As an efficient and stable energy storage device, lithium-ion batteries (LIBs) have become an important part of today's society and are widely used in production and life. The research on the performance of LIBs is also widely concerned by researchers. The electrode material that plays a decisive role in the performance of the battery is our key research object, and many kinds of new negative electrode materials have been explored. Metal organic frameworks (MOFs) are a type of coordination polymers that have attracted wide attention in recent years [1][2]. With MOFs as the precursor, porous metal oxides and porous carbon materials with a controllable structure can be obtained. As electrode materials, they can significantly improve the electrochemical performance of batteries. Therefore, MOFs have become the preferred material of our new electrode materials. In this paper, hydrothermal method is adopted to prepare spherical porous Ni-MOFs material, which is calcined into metal oxide NiO material, and then its electrical conductivity and electrochemical performance are improved on the basis of retaining spherical pore structure. At the constant current density of 1C, the reversible capacity of NiO material maintains stably at 160mAh/g and the coulomb efficiency reaches 97.12% at 200 circles. In this paper, Ni-MOFs is synthesized with graphene oxide (GO) to generalize GO/Ni-MOFs material, and then it is transformed into reduced graphene oxide (RGO) to obtain RGO/NiO. RGO acts as a soft protective layer of active substances, which greatly improves the structural stability of the electrode during charging and discharging process. At the constant current density of 1C and at 200 circles, the reversible capacity reaches 440mAh/g, the coulomb efficiency reaches 99.49%, and its multiplying power and impedance performance are also very out.
In this paper, the hot deformation behavior of a TNM TiAl-based alloy (Ti-44.45Al-3.80Nb-1.01Mo-0.29Si-0.14B) is investigated via isothermal compression tests. The experimental results demonstrate that the critical strain for dynamic recrystallization gradually decreases with increasing deformation temperature. At the initial stage of the low-temperature deformation process, the deformation is mainly caused by dislocation glide in the g and b phases. When the deformation reaches a certain level, dislocation glide in the b and the DRX g phases dominates the deformation. In the high-temperature deformation process, the deformation is the result of dislocation glide in the a and b phases.
Lithium ion batteries (LIBs) is a kind of rechargeable secondary battery, developed from lithium battery, lithium ions move between the positive and negative electrodes to realize the charging and discharging of external circuits. Zeolitic imidazolate frameworks (ZIFs) are porous crystalline materials in which organic imidazole esters are cross-linked to transition metals to form a framework structure. In this article, ZIF-67 is used as a sacrificial template to prepare nano porous carbon (NPC) coated cobalt nanoparticles. The final product Co/NPC composites with complete structure, regular morphology and uniform size were obtained by this method. The conductive network of cobalt and nitrogen doped carbon can shorten the lithium ion transport path and present high conductivity. In addition, amorphous carbon has more pores that can be fully in contact with the electrolyte during charging and discharging. At the same time, it also reduces the volume expansion during the cycle and slows down the rate of capacity attenuation caused by structure collapse. Co/NPC composites first discharge specific capacity up to 3115 mA h/g, under the current density of 200 mA/g, circular 200 reversible capacity as high as 751.1 mA h/g, and the excellent rate and resistance performance. The experimental results show that the Co/NPC composite material improves the electrical conductivity and electrochemical properties of the electrode. The cobalt based ZIF-67 as the precursor has opened the way for the design of highly performance electrodes for energy storage and electrochemical catalysis.
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