Degradation Of Cell Performance Research Articles

An asymmetric membrane electrode assembly for high-performance proton exchange membrane fuel cells

The membrane electrode assembly (MEA) is a critical part of proton exchange membrane fuel cells (PEMFCs) and has a significant impact on their performance. A novel preparation method of MEA is proposed in this work to inhibit the swelling and deformation of the proton exchange membrane (PEM) during MEA preparation and improve the interface between the PEM and cathode catalyst layer (CL). Using this novel fabrication method, an asymmetric MEA is prepared, where the anode and cathode parts are fabricated separately and then integrated by a hot-pressing process. The cathode part is prepared by covering the gas diffusion electrode (GDE) onto a layer of a perfluorosulfonic acid dispersion to form a membrane-coated electrode according to a wet-contact interface design, thereby ensuring a tight and concave-convex PEM/CL interface on the cathode. The anode part is prepared by spraying the CL onto a commercial PEM with a substrate to form a CL-coated PEM. An MEA was also prepared according to the traditional catalyst-coated membrane (CCM) method for comparison. The asymmetric MEA based on the new manufacturing process performs better than the traditional CCM-type MEA under the same PEM thickness prerequisite. The peak power densities of the asymmetric MEA are verified to be 18% (H2/air) and 31% (H2/O2) higher than conventional CCM-type MEA. In addition, the asymmetric MEA shows less cell performance degradation after 3000 dry/wet test cycles than the CCM-type MEA.

Effects of neutron radiation on the key component cells of upright metamorphic four-junction (UMM4J) solar cells

In this study, the bandgap of the top three junctions of the UMM4J solar cell was optimized based on the spectral matching principle. Three materials, namely AlGaInP (1.957 eV), AlInGaAs (1.495 eV), and InGaAs (1.171 eV), were selected as the materials for the top three sub-cells. The component cells were fabricated using metal organic chemical vapor deposition (MOCVD) to verify their radiation resistance performance. Neutron irradiation with an equivalent energy of 1 MeV and a fluence of 6 × 1013 cm−2 was used to evaluate the end-of-life performance. The light current-voltage (LIV) and external quantum efficiency (EQE) results reveal that the AlGaInP (1.957 eV) component cells demonstrate superior radiation resistance performance, while the InGaAs (1.171 eV) component cells exhibit the poorest radiation resistance performance. After ensuring a sufficient margin of degradation for the InGaAs (1.171 eV) sub-cells, the AlInGaAs (1.495 eV) component cells serve as the current-limiting junction before and after radiation, resulting in an enhanced radiation hardness of the UMM4J solar cell. Furthermore, deep level transient spectroscopy (DLTS) was employed to directly assess the radiation-induced defects of the three-component cells. The degradation of solar cell performance primarily stems from the defects that induce Shockley-Read-Hall (SRH) recombination.

Effects of different interface on the stability of hybrid heterojunction solar cells

With the rapid increase in efficiency of organic-inorganic hybrid solar cells of Si-poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), their poor stability has become an important factor limiting its further development. Here, we demonstrate that the moisture in the air is the main cause for the performance degradation of the hybrid heterojunction solar cells (HHSCs) and innovatively discovered the effect of the Ag electrodes on the degradation of HHSCs. When exposed to air, the growth of the thin oxide layer on the interface of n-Si/PEDOT:PSS and the formation of silver sulfide (Ag2S) on the Ag/PEDOT:PSS interface together caused the increase in the series resistance (Rs) of the HHSCs. The increase in Rs decreases the fill factor (FF) of the HHSCs and thus leads to the degradation of the cell performance.

Microstructural Insights into Performance Loss of High-Voltage Spinel Cathodes for Lithium-ion Batteries.

Spinel-structured LiNix Mn2-x O4 (LNMO), with low-cost earth-abundant constituents, is a promising high-voltage cathode material for lithium-ion batteries. Even though extensive electrochemical investigations have been conducted on these materials, few studies have explored correlations between their loss in performance and associated changes in microstructure. Here, down to the atomic scale, the structural evolution of these materials is investigated upon the progressive cycling of lithium-ion cells. Transgranular cracking is revealed to be a key feature during cycling; this cracking is initiated at the particle surface and leads to the penetration of electrolytes along the crack path, thereby increasing particle exposure to the electrolyte. The lattice structure on the crack surface shows spatial variances, featuring a top layer of rock-salt, a sublayer of a Mn3 O4 -like arrangement, and then a mixed-cation region adjacent to the bulk lattice. The transgranular cracking, along with the emergence of local lattice distortion, becomes more evident with extended cycling. Further, phase transformation at primary particle surfaces and void formation through vacancy condensation is found in the cycled samples. All these features collectively contribute to the performance degradation of the battery cells during electrochemical cycling.

Performance degradation prediction method of PEM fuel cells using bidirectional long short-term memory neural network based on Bayesian optimization

Proton exchange membrane (PEM) fuel cell is the core equipment that can directly convert hydrogen energy into electricity. In the process of long-term operation, due to the aging of membrane electrode assembly and other components, the fuel cell performance gradually deteriorates. The voltage prediction of fuel cells is very important for performance and lifetime optimization. Long short-term memory neural network is one of the widely used prediction methods. Based on the prediction method of bidirectional long short-term memory neural network, the hyperparameters of the neural network model by Bayesian optimization algorithm is optimized to improve the accuracy of fuel cell performance degradation prediction. When the sampling time interval is 25 min and the training set is 45 %, the root mean square error and the average absolute percentage error of the prediction results is reduced to 6.3 mV and 0.1245 %, respectively. Moreover, by analyzing the influence of different sampling time intervals and training set proportion on the prediction results, a data set that takes into accounts both efficiency and accuracy is obtained. The proposed method based on Bayesian optimization can achieve more accurate performance degradation prediction.

Phase-Field Modelling of Microstructure Evolution in Solid Oxide Cells

The performance degradation of Solid Oxide Cells (SOC) caused by microstructure evolution limits the SOC’s lifetime. Long-term testing combined with post-mortem characterization is one common approach to clarify degradation mechanisms and develop counter-acting measures, but this is associated with extensive amount of experimental work and long research time. Instead, many researchers have devoted their efforts to investigating degradation using computational methods. The phase-field model has been utilized in the SOC research to illustrate the microstructure evolution during long-term operation from micron to millimeter scale, with the possibility of taking into account the mechanical properties as well. In this article, the principle of the phase-field method and different models are introduced first, followed by examples published in literature on phase-field modeling of various degradation phenomena in SOCs. Finally, possible strategies coupling modelling and experimental research in optimizing SOC performance and microstructure are discussed.

Understanding the process of carbon corrosion and its impact on performance degradation during simulated start-stop operations for the proton exchange membrane fuel cell

There remains a need for a thorough understanding of the process of carbon corrosion in proton exchange membrane fuel cell and its impact on performance degradation so that appropriate preventive measures against carbon corrosion can be implemented. In this study, we examined the carbon corrosion in detail during simulated start-stop cycles. Using double-layer capacitance as an indicator, we tracked the transformations of electrode structure and surface properties. The impact of carbon corrosion on the performance degradation was analyzed via voltage loss breakdown based on the H2/air polarization curve. Ex-situ characterization techniques were conducted to monitor the change of the surface chemical properties and microstructures of electrode. The results show that carbon corrosion and cell performance degradation proceeded in three stages during simulated start-stop cycles. Within 150 cycles (Stage 1), the cell overpotential increased slightly, which was due to the increase in the ohmic and gas diffusion medium mass transfer overpotential rather than the electrochemical area loss. After 600 cycles (Stage 2), significant electrode degradation occurred and electrode thickness was reduced to less than its half. As a result, the cell overpotential increased dramatically (by 35.8% at 0.55 A cm−2), which is mainly attributed to the increase of mass transfer overpotential. Eventually (Stage 3), the electrode structure was stabilized after all the surface defects and amorphous carbon were removed. Among these three stages, Stage 2 is the critical stage that causes the major degradation of cell performance.

Prediction of fuel cell performance degradation using a combined approach of machine learning and impedance spectroscopy

Accurate prediction of performance degradation in complex systems such as solid oxide fuel cells is crucial for expediting technological advancements. However, significant challenges still persist due to limited comprehension of degradation mechanisms and difficulties in acquiring in-situ features. In this study, we propose an effective approach that integrates long short-term memory (LSTM) neural network and dynamic electrochemical impedance spectroscopy (DEIS). This integrated approach enables precise prediction of future evolutions in both current-voltage and EIS features using historical testing data, without prior knowledge of degradation mechanisms. For short-term predictions spanning hundreds of hours, our approach achieves a prediction accuracy exceeding 0.99, showcasing promising prospects for diagnostic applications. Additionally, for long-term predictions spanning thousands of hours, we quantitatively determine the significance of each degradation mechanism, which is crucial for enhancing cell durability. Moreover, our proposed approach demonstrates satisfactory predictive ability in both time and frequency domains, offering the potential to reduce EIS testing time by more than half.

Durability of advanced low temperature lithium compound electrode ceramic fuel cell for transportation

In recent years, a ceramic fuel cell with lithium compound such as Ni0·8Co0·15Al0·05LiO2 (NCAL) as its electrode is reduced in H2 to produce lithium compounds containing molten salt and diffused into oxide electrolyte to form an “oxide-lithium compounds molten salt” composite electrolyte with ultra-high ionic conductivity, which made the cell have remarkable low-temperature power generation performance. It is found that the dynamic migration of lithium compounds produced by NCAL anode in the cell with Ce0.9Gd0.1O2-δ (GDC) as electrolyte during the constant current durability test is the main reason for the cell performance degradation. In this paper, we found that adding different mass ratios of NaFeO2 to the GDC electrolyte to construct GDC/NaFeO2 composite electrolyte can significantly affect the durability of the cell. Under the constant current density test conditions of 550 °C, 0.2 A cm−2, the performance of the cell with GDC/NaFeO2 composite with a mass ratios of 8/2 as electrolyte maintained relatively good durability in the constant current test of 50 h. The characterization results show that the NaFeO2 reacts with lithium compounds such as LiOH to generate LiFeO2 and NaOH, and NaFeO2 is reduced to Fe and NaOH by H2. A proper amount of NaFeO2 in the GDC/NaFeO2 composite electrolyte can produce sodium compound molten salt during the performance test to replace the role of lithium compound molten salt in improving the electrolyte ionic conductivity and the cell sealing, while slowing down the dynamic migration of the molten salt in the cell, thus improving the durability of the cell. The findings in this paper provide evidence and relevant theories for the performance degradation and durability improvement mechanism of this new type of lithium compound electrode ceramic fuel cell (LCCFCs), and propose new strategies for obtaining LCCFCs with better durability.

(Keynote) Inferring Degradation Modes from Battery Cycling Data

Battery research and development efforts necessarily involve large-scale experimental studies where cells are cycled under different conditions. Physics based models (PBM) of the type pioneered by John Newman, Ralph White, and others can play a key role in interpreting the resulting cycling data, and of course can be used to improve performance by modifications of cell design to optimize for a specific application. Long-term studies that characterize degradation in cell performance are an important type of cycling experiment that can be used to estimate useful battery life in a real-world application. The establishment of correlations between duty cycle and life is valuable and can inform battery management systems with a goal to extend life. During the course of such experiments, large data sets are created and we explore how a PBM might be used to infer the modes of cathode degradation. From degradation modes, mechanisms of degradations might be hypothesized, and this may lead to insights to further improve design and operation.Here, two PBM are reformulated to determine how cell parameters such as the amount of active cathode material appears to change with cycle number. Parameter estimation is applied to cycling data, and parameter changes are tracked for cycling data at different C-rates and different cutoff voltages. Parameter estimates are challenged with complementary experimental data for NMC and for a second cathode material that has been characterized extensively. The comparisons suggest that the methodology is effective and can provide physical insights into degradation mechanisms. To facilitate the “workflow,” inverse surrogate machine-learning techniques, in which simulation data are used for training neural networks to rapidly estimate parameters from experimental data, were utilized. To allow for both imperfect PBM and for non-ideal experimental data, data augmentation methods were introduced to improve the accuracy of parameter estimation algorithms. Examples are shown, with an emphasis on the physics over the mathematics and with an eye towards next steps.

Investigation on Reaction Mechanism in an SOFC Composite Cathode by Using Patterned Thin Film Electrodes

Introduction For the further commercial use of solid oxide fuel cells (SOFCs), operating at intermediate temperatures is demanded. When reducing the operating temperature, the degradation of cathodic activity occupies the largest part of degradation of cell performance. Therefore, to improve the performance of SOFCs at intermediate temperature, the activity of cathodic reaction has to be improved.The cathodic reaction of SOFCs proceeds not only at triple phase boundaries (TPBs) of electrode, electrolyte and gas but also at double phase boundaries (DPBs) of electrode and gas, when a mixed ionic and electronic conductor (MIEC) is used. Thus, increasing the DPB area is considered as the best way to improve the cathodic performance. However, it was reported that composite cathodes of MIEC and electrolyte particles showed better performance than simple MIEC cathodes, despite the DPB area decreased [1]. Possible reasons for such performance enhancement can be considered as (i) promotion of oxide ion diffusion and/or (ii) the increase of TPB concentration. However, the reason for the performance enhancement by making a composite cathode are not-well understood so far.In this study, we aimed to understand the cathodic reaction in a composite cathode of MIEC and electrolyte. For this purpose, we proposed new types of original model electrodes to simulate the reaction in actual porous composite electrodes. From electrochemical and the operando X-ray absorption spectroscopic measurements of the model electrodes, we tried to separately evaluate the contribution of ion diffusion and TPB reactions on the performance improvement of composite cathode. Methods When using a porous electrode, it is difficult to investigate the reaction mechanism because of its complicated microstructures. Our research group proposed so-called “patterned thin film model electrode” like Figure 1(a) as a model electrode to reproduce the reaction in a porous electrode while removing the influence of microstructure [2]. In this model electrode, the contact area of electrode and electrolyte was limited by partially inserting an insulating layer, and thus the reaction distribution was formed in the electrode as a function of the distance from the electrode/electrolyte interface.In this study, we proposed two new types of model electrodes as Figure 1(b) and 1(c) to simulate the porous composite electrode. In the patterned composite electrode (b), an electrolyte layer was inserted between the electrode and insulator. On the other hand, in the patterned composite electrode (c), a part of electrode was removed to introduce TPBs. From the difference between the model electrodes (a) and (b), the contribution of oxide ion diffusion in composite electrode was estimated. From the difference between the model electrodes (b) and (c) the contribution of the TPB reaction was estimated. In this study, we selected La0.6Sr0.4CoO3-δ (LSC64) as an MIEC cathode and Gd0.1Ce0.9O2-δ (GDC10) as an electrolyte material. Operando micro X-ray absorption spectroscopy (μ-XAS) measurement was conducted with the model electrodes to investigate the effective reaction area of the model electrode. In this measurement, a change in the oxygen chemical potential can be detected as a change of X-ray absorbance at the fixed energy near the Co K-edge accompanying a change of the oxidation state of Co in the LSC64 [3]. Thus, the reaction distribution could be evaluated by measuring the change of the X-ray absorbance due to the polarization as a function of the distance from the electrode/electrolyte interface. Results and Discussion Figure 2 shows the results of μ-XAS measurement at 973 K under 1 bar O2 with cathodic polarization. The area where the ratio of absorbance is larger than 1 corresponds to the area where the oxygen chemical potential is changed due to the polarization, i.e. the effective reaction area. The reaction area of the model electrode (b) was longer than that of the model electrode (a). This suggested oxide ion diffusion was improved by inserting the GDC layer. On the other hand, the reaction area of the model electrode (c) was longer than that of the model electrode (b). Generally, the reaction on the mixed conducting LSC64 electrode is supposed to proceed DPB reaction mainly. However, the longer reaction area of model electrode (c) indicated that the contribution of TPB reaction was also significant in the LSC64 composite electrode. As a conclusion, both promotion of oxide diffusion and the increase of TPB effective for the enhancement of the cathodic reaction in MIEC composite electrode.[1] Y. T. Kim, et al., Solid State Ionics, 309, 77-85 (2017).[2] K. Amezawa, et al., ECS transactions, 62(2), 129-135 (2015).[3] Y. Orikasa, et al., Journal of Physical Chemistry C, 115, 16433–16438 (2011). Figure 1

Mathematical Modeling of the Performance-Degradation Mechanisms of Cation-Contaminated Proton-Exchange-Membrane Water Electrolysis

The role of hydrogen as a commercial energy carrier is dependent on the development of robust processes to convert hydrogen into usable electricity as well as produce hydrogen at large scales. Proton-exchange-membrane water electrolysis (PEMWE) is a leading technology with the potential to produce hydrogen at projected consumption rates. In PEMWE, water is electrochemically split into hydrogen and oxygen gas using a membrane—electrode assembly, which uses a membrane capable of transporting both water and protons. Reactant water containing cationic impurities have been observed to degrade cell performance. Thus, developing an understanding of the influence of cationic contaminants is important to developing mitigation and recovery strategies for PEMWE systems.In the current work, mathematical models were developed to provide insight into the mechanisms of performance degradation due to cationic contaminants. The models are non-isothermal continuum models that describe multi-phase porous flow, electrochemical reactions, and concentrated-species transport in both the gas membrane, and ionomer phases. Simulations were performed in steady-state and transient operational modes for various cationic species at several ionic concentrations. The calibration and fitting of the models were performed using experimental measurements performed by the National Renewable Energy Laboratory. The mathematical models suggest that gradients facilitate the adsorption of cationic contaminants in reactant water, which subsequently accumulate in the cathode catalyst layer, as shown in Figure 1(a), and inhibit the PEMWE hydrogen-evolution reaction (HER) that consume protons and electrons to produce hydrogen gas. The models suggest that protonic conductivity is not significantly affected by low-concentration cationic species, but access to the catalyst active sites in the cathode catalyst layer is severely impeded. As a result, the evolution of hydrogen then proceeds by an alkaline mechanism, where water and electrons combine to produce hydrogen gas and hydroxide ions. An interpolated polarization curve shown in Figure 1(b) suggests that cell operation at high current densities favor the alkaline HER reaction due to the lack of protons in the cathode catalyst layer.This research is supported by DOE Hydrogen and Fuel Cell Technologies Office, through the H2NEW Consortia. Figure 1

Rechargeable Silicon-Ion Batteries

Silicon (Si) is the second abundant material in nature and yet, despite its high abundance and ease of production, the possibility of using Si as an active multivalent rechargeable anode was never explored or reported. As a proof of concept, we will discuss in this talk a new rechargeable Si-ion cell, its design and architecture, enabling Si to be reversibly discharged at 1.1 V and charged at 1.5 V. Several discharge-charge cycles were achieved, utilizing heavy doped n-type Si wafer anodes, and hybrid based ionic liquid electrolytes. In addition, dissolved halides are functioning as conversion cathodes. Cell characterizations correlated the discharge and charge processes with the presence of dissolved fluoride and Si species in the electrolyte. The presence of appreciable fluoride species is crucial in both establishing surface activation and battery operation, and their depletion is directly linked to cell performance degradation. We will discuss Si ions deposition and dissolution mechanisms.

Demonstrating the absence of metal ion contamination in operando PEM fuel cells utilizing unmodified stainless steel bipolar plates

Using stainless steel as material for bipolar plates (BPPs) in proton exchange membrane fuel cells (PEMFCs) carries a perceived risk of corrosion and subsequent metal ion contamination of the membrane electrode assembly (MEA). However, assessments in literature on this hazard to PEMFC systems have been based on ex-situ corrosion studies, where general assumptions made on the BPP environment might not be a correct simulation of real on-site conditions. In this contribution, uncoated BPPs from stainless steel grades 304 L, 316 L and 904 L were subjected to in-situ hybrid endurance/stress testing to simulate realistic conditions in operating fuel cell systems and re-evaluate the need of additional corrosion protection. A post analysis of the plates showed no signs of surface dissolution on any of the tested samples and the concentration of iron in the MEA averaged 7 to 10 ppm for uncoated samples and 7 to 11 ppm for coated and graphitic reference tests, displaying a negligible amount of trace metals compared to critical thresholds found in literature. Contact resistance values were stable for all samples and observable changes in cell performance and voltage degradation was confirmed to be unrelated to the presence of uncoated bipolar plates. The combined effects of decoupling of bipolar plate surface potentials from electrode potentials and operational control of stable gas flow compositions to sustain stainless steel surface passivation, were identified as explanation for the experimentally observed corrosion resistance of uncoated stainless steel plates in PEMFCs.

Overview of Approaches to Increase the Electrochemical Activity of Conventional Perovskite Air Electrodes.

The progressive research trends in the development of low-cost, commercially competitive solid oxide fuel cells with reduced operating temperatures are closely linked to the search for new functional materials as well as technologies to improve the properties of established materials traditionally used in high-temperature devices. Significant efforts are being made to improve air electrodes, which significantly contribute to the degradation of cell performance due to low oxygen reduction reaction kinetics at reduced temperatures. The present review summarizes the basic information on the methods to improve the electrochemical performance of conventional air electrodes with perovskite structure, such as lanthanum strontium manganite (LSM) and lanthanum strontium cobaltite ferrite (LSCF), to make them suitable for application in second generation electrochemical cells operating at medium and low temperatures. In addition, the information presented in this review may serve as a background for further implementation of developed electrode modification technologies involving novel, recently investigated electrode materials.

Improving mass transfer in anion exchange membrane water electrolysis by ordered gas diffusion layer

For tight assembly electrochemical gas evolution devices, such as anion exchange membrane water electrolysis (AEMWE), bubbles blocking gas diffusion layer (GDL) channels is one of the key reasons for cell performance degradation under high current densities. To enhance mass transport in GDLs at high current densities, herein we report a 3D printed Ni GDL (GDL3D print) with straight-through pores and three-dimensional periodic structures. Due to its periodic structures and high hydrophilicity, GDL3D print is more conducive to the rapid escape of bubbles and timely replenishment of water, showing higher mass transfer efficiency and lower ohmic resistance. Therefore, compared with the commercial nickel foam (NF), GDL3D print exhibits better cell performance not only in 1 mol/L KOH solutions but also in pure-water-fed AEMWE, and the cell voltage of AEMWE using GDL3D print as the anode GDL is only 1.8 V at 1 A cm−2. This work provides a useful guidance for GDL design for tight assembly electrochemical gas evolution devices.

Anti-poisoning performance of flat-tube solid oxide fuel cell in high concentration [formula omitted]S environment

In this work, the anti-poisoning performance of flat-tube solid oxide fuel cells (FT-SOFCs) is investigated in high concentrations of H2S. The degradation rate of the cell is 0.52%/ h, 0.27%/ h and 0.305%/ h at 750 °C, when the concentration of H2S is 161 ppm, 182∼222 ppm and 226 ppm, respectively, and the performance can be restored by humidification of H2. The resistance to sulfur poisoning breaks through the limitation, proving the stability advantage of the flat-tube structure. Through energy dispersive spectrometer (EDS) and Raman spectrum analysis, it is found that the cell performance degradation under high concentration of H2S is mainly caused by the loss of metallic nickel caused by the migration and decomposition of nickel-sulfur compounds, which will reduce the active sites of H2 participating in the anode reaction. This study provides a reference for the application of flat-tube structure cells under high concentrations of H2S.

Investigation of the Electrode-Electrolyte Interfaces in Solid Oxide Cells

The interface between electrodes and electrolyte in a solid oxide cell (SOC) are critical locations for cell performance. These interfaces originate from the chemical interaction of two different materials during processing. Different mechanisms can degrade cell performance on the air and fuel side, which necessitates different approaches to mitigate these effects. Here, materials interaction during processing is discussed for selected materials on the air side of an SOC. A new approach to obtain barrier layers of doped ceria with submicron thickness is introduced, and it is confirmed that only the interdiffusion layer between ceria and zirconia is necessary to prevent the formation of SrZrO3. Furthermore, the effect of the microstructure of a GDC layer on the sintering of a perovskite air electrode in this layer is investigated. It is demonstrated that the morphology of the GDC layer has an impact on the quality of the interface between air electrode and barrier layer.

Effective Suppression of LSCF Air Electrode Degradation by Air Cleaning

The performance degradation of air electrodes in solid oxide cells is strongly affected by impurities such as sulfur dioxide. Filtration is a practical approach for proton-exchange membrane fuel cells with high air purity demands. This study aims to evaluate the applicability of such a filter consisting of specially modified activated carbons for the LSCF air electrode. Different air quality qualities were used to differentiate degradation mechanisms caused by ambient air impurities from the intrinsic aging of a cell. Analyzing the impedance spectra using a distribution of relaxation times (DRT) and a complex nonlinear least squares fit (CNLS) revealed a significant degradation rate in the first 360 hours. Filtering the air reduces the degradation rate significantly. A similar degradation of cell performance occurs in cleaned air as in synthetic air, indicating the ability of the filter material to prolong the lifetime of SOCs through the adsorption of gas impurities.

In-Situ Observation of Temperature Distribution on a Planar Type SOEC During Start-Stop Cycle Operation

It is important to establish various analytical methods for solid oxide electrolysis cells (SOECs) under practical operating conditions to improve their performance and to analyze their degradation phenomena. In-situ observation of temperature distribution on a planar-type SOEC enables to reveal the distributions of electrochemical reactions and the cell degradation over time. In this study, 600-hour operation tests under start-stop cycling and constant current loading conditions have conducted using a 5 cm × 5 cm planar-type cell to evaluate the SOEC electrochemical performance and to observe the cell surface by infrared camera. The effect of cell performance degradation on the temperature distribution during operation has been evaluated. As a result, it was found that the temperature distribution on the cell surface is affected by the gas flow and current distribution, and that the temperature distribution on the cell surface changes after long-term operation even with constant-current loading operation.