A fuel cell is an electrochemical cell that converts energy
from a fuel into electrical energy. Electricity is generated from the
reaction between a fuel supply and an oxidizing agent. The reactants
flow into the cell, and the reation products flow out of it, while the
electrolyte remains within it. Fuel cells can operate continuously as
long as the necessary reactant and oxidant flows are maintained.
micro-DMFC (Direct-Methanol fuel cell) employ methanol and water to
produce energys, which follows the following chemical reaction:
Since the energy density of methanol is very high (10 times larger than lithium), the energy density of micro-DMFC is much more higher than the traditional fuel cells. Besides, the reaction products are just water and carbon dioxide, which makes micro-DMFC environment friendly.
anode mold of micro-DMFC is fabricated by photolighographe and the
cathode mold of micro-DMFC is fabricated by machine. Then hot embossing
is used to fabricate bipolar plates by the anode and cathode mold. To
improve the hydrophilicity of surface, three bi-layers of PDDA and PSS
are self-assembled on the plates.Gas separation is made of a piece of
carbon paper coated with PTFE.
micro-DMFC is assembled following the structure in figure 1 (right).
Membrane electrode assembles with sealant and the bipolar plates are
sandwitched one by one with bipolar plates as the end plates. Each fuel
cell is serial interconnected by the bipolar plates. The stack can be
extended to more than two fuel cells serial interconnected. Ambient air
could diffuse to cathode catalyst thtough the gap constructed by a
pillar array. The final fuel cells are as shown in figure 1 (right).
Fig 1. Structure of micro-DMFC stack (left) and a single micro-DMFC stack (right)