Revelation mechanism of polarisation process and strategies for high performance in microfluidic fuel cells: A review

The microfluidic fuel cell is one of the most promising micro power sources for the portable electronic devices due to the low cost, environmental friendliness, and substantial power outputs. The practical voltage output is lower than that of thermodynamic theory prediction because of the unavoidable losses in practice, and the polarisation losses are formed from the electrochemical loss, ohmic loss, and concentration loss. Abundant optimisation investigations are conducted in previous articles for decreasing the polarisation loss and improving the cell performance. Researches show that the exchange current density is increased and activation reaction energy barrier is decreased via the decoration and modification of catalytic electrode, thereby reducing the electrochemical loss. Improving the electric conduction via the setting of current collector can effectively reduce the ohmic loss. Moreover, the ohmic loss is decreased by using the high concentration electrolyte and reducing the ion transport distances between the anode and cathode. Optimising the channel and electrode structures including the development of novel structure, the setting of microridge, and array anode can availably limit the fuel concentration and depletion effect, thus decreasing the concentration loss. Significantly, the reduced concentration polarisation is realized by increasing flow rate and employing counter flow configuration.