Mixed polyanion phosphate Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)is regarded as the most promising cathode material for sodium-ion batteries(SIBs),due to its high structural stability and low-cost environmental frien...Mixed polyanion phosphate Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)is regarded as the most promising cathode material for sodium-ion batteries(SIBs),due to its high structural stability and low-cost environmental friendliness.However,its intrinsic low conductivity and sluggish Na^(+)diffusion restricted the fast-charge and low-temperature sodium storage.Herein,an NFPP composite encapsulated by in-situ pyrolytic carbon and coupled with expanded graphite(NFPP@C/EG)was constructed via a sol-gel method followed by a ballmill procedure.Due to the dual-carbon modified strategy,this NFPP@C/EG only enhanced the electronic conductivity,but also endowed more channels for Na^(+)diffusion.As cathode for SIBs,the optimized NFPP(M-NFPP@C/EG)delivers excellent rate capability(capacity of~80.5 mAh/g at 50 C)and outstanding cycling stability(11000 cycles at 50 C with capacity retention of 89.85%).Additionally,cyclic voltammetry(CV)confirmed that its sodium storage behavior is pseudocapacitance-controlled,with in-situ electrochemical impedance spectroscopy(EIS)further elucidating improvements in electrode reaction kinetics.At lower temperatures(0℃),M-NFPP@C/EG demonstrated exceptional cycling performance(8800 cycles at 10 C with capacity retention of 95.81%).Moreover,pouch cells also exhibited excellent stability.This research demonstrates the feasibility of a dual carbon modification strategy in enhancing NFPP and proposes a low-cost,high-rate,and ultra-stable cathode material for SIBs.展开更多
Zero-valent iron（ZⅥ） was loaded on expanded graphite（EG） to produce a composite material（EG-ZⅥ） for efficient removal of hexavalent chromium（Cr（Ⅵ））. EG and EG-ZⅥ were characterized by X-ray diffraction（...Zero-valent iron（ZⅥ） was loaded on expanded graphite（EG） to produce a composite material（EG-ZⅥ） for efficient removal of hexavalent chromium（Cr（Ⅵ））. EG and EG-ZⅥ were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）,Fourier-transform infrared（FTIR） spectroscopy and Brunauer–Emmett–Teller（BET） analysis. EG-ZⅥ had a high specific surface area and contained sub-micron sized particles of zero-valent iron. Batch experiments were employed to evaluate the Cr（Ⅵ） removal performance. The results showed that the Cr（Ⅵ） removal rate was 98.80% for EG-ZⅥ,which was higher than that for both EG（10.00%） and ZⅥ（29.80%）. Furthermore, the removal rate of Cr（Ⅵ） by EG-ZⅥ showed little dependence on solution p H within a p H range of 1–9.Even at pH 11, a Cr（Ⅵ） removal rate of 62.44% was obtained after reaction for 1 hr. EG-ZⅥ could enhance the removal of Cr（Ⅵ） via chemical reduction and physical adsorption,respectively. X-ray photoelectron spectroscopy（XPS） was used to analyze the mechanisms of Cr（Ⅵ） removal, which indicated that the ZⅥ loaded on the surface was oxidized, and the removed Cr（Ⅵ） was immobilized via the formation of Cr（III） hydroxide and Cr（III）–Fe（III）hydroxide/oxyhydroxide on the surface of EG-ZⅥ.展开更多
A Ni Fe_2O_4/expanded graphite(Ni Fe_2O_4/EG)nanocomposite was prepared via a simple and inexpensive synthesis method. Its lithium storage properties were studied with the goal of applying it as an anode in a lithium-...A Ni Fe_2O_4/expanded graphite(Ni Fe_2O_4/EG)nanocomposite was prepared via a simple and inexpensive synthesis method. Its lithium storage properties were studied with the goal of applying it as an anode in a lithium-ion battery. The obtained nanocomposite exhibited a good cycle performance, with a capacity of 601 m Ah g^(-1)at a current of 1 A g^(-1)after 800 cycles. This good performance may beattributed to the enhanced electrical conductivity and layered structure of the EG. Its high mechanical strength could postpone the disintegration of the nanocomposite structure,efficiently accommodate volume changes in the Ni Fe_2O_4-based anodes, and alleviate aggregation of Ni Fe_2O_4 nanoparticles.展开更多
A new method for preparing expanded graphite-based composites （EGCs） was developed.The obtained samples were characterized by scanning electron microscopy （SEM）,transmission electron microscope （TEM） and nitroge...A new method for preparing expanded graphite-based composites （EGCs） was developed.The obtained samples were characterized by scanning electron microscopy （SEM）,transmission electron microscope （TEM） and nitrogen adsorption.The experimental results indicated that the EGCs was not simply mechanical mixture of EG and activated carbon,instead the activated carbon was coated on the surface of interior and external pores of the EG in the form of thin carbon layer.The thickness of the activated carbon layer was nearly one hundred nanometers by calculation.It was shown that the higher the impregnation ratio and the activation temperature were,the easier the porosity development would be.And the BET surface area and the total pore volume were as high as 1978 m2/g and 0.9917 cm3/g respectively at 350℃ with an impregnation ratio of 0.9.展开更多
Expanded graphite(EG) films exhibit potential use in a wide field including thermal management, conductive applications,and electromagnetic interference(EMI) shielding. However, their poor tensile strength and brittle...Expanded graphite(EG) films exhibit potential use in a wide field including thermal management, conductive applications,and electromagnetic interference(EMI) shielding. However, their poor tensile strength and brittleness are crucial deficiencies for commercial applications. To address these defects, in our work, natural rubber(NR) is employed to improve EG films for better mechanical strength and flexibility. The origin of the strengthening effect of EG films by the addition of natural rubber mainly arises from the formation of a simulate shell structure. Compared to the neat EG films, the addition of merely 2 wt% NR can give rise to superior ductility. Further, the loading of 10 wt% NR realizes a significant mechanical enhancement of the EG/NR films, i.e., 2.4 and 11.4 times increase in tensile strength and elongation at break, respectively. Besides, EG/NR films containing 10 wt% NR can still sustain excellent thermal and electric conductivities of 173 W·m^-1·K^-1 and 75 S·cm^-1, respectively. Furthermore, a very high EMI of 41.4 dB is achieved as the film thickness reaches 50 μm. Thus, the lightweight EG/NR films with comprehensive performance as well as their virtue of green and simple large-scale preparation endow them with the possibility of designing next-generation flexible electronics.展开更多
The expandable graphite(EG)modified TiO_(2) nanocomposites were prepared by the high shearmethod using the TiO_(2) nanoparticles(NPs)and EG as precursors,in which the amount of EG doped in TiO_(2) was 10 wt.%.Followed...The expandable graphite(EG)modified TiO_(2) nanocomposites were prepared by the high shearmethod using the TiO_(2) nanoparticles(NPs)and EG as precursors,in which the amount of EG doped in TiO_(2) was 10 wt.%.Followed by the impregnation method,adjusting the pH of the solution to 10,and using the electrostatic adsorption to achieve spatial confinement,the Pt elementswere mainly distributed on the exposed TiO_(2),thus generating the Pt/10EG-TiO_(2)-10 catalyst.The best CO oxidation activity with the excellent resistance to H_(2)O and SO_(2) was obtained over the Pt/10EG-TiO_(2)-10 catalyst:CO conversion after 36 hr of the reaction was ca.85%under the harsh condition of 10 vol.%H_(2)O and 100 ppm SO_(2) at a high gaseous hourly space velocity(GHSV)of 400,000 hr−1.Physicochemical properties of the catalystswere characterized by various techniques.The results showed that the electrostatic adsorption,which riveted the Pt elements mainly on the exposed TiO_(2) of the support surface,reduced the dispersion of Pt NPs on EG and achieved the effective dispersion of Pt NPs,hence significantly improving CO oxidation activity over the Pt/10EG-TiO_(2)-10 catalyst.The 10 wt.%EG doped in TiO_(2) caused the TiO_(2) support to form a more hydrophobic surface,which reduced the adsorption of H_(2)O and SO_(2) on the catalyst,greatly inhibited deposition of the TiOSO_(4) and formation of the PtSO4 species as well as suppressed the oxidation of SO_(2),thus resulting in an improvement in the resistance to H_(2)O and SO_(2) of the Pt/10EG-TiO_(2)-10 catalyst.展开更多
The modified graphite anode materials have some prominent advantages over other anode materials in the industrial applications.A novel simple and gentle method is proposed to synthesize the mild expanded graphite micr...The modified graphite anode materials have some prominent advantages over other anode materials in the industrial applications.A novel simple and gentle method is proposed to synthesize the mild expanded graphite microspheres(MEGMs) from flake graphite spheres through a combined modified pressurized oxidation combined with the microwave treatment.The microstructural results demonstrate that moderately expanded MEGMs with an expansion volume between 4 and 10 ml·g^(-1)exhibit a highly microporous structure with an enlarged interlayer spacing,a decreased microcrystalline size,as well as an increased number of functional groups on the surface,resulting in the increased storage sites and spaces for lithium ions and the enhanced diffusion rate of lithium ions.When used as the anode material for lithium-ion batteries,the MEGM-T75t30 obtained by oxidation treatment at 75℃ for 30 min followed by microwave irradiation for expansion displays a high reversible capacity of 446.7 mAh·g^(-1) at 100 mA·g^(-1) after 100 cycles and excellent rate performance(330 and 116 mAh·g^(-1) at 800 and 3200 mA·g^(-1),respectively).Therefore,the MEGMs prepared by this convenient and mild method show excellent electrochemical properties and good application potential.展开更多
The intercalation compounds of CuCl2 were synthesized with expanded graphite, whose magnitude of the electrical conductivity is about 10(3)S(.)cm(-1). Their electrical conductivity is 3 similar to6 times as high as th...The intercalation compounds of CuCl2 were synthesized with expanded graphite, whose magnitude of the electrical conductivity is about 10(3)S(.)cm(-1). Their electrical conductivity is 3 similar to6 times as high as that of the expanded graphite, and about 10 times as high as that of GIC made of the non-expanded graphite. The microanalysis results of chemical compounds by X-ray energy spectrum scanning of TEM testified that the atomic ratio of chloride and cupric is nonstoichoimetric. The multivalence and exchange of electrovalence of the cupric ion was confirmed by the XPS-ESCA. Vacancy of chlorine anion increases the concentration of charge carrier. The special stage structure, made of graphite and chloride, produces a weak chemical bond belt and provides a carrier space in the direction of GIC layer. These factors develop the electrical properties.展开更多
Aluminum-ion battery(AIB)is very promising for its safety and large current charge–discharge.However,it is challenging to build a high-performance AIB system based on low-cost materials especially cathode&electro...Aluminum-ion battery(AIB)is very promising for its safety and large current charge–discharge.However,it is challenging to build a high-performance AIB system based on low-cost materials especially cathode&electrolyte.Despite the low-cost expanded graphite-triethylaminehydrochloride(EG-ET)system has been improved in cycle performance,its rate capability still remains a gap with the expensive graphene-alkylimidazoliumchloride AIB system.In this work,we treated the cheap EG appropriately through an industrial high-temperature process,employed the obtained EG3K(treated at 3000℃)cathode with AlCl_(3)-ET electrolyte,and built a novel,high-rate capability and double-cheap AIB system.The new EG3K-ET system achieved the cathode capacity of average 110 m Ah g^(-1)at 1 A g^(-1)with 18,000cycles,and retained the cathode capacity of 100 m Ah g^(-1)at 5 A g^(-1)with 27,500 cycles(fast charging of 72 s).Impressively,we demonstrated that a battery pack(EG3K-ET system,12 m Ah)had successfully driven the Model car running 100 m long.In addition,it was confirmed that the improvement of rate capability in the EG3K-ET system was mainly derived by deposition,and its capacity contribution ratio was about 53.7%.This work further promoted the application potential of the low-cost EG-ET AIB system.展开更多
High-efficiency microwave absorbers with broadband absorption are strongly desired for electromag-netic protection.Herein,we successfully synthesized a hybrid microwave absorbing material with two-dimensional layered ...High-efficiency microwave absorbers with broadband absorption are strongly desired for electromag-netic protection.Herein,we successfully synthesized a hybrid microwave absorbing material with two-dimensional layered structure,which consisted of expanded graphite(EG)and boron nitride(BN).The introduction of BN is to regulate the conductivity of EG and also to improve the thermal stability of the composite material.The ultrathin BN nano-sheets were uniformly wrapped on the EG sheets via chemi-cal vapor deposition.Attributed to the dielectric loss and conductive loss,the as-prepared hybrid material exhibited high performance for microwave absorption.The effective absorbing bandwidth(reflection loss value<-10 dB)was achieved up to 9.37 GHz with the thickness of 2.4 mm in the frequency range of 5.75-6.98 GHz and 9.86-18 GHz.And the minimum reflection loss was-51.58 dB at the thickness of 3 mm.The excellent performance of microwave absorption was attributed to the dielectric loss,interfacial polarization loss and optimized impedance matching.Moreover,compared to pure EG,the thermal de-composition temperature of EG/BN composite materials had increased by about 100℃which was up to 714℃.Taking the advantages of high thermal stability of BN as well as the fine microwave absorbability of EG,the EG/BN composites would be applied in high-temperature microwave absorbing fields.展开更多
Fume suppression mechanisms and the effect of expanded graphite on the performance of asphalt were studied by applying infrared spectroscopy（FT-IR）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and ...Fume suppression mechanisms and the effect of expanded graphite on the performance of asphalt were studied by applying infrared spectroscopy（FT-IR）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and comprehensive thermal analysis（TG, DSC）. The experimental results confirm that asphalt which is mixed with expandable graphite will expand in the process of hot mix, and the expanded graphite layer will swell by the light component in the asphalt. The light component in the asphalt and PAHs adsorption on expanded graphite surface or part of the plug in the expanded graphite layer between plates made nucleation crystallization growth. And the Van der Waals force and the bonding of the lattice can effectively restrain the asphalt fume release. Meanwhile, the expanding agent with oxidative can spread into the asphalt, leading to asphalt oxygenated and plastic abate, while the ductility decreases. Expanded graphite, SBS modifier and environment- friendly plasticizers are used to composite modified asphalt. According to asphalt fume release experiment, normal test of asphalt performance, Brookfield viscosity test, RTFOT test and asphalt mixture tests（high temperature stability, low temperature stability, water stability）, it has been proven that the modified asphalt’s performance is better than that of matrix asphalt and equivalent to that of SBS modified asphalt. Furthermore, it has good fume suppression effect.展开更多
As lithium(Li)-ion batteries expand their applications,operating over a wide temperature range becomes increasingly important.However,the lowtemperature performance of conventional graphite anodes is severely hampered...As lithium(Li)-ion batteries expand their applications,operating over a wide temperature range becomes increasingly important.However,the lowtemperature performance of conventional graphite anodes is severely hampered by the poor diffusion kinetics of Li ions(Li^(+)).Here,zinc oxide(ZnO) nanoparticles are incorporated into the expanded graphite to improve Li^(+)diffusion kinetics,resulting in a significant improvement in lowtemperature performance.The ZnO-embedded expanded graphite anodes are investigated with different amounts of ZnO to establish the structurecharge storage mechanism-performance relationship with a focus on lowtemperature applications.Electrochemical analysis reveals that the ZnOembedded expanded graphite anode with nano-sized ZnO maintains a large portion of the diffusion-controlled charge storage mechanism at an ultra-low temperature of-50℃ Due to this significantly enhanced Li^(+)diffusion rate,a full cell with the ZnO-embedded expanded graphite anode and a LiNi_(0.88)Co_(0.09)Al_(0.03)O_(2)cathode delivers high capacities of 176 mAh g^(-1)at20℃ and 86 mAh g^(-1)at-50℃ at a high rate of 1 C.The outstanding low-temperature performance of the composite anode by improving the Li^(+)diffusion kinetics provides important scientific insights into the fundamental design principles of anodes for low-temperature Li-ion battery operation.展开更多
In order to obtain anatase TiO2/expanded graphite with high expansion volume, titania gel was introduced to expandable graphite surface by sol-gel process, and then the composite was expanded and calcined at high temp...In order to obtain anatase TiO2/expanded graphite with high expansion volume, titania gel was introduced to expandable graphite surface by sol-gel process, and then the composite was expanded and calcined at high tempera- ture. The samples were analysed by using scanning electron microscope （SEM）, X-ray diffraction（XRD）, energy disperse spectroscopy （EDS）, and differential scanning calorimetry （DSC）. The optimal conditions for preparation are as follows： the molar ratio of tetrabutyl orthotitanate to triethanolamine is 1 ： 0.4, and the calcination and expansion temperature is in the range of 650--750 ~C. Under such conditions, the expansion volume of composites could reach 98 mE/g, and the mass loss ratio is less than 5%. The analysis shows that lower temperature and smaller particle size of graphite are helpful to the formation of anatase-type of TiO2, but larger particle size will lead to lower mass loss ratio, and higher temperature and larger particle size will lead to higher expansion volume.展开更多
Currently,Na-ion battery(NIB) has become one of the most potential alternatives for Li-ion batteries due to the safety and low cost.As a promising anode for Na-ion storage,expanded graphite has attracted considerable ...Currently,Na-ion battery(NIB) has become one of the most potential alternatives for Li-ion batteries due to the safety and low cost.As a promising anode for Na-ion storage,expanded graphite has attracted considerable attention.However,the sodiation-desodiation process is still unclear.In our work,we obtain expanded graphite through slight modified Hummer's method and subsequent thermal treatment,which exhibits excellent cycling stability.Even at a high current density of 1 A g^(-1),our expanded graphite still remains a high reversible capacity of 100 mA h g^(-1) after 2600 cycles.Furthermore,we also investigate the electrochemical mechanism of our expanded graphite for Na-ion storage by operando Raman technique,which illuminate the electrochemical reaction during different sodiation-desodiation processes.展开更多
A new material is prepared by impregnating the expanded graphite(EG) into ethanol solutions of metal acetate and then drying and reducing it in H2.It contains the EG and the nanoparticles of the magnetic Ni–Fe alloy ...A new material is prepared by impregnating the expanded graphite(EG) into ethanol solutions of metal acetate and then drying and reducing it in H2.It contains the EG and the nanoparticles of the magnetic Ni–Fe alloy for the electromagnetic shielding.Its morphology,phase structure,magnetic properties,and electromagnetic shielding effectiveness(SE) are investigated in our experiment.It shows that the morphology,the phase structure,and the magnetic property of the composite can be modified by altering the Ni content in the alloy nanoparticles.Interestingly,the SE can be enhanced to 54–70 d B at low frequencies(300 kHz–10 MHz) by dispersing the magnetic nanoparticles onto EG.展开更多
Expanded graphite （r-;G） shows higher adsorption capacity for oils than for dyes. To illustrate the different adsorption mechanism of EG for these pollutants, adsorption capacities of dyes and oil on EG were firs...Expanded graphite （r-;G） shows higher adsorption capacity for oils than for dyes. To illustrate the different adsorption mechanism of EG for these pollutants, adsorption capacities of dyes and oil on EG were firstly studied. And then stepwise adsorption for oils was carried out with EG which has been saturated firstly by dyes, the difference between adsorbance of oil on EG was checked with deviation analysis. Scanning electronic microscopy （SEM） analysis was used to show structure difference of EG adsorbed different adsorbates. These used adsorbates were SD300 oil, basic fuchsine, Auramine lake yellow O and acid brilliant red 3B. The adsorption isotherm of dyes on EG is type 11 or type 1, and their equilibrium adsorbances are less than 1.0 g/g. While, adsorbance for SD300 oil can reach 104.5 g/g. Deviation analysis for stepwise adsorbances of oil shows no statistical significance. EG saturated firstly by dyes, still has an average adsorption capacity of 35 g/g for SD300 oil, and it does not change with the initial dyes concentration. SEM photos illustrate the adsorption of oil on EG is mainly filling, In the adsorption of dyes, there is severe breakage of the V-type pore and shrinkage of the particle. Kinetic difference is analyzed also.展开更多
By using hydrothermal synthesis method, successively adding tetrabutyl titanate and expandable flake graphite in 40 mL 0.95% NH4Cl solution prepared the nano TiO2/expandable flake graphite, which was then settled in m...By using hydrothermal synthesis method, successively adding tetrabutyl titanate and expandable flake graphite in 40 mL 0.95% NH4Cl solution prepared the nano TiO2/expandable flake graphite, which was then settled in muffle furnace in the expansion of 10 s under 800 ℃ and got nanosized TiO2/expanded graphite. Synthesized that with CoFe2O4 by chemical coprecipitation method finally prepared magnetic nanosized photocatalyst TiO2/expanded graphite. Magnetic nanosized TiO2/expanded graphite was studied on the photodegradation performance of methyl orange solution and the magnetic recovery after the degradation of methyl orange solution. The experiment result showed that in 50 mL 25 mg/L methyl orange solution joined 120 mg loading 50% TiO2 of the expanded graphite, exposed to ultraviolet irradiation for 1 h, the methyl orange decolorization ratio was 90%. When the load of CoFe2O4 in nanosized TiO2/expanded graphite reached 40%, its magnetic recovery efficiency reached 94.3%.展开更多
The expanded graphite (EG) with a low density and better extinction performance can be used in military as passive jamming material in IR and MMW bands. Its complex refractive index is a significant parameter for the ...The expanded graphite (EG) with a low density and better extinction performance can be used in military as passive jamming material in IR and MMW bands. Its complex refractive index is a significant parameter for the extinction property. This paper presents a method to calculate the complex refractive index of EG. The reflection spectra of EG pellets were measured in the 0.24-2.6μm and 2.5-25μm bands, respectively. Based on the measurement results, the complex refractive index of EG in 5-10μm band was calculated by using Kramers-Kronig(K-K) relation and Bruggeman effective medium theory, and then the errors were analyzed. The results indicate that it is feasible to calculate the complex refractive index of EG based on its IR reflection spectra data.展开更多
Relying on the great success in portable and smart devices,lithium ion batteries(LIBs)have been considered as one of the leading technologies in electric vehicles(EVs)and stationary energy storage systems(ESSs).With t...Relying on the great success in portable and smart devices,lithium ion batteries(LIBs)have been considered as one of the leading technologies in electric vehicles(EVs)and stationary energy storage systems(ESSs).With the rapid development of EVs and ESSs,the technology upgrading of LIBs is highly demanded.As expected,it requires LIBs with improved power and energy densities[1].展开更多
A 1-octadecanol(OD)/1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol(DMDBS)/expander graphite(EG) composite was prepared as a form-stable phase change material(PCM) by vacuum melting method. The results of field emissio...A 1-octadecanol(OD)/1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol(DMDBS)/expander graphite(EG) composite was prepared as a form-stable phase change material(PCM) by vacuum melting method. The results of field emission-scanning electron microscopy(FE-SEM) showed that 1-octadecanol was restricted in the three-dimensional network formed by DMDBS and the honeycomb network formed by EG. X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FT-IR) results showed that no chemical reaction occurred among the components of composite PCM in the preparation process. The gel-to-sol transition temperature of the composite PCMs containing DMDBS was much higher than the melting point of pure 1-octadecanol. The improvements in preventing leakage and thermal stability limits were mainly attributed to the synergistic effect of the three-dimensional network formed by DMDBS and the honeycomb network formed by EG. Differential scanning calorimeter(DSC) was used to determine the latent heat and phase change temperature of the composite PCMs. During melting and freezing process the latent heat values of the PCM with the composition of 91% OD/3% DMDBS/6% EG were 214.9 and 185.9 kJ·kg-1, respectively. Its degree of supercooling was only 0.1 ℃. Thermal constant analyzer results showed that its thermal conductivity(κ) changed up to roughly 10 times over that of OD/DMDBS matrix.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFB2502000)the National Natural Science Foundation of China(Nos.U21A20332,51771076,U21A200970,52301266)the Science and Technology Planning Project of Guangzhou(No.2024A04J3332)。
文摘Mixed polyanion phosphate Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)is regarded as the most promising cathode material for sodium-ion batteries(SIBs),due to its high structural stability and low-cost environmental friendliness.However,its intrinsic low conductivity and sluggish Na^(+)diffusion restricted the fast-charge and low-temperature sodium storage.Herein,an NFPP composite encapsulated by in-situ pyrolytic carbon and coupled with expanded graphite(NFPP@C/EG)was constructed via a sol-gel method followed by a ballmill procedure.Due to the dual-carbon modified strategy,this NFPP@C/EG only enhanced the electronic conductivity,but also endowed more channels for Na^(+)diffusion.As cathode for SIBs,the optimized NFPP(M-NFPP@C/EG)delivers excellent rate capability(capacity of~80.5 mAh/g at 50 C)and outstanding cycling stability(11000 cycles at 50 C with capacity retention of 89.85%).Additionally,cyclic voltammetry(CV)confirmed that its sodium storage behavior is pseudocapacitance-controlled,with in-situ electrochemical impedance spectroscopy(EIS)further elucidating improvements in electrode reaction kinetics.At lower temperatures(0℃),M-NFPP@C/EG demonstrated exceptional cycling performance(8800 cycles at 10 C with capacity retention of 95.81%).Moreover,pouch cells also exhibited excellent stability.This research demonstrates the feasibility of a dual carbon modification strategy in enhancing NFPP and proposes a low-cost,high-rate,and ultra-stable cathode material for SIBs.
基金supported by the National Key Research and Development Program of China(No.2017YFD0801503)the Fundamental Research Funds for the Central Universities(No.PYVZ1703)the Higher Education and High-quality and World-class Universities(PY201606)
文摘Zero-valent iron（ZⅥ） was loaded on expanded graphite（EG） to produce a composite material（EG-ZⅥ） for efficient removal of hexavalent chromium（Cr（Ⅵ））. EG and EG-ZⅥ were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）,Fourier-transform infrared（FTIR） spectroscopy and Brunauer–Emmett–Teller（BET） analysis. EG-ZⅥ had a high specific surface area and contained sub-micron sized particles of zero-valent iron. Batch experiments were employed to evaluate the Cr（Ⅵ） removal performance. The results showed that the Cr（Ⅵ） removal rate was 98.80% for EG-ZⅥ,which was higher than that for both EG（10.00%） and ZⅥ（29.80%）. Furthermore, the removal rate of Cr（Ⅵ） by EG-ZⅥ showed little dependence on solution p H within a p H range of 1–9.Even at pH 11, a Cr（Ⅵ） removal rate of 62.44% was obtained after reaction for 1 hr. EG-ZⅥ could enhance the removal of Cr（Ⅵ） via chemical reduction and physical adsorption,respectively. X-ray photoelectron spectroscopy（XPS） was used to analyze the mechanisms of Cr（Ⅵ） removal, which indicated that the ZⅥ loaded on the surface was oxidized, and the removed Cr（Ⅵ） was immobilized via the formation of Cr（III） hydroxide and Cr（III）–Fe（III）hydroxide/oxyhydroxide on the surface of EG-ZⅥ.
基金support from the National Basic Research Program of China (2014CB239702)National Natural Science Foundation of China (Grant Nos. 21371121, 21506126 and 51502174)+1 种基金Shenzhen Science and Technology Research Foundation (Grant Nos. JCYJ20150324141711645,JCYJ20150324141711616 and JCYJ20150626090504916)China Postdoctoral Science Foundation (2015 M582401 and 2015 M572349)
文摘A Ni Fe_2O_4/expanded graphite(Ni Fe_2O_4/EG)nanocomposite was prepared via a simple and inexpensive synthesis method. Its lithium storage properties were studied with the goal of applying it as an anode in a lithium-ion battery. The obtained nanocomposite exhibited a good cycle performance, with a capacity of 601 m Ah g^(-1)at a current of 1 A g^(-1)after 800 cycles. This good performance may beattributed to the enhanced electrical conductivity and layered structure of the EG. Its high mechanical strength could postpone the disintegration of the nanocomposite structure,efficiently accommodate volume changes in the Ni Fe_2O_4-based anodes, and alleviate aggregation of Ni Fe_2O_4 nanoparticles.
基金Funded by the Science Foundation of Jiangsu Province (No. BK2009534)Foundation of Oil Gas Storage and Transport of Jiangsu Province (No.CY0901)
文摘A new method for preparing expanded graphite-based composites （EGCs） was developed.The obtained samples were characterized by scanning electron microscopy （SEM）,transmission electron microscope （TEM） and nitrogen adsorption.The experimental results indicated that the EGCs was not simply mechanical mixture of EG and activated carbon,instead the activated carbon was coated on the surface of interior and external pores of the EG in the form of thin carbon layer.The thickness of the activated carbon layer was nearly one hundred nanometers by calculation.It was shown that the higher the impregnation ratio and the activation temperature were,the easier the porosity development would be.And the BET surface area and the total pore volume were as high as 1978 m2/g and 0.9917 cm3/g respectively at 350℃ with an impregnation ratio of 0.9.
基金financially supported by the National Natural Science Foundation of China (Nos. 51573102 and 51721091)
文摘Expanded graphite(EG) films exhibit potential use in a wide field including thermal management, conductive applications,and electromagnetic interference(EMI) shielding. However, their poor tensile strength and brittleness are crucial deficiencies for commercial applications. To address these defects, in our work, natural rubber(NR) is employed to improve EG films for better mechanical strength and flexibility. The origin of the strengthening effect of EG films by the addition of natural rubber mainly arises from the formation of a simulate shell structure. Compared to the neat EG films, the addition of merely 2 wt% NR can give rise to superior ductility. Further, the loading of 10 wt% NR realizes a significant mechanical enhancement of the EG/NR films, i.e., 2.4 and 11.4 times increase in tensile strength and elongation at break, respectively. Besides, EG/NR films containing 10 wt% NR can still sustain excellent thermal and electric conductivities of 173 W·m^-1·K^-1 and 75 S·cm^-1, respectively. Furthermore, a very high EMI of 41.4 dB is achieved as the film thickness reaches 50 μm. Thus, the lightweight EG/NR films with comprehensive performance as well as their virtue of green and simple large-scale preparation endow them with the possibility of designing next-generation flexible electronics.
基金supported by the National Key R&D Program of China (No.2017YFC0210303).
文摘The expandable graphite(EG)modified TiO_(2) nanocomposites were prepared by the high shearmethod using the TiO_(2) nanoparticles(NPs)and EG as precursors,in which the amount of EG doped in TiO_(2) was 10 wt.%.Followed by the impregnation method,adjusting the pH of the solution to 10,and using the electrostatic adsorption to achieve spatial confinement,the Pt elementswere mainly distributed on the exposed TiO_(2),thus generating the Pt/10EG-TiO_(2)-10 catalyst.The best CO oxidation activity with the excellent resistance to H_(2)O and SO_(2) was obtained over the Pt/10EG-TiO_(2)-10 catalyst:CO conversion after 36 hr of the reaction was ca.85%under the harsh condition of 10 vol.%H_(2)O and 100 ppm SO_(2) at a high gaseous hourly space velocity(GHSV)of 400,000 hr−1.Physicochemical properties of the catalystswere characterized by various techniques.The results showed that the electrostatic adsorption,which riveted the Pt elements mainly on the exposed TiO_(2) of the support surface,reduced the dispersion of Pt NPs on EG and achieved the effective dispersion of Pt NPs,hence significantly improving CO oxidation activity over the Pt/10EG-TiO_(2)-10 catalyst.The 10 wt.%EG doped in TiO_(2) caused the TiO_(2) support to form a more hydrophobic surface,which reduced the adsorption of H_(2)O and SO_(2) on the catalyst,greatly inhibited deposition of the TiOSO_(4) and formation of the PtSO4 species as well as suppressed the oxidation of SO_(2),thus resulting in an improvement in the resistance to H_(2)O and SO_(2) of the Pt/10EG-TiO_(2)-10 catalyst.
基金financially supported by the National Natural Science Foundation of China(Nos.51702191,51802325 and U1510134)the Natural Science Foundation of Shanxi Province,China(No.201901D111037)+3 种基金Scientific Research Foundation for Young Scientists of Shanxi Province,China(No.201901D211585)the Science and Technology Innovation Planning Project in Universities and Colleges of Shanxi Province of China(No.2019L0012)the Unveiling Bidding Projects of Shanxi Province,China(No.20191101008)the Shanxi“1331 Project”Key Innovative Research Team。
文摘The modified graphite anode materials have some prominent advantages over other anode materials in the industrial applications.A novel simple and gentle method is proposed to synthesize the mild expanded graphite microspheres(MEGMs) from flake graphite spheres through a combined modified pressurized oxidation combined with the microwave treatment.The microstructural results demonstrate that moderately expanded MEGMs with an expansion volume between 4 and 10 ml·g^(-1)exhibit a highly microporous structure with an enlarged interlayer spacing,a decreased microcrystalline size,as well as an increased number of functional groups on the surface,resulting in the increased storage sites and spaces for lithium ions and the enhanced diffusion rate of lithium ions.When used as the anode material for lithium-ion batteries,the MEGM-T75t30 obtained by oxidation treatment at 75℃ for 30 min followed by microwave irradiation for expansion displays a high reversible capacity of 446.7 mAh·g^(-1) at 100 mA·g^(-1) after 100 cycles and excellent rate performance(330 and 116 mAh·g^(-1) at 800 and 3200 mA·g^(-1),respectively).Therefore,the MEGMs prepared by this convenient and mild method show excellent electrochemical properties and good application potential.
基金This paper was the part of doctor thesis of China Uni-versity of Geoscience, (Beijing). The project was sup-' ported by Natio
文摘The intercalation compounds of CuCl2 were synthesized with expanded graphite, whose magnitude of the electrical conductivity is about 10(3)S(.)cm(-1). Their electrical conductivity is 3 similar to6 times as high as that of the expanded graphite, and about 10 times as high as that of GIC made of the non-expanded graphite. The microanalysis results of chemical compounds by X-ray energy spectrum scanning of TEM testified that the atomic ratio of chloride and cupric is nonstoichoimetric. The multivalence and exchange of electrovalence of the cupric ion was confirmed by the XPS-ESCA. Vacancy of chlorine anion increases the concentration of charge carrier. The special stage structure, made of graphite and chloride, produces a weak chemical bond belt and provides a carrier space in the direction of GIC layer. These factors develop the electrical properties.
基金the support of the National Natural Science Foundation of China(51533008,51703194 and 21805242)the National Key R&D Program of China(2016YFA0200200)the Excellent Postdoctoral Special Fund of Zhejiang University for funding this research work。
文摘Aluminum-ion battery(AIB)is very promising for its safety and large current charge–discharge.However,it is challenging to build a high-performance AIB system based on low-cost materials especially cathode&electrolyte.Despite the low-cost expanded graphite-triethylaminehydrochloride(EG-ET)system has been improved in cycle performance,its rate capability still remains a gap with the expensive graphene-alkylimidazoliumchloride AIB system.In this work,we treated the cheap EG appropriately through an industrial high-temperature process,employed the obtained EG3K(treated at 3000℃)cathode with AlCl_(3)-ET electrolyte,and built a novel,high-rate capability and double-cheap AIB system.The new EG3K-ET system achieved the cathode capacity of average 110 m Ah g^(-1)at 1 A g^(-1)with 18,000cycles,and retained the cathode capacity of 100 m Ah g^(-1)at 5 A g^(-1)with 27,500 cycles(fast charging of 72 s).Impressively,we demonstrated that a battery pack(EG3K-ET system,12 m Ah)had successfully driven the Model car running 100 m long.In addition,it was confirmed that the improvement of rate capability in the EG3K-ET system was mainly derived by deposition,and its capacity contribution ratio was about 53.7%.This work further promoted the application potential of the low-cost EG-ET AIB system.
文摘High-efficiency microwave absorbers with broadband absorption are strongly desired for electromag-netic protection.Herein,we successfully synthesized a hybrid microwave absorbing material with two-dimensional layered structure,which consisted of expanded graphite(EG)and boron nitride(BN).The introduction of BN is to regulate the conductivity of EG and also to improve the thermal stability of the composite material.The ultrathin BN nano-sheets were uniformly wrapped on the EG sheets via chemi-cal vapor deposition.Attributed to the dielectric loss and conductive loss,the as-prepared hybrid material exhibited high performance for microwave absorption.The effective absorbing bandwidth(reflection loss value<-10 dB)was achieved up to 9.37 GHz with the thickness of 2.4 mm in the frequency range of 5.75-6.98 GHz and 9.86-18 GHz.And the minimum reflection loss was-51.58 dB at the thickness of 3 mm.The excellent performance of microwave absorption was attributed to the dielectric loss,interfacial polarization loss and optimized impedance matching.Moreover,compared to pure EG,the thermal de-composition temperature of EG/BN composite materials had increased by about 100℃which was up to 714℃.Taking the advantages of high thermal stability of BN as well as the fine microwave absorbability of EG,the EG/BN composites would be applied in high-temperature microwave absorbing fields.
基金Funded by the National Natural Science Foundation of China(No.51078372)the Doctoral Program of Higher Specialized Research Foundation(No.20105522110002)
文摘Fume suppression mechanisms and the effect of expanded graphite on the performance of asphalt were studied by applying infrared spectroscopy（FT-IR）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and comprehensive thermal analysis（TG, DSC）. The experimental results confirm that asphalt which is mixed with expandable graphite will expand in the process of hot mix, and the expanded graphite layer will swell by the light component in the asphalt. The light component in the asphalt and PAHs adsorption on expanded graphite surface or part of the plug in the expanded graphite layer between plates made nucleation crystallization growth. And the Van der Waals force and the bonding of the lattice can effectively restrain the asphalt fume release. Meanwhile, the expanding agent with oxidative can spread into the asphalt, leading to asphalt oxygenated and plastic abate, while the ductility decreases. Expanded graphite, SBS modifier and environment- friendly plasticizers are used to composite modified asphalt. According to asphalt fume release experiment, normal test of asphalt performance, Brookfield viscosity test, RTFOT test and asphalt mixture tests（high temperature stability, low temperature stability, water stability）, it has been proven that the modified asphalt’s performance is better than that of matrix asphalt and equivalent to that of SBS modified asphalt. Furthermore, it has good fume suppression effect.
基金supported by an Early Career Faculty Grant from NASA’s Space Technology Research Grants Program (80NSSC18K1509)supported by the Institute for Electronics and Nanotechnology Seed Grant and performed in part at the Georgia Tech Institute for Electronics and Nanotechnology, a member of the National Nanotechnology Coordinated Infrastructure (NNCI), which was supported by the National Science Foundation (ECCS-2025462)
文摘As lithium(Li)-ion batteries expand their applications,operating over a wide temperature range becomes increasingly important.However,the lowtemperature performance of conventional graphite anodes is severely hampered by the poor diffusion kinetics of Li ions(Li^(+)).Here,zinc oxide(ZnO) nanoparticles are incorporated into the expanded graphite to improve Li^(+)diffusion kinetics,resulting in a significant improvement in lowtemperature performance.The ZnO-embedded expanded graphite anodes are investigated with different amounts of ZnO to establish the structurecharge storage mechanism-performance relationship with a focus on lowtemperature applications.Electrochemical analysis reveals that the ZnOembedded expanded graphite anode with nano-sized ZnO maintains a large portion of the diffusion-controlled charge storage mechanism at an ultra-low temperature of-50℃ Due to this significantly enhanced Li^(+)diffusion rate,a full cell with the ZnO-embedded expanded graphite anode and a LiNi_(0.88)Co_(0.09)Al_(0.03)O_(2)cathode delivers high capacities of 176 mAh g^(-1)at20℃ and 86 mAh g^(-1)at-50℃ at a high rate of 1 C.The outstanding low-temperature performance of the composite anode by improving the Li^(+)diffusion kinetics provides important scientific insights into the fundamental design principles of anodes for low-temperature Li-ion battery operation.
基金Supported by Applied Basic Research Project of Sichuan Province (No.2006J13-014)Innovation Fund of Panzhihua University
文摘In order to obtain anatase TiO2/expanded graphite with high expansion volume, titania gel was introduced to expandable graphite surface by sol-gel process, and then the composite was expanded and calcined at high tempera- ture. The samples were analysed by using scanning electron microscope （SEM）, X-ray diffraction（XRD）, energy disperse spectroscopy （EDS）, and differential scanning calorimetry （DSC）. The optimal conditions for preparation are as follows： the molar ratio of tetrabutyl orthotitanate to triethanolamine is 1 ： 0.4, and the calcination and expansion temperature is in the range of 650--750 ~C. Under such conditions, the expansion volume of composites could reach 98 mE/g, and the mass loss ratio is less than 5%. The analysis shows that lower temperature and smaller particle size of graphite are helpful to the formation of anatase-type of TiO2, but larger particle size will lead to lower mass loss ratio, and higher temperature and larger particle size will lead to higher expansion volume.
基金financial supports from the National Natural Science Foundation of China (51702056, 51772135)the Ministry of Education of China (6141A02022516)+2 种基金the Fundamental Research Funds for the Central Universities (21617330)the China Postdoctoral Science Foundation (2017M622902, 2019T120790)GDHVPS (2017)。
文摘Currently,Na-ion battery(NIB) has become one of the most potential alternatives for Li-ion batteries due to the safety and low cost.As a promising anode for Na-ion storage,expanded graphite has attracted considerable attention.However,the sodiation-desodiation process is still unclear.In our work,we obtain expanded graphite through slight modified Hummer's method and subsequent thermal treatment,which exhibits excellent cycling stability.Even at a high current density of 1 A g^(-1),our expanded graphite still remains a high reversible capacity of 100 mA h g^(-1) after 2600 cycles.Furthermore,we also investigate the electrochemical mechanism of our expanded graphite for Na-ion storage by operando Raman technique,which illuminate the electrochemical reaction during different sodiation-desodiation processes.
基金supported by the National Natural Science Foundation of China(Nos.50977042 and 10904061)the“863”program of MSTC(No.2006AA03Z458)the research funds for Nanjing Institute of Technology(No.YKJ201002)
文摘A new material is prepared by impregnating the expanded graphite(EG) into ethanol solutions of metal acetate and then drying and reducing it in H2.It contains the EG and the nanoparticles of the magnetic Ni–Fe alloy for the electromagnetic shielding.Its morphology,phase structure,magnetic properties,and electromagnetic shielding effectiveness(SE) are investigated in our experiment.It shows that the morphology,the phase structure,and the magnetic property of the composite can be modified by altering the Ni content in the alloy nanoparticles.Interestingly,the SE can be enhanced to 54–70 d B at low frequencies(300 kHz–10 MHz) by dispersing the magnetic nanoparticles onto EG.
文摘Expanded graphite （r-;G） shows higher adsorption capacity for oils than for dyes. To illustrate the different adsorption mechanism of EG for these pollutants, adsorption capacities of dyes and oil on EG were firstly studied. And then stepwise adsorption for oils was carried out with EG which has been saturated firstly by dyes, the difference between adsorbance of oil on EG was checked with deviation analysis. Scanning electronic microscopy （SEM） analysis was used to show structure difference of EG adsorbed different adsorbates. These used adsorbates were SD300 oil, basic fuchsine, Auramine lake yellow O and acid brilliant red 3B. The adsorption isotherm of dyes on EG is type 11 or type 1, and their equilibrium adsorbances are less than 1.0 g/g. While, adsorbance for SD300 oil can reach 104.5 g/g. Deviation analysis for stepwise adsorbances of oil shows no statistical significance. EG saturated firstly by dyes, still has an average adsorption capacity of 35 g/g for SD300 oil, and it does not change with the initial dyes concentration. SEM photos illustrate the adsorption of oil on EG is mainly filling, In the adsorption of dyes, there is severe breakage of the V-type pore and shrinkage of the particle. Kinetic difference is analyzed also.
文摘By using hydrothermal synthesis method, successively adding tetrabutyl titanate and expandable flake graphite in 40 mL 0.95% NH4Cl solution prepared the nano TiO2/expandable flake graphite, which was then settled in muffle furnace in the expansion of 10 s under 800 ℃ and got nanosized TiO2/expanded graphite. Synthesized that with CoFe2O4 by chemical coprecipitation method finally prepared magnetic nanosized photocatalyst TiO2/expanded graphite. Magnetic nanosized TiO2/expanded graphite was studied on the photodegradation performance of methyl orange solution and the magnetic recovery after the degradation of methyl orange solution. The experiment result showed that in 50 mL 25 mg/L methyl orange solution joined 120 mg loading 50% TiO2 of the expanded graphite, exposed to ultraviolet irradiation for 1 h, the methyl orange decolorization ratio was 90%. When the load of CoFe2O4 in nanosized TiO2/expanded graphite reached 40%, its magnetic recovery efficiency reached 94.3%.
文摘The expanded graphite (EG) with a low density and better extinction performance can be used in military as passive jamming material in IR and MMW bands. Its complex refractive index is a significant parameter for the extinction property. This paper presents a method to calculate the complex refractive index of EG. The reflection spectra of EG pellets were measured in the 0.24-2.6μm and 2.5-25μm bands, respectively. Based on the measurement results, the complex refractive index of EG in 5-10μm band was calculated by using Kramers-Kronig(K-K) relation and Bruggeman effective medium theory, and then the errors were analyzed. The results indicate that it is feasible to calculate the complex refractive index of EG based on its IR reflection spectra data.
基金financial support from the Pearl River Talent Recruitment Program(2019QN01L096)China the Guangdong Innovative and Entrepreneurial Research Team Program(2019ZT08L075)+1 种基金China the Guangdong Science and Technology Program(2020B121201003)China and the“Young Talent Fellowship”Program through South China University of Technology。
文摘Relying on the great success in portable and smart devices,lithium ion batteries(LIBs)have been considered as one of the leading technologies in electric vehicles(EVs)and stationary energy storage systems(ESSs).With the rapid development of EVs and ESSs,the technology upgrading of LIBs is highly demanded.As expected,it requires LIBs with improved power and energy densities[1].
基金Funded by Science and Technology Support Program of Hubei Province of China(No.2015BAA111)
文摘A 1-octadecanol(OD)/1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol(DMDBS)/expander graphite(EG) composite was prepared as a form-stable phase change material(PCM) by vacuum melting method. The results of field emission-scanning electron microscopy(FE-SEM) showed that 1-octadecanol was restricted in the three-dimensional network formed by DMDBS and the honeycomb network formed by EG. X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FT-IR) results showed that no chemical reaction occurred among the components of composite PCM in the preparation process. The gel-to-sol transition temperature of the composite PCMs containing DMDBS was much higher than the melting point of pure 1-octadecanol. The improvements in preventing leakage and thermal stability limits were mainly attributed to the synergistic effect of the three-dimensional network formed by DMDBS and the honeycomb network formed by EG. Differential scanning calorimeter(DSC) was used to determine the latent heat and phase change temperature of the composite PCMs. During melting and freezing process the latent heat values of the PCM with the composition of 91% OD/3% DMDBS/6% EG were 214.9 and 185.9 kJ·kg-1, respectively. Its degree of supercooling was only 0.1 ℃. Thermal constant analyzer results showed that its thermal conductivity(κ) changed up to roughly 10 times over that of OD/DMDBS matrix.
