Meet the smallest fully integrated fuel cell in the world: only 9 mm3 in volume but 254 W per Liter in energy density. This millitechnology power source is the invention of  S. Moghaddam, PhD and his team [1]. A chemical reactor is used to produce hydrogen by reacting a metal hydride with water vapor.




 




The metal hydride chosen is lithium aluminum hydride, LiAlH4  ,which reacts with water to release hydrogen by the following equation:




 




 LiAlH4 (s) + 4 H2O (g)  → Li+ + Al3+ + 4 OH- + 4 H2  (g)





Hydrogen pressure regulates the delivery of water vapor into the reactor thus the rate of reaction. The product hydrogen exits the chamber to reach a membrane electrode assembly. Full microfabricated system operates with its stored fuel and passive control system. External power is not required.

This fuel cell might become the choice portable micropower generator in new electronics.




 




 




[1] Moghaddam, S.; Pengwang, E.; Lin, K. Y.; Masel, R. I.; Shannon, M. A.; Millimeter-Scale Fuel Cell With Onboard Fuel and Passive Control System, Journal of Microelectromechanical Systems, Volume 17,  Issue 6,  Dec. 2008 Page(s):1388 - 1395