Progress in the use of electrospun nanofiber electrodes for solid oxide fuel cells: a review

The application of one-dimensional nanofibers in the fabrication of an electrode greatly improves the performance of solid oxide fuel cells (SOFCs) due to its advantages on electron transfer and mass transport. Various mixed ionic-electronic conducting materials with perovskites and Ruddlesden-Popper-type metal oxide structures are successfully electrospun into nanofibers in recent years mostly in solvent solution and some in melt forms, which are used as anode and cathode electrodes for SOFCs. This paper presents a comprehensive review of the structure, electrochemical performance, and development of anode and cathode nanofiber electrodes including processing, structure, and property characterization. The focuses are first on the precursor, applied voltage, and polymer in the material electrospinning process, the performance of the fiber, potential limitation and drawbacks, and factors affecting fiber morphology, and sintering temperature for impurity-free fibers. Information on relevant methodologies for cell fabrication and stability issues, polarization resistances, area specific resistance, conductivity, and power densities are summarized in the paper, and technology limitations, research challenges, and future trends are also discussed. The concluded information benefits improvement of the material properties and optimization of microstructure of the electrodes for SOFCs.

Oxygen adsorption properties on a palladium promoted La1−xSrxMnO3solid oxide fuel cell cathode

Pd clusters serve as active centers on the LSM surface and enhance the electron transference properties during oxygen reduction reactions.

Preparation of Sm(x)Ce(1-x)O2(SDC) electrolyte film with gradient structure via a gas-phase controlling convection-diffusion approach on porous substrate

A SDC electrolyte film with gradient structure rooted on porous alumina substrate has been prepared by using a gas-phase controlling convection-diffusion approach. Investigation on the fabrication principles and the co-precipitation kinetics turned out the gradient distribution of hydroxide product of Ce(OH)(3) and Sm(OH)(3) in a porous substrate could be formed as induced by the down-toward diffusion of NH(3)·H(2)O in polar solvent along vertical direction and the up-toward convection of Sm(3+) and Ce(3+) ions over the cross-section of porous substrate, and the aim ratio of Ce to Sm of 4:1 in the sediment phase would be achieved by controlling component concentration in bulk solution. As a result, Sm(0.2)Ce(0.8)O(2.0)(SDC) electrolyte film with gradient microstructure could be fabricated after a subsequent sintering treatment at a high temperature. Investigation of crystal phase, structural, compositional characteristics of the sintered SDC/substrate specimens proved that a uniform and dense SDC film with an average grain size of ~500 nm spread over on the surface of substrate, and a correct cubic fluorite phase has been formed. Gradient variation presented in both the microstructure of SDC/substrate and the component contents over the cross-section of the SDC/substrate. Numerical analysis on the EDX data presented three component parts were sectioned, including a dense SDC layer of ~25 μm, a uniform filling layer of ~140 μm and a successive diffuse layer stretching as far as ~250 μm. Effect of bulk pH on thickness and surface microstructure of SDC film has been discussed. This microstructure-optimization approach will be applicable to fabricate electrode-supported gradient electrolyte films for IT-SOFC.