Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment ...Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment of Ti_(3)C_(2)MXene under Ar/H_(2)S atmosphere to facilitate the hydrogen release and uptake from MgH_(2).The S-Ti_(3)C_(2)exhibited pleasant catalytic effect on the hydriding/dehydriding kinetics and cyclic stability of MgH_(2).The addition of 5 wt%S-Ti_(3)C_(2)into MgH_(2)resulted in a reduction of 114℃in the starting dehydriding temperature compared to pure MgH_(2).MgH_(2)+5 wt%S-Ti_(3)C_(2)sample could quickly release 6.6 wt%hydrogen in 17 min at 220℃,and 6.8 wt%H_(2)was absorbed in 25 min at 200℃.Cyclic testing revealed that MgH_(2)+5 wt%S-Ti_(3)C_(2)system achieved a reversible hydrogen capacity of 6.5 wt%.Characterization analysis demonstrated that Ti-species(Ti0,Ti^(2+),Ti-S,and Ti^(3+))as active species significantly lowered the dehydrogenation temperature and promoted the re-/dehydrogenation kinetics of MgH_(2),and sulfur doping can effectively improve the stability of Ti0 and Ti^(3+),contributing to the improvement of cyclic stability of MgH_(2).This study provides strategy for the construction of catalysts for hydrogen storage materials.展开更多
Rich-nickel layered ternary NCM811 has been widely used in the field of electric vehicles ascribed to its high theoretical specific capacity.However,poor cycling stability and rate-performance hindered its further dev...Rich-nickel layered ternary NCM811 has been widely used in the field of electric vehicles ascribed to its high theoretical specific capacity.However,poor cycling stability and rate-performance hindered its further development.Herein,different amounts of nitrogen-doped carbon were wrapped on the surface of NCM811 via a facile rheological phase method by regulating the amount of dopamine hydrochloride.The effects of the coating amounts on the structure and electrochemical performance are investigated.The DFT calculation,XRD,SEM and XPS reveal that an appropriate amount of nitrogen-doped carbon coating could uniformly form a protective layer on the NCM811 surface and the introduced N could anchor Ni atoms to inhibit the Li^(+)/Ni^(2+)mixing,but excessive amount would reduce Ni^(3+)to Ni^(2+)so as to conversely aggravate Li^(+)/Ni^(2+)mixing.Among the samples,the NCM811-CN0.75 sample exhibits the most excellent electrochemical performance,delivering a high-rate capacity of 151.6 mA·h/g at 10C,and long-term cyclability with 82.2%capacity retention after 300 cycles at 5C,exhibiting remarkable rate-performance and cyclability.展开更多
The accumulative shear deformation of soft clays under cyclic loads is considered as pseudo-static creep. A pseudo-static elasto-plastic cyclic creep model is developed based on the visco-elasto-plastic theory. The pa...The accumulative shear deformation of soft clays under cyclic loads is considered as pseudo-static creep. A pseudo-static elasto-plastic cyclic creep model is developed based on the visco-elasto-plastic theory. The parameters in the model are determined by cyclic triaxial soil tests. A method for analyzing the stability of offshore soft foundation under wave loads is given by combining the model with pseudo-static creep analysis. An example is analyzed by the method. The results show that the horizontal and vertical stability of foundations under wave loads can be analyzed by it and the analytical results are qualitatively consistent with the observed failure modes of shallow foundations.展开更多
Lithium-metal battery based on Ni-rich cathode provides high energy density but presents poor cyclic stability due to the unstable electrode/electrolyte interfaces on both cathode and anode.In this work,we report a ne...Lithium-metal battery based on Ni-rich cathode provides high energy density but presents poor cyclic stability due to the unstable electrode/electrolyte interfaces on both cathode and anode.In this work,we report a new strategy to address this issue.It is found that the cyclic stability of Ni-rich/Li battery can be significantly improved by using succinic anhydride(SA) as an electrolyte additive.Specifically,the capacity retention of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)/Li cell is improved from 14% to 83% after 200cycles at 1 C between 3.0 and 4.35 V by applying 5% SA.The underlying mechanism of SA contribution is understood by comparing the effects of malic anhydride(MA) and citraconic anhydride(CA), both of which share a similar molecular structure to SA but show different effects.On anode side,SA can but MA and CA cannot form a protective solid electrolyte interphase(SEI) on Li anode.On cathode side,three anhydrides can suppress the formation of hydrogen fluoride from electrolyte oxidation decomposition,but SA behaves best.Typically,MA shows adverse effects on the interface stability of Li anode and NCM811 cathode,which originates from its high acidity.Though the acidity of MA can be mitigated by substituting a methyl for one H atom at its C=C bond,the substituent CA cannot compete with SA in cyclic stability improvement of the cell,because the SEI resulting from CA is not as robust as that from SA,which is related to the binding energy of the SEI components.This understanding reveals the importance of the electrolyte acidity on the Ni-rich cathode and the robustness of the SEI on Li anode,which is helpful for rationally designing new electrolyte additives to further improve the cyclic stability of high-energydensity Ni-rich/Li batteries.展开更多
Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is cruci...Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is crucial to design a high-performance material. Based on this, here, nitrogen-doped activated carbon(NAC) was prepared by pyrolyzing the blend of activated carbon powder(ACP) and melamine for the positive electrode of asymmetric CDI. By comparing the indicators changes such as conductivity, salt adsorption capacity, pH, and charge efficiency of the symmetrical ACP-ACP device to the asymmetric ACP-NAC device under different CDI cycles, as well as the changes of the electrochemical properties of anode and cathode materials after long-term operation, the reasons for the decline of the stability of the CDI performance were revealed. It was found that the carboxyl functional groups generated by the electro-oxidation of anode carbon materials make the anode zero-charge potential(E_(pzc)) shift positively,which results in the uneven distribution of potential windows of CDI units and affects the adsorption capacity. Furthermore, by understanding the electron density on C atoms surrounding the N atoms, we attribute the increased cyclic stability to the enhanced negativity of the charge of carbon atoms adjacent to quaternary-N and pyridinic-oxide-N.展开更多
Safe operation of electrochemical capacitors(supercapacitors)is hindered by the flammability of commercial organic electrolytes.Non-flammable Water-in-Salt(WIS)electrolytes are promising alternatives;however,they are ...Safe operation of electrochemical capacitors(supercapacitors)is hindered by the flammability of commercial organic electrolytes.Non-flammable Water-in-Salt(WIS)electrolytes are promising alternatives;however,they are plagued by the limited operation voltage window(typically≤2.3 V)and inherent corrosion of current collectors.Herein,a novel deep eutectic solvent(DES)-based electrolyte which uses formamide(FMD)as hydrogen-bond donor and sodium nitrate(NaNO_(3))as hydrogen-bond acceptor is demonstrated.The electrolyte exhibits the wide electrochemical stability window(3.14 V),high electrical conductivity(14.01 mScm^(-1)),good flame-retardance,anticorrosive property,and ultralow cost(7%of the commercial electrolyte and 2%of WIS).Raman spectroscopy and Density Functional Theory calculations reveal that the hydrogen bonds between the FMD molecules and NO_(3)^(-)ions are primarily responsible for the superior stability and conductivity.The developed NaNO_(3)/FMD-based coin cell supercapacitor is among the best-performing state-of-art DES and WIS devices,evidenced by the high voltage window(2.6 V),outstanding energy and power densities(22.77 Wh kg^(-1)at 630 W kg^(-1)and 17.37 kW kg^(-1)at 12.55 Wh kg^(-1)),ultralong cyclic stability(86%after 30000 cycles),and negligible current collector corrosion.The NaNO_(3)/FMD industry adoption potential is demonstrated by fabricating 100 F pouch cell supercapacitors using commercial aluminum current collectors.展开更多
The study of the influence of the cobalt content on the cyclic stability of superelasticity(SE)was carried out in quenched Ni_(44)Fe_(19)Ga_(27)Co_(10)and Ni_(39)Fe_(19)Ga_(27)Co_(15)(at.%)single crystals under compre...The study of the influence of the cobalt content on the cyclic stability of superelasticity(SE)was carried out in quenched Ni_(44)Fe_(19)Ga_(27)Co_(10)and Ni_(39)Fe_(19)Ga_(27)Co_(15)(at.%)single crystals under compression.It is shown that an increase in the cobalt content leads to embrittlement of the material and a decrease in the cyclic stability of SE.In Ni_(44)Fe_(19)Ga_(27)Co_(10)single crystals,during the first 20 loading/unloading cycles,the elastic energy relaxation occurs along with the formation of dislocations and residual martensite,which leads to a decrease in critical stress of martensite formation and in stress hysteresis.During the next 80 cycles,SE becomes more stable.Stabilization is accompanied by a slight change in the parameters.On the contrary,Ni_(39)Fe_(19)Ga_(27)Co_(15)single crystals are characterized by high-strength characteristics,which lead to high SE stability during the first 20 loading/unloading cycles.However,after 20 cycles,a strong degradation of the SE is observed through the formation of microcracks,which ultimately leads to the destruction of the sample.The results of work are replicable for cycling at different temperatures from all temperature ranges of superelasticity.展开更多
The undesired side reactions at electrode/electrolyte interface as well as the irreversible phase evolution during electrochemical cycling significantly affect the cyclic performances of nickel-rich NMCs electrode mat...The undesired side reactions at electrode/electrolyte interface as well as the irreversible phase evolution during electrochemical cycling significantly affect the cyclic performances of nickel-rich NMCs electrode materials.Electrolyte optimization is an effective approach to suppress such an adverse side reaction,thereby enhancing the electrochemical properties.Herein,a novel boron-based film forming additive,tris(2,2,2-trifluoroethyl)borate(TTFEB),has been introduced to regulate the interphasial chemistry of LiNi0.8Mn0.1Co0.1O2(NMC811)cathode to improve its long-term cyclability and rate properties.The results of multi-model diagnostic study reveal that formation lithium fluoride(LiF)-rich and boron(B)containing cathode electrolyte interphase(CEI)not only stabilizes cathode surface,but also prevents electrolyte decomposition.Moreover,homogenously distributed B containing species serves as a skeleton to form more uniform and denser CEI,reducing the interphasial resistance.Remarkably,the Li/NMC811 cell with the TTFEB additive delivers an exceptional cycling stability with a high-capacity retention of 72.8%after 350 electrochemical cycles at a 1 C current rate,which is significantly higher than that of the cell cycled in the conventional electrolyte(59.7%).These findings provide a feasible pathway for improving the electrochemical performance of Ni-rich NMCs cathode by regulating the interphasial chemistry.展开更多
Hydrogen energy has gained widespread recognition for its environmentally friendly nature,high energy density and abundant resources,making it a promising energy carrier for a sustainable and clean energy society.Howe...Hydrogen energy has gained widespread recognition for its environmentally friendly nature,high energy density and abundant resources,making it a promising energy carrier for a sustainable and clean energy society.However,safe and efficient hydrogen storage remains a significant challenge due to its inherent leakiness and flammability.To overcome these challenges,alloys featuring body-centered cubic(BCC)structures have emerged as compelling candidates for hydrogen storage,owing to their exceptional capacity to achieve high-density hydrogen storage up to 3.8 wt%at ambient temperatures.Nonetheless,their practical application faces limited dehydriding capacity,complex activation processes,high costs and poor cyclic stability.Various modification strategies have been explored to overcome these limitations,including lattice regulation,element substitution,rare earth doping and heat treatment.This progress report presents an overview of the previous advancements to enhance five crucial aspects(high-V,medium-V,low-V,V-free and high-entropy alloys)in composition design and hydrogen storage properties within BCC-structured alloys.Subsequently,an in-depth analysis is conducted to examine the relationship between crystal structures and hydrogen storage properties specific to BCC-structured alloys,covering aspects such as composition,crystal structure,hydrogen storage capacity,enthalpy and entropy.Furthermore,this review explores current challenges in this field and outlines directions for future research.These insights provide valuable guidance for the design of innovative and cost-effective hydrogen storage alloys.展开更多
This review details the advancement in the development of V–Ti-based hydrogen storage materials for using in metal hydride(MH)tanks to supply hydrogen to fuel cells at relatively ambient temperatures and pressures.V...This review details the advancement in the development of V–Ti-based hydrogen storage materials for using in metal hydride(MH)tanks to supply hydrogen to fuel cells at relatively ambient temperatures and pressures.V–Tibased solid solution alloys are excellent hydrogen storage materials among many metal hydrides due to their high reversible hydrogen storage capacity which is over 2 wt%at ambient temperature.The preparation methods,structure characteristics,improvement methods of hydrogen storage performance,and attenuation mechanism are systematically summarized and discussed.The relationships between hydrogen storage properties and alloy compositions as well as phase structures are discussed emphatically.For large-scale applications on MH tanks,it is necessary to develop low-cost and high-performance V–Ti-based solid solution alloys with high reversible hydrogen storage capacity,good cyclic durability,and excellent activation performance.展开更多
Efficient,safe,and economical hydrogen storage technology is vital for hydrogen’s broad use as an energy carrier,with V-based BCC alloys standing out for their high theoretical storage capacity.However,the high cost ...Efficient,safe,and economical hydrogen storage technology is vital for hydrogen’s broad use as an energy carrier,with V-based BCC alloys standing out for their high theoretical storage capacity.However,the high cost of V has restricted their practical application.In this work,a cost-effective Ti–Cr–(Fe V80)alloy was successfully synthesized through a pre-refinement process involving the addition of Y/Zr to the Fe V80 alloy.The resulting Ti_(27)Cr_(27)(Fe V80+Y)_(46)alloy exhibited an effective dehydriding capacity of 2.3 wt%,with a capacity retention rate of 97.2%after 200 cycles.Through the analysis of HSC Chemistry 6.0 software and backscattered electron(BSE),it has been discovered that the prerefinement process significantly reduces the presence of Al,Si,and O impurities,leading to improved compositional uniformity.After the re-refinement,the formation of the Ti–rich phases had been notably curbed.This,along with a marked decrease in the pressure–composition–temperature(PCT)curve’s slope factor from 1.58 to 0.36,results in enhanced hydriding capacity(from 3.2 wt%to 3.7 wt%),reversible dehydriding capacity(from 2.0 wt%to 2.3 wt%),and a remarkable increase in the capacity retention rate(from 75.8%to 97.2%).The kinetics and thermodynamic properties of the alloys were calculated using the Arrhenius and Van’t Hoff equations,providing insights into their performance characteristics.The mechanism behind the alloy’s improved cyclic stability has been elucidated through an analysis of lattice distortion and X-ray photoelectron spectroscopy(XPS).These findings open new routes for the development of cost-effective Fe V80-based hydrogen storage materials.展开更多
Separator modification is an effective approach to suppress dendrite growth to realize high-energy sodium metal batteries(SMBs)in practical applications,however,its success is mainly subject to surface modification.He...Separator modification is an effective approach to suppress dendrite growth to realize high-energy sodium metal batteries(SMBs)in practical applications,however,its success is mainly subject to surface modification.Herein,a separator with multifunctional layers composed of N-doped mesoporous hollow carbon spheres(HCS)as the inner layer and sodium fluoride(NaF)as the outer layer on commercial polypropylene separator(PP)is proposed(PP@HCS-NaF)to achieve stable cycling in SMB.At the molecular level,the inner HCS layer with a high content of pyrrolic-N induces the uniform Na^(+)flux as a potential Na^(+)redistributor for homogenous deposition,whereas its hollow mesoporous structure offers nanoporous buffers and ion channels to regulate Na^(+)ion distribution and uniform deposition.The outer layer(NaF)constructs the NaF-enriched robust solid electrolyte interphase layer,significantly lowering the Na^(+)ions diffusion barrier.Benefiting from these merits,higher electrochemical performances are achieved with multifunctional double-layered PP@HCS-NaF separators compared with single-layered separators(i.e.PP@HCS or PP@NaF)in SMBs.The Na‖Cu half-cell with PP@HCS-NaF offers stable cycling(280 cycles)with a high CE(99.6%),and Na‖Na symmetric cells demonstrate extended lifespans for over 6000 h at 1 mA cm^(-2)with a progressively stable overpotential of 9 mV.Remarkably,in Na‖NVP full-cells,the PP@HCS-NaF separator grants a stable capacity of~81 mA h g^(-1)after 3500 cycles at 1 C and an impressive rate capability performance(~70 mA h g^(-1)at 15 C).展开更多
The hydrogen storage mechanism of a single-phase nanocrystalline mechanically alloyed Al-Cr-Cu-Fe-Ni high-entropy alloy (HEA) was investigated in this study. The alloys were synthesized from the elemental powders usin...The hydrogen storage mechanism of a single-phase nanocrystalline mechanically alloyed Al-Cr-Cu-Fe-Ni high-entropy alloy (HEA) was investigated in this study. The alloys were synthesized from the elemental powders using high-energy attritor ball mill with hexane as the process control agent. The material obtained after 40 h of milling was nanocrystalline and exhibited body-centered cubic (BCC) phase with a lattice parameter of 0.289 nm. The nanocrystalline Al-Cr-Cu-Fe-Ni HEA demonstrated remarkable hydrogen stor-age capacity at 300℃ and 50 atm hydrogen pressure, absorbing 2.1wt% of hydrogen within 3 min and desorbing approximately 1.6wt% of hydrogen in 6 min. These rapid absorption and desorption processes highlighted the efficiency of the alloy for hydrogen uptake and release. Additionally, the alloy exhibited good cyclic stability, with a loss of only 0.2wt% of its hydrogen capacity across 25 cycles. The exceptional cycle stability and rapid kinetics of hydrogen storage and release make the nanocrystalline Al-Cr-Cu-Fe-Ni HEA a viable choice for hydrogen storage applications.展开更多
Rare earth-Mg-Ni-based superlattice structure alloys have garnered recognition as promising materials for hydrogen storage.However,their application is impeded by suboptimal cycling longevity.The novel AB_(4)-type all...Rare earth-Mg-Ni-based superlattice structure alloys have garnered recognition as promising materials for hydrogen storage.However,their application is impeded by suboptimal cycling longevity.The novel AB_(4)-type alloy emerges as an attractive candidate,distinguished by its good structure stability,high rate capability,and long-term durability.Herein,we designed an AB_(4)-type La_(0.6)0Sm_(0.22)Mg_(0.18)Ni_(4.09)Al_(0.09)Mn_(0.10)alloy that manifests superior electrochemical performance.The obtained AB_(4)-type single-phase alloy delivers a high discharge capacity of 375.2 mAh·g^(-1)and features outstanding discharge ability at high rates,maintaining 121 mAh·g^(-1)even at a discharge rate of 6C.The excellent high-rate discharge performance can be attributed to its fast charge transfer and hydrogen diffusion kinetics.Moreover,the AB_(4)-type alloy maintains a capacity retention of 84.5%after 200 cycles and retains 55.7%of its capacity retention even after 500 cycles.This work provides a good alternative to hydrogen storage alloy with high power and long cycling durability performance for nickel metal hydride batteries.展开更多
As a typical reactive composite hydrogen storage system,2LiBH_(4)-MgH_(2)holds an ultrahigh hydrogen storage capacity of 11.5 wt%.However,it suffers from sluggish hydrogen storage kinetics due to the difficult nucleat...As a typical reactive composite hydrogen storage system,2LiBH_(4)-MgH_(2)holds an ultrahigh hydrogen storage capacity of 11.5 wt%.However,it suffers from sluggish hydrogen storage kinetics due to the difficult nucleation of MgB_(2).Herein,amorphous VB_(2)nanoparticles with an average size of approximately 32 nm are synthesized to enhance the hydrogen storage performance of 2LiBH_(4)-MgH_(2)composite.VB_(2),sharing the same hexagonal structure with MgB_(2)with a d-value mismatch ratio of only 2.28%,could serve as effective nucleation sites for promoting the formation of MgB_(2).Theoretical calculations reveal that the introduction of VB_(2)significantly reduces the binding energies of B and Mg,facilitating in situ nucleation of MgB_(2).As a result,after the introduction of VB_(2)nanoparticles,complete hydrogen desorption of 9.23 wt%is achieved for 2LiBH_(4)-MgH_(2)within 2 h at 400℃,which is 4 times shorter than the time required for pure 2LiBH_(4)-MgH_(2),and no nucleation incubation period for hydrogen desorption is observed even at a low temperature of380℃.More importantly,a reversible capacity of9.3 wt%,corresponding to a capacity retention of 100%,could be preserved after 10 cycles of hydrogen storage,demonstrating stable reversible hydrogen storage performance.This study provides a novel technological pathway for improving the reversible hydrogen storage performance of composite metal hydrides and offers significant insights into the development of high-performance hydrogen storage materials.展开更多
The structures and electrochemical properties of the Ti1.4V0.6Ni ribbon before and after heat treatment are investigated systematically. The structure of the sample is characterized by X-ray powder diffraction analysi...The structures and electrochemical properties of the Ti1.4V0.6Ni ribbon before and after heat treatment are investigated systematically. The structure of the sample is characterized by X-ray powder diffraction analysis. Electrochemical properties including the discharge capacity, the cyclic stability and the high-rate discharge ability are tested. X-ray powder diffraction analysis shows that after heat treatment at 590 °C for 30 min, all samples mainly consist of the icosahedral quasicrystal phase (I-phase), Ti2Ni phase (FCC), V-based solid solution phase (BCC) and C14 Laves phase (hexagonal). Electrochemical measurements show that the maximum discharge capacity of the alloy electrode after heat treatment is 330.9 mA?h/g under the conditions that the discharge current density is 30 mA/g and the temperature is 30 °C. The result indicates that the cyclic stability and the high-rate discharge ability are all improved. In addition, the electrochemical kinetics of the alloy electrode is also studied by electrochemical impedance spectroscopy (EIS) and hydrogen diffusion coefficient (D).展开更多
Developing metal-organic framework(MOF)-based materials with good cyclic stability is the key to their practical application.Fluorinated organic compounds are usually highly chemically stability due to the high electr...Developing metal-organic framework(MOF)-based materials with good cyclic stability is the key to their practical application.Fluorinated organic compounds are usually highly chemically stability due to the high electronegativity of fluorine.Also,the pillared-layer structures based on coordination bonds have better structure and thermal stability than those based on hydrogen bonds.Herein,the fluorinated pillared-layer[Ni(2,3,4,5-tetrafluorobenzoic acid)(4,4-bipyridine)]nMOF([Ni(TFBA)(Bpy)]n)materials were constructed through a facile room-temperature solution reaction and used as electrode materials for supercapacitors.Surprisingly,the size/morphology of Ni(TFBA)(Bpy)nMOFs could be adjusted by varying the synthesis time.Benefting from the short ion diffusion length,unique pillar-layer structure,and strong intercomponent synergy of organic ligands,the Ni(TFBA)(Bpy)nMOF microrods showed a higher electrochemical energy storage capability than bulk MOFs.At the same time,compared to the non-fluorinated[Ni(benzoic acid)(Bpy)]nMOFs(31.5%capacitance decay),the fluorinated Ni(TFBA)(Bpy)n MOFs have a higher cycle stability with only 2.6%capacitance loss after 5000 cycles at 3 m A/cm^(2).展开更多
Graphite as a promising anode candidate of K-ion batteries(KIBs)has been increasingly studied currently,but corresponding rate performance and cycling stability are usually inferior to amorphous carbon materials.To pr...Graphite as a promising anode candidate of K-ion batteries(KIBs)has been increasingly studied currently,but corresponding rate performance and cycling stability are usually inferior to amorphous carbon materials.To protect the layer structure and further boost performance,tempura-like carbon/carbon nanocomposite of graphite@pitch-derived S-doped carbon(G@PSC)is designed and prepared by a facile and low-temperature modified molten salt method.This robust encapsulation structure makes their respective advantages complementary to each other,showing mutual promotion of electrochemical performances caused by synergy effect.As a result,the G@PSC electrode is applied in KIBs,delivering impressive rate capabilities(465,408,370,332,290,and 227 m A h g^(-1)at 0.05,0.2,0.5,1,2,and 5 A g^(-1))and ultralong cyclic stability(163 m A g^(-1)remaining even after 8000 cycles at 2 A g^(-1)).On basis of ex-situ studies,the sectionalized K-storage mechanism with adsorption(pseudocapacitance caused by S doping)-intercalation(pitch-derived carbon and graphite)pattern is revealed.Moreover,the exact insights into remarkable rate performances are taken by electrochemical kinetics tests and density functional theory calculation.In a word,this study adopts a facile method to synthesize high-performance carbon/carbon nanocomposite and is of practical significance for development of carbonaceous anode in KIBs.展开更多
To improve the cyclic stability of La-Mg-Ni system alloy, as-cast La0.75Mg0.25Ni3.5Co0.2 alloy was annealed at 1123, 1223, and 1323 K for 10 h in 0.3 MPa argon. The microstructure and electrochemical performance of di...To improve the cyclic stability of La-Mg-Ni system alloy, as-cast La0.75Mg0.25Ni3.5Co0.2 alloy was annealed at 1123, 1223, and 1323 K for 10 h in 0.3 MPa argon. The microstructure and electrochemical performance of different annealed alloys were investigated systematically by X-Ray Diffraction （XRD）, Scanning Electron Microscopy （SEM）, X-Ray Photoelectron Spectroscopy （XPS）, and electrochemical experiments. The results obtained by XRD and SEM showed that the as-cast and annealed （1123 K） alloys had multiphase structure containing LaNis, （La, Mg）2（Ni, Co）7 and few LaNi2 phases. When annealing temperatures approached 1223 and 1323 K, LaNi2 phase disappeared. The annealed alloys at 1223 and 1323 K were composed of LaNi5, （La, Mg）2（Ni, Co）7 and （La, Mg）（Ni, Co）3 phases. With increasing annealing temperature, the maximum discharge capacity of the alloy decreased monotonously, but the cyclic stability was improved owing to structure homogeneity and grain growth after annealing, as well as the enhancement of anti-oxidation/corrosion ability and the suppression of pulverization during cycling in KOH electrolyte.展开更多
Remarkable attention has been directed to Prussian blue(PB) and its analogues(PBA) as one of the most widely used metal-organic frameworks(MOFs) especially in the field of energy storage devices due to their fabulous ...Remarkable attention has been directed to Prussian blue(PB) and its analogues(PBA) as one of the most widely used metal-organic frameworks(MOFs) especially in the field of energy storage devices due to their fabulous features such as 3D open framework, high surface area, controllable distribution of pores and the low cost. Nevertheless, their depressed conductivity causes some insulation when being used as an electrode for supercapacitors leading to be restricted in further applications particularly the electronics. To the best of our knowledge, our review aimed primarily to give a total picture of the research that was done on utilizing PB and PBA for fabricating the electrodes of supercapacitor, studying their synthesis approaches in addition to the hybridization with other materials such as graphene, CNTs and conducting polymer. It also addresses the transformation of PB or PBA into other interesting nanostructures such as oxides, sulfides, and bicomponent of graphitic carbon nitride/metal oxides, as well. Furthermore,It exhibits various avenues for overcoming their disadvantages of bad cycle life, retention rate and not achieving the desired values of energy/power densities opening the door for enlarging the number of researches on their application as supercapacitors.展开更多
基金supported by the National Natural Science Foundation of China(U22A20120,52071135,51871090,U1804135,and 52301269)the Natural Science Foundation of Hebei Province for Innovation Groups Program(C2022203003)Fundamental Research Funds for the Universities of Henan Province(NSFRF220201).
文摘Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment of Ti_(3)C_(2)MXene under Ar/H_(2)S atmosphere to facilitate the hydrogen release and uptake from MgH_(2).The S-Ti_(3)C_(2)exhibited pleasant catalytic effect on the hydriding/dehydriding kinetics and cyclic stability of MgH_(2).The addition of 5 wt%S-Ti_(3)C_(2)into MgH_(2)resulted in a reduction of 114℃in the starting dehydriding temperature compared to pure MgH_(2).MgH_(2)+5 wt%S-Ti_(3)C_(2)sample could quickly release 6.6 wt%hydrogen in 17 min at 220℃,and 6.8 wt%H_(2)was absorbed in 25 min at 200℃.Cyclic testing revealed that MgH_(2)+5 wt%S-Ti_(3)C_(2)system achieved a reversible hydrogen capacity of 6.5 wt%.Characterization analysis demonstrated that Ti-species(Ti0,Ti^(2+),Ti-S,and Ti^(3+))as active species significantly lowered the dehydrogenation temperature and promoted the re-/dehydrogenation kinetics of MgH_(2),and sulfur doping can effectively improve the stability of Ti0 and Ti^(3+),contributing to the improvement of cyclic stability of MgH_(2).This study provides strategy for the construction of catalysts for hydrogen storage materials.
基金Project(2021H0028) supported by the Natural Scienceof Fujian Province,ChinaProject(JAT200455) supported by the Fujian Provincial Young and Middle-aged Teacher Education Project,ChinaProject(fma2023003) supported by the Open Fund of Fujian Provincial Key Laboratory of Functional Materials and Applications,China。
文摘Rich-nickel layered ternary NCM811 has been widely used in the field of electric vehicles ascribed to its high theoretical specific capacity.However,poor cycling stability and rate-performance hindered its further development.Herein,different amounts of nitrogen-doped carbon were wrapped on the surface of NCM811 via a facile rheological phase method by regulating the amount of dopamine hydrochloride.The effects of the coating amounts on the structure and electrochemical performance are investigated.The DFT calculation,XRD,SEM and XPS reveal that an appropriate amount of nitrogen-doped carbon coating could uniformly form a protective layer on the NCM811 surface and the introduced N could anchor Ni atoms to inhibit the Li^(+)/Ni^(2+)mixing,but excessive amount would reduce Ni^(3+)to Ni^(2+)so as to conversely aggravate Li^(+)/Ni^(2+)mixing.Among the samples,the NCM811-CN0.75 sample exhibits the most excellent electrochemical performance,delivering a high-rate capacity of 151.6 mA·h/g at 10C,and long-term cyclability with 82.2%capacity retention after 300 cycles at 5C,exhibiting remarkable rate-performance and cyclability.
基金National Natral Science Foundation of China(Grant No.59679018)
文摘The accumulative shear deformation of soft clays under cyclic loads is considered as pseudo-static creep. A pseudo-static elasto-plastic cyclic creep model is developed based on the visco-elasto-plastic theory. The parameters in the model are determined by cyclic triaxial soil tests. A method for analyzing the stability of offshore soft foundation under wave loads is given by combining the model with pseudo-static creep analysis. An example is analyzed by the method. The results show that the horizontal and vertical stability of foundations under wave loads can be analyzed by it and the analytical results are qualitatively consistent with the observed failure modes of shallow foundations.
基金supported by the National Natural Science Foundation of China(Grant No.21872058)。
文摘Lithium-metal battery based on Ni-rich cathode provides high energy density but presents poor cyclic stability due to the unstable electrode/electrolyte interfaces on both cathode and anode.In this work,we report a new strategy to address this issue.It is found that the cyclic stability of Ni-rich/Li battery can be significantly improved by using succinic anhydride(SA) as an electrolyte additive.Specifically,the capacity retention of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)/Li cell is improved from 14% to 83% after 200cycles at 1 C between 3.0 and 4.35 V by applying 5% SA.The underlying mechanism of SA contribution is understood by comparing the effects of malic anhydride(MA) and citraconic anhydride(CA), both of which share a similar molecular structure to SA but show different effects.On anode side,SA can but MA and CA cannot form a protective solid electrolyte interphase(SEI) on Li anode.On cathode side,three anhydrides can suppress the formation of hydrogen fluoride from electrolyte oxidation decomposition,but SA behaves best.Typically,MA shows adverse effects on the interface stability of Li anode and NCM811 cathode,which originates from its high acidity.Though the acidity of MA can be mitigated by substituting a methyl for one H atom at its C=C bond,the substituent CA cannot compete with SA in cyclic stability improvement of the cell,because the SEI resulting from CA is not as robust as that from SA,which is related to the binding energy of the SEI components.This understanding reveals the importance of the electrolyte acidity on the Ni-rich cathode and the robustness of the SEI on Li anode,which is helpful for rationally designing new electrolyte additives to further improve the cyclic stability of high-energydensity Ni-rich/Li batteries.
文摘Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is crucial to design a high-performance material. Based on this, here, nitrogen-doped activated carbon(NAC) was prepared by pyrolyzing the blend of activated carbon powder(ACP) and melamine for the positive electrode of asymmetric CDI. By comparing the indicators changes such as conductivity, salt adsorption capacity, pH, and charge efficiency of the symmetrical ACP-ACP device to the asymmetric ACP-NAC device under different CDI cycles, as well as the changes of the electrochemical properties of anode and cathode materials after long-term operation, the reasons for the decline of the stability of the CDI performance were revealed. It was found that the carboxyl functional groups generated by the electro-oxidation of anode carbon materials make the anode zero-charge potential(E_(pzc)) shift positively,which results in the uneven distribution of potential windows of CDI units and affects the adsorption capacity. Furthermore, by understanding the electron density on C atoms surrounding the N atoms, we attribute the increased cyclic stability to the enhanced negativity of the charge of carbon atoms adjacent to quaternary-N and pyridinic-oxide-N.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(No.LY23E060004)Royal Society Newton Advanced Fellowship(No.52061130218)
文摘Safe operation of electrochemical capacitors(supercapacitors)is hindered by the flammability of commercial organic electrolytes.Non-flammable Water-in-Salt(WIS)electrolytes are promising alternatives;however,they are plagued by the limited operation voltage window(typically≤2.3 V)and inherent corrosion of current collectors.Herein,a novel deep eutectic solvent(DES)-based electrolyte which uses formamide(FMD)as hydrogen-bond donor and sodium nitrate(NaNO_(3))as hydrogen-bond acceptor is demonstrated.The electrolyte exhibits the wide electrochemical stability window(3.14 V),high electrical conductivity(14.01 mScm^(-1)),good flame-retardance,anticorrosive property,and ultralow cost(7%of the commercial electrolyte and 2%of WIS).Raman spectroscopy and Density Functional Theory calculations reveal that the hydrogen bonds between the FMD molecules and NO_(3)^(-)ions are primarily responsible for the superior stability and conductivity.The developed NaNO_(3)/FMD-based coin cell supercapacitor is among the best-performing state-of-art DES and WIS devices,evidenced by the high voltage window(2.6 V),outstanding energy and power densities(22.77 Wh kg^(-1)at 630 W kg^(-1)and 17.37 kW kg^(-1)at 12.55 Wh kg^(-1)),ultralong cyclic stability(86%after 30000 cycles),and negligible current collector corrosion.The NaNO_(3)/FMD industry adoption potential is demonstrated by fabricating 100 F pouch cell supercapacitors using commercial aluminum current collectors.
基金financially supported by the Russian Science Foundation(No.21-19-00287).
文摘The study of the influence of the cobalt content on the cyclic stability of superelasticity(SE)was carried out in quenched Ni_(44)Fe_(19)Ga_(27)Co_(10)and Ni_(39)Fe_(19)Ga_(27)Co_(15)(at.%)single crystals under compression.It is shown that an increase in the cobalt content leads to embrittlement of the material and a decrease in the cyclic stability of SE.In Ni_(44)Fe_(19)Ga_(27)Co_(10)single crystals,during the first 20 loading/unloading cycles,the elastic energy relaxation occurs along with the formation of dislocations and residual martensite,which leads to a decrease in critical stress of martensite formation and in stress hysteresis.During the next 80 cycles,SE becomes more stable.Stabilization is accompanied by a slight change in the parameters.On the contrary,Ni_(39)Fe_(19)Ga_(27)Co_(15)single crystals are characterized by high-strength characteristics,which lead to high SE stability during the first 20 loading/unloading cycles.However,after 20 cycles,a strong degradation of the SE is observed through the formation of microcracks,which ultimately leads to the destruction of the sample.The results of work are replicable for cycling at different temperatures from all temperature ranges of superelasticity.
基金supported by the National Natural Science Foundation of China(Grant No.22209106).
文摘The undesired side reactions at electrode/electrolyte interface as well as the irreversible phase evolution during electrochemical cycling significantly affect the cyclic performances of nickel-rich NMCs electrode materials.Electrolyte optimization is an effective approach to suppress such an adverse side reaction,thereby enhancing the electrochemical properties.Herein,a novel boron-based film forming additive,tris(2,2,2-trifluoroethyl)borate(TTFEB),has been introduced to regulate the interphasial chemistry of LiNi0.8Mn0.1Co0.1O2(NMC811)cathode to improve its long-term cyclability and rate properties.The results of multi-model diagnostic study reveal that formation lithium fluoride(LiF)-rich and boron(B)containing cathode electrolyte interphase(CEI)not only stabilizes cathode surface,but also prevents electrolyte decomposition.Moreover,homogenously distributed B containing species serves as a skeleton to form more uniform and denser CEI,reducing the interphasial resistance.Remarkably,the Li/NMC811 cell with the TTFEB additive delivers an exceptional cycling stability with a high-capacity retention of 72.8%after 350 electrochemical cycles at a 1 C current rate,which is significantly higher than that of the cell cycled in the conventional electrolyte(59.7%).These findings provide a feasible pathway for improving the electrochemical performance of Ni-rich NMCs cathode by regulating the interphasial chemistry.
基金supported by the National Key R&D Program of China(No.2022YFB3504700)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0400304)the Research Fund of Key Laboratory of Rare Earths,Chinese Academy of Sciences(No.E32PF00116).
文摘Hydrogen energy has gained widespread recognition for its environmentally friendly nature,high energy density and abundant resources,making it a promising energy carrier for a sustainable and clean energy society.However,safe and efficient hydrogen storage remains a significant challenge due to its inherent leakiness and flammability.To overcome these challenges,alloys featuring body-centered cubic(BCC)structures have emerged as compelling candidates for hydrogen storage,owing to their exceptional capacity to achieve high-density hydrogen storage up to 3.8 wt%at ambient temperatures.Nonetheless,their practical application faces limited dehydriding capacity,complex activation processes,high costs and poor cyclic stability.Various modification strategies have been explored to overcome these limitations,including lattice regulation,element substitution,rare earth doping and heat treatment.This progress report presents an overview of the previous advancements to enhance five crucial aspects(high-V,medium-V,low-V,V-free and high-entropy alloys)in composition design and hydrogen storage properties within BCC-structured alloys.Subsequently,an in-depth analysis is conducted to examine the relationship between crystal structures and hydrogen storage properties specific to BCC-structured alloys,covering aspects such as composition,crystal structure,hydrogen storage capacity,enthalpy and entropy.Furthermore,this review explores current challenges in this field and outlines directions for future research.These insights provide valuable guidance for the design of innovative and cost-effective hydrogen storage alloys.
基金supported by the Key-Area Research and Development Program of Guangdong Province(No.2023B0909060001)the National Natural Science Foundation of China(No.52271213)。
文摘This review details the advancement in the development of V–Ti-based hydrogen storage materials for using in metal hydride(MH)tanks to supply hydrogen to fuel cells at relatively ambient temperatures and pressures.V–Tibased solid solution alloys are excellent hydrogen storage materials among many metal hydrides due to their high reversible hydrogen storage capacity which is over 2 wt%at ambient temperature.The preparation methods,structure characteristics,improvement methods of hydrogen storage performance,and attenuation mechanism are systematically summarized and discussed.The relationships between hydrogen storage properties and alloy compositions as well as phase structures are discussed emphatically.For large-scale applications on MH tanks,it is necessary to develop low-cost and high-performance V–Ti-based solid solution alloys with high reversible hydrogen storage capacity,good cyclic durability,and excellent activation performance.
基金financially supported by the National Key R&D Program of China(No.2022YFB3504700)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0400304)the Research Fund of Key Laboratory of Rare Earth,Chinese Academy of Sciences(No.E32PF00116)。
文摘Efficient,safe,and economical hydrogen storage technology is vital for hydrogen’s broad use as an energy carrier,with V-based BCC alloys standing out for their high theoretical storage capacity.However,the high cost of V has restricted their practical application.In this work,a cost-effective Ti–Cr–(Fe V80)alloy was successfully synthesized through a pre-refinement process involving the addition of Y/Zr to the Fe V80 alloy.The resulting Ti_(27)Cr_(27)(Fe V80+Y)_(46)alloy exhibited an effective dehydriding capacity of 2.3 wt%,with a capacity retention rate of 97.2%after 200 cycles.Through the analysis of HSC Chemistry 6.0 software and backscattered electron(BSE),it has been discovered that the prerefinement process significantly reduces the presence of Al,Si,and O impurities,leading to improved compositional uniformity.After the re-refinement,the formation of the Ti–rich phases had been notably curbed.This,along with a marked decrease in the pressure–composition–temperature(PCT)curve’s slope factor from 1.58 to 0.36,results in enhanced hydriding capacity(from 3.2 wt%to 3.7 wt%),reversible dehydriding capacity(from 2.0 wt%to 2.3 wt%),and a remarkable increase in the capacity retention rate(from 75.8%to 97.2%).The kinetics and thermodynamic properties of the alloys were calculated using the Arrhenius and Van’t Hoff equations,providing insights into their performance characteristics.The mechanism behind the alloy’s improved cyclic stability has been elucidated through an analysis of lattice distortion and X-ray photoelectron spectroscopy(XPS).These findings open new routes for the development of cost-effective Fe V80-based hydrogen storage materials.
基金supported by the National Natural Science Foundation of China(Grant Number 22350410379)Zhejiang Provincial Natural Science Foundation of China(LZ23B030003)+1 种基金the Fundamental Research Funds for the Central Universities(226-202400075)Ten Thousand Talent Program of Zhejiang Province.
文摘Separator modification is an effective approach to suppress dendrite growth to realize high-energy sodium metal batteries(SMBs)in practical applications,however,its success is mainly subject to surface modification.Herein,a separator with multifunctional layers composed of N-doped mesoporous hollow carbon spheres(HCS)as the inner layer and sodium fluoride(NaF)as the outer layer on commercial polypropylene separator(PP)is proposed(PP@HCS-NaF)to achieve stable cycling in SMB.At the molecular level,the inner HCS layer with a high content of pyrrolic-N induces the uniform Na^(+)flux as a potential Na^(+)redistributor for homogenous deposition,whereas its hollow mesoporous structure offers nanoporous buffers and ion channels to regulate Na^(+)ion distribution and uniform deposition.The outer layer(NaF)constructs the NaF-enriched robust solid electrolyte interphase layer,significantly lowering the Na^(+)ions diffusion barrier.Benefiting from these merits,higher electrochemical performances are achieved with multifunctional double-layered PP@HCS-NaF separators compared with single-layered separators(i.e.PP@HCS or PP@NaF)in SMBs.The Na‖Cu half-cell with PP@HCS-NaF offers stable cycling(280 cycles)with a high CE(99.6%),and Na‖Na symmetric cells demonstrate extended lifespans for over 6000 h at 1 mA cm^(-2)with a progressively stable overpotential of 9 mV.Remarkably,in Na‖NVP full-cells,the PP@HCS-NaF separator grants a stable capacity of~81 mA h g^(-1)after 3500 cycles at 1 C and an impressive rate capability performance(~70 mA h g^(-1)at 15 C).
基金financial support from UGC, India, via the UGC Non-NET Fellowshipthe Council of Science and Technology, Uttar Pradesh, India (CST/d-833, Project Id 4057) for financial support
文摘The hydrogen storage mechanism of a single-phase nanocrystalline mechanically alloyed Al-Cr-Cu-Fe-Ni high-entropy alloy (HEA) was investigated in this study. The alloys were synthesized from the elemental powders using high-energy attritor ball mill with hexane as the process control agent. The material obtained after 40 h of milling was nanocrystalline and exhibited body-centered cubic (BCC) phase with a lattice parameter of 0.289 nm. The nanocrystalline Al-Cr-Cu-Fe-Ni HEA demonstrated remarkable hydrogen stor-age capacity at 300℃ and 50 atm hydrogen pressure, absorbing 2.1wt% of hydrogen within 3 min and desorbing approximately 1.6wt% of hydrogen in 6 min. These rapid absorption and desorption processes highlighted the efficiency of the alloy for hydrogen uptake and release. Additionally, the alloy exhibited good cyclic stability, with a loss of only 0.2wt% of its hydrogen capacity across 25 cycles. The exceptional cycle stability and rapid kinetics of hydrogen storage and release make the nanocrystalline Al-Cr-Cu-Fe-Ni HEA a viable choice for hydrogen storage applications.
基金supported by the Natural Science Foundation of China(Nos.52201282 and 52371239)the Natural Science Foundation of Hebei Province(No.E2024203037)+1 种基金the Basic Innovation Research Project in Yanshan University(2022LGZD004)Baotou Science and Technology Planning Project(No.XM2022BT09).
文摘Rare earth-Mg-Ni-based superlattice structure alloys have garnered recognition as promising materials for hydrogen storage.However,their application is impeded by suboptimal cycling longevity.The novel AB_(4)-type alloy emerges as an attractive candidate,distinguished by its good structure stability,high rate capability,and long-term durability.Herein,we designed an AB_(4)-type La_(0.6)0Sm_(0.22)Mg_(0.18)Ni_(4.09)Al_(0.09)Mn_(0.10)alloy that manifests superior electrochemical performance.The obtained AB_(4)-type single-phase alloy delivers a high discharge capacity of 375.2 mAh·g^(-1)and features outstanding discharge ability at high rates,maintaining 121 mAh·g^(-1)even at a discharge rate of 6C.The excellent high-rate discharge performance can be attributed to its fast charge transfer and hydrogen diffusion kinetics.Moreover,the AB_(4)-type alloy maintains a capacity retention of 84.5%after 200 cycles and retains 55.7%of its capacity retention even after 500 cycles.This work provides a good alternative to hydrogen storage alloy with high power and long cycling durability performance for nickel metal hydride batteries.
基金financially supported by the National Key R&D Program of China(No.2021YFB 3802400)the National Natural Science Foundation of China(Nos.U2130208,22279020 and 52301264)the Science and Technology Commission of Shanghai Municipality(Nos.23ZR1406500 and 22ZR1406500)
文摘As a typical reactive composite hydrogen storage system,2LiBH_(4)-MgH_(2)holds an ultrahigh hydrogen storage capacity of 11.5 wt%.However,it suffers from sluggish hydrogen storage kinetics due to the difficult nucleation of MgB_(2).Herein,amorphous VB_(2)nanoparticles with an average size of approximately 32 nm are synthesized to enhance the hydrogen storage performance of 2LiBH_(4)-MgH_(2)composite.VB_(2),sharing the same hexagonal structure with MgB_(2)with a d-value mismatch ratio of only 2.28%,could serve as effective nucleation sites for promoting the formation of MgB_(2).Theoretical calculations reveal that the introduction of VB_(2)significantly reduces the binding energies of B and Mg,facilitating in situ nucleation of MgB_(2).As a result,after the introduction of VB_(2)nanoparticles,complete hydrogen desorption of 9.23 wt%is achieved for 2LiBH_(4)-MgH_(2)within 2 h at 400℃,which is 4 times shorter than the time required for pure 2LiBH_(4)-MgH_(2),and no nucleation incubation period for hydrogen desorption is observed even at a low temperature of380℃.More importantly,a reversible capacity of9.3 wt%,corresponding to a capacity retention of 100%,could be preserved after 10 cycles of hydrogen storage,demonstrating stable reversible hydrogen storage performance.This study provides a novel technological pathway for improving the reversible hydrogen storage performance of composite metal hydrides and offers significant insights into the development of high-performance hydrogen storage materials.
基金Project (20112216120001) supported by the Doctoral Program of Tertiary Education of the Ministry of Education of ChinaProject(21215141) supported by the Natural Science Foundation of Jilin Province, China+3 种基金Project (20921002) supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of ChinaProjects (21073179, 61106050) supported by the National Natural Science Foundation of ChinaProject (BE2012047) supported by Scientific and Technological Supporting Program of Jiangsu Province of China and GS Yuasa Corporation of JapanProject (11KZ38) supported by and Scientific and Technological Pillar Project of Changchun, China
文摘The structures and electrochemical properties of the Ti1.4V0.6Ni ribbon before and after heat treatment are investigated systematically. The structure of the sample is characterized by X-ray powder diffraction analysis. Electrochemical properties including the discharge capacity, the cyclic stability and the high-rate discharge ability are tested. X-ray powder diffraction analysis shows that after heat treatment at 590 °C for 30 min, all samples mainly consist of the icosahedral quasicrystal phase (I-phase), Ti2Ni phase (FCC), V-based solid solution phase (BCC) and C14 Laves phase (hexagonal). Electrochemical measurements show that the maximum discharge capacity of the alloy electrode after heat treatment is 330.9 mA?h/g under the conditions that the discharge current density is 30 mA/g and the temperature is 30 °C. The result indicates that the cyclic stability and the high-rate discharge ability are all improved. In addition, the electrochemical kinetics of the alloy electrode is also studied by electrochemical impedance spectroscopy (EIS) and hydrogen diffusion coefficient (D).
基金supported by the National Natural Science Foundation of China(No.U1904215)the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP)+1 种基金Natural Science Foundation of Jiangsu Province(No.BK20200044)Excellent doctoral dissertation of Yangzhou University and the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX19_2099)。
文摘Developing metal-organic framework(MOF)-based materials with good cyclic stability is the key to their practical application.Fluorinated organic compounds are usually highly chemically stability due to the high electronegativity of fluorine.Also,the pillared-layer structures based on coordination bonds have better structure and thermal stability than those based on hydrogen bonds.Herein,the fluorinated pillared-layer[Ni(2,3,4,5-tetrafluorobenzoic acid)(4,4-bipyridine)]nMOF([Ni(TFBA)(Bpy)]n)materials were constructed through a facile room-temperature solution reaction and used as electrode materials for supercapacitors.Surprisingly,the size/morphology of Ni(TFBA)(Bpy)nMOFs could be adjusted by varying the synthesis time.Benefting from the short ion diffusion length,unique pillar-layer structure,and strong intercomponent synergy of organic ligands,the Ni(TFBA)(Bpy)nMOF microrods showed a higher electrochemical energy storage capability than bulk MOFs.At the same time,compared to the non-fluorinated[Ni(benzoic acid)(Bpy)]nMOFs(31.5%capacitance decay),the fluorinated Ni(TFBA)(Bpy)n MOFs have a higher cycle stability with only 2.6%capacitance loss after 5000 cycles at 3 m A/cm^(2).
基金the financial support from the National Natural Science Foundation of China(No.91963118)the 111 Project(No.B13013)supported by the Open Project Program of Key Laboratory of Preparation and Application of Environmental Friendly Materials(Jilin Normal University),Ministry of Education,China(No.2020004)。
文摘Graphite as a promising anode candidate of K-ion batteries(KIBs)has been increasingly studied currently,but corresponding rate performance and cycling stability are usually inferior to amorphous carbon materials.To protect the layer structure and further boost performance,tempura-like carbon/carbon nanocomposite of graphite@pitch-derived S-doped carbon(G@PSC)is designed and prepared by a facile and low-temperature modified molten salt method.This robust encapsulation structure makes their respective advantages complementary to each other,showing mutual promotion of electrochemical performances caused by synergy effect.As a result,the G@PSC electrode is applied in KIBs,delivering impressive rate capabilities(465,408,370,332,290,and 227 m A h g^(-1)at 0.05,0.2,0.5,1,2,and 5 A g^(-1))and ultralong cyclic stability(163 m A g^(-1)remaining even after 8000 cycles at 2 A g^(-1)).On basis of ex-situ studies,the sectionalized K-storage mechanism with adsorption(pseudocapacitance caused by S doping)-intercalation(pitch-derived carbon and graphite)pattern is revealed.Moreover,the exact insights into remarkable rate performances are taken by electrochemical kinetics tests and density functional theory calculation.In a word,this study adopts a facile method to synthesize high-performance carbon/carbon nanocomposite and is of practical significance for development of carbonaceous anode in KIBs.
基金Project supported by the National Natural Science Foundation of China(50642033 50701011)+1 种基金Key Technologies R&D Program of Inner Mongolia, China (20050205)Natural Science Foundation of Inner Mongolia, China (200711020703)
文摘To improve the cyclic stability of La-Mg-Ni system alloy, as-cast La0.75Mg0.25Ni3.5Co0.2 alloy was annealed at 1123, 1223, and 1323 K for 10 h in 0.3 MPa argon. The microstructure and electrochemical performance of different annealed alloys were investigated systematically by X-Ray Diffraction （XRD）, Scanning Electron Microscopy （SEM）, X-Ray Photoelectron Spectroscopy （XPS）, and electrochemical experiments. The results obtained by XRD and SEM showed that the as-cast and annealed （1123 K） alloys had multiphase structure containing LaNis, （La, Mg）2（Ni, Co）7 and few LaNi2 phases. When annealing temperatures approached 1223 and 1323 K, LaNi2 phase disappeared. The annealed alloys at 1223 and 1323 K were composed of LaNi5, （La, Mg）2（Ni, Co）7 and （La, Mg）（Ni, Co）3 phases. With increasing annealing temperature, the maximum discharge capacity of the alloy decreased monotonously, but the cyclic stability was improved owing to structure homogeneity and grain growth after annealing, as well as the enhancement of anti-oxidation/corrosion ability and the suppression of pulverization during cycling in KOH electrolyte.
基金the National Research Foundation of Korea Grant funded by the Korean Government(MEST)(NRF2019R1I1A3A01063833)Korea Environment Industry&Technology Institute(KEITI)through Technology Development Program for Environmental Industry Advancement funded by Korea Ministry of Environment(MOE)(RE201805141)+1 种基金the National Research Foundation(NRF)of Korea(NRF-2019R1A2C1006677)Hannam University research fund in 2019。
文摘Remarkable attention has been directed to Prussian blue(PB) and its analogues(PBA) as one of the most widely used metal-organic frameworks(MOFs) especially in the field of energy storage devices due to their fabulous features such as 3D open framework, high surface area, controllable distribution of pores and the low cost. Nevertheless, their depressed conductivity causes some insulation when being used as an electrode for supercapacitors leading to be restricted in further applications particularly the electronics. To the best of our knowledge, our review aimed primarily to give a total picture of the research that was done on utilizing PB and PBA for fabricating the electrodes of supercapacitor, studying their synthesis approaches in addition to the hybridization with other materials such as graphene, CNTs and conducting polymer. It also addresses the transformation of PB or PBA into other interesting nanostructures such as oxides, sulfides, and bicomponent of graphitic carbon nitride/metal oxides, as well. Furthermore,It exhibits various avenues for overcoming their disadvantages of bad cycle life, retention rate and not achieving the desired values of energy/power densities opening the door for enlarging the number of researches on their application as supercapacitors.
