Curing Kinetics, Mechanical Properties and Thermal Stability of Epoxy/Graphene Nanoplatelets(GNPs) Powder Coatings

Epoxy/graphene nanoplatelets（GNPs） powder coatings were fabricated using ultrasonic predispersion of GNPs and melt-blend extrusion method. The isothermal curing kinetics of epoxy/GNPs powder coating were monitored by means of real-time Fourier transform infrared spectroscopy（FT-IR） with a heating cell. The mechanical properties of the epoxy/GNPs cured coatings had been investigated, by evaluating their fracture surfaces with field-emission scanning electron microscopy（FE-SEM） after three-point-bending tests. The thermal stability of the epoxy/GNPs cured coatings was studied by thermo-gravimetric analysis（TGA）. The isothermal curing kinetics result showed that the GNPs would not affect the autocatalytic reaction mechanism, but the loading of GNPs below 1.0 wt % additive played a prompting role in the curing of the epoxy/GNPs powder coatings. The fracture strain, fracture toughness and impact resistance of the epoxy/GNPs cured coatings increased dramatically at low levels of GNPs loading（1 wt %）, indicating that the GNPs could improve the toughness of the epoxy/GNPs powder coatings. Furthermore, from FE-SEM studies of the fracture surfaces, the possible toughening mechanisms of the epoxy/GNPs cured coatings were proposed. TGA result showed that the incorporation of GNPs improved the thermal stability of the cured coatings. Hence, the GNPs modified epoxy can be an efficient approach to toughen epoxy powder coating along with improving their thermal stability.

Structural Modification of Al65Cu16.5Ti18.5 Amorphous Powder through Annealing and Post Milling： Improving Thermal Stability

To improve thermal stability of the Al65Cu16.5Ti18.5 amorphous powder,structural modification of the amorphous powder was performed through annealing and post milling.Annealing above the crystallization temperature（Tx） not only induced nanoscale intermetallics to precipitate in the amorphous powder,but also increased Cu atomic percentage within the residual amorphous phase.Post milling induced the amorphization of the nanocrystal intermetallics and the formation of Cu9Al4 from the residual amorphous phase.Thus,a mixed structure consisting of amorphous phase and Cu9Al4 was obtained in the powder after annealing and post milling（the APMed powder）.The phase constituent in the APMed powder did not change during the post annealing,which exhibited significantly improved thermal stability in comparison with the as-milled amorphous powder.

Recent advances and perspectives on prelithiation strategies for lithium-ion capacitors

Lithium-ion capacitors(LICs),consisting of a capacitor-type material and a battery-type material together with organic electrolytes,are the state-of-the-art electrochemical energy storage devices compared with supercapacitors and batteries.Owing to their unique characteristics,LICs received a lot of attentions,and great progresses have been achieved,especially in the exploration of cathode and anode materials.Prelithiation techniques are regarded as indispensable procedures for LICs systems,which can compensate for the initial irreversible capacity loss,increase the Li^(+)concentration in the electrolyte,raise the working voltage and resolve the safety and cycle stability issues;however,its research progress is slow,and there is not enough attention until now.In this overview,we look into the ongoing processes on the recent development of prelithiation technologies,especially in organic electrolyte consumption-type LICs.In particular,some prelithiation strategies for LICs are summarized and discussed in detail,including the ex situ electrochemical method,in situ electrochemical method,and cathode prelithiation additives method.Moreover,we propose some unresolved challenges and prospects for prelithiation technologies from the basic research ideas and future key research directions.This work aims to bring up new insights to reassess the significance of premetallation strategies for advanced hybrid-ion capacitors based on the currently proposed prelithiation strategies.