Novel aluminium air batteries for ultralight micro-aircraft

Abstract

This thesis investigates the feasibility of using a structural aluminium air battery to power an ultralight, unmanned micro-aircraft. Weight loss, voltammetry and scanning electron microscopy have been used to investigate the rate of corrosion and anodic dissolution of aluminium materials in potential battery electrolytes. Various alloys were examined in both alkaline and saline electrolytes and there were substantial differences in corrosion resistance, types of corrosion and overpotential required for anodic dissolution. It was found that high purity aluminium and alloys with small additions of certain metals had better corrosion resistance in alkaline solution. No materials investigated would allow extended storage of a battery; emphasis was therefore placed on a cell where 8M KOH Vias added immediately before discharge. AB50V, an AI-Mg-Ga-Sn alloy, was selected as the negative electrode in a small aluminium-air battery. This alloy had an open circuit potential of ~ -2.0 V vs. SCE and gave a current density of 100 rnA cm-2 at ~ -1.8 V vs. SeE. A test battery cell was constructed incorporating a Pt-catalysed air cathode, and a battery voltage of ~ 1 J V at a current density of 160 rnA cm-2 was obtained using the AB50Valloy. The non-availability commercially of more alloys \vith fully specified compositions and a controlled range of compositions hampered both the scientific interpretation of the data and the optimisation of battery performance. High surface area fOTIns of aluminium should substantially improve this performance but are only available commercially in Al of unspecified composition. Commercially available AI foams were found to corrode very rapidly. Stacked meshes made with melts pun aluminium were compressed, and although they showed reasonable structural strength, did not show the required performance; meltspun fibres are inherently impure due to the fabrication process and so were lillsuitable for making high purity alloys. With the low weight of the current structural polymer foam used in production of the U A V, the positioning of the battery system on the plane is constrained to a skin around the nose cone. Such a design would, however, provide additional structural support to the aircraft, increase significantly the volume for electronics and sensory equipment in the pod. and reduce heating of such equipment by the battery operation.

More information

Identifiers

Catalogue record

Export record

ASCII CitationAtomBibTeXData Cite XMLDublin CoreDublin CoreEP3 XMLEndNoteHTML CitationHTML CitationHTML ListJSONMETSMODSMPEG-21 DIDLOpenURL ContextObjectOpenURL ContextObject in SpanRDF+N-TriplesRDF+N3RDF+XMLRIOXX2 XMLReferReference ManagerSimple Metadata