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Transition metal sulfides are of great interest as electrode material for alkali metal-ion batteries due to their high theoretical capacity. However, sluggish ion migration and electron transfer kinetics lead to poor cycling stability and rate performance, which hinders their practical applications. Herein, we develop a two-step localized carbonization and sulfurization method to construct a CoS

The shuttle effects of polysulfide intermediates (LiPSs) and sluggish kinetics during sulfur reduction reaction (SRR) process severely exacerbate the electrochemical performances of Li-S batteries. Herein, a unique nanocatalyst comprising β-NiOOH nanosheets uniformly implanted on the surface of carbon nanotubes (CNT@NiOOH) was designed and synthesized for sulfur cathodes. The β-NiOOH nanosheets have great capability of adsorbing LiPSs as well as superior catalytic activity for accelerating LiPS conversion, providing a more efficient method to restrain shuttle effects and improve the kinetics of SRR. Moreover, the nanometer-scale epitaxial growth and uniform distribution of β-NiOOH on CNTs provide a multidimensional catalytic skeleton with sufficient accessible active surfaces, unimpeded LiPS diffusion pathways, and resultant high utilization of active sites. Simultaneously, stable electron transportation pathways are also obtained by being synthesized on CNTs to avoid the faultiness of poor electron conductivity of β-NiOOH. These conspicuous advantages contribute to fully exert the catalytic and LiPS anchoring potential of CNT@NiOOH, bringing about the ultralong cycle performance and excellent capacity reversibility at a high discharge rate. Reticular CNT@NiOOH frameworks are assembled with the sulfur composite materials (SCMs) by a self-assembly method, and a super-high capacity of 813.3 mA h g

Recently, MnO2 has gained attention as an electrode material because of its very high theoretical capacity and abundant availability. However, the very high volumetric change caused by its conversion-type reaction results in bad reversibility of charge-discharge. In this study, δ-MnO2 of thickness 8 nm anchored on the surface of carbon nanotubes (CNT) by Mn-O-C chemical bonding is synthesized via a facile hydrothermal method. Numerous ex-situ characterizations of the lithium storage process were performed. Furthermore, density functional theory (DFT) calculations indicated that δ-MnO2 (0 1 2) thermodynamically prefers bonding with CNTs. Moreover, the interfacial interaction reinforces the connection of Mn-O and reduces the bond strength of Li-O in lithiated MnO2, which could facilitate an intercalation-type lithium storage reaction. Consequently, the as-synthesized δ-MnO2 retains an excellent reversible capacity of 577.5 mAh g − 1 in 1000 cycles at a high rate of 2 A g − 1 between 0.1 V and 3.0 V. The results of this study demonstrate the possibility of employing the cost-effective transition metal oxides as intercalation lithium storage dominant electrodes for advanced rechargeable batteries.

Li–air battery exhibits a promising prospect as energy conversion and storage devices due to its ultrahigh theoretical energy density. However, lithium metal as anode is hampered due to the intricate ambient electrochemical environment especially in the open and semi-open batteries. Herein a strategy that in situ fabricating dual-phase protective interface is proposed to improve the durability of lithium metal anode for Li–air battery. A thin film generates and contacts intimately on the surface via floating lithium foil on a silane mixed solution, then the inorganic particles Li6(Si2O7) appear adaptively and embeds in the Si-O-Si polymer during the initial lithium plating/stripping process. The in-situ integration of inorganic particles and polymer matrix enable the interface to possess a dense morphology, high mechanical rigidity, high lithium ions conductivity and high interface energy, defending the attack of moisture and O2− and furthermore keeping a homogeneous Li+ deposition even at high local current density. As a result, an outstanding improvement on the reversibility of Li–air battery is achieved with 180 cycles at a high current density of 1000 ​mA ​g−1 and capacity control of 1000 ​mAh g−1 in air atmosphere (O2:N2:H2O ​= ​4:16:3).

Promoting the reversible structural transformation and carrier migration dynamics simultaneously in a multiple ion-involved process is vital for sulfide electrode materials. Herein, TiS2 with a sulfide cluster vacancy (CV–TiS2−x) has been calculated and prepared to explore a novel strategy to improve the electrochemistry reversibility of sulfide electrodes. It is found that the cluster vacancy can serve as an effective control factor for the improvement of the Fermi level, and enhances the electrochemical stability of CV–TiS2−x in the liquid organic electrolyte system. Moreover, owing to the plentiful positively charged S-vacancies, the CV–TiS2−x samples exhibit an extended interplanar spacing and retain their structural integrity during the lithium ion insertion process. The integrated HRTEM, in situ XRD, XPS analysis and electrochemical study reveal that the cluster vacancy is not only responsible for an increase in reversible performance, but also boosting the anionic redox reaction of (S2)2− species. Therefore, the CV–TiS2−x electrode delivers a reversible capacity of 650 mA h g−1 for 300 cycles at a current density of 1C (220 mA g−1). Our study provides a novel strategy of introducing sulfur cluster vacancies to improve the electrochemical activity of TiS2, which can be applied to other sulfide electrodes.

Volume changes, polysulfide shuttle effects, and low Li-ion/electronic conductivity of sulfide electrodes limit their application in Li-ion batteries with high-energy density. Here, micron FeS2 particles with bifunctional carbon nanotubes (FeS2@B–CNTs) including CNT internal conductive networks and external protective cages were prepared by a one-step solvothermal method. The internal CNTs anchor FeS2via chemical binding, which much more effectively inhibited the shuttle effect than physical confinement alone. Meanwhile, reticular CNT cages were generated on the surface of the composite FeS2 micron particles, buffering volumetric changes during cycling and further restraining the shuttle of polysulfides. Additionally, a three-dimensional CNT framework offered a primarily continuous charge transfer pathway. The FeS2@B–CNTs electrode had a high initial coulombic efficiency of 91.3% and delivered a capacity of 698 mA h g−1 over 500 cycles at 1000 mA g−1. The Li-ion diffusion coefficient is two orders of magnitude higher than those of previous reports, which improved the rate performance of the FeS2@B–CNTs electrode. These studies on micron FeS2 spheres shed light on the design strategies for the application of sulfide electrodes.

We publish a Chinese Resume Corpus for researches of information extraction. The corpus contains 178 thousand resume documents and over 33 million words. The resume documents with unstructured form contain many types of common information like name, gender, birthday, education, work experience, and so forth. We evaluate this corpus by using four types of mainstream neural network models for demonstrating the potential of our corpus to promote the development of information extraction research.

In order to mitigate the gradual phase transition and improve the structural stability of Li-rich layered cathode materials, an antisite-defect nanolayer (transition metal ions replacing Li+ in Li slab) with a thickness of ~ 2 nm was induced on the surface of Li1.16(Ni0.25Mn0.75)0.84O2 by doping with boracic polyanions in our study. It is found that the 2 mol% and 3 mol% BO33--doping samples show the excellent cycling stability with capacity retention of 91.2% and 93.7% after 300 cycles at 0.5 C. More importantly, the BO33- doping restrains the decay of discharge voltage upon cycling and has the prospect to overcome the fatal drawback of Li-rich layered oxides. The results demonstrate that the BO33- doping contributes to the generation of an antisite-defect nanolayer on the surface, which hinders the formation of the Li-ion vacancies and the continued migration of much more transition metal ions to the Li slab at a deep charging state. The antisite-defect nanolayer obviously improves surface structural stability and also inhibits the appearance of the amorphous domain in the bulk, which are favorable to maintain the facile lithium diffusion pathways during cycling and improve the capacity retention and rate capability.

A low complexity scheme is proposed for direct detection orthogonal frequency division multiple access passive optical network, based on optical single sideband modulation and polarisation multiplexing. By utilising Hermitian symmetry mapping and Hilbert transformation, the hardware requirement is reduced. Theoretical expressions are presented to explain the cross-polarisation interference, and a channel estimation algorithm is proposed for polarisation crosstalk. In addition, system parameters are discussed to optimise the performance of the proposed scheme. Copyright © 2013 John Wiley & Sons, Ltd.