Void Space Research Articles

Granular Hydrogels for Harnessing the Immune Response.

This review aims to understand the current progress in immune-instructive granular hydrogels and identify the key features used as immunomodulatory strategies. Published work is systematically reviewed and relevant information about granular hydrogels used throughout these studies is collected. The base polymer, microgel generation technique, polymer crosslinking chemistry, particle size and shape, annealing strategy, granular hydrogel stiffness, pore size and void space, degradability, biomolecule presentation, and drug release are cataloged for each work. Several granular hydrogel parameters used for immune modulation: porosity, architecture, bioactivity, drug release, cell delivery, and modularity, are identified. The authors found in this review that porosity is the most significant factor influencing the innate immune response to granular hydrogels, while incorporated bioactivity is more significant in influencing adaptive immune responses. Here, the authors' findings and summarized results from each section are presented and suggestions are made for future studies to better understand the benefits of using immune-instructive granular hydrogels.

THE MICROMORPHOLOGY OF AN SENSISITVE HILLY SOIL AS HABITAT FOR MICROBIOTA DELIVERING SOIL ECOSYSTEM SERVICES

The paper investigated the aspects related to the intimate processes taking place in a slope soil, located in the hilly region of Buzău County (Aldeni), an area highly affected by erosion processes. The study was focused on a Cambic-Cumulic Chernozem, located in the lower part of a convex slope facing south. The results showed that the plasma leaching process is very high in the upper Apt-A/B horizons: emphasised by the abundance of the impure clay coatings, which practically coated many structural aggregates. The granulometry data weakly emphasized these aspects: the differences between the clay content in the top Ap and Aph horizons is 1.1%, while the physical clay ( 0.01 mm) showed a higher difference of 1.8%. In contrast, the hydro-physical analysis showed impressive differences, comparing to the granulometry: total porosity is 53.5% in Ap and 43.2% in Aph, while the hydraulic conductivity is 10.29 mm/h in Ap, dropping to 4.57 mm/h in Aph. These differences could be due to the impure (and rich in Fe gels) clay coating which coated and even clog many pores. In the Bv horizon the clay attended a maximum (35.9%, comparing to 30.4% in the upper and 33.5% in the lower horizons respectively), the groundmass plasma is relatively stable, while the clay coatings are rarely. In stead, the plasma from the humic coprolites "massively" leached in the void space. The macro- and mesofauna activity is very high, suggesting a friendly habitat, and showing good conditions for high level of cumulic soil services delivery.

High Permeability Streak Identification and Modelling Approach for Carbonate Reef Reservoir

Reef reservoirs are characterised by a complex structure of void space, which is a combination of intergranular porosity, fractures, and vuggy voids distributed chaotically in the carbonate body in different proportions. This causes great uncertainty in the distribution of porosity and permeability properties in the reservoir volume, making field development a complex and unpredictable process associated with many risks. High densities of carbonate secondary alterations can lead to the formation of zones with abnormally high porosity and permeability—high permeability streaks or super-reservoirs. Taking into account super-reservoirs in the bulk of the deposit is necessary in the dynamic modelling of complex-structure reservoirs because it affects the redistribution of filtration flows and is crucial for reservoir management. This paper proposes a method for identifying superreservoirs by identifying enormously high values of porosity and permeability from different-scale study results, followed by the combination and construction of probabilistic curves of superreservoirs. Based on the obtained curves, three probabilistic models of the existence of a superreservoir were identified: P10, P50, and P90, which were further distributed in the volume of the reservoir and on the basis of which new permeability arrays were calculated. Permeability arrays were simulated in a dynamic model of the Alpha field. The P50 probabilistic model showed the best history matching after one iteration.

Particle dispersion through porous media with heterogeneous attractions.

Porous media used in many practical applications contain natural spatial variations in composition and surface charge that lead to heterogeneous physicochemical attractions between the media and transported particles. We performed Stokesian dynamics (SD) simulations to examine the effects of heterogeneous attractions on quiescent diffusion and hydrodynamic dispersion of particles within geometrically ordered arrays of nanoposts. We find that transport under quiescent conditions occurs by two mechanisms, diffusion through the void space and intermittent hopping between the attractive wells of different nanoposts. As the attraction heterogeneity increases, the latter mechanism becomes dominant, resulting in an increase in the particle trajectory tortuosity, deviations from Gaussian behavior in the particle displacement distributions, and a decrease in the long-time particle diffusivity. Similarly, under flow conditions corresponding to low Péclet number (Pe), increased attraction heterogeneity leads to transient localization near the nanoposts, resulting in a broadening of the particle distribution and enhanced longitudinal dispersion in the direction of flow. At high Pe where advection strongly dominates, however, the longitudinal dispersion coefficient is insensitive to attraction heterogeneity and exhibits Taylor-Aris dispersion behavior. Our findings provide insight into how heterogeneous interactions may influence particle transport in complex 3-D porous media.

NUMERICAL DESIGN OF ASYMMETRIC POROUS MATERIALS WITH TARGET PROPERTIES

Numerical tools have become ubiquitous in design of manufactured porous materials. Many methods have been developed for imaging, reconstruction, material property estimation, and generation of materials in a virtual environment with the ultimate goal of understanding the connection between the synthesis process, material microstructure, and material properties. In previous works, we presented a new random field-based generation technique called adjustable level cut filtered Poisson field (ALCPF). We paired the ALCPF technique with a flow simulation method, the pore topology method (PTM), to compute material properties and verify that targets have been attained. Building on our earlier work where we demonstrated the ability of ALCPF to efficiently generate a wide variety of homogeneous microstructures, we pursue three new goals. First, we extend ALCPF to produce heterogeneous asymmetric porous materials with a target pore size gradient. Second, we demonstrate the capability of asymmetric-ALCPF to control both solid and void spaces by generating virtual asymmetric materials with different types of solid matrix geometries and void space pore size gradients. Third, we use these materials to assess the accuracy of PTM results in comparison with the solution from a direct numerical simulation. This work demonstrates that the ALCPF method successfully generates porous microstructures with desired asymmetric geometry with less than 4% error compared to target pore size gradient. Also, PTM estimates permeability with an average error of less than 7% compared to direct numerical simulation results.

Antivirus and antibacterial filters for face masks based on silver quantum dots

Background/Aim. Available face masks, used to protect the respiratory system from various types of pathogens, show unsatisfactory efficiency because the size of viruses like severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is much smaller than the void spaces in these masks. Difficult breathing through some masks quickly tires out, which makes ordinary people avoid wearing them. These facts suggest that a new strategy is desirable for designing protective face masks. The aim of the study was to present new filters for face masks to protect people exposed to high concentrations of bacteria and viruses, particularly SARS-CoV-2. Methods. Filters for these masks were manufactured of dense cotton fabric impregnated with silver quantum dots. The filters were characterized by scanning electron microscopy and ioncoupled plasma mass spectrometry. Wettability properties were determined by measuring contact angles with water, and a color fastness test was performed. Antibacterial assay was performed using Staphylococcus (S.) aureus. Viability quantitative polymerase chain reaction (qPCR) for virus integrity assay and reverse transcription qPCR (RT-qPCR) assay were used for antiviral activity assessment. Results. In vitro assays showed extremely high efficiency of these filters in destroying S. aureus and SARS-CoV-2 virus. The filters also showed high safety and easy breathing possibilities. Conclusion. The high efficiency of these masks against SARS-CoV-2 has been demonstrated through numerous tests, and they have been approved as anti-SARS-CoV-2 masks for the first time in the world. In the meantime, this solution has been applied in practice, and the data obtained about that are very encouraging.

Mechanical and clogging characteristics of SBR modified pervious concrete reinforced with geogrids - A Functional Data Analysis approach

Pervious concrete is a special type of concrete with high porosity but with limited structural strength. Geogrid reinforced pervious concrete is a specialized type of pervious concrete that incorporates geogrids for added structural performance. The composite material benefits from the geogrid's tensile strength and load-spreading capability with the addition of geogrids. Present study aims at investigating the mechanical, shrinkage and clogging characteristics of Styrene Butadiene Rubber (SBR) modified pervious concrete reinforced with glass fiber mesh, HDPE mesh, fiber glass geogrid, HDPE geogrid and coir geogrid. SBR modification is done from 0% to 15% by weight of cement The results show a palpable improvement in flexural strength of pervious concrete. HDPE geogrid provides almost the double flexural strength as non-reinforced pervious concrete. SBR modification of pervious concrete also enhanced the mechanical properties. Each grid/mesh has its own optimum dosage of SBR for maximum flexural strength. Laying geogrids can reduce the drying shrinkage of pervious concrete. The relative contact area of grid/mesh with the cement paste is a critical factor in reducing drying shrinkage. However, geogrid can lead to clogging in pervious concrete. Soil particles get accumulated in the void spaces and thereby reduce its permeability. Coir geogrid traps a larger quantity of soil particles impairing the permeability. Functional regression modelling by Functional Data Analysis approach is used to analyse the relationship between various grids and meshes with the properties of pervious concrete. The p-value and derivative plots gives better insight into the factorial effects.

Bacteria–fungi interaction for material formation

Abstract This paper describes an early-stage research and experiments exploring methods of co-cultivation of the fungal strain Ganoderma lucidum and the bacterial strain Sporosarcina pasteurii within the field of architecture. Co-cultivating these species within a bio-based compound, forming a living material, shows that the binding abilities of both microbial partners can be harnessed through multistep production techniques. As the mycelial network of the fungus spreads through the inoculated wood substrate, bacterial cells disperse and multiply on this same network and release the enzyme urease throughout the now-forming compound bound by the fungus. The enzyme is one of the key actors in the biocementation process, which is activated with the addition of a calcium source to the material. Calcium carbonate minerals form and attach on the hyphae, as well as in between the network, inside the wood sawdust pieces and around void spaces within the composite. While additional data collection is required, the current state of this research suggests that properties of both living materials can be expanded, for example, fire resistance and compressive strength compared to traditional mycelium-based composites, as well as the increased ability of the bacteria to homogeneously distribute and exist in unfavorable environments compared to mono-cultured bacterial communities.

Leveraging ordered voids in microporous perovskites for intercalation and post-synthetic modification.

We report the use of porous organic layers in two-dimensional hybrid organic-inorganic perovskites (HOIPs) to facilitate permanent small molecule intercalation and new post-synthetic modifications. While HOIPs are well-studied for a variety of optoelectronic applications, the ability to manipulate their structure after synthesis is another handle for control of physical properties and could even enable use in future applications. If designed properly, a porous interlayer could facilitate these post-synthetic transformations. We show that for a series of copper-halide perovskites, a crystalline arrangement of designer ammonium groups allows for permanently porous interlayer space to be accessed at room temperature. Intercalation of the electroactive molecules ferrocene and tetracyanoethylene into this void space can be performed with tunable loadings, and these intercalated perovskites are stable for months. The porosity also enables reactivity at the copper-halide layer, allowing for facile halide replacement. Through this, we access previously unobserved reactivity with halogens to perform halide substitution, and even replace halides with pseudohalides. In the latter case, the porous structure allows for stabilization of new phases, specifically a novel copper-thiocyanate perovskite phase, only accessible through post-synthetic modification. We envision that this broad design strategy can be expanded to other industrially relevant HOIPs to create a new class of highly adjustable perovskites.

A cobalt(II) coordination polymer-derived catalyst engineered via temperature-induced semi-reversible single-crystal-to-single-crystal (SCSC) dehydration for efficient liquid-phase epoxidation of olefins.

Single-crystal-to-single-crystal (SCSC) transformations provide more avenues for phase transitions, which have piqued great interest in crystal engineering. In this work, a 3D Co(II)-based coordination polymer (CP), {Co2(OH2)8(btec)}·4H2O (1), (where (btec)4- = 1,2,4,5-benzenetetracarboxylate) undergoes SCSC transition upon heating at 180 °C to afford an anhydrous phase [Co2(btec)] (1'). Room-temperature water-vapour induced semi-reversible SCSC transformation of 1' involves condensation of two water molecules coordinating to the metal cluster, yielding a new framework [Co2(OH2)2(btec)] (2). These SCSC transitions were accomplished through a sequential bond breaking and new bond formation process which was accompanied by colour changes from orange (1) → violet (1') → pink (2). All materials were structurally elucidated by single-crystal X-ray diffraction (SCXRD) and further established by various analytical techniques. According to SCXRD data, all the frameworks possess octahedral geometries around the cobalt(II) sphere. SCXRD studies further revealed that 1 is a polymeric architecture with a binodal 4-c sql topology while 1' and 2 possess (3,6)-c kgd and (4,6)-c scu 3D nets, respectively. By virtue of multitopicity exhibited by the tetracarboxylate, the coordination number of the linker around the Co(II) sphere increased from four (in 1) to eight (in 1') and then decreased to six (in 2). Most interestingly, permanent porosity could be observed for the dihydrate 2, originated from potential void space as substantiated by dinitrogen (N2) sorption isotherm. These porous frameworks were active catalysts for the aerobic epoxidation of the model substrate cyclohexene using molecular oxygen (O2) as the final oxidant in the presence of the sacrificial i-butyraldehyde (IBA) reductant. For using the dihydrous phase 2, cyclohexene and various other olefins were catalytically oxidised to their corresponding epoxides with up to 38.5% conversion and 99.0% selectivity. The catalyst 2 can be expediently recycled in four runs without significant loss of activity. This research demonstrates that a little innovation in the active-site-engineered organic-inorganic hybrid materials can significantly enhance the catalytic performance and selectivity of coordination polymer-derived heterogeneous catalysts.

ВИЗНАЧЕННЯ ЕФЕКТИВНОЇ ПОРИСТОСТІ ПОРІД-КОЛЕКТОРІВ ЗА ДАНИМИ СТРУКТУРИ ЇХ ПУСТОТНОГО ПРОСТОРУ У ВІЗЕЙСЬКИХ І ТУРНЕЙСЬКИХ ВІДКЛАДАХ БЕРЕЗІВСЬКОГО РОДОВИЩА

Background. Currently, it is quite important to track the patterns of the internal structure of reservoirs with their physical properties. The analysis of well-logging data in the well 203 of the Berezivske field of the Dnipro-Donetsk depression is necessary to assess the prospectivity of complexly structured reservoirs. Methods. The methodology for studying the void space structure in complexly structured reservoirs involved several stages: interpretation of well logging data; determination of parameters for the initial mathematical model of the reservoir; inversion of data from acoustic surveys into a curve of the distribution of different void formats; evaluation of reservoir rock types with determination of their effective porosity. Results. Based on the data of compressional and shear wave velocities, as well as density, three distinct rock groups were identified: compacted sandstone, calcareous sandstone and limestone. The initial approximation was obtained for each rock sample, including the set of void formats and their concentration within the reservoir layers. Direct analysis of the resulting data by the authors revealed that the most optimal void formats for the investigated intervals are: for intergranular voids – 0.07 to 0.9; for transitional voids and microcracks – 0.05 to 0.077; for microcracks – 0.007 to 0.0019; for caverns – 4 to 8. Based on the research results, it has been established that granular-cavernous porosity (39,2 %) and fracturedcavernous-granular porosity (29,5 %) are prevailing types of reservoirs. Conclusions. The calculated values of the void formats were used for these formations to quantitatively assess effective porosity based on the obtained data and specific electrical resistivity values at different depths of investigation. The resulting approximation of α = 0.6996 was selected, which reduced the error in calculating the effective porosity of reservoir rocks. The obtained results have demonstrated that the proposed methodologies are essential for understanding and quantitatively assessing the void space structure and filtration-capacitive properties of reservoir rocks, particularly when we are facing with a limited well logging data and restrictive core sampling.

Selectivity descriptors of the catalytic n-hexane cracking process over 10-membered ring zeolites.

Zeolite-mediated catalytic cracking of alkanes is pivotal in the petrochemical and refining industry, breaking down heavier hydrocarbon feedstocks into fuels and chemicals. Its relevance also extends to emerging technologies such as biomass and plastic valorization. Zeolite catalysts, with shape selectivity and selective adsorption capabilities, enhance efficiency and sustainability due to their well-defined network of pores, dimensionality, cages/cavities, and channels. This study focuses on the alkane cracking over 10-membered ring (10-MR) zeolites under industrially relevant conditions. Through a series of characterizations, including operando UV-vis spectroscopy and solid-state NMR spectroscopy, we intend to address mechanistic debates about the alkane cracking mechanism, aiming to understand the dependence of product selectivity on zeolite topologies. The findings highlight topology-dependent mechanisms, particularly the role of intersectional void spaces in zeolite ZSM-5, influencing aromatic-based product selectivity. This work provides a unique understanding of zeolite-catalyzed hydrocarbon conversion, linking alkane activation steps to the traditional hydrocarbon pool mechanism, contributing to the fundamental knowledge of this crucial industrial process.

Failure behavior of 70/30 brass lattice structure with a proposed cell topology produced by rapid investment casting

Lattice structures are unique architectural configurations with repeated unit cells and significant void spaces, offering exceptional specific strength, stiffness, and energy absorption capacity. These properties make them ideal for lightweight structures and mechanical dampers. Rapid investment casting, a blend of investment casting and 3D printing, emerges as a promising method for metal lattice structure production. It outperforms typical metal additive manufacturing, yielding products with fewer defects. A proposed cell topology has been introduced, striking an optimal balance between printability, castability, tensile strength, and shear strength. To explore its performance under compressive loading, 70/30 brass lattice structures with two varying heights were fabricated using rapid investment casting and evaluated. Shorter samples displayed uniform expansion within each cell row, while taller ones experienced abrupt shear fractures, resulting in lower absorbed energy. Detailed microstructure observations and additional mechanical properties were obtained, enhancing the understanding of failure behavior. In conclusion, rapid investment casting combined with the proposed cell topology opens exciting possibilities for manufacturing high-performance lattice structures with improved mechanical characteristics.

Two-step construction of KPDMS/Al2O3 ultra-barriers for wearable sensors.

Wearable devices hold significant potential in healthcare and medical diagnostics. One major challenge in realizing this potential is the low barrier property of polymer substrates, which fail to withstand surrounding moisture and biofluids. In this work, a two-step strategy involving ALI followed by a UV-curing process is developed to fabricate a K48PDMS/Al2O3 ultra-barrier with high barrier property of 7.82 × 10-5 g m-2 day-1 under stretching strain, representing one of the highest values among current works. Moreover, the K48PDMS/Al2O3 barrier enables Ca-tested devices to exhibit extended operational lifetimes of up to 12 days in simulated rain. It also ensures the high sensitivity of strain sensors for real-time monitoring of health-related physiological signals, even when exposed to aggressive solutions such as PBS, KOH, and glucose. A clear "filling-cross-linking" mechanism is revealed, involving the filling of the void spaces within polymer chains followed by the cross-linking of polymer side chains to enhance the density of the hybrid layer. Adjusting porosity and functional group density ensures complete Al2O3 infiltration into the polymer. The cross-linking increases from 12.31% to 73.79% compared to the UV-curing process alone due to the presence of Al2O3, further enhancing the density of the hybrid layer and its barrier properties. The proposed strategy in our work shows great potential for providing highly reliable encapsulation for wearable electronics.

Comparison of Mechanical Properties of Compacted Waste Soil from Open Dumping Area and Clay Soil for Future Development

Estimating the mechanical properties of soil samples involves analysing properties such as shear strength, density, and moisture content. It is important to use consistent and standardized testing methods, as well as to normalize the data to the same volume or weight, when comparing soil mechanical properties. Evaluating multiple properties will provide a more complete understanding of the differences between soils. Additionally, it is crucial to consider factors such as soil composition, history, and location when comparing soil properties. The main purpose of this paper is to compare the two types of soil which are waste soil and clay soil. Waste soil tends to have weak structure due to the multiple content of waste while clay soil is weak because of water absorption of in the clay structure. These two properties will have implications in terms of its mechanical properties. The experimental works that was conducted in this research are direct shear stress, density, water content and compressive strength. Clay soils tend to be less dense due to their fine-grained nature and the small size of their particles. Waste soil, on the other hand, can vary in density and can often be less dense than natural soils due to the presence of large void spaces. The water content in clay soils can significantly affect its shear strength, as excessive water can weaken the cohesive forces between the clay particles. In waste soil, the moisture content can affect the density and compaction of the soil, which can impact its stability. The expected outcome from this research is the conclusion of the mechanical properties for both types of soil.

Analyzing the Spatial Composition via Datascape Design Methodology in MVRDV's Projects

MVRDV describes its design method as ‘Datascape.’ All information that affects buildings, such as building codes, economic feasibility, and environmental requirements, is converted into data, and the results are built into a project. This paper aims to clarify and objectify the characteristics of the architectural space composition method in MVRDV architecture and to make it an alternative to contemporary architecture. A literature review of the concept of datascape and continuity, the theoretical background of MVRDV, was used as a methodology. Based on this, the specific space composition methods are extracted from common denominators in MVRDV’s projects. The result showed that the space composition method by void is a method of creating a void space by deleting stacked programs, and it is a concept that appeared in response to the urban density described by MVRDV. Constructing space by program creates a continuous space by internalizing the architectural program within the space and blurs the boundaries between inside and outside through transparency. The method of constructing space by diagrams creates the space and form of a building through the reinterpretation and rearrangement of a given program. The diagram referred to here appears in various spaces and forms in architecture, such as maps, statistical tables, and diagrams. The space composition method by the internal continuity plane refers to a space in which the city and the space are continuous. It is a space where mutual communication occurs where the distinction between inside and outside is ambiguous due to this continuous space. This can be said to establish a mutually ongoing relationship between the site and the interior space.

MoS2@CoS2 heterostructured tube-in-tube hollow nanofibers with enhanced reaction reversibility and kinetics for sodium-ion storage

Rational synergism in spatial nanostructures and heterogeneity are effective ways to enhance reaction reversibility and kinetics of materials for sodium-ion battery electrodes. Herein, we have designed MoS2@CoS2 heterostructured tube-in-tube hollow nanofibers via simple electrospinning, pyrolysis and sulfuration processes. The unique double-walled tubular structure resulted from a stepwise crystallization accompanied by pyrolysis volume shrinkage. It has appropriate void space and abundant MoS2@CoS2 heterointerfaces that can effectively avoid the volumetric change during the reaction process and accelerate the whole infiltration of the electrolyte. The formed MoS2/CoS2 heterojunction introduces a built-in electric field, which increases the adsorption energy and reduces the migration energy barrier of sodium ions. The synergies between distinctive hollow structures and heterogeneous compositional advantages lead to enhanced electrochemical performance for sodium storage with remarkable reversible capacity (858.3 mAh g–1 at 0.5 A g–1), high-rate performance (555.7 mAh g–1 at 5 A g–1), and superior long-term cycling stability (399.6 mAh g–1 after 1400 cycles at 8 A g–1). This rational spatial structures and heterogeneity synergetic strategy provide favorable inspiration for designing extraordinary performance electrode materials for sodium-ion batteries.

Recycled solar-grade silicon kerf scraps and sandwiched by tunable porous carbon sheets as commercial anodes

To commercialize silicon/carbon (Si/C) anodes easy, the solar-grade silicon kerf scraps (SGSKS) abandoned from photovoltaic industry are purified and recycled as a cost-efficient silicon source for lithium storage. However, limited by commercial cathodes, pursuing good structural integrity and durable lifespans is more worthy of concern than super-high capacity for commercial Si/C anodes which is primarily impacted by silicon mass fraction and volume vibration tolerance. Hence, controlling silicon mass loading and providing sufficient void spaces for volume vibration are significant for the high-grade Si/C anodes. Herein, a highly-tunable and facile synthesis approach for Si/C composite sandwiched by porous carbon sheets (PCS/Si) is described using flake-like CaCO3 as template and SGSKS as raw materials. Through regulating the mass ratio of CaCO3 and silicon, it can effectively control silicon mass loading and void spaces in PCS/Si for strengthening structural integrity, prolonging lifespans, simultaneously achieving sufficient capacity to meet commercial demands. The experimental findings demonstrate that benefitting from this deliberate design, the optimized PCS/Si-2 composite with silicon mass loading of 30.62 wt% delivers a high-profile capacity retention of 853.4 mAhg−1 at 0.2 Ag−1 with a relatively good structural integrity. Moreover, full cells using PCS/Si-2 anodes matched with commercial LiCO2 cathodes exhibit a long-cycle steady capacity of 103.4 mAhg−1 at 0.2 C which also can light a row of LED bulbs for hours, facilitating a rosy potential for commercial application. Meanwhile, it offers an alternative and valuable viewpoint for high-value recycle and reutilization of photovoltaic waste, promoting resource conservation and environment protection.

Microscale Simulation of Carbon Support Structure Degradation in Polymer Electrolyte Fuel Cell

Understanding the mechanism of Polymer electrolyte fuel cell (PEFC) degradation plays an important role in improving fuel cell performance and durability. For the PEFC system, the structure of catalyst layers (CLs) is the critical component that determines cell performance. The PEFC degradation due to the reduction of carbon on the CLs has been investigated in previous studies [1]. In our past studies, we focused on the actual heterogeneous porous structure of catalyst layer. From these results, it was found that mass transport performance of oxygen and proton in heterogeneous porous catalyst layer, which consists of carbon support, ionomer and void space, is much lower than that of theoretical prediction in homogeneous porous media [2-5]. In addition, it depends on the structure of carbon black, the coating structure of ionomer and the local distribution of these materials. Thus, it is important to understand and to predict the carbon support structure change by degradation because this structural degradation strongly affect the mass transport performance. In this work, the effect of CLs porous carbon support degradation on cell performance is investigated by microscale simulation.The CLs structures, consisting of porous carbon, ionomer, and Pt, are created by our previous study multi-block method [2,6]. In our simulation, we focus on studying the effect of CLs' beginning-of-life (BOL) and end-of-life (EOL) structure in the degradation process. The CLs creation procedure is illustrated in Fig. 1. Firstly, CLs structure are created by packing CB and covered ionomer and Pt. The amount of ionomer and Pt are assumed as constant during the degradation process. Therefore, the amount of carbon is reduced in EOL structure. In this study, various CLs structures with decreasing of carbon volume are constructed. Furthermore, the mechanical stress distribution under compression condition was simulated in each structure to understand the effect of framework of carbon on local porosity in catalyst layer. The effect of carbon corrosion in CLs is investigated by calculating the cell performance of PEFC of each CLs structure by ORR mass transport and electrochemical reaction calculation with our previous method [6].The cell performance is significantly decreased by reducing carbon. The degradation mechanism of PFEC is explained by degradation of not only effective surface area but also the porous structure change which affect oxygen diffusion performance. Moreover, compared with BOL structure the apparant thickness of covered ionomer layer is higher in EOL structures because of carbon corrosion and constancy of ionomer. Hence, the higher oxygen diffusion resistance in secondary pore and ionomer layer occur in CLs degradation structures. The effect of this dynamic structure change on cell output performance will be reported in this presentation.Acknowledgements:This research was supported by the New Energy and Industrial Technology Development Organization (NEDO), Japan, grant number P20003-20001327-0.

Investigating the Effects of Modified Interlayer Spacing within Mixed Metal Oxide Cathode Materials for Next-Generation Aqueous Rechargeable Zinc-Ion Batteries

Aqueous rechargeable zinc-ion batteries (ZIBs) are a promising addition to the current energy storage landscape, particularly supporting the decarbonization of the power sector as a low-cost, high safety alternative to lithium-ion batteries. Unfortunately, the relative infancy of ZIBs means that there are a limited number of reported cathode materials, and a divisive understanding of the operating principles for those which have been reported including Mn- and V-oxides. The large solvation shell of the working cation (Zn2+) imparts several design requirements for cathode material development, specifically the need for sufficient void space for Zn2+ intercalation, further limiting the materials which have been reported. Looking to other well-established battery chemistries, we considered the use of layered mixed metal oxides (MMOs) with Mn due to its known electrochemical activity within the operating voltage of aqueous ZIBs. We developed several MMO cathodes with tuned interlayer distance to achieve the larger void spacing capable of accommodating Zn2+. We investigated the impact of composition on the structural and electrochemical properties of 15+ different MMO materials. We determined that interlayer spacing plays critical role in electrochemical performance and that there is an optimal composition to provide enhanced specific capacity to the battery. Considering the narrow range of reported ZIBs cathodes, in this study we proposed several new materials that expand the scope of viable cathodes for next generation ZIBs and provides direction for future researchers to accelerate new material development for this technology.