Transition metal oxides for high performance sodium ion battery anodes

Sodium-ion batteries (SIBs) are attracting considerable attention with expectation of replacing lithium-ion batteries (LIBs) in large-scale energy storage systems (ESSs). To explore high performance anode materials for SIBs is highly desired subject to the current anode research mainly limited to carbonaceous materials. In this study, a series of transition metal oxides (TMOs) is successfully demonstrated as anodes for SIBs for the first time. The sodium uptake/extract is confirmed in the way of reversible conversion reaction. The pseudocapacitance-type behavior is also observed in the contribution of sodium capacity. For Fe2O3anode, a reversible capacity of 386 mAh g-1at 100 mA g-1 is achieved over 200 cycles; as high as 233 mAhg-1is sustained even cycling at a large current-density of 5 A g-1

The Empirical Study on relationship among Ethical Institution, Corporate Social Performance and Corporate Performance

The role of ethical system building in corporate competitiveness promoting is an important issue of corporate social responsibility research. This paper discussed the intermediary function of corporate social responsibility behavior between ethical system and corporate performance, through theoretical analysis and empirical test. The object of our research was enterprise senior managers in China. We recovered 167 valid questionnaires. The result indicates that ethical system does not have positive effect on corporate performance directly, but CSR behavior both obvious positively associates with ethical system and corporate performance. The CSR behavior is a mediating variable between ethical system and corporate performance. This research is an important part of CSR research, it strengths the importance of ethical system building

Strong Attractor of Beam Equation with Structural Damping and Nonlinear Damping

This paper is mainly concerned with the existence of a global strong attractor for the nonlinear extensible beam equation with structural damping and nonlinear external damping. This kind of problem arises from the model of an extensible vibration beam. By the asymptotic compactness of the related continuous semigroup, we prove the existence of a strong global attractor which is connected with phase space D(Δ2)×H01(Ω)∩H2(Ω)

Engineering hierarchical hollow nickel sulfide spheres for high-performance sodium storage

Sodium-ion batteries (SIBs) are considered as promising alternatives to lithium-ion batteries (LIBs) for energy storage due to the abundance of sodium, especially for grid distribution systems. The practical implementation of SIBs, however, is severely hindered by their low energy density and poor cycling stability due to the poor electrochemical performance of the existing electrodes. Here, to achieve high-capacity and durable sodium storage with good rate capability, hierarchical hollow NiS spheres with porous shells composed of nanoparticles are designed and synthesized by tuning the reaction parameters. The formation mechanism of this unique structure is systematically investigated, which is clearly revealed to be Ostwald ripening mechanism on the basis of the time-dependent morphology evolution. The hierarchical hollow structure provides sufficient electrode/electrolyte contact, shortened Na+ diffusion pathways, and high strain-tolerance capability. The hollow NiS spheres deliver high reversible capacity (683.8 mAh g−1 at 0.1 A g−1), excellent rate capability (337.4 mAh g−1 at 5 A g−1), and good cycling stability (499.9 mAh g−1 with 73% retention after 50 cycles at 0.1 A g−1)

Pullback D-Attractor of Coupled Rod Equations with Nonlinear Moving Heat Source

We consider the pullback D-attractor for the nonautonomous nonlinear equations of thermoelastic coupled rod with a nonlinear moving heat source. By Galerkin method, the existence and uniqueness of global solutions are proved under homogeneous boundary conditions and initial conditions. By prior estimates combined with some inequality skills, the existence of the pullback D-absorbing set is obtained. By proving the properties of compactness about the nonlinear operator g1(·), g2(·), and then proving the pullback D-condition (C), the existence of the pullback D-attractor of the equations previously mentioned is given

Attractor of Beam Equation with Structural Damping under Nonlinear Boundary Conditions

Simultaneously, considering the viscous effect of material, damping of medium, and rotational inertia, we study a kind of more general Kirchhoff-type extensible beam equation utt-uxxtt+uxxxx-σ(∫0l‍(ux)2dx)uxx-ϕ(∫0l‍(ux)2dx)uxxt=q(x), in  [0,L]×R+ with the structural damping and the rotational inertia term. Little attention is paid to the longtime behavior of the beam equation under nonlinear boundary conditions. In this paper, under nonlinear boundary conditions, we prove not only the existence and uniqueness of global solutions by prior estimates combined with some inequality skills, but also the existence of a global attractor by the existence of an absorbing set and asymptotic compactness of corresponding solution semigroup. In addition, the same results also can be proved under the other nonlinear boundary conditions

Enhanced Electrocatalytic Performance of Co3O4/Ketjen-Black Cathodes for Li-O2 Batteries

A series of Co3O4/Ketjen Black cathodes are fabricated by electrostatic spray deposition technique for Li-O2 batteries. A sluggish kinetics of oxygen reduction reaction and oxygen evolution reaction processes is noted either when Co3O4 is lacked or Ketjen Black is insufficient, which leads to much higher overpotentials between charge and discharge profiles. By contrast, with the optimal design in terms of electric conduction and catalytic activity, the Co3O4/Ketjen Black (80 wt%) composite achieves enhanced electrochemical performance with an initial discharge capacity of 2044 mAh g-1 and maintaining 33 cycles at a fixed capacity of 500 mAh g-1. The electrochemical characterization indicates that the improved Li-O2 battery performance may benefit from the highest oxygen reduction reaction and oxygen evolution reaction activity under this electro-chemically optimized composite. This work may shed light on the design principle of future cathode materials for Li-O2 batteries

Readily Exfoliated TiSe2 Nanosheets for High-Performance Sodium Storage

Materials with sheet-like morphologies are highly desirable candidates for energy storage and conversion applications, due to the confined atomic thickness and high surface area, which would largely improve the electrochemical reaction kinetics. In this work, the sodium storage performance of TiSe 2 nanosheets and corresponding sodiation/desodiation reaction mechanism are studied for the first time. TiSe 2 nanosheets are readily exfoliated from bulk TiSe 2 after quick ultrasonication or grinding. The TiSe 2 nanosheets exhibit a reversible capacity of 147mAhg -1 at 0.1Ag -1 , and show excellent rate capability with a capacity of 103mAhg -1 at an ultra-high current density of 10.0Ag -1 . The combined in situ XRD and ex-situ HRTEM results suggest that sodium storage in TiSe 2 is achieved through a multi-step intercalation/deintercalation mechanism. Besides, TiSe 2 might be a promising 2D nanomaterial platform for other energy and electronic applications due to its easy exfoliation and unique physicochemical properties