Advancing Li-ion storage performance with hybrid vertical carbon/Ni_(3)S_(2)-based electrodes

Conversion-reaction induced charge storage mechanisms of transition metal sulphides have received considerable interest in designing high-capacity electrodes for electrochemical energy storage devices.However,their low conductivity and structural degradation during cycling limit their applications as energy storage devices.A combination of different nickel sulphide phases tailored with carbon nanostructures is suggested to address these limitations.Herein,a facile,two-step approach is demonstrated for fabricating a hybrid electrode,consisting of trinickel disulphide(Ni_(3)S_(2))formed on a metallic Ni nanoparticle supported by vertical carbon nanotubes(VCN)backbone in the form Ni_(3)S_(2)/Ni@VCN.Ni_(3)S_(2)/Ni@VCN electrodes were tested as anode for lithium-ion batteries,and the electrode featured outstanding lithiumstorage capabilities with a high reversible capacity(1113 m Ah g^(-1) after 100 cycles at 100 m A g^(-1)),excellent long-term cycling stability(770 m Ah g^(-1) after 500 cycles at 200 m A g^(-1)),and good rate capability.The resulting electrode performance is one of the best Li-ion storage capabilities in the Ni_(3)S_(2)-type anode materials described.A unique “broccoli-like”structure of polycrystalline Ni_(3)S_(2)capped on conductive VCN backbone helps the interface storage process and boosts lithium storage performance.

N-Graphene Nanowalls via Plasma Nitrogen Incorporation and Substitution: The Experimental Evidence

Incorporating nitrogen(N)atom in graphene is considered a key technique for tuning its electrical properties.However,this is still a great challenge,and it is unclear how to build N-graphene with desired nitrogen configurations.There is a lack of experimental evidence to explain the influence and mechanism of structural defects for nitrogen incorporation into graphene compared to the derived DFT theories.Herein,this gap is bridged through a systematic study of different nitrogen-containing gaseous plasma post-treatments on graphene nanowalls(CNWs)to produce N-CNWs with incorporated and substituted nitrogen.The structural and morphological analyses describe a remarkable difference in the plasma–surface interaction,nitrogen concentration and nitrogen incorporation mechanism in CNWs by using different nitrogen-containing plasma.Electrical conductivity measurements revealed that the conductivity of the N-graphene is strongly influenced by the position and concentration of C–N bonding configurations.These findings open up a new pathway for the synthesis of N-graphene using plasma post-treatment to control the concentration and configuration of incorporated nitrogen for application-specific properties.

Stable dielectric response of low-loss aromatic polythiourea thin films on Pt/SiO_(2) substrate

We have investigated dielectric properties of aromatic polythiourea(ArPTU,a polar polymer containing high dipolar moments with very low defect levels)thin films that were developed on Pt/SiO_(2) substrate.The detected response is compared to the response of commercially available polymers,such as high density polyethylene(HDPE)and polypropylene(PP),which are at present used in foil capacitors.Stable values of the dielectric constantε'≈5(being twice higher than in HDPE and PP)over broad temperature and frequency ranges and dielectric losses as low as in commercial systems suggest ArPTU as a promising candidate for future use in a variety of applications.

Halophily reloaded:new insights into the extremophilic life-style of Wallemia with the description of Wallemia hederae sp.nov

Wallemia comprises air-and food-borne,mycotoxigenic contaminants including the halophilic W.ichthyophaga,xerotolerant W.sebi and xerophilic W.muriae.Wallemia isolates are easily overlooked and only a comparably small number of strains have been deposited in culture collections so far.In order to better understand the natural distribution of Wallemia spp.and to encounter their natural habitats,we tested more than 300 low-water-activity substrates and 30 air samples from a wide geographical coverage.We isolated more than 150 new Wallemia strains.Wallemia sebi and W.muriae were isolated mostly from hypersaline water,low-water-activity foods,plant materials and indoor.Wallemia muriae is the dominant Wallemia species in the air of natural and human influenced environments in Europe.New isolates of W.ichthyophaga were obtained from hypersaline environments such as brine,salt crystals,salty foods and MgCl_(2)-rich bitterns,and from the air of hay barns in Denmark.Five halotolerant strains were recognised as a hitherto un-described species Wallemia hederae,the phylogenetic sister of the halophilic W.ichthyophaga.Wallemia spp.show in-vitro growth on media that contain the chaotropic salt MgCl_(2).Wallemia ichthyophaga can grow in liquid medium enriched with 2 M MgCl_(2).Never before has a microorganism been grown on comparably high MgCl_(2) concentrations.Tests of the activity of a wide range of extracellular enzymes in the presence of NaCl also suggested that Wallemia iswell-adapted to substrates with a reduced water activity.