Modification strategies improving the electrochemical and structural stability of high-Ni cathode materials

With the increasing spotlight in electric vehicles,there is a growing demand for high-energy-density batteries to enhance driving range.Consequently,several studies have been conducted on high-energy-density LiNi_(x)Co_(y)Mn_(z)O_(2)cathodes.However,there is a limit to permanent performance deterioration because of side reactions caused by moisture in the atmosphere and continuous microcracks during cycling as the Ni content to express high energy increases and the content of Mn and Co that maintain structural and electrochemical stabilization decreases.The direct modification of the surface and bulk regions aims to enhance the capacity and long-term performance of high-Ni cathode materials.Therefore,an efficient modification requires a study based on a thorough understanding of the degradation mechanisms in the surface and bulk region.In this review,a comprehensive analysis of various modifications,including doping,coating,concentration gradient,and single crystals,is conducted to solve degradation issues along with an analysis of the overall degradation mechanism occurring in high-Ni cathode materials.It also summarizes recent research developments related to the following modifications,aims to provide notable points and directions for post-studies,and provides valuable references for the commercialization of stable high-energy-density cathode materials.

Solution-processing approach of nanomaterials toward an artificial sensory system

Artificial sensory systems have emerged as pivotal technologies to bridge the gap between the virtual and real-world,replicating human senses to interact intelligently with external stimuli.To practically apply artificial sensory systems in the real-world,it is essential to mass-produce nanomaterials with ensured sensitivity and selectivity,purify them for desired functions,and integrate them into large-area sensory devices through assembly techniques.A comprehensive understanding of each process parameter from material processing to device assembly is crucial for achieving a high-performing artificial sensory system.This review provides a technological framework for fabricating high-performance artificial sensory systems,covering material processing to device integrations.We introduce recent approaches for dispersing and purifying various nanomaterials including 0D,1D,and 2D nanomaterials.We then highlight advanced coating and printing techniques of the solution-processed nanomaterials based on representative three methods including(i)evaporation-based assembly,(ii)assisted assembly,and(iii)direct patterning.We explore the application and performances of these solution-processed materials and printing methods in fabricating sensory devices mimicking five human senses including vision,olfaction,gustation,hearing,and tactile perception.Finally,we suggest an outlook for possible future research directions to solve the remaining challenges of the artificial sensory systems such as ambient stability,device consistency,and integration with AI-based software.

Progress of Materials and Devices for Neuromorphic Vision Sensors

The latest developments in bio-inspired neuromorphic vision sensors can be summarized in 3 keywords:smaller,faster,and smarter.(1)Smaller:Devices are becoming more compact by integrating previously separated components such as sensors,memory,and processing units.As a prime example,the transition from traditional sensory vision computing to in-sensor vision computing has shown clear benefits,such as simpler circuitry,lower power consumption,and less data redundancy.(2)Swifter:Owing to the nature of physics,smaller and more integrated devices can detect,process,and react to input more quickly.In addition,the methods for sensing and processing optical information using various materials(such as oxide semiconductors)are evolving.(3)Smarter:Owing to these two main research directions,we can expect advanced applications such as adaptive vision sensors,collision sensors,and nociceptive sensors.This review mainly focuses on the recent progress,working mechanisms,image pre-processing techniques,and advanced features of two types of neuromorphic vision sensors based on near-sensor and in-sensor vision computing methodologies.

Stable immobilization of lithium polysulfides using three-dimensional ordered mesoporous Mn_(2)O_(3) as the host material in lithium-sulfur batteries

Lithium-sulfur batteries(LSBs)have drawn significant attention owing to their high theoretical discharge capacity and energy density.However,the dissolution of long-chain polysulfides into the electrolyte during the charge and discharge process(“shuttle effect”)results in fast capacity fading and inferior electrochemical performance.In this study,Mn_(2)O_(3)with an ordered mesoporous structure(OM-Mn_(2)O_(3))was designed as a cathode host for LSBs via KIT-6 hard templating,to effectively inhibit the polysulfide shuttle effect.OM-Mn_(2)O_(3)offers numerous pores to confine sulfur and tightly anchor the dissolved polysulfides through the combined effects of strong polar-polar interactions,polysulfides,and sulfur chain catenation.The OM-Mn_(2)O_(3)/S composite electrode delivered a discharge capacity of 561 mAh g^(-1) after 250 cycles at 0.5 C owing to the excellent performance of OM-Mn_(2)O_(3).Furthermore,it retained a discharge capacity of 628mA h g^(-1) even at a rate of 2 C,which was significantly higher than that of a pristine sulfur electrode(206mA h g^(-1)).These findings provide a prospective strategy for designing cathode materials for high-performance LSBs.

Multifunctional MXene/Carbon Nanotube Janus Film for Electromagnetic Shielding and Infrared Shielding/Detection in Harsh Environments

Multifunctional,flexible,and robust thin films capable of operating in demanding harsh temperature environments are crucial for various cutting-edge applications.This study presents a multifunctional Janus film integrating highly-crystalline Ti_(3)C_(2)T_(x) MXene and mechanically-robust carbon nanotube(CNT)film through strong hydrogen bonding.The hybrid film not only exhibits high electrical conductivity(4250 S cm^(-1)),but also demonstrates robust mechanical strength and durability in both extremely low and high temperature environments,showing exceptional resistance to thermal shock.This hybrid Janus film of 15μm thickness reveals remarkable multifunctionality,including efficient electromagnetic shielding effectiveness of 72 dB in X band frequency range,excellent infrared(IR)shielding capability with an average emissivity of 0.09(a minimal value of 0.02),superior thermal camouflage performance over a wide temperature range(−1 to 300℃)achieving a notable reduction in the radiated temperature by 243℃ against a background temperature of 300℃,and outstanding IR detection capability characterized by a 44%increase in resistance when exposed to 250 W IR radiation.This multifunctional MXene/CNT Janus film offers a feasible solution for electromagnetic shielding and IR shielding/detection under challenging conditions.

Microstructure and mechanical property of A356 based composite by friction stir processing

Friction stir processing （FSP） was used to incorporate SiC particles into the matrix of A356 Al alloy to form composite material. Constant tool rotation speed of 1800 r/min and travel speed of 127 mm/min were used in this study. The base metal （BM） shows the hypoeutectic Al-Si dendrite structure. The microstructure of the stir zone （SZ） is very different from that of the BM. The eutectic Si and SiC particles are dispersed homogeneously in primary Al solid solution. The thermo-mechanically affected zone （TMAZ）, where the original microstructure is greatly deformed, is characterized by dispersed eutectic Si and SiC particles aligned along the rotational direction of the tool. The hardness of the SZ shows higher value than that of the BM because some defects are remarkably reduced and the eutectic Si and SiC particles are dispersed over the SZ.

High Temperature Corrosion of Fe-C-S Cast Irons in Oxidizing and Sulfidizing Atmospheres

The corrosion behavior of spheroidal graphite and flake graphite cast irons was studied in oxidizing and sulfidizing atmospheres between 600 and 800℃ for 50 h. The corrosion rate in the sulfidizing atmosphere was faster than that in air above 700℃, due to the formation of the Fe0.975S sulfide. The corrosion rate of the spheroidal graphite cast iron was similar to that of the flake graphite cast iron.

Effect of SiC particles on microstructure and mechanical property of friction stir processed AA6061-T4

Friction stir processing of AA6061-T4 alloy with SiC particles was successfully carried out.SiC particles were uniformly dispersed into an AA6061-T4 matrix.Also SiC particles promoted the grain refinement of the AA6061-T4 matrix by FSP.The mean grain size of the stir zone (SZ) with the SiC particles was obviously smaller than that of the stir zone without the SiC particles.The microhardness of the SZ with the SiC particles reached about HV80 due to the grain refinement and the distribution of the SiC particles.

Electrodeposited copper oxides with a suppressed interfacial amorphous phase using mixed-crystalline ITO and their enhanced photoelectrochemical performances

The effectiveness of photoelectrochemical(PEC)water splitting is significantly restricted by insufficient light harvesting,rapid charge recombination,and slow water reduction kinetics.Since the presence of amorphous phases in the interfaces hinders the overcome of these inherent limitations,a photoelectrode must be built strategically.Herein,we artificially controlled the crystallographic orientation of indium tin oxide(ITO)to determine the orientation with the smallest lattice mismatch at the Cu_(2)O interface,thus significantly reducing the amorphous phase in the early stage of electrodeposition nucleation.The[222]/[400]mixed orientation ITO primarily exposed the{400}surface planes and accelerated charge transfer by forming an optimal interface with preferentially grown(111)oriented Cu_(2)O and minimized amorphous region.In addition,the ITO surface energy was calculated using density functional theory to theoretically verify which plane is more active for growing the photoactivation layer.The rationally designed ITO/Cu_(2)O/Al-dope Zn O/TiO_(2)/Rh-P device,with each layer serving a specific purpose,achieved a photocurrent density of 8.23 mA cm^(-2)at 0 VRHEunder AM 1.5 G illumination,providing a standard method for effective solar-to-hydrogen conversion photocathodes.

Roles of humidity and heat treatment temperatures on YBa_2Cu_3O_(7-x) coated conductors by trifluoroacetic acid-metal organic deposition process

YBa2Cu3O7-x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition(TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure,degree of texture and critical properties of the films were evaluated.In order to understand the combined effects of the humidity and the calcining and firing temperatures on critical properties,heat-treatment was performed at various temperatures with the other processing variables fixed.The films were calcined at 400-430 ℃ and fired at 750-800 ℃ in a 0-12.1% humidified Ar-O2 atmosphere.The texture was determined by pole-figure analysis.The amount of the BaF2 phase was effectively reduced and a sharp and strong biaxial texture was formed under a humidified atmosphere,which led to increased critical properties.In addition,the microstructure varied significantly with firing temperature but changed little with calcining temperature.The highest IC of 40 A/cm-width,which corresponds to JC value of 1.8 MA/cm2,was obtained for the films fired at 775 ℃(in 12.1% humidity) after calcining at 400-430 ℃.It is likely that the highest IC value is due to the formation of a more pure YBCO phase,c-axis grains,and a denser microstructure.

Alveolar macrophage phagocytosis-evading inhaled microgels incorporating nintedanib-PLGA nanoparticles and pirfenidone-liposomes for improved treatment of pulmonary fibrosis

Idiopathic pulmonary fibrosis(IPF)is a chronic inflammatory and fibrotic response-driven lung disease that is difficult to cure because it manifests excessive profibrotic cytokines(e.g.,TGF-β),activated myofibroblasts,and accumulated extracellular matrix(ECM).In an attempt to develop an inhalation formulation with enhanced antifibrotic efficacy,we sought to fabricate unique aerosolizable inhaled microgels(μGel)that contain nintedanib-poly(lactic-co-glycolic acid)(PLGA)nanoparticles(NPs;n-PN)and pirfenidone-liposomes(p-LP).The aero-μGel was~12μm,resisted phagocytosis by alveolar macrophages in vitro and in vivo,and protected inner-entrapped n-PN and p-LP.The n-PN/p-LP@aero-μGel caused enhanced/extended antifibrotic efficacy in a bleomycin-induced pulmonary fibrosis mouse presumably due to prolonged lung residence.Consequently,the results obtained by intratracheal aerosol insufflation of our n-PN/p-LP@aero-μGel twice a week were much better than those by as many as seven doses of single or mixed applications of n-PN or p-LP.The antifibrotic/pharmacokinetic results for the n-PN/p-LP@aero-μGel included reduced fibrosis progression,restored lung physiological functions,deactivated myofibroblasts,inhibited TGF-βprogression,and suppressed ECM component production(collagen I andα-SMA)along with prolonged lung retention time.We believe that our n-PN/p-LP@aero-μGel increased the local availability of both nintedanib and pirfenidone due to evasion of alveolar macrophage phagocytosis and prolonged lung retention with reduced systemic distribution.Through this approach,our inhalation formulation subsequently attenuated fibrosis progression and improved lung function.Importantly,these results hold profound implications in the therapeutic potential of our n-PN/p-LP@aero-μGel to serve as a clinically promising platform,providing significant advancements for improved treatment of many respiratory diseases including IFP.

Trifunctional robust electrocatalysts based on 3D Fe/N-doped carbon nanocubes encapsulating Co4N nanoparticles for efficient battery-powered water electrolyzers

Herein,we have designed a highly active and robust trifunctional electrocatalyst derived from Prussian blue analogs,where Co_(4)N nanoparticles are encapsulated by Fe embedded in N-doped carbon nanocubes to synthesize hierarchically structured Co_(4)N@Fe/N-C for rechargeable zinc-air batteries and overall water-splitting electrolyzers.As confirmed by theoretical and experimental results,the high intrinsic oxygen reduction reaction,oxygen evolution reaction,and hydrogen evolution reaction activities of Co_(4)N@Fe/N-C were attributed to the formation of the heterointerface and the modulated local electronic structure.Moreover,Co_(4)N@Fe/N-C induced improvement in these trifunctional electrocatalytic activities owing to the hierarchical hollow nanocube structure,uniform distribution of Co_(4)N,and conductive encapsulation by Fe/N-C.Thus,the rechargeable zinc-air battery with Co_(4)N@Fe/N-C delivers a high specific capacity of 789.9 mAh g^(-1) and stable voltage profiles over 500 cycles.Furthermore,the overall water electrolyzer with Co_(4)N@Fe/N-C achieved better durability and rate performance than that with the Pt/C and IrO2 catalysts,delivering a high Faradaic efficiency of 96.4%.Along with the great potential of the integrated water electrolyzer powered by a zinc-air battery for practical applications,therefore,the mechanistic understanding and active site identification provide valuable insights into the rational design of advanced multifunctional electrocatalysts for energy storage and conversion.

Characterization of flexible copper laminates fabricated by Cu electro-plating process

Flexible copper clad laminates(FCCLs) were fabricated using the electro-plating process and the combined effect of the current density and plating time on their surface morphology,texture,hardness,electrical resistivity and folding behavior was evaluated.To achieve Cu layers with similar thicknesses,the current density was varied in the range of 0.2-3 A/dm2 and the plating time was controlled in the range of 0.5-7.5 h to compensate for the variation of the current density.The surface morphology,hardness,and folding behavior were characterized by atomic force microscopy,nanoindentation technique and Massachusett Institute of Technology folding endurance test,respectively.The X-ray diffraction patterns indicated that the Cu phase was formed without any secondary phases;however,the preferred orientation changed from(220) to(111) as the current density increased over 1 A/dm2.In addition,it was observed that the root-mean-square and hardness values decreased when the current density increased and the plating time decreased simultaneously.The electrical resistivity was as low as approximately 21 nΩ·m and the number of cycles without failure in the folding test was over 15 000,which were comparable to those of commercial FCCLs.

Fabrication of two-layer flexible copper clad laminate by electroless-Cu plating on surface modified polyimide

A flexible copper clad laminate(FCCL) was fabricated using electroless-and electro-Cu plating processes and the effects of pre-treatment time on the adhesion strength of the FCCL were evaluated based on interfacial morphology.The neutralization and catalyst time were varied in the range of 0-20 min and 0.1-10 min,respectively,and the interfacial condition of the FCCL was characterized by atomic force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS).It is observed that the peel strength increases significantly as the neutralization and catalyst time increase.Peel strength as high as 7.2-7.3 N/cm is obtained as the neutralization and catalyst time increase up to 20 min and 10 min,respectively,which is comparable to the strength achieved by the conventional laminating and sputtering processes.These improvements are probably due to an increase in the surface roughness of polyimide(PI),the activated surface condition,and the adsorption of palladium ions/atoms(Pd) on the PI surface which act as nucleation sites for Cu.

Fabrication of SiC_p/AA5083 composite via friction stir welding

Microstructure and mechanical properties of SiCp /AA5083 composite fabricated by friction stir welding (FSW) were investigated.The influence of the number of FSW passes on the distribution of SiC particles and mechanical properties in the joint was studied.After one pass,the SiC particles were entangled in the upper side of the stir zone (SZ).However,the particle distribution became more uniform after two passes due to the repeated stirring of the joint.As the SiC particles facilitate the grain refinement in the SZ by the pinning effect,the particle including region has much smaller grain size than the SZ without SiC particles.The SiCp /AA5083 composite region exhibits a Vickers hardness of HV90,which is much higher than the value of HV80 in the SZ produced by FSW without SiC particles.

Bioresorbable Multilayer Photonic Cavities as Temporary Implants for Tether-Free Measurements of Regional Tissue Temperatures

Objective and Impact Statement.Real-time monitoring of the temperatures of regional tissue microenvironments can serve as the diagnostic basis for treating various health conditions and diseases.Introduction.Traditional thermal sensors allow measurements at surfaces or at near-surface regions of the skin or of certain body cavities.Evaluations at depth require implanted devices connected to external readout electronics via physical interfaces that lead to risks for infection and movement constraints for the patient.Also,surgical extraction procedures after a period of need can introduce additional risks and costs.Methods.Here,we report a wireless,bioresorbable class of temperature sensor that exploits multilayer photonic cavities,for continuous optical measurements of regional,deep-tissue microenvironments over a timeframe of interest followed by complete clearance via natural body processes.Results.The designs decouple the influence of detection angle from temperature on the reflection spectra,to enable high accuracy in sensing,as supported by in vitro experiments and optical simulations.Studies with devices implanted into subcutaneous tissues of both awake,freely moving and asleep animal models illustrate the applicability of this technology for in vivo measurements.Conclusion.The results demonstrate the use of bioresorbable materials in advanced photonic structures with unique capabilities in tracking of thermal signatures of tissue microenvironments,with potential relevance to human healthcare.

High-Throughput Pb Recycling for Perovskite Solar Cells Using Biomimetic Whitlockite

Pb contamination in aquatic environments causes severe pollution;therefore,harmless absorbents are required.In this study,we report a novel synthesis of whitlockite(WH,Ca_(18)Mg_(2)(HPO_(4))_(2)(PO_(4))_(12)),which is the second most abundant biomineral in human bone,and its application as a high-performing Pb^(2+)absorbent.Hydroxyapatite(HAP)and WH are prepared via a simple precipitation method.The Pb2+absorption performance and mechanism of the synthesized biominerals are investigated in aqueous solutions at neutral pH.The results demonstrate that WH exhibits an excellent Pb2+absorption capacity of 2339 mg g^(−1),which is 1.68 times higher than the recorded value for HAP.Furthermore,the absorbed Pb^(2+) ions are recycled into high-purity PbI_(2).This is employed as a precursor for the fabrication of perovskite solar cells(PSCs),resulting in a conversion efficiency of 19.00%comparable to that of commercial PbI2 powder(99.99%purity).Our approach provides an efficient way to remove Pb^(2+)ions from water and reuse them in the recycling of PSCs.

Artificial optoelectronic synapse based on spatiotemporal irradiation to source-sharing circuitry of synaptic phototransistors

To overcome the intrinsic inefficiency of the von Neumann architecture,neuromorphic devices that perform analog vector–matrix multiplication have been highlighted for achieving power-and time-efficient data processing.In particular,artificial synapses,of which conductance should be programmed to represent the synaptic weights of the artificial neural network,have been intensively researched to realize neuromorphic devices.Here,inspired by excitatory and inhibitory synapses,we develop an artificial optoelectronic synapse that shows both potentiation and depression characteristics triggered only by optical inputs.The design of the artificial optoelectronic synapse,in which excitatory and inhibitory synaptic phototransistors are serially connected,enables these characteristics by spatiotemporally irradiating the phototransistor channels with optical pulses.Furthermore,a negative synaptic weight can be realized without the need for electronic components such as comparators.With such attributes,the artificial optoelectronic synapse is demonstrated to classify three digits with a high recognition rate(98.3%)and perform image preprocessing via analog vector-matrix multiplication.

Photophysical,optical,and photocatalytic hydrogen production properties of layered-type BaNb_(2-x)Ta_(x)P_(2)O_(11)(x=0,0.5,1.0,1.5,and 2.0)compounds

Layered-type metal phosphates of BaNb_(2-x)Ta_(x)P_(2)O_(11)(x=0,0.5,1.0,1.5,and 2.0)were synthesized using a solid-state reaction method.The photophysical,optical,and photocatalytic hydrogen production properties of the resulting powders were investigated for the first time.Phase-pure and homogeneous powders with irregular morphologies were obtained at a calcination temperature of 1200℃.As the Ta content increased,the interlayer distance along the c-axis increased by up to 0.14%.Additionally,the optical bandgap values increased from 3.32 to 3.59 eV.The energy band positions were estimated from the Mott–Schottky measurements.BaNb_(2)P_(2)O_(11)(x=0)exhibited the lowest conduction band edge position(-0.14 V vs.the normal hydrogen electrode,NHE),which is located above the water reduction potential(0.0 V vs.NHE).In comparison,BaTa_(2)P_(2)O_(11)(x=2.0)exhibited the highest conduction band edge position(-0.29 V vs.NHE),comparable to that of TiO_(2).The photocatalytic activity for hydrogen produced from splitting water was measured under ultraviolet light irradiation.Notably,BaTa_(2)P_(2)O_(11)exhibited the highest activity(7.3μmol/h),which was 15 and 10 times larger than BaNb_(2)P_(2)O_(11)(0.5μmol/h)and nano-TiO_(2)(0.7μmol/h),respectively.The activity of BaTa_(2)P_(2)O_(11)increased to 24.4μmol/h after deposition of the NiO_(x)co-catalyst(1 wt.%),which remained stable during continuous operation(~35 h).

Origin of the giant persistent photoconductivity in LaAlO_(3)/SrTiO_(3)heterostructures probed by noise spectroscopy

LaAlO_(3)/SrTiO_(3)(LAO/STO)heterostructures have shown a strong persistent photoconductivity(PPC)at room temperature.The abnormally strong PPC has attracted immense research interest due to its possible applications in optically-tunable electronic devices.Despite its promise,the fundamental understanding of the PPC in the LAO/STO heterostructures is still elusive.Herein,we report that the giant PPC origi-nates from the photo-induced valence change in oxygen vacancies near the LAO/STO interface.Our spec-tral analysis of the photocurrent and the model-fitting study consistently show that the ionized oxygen vacancies near the interface are neutralized during the electron relaxation process.They hinder the complete relaxation of the photoexcited electrons by the deeply-located oxygen vacancies and result in the strong PPC.The change in the ionization state distribution of the oxygen vacancies is probed by the per-sistent noise behavior at the frequency between 1 kHz and 20 kHz regime.These results provide insight into the role of oxygen vacancies in influencing the internal charge distribution and triggering the PPC phenomena in complex oxide heterostructures.