature fuel cells based on porous silicon.
The starting point of the fabrication process consists in machining silicon membranes through KOH wet etching. The silicon membranes are then made porous by anodisation in a fluorhydric medium. The obtained porosity rate is of the order of 50%, with pore diameters around 30 nm. Molecule grafting or ionomere impregnation then allows to get nanoporous silicon. The fuel cell is eventually realised by bonding commercial electrodes containing a catalyst.
Collaborations and funding
LEPMI, Sagem, CEA Liten
European project MICROPAC
Research activities
Top view of a miniature fuel cell
The presented figure shows a top view of the fabricated silicon fuel cell. It consists in a 500 µm thick piece of silicon, 7mm x 7 mm in size. The active part lies in the black centre part of the device (3 mm x 3 mm in size). The golden remaining part of the surface acts like a current collector. This device, once fueled by hydrogen on one side and air on the other side, generates an electrical voltage and hence an electrical current. A typical voltage-current characteristics of such a fuel cell is reported in the Figure below.
Measurement of the voltage and power delivered by the miniature fuel cell as a function of the applied current density.
Perspectives
In the developed approach, proton conductivity is achieved through molecular grafting. The obtained results are better than the inomeric reference Nafion and at lower cost. Our fuel cell performance can however still be improved. A factor of 10 in the protonic conductivity should be obtained by maximizing the grafting density and by changing the nature of the grafted molecules. The main difficulty actually lies in the hydrogen source. A technique currently being patented will be evaluated and tested to tackle this issue.
⇒ 
