LiBH_(4)with high hydrogen storage density,is regarded as one of the most promising hydrogen storage materials.Nevertheless,it suffers from high dehydrogenation temperature and poor reversibility for practical use.Nan...LiBH_(4)with high hydrogen storage density,is regarded as one of the most promising hydrogen storage materials.Nevertheless,it suffers from high dehydrogenation temperature and poor reversibility for practical use.Nanoconfinement is effective in achieving low dehydrogenation temperature and favorable reversibility.Besides,graphene can serve as supporting materials for LiBH_(4)catalysts and also destabilize LiBH_(4)via interfacial reaction.However,graphene has never been used alone as a frame material for nanoconfining LiBH_(4).In this study,graphene microflowers with large pore volumes were prepared and used as nanoconfinement framework material for LiBH_(4),and the nanoconfinement effect of graphene was revealed.After loading 70 wt%of LiBH_(4) and mechanically compressed at 350 MPa,8.0 wt% of H2 can be released within 100 min at 320C,corresponding to the highest volumetric hydrogen storage density of 94.9 g H2 L^(-1)ever reported.Thanks to the nanoconfinement of graphene,the rate-limiting step of dehydrogenation of nanoconfined LiBH_(4) was changed and its apparent activation energy of the dehydrogenation(107.3 kJ mol^(-1))was 42%lower than that of pure LiBH_(4).Moreover,the formation of the intermediate Li_(2)B_(12)H_(12) was effectively inhibited,and the stable nanoconfined structure enhanced the reversibility of LiBH_(4).This work widens the understanding of graphene's nanoconfinement effect and provides new insights for developing high-density hydrogen storage materials.展开更多
The use of redox-active organic electrode materials in energy storage is restricted due to their inferior solvent resistance,abysmal conductivity,and the resultant low practical capacity.To address these issues,a clas...The use of redox-active organic electrode materials in energy storage is restricted due to their inferior solvent resistance,abysmal conductivity,and the resultant low practical capacity.To address these issues,a class of bipolar p-phenylenediimidazole-based small-molecule compounds are designed and fabricated.Theπ-conjugated backbone of these small molecules allows for electron delocalization on a big conjugation plane,endowing them with good conductivity and reaction reversibility.Furthermore,when the para-positions of phenylene are occupied by hydroxyl groups,as-formed intramolecular hydrogen bonds(N-H...O)between phenolic hydroxyl groups and the–NH groups of imidazole rings further enhance the structural planarity,resulting in higherπ-conjugation degree and better conductivity,and thus higher utilization of active sites and electrode capacity,proved by both experimental results and theoretical calculations.The optimized composite electrode DBNQ@rGO-45 shows a high specific capacity(∼308 mA h g^(−1)at 100 mA g^(−1))and a long cycling stability(112.9 mA h g^(−1)after 6000 cycles at 2000 mA g^(−1)).The significantly better electrochemical properties for hydroxyl group-containing compounds than those without hydroxyl groups attributed to intramolecular hydrogen bond-induced conjugation enhancement will inspire the structure design of organic electrodes for better energy storage.展开更多
The commercialization of electrolytic MnO_(2)-Zn batteries is highly applauded owing to the advantages of cost-effectiveness,high safety,high energy density,and durable working performance.However,due to the low rever...The commercialization of electrolytic MnO_(2)-Zn batteries is highly applauded owing to the advantages of cost-effectiveness,high safety,high energy density,and durable working performance.However,due to the low reversibility of the cathode MnO_(2)/Mn^(2+)chemistry at high areal capacities and the severe Zn anode corrosion,the practical application of MnO_(2)-Zn batteries is hampered by inadequate lifespan.Leveraging the full advantage of an iodine redox mediator,here we design a highly rechargeable electrolytic MnO_(2)-Zn battery with a high areal capacity.The MnO_(2)-Zn battery coupled with an iodine mediator in a mild electrolyte shows a high discharge voltage of 1.85 V and a robust areal capacity of 10 mAh cm^(-2)under a substantial discharge current density of 160 mA cm^(-2).The MnO_(2)/I_(2)-Zn battery with an areal capacity of 10 mAh cm^(-2)exhibits prolonged stability of over 950 cycles under a high-capacity retention of~94%.The scaled-up MnO_(2)/I_(2)-Zn battery reveals a stable cycle life under a cell capacity of~600 mAh.Moreover,our constructed MnO_(2)/I_(2)-Zn battery demonstrates a practical energy density of~37 Wh kg^(-1)and a competitive energy cost of<18 US$kWh^(-1)by taking into account the cathode,anode,and electrolyte.The MnO_(2)/I_(2)-Zn battery,with its remarkable reversibility and reasonable energy density,enlightens a new arena of large-scale energy storage devices.展开更多
Zinc-based flow batteries(ZFBs)have aroused great favor in large-scale energy storage due to the high security and low cost.However,the low areal capacity arising from the limited space for Zn plating hinders the furt...Zinc-based flow batteries(ZFBs)have aroused great favor in large-scale energy storage due to the high security and low cost.However,the low areal capacity arising from the limited space for Zn plating hinders the further development.Herein,a novel carbon felt-Sn-carbon felt sandwich host(CSCH)is designed and constructed.Benefiting from the strong chemical absorption and the dehydration effect on Zn(H_(2)O)_(6)^(2+),the Sn activation layer in the CSCH demonstrates the lowest comprehensive resistance for Zn deposition.Thus,Zn is induced to nucleate preferentially on the Sn activation layer,and grows towards the membrane,regulating the spatial distribution of Zn electrochemical deposits,which remarkably improves the areal capacity and cyclic stability of Zn anode.Consequently,the zinc-bromine flow batteries equipped with CSCH electrodes can achieve the ultra-high areal capacity of 120 mA h cm^(-2)at 80 mA cm^(-2),and run stably for 140 h with average energy efficiency of 80.3%in the extreme condition(80 mA cm^(-2),80 mA h cm^(-2)).This innovative work will inspire future advanced designs for high areal capacity electrodes in ZFBs.展开更多
Corrosion is a primary cause of the slippage of friction⁃type high⁃strength bolted(FHSB)T⁃stub connections.This paper attempts to quantify the residual capacity of FHSB T⁃stub connections with corroded nuts.Firstly,co...Corrosion is a primary cause of the slippage of friction⁃type high⁃strength bolted(FHSB)T⁃stub connections.This paper attempts to quantify the residual capacity of FHSB T⁃stub connections with corroded nuts.Firstly,corrosion simulation tests were conducted on 48 manually cut nuts to find out the relationship between the damage degree of nut section and the residual clamping force(RCF)of bolt.Then,static load tests were carried out on 24 FHSB T⁃stub connections with nuts of different degrees of damage to obtain the failure modes.By finite⁃element(FE)models,a comparative analysis was performed on the initial friction load(IFL)and ultimate strength(US)of each connection with corroded nuts.Finally,the parameters of 96 FE models for FHSB T⁃stub connections were analyzed and used to derive the calculation formulas for the degree of damage for each nut and the IFL and US of each connection.The results show that the RCF decay of a bolt is a quadratic function of the equivalent radius loss ratio and the shear failure after nut corrosion;the IFL of each connection had a clear linear correlation with the RCF of the corresponding bolts,and the correlation depends on the applied load and static friction on connecting plate interface induced by the clamping force;the static friction had little impact on the US of the connection;the proposed IFL and US formulas can effectively derive the residual anti⁃slip capacity of FHSB T⁃stub connections from the degree of damage of the corroded nut section.The research results provide a scientific basis for the replacement and maintenance of corroded bolts of FHSB T⁃stub connections.展开更多
Hydrogen has been deemed as one of the most efficient energy carriers for a broad variety of industrial applications[1,2].Large-scale,low-cost hydrogen production,safe storage and delivery represent a tremendous techn...Hydrogen has been deemed as one of the most efficient energy carriers for a broad variety of industrial applications[1,2].Large-scale,low-cost hydrogen production,safe storage and delivery represent a tremendous technological challenge and have become a subject of intense research and development activities in the past few decades[3–5].展开更多
Silicon monoxide(SiO)is an attractive anode material for next-generation lithium-ion batteries for its ultra-high theoretical capacity of 2680 mAh g−1.The studies to date have been limited to electrodes with a rela-ti...Silicon monoxide(SiO)is an attractive anode material for next-generation lithium-ion batteries for its ultra-high theoretical capacity of 2680 mAh g−1.The studies to date have been limited to electrodes with a rela-tively low mass loading(<3.5 mg cm^(−2)),which has seriously restricted the areal capacity and its potential in practical devices.Maximizing areal capacity with such high-capacity materials is critical for capitalizing their potential in practi-cal technologies.Herein,we report a monolithic three-dimensional(3D)large-sheet holey gra-phene framework/SiO(LHGF/SiO)composite for high-mass-loading electrode.By specifically using large-sheet holey graphene building blocks,we construct LHGF with super-elasticity and exceptional mechanical robustness,which is essential for accommodating the large volume change of SiO and ensuring the structure integrity even at ultrahigh mass loading.Additionally,the 3D porous graphene network structure in LHGF ensures excellent electron and ion transport.By systematically tailoring microstructure design,we show the LHGF/SiO anode with a mass loading of 44 mg cm^(−2)delivers a high areal capacity of 35.4 mAh cm^(−2)at a current of 8.8 mA cm^(−2)and retains a capacity of 10.6 mAh cm^(−2)at 17.6 mA cm^(−2),greatly exceeding those of the state-of-the-art commercial or research devices.Furthermore,we show an LHGF/SiO anode with an ultra-high mass loading of 94 mg cm^(−2)delivers an unprecedented areal capacity up to 140.8 mAh cm^(−2).The achievement of such high areal capacities marks a critical step toward realizing the full potential of high-capacity alloy-type electrode materials in practical lithium-ion batteries.展开更多
Graphene was produced via a soft chemistry synthetic route for lithium ion battery applications. The sample was characterized by X-ray diffraction, nitrogen adsorption-desorption, field emission scanning electron micr...Graphene was produced via a soft chemistry synthetic route for lithium ion battery applications. The sample was characterized by X-ray diffraction, nitrogen adsorption-desorption, field emission scanning electron microscopy and transmission electron microscopy, respectively. The electrochemical performances of graphene as anode material were measured by cyclic voltammetry and galvanostatic charge/ discharge cycling. The experimental results showed that the graphene possessed a thin wrinkled paper-like morphology and large specific surface area (342 m2 · g ^-1). The first reversible specific capacity of the graphene was as high as 905 mA· h · g ^-1 at a current density of 100 mA · g ^-1. Even at a high current density of 1000 or 2000 mA · g ^-1, the graphene maintained good cycling stability, indicating that it is a promising anode material for high-performance lithium ion batteries.展开更多
Composites that can rapidly self-healing their structure and function at room temperature have broad application prospects.However,in view of the complexity of composite structure and composition,its self-heal is faci...Composites that can rapidly self-healing their structure and function at room temperature have broad application prospects.However,in view of the complexity of composite structure and composition,its self-heal is facing challenges.In this article,supramolecular effect is proposed to repair the multistage structure,mechanical and thermal properties of composite materials.A stiff and tough supramolecular frameworks of 2-[[(butylamino)carbonyl]oxy]ethyl ester(PBA)–polydimethylsiloxane(PDMS)were established using a chain extender with double amide bonds in a side chain to extend prepolymers through copolymerization.Then,by introducing the copolymer into a folded graphene film(FGf),a highly thermally conductive composite of PBA–PDMS/FGf with self-healing capacity was fabricated.The ratio of crosslinking and hydrogen bonding was optimized to ensure that PBA–PDMS could completely self-heal at room temperature in 10 min.Additionally,PBA–PDMS/FGf exhibits a high tensile strength of 2.23±0.15 MPa at break and high thermal conductivity of 13±0.2 W m^(−1)K^(−1);of which the self-healing efficiencies were 100%and 98.65%at room temperature for tensile strength and thermal conductivity,respectively.The excellent self-healing performance comes from the efficient supramolecular interaction between polymer molecules,as well as polymer molecule and graphene.This kind of thermal conductive self-healing composite has important application prospects in the heat dissipation field of next generation electronic devices in the future.展开更多
Aqueous battery-supercapacitor hybrid devices(BSHs)are of great importance to enrich electrochemical energy storage systems with both high energy and power densities.However,further improvement of BSHs in aqueous elec...Aqueous battery-supercapacitor hybrid devices(BSHs)are of great importance to enrich electrochemical energy storage systems with both high energy and power densities.However,further improvement of BSHs in aqueous electrolytes is greatly hampered by operating voltage and capacity limits.Different from the conventional intercalation/de-intercalation mechanism,Bi_(2)O_(3) implements charge storage by a reversible phase conversion mechanism.Herein,taking Bi_(2)O_(3) electrode with wide potential window(from-1.2 to 1 V vs.saturated calomel electrode)and high capacity as battery-type anode,we propose that the overall performance of aqueous BSHs can be greatly upgraded under neutral condition.By paring with stable layer-structuredδ-MnO_(2) cathode,a sodium-ion Bi_(2)O_(3)//MnO_(2) BSH with an ultrahigh voltage of 2.4 V in neutral sodium sulfate electrolyte is developed for the first time.This hybrid device exhibits high capacity(~215 C g^(-1) at 1 mA cm^(-2)),relatively long lifespan(~77.2%capacity retention after 1500 cycles),remarkable energy density(71.7 Wh kg^(-1)@400.5 W kg^(-1))and power density(3204.3 W kg^(-1)@18.8 Wh kg^(-1)).Electrochemical measurements combining a set of spectroscopic techniques reveal the reversible phase conversion between bismuth oxide and metallic bismuth(Bi_(2)O_(3)?Bi0)through Bi^(2+) transition phase in neutral sodium sulfate solution,which can deliver multielectron transfer up to 6,leading to the high-energy BSHs.Our work sheds light on the feasibility of using Bi_(2)O_(3) electrode under neutral condition to address the issue of narrow voltage and low capacity for aqueous BSHs.展开更多
Cylindrical nickel metal hydride (Ni-MH) battery with high specific volume capacity was prepared by using the oxyhydroxide Ni(OH)2 and AB5 type hydrogen storage alloy and adjusting the designing parameters of posi...Cylindrical nickel metal hydride (Ni-MH) battery with high specific volume capacity was prepared by using the oxyhydroxide Ni(OH)2 and AB5 type hydrogen storage alloy and adjusting the designing parameters of positive and negative electrodes. The oxyhydroxide Ni(OH)2 was synthesized by oxidizing spherical β-Ni(OH)2 with chemical method. The X-ray diffraction (XRD) patterns and the Fourier transform infrared (PT-IR) spectra indicated that 7-NiOOH was formed on the oxyhydroxide Ni(OH)2 powders, and some H2O molecules were inserted into their crystal lattice spacing. The battery capacity could not be improved when the oxyhydroxide Ni(OH)2 sample was directly used as the positive active materials. However, based on the conductance and residual capacity of the oxyhydroxide Ni(OH)2 powders, AA size Ni-MH battery with 2560 mA.h capacity and 407 W·h·L^-1 specific volume energy at 0.2C was obtained by using the commercial spherical β-Ni(OH)2 and AB5-type hydrogen-storage alloy powders as the active materials when 10% mass amount of the oxyhydroxide Ni(OH)2 with 2.50 valence was added to the positive active materials and subsequently the battery designing parameters were adjusted as well. The as-prepared battery showed 70% initial capacity after 80 cycles at 0.5C. The possibility for adjusting the capacity ratio of positive and negative electrodes from 1 : 1.35 to 1 : 1.22 was demonstrated preliminarily. It is considered the as-prepared battery can meet the requirement of some special portable electrical instruments.展开更多
We propose a new design of the high channel capacity in Mobile Ad Hoc Network that uses the dense wave-length division multiplexing wavelength enhancement, in which the increasing in channel capacity and sig-nal secur...We propose a new design of the high channel capacity in Mobile Ad Hoc Network that uses the dense wave-length division multiplexing wavelength enhancement, in which the increasing in channel capacity and sig-nal security can be provided. The increasing in number of channel can be obtained by the increasing in wavelength density, while the security is introduced by the specific wavelength filter, which is operated by the Ad Hoc node operator and link with other nodes in coverage by dedicated one-to-one in direct or relay node. The optical communication wavelength enhancement is reviewed. The advantage is that the proposed system can be implemented and used incorporating with the existed communication link in both infrastruc-ture-based and Ad Hoc networks wireless network, where the privacy can be provided, which is discussed in details.展开更多
Aqueous zinc ion hybrid capacitors(ZIHCs)hold great potential for large-scale energy storage applications owing to their high safety and low cost,but suffer from low capacity and energy density.Herein,pyridinic nitrog...Aqueous zinc ion hybrid capacitors(ZIHCs)hold great potential for large-scale energy storage applications owing to their high safety and low cost,but suffer from low capacity and energy density.Herein,pyridinic nitrogen enriched porous carbon(nPC)was successfully synthesized via the growth,subsequent annealing and acid etching of bimetal organic frameworks for high capacity and safe ZIHCs with exceptional rate capability.Benefiting from the mesopores for easy ion diffusion,high electrical conductivity enabled by in-situ grown carbon nanotubes matrix and residual metal Co nanoparticles for fast electron transfer,sufficient micropores and high N content(8.9 at%)with dominated pyridinic N(54%)for enhanced zinc ion storage,the resulting nPC cathodes for ZIHCs achieved high capacities of 302 and137 m Ah g^(-1) at 1 and 18 A g^(-1),outperforming most reported carbon based cathodes.Theoretical results further disclosed that pyridinic N possessed larger binding energy of-4.99 eV to chemically coordinate with Zn2+than other N species.Moreover,quasi-solid-state ZIHCs with gelatin based gel electrolytes exhibited high energy density of 157.6 Wh kg^(-1) at 0.69 kW kg^(-1),high safety and mechanical flexibility to withstand mechanical deformation and drilling.This strategy of developing pyridinic nitrogen enriched porous carbon will pave a new avenue to construct safe ZIHCs with high energy densities.展开更多
This paper presents the results of an experimental study carried out using large scale equipment to observe the effect of geometry on gas distribution properties of a high capacity corrugated sheet structured packing ...This paper presents the results of an experimental study carried out using large scale equipment to observe the effect of geometry on gas distribution properties of a high capacity corrugated sheet structured packing (Montz-pak B 1-250M) and to compare it with that of its conventional counterpart (Montz-pak B1-250). Although the high capacity packing exhibits a significantly lower overall pressure drop, the gas distribution performance is similar to that of the conventional packing, and in both cases consistently good one.展开更多
Magnesium hydride has attracted great attention because of its high theoretical capacity and outstanding reversibility, nevertheless, its practical applications have been restricted by the disadvantages of the sluggis...Magnesium hydride has attracted great attention because of its high theoretical capacity and outstanding reversibility, nevertheless, its practical applications have been restricted by the disadvantages of the sluggish kinetics and high thermodynamic stability. In this work, an unexpected high reversible hydrogen capacity over 8.0 wt% has been achieved from MgH2 metal hydride composited with small amounts of LiBH4 and Li3AlH6 complex hydrides, which begins to release hydrogen at 276 ℃ and then completely dehydrogenates at 360 ℃. The dehydrogenated MgH2+LiBH4/Li3AlH6 composite can fully reabsorb hydrogen below 300 ℃ with an excellent cycling stability. The composite exhibits a significant reduction of dehydrogenation activation energy from 279.7 kJ/mol(primitive MgH2) to 139.3 kJ/mol(MgH2+LiBH4/Li3AlH6),as well as a remarkable reduction of dehydrogenation enthalpy change from 75.1 k J/mol H2(primitive MgH2) to 62.8 kJ/mol H2(MgH2+LiBH4/Li3AlH6). The additives of LiBH4 and Li3AlH6 not only enhance the cycling hydrogen capacity, but also simultaneously improve the reversible de/rehydrogenation kinetics, as well as the dehydrogenation thermodynamics. This notable improvement on the hydrogen absorption/desorption behaviors of the MgH2+LiBH4/Li3AlH6 composite could be attributed to the dehydrogenated products including Li3Mg7, Mg17Al12 and MgAlB4, which play a key role on reducing the dehydrogenation activation energy and increasing diffusion rate of hydrogen. Meanwhile, the LiBH4 and Li3AlH6 effectively destabilize MgH2 with a remarkable reduction on dehydrogenation enthalpy change in terms of thermodynamics. In particular, the Li3Mg7, Mg17Al12 and MgAlB4 phases can reversibly transform into MgH2, Li3AlH6 and LiBH4 after rehydrogenation, which contribute to maintain a high cycling capacity.This constructing strategy can further promote the development of high reversible capacity Mg-based materials with suitable de/rehydrogenation properties.展开更多
The addition of rare earth yttrium(Y) can improve the performances of high temperature titanium alloys,such as the tensile ductility,thermal stability and creep property,etc.However,few studies on the effect of Y on t...The addition of rare earth yttrium(Y) can improve the performances of high temperature titanium alloys,such as the tensile ductility,thermal stability and creep property,etc.However,few studies on the effect of Y on the castability of titanium alloys have been carried out,which is significant to fabrication of thin-walled complex titanium castings by investment casting.In this study,the microstructure and mold filling capacity of a Ti-1100 alloy with different Y additions(0,0.1wt.%,0.3wt.%,0.5wt.% and 1.0wt.%) were investigated systematically through investment casting experiments,and the casting experiments were carried out in a centrifugal titanium casting machine.The microstructures of the alloy were observed via the optical microscopy,scanning electron microscopy and transmission electron microscopy.The mold filling capacity was tested by using of a grid pattern and was evaluated by the number of segments completely filled by the cast alloy.The results indicate that the grain size is decreased and the mold filling capacity is improved significantly with increasing the addition of Y from 0 to 1.0wt.%.The average primary grain size of Ti-1100 alloy is reduced from 250 μm to 50 μm and the mold filling capacity is increased from 61.5% to 100%.Considering the potential harmful effect on tensile properties of titanium alloys due to high concentrations of Y,it is suggested that Y addition should be about 0.3wt.%.展开更多
Potassium-based dual ion batteries(KDIBs)have attracted significant attention owing to high working voltage,high safety,low processing cost,and environmental friendliness.Nevertheless,one great challenge for practical...Potassium-based dual ion batteries(KDIBs)have attracted significant attention owing to high working voltage,high safety,low processing cost,and environmental friendliness.Nevertheless,one great challenge for practical KDIBs is to develop suitable anode materials with high specific capacity.Herein,we report an architecture of hierarchically porous antimony nanoparticles/carbon nanofibers(HPSb CNFs)as flexible,free-standing anode for high-performance KDIBs.The HPSb CNFs with hierarchically porous structure,and high-content nitrogen doping,not only offer sufficient free space to tolerate the repetitive volume expansion of Sb nanoparticles during long-term cycling,but also greatly facilitate the transport of electrons and ions within electrode,ensuring high material utilization ratio.Thus,the KDIBs,constituted by HPSb CNFs-700(calcined at 700°C)anode and graphite cathode,exhibited a high reversible capacity of 440 m Ah g^(-1)with high discharge medium voltage of 4.5 V at a specific current of 200 m A g^(-1)(the highest capacity for all KDIBs normalized by the mass of the anode),and excellent cyclic life.Outstanding electrochemical reversibility of the KDIBs was further demonstrated by ex situ XRD,ex situ Raman spectrum,and HRTEM.These results suggest the as-designed HPSb CNFs-700 with highcapacity and long-term cycling stability is a promising anode material for high-performance KDIBs.展开更多
Construction of a thickness‐independent electrode with high active material mass loading is crucial for the development of high energy rechargeable lithium battery.Herein,we fabricate an all‐in‐one integrated SnS2@...Construction of a thickness‐independent electrode with high active material mass loading is crucial for the development of high energy rechargeable lithium battery.Herein,we fabricate an all‐in‐one integrated SnS2@3D multichannel carbon matrix(SnS2@3DMCM)electrode with in‐situ growth of ultrathin SnS2 nanosheets inside the inner walls of three dimensional(3D)multichannels.The interconnected conductive carbon matrix derived from natural wood acts as an integrated porous current collector to avail the electrons transport and accommodate massive SnS2 nanosheets,while plenty of 3D aligned multichannels facilitate fast ions transport with electrode thickness‐independent even under high mass loading.As expected,the integrated SnS2@3DMCM electrode exhibits remarkable electrochemical lithium storage performance,such as exceptional high‐areal‐capacity of 6.4 mAh cm−2,high rate capability of 3 mAh cm−2 under current of 6.8 mAcm−2(10 C),and stable cycling performance of 6.8 mAcm−2 with a high mass loading of 7mg cm−2.The 3D integrated porous electrode constructing conveniently with the natural source paves new avenues towards future high‐performance lithium batteries.展开更多
A mathematical model was developed to predict the maximum heat transfer capacity of high temperature heat pipe with triangular grooved wick. The effects of the inclination angle and geometry structure were considered ...A mathematical model was developed to predict the maximum heat transfer capacity of high temperature heat pipe with triangular grooved wick. The effects of the inclination angle and geometry structure were considered in the proposed model.Maximum heat transfer capacity was also investigated experimentally. The model was validated by comparing with the experimental results. The maximum heat transfer capacity increases with the vapor core radius increasing. Compared with the inclination angle of0°, the maximum heat transfer capacity increases at the larger inclination angle, and the change with temperature is larger. The performance of heat pipe with triangular grooved wick is greatly influenced by gravity, so it is not recommended to be applied to the dish solar heat pipe receiver.展开更多
Manufacturing process,diffusion co-efficient and areal capacity are the three main criteria for regulating thick electrodes for lithium-ion batteries(LIBs).However,simultaneously regulating these criteria for LIBs is ...Manufacturing process,diffusion co-efficient and areal capacity are the three main criteria for regulating thick electrodes for lithium-ion batteries(LIBs).However,simultaneously regulating these criteria for LIBs is desirable but remains a significant challenge.In this work,niobium pentoxide(Nb_(2)O_(5))anode and lithium iron phosphate(LiFePO_(4))cathode materials were chosen as the model materials and demonstrate that these three parameters can be simultaneously modulated by incorporation of micro-carbon fibers(MCF)and carbon nanotubes(CNT)with both Nb_(2)O_(5) and LFP via vacuum filtration approach.Both as-prepared MNC-20 anode and MLC-20 cathode achieves high reversible areal capacity of≈5.4 m A h cm^(-2)@0.1 C and outstanding Li-ion diffusion coefficients of≈10~(-8)cm~2 s~(-1)in the half-cell configuration.The assembled MNC-20‖MLC-20 full cell LIB delivers maximum energy and power densities of244.04 W h kg^(-1)and 108.86 W kg^(-1),respectively.The excellent electrochemical properties of the asprepared thick electrodes can be attributed to the highly conductive,mechanical compactness and multidimensional mutual effects of the MCF,CNT and active materials that facilitates rapid Li-ion diffusion kinetics.Furthermore,electrochemical impedance spectroscopy(EIS),symmetric cells analysis,and insitu Raman techniques clearly validates the enhanced Li-ion diffusion kinetics in the present architecture.展开更多
基金supported by National Key Research and Development Program of China(2021YFB4000602)National Natural Science Foundation of PR China(Nos.52071287,52072342,52271227)+3 种基金National Outstanding Youth Foundation of China(No.52125104)Natural Science Foundation of Zhejiang Province,PR China(No.LZ23E010002)Young Talent Fund of Association for Science and Technology in Shaanxi,China(No.20220456)Young Star Project of Science and Technology of Shaanxi Province(2022KJXX-43).
文摘LiBH_(4)with high hydrogen storage density,is regarded as one of the most promising hydrogen storage materials.Nevertheless,it suffers from high dehydrogenation temperature and poor reversibility for practical use.Nanoconfinement is effective in achieving low dehydrogenation temperature and favorable reversibility.Besides,graphene can serve as supporting materials for LiBH_(4)catalysts and also destabilize LiBH_(4)via interfacial reaction.However,graphene has never been used alone as a frame material for nanoconfining LiBH_(4).In this study,graphene microflowers with large pore volumes were prepared and used as nanoconfinement framework material for LiBH_(4),and the nanoconfinement effect of graphene was revealed.After loading 70 wt%of LiBH_(4) and mechanically compressed at 350 MPa,8.0 wt% of H2 can be released within 100 min at 320C,corresponding to the highest volumetric hydrogen storage density of 94.9 g H2 L^(-1)ever reported.Thanks to the nanoconfinement of graphene,the rate-limiting step of dehydrogenation of nanoconfined LiBH_(4) was changed and its apparent activation energy of the dehydrogenation(107.3 kJ mol^(-1))was 42%lower than that of pure LiBH_(4).Moreover,the formation of the intermediate Li_(2)B_(12)H_(12) was effectively inhibited,and the stable nanoconfined structure enhanced the reversibility of LiBH_(4).This work widens the understanding of graphene's nanoconfinement effect and provides new insights for developing high-density hydrogen storage materials.
基金the financial support by the National Natural Science Foundation of China (22371010, 21771017, and 51702009)the "Hundred Talents Program" of the Chinese Academy of Sciences, the Fundamental Research Funds for the Central Universities+1 种基金the Shenzhen Science and Technology Program (JCYJ20210324115412035, JCYJ2021-0324123202008, JCYJ20210 324122803009 and ZDSYS20210813095534001)the Guangdong Basic and Applied Basic Research Foundation (2021A1515110880)
文摘The use of redox-active organic electrode materials in energy storage is restricted due to their inferior solvent resistance,abysmal conductivity,and the resultant low practical capacity.To address these issues,a class of bipolar p-phenylenediimidazole-based small-molecule compounds are designed and fabricated.Theπ-conjugated backbone of these small molecules allows for electron delocalization on a big conjugation plane,endowing them with good conductivity and reaction reversibility.Furthermore,when the para-positions of phenylene are occupied by hydroxyl groups,as-formed intramolecular hydrogen bonds(N-H...O)between phenolic hydroxyl groups and the–NH groups of imidazole rings further enhance the structural planarity,resulting in higherπ-conjugation degree and better conductivity,and thus higher utilization of active sites and electrode capacity,proved by both experimental results and theoretical calculations.The optimized composite electrode DBNQ@rGO-45 shows a high specific capacity(∼308 mA h g^(−1)at 100 mA g^(−1))and a long cycling stability(112.9 mA h g^(−1)after 6000 cycles at 2000 mA g^(−1)).The significantly better electrochemical properties for hydroxyl group-containing compounds than those without hydroxyl groups attributed to intramolecular hydrogen bond-induced conjugation enhancement will inspire the structure design of organic electrodes for better energy storage.
基金W.C.acknowledges the startup funds from USTC(Grant#KY2060000150)the Fundamental Research Funds for the Central Universities(WK2060000040).
文摘The commercialization of electrolytic MnO_(2)-Zn batteries is highly applauded owing to the advantages of cost-effectiveness,high safety,high energy density,and durable working performance.However,due to the low reversibility of the cathode MnO_(2)/Mn^(2+)chemistry at high areal capacities and the severe Zn anode corrosion,the practical application of MnO_(2)-Zn batteries is hampered by inadequate lifespan.Leveraging the full advantage of an iodine redox mediator,here we design a highly rechargeable electrolytic MnO_(2)-Zn battery with a high areal capacity.The MnO_(2)-Zn battery coupled with an iodine mediator in a mild electrolyte shows a high discharge voltage of 1.85 V and a robust areal capacity of 10 mAh cm^(-2)under a substantial discharge current density of 160 mA cm^(-2).The MnO_(2)/I_(2)-Zn battery with an areal capacity of 10 mAh cm^(-2)exhibits prolonged stability of over 950 cycles under a high-capacity retention of~94%.The scaled-up MnO_(2)/I_(2)-Zn battery reveals a stable cycle life under a cell capacity of~600 mAh.Moreover,our constructed MnO_(2)/I_(2)-Zn battery demonstrates a practical energy density of~37 Wh kg^(-1)and a competitive energy cost of<18 US$kWh^(-1)by taking into account the cathode,anode,and electrolyte.The MnO_(2)/I_(2)-Zn battery,with its remarkable reversibility and reasonable energy density,enlightens a new arena of large-scale energy storage devices.
基金supported by the National Natural Science Foundation of China(22179019)the Natural Science Foundation of Hebei Province,China(B2020501003)the Fundamental Research Funds for the Central Universities(N2023030)。
文摘Zinc-based flow batteries(ZFBs)have aroused great favor in large-scale energy storage due to the high security and low cost.However,the low areal capacity arising from the limited space for Zn plating hinders the further development.Herein,a novel carbon felt-Sn-carbon felt sandwich host(CSCH)is designed and constructed.Benefiting from the strong chemical absorption and the dehydration effect on Zn(H_(2)O)_(6)^(2+),the Sn activation layer in the CSCH demonstrates the lowest comprehensive resistance for Zn deposition.Thus,Zn is induced to nucleate preferentially on the Sn activation layer,and grows towards the membrane,regulating the spatial distribution of Zn electrochemical deposits,which remarkably improves the areal capacity and cyclic stability of Zn anode.Consequently,the zinc-bromine flow batteries equipped with CSCH electrodes can achieve the ultra-high areal capacity of 120 mA h cm^(-2)at 80 mA cm^(-2),and run stably for 140 h with average energy efficiency of 80.3%in the extreme condition(80 mA cm^(-2),80 mA h cm^(-2)).This innovative work will inspire future advanced designs for high areal capacity electrodes in ZFBs.
文摘Corrosion is a primary cause of the slippage of friction⁃type high⁃strength bolted(FHSB)T⁃stub connections.This paper attempts to quantify the residual capacity of FHSB T⁃stub connections with corroded nuts.Firstly,corrosion simulation tests were conducted on 48 manually cut nuts to find out the relationship between the damage degree of nut section and the residual clamping force(RCF)of bolt.Then,static load tests were carried out on 24 FHSB T⁃stub connections with nuts of different degrees of damage to obtain the failure modes.By finite⁃element(FE)models,a comparative analysis was performed on the initial friction load(IFL)and ultimate strength(US)of each connection with corroded nuts.Finally,the parameters of 96 FE models for FHSB T⁃stub connections were analyzed and used to derive the calculation formulas for the degree of damage for each nut and the IFL and US of each connection.The results show that the RCF decay of a bolt is a quadratic function of the equivalent radius loss ratio and the shear failure after nut corrosion;the IFL of each connection had a clear linear correlation with the RCF of the corresponding bolts,and the correlation depends on the applied load and static friction on connecting plate interface induced by the clamping force;the static friction had little impact on the US of the connection;the proposed IFL and US formulas can effectively derive the residual anti⁃slip capacity of FHSB T⁃stub connections from the degree of damage of the corroded nut section.The research results provide a scientific basis for the replacement and maintenance of corroded bolts of FHSB T⁃stub connections.
基金the financial support from the National Natural Science Foundation of China(Nos.21473164,21603195 and 21875225)Major project of Technical Innovation of Hubei Province(No.2017AAA126)the Fundamental Research Funds for Central Universities,China University of Geosciences(Wuhan)(Nos.CUGL170405 and CUG180604)。
文摘Hydrogen has been deemed as one of the most efficient energy carriers for a broad variety of industrial applications[1,2].Large-scale,low-cost hydrogen production,safe storage and delivery represent a tremendous technological challenge and have become a subject of intense research and development activities in the past few decades[3–5].
基金support by the National Natural Science Foundation of China(Nos.52074113,22005091)the Fundamental Research Funds of the Central Universities(No.531107051048)+6 种基金the Changsha Municipal Natural Science Foundantion(Grant No.43184)the CITIC Metals Ningbo Energy Co.Ltd.(No.H202191380246)Xidong Duan acknowledges support by the National Natural Science Foundation of China(Nos.51991343,51991340,61804050 and 51872086)the Hunan Key Laboratory of Two-Dimensional Materials(No.2018TP1010)Junfei Liang acknowledges support by the National Natural Science Foundation of China(No.U1910208)the National Natural Science Foundation of Shanxi Province(No.201901D111137)Tao Wang acknowledges support by the National Natural Science Foundation of China(No.22005092).
文摘Silicon monoxide(SiO)is an attractive anode material for next-generation lithium-ion batteries for its ultra-high theoretical capacity of 2680 mAh g−1.The studies to date have been limited to electrodes with a rela-tively low mass loading(<3.5 mg cm^(−2)),which has seriously restricted the areal capacity and its potential in practical devices.Maximizing areal capacity with such high-capacity materials is critical for capitalizing their potential in practi-cal technologies.Herein,we report a monolithic three-dimensional(3D)large-sheet holey gra-phene framework/SiO(LHGF/SiO)composite for high-mass-loading electrode.By specifically using large-sheet holey graphene building blocks,we construct LHGF with super-elasticity and exceptional mechanical robustness,which is essential for accommodating the large volume change of SiO and ensuring the structure integrity even at ultrahigh mass loading.Additionally,the 3D porous graphene network structure in LHGF ensures excellent electron and ion transport.By systematically tailoring microstructure design,we show the LHGF/SiO anode with a mass loading of 44 mg cm^(−2)delivers a high areal capacity of 35.4 mAh cm^(−2)at a current of 8.8 mA cm^(−2)and retains a capacity of 10.6 mAh cm^(−2)at 17.6 mA cm^(−2),greatly exceeding those of the state-of-the-art commercial or research devices.Furthermore,we show an LHGF/SiO anode with an ultra-high mass loading of 94 mg cm^(−2)delivers an unprecedented areal capacity up to 140.8 mAh cm^(−2).The achievement of such high areal capacities marks a critical step toward realizing the full potential of high-capacity alloy-type electrode materials in practical lithium-ion batteries.
基金Funded by the Chongqing University Scientific&Technological Innovation Fund for Graduates(No.CDJXS12130006)
文摘Graphene was produced via a soft chemistry synthetic route for lithium ion battery applications. The sample was characterized by X-ray diffraction, nitrogen adsorption-desorption, field emission scanning electron microscopy and transmission electron microscopy, respectively. The electrochemical performances of graphene as anode material were measured by cyclic voltammetry and galvanostatic charge/ discharge cycling. The experimental results showed that the graphene possessed a thin wrinkled paper-like morphology and large specific surface area (342 m2 · g ^-1). The first reversible specific capacity of the graphene was as high as 905 mA· h · g ^-1 at a current density of 100 mA · g ^-1. Even at a high current density of 1000 or 2000 mA · g ^-1, the graphene maintained good cycling stability, indicating that it is a promising anode material for high-performance lithium ion batteries.
基金financially supported by National Natural Science Foundation of China (Grant Nos. 52173078, 52130303, 51973158, 51803151, and 51973152)the Science Foundation for Distinguished Young Scholars in Tianjin (No. 19JCJQJC61700)Tianjin Postgraduate Scientific Research Innovation Project in 2019 (2019YJSB181)
文摘Composites that can rapidly self-healing their structure and function at room temperature have broad application prospects.However,in view of the complexity of composite structure and composition,its self-heal is facing challenges.In this article,supramolecular effect is proposed to repair the multistage structure,mechanical and thermal properties of composite materials.A stiff and tough supramolecular frameworks of 2-[[(butylamino)carbonyl]oxy]ethyl ester(PBA)–polydimethylsiloxane(PDMS)were established using a chain extender with double amide bonds in a side chain to extend prepolymers through copolymerization.Then,by introducing the copolymer into a folded graphene film(FGf),a highly thermally conductive composite of PBA–PDMS/FGf with self-healing capacity was fabricated.The ratio of crosslinking and hydrogen bonding was optimized to ensure that PBA–PDMS could completely self-heal at room temperature in 10 min.Additionally,PBA–PDMS/FGf exhibits a high tensile strength of 2.23±0.15 MPa at break and high thermal conductivity of 13±0.2 W m^(−1)K^(−1);of which the self-healing efficiencies were 100%and 98.65%at room temperature for tensile strength and thermal conductivity,respectively.The excellent self-healing performance comes from the efficient supramolecular interaction between polymer molecules,as well as polymer molecule and graphene.This kind of thermal conductive self-healing composite has important application prospects in the heat dissipation field of next generation electronic devices in the future.
基金supported by the National Natural Science Foundation of China (21872105, 22072107)the Science & Technology Commission of Shanghai Municipality (19DZ2271500)。
文摘Aqueous battery-supercapacitor hybrid devices(BSHs)are of great importance to enrich electrochemical energy storage systems with both high energy and power densities.However,further improvement of BSHs in aqueous electrolytes is greatly hampered by operating voltage and capacity limits.Different from the conventional intercalation/de-intercalation mechanism,Bi_(2)O_(3) implements charge storage by a reversible phase conversion mechanism.Herein,taking Bi_(2)O_(3) electrode with wide potential window(from-1.2 to 1 V vs.saturated calomel electrode)and high capacity as battery-type anode,we propose that the overall performance of aqueous BSHs can be greatly upgraded under neutral condition.By paring with stable layer-structuredδ-MnO_(2) cathode,a sodium-ion Bi_(2)O_(3)//MnO_(2) BSH with an ultrahigh voltage of 2.4 V in neutral sodium sulfate electrolyte is developed for the first time.This hybrid device exhibits high capacity(~215 C g^(-1) at 1 mA cm^(-2)),relatively long lifespan(~77.2%capacity retention after 1500 cycles),remarkable energy density(71.7 Wh kg^(-1)@400.5 W kg^(-1))and power density(3204.3 W kg^(-1)@18.8 Wh kg^(-1)).Electrochemical measurements combining a set of spectroscopic techniques reveal the reversible phase conversion between bismuth oxide and metallic bismuth(Bi_(2)O_(3)?Bi0)through Bi^(2+) transition phase in neutral sodium sulfate solution,which can deliver multielectron transfer up to 6,leading to the high-energy BSHs.Our work sheds light on the feasibility of using Bi_(2)O_(3) electrode under neutral condition to address the issue of narrow voltage and low capacity for aqueous BSHs.
基金Supported by the Natural Science Foundation of Department of Education (05Z008) and the Science and Technology Projects of Guangdong Province (2007B030101007).
文摘Cylindrical nickel metal hydride (Ni-MH) battery with high specific volume capacity was prepared by using the oxyhydroxide Ni(OH)2 and AB5 type hydrogen storage alloy and adjusting the designing parameters of positive and negative electrodes. The oxyhydroxide Ni(OH)2 was synthesized by oxidizing spherical β-Ni(OH)2 with chemical method. The X-ray diffraction (XRD) patterns and the Fourier transform infrared (PT-IR) spectra indicated that 7-NiOOH was formed on the oxyhydroxide Ni(OH)2 powders, and some H2O molecules were inserted into their crystal lattice spacing. The battery capacity could not be improved when the oxyhydroxide Ni(OH)2 sample was directly used as the positive active materials. However, based on the conductance and residual capacity of the oxyhydroxide Ni(OH)2 powders, AA size Ni-MH battery with 2560 mA.h capacity and 407 W·h·L^-1 specific volume energy at 0.2C was obtained by using the commercial spherical β-Ni(OH)2 and AB5-type hydrogen-storage alloy powders as the active materials when 10% mass amount of the oxyhydroxide Ni(OH)2 with 2.50 valence was added to the positive active materials and subsequently the battery designing parameters were adjusted as well. The as-prepared battery showed 70% initial capacity after 80 cycles at 0.5C. The possibility for adjusting the capacity ratio of positive and negative electrodes from 1 : 1.35 to 1 : 1.22 was demonstrated preliminarily. It is considered the as-prepared battery can meet the requirement of some special portable electrical instruments.
文摘We propose a new design of the high channel capacity in Mobile Ad Hoc Network that uses the dense wave-length division multiplexing wavelength enhancement, in which the increasing in channel capacity and sig-nal security can be provided. The increasing in number of channel can be obtained by the increasing in wavelength density, while the security is introduced by the specific wavelength filter, which is operated by the Ad Hoc node operator and link with other nodes in coverage by dedicated one-to-one in direct or relay node. The optical communication wavelength enhancement is reviewed. The advantage is that the proposed system can be implemented and used incorporating with the existed communication link in both infrastruc-ture-based and Ad Hoc networks wireless network, where the privacy can be provided, which is discussed in details.
基金financially supported by the National Key R@D Program of China(Grants 2016YBF0100100 and 2016YFA0200200)National Natural Science Foundation of China(Grants 51872283,and 21805273)+8 种基金Liaoning BaiQianWan Talents Program,LiaoNing Revitalization Talents Program(Grant XLYC1807153)Natural Science Foundation of Liaoning Province(2020-MS-095)Joint Research Fund Liaoning-Shenyang National Laboratory for Materials Science(Grants 20180510038)DICP(DICP ZZBS201708,DICP ZZBS201802,and DICP I202032)DICP&QIBEBT(Grant No.DICP&QIBEBT UN201702)Dalian National Laboratory For Clean Energy(DNL),CAS,DNL Cooperation Fund,CAS(DNL180310,DNL180308,DNL201912,and DNL201915)the Fundamental Research Funds for the Central Universities of China(N180503012)the State Key Laboratory of Fine Chemicals(KF1911)the CAS Key Laboratory of Carbon Materials(KLCMKFJJ2004)。
文摘Aqueous zinc ion hybrid capacitors(ZIHCs)hold great potential for large-scale energy storage applications owing to their high safety and low cost,but suffer from low capacity and energy density.Herein,pyridinic nitrogen enriched porous carbon(nPC)was successfully synthesized via the growth,subsequent annealing and acid etching of bimetal organic frameworks for high capacity and safe ZIHCs with exceptional rate capability.Benefiting from the mesopores for easy ion diffusion,high electrical conductivity enabled by in-situ grown carbon nanotubes matrix and residual metal Co nanoparticles for fast electron transfer,sufficient micropores and high N content(8.9 at%)with dominated pyridinic N(54%)for enhanced zinc ion storage,the resulting nPC cathodes for ZIHCs achieved high capacities of 302 and137 m Ah g^(-1) at 1 and 18 A g^(-1),outperforming most reported carbon based cathodes.Theoretical results further disclosed that pyridinic N possessed larger binding energy of-4.99 eV to chemically coordinate with Zn2+than other N species.Moreover,quasi-solid-state ZIHCs with gelatin based gel electrolytes exhibited high energy density of 157.6 Wh kg^(-1) at 0.69 kW kg^(-1),high safety and mechanical flexibility to withstand mechanical deformation and drilling.This strategy of developing pyridinic nitrogen enriched porous carbon will pave a new avenue to construct safe ZIHCs with high energy densities.
文摘This paper presents the results of an experimental study carried out using large scale equipment to observe the effect of geometry on gas distribution properties of a high capacity corrugated sheet structured packing (Montz-pak B 1-250M) and to compare it with that of its conventional counterpart (Montz-pak B1-250). Although the high capacity packing exhibits a significantly lower overall pressure drop, the gas distribution performance is similar to that of the conventional packing, and in both cases consistently good one.
基金the financial supports for this research from the National Basic Research Program of China(2019YFB1505103)the National Natural Science Foundation of China(51571179 and 51671173)the Open Fund of the Guangdong Provincial Key Laboratory of Advance Energy Storage Materials。
文摘Magnesium hydride has attracted great attention because of its high theoretical capacity and outstanding reversibility, nevertheless, its practical applications have been restricted by the disadvantages of the sluggish kinetics and high thermodynamic stability. In this work, an unexpected high reversible hydrogen capacity over 8.0 wt% has been achieved from MgH2 metal hydride composited with small amounts of LiBH4 and Li3AlH6 complex hydrides, which begins to release hydrogen at 276 ℃ and then completely dehydrogenates at 360 ℃. The dehydrogenated MgH2+LiBH4/Li3AlH6 composite can fully reabsorb hydrogen below 300 ℃ with an excellent cycling stability. The composite exhibits a significant reduction of dehydrogenation activation energy from 279.7 kJ/mol(primitive MgH2) to 139.3 kJ/mol(MgH2+LiBH4/Li3AlH6),as well as a remarkable reduction of dehydrogenation enthalpy change from 75.1 k J/mol H2(primitive MgH2) to 62.8 kJ/mol H2(MgH2+LiBH4/Li3AlH6). The additives of LiBH4 and Li3AlH6 not only enhance the cycling hydrogen capacity, but also simultaneously improve the reversible de/rehydrogenation kinetics, as well as the dehydrogenation thermodynamics. This notable improvement on the hydrogen absorption/desorption behaviors of the MgH2+LiBH4/Li3AlH6 composite could be attributed to the dehydrogenated products including Li3Mg7, Mg17Al12 and MgAlB4, which play a key role on reducing the dehydrogenation activation energy and increasing diffusion rate of hydrogen. Meanwhile, the LiBH4 and Li3AlH6 effectively destabilize MgH2 with a remarkable reduction on dehydrogenation enthalpy change in terms of thermodynamics. In particular, the Li3Mg7, Mg17Al12 and MgAlB4 phases can reversibly transform into MgH2, Li3AlH6 and LiBH4 after rehydrogenation, which contribute to maintain a high cycling capacity.This constructing strategy can further promote the development of high reversible capacity Mg-based materials with suitable de/rehydrogenation properties.
文摘The addition of rare earth yttrium(Y) can improve the performances of high temperature titanium alloys,such as the tensile ductility,thermal stability and creep property,etc.However,few studies on the effect of Y on the castability of titanium alloys have been carried out,which is significant to fabrication of thin-walled complex titanium castings by investment casting.In this study,the microstructure and mold filling capacity of a Ti-1100 alloy with different Y additions(0,0.1wt.%,0.3wt.%,0.5wt.% and 1.0wt.%) were investigated systematically through investment casting experiments,and the casting experiments were carried out in a centrifugal titanium casting machine.The microstructures of the alloy were observed via the optical microscopy,scanning electron microscopy and transmission electron microscopy.The mold filling capacity was tested by using of a grid pattern and was evaluated by the number of segments completely filled by the cast alloy.The results indicate that the grain size is decreased and the mold filling capacity is improved significantly with increasing the addition of Y from 0 to 1.0wt.%.The average primary grain size of Ti-1100 alloy is reduced from 250 μm to 50 μm and the mold filling capacity is increased from 61.5% to 100%.Considering the potential harmful effect on tensile properties of titanium alloys due to high concentrations of Y,it is suggested that Y addition should be about 0.3wt.%.
基金financially supported by the National Natural Science Foundation of China(Grant No.21673070)the Fundamental Research Funds of the Central Universities(No.531107051048)Hunan Key Laboratory of Two-Dimensional Materials(No.801200005)
文摘Potassium-based dual ion batteries(KDIBs)have attracted significant attention owing to high working voltage,high safety,low processing cost,and environmental friendliness.Nevertheless,one great challenge for practical KDIBs is to develop suitable anode materials with high specific capacity.Herein,we report an architecture of hierarchically porous antimony nanoparticles/carbon nanofibers(HPSb CNFs)as flexible,free-standing anode for high-performance KDIBs.The HPSb CNFs with hierarchically porous structure,and high-content nitrogen doping,not only offer sufficient free space to tolerate the repetitive volume expansion of Sb nanoparticles during long-term cycling,but also greatly facilitate the transport of electrons and ions within electrode,ensuring high material utilization ratio.Thus,the KDIBs,constituted by HPSb CNFs-700(calcined at 700°C)anode and graphite cathode,exhibited a high reversible capacity of 440 m Ah g^(-1)with high discharge medium voltage of 4.5 V at a specific current of 200 m A g^(-1)(the highest capacity for all KDIBs normalized by the mass of the anode),and excellent cyclic life.Outstanding electrochemical reversibility of the KDIBs was further demonstrated by ex situ XRD,ex situ Raman spectrum,and HRTEM.These results suggest the as-designed HPSb CNFs-700 with highcapacity and long-term cycling stability is a promising anode material for high-performance KDIBs.
基金Innovation Program of Shanghai Municipal Education Commission,Grant/Award Number:2019‐01‐07‐00‐07‐E00015National Natural Science Foundation of China,Grant/Award Numbers:21875141,51671135,51971146+4 种基金Support of young teachers in Shanghai colleges and universities,Grant/Award Number:ZZslg18039Shanghai Outstanding Academic Leaders PlanProgram of Shanghai Subject Chief Scientist,Grant/Award Number:17XD1403000Shanghai Pujiang Program,Grant/Award Number:18PJ1409000Opening Project of State Key Laboratory of Advanced Chemical Power Sources,Grant/Award Number:SKL‐ACPS‐C‐23。
文摘Construction of a thickness‐independent electrode with high active material mass loading is crucial for the development of high energy rechargeable lithium battery.Herein,we fabricate an all‐in‐one integrated SnS2@3D multichannel carbon matrix(SnS2@3DMCM)electrode with in‐situ growth of ultrathin SnS2 nanosheets inside the inner walls of three dimensional(3D)multichannels.The interconnected conductive carbon matrix derived from natural wood acts as an integrated porous current collector to avail the electrons transport and accommodate massive SnS2 nanosheets,while plenty of 3D aligned multichannels facilitate fast ions transport with electrode thickness‐independent even under high mass loading.As expected,the integrated SnS2@3DMCM electrode exhibits remarkable electrochemical lithium storage performance,such as exceptional high‐areal‐capacity of 6.4 mAh cm−2,high rate capability of 3 mAh cm−2 under current of 6.8 mAcm−2(10 C),and stable cycling performance of 6.8 mAcm−2 with a high mass loading of 7mg cm−2.The 3D integrated porous electrode constructing conveniently with the natural source paves new avenues towards future high‐performance lithium batteries.
基金Project(51076062)supported by the National Natural Science Foundation of China
文摘A mathematical model was developed to predict the maximum heat transfer capacity of high temperature heat pipe with triangular grooved wick. The effects of the inclination angle and geometry structure were considered in the proposed model.Maximum heat transfer capacity was also investigated experimentally. The model was validated by comparing with the experimental results. The maximum heat transfer capacity increases with the vapor core radius increasing. Compared with the inclination angle of0°, the maximum heat transfer capacity increases at the larger inclination angle, and the change with temperature is larger. The performance of heat pipe with triangular grooved wick is greatly influenced by gravity, so it is not recommended to be applied to the dish solar heat pipe receiver.
基金supported by the Science and Technology Innovation Program of Hunan Province(2022WZ1012)the Hunan Joint International Laboratory of Advanced Materials and Technology for Clean Energy(2020CB1007)the Natural Science Foundation of Guangzhou(202201020147)。
文摘Manufacturing process,diffusion co-efficient and areal capacity are the three main criteria for regulating thick electrodes for lithium-ion batteries(LIBs).However,simultaneously regulating these criteria for LIBs is desirable but remains a significant challenge.In this work,niobium pentoxide(Nb_(2)O_(5))anode and lithium iron phosphate(LiFePO_(4))cathode materials were chosen as the model materials and demonstrate that these three parameters can be simultaneously modulated by incorporation of micro-carbon fibers(MCF)and carbon nanotubes(CNT)with both Nb_(2)O_(5) and LFP via vacuum filtration approach.Both as-prepared MNC-20 anode and MLC-20 cathode achieves high reversible areal capacity of≈5.4 m A h cm^(-2)@0.1 C and outstanding Li-ion diffusion coefficients of≈10~(-8)cm~2 s~(-1)in the half-cell configuration.The assembled MNC-20‖MLC-20 full cell LIB delivers maximum energy and power densities of244.04 W h kg^(-1)and 108.86 W kg^(-1),respectively.The excellent electrochemical properties of the asprepared thick electrodes can be attributed to the highly conductive,mechanical compactness and multidimensional mutual effects of the MCF,CNT and active materials that facilitates rapid Li-ion diffusion kinetics.Furthermore,electrochemical impedance spectroscopy(EIS),symmetric cells analysis,and insitu Raman techniques clearly validates the enhanced Li-ion diffusion kinetics in the present architecture.