Analogous Materials Research Articles

Achieving Long-Cycle-Life Zinc-Ion Batteries through a Zincophilic Prussian Blue Analogue Interphase.

The practical application of rechargeable aqueous zinc-ion batteries (ZIBs) has been severely hindered by detrimental dendrite growth, uncontrollable hydrogen evolution, and unfavorable side reactions occurring at the Zn metal anode. Here, we applied a Prussian blue analogue (PBA) material K2Zn3(Fe(CN)6)2 as an artificial solid electrolyte interphase (SEI), by which the plentiful -C≡N- ligands at the surface and the large channels in the open framework structure can operate as a highly zincophilic moderator and ion sieve, inducing fast and uniform nucleation and deposition of Zn. Additionally, the dense interface effectively prevents water molecules from approaching the Zn surface, thereby inhibiting the hydrogen-evolution-resultant side reactions and corrosion. The highly reversible Zn plating/stripping is evidenced by an elevated Coulombic efficiency of 99.87% over 600 cycles in a Zn/Cu cell and a prolonged lifetime of 860 h at 5 mA cm-2, 2 mAh cm-2 in a Zn/Zn symmetric cell. Furthermore, the PBA-coated Zn anode ensures the excellent rate and cycling performance of an α-MnO2/Zn full cell. This work provides a simple and effective solution for the improvement of the Zn anode, advancing the commercialization of aqueous ZIBs.

Optical polarization studies of latex beads in aqueous solution: An analog for radar scattering in icy regolith

This study presents low phase angle 0°–5° measurements of polarimetric properties of icy planetary regolith analog materials acquired using the custom-built Multi-Axis- Goniometer-Instrument (MAGI). We present same sense (SC), and opposite sense (OC) backscatter circular polarization coefficients, circular polarization ratio (CPR), and degree linear polarization (DLP) of spherical latex (non-dye) beads of varying sizes and volume concentrations (v/v) in aqueous solutions (λ=0.8μm) in water. We also present measurements of alumina powder in air at λ=1.064μm. Measurements showed that at a low incidence angle (i=0°), backscatter is dominated by surface specular single-bounce scattering, that hides other scattering processes. At high (i=15°) incidence angle, surface single-bounce surface scattering becomes negligible, allowing for the detection of diffuse, dihedral (multiple bounces) scattering. We find that classical Mie alumina particles (2.1μm,4.0μm) enhance subsurface scattering due to a larger void space relative to larger Mie particles (30μm), that cause the radar signal to scatter forward off small imperfections, maintaining the polarization properties of the signal and generating high >1CPR. Latex beads, representing impurities, demonstrate the impact of isotropic and anisotropic scattering on radar signatures. This study also found that the scattering medium’s anisotropy correlates to the size of the beads, while the void space of the medium inversely correlates with the bead size and the volume concentration (v/v) of the beads. Rayleigh beads, due to isotropic scattering from the reduced scattering cross-section and higher transparency relative to larger impurities, generate subsurface single bounce scattering from the sample platform, producing OC≫SC and a low (<0.5)CPR across all v/v. Rayleigh impurities in transparent water-ice simulate single bounce scattering from underlying layers. Conversely, classical and large Mie beads generate anisotropic scattering that intensifies scattering in the forward direction with high CPR, inversely proportional to the volume concentration. This study aids in interpreting radar observations of icy bodies in the solar system, providing insights into the interplay between radar waves and icy regolith compositions.

Life cycle carbon analysis of packaging products containing purposely grown nonwood fibers: A case study on the use of switchgrass pulp for linerboard and corrugating medium

Sustainability is driving innovation in the pulp and paper industry to produce goods with lower carbon footprints. Although most of the efforts are currently focused on increasing energy efficiency or switching to renewable fuels, the attention toward alternative feedstocks has increased in recent years. Claims of nonwood fibers requiring lower use of chemicals and energy than wood fibers, along with negative consumer perceptions of tree felling, are helping purposely grown nonwoods to gain market share. The potential nonwood fiber environmental superiority over virgin or recycled wood fibers remains controversial and is often driven more by emotion and public perception rather than facts. This paper estimates the carbon footprint of corrugating medium and linerboard containing switchgrass pulp compared to analogous wood-based materials. The study includes a life cycle carbon analysis spanning from cradle to gate, which comprises stages for fiber production, pulping, papermaking, and corresponding transportation. Carbon footprints for virgin linerboard, recycled linerboard, virgin medium, and recycled medium were estimated at around 510, 620, 460, and 670 kg carbon dioxide equivalent per metric ton (kg CO2eq/t), respectively. Replacing 30% of the virgin or recycled material with switchgrass pulp translated into carbon footprint increases of around 60%, 45%, 62%, and 38%, respectively. Thus, for the proposed case study, the results suggest that switchgrass-based medium and linerboard can present a higher carbon footprint than products made from virgin and recycled wood fibers. The main driver is the production of nonwood mechanical pulp. This study was designed to mitigate part of the uncertainty around the environmental sustainability of medium and linerboard made from the selected purposely grown nonwood fibers.

Life cycle carbon analysis of packaging products containing nonwood residues: A case study on linerboard and corrugating medium

Circularity is creating momentum toward utilizing waste feedstock in a myriad of applications. The paper industry is not an exception to this trend, and packaging products made from agricultural or agro-industrial residues are receiving more attention now than ever. Additionally, negative consumer perceptions of tree felling are accelerating the acceptance of these fibers. Nevertheless, adopting these residues raises the issue of whether they constitute a better alternative to fight climate change than wood. Answering this question is imperative to ensure that pledges to reduce carbon footprints across the industry are fulfilled. This paper aims to estimate the carbon footprint of corrugating medium and linerboard containing wheat straw and sugarcane bagasse pulp compared to analogous wood-based materials. The goal was also to understand how methodological decisions to allocate emissions to nonwood residues can affect the results. This study includes a life cycle carbon analysis spanning from cradle to grave, which comprises stages for residue production, pulping, paper-making, waste management, and corresponding transportation. For the proposed case study, the results suggest that straw- and bagasse-based medium and linerboard can present a higher carbon footprint than products made from virgin and recycled wood fibers. The main driver is the production of nonwood chemimechanical pulp. In addition, the lower capacity of nonwood residues to be recycled increases the overall impact. Finally, decisions around emissions allocation highly influence the results. This study helps mitigate part of the uncertainty around the environmental sustainability of corrugating medium and linerboard made from the selected nonwood residues.

Study on the Selectivity of Molecular Imprinting Materials Determined through Hydrogen Bonding on Template Molecular Structures of Flavonoids.

Molecular imprinting technology is widely used for the specific identification of compounds, but the selective recognition mechanisms of the same compounds still need to be further studied. Based on differences in hydrogen bond size and orientation, molecularly imprinted polymers (MIPs) were designed to adsorb flavonols with the same parent core and different hydroxyl groups. A surface-imprinted material was designed with silicon dioxide as the carrier, myricetin as the template molecule, and methacrylic acid (MAA) as the functional monomer. Scanning electron microscopy (SEM), Brunauer-Emmett-Teller surface area (BET) analyses, Fourier-transform infrared spectroscopy (FT-IR), and other characterization experiments were carried out. The intrinsic mechanism of the MIPs was also explored. The MIPs showed good adsorption of myricetin and other flavonoids through hydrogen bonding and steric hindrance. The adsorption capacity was 3.12-9.04 mg/g, and the imprinting factor was 1.78-3.37. Flavonoids with different hydroxyl groups in different numbers and directions had different hydrogen bond strengths with functional monomers. R2, R4, and R1 on 2-phenylchromogenone had stronger electronegativity, and the hydroxyl group was also more likely to form and have stronger hydrogen bonds. The hydroxyl negativity and the degree of steric hindrance of flavonoids played a major role in the recognition of molecularly imprinted materials. This study is of great significance for the synthesis of and selection of templates for analogous molecular imprinting materials.

Recycled or Bio-Based Solvents for the Synthesis of ZnO Nanoparticles: Characterization and Validation in Organic Solar Cells.

Among solution-processable metal oxides, zinc oxide (ZnO) nanoparticle inks are widely used in inverted organic solar cells for the preparation, at relatively low temperatures (<120 °C), of highly efficient electron-transporting layers. There is, however, a recent interest to develop more sustainable and less impacting methods/strategies for the preparation of ZnO NPs with controlled properties and improved performance. To this end, we report here the synthesis and characterization of ZnO NPs obtained using alternative reaction solvents derived from renewable or recycled sources. In detail, we use (i) recycled methanol (r-MeOH) to close the loop and minimize wastes or (ii) bioethanol (b-EtOH) to prove the effectiveness of a bio-based solvent. The effect of r-MeOH and b-EtOH on the optical, morphological, and electronic properties of the resulting ZnO NPs, both in solution and thin-films, is investigated, discussed, and compared to an analogous reference material. Moreover, to validate the properties of the resulting materials, we have prepared PTB7:PC71BM-based solar cells containing the different ZnO NPs as a cathode interlayer. Power conversion efficiencies comparable to the reference system (≈7%) were obtained, validating the proposed alternative and more sustainable approach.

Highly Selective and Efficient Perdeuteration of n‐Pentane via H/D Exchange Catalyzed by a Silica‐Supported Hafnium‐Iridium Bimetallic Complex

AbstractA Surface OrganoMetallic Chemistry (SOMC) approach is used to prepare a novel hafnium‐iridium catalyst immobilized on silica, HfIr/SiO2, featuring well‐defined [≡SiOHf(CH2tBu)2(μ‐H)3IrCp*] surface sites. Unlike the monometallic analogous materials Hf/SiO2 and Ir/SiO2, which promote n‐pentane deuterogenolysis through C−C bond scission, we demonstrate that under the same experimental conditions (1 bar D2, 250 °C, 3 h, 0.5 mol %), the heterobimetallic catalyst HfIr/SiO2 is highly efficient and selective for the perdeuteration of alkanes with D2, exemplified on n‐pentane, without substantial deuterogenolysis (&lt;2 % at 95 % conversion). Furthermore this HfIr/SiO2 catalyst is robust and can be re‐used several times without evidence of decomposition. This represents substantial advance in catalytic H/D isotope exchange (HIE) reactions of C(sp3)−H bonds.

Highly Selective and Efficient Perdeuteration of n-Pentane via H/D Exchange Catalyzed by a Silica-Supported Hafnium-Iridium Bimetallic Complex.

A Surface OrganoMetallic Chemistry (SOMC) approach is used to prepare a novel hafnium-iridium catalyst immobilized on silica, HfIr/SiO2, featuring well-defined [≡SiOHf(CH2 tBu)2(μ-H)3IrCp*] surface sites. Unlike the monometallic analogous materials Hf/SiO2 and Ir/SiO2, which promote n-pentane deuterogenolysis through C-C bond scission, we demonstrate that under the same experimental conditions (1 bar D2, 250 °C, 3 h, 0.5 mol %), the heterobimetallic catalyst HfIr/SiO2 is highly efficient and selective for the perdeuteration of alkanes with D2, exemplified on n-pentane, without substantial deuterogenolysis (<2 % at 95 % conversion). Furthermore this HfIr/SiO2 catalyst is robust and can be re-used several times without evidence of decomposition. This represents substantial advance in catalytic H/D isotope exchange (HIE) reactions of C(sp3)-H bonds.

Influence of varying carbon oxides concentrations on the selectivity of an electrical sensor utilizing graphene nanoribbons

We have considered a graphene nano ribbon-based two probe-device working on the principle of alteration of current-voltage (I–V) characteristic, upon interactions of its channel material with the adsorbed gas molecules. The analysis of sensing parameters alongside the electron transport mechanism was carried out by using density functional theory (DFT) formulated on the Hohenberg-Kohen paradigm in conjunction with the non-equilibrium green functions (NEGF) method. Electronic transport through similar work reported earlier reveals that the combination of these two techniques coordinates extremely well and yields convincing electronic results. The nanoribbon-based sensing device was employed to evaluate its capability to detect Carbon dioxide (CO2) and Carbon monoxide (CO) molecules. Analysis of the computed result reveals significant modifications in the electronic property of the device upon adsorption of carbon dioxide and carbon monoxide entities on the channel surface. One such significant and dramatic change in the characteristic that we observed is the nature of the channel that transforms from metallic to semi-metallic. Another observed change is the signal amplification capability relative to the pristine device. The signal gets amplified on increasing number of molecular entities from one to six.The transformation in sensor performance is additionally supported by examining variations in multiple parameters, including adsorption energy, charge transfer, differential resistance, and the figure of merit, also known as the peak-to-valley ratio (PVR). The investigation unveiled that the currently designed zigzag graphene nanoribbon (ZGNR) model exhibits high sensitivity to both CO2 and CO gases. This phenomenon is substantiated by the elevated adsorption energy, increased charge transfer, elevated peak-to-valley ratio (PVR), and heightened sensor response. The substantial sensor response, registering at a magnitude of 8.3, underscores the efficacy of the current system in detecting both low and high concentrations of CO and CO2 molecules. The current study emphasizes the notion that understanding the electronic and transport behaviour of zigzag graphene nanoribbons (ZGNR) and analogous materials could offer valuable insights for addressing the threat of environmental pollution.

The Effect of Die Material on the Crown Fracture Strength of Zirconia Crowns.

Determination of the eligibility of several tooth analog materials for use in crown fracture testing. A standardized premolar crown preparation was replicated into three types of resin dies (C&B, low modulus 3D printed resin; OnX, high modulus 3D printed resin composite; and highest modulus milled resin composite). 0.8 mm zirconia crowns were bonded to the dies and the maximum fracture load of the crowns was tested. Twelve extracted human premolars were prepared to a standardized crown preparation, and duplicate dies of the prepared teeth were 3D printed out of C&B. Zirconia crowns were bonded to both the dies and natural teeth, and their fracture load was tested. There was no statistical difference between the fracture load of zirconia crowns bonded to standardized dies of C&B (1084.5 ± 134.2 N), OnX (1112.7 ± 109.8 N) or Lava Ultimate (1137.5 ± 88.7 N) (p = 0.580). There was no statistical difference between the fracture load of crowns bonded to dentin dies (1313 ± 240 N) and a 3D-printed resin die (C&B, 1156 ± 163 N) (p = 0.618). There was no difference in the static fracture load of zirconia crowns bonded to standardized resin dies with different moduli or between a low modulus resin die and natural dentin die.

Interfacing as embodied practice: journeys between print, screen and beyond

ABSTRACT This paper develops a concept of interfacing as a heterogeneous zone of interaction, a relational space created by users as they bring together interact with and draw on a range of digital and analogue materials, sources and technologies. It examines the ways tourists and travellers access, engage, use, transfer and blend multiple media sources drawing across both analogue and digital sources as they plan, execute and reflect on the trips and visits they make. It derives from a series of in depth ‘show and tell’ style interviews with 18 participants recruited in the UK. It contributes to the growing literature on digital geographies by exploring the relational spatiality by which individuals build interfacing activities around specific tasks and experiences as heterogeneous and contingent socio-material spaces. It develops a conception of interfacing around two interrelated and iterative sets of embodied practices. These are firstly, assembling and mobilising and secondly intermediating and sense making. Using this twin conception of interfacing as an active making, the paper discusses how and where a conception of interfacing as embodied practice might contribute to understandings of human digital relationships within complex poly media situations and environments.

Open educational resources on preservation: An overview

In the last decade there have been many initiatives and projects that have dealt with open educational resources with the goal of making education more available and also of improving formal educational practices. The Erasmus+ project Digital Education for Crisis Situations: Times When There Is No Alternative is such an initiative and one of its planned intellectual outputs is to produce a new open educational resource on the preservation of analogue and digital materials. Planning and creating an open educational resource on preservation needs to be based on an understanding of the content that comprises the complex field of preservation. This also provides the basis for conducting research on the available open educational resources in this field. This article aims to provide an overview of the available open educational resources on preservation through an investigation of open educational resource platforms, finding open educational resources on preservation, and analysing them according to the theoretical background on preservation. This provides an understanding of what kinds of open educational resources exist in the field of preservation and also informs the way a new open educational resource should be created.

A sample preparation guide for clay‐rich carbonaceous chondrites

AbstractThe matrix of the C2‐ungrouped Tarda meteorite contains abundant smectite minerals that swell and crumble when exposed to polar liquids, causing the sample to rapidly slake. This phenomenon presents a serious challenge when polishing the meteorite, as common polishing liquids used on carbonaceous chondrites, such as water, ethanol, ethylene glycol, and isopropyl alcohol, are polar and will cause the sample to swell, making it unsuitable for some analyses. Hexane and mineral oil are nonpolar liquids that were found to not induce swelling on highly expansive montmorillonite‐clay analog material and were effectively integrated into a polishing procedure for Tarda. Here, we detail a procedure for mounting, cutting, and polishing the Tarda meteorite to prepare a surface that is suitable for a variety of sensitive techniques, such as electron microprobe analysis. This work offers a practical methodology for the preparation of other clay‐rich samples, which may include the recently returned Ryugu and Bennu materials.

Ab initio computation of low-temperature miscibility gap of V(Se,Te)2

Monolayers of quasi-binary transition metal dichalcogenides are a focus of attention as they are expected to exhibit many exciting physical properties, but not much is known about their thermodynamic stability. In this study, we use a combination of global energy landscape exploration, local minimization using density functional theory, and thermodynamic analysis, to compute the composition-temperature phase diagram of the quasi-binary V(Se,Te)2 system, both for a 2H monolayer and for the analogous bulk material. We find that the phase diagram exhibits a miscibility gap, with a critical temperature T c = 500 K and T c = 650 K for monolayer and bulk, respectively, indicating that the system prefers to form solid solution phases. In particular, at room temperature, the thermodynamically stable phase of the monolayer would correspond to a decomposition into two solid solution monolayers, with ca. 90% Se and Te content, respectively.

A physicochemical-sensing electronic skin for stress response monitoring.

Approaches to quantify stress responses typically rely on subjective surveys and questionnaires. Wearable sensors can potentially be used to continuously monitor stress-relevant biomarkers. However, the biological stress response is spread across the nervous, endocrine, and immune systems, and the capabilities of current sensors are not sufficient for condition-specific stress response evaluation. Here we report an electronic skin for stress response assessment that non-invasively monitors three vital signs (pulse waveform, galvanic skin response and skin temperature) and six molecular biomarkers in human sweat (glucose, lactate, uric acid, sodium ions, potassium ions and ammonium). We develop a general approach to prepare electrochemical sensors that relies on analogous composite materials for stabilizing and conserving sensor interfaces. The resulting sensors offer long-term sweat biomarker analysis of over 100 hours with high stability. We show that the electronic skin can provide continuous multimodal physicochemical monitoring over a 24-hour period and during different daily activities. With the help of a machine learning pipeline, we also show that the platform can differentiate three stressors with an accuracy of 98.0%, and quantify psychological stress responses with a confidence level of 98.7%.

Cohesion and shear strength of compacted lunar and Martian regolith simulants

Shear strength and cohesion of granular materials are important geotechnical properties that play a crucial role in the stability and behavior of lunar and Martian regolith, as well as their terrestrial analog materials. To characterize and predict shear strength and cohesion for future space missions, it is also important to understand the effects of particle size distribution and density on these fundamental geotechnical properties. Generalized equations have been established using empirical data from direct shear measurements of lunar and Martian regolith simulants to quantify the effects of particle size distribution and density on cohesion and shear strength. Preliminary results are also presented highlighting the effects of atmospheric absorbed water on shear strength and cohesion when conducting experiments in atmospheric conditions on Earth. The results of this study show that cohesion increases exponentially with bulk density, while the exponential growth constant is also dependent on particle size distribution. The presence of absorbed atmospheric water can also produce non-monotonic effects on the shear strength of regolith, and it's influence on shear strength varies based on sample density for Earth-based experiments and applications. Together, these results highlight the importance of particle size distribution, bulk density, and atmospheric water content on the shear strength and cohesion of lunar and Martian simulants. This study also establishes generalized equations for predictive, testing, and modeling efforts for future space missions.

Insights Into Modern Undergraduate Ultrasound Education: Prospective Comparison of Digital and Analog Teaching Resources in a Flipped Classroom Concept - The DIvAN Study.

Purpose Sonography training has become an important part of university medicine courses. This study explores the impact of digital and analog teaching resources on learning outcomes, knowledge retention, and student preferences and motivation in a flipped classroom setting. Materials and Methods This prospective controlled study involving two groups of third-year medical students included a voluntary three-day compact ultrasound course given in a flipped classroom, comprising 26 teaching units of 45 minutes each. Hardcopy lecture notes (control group) and E-learning (study group) were used as teaching resources. Evaluations were conducted before (pre) and during the preparation phase (intermediate), and after (post) the face-to-face course. Likert scale responses, written theory tests with very short answer questions (Theorypre, Theoryinter, Theorypost), and practical examinations (Practiceinter, Practicepost) were used for student self-assessment and to measure attitude, motivation, as well as theoretical and practical skills. Results A total of N=236 complete data sets (study group n=136; control group n=100) were analyzed. Both groups showed an equivalent initial level of, and a continuous and significant (p<0.01) increase in, subjective and objective skills over the evaluated time frame. The study group achieved significantly (p<0.05) better results in Theoryinter, Theorypost, Practiceinter, and Practicepost. The study group evaluated their teaching resource and the training concept significantly (p<0.05) better. Conclusion The integration of digital resources into sonography education provides comparable learning outcomes to traditional analog materials, enhancing the preparatory phase. In the future, digitally supported training should be used more.

메이커 기반 비구조화된 문제해결 활동에서 초등학생의 경험의 의미 탐색

This study utilized qualitative research methods to investigate the experiences and learning outcomes of fifth-grade elementary school students engaged in making activities using analog materials and tools to solve open-ended problems. The students worked in groups to design a vehicle capable of traveling a distance of 1 meter with no restrictions on materials or structure. The study involved 23 students and their teachers, with data collected through student interviews, student artwork, classroom teacher observation journals, and teacher interviews. Transcribed interviews were categorized and interpreted for significance. The findings are categorized into problem-solving processes and the experiential semantics of open problem-maker activities.&#x0D; The subsequent findings highlight the significance of maker-based, unstructured problem-solving activities for elementary school students. Firstly, students encountered diverse transportation forms and engaged in problem-solving within unstructured activities that allowed for decision-making and choice. Secondly, their encounters with various symbols exhibited openness, complexity, realism, and continuity. Thirdly, students expressed a strong desire for learning through their engagement in tactile thinking and interaction with their environment.&#x0D; In conclusion, unstructured problem-solving activities foster student choice, reasoning, and communication and offer learning opportunities through failure. Moreover, learning is viewed as a continuous journey rather than a destination, with learners' individual differences and experiences significantly shaping new learning.

Improving the Electronic Conductivity of Alluaudite Na2.5Fe1.75(SO4)3 Cathodes for Na-Ion Batteries

The increasing dependency on batteries in modern technology has led to an ever-increasing demand that cannot be met by Li-ion batteries (LIBs) alone. The push towards using renewable energy and electric vehicles, coupled with the limited reserves of lithium resources is encouraging research into alternative options for electrochemical storage devices. Na-ion batteries (SIBs) are a promising alternatives due to the similarity of their chemistry to LIBs. This allows for utilisation of analogous materials and methods already in place for LIBs. Furthermore, SIBs are more economically viable and environmentally sustainable due to the abundance of the elements that can be utilised as electrode active materials. For example, SIB cathodes, such as Na2.5Fe1.75(SO4)3, can be synthesised from precursor materials that are widely available by-products of industry. The polyanionic framework of Na2.5Fe1.75(SO4)3 has three 3-dimensional vacancies within it, in which Na-ions de/intercalate.[1] However, the performance of Na-ion batteries is hindered by the low electronic conductivity of these polyanionic compounds, affecting the flow of electrons through the material and the reversible movements of the Na ions.[2] To address this issue, previous reports have shown that using a conductive additive such as carbon black and graphene oxides can increase the electronic conductivity of Na ion cathode materials and improving battery performance.[3]In this work, we investigate a non-stoichiometric alluaudite phase Na2.5Fe1.75(SO4)3 material (NFS), produced by a ball-milling-assisted solid-state synthesis. A study of the effects of variables on the ball milling process using the was carried out. A multi-step process involving a repetition of the ball milling and annealing was used to decrease particle size and eliminate impurities. The results were compared regarding particle size, impurities present, conductivity and battery performance. The obtained materials were characterised using X-ray diffraction, scanning electron microscopy and electrochemical impedance spectroscopy. The materials were tested as cathodes in sodium half-cells with 1 mol/L NaClO4 in ethylene carbonate (EC)/ propylene carbonate (PC) electrolyte. The additional ball milling and annealing steps saw a significant decrease in impurities present across all variations in methodology. All batteries show three redox peaks in their differential capacity plots, demonstrating that all three vacancies within the polyanionic framework of Na2.5Fe1.75(SO4)3 are active during charge and discharge. The best performing electrode achieved a capacity of 80 mAh/g using only C45 as a conductive additive. These are promising results that are expected to improve with further studies researching the addition of RGOs and MXenes into the ball milling process. These composite electrodes will be prepared by combining rGOs/MXenes with the NFS precursors during the synthesis process of Na2.5Fe1.75(SO4)3 to enhance battery performance further.

SiO2 Nanoparticle Coating to Enable Polyethylene-Based Na-Ion Battery Separators

The increasing demand for Li-ion batteries (LIBs), pushed even more by the electrical vehicle industry, has highlighted the concern with the scarcity and uneven distribution of LIB raw materials. Electrochemical energy storage based on alternative chemistries, once properly developed, may provide sufficient energy density to partly supply that demand, reducing the dependence on Li natural reserves. Among the studied chemistries, Na-ion-based storage is currently attracting a lot of research attention. This is partly due to the similarities between Li and Na, which allow for the utilisation of analogous materials and methods already in place for LIBs. However, not every component of LIBs can be directly applied to Na-ion batteries (SIB).[1] This is the case for battery separators, the membranes used to avoid physical contact between the two battery electrodes to prevent short circuiting while conducting ions from one battery pole to the other. Porous polyolefin films, such as polyethylene (PE) and polypropylene (PP), have been successfully used in LIBs, but are not compatible with SIB electrolytes. In the latter case, issues arise from the poor wettability of the separator with the electrolyte, which leads to low ionic conductivity, and creates an uneven flux of ions that can cause cell failure. To address this issue, previous reports have shown that the presence of inorganic oxides such as ZrO2 [2] and SiO2 [3] on polyolefin films can increase the affinity of the separator with commonly used LIB and SIB electrolytes. Moreover, ceramic-modified films also show higher thermal stability and hindered thermal shrinkage, which improves battery safety.In this work, we investigated PE coated with spherical SiO2 particles (designed by Glantreo, Ireland) with different sizes of 85 and 200 nm. The coatings were made by tape casting both sides of a PE film with slurries containing SiO2 particles and a binder. Binder type, SiO2 concentration and SiO2/binder ratio were optimized for each particle size. The obtained films were characterized by scanning electron microscopy and infrared spectroscopy, and were compared regarding their wettability, thermal stability, and ionic conductivity. The films were tested as separators in hard-carbon half-cells with 1 mol/L NaClO4 in either diethylene glycol dimethyl ether (DEGDME) or ethylene carbonate (EC)/ propylene carbonate (PC) electrolyte. With carbonate-based electrolyte, PE has very low wettability and cells short circuit within the first cycle. However, SiO2-PE samples showed higher wettability, which allowed for cycling at low current densities. In DEGDME-based electrolyte, cells with PE separator presented capacity fade, with 50% capacity loss after 250 cycles at 400 mA/g. On the other hand, cells with SiO2-PE separator had stable cycling for more than 300 cycles and no short-circuiting was observed, even when high active mass loading electrodes (8 mg/cm2) were used. These are promising results showing that a surface layer of SiO2 particles can make PE a viable option for SIB separators.