A new intercalation-type anode material is reported herein to improve the lithium storage kinetics for high-rate lithium ion capacitors.The crystal structure of orthorhombic NaNbO3 indicates two possible tunnels for l...A new intercalation-type anode material is reported herein to improve the lithium storage kinetics for high-rate lithium ion capacitors.The crystal structure of orthorhombic NaNbO3 indicates two possible tunnels for lithium ions insertion into NaNbO3 host along the<101>and<141>directions.Moreover,in situ XRD is conducted to investigate the lithium storage mechanism and structural evolution of the NaNb O_(3) anode,demonstrating its intercalation behavior through(101)and(141)planes.Furthermore,the rGO nanosheets are introduced to facilitate the charge transfer,which also effectively prevent the aggregation of NaNbO3 nanocubes.As expected,the NaNbO_(3)/rGO nanocomposites possess remarkable reversible capacity(465 mA h g^(-1) at 0.1 A g^(-1)),superior rate capability(325 mA h g^(-1) at 1.0 A g^(-1))and cycling stability,attributed to their synergistic effect and high Li+diffusion coefficient DLi[D(NaNbO_(3)/rGO)/D(NaNbO_(3))≈31.54].Remarkably,the NaNbO3/rGO-based LIC delivers a high energy density of 166.7 W h kg^(-1) at 112.4 W kg^(-1) and remains 24.1 W h kg^(-1) at an ultrahigh power density of26621.2 W kg^(-1),with an outstanding cycling durability(90%retention over 3000 cycles at 1.0 A g^(-1)).This study provides new insights on novel intercalation-type anode material to enrich the materials system of LICs.展开更多
Bismuth (Bi) has indeed inspired great interests in lithium-ion batteries (LIBs) due to the high capacity,but was still limited by the low electrical conductivity and large volume variation.Herein,a composite material...Bismuth (Bi) has indeed inspired great interests in lithium-ion batteries (LIBs) due to the high capacity,but was still limited by the low electrical conductivity and large volume variation.Herein,a composite material based on Bi nanoparticles in situ encapsulated by carbon film (Bi@CF) is prepared successfully through a facile metal–organic framework (MOF)-engaged approach.As anode materials for LIBs,the Bi@CF composites achieved high reversible capacities of 705 and 538 mAh g^(-1)at 0.2 and 0.5 A g^(-1) after200 cycles,and long cycling performance with a stable capacity of 306 mAh g^(-1)at 1.0 A g^(-1) even after 900 cycles.In situ X-ray diffraction (XRD) measurements clearly revealed the conversion between Bi and Li_(3)Bi during the alloying/dealloying process,confirming the good electrochemical reversibility of Bi@CF for Li-storage.The reaction kinetics of this Bi@CF composite was further studied by galvanostatic intermittent titration technique (GITT).This work may provide an inspiration for the elaborate design and facile preparation of alloy-type anode materials for high-performance rechargeable batteries.展开更多
The anion storage behavior of graphite positive electrode in a dual-ion battery is closely related to the solvation of anion in the corresponding electrolyte solution.The classical electrolyte solutions of Li BF_(4)^(...The anion storage behavior of graphite positive electrode in a dual-ion battery is closely related to the solvation of anion in the corresponding electrolyte solution.The classical electrolyte solutions of Li BF_(4)^(-)sulfolane(SL)have long been recognized in the community of lithium batteries and still appear promising in dual-ion batteries.Nevertheless,the solvation of BF_(4)^(-)by SL has seldom been addressed before.In this study,the solvation states of SL-BF_(4)^(-)are adjusted by varying LiBF_(4)concentration or introducing auxiliary salts of LiPF_6or SBPBF_(4)(SBP:spiro-(1,1')-bipyrrolidinium)in the electrolyte solutions of Li/graphite dualion cells.The electrochemical storage processes of SL-BF_(4)^(-)anions in graphite electrodes are investigated through in situ X-ray diffraction measurements.Two kinds of graphite intercalation compounds(GICs)with contrastive intercalation gallery heights(IGHs)have been discovered,which are ascribed to the storage of different kinds of SL-BF_(4)^(-)anions in graphite electrode.The interactions between ions and SL in the electrolyte solutions are characterized by Fourier transform infrared spectroscopy and then correlated with the performance of Li/graphite cells.展开更多
Intercalating Nb-based oxides are promising anode compounds for lithiumion batteries since they have both good safety and large capacities.However,the research in this field is still limited.Here,Mo_(3)Nb_(14)O_(44)wi...Intercalating Nb-based oxides are promising anode compounds for lithiumion batteries since they have both good safety and large capacities.However,the research in this field is still limited.Here,Mo_(3)Nb_(14)O_(44)with a large theoretical capacity of 398 mAh g^(–1)(Mo^(64)←→Mo^(4+)and Nb^(5+)←→Nb^(3+))is exploited as a new Nb-based oxide anode compound,and Mo_(3)Nb_(14)O_(44)micron-sized particles(Mo_(3)Nb_(14)O_(44)-M)and Mo3Nb14O44 nanowires(Mo_(3)Nb_(14)O_(44)-N)are demonstrated.Mo3Nb14O44 owns a tetragonal shear ReO_(3)crystal structure(high-symmetric 14 space group)constructed by 4×4×∞(Mo,Nb)O_(6)octahedron blocks linked by Mo O4 tetrahedra,forming an A–B–A layered structure with a large interlayer spacing.This interesting structure allows fast Li+storage within the interlayers and significant intercalation-pseudocapacitive behavior,leading to the high rate performance of Mo_(3)Nb_(14)O_(44)-M/Mo_(3)Nb_(14)O_(44)-N with a large 10 C versus 0.1 C capacity retention percentage of 38.1/54.2%.Mo_(3)Nb_(14)O_(44)-M/Mo_(3)Nb_(14)O_(44)-N further exhibits a safe operating potential of 1.72/1.68 V,large reversible capacity of 323/321 m Ah g^(–1)at 0.1 C,high initial coulombic efficiency of 92.2/90.0%,and good cycling stability with 71.8/75.8%capacity retention after 1000 cycles at10 C.Additionally,a Li Mn_(2)O_(4)/Mo_(3)Nb_(14)O_(44)-N full cell also performs well.Therefore,Mo_(3)Nb_(14)O_(44)holds great promise as a fast-charging,safe,largecapacity,high-efficient,and long-life Li^(+)anode container.展开更多
Changes of a 65Ni25Cu10A1203 catalyst consisting of Ni-enriched and Cu-enriched alloys were investigated in the bulk and on the surface during the growth of nitrogen-doped carbon nanofibers （N-CNFs） by decomposition...Changes of a 65Ni25Cu10A1203 catalyst consisting of Ni-enriched and Cu-enriched alloys were investigated in the bulk and on the surface during the growth of nitrogen-doped carbon nanofibers （N-CNFs） by decomposition of a 50%C2I-I4/50%NH3 mixture using in situ X-ray diffraction （XRD） analysis, ex situ X-ray photoelectron spectroscopy （XPS） and transmission electron microscopy （TEM） techniques. It was shown that N-CNF growth at 450-650 ℃is accompanied by dissolution of carbon and nitrogen in the Ni-enriched alloy, whereas Cu-enriched alloy remains inactive. A correlation between nickel and copper surface concentrations and properties of N-CNFs in relation to the nitrogen content was found. It was demonstrated that phase composition of the catalyst during N-CNF growth determines the type of N-CNFs structure.展开更多
The negative thermal expansion(NTE) phenomenon is of great significance in fabricating zero thermal expansion(ZTE) materials to avoid thermal shock during heating and cooling. NTE is observed in limited groups of mate...The negative thermal expansion(NTE) phenomenon is of great significance in fabricating zero thermal expansion(ZTE) materials to avoid thermal shock during heating and cooling. NTE is observed in limited groups of materials, e.g., metal cyanides, oxometallates, and metalorganic frameworks, but has not been reported in the family of metal hydrides. Herein, a colossal and continuous negative thermal expansion is firstly developed in the low-temperature phases of LT1-and LT2-Mg_(2)NiH_(4) between 488 K and 733 K from in-situ transmission electron microscope(TEM) video, with the volume contraction reaching 18.7% and 11.3%, respectively. The mechanisms for volume contraction of LT1 and LT2 phases are elucidated from the viewpoints of phase transformation, magnetic transition, and dehydrogenation, which is different from common NTE materials containing flexible polyhedra units in the structure. The linear volume shrinkage of LT2 in the temperature of 488-553 K corresponds to the phase transition of LT2→HT with a thermal expansion coefficient of -799.7 × 10^(-6) K^(-1) revealed by in-situ synchrotron powder X-ray diffraction. The sudden volume contraction in LT1 between 488 and 493 K may be caused by the rapid dehydrogenation of LT1 to Mg_(2)Ni. The revealed phenomenon in single composite material with different structures would be significant for preparing zero thermal expansion materials by tuning the fraction of LT1 and LT2 phases.展开更多
Recently,abundant resources,low-cost sodium-ion batteries are deemed to the new-generation battery in the field of largescale energy storage.Nevertheless,poor active reaction dynamics,dissolution of intermediates and ...Recently,abundant resources,low-cost sodium-ion batteries are deemed to the new-generation battery in the field of largescale energy storage.Nevertheless,poor active reaction dynamics,dissolution of intermediates and electrolyte matching problems are significant challenges that need to be solved.Herein,dimensional gradient structure of sheet-tube-dots is constructed with CoSe2@CNTs-MXene.Gradient structure is conducive to fast migration of electrons and ions with the association of ether electrolyte.For half-cell,CoSe2@CNTs-MXene exhibits high initial coulomb efficiency(81.7%)and excellent cycling performance(400 mAh g^-1 cycling for 200 times in 2 Ag^−1).Phase transformation pathway from crystalline CoSe2-Na2Se with Co and then amorphous CoSe2 in the discharge/charge process is also explored by in situ X-ray diffraction.Density functional theory study discloses the CoSe2@CNTs-MXene in ether electrolyte system which contributes to stable sodium storage performance owing to the strong adsorption force from hierarchical structure and weak interaction between electrolyte and electrode interface.For full cell,CoSe2@CNTs-MXene//Na3V2(PO4)3/C full battery can also afford a competitively reversible capacity of 280 mAh g^−1 over 50 cycles.Concisely,profiting from dimensional gradient structure and matched electrolyte of CoSe2@CNTs-MXene hold great application potential for stable sodium storage.展开更多
The intercalation behavior of spiro-(1,1)-bipyrrolidinium cation(SBP+) into graphite electrode from spiro-(1,1)-bipyrrolidinium tetrafluoroborate-ethylene carbonate(SBPBF4-EC) solutions is investigated by conventional...The intercalation behavior of spiro-(1,1)-bipyrrolidinium cation(SBP+) into graphite electrode from spiro-(1,1)-bipyrrolidinium tetrafluoroborate-ethylene carbonate(SBPBF4-EC) solutions is investigated by conventional electrochemical tests and in situ X-ray diffraction measurements. Two kinds of graphite intercalation compounds(GICs) with discrete characteristic intercalated gallery heights(IGHs)(ca. 0.95 and0.75 nm) can be obtained with varying the salt concentration. The effect of graphite type is also addressed.展开更多
A series of Y zeolites exchanged with different amount of cerium and lanthanum cations were investigated. Comprehensive routine analysis tools including X-ray photoelectron spectroscopy（XPS）, X-ray fluorescence（XRF...A series of Y zeolites exchanged with different amount of cerium and lanthanum cations were investigated. Comprehensive routine analysis tools including X-ray photoelectron spectroscopy（XPS）, X-ray fluorescence（XRF）, X-ray diffraction（XRD） and Py-Fourier transform infrared spectroscopy（Py-FTIR） were used to identify the cation location, and the result was verified via XRD Rietveld study. The results revealed that almost all the RE cations in RE-4, most cations in RE-8 to RE-14 and part of cations in RE-16 were located in the sodalite cage. The Al^（IV）/（Al^V＋Al^（VI）） values revealed by ^（27）Al MAS NMR spectra, the silicon aluminum ratio of the framework（SARF） values deduced from ^（29）Si MAS NMR spectra and XRD, and hydroxyl amount were reasonably in accordance with the location and content of rare earth cations. The hydrothermal stability derived from in situ XRD investigation and catalyst activity provided by micro-activity test manifested that samples RE-8 to RE-14 exhibited better performances than RE-4 and RE-16, among which RE-12 had the best properties. The phenomena were interpreted by the cation location and structural properties.展开更多
Diflerent from the traditional pyTometallurgical recovery process of Li and Co from spent lithium-ion batteries,a new recovery method for Li and Co was established by converting LiCoO2 into water-soluble metal sul-fat...Diflerent from the traditional pyTometallurgical recovery process of Li and Co from spent lithium-ion batteries,a new recovery method for Li and Co was established by converting LiCoO2 into water-soluble metal sul-fates by roasting a mixture of LiCoO2 and NaHSO4-H2O.The evolution law of the mixture with increased roasting temperature was investigated by thennogravimetry-diflerential scamiing calorimetry(TG-DSC),in situ X-ray diflrac-tion(XRD),XRD,and X-ray photoelectron spectroscopy(XPS).The results show that the phase transition of LiCoO2 mixed with NaHSO4 H2O with increased temperature proceeded as follows:LiCoO2,NaHSO4 H2O→LiCo02,NaHSO4→Lil-xCo02,LiNaSO4,Na2S2O7,Na2SO4→Li1-xCoCO2,Co3O4,LiNaSO4,Na2SO4→Co3O4,LiNaSO4.The reaction mechanism of this roasting process may be as follows:LiCoO2+NaHSO4-H2O→l/2Li2SO4+l/2Na2SO4+l/3Co3O4+l/12O2+3/2H2O,Li2SO4+Na2SO4=2LiNaSO4.展开更多
Layered LiMO_(2)(M=Ni,Co,and Mn) is a type of promising cathode materials for high energy density and high work voltage lithium-ion batteries.However,the poor rate performance and low power density hinder its further ...Layered LiMO_(2)(M=Ni,Co,and Mn) is a type of promising cathode materials for high energy density and high work voltage lithium-ion batteries.However,the poor rate performance and low power density hinder its further applications.The capacity fade is related to the structural transformation in the layered LiMO_(2).In this work,the structural changes of bi-material cathode composed of mesoporous graphene and layered LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM) were studied via in situ X-ray diffraction(XRD).During different C-rate charge-discharge test at the voltage range of 2.5-4.1 V,the composite cathode of NCM-graphene(NCM-G) reveals better rate performances than pure NCM cathode.The NCM-G composite electrode displays a higher rate capability of 76.7 mAh·g^(-1) at 5 C rate,compared to the pure NCM cathode of 69.8 mAh·g^(-1)discharge capacity.The in situ XRD results indicate that a reversible phase transition from hexagonal H1 to hexagonal H2 occurs in layered NCM material during 1 C chargedischarge process.With the current increasing to 2 C/5 C,the structure of layered NCM material for both electrodes reveals few changes during charge and discharge processes,which indicates the less utilization of NCM component at high C-rates.Hence,the improved rate performance for bi-material electrode is attributed to the highly conductive mesoporous graphene and the synergistic effect of mesoporous graphene and NCM material.展开更多
Li[Ni0.6Co0.2Mn0.2]O2(NCM622)is one of the best commercialized cathodes in the battery field.However,poor cyclability at relatively high temperature hinders its multiple usages.Here,operando tests were performed to in...Li[Ni0.6Co0.2Mn0.2]O2(NCM622)is one of the best commercialized cathodes in the battery field.However,poor cyclability at relatively high temperature hinders its multiple usages.Here,operando tests were performed to investigate the phase transitions and electron/ion transfer process of lavered NCM622 at 25 and 55℃.The identified spinel structure resulting in the poor cyclability at 55℃ guides the commercialization of batteries at high temperature.展开更多
The superplasticity of Ti-43Al-9V-0.2Y alloy sheet hot-rolled at 1100℃was systematically investigated in the temperature range of 750-900℃under an initial strain rate of 10^(-4)s^(-1).A bimodalγgraindistribution mi...The superplasticity of Ti-43Al-9V-0.2Y alloy sheet hot-rolled at 1100℃was systematically investigated in the temperature range of 750-900℃under an initial strain rate of 10^(-4)s^(-1).A bimodalγgraindistribution microstructure of Ti Al alloy sheet,with abundant nano-scale or sub-micronγlaths embedded insideβmatrix,exhibits an impressive superplastic behaviour.This inhomogeneous microstructure shows low-temperature superplasticity with a strain-rate sensitivity exponent of m=0.27 at 800℃,which is the lowest temperature of superplastic deformation for Ti Al alloys attained so far.The maximum elongation reaches~360%at 900℃with an initial strain rate of 2.0×10^(-4)s^(-1).To elucidate the softening mechanism of the disorderedβphase during superplastic deformation,the changes of phase composition were investigated up to 1000℃using in situ high-temperature X-ray diffraction(XRD)in this study.The results indicate thatβphase does not undergo the transformation from an ordered L2;structure to a disordered A2 structure and cannot coordinate superplastic deformation as a lubricant.Based on the microstructural evolution and occurrence of bothγandβdynamic recrystallization(DR)after tensile tests as characterized with electron backscatter diffraction(EBSD),the superplastic deformation mechanism can be explained by the combination of DR and grain boundary slipping(GBS).In the early stage of superplastic deformation,DR is an important coordination mechanism as associated with the reduced cavitation and dislocation density with increasing tensile temperature.Sufficient DR can relieve stress concentration arising from dislocation piling-up at grain boundaries through the fragmentation from the original coarse structures into the fine equiaxed ones due to recrystallization,which further effectively suppresses apparent grain growth during superplastic deformation.At the late stage of superplastic deformation,these equiaxed grains make GBS prevalent,which can effectively avoid intergranular cracking and is conducive to the further improvement in elongation.This study advances the understanding of the superplastic deformation mechanism of intermetallic Ti Al alloy.展开更多
Iron-based composite nanostructures with ceria or titania as shell coating on naked iron spheres were successfully synthesized and used to catalyze ammonia decomposition. The structure and texture of fresh and used ca...Iron-based composite nanostructures with ceria or titania as shell coating on naked iron spheres were successfully synthesized and used to catalyze ammonia decomposition. The structure and texture of fresh and used catalysts were characterized by transmission electron microscopy, X-ray diffraction, in situ X-ray diffraction, temperature-programmed reduction by hydrogen, and N2 adsorption-desorption. For ammonia decomposition, the iron-based composite catalyst coated with cerium and titanium showed excellent catalytic activity compared with naked iron sphere catalyst, with the former yielding nearly 100 % ammonia conversions at 650 ℃ and showing high stability in the catalysis test （for 60 h） at 600 ℃ with a space velocity of 24,000 cm3 gcat h-1. These results showed that adding cerium and titanium played a key role in improving catalytic activity for ammonia decomposition and enabling high thermal stability.展开更多
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20170549)the National Natural Science Foundation of China(No.21706103)Postdoctoral Science Foundation of Jiangsu Province(No.2019K295)。
文摘A new intercalation-type anode material is reported herein to improve the lithium storage kinetics for high-rate lithium ion capacitors.The crystal structure of orthorhombic NaNbO3 indicates two possible tunnels for lithium ions insertion into NaNbO3 host along the<101>and<141>directions.Moreover,in situ XRD is conducted to investigate the lithium storage mechanism and structural evolution of the NaNb O_(3) anode,demonstrating its intercalation behavior through(101)and(141)planes.Furthermore,the rGO nanosheets are introduced to facilitate the charge transfer,which also effectively prevent the aggregation of NaNbO3 nanocubes.As expected,the NaNbO_(3)/rGO nanocomposites possess remarkable reversible capacity(465 mA h g^(-1) at 0.1 A g^(-1)),superior rate capability(325 mA h g^(-1) at 1.0 A g^(-1))and cycling stability,attributed to their synergistic effect and high Li+diffusion coefficient DLi[D(NaNbO_(3)/rGO)/D(NaNbO_(3))≈31.54].Remarkably,the NaNbO3/rGO-based LIC delivers a high energy density of 166.7 W h kg^(-1) at 112.4 W kg^(-1) and remains 24.1 W h kg^(-1) at an ultrahigh power density of26621.2 W kg^(-1),with an outstanding cycling durability(90%retention over 3000 cycles at 1.0 A g^(-1)).This study provides new insights on novel intercalation-type anode material to enrich the materials system of LICs.
基金supported by the 100 Talents Plan Foundation of Sun Yat-sen UniversityThousand Youth Talents Plan of China and Guangdong Province+1 种基金the Program for Guangdong Introducing Innovative and Entrepreneurial Teams (2017ZT07C069)the NSFC Projects (22075321, 21821003 and 21890380)。
文摘Bismuth (Bi) has indeed inspired great interests in lithium-ion batteries (LIBs) due to the high capacity,but was still limited by the low electrical conductivity and large volume variation.Herein,a composite material based on Bi nanoparticles in situ encapsulated by carbon film (Bi@CF) is prepared successfully through a facile metal–organic framework (MOF)-engaged approach.As anode materials for LIBs,the Bi@CF composites achieved high reversible capacities of 705 and 538 mAh g^(-1)at 0.2 and 0.5 A g^(-1) after200 cycles,and long cycling performance with a stable capacity of 306 mAh g^(-1)at 1.0 A g^(-1) even after 900 cycles.In situ X-ray diffraction (XRD) measurements clearly revealed the conversion between Bi and Li_(3)Bi during the alloying/dealloying process,confirming the good electrochemical reversibility of Bi@CF for Li-storage.The reaction kinetics of this Bi@CF composite was further studied by galvanostatic intermittent titration technique (GITT).This work may provide an inspiration for the elaborate design and facile preparation of alloy-type anode materials for high-performance rechargeable batteries.
基金financially supported by the National Natural Science Foundation of China,China(21975251)。
文摘The anion storage behavior of graphite positive electrode in a dual-ion battery is closely related to the solvation of anion in the corresponding electrolyte solution.The classical electrolyte solutions of Li BF_(4)^(-)sulfolane(SL)have long been recognized in the community of lithium batteries and still appear promising in dual-ion batteries.Nevertheless,the solvation of BF_(4)^(-)by SL has seldom been addressed before.In this study,the solvation states of SL-BF_(4)^(-)are adjusted by varying LiBF_(4)concentration or introducing auxiliary salts of LiPF_6or SBPBF_(4)(SBP:spiro-(1,1')-bipyrrolidinium)in the electrolyte solutions of Li/graphite dualion cells.The electrochemical storage processes of SL-BF_(4)^(-)anions in graphite electrodes are investigated through in situ X-ray diffraction measurements.Two kinds of graphite intercalation compounds(GICs)with contrastive intercalation gallery heights(IGHs)have been discovered,which are ascribed to the storage of different kinds of SL-BF_(4)^(-)anions in graphite electrode.The interactions between ions and SL in the electrolyte solutions are characterized by Fourier transform infrared spectroscopy and then correlated with the performance of Li/graphite cells.
基金supported by National Natural Science Foundation of China(51762014)China Postdoctoral Science Foundation(2019M652316)
文摘Intercalating Nb-based oxides are promising anode compounds for lithiumion batteries since they have both good safety and large capacities.However,the research in this field is still limited.Here,Mo_(3)Nb_(14)O_(44)with a large theoretical capacity of 398 mAh g^(–1)(Mo^(64)←→Mo^(4+)and Nb^(5+)←→Nb^(3+))is exploited as a new Nb-based oxide anode compound,and Mo_(3)Nb_(14)O_(44)micron-sized particles(Mo_(3)Nb_(14)O_(44)-M)and Mo3Nb14O44 nanowires(Mo_(3)Nb_(14)O_(44)-N)are demonstrated.Mo3Nb14O44 owns a tetragonal shear ReO_(3)crystal structure(high-symmetric 14 space group)constructed by 4×4×∞(Mo,Nb)O_(6)octahedron blocks linked by Mo O4 tetrahedra,forming an A–B–A layered structure with a large interlayer spacing.This interesting structure allows fast Li+storage within the interlayers and significant intercalation-pseudocapacitive behavior,leading to the high rate performance of Mo_(3)Nb_(14)O_(44)-M/Mo_(3)Nb_(14)O_(44)-N with a large 10 C versus 0.1 C capacity retention percentage of 38.1/54.2%.Mo_(3)Nb_(14)O_(44)-M/Mo_(3)Nb_(14)O_(44)-N further exhibits a safe operating potential of 1.72/1.68 V,large reversible capacity of 323/321 m Ah g^(–1)at 0.1 C,high initial coulombic efficiency of 92.2/90.0%,and good cycling stability with 71.8/75.8%capacity retention after 1000 cycles at10 C.Additionally,a Li Mn_(2)O_(4)/Mo_(3)Nb_(14)O_(44)-N full cell also performs well.Therefore,Mo_(3)Nb_(14)O_(44)holds great promise as a fast-charging,safe,largecapacity,high-efficient,and long-life Li^(+)anode container.
基金supported by the Federal Target Program "Scientific and Educational Personnel of Innovative Russia" 2009–2013 (Agreement 8429)RFBR Grant No 12-03-01091-a+2 种基金Presidium RAS (Project 2451)Presidium SB RAS (Project 36)Integration Research Projects SB RAS No 75
文摘Changes of a 65Ni25Cu10A1203 catalyst consisting of Ni-enriched and Cu-enriched alloys were investigated in the bulk and on the surface during the growth of nitrogen-doped carbon nanofibers （N-CNFs） by decomposition of a 50%C2I-I4/50%NH3 mixture using in situ X-ray diffraction （XRD） analysis, ex situ X-ray photoelectron spectroscopy （XPS） and transmission electron microscopy （TEM） techniques. It was shown that N-CNF growth at 450-650 ℃is accompanied by dissolution of carbon and nitrogen in the Ni-enriched alloy, whereas Cu-enriched alloy remains inactive. A correlation between nickel and copper surface concentrations and properties of N-CNFs in relation to the nitrogen content was found. It was demonstrated that phase composition of the catalyst during N-CNF growth determines the type of N-CNFs structure.
基金supported by the National Key Research and Development Program of China (2021YFB3701001)the National Natural Science Foundation of China (51871143)+1 种基金Shanghai Engineering Research Center for Metal Parts Green Remanufacture (No.19DZ2252900) from Shanghai Engineering Research Center Construction ProjectShanghai Rising-Star Program (21QA1403200)。
文摘The negative thermal expansion(NTE) phenomenon is of great significance in fabricating zero thermal expansion(ZTE) materials to avoid thermal shock during heating and cooling. NTE is observed in limited groups of materials, e.g., metal cyanides, oxometallates, and metalorganic frameworks, but has not been reported in the family of metal hydrides. Herein, a colossal and continuous negative thermal expansion is firstly developed in the low-temperature phases of LT1-and LT2-Mg_(2)NiH_(4) between 488 K and 733 K from in-situ transmission electron microscope(TEM) video, with the volume contraction reaching 18.7% and 11.3%, respectively. The mechanisms for volume contraction of LT1 and LT2 phases are elucidated from the viewpoints of phase transformation, magnetic transition, and dehydrogenation, which is different from common NTE materials containing flexible polyhedra units in the structure. The linear volume shrinkage of LT2 in the temperature of 488-553 K corresponds to the phase transition of LT2→HT with a thermal expansion coefficient of -799.7 × 10^(-6) K^(-1) revealed by in-situ synchrotron powder X-ray diffraction. The sudden volume contraction in LT1 between 488 and 493 K may be caused by the rapid dehydrogenation of LT1 to Mg_(2)Ni. The revealed phenomenon in single composite material with different structures would be significant for preparing zero thermal expansion materials by tuning the fraction of LT1 and LT2 phases.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.U1632151 and 21706048)the Key Research and Development Project of Anhui Province of China(Grant No.1704a0902023)the Open Project of Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices(No.JS1802)。
文摘Recently,abundant resources,low-cost sodium-ion batteries are deemed to the new-generation battery in the field of largescale energy storage.Nevertheless,poor active reaction dynamics,dissolution of intermediates and electrolyte matching problems are significant challenges that need to be solved.Herein,dimensional gradient structure of sheet-tube-dots is constructed with CoSe2@CNTs-MXene.Gradient structure is conducive to fast migration of electrons and ions with the association of ether electrolyte.For half-cell,CoSe2@CNTs-MXene exhibits high initial coulomb efficiency(81.7%)and excellent cycling performance(400 mAh g^-1 cycling for 200 times in 2 Ag^−1).Phase transformation pathway from crystalline CoSe2-Na2Se with Co and then amorphous CoSe2 in the discharge/charge process is also explored by in situ X-ray diffraction.Density functional theory study discloses the CoSe2@CNTs-MXene in ether electrolyte system which contributes to stable sodium storage performance owing to the strong adsorption force from hierarchical structure and weak interaction between electrolyte and electrode interface.For full cell,CoSe2@CNTs-MXene//Na3V2(PO4)3/C full battery can also afford a competitively reversible capacity of 280 mAh g^−1 over 50 cycles.Concisely,profiting from dimensional gradient structure and matched electrolyte of CoSe2@CNTs-MXene hold great application potential for stable sodium storage.
基金financially supported by National Natural Science Foundation of China (No. 21975251)。
文摘The intercalation behavior of spiro-(1,1)-bipyrrolidinium cation(SBP+) into graphite electrode from spiro-(1,1)-bipyrrolidinium tetrafluoroborate-ethylene carbonate(SBPBF4-EC) solutions is investigated by conventional electrochemical tests and in situ X-ray diffraction measurements. Two kinds of graphite intercalation compounds(GICs) with discrete characteristic intercalated gallery heights(IGHs)(ca. 0.95 and0.75 nm) can be obtained with varying the salt concentration. The effect of graphite type is also addressed.
基金Project supported by the Foundation of SINOPEC(111015)
文摘A series of Y zeolites exchanged with different amount of cerium and lanthanum cations were investigated. Comprehensive routine analysis tools including X-ray photoelectron spectroscopy（XPS）, X-ray fluorescence（XRF）, X-ray diffraction（XRD） and Py-Fourier transform infrared spectroscopy（Py-FTIR） were used to identify the cation location, and the result was verified via XRD Rietveld study. The results revealed that almost all the RE cations in RE-4, most cations in RE-8 to RE-14 and part of cations in RE-16 were located in the sodalite cage. The Al^（IV）/（Al^V＋Al^（VI）） values revealed by ^（27）Al MAS NMR spectra, the silicon aluminum ratio of the framework（SARF） values deduced from ^（29）Si MAS NMR spectra and XRD, and hydroxyl amount were reasonably in accordance with the location and content of rare earth cations. The hydrothermal stability derived from in situ XRD investigation and catalyst activity provided by micro-activity test manifested that samples RE-8 to RE-14 exhibited better performances than RE-4 and RE-16, among which RE-12 had the best properties. The phenomena were interpreted by the cation location and structural properties.
基金Supported by the National Natural Science Foundation of China(No.51864032)and the Joint Fund Between the Shenyang National Laboratory for Materials Science and the State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,China(No.l8LHZD002).
文摘Diflerent from the traditional pyTometallurgical recovery process of Li and Co from spent lithium-ion batteries,a new recovery method for Li and Co was established by converting LiCoO2 into water-soluble metal sul-fates by roasting a mixture of LiCoO2 and NaHSO4-H2O.The evolution law of the mixture with increased roasting temperature was investigated by thennogravimetry-diflerential scamiing calorimetry(TG-DSC),in situ X-ray diflrac-tion(XRD),XRD,and X-ray photoelectron spectroscopy(XPS).The results show that the phase transition of LiCoO2 mixed with NaHSO4 H2O with increased temperature proceeded as follows:LiCoO2,NaHSO4 H2O→LiCo02,NaHSO4→Lil-xCo02,LiNaSO4,Na2S2O7,Na2SO4→Li1-xCoCO2,Co3O4,LiNaSO4,Na2SO4→Co3O4,LiNaSO4.The reaction mechanism of this roasting process may be as follows:LiCoO2+NaHSO4-H2O→l/2Li2SO4+l/2Na2SO4+l/3Co3O4+l/12O2+3/2H2O,Li2SO4+Na2SO4=2LiNaSO4.
基金financially supported by the National Natural Science Foundation of China(Nos.51822706 and51777200)the Beijing Municipal and Technology Commission(No.Z181100000118006)。
文摘Layered LiMO_(2)(M=Ni,Co,and Mn) is a type of promising cathode materials for high energy density and high work voltage lithium-ion batteries.However,the poor rate performance and low power density hinder its further applications.The capacity fade is related to the structural transformation in the layered LiMO_(2).In this work,the structural changes of bi-material cathode composed of mesoporous graphene and layered LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM) were studied via in situ X-ray diffraction(XRD).During different C-rate charge-discharge test at the voltage range of 2.5-4.1 V,the composite cathode of NCM-graphene(NCM-G) reveals better rate performances than pure NCM cathode.The NCM-G composite electrode displays a higher rate capability of 76.7 mAh·g^(-1) at 5 C rate,compared to the pure NCM cathode of 69.8 mAh·g^(-1)discharge capacity.The in situ XRD results indicate that a reversible phase transition from hexagonal H1 to hexagonal H2 occurs in layered NCM material during 1 C chargedischarge process.With the current increasing to 2 C/5 C,the structure of layered NCM material for both electrodes reveals few changes during charge and discharge processes,which indicates the less utilization of NCM component at high C-rates.Hence,the improved rate performance for bi-material electrode is attributed to the highly conductive mesoporous graphene and the synergistic effect of mesoporous graphene and NCM material.
基金Supported by the Project of the Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory,China(No.XH12020-003)the National Natural Science Foundation of China(No.51521001)+1 种基金the National Key Research and Development Program of China(No.2016YFA0202603)the Fundamental Rescarch Funds for the Central Universities of China(No.WUT:205201019)。
文摘Li[Ni0.6Co0.2Mn0.2]O2(NCM622)is one of the best commercialized cathodes in the battery field.However,poor cyclability at relatively high temperature hinders its multiple usages.Here,operando tests were performed to investigate the phase transitions and electron/ion transfer process of lavered NCM622 at 25 and 55℃.The identified spinel structure resulting in the poor cyclability at 55℃ guides the commercialization of batteries at high temperature.
基金the financial support from the Singapore Ministry of Education Academic Research Funds(R-265–000–686–114 and MOE2018-T2–1–140)。
文摘The superplasticity of Ti-43Al-9V-0.2Y alloy sheet hot-rolled at 1100℃was systematically investigated in the temperature range of 750-900℃under an initial strain rate of 10^(-4)s^(-1).A bimodalγgraindistribution microstructure of Ti Al alloy sheet,with abundant nano-scale or sub-micronγlaths embedded insideβmatrix,exhibits an impressive superplastic behaviour.This inhomogeneous microstructure shows low-temperature superplasticity with a strain-rate sensitivity exponent of m=0.27 at 800℃,which is the lowest temperature of superplastic deformation for Ti Al alloys attained so far.The maximum elongation reaches~360%at 900℃with an initial strain rate of 2.0×10^(-4)s^(-1).To elucidate the softening mechanism of the disorderedβphase during superplastic deformation,the changes of phase composition were investigated up to 1000℃using in situ high-temperature X-ray diffraction(XRD)in this study.The results indicate thatβphase does not undergo the transformation from an ordered L2;structure to a disordered A2 structure and cannot coordinate superplastic deformation as a lubricant.Based on the microstructural evolution and occurrence of bothγandβdynamic recrystallization(DR)after tensile tests as characterized with electron backscatter diffraction(EBSD),the superplastic deformation mechanism can be explained by the combination of DR and grain boundary slipping(GBS).In the early stage of superplastic deformation,DR is an important coordination mechanism as associated with the reduced cavitation and dislocation density with increasing tensile temperature.Sufficient DR can relieve stress concentration arising from dislocation piling-up at grain boundaries through the fragmentation from the original coarse structures into the fine equiaxed ones due to recrystallization,which further effectively suppresses apparent grain growth during superplastic deformation.At the late stage of superplastic deformation,these equiaxed grains make GBS prevalent,which can effectively avoid intergranular cracking and is conducive to the further improvement in elongation.This study advances the understanding of the superplastic deformation mechanism of intermetallic Ti Al alloy.
文摘Iron-based composite nanostructures with ceria or titania as shell coating on naked iron spheres were successfully synthesized and used to catalyze ammonia decomposition. The structure and texture of fresh and used catalysts were characterized by transmission electron microscopy, X-ray diffraction, in situ X-ray diffraction, temperature-programmed reduction by hydrogen, and N2 adsorption-desorption. For ammonia decomposition, the iron-based composite catalyst coated with cerium and titanium showed excellent catalytic activity compared with naked iron sphere catalyst, with the former yielding nearly 100 % ammonia conversions at 650 ℃ and showing high stability in the catalysis test （for 60 h） at 600 ℃ with a space velocity of 24,000 cm3 gcat h-1. These results showed that adding cerium and titanium played a key role in improving catalytic activity for ammonia decomposition and enabling high thermal stability.
