Zn_(3)V_(2)O_(8) was considered as a promising anode material for lithium-ion battery(LIB),because of its high theoretical specific capacity,environmental friendliness,and ease of availability.However,the large volume...Zn_(3)V_(2)O_(8) was considered as a promising anode material for lithium-ion battery(LIB),because of its high theoretical specific capacity,environmental friendliness,and ease of availability.However,the large volume change and low electronic conductivity of Zn_(3)V_(2)O_(8)in repeated charge/discharge cycles have severely limited its applications.To solve the above issues,hierarchical Zn_(3)V_(2)O_(8) microspheres assembled by two-dimensional(2D)nanosheets were successfully synthesized,and carbon nanotubes(CNTs)were further introduced to cross-link the Zn_(3)V_(2)O_(8) microspheres.The interconnected nature of the three-dimensional(3D)conducting network and the special hierarchical morphology were beneficial for improving the stability and conductivity of the composite,leading to the reduction of the impedance and a significant improvement of the electrochemical performance.The reversible capacity of the as-prepared composite can achieve 1049.5mAh·g^(-1)at a current density of 0.2 A·g^(-1)with a capacity retention of~81%after 100 cycles.It is suggested that morphology modulation coupled with interconnecting CNT network is an effective method to boost the electrochemical performance of the anode materials for lithium-ion batteries.展开更多
Fabrication of thin-wall components using the laser powder bed fusion(LPBF)additive manufacturing(AM)technology was investigated for two“hard-to-weld”high gamma prime Ni-based superalloys RENé65(R65)and REN...Fabrication of thin-wall components using the laser powder bed fusion(LPBF)additive manufacturing(AM)technology was investigated for two“hard-to-weld”high gamma prime Ni-based superalloys RENé65(R65)and RENé108(R108).Simple block parts with wall thicknesses of 0.25 mm,1.00 mm,and5.00 mm are printed using a bidirectional laser scanning strategy without layer-wise rotation.Parts with walls thinner than 5 mm fail before reaching the designated build height.Results indicate that reduction of limiting build height(LBH)corresponds to the reduction of part thickness and is unaffected by alloy composition.On the contrary,the number of internal micro-cracks along columnar grain boundaries in the build direction(BD)increases with part thickness and is significantly higher in R108 than R65.These findings suggest that reduced LBH in parts with thinner walls is not caused by internal micro-crack formation.Fractography and finite element analysis(FEA)of the in-process thermal stresses show that the LBH trend is not explained by the conventional cracking mechanism.Simulations suggest that part thickness affects stress distribution leading to more substantial distortion and consequent failure to add layers for continued fabrication of thinner parts.展开更多
基金financially supported by the National Natural Science Foundation of China(No.22279030)the Project of Key Laboratory of Superlight Materials and Surface Technology of Harbin Engineering UniversityHebei Key Laboratory of Dielectric and Electrolyte Functional Material,Northeastern University at Qinhuangdao(No.HKDEFM2021201)。
文摘Zn_(3)V_(2)O_(8) was considered as a promising anode material for lithium-ion battery(LIB),because of its high theoretical specific capacity,environmental friendliness,and ease of availability.However,the large volume change and low electronic conductivity of Zn_(3)V_(2)O_(8)in repeated charge/discharge cycles have severely limited its applications.To solve the above issues,hierarchical Zn_(3)V_(2)O_(8) microspheres assembled by two-dimensional(2D)nanosheets were successfully synthesized,and carbon nanotubes(CNTs)were further introduced to cross-link the Zn_(3)V_(2)O_(8) microspheres.The interconnected nature of the three-dimensional(3D)conducting network and the special hierarchical morphology were beneficial for improving the stability and conductivity of the composite,leading to the reduction of the impedance and a significant improvement of the electrochemical performance.The reversible capacity of the as-prepared composite can achieve 1049.5mAh·g^(-1)at a current density of 0.2 A·g^(-1)with a capacity retention of~81%after 100 cycles.It is suggested that morphology modulation coupled with interconnecting CNT network is an effective method to boost the electrochemical performance of the anode materials for lithium-ion batteries.
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)(No.CRDPJ 533406-18)
文摘Fabrication of thin-wall components using the laser powder bed fusion(LPBF)additive manufacturing(AM)technology was investigated for two“hard-to-weld”high gamma prime Ni-based superalloys RENé65(R65)and RENé108(R108).Simple block parts with wall thicknesses of 0.25 mm,1.00 mm,and5.00 mm are printed using a bidirectional laser scanning strategy without layer-wise rotation.Parts with walls thinner than 5 mm fail before reaching the designated build height.Results indicate that reduction of limiting build height(LBH)corresponds to the reduction of part thickness and is unaffected by alloy composition.On the contrary,the number of internal micro-cracks along columnar grain boundaries in the build direction(BD)increases with part thickness and is significantly higher in R108 than R65.These findings suggest that reduced LBH in parts with thinner walls is not caused by internal micro-crack formation.Fractography and finite element analysis(FEA)of the in-process thermal stresses show that the LBH trend is not explained by the conventional cracking mechanism.Simulations suggest that part thickness affects stress distribution leading to more substantial distortion and consequent failure to add layers for continued fabrication of thinner parts.
