A-Site Deficient Lst-Based Perovskite Fibers with Ni Exsolution for Reversible Solid Oxide Cells

Abstract

Reversible solid oxide cells (RSOCs) as new energy converting devices with superior conversion efficiency can operate in both fuel cell (FC) mode and electrolysis cell (EC) mode. However, the main challenges for fuel electrode materials are poor electrochemical performance and limited durability due to the sluggish hydrogen catalysis kinetics. Here, we demonstrate an advanced fiber-structured LaxSrxTi0.9Ni0.1O3-δ (LSTNx) architecture with a series of A-site deficiency (x=0.5, 0.45, and 0.4), which can be applied to reversible solid cells as a promising candidate of fuel electrode materials. LSTNx fibers decorated with Ni nanoparticles (NPs) were fabricated via electrospinning technique and in-situ exsolution method. A-site deficiency played a critical role in Ni exsolution and the morphology of LSTNx nanofibers. La0.4Sr0.4Ti0.9Ni0.1O3-δ fibers with moderate A-site deficiency displayed homogeneous Ni NPs on the surface and excellent stability at 800℃ in pure H2. A single cell with LSTN0.4 fuel electrode (~40 μm) | GDC barrier layer (~0.5 μm) | SSZ electrolyte (~250 μm) | GDC barrier layer (~0.5 μm) | composite LSCF-GDC air electrode (~40 μm) exhibits maximum power density of 547.44 mW·cm-2 at 800℃ in wet H2 and the current density of -1.351 A·cm-2 under the potential of 1.5 V in 50% H2O/H2 atmosphere. The 5-cyclic long-term reversible tests of FC and EC modes were carried out under the potential of 0.5/1.5 V for 60 h, respectively. The current density degradation was approximately 0.67% in EC mode and 2.73% in FC mode after 5-cyclic reversible tests in LSTN0.4 single cells, suggesting a reliable fiber-structured architecture for RSOCs. Figure 1