Hard carbon materials are characterized by having rich resources,simple processing technology,and low cost,and they are promising as one of the anode electrodes for commercial applications of sodium-/potassium-ion bat...Hard carbon materials are characterized by having rich resources,simple processing technology,and low cost,and they are promising as one of the anode electrodes for commercial applications of sodium-/potassium-ion batteries.Simultaneously,exploring the alkali metal ion storage mechanism is particularly important for designing high-performance electrode materials.However,the structure of hard carbon is more complex,and the description of energy storage behavior is quite controversial.In this study,the Magnolia grandiflora Lima leaf is used as a precursor,combined with simple pyrolysis and impurity removal processes,to obtain biomass-derived hard carbon material(carbonized Magnolia grandiflora Lima leaf[CMGL]).When it is used as an anode for sodium-ion batteries,it exhibits a high specific capacity of 315mAh/g,and the capacity retention rate is 90.0%after 100 cycles.For potassium-ion batteries,the charge specific capacity is 263.5mAh/g,with a capacity retention rate of 85.5%at the same cycling.Furthermore,different electrochemical analysis methods and microstructure characterization techniques were used to further elucidate the sodium/potassium storage mechanism of the material.All the results indicate that the high potential slope region represents the adsorption/desorption characteristics on the surface active sites,whereas the low-potential quasiplateau region belongs to the ion insertion/extraction in the graphitic microcrystallites interlayer.It is noteworthy that potassium ion is randomly intercalated between the graphitic microcrystallite layer without forming a segmented intercalation compound structure.展开更多
In higher engineering education,professional courses and ideological and political theory courses go in the same direction,which is an important task of the current professional curriculum construction.This paper intr...In higher engineering education,professional courses and ideological and political theory courses go in the same direction,which is an important task of the current professional curriculum construction.This paper introduces the key and difficult problems in the teaching content of the course Engineering Valuation in the Department of Engineering Management and Real Estate of Jiangxi Normal University.Based on the characteristics of simulation information technology such as BIM and VR and the differences of ideological and political elements,it updates and improves the cases of courses for ideological and political education,gives full play to the synergistic effect,and realizes the"triple"talent training goal of knowledge,ability and literacy.展开更多
Metallic antimony(Sb) has been attracted much attentions as anode for lithium-ion batteries due to its high capacity.Nevertheless,the large volume expansion during the lithiation process leads to poor electrochemical ...Metallic antimony(Sb) has been attracted much attentions as anode for lithium-ion batteries due to its high capacity.Nevertheless,the large volume expansion during the lithiation process leads to poor electrochemical performance,which seriously limits the practical application in lithium-ion batteries.Herein,NiSb nanoparticles encapsulated by carbon nanosheets have been developed via a facile strategy and as anode for lithium-ion batteries.In this attractive structure,the carbon nanosheets can effectively avoid volume change of NiSb nanoparticles and inhibit the direct contact of NiSb nanoparticles to the electrolyte during the lithiation/delithiation process.As a result,the NiSb/C nanosheets display an outstanding long cycling performance(405 mA h g-1 after 1000 cycles at 1.0 A g-1) and excellent rate capability(305 mA h g-1 at 2.0 A g-1) when application in lithium-ion batteries.展开更多
Nickel-rich layered oxides have been identified as the most promising commercial cathode materials for lithium-ion batteries(LIBs)for their high theoretical specific capacity.However,the poor cycling stability of nick...Nickel-rich layered oxides have been identified as the most promising commercial cathode materials for lithium-ion batteries(LIBs)for their high theoretical specific capacity.However,the poor cycling stability of nickel-rich cathode materials is one of the major barriers for the large-scale usage of LIBs.The existing obstructions that suppress the capacity degradation of nickel-rich cathode materials are as a result of phase transition,mechanical instability,intergranular cracks,side reaction,oxygen loss,and thermal instability during cycling.Core–shell structures,oxidating precursors,electrolyte additives,doping/coating and synthesizing single crystals have been identified as effective methods to improve cycling stability of nickel-rich cathode materials.Herein,recent progress of surface modification,e.g.coating and doping,in nickel-rich cathode materials are summarized based on Periodic table to provide a clear understanding.Electrochemical performances and mechanisms of modified structure are discussed in detail.It is hoped that an overview of synthesis and surface modification can be presented and a perspective of nickel-rich materials in LIBs can be given.展开更多
Potassium ion batteries(PIBs) have been regarded as promising alternatives to lithium ion batteries(LIBs)on account of their abundant resource and low cost in large scale energy storage applications. However,it still ...Potassium ion batteries(PIBs) have been regarded as promising alternatives to lithium ion batteries(LIBs)on account of their abundant resource and low cost in large scale energy storage applications. However,it still remains great challenges to explore suitable electrode materials that can reversibly accommodate large size of potassium ions. Here, we construct oxygen-deficient V_(2)O_(3)nanoparticles encapsulated in amorphous carbon shell(Od-V_(2)O_(3)@C) as anode materials for PIBs by subtly combining the strategies of morphology and deficiency engineering. The MOF derived nanostructure along with uniform carbon coating layer can not only enables fast K+migration and charge transfer kinetics, but also accommodate volume change and maintain structural stability. Besides, the introduction of oxygen deficiency intrinsically tunes the electronic structure of materials according to DFT calculation, and thus lead to improved electrochemical performance. When utilized as anode for PIBs, Od-V_(2)O_(3)@C electrode exhibits superior rate capability(reversible capacities of 262.8, 227.8, 201.5, 179.8, 156.9 mAh/g at 100, 200, 500, 1000 and2000 mA/g, respectively), and ultralong cycle life(127.4 mAh/g after 1000 cycles at 2 A/g). This study demonstrates a feasible way to realize high performance PIBs through morphology and deficiency engineering.展开更多
Dielectric capacitors with high capacitive energy storage are urgently needed to meet the growing demand for high-performance energy storage devices.Herein,a novel lead-free Sr_(5)BiTi_(3)Nb_(7)O_(30)(SBTN)tungsten br...Dielectric capacitors with high capacitive energy storage are urgently needed to meet the growing demand for high-performance energy storage devices.Herein,a novel lead-free Sr_(5)BiTi_(3)Nb_(7)O_(30)(SBTN)tungsten bronze relaxor ferroelectric ceramic is prepared and explored for potential energy storage applications.A high recoverable energy density Wrec(~3.72 J/cm^(3))and ultrahigh efficiencyη(~94.2%)at 380 kV/cm are achieved simultaneously.Both Wrec andηexhibit superior stabilities against temperature(30-140°C),cycles(100-105)and frequency(1-500 Hz).In addition,a high current density of 796 A/cm^(2) and a large power density of 71.7 MW/cm^(3) are achieved,together with good thermal endurance and fatigue resistance.These results demonstrate that the obtained SBTN ceramic can be deemed as the promising candidates for dielectric capacitor applications.展开更多
基金This study was financially supported by the National Natural Science Foundation of China(No.21965017).
文摘Hard carbon materials are characterized by having rich resources,simple processing technology,and low cost,and they are promising as one of the anode electrodes for commercial applications of sodium-/potassium-ion batteries.Simultaneously,exploring the alkali metal ion storage mechanism is particularly important for designing high-performance electrode materials.However,the structure of hard carbon is more complex,and the description of energy storage behavior is quite controversial.In this study,the Magnolia grandiflora Lima leaf is used as a precursor,combined with simple pyrolysis and impurity removal processes,to obtain biomass-derived hard carbon material(carbonized Magnolia grandiflora Lima leaf[CMGL]).When it is used as an anode for sodium-ion batteries,it exhibits a high specific capacity of 315mAh/g,and the capacity retention rate is 90.0%after 100 cycles.For potassium-ion batteries,the charge specific capacity is 263.5mAh/g,with a capacity retention rate of 85.5%at the same cycling.Furthermore,different electrochemical analysis methods and microstructure characterization techniques were used to further elucidate the sodium/potassium storage mechanism of the material.All the results indicate that the high potential slope region represents the adsorption/desorption characteristics on the surface active sites,whereas the low-potential quasiplateau region belongs to the ion insertion/extraction in the graphitic microcrystallites interlayer.It is noteworthy that potassium ion is randomly intercalated between the graphitic microcrystallite layer without forming a segmented intercalation compound structure.
基金The Teaching Reform Project in Jiangxi Province-the Application of BIM Simulation Information Technology in the Teaching of Engineering Valuation Course Group(JXJG-19-2-48)Jiangxi Educational Planning Project-Research on the Realization of Synergistic Effect of BIM and MOOC in Higher Engineering Education(16YB014).
文摘In higher engineering education,professional courses and ideological and political theory courses go in the same direction,which is an important task of the current professional curriculum construction.This paper introduces the key and difficult problems in the teaching content of the course Engineering Valuation in the Department of Engineering Management and Real Estate of Jiangxi Normal University.Based on the characteristics of simulation information technology such as BIM and VR and the differences of ideological and political elements,it updates and improves the cases of courses for ideological and political education,gives full play to the synergistic effect,and realizes the"triple"talent training goal of knowledge,ability and literacy.
基金the financial support from Guangdong Natural Science Funds for Distinguished Young Scholar(2016A030306010)China Postdoctoral Science Foundation(2017M622675)Natural Science Foundation of Guangdong Province(2018A030313944)
文摘Metallic antimony(Sb) has been attracted much attentions as anode for lithium-ion batteries due to its high capacity.Nevertheless,the large volume expansion during the lithiation process leads to poor electrochemical performance,which seriously limits the practical application in lithium-ion batteries.Herein,NiSb nanoparticles encapsulated by carbon nanosheets have been developed via a facile strategy and as anode for lithium-ion batteries.In this attractive structure,the carbon nanosheets can effectively avoid volume change of NiSb nanoparticles and inhibit the direct contact of NiSb nanoparticles to the electrolyte during the lithiation/delithiation process.As a result,the NiSb/C nanosheets display an outstanding long cycling performance(405 mA h g-1 after 1000 cycles at 1.0 A g-1) and excellent rate capability(305 mA h g-1 at 2.0 A g-1) when application in lithium-ion batteries.
文摘Nickel-rich layered oxides have been identified as the most promising commercial cathode materials for lithium-ion batteries(LIBs)for their high theoretical specific capacity.However,the poor cycling stability of nickel-rich cathode materials is one of the major barriers for the large-scale usage of LIBs.The existing obstructions that suppress the capacity degradation of nickel-rich cathode materials are as a result of phase transition,mechanical instability,intergranular cracks,side reaction,oxygen loss,and thermal instability during cycling.Core–shell structures,oxidating precursors,electrolyte additives,doping/coating and synthesizing single crystals have been identified as effective methods to improve cycling stability of nickel-rich cathode materials.Herein,recent progress of surface modification,e.g.coating and doping,in nickel-rich cathode materials are summarized based on Periodic table to provide a clear understanding.Electrochemical performances and mechanisms of modified structure are discussed in detail.It is hoped that an overview of synthesis and surface modification can be presented and a perspective of nickel-rich materials in LIBs can be given.
基金financial support from the National Natural Science Foundation of China(Nos.51922042 and 51872098)Fundamental Research Funds for Central Universities,China(No.2020ZYGXZR074)the Scientific and Technological Plan of Qingyuan City,China(2019DZX008)。
文摘Potassium ion batteries(PIBs) have been regarded as promising alternatives to lithium ion batteries(LIBs)on account of their abundant resource and low cost in large scale energy storage applications. However,it still remains great challenges to explore suitable electrode materials that can reversibly accommodate large size of potassium ions. Here, we construct oxygen-deficient V_(2)O_(3)nanoparticles encapsulated in amorphous carbon shell(Od-V_(2)O_(3)@C) as anode materials for PIBs by subtly combining the strategies of morphology and deficiency engineering. The MOF derived nanostructure along with uniform carbon coating layer can not only enables fast K+migration and charge transfer kinetics, but also accommodate volume change and maintain structural stability. Besides, the introduction of oxygen deficiency intrinsically tunes the electronic structure of materials according to DFT calculation, and thus lead to improved electrochemical performance. When utilized as anode for PIBs, Od-V_(2)O_(3)@C electrode exhibits superior rate capability(reversible capacities of 262.8, 227.8, 201.5, 179.8, 156.9 mAh/g at 100, 200, 500, 1000 and2000 mA/g, respectively), and ultralong cycle life(127.4 mAh/g after 1000 cycles at 2 A/g). This study demonstrates a feasible way to realize high performance PIBs through morphology and deficiency engineering.
基金supported by the Natural Science Foundation of Zhejiang Province(LY22E020006).
文摘Dielectric capacitors with high capacitive energy storage are urgently needed to meet the growing demand for high-performance energy storage devices.Herein,a novel lead-free Sr_(5)BiTi_(3)Nb_(7)O_(30)(SBTN)tungsten bronze relaxor ferroelectric ceramic is prepared and explored for potential energy storage applications.A high recoverable energy density Wrec(~3.72 J/cm^(3))and ultrahigh efficiencyη(~94.2%)at 380 kV/cm are achieved simultaneously.Both Wrec andηexhibit superior stabilities against temperature(30-140°C),cycles(100-105)and frequency(1-500 Hz).In addition,a high current density of 796 A/cm^(2) and a large power density of 71.7 MW/cm^(3) are achieved,together with good thermal endurance and fatigue resistance.These results demonstrate that the obtained SBTN ceramic can be deemed as the promising candidates for dielectric capacitor applications.
