Mercury Porosimetry Research Articles

Unveiling the fundamentals of flow boiling heat transfer enhancement on structured surfaces.

Micro- and nanostructured surfaces offer the potential to enhance two-phase heat transfer. However, the mechanisms behind these enhancements are not well-understood due to insufficient diagnostic methods, leading to reliance on trial-and-error surface development. We introduce in situ boroscopy to investigate microscale bubble dynamics during flow boiling nucleation and subsequent flow regime development. This method was applied in saturated flow boiling experiments within chemically etched aluminum and copper tubes. Although the surfaces have self-similar surface structures, our findings revealed varied heat transfer coefficient enhancements, with increases of up to 391% on aluminum and 41% on copper. Using boroscopy, we identified key mechanisms of heat transfer enhancement. We further used mercury porosimetry to determine the impact of pore size distribution on thermal performance. The boroscopy technique introduced here not only elucidates the underlying processes of flow boiling heat transfer enhancement but also has potential applications for the study of other two-phase phenomena.

Fractal Modelling of Heterogeneous Catalytic Materials and Processes.

This review considers the use of fractal concepts to improve the development, fabrication, and characterisation of catalytic materials and supports. First, the theory of fractals is discussed, as well as how it can be used to better describe often highly complex catalytic materials and enhance structural characterisation via a variety of different methods, including gas sorption, mercury porosimetry, NMR, and several imaging modalities. The review then surveys various synthesis and fabrication methods that can be used to create catalytic materials that are fractals or possess fractal character. It then goes on to consider how the fractal properties of catalysts affect their performance, especially their overall activity, selectivity for desired products, and resistance to deactivation. Finally, this review describes how the optimum fractal catalyst material for a given reaction system can be designed on a computer.

Comparison of Mercury Intrusion and Nitrogen Adsorption Measurements for the Characterization of Certain Natural Raw Materials Deposits

The porosity of materials is important in many applications, products and processes, such as electrochemical devices (electrodes, separator, active components in batteries), porous thin film, ceramics, soils, construction materials, ..etc. This can be characterized in many different methods, and the most important methods for industrial purposes are the N2 gas adsorption and mercury porosimetry. In the present paper, both of these techniques have been used to characterize some of Iraqi natural raw materials deposits. These are Glass Sand, Standard Sand, Flint Clay and Bentonite. Data from both analyses on the different types of natural raw materials deposits are critically examined and discussed. The results of specific surface areas showed considerable difference between the two sets of data on the same material. This indicates that the material have an external surface which can not be measure by mercury porosimeter. Also pore size distribution data obtained from N2 adsorption measurements shows a wide range of the smallest pore size. This result suggests that materials have micropores using IUPAC definitions of pore size.

β-Ca3(PO4)2- Ca9.95Li1.05(PO4)7 lamellar microstructure by chemical etching: Synthesis, characterization and in vitro bioactivity

In this study, new multilayer 3D porous scaffolds were designed with a core composed of Ca3O5Si (C3S) and external layers composed of Ca5Li2(PO4)4. Scaffolds' surface topography was modified to reveal a lamellar microstructure by applying chemical etching. Scaffolds were characterized by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy (FESEM/EDX), Fourier Transform Infrared Spectroscopy (FTIR) and Mercury Porosimetry. In vitro bioactivity was evaluated by immersing scaffolds in simulated body fluid (SBF) at 1, 3 and 7 days. Scaffolds presented calcium pyrophosphate, β-tricalcium phosphate (β-TCP), nonstoichiometric and stoichiometric calcium/lithium phosphate as the main phases. The calcium pyrophosphate and stoichiometric calcium/lithium phosphate in the external layer were eliminated by the chemical etching process, which revealed the lamellar microstructure. Lamellar width varied from 1.44 μm to 0.73 μm depending on the chemical etching time. The obtained mechanical strength results influenced samples’ macroporosity, which ranged from 50 % to 64 %. These samples also exhibited microporosity between 30.3 % and 49.0 %. During the bioactivity test, all the chemically etched samples showed a hydroxyapatite-like (HA-like) precipitate, except for the sample chemically etched for 30 s at day 1. At day 7, the lamellar microstructure in the samples chemically etched for 30 s and 45 s (C-30 s and C-45 s) was completely covered by the HA-like precipitate, whereas the lamellar microstructure in the sample chemically etched for 60 s (C-60 s) was only partially covered by the HA-like precipitate.

Development of a P(L-D,L)LA Foam as a Dura Substitute and Its In Vitro Evaluation

Dura substitutes are used to reduce the risk of postoperative complications following neurosurgical interventions, and to facilitate the healing of dura damages or defects caused by injuries. Traditional tissue transplants have limitations like limited tissue availability, potential risk of immune rejection and disease transmission. The use of biomaterials composed of synthetic polymers as dura substitutes offers a promising approach to overcome these limitations to replace and treat damaged dura mater. Potential biocompatible porous scaffolds still need to be developed to minimize the risks of immune response and disease transmission, while also ensuring effective cell migration and cell ingrowth in three dimension. The aim of the present study was to develop a poly(L-lactide-co-D,L-lactide) (P(L-D,L)LA) foam with an optimal pore size for dura mater substitution, investigate its morphological characteristics, and evaluate its potential for dura mater regeneration by assessing the spreading and growth of meningeal cells within it through in vitro studies. Foams were produced by lyophilization using different concentrations of P(L-D,L)LA solution. A GMP-grade P(L-D,L)LA, suitable for medical device applications, was used in this study. Morphological analysis was performed using scanning electron microscopy, and porosity of the foams was studied with mercury porosimetry. In in vitro studies, meningeal cells were seeded onto the polymeric foams, and their behavior and proliferation in these scaffolds were investigated with cytoskeleton and nucleus staining, and colorimetric cell proliferation assay, respectively. Scanning electron microscopy results showed that the foams prepared with 2.5% and 3% polymer solutions displayed good structural integrity and convenient interconnectivity, with pore sizes ranging from 80 to 150 µm. However, the foams prepared with 2% and 4% polymer solution demonstrated poor structural integrity and low interconnectivity, respectively. In vitro studies showed that the foams prepared with 2.5% and 3% polymer solutions served effectively as scaffolds for meningeal cells, and the cells attached, spread and homogeneously distributed. In addition, the cells proliferated and increased in number over time within these polymeric scaffolds. These findings suggest that the foams produced with 2.5% and especially 3% P(L-D,L)LA polymer solutions could effectively serve as a suitable substitute for the dura mater, providing an appropriate environment for cell ingrowth and tissue integration. This indicates that the developed foam could be a promising treatment for dura mater damage or defects, with the potential approach to promote regeneration in future in vivo and clinical studies.

Analysis of Wall Thickness and Absorption Characteristics of Ammonium Nitrate(V) from Various Sources.

This study investigates the wall thickness and specific surface area (SBET) of ammonium nitrate(V) samples of varying provenance. The research focuses on both fertilizer-grade ammonium nitrate(V) and three porous prill samples obtained from different manufacturers. The samples were analyzed using tomography scanning and two distinct porosimetry methods. The wall thickness analysis revealed that fertilizer-grade ammonium nitrate(V) possesses thicker walls, ranging from 0.05 to 0.40 mm, compared to porous prill-type ammonium nitrate(V), which predominantly exhibited wall thicknesses between 0.05 and 0.025 mm, with occasional thicker regions up to 0.040 mm. These variations in wall thickness are likely attributable to differences in manufacturing processes and prilling conditions specific to the ammonium nitrate(V) porous prill-type samples. The specific surface area (SBET), derived from nitrogen adsorption measurements, indicated that the samples exhibited surface areas ranging from 0.011 to 0.466 m2·g, suggesting that these samples do not exhibit particularly high absorption capacities. However, the SBET values obtained from the mercury intrusion method suggested significantly higher absorption capacities, falling within the range of 4.87-18.29 m2·g. These findings suggest that mercury porosimetry may provide a more accurate assessment of the porosity and absorption potential of ammonium nitrate(V) samples.

Evolution of Correlated Morphological and Structural Disorder in Boehmite‐Derived Alumina with Progressive Calcination

AbstractThis study explores the morphological and structural transformation of boehmite (AlOOH) into transition aluminas during calcination, a pathway crucial for diverse industrial applications. The primary focus is on the topotactic transformation of boehmite into γ‐Al2O3 and its subsequent transitions into higher temperature polymorphs, culminating in α‐Al2O3. Utilizing a combination of in situ X‐ray diffraction, in situ and ex situ transmission electron microscopy, 27Al solid‐state nuclear magnetic resonance, thermogravimetric analysis, nitrogen physisorption, and mercury porosimetry, this work provides insights into the morphological and structural reordering during the calcination process. Furthermore, the study highlights the significant impact of thermal processing on the morphological evolution of boehmite and transition aluminas, characterized by changes in pore structure sizes and shapes. These findings offer valuable insights for optimizing the properties of alumina‐based materials for specific applications.

Charcoal in Anaerobic Digestion: Part 1—Characterisation of Charcoal

Biochar (BC) is often used as an additive in anaerobic digestion (AD) to increase yield and/or to stabilise the process when the manure content is increased. Unfortunately, BC is rarely described in detail in terms of its raw material sources, production processes, and structural, physical and chemical properties to allow correlation with its effects on AD. It is an open question whether microorganisms from AD can penetrate into different biochar pore types, depending on their wood origin. In this paper, we describe the preparation (temperatures, treatment times, yields) and characterisation shrinkage, density, pore sizes, pore size distribution, specific surface area, ash, volatiles, fixed carbon, elemental composition, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), benzene, toluene, ethyl-toluene, xylene (BTEX) and volatile halogenated hydrocarbons (VHH) of BC cubes of Scots pine (Pinus sylvestris) and common beech (Fagus sylvatica) powder made from this BC in addition to commercial charcoal powder. The pore size distribution determined by mercury porosimetry differs from that determined by 3D-reflected light microscopy. After incubating BC cubes in AD, the cubes were mechanically cleaned and cut into two pieces. Microorganisms were detected inside the cubes by fluorescence microscopy. Particle size and wood source determine the influence of BC on AD.

3D‐Printed Highly Porous Functional Materials for the Efficient Removal of Adenovirus

AbstractHierarchical porous acrylate‐based materials are highly interesting as 3D filter materials, such as for virus removal from suspensions. Here, the synthesis of highly porous monolithic 3D materials by polymerization‐induced phase separation in liquid crystal display (LCD) based 3D printing is presented for the efficient removal of human adenovirus type 5. The hierarchical porosity can be tuned via the variation of the photocurable resin composition (i.e., inherent porosity) and the computer‐aided design (i.e., “printed” porosity; microchannels). 3D polymer structures with highly intricate geometries and structural features ranging from ≈20 nm up to cm can be achieved, which can be used for effective virus removal in a laboratory‐scale flow‐through approach. Combined focused ion beam/scanning electron microscopy tomography and mercury porosimetry provide detailed information on the inherent pore size, pore size distribution, and pore interconnectivity, which is key for the performance of such functional 3D materials. Polymers with a theoretical void volume of 75% show virus capture with a removal efficiency of ≈70% of the adenovirus. Polymers with the same theoretical void volume and macroscopic design but a more hydrophobic nature captured only ≈33%. An optimized adenovirus retention of 98% is achieved by adjusting the microchannels of the tunable inserts.

Macroporous Structures of Nb-SnO2 Particles as a Catalyst Support Induce High Porosity and Performance in Polymer Electrolyte Fuel Cell Catalyst Layers.

Macroporous niobium-doped tin oxide (NTO) is introduced as a robust alternative to conventional carbon-based catalyst supports to improve the durability and performance of polymer electrolyte fuel cells (PEFCs). Metal oxides like NTO are more stable than carbon under PEFC operational conditions, but they can compromise gas diffusion and water management because of their denser structures. To address this tradeoff, we synthesized macroporous NTO particles using a flame-assisted spray-drying technique employing poly(methyl methacrylate) as a templating agent. X-ray diffraction analysis and scanning electron microscopy confirmed the preservation of crystallinity and revealed a macroporous morphology with larger pore volumes and diameters than those in flame-made NTO nanoparticles, as revealed by mercury porosimetry. The macroporous NTO particles exhibited enhanced maximum current density and reduced gas diffusion resistance relative to commercial carbon supports. Our findings establish a foundation for integrating macroporous NTO structures into PEFCs to optimize durability and performance.

Surface Modification of a Zeolite Microfiltration Membrane: Characterization and Application to the Treatment of Colored and oily Wastewaters

Membrane-based technologies used for water treatment can be an excellent alternative to handle wastewater including both conventional and emerging pollutants as they can provide technological (e.g., high quality of treated water) and economic (e.g., small footprint and low unit cost of production) advantages over other water treatment processes. Recently, low cost ceramic membranes fabricated from natural resources like kaolinitic clay, bentonite clay, phosphate are increasingly used owing to their low-cost starting materials, low sintering temperature and their excellent additional properties. Moreover, the modification of the surface by grafting process provides membranes appropriate for low UF process (dp < 10 nm) and suitable for micropollutants removal at relatively high permeate flux value which can be maintained during filtration due to antifouling characteristics of the UF active layer. In this work, the surface of microfiltration membranes made from natural zeolite was chemically modified by grafting with 1 H, 1 H, 2 H, 2 H-perfluorodecyltriethoxysilane molecule named PFAS. Various characterization methods and techniques, including scanning electron microscopy (SEM), mercury porosimetry, FTIR, TGA, and contact angle, were used to check the properties of the membranes surface before and after grafting. The grafted membranes pore size and porosity were reduced, as proved by SEM images. The determination of the water permeability shows a reduction from 1218 L.h−1.m−2.bar −1 to 204 L.h−1.m−2.bar −1 which confirm the surface densification. The application of the grafted membrane to the treatment of Indigo Blue (IB) colored solution and oily wastewater was investigated to evaluate the performances of this membrane in terms of permeate flux and pollutants retention. The filtration results revealed a good retention of color and oil, exceeding 95% for both parameters. Therefore, it is interesting to recommend this new low-cost membrane for the treatment of industrial wastewater containing recalcitrant pollutants such as color. The study of the effect of the treated colored solution on plant growth, shows that the presence of some residual nutrients required for crops growth, might make the IB treated water beneficial for irrigation purposes.

Methods of Pore Structural Characterisation of Sedimentary Rocks and Their Constituent Minerals

Pore structural characterisation is important for rocks and their constituent minerals in order to understand physico-chemical processes occurring therein. Rather than a broad general survey of potential pore characterisation techniques, this review focuses on an in-depth discussion of some key current issues in this topic. A so-called ‘brute-force’ characterisation approach involving a single imaging modality is seldom possible for rocks due to their high degree of heterogeneity. This work surveys alternate strategies suitable for rocks. Further, this work addresses some misapprehensions and misunderstandings that have arisen concerning some experimental techniques offering alternate strategies to the brute-force approach, such as gas overcondensation and mercury porosimetry. It also considers some pore structural characterisation techniques, such as cryoporometry, that are seldom used in the context of natural materials and surveys their capabilities.

Fabrication of Flat Tubular Clay-Based Porous Support Filters

Objective: Mongolia has few freshwater resources. It is therefore important to conserve water resources. An efficient possibility is to purify water and reuse it. Therefore, the scientists from the Material Science Center of the Mongolian University of Science and Technology collaborated with the researcher from the Korea Institute of Material Science and carried out a project between 2017-2020. Theoretical Framework: In this study, Mongolian zeolites and prepared kaolin were used and flat tubular porous support was extruded by a double screw vacuum extruder at KIMS. Method: The supports were burned at 800 and 1000°C and the properties such as pore distribution were determined by mercury porosimetry Results and Discussion: The zeolite-kaolin support had a bulk density of 1.46 g/cm3, a porosity of 41.52% and, an average pore size of 218 nm. With its water permeability of 115 L/m2·h at 0.01 MPa and 970 L/m2·h at 0.08 MPa, the support achieved good results. Research Implications: The wastewater treatment tests show that these membranes also have good compressive strengths. We have cleaned the sewage from a leather factory, which was very highly contaminated and has high viscosity. Originality/Value: Since there is no chemical industry in Mongolia, raw materials for synthetic materials are imported. The main significance of this research work lies in determining the possibility of producing ceramic membranes for water filtration using the mineral resources of our country, and it will serve as the basis for future research.

Characterisation of asbestos-containing wastes by thermal analysis

The study examined building materials containing asbestos, which have been considered hazardous waste for several years. Samples were taken from various places in Poland. The chemical composition was examined using chemical analysis, the mineralogical phases were identified using X-ray diffraction, and the structure was identified using scanning electron microscopy, taking into account energy-dispersive spectroscopy. Thermal tests of the samples were performed using thermal analysis, thermogravimetric measurements and high-temperature microscopy. Additionally, changes that occurred in the microstructure were determined using mercury porosimetry and infrared spectroscopy. All the above research methods were used to characterise the properties of cement–asbestos materials, which were also subjected to isothermal thermal treatment at a temperature of 1100 °C for 4 h. The results proved that the material after thermal treatment undergoes significant structural changes. The thermal decomposition process of cement–asbestos involves dehydration, dehydroxylation and then recrystallisation to new stable crystalline phases but in the context of asbestos, we are dealing here with the so-called phenomenon of pseudomorphosis. Knowledge about the thermal properties of asbestos materials can provide us with data on how the material undergoes significant structural changes, thanks to which it will be possible to use neutralised cement–asbestos waste as possible safe materials.

Method to determine envelope density for roller compacted ribbons by solid displacement of glass microspheres

The envelope density of the roll-compacted ribbon is a widely accepted physical property that serves as a criterion for the transferability of dry granulation processes. Existing methods of obtaining ribbon density data have drawbacks in their reliability and availability at production facilities. A novel method is proposed in this paper and the performance thereof is compared to other established techniques. A pilot study was conducted on several roller compactors to prepare various batches of ribbons under different process parameters using model and real formulations from the industry. The presented method measures the envelope volume of roll-compacted ribbons by solid volume displacement of glass microspheres. The solid displacement method for measuring envelope density is as precise as mercury porosimetry, provided that the ribbon quality is adequate, even in the presence of minor structural failures, it is nondestructive allowing sample reuse, and it is scalable to larger ribbon sizes.

Preparation and in vivo osteogenesis of acellular dermal matrix/dicalcium phosphate composite scaffold for bone repair

To investigate the physicochemical properties, osteogenic properties, and osteogenic ability in rabbit model of femoral condylar defect of acellular dermal matrix (ADM)/dicalcium phosphate (DCP) composite scaffold. ADM/DCP composite scaffolds were prepared by microfibril technique, and the acellular effect of ADM/DCP composite scaffolds was detected by DNA residue, fat content, and α-1，3-galactosyle (α-Gal) epitopes; the microstructure of scaffolds was characterized by field emission scanning electron microscopy and mercury porosimetry; X-ray diffraction was used to analyze the change of crystal form of scaffold; the solubility of scaffolds was used to detect the pH value and calcium ion content of the solution; the mineralization experiment in vitro was used to observe the surface mineralization. Twelve healthy male New Zealand white rabbits were selected to prepare the femoral condylar defect models, and the left and right defects were implanted with ADM/DCP composite scaffold (experimental group) and skeletal gold ® artificial bone repair material (control group), respectively. Gross observation was performed at 6 and 12 weeks after operation; Micro-CT was used to detect and quantitatively analyze the related indicators [bone volume (BV), bone volume/tissue volume (BV/TV), bone surface/bone volume (BS/BV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), bone mineral density (BMD)], and HE staining and Masson staining were performed to observe the repair of bone defects and the maturation of bone matrix. Gross observation showed that the ADM/DCP composite scaffold was a white spongy solid. Compared with ADM, ADM/DCP composite scaffolds showed a significant decrease in DNA residue, fat content, and α-Gal antigen content ( P<0.05). Field emission scanning electron microscopy showed that the ADM/DCP composite scaffold had a porous structure, and DCP particles were attached to the porcine dermal fibers. The porosity of the ADM/DCP composite scaffold was 76.32%±1.63% measured by mercury porosimetry. X-ray diffraction analysis showed that the crystalline phase of DCP in the ADM/DCP composite scaffolds remained intact. Mineralization results in vitro showed that the hydroxyapatite layer of ADM/DCP composite scaffolds was basically mature. The repair experiment of rabbit femoral condyle defect showed that the incision healed completely after operation without callus or osteophyte. Micro-CT showed that bone healing was complete and a large amount of new bone tissue was generated in the defect site of the two groups, and there was no difference in density between the defect site and the surrounding bone tissue, and the osteogenic properties of the two groups were equivalent. There was no significant difference in BV, BV/TV, BS/BV, Tb.Th, Tb.N, and BMD between the two groups ( P>0.05), except that the Tb.Sp in the experimental group was significantly higher than that in the control group ( P<0.05). At 6 and 12 weeks after operation, HE staining and Masson staining showed that the new bone and autogenous bone fused well in both groups, and the bone tissue tended to be mature. The ADM/DCP composite scaffold has good biocompatibility and osteogenic ability similar to the artificial bone material in repairing rabbit femoral condylar defects. It is a new scaffold material with potential in the field of bone repair.

Flue gas desulfurization by natural recyclable manganese ore in packed bed reactor and its performance prediction by random pore model

Various grades of manganese dioxide ores, as a natural recyclable sorbent, can be used in dry flue gas desulfurization (FGD) at moderate temperatures (350–450 °C). This research provided low- and high-grade manganese dioxide ores to examine SO2 removal in a packed bed reactor. To obtain characteristic parameters of mineral sorbents, XRD, XRF, BET, and mercury porosimetry were employed. Then, kinetic parameters of desulfurization reaction were determined using thermogravimeter analyzer (TGA) and random pore model (RPM) for a single pellet. In desulfurization experiments of simulated flue gas in a packed bed reactor and mass spectrometer (MS) apparatus, the breakthrough times were measured under various operating conditions. The onset of these breakthrough times or life-time of MnO2 reactor for the SO2 removal was predicted successfully by RPM for a packed bed reactor using related kinetic constants from TGA. In addition, reacted sorbets were recycled multiple times after washing with water. Not only does this simple method separate MnSO4 from unreacted sorbents as a valuable byproduct to reduce the FGD cost, but it also improves pore size distribution (PSD) of mineral MnO2 by creating large pores. Modified PSD of this recycled sorbent caused increased breakthrough time.

Phosphate mine by-products as new cementitious binders for eco-mortars production: Experiments and machine learning approach

Phosphate mining industry generates different types of by-products that have significant environmental impacts such as ecosystems destruction and soil contamination. To reduce their environmental footprint, these wastes were investigated as supplementary cementitious materials (SCMs). The generated by-products included a clayey material and calcareous marl which were used in the current study. Blends of the abovementioned materials with cement (ratio of 1:1) were investigated using X-Ray Fluorescence spectrometry (XRF), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TDA-TG), Mercury Porosimetry, Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Electromechanical testing device. Using these results, a learning model based on multiple linear regression (MLR) was proposed to predict the compressive strength and the specific surface area from the constituents of the material, the additives, the L/S ratio, and the hardening regime. The accuracy of the models was assessed using the correlation coefficient (R2), mean absolute error (MAE), and root mean square error (RMSE). Compressive strength results confirmed that the sample's strength improved with the amount of calcined clay. Unlike the water demand where the mixtures required more water than the OPC mixture. SEM-EDS examinations proved the existence of the C–S–H gel, responsible for the specimen strength. The used machine learning model demonstrated excellent performance and practical potential to predict both compressive strength (CS) and specific surface area (SS) by capturing both linear and nonlinear relationships. As well as time and plasticizer were the most influential factors on the properties studied (CS and SS) and their effect was positive. This sensitivity study provides important information on the critical factors influencing compressive strength and specific surface area in the different ranges considered.

Preliminary microstructural research of clay solid bricks taken from historic buildings located in Poland

The article presents the results of the preliminary experimental research and analysis of the structure of samples of clay solid bricks from six historical buildings erected in Poland in the years 1300 to 1910. Images obtained with a scanning electron microscope; parameters characterizing the pore space of the ceramic material, which were obtained using mercury porosimetry; and chemical composition identified using an energy dispersive X-ray spectroscopy, were analyzed. The test results showed that as the age of the brick increases, the homogeneity of its structure decreases, the chemical composition of all samples is quite similar, and in the tested samples, large disproportions in the percentage of pore width in individual ranges can be observed. An indicator P-index useful in comparing the studied structures was proposed, based on the knowledge of the share of the pores’ width within the adopted ranges.

Relationship between particle shape and fast-charging capability of a dry-processed graphite electrode in lithium-ion batteries

Improving lithium-ion transport in electrodes by controlling electrode microstructure is a promising option for enhancing the fast-charging capability of graphite anodes in lithium-ion batteries. Dry processing of electrodes based on a polytetrafluoroethylene binder has attracted considerable attention as an alternative to solvent-based wet processing. The morphology of graphite particles has a significant impact on electrode microstructure, but few reports have been published on dry-processed graphite anodes. In this work, we found that the morphology of graphite particles is a key factor to determine the fast-charging capability of the dry-processed graphite electrode as well as the microstructure of the dry-processed graphite electrode. X-ray microscopy combined with mercury porosimetry and symmetrical cell electrochemical impedance spectroscopy reveal that the difference in porosity between the top and bottom layers of a dry electrode with spherical graphite particles is greater than that of flake-shaped graphite particles, resulting in enhanced lithium-ion transport in the electrode and improved fast-charging capability at a high charging rate of 5C (17.5 mA cm−2). These findings supply insights into the effective design of dry-processed graphite anodes with an emphasis on fast-charging capability as well as the development of graphite anode materials for dry-processing based lithium-ion batteries.