In order to study the microstructure evolution rule of pure aluminum plates during different cold-rolled (CR) deformation degrees and annealing processes, samples with aCR deformation of 50~85%, heating rates of 60~100 °C/min and annealing at the target temperature of 350~500 °C were investigated. The microstructure, crystallite dimension and grain boundary characteristics were characterized by the methods of polarizing microscope (PM) and electron backscattered diffraction (EBSD). The results showed that the crystallite dimension of the initial state was 102 μm and ends up completely broken with an increase in the CR deformation degree. When the CR deformation increases to 85%, the deformed micro-bands were very small, with a band spacing of 5~10 μm. At this time, the grain distortion is more serious, there are more high-density grain defects, such as dislocations, and there is a high deformation of the storage energy, which is the energy preparation for the subsequent finished products to withstand the annealing process. The recrystallization fraction was higher with an increase in annealing temperature. After completed recrystallization, the grains showed an equiaxed shape. Orientation imaging and misorientation angle analysis showed that the red-oriented grains of the (001) plane, which had preferred nucleation, recrystallization and rapid grain growth. Final grains of the completed recrystallization are relatively coarse. Under the same deformation, the average crystallite dimension of the recrystallized grains decreases with an increase in annealing heating rate.
Although magnesium rechargeable battery (MRB) raise considerable attention, the research on MRBs is still in its infancy. One of issues is that magnesium ions is difficult to reversibly (de)-intercalate in...
The thermodynamic, electronic, and kinetic properties were systematically investigated during the process of Li and Mg atoms into VOCl. The upper limit of Li and Mg intercalation into VOCl is xLi =1 and xMg=0.5, respectively. At high concentration, the further lithiation and magnesiation will cause the phase evolution. The pair correlation function (PCF) diagrams prove the formation of V metal at high concentration of xLi and xMg. The four discharge plateaus of lithiation are observed at 2.10, 2.23, 1.62 and 1.23 V vs. Li+/Li in the concentration range of 0≤xLi≤1, while the average voltage of the embedded Mg is 1.10 V vs. Mg2+/Mg in the concentration range of 0≤xMg≤0.25, which are consistent with the experimental values. The diffusion energy barriers of Li ions and Mg ions in VOCl are 0.22 and 0.72 eV, respectively, which are much lower than those of other intercalation materials. Based on the thermodynamic/kinetic properties and the AIMD simulation results, the electrochemical process of layered VOCl is an intercalation-conversion reaction process upon the lithiation and magnesiation processes.
The low specific capacity and Mg non-affinity of graphite
limit
the energy density of ion rechargeable batteries. Here, we first identify
that the monolayer C12‑3‑3 in sp
2–sp
3 carbon hybridization
with high Li/Mg affinity is an appropriate anode material for Li-ion
batteries and Mg-ion batteries via the first-principles simulations.
The monolayer C12‑3‑3 can achieve high specific
capacities of 1181 mAh/g for Li and 739 mAh/g for Mg, higher than
those of most previous anodes. The Li storage reaction is an “adsorption–conversion–intercalation
mechanism”, while the Mg storage reaction is an “adsorption
mechanism”. The 2D carbon material of C12‑3‑3 displays fast diffusion kinetics with low diffusion barriers of
0.41 eV for Li and 0.21 eV for Mg. As a new carbon-based anode material,
the monolayer C12‑3‑3 will promote the practical
application of batteries with high-capacity and high-rate performance.
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