A dual-structured anode/Ni-mesh current collector hollow fibre for micro-tubular solid oxide fuel cells (SOFCs)

Abstract

In this study, a unique dual-structured hollow fibre design has been developed for micro-tubular solid oxide fuel cells (MT-SOFCs), using a single-step phase-inversion assisted co-extrusion technique. The dual-structured design consists of an outer anode layer and an inner anodic current collecting layer that are formed simultaneously during fabrication. Meanwhile, a plurality of micro-channels initiating from the exterior surface of the anode layer penetrate through the two layers, forming a highly asymmetric anode and a mesh current collecting layer, which significantly facilitates the gas transport. With the increasing thickness of the current collecting layer (approximately 15–60 μm), electrical conductivity increases from 1.9 × 104 S cm−1 to 4.0 × 104 S cm−1, while the mechanical strength drops slightly from approximately 168–113 MPa due to its ‘dragging effect’ during co-sintering. The benefits of improved current collection may potentially overweigh the reduced mechanical property, especially when dual-structured hollow fibres of this type are bundled together to form a stack. Moreover, benefiting from this innovative design, sustainable development of a larger scale of MT-SOFC stack or system becomes less challenging, since technical issues, such as concentration polarization and efficient current collection, hampering the MT-SOFC system design, can be completely overcome.