Energy Diffusion Research Articles

Investigation of heat transfer enhancement and thermal stratification phenomenon on supercritical hydrogen fuel flow

Thermal stratification is one of the major issues in rectangular regenerative cooling channels because of the asymmetric heating and limited turbulent diffusion of thermal energy of the fuel. As a result, the heat transfer performance is decreased. This paper uses Ansys fluent software to construct a novel cooling structure that combines wavy wall surfaces with cylindrical fins. In addition to this new configuration, this study also examined three other configurations (straight-smooth, cylindrical-ribs, and wavy-smooth) and compared them with each other. This structure aims to efficiently enhance hydrogen coolant flow and heat transfer characteristics while reducing the extent of the non-uniform distribution issue. The results show that the new structure’s Nusselt number and maximum wall temperature are enhanced by 46.89% and 22.71%, respectively, compared to the straight-smooth structure; in contrast, the friction factor increased only by 3.64% over the smooth channel. The novel design has the best thermal performance factor compared to the other three designs, which is improved by 43.33% over the smooth channel. Among all configurations, the new structure is the best fluid temperature distribution configuration, which shows an optimal distribution of the coolant temperatures between layers; thus, the stratification phenomena decreased significantly.

Operationally stable perovskite solar modules enabled by vapor-phase fluoride treatment.

The ever-increasing power conversion efficiency of perovskite solar cells has illuminated the future of the photovoltaic industry, but the development of commercial devices is hampered by their poor stability. In this study, we report a scalable stabilization method using vapor-phase fluoride treatment, which achieves 18.1%-efficient solar modules (228 square centimeters) with accelerated aging-projected T80 lifetimes (time to 80% of efficiency remaining) of 43,000 ± 9000 hours under 1-sun illumination at 30°C. The high stability results from vapor-enabled homogeneous fluorine passivation over large-area perovskite surfaces, suppressing defect formation energy and ion diffusion. The extracted degradation activation energy of 0.61 electron volts for solar modules is comparable to that of most reported stable cells, which indicates that modules are not inherently less stable than cells and closes the cell-to-module stability gap.

Development of sulfonated graphite oxide incorporated poly(styrene sulfonic acid‐co‐malic acid) crosslinked sodium alginate membranes for pervaporation dehydration of isopropanol

AbstractPervaporation (PV) is a promising membrane‐based technology for dehydrating alcohols and separation of close‐boiling liquids. Poly(styrene sulfonic acid‐co‐maleic acid) (PSSAMA) crosslinked sodium alginate (NaAlg) membrane was developed, and was then modified by varying the mass% of sulfonated graphite oxide (SGO). Physicochemical properties of the resulting membranes were assessed using FTIR, WXRD, TGA, DSC, and SEM. The pervaporation study was carried out to assess membrane performance in dehydrating isopropanol. The membrane with 16 mass% of SGO exhibited the highest separation factor of 6025 and flux of 14.66 × 10−2 kg m−2 h−1 at 30°C for 10 mass% of water in the feed and were able to break the water–isopropanol azeotropic point. The activation energy for water permeation (Epw) was lower than that of isopropanol permeation (EIPA), indicating the high separation ability. Activation energies for total permeation (EP) and total diffusion (ED) ranged from 12.42 to 49.13 and 12.99 to 54.42 kJ mol−1, respectively. Negative enthalpy values (ΔHs) suggested Langmuir's sorption predominance for all membranes.Highlights The SGO incorporated crosslinked NaAlg composite membranes were prepared. The membrane containing 16 mass% of SGO showed the highest water uptake. Membrane with 16 mass% of SGO showed the highest flux and separation factor. All composite membranes showed excellent thermal and mechanical stability. Membrane with 16 mass% of SGO demonstrated excellent PV performance.

Diffusion Barrier Performance of Ni-W Layer at Sn/Cu Interfacial Reaction.

As the integration of chips in 3D integrated circuits (ICs) increases and the size of micro-bumps reduces, issues with the reliability of service due to electromigration and thermomigration are becoming more prevalent. In the practical application of solder joints, an increase in the grain size of intermetallic compounds (IMCs) has been observed during the reflow process. This phenomenon results in an increased thickness of the IMC layer, accompanied by a proportional increase in the volume of the IMC layer within the joint. The brittle nature of IMC renders it susceptible to excessive growth in small-sized joints, which has the potential to negatively impact the reliability of the welded joint. It is therefore of the utmost importance to regulate the formation and growth of IMCs. The following paper presents the electrodeposition of a Ni-W layer on a Cu substrate, forming a barrier layer. Subsequently, the barrier properties between the Sn/Cu reactive couples were subjected to a comprehensive and systematic investigation. The study indicates that the Ni-W layer has the capacity to impede the diffusion of Sn atoms into Cu. Furthermore, the Ni-W layer is a viable diffusion barrier at the Sn/Cu interface. The "bright layer" Ni2WSn4 can be observed in all Ni-W coatings during the soldering reflow process, and its growth was almost linear. The structure of the Ni-W layer is such that it reduces the barrier properties that would otherwise be inherent to it. This is due to the "bright layer" Ni2WSn4 that covers the original Ni-W barrier layer. At a temperature of 300 °C for a duration of 600 s, the Ni-W barrier layer loses its blocking function. Once the "bright layer" Ni2WSn4 has completely covered the original Ni-W barrier layer, the diffusion activation energy for Sn diffusion into the Cu substrate side will be significantly reduced, particularly in areas where the distortion energy is concentrated due to electroplating tension. Both the "bright layer" Ni2WSn4 and Sn will grow rapidly, with the formation of Cu-Sn intermetallic compounds (IMCs). At temperatures of 250 °C, the growth of Ni3Sn4-based IMCs is controlled by grain boundaries. Conversely, the growth of the Ni2WSn4 layer (consumption of Ni-W layer) is influenced by a combination of grain boundary diffusion and bulk diffusion. At temperatures of 275 °C and 300 °C, the growth of Ni3Sn4-based IMCs and the Ni2WSn4 layer (consumption of Ni-W layer) are both controlled by grain boundaries. The findings of this study can inform the theoretical design of solder joints with barrier layers as well as the selection of Ni-W diffusion barrier layers for use in different soldering processes. This can, in turn, enhance the reliability of microelectronic devices, offering significant theoretical and practical value.

Path ahead: Tackling the Challenge of Computationally Estimating Lithium Diffusion in Cathode Materials.

In the roadmap toward designing new and improved materials for Lithium ion batteries, the ability to estimate the diffusion coefficient of Li atoms in electrodes, and eventually solid-state electrolytes, is key. Nevertheless, as of today, accurate prediction through computational tools remains challenging. Its experimental measurement does not appear to be much easier. In this work, we devise a computational protocol for the determination of the Li-migration energy barrier and diffusion coefficient, focusing on a common cathode material such as LiNiO2, which represents a prototype of the widely adopted NMC (LiNi1-x-y Mn x Co y O2) class of materials. Different methodologies are exploited, combining ab initio metadynamics, path sampling, and density functional theory. Furthermore, we propose a novel, fast, and simple 1D approximation for the estimation of the effective frequency. The outlined computational protocol aims to be generally applicable to Lithium diffusion in other materials and components for batteries, including anodes and solid electrolytes.

Mullite Mineral-Derived Robust Solid Electrolyte Enables Polyiodide Shuttle-Free Zinc-Iodine Batteries.

Zinc dendrite, active iodine dissolution, and polyiodide shuttle caused by the strong interaction between liquid electrolyte and solid electrode are the chief culprits for the capacity attenuation of aqueous zinc-iodine batteries (ZIBs). Herein, mullite is adopted as raw material to prepare Zn-based solid-state electrolyte (Zn-ML) for ZIBs through zinc ion exchange strategy. Owing to the merits of low electronic conductivity, low zinc diffusion energy barrier, and strong polyiodide adsorption capability, Zn-ML electrolyte can effectively isolate the redox reactions of zinc anode and AC@I2 cathode, guide the reversible zinc deposition behavior, and inhibit the active iodine dissolution as well as polyiodide shuttle during cycling process. As expected, wide operating voltage window of 2.7V (vs Zn2+/Zn), high Zn2+ transference number of 0.51, and low activation energy barrier of 29.7kJ mol-1 can be achieved for the solid-state Zn//Zn cells. Meanwhile, high reversible capacity of 127.4 and 107.6 mAh g-1 can be maintained at 0.5 and 1 A g-1 after 3000 and 2100 cycles for the solid-state Zn//AC@I2 batteries, corresponding to high-capacity retention ratio of 85.2% and 80.7%, respectively. This study will inspire the development of mineral-derived solid electrolyte, and facilitate its application in Zn-based secondary batteries.

Room-temperature hydrogen adsorption in Pd nanoparticle decorated UiO-66-NH2 via spillover

To improve room-temperature hydrogen storage, palladium (Pd) nanoparticles were innovatively decorated by carbon bridge onto the amino-group functioned Zr-terephthalate metal-organic framework (MOF) UiO-66 to reduce the diffusion energy barrier and then improve the hydrogen spillover effect. Powder X-ray diffraction shows broad Pd peak and retained UiO-66-NH2 integrity after Pd decoration. The hydrogen uptake capacity show that UiO-66-NH2-Pd exhibits best hydrogen storage performance than UiO-66-NH2 and pristine UiO-66. The hydrogen up taken in Pd decorated UiO-66 (UiO-66-NH2-1Pd) was close to 4 wt% under 20 MPa at room temperature. Density functional theory (DFT) calculations show that hydrogen adsorption energy of UiO-66-NH2-Pd was −0.5897 eV, which was much lower than that of UiO-66-NH2 (−0.3716 eV) and UiO-66 (−0.2975 eV). Ultimately, Pd decorated NH2 group functioned UiO-66 enable improve storage capacities through hydrogen spillover under ambient conditions which could satisfy the demand for sustainable energy, especially for the long-term storage energy media.

Deciphering the structural and kinetic factors in lithium titanate for enhanced performance in Li+/Na+ dual-cation electrolyte

The widespread application of Li4Ti5O12 (LTO) anode in lithium-ion batteries has been hindered by its relatively low energy density. In this study, we investigated the capacity enhancement mechanism of LTO anode through the incorporation of Na+ cations in an Li+-based electrolyte (dual-cation electrolyte). LTO thin film electrodes were prepared as conductive additive-free and binder-free model electrodes. Electrochemical performance assessments revealed that the dual-cation electrolyte boosts the reversible capacity of the LTO thin film electrode, attributable to the additional pseudocapacitance and intercalation of Na+ into the LTO lattice. Operando Raman spectroscopy validated the insertion of Li+/Na+ cations into the LTO thin film electrode, and the cation migration kinetics were confirmed by ab initio molecular dynamic (AIMD) simulation and electrochemical impedance spectroscopy, which revealed that the incorporation of Na+ reduces the activation energy of cation diffusion within the LTO lattice and improves the rate performance of LTO thin film electrodes in the dual-cation electrolyte. Furthermore, the interfacial charge transfer resistance in the dual-cation electrolyte, associated with ion de-solvation processes and traversal of the cations in the solid-electrolyte interphase (SEI) layer, are evaluated using the distribution of relaxation time, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Our approach of performance enhancement using dual-cation electrolytes can be extrapolated to other battery electrodes with sodium/lithium storage capabilities, presenting a novel avenue for the performance enhancement of lithium/sodium-ion batteries.

Investigating temperature-dependent gas permeation in PIM-1: Hysteresis, annealing effects, and thermal history impact

This study investigates the gas permeability, diffusion coefficients, and solubility coefficients of CO2 and N2 in PIM-1 over the temperature range of 35 °C–135 °C. During the first heating-cooling cycle, both gases' permeability exhibited hysteresis, which diminished during the second cycle. Thermal mechanical analysis confirmed volume relaxation occurring at temperatures above 95 °C, indicating physical aging. By calculating the relaxation time associated with volume relaxation, the influence of physical aging was minimized through measurements on samples annealed at 135 °C for 15 h. This approach enabled a successful evaluation of the temperature dependence of gas permeability under conditions where the impact of physical aging could be disregarded. The results revealed that the permeability of CO2 decreased, and that of N2 increased with increasing temperature. The diffusion coefficients showed positive temperature dependence, while the solubility coefficients decreased. Physical aging significantly affected the diffusion coefficients but had minimal impact on the solubility coefficients. Heat of sorption and activation energies for gas permeability and diffusion estimated, and it was found that the decrease in CO2 permeability with temperature was mainly attributed to the large heat of sorption for CO2.

Research on the performance of methanol/PODE dual fuel spark-assisted compression ignition combustion with different intake air adjustment

There is room for continued research and optimization on the exothermal processes and performance of methanol/polyoxymethylene dimethyl ether (PODE) dual fuel spark-assisted compression ignition (DF-SACI) with different air adjustment. The exothermal processes of methanol/PODE DF-SACI were investigated and optimized at varying methanol premix ratios (RM) and intake adjustment methods to maximize the promoting effect of spark ignition (SI). The results show that burning intensity progressively falls, while the ignition delay, CA50 and combustion duration progressively rise as excess air coefficient (λ) climbs. The resistance of high RM to lean combustion is weaker than low RM. As λ grows, the high-intensity exotherm is progressively transformed to the softer exotherm. Consequently, the exothermal energy from premixed compression ignition is progressively converted into the exothermal energy from DF-SACI. Subsequently, the exothermal energy from DF-SACI is progressively replaced by the exothermal energy of diffusion and SI combustion. By reducing air through intake variable valve timing (VVT), the optimal brake thermal efficiency (BTE) and RM under brake mean effective pressure (BMEP) of 0.4 MPa can be elevated to 40.67 % and 60 %, respectively. The optimal BTE for BMEP of 0.6 and 0.4 MPa are further enlarged from 42.82 % and 40.67 % to 43.52 % and 41.41 % by adjusting exhaust VVT, respectively.

Tailoring d–p Orbital Hybridization to Decipher the Essential Effects of Heteroatom Substitution on Redox Kinetics

AbstractThe heteroatom substitution is considered as a promising strategy for boosting the redox kinetics of transition metal compounds in hybrid supercapacitors (HSCs) although the dissimilar metal identification and essential mechanism that dominate the kinetics remain unclear. It is presented that d‐p orbital hybridization between the metal and electrolyte ions can be utilized as a descriptor for understanding the redox kinetics. Herein, a series of Co, Fe and Cu heteroatoms are respectively introduced into Ni3Se4 cathodes, among them, only the moderate Co‐substituted Ni3Se4 can hold the optimal d‐p orbital hybridization resulted from the formed more unoccupied antibonding states π*. It inevitably enhances the interfacial charge transfer and ensures the balanced OH− adsorption‐desorption to accelerate the redox kinetics validated by the lowest reaction barrier (0.59 eV, matching well with the theoretical calculations). Coupling with the lower OH− diffusion energy barrier, the prepared cathode delivers ultrahigh rate capability (~68.7 % capacity retention even the current density increases by 200 times), and an assembled HSC also presents high energy/power density. This work establishes the principles for determining heteroatoms and deciphers the underlying effects of the heteroatom substitution on improving redox kinetics and the rate performance of battery‐type electrodes from a novel perspective of orbital‐scale manipulation.

Tailoring d-p Orbital Hybridization to Decipher the Essential Effects of Heteroatom Substitution on Redox Kinetics.

The heteroatom substitution is considered as a promising strategy for boosting the redox kinetics of transition metal compounds in hybrid supercapacitors (HSCs) although the dissimilar metal identification and essential mechanism that dominate the kinetics remain unclear. It is presented that d-p orbital hybridization between the metal and electrolyte ions can be utilized as a descriptor for understanding the redox kinetics. Herein, a series of Co, Fe and Cu heteroatoms are respectively introduced into Ni3Se4 cathodes, among them, only the moderate Co-substituted Ni3Se4 can hold the optimal d-p orbital hybridization resulted from the formed more unoccupied antibonding states π*. It inevitably enhances the interfacial charge transfer and ensures the balanced OH- adsorption-desorption to accelerate the redox kinetics validated by the lowest reaction barrier (0.59 eV, matching well with the theoretical calculations). Coupling with the lower OH- diffusion energy barrier, the prepared cathode delivers ultrahigh rate capability (~68.7 % capacity retention even the current density increases by 200 times), and an assembled HSC also presents high energy/power density. This work establishes the principles for determining heteroatoms and deciphers the underlying effects of the heteroatom substitution on improving redox kinetics and the rate performance of battery-type electrodes from a novel perspective of orbital-scale manipulation.

Modeling of Physical-Chemical and Electronic Properties of Lithium-Containing 4H—SiC and Binary Phases of the Si—C–Li System

In the equilibrium model of the solid surface–adatom system, including a three-dimensional interfacial surface, changes in surface properties are considered, taking into account the chemical potential due to the action of surface tension. The relationship between chemical potential and electrochemical potential of the ith component in an electrochemical cell is analyzed. Using the density functional theory (DFT), the adsorption, electronic, and thermodynamic properties of 2 × 2 × 1 and 3 × 3 × 1 supercells of crystalline compounds AmBn, (, where n and m are stoichiometric coefficients) of the boundary binary systems of the ternary phase diagram of Si–C–Li are studied. The stability of phases AmBn and property calculations are carried out with the exchange-correlation functional within the framework of the generalized gradient approximation (GGA PBE). The parameters of the crystal structures of the compounds AmBn, the adsorption energy of the lithium adatom on a 4H–SiC substrate, the electronic structure, and the thermodynamic properties of supercells are calculated. The thermodynamically stable configurations of the 4H–SiC–Liads supercells having different locations Liads are determined. The DFT GGA PBE calculations of the enthalpy of formation of compounds AmBn are carried out in the ternary Si–C–Li system. Taking into account the changes in the Gibbs free energy in the solid-phase exchange reactions between binary compounds, equilibrium sections (connodes) in the concentration triangle of the Si–C–Li phase diagram are established. An isothermal section of the Si–C–Li phase diagram at 298 K is constructed. The patterns of diffusion processes that are related to the movement of particles on the surface layer of the 6H–SiC sample are analyzed. The activation energy of lithium diffusion in 6H–SiC is calculated from the Arrhenius type relation in two temperature ranges (769–973 K) and (1873–2673 K).

Ni/Ni4N nanoparticles anchored on 3D necklace-like carbon framework as free-standing bifunctional host for practical Li-S full cells

Inhibiting the shuttle effect, accelerating sulfur redox kinetics and controlling lithium homogeneous deposition are significant to achieve the flexible lithium-sulfur (Li-S) cells with high energy density and safety. In this study, we successfully synthesized a three-dimensional (3D) free-standing necklace-like fabric consisting of heterostructured Ni/Ni4N nanoparticles confined into hollow carbon cages implanted with N-doped carbon nanofibers (Ni/Ni4N@NCC). This unique 3D necklace-like framework and interface electronic structure of Ni/Ni4N@NCC could effectively addresses the challenges associated with both sulfur cathode and lithium anode in Li-S cells. Combine with experimental tests and DFT simulations, Ni/Ni4N@NCC not only strengthened chemical anchoring and accelerated lithium polysulfides conversion, but also induced Li uniform deposition and growth due to its excellent lithiophilicity and low Li diffusion energy barrier. For the anode, the lithium foil coating with Ni/Ni4N@NCC interlayer (denoted as Li-Ni/Ni4N@NCC anode) showed exceptional long-term cycling stability over 1000 h at the high current density of 5 mA cm−2 for high areal capacity of 5 mAh cm−2. The S-Ni/Ni4N@NCC||Li-Ni/Ni4N@NCC cell with sulfur loading (6.8mg cm−2) exhibited high areal capacities of 6.11 mAh cm−2. The synergetic effect of fascinating necklace-like structure and heterogeneous interface offer instruction for the practically viable design of high-performance flexible Li-S full cells.

Tailored crystal planes of VO2 cathode power fast Zn2+ storage

Vanadium dioxide (VO2) cathode with specific tunnel structure and favorable specific capacity is critical for developing aqueous zinc-ion batteries (AZIBs) with excellent electrochemical performance. However, sluggish electrochemical kinetics hampered its development in burgeoning energy storage devices. Herein, we tailored VO2 material with different exposed crystal planes and employed as cathodes for AZIBs. The comprehensive analyses indicate the exposed (201) and (001) crystal planes are favorable for fast electrochemical kinetics, high capacitance storage, and the smallest diffusion energy barrier, which guarantee electrodes with high discharge capacity (367 mA h/g at 0.1 A/g), excellent rate capability (281 mA h/g at 4 A/g) and cycling stability over 800 cycles. Besides, Ex-situ characterizations manifest VO2 cathode with specific exposed crystal planes easily transformed to Zn3+x(OH)2V2O7·2H2O in the first discharge process, hence allowing continuous embedding of Zn2+ in this layered structure, and the ex-situ scanning electron microscopy (SEM) analysis confirms the morphology change matched well with the structural transformation. This study may enlighten and promote the role of exposed crystal plane to develop high-performance rechargeable batteries.

Transient energy transfer and cascade analysis for stratified turbulent channel flows

A comprehensive and fine-grained transient analysis of the kinetic budget equation in the spectral and spatial domains for channel flow subjected to stable stratification is performed, through a series of large eddy simulations (LES) at a bulk Reynolds number of 2200 and for Froude numbers of 0.5, 2.0, 4.5 and 6.8, thereby covering a range of stratification strengths from high to low. The dynamic Smagorinsky eddy viscosity-based sub-grid scale (SGS) model is used for closure. Validation of the methodology is carried out by comparing the turbulent flow LES results to previously published channel flow results. The analysis is focussed on the effect of stratification on the energy cascade process of an initially turbulent flow in a channel configuration. The terms in the kinetic budget equation, in the homogeneous and inhomogeneous directions, are compared for different Froude numbers to assess the effects of weak and strong stratification on turbulent statistics. Transient results are plotted to highlight the role played by different terms in the budget equation and to understand the formation of the gravity waves in the core or outer regions of the wall-bounded flow in the presence of stratification. The energy cascade reveals some interesting observations about the functions of viscous diffusion, pressure diffusion, and inhomogeneous energy transfer in the initial phase of the development of flow, which in turn helps to explain the stationary waves observed in the presence of strong stratification.

H2-D2 Exchange Activity and Electronic Structure of Ag x Pd1-x Alloy Catalysts Spanning Composition Space.

Many computational studies of catalytic surface reaction kinetics have demonstrated the existence of linear scaling relationships between physical descriptors of catalysts and reaction barriers on their surfaces. In this work, the relationship between catalyst activity, electronic structure, and alloy composition was investigated experimentally using a Ag x Pd1-x Composition Spread Alloy Film (CSAF) and a multichannel reactor array that allows measurement of steady-state reaction kinetics at 100 alloy compositions simultaneously. Steady-state H2-D2 exchange kinetics were measured at atmospheric pressure on Ag x Pd1-x catalysts over a temperature range of 333-593 K and a range of inlet H2 and D2 partial pressures. X-ray photoelectron spectroscopy (XPS) was used to characterize the CSAF by determining the local surface compositions and the valence band electronic structure at each composition. The valence band photoemission spectra showed that the average energy of the valence band, ε̅v, shifts linearly with composition from -6.2 eV for pure Ag to -3.4 eV for pure Pd. At all reaction conditions, the H2-D2 exchange activity was found to be highest on pure Pd and gradually decreased as the alloy was diluted with Ag until no activity was observed for compositions with x Pd < 0.58. Measured H2-D2 exchange rates across the CSAF were fit using the Dual Subsurface Hydrogen (2H') mechanism to extract estimates for the activation energy barriers to dissociative adsorption, ΔE ads ‡, associative desorption, ΔE des ‡, and the surface-to-subsurface diffusion energy, ΔE ss, as a function of alloy composition, x Pd. The 2H' mechanism predicts ΔE ads ‡ = 0-10 kJ/mol, ΔE des ‡ = 30-65 kJ/mol, and ΔE ss = 20-30 kJ/mol for all alloy compositions with x Pd ≥ 0.64, including for the pure Pd catalyst (i.e., x Pd = 1). For these Pd-rich catalysts, ΔE des ‡ and ΔE ss appeared to increase by ∼5 kJ/mol with decreasing x Pd. However, due to the coupling of kinetic parameters in the 2H' mechanism, we are unable to exclude the possibility that the kinetic parameters predicted when x Pd ≥ 0.64 are identical to those predicted for pure Pd. This suggests that H2-D2 exchange occurs only on bulk-like Pd domains, presumably due to the strong interactions between H2 and Pd. In this case, the decrease in catalytic activity with decreasing x Pd can be explained by a reduction in the availability of surface Pd at high Ag compositions.

Synergistic effect of LixSi/Li3N artificial interface and 3D framework for enabling Dendrite-free, long-life lithium metal anodes

Lithium metal is highly favored as an ideal anode material in future high-capacity lithium batteries due to its appealing properties. Nevertheless, the implementation of lithium metal batteries (LMBs) is severely plagued by challenges such as instable solid electrolyte interface (SEI), uncontrolled growth of dendrite, and severe volume expansion. Herein, to address the aforementioned issues, an artificial SEI layer is fabricated, which is comprised of LixSi alloy and Li3N. The in-situ generated LixSi/Li3N interface is formed on the carbon fiber (denoted as CF/LixSi/Li3N) through a spontaneous reaction between molten Li and Si3N4. Density functional theory (DFT) calculations reveal that LixSi alloy has low ion diffusion energy barrier, which facilitates the low nucleation overpotential of Li+ and enables homogeneous lithium deposition. Li3N can further promote the rapid Li+ transport due to the excellent Li+ conductivity. In addition, the reserved 3D space effectively mitigates the volume change along cycling procedure. Owing to the synergistic effect of the LixSi/Li3N protective layer and the 3D structure, the composite anode shows higher cycling stability with a lifetime of more than 3000 cycles at 1 mA cm−2. Furthermore, matched with commercial LiFePO4 (LFP) and LiNi5Co2Mn3O2 (NCM523) cathodes, the full cells also exhibit impressive electrochemical properties. This work introduces an ingenious approach for constructing stable lithium metal anodes and effective lithium metal batteries.

Thermodynamic prediction of filler surface modification by APTES on corrosion resistance of nano-TiO2/waterborne epoxy coatings

Common techniques for creating novel coatings include chemically modifying inorganic fillers and exploring how modifications affect coating service performance. However, it frequently takes a lot of time and tedious attempts to get the ideal alteration degree for fillers. Although the surface energy of the fillers is thought to be a significant thermodynamic parameter, it is still unknown how chemical modification affects surface energy and how the properties of fillers in a coating relate to the quantization difference of thermodynamic parameters. In this study, the impact of chemical modification on the quantization difference of nano-TiO2 surface energy has been uncovered. Creating a “wetting-reagglomeration-adsorption” isogram by utilizing three surface interfacial parameters has also been achieved: the contact angle between the liquid resin and the filler, the driving energy of the filler reagglomeration, and the polymer molecules' diffusion energy at the filler/coating interface. The relationship between the quantitative difference of thermodynamic parameters and the dispersion, compatibility and interfacial strength of the fillers in the waterborne epoxy was predicted by the isocontour map. From the isocontour map, the modified nano-TiO2 fillers with 4.04 APTES molecules/nm2 shows the minimum ∆Wa of 16.17 mJ/m2 and the maximum Ws of 23.15 mJ/m2 in the composite coating, which is predicted to exhibit the best dispersibility and the strongest interfacial strength. The prediction results were successfully verified by the techniques of microscopic morphology observation (TEM and SEM), mechanical properties tests (DMA and tensile tests), and corrosion resistance tests (EIS and salt spray tests). This work has a significant guiding role in the development of the filler modifications for the creation of novel coatings.

Wave propagation in a light-temperature neural network under adaptive local energy balance.

External electric and mechanical stimuli can induce shape deformation in excitable media because of its intrinsic flexible property. When the signals propagation in the media is described by a neural network, creation of heterogeneity or defect is considered as the effect of shape deformation due to accumulation or release of energy in the media. In this paper, a temperature-light sensitive neuron model is developed from a nonlinear circuit composed of a phototube and a thermistor, and the physical energy is kept in capacitive and inductive terms. Furthermore, the Hamilton energy for this function neuron is obtained in theoretical way. A regular neural network is built on a square array by activating electric synapse between adjacent neurons, and a few of neurons in local area is excited by noisy disturbance, which induces local energy diversity, and continuous coupling enables energy propagation and diffusion. Initially, the Hamilton energy function for a temperature-light sensitive neuron can be obtained. Then, the finite neurons are applied noise to obtain energy diversity to explore the energy spread between neurons in the network. For keeping local energy balance, one intrinsic parameter is regulated adaptively until energy diversity in this local area is decreased greatly. Regular pattern formation indicates that local energy balance creates heterogeneity or defects and a few of neurons show continuous parameter shift for keeping energy balance in a local area, which supports gradient energy distribution for propagating waves in the network.