MnO3 Cathode Research Articles

An investigation of Cr vaporization from SUS430 metallic interconnect and deposition on (La,Sr)MnO3 cathode of intermediate temperature solid oxide fuel cells

In solid oxide fuel cells (SOFCs), chromium deposition and poisoning of metallic interconnect is one of the most important issues in the electrochemical activity and stability of the cathode for the oxygen reduction reaction (ORR). In this paper, the chromium evaporation characteristics, oxide scale growth, and deposition of chromium on the ORR on (La,Sr)MnO3 (LSM) cathode are studied at 700–800 °C for SUS430 alloy interconnect material in the intermediate-temperature solid oxide fuel cells. The chromium vaporization rate is measured using the transpiration technique and the surface morphologies, and cross-sections of oxide scales are examined by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The results indicate that chromium volatilization is correlated with the composition and morphology of the oxide scale, the Cr volatilization process presents two stages according to the structural evolution of the oxide scale. In addition, deposition and poisoning of Cr species released from metallic interconnect on the LSM cathode are studied and the formation of MnCr2O4 phase on the LSM backbone degrades the ORR electrochemical activity, causing the increase of overpotential of the cathode. The results obtained give insight into the mechanism of the Cr poisoning effect in intermediate-temperature.

Experimental and computational investigations on the SO2 poisoning of (La0.8Sr0.2)0.95MnO3 cathode materials

To study the formation of detrimental phases under the sulfur gas impurity to the long-term degradation in the LSM cathode material, the classic cathode material, (La 0.8 Sr 0.2 ) 0.95 MnO 3 (LSM), was prepared, sintered, and annealed at 800, 900, and 1000 °C in the sulfur-containing atmospheres, respectively. Through X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Transmission electron microscopy (TEM) techniques, as well as the CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) methodology, the secondary phases, especially the detrimental ones, under different conditions were predicted and experimentally verified correspondingly. Furthermore, sulfur poisoning results indicate that the accelerated tests might have degradation mechanisms different from actual operation conditions. More importantly, comprehensive comparisons among various impurity-containing conditions were also made to recommend better operation parameters.

Correlation Microstructure of Triple Phase Boundary and Crystallinity in SOFC Cells NiO/LSGM/LCM

The electrochemical process in the TPB microstructure depends on the conductivity of the SOFC cell constituent materials. Electrolyte and electrode materials must have good conductivity. The crystallinity of an electrolyte can affect its conductivity. In this study, the electrolyte La0.8Sr0.2Ga0.8Mg0.2O3–δ (LSGM) was used and is known to have good conductivity at intermediate temperatures. The single cell of LSGM electrolyte with La0.7Ca0.3MnO3 (LCM) cathode which has high electronic conductivity and NiO anode which has low area-specific resistance (ASR) is expected to produce compatible cells. The production of NiO/LSGM/LCM cells was carried out through the solid-solid phase synthesis method. Microstructural analysis of TPB was performed using SEM-EDS; meanwhile, crystallinity was obtained through XRD analysis. The crystallinity values of NiO, LSGM and LCM cell components above 80% allow the cells to produce high conductivity with a three-phase boundary microstructure from porous electrodes and relatively dense electrolytes which can increase the possibility of gas, ion and electron encounters in the TPB. In SOFC NiO/LSGM/LCM cells, Ni=11.08%; Ca=6.84%; Mn=9.28% and no precipitate is formed at the electrolyte-electrode boundary, so that the electrochemical process on the TPB microstructure could run well.

Nanoscale Analysis of LSM/YSZ Interfaces within Composite Cathodes for Commercial Solid Oxide Fuel Cells

While performance degradation for solid oxide fuel cells (SOFCs) comes in many forms, one important contributor is cation transport during long-term operation. This transport alters the chemical composition at electrode/electrolyte interfaces. These interfaces are carefully engineered to provide the critical reaction sites for oxidation and reduction reactions that regulate SOFC electrical production. Therefore, fundamental understanding of the chemical evolution of these interfaces is critical. The current study coordinates scanning transmission electron microscopy (STEM) with atom probe tomography (APT) in order to probe composition at the nanoscale across cathode/electrolyte interfaces for anode-supported commercial SOFCs. These SOFCs contain a porous composite cathode layer, consisting of sintered (La0.8Sr0.2)0.95MnO3 cathode particles and yttria-stabilized zirconia (YSZ) electrolyte particles. SOFCs are operated up to 500 hours in duration at a current density of 0.75 A/cm2 (or at open circuit) and at an operation temperature of 800°C. Measured cell voltage increases over the first 100 hours of operation, followed by a steady and linear drop in cell voltage that translates to 5.35% performance loss per 1000 hours. STEM-based energy dispersive spectroscopy (EDS) indicates nanoscale Mn-oxide formation at LSM particle surfaces after 500 hours of operation. Compositional profiles acquired by APT across LSM/YSZ particle interfaces indicate as-sintered interfaces are chemically well-defined, but La and Mn penetrate up to 5 nm into YSZ particles over the course of 500 hours. Additionally, as-sintered LSM particles exhibit measurable Mn enrichment within 20 nm of an adjacent YSZ particle. After 100 hours of operation, A-site deficiency is restored for LSM particle surfaces adjacent to YSZ. Meanwhile, the YSZ composition adjacent to LSM exhibits depletion in Y content over the first 100 hours of operation. These results suggest that initial cell voltage increase within 100 hours of operation corresponds to both Mn and Y transport at LSM/YSZ interfaces. STEM-based electron energy loss spectroscopy (EELS) provides additional insight regarding local cation valence states in relation to measured composition variations for these LSM/YSZ interfaces.

Influence of Bi1.5Y0.5O3 Active Layer on the Performance of Nanostructured La0.8Sr0.2MnO3 Cathode

The efficiency of solid oxide fuel cell cathodes can be improved by microstructural optimization and using active layers, such as doped bismuth oxides. In this work, Bi1.5Y0.5O3 (BYO) films are prepared by spray-pyrolysis deposition at reduced temperatures on a Zr0.84Y0.16O1.92 (YSZ) electrolyte. The influence of the BYO film on the performance of an La0.8Sr0.2MnO3 (LSM) cathode prepared by traditional screen-printing and spray-pyrolysis is investigated. A complete structural, morphological, and electrochemical characterization is carried out by X-ray diffraction, electron microscopy, and impedance spectroscopy. The incorporation of BYO films decreases the Area Specific Resistance (ASR) of screen-printed cathodes from 6.4 to 2.2 Ω cm2 at 650 °C. However, further improvements are observed for the nanostructured electrodes prepared by spray-pyrolysis with ASRs of 0.55 and 1.15 Ω cm2 at 650 °C for cathodes with and without an active layer, respectively. These results demonstrate that microstructural control using optimized fabrication methods is desirable to obtain high-efficiency electrodes for solid oxide fuel cell (SOFC) applications.

High Volumetric Energy Density Sulfur Cathode with Heavy and Catalytic Metal Oxide Host for Lithium-Sulfur Battery.

For high‐energy lithium–sulfur batteries, the poor volumetric energy density is a bottleneck as compared with lithium–ion batteries, due to the low density of both the sulfur active material and sulfur host. Herein, in order to enhance the volumetric energy density of sulfur cathode, a universal approach is proposed to fabricate a compact sulfur cathode with dense materials as sulfur host, instead of the old‐fashioned lightweight carbon nanomaterials. Based on this strategy, heavy lanthanum strontium manganese oxide (La0.8Sr0.2MnO3), with a high theoretical density of up to 6.5 g cm−3, is introduced as sulfur host. Meanwhile, the La0.8Sr0.2MnO3 host also acts as an efficient electrocatalyst to accelerate the diffusion, adsorption, and redox dynamics of lithium polysulfides in the charge–discharge processes. As a result, such S/La0.8Sr0.2MnO3 cathode presents high gravimetric/volumetric capacity and outstanding cycling stability. Moreover, an ultra‐high volumetric energy density of 2727 Wh L−1 ‐cathode is achieved based on the densification effect with higher density (1.69 g cm−3), which is competitive to the Ni‐rich oxide cathode (1800–2160 Wh L−1) of lithium–ion batteries. The current study opens up a path for constructing high volumetric capacity sulfur cathode with heavy and catalytic host toward practical applications of lithium–sulfur batteries.

Suitability of strontium and cobalt-free perovskite cathodes with La9.67Si5AlO26 apatite electrolyte for intermediate temperature solid oxide fuel cells.

Aluminium-doped lanthanum silicate (LSAO) apatite-type compounds have been considered as promising candidates for substituting yttria-stabilized zirconia (YSZ) as electrolytes for intermediate temperature solid oxide fuel cells (IT-SOFC). Nevertheless, not many materials have been reported to work as cathodes in a LSAO apatite-based cell. In the present work, eight different strontium and cobalt-free compounds with a perovskite-type structure and the general composition LaM1-xNxO3-δ (where M = Fe, Cr, Mn; N = Cu, Ni; and x = 0.2, 0.3) have been tested. This study includes the synthesis and structural characterization of the compounds, as well as thermomechanical and chemical compatibility tests between them. Functional characterization of the individual components has been performed by electrochemical impedance spectroscopy (EIS). Apatite/perovskite symmetrical cells were used to measure area-specific resistance (ASR) of the half cell in an intermediate temperature range (500-850 °C) both with and without DC bias. According to its electrochemical behaviour, LaFe0.8Cu0.2O3-δ is the most promising material for IT-SOFC among the compositions tested since its ASR is similar to that of the traditional (LaxSr1-x)MnO3 (LSM) cathode.

Improvement of electrochemical performance of Li1.96Mg0.02MnO3 by surface treatment

As a prospective cathode material, the main shortages of Li2MnO3 are its low practical capacity and poor cycling stability. Here, an electrochemically stable and low-cost nickel nitrate surface treatment of Li1.96Mg0.02MnO3 cathode material is prepared by solid-state reaction. The advantage of this material lies in Mg2+ ions playing a key role in improving the discharge capacities by larger amount of Li+ extracted and inserted through Li vacancies. Meanwhile, nickel containing layered oxide coating layer serves as the protector to suppress the dissolution of manganese as well as stabilizing the layer structure. As a result, this cathode delivered a superior discharge capacity of 177.4 mAh g−1 after 40 cycles at 0.1C, which was approximately 57.8% higher than that of pristine Li2MnO3. After comparison, it presented an optimal rate performance at different C rate. Therefore, surface treatment will bring Li1.96Mg0.02MnO3 a bright future at the race of cathode development for lithium ion batteries.

Effect of Fe Substitution on the Structural, Electrical and Dielectric Properties of La0.70Ca0.30MnO3 Cathode for SOFCs

Perovskite solid solutions (La0.70Ca0.30)(FexMn1-x)O3 where x = 0.01, 0.20, 0.30 and 0.40 ceramics were synthesized by solid state reaction route. The structural studies were carried by X-Ray diffraction method and the observed results have indicated that all the prepared samples were crystallized into single phase. The surface morphology was studied by Scanning Electron Microscopy and the images have revealed that grain size has increased with the increasing concentration of Fe. Archimedes principle was used to calculate the density of all the sintered samples and the density values were observed to be in increasing order. The impedance and dielectric properties have been characterized at different ranges of temperature and frequency. The value of electrical conductivity were found to be more than 100 S cm-1, which indicate that the synthesized material is suitable material for cathode of Solid Oxide Fuel Cell.

First principles calculations of oxygen reduction reaction at fuel cell cathodes

Abstract The efficiency of solid oxide fuel cells (SOFC) depends critically on materials, in particular for the cathode where the oxygen reduction reaction (ORR) occurs. Typically, mixed conducting perovskite ABO3-type materials are used for this purpose. The dominating surface terminations are (001) AO and BO2, with the relative fractions depending on materials composition and ambient conditions. Here, results of recent large-scale first principles (ab initio) calculations for the two alternative polar (La,Sr)O and MnO2 (001) terminations of (La,Sr)MnO3 cathode materials are discussed. The surface oxygen vacancy concentration for the (La,Sr)O termination is more than 5 orders of magnitude smaller compared to MnO2, which leads to drastically decreased estimated ORR rates. Thus, it is predicted for prototypical SOFC cathode materials that the BO2 termination largely determines the ORR kinetics, although with Sr surface segregation (long-term degradation) its fraction of the total surface area decreases, which slows down cathode kinetics.

Lowered Sintering Temperature on Synthesis of La9.33Si6O26 (LSO) – La0.8Sr0.2Ga0.8Mg0.2O2.55 (LSGM) Electrolyte Composite and the Electrical Performance on La0.7Ca0.3MnO3 (LCM) Cathode

Solid oxide fuel cell (SOFC) is the device that can convert chemical energy into electricity with highest efficiency among other fuel cell. La9.33Si6O26 (LSO) is the potential electrolyte at intermediate operation temperature SOFC. Low ionic conductivity of lanthanum silicate-based electrolyte will lead into bad electrical performance on lanthanum manganite-based anode. In this study, LSO was combine with La0.8Sr0.2Ga0.8Mg0.2O2.55 (LSGM) electrolyte by using conventional solid state reaction to enhance the electrical performance of LSO on LCM cathode. However, pre-requisite high sintering temperature on preparation of LSO-LSGM composite will lead into phase transition phase of LSGM that may affect in decreasing the electrical performance. This study resulted that lowered sintering temperature from its ideal temperature still give an improved electrical performance of LCM/LSO-LSGM/LCM symmetrical cell. The ASR value is 0.14 Ω.cm2 which much lower than its analogous symmetrical cell, LSM/LSO/LSM that was reported before.

Interface formation and Mn segregation of directly assembled La0.8Sr0.2MnO3 cathode on Y2O3-ZrO2 and Gd2O3-CeO2 electrolytes of solid oxide fuel cells

The establishment of intimate electrode/electrolyte interface is very important in solid oxide fuel cells (SOFCs), because it plays a critical role in the overall cell performance and durability. In this study, Mn segregation and interface formation between directly assembled La0.8Sr0.2MnO3 (LSM) electrode and yttrium-stabilized zirconia (YSZ) or gadolinium-doped ceria (GDC) electrolytes are studied using combined focused ion beam and scanning transmission electron microscopy (FIB-STEM). In the case of LSM/YSZ and LSM/GDC electrodes, a significant reduction in the electrode ohmic resistance is observed after cathodic polarization at 900 °C and 500 mA cm−2, indicating the formation of an intimate interface. However, LSM particles start to disintegrate at the electrode/electrolyte interface with the increase of polarization time in the case of LSM/YSZ electrode. On the other hand, the LSM/GDC interface is very stable with negligible microstructure change at the interface. Mn segregation from the LSM perovskite structure is identified under the influence of polarization in both LSM/YSZ and LSM/GDC electrodes. The results demonstrate that nature of the electrolyte plays a critical role in the electrochemical activity, microstructure, morphology and stability of LSM/electrolyte interface under SOFC operation conditions.

Mechanism of chromium poisoning the conventional cathode material for solid oxide fuel cells

Chromium poisoning the La0.875Sr0.125MnO3 (LSM) cathode for solid oxide fuel cells is a critical issue that can strongly affect the stability. In this study, we evaluate the temperature distribution in a SOFC based on a 3D model and then combine conductivity test and material computation to reveal the effects of chromium in SUS430 stainless steels on LSM conductivities. The starch concentration in LSM pellets and the applied pressure on the contact with interconnect materials show close relationships with the chromium poisoning behavior. The density functional theory (DFT) computing results indicate that chromium atoms preferably adsorb on the MnO2-terminated and La (Sr)-O-terminated (001) surfaces. The resulting conclusions are expected to deeply understand mechanism of chromium deactivating conventional cathodes at some typical operational conditions, and offer crucial information to optimize the structure to avoid the poisoning effect.

Enhanced performance of La0.8Sr0.2MnO3 cathode for solid oxide fuel cells by co-infiltration of metal and ceramic precursors

The electrochemical performance of a La0.8Sr0.2MnO3 (LSM) cathode electrode of solid oxide fuel cells (SOFCs) was promoted by the infiltration of metallic (Ag) and ceramic (La0.8Sr0.2FeO3 (LSF), CeO2) nano-catalysts. Electrochemical and microstructural techniques were used to investigate the effects of the addition of the infiltrated materials. The SEM observations showed that a well-dispersed arrangement of catalyst nano-particles is formed on the micron-sized LSM backbone. Electrochemical impedance spectroscopy (EIS) along with the analysis of distribution of relaxation time (DRT) and polarization measurement were conducted using a three electrode configuration setup. The EIS results revealed that the effect of the Ag nano-catalyst in lowering the polarization resistance is more sensible at lower temperatures, whereas LSF has more impact on the reduction of polarization resistance at higher temperatures. The best performance enhancement was achieved by the co-infiltration of Ag-ceria into the LSM electrode. The co-infiltration of Ag and ceria reduced the polarization resistance of the electrode to 2.5% of that for the pure LSM electrode. Furthermore, the infiltration of Ag solution reduced the electrode overpotential by about 114% at 700 °C.

Organic acids as electrostatic dispersing agents to prepare high quality particulate thin film

A simple electrophoretic method is developed for the fabrication of high quality electrolyte film on NiO-YSZ anode substrate for solid oxide fuel cell (SOFC) application. Aromatic carboxylic acids viz. benzoic acid and trimellitic acid have been explored as electrostatic stabilizer to prepare yttria stabilized zirconia (8YSZ) suspensions in isopropanol medium. Systematic studies on different suspension properties and deposition kinetics are carried out for each stabilizing agent to optimize the suspension chemistries and deposition conditions. Successful cathodic deposition has been achieved on polymer coated NiO-YSZ anode substrate using both benzoic acid and trimellitic acid as charging agents. Upon co-firing at 1400 °C, these films resulted in well-adhered dense YSZ coating (thickness: 7–12 μm) on the porous anode substrate. SOFC coupon cells are then fabricated by screen-printing La0.65Sr0.3MnO3 cathode layer on the top of the electrolyte. Maximum current densities as obtained from these single cells vary in the range of 1.3–1.6 A/cm2 for a cell voltage of 0.7 at 800 °C.

Improved polarization behaviour of nanostructured La0.65Sr0.3MnO3 cathode with engineered morphology

We report a simple synthesis of La0.65Sr0.3MnO3 nanorods (LSM-R) through hydrothermal reaction followed by calcination at high temperature (700–850 °C). Thermogravimetric analysis and XRD study reveals that 850 °C is adequate for phase pure LSM-R formation. The microstructure of the powder has been clinically studied using FESEM and TEM. It is observed that the intermediate hydrothermal treatment plays key role in formation of such nanorods. Different bulk properties of LSM-R like sinteractivity, CTE, density, electrical conductivity etc. have been comprehensively studied. A maximum electrical conductivity of around 250 S/cm at 800 °C is obtained when LSM-R specimen is sintered at 1200 °C/2 h. The cathodic polarization of such LSM-R is measured using impedance analysis. It is observed that polarization value initially decreases attains minimum and then starts to increase with increase in cathode sintering temperature and dwelling time. A minimum cathodic polarization value of 0.32 Ω/cm2 at 800 °C is obtained at an optimized cathode sintering condition of 1000 °C/2 h.

(Invited) The Effect of (La,Sr)MnO3 Cathode Surface Termination on Its Electronic Structure

La1-xSrxMnO3 (LSM) was one of the first perovskites used as SOFC cathode material. Its (001) surface has two possible terminations, LaSrO and MnO2, with quite different properties and oxygen reduction efficiencies. To avoid effects of surface polarity and the dipole moment across the material, symmetric non-stoichiometric slabs are commonly used in theoretical calculations with identical terminating planes on its both sides. We analyzed the dependence of the electronic structure (density of states) and charge distribution (effective atomic charges and chemical bond covalency) on the slab termination and Mn ion oxidation state (controlled by the Sr content and slab nonstoichiometry).

(Invited) The Effect of (La,Sr)MnO3 Cathode Surface Termination on Its Electronic Structure

La1-xSrxMnO3 (LSM) was one of the first perovskites employed as SOFC cathode material and is still used in the form of porous composites with the respective electrolyte [1]. In our previous study [2], we analyzed oxygen adsorption, dissociation and migration on the (001) MnO2-terminated LM surface. In pure LaMnO3, the MnO2 (001) termination was found to be the energetically most stable, however with an increase of Sr doping, the (La,Sr)O termination is predicted to become even more favorable thermodynamically [3]. In this talk, we discuss and compare the results of first principles calculations on the elementary steps (oxygen vacancy formation, O2 molecule and O atom adsorption) of the oxygen reduction reaction on (La,Sr)MnO3 on the two (001) polar terminations – (La,Sr)O and MnO2. The LSM slab calculations were performed using the plane wave VASP computer code with GGA exchange correlation functionals. Properties of oxygen vacancies in different planes from the surface were analyzed. The vacancy formation energy on the MnO2 terminated surface is smaller than that in bulk. In contrast, the vacancy energy on the (La,Sr)O termination is larger, thus strongly reducing the surface vacancy concentration. Our approach allows for a clear separation of the two distinct effects -- different surface terminations and slab cation stoichiometry (ratio of a number of (La,Sr) ions to Mn that affects the average Mn oxidation state). It is found that oxygen vacancy formation energy in the bulk (slab center) is almost independent of the Mn oxidation state in the region +2.6 to +3.25, whereas it is monotonically decreasing on both surfaces. This surface-to-bulk discrepancy will be discussed. The oxygen atom adsorption energy on the (La,Sr)O termination considerably exceeds that on the MnO2 termination. As a result, the equilibrium oxygen adsorbate concentration was found to be about two orders of magnitude larger for the (La,Sr)O termination, but on the other hand, the surface oxygen vacancy concentration is smaller by nearly six orders of magnitude. Therefore, the oxygen reduction rate on (La,Sr)O termination is expected to be significantly lower than on the MnO2 termination. [1]. M. Kuklja, E.A. Kotomin, R. Merkle, Yu.A. Mastrikov, J. Maier, PCCP 15, 5443 (2013). [2]. Yu.A. Mastrikov, R. Merkle, E. Heifets, E. A. Kotomin, J. Maier, J. Phys. Chem. C 114, 3017 (2010). [3]. S. Piskunov, E. Heifets, T. Jacob, E. A. Kotomin, E. Spohr, Phys. Rev.B 78, 121406 (2008).

Placement of Reference Electrode, Electrolyte Thickness and Three-Electrode Cell Configuration in Solid Oxide Fuel Cells: A Brief Review and Update on Experimental Approach

Cell configuration and placement of reference electrode (RE) have been a subject of intensive interests to the solid oxide fuel cells (SOFCs) communities. Here, the relationship between the position of RE, electrolyte thickness, electrode/electrolyte contact and reliability of 3-electrode cell configuration in electrode polarization and resistance separation is briefly reviewed with particular emphasis on the experimental approach. Numerous modelling studies show that distortion to the electrochemical impedance measurement of electrode reactions on thin electrolyte cells is not avoidable due to the misalignment of working and counter electrodes (WE and CE) and the differences in their electrochemical characteristics. This has been verified experimentally that the asymmetric contact at the electrode/electrolyte interface can cause the shift of equipotential line/surface away from the electrolyte region, leading to the significant distortion in the polarization measurements. However, the distortion effect of misalignment on the equipotential line/surface depends strongly on the electrolyte thickness. In the case of SOFCs with model La0.8Sr0.2MnO3 cathode and Ni-yttria-stabilized zirconia (Ni-YSZ) cermet anode, the threshold for YSZ electrolyte thickness with equal partitioning of the cell resistance is ∼250 μm. In conclusion, for reliable and accurate polarization and impedance measurements in electrolyte-supported cells, it is suggested that minimum YSZ electrolyte thickness should be 250 μm for plate cells with electrode areas of ∼10 cm2 and 500 μm for button cells with electrode areas less than 1 cm2 for symmetric 3-electrode cell configurations with RE positioned on the inactive surface of electrolyte.

A FIB-STEM Study of La0.8Sr0.2MnO3 Cathode and Y2O3-ZrO2/Gd2O3-CeO2 Electrolyte Interfaces of Solid Oxide Fuel Cells

The interfaces between cathode and electrolyte in solid oxide fuel cells (SOFCs) play a critical role in the overall performance and durability, and are generally formed by pre-sintering at high temperatures, e.g., ∼1150°C in the case of La0.8Sr0.2MnO3 (LSM) cathodes. Here the interface between LSM and yttria-stabilized zirconia (YSZ) or Gd-doped ceria (GDC) electrolytes formed under high temperature sintering is studied using Focused Ion Beam and Scanning Transmission Electron Microscope (FIB-STEM) techniques. In the case of LSM/YSZ interface, there is a significant cation interdiffusion, particularly Mn2+ into YSZ electrolyte in the convex contact ring region and Mn, La and Y cation diffusion along the grain boundary of YSZ electrolyte also occurs. For LSM/GDC interface, no cation interdiffusion was observed. The results indicate the formation of semi-coherent interface, i.e., an atom-by-atom matching only exists locally in regions along the interface, but orientation relationship and lattice mismatch factor between electrode and electrolyte crystallographic planes at the LSM/YSZ and LSM/GDC interfaces vary significantly. Lattice disorientation and misfit of the crystallographic planes occur within a narrow region of 0.10–0.5 nm wide with no amorphous or solid solution formation. The results demonstrate that cation interdiffusion is not an essential requirement for the formation of heterointerfaces for LSM electrode, and disorientation and dislocation of the crystallographic planes at the interface does not impede the oxygen diffusion and incorporation process for the O2 reduction reaction.