Optimal Cell Performance Research Articles

Photogalvanics of the lactic acid reductant - Carmoisine A photosensitizer-CAPB surfactant electrolyte: An optimization, stability and illumination window size effect

The photogalvanic cells presented in this research work are energy devices having dual role of simultaneous solar power generation and storage. The study of photogalvanics of the Lactic acid reductant-Carmoisine A photosensitizer- Cocamidopropyl betaine (CAPB) surfactant-NaOH alkali has been done under artificial illumination for exploring a most suitable combination of photosensitizer, reductant and surfactant for further enhancing the solar harvesting efficiency. This combination of chemicals (Lactic acid-Carmoisine A-CAPB-NaOH) has shown remarkable improvement in the cell performance. The optimum conditions for cell have also been investigated for optimal cell performance. The electrical output of the cell has been found to depend on the cumulative effect of all cell fabrication variables. The observed power is of the order 1012.70 μW with efficiency 28.84 %. The electrical out-put of the photo-galvanic cells is found almost independent of the size of the illumination window. The initial power generated from the cell was ∼309.0 µW (taken as 100 %), and power at the end of 6th day was ∼0.0009 %. This long term study of the cell in post-illuminated dark conditions shows capacity of the cell to store and release the power over long period of time. Therefore, the Lactic acid reductant-Carmoisine A photosensitizer -CAPB surfactant combination is a good alternative for use in the fabrication of highly efficient photogalvanic cells.

Research on PbTiO3 nanoparticles optimized mesoporous layer for perovskite solar cells

Organic-inorganic hybrid perovskite solar cells have garnered significant attention due to their facile fabrication process and high photovoltaic conversion efficiency. The electron transport layer plays a crucial role in the carrier separation mechanism of perovskite solar cells, making it a focal point for enhancing cell performance. In this study, PbTiO3 was introduced into TiO2 mesoporous layers by modification and doping in order to optimize cell performance. Initially, the use of PbTiO3-modified mesoporous layers revealed issues such as non-uniform modification layers, low film coverage rates, and reduced light transmittance. These issues hindered the ability of PbTiO3 to facilitate carrier separation and resulting in suboptimal optimization effects. However, by utilizing PbTiO3-doped mesoporous layers for optimizing cell performance, we observed improved quality and higher light transmittance in the perovskite films. As a consequence of the improved carrier separation achieved by PbTiO3, the efficiency of the solar cell has been enhanced to 5.51%.

Analyzing the Effect of Electrolyte Quantity on the Aging of Lithium-Ion Batteries.

Despite a substantial impact on various economic and cell technology factors, the influence of electrolyte quantities is rarely addressed in research. This study examines the impact of varying electrolyte quantities on cell performance and aging processes using three different electrolytes: LP57 (1 M LiPF6 in ethylene carbonate:ethyl methyl carbonate (EC:EMC 3:7 w/w), LP572 (LP57+2 wt.% vinylene carbonate (VC)) and LP57 + absVC (18.351 mg VC). Comprehensive analytical post mortem investigations revealed that continuous excessive electrolyte decomposition determines the performance of cells using LP57, leading to enhanced irreversible lithium-ion loss and interphase thickening with increasing electrolyte volume. Impedance rise due to the growth of the interphase was also identified as the cause of degrading cell performance with rising amounts of LP572, attributed to an increasingly pronounced consumption of VC rather than electrolyte aging effects. By varying the electrolyte quantity while maintaining a constant amount VC within the cell system, the differences in cell performance were minimized, and observed deteriorating effects were suppressed. This study demonstrates the sensitive interdependence of electrolyte volume and additive concentration, practically affecting aging behavior. Comprehensively understanding the characteristics of each individual electrolyte component and tailoring the electrolytes to cell-specific cell properties proves to be crucial to optimize cell performance.

(Invited) Model-Based BMS for Current and Next-Generation Batteries

Fast charging is researched heavily for the widespread implementation of lithium-ion batteries for electric vehicles. However, charging at high currents accelerates several parasitic reactions that lead to the degradation of the cell, affecting its lifetime. These reactions lead to loss of lithium inventory, loss of active material, and increased impedance in the cell. Examples of these side reactions include the growth of the solid-electrolyte interphase (SEI) layer, transition metal dissolution and deposition, lithium plating, solvent oxidation, etc. These mechanisms degrade the cell and reduce its cycle life.Physics-based multi-scale battery models solve for equations that govern the charge and mass balances within the cell. Using these detailed mathematical models, it is possible to study material degradation mechanisms and predict their impact on capacity loss under several operating conditions. These models can be used to design new batteries with appropriate materials and design parameters suited for any given purpose.More critically, these models can be integrated with battery management systems (BMS) to control the cell’s performance. These models can further be used to design novel charging protocols that enable safe and optimal cell performance and suppress cell material degradation. The BMS monitors and maintains the voltage, current, and temperature and estimates the internal states of the cell. Model-based BMS algorithms require fast codes that can predict and estimate battery parameters in real-time and control the battery’s performance under different loads.Currently, the BMS implements equivalent circuit models that inadequately predict the cell’s performance for various conditions and design parameters. This talk presents the current efforts to move the models for BMS for current and next-generation batteries for single-cell to pack-level simulations. Figure 1

A comprehensive study on effective triple‐phase boundary density and its correlation with active anode thickness in solid oxide fuel cells

AbstractSolid oxide fuel cells (SOFCs) are highly promising devices for efficient and low‐emission energy conversion. The effective triple‐phase boundary (TPB) density refers to the fraction of percolated TPB density that effectively contributes to the current production during cell operation. This is one of the most fundamental and least understood aspects of the cell design and performance assessment. This study methodically investigates the effective TPB density, using a computational fluid dynamics model based on the TPB‐based kinetics and its correlation with the active anode thickness. Experimental data from previously published studies with varying thicknesses of anode functional layer and operating regimes are utilized to validate the model. The results of this study reaffirm that a significant fraction of the percolated TPB density in SOFCs remains unused during cell operation. This finding emphasizes the need to consider the effective TPB density for theoretical and experimental investigations focusing on optimizing cell performance. Furthermore, an inverse relationship is observed between the effective TPB density and the active anode thickness; a lower active anode thickness corresponds to a higher effective TPB density and vice versa. These findings contribute to advancing sustainable energy systems by guiding the development of more efficient SOFC designs and operational strategies that effectively utilize TPB sites.

Optimum Solar Cell Power Conversion Efficiency-Based Patterned Planar Solar Surface Morphology with Various Solar Cell Absorber Structures

This paper simulated the optimum solar cell power conversion efficiency-based planar solar surface morphology with various solar cell absorber structures. The spectral light intensity, reflected, absorbed, and transmission coefficients versus wavelength band spectrum varied from 300[Formula: see text]nm to 1300[Formula: see text]nm through the visible to near-infrared regions. The optimum solar cell performance parameters or key parameters are studied with different solar cell structure designs based on different surface contact and back contact layers. Cumulative generation current, cumulative electron–hole pair generation rate and electron–hole pair generation rate are clarified versus substrate depth for various solar cell structure designs. The absorbed current in substrate is optimized for various solar cell structure designs. Maximum power voltage and current are also optimized for the proposed solar cell structure design. The effective solar cell power efficiency is also demonstrated based on the optimized maximum power current and maximum power voltage.

The central role of magnesium in skeletal muscle: from myogenesis to performance.

A physiological concentration of magnesium (Mg) is essential for optimal skeletal muscle function. Indeed, Mg plays a crucial role during the differentiation process (myogenesis), in muscle fiber composition, muscle contraction and performance. This narrative review describes in detail the relevance of Mg in skeletal muscle, highlighting the importance of adequate Mg intake to ensure optimal skeletal muscle cell function and performance in individuals of all ages.

Study of KOH as alkali for enhancing performance of photo-galvanic cell in transparent cylindrical cell design

Photo-galvanic cells are liquid electrolyte-based dye-sensitized solar cells. Chemically, the dye/pigment photo-sensitizer, reductant, surfactant, and alkali materials are the main fabrication components of these cells. Most dye/pigment materials are more soluble and stable at high pH. The pH of Potassium hydroxide (an alkali of plant nutrient ‘potassium’ element) is very high. Therefore, Potassium hydroxide is supposed to be the best eco-friendly and effective alkali medium for photogalvanics. As far as alkali is concerned, NaOH has been exploited extensively in photo-galvanics. Although, the NaOH-based photo-galvanics show good electrical output, it is plagued with some drawbacks like shorter shelf life, high cost, unsafe for skin, low conductivity, low water solubility, etc. Therefore, in the present research, the KOH has been exploited as an alkali material for harvesting solar energy using the Sunset Yellow FCF dye sensitizer-Ascorbic acid reductant-CTAB surfactant cylindrical cell designed photo-galvanic system.In the present study, the observed optimum cell performance is as follows-open-circuit potential 777 mV, maximum current 25000 μA, short-circuit current 5600 μA, power 733.6 μW, fill factor 0.16, and efficiency is 19.77 % at pH 14.30. The Sunset Yellow FCF dye shows very high photostability and photo-absorption with KOH alkali. The power storage capacity is sufficiently robust, as the cell is capable of supplying power at its ∼36.16 % capacity after a very long time of 24 h. The KOH-Sunset Yellow FCF dye sensitizer-Ascorbic acid reductant-CTAB surfactant photo-galvanics in the present study show improved results over the reported results for the NaOH-Sunset Yellow FCF dye sensitizer-Ascorbic acid reductant-CTAB surfactant photo-galvanics. The reasons for the good photo-galvanics with KOH alkali may be attributed to some peculiar chemical and physical properties of KOH vis-à-vis the chemical and physical properties of NaOH.

Coin‐Shaped Carbon Prepared with Cerbera manghas Fibers via Multistage Carbonization and Activation for High‐Performance Symmetrical Supercapacitors

AbstractSupercapacitor energy storage devices and activated carbon (AC) manufacturing materials for producing high‐performance supercapacitors have received extensive attention from researchers. Biomass‐based AC has been extensively studied due to its environmental friendliness, abundant availability, porous structure, and high specific surface area. This work focuses on developing biomass‐based carbon electrodes derived from Cerbera manghas fiber (CMF) with variations in carbonization temperature to obtain optimum supercapacitor cell performance. The prepared CMF AC was characterized using energy dispersive X‐ray, Fourier transform infrared, X‐ray diffraction, scanning electron microscope, and nitrogen isothermal adsorption–desorption. CMF AC with the optimum carbonization temperature (CMF‐600) produced a fibrous structure with a lot of mesoporous so that the specific surface area and specific capacitance were high, namely, 721.495 m2 g−1 and 221 F g−1 at scan rate 1 mV s−1, respectively. The results of this study indicate that selecting the optimum temperature can enhance the performance of supercapacitor cells and make AC based on CMF biomass potential for cheap and efficient energy storage applications.

Enhancing the Performance of the Mesoporous TiO2 Film in Printed Perovskite Photovoltaics through High‐Speed Imaging and Ink Rheology Techniques

AbstractMesoscopic carbon‐based perovskite solar cells (C‐PSCs) have the potential to be manufactured at an industrial scale by utilizing screen‐printing, a simple, affordable, and commercially mature process. As such, many recent publications have focused on enhancing performance through modifying cell architecture and perovskite chemistries. This work examines how ink rheology can be tuned to optimize cell performance through reducing the occurrence of common print defects to create higher quality m‐TiO2 films. Inks with different solvent dilutions and rheological profiles are assessed using high‐speed imaging through the screen‐printing visualization (SPV) technique, to investigate the impact of the viscosity and elasticity on ink separation mechanisms. The resultant film quality and its influence on device performances are then assessed. Ink separation lengths are minimized, and the formation of filaments ceases during printing, leading to improved TiO2 film topography and homogenous infiltration of the perovskite precursor. Consequently, PCE is improved by over 10% of the original efficiency in cells and 224 cm2 active area modules due to enhanced Voc and FF. These results not only provide key insights into tailoring ink rheology, to achieve improved print homogeneity and higher performing cells, but also aid further work on enhancing the performance of other screen‐printed functional films.

Combination of multiple routes to enhance DSSC performance: Flower-like structure of SnO2 as photoanode and modification with Ag nanoparticle

SnO2 is an attractive photoanode material for dye-sensitized solar cells (DSSCs), but it has many drawbacks and needs to be modified. In this study, flower-like SnO2 particles are firstly prepared by a simple one-step hydrothermal synthesis method respectively, and the effect of hydrothermal reaction time on the growth of the particles is explored. The morphological and structural characterisation reveals that the flower-like particles have a larger specific surface area can provide more adsorption sites for dye molecules and are more suitable for photoanode materials. Then the optimal flower-like SnO2 particles are selected to prepare the photoanode, which is also modified with different concentrations of Ag nanoparticles to successfully introduce the localized surface plasmon resonance (LSPR) effect, and the optimal modification concentration is explored. Conformal characterisation, dye adsorption and light absorption tests revealed that the modification of Ag nanoparticles not only optimises the photoanode conformal structure and improves the dye adsorption, but also works in conjunction with the LSPR effect to improve the light absorption and utilisation, thus increasing the cell efficiency. Many cell performances of DSSC are also greatly improved due to the above work, and the optimal cell performance of DSSC is achieved when the Ag nanoparticles doping concentration is 0.03 M. Compared with the pure flower-like SnO2-based photoanode DSSC, the short-circuit current density of the best Ag nanoparticle-modified DSSC is enhanced by 28.56% to 15.80 mA/cm2, and its efficiency is improved by 20.82%–5.92%.

Effects of gas diffusion layer thickness on PEM fuel cells with composite foam-rib flow fields

Gas diffusion layers (GDLs) play a crucial role for the performance of proton exchange membrane fuel cells (PEMFCs). The utilization of composite foam-rib flow fields (CFRFFs) can alter the reactant gas transfer pattern, hence improving the efficiency of under-rib reactant gas transfer and water drainage. The impact of the cathode and anode GDL thicknesses (hc,GDL and ha,GDL) on the performance of CFRFF design is investigated by three-dimensional multiphase non-isothermal numerical simulation in this study. The results indicate that for the conventional rib flow field (CRFF) design, there is an optimal hc,GDL for optimal cell performance, while for the CFRFF design, as hc,GDL becomes thinner, the cell performance increases, and the trend is dominated by the variation of the oxygen concentration. Under a thin GDL, the rib width of the CRFF design should be as small as possible to minimize concentration polarization loss, while the rib width of the CFRFF design can be slightly larger. Furthermore, by decreasing the thickness of ha,GDL in both the CRFF and CFRFF designs, there is an increase in the dissolved water content in the ionomer of the cathode CL and a subsequent decrease in the Ohmic polarization loss.

Numerical investigation of effect of mechanical compression on the transport properties of fuel cell microporous layer using a pore-scale model

The microporous layer (MPL) plays an important role in water and thermal management of proton exchange membrane fuel cells (PEMFCs). An in-depth investigation of the mechanical compression effect on transport properties in the MPL can help optimize cell performance. In this work, the microstructure of the MPL is numerically reconstructed and the finite element method is applied to simulate mechanical behavior. Besides, the distribution of stress-strain, porosity, and pore size in the MPL under ten different levels of mechanical compression strains are studied. Lastly, the pore-scale model is employed to investigate the effective transport properties of the MPL as a function of compression strain. The analysis reveals that as the MPL strain increases from 0% to 40%, there is a 29% decrease in porosity, a 50% reduction in average pore diameter, a 60% decrease in effective gas diffusivity, a 100% increase in tortuosity, and an 80% increase in electrical and thermal conductivity. With the escalation of mechanical compression, both the magnitude and uniformity of stress-strain-displacement concurrently rise. Mechanical compression strains below 20% exhibit a lesser impact on transport properties. Beyond this threshold, exceeding the 20% compression strain point, mechanical stress assumes a critical role in influencing MPL transport properties.

Classification of cell line Halm machine data in solar panel production factories using artificial intelligence models

<p>A solar energy module consists of solar cells that convert sunlight into electrical energy. The quality of these cells is the most important determinant of panel performance and lifespan. High-quality cells increase energy efficiency and extend panel life. Solar cells are typically composed of crystalline silicon, thin layers, and organic materials. Each material has its own advantages and disadvantages. However, what all cells have in common is that they produce electrical energy when exposed to solar radiation. Solar cells can be classified and ranked. This classification indicates the efficiency and performance of the cell. Solar energy modules are widely used to meet the energy needs of many homes and businesses. Accurately measuring cell performance can improve the overall efficiency of the panel. Therefore, AI (artificial intelligence) modeling offers many advantages in optimizing cell performance. The study yielded several benefits associated with modeling solar panel cells with artificial intelligence. Some of the benefits derived from this research are: Improved efficiency, Error detection and correction, Reduced maintenance costs, predictability, Increased production. These advantages demonstrate that AI modeling can help optimize solar panel cell performance.</p>

CIGS solar cells using ZrS2 as buffer layer: Numerical simulation

This study presents numerical optimization using the SCAPS-1D software package based on copper indium gallium selenide (CIGS) solar cell structure. ZrS2 is selected as a buffer layer in this research. The effect of carrier concentration and thickness of absorber/buffer layers on the electrical and photovoltaic performance of CIGS/ZrS2 solar cells have been investigated. The results showed an increase in the thickness from 0.2 to 2.0 µm and the carrier concentration of CIGS from 1012 to 1018 cm−3, increasing the Voc. The Jsc was increased with an increase in CIGS thickness. In addition, the increase in carrier concentration and thickness of CIGS lead to an increase in the CIGS/ZrS2 solar cell efficiency. The thickness of 1.4 µm and carrier concertation of 1018 cm−3 have been considered as optimized conditions. The increase in ZrS2 thickness results in an increase in the Jsc, and the power conversion efficiency (η). Consequently, the thickness of 0.35 µm, the carrier concentration of 1017 cm−3, and energy band gap of 1.5 eV can be selected as an optimum conditions for the ZrS2 buffer layer, which presents the η of 26.95%. Finally, the effect of series resistance (Rs) and shunt resistance (Rsh) have been investigated on the CIGS/ZrS2. The results exhibited that optimal solar cell performance is achieved when the Rs is low, and the Rsh is high.

Power Generation Charactristics of Polymer Electrolyte Fuel Cells with Electrocatalysts Supported on SnO2 in High Current Density Range

Introduction Considerable efforts have been made for FCEV commercialization, for which sufficient performance and durability have to be achieved1. SnO2-supported electrocatalysts with carbon backbone have a potential to achieve both high catalytic activity and high cycling durability2-3. However, it is necessary to further optimize cell performance up to high current densities for such alternative electrocatalysts. By controlling the thickness of the seal material and optimizing the Nafion content of the electrocatalyst layer, successful reduction of various overvoltages and improved power generation performance can be achieved, especially in the high current density region4. This study aims to further improve cell performance at high current densities by varying electrocatalyst layer fabrication conditions and selecting suitable settings for the MEAs. Experimental Using mesoporous carbon (MC) as a support backbone and SnO2 as a support surface layer on the cathode side5, membrane-electrode-assemblies (MEAs) with Pt/Sn0.92Nb0.08O2/MC electrocatalysts were fabricated. On the anode side, a standard Pt/C catalyst (TEC10E50E, Tanaka Kikinzoku Kogyo, Japan) was used. Cell performance and overvoltages up to high current densities were measured by varying the size of electrocatalyst particles. Start-stop cycle tests up to 60,000 cycles were also conducted. Results and discussion By ball milling before the Pt loading process in the preparation of the SnO2-supported electrocatalyst Pt/Sn0.98Nb0.02O2/MC, various overvoltages could be reduced, and cell performance became almost comparable to that of the standard Pt/C catalyst. Figure 1 shows the comparison of IV characteristics and Figure 2 shows the comparison of microstructures of electrocatalyst layers. Ball milling resulted in a more appropriate microstructure of the electrocatalyst layer due to the homogenization of the electrocatalyst particle size. As shown in Figure 3, the ECSA retention after 60,000 start-stop cycles was about 50%. Even when MC was used as the support framework, high durability could be achieved due to the presence of SnO2, which was further improved by ball milling. Without ball-milling, the retention was about 45%.In the future, we aim to further improve cell performance by controlling the porous microstructure and water management of the electrocatalysts layer. We will fabricate cells under various conditions, conduct performance tests, and analyze overvoltages. The start-stop and load cycle durability will also be evaluated. Based on these efforts, the latest results of cell performance and durability tests will be presented. Acknowledgment This paper is based on results obtained from a project, JPNP20003, commissioned by the New Energy and Industrial Technology Development Organization (NEDO). References Takahashi, T. Ikeda, K. Murata, O. Hotaka, S. Hasegawa, Y. Tachikawa, M. Nishihara, J. Matsuda, T. Kitahara, S. M. Lyth, A. Hayashi, and K. Sasaki, J. Electrochem. Soc., 169, 044523 (2022).Nakazato, D. Kawachino, Z. Noda, J. Matsuda, S. M. Lyth, A. Hayashi, K. Sasaki, J. Electrochem. Soc., 165, F1154 (2018).Matsumoto, M. Nagamine, Z. Noda, J. Matsuda, S. M. Lyth, A. Hayashi, K. Sasaki, J. Electrochem. Soc., 165, F1164 (2018).Ogawa, Y. Inoue, K. Yamamoto, M. Yasutake, Z. Noda, S. M. Lyth, J. Matsuda, M. Nishihara, A. Hayashi, K. Sasaki, ECS Trans., 109 (9), 241 (2022).Inoue, M. Yasutake, Z. Noda, S. M. Lyth, M. Nishihara, A. Hayashi, J. Matsuda, K. Sasaki, ECS Trans., 109 (9), 413 (2022). Figure 1

Towards Conformally Grafted Thin Film Ionomers for High Performance Polymer Electrolyte Fuel Cells

The development of the next generation of polymer electrolyte fuel cells has become a major focus in the decarbonization of heavy-duty transportation, such as public transport, land, aviation, and maritime freight1. Specifically, there is a need for improved catalyst layers with lower amounts of expensive platinum group metals2, as well as improved mass transport characteristics at high current densities, fluorine-free ionomers, and increased durability3. Achieving an optimal electrode microstructure is crucial in this process, as it influences the mass transport of reactant gases and products2. The chemistry and morphology of the ionomer film determine proton availability and affect oxygen transport and overall catalyst utilization. Thus, it is critical to maintain a delicate balance between the transport of reactants, products, protons, and electrons to ensure optimal cell performance. Traditional catalyst layers are fabricated using catalyst ink dispersions which limits the control over the triple-phase boundary microstructure4. This is problematic as poor distribution of the ionomer has been shown to have a negative impact on fuel cell performance5. It has been observed that some catalytic sites are inundated with ionomer, leading to a high oxygen transport resistance, while other uncoated sites may experience a lack of protons. Moreover, research has shown that the catalyst's active sites can be poisoned by the adsorption of sulfonic acid moieties present in commonly used ionomers. Motivated by these challenges, and the negative environmental impact of conventional fluorinated ionomers, it is essential to develop alternative ionomer chemistries and coating techniques6.To address these challenges, our research focuses on developing innovative synthetic methods that leverage both electrochemical and chemical principles to enable local control of ionomer coating in the catalyst layer. Our interest in these methods originates from their scalability and ability to control the morphology of coatings (e.g. thickness, conformality, porosity and polymer length). We employ grafting techniques based on radical mechanisms to covalently graft conformal ionomer thin films onto conventional Pt/C catalysts to produce improved triple phase boundaries. A vast array of monomers with different kinds of functionalities (e.g. amines, vinylics, diazo-compounds, carboxylates) can be used for grafting, including fluorine-free systems7. In this presentation, I will first describe the synthetic procedure to produce ionomer thin films. Second, we perform ex-situ characterization including electron microscopy, porosimetry and wettability measurements. Furthermore, we study the ionomeric nature of the films by its ion exchange capacity. Subsequently, we screen the most promising samples in single cell tests and compare them against a state-of-the-art benchmark. By combining potentiostatic and impedance-based techniques, we seek to gain insight into the in-operando characteristics of these new electrode materials. Through this comprehensive set of experiments, we aim to elucidate morphology – property – performance relationships for these ionomer thin films to further guide optimization of catalyst microstructures. Acknowledgement: This publication is part of the project 3D-FCoat (3-Dimensional structures for Fuel Cells through advanced Coating techniques) of the research program LIFT which is (partly) financed by the Dutch Research Council (NWO) and Nedstack Fuel Cell Technology B.V.

Pressure and Impedance Based in Situ Diagnostic Methods for Water Management in Proton Exchange Membrane Fuel Cells Applications

Recent advancements in proton exchange membrane fuel cells (PEMFCs) have led to significant developments in low-carbon transport technology, enabling the generation of clean, efficient electricity with minimal noise and toxic emissions for heavy-duty applications. However, effective water management remains a critical challenge in PEMFCs due to the intricate phase changes and liquid-gas transport processes within key components, which significantly impact cell performance and longevity in industrial applications. Given the rapid dynamics of water activities and material responses within cells, in situ diagnostic techniques for water management in PEMFCs are essential for optimizing cell performance and extending the lifespan of fuel cell stack and system.Water, electrochemically produced on the cathode side, can cause potential flooding in key components including the catalyst layer (CL) and gas diffusion layers (GDLs), impeding air/oxygen supply to the cathode side. To characterize the performance loss induced by water flooding, Electrochemical Impedance Spectroscopy (EIS) is commonly employed as a fuel cell diagnostic tool. EIS records the contributions of different polarization processes to the global impedance with individual time constants during operation. However, the interpretation of complex EIS spectra can be very challenging, as polarization processes may overlap in frequency and be difficult to identify. To address this issue, Distribution of Relaxation Times (DRT) analysis is implemented as a powerful tool that allows for a clear separation and quantification of the polarization processes showing as peaks in a frequency domain [1]. Thus, we utilize EIS-based DRT analysis as an in-situ diagnostic tool to detect cathode flooding during cell operation. To validate this approach, we have conducted tests on a 300 cm2 low temperature PEMFC, varying one operation parameter at a time and evaluating its effects on cathode flooding by studying the frequency and height evolution of DRT peaks.Nevertheless, water flooding is not confined to the cathode side, as water can also permeate through the proton exchange membrane (PEM) and reach the anode side, resulting in potential fuel starvation on the cathode's counterpart and subsequent degradation of carbon-based materials. To address the sensitivity limitation of the EIS-based DRT method in detecting anode flooding, we employ an in-house developed pressure drop indicator (PDI) tool, as a non-invasive and real-time approach for diagnosing water flooding in the anode. The PDI tool assesses the pressure drop across anode channels, which is a function of the liquid water contents in bipolar plates considering the pressure reduction mainly caused by the frictional drag [2]. The effectiveness of the PDI tool is validated through cell testing at different water flooding levels by varying relative humidity and pressure conditions. This technique offers timely and sensitive detection of anode water flooding in PEMFCs, which is crucial for alarming irreversible material degradation in the electrode and facilitating appropriate follow-up actions.To conclude, we have developed and employed in situ PDI and EIS-based DRT methods within our water management framework for diagnosing water flooding in both the anode and cathode of PEMFCs in industrial applications. The combination of these techniques offers real-time and accurate assessments on water management conditions, which is crucial for optimizing overall performance and longevity of PEMFC stacks and systems.[1] Heinzmann, M., Weber, A., Ivers-Tiffée, E. (2018). Advanced impedance study of polymer electrolyte membrane single cells by means of distribution of relaxation times. Journal of Power Sources, 402, 24-33.[2] Barbir, F., Gorgun, H., & Wang, X. (2005). Relationship between pressure drop and cell resistance as a diagnostic tool for PEM fuel cells. Journal of Power Sources, 141(1), 96-101. Figure 1

Review on Bubble Dynamics in Proton Exchange Membrane Water Electrolysis: Towards Optimal Green Hydrogen Yield.

Water electrolysis using a proton exchange membrane (PEM) holds substantial promise to produce green hydrogen with zero carbon discharge. Although various techniques are available to produce hydrogen gas, the water electrolysis process tends to be more cost-effective with greater advantages for energy storage devices. However, one of the challenges associated with PEM water electrolysis is the accumulation of gas bubbles, which can impair cell performance and result in lower hydrogen output. Achieving an in-depth knowledge of bubble dynamics during electrolysis is essential for optimal cell performance. This review paper discusses bubble behaviors, measuring techniques, and other aspects of bubble dynamics in PEM water electrolysis. It also examines bubble behavior under different operating conditions, as well as the system geometry. The current review paper will further improve the understanding of bubble dynamics in PEM water electrolysis, facilitating more competent, inexpensive, and feasible green hydrogen production.

Characterization of Cost-Saving Monofacial PERC Module under Field Conditions in South Korea

The photovoltaic (PV) industry is constantly striving to increase module power output while decreasing costs. Importantly, the performance and reliability of cost-saving products should be evaluated before being launched into the PV market to avoid any unnecessary side effects. This study investigated the performance of a monofacial module employing a cost-saving bifacial cell installed at a carport in South Korea. The bifacial cell reduces costs, compared to monofacial cell, by using a lower quantity of aluminum paste on its rear; consequently, it has become a popular product in the PV industry. The monofacial module employing the bifacial cell showed an improved voltage temperature coefficient and low-light performance over monofacial cell-based module. Our field data highlight three conclusions from the bifacial cell-based module; it showed (1) different voltage temperature coefficients with better performance at lower temperatures, (2) better low-light performance owing to high series resistance, and (3) high current owing to its bifaciality. Notably, under high irradiance and temperature conditions, the bifacial cell performed worse than the monofacial cell. We concluded that this type of cell may perform well under northern European climatic conditions, though further investigation is required to optimize cell performance under various weather conditions.