Abstract Purpose – The purpose of this work is to present the strategies and current state of development in the field of micro solid oxide fuel cells (mSOFC)。 Design/methodology/approach – In the paper recent strategies of conventional and single chamber mSOFC are described。 Some examples based on the author’s research are presented。Findings – It can be concluded that scale down of ceramic technologies is still more popular than MEMS。 However, MEMS-based technologies become recently to be used more frequently。Research limitations/implications – The work is limited to the description of materials and technologies used in mSOFC。Originality/value – The review presents very recent research in mSOFC。 The results demonstrate critical areas in development of suitable technologies。84899

Keywords Films (states of matter), Fuels, Electric power generation Paper type General review

1。Introduction

More and more nowadays, there is a growing demand for relatively low power, autonomous power sources due to increasing existence of sensors, actuators and miniaturized and portable systems。 The devices, which can provide between 0。5 and 50 W of power, are frequently called micro power sources。

For this purpose fuel cells are particularly  attractive because:

●they can directly convert from chemical to electrical energy with high efficiencies (< 50 percent);

●the volumetric energy densities are one of the highest in comparison to the other energy systems;

●they are low-vibration and low-noise systems and provide minimum or no air pollution;  and

●unlike batteries  they  can  continuously  produce  energy (as long as fuel is   provided)。

Micro direct methanol fuel cells (m-DMFC) are the most studied technology as micro power source for replacing batteries because theoretically direct methanol fuel  cell could achieve energy as high as  5 kWh/l。  There  are  still some drawbacks that have to   be   overcome; nevertheless the first commercial systems are already available on the market。 Micro solid oxide fuel cells (mSOFC) are  one possible alternative to  m-DMFC。  It  is  predicted  that  they will have 3-4 times higher energy density and  specific energy than traditional Ni metal hydride and  Li-ion batteries。

The current issue and full text archive of this journal is available at

www。emeraldinsight。com/1356-5362。htm

Microelectronics International 25/2 (2008) 42– 48

q Emerald Group Publishing Limited [ISSN 1356-5362] [DOI 10。1108/13565360810876001]

2。

Solid oxide fuel cells

Solid oxide fuel cells (SOFCs) are one of the most efficient energy conversion devices。 Although Sir William Grove constructed the first SOFC in 1839, it is the NASA space program in the 1960s which moved their development forward。 They are one of the most efficient energy conversion devices because the SOFCs chemical energy is directly converted into electrical。 Their working mechanism, briefly speaking, is based on the  difference  of  chemical  potential  between  two  sides of solid electrolytes, which conducts oxygen ions only。 The difference of chemical potential is created when gases with different oxygen partial pressures (e。g。 hydrogen and air) are supplied to anode and cathode side of electrolyte。 As a result of chemical potential gradient in the electrolyte the electromotive force is formed in accordance with Nernst law。 Once anode and cathode are connected with external circuit, the electrical current is flowing due to flow of ionic current in the electrolyte and electrochemical reactions at the electrodes。 In this way chemical energy stored in the gases is converted into electrical one。