Cell Durability Research Articles

ICOS-expressing CAR-T cells mediate durable eradication of triple-negative breast cancer and metastasis

BackgroundThe failure of conventional therapies and the propensity for recurrence and metastasis make triple-negative breast cancer (TNBC) a formidable challenge with grim prognoses and diminished survival rates. Immunotherapy, including immune...

Ion-Mediated Molecular Bridging at Buried Interface Enhances Perovskite Solar Cell Durability.

Engineering heterointerfaces via molecular bridging has been crucial for achieving perovskite solar cells (PSCs) featuring optimal power conversion efficiencies (PCEs) and environmental durability. However, the challenge remains in ensuring interfacial mechanical reliability to enhance the long-term durability of PSCs. Herein, an ion-mediated molecular bridging strategy is intentionally exploited to improve the mechanical integrity between the perovskite bottom and electron-transport layers (ETLs) through balancing interfacial toughness and strength. As a demonstration of the concept, a zwitterionic guanylurea phosphate additive is preburied onto the SnO2 ETL, in which the guanylurea with bifacial NH2 groups servers as a molecular bridge connecting the perovskite and ETL through electrostatic coupling, while the phosphate can interact with charged species at the heterointerface to strengthen the mechanical contact. Benefiting from the robust heterointerfaces, the mechanical durability of flexible PSCs is significantly enhanced, retaining 91.3% of the original efficiency following 6000 bending cycles (bending radius = 3 mm). Additionally, the enhanced mechanical integrity at the buried interface also benefits the charge transfer and chemical stability in rigid PSCs, contributing to PCEs of over 25% as well as thermal stability with T86 of 1200 h under aging at 85 °C.

Performance prediction and enhancement strategy of a new proton exchange membrane fuel cell-hydrophilic modified tubular still hybrid system

The abundant low-grade waste heat generation in proton exchange membrane fuel cell (PEMFC) not only leads to energy wasting but also degrades the cell durability. Herein, an innovative hybrid system model that integrates PEMFC with a hydrophilic modified tubular still (HMTS) is developed, aiming to remove and harness the waste heat for extra freshwater production. Based on thermodynamic and electrochemical theories and considering major irreversible losses within the system, the model is formulated to obtain the performance metrics. Computational results demonstrate that the hybrid system outperforms the independent PEMFC, exhibiting a 13.26 % increase in maximum output power density, as well as significant improvements in energy efficiency (6.49 %) and exergy efficiency (23.36 %). Exhaustive parametric studies show that raising the fuel cell's operation temperature and operation pressure and the wind velocity, or reducing the thermodynamic losses positively enhances the overall output performance. Nevertheless, enlarging the proton exchange membrane thickness, tube shell diameter, or length of the tube shell worsens the output performance. Local sensitivity analyses identify that the thickness of proton exchange membrane is the most sensitive factor affecting the output performance. These results are helpful for optimally designing and running a high-efficient system.

Correlating Catalyst Growth with Liquid Water Distribution in Polymer Electrolyte Fuel Cells.

This study investigates the impact of liquid water distribution in a polymer electrolyte fuel cell (PEFC) on the spatially heterogeneous platinum (Pt) catalyst degradation. The membrane electrode assemblies (MEAs) are aged using accelerated stress tests (ASTs) in varied cathode gas environments (N2 and air) to instigate Pt catalyst degradation. The study employs high-resolution neutron imaging and synchrotron micro-X-ray diffraction (micro-XRD) to map liquid water distribution and Pt particle size, respectively. Neutron radiographs reveal liquid water accumulation primarily within the diffusion media, especially under flow field lands, due to thermal resistance differences between channels and lands. Aged MEAs exhibit increased water retention, likely due to increased hydrophilicity of the diffusion media with aging. Synchrotron micro-XRD maps unveil significant heterogeneity in Pt particle size distribution in the aged MEAs, correlated with preferential liquid water accumulation under flow field lands. This study highlights the critical role of flow field design and water distribution in catalyst degradation, underscoring the need for innovative strategies to enhance fuel cell durability and performance.

Water electrolysis using fluorine-free, reinforced sulfo-phenylated polyphenylene membranes

Fluorinated proton-exchange membranes (PEMs), such as Nafion™, which is the current state-of-the-art polymer, present environmental challenges, driving the need for more sustainable alternatives for proton-exchange membrane water electrolysis (PEMWE) systems. However, fluorine-free membranes like sulfo-phenylated polyphenylene biphenyl (sPPB-50) often suffer from mechanical instability, excessive swelling, and limited cell durability, which hinder their practical applications. This study explores reinforced fluorine-free sulfo-phenylated polyphenylene membranes (Pemion™) with thicknesses of 15 µm (Pemion-15) and 40 µm (Pemion-40) as a potential solution to these issues. Pemion membranes were compared with both sPPB-50 and Nafion™ 112 (N112), focusing on key properties such as water uptake, dimensional swelling, proton conductivity, and durability in PEMWE applications. The results show that Pemion-reinforced membranes exhibit good performance for PEMWE allowing high current densities at lower voltages. Pemion-40 exhibited a low hydrogen gas crossover compared to sPPB-50 and N112. Under a constant current of 1 A cm−2, Pemion-40 exhibited a voltage loss rate of 1.46 mV h−1 over 100 h of operation. This study highlights the importance of structural reinforcement in enhancing the stability and efficiency of fluorine-free membranes, providing a promising route for sustainable alternatives in PEMWE systems.

The Impact of Substrate Temperature on the Adhesion Strength of Electroplated Copper on an Al-Doped ZnO/Si System.

This research, which involved a comprehensive methodology, including depositing electroplated copper on a copper seed layer and Al-doped ZnO (AZO) thin films on textured silicon substrates using DC magnetron sputtering with varying substrate heating, has yielded significant findings. The study thoroughly investigated the effects of substrate temperature (Ts) on copper adhesion strength and morphology using the peel force test and electron microscopy. The peel force test was conducted at angles of 90°, 135°, and 180°. The average adhesion strength was about 0.2 N/mm for the samples without substrate heating. For the samples with substrate heating at 100 °C, the average peeling force of the electroplated copper film was about 1 N/mm. The average peeling force increased to 1.5 N/mm as the substrate heating temperature increased to 200 °C. The surface roughness increases as the annealing temperature of the Cu/AZO/Si sample increases. These findings not only provide a reliable and robust method for applying AZO transparent conductive films onto silicon solar cells but also underscore its potential to significantly enhance the efficiency and durability of solar cells significantly, thereby instilling confidence in the field of solar cell technology.

Tunnel silicon oxynitride phase transformation for n-type polysilicon passivating contacts in crystalline silicon solar cells

The study investigates the fabrication and characterization of tunnel oxynitride (TON) layers produced using Plasma-Enhanced Chemical Vapor Deposition (PECVD) at different pressure and power variations. The aim is to explore TON layers as potential substitutes for conventional SiO2 in Tunnel Oxide Passivated Contact (TOPCon) solar cells. Foe this purpose, an effective oxide thickness (EOT) of 1.1–1.2 nm and 1.5–1.6 nm has been achieved by treating the TON samples with NH3 and N2 gas plasma, respectively. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed critical variations in the chemical bonding within TON layers, which exhibit different properties based on the deposition conditions. The presence of nitrogen-nitrogen and nitrogen–hydrogen bonds is prominently influenced by changes in the PECVD parameters, directly affecting the layer’s optical and electronic properties. Notably, the presence of hydroxyl (O–H) and amino (NH2) groups within the TON structure suggests an improvement in surface passivation, essential for optimizing solar cell performance and durability. A lifetime of 737 and 823 μs has been recorded for N2 and NH3 samples, compared to the NAOS 710 μs reference sample. NH3 plasma-treated samples show an improved iVoc of 736 mV, indicating better phase transformation and passivation quality than N2 plasma treatment and the NAOS reference sample.

Highly active and stable oxygen electrode PrBaCo2O5+δ-Ba2CoWO6 enabled by In Situ formed misfit dislocation interface for reversible solid oxide cell

The energy conversion efficiency and durability of the reversible solid oxide cell (RSOC) is restricted by the development of highly active and stable oxygen electrode. Herein, an in-situ formed composite PrBaCo2O5+δ-Ba2CoWO6 oxygen electrode is proposed, which consists of a highly active A-site double perovskite (A-DP) phase and a stable B-site double perovskite (B-DP) phase. Misfit dislocation interface is formed between these two phases, exerting lattice tensile stress on the A-DP phase, which enhances catalytic activity and inhibits Ba segregation. Additionally, the B-DP phase suppresses lattice expansion of A-DP phase through the dislocation interface, thereby improving thermo-mechanical stability. Consequently, the composite electrode demonstrates a low polarization resistance of 0.056 Ω cm2 at 650 °C, impressive stability at 650 °C for 500 h in symmetrical cell tests, and excellent thermal-mechanical stability under 29 thermal cycles. A maximum power density of 0.75 W cm−2 and an electrolysis current density of 0.84 A cm−2 at 1.3 V were achieved at 650 °C by the composite electrode on a 260 μm-electrolyte supported cell configuration, which surpass most of the reported oxygen electrode materials. Furthermore, the cell exhibits excellent operational stability, with low degradation rates of 0.49 × 10−1 mV h−1 and 1.5 × 10−1 mV h−1 in fuel cell and electrolysis cell modes, respectively. This work offers an effective method for designing highly active and stable oxygen electrodes for RSOCs.

Investigation of the Effect of Initial Anode Structures on the Durability of Water Electrolysis Cells

Water electrolysis systems directly using renewable energy have been focused on this study. From our previous finding in the long-term accelerated voltage fluctuation test using actual wind power voltage fluctuations, increasing hydrophobicity and reducing gas stagnation within the anode catalyst layer were suggested. Then, controlling hydrophobic characters was considered in this study. Hydrophobic materials, such as polytetrafluoroethylene and polypyrrole, were chosen and added to the anode layers. As expected, the addition of 30% polytetrafluoroethylene improved hydrophobicity but also increased ohmic resistance, lowering IV performance. On the other hand, the use of polypyrrole was found to improve hydrophobicity while maintaining IV performance. However, the slight increase in activation and diffusion overvoltages was also observed, which was most likely owing to poor distribution of polypyrrole in the anode layer and possibly improved by adding a milling process.

Investigation of the Effect of Initial Anode Structures on the Durability of Water Electrolysis Cells

Water electrolysis systems directly using renewable energy have been focused on this study. From our previous finding in the long-term accelerated voltage fluctuation test using actual wind power voltage fluctuations, increasing hydrophobicity and reducing gas stagnation within the anode catalyst layer were suggested. Then, controlling hydrophobic characters was considered in this study. Hydrophobic materials, such as polytetrafluoroethylene and polypyrrole, were chosen and added to the anode layers. As expected, the addition of 30% polytetrafluoroethylene improved hydrophobicity but also increased ohmic resistance, lowering IV performance. On the other hand, the use of polypyrrole was found to improve hydrophobicity while maintaining IV performance. However, the slight increase in activation and diffusion overvoltages was also observed, which was most likely owing to poor distribution of polypyrrole in the anode layer and possibly improved by adding a milling process.

Investigation of the Durability of a Water Electrolysis Cell with Iridium Fiber Anode Against Voltage Fluctuations Simulating Wind Power

Durability of a water electrolysis cell against the voltage fluctuations is focused on in this study. An accelerated potential fluctuation test was performed for a newly developed MEA with Iridium fiber anode in our lab. In the first 40 sets of the test, no positive effect of the fiber structure was seen, and rather the fast current loss related to gas stagnation was observed. That was assumed to be owing to the coverage on inter-fiber pores by extra Nafion® ionomer. However, in the latter 40 sets, the expansion of the anode layer was confirmed by SEM images, and the rate of gas stagnation was decreased. Furthermore, the recovery of I-V performance after the rest period was sufficiently good, and almost no irreversible degradation was considered. Therefore, the Iridium fiber anode most likely has high durability against the increased internal pressure in the anode layer derived by stagnated gases.

Influence of the Clamping Force and the Formation of Liquid Water Along the Channel on the Local Diffusion Processes in PEMFCs

A novel measurement setup, technique, and segmented model are introduced to spatially resolve mass transport losses along the channel in a PEMFC. The newly designed segmented cell enables not only the measurement of local current and voltage data but also the capture of local temperature and compression levels. By extending the commonly used limiting current method, the local mass transport resistance is determined as a function of local operating parameters. The local current and temperature are directly measured, while the operating conditions along the channel such as pressure, oxygen fraction, and relative humidity are obtained empirically from a 1-D differential model. Leveraging both measured and empirically-based simulation results, this comprehensive approach facilitates the characterization of mass transport resistance distribution along the gas channel. The learnings from this study provide valuable insight into the optimization of channel and materials design for enhancing large active area fuel cell performance and durability.

Influence of the Clamping Force and the Formation of Liquid Water Along the Channel on the Local Diffusion Processes in PEMFCs

A novel measurement setup, technique, and segmented model are introduced to spatially resolve mass transport losses along the channel in a PEMFC. The newly designed segmented cell enables not only the measurement of local current and voltage data but also the capture of local temperature and compression levels. By extending the commonly used limiting current method, the local mass transport resistance is determined as a function of local operating parameters. The local current and temperature are directly measured, while the operating conditions along the channel such as pressure, oxygen fraction, and relative humidity are obtained empirically from a 1-D differential model. Leveraging both measured and empirically-based simulation results, this comprehensive approach facilitates the characterization of mass transport resistance distribution along the gas channel. The learnings from this study provide valuable insight into the optimization of channel and materials design for enhancing large active area fuel cell performance and durability.

Key Control Characteristics of Carbon Black Materials for Fuel Cells and Batteries for a Standardized Characterization of Surface Properties

AbstractCarbon Blacks (CBs) are primarily used in electrocatalysis as support materials for nanoparticulate electrocatalysts. In fuel cells, CBs, catalysts, and proton conductive polymers (ionomers) undergo a dispersion/homogenization process for electrode coating. The interactions between components in dispersion and the surface of CB particles are complex. The surface characteristics of CB particles impact slurry formulation, electrode coating, and the resulting electrode layer, affecting fuel cell and battery performance and durability. This study investigates commercially available CBs such as Vulcan XC72R, Ketjen Black EC‐300J, Ketjen Black EC‐600JD, and Super C65, focusing on application‐relevant key control characteristics (KCCs). The KCCs include physicochemical features like electrical conductivity (electron transport through the catalyst layer, CL), oxygen‐containing surface groups (hydrophilicity/phobicity of the CL, catalyst functionalization), surface basicity/acidity, ionomer adsorption, and particle dispersibility (catalyst ink stability). KCCs are determined by particle bulk electrical conductivity, Boehm titration (BT), isoelectric point (IEP), and Hansen solubility parameters (HSP). HSP, understood as similarity parameters for particles, indicate how nanoparticle surfaces interact with liquids during dispersion. The proposed KCCs serve as a starting point for characterizing CBs and guiding product design to obtain meaningful structure‐property relationships, essential for a successful energy transition.

A Facile Low Prevacuum Treatment to Enhance the Durability of Nonfullerene Organic Solar Cells

Herein, a straightforward vacuum‐assisted method is introduced to enhance the stability of nonfullerene organic solar cells (OSCs). The method, termed “prevacuum” involves subjecting the active layer (D18:Y6) to a low‐pressure vacuum (−1 bar) before thermal annealing at 100 °C. Compared to untreated devices, prevacuum‐treated OSCs exhibit a notable increase in power conversion efficiency from 13.71% to 14.90%. This enhancement is attributed to improved light absorption and charge extraction, as evidenced by external quantum efficiency measurements. Moreover, prevacuum treatment significantly improves device stability under operational conditions, with a 30% power loss occurring after 8.25 h compared to 4.5 h for untreated devices. This improvement is attributed to the removal of volatile components and impurities during the vacuum process, leading to a more hydrophobic and stable active layer. The study demonstrates the efficacy of prevacuum treatment as a simple and accessible method for enhancing the performance and longevity of OSCs, paving the way for their broader application in sustainable energy technologies.

Impact of PTQ11 polymer doping on the optoelectronic and structural properties of a CH3NH3PbI3 perovskite photovoltaic cell

At present, one of the most swiftly progressing domains in solar photovoltaics is perovskite-based solar cells. Chemical modification of perovskites with foreign atoms represents a potentially fruitful approach to customizing material characteristics with the aim of enhancing the functionality and durability of solar cells. In this study, we first documented the inverted structure of PTQ11 polymer-doped perovskite solar cells composed of CH3NH3PbI3 (MAPbI3) perovskite thin film. The findings indicate that the active layer morphology is enhanced through PTQ11 doping, leading to rapid suppression of photoluminescence and delayed carrier recombination. The XRD and Raman spectral analyses revealed the crystalline, single phase, tetragonal, and highly pure MAPbI3 thin film with the preferred (220) orientation. Energy gaps ranging from 1.596 eV to 1.577 eV and absorption coefficients exceeding 105 cm−1 were characteristics of the doped thin film, which varied with the doping concentration. A transition occurred on the perovskite film’s surface to form smooth, compressed pores measuring 1.63 µm in diameter. This modification potentially enhanced the photovoltaic performance by facilitating charge transport. With an open circuit voltage of 1.11 V, a power conversion efficiency (PCE) of 18.24 %, a short-circuit current density of 22.32 mA/cm2, and a fill factor of 73.65 %, the PTQ11-9 mg/mL sample constituted the solar cell device base. Hence, the findings suggest that the doping of PTQ11 polymer represents a potentially effective approach to improve the performance of perovskite solar cells.

Finite element modeling of the glass sealing process for solid oxide cell stacks

The sealing process for solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) stacks is a vital step in the assembly and manufacturing of these systems. The cell seal and stack seal serve to prevent leakage and the mixing of air with hydrogen and steam during operation. Good seals are critical for reporting accurate cell and stack performance and durability, as leaks can mask degradations and manifest as performance improvement. Predictive modeling of seal materials during sealing processes for SOFC and SOEC stacks has been largely unexplored and could provide design and manufacturing insights for these systems. In this work, finite element modeling was conducted to simulate the assembly and stack sealing of planar cells to capture the densification, viscous flow, and crystallization behavior of the G18 glass ceramic seal material during full scale stack fabrication. The Skorohod-Olevsky viscous sintering material model was implemented in the ANSYS finite element program and modified to account for crystallization effects to simulate the response of the G18 seal material. The effects of initial cell/stack curvature were captured via preliminary stack manufacturing simulations, and its influence on stack sealing quality was studied. Effects of compressive loading sequence and configuration were investigated.

Study on Attenuation Mechanism and Durability Improvement of Platinum-Carbon Catalysts for Proton Exchange Membrane Fuel Cells

The relationship between Pt particle size and activity and durability of Pt/C electrocatalysts on rotating disk electrodes is established and the results show that Pt/C electrocatalysts with particle size over 3.5 nm have excellent resistance to Pt particle decay and carbon corrosion. Further, the research results on the mechanism of Pt particle decay and carbon corrosion show that the Pt particle attenuation is composed of 80% Ostwald ripening and 20% particle agglomeration, and the carbon corrosion is affected by the catalytic action of Pt particles. Therefore, the above results show that regulating the Pt particle size to 3.5–4.0 nm can improve the durability of Pt/C electrocatalysts on RDE. To verify the accuracy of this conclusion and determine the optimal particle size range in practical application, single cells with 5 × 5 cm2 is assembled to evaluate the performance and durability of cathode Pt/C electrocatalysts under H2/air. The results show that cathode Pt/C electrocatalysts with particle size between 3.5 nm and 3.8 nm have high single cell performance (2.3 A cm−2@0.65 V) and durability (A loss of 15 mV@0.8 A cm−2 after 30000 cycles). These findings reveal the attenuation mechanism of Pt/C electrocatalysts and provide ideas for the development of high-durability Pt-based electrocatalysts for practical applications.

A CFD‐based manifold design methodology for large‐scale PEM fuel cell stacks

AbstractThe flow distribution issue is of significance to the fuel cell stack performance and durability, which herein is studied from a theoretical and practical level. The manifold flow fundamentals are clarified and the pressure‐reconstruction‐based principle to regulate flow distribution is revealed. The prerequisite and corequisite lie in the ratio of pressure drop between headers and the entire manifold, and the pressure recovery in the inlet header. Accordingly, a step‐by‐step manifold design methodology is proposed and further quantified by detailed and organized simulations. A desirable effect on flow uniformity is validated in large‐scale stacks consisting of 300 and 400 cells, and the values of flow uniformity index represented by coefficient of variation (CV) are 3.32% and 2.95%, respectively. Moreover, a novel wedge‐shaped layout of the intake header is proposed for further optimization. The corresponding CV values have notably declined to 1.36% and 1.29%, nearly 60% lower than the conventional rectangular counterparts.

Interfacial engineering of (Ce,Zr)O2 composite barrier layers for enhancing the durability of solid oxide fuel cells

The dense GdxCe1-xO2 (GDC) barrier layer can't prevent the diffusion of small amounts of Sr through grain boundaries. Recent studies indicate that the (Ce,Zr)O2 composite, placed between GDC and YSZ (Y2O3 stabilized ZrO2) electrolyte, can effectively suppress SrZrO3 formation. In this study, we successfully designed and prepared an anode-supported solid oxide fuel cell (SOFC) with a dense GDC/IDL (interdiffusion layer) composite barrier layer, demonstrates excellent inhibition of elemental diffusion through grain boundaries. Compared with the cell with a single dense GDC barrier layer, the cell with GDC/IDL composite barrier layer exhibits largely improved durability, with a two-fold decreased degradation rate of 2.7 %/kh, operated under constant current density of 400 mA/cm2 at 720 °C. The cell with GDC/IDL barrier layer presents decreased initial performances, with lager Rohm of 0.085 Ω cm2 than 0.075 Ω cm2, and smaller initial Pmax of 0.905 W/cm2 than 1.019 W/cm2 at 750 °C. However, the cell performance surpasses the cell with single GDC barrier after 230 h. Thus, we obtain a new strategy to achieve improved cell durability by sacrificing the cell's initial performance. The in-situ constructed continuous and dense GDC/IDL composite optimizes the electrolyte/cathode interface while maintaining decent electrochemical performance, providing a new horizon to design and prepare high performance and durable SOFCs.