High temperature mechanical properties and microstructure of die forged Al-5.87Zn-2.07Mg-2.42Cu alloy

The high temperature mechanical properties(250 ℃) and microstructure of a die-forged Al-5.87 Zn-2.07 Mg-2.42 Cu alloy after T6 heat treatment were investigated. High temperature tensile tests show that as the temperature increases from room temperature to 250 ℃, the ultimate tensile strength of the alloy decreases from 638 to 304 MPa, and the elongation rises from 13.6% to 20.4%. Transmission electron microscopy(TEM) and electron backscattered diffraction(EBSD) were applied for microstructure characterization, which indicates that the increase of tensile temperature can lead to the coarsening of precipitates, drop of dislocation density, and increase of dynamic recovery. After tensile testing at 250 ℃, a sub-grain structure composed of a high fraction of small-angle grain boundary is formed.

Freestanding carbon fiber-confined yolk-shelled silicon-based anode for promoted lithium storage applications

A flexible carbon fiber-confined yolk-shelled silicon-based composite is reported as an anode material for lithium storage applications.Silicon nanoparticles(Si NPs)are confined by the N-doped hollow carbon cages(SiNHC)and these uniform dispersed yolk-shell-structured Si-NHC units were encapsulated by the carbon fibers within an interconnected three-dimensional(3D)framework(Si-NHC@CNFs).For the encapsulated yolkshelled Si-NHC,the void space between the inner Si NPs and outer NHC can accommodate the structural changes of Si NPs during charging/discharging processes,leading to effectively improved structural stability and cycling life.More importantly,all the Si-NHC units were bridged together through a conductive CNFs"highway"to enhance the overall conductivity and tap density further.As observed,Si-NHC@CNFs exhibited an initial discharge capacity of 1364.1 mAh·g^(-1)at 1000 mA·g^(-1)and678.9 mAh·g^(-1)at 2000 mA·g^(-1).Furthermore,the reversible capacity was well maintained at 752.2 mAh·g^(-1)at500 mA·g^(-1)after 6000 ultra-long cycles.

Ru-doped phosphorene for electrochemical ammonia synthesis

The electrochemical ammonia synthesis has attracted increasing attention due to its energy saving characteristics.However,developing novel electrocatalysts and their mechanism remain great challenges.Here,several transition metal(TM)atoms doped on phosphorene were studied as N2 fixation electrocatalysts by using density functional theory(DFT)calculations.The results demonstrate that single Ru atom doped phosphorene shows an excellent catalytic activity for ammonia synthesis via the enzymatic pattern.A small overpotential of 0.696 V is achieved for this process.The effect of oxidation in the catalyst was also discussed in our work.Oxidation deactivates the catalyst,which should be avoided in the experiment.Our outcomes offer a novel perspective for single-atom catalytic ammonia synthesis with phosphorene as a substrate.

Nonsolvent-induced phase separation-derived TiO_(2) nanotube arrays/porous Ti electrode as high-energy-density anode for lithium-ion batteries

TiO_(2) nanotube arrays,growing on three-dimensional(3 D)porous Ti membrane,were synthesized using a facile nonsolvent-induced phase separation and anodization process.The length of those three-dimensional nanotube arrays could be tuned by prolonging the anodizing time.When the anodizing time is 8 h,the three-dimensional TiO_(2) nanotube arrays/porous Ti electrode exhibits well cycling stability and ultra-high specific capacity,which is used in lithium-ion batteries,attributed to the high utilization rate of the substrate and the high growth intensity of the active materials.Three-dimensional TiO_(2) nano tube arrays/porous Ti electrode,at 100μA·cm^(-2) with 8 h anodizing time,shows a typical discharge plateau at 1.78 V and exhibits the specific capacity with 2126.7μAh·cm^(-2),The novel nanotube arrays@3 D porous architecture effectively shortens the electron/ion transmission path,which could pave way for optimizing the design of highperformance anode materials for next-generation energy storage system.

Fabrication of Nb2O5/C nanocomposites as a high performance anode for lithium ion battery

Nb_2O_5/C nanosheets are successfully prepared through a mixing process and followed by heating treatment.Such Nb_2O_5/C based electrode exhibits high rate performance and remarkable cycling ability,showing a high and stable specific capacity of ~380mAhg^（-1） at the current density of 50 mAg^（-1）（much higher than the theoretical capacity of Nb_2O_5）.Further more,at a current density of 500mAg^（-1）,the nanocomposites electrode still exhibits a specific capacity of above 150 mAh g^（-1） after 100 cycles.These results suggest the Nb_2O_5/C nanocomposite is a high performance anode material for lithium-ion batteries.