Nash, Scott and Dawson, Richard and Andrieux, Fabrice (2017) The development of a membraneless direct borohydride alkaline fuel cell. PhD thesis, Lancaster University.
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Abstract
Fuel cells offer the potential for the generation of clean, renewable energy source for a wide variety of applications. Low temperature fuel cells (< 150 °C) are most suitable for portable applications, out of these the alkaline fuel cell (AFC) shows increased electrode kinetics over other fuel cell types. The direct borohydride alkaline fuel cell (DBAFC), a derivative of the AFC, can provide increased power output and improved safety features afforded using borohydride in place of hydrogen gas. However, relatively little research has been conducted on DBAFC, particularly membraneless DBAFC. This work aims to address this and describes an investigation into every aspect of DBAFC to evaluate their deployment on an industrial scale.As such, candidate electrocatalysts were assessed for their electrocatalytic activity towards the oxidation of borohydride in alkaline media for use in DBAFCs using cyclic voltammetry. The candidate electrocatalysts, including Pt, Pd and Ru on activated C and cathode electrocatalysts were then developed into a screen printable electrode ink, a method which could be easily upscaled for mass manufacture. A screen-printed anode developed outperformed commercially available AFC anodes with the developed cathode performing sufficiently when evaluated using electrochemical polarisation. Computer simulations were used to design individual components of a DBAFC, which were built and tested experimentally through operational use and electrochemical impendence analysis. The developed DBAFC performed well, with theoretically low ionic leakage when in a stack, good distribution of electrolyte and air and a low cell weight. Finally, a system was designed to evaluate different electrolyte flow methods and operating conditions and produced a flexible testing system for DBAFC suitable for scale up.The results generated indicate that DBAFCs are a viable alternative to other low temperature fuel cells. Using an effective anode electrocatalyst and system design, DBAFC could be used for a variety of applications.