Ionic liquid treated carbon nanotube sponge as high areal capacity cathode for lithium sulfur batteries

Carbon nanotube sponges filled sandwich panels with superior high-power continuous wave laser resistance

Effect of highly-porous and lightweight carbon nanotube sponges on the high-power continuous wave laser ablation resistance of the sandwich panel was investigated experimentally. As a comparison, thermal responses of monolithic plate, carbon nanotube film filled sandwich panel, unfilled sandwich panel and carbon nanotube sponge filled sandwich panel subjected to continuous wave laser irradiation were analyzed. Experimental results showed that the laser resistance of the carbon nanotube filled sandwich panel is obviously higher than the unfilled structure. The added failure time of the sandwich panel by filling the cores with the carbon nanotube sponge of unit mass was about 18 times and 33 times longer than that by filling with the conventional ablative and insulated material. It could be understood by the high thermal diffusion coefficient and latent heat of sublimation of the carbon nanotube sponge. During ablation by the continuous wave, the carbon nanotube sponge not only fast consumed the absorbed laser energy through phase change of a large-area material due to its high latent heat of sublimation, but also quickly dispersed the heat energy introduced by the continuous wave laser due to its high thermal diffusion coefficient, leading to the extraordinary laser ablation resistance.

Construction of all-carbon micro/nanoscale interconnected sulfur host for high-rate and ultra-stable lithium-sulfur batteries: Role of oxygen-containing functional groups

Carbon nanotubes (CNTs) are often used to settle down the sluggish reaction kinetics in lithium-sulfur batteries (LSBs). However, the self-aggregation of CNTs often makes them fail to effectively inhibit the shuttling effect of soluble lithium polysulfide (LiPS) intermediates. Herein, a type of ultra-stable carbon micro/nano-scale interconnected "carbon cages" has been designed by incorporating polar acid-treated carbon fibers (ACF) into three-dimensional (3D) CNT frameworks during vacuum filtration processes. Results show that the ACF-CNT composite frameworks possess a reinforced-concrete-like structure, in which the ACFs can well work as the main mechanical supporting frames for the composite electrodes, and the oxygen-containing functional groups (OFGs) formed on them as cross linker between ACFs and CNTs. Benefitted from this design, the ACF-CNT/S cathodes deliver an excellent rate capability (retain 72.6% at 4C). More impressively, the ACF-CNT/S cathodes also show an ultrahigh cycling stability (capacity decay rate of 0.001% per cycle over 350 cycles at 2C). And further optimization suggests that the suitable treatment on CFs could balance the chemical adsorption (OFGs) and physical confinement (carbon cages), leading to fast and durable electrochemical reaction dynamics. In addition, the assembled soft-pack LSBs further show a high dynamic bending stability.

Understanding of Lithium Insertion into 3D Porous Carbon Scaffolds with Hybridized Lithiophobic and Lithiophilic Surfaces by In-Operando Study

In-operando study coupled with voltage/current profiles are presented in order to unveil lithium insertion processes into 3D porous carbon nanotube (CNT) structures whose surfaces were altered to have lithiophobic, lithiophilic, and hybridized lithiophobic/philic characteristics using graphitic surfaces with/without carboxyl/hydroxyl groups. We found the lithiophobic graphitic surfaces hindered lithium insertion into the scaffold despite the high conductivity of CNT. The lithiophilic surface caused another problem of lithium deposition on the outer surface of the electrode, clogging pores and engendering dendrites. Conversely, in the hybridized CNT, lithiophilic trenches partially created on the pristine CNT allowed for uniform lithium deposition into the pores by simultaneously improved lithium attraction and charge transfer, reaching a high areal capacity of 16 mAh cm^-2 even with a current density of 8 mA cm^-2 without noticeable dendrite formation and volume expansion. Our hybridization approach provides valuable insight to realize a high-energy-density anode by uniformly impregnating lithium into porous media.

Chitosan production from Paecilomyces saturatus using three monosaccharides via mixture design

In this study, we demonstrate that chitosan is produced from Paecilomyces saturatus fungi using ternary monosaccharide carbon sources liquid cultivation via mixture design strategy. Sixteen experiments were carried out to obtain regression equations of fungal dry mycelial biomass (W), chitosan ratio (R), and deacetylation degree (DD) for plotting contour lines. Contour lines reveal that the maximum W, R, and DD can be simultaneously obtained in cultivated media containing 20% glucose, 60% fructose and 20% mannitol rather than pure monosaccharide cultivation. Three additional confirmation experiments based on the maximum FuCS deacetylation degree had been performed to confirm to be 92.3% via Fourier-transform infrared spectra. Accordingly, FuCS possessed much better anti-microbial activity on E. coli than commercial chitosan (CrCS). Meanwhile, X-ray diffraction results confirmed that FuCS possessed both α and γ crystalline peaks while CrCS possessed only α crystalline peak, being collaborated with thermogravimetric analysis results. The superior FuCS was obtained by using ternary monosaccharides system in fungal culture via mixture design for the first time. This study provides a new approach to produce chitosan from fungal cultivation by using the mixture design strategy.