Engineering Mixed Ionic Electronic Conduction in La_0.8Sr_0.2MnO_3+δ Nanostructures through Fast Grain Boundary Oxygen Diffusivity

Abstract

Nanoionics has become an increasingly promising field for the future development of advanced energy conversion and storage devices, such as batteries, fuel cells, and supercapacitors. Particularly, nanostructured materials offer unique properties or combinations of properties as electrodes and electrolytes in a range of energy devices. However, the enhancement of the mass transport properties at the nanoscale has often been found to be difficult to implement in nanostructures. Here, an artificial mixed ionic electronic conducting oxide is fabricated by grain boundary (GB) engineering thin films of La0.8Sr0.2MnO3+δ. This electronic conductor is converted into a good mixed ionic electronic conductor by synthesizing a nanostructure with high density of vertically aligned GBs with high concentration of strain‐induced defects. Since this type of GBs present a remarkable enhancement of their oxide‐ion mass transport properties (of up to six orders of magnitude at 773 K), it is possible to tailor the electrical nature of the whole material by nanoengineering, especially at low temperatures. The presented results lead to fundamental insights into oxygen diffusion along GBs and to the application of these engineered nanomaterials in new advanced solid state ionics devices such are micro‐solid oxide fuel cells or resistive switching memories.

Effect of La0.6Sr0.4Co0.2Fe0.8O3-δ microstructure on oxygen surface exchange kinetics

“…For both LSCF films, the dominant crystalline orientation is confirmed to be (100) (pseudocubic notation). smooth transition at the interface may be due to the presence of a high concentration of defects which would facilitate ion transport and diffusion [6,16]. Detailed analyses of the two types of LSCF microstructure are currently being performed and results will be reported in the future.…”

“…Recently, studies have also shown that engineering of lattice strain in oxygen ion conductors via heterostructures could lead to significant increases in ionic conductivity [3][4][5]. Studies have further demonstrated enhanced oxygen diffusion mediated by grain boundaries, suggesting the enhancement of mass and charge transport properties in such intrinsic interfaces [6][7]. However, systematic comparison from sample to sample is complicated by the fact that controlling the density and size of grains usually entails modifying the film deposition parameters which would invariably affect its corresponding properties.…”

Reliable current changes with selectivity ratio above 109 observed in lightly doped zinc oxide films

“…8 To overcome the leakage current issue, the mixed-ionicelectronic conduction (MIEC) selector was developed by IBM. 10,11 The MIEC is widely accepted as a nearly ideal selector because it shows low off-current (100 pA), high on-current (10 μA) and steep subthreshold swing characteristics (o60 mV per decade). However, its conduction mechanism is not clearly understood, and its reliability has not yet been confirmed.…”

Nanostructuring the electronic conducting La0.8Sr0.2MnO3−δ cathode for high-performance in proton-conducting solid oxide fuel cells below 600°C

“…Even compared with the conventional intermediate temperature cathode materials, the LSM-BZY cathode in our study shows both smaller electrode polarization resistance and larger fuel cell power output. It has been recently reported that the oxygen diffusion and electrocatalytic activity of LSM are improved at the grain boundary of nanocrystalline films at low temperature [50,51]. One can speculate that this happened also at the surface of LSM nanoparticles, explaining the outstanding increase in power performance.…”