In the development of rechargeable lithium ion batteries(LIBs),silicon anodes have attracted much attention because of their extremely high theoretical capacity,relatively low Li-insertion voltage and the availability...In the development of rechargeable lithium ion batteries(LIBs),silicon anodes have attracted much attention because of their extremely high theoretical capacity,relatively low Li-insertion voltage and the availability of silicon resources.However,their large volume expansion and fragile solid electrolyte interface(SEI)film hinder their commercial application.To solve these problems,Si has been combined with various carbon materials to increase their structural stability and improve their interface properties.The use of different carbon materials,such as amorphous carbon and graphite,as three-dimensional(3D)protective anode coatings that help buffer mechanical strain and isolate the electrolyte is detailed,and novel methods for applying the coatings are outlined.However,carbon materials used as a protective layer still have some disadvantages,necessitating their modification.Recent developments have focused on modifying the protective carbon shells,and substitutes for the carbon have been suggested.展开更多
This work adopts a multi⁃step etching⁃heat treatment strategy to prepare porous silicon microsphere com⁃posite with Sb⁃Sn surface modification and carbon coating(pSi/Sb⁃Sn@C),using industrial grade SiAl alloy micro⁃sp...This work adopts a multi⁃step etching⁃heat treatment strategy to prepare porous silicon microsphere com⁃posite with Sb⁃Sn surface modification and carbon coating(pSi/Sb⁃Sn@C),using industrial grade SiAl alloy micro⁃spheres as a precursor.pSi/Sb⁃Sn@C had a 3D structure with bimetallic(Sb⁃Sn)modified porous silicon micro⁃spheres(pSi/Sb⁃Sn)as the core and carbon coating as the shell.Carbon shells can improve the electronic conductivi⁃ty and mechanical stability of porous silicon microspheres,which is beneficial for obtaining a stable solid electrolyte interface(SEI)film.The 3D porous core promotes the diffusion of lithium ions,increases the intercalation/delithia⁃tion active sites,and buffers the volume expansion during the intercalation process.The introduction of active met⁃als(Sb⁃Sn)can improve the conductivity of the composite and contribute to a certain amount of lithium storage ca⁃pacity.Due to its unique composition and microstructure,pSi/Sb⁃Sn@C showed a reversible capacity of 1247.4 mAh·g^(-1) after 300 charge/discharge cycles at a current density of 1.0 A·g^(-1),demonstrating excellent rate lithium storage performance and enhanced electrochemical cycling stability.展开更多
A novel synthesis method of carbon-coated LiNil/3Mnl/3COl/302 cathode material for lithium-ion battery was reported. The carbon coating was produced from a precursor, glucose, by microwave-pyrolysis method. The prepar...A novel synthesis method of carbon-coated LiNil/3Mnl/3COl/302 cathode material for lithium-ion battery was reported. The carbon coating was produced from a precursor, glucose, by microwave-pyrolysis method. The prepared powders were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, X-ray fluorescence （XRF） and charge/discharge tests. XRD results indicate that the carbon coating does not change the phase structure of LiNil/3Mnl/3C01/302 material. SEM results show that the surface of spherical carbon-coated material becomes rough. Electrochemical performance results show that the carbon coating can improve the cycling performance of LiNii/3Mnl/3C01/302. The specific discharge capacity retention of the carbon-coated LiNi1/3Mnt/3Col/30z reached 85.0%-96.0% at the 50th cycle at 0.2C rate, and the specific discharge capacity retention is improved at a high rate.展开更多
The tribology behaviors of Ti6Al7Nb,its alloy with N-ion implantation,and its alloy with diamond-like carbon(DLC)coating were investigated in artificial saliva.Fretting wear tests of untreated,N-ion implanted and DLC ...The tribology behaviors of Ti6Al7Nb,its alloy with N-ion implantation,and its alloy with diamond-like carbon(DLC)coating were investigated in artificial saliva.Fretting wear tests of untreated,N-ion implanted and DLC coated Ti6Al7Nb alloys plate against a Si3N4ball were carried out on a reciprocating sliding fretting wear test rig.Based on the analysis of X-ray diffraction,Raman spectroscopy,3-D profiler,SEM morphologies and frictional kinetics behavior analysis,the damage behavior of surface modification layer was discussed in detail.The results indicated that the fretting wear behavior of Ti6Al7Nb alloy with N-ion implantation was increased with the dose increase of the implanted nitrogen ions.Moreover,the DLC-coated Ti6Al7Nb alloy with low ion implantation could improve the fretting wear behavior greatly.In addition,the Ti6Al7Nb with DLC coating had better ncorrosion resistance due to the special compact structure.All results suggested that the Ti6Al7Nb with DLC coating had better wear resistance than that with N-ion implantation in artificial saliva.展开更多
To address the issues of large volume change and low conductivity of silicon(Si)materials,carbon coatings have been widely employed as surface protection agent and conductive medium to encapsulate the Si materials,whi...To address the issues of large volume change and low conductivity of silicon(Si)materials,carbon coatings have been widely employed as surface protection agent and conductive medium to encapsulate the Si materials,which can improve the electrochemical performance of Si-based electrodes.There has been a strong demand to gain a deeper understanding of the impact of efficient carbon coating over the lithiation and delithiation process of Si materials.Here,we report the first observation of the extended two-phase transformation of carbon-coated Si nanoparticles(Si/C)during electrochemical processes.The Si/C nanoparticles were prepared by sintering Si nanoparticles with polyvinylidene chloride precursor.The Si/C electrode underwent a two-phase transition during the first 20 cycles at 0.2 C,but started to engage in solid solution reaction when the ordered compact carbon coating began to crack.Under higher current density conditions,the electrode was also found to be involved in solid solution reaction,which,however,was due to the overwhelming demand of kinetic property rather than the breaking of the carbon coating.In comparison,the Si/C composites prepared with sucrose possessed more disordered and porous carbon structures,and presented solid solution reaction throughout the entire cycling process.展开更多
Earth-abundant magnetite(Fe_(3)O_(4))as cathode materials in aqueous zinc-ion batteries(ZIBs)is limited by its very low capacity and poor cycling.Here,a combined strategy based on carbon coating and electrolyte optimi...Earth-abundant magnetite(Fe_(3)O_(4))as cathode materials in aqueous zinc-ion batteries(ZIBs)is limited by its very low capacity and poor cycling.Here,a combined strategy based on carbon coating and electrolyte optimization is adopted to improve the performance of Fe_(3)O_(4).The Zn-Fe_(3)O_(4)@C batteries display specific capacities of 93 mAh g^(−1) and 81%capacity retention after 200 cycles.Such performance is attributed to the enhanced electrical conductivity and structural stability of Fe_(3)O_(4)@C nanocomposites with suppressed iron dissolution.Experimental analysis reveals that the charge storage is contributed by diffusion-limited redox reactions and surface-controlled pseudocapacitance.A stretchable Zn-Fe_(3)O_(4)@C battery is further fabricated,showing stable performance when it is bent or stretched.Fe_(3)O_(4) is a promising cathode material for cost-effective,safe,sustainable and wearable energy supplies.展开更多
Copper nanowires(CuNWs)are promising electrode materials,especially for used in flexible and transparent electrodes,due to their advantages of earth-abundant,low-cost,high conductivity and flexibility.However,the poor...Copper nanowires(CuNWs)are promising electrode materials,especially for used in flexible and transparent electrodes,due to their advantages of earth-abundant,low-cost,high conductivity and flexibility.However,the poor stability of CuNWs against oxidation and chemic-al corrosion seriously hinders their practical applications.Herein,we propose a facile strategy to improve the chemical stability of CuNWs by in situ coating of carbon protective layer on top of them through hydrothermal carbonization method.The influential factors on the growth of carbon film including the concentration of the glucose precursor(carbon source),hydrothermal temperature,and hydrothermal time are sys-tematically studied.By tailoring these factors,carbon layers with thickness of 3-8 nm can be uniformly grown on CuNWs with appropriate glucose concentration around 80 mg·mL−1,hydrothermal temperature of 160-170°C,and hydrothermal time of 1-3 h.The as-prepared carbon-coated CuNWs show excellent resistance against corrosion and oxidation,and are of great potential to use broadly in various optoelectronic devices.展开更多
Carbon-coating is a simple and practical method to improve the electrochemical performance of soft carbon anode for fast-charging lithium-ion battery,e.g.,reducing the loss of active lithium during the formation of th...Carbon-coating is a simple and practical method to improve the electrochemical performance of soft carbon anode for fast-charging lithium-ion battery,e.g.,reducing the loss of active lithium during the formation of the solid electrolyte interface(SEI)film,and thereby improving the initial coulombic efficiency.However,the systematic study of relationships between carbon-coating layer properties and electrochemical performances is still lacking.Therefore,two soft carbon materials with different carbon-coating layers were used as model materials,which were prepared by vapor-phase method and solid-phase method,respectively.SEM,TEM,XRD and Raman were conducted to characterize the structural evolution of the soft carbon in the coating process.CV,GCPL,EIS and GITT were conducted to analyze the electrochemical performance of carbon-coating soft carbon.This work provides a good guidance for the development of fast-charging soft carbon material.展开更多
Pyrolytic carbon(PyC) coatings are deposited on the Nextel-440 fiber fabrics by chemical vapor deposition(CVD).The dielectric properties of the Nextel-440 fiber fabrics with PyC coatings(Nextel-440/PyC) are investigat...Pyrolytic carbon(PyC) coatings are deposited on the Nextel-440 fiber fabrics by chemical vapor deposition(CVD).The dielectric properties of the Nextel-440 fiber fabrics with PyC coatings(Nextel-440/PyC) are investigated in a temperature range from room temperature to 700℃ in X-band. Compared with the permittivity of the original Nextel-440 received,the complex permittivity of the Nextel-440/PyC(the real part εand the imaginary part ε), is significantly improved: εof the Nextel-440/PyC has a positive temperature coefficient, in contrast, εof the Nextel-440/PyC exhibits a negative temperature coefficient. Moreover, the reflection loss in units of d B is calculated. The results indicate that the microwave absorbing properties of the Nextel-440/PyC coatings is enhanced at 700℃ compared with that at lower temperatures.展开更多
Cycling and rate performance of natural graphite is still limited by the sluggish kinetics of lithium ions,which can be improved by surface modifications in previous research.Among these methods,amorphous carbon coati...Cycling and rate performance of natural graphite is still limited by the sluggish kinetics of lithium ions,which can be improved by surface modifications in previous research.Among these methods,amorphous carbon coating has been proved to be mature and efficient.However,the significance of coating uniformity in relation to solid electrolyte interphase(SEI)has been largely overlooked.In this study,the uniformity of amorphous carbon coating is adjusted by the particle size of pitch.When discharged-charged at 1 C,graphite half-cells with such uniform coating show 90.3%of the capacity at 0.1 C,while that is 82.1%for non-uniform coating.Additionally,improved initial coulombic efficiency and cycling stability are demonstrated.These can be attributed to graphite anodes featuring a uniform carbon coating that promotes effective and homogeneous LiF formation within the inorganic matrix.This leads to the establishment of a stabilized SEI,confirmed by time-of-flight secondary ion mass spectrometry(TOF-SIMS).This work provides valuable reference into the rational control of graphite interfaces for high electrochemical performance.展开更多
The effect of diamond-like carbon(DLC)coating(fabricated by cathodic arc deposition)on mechanical properties,tribological behavior and corrosion performance of the Ni−Al−bronze(NAB)alloy was investigated.Nano-hardness...The effect of diamond-like carbon(DLC)coating(fabricated by cathodic arc deposition)on mechanical properties,tribological behavior and corrosion performance of the Ni−Al−bronze(NAB)alloy was investigated.Nano-hardness and pin-on-plate test showed that DLC coating had a greater hardness compared with NAB alloy.Besides,the decrease in friction coefficient from 0.2 for NAB substrate to 0.13 for the DLC-coated sample was observed.Potentiodynamic polarization and EIS results showed that the corrosion current density decreased from 2.5μA/cm2 for bare NAB alloy to 0.14μA/cm2 for DLC-coated sample in 3.5 wt.%NaCl solution.Moreover,the charge transfer resistance at the substrate−electrolyte interface increased from 3.3 kΩ·cm2 for NAB alloy to 120.8 kΩ·cm2 for DLC-coated alloy,which indicated an increase in corrosion resistance due to the DLC coating.展开更多
Composite coatings consisting of carbon and polytetrafluoroethylene(PTFE) were prepared on Ti alloy substrate by a simple two-step process of hydrothermal and impregnation. The morphology, composition, hydrophobic and...Composite coatings consisting of carbon and polytetrafluoroethylene(PTFE) were prepared on Ti alloy substrate by a simple two-step process of hydrothermal and impregnation. The morphology, composition, hydrophobic and corrosion properties of the composite coatings were characterized by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR), water contact angle method, X-ray photoelectron spectroscopy(XPS) and electrochemical technique, respectively. The effect of PTFE content on the corrosion properties of the composite coatings was studied. It is found that the composite coating film exhibits a full coverage with uniformly distributed PTFE when 0.1 mol/L of glucose is used as carbon source and 20 wt.% PTFE suspension as impregnating solution. The coating with 20 wt.% PTFE has a good bonding strength with Ti plate and exhibits excellent hydrophobic property with a water contact angle of 142.3° as well as superior corrosion resistance with corrosion current density as low as 0.0045 μA/cm^2. With regard to its excellent hydrophobicity and corrosion resistance, the carbon-PTFE composite coating may find potential application in automobiles and metal corrosion industries.展开更多
Layered alkali-metal titanate materials are considered as attractive anodes for sodium ion batteries due to their favorable safety and low cost.However,their practical implementation faces major challenges of low elec...Layered alkali-metal titanate materials are considered as attractive anodes for sodium ion batteries due to their favorable safety and low cost.However,their practical implementation faces major challenges of low electronic conductivity and inevitable volume variation during Na^(+)intercalation and de-intercalation,which are generally difficult to conquer by a single modification method.Herein,a synergistic ally enhancing strategy to promote the electrochemical performance of Na_(2)Ti_(2)O_(5)nanowire array anode via simultaneous hydrogenation and carbon coating is developed.Hydrogenation leads to partially reduced titanium;together with conductive carbon layer,it endows Na_(2)Ti_(2)O_(5)with fast electron transport and structural stability.The resulting H-Na_(2)Ti_(2)O_(5)@C anode exhibits enhanced rate capability(8.0C,165 mAh·g^(-1))and stable cycle performance up to 1000 times in sodium-ion half-cells(the capacity of H-Na_(2)Ti_(2)O_(5)without carbon fades drastically after only 100 cycles).In addition,a newcoupling full cell is further designed with graphene hybridized high-voltage Na_(3)(VO_(0.5))_(2)(PO4)_(2)F_(2)as cathode,capable of delivering a high specific energy density of 212.1 Wh·kg^(-1)(based on the mass of both anode and cathode)and good rate and cycling stability.This work may offer inspiration for synergistic optimization of electrode materials for advanced electrochemical energy storage devices.展开更多
The superlattice La-Y-Ni-based hydrogen storage alloys have high discharge capacity and are easy to prepare.However,there is still a gap in commercial applications because of the severe corrosion of the alloys in elec...The superlattice La-Y-Ni-based hydrogen storage alloys have high discharge capacity and are easy to prepare.However,there is still a gap in commercial applications because of the severe corrosion of the alloys in electrolyte and poor high-rate dischargeability(HRD).Therefore,(LaSmY)(NiMnAl)_(3.5) alloy was prepared by magnetic levitation induction melting,and then the alloy was coated with different contents(0.1 wt%-1.0 wt%) of nano-carbons by low-temperature sintering with sucrose as the carbon source in this work.The results show that the cyclic stability and HRD of the alloy first increase and then decrease with the increase of carbon contents.The kinetic results show that the electrocatalytic activity and conductivity of the alloy electrodes can be enhanced by carbon coating.The electrochemical properties of the alloy are the best when the carbon coating content is 0.3 wt%.Compared with the uncoated alloy,the maximum discharge capacity(C_(max)) improves from 354.5 to 359.0 mAh/g,the capacity retention rate after 300 cycles(S_(300)) enhances from 73.15% to 80.01%,and the HRD_(1200) of the alloy enhances from 74.39% to 74.39%.展开更多
The"one pot"simultaneous carbon coating and doping of TiO_(2) materials by the hydrolysis of TiCl4 in fructose is reported.The synergistic effect of carbon doping and coating of TiO_(2) to significantly boos...The"one pot"simultaneous carbon coating and doping of TiO_(2) materials by the hydrolysis of TiCl4 in fructose is reported.The synergistic effect of carbon doping and coating of TiO_(2) to significantly boost textural,optical and electronic properties and photocurrent of TiO_(2) for high performance visible light H2 production from water splitting has been comprehensively investigated.Carbon doping can significantly increase the thermal stability,thus inhibiting the phase transformation of the Titania material from anatase to rutile while carbon coating can suppress the grain aggregation of TiO_(2).The synergy of carbon doping and coating can not only ensure an enhanced narrowing effect of the electronic band gap of TiO_(2) thus extending the absorption of photocatalysts to the visible regions,but also promote dramatically the separation of electron-hole pairs.Owing to these synergistic effects,the carbon coated and doped TiO_(2) shows much superior photocatalytic activity for both degradation of organics and photocatalytic/photoelectro chemical(PEC)water splitting under simulated sunlight illumination.The photocatalytic activity of obtained materials can reach 5,4 and 2 times higher than that of pristine TiO_(2),carbon doped TiO_(2) and carbon coated TiO_(2),respectively in the degradation of organic pollutants.The carbon coated and doped TiO_(2) materials exhibited more than 37 times and hundreds of times photocurrent enhancement under simulated sunlight and visible light,respectively compared to that of pristine TiO_(2).The present work providing new comprehensive understanding on carbon coating and doping effect could be very helpful for the development of advanced TiO_(2) materials for a large series of applications.展开更多
Li_(3)FeF_(6)has been the focus of research of fluorine-based cathode materials for lithium-ion batteries.Because of the low electronic conductivity of Li3 FeF6,the decrease of particle size,by an energyconsuming long...Li_(3)FeF_(6)has been the focus of research of fluorine-based cathode materials for lithium-ion batteries.Because of the low electronic conductivity of Li3 FeF6,the decrease of particle size,by an energyconsuming long-time ball milling process with carbon,is necessary to achieve a high electrochemical performance.The most successful method to enhance electrochemical activity,carbon coating,seemed to be impracticable,so far,for sensitive fluorides like Li3 FeF6.In this work,carbon coating on Li3 FeF6 particles has been successfully achieved for the first time,while avoiding both extended hydrolysis and Fe(Ⅲ)-Fe(Ⅱ)reduction.The heat treatment and atmosphere,yielding the maximal transformation of organic carbon to both graphitised and disordered carbon,has been determined.Carbon coating,with a thickness of approximately 2.5 nm,has been achieved by controlled thermal decomposition of glucose,under air,at 300℃.Raman and X-ray photoelectron spectroscopy(XPS)experiments have proved the existence of carbon and Fe2O3 on the surface of Li3FeF6 nanoparticles.XPS spectroscopy indicates the presence of organic residues from glucose decomposition.Attempts to further reduce the orga nic carbon content results in a decrease of the amorphous carbon coating layer.Optimised carbon-coated Li3 FeF6 nanoparticles deliver 122 mA h g^(-1)(85%of theoretical capacity)significantly higher than that of a noncoated sample(58 mA h g^(-1)).Even more,a significant beneficial effect of carbon coating on both capacity retention and coulombic efficiency is observed.展开更多
In the glass molding process,the sticking reaction and fatigue wear between the glass and mold hinder the service life and functional application of the mold at the elevated temperature.To improve the chemical inertne...In the glass molding process,the sticking reaction and fatigue wear between the glass and mold hinder the service life and functional application of the mold at the elevated temperature.To improve the chemical inertness and anti-friction properties of the mold,an amorphous carbon coating was synthesized on the tungsten carbide-cobalt(WC–8Co)substrate by magnetron sputtering.The friction behavior between the glass and carbon coating has a significant influence on the functional protection and service life of the mold.Therefore,the glass ring compression tests were conducted to measure the friction coefficient and friction force of the contact interface between the glass and amorphous carbon coating at the high temperature.Meanwhile,the detailed characterization of the amorphous carbon coating was performed to study the microstructure evolution and surface topography of the amorphous carbon coating during glass molding process by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Ramon spectroscopy,and atomic force microscope(AFM).The results showed that the amorphous carbon coating exhibited excellent thermal stability,but weak shear friction strength.The friction coefficient between the glass and coating depended on the temperature.Besides,the service life of the coating was governed by the friction force of the contact interface,processing conditions,and composition diffusion.This work provides a better understanding of the application of carbon coatings in the glass molding.展开更多
A series of silver-doped graphite-like carbon coatings was prepared on the surface of aluminum alloy using the magnetron sputtering method. The spontaneous escape behavior and inhibition mechanism of silver from graph...A series of silver-doped graphite-like carbon coatings was prepared on the surface of aluminum alloy using the magnetron sputtering method. The spontaneous escape behavior and inhibition mechanism of silver from graphite-like carbon coating were studied. The results showed that when the sample prepared with a 0.01-A current on the silver target was placed in an atmospheric environment for 0.5 h, an apparent silver escape phenomenon could be observed. However, the silver escape phenomenon was not observed for samples prepared with a 0.05-A current on the silver target if the sample was retained in a 10^（-1） Pa vacuum environment, even after 48 h. Compared with the sample placed in the atmospheric environment immediately after an ion plating process, the silver escape time lagged for 6 h. Nanometer-thick pure carbon coating coverage could effectively suppress silver escape. When the coating thickness reached700 nm, permanent retention of silver could be achieved in the silver-doped graphite-like carbon coating.As the silver residue content in the graphite-like carbon coating increased from 2.27 at.% to 5.35 at.%, the interfacial contact resistance of the coating decreased from 51mΩcm^2 to 6 mΩcm^2.展开更多
P-doping is an effective way to modulate the electronic structure and improve the Na+diffusion kinetics of TiO_(2), enabling enhanced electrochemical performance. However, it is a challenge to prepare TiO;with a high ...P-doping is an effective way to modulate the electronic structure and improve the Na+diffusion kinetics of TiO_(2), enabling enhanced electrochemical performance. However, it is a challenge to prepare TiO;with a high P-doping concentration starting from TiO_(2)in a crystalline state. In this work, we design a novel two-step route for constructing a carbon-coated anatase P-doping TiO_(2)nanospheres(denote as(PAn TSS)@NC) with high P-doping concentration, by utilizing amorphous TiO;nanospheres with the ultrahigh specific area as P-doping precursor firstly, and followed by carbon coating treatment. Experimental results demonstrate that P is successfully doped into the crystal lattice and carbon layer is well coated on the surface of TiO_(2), with P-doping and carbon-coating contents of ~13.5 wt% and 10.4 wt%, respectively,which results in the enhanced pseudocapacitive behavior as well as favorable Na+and electron transferring kinetics. The(P-AnTSS)@NC sample shows excellent rate and cycle performance, exhibiting specific capacities of 177 and 115 m Ah/g at 0.1 and 1.0 A/g after 150 and 2000 cycles, respectively.展开更多
Poor electron conductivity is the key issue influencing the rate capability of NaTi_(2)(PO_(4))_(3)(NTP).Hence,herein,polyacrylonitrile(PAN)was utilized as a NTP modifier by simply mixing NTP in a liquid PAN suspensio...Poor electron conductivity is the key issue influencing the rate capability of NaTi_(2)(PO_(4))_(3)(NTP).Hence,herein,polyacrylonitrile(PAN)was utilized as a NTP modifier by simply mixing NTP in a liquid PAN suspension,followed by sintering at 850℃ for 5 h.The product with a PAN/NTP mass ratio of 0.3 delivered splendid rate capabilities(achieving lithiation capacities of 282.9,243.0,207.1,173.1,133.5,and 257.5 mAh g^(−1) at 0.1,0.2,0.4,0.8,1.6,and 0.1 A^(−1),respectively)and excellent long cycling life(capacity retention of 165.5 mAh g^(−1) after 1200 cycles at 0.5 A g−1).Based on detailed structural and compositional characterizations,as well as cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS),the uniform N-doped carbon coating stemming from PAN carbonization around the NTP particles promoted electron transfer,while the oxygen vacancies induced by N-doping in NTP facilitated Li+diffusion.The boosted and well matched electronic and ionic conductivities give rise to the optimized electrochemical performance.展开更多
文摘In the development of rechargeable lithium ion batteries(LIBs),silicon anodes have attracted much attention because of their extremely high theoretical capacity,relatively low Li-insertion voltage and the availability of silicon resources.However,their large volume expansion and fragile solid electrolyte interface(SEI)film hinder their commercial application.To solve these problems,Si has been combined with various carbon materials to increase their structural stability and improve their interface properties.The use of different carbon materials,such as amorphous carbon and graphite,as three-dimensional(3D)protective anode coatings that help buffer mechanical strain and isolate the electrolyte is detailed,and novel methods for applying the coatings are outlined.However,carbon materials used as a protective layer still have some disadvantages,necessitating their modification.Recent developments have focused on modifying the protective carbon shells,and substitutes for the carbon have been suggested.
文摘This work adopts a multi⁃step etching⁃heat treatment strategy to prepare porous silicon microsphere com⁃posite with Sb⁃Sn surface modification and carbon coating(pSi/Sb⁃Sn@C),using industrial grade SiAl alloy micro⁃spheres as a precursor.pSi/Sb⁃Sn@C had a 3D structure with bimetallic(Sb⁃Sn)modified porous silicon micro⁃spheres(pSi/Sb⁃Sn)as the core and carbon coating as the shell.Carbon shells can improve the electronic conductivi⁃ty and mechanical stability of porous silicon microspheres,which is beneficial for obtaining a stable solid electrolyte interface(SEI)film.The 3D porous core promotes the diffusion of lithium ions,increases the intercalation/delithia⁃tion active sites,and buffers the volume expansion during the intercalation process.The introduction of active met⁃als(Sb⁃Sn)can improve the conductivity of the composite and contribute to a certain amount of lithium storage ca⁃pacity.Due to its unique composition and microstructure,pSi/Sb⁃Sn@C showed a reversible capacity of 1247.4 mAh·g^(-1) after 300 charge/discharge cycles at a current density of 1.0 A·g^(-1),demonstrating excellent rate lithium storage performance and enhanced electrochemical cycling stability.
基金Project(U1202272)supported by the National Natural Science Foundation of China
文摘A novel synthesis method of carbon-coated LiNil/3Mnl/3COl/302 cathode material for lithium-ion battery was reported. The carbon coating was produced from a precursor, glucose, by microwave-pyrolysis method. The prepared powders were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, X-ray fluorescence （XRF） and charge/discharge tests. XRD results indicate that the carbon coating does not change the phase structure of LiNil/3Mnl/3C01/302 material. SEM results show that the surface of spherical carbon-coated material becomes rough. Electrochemical performance results show that the carbon coating can improve the cycling performance of LiNii/3Mnl/3C01/302. The specific discharge capacity retention of the carbon-coated LiNi1/3Mnt/3Col/30z reached 85.0%-96.0% at the 50th cycle at 0.2C rate, and the specific discharge capacity retention is improved at a high rate.
文摘The tribology behaviors of Ti6Al7Nb,its alloy with N-ion implantation,and its alloy with diamond-like carbon(DLC)coating were investigated in artificial saliva.Fretting wear tests of untreated,N-ion implanted and DLC coated Ti6Al7Nb alloys plate against a Si3N4ball were carried out on a reciprocating sliding fretting wear test rig.Based on the analysis of X-ray diffraction,Raman spectroscopy,3-D profiler,SEM morphologies and frictional kinetics behavior analysis,the damage behavior of surface modification layer was discussed in detail.The results indicated that the fretting wear behavior of Ti6Al7Nb alloy with N-ion implantation was increased with the dose increase of the implanted nitrogen ions.Moreover,the DLC-coated Ti6Al7Nb alloy with low ion implantation could improve the fretting wear behavior greatly.In addition,the Ti6Al7Nb with DLC coating had better ncorrosion resistance due to the special compact structure.All results suggested that the Ti6Al7Nb with DLC coating had better wear resistance than that with N-ion implantation in artificial saliva.
基金This study is funded by the Assistant Secretary for Energy Efficiency,Vehicle Technologies Office of the U.S.Department of Energy,under the Si Consortium Program.Electron microscopy experiments are conducted at the National Centre for Electron Microscopy and the Molecular Foundry located at Lawrence Berkeley National Laboratory is supported by the Director,Office of Science,Office of Basic Energy Sciences,the U.S.Department of Energy under Contract No.DE-AC02-05CH11231.
文摘To address the issues of large volume change and low conductivity of silicon(Si)materials,carbon coatings have been widely employed as surface protection agent and conductive medium to encapsulate the Si materials,which can improve the electrochemical performance of Si-based electrodes.There has been a strong demand to gain a deeper understanding of the impact of efficient carbon coating over the lithiation and delithiation process of Si materials.Here,we report the first observation of the extended two-phase transformation of carbon-coated Si nanoparticles(Si/C)during electrochemical processes.The Si/C nanoparticles were prepared by sintering Si nanoparticles with polyvinylidene chloride precursor.The Si/C electrode underwent a two-phase transition during the first 20 cycles at 0.2 C,but started to engage in solid solution reaction when the ordered compact carbon coating began to crack.Under higher current density conditions,the electrode was also found to be involved in solid solution reaction,which,however,was due to the overwhelming demand of kinetic property rather than the breaking of the carbon coating.In comparison,the Si/C composites prepared with sucrose possessed more disordered and porous carbon structures,and presented solid solution reaction throughout the entire cycling process.
基金This work was supported by National Natural Science Foundation of China(51873088)the Tianjin Municipal Science and Technology Commission(18JCZDJC38400)in China.
文摘Earth-abundant magnetite(Fe_(3)O_(4))as cathode materials in aqueous zinc-ion batteries(ZIBs)is limited by its very low capacity and poor cycling.Here,a combined strategy based on carbon coating and electrolyte optimization is adopted to improve the performance of Fe_(3)O_(4).The Zn-Fe_(3)O_(4)@C batteries display specific capacities of 93 mAh g^(−1) and 81%capacity retention after 200 cycles.Such performance is attributed to the enhanced electrical conductivity and structural stability of Fe_(3)O_(4)@C nanocomposites with suppressed iron dissolution.Experimental analysis reveals that the charge storage is contributed by diffusion-limited redox reactions and surface-controlled pseudocapacitance.A stretchable Zn-Fe_(3)O_(4)@C battery is further fabricated,showing stable performance when it is bent or stretched.Fe_(3)O_(4) is a promising cathode material for cost-effective,safe,sustainable and wearable energy supplies.
基金the National Natural Science Foundation of China(No.21403089)the Fundamental Research Funds for the Central Universities,China(No.2042020kf0195).
文摘Copper nanowires(CuNWs)are promising electrode materials,especially for used in flexible and transparent electrodes,due to their advantages of earth-abundant,low-cost,high conductivity and flexibility.However,the poor stability of CuNWs against oxidation and chemic-al corrosion seriously hinders their practical applications.Herein,we propose a facile strategy to improve the chemical stability of CuNWs by in situ coating of carbon protective layer on top of them through hydrothermal carbonization method.The influential factors on the growth of carbon film including the concentration of the glucose precursor(carbon source),hydrothermal temperature,and hydrothermal time are sys-tematically studied.By tailoring these factors,carbon layers with thickness of 3-8 nm can be uniformly grown on CuNWs with appropriate glucose concentration around 80 mg·mL−1,hydrothermal temperature of 160-170°C,and hydrothermal time of 1-3 h.The as-prepared carbon-coated CuNWs show excellent resistance against corrosion and oxidation,and are of great potential to use broadly in various optoelectronic devices.
基金Science and Technology Program of Zhejiang Province(2022C01071)Major Science and technology projects in Ningbo(2022Z026).
文摘Carbon-coating is a simple and practical method to improve the electrochemical performance of soft carbon anode for fast-charging lithium-ion battery,e.g.,reducing the loss of active lithium during the formation of the solid electrolyte interface(SEI)film,and thereby improving the initial coulombic efficiency.However,the systematic study of relationships between carbon-coating layer properties and electrochemical performances is still lacking.Therefore,two soft carbon materials with different carbon-coating layers were used as model materials,which were prepared by vapor-phase method and solid-phase method,respectively.SEM,TEM,XRD and Raman were conducted to characterize the structural evolution of the soft carbon in the coating process.CV,GCPL,EIS and GITT were conducted to analyze the electrochemical performance of carbon-coating soft carbon.This work provides a good guidance for the development of fast-charging soft carbon material.
基金supported by the National Natural Science Foundation of China(Grant No.51072165)the Fund of the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University,China(Grant Nos.KP201307 and SKLSP201313)
文摘Pyrolytic carbon(PyC) coatings are deposited on the Nextel-440 fiber fabrics by chemical vapor deposition(CVD).The dielectric properties of the Nextel-440 fiber fabrics with PyC coatings(Nextel-440/PyC) are investigated in a temperature range from room temperature to 700℃ in X-band. Compared with the permittivity of the original Nextel-440 received,the complex permittivity of the Nextel-440/PyC(the real part εand the imaginary part ε), is significantly improved: εof the Nextel-440/PyC has a positive temperature coefficient, in contrast, εof the Nextel-440/PyC exhibits a negative temperature coefficient. Moreover, the reflection loss in units of d B is calculated. The results indicate that the microwave absorbing properties of the Nextel-440/PyC coatings is enhanced at 700℃ compared with that at lower temperatures.
基金Project(52377220)supported by the National Natural Science Foundation of ChinaProject(kq2208265)supported by the Natural Science Foundation of Changsha,Hunan Province,ChinaProject supported by State Key Laboratory of Powder Metallurgy(Central South University,Changsha,China)。
文摘Cycling and rate performance of natural graphite is still limited by the sluggish kinetics of lithium ions,which can be improved by surface modifications in previous research.Among these methods,amorphous carbon coating has been proved to be mature and efficient.However,the significance of coating uniformity in relation to solid electrolyte interphase(SEI)has been largely overlooked.In this study,the uniformity of amorphous carbon coating is adjusted by the particle size of pitch.When discharged-charged at 1 C,graphite half-cells with such uniform coating show 90.3%of the capacity at 0.1 C,while that is 82.1%for non-uniform coating.Additionally,improved initial coulombic efficiency and cycling stability are demonstrated.These can be attributed to graphite anodes featuring a uniform carbon coating that promotes effective and homogeneous LiF formation within the inorganic matrix.This leads to the establishment of a stabilized SEI,confirmed by time-of-flight secondary ion mass spectrometry(TOF-SIMS).This work provides valuable reference into the rational control of graphite interfaces for high electrochemical performance.
文摘The effect of diamond-like carbon(DLC)coating(fabricated by cathodic arc deposition)on mechanical properties,tribological behavior and corrosion performance of the Ni−Al−bronze(NAB)alloy was investigated.Nano-hardness and pin-on-plate test showed that DLC coating had a greater hardness compared with NAB alloy.Besides,the decrease in friction coefficient from 0.2 for NAB substrate to 0.13 for the DLC-coated sample was observed.Potentiodynamic polarization and EIS results showed that the corrosion current density decreased from 2.5μA/cm2 for bare NAB alloy to 0.14μA/cm2 for DLC-coated sample in 3.5 wt.%NaCl solution.Moreover,the charge transfer resistance at the substrate−electrolyte interface increased from 3.3 kΩ·cm2 for NAB alloy to 120.8 kΩ·cm2 for DLC-coated alloy,which indicated an increase in corrosion resistance due to the DLC coating.
基金Project(2018YFB1502500) supported by the National Key Research and Development Program of ChinaProject supported by State Key Laboratory of Powder Metallurgy,Central South University,China+1 种基金Projects(21506258,51774127) supported by the National Natural Science Foundation of ChinaProject(2019RS2067) supported by the Science and Technology Planning Project of Hunan Province,China
文摘Composite coatings consisting of carbon and polytetrafluoroethylene(PTFE) were prepared on Ti alloy substrate by a simple two-step process of hydrothermal and impregnation. The morphology, composition, hydrophobic and corrosion properties of the composite coatings were characterized by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR), water contact angle method, X-ray photoelectron spectroscopy(XPS) and electrochemical technique, respectively. The effect of PTFE content on the corrosion properties of the composite coatings was studied. It is found that the composite coating film exhibits a full coverage with uniformly distributed PTFE when 0.1 mol/L of glucose is used as carbon source and 20 wt.% PTFE suspension as impregnating solution. The coating with 20 wt.% PTFE has a good bonding strength with Ti plate and exhibits excellent hydrophobic property with a water contact angle of 142.3° as well as superior corrosion resistance with corrosion current density as low as 0.0045 μA/cm^2. With regard to its excellent hydrophobicity and corrosion resistance, the carbon-PTFE composite coating may find potential application in automobiles and metal corrosion industries.
基金financially supported by the National Natural Science Foundation of China(Nos.52072136,51872104,51972257 and 52172229)the National Key R&D Program of China(No.2016YFA0202602)the Fundamental Research Funds for the Central Universities(No.WUT:2021IVA115)
文摘Layered alkali-metal titanate materials are considered as attractive anodes for sodium ion batteries due to their favorable safety and low cost.However,their practical implementation faces major challenges of low electronic conductivity and inevitable volume variation during Na^(+)intercalation and de-intercalation,which are generally difficult to conquer by a single modification method.Herein,a synergistic ally enhancing strategy to promote the electrochemical performance of Na_(2)Ti_(2)O_(5)nanowire array anode via simultaneous hydrogenation and carbon coating is developed.Hydrogenation leads to partially reduced titanium;together with conductive carbon layer,it endows Na_(2)Ti_(2)O_(5)with fast electron transport and structural stability.The resulting H-Na_(2)Ti_(2)O_(5)@C anode exhibits enhanced rate capability(8.0C,165 mAh·g^(-1))and stable cycle performance up to 1000 times in sodium-ion half-cells(the capacity of H-Na_(2)Ti_(2)O_(5)without carbon fades drastically after only 100 cycles).In addition,a newcoupling full cell is further designed with graphene hybridized high-voltage Na_(3)(VO_(0.5))_(2)(PO4)_(2)F_(2)as cathode,capable of delivering a high specific energy density of 212.1 Wh·kg^(-1)(based on the mass of both anode and cathode)and good rate and cycling stability.This work may offer inspiration for synergistic optimization of electrode materials for advanced electrochemical energy storage devices.
基金The financial supports provided by the National Key R&D Program of China (2019YFE0103600)。
文摘The superlattice La-Y-Ni-based hydrogen storage alloys have high discharge capacity and are easy to prepare.However,there is still a gap in commercial applications because of the severe corrosion of the alloys in electrolyte and poor high-rate dischargeability(HRD).Therefore,(LaSmY)(NiMnAl)_(3.5) alloy was prepared by magnetic levitation induction melting,and then the alloy was coated with different contents(0.1 wt%-1.0 wt%) of nano-carbons by low-temperature sintering with sucrose as the carbon source in this work.The results show that the cyclic stability and HRD of the alloy first increase and then decrease with the increase of carbon contents.The kinetic results show that the electrocatalytic activity and conductivity of the alloy electrodes can be enhanced by carbon coating.The electrochemical properties of the alloy are the best when the carbon coating content is 0.3 wt%.Compared with the uncoated alloy,the maximum discharge capacity(C_(max)) improves from 354.5 to 359.0 mAh/g,the capacity retention rate after 300 cycles(S_(300)) enhances from 73.15% to 80.01%,and the HRD_(1200) of the alloy enhances from 74.39% to 74.39%.
基金supported by the National Natural Science Foundation of China(U1663225,21805280)Program for Changjiang Scholars and Innovative Research Team in University(IRT15R52)+2 种基金the Minstry of Education of Chinathe 111 Project(Grant No.B20002)from the Ministry of Science and Technology and the Ministry of Education of China,China,European Commission,Interreg V France-Wallonie-Vlaanderen(Depollutair)the Fundamental Research Funds for the Central Universities(WUT:2017III001),Chinathe FJIRSM&IUE Joint Research Fund(RHZX-2018-002),China for supporting this work。
文摘The"one pot"simultaneous carbon coating and doping of TiO_(2) materials by the hydrolysis of TiCl4 in fructose is reported.The synergistic effect of carbon doping and coating of TiO_(2) to significantly boost textural,optical and electronic properties and photocurrent of TiO_(2) for high performance visible light H2 production from water splitting has been comprehensively investigated.Carbon doping can significantly increase the thermal stability,thus inhibiting the phase transformation of the Titania material from anatase to rutile while carbon coating can suppress the grain aggregation of TiO_(2).The synergy of carbon doping and coating can not only ensure an enhanced narrowing effect of the electronic band gap of TiO_(2) thus extending the absorption of photocatalysts to the visible regions,but also promote dramatically the separation of electron-hole pairs.Owing to these synergistic effects,the carbon coated and doped TiO_(2) shows much superior photocatalytic activity for both degradation of organics and photocatalytic/photoelectro chemical(PEC)water splitting under simulated sunlight illumination.The photocatalytic activity of obtained materials can reach 5,4 and 2 times higher than that of pristine TiO_(2),carbon doped TiO_(2) and carbon coated TiO_(2),respectively in the degradation of organic pollutants.The carbon coated and doped TiO_(2) materials exhibited more than 37 times and hundreds of times photocurrent enhancement under simulated sunlight and visible light,respectively compared to that of pristine TiO_(2).The present work providing new comprehensive understanding on carbon coating and doping effect could be very helpful for the development of advanced TiO_(2) materials for a large series of applications.
基金This work was financially supported by the“Agencia Estatal de Investigación/Fondo Europeo de Desarrollo Regional”(FEDER/UE)and“Comunidad de Madrid”(Nos.MAT2016-78632-C4-1-R and S2013/MIT-2753)Characterisation techniques for this research were partially financed by the EU funds(Nos.POPW.01.03.00-20.034/09-00 and POPW.01.03.00-20-004/11-00)。
文摘Li_(3)FeF_(6)has been the focus of research of fluorine-based cathode materials for lithium-ion batteries.Because of the low electronic conductivity of Li3 FeF6,the decrease of particle size,by an energyconsuming long-time ball milling process with carbon,is necessary to achieve a high electrochemical performance.The most successful method to enhance electrochemical activity,carbon coating,seemed to be impracticable,so far,for sensitive fluorides like Li3 FeF6.In this work,carbon coating on Li3 FeF6 particles has been successfully achieved for the first time,while avoiding both extended hydrolysis and Fe(Ⅲ)-Fe(Ⅱ)reduction.The heat treatment and atmosphere,yielding the maximal transformation of organic carbon to both graphitised and disordered carbon,has been determined.Carbon coating,with a thickness of approximately 2.5 nm,has been achieved by controlled thermal decomposition of glucose,under air,at 300℃.Raman and X-ray photoelectron spectroscopy(XPS)experiments have proved the existence of carbon and Fe2O3 on the surface of Li3FeF6 nanoparticles.XPS spectroscopy indicates the presence of organic residues from glucose decomposition.Attempts to further reduce the orga nic carbon content results in a decrease of the amorphous carbon coating layer.Optimised carbon-coated Li3 FeF6 nanoparticles deliver 122 mA h g^(-1)(85%of theoretical capacity)significantly higher than that of a noncoated sample(58 mA h g^(-1)).Even more,a significant beneficial effect of carbon coating on both capacity retention and coulombic efficiency is observed.
基金The authors gratefully acknowledge the financial support of the Natural Science Foundation of Guangdong Province(2018A030313466)the assistance on the observation received from the Electron Microscope Center of the Shenzhen University.
文摘In the glass molding process,the sticking reaction and fatigue wear between the glass and mold hinder the service life and functional application of the mold at the elevated temperature.To improve the chemical inertness and anti-friction properties of the mold,an amorphous carbon coating was synthesized on the tungsten carbide-cobalt(WC–8Co)substrate by magnetron sputtering.The friction behavior between the glass and carbon coating has a significant influence on the functional protection and service life of the mold.Therefore,the glass ring compression tests were conducted to measure the friction coefficient and friction force of the contact interface between the glass and amorphous carbon coating at the high temperature.Meanwhile,the detailed characterization of the amorphous carbon coating was performed to study the microstructure evolution and surface topography of the amorphous carbon coating during glass molding process by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Ramon spectroscopy,and atomic force microscope(AFM).The results showed that the amorphous carbon coating exhibited excellent thermal stability,but weak shear friction strength.The friction coefficient between the glass and coating depended on the temperature.Besides,the service life of the coating was governed by the friction force of the contact interface,processing conditions,and composition diffusion.This work provides a better understanding of the application of carbon coatings in the glass molding.
基金financial support of the project from the National Natural Science Foundation of China (Nos. 51571114 and 51401106)the Natural Science Foundation of Jiangsu Province (No. BK20130935)
文摘A series of silver-doped graphite-like carbon coatings was prepared on the surface of aluminum alloy using the magnetron sputtering method. The spontaneous escape behavior and inhibition mechanism of silver from graphite-like carbon coating were studied. The results showed that when the sample prepared with a 0.01-A current on the silver target was placed in an atmospheric environment for 0.5 h, an apparent silver escape phenomenon could be observed. However, the silver escape phenomenon was not observed for samples prepared with a 0.05-A current on the silver target if the sample was retained in a 10^（-1） Pa vacuum environment, even after 48 h. Compared with the sample placed in the atmospheric environment immediately after an ion plating process, the silver escape time lagged for 6 h. Nanometer-thick pure carbon coating coverage could effectively suppress silver escape. When the coating thickness reached700 nm, permanent retention of silver could be achieved in the silver-doped graphite-like carbon coating.As the silver residue content in the graphite-like carbon coating increased from 2.27 at.% to 5.35 at.%, the interfacial contact resistance of the coating decreased from 51mΩcm^2 to 6 mΩcm^2.
基金supported by the National Natural Science Foundation of China (No. 21875071)the Guangdong key R&D Program of China (No. 2019B090908001)。
文摘P-doping is an effective way to modulate the electronic structure and improve the Na+diffusion kinetics of TiO_(2), enabling enhanced electrochemical performance. However, it is a challenge to prepare TiO;with a high P-doping concentration starting from TiO_(2)in a crystalline state. In this work, we design a novel two-step route for constructing a carbon-coated anatase P-doping TiO_(2)nanospheres(denote as(PAn TSS)@NC) with high P-doping concentration, by utilizing amorphous TiO;nanospheres with the ultrahigh specific area as P-doping precursor firstly, and followed by carbon coating treatment. Experimental results demonstrate that P is successfully doped into the crystal lattice and carbon layer is well coated on the surface of TiO_(2), with P-doping and carbon-coating contents of ~13.5 wt% and 10.4 wt%, respectively,which results in the enhanced pseudocapacitive behavior as well as favorable Na+and electron transferring kinetics. The(P-AnTSS)@NC sample shows excellent rate and cycle performance, exhibiting specific capacities of 177 and 115 m Ah/g at 0.1 and 1.0 A/g after 150 and 2000 cycles, respectively.
基金This work was supported by Project ZR2022QE165 of Shandong Provincial Natural Science Foundation,China.
文摘Poor electron conductivity is the key issue influencing the rate capability of NaTi_(2)(PO_(4))_(3)(NTP).Hence,herein,polyacrylonitrile(PAN)was utilized as a NTP modifier by simply mixing NTP in a liquid PAN suspension,followed by sintering at 850℃ for 5 h.The product with a PAN/NTP mass ratio of 0.3 delivered splendid rate capabilities(achieving lithiation capacities of 282.9,243.0,207.1,173.1,133.5,and 257.5 mAh g^(−1) at 0.1,0.2,0.4,0.8,1.6,and 0.1 A^(−1),respectively)and excellent long cycling life(capacity retention of 165.5 mAh g^(−1) after 1200 cycles at 0.5 A g−1).Based on detailed structural and compositional characterizations,as well as cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS),the uniform N-doped carbon coating stemming from PAN carbonization around the NTP particles promoted electron transfer,while the oxygen vacancies induced by N-doping in NTP facilitated Li+diffusion.The boosted and well matched electronic and ionic conductivities give rise to the optimized electrochemical performance.
