Owing to their safety and low cost,magnesium ion batteries(MIBs)have attracted much attention in recent years.However,the sluggish diffusion dynamics of magnesium ions hampers the search for appropriate cathode materi...Owing to their safety and low cost,magnesium ion batteries(MIBs)have attracted much attention in recent years.However,the sluggish diffusion dynamics of magnesium ions hampers the search for appropriate cathode materials with excellent electrochemical performance.Herein,we design and synthesize a novel flexible three-dimensional-networked composite of iron vanadate nanosheet arrays/carbon cloths(3 D FeVO/CC)as a binder-free cathode for MIBs.Relative to bare FeVO nanosheets,the 3 D binder-free electrode with designed architecture enables a full range of electrochemical potential,including a high specific capacity of270 mA h g^(-1) and an increased life span(over 5000 cycles).Such achievable high-density energy originates from the synergistic optimization of electron and ion kinetics,while the durability benefits from the robust structure that prevents degradation in cycling.The single-phase reaction mechanism of FeVO in the magnesium ion storage process is also explored by in-situ X-ray diffraction and Raman technologies.Moreover,a flexible MIB pouch cell(3 D FeVO/CCIMgNaTi_(3)O_(7)) is assembled and exhibits practical application potential.This work verifies that 3 D FeVO/CC is a potential candidate cathode material that can satisfy the requirements of highperformance MIBs.It also opens a new avenue to improve the electrochemical performance of cathode materials for MIBs.展开更多
Sluggish kinetics of Mg^2+intercalation and low working potential seriously hinder the development of highenergy-density magnesium-ion batteries(MIBs).Hence developing cathode materials with fast Mg^2+diffusion and hi...Sluggish kinetics of Mg^2+intercalation and low working potential seriously hinder the development of highenergy-density magnesium-ion batteries(MIBs).Hence developing cathode materials with fast Mg^2+diffusion and high working voltage is a key to overcome the obstacles in MIBs.Herein,a tetragonal NaV2O2(PO4)2 F/reduced graphene oxide(r GO)is proposed as an effective Mg^2+host for the first time.It exhibits the highest average discharge voltage(3.3 V vs.Mg^2+/Mg),fast diffusion kinetics of Mg^2+with the average diffusivity of 2.99×10^-10 cm^2s^-1,and ultralong cycling stability(up to 9500 cycles).The Mg^2+storage mechanism of NaV2O2(PO4)2 F/r GO is demonstrated as a single-phase(de)intercalation reaction by in situ X-ray diffraction(XRD)technology.Density functional theory(DFT)computations further reveal that Mg^2+ions tend to migrate along the a direction.X-ray absorption near edge structure(XANES)demonstrates a decrease in the average valence of vanadium,and the local coordination environment around vanadium site is highly conserved after magnesiation.Moreover,the assembled NaV2O2(PO4)2 F//Mg0.79NaTi2(PO4)3 Mg-ion full cell exhibits high power and energy densities,which indicates that NaV2O2(PO4)2 F/r GO owns potential for practical applications.This work achieves a breakthrough in the working voltage of cathode materials for MIBs and provides a new opportunity for high-energy-density MIBs.展开更多
The low-cost and high-capacity metal oxides/oxyhydroxides possess great merits as anodes for lithium-ion batteries(LIBs)with high energy density.However,their commercialization is greatly hindered by insufficient rate...The low-cost and high-capacity metal oxides/oxyhydroxides possess great merits as anodes for lithium-ion batteries(LIBs)with high energy density.However,their commercialization is greatly hindered by insufficient rate capability and cyclability.Rational regulations of metal oxides/oxyhydroxides with hollow geometry and disordered atomic frameworks represent efficient ways to improve their electrochemical properties.Herein,we propose a fast alkalietching method to realize the in-situ fabrication of iron oxyhydroxide with one-dimensional(1D)hierarchical hollow nanostructure and amorphous atomic structure from the iron vanadate nanowires.Benefiting from the improved electron/ion kinetics and efficient buffer ability for the volumetric change during the electro-cycles both in nanoscale and atomic level,the graphene-modified amorphous hierarchical FeOOH nanotubes(FeOOH-NTs)display high rate capability(~650 mA h g^−1 at 2000 mA g^−1)and superior long-term cycling stability(463 mA h g^−1 after 1800 cycles),which represents the best cycling performance among the reported FeOOH-based materials.More importantly,the selective dissolutionregrowth mechanism is demonstrated based on the time tracking of the whole transition process,in which the dissolution of FeVO4 and the in-situ selective re-nucleation of FeOOH during the formation of FeOOH-NTs play the key roles.The present strategy is also a general method to prepare various metal(such as Fe,Mn,Co,and Cu)oxides/oxyhydroxides with 1D hierarchical nanostructures.展开更多
基金supported by the National Key Research and Development Program of China(2020YFA0715000)the National Natural Science Foundation of China(51832004 and 51972259)+1 种基金the Natural Science Foundation of Hubei Province(2019CFA001)Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT2020-003)。
文摘Owing to their safety and low cost,magnesium ion batteries(MIBs)have attracted much attention in recent years.However,the sluggish diffusion dynamics of magnesium ions hampers the search for appropriate cathode materials with excellent electrochemical performance.Herein,we design and synthesize a novel flexible three-dimensional-networked composite of iron vanadate nanosheet arrays/carbon cloths(3 D FeVO/CC)as a binder-free cathode for MIBs.Relative to bare FeVO nanosheets,the 3 D binder-free electrode with designed architecture enables a full range of electrochemical potential,including a high specific capacity of270 mA h g^(-1) and an increased life span(over 5000 cycles).Such achievable high-density energy originates from the synergistic optimization of electron and ion kinetics,while the durability benefits from the robust structure that prevents degradation in cycling.The single-phase reaction mechanism of FeVO in the magnesium ion storage process is also explored by in-situ X-ray diffraction and Raman technologies.Moreover,a flexible MIB pouch cell(3 D FeVO/CCIMgNaTi_(3)O_(7)) is assembled and exhibits practical application potential.This work verifies that 3 D FeVO/CC is a potential candidate cathode material that can satisfy the requirements of highperformance MIBs.It also opens a new avenue to improve the electrochemical performance of cathode materials for MIBs.
基金supported by the National Key Research and Development Program of China(2016YFA0202603 and 2016YFA0202601)the National Natural Science Fund for Distinguished Young Scholars(51425204)+1 种基金the National Natural Science Foundation of China(51832004,51602239 and 51672307)the International Science&Technology Cooperation Program of China(2013DFA50840)。
文摘Sluggish kinetics of Mg^2+intercalation and low working potential seriously hinder the development of highenergy-density magnesium-ion batteries(MIBs).Hence developing cathode materials with fast Mg^2+diffusion and high working voltage is a key to overcome the obstacles in MIBs.Herein,a tetragonal NaV2O2(PO4)2 F/reduced graphene oxide(r GO)is proposed as an effective Mg^2+host for the first time.It exhibits the highest average discharge voltage(3.3 V vs.Mg^2+/Mg),fast diffusion kinetics of Mg^2+with the average diffusivity of 2.99×10^-10 cm^2s^-1,and ultralong cycling stability(up to 9500 cycles).The Mg^2+storage mechanism of NaV2O2(PO4)2 F/r GO is demonstrated as a single-phase(de)intercalation reaction by in situ X-ray diffraction(XRD)technology.Density functional theory(DFT)computations further reveal that Mg^2+ions tend to migrate along the a direction.X-ray absorption near edge structure(XANES)demonstrates a decrease in the average valence of vanadium,and the local coordination environment around vanadium site is highly conserved after magnesiation.Moreover,the assembled NaV2O2(PO4)2 F//Mg0.79NaTi2(PO4)3 Mg-ion full cell exhibits high power and energy densities,which indicates that NaV2O2(PO4)2 F/r GO owns potential for practical applications.This work achieves a breakthrough in the working voltage of cathode materials for MIBs and provides a new opportunity for high-energy-density MIBs.
基金This work was supported by the National Key Research and Development Program of China(2017YFE0127600,2016YFA0202600)the Program of Introducing Talents of Discipline to Universities(B17034)+3 种基金the National Natural Science Foundation of China(51521001 and 51602239)the National Natural Science Fund for Distinguished Young Scholars(51425204)Hubei Provincial Natural Science Foundation(2016CFB267)the Fundamental Research Funds for the Central Universities(WUT:2017-YB-001).
文摘The low-cost and high-capacity metal oxides/oxyhydroxides possess great merits as anodes for lithium-ion batteries(LIBs)with high energy density.However,their commercialization is greatly hindered by insufficient rate capability and cyclability.Rational regulations of metal oxides/oxyhydroxides with hollow geometry and disordered atomic frameworks represent efficient ways to improve their electrochemical properties.Herein,we propose a fast alkalietching method to realize the in-situ fabrication of iron oxyhydroxide with one-dimensional(1D)hierarchical hollow nanostructure and amorphous atomic structure from the iron vanadate nanowires.Benefiting from the improved electron/ion kinetics and efficient buffer ability for the volumetric change during the electro-cycles both in nanoscale and atomic level,the graphene-modified amorphous hierarchical FeOOH nanotubes(FeOOH-NTs)display high rate capability(~650 mA h g^−1 at 2000 mA g^−1)and superior long-term cycling stability(463 mA h g^−1 after 1800 cycles),which represents the best cycling performance among the reported FeOOH-based materials.More importantly,the selective dissolutionregrowth mechanism is demonstrated based on the time tracking of the whole transition process,in which the dissolution of FeVO4 and the in-situ selective re-nucleation of FeOOH during the formation of FeOOH-NTs play the key roles.The present strategy is also a general method to prepare various metal(such as Fe,Mn,Co,and Cu)oxides/oxyhydroxides with 1D hierarchical nanostructures.
