Xiuxia Meng

Novel cathode-supported hollow fibers for light weight micro-tubular solid oxide fuel cells with an active cathode functional layer

Micro-tubular SOFCs have the potential to become light-weight portable auxiliary power units for aircraft or spacecraft. In this work, a novel dual-layer ceramic hollow fiber for a cathode-supported micro-tubular solid oxide fuel cell (MT-SOFC) has been successfully developed via a co-spinning-sintering technique. The green cathode hollow fibers, in dual layer configuration, consisting of a La0.8Sr0.2MnO3−δ (LSM) main layer and a LSM–Y2O3 stabilized ZrO2 (YSZ) functional layer with increased three phase boundary length, are first prepared by co-spinning, which are then sintered at around 1350 °C to allow the creation of sufficient mechanical strength. Other cell components like the electrolyte (YSZ) and anode (NiO + YSZ) are then coated separately. The coated electrolyte film with a thickness of around 27 μm is obtained by co-sintering of YSZ/LSM–YSZ/LSM in a sandwich structure. The porous LSM substrate functions as an oxygen-supplying and current collecting layer. The prepared MT-SOFC, tested with hydrogen as the fuel and air as the oxidant, delivers a maximum power density of up to 475 mW cm−2 at 850 °C, which is much higher than that of a similar cell without a cathode functional layer.

Oxygen permeation behavior through Ce0.9Gd0.1O2−δ membranes electronically short-circuited by dual-phase Ce0.9Gd0.1O2−δ–Ag decoration

Electronically short-circuited ion conducting fluorite membranes for air separation are a relatively novel category of ceramic membranes overcoming the long-standing stability problem of the state-of-the-art perovskite membranes under reducing and acidic conditions. Such robust membranes have particular potential to further improve the economics of clean energy projects and syngas production. In this work, we adopted the conventional dual-phase membrane idea to decorate the fluorite membrane surface. Previously, a pure noble metal layer was employed as an electronic decoration layer which displayed several limitations. In this work, instead, a dual-phase mixture of Ce0.9Gd0.1O2−δ (50 wt%)–Ag (50 wt%) was applied as the decoration layer of the Ce0.9Gd0.1O2−δ bulk membrane. Such a strategy not only reduces the material cost and enhances the interface adherence but also significantly improves the O2 flux rates as more triple-phase boundary area is created for surface O2 exchange reactions. We further confirm the stability of the resultant short-circuited Ce0.9Gd0.1O2−δ membrane during the 130 hour permeation test at high temperatures under a CO2 containing atmosphere.