Low Diffusion Research Articles

Additive manufacturing of sustainable and heat-resistant Al-Fe-Mo-Si-Zr alloys

Improving the sustainability of metals and alloys is essential for slowing down global warming. The reason is that their extraction and production stand for about 40% of all greenhouse gas emissions in the industrial sector. This motivates new alloy design and processing criteria such as the (1) preferred use of abundant and sustainable alloying elements and (2) improved material tolerance against impurity intrusion from recycling. In this context, additive manufacturing (AM) is attractive, through rapid solidification, capable of quenching impurities into a solid solution state, avoiding formation of large intermetallics and introduction of metastable phases. Here, by using this approach we show how iron, an important scrap-related contaminant in aluminum alloys, can be turned from a harmful into a valuable ingredient. Specifically, the addition of Mo and Si facilitates the formation of beneficial metastable body-centred cubic (BCC) Al12(Fe, Mo)3Si phase, instead of more stable but detrimental intermetallic variants commonly observed in Al-Fe alloys. The as-built microstructures have excellent thermal stability, tested up to 200hours at 300 °C, because of low diffusivity of Fe and the formation of Zr shell. We find that for such supersaturated alloys, two issues are important, namely (a) the heterogeneous microstructures in the as-built condition, (b) the evolution of metastable precipitates during heating. We suggest that this type of approach help to guide sustainable alloy design via AM and other rapid solidification processes.

Research on the properties of brucite-based magnesium phosphate cement fire resistive coating for steel structures

Magnesium Phosphate Cement (MPC) exhibits high strength, exceptional high-temperature resistance, and outstanding adhesion properties at the steel interface, rendering it an ideal material for fire resistive coatings on steel structures. In this study, natural brucite powder was employed as the magnesium source, while hollow glass microspheres (HGM) were utilized as functional modifiers to formulate brucite-based MPC fire resistive coatings for steel structures. This research explored the influence of the mass ratio of brucite powder to ammonium dihydrogen phosphate (M/P), the brucite particle size, and the addition of HGM on the physical, mechanical, and fire-retardant properties of the coatings. The microstructure of the brucite-based MPC before and after fire testing was examined using SEM, XRD, TG-DTG, and X-CT. The results indicated that with an M/P ratio of 2.5:1 and a brucite particle size of 75–150 μm, the material exhibited optimal overall performance and was suitable as a matrix material for MPC. The incorporation of an appropriate amount of HGM increased the compressive strength of brucite-based MPC by 33.4 %, reduced the dry density by 20.5 %, extended the fire resistance of the structure, and decreased the thermal conductivity by 48.2 %. This can be attributed to: (i) HGM filling the pores in brucite-based MPC, creating a denser microstructure; (ii) HGM forming a closed porous structure with the MPC matrix, reducing thermal conductivity and increasing thermal resistance; (iii) The low thermal diffusivity of HGM/MPC impeded heat transfer, thereby decelerating thermal decomposition and flame propagation.

Fluidic Interface for Surface-based DNA Origami Studies.

Traditionally, the use of DNA origami nanostructures (DONs) to study early cell signaling processes has been conducted using standard laboratory equipment with DONs typically utilized in solution. Surface-based technologies simplify the microscopic analysis of cells treated with DON agents by anchoring them to solid substrates, thus avoiding the complications of receptor-mediated endocytosis. A robust microfluidic platform for real-time monitoring and precise functionalization of surfaces with DONs was developed here. The combination of controlled flow conditions with an upright total internal reflection fluorescence microscope enabled the kinetic analysis of the immobilization of DONs on DNA-functionalized surfaces. The results revealed that DON morphology and binding tags influence the binding kinetics and that DON hybridization on surfaces is more effective in microfluidic devices with larger-than-standard dimensions, addressing the low diffusivity challenge of DONs. The platform enabled the decoration of DONs with protein-binding ligands and in situ investigation of ligand occupancy on DONs to produce high-quality bioactive surfaces. These surfaces were used to recruit and activate the epidermal growth factor receptor (EGFR) through clustering in the membranes of living cancer cells (MCF-7) using an antagonistic antibody (Panitumumab). The activation was quantified depending on the interligand distances of the EGFR-targeting antibody.

Harnessing MBene termination for superior anode interfaces in Li/Ca-ion batteries

The elevation of two-dimensional (2D) transition metal borides, specifically MBenes, as anode materials for lithium-ion batteries (LIBs) and calcium-ion batteries (CIBs) can be achieved through strategic functionalization with appropriate groups. Utilizing a first-principles approach, we conducted an in-depth investigation into the electrochemical properties of chlorine-terminated V2B (V2BCl2) as a candidate anode material for LIBs and CIBs. V2BCl2 exhibits metallic behavior, as demonstrated by band structure analysis, which endows it with exceptional conductivity due to the free electron surface of the system, thereby embodying ideal anode characteristics. The dynamic and thermal stability of the system was assessed through comprehensive phonon dispersion analyses and ab-initio molecular dynamics (AIMD) calculations. High net charge transfer rates of Li/Ca ions towards the monolayer, augmented electron localization function (ELF) near system atoms, and the presence of ionic bonds between Ca/Li and the V2BCl2 monolayer contribute to the enhanced conductivity observed in these anode systems. This is corroborated by metrics such as the projected crystal orbital Hamiltonian population (-pCOHP), low diffusion energy barriers (< 0.35 eV) facilitating rapid charging mechanisms, and low open circuit voltages (< 0.32 V) ensuring robust battery performance stability. Furthermore, V2BCl2 exhibits notable specific storage capacities of 875.67 mAh g−1 for Ca ions and 1167.75 mAh g−1 for Li ions, surpassing the benchmarks set by recent MBene systems. These promising results strongly advocate for V2BCl2 as a viable candidate for anode material in both LIB and CIB applications, highlighting its potential significance in advancing battery technology.

Unraveling the enhanced sodium-storage mechanism in a strongly bonded 2D honeycomb borophene/boron phosphide heterostructure

The growing modern demand for battery capacity is driving the development of high-capacity metal-ion battery anodes for future energy storage. Two-dimensional (2D) material-based heterostructures have shown advantages as alternative anodes due to their enhanced adsorption capacity. The lightweight nature of honeycomb borophene (HB) is beneficial for serving as a high-capacity anode but is constrained by structural instability arising from electron deficiency. In this study, using first-principles calculations, we propose a HB/boron phosphide (BP) heterostructure as an anode for both lithium-ion batteries and sodium-ion batteries (SIBs). The heterostructure engineering not only stabilizes the HB structure but also leads to a bonding heterostructure instead of common van der Walls type. The HB/BP demonstrates robust structural stability and reversibility when multiple ions are stored. In addition, the HB/BP offers stable storage sites and low diffusion barriers for lithium (0.31 eV) and sodium (0.28 eV), indicating rapid charging–discharging performance. Notably, the predicted maximum sodium storage capacity reaches 2402 mAh/g, surpassing that of the constituent monolayers and most 2D heterostructures. The underlying mechanism for high storage capacity is elucidated through detailed charge image model analysis, offering atomistic-scale insights for constructing high-capacity anodes. All results suggest that the presented HB/BP is a promising anode candidate for SIBs and opens an avenue for stabilizing HB in energy storage.

Study on an Interpenetrating Artificial SEI for Lithium Metal Anode Modification and Fast Charging Characterization.

Artificial SEI is one of the effective strategies to improve lithium dendrites and suppress side reactions. However, the role of SEI components and distribution on the modification of the lithium metal anode remains unclear. Therefore, in this study, the oxygen-sulfur (O-S) component and its distribution in SEI were modulated by designing experiments, and then the mechanism of its action was deeply investigated. The study is based on an in-depth analysis of the properties of lithium sulfide (Li2S) and lithium oxide (Li2O) as SEI layer materials and effectively combines them in an ether electrolyte environment to form an innovative SEI structure. The experimental results show that the optimal SEI modulation condition is O120-S10. O120-S10 significantly improves the kinetic performance of electrochemical reactions, reduces the film resistance, and achieves cycling stability of up to 2100 h during high-capacity lithium deposition/stripping at 5 mAh cm-2. When used in conjunction with a ternary cathode material (NCM811), the O120-S10 demonstrates excellent performance under high rate charge/discharge conditions at 10C. After 1500 cycle tests, the battery's specific capacity was maintained at 90 mAh g-1 and the Coulombic efficiency reached 98.52%. Through X-ray photoelectron spectroscopy (XPS) analysis, the vertical structure and ratio distribution of components in SEI were revealed in detail, and the optimal component ratios of Li2S 46.48%, Li2O 46.02%, and Li2CO3 7.50% were determined. The mechanism of action is to achieve a 1 + 1 > 2 superlinear synergistic effect and fast charging performance by combining the ability of Li2O's low lithium ion diffusion barrier with Li2S's ability to inhibit the growth of lithium dendrites.

A novel Ta-contained TiAl alloy with excellent high temperature performance designed for powder hot isostatic pressing

TiAl alloys offer strong potential for replacing conventional nickel-base alloys in structural applications at high temperatures, which requires good high temperature performance. This study analyzes the creep performance and thermal exposure characteristics for a powder hot isostatic pressing (P-HIP) Ta-contained TiAl alloy. The microstructure characteristics, creep performance, and thermal exposure properties of the nearly lamellar (NL) alloy with a size of about 145 μm were investigated. The alloy remains 0.72 % fracture strain at room temperature after exposure at 750 ℃ for 1000 h. The fitting results of creep curves show that the creep stress index n is 15.82 at 750 ℃, indicating the power law creep mechanism. By reducing the interfacial energy, Ta can facilitate the formation of metastable structures and achieve refinement. The enrichment of Ta element at the lamellar edge, both observed after thermal exposure and creep, inhibits the growth of lamellae and hinders the expansion of cavities due to its low diffusion rate, improving the thermal stabilities and creep performance. The P-HIP Ta-contained TiAl alloy shows exciting high temperature performance.

The role of crystallographic orientation on surface properties and ion transport in lithium germanate (Li2GeO3) anodes: A computational approach

The performance of lithium-ion batteries (LIBs) hinges on the surface properties of their anodes. Compared to the bulk material, the anode surface is more susceptible to environmental changes during lithium (Li) intake and release, directly impacting factors like capacity, cycling stability, and charge/discharge rates. Lithium germanate (Li2GeO3, LGO) has emerged as a promising anode material due to its fast Li-ion conduction. While numerous studies have explored performance improvements through various methods, including defect engineering. However, there is currently a lack of atomistic-level understanding of the surface structure. Consequently, despite the importance of precisely understanding the surface to manipulate its different properties, specific surface details of LGO remain unclear. This knowledge gap hinders precise manipulation of surface properties for optimal performance.This study addresses this critical need by employing theoretical calculations to predict the structural, electrochemical characteristics, and Li-ion transport behavior in LGO surfaces. Our results indicate that polar surfaces exhibit lower formation energies compared to non-polar surfaces. Further investigation revealed that Li-terminated surfaces possess the lowest surface energy among various surface terminations. Interestingly, the work function calculations displayed an opposite trend to surface formation energy, with polar surfaces exhibiting the lowest work function values.To explore Li-ion transport, we employed ab initio molecular dynamics simulations. Notably, the (003) surface displayed the highest Li-ion diffusion rate among all considered surfaces.Further analysis of the (001) surface, which exhibited similar diffusion pathways to the (003) surface, revealed a lower diffusion rate.To understand this disparity, nudged elastic band (NEB) simulations were used to estimate the energy barriers for Li-ion migration along each pathway in both structures. Despite sharing similar pathways, the energy barriers in the (003) surface were significantly lower than those in the (001) surface. This finding suggests that the intrinsic energy landscape of the surface plays a crucial role in dictating Li-ion transport behavior.

Defect-rich hard carbon designed by heteroatom escape assists sodium storage performance for sodium-ion batteries

Sodium-ion batteries (SIBs) avoids the use of expensive cobalt element, and the abundance of sodium element is high, so it shows great application potential, and the development of sodium-ion battery materials is of great value. Biomass precursors have the advantages of low cost and widely and sufficiently distributed resources, and embody the environmental concept of waste utilization, however, the poor reversible specific capacity and initial coulombic efficiency (ICE) of pristine corn stover-derived hard carbons (CSHCs) limit their practical application value. In this paper, we propose a method to increase the reversible specific capacity of hard carbon and maintain high ICE, introduce heteroatoms into graphene-like nanosheets at low carbonization temperature, then escape heteroatoms through high pyrolysis temperature, create defects in the graphene-like carbon layer and expand the (002) layer spacing. Density functional theory (DFT) calculations show that defects are beneficial to the adsorption of Na+ on graphene-like nanosheets, and Na+ have a lower diffusion barrier between layers rich in defects and extended (002) layer spacing. Compared with the conventional low pyrolysis temperature heteroatom doping process, the present method exhibits superior ICE. In the ester-based electrolyte, the modified hard carbon (D-CSHC) exhibits a superior specific capacity of 284.5 mAh/g and an ICE of 85.9 % as compared to the pristine corn stover-derived hard carbon (233.5 mAh/g, 72.7 %). In addition, the capacity retention rate was 92.6 % after 500 turns of constant current cycles at 0.15 A/g.

Advancing Zn-ion Battery Electrodes: Exploring the Potential of Graphene-Polythiophene Nanocomposites through First-Principles Analysis

AbstractThis research investigates the electronic and electrochemical properties of graphene-polythiophene (G/Pth) nanocomposites, as potential anode materials for Zn-ion batteries. By capitalizing on the distinctive attributes of these constituent materials, the research aims to unravel critical aspects, such as: interaction studies, electronic structure, charge transfer, charge density difference, the density of states (DOS), theoretical specific capacity, open circuit voltage, Zn-ion diffusion, and the structural stability of G/Pth. The findings present compelling insights into the adsorption process, revealing an exothermic adsorption energy of -2.79 eV and an adsorption height of 3.51 Å for the polythiophene onto the graphene nanosheets. The loading of Zn atoms onto the G/Pth nanocomposite, yields a noteworthy maximum specific capacity of 585 mAh/g. The nanocomposite exhibits an exceptionally low Zn diffusion barrier of 6 meV, thereby, facilitating a swift Zn diffusion across its surface. These results suggest the promising potential of G/Pth nanocomposites as anode materials for Zn-ion batteries, and hence, providing valuable insights into their electronic and structural properties. It is believed that this study, has significantly, contributed to the advancement of the comprehension of polymer substrate-based energy storage materials. Also, it establishes a foundation for further research to develop more effective and efficient solutions for energy storage in Zn-ion batteries. Graphical Abstract

Selective regulation of nanosheets inside or outside carbon nanoboxes for advanced supercapacitors

Rational structure control is an effective route to boost electrochemical performance of energy storage materials and devices. Confining composite materials with core–shell structure in hollow carbon nanomaterils is challenging and valuable in the field of energy storage. Herein, driving inward formation of core–shell structured Fe3O4@MnO2 in hollow carbon nanoboxes is achieved for superior supercapacitor electrodes. It’s found that when small Fe3O4 nanoparticles are reserved in carbon nanoboxes in advance, the MnO2 nanosheets only grow on the internal Fe3O4 nanoparticles to form Fe3O4@MnO2 core–shell structure in the carbon nanoboxes (Fe3O4@MnO2@C NBs) or only on the outer shell of carbon nanoboxes (Fe3O4@C@MnO2) or on both Fe3O4 nanoparticles and the carbon shell (Fe3O4@MnO2@C@MnO2), which can be selectively regulated. The density functional theory (DFT) calculation reveals that Fe3O4@MnO2@C NBs have higher conductivity, higher adsorption energy and lower diffusion energy barrier for sodium ions due to the core–shell structure of Fe3O4@MnO2 in carbon nanoboxes, which could promote the reaction kinetics efficiently. The asymmetric quasi-solid supercapacitor based on Fe3O4@MnO2@C NBs electrode achieves an energy density of 49.75 Wh kg−1 at a power density of 820 W kg−1 and demonstrates excellent stability. The route may provide a method for achieving complex internal structure control in hollow carbon material to enhance the electrochemical properties.

Differences in brain structure and cognitive performance between patients with long-COVID and those with normal recovery

BackgroundThe pathophysiology of protracted symptoms after COVID-19 is unclear. This study aimed to determine if long-COVID is associated with differences in baseline characteristics, markers of white matter diffusivity in the brain, and lower scores on objective cognitive testing. MethodsIndividuals who experienced COVID-19 symptoms for more than 60 days post-infection (long-COVID) (n = 56) were compared to individuals who recovered from COVID-19 within 60 days of infection (normal recovery) (n = 35). Information regarding physical and mental health, and COVID-19 illness was collected. The National Institute of Health Toolbox Cognition Battery was administered. Participants underwent magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI). Tract-based spatial statistics were used to perform a whole-brain voxel-wise analysis on standard DTI metrics (fractional anisotropy, axial diffusivity, mean diffusivity, radial diffusivity), controlling for age and sex. NIH Toolbox Age-Adjusted Fluid Cognition Scores were used to compare long-COVID and normal recovery groups, covarying for Age-Adjusted Crystallized Cognition Scores and years of education. False discovery rate correction was applied for multiple comparisons. ResultsThere were no significant differences in age, sex, or history of neurovascular risk factors between the groups. The long-COVID group had significantly (p < 0.05) lower mean diffusivity than the normal recovery group across multiple white matter regions, including the internal capsule, anterior and superior corona radiata, corpus callosum, superior fronto-occiptal fasciculus, and posterior thalamic radiation. However, the effect sizes of these differences were small (all β<|0.3|) and no significant differences were found for the other DTI metrics. Fluid cognition composite scores did not differ significantly between the long-COVID and normal recovery groups (p > 0.05). ConclusionsDifferences in diffusivity between long-COVID and normal recovery groups were found on only one DTI metric. This could represent subtle areas of pathology such as gliosis or edema, but the small effect sizes and non-specific nature of the diffusion indices make pathological inference difficult. Although long-COVID patients reported many neuropsychiatric symptoms, significant differences in objective cognitive performance were not found.

Morphological control of bicontinuous phase-separated patterns by preparing mixed monolayers using non-amphiphilic s-triazine derivatives with three fluorinated chains

In this study, the morphogenesis of the bicontinuous phase separation in mixed monolayers of a non-amphiphilic fluorocarbon derivative without a hydrophilic group and long-chain fatty acids is discussed. These fluorocarbon derivatives contain an s-triazine ring and three fluorocarbon chains. The corresponding fluorocarbon derivatives exhibit high crystallinity in the monolayers, allowing them to maintain crystalline regularity even in the "sea" region of the mixed monolayer that exhibits phase separation. In controlling the bicontinuous pattern, the formation of complex phase-separated morphology in the mixed system of fluorine-based derivatives and comb polymers, along with the high concentration and low diffusion conditions in the mixed hydrocarbon/fluorocarbon system, were examined. It was observed that the condensed phase domains became angular shape at a low temperature (5 °C), and the surface approached a bicontinuous feature at a high temperature (40 °C). With the formation of hydrogenated condensed domains, the "sea" region of fluorocarbon chains lost its order. At this point, the shape of the nanodomains tended to become more circular.

Towards MnN as a replacement for IrMn

There is an urgent need to identify new antiferromagnetic materials that offer a replacement for IrMn alloys for room temperature and above applications. This is driven by the scarcity and high cost of Ir. Recently, MnN with {002} texture grown on a Ta seed layer has been proposed as a cost-effective alternative. However, two key issues need to be addressed before this material can be considered a realistic alternative to IrMn: thick layers of approximately 30 nm are required due to its relatively low magnetocrystalline anisotropy and nitrogen diffusion into the Ta layer at relatively low temperatures results in poor temperature performance. In this work, we show a potential pathway to overcome these issues. By using a W rather than a Ta seed layer, N diffusion is minimized, if not eliminated, at temperatures exceeding 300∘C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$300\\,^{\\circ }\\hbox {C}$$\\end{document}. Furthermore, preferential {111} growth is achieved and a significantly enhanced anisotropy, 2.6·106erg/cm3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$2.6 \\cdot 10^{6}\\,\\hbox {erg}/\\hbox {cm}^{3}$$\\end{document}, has been measured. This value is almost identical to that measured for 3D randomly oriented IrMn.

Evolution of interface voids and columnar grains of the FeCrAl/RAFMs HIP bonding joint

Hot Isostatic Pressing (HIP) diffusion bonding of FeCrAl and reduced-activation ferritic/martensitic steels (RAFMs) is a novel method for preparing the tritium permeation barrier (TPB) in nuclear fusion reactors. This study primarily investigates the formation mechanisms and evolution of interfacial voids and columnar grains under different bonding temperatures and post-welding heat treatment (PWHT) conditions. It is found that increasing bonding temperature facilitates element diffusion, leading to the closure of interfacial voids. Decarbonization of RAFMs and the increase in Cr content facilitates the formation of interfacial columnar grains, with C playing a crucial role in this process due to its lower diffusion activation energy than Cr. Although appropriate PWHT can reduce the size of interfacial columnar grains, it cannot entirely diminish them. The FeCrAl/IPFs joint effectively prevents the formation of brittle (Cr, C) compounds and interfacial AlN defects. After HIP (1050 °C) + PWHT (750 °C), the joint achieves high tensile strength and ductility both at room temperature and 300 °C. The enhancement in ductility is primarily attributed to the high Schmid factor of interfacial columnar grains, which facilitated the activation of the primary slip system under tensile load, resulting in a high elongation of joints.

Characterization of ferrous-xylenol orange-polyvinyl alcohol gel for gamma dosimetry using spectroscopy

Abstract Fricke gel dosimeters are appropriate candidates for gamma dosimetry. Polyvinyl alcohol Fricke gel dosimeters are the most recent introduced gel dosimeters which have low ion diffusion. In this work, samples of ferrous-xylenol orange-polyvinyl alcohol gel dosimeters were prepared and characterized using optical spectroscopy. Using win XCOM program and the elemental composition of the gel, the mass attenuation coefficients for photons were evaluated. The results exhibited that the prepared gel is the nearly radiological blood-, soft tissue- and water-equivalent. The 60Co gamma cell unit was used to irradiate the gel samples. A dose range response was found linear from 10 to 30 Gy and suitable for blood irradiation dosimetry. Additionally, the gel response good repeatability was confirmed by the coefficient of variation calculations. Furthermore, chemical yield of the gel was estimated to be 34.6. The good characteristics of the prepared gel make it appropriate for dosimetry of blood irradiators.

White matter microstructural and inflammation-based subgroups in bipolar disorder II depression differentiate in depressive and psychotic symptoms

BackgroundElevated inflammation and impaired white matter (WM) microstructure have been observed in bipolar disorder (BD). The link between inflammation, WM integrity, and psychiatric symptoms in BD-II depression (BDII-D) remains unknown. We aimed to define BDII-D subgroups through the interplay of inflammation and WM microstructure, and to explore differences in psychiatric symptoms between subgroups, thus offering insight into elucidating the explanatory measures linked to BDII-D. MethodsWM differences were compared between 146 BDII-D individuals and 151 health controls (HCs) by Tract-Based Spatial Statistics. Partial correlation with multiple comparison corrections was used to explore associations between WM, inflammation, and psychiatric symptoms. The canonical correlation analysis metrics of WM and inflammation followed by k-means clustering were used to define WM microstructural-inflammation subgroups of BDII-D. The differences in clinical profiles were compared between the subgroups. ResultsCompared with HCs, BDII-D showed significant WM alterations in the anterior thalamic radiation (ATR), cingulum, forceps, and inferior fronto-occipital fasciculus. In BDII-D, lower fraction anisotropy (FA) within the right ATR and cingulum were significantly associated with higher interleukin-6, while lower FA in the cingulum and lower axial diffusivity in the forceps major exhibited significant links with higher C-reactive protein. Among the subgroups identified, subgroup II characterized by elevated inflammation and impaired WM integrity displayed greater psychiatric symptoms. ConclusionsWM alterations are concentrated in emotional neurocircuits and are linked to inflammation in BDII-D. WM-inflammation subgroups exhibit distinct variations in psychiatric symptoms. Thus, WM alterations and inflammation might be an explanatory process in the pathophysiology of BDII-D.

SnF2-Catalyzed Lithiophilic-Lithiophobic Gradient Interface for High-Rate PEO-Based All-Solid-State Batteries.

Polyethylene oxide (PEO)-based all-solid-state lithium metal batteries (ASSLMBs) are strongly hindered by the fast dendrite growth at the Li metal/electrolyte interface, especially under large rates. The above issue stems from the suboptimal interfacial chemistry and poor Li+ transport kinetics during cycling. Herein, a SnF2-catalyzed lithiophilic-lithiophobic gradient solid electrolyte interphase (SCG-SEI) of LixSny/LiF-Li2O is in situ formed. The superior ionic LiF-Li2O rich upper layer (17.1 nm) possesses high interfacial energy and fast Li+ diffusion channels, wherein lithiophilic LixSny alloy layer (8.4 nm) could highly reduce the nucleation overpotential with lower diffusion barrier and promote rapid electron transportation for reversible Li+ plating/stripping. Simultaneously, the insoluble SnF2-coordinated PEO promotes the rapid Li+ ion transport in the bulk phase. As a result, an over 46.7 and 3.5 times improvements for lifespan and critical current density of symmetrical cells are achieved, respectively. Furthermore, LiFePO4-based ASSLMBs deliver a recorded cycling performance at 5 C (over 1000 cycles with a capacity retention of 80.0 %). More importantly, impressive electrochemical performances and safety tests with LiNi0.8Mn0.1Co0.1O2 and pouch cell with LiFePO4, even under extreme conditions (i.e., 100 °C), are also demonstrated, reconfirmed the importance of lithiophilic-lithiophobic gradient interfacial chemistry in the design of high-rate ASSLMBs for safety applications.

SnF2‐Catalyzed Lithiophilic–Lithiophobic Gradient Interface for High‐Rate PEO‐Based All‐Solid‐State Batteries

AbstractPolyethylene oxide (PEO)‐based all‐solid‐state lithium metal batteries (ASSLMBs) are strongly hindered by the fast dendrite growth at the Li metal/electrolyte interface, especially under large rates. The above issue stems from the suboptimal interfacial chemistry and poor Li+ transport kinetics during cycling. Herein, a SnF2‐catalyzed lithiophilic‐lithiophobic gradient solid electrolyte interphase (SCG‐SEI) of LixSny/LiF‐Li2O is in situ formed. The superior ionic LiF‐Li2O rich upper layer (17.1 nm) possesses high interfacial energy and fast Li+ diffusion channels, wherein lithiophilic LixSny alloy layer (8.4 nm) could highly reduce the nucleation overpotential with lower diffusion barrier and promote rapid electron transportation for reversible Li+ plating/stripping. Simultaneously, the insoluble SnF2‐coordinated PEO promotes the rapid Li+ ion transport in the bulk phase. As a result, an over 46.7 and 3.5 times improvements for lifespan and critical current density of symmetrical cells are achieved, respectively. Furthermore, LiFePO4‐based ASSLMBs deliver a recorded cycling performance at 5 C (over 1000 cycles with a capacity retention of 80.0 %). More importantly, impressive electrochemical performances and safety tests with LiNi0.8Mn0.1Co0.1O2 and pouch cell with LiFePO4, even under extreme conditions (i.e., 100 °C), are also demonstrated, reconfirmed the importance of lithiophilic‐lithiophobic gradient interfacial chemistry in the design of high‐rate ASSLMBs for safety applications.

Bilayer graphene, bilayer GeC and graphene/GeC bilayer heterostructure as anode materials for lithium-ion batteries: First-principles calculations

There is a great effort to develop the high-efficient anode materials for lithium-ion batteries with high stability and mobility. In this paper, we adopt the first-principles calculations to study the electrochemical properties of Li intercalation within bilayer graphene (BLG), bilayer GeC (BLGeC) and graphene/GeC bilayer heterostructure (BLGGeC) as anode materials. Our calculations disclose the following findings: (1) The interlayer is modulated by the stacking patterns and bilayer species. (2) The most energetically favorite intercalation of the Li atom is achieved in BLG with AA stacking because of the lowest adsorption energy. (3) The descending order of energy barriers is BLGGeC > BLGeC > BLG. The low diffusion barriers of BLG (0.025 eV) and BLGeC (0.09 eV) imply their high charging/discharging rates. Finally, the findings underline that the bilayer is a promising anode material and its electrochemical characteristics can be changed by adjusting the stacking configurations and its species.