Titanium dioxide(TiO_2) has been investigated broadly as a stable,safe,and cheap anode material for sodium-ion batteries in recent years.However,the poor electronic conductivity and inherent sluggish sodium ion diffus...Titanium dioxide(TiO_2) has been investigated broadly as a stable,safe,and cheap anode material for sodium-ion batteries in recent years.However,the poor electronic conductivity and inherent sluggish sodium ion diffusion hinder its practical applications.Herein,a self-template and in situ vulcanization strategy is developed to synthesize self-supported hybrid nanotube arrays composed of nitrogen/sulfur-codoped carbon coated sulfur-doped TiO_2 nanotubes(S-TiO_2@NS-C) starting from H_2 Ti_2 O_5-H_2 O nanoarrays.The S-TiO_2@NS-C composite with one-dimensional nano-sized subunits integrates several merits.Specifically,sulfur doping strongly improves the Na~+ storage ability of TiO_2@C-N nanotubes by narrowing the bandgap of original TiO_2.Originating from the nanoarrays structures built from hollow nanotubes,carbon layer and sulfur doping,the sluggish Na~+ insertion/extraction kinetics is effectively improved and the volume variation of the electrode material is significantly alleviated.As a result,the S-TiO_2@NS-C nanoarrays present efficient sodium storage properties.The greatly improved sodium storage performances of S-TiO_2@NS-C nanoarrays confirm the importance of rational engineering and synthesis of hollow array architectures with higher complexity.展开更多
In this study, S-doped NbSea （NbSo.aSel.8） powders were fabricated, and the corresponding Cu-based composites （Cu/NbSo.eSe1.8） were obtained by powder metallurgy technique. The phase compositions, physical, and tr...In this study, S-doped NbSea （NbSo.aSel.8） powders were fabricated, and the corresponding Cu-based composites （Cu/NbSo.eSe1.8） were obtained by powder metallurgy technique. The phase compositions, physical, and tribological properties of Cu-based composites were investigated systematically. The results show that Cu matrix reacts with NbSo.2Sel.8 to produce Cu2Se and Cu0.38NbSo.2Se1.8 during sintering process, which influences the physical and tribological properties of Cu-based composites significantly. Specially, with NbS0.2Se1.8 content increasing, the density of Cu/ NbSo.2Se1.8 composites decreases, and the hardness increases firstly and then decreases, while the electric resistivity in- creases slightly. In addition, the incorporation of NbSo.2Se1.8 enhances the tribological properties of Cu greatly, which is attributed to the lubricating effect of Cuo,38NbSo.2Se1.8 and the reinforcement effect of Cu2Se. In particular, when the content of NbSo.2Sel.8 is 6 wt%, the Cu-based composite has the best tribological properties.展开更多
Metal selenides have been explored as promising sodium storage materials owing to their high theoretical capacity.However,sluggish Naþdiffusion and low electronic conductivity of selenides still hinder their prac...Metal selenides have been explored as promising sodium storage materials owing to their high theoretical capacity.However,sluggish Naþdiffusion and low electronic conductivity of selenides still hinder their practical applications.Herein,FeSe_(2-x)S_(x)microspheres have been prepared via a self-doping solvothermal method using NH4Fe(SO4)2 as both the Fe and S source,followed by gas phase selenization.The density functional theory calculation results reveal that S doping not only improves the Na adsorption,but also lower the diffusion energy barrier of Na atoms at the S doping sites,at the same time enhance the electronic conductivity of FeSe_(2-x)S_(x).The carbon-free nature of the FeSe_(2-x)S_(x)microspheres results in a low specific surface area and a high tap density,leading to an initial columbic efficiency of 85.6%.Compared with pure FeSe_(2),such FeSe_(2-x)S_(x)delivers a high reversible capacity of 373.6 mAh⋅g^(-1)at a high current density of 5 A⋅g^(-1)after 2000 cycles and an enhanced rate performance of 305.8 mAh⋅g^(-1)at even 50 A⋅g1.Finally,the FeSe_(2-x)S_(x)//NVP pouch cells have been assembled,achieving high energy and volumetric energy densities of 118 Wh⋅kg1 and 272 mWh⋅cm3,respectively,confirming the potential of applications for the FeSe_(2-x)S_(x)microspheres.展开更多
基金financial supports provided by the National Natural Science Foundation of China (21871164)the Taishan Scholar Project Foundation of Shandong Province (ts20190908, ts201511004)the Natural Science Foundation of Shandong Province (ZR2019MB024)。
文摘Titanium dioxide(TiO_2) has been investigated broadly as a stable,safe,and cheap anode material for sodium-ion batteries in recent years.However,the poor electronic conductivity and inherent sluggish sodium ion diffusion hinder its practical applications.Herein,a self-template and in situ vulcanization strategy is developed to synthesize self-supported hybrid nanotube arrays composed of nitrogen/sulfur-codoped carbon coated sulfur-doped TiO_2 nanotubes(S-TiO_2@NS-C) starting from H_2 Ti_2 O_5-H_2 O nanoarrays.The S-TiO_2@NS-C composite with one-dimensional nano-sized subunits integrates several merits.Specifically,sulfur doping strongly improves the Na~+ storage ability of TiO_2@C-N nanotubes by narrowing the bandgap of original TiO_2.Originating from the nanoarrays structures built from hollow nanotubes,carbon layer and sulfur doping,the sluggish Na~+ insertion/extraction kinetics is effectively improved and the volume variation of the electrode material is significantly alleviated.As a result,the S-TiO_2@NS-C nanoarrays present efficient sodium storage properties.The greatly improved sodium storage performances of S-TiO_2@NS-C nanoarrays confirm the importance of rational engineering and synthesis of hollow array architectures with higher complexity.
基金financially supported by the National Nature Science Foundation of China(Nos.51405199 and21301075)the Natural Science Foundation of Jiangsu Province(Nos.BK20140551 and BK20140562)+4 种基金the Postdoctoral Science Foundation of China(No.2014M561579)the Postdoctoral Science Foundation of Jiangsu Province(No.1401106C)the Opening Foundation of Jiangsu Province Material Tribology Key Laboratory(No.Kjsmcx201304)the Senior Intellectuals Fund of Jiangsu University(No.13JDG099)the Industry-Academy-Research Union Foundation of Jiangsu Province(No.BY2013065-05)
文摘In this study, S-doped NbSea （NbSo.aSel.8） powders were fabricated, and the corresponding Cu-based composites （Cu/NbSo.eSe1.8） were obtained by powder metallurgy technique. The phase compositions, physical, and tribological properties of Cu-based composites were investigated systematically. The results show that Cu matrix reacts with NbSo.2Sel.8 to produce Cu2Se and Cu0.38NbSo.2Se1.8 during sintering process, which influences the physical and tribological properties of Cu-based composites significantly. Specially, with NbS0.2Se1.8 content increasing, the density of Cu/ NbSo.2Se1.8 composites decreases, and the hardness increases firstly and then decreases, while the electric resistivity in- creases slightly. In addition, the incorporation of NbSo.2Se1.8 enhances the tribological properties of Cu greatly, which is attributed to the lubricating effect of Cuo,38NbSo.2Se1.8 and the reinforcement effect of Cu2Se. In particular, when the content of NbSo.2Sel.8 is 6 wt%, the Cu-based composite has the best tribological properties.
基金supported by the National Key R&D Program of China(No.2021YFB2401900).
文摘Metal selenides have been explored as promising sodium storage materials owing to their high theoretical capacity.However,sluggish Naþdiffusion and low electronic conductivity of selenides still hinder their practical applications.Herein,FeSe_(2-x)S_(x)microspheres have been prepared via a self-doping solvothermal method using NH4Fe(SO4)2 as both the Fe and S source,followed by gas phase selenization.The density functional theory calculation results reveal that S doping not only improves the Na adsorption,but also lower the diffusion energy barrier of Na atoms at the S doping sites,at the same time enhance the electronic conductivity of FeSe_(2-x)S_(x).The carbon-free nature of the FeSe_(2-x)S_(x)microspheres results in a low specific surface area and a high tap density,leading to an initial columbic efficiency of 85.6%.Compared with pure FeSe_(2),such FeSe_(2-x)S_(x)delivers a high reversible capacity of 373.6 mAh⋅g^(-1)at a high current density of 5 A⋅g^(-1)after 2000 cycles and an enhanced rate performance of 305.8 mAh⋅g^(-1)at even 50 A⋅g1.Finally,the FeSe_(2-x)S_(x)//NVP pouch cells have been assembled,achieving high energy and volumetric energy densities of 118 Wh⋅kg1 and 272 mWh⋅cm3,respectively,confirming the potential of applications for the FeSe_(2-x)S_(x)microspheres.
