Unraveling the Fundamental Mechanism of Interface Conductive Network Influence on the Fast‑Charging Performance of SiO‑Based Anode for Lithium‑Ion Batteries

Progress in the fast charging of high-capacity silicon monoxide(SiO)-based anode is currently hindered by insufficient conductivity and notable volume expansion.The construction of an interface conductive network effectively addresses the aforementioned problems;however,the impact of its quality on lithium-ion transfer and structure durability is yet to be explored.Herein,the influence of an interface conductive network on ionic transport and mechanical stability under fast charging is explored for the first time.2D modeling simulation and Cryo-transmission electron microscopy precisely reveal the mitigation of interface polarization owing to a higher fraction of conductive inorganic species formation in bilayer solid electrolyte interphase is mainly responsible for a linear decrease in ionic diffusion energy barrier.Furthermore,atomic force microscopy and Raman shift exhibit substantial stress dissipation generated by a complete conductive network,which is critical to the linear reduction of electrode residual stress.This study provides insights into the rational design of optimized interface SiO-based anodes with reinforced fast-charging performance.

Emerging Flexible Thermally Conductive Films:Mechanism,Fabrication,Application

Effective thermal management is quite urgent for electronics owing to their ever-growing integration degree,operation frequency and power density,and the main strategy of thermal management is to remove excess energy from electronics to outside by thermal conductive materials.Compared to the conventional thermal management materials,flexible thermally conductive films with high in-plane thermal conductivity,as emerging candidates,have aroused greater interest in the last decade,which show great potential in thermal management applications of next-generation devices.However,a comprehensive review of flexible thermally conductive films is rarely reported.Thus,we review recent advances of both intrinsic polymer films and polymer-based composite films with ultrahigh in-plane thermal conductivity,with deep understandings of heat transfer mechanism,processing methods to enhance thermal conductivity,optimization strategies to reduce interface thermal resistance and their potential applications.Lastly,challenges and opportunities for the future development of flexible thermally conductive films are also discussed.

Effect of Zn content on microstructure,mechanical properties and thermal conductivity of extruded Mg-Zn-Ca-Mn alloys

Mg-Zn-Ca-Mn series alloys are developed as promising candidates of 5G communication devices with excellent thermal conductivities,great ductility,and acceptable strength.In present paper,Mg-x Zn-0.4Ca-0.2Mn(x=2wt%,4wt%,6wt%)alloys were prepared by a near-solidus extrusion and the effect of Zn content on mechanical and thermal properties were investigated.The results showed that the addition of minor Ca led to the formation of Ca_(2)Mg_(6)Zn_(3) eutectic phase at grain boundaries.A type of bimodal microstructure occurred in the as-extruded alloys,where elongated coarse deformed grains were embedded in refined recrystallized grains matrix.Correspondingly,both yield strength and ductility of the alloys were significantly enhanced after extrusion due to the great grain refinement.Specially,higher Zn content led to the increment in yield strength and a slight reduction in elongation due to the larger fractions of second phase particles.The room temperature thermal conductivity of as-extruded alloys was also improved compared with that of as-cast counterparts.The increment of Zn content decreased the thermal conductivity of both as-cast and as-extruded alloys,which was due to the increased second phase fraction and solution atoms in the matrix,that hindering the motion of electrons.The as-extruded Mg-2Zn-0.4Ca-0.2Mn(wt%)alloy exhibited the highest elongation of 27.7% and thermal conductivity of 139.2 W/(m·K),combined with an acceptable ultimate tensile strength of 244.0 MPa.The present paper provides scientific guidance for the preparation of lightweight materials with high ductility and high thermal conductivity.

INVESTIGATION OF MICROSTRUCTURE AND CONDUCTIVE MECHANISM OF HIGH DENSITY POLYETHYLENE/CARBON BLACK PARTICLE COMPOSITE BY POSITRON ANNIHILATION LIFETIME SPECTROSCOPY

The microstmcture and conductive mechanism of high density polyethylene/carbon black (HDPE/CB) composite were investigated by positron annihilation lifetime spectroscopy (PALS). The PALS were measured in two series of samples,one with various CB contents in the composites and the other with various γ-irradiation doses in HDPE/CB composite containing 20 wt% CB. It was found that CB particles distribute in the amorphous regions, the CB critical content value in HDPE/CB composite is about 16.7 wt% and the suitable γ-irradiation dose for improving the conductive behavior of HDPE/CB composite is about 20 Mrad. The result observed for the second set of samples suggests that γ-irradiation causes not only cross-linking in amorphous regions but also destruction of the partial crystalline structure. Therefore, a suitable irradiation dose, about 20 Mrad, can induce sufficient cross-linking in the amorphous regions without enhancing the decomposition of crystalline structure, so that the positive temperature coefficient (PTC) effect remains while the negative temperature coefficient (NTC) effect is suppressed. A new interpretation of the conductive mechanism, which might provide a more detailed explanation of the PTC effect and the NTC effect has been proposed.

Trade-offs between ion-conducting and mechanical properties: The case of polyacrylate electrolytes

Polymer electrolytes(PEs)have been long recognized as the key materials to enable energy-dense batteries and render flexible energy devices practically viable,owing to their chemical and mechanical reliability.However,much of their promise is yet to be realized.The roomtemperature ion conductivity of existing PEs still falls short of the implementation criterion of 10^(-4) S cm^(-1) on the promise of acceptable mechanical properties,thereby precluding their practical application.The twin but inversely related duties of polymers,that is,functioning as both an ion-conducting medium and a structural backbone,underlie this issue but are less elucidated systematically.The polyacrylate(PA)family is among promising polymer matrices on account of ester polarity,electrode compatibility,chemical tunability,and mechanical durability.The extensive applicability of PA in plasticized gels,dry solids,and emerging composites makes PA-based PEs representative to illustrate the trade-off between ion conduction and mechanical strength.We herein seek to outline the stated long-standing conflict exemplified by PA-based PEs,focusing on crucial strategies toward balancing and reconciling the two mutually exclusive properties,with the intention of offering designing guidelines for next-generation PEs.

Temperature-mediated structural evolution of vapor–phase deposited cyclosiloxane polymer thin films for enhanced mechanical properties and thermal conductivity

Polymer-derived ceramic(PDC) thin films are promising wear-resistant coatings for protecting metals and carbon-carbon composites from corrosion and oxidation.However,the high pyrolysis temperature hinders the applications on substrate materials with low melting points.We report a new synthesis route for PDC coatings using initiated chemical vapor deposited poly(1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane)(pV_3D_3) as the precurs or.We investigated the changes in siloxane moieties and the network topology,and proposed a three-stage mechanism for the thermal annealing process.The rise of the connectivity number for the structures obtained at increased annealing temperatures was found with strong correlation to the enhanced mechanical properties and thermal conductivity.Our PDC films obtained via annealing at 850℃ exhibit at least 14.6% higher hardness than prior reports for PDCs synthesized below 1100℃.Furthermore,thermal conductivity up to 1.02 W(mK)^(-1) was achieved at the annealing temperature as low as 700℃,which is on the same order of magnitude as PDCs obtained above 1100℃.Using minimum thermal conductivity models,we found that the thermal transport is dominated by diffusons in the films below the percolation of rigidity,while ultra-short mean-free path phonons contribute to the thermal conductivity of the films above the percolation threshold.The findings of this work provide new insights for the development of wear-resistant and thermally conductive PDC thin films for durable protection coatings.

Conduction Properties and Scattering Mechanisms in F-doped Textured Transparent Conducting SnO_2 Films Deposited by APCVD

Transparent conducting F-doped texture SnO2 films with resistivity as low as 5× 10-4 Ω ·cm,with carrier concentrations between 3.5 × 1020 and 7× 1020 cm-3 and Hall mobilities from 15.7 to 20.1 cm2/(V/s) have been prepared by atmosphere pressure chemical vapour deposition (APCVD). These polycrystalline films possess a variable preferred orientation, the polycrystallite sizes and orientations vary with substrate temperature. The substrate temperature and fluorine flow rate dependence of conductivity, Hall mobility and carrier conentration fOr the resultingfilms have been obtained. The temperature dependence of the mobiity and carrier concentrationhave been measured over a temperature range 16～400 K. A systematically theoretical analysis on scattering mechanisms for the highly conductive SnO2 films has been given. Both theoretical analysis and experimental results indicate that for these degenerate, polycrystalline SnO2 ：F films in the low temperature range (below 100 K), ionized impurity scattering is main scattering mechanism. However, when the temperature is higher than 100 K, the lattice vibration scattering becomes dominant. The grain boundary scattering makes a small contribution to limit the mobility of the films.

The conductive mechanisms of a titanium oxide memristor with dopant drift and a tunnel barrier

Nano-scale titanium oxide memristors exhibit complex conductive characteristics, which have already been proved by existing research. One possible reason for this is that more than one mechanism exists, and together they codetermine the conductive behaviors of the memristor. In this paper, we first analyze the theoretical base and conductive process of a memristor, and then propose a compatible circuit model to discuss and simulate the coexistence of the dopant drift and tunnel barrier-based mechanisms. Simulation results are given and compared with the published experimental data to prove the possibility of the coexistence. This work provides a practical model and some suggestions for studying the conductive mechanisms of memristors.

Crystallization and Conductivity Mechanism of ITO Films on Different Substrates Deposited with Different Substrate Temperatures

ITO thin films were grown on PC(polycarbonate), PMMA(polymethyl methacrylate) and glass substrates by r.f. magnetron sputtering. The electrical, structural and chemical characteristics of ITO films were analyzed by the Hall Technique, X-ray diffraction, and X-ray photoelectron spectroscopy. XPS studies suggest that all the ITO films consist of crystalline and amorphous phases. The degree of crystallinity increases from less than 45% to more than 90% when the substrate temperature increases from 80 to 300 ℃. The In and Sn exist in the chemical state of In3+ and Sn4+, respectively, independent of substrate type and temperature. The enrichment of Sn on surface and In in body of ITO films are also revealed. And, the oxygen deficient regions exist both in surface layer and film body. For ITO films deposited under 180 ℃ , the carrier concentration are mainly provided by oxygen vacancies, and the dominant electron carrier scattering mechanism is grain boundary scattering between the crystal and the amorphous grain. For ITO films deposited over 180 ℃, the carrier concentration are provided by tin doping, and the dominant scattering mechanism transforms from grain boundary scattering between the crystal grains to ionized impurity scattering with increasing deposition temperature.

IONIC CONDUCTION MECHANISM IN Na_(5+x)YA1_xSi_(4-x)O_(12) SUPERIONIC CONDUCTORS

Na5+xYAlxSi4-xO12 superionic conductors arerhombohedral R3c space group.Their structures arecharacterized by(Alx/4Si1-x/4)O4 tetrahedra linked toform puckered(Al3xSi4-x)4O35 rings parallel to thebasal plane of the hexagonal cell.These rings,separated by parts of sodium oxygen polyhedron,arestacked to form large rigid colums parallel to c axis.The columns are linked by[YO6]octahedra to form athree-dimensional Framework with large channels betweenthe rings.Parts of Na ions located in the cores of thecolumns are movable.In terms of the conductionmechanism,the concentration of conducting Na+ ions wascarried out and compared with the experimental results.It was found that the theoretical values accord withthe experimental results.

Ignition processes and characteristics of charring conductive polymers with a cavity geometry in precombustion chamber for applications in micro/nano satellite hybrid rocket motors

The arc ignition system based on charring polymers has advantages of simple structure,low ignition power consumption and multiple ignitions,which bringing it broadly application prospect in hybrid propulsion system of micro/nano satellite.However,charring polymers alone need a relatively high input voltage to achieve pyrolysis and ignition,which increases the burden and cost of the power system of micro/nano satellite in practical application.Adding conductive substance into charring polymers can effectively decrease the conducting voltage which can realize low voltage and low power consumption repeated ignition of arc ignition system.In this paper,a charring conductive polymer ignition grain with a cavity geometry in precombustion chamber,which is composed of PLA and multiwall carbon nanotubes(MWCNT)was proposed.The detailed ignition processes were analyzed and two different ignition mechanisms in the cavity of charring conductive polymers were revealed.The ignition characteristics of charring conductive polymers were also investigated at different input voltages,ignition grain structures,ignition locations and injection schemes in a visual ignition combustor.The results demonstrated that the ignition delay and external energy required for ignition were inversely correlated with the voltages applied to ignition grain.Moreover,the incremental depth of cavity shortened the ignition delay and external energy required for ignition while accelerated the propagation of flame.As the depth of cavity increased from 2 to 6 mm(at 50 V),the time of flame propagating out of ignition grain changed from 235.6 to 108 ms,and values of mean ignition delay time and mean external energy required for ignition decreased from 462.8 to 320 ms and 16.2 to 10.75 J,respectively.The rear side of the cavity was the ideal ignition position which had a shorter ignition delay and a faster flame propagation speed in comparison to other ignition positions.Compared to direct injection scheme,swirling injection provided a more favorable flow field environment in the cavity,which was beneficial to ignition and initial flame propagation,but the ignition position needed to be away from the outlet of swirling injector.At last,the repeated ignition characteristic of charring conductive polymers was also investigated.The ignition delay time and external energy required for ignition decreased with repeated ignition times but the variation was decreasing gradually.

Development of conductive hydrogels: from design mechanisms to frontier applications

Owing to their excellent mechanical flexibility, electrical conductivity, and biocompatibility, conductive hydrogels(CHs) are widely used in the fields of energy and power, and biomedical technology. To arrive at a better understanding of the design methods and development trends of CHs, this paper summarizes and analyzes related research published in recent years. First,we describe the properties and characteristics of CHs. Using Scopus, the world’s largest abstract and citation database, we conducted a quantitative analysis of the related literature from the past 15 years and summarized development trends in the field of CHs. Second, we describe the types of CH network crosslinking and basic functional design methods and summarize the three-dimensional(3D) structure-forming methods and conductive performance tests of CHs. In addition, we introduce applications of CHs in the fields of energy and power, biomedical technology, and others. Lastly, we discuss several problems in current CH research and introduce some prospects for the future development of CHs.

Performance of High Thermal Conductivity Dense Silica Bricks and Their High Thermal Conductivity Mechanism

High thermal conductivity dense silica bricks have the higher thermal conductivity than ordinary silica bricks,which is conducive to the realization of energy saving and emission reduction in the iron and steel industry.The performance of ordinary silica bricks and high thermal conductivity dense silica bricks was compared,and the high thermal conductivity mechanism was analyzed.The results show that(1)compared with ordinary silica bricks,high thermal conductivity dense silica bricks have the characteristics of higher thermal conductivity,lower apparent porosity,higher tridymite content,higher compressive strength,and higher thermal expansion;(2)by increasing the tridymite content and reducing the porosity,the close packing of honeycombα-tridymite improves the density and continuity of the SiO_(2)frame structure of the silica bricks,and the larger area perpendicular to the heat transfer direction improves the thermal conductivity of the bricks;(3)the densification of the silica bricks also increases the thermal expansion of the bricks,but they still meet the standard requirements.

Conductance switching mechanism of Rose Bengal organic thin films in ambient conditions

The molecular thin films of Rose Bengal (RB) embedded in polymethyl methacrylate matrix are fabricated by using the spin-coating technique. The macroscopic current-voltage (I-V) characterization of the film shows that the RB molecule has two conductance switching states with a high ON/OFF ratio in ambient conditions. The infrared spectra indicate that intermolecular hydrogen bonds can form in the RB thin films after their hydrolysis in air. With the first-principles calculations, we demonstrate that the hydrogen bonds will be destroyed in concomitance with the conformational change when the RB molecule switches to its high-conductance state after applying a voltage.

Influence of anisotropy on the electrical conductivity and diffusion coefficient of dry K-feldspar： Implications of the mechanism of conduction

The electrical conductivities of single-crystal K-feldspar along three different crystallographic directions are investigated by the Solartron-1260 Impedance/Gain-phase analyzer at 873 K–1223 K and 1.0 GPa–3.0 GPa in a frequency range of 10-1 Hz–106 Hz. The measured electrical conductivity along the ⊥ [001] axis direction decreases with increasing pressure, and the activation energy and activation volume of charge carriers are determined to be 1.04 ± 0.06 e V and 2.51 ± 0.19 cm^3/mole, respectively. The electrical conductivity of K-feldspar is highly anisotropic, and its value along the⊥ [001] axis is approximately three times higher than that along the ⊥ [100] axis. At 2.0 GPa, the diffusion coefficient of ionic potassium is obtained from the electrical conductivity data using the Nernst–Einstein equation. The measured electrical conductivity and calculated diffusion coefficient of potassium suggest that the main conduction mechanism is of ionic conduction, therefore the dominant charge carrier is transferred between normal lattice potassium positions and adjacent interstitial sites along the thermally activated electric field.

Preparation,Performance and Slag Resistant Mechanism of Low Thermal Conductivity Microporous Corundum

The microporous corundum material was prepared using alumina micro-powder as the main raw material,alumina sol and starch as binders by a wet process,achieving the bulk density of 3. 05 g·cm^(-3),the apparent porosity of 9. 1%,the closed porosity of 12. 3%,the median pore diameter of 0. 43 μm,and the thermal conductivity of 6. 5 W·m^(-1)·K^(-1)at 800 ℃ which is41. 6% lower than that of common corundum. The slag resistance of the microporous corundum material was studied by immersion and compared with that of the common corundum aggregate, and the slag resistant mechanism of microporous corundum material was revealed. The results show that the slag resistance of the microporous corundum material is superior to that of the common corundum aggregate,the SEM and EDX show that on the reaction interface between microporous corundum and molten slag,a continuous isolation layer with a large quantity of CA_2 and CA_6columnar crystals is formed; while the common corundum aggregate reacts with the molten slag interface to form a discontinuous isolation layer of columnar crystals,through which a lot of molten slag corrodes or permeates into the aggregate. The mechanism is mainly that the microporous structure is more advantageous to nucleation and growth of CA_2 and CA_6 columnar crystals; in the reaction with the aggregate,the molten slag gets saturated and the critical solution thickness of the microporous corundum and the common corundum is 0. 16 μm and 0. 34 μm,respectively,this is caused by the smaller microporous corundum aggregate pores; and the smaller pores also increase the second phase ripening rate of microporous corundum,which is 9. 7 times of that of the common corundum.

Effect of Cerium on Mechanical Performance and Electrical Conductivity of Aluminum Rod for Electrical Purpose

The effect of rare earth element Ce on mechanical performance and electrical conductivity of aluminum rod for electrical purpose were studied under industrial production condition. Using optical microscope, SEM, TEM, EDS and X-ray diffractometer, the microstructure and phase composition of aluminum rod were measured and analyzed. The results indicate that the content of rare earth element Ce is between 0.05%～0.16% in the aluminum rod for electrical purpose. Its tensile strength is enhanced to some extent. The research also discovers that the tensile strength is enhanced remarkably with impurity element Si content increases. Because influence of Si is big to the conductivity, the Si content should be controlled continuously strictly in the aluminum for electrical purpose. Adding rare earth element Ce reduces the solid solubility of Si in the aluminum matrix, and the negative effect of Si on the aluminum conductor reduces effectively. So the limit of in Si content in aluminum rod for electrical purpose can be relaxed moderately.

Influence of t-ZrO_2 addition on mechanical property and electrical conductivity of YSZ electrolyte

8YSZ material that has high electrical conductivity is widely used as electrolytes for solid oxide fuel cells (SOFCs). But its low strength and low fracture toughness hampered the development of SOFCs. In order to find a best method to improve the capability of YSZ electrolyte, the effects of 3Y-TZP additive on the density, strength, conductivity and microstructure were studied by means of X-ray diffraction and Vicker′s hardness apparatus. The strength and conductivity of YSZ electrolyte doped with different amounts of 3Y-TZP were determined. It is shown that the samples sintered at 1450 ℃ for 2 h are the best in properties. When 3Y-TZP powders are added to the YSZ system, the results demonstrate that strength of the electrolyte increases remarkably, and the fracture toughness is improved. The electrical conductivity is lowered only slightly. The results display that the flexural strength and the fracture toughness of ceramics with 30wt.% TZP reach 300 MPa and 3.7 MPa·m1/2, respectively, and the conductivity at 1000 ℃ reaches 0.11 S·cm-1.

POLYMERIC IONIC CONDUCTORS MODIFIED WITH POLAR GROUPS:PART Ⅰ. IONIC CONDUCTION AND MECHANICAL PROPERTY OF LI-COMPLEX BASED ON ACRYLAM ID E-COPOLYMERIZED METHACRYLATES

Acrylamide was introduced onto the chain of poly[oligo(oxyethylene) methacrylate] as a polar constituent, and the effect of its presence on the mechanical strength and ionic conduction properties of Li-salt complex based on the resultant copolymer was investigated. The introduction of the polar constituent raises chain rigidity, retards crystallization of oligo(oxyethylene) domain and promotes the dissociation of lithium salt. The factors work on the mechanical and conduction properties synergistically, therefore both of the properties are improved simultaneously as the consequence of acrylamide-introduction.

Effect of Ce on castability,mechanical properties and electric conductivity of commercial purity aluminum

Effects of Ce addition on microstructure,castability(fluidity and hot tearing sensitivity),mechanical properties and electric conductivity of commercial purity aluminum(CP-AI) were investigated through microstructure observation and performance tests.Results show that adding Ce in a CP-AI can considerably refine the grains,and has an important influence on the amount,crystallographic forms,and distribution of secondary phases.Addition of Ce also has a large impact on the fluidity and hot tearing sensitivity(HTS) of the CP-AI.With the addition of Ce from 0.1wt.%to 0.5wt.%,the fluidity of CP-AI is first increased remarkably and then decreased,and the HTS has an opposite response.The best castability of the studied alloys appears to be at 0.2wt.%-0.3wt.%Ce addition.The remarkable improvement in castability is attributed to the considerable refinement of grain structure.Ce addition can also lead to a significant rise in electric conductivity.The maximum conductivity of the as-cast CP-AI is 59.7%IACS with an addition of 0.2wt.%Ce.The T7 heat treatment can further improves the conductivity to 60.7%IACS.The Ce-induced evolution of the secondary phases is believed to be the mechanism for it.