Almost 15 years have gone ever since the discovery of graphene as a single atom layer. Numerous papers have been published to demonstrate its high electron mobility, excellent thermal and mechanical as well as optical properties. We have recently seen more and more applications towards using graphene in commercial products. This paper is an attempt to review and summarize the current status of the research of the thermal properties of graphene and other 2D based materials including the manufacturing and characterization techniques and their applications, especially in electronics and power modules. It is obvious from the review that graphene has penetrated the market and gets more and more applications in commercial electronics thermal management context. In the paper, we also made a critical analysis of how mature the manufacturing processes are; what are the accuracies and challenges with the various characterization techniques and what are the remaining questions and issues left before we see further more applications in this exciting and fascinating field.
The development of Li−S batteries is largely impeded by the complicated shuttle effect of lithium polysulfides (LiPSs) and sluggish reaction kinetics. In addition, the low mass loading/utilization of sulfur is another key factor that makes Li−S batteries difficult to commercialize. Here, a porous catalytic V 2 O 3 / V 8 C 7 @carbon composite derived from MIL-47 (V) featuring heterostructures is reported to be an efficient polysulfide regulator in Li−S batteries, achieving a substantial increase in sulfur loading while still effectively suppressing the shuttle effect and enhancing kinetics. Systematic mechanism analyses suggest that the LiPSs strongly adsorbed on the V 2 O 3 surface can be rapidly transferred to the V 8 C 7 surface through the built-in interface for subsequent reversible conversion by an efficient catalytic effect, realizing enhanced regulation of LiPSs from capture to conversion. In addition, the porous structure provides sufficient sulfur storage space, enabling the heterostructures to exert full efficacy with a high sulfur loading. Thus, this S−V 2 O 3 /V 8 C 7 @carbon@graphene cathode exhibits prominent rate performance (587.6 mAh g −1 at 5 C) and a long lifespan (1000 cycles, 0.017% decay per cycle). It can still deliver superior electrochemical performance even with a sulfur loading of 8.1 mg cm −2 . These heterostructures can be further applied in pouch cells and produce stable output at different folding angles (0−180°). More crucially, the cells could retain 4.3 mAh cm −2 even after 150 cycles, which is higher than that of commercial lithium-ion batteries (LIBs). This strategy for solving the shuttle effect under high sulfur loading provides a promising solution for the further development of high-performance Li−S batteries.
It is difficult to achieve high efficiency production of hydrophobic graphene by liquid phase exfoliation due to its poor dispersibility and the tendency of graphene sheets to undergo π−π stacking. Here, we report a water-phase, non-dispersion exfoliation method to produce highly crystalline graphene flakes, which can be stored in the form of a concentrated slurry (50 mg mL−1) or filter cake for months without the risk of re-stacking. The as-exfoliated graphene slurry can be directly used for 3D printing, as well as fabricating conductive graphene aerogels and graphene−polymer composites, thus avoiding the use of copious quantities of organic solvents and lowering the manufacturing cost. This non-dispersion strategy paves the way for the cost-effective and environmentally friendly production of graphene-based materials.
Highly efficient heterogeneous catalysts are desired for the development of new energy storage materials. The rational choice and use of capping ligands are of significant importance for performance optimization of metal nanoparticle (NP) catalysts. By exploiting amine-rich polyethylenimine (PEI) and graphene oxide (GO) as a NP support, we demonstrate that as a capping ligand, PEI deposited on GO provides a novel pathway able to simultaneously control the morphology, spatial distribution, surface active sites of cobalt (Co) NPs, and remarkably enhances their catalytic properties for the hydrolytic dehydrogenation of ammonia borane (AB). Such a synergistic effect enables the synthesized PEI-GO/Co catalysts to reveal extremely high dehydrogenation activities under atmosphere condition. A total turnover frequency of 39.9 molH2 min(-1) molCo(-1) and an apparent activation energy of 28.2 kJ mol(-1) make the catalytic performance of these PEI-GO/Co catalysts comparable to those of noble metal-based catalysts, including bimetallic and multimetallic catalysts.
In situ formed LiF grains are confined and evenly distributed throughout a covalent organic framework (COF) film, which exhibits cooperative effectiveness to greatly stabilize the lithium metal.
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