A Novel Approach to Engineering Structures of a Solid Oxide Fuel Cell (SOFC): 3D Direct Write Technology

This thesis centers on the use of 3D direct write printing processes to produce Solid Oxide Fuel Cell (SOFC) structures having engineered porosity and macro structure. The objective of the work presented here is to be able to locally control porosity in the anode and cathode structure using 3D direct write printing methods. It is well understood that grading the electrodes enhances the SOFC's performance. A hierarchically graded porous electrode structure, varying from smallest pores at the electrode/electrolyte interface to largest pores at electrode/gas interface can be printed via 3D direct write methods. Layers as thin as 15microm have been achieved using this process. The change in the degree of electrode porosity achieved by varying the graphite loading fraction has been experimentally mapped out. The feasibility of changing the composition/porosity within a layer has been demonstrated, which also opens up possibilities for varying chemical composition within a layer/plane.;The second contribution of this work centers on the synthesis of a channeled electrode architecture aimed at producing structures with extremely low tortuosity. The proposed direct-write synthesis approach overcomes limitations of alternative approaches by allowing symmetric ribs and channels to be printed that balance out shrinkage stresses. The proposed channel architecture has been demonstrated, and models correlating process parameters with resulting surface area have been developed.