Charge separation and transport in La0.6Sr0.4Co0.2Fe0.8O3-δ and ion-doping ceria heterostructure material for new generation fuel cell

• Published in: Nano energy Vol. 37; pp. 195 - 202
• Main Authors: Zhu, Bin, Wang, Baoyuan, Wang, Yi, Raza, Rizwan, Tan, Wenyi, Kim, Jung-Sik, van Aken, Peter A., Lund, Peter
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2017
• Subjects: Charge separation; Charge separation, ionic transport; Composite; Fuel cell device; Heterostructure; ionic transport; Semiconductor ionic fuel cell; Semiconductor-ion material; Heterostructure; Semiconductor-ion material; Fuel cell device; Semiconductor ionic fuel cell; Composite; Charge separation, ionic transport
• ISSN: 2211-2855; 2211-3282
• DOI: 10.1016/j.nanoen.2017.05.003

Functionalities in heterostructure oxide material interfaces are an emerging subject resulting in extraordinary material properties such as great enhancement in the ionic conductivity in a heterostructure between a semiconductor SrTiO3 and an ionic conductor YSZ (yttrium stabilized zirconia), which can be expected to have a profound effect in oxygen ion conductors and solid oxide fuel cells [1–4]. Hereby we report a semiconductor-ionic heterostructure La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and Sm-Ca co-doped ceria (SCDC) material possessing unique properties for new generation fuel cells using semiconductor-ionic heterostructure composite materials. The LSCF-SCDC system contains both ionic and electronic conductivities, above 0.1S/cm, but used as the electrolyte for the fuel cell it has displayed promising performance in terms of OCV (above 1.0V) and enhanced power density (ca. 1000mW/cm2 at 550°C). Such high electronic conduction in the electrolyte membrane does not cause any short-circuiting problem in the device, instead delivering enhanced power output. Thus, the study of the charge separation/transport and electron blocking mechanism is crucial and can play a vital role in understanding the resulting physical properties and physics of the materials and device. With atomic level resolution ARM 200CF microscope equipped with the electron energy-loss spectroscopy (EELS) analysis, we can characterize more accurately the buried interface between the LSCF and SCDC further reveal the properties and distribution of charge carriers in the heterostructures. This phenomenon constrains the carrier mobility and determines the charge separation and devices’ fundamental working mechanism; continued exploration of this frontier can fulfill a next generation fuel cell based on the new concept of semiconductor-ionic fuel cells (SIFCs). The charge separation processes, from nano-particle level to the device level, are key to the scientific understanding of the SIFCs. The synergistic effect of junction and energy band alignment towards the charge separation from particle to device level, in particular blocking electron crossover, as well as the promotion of ion transport by built-in field, contribute to the working principle and facilitates high power output in the SIFC. Thus, it can realize fuel cell functions and fuel-to-electricity conversion through different means from the conventional fuel cell, wherein the semiconductor-ionic heterostructure, charge separation and junction play key roles, and joining physics and electrochemical processes are in force. [Display omitted] •Functionalities in heterostructure oxide material interfaces.•The LSCF-SCDC system contains both ionic and electronic conductivities.•Enhanced power density (ca. 1000mW/cm2 at 550°C).•Next generation fuel cell will be based on the new concept of semiconductor-ionic.